add mini_fo fix from #1801

[oweals/openwrt.git] / target / linux / generic-2.6 / patches-2.6.22 / 209-mini_fo.patch

diff -urN linux-2.6.21.1.old/fs/Kconfig linux-2.6.21.1.dev/fs/Kconfig
--- linux-2.6.21.1.old/fs/Kconfig       2007-05-26 19:03:45.497714200 +0200
+++ linux-2.6.21.1.dev/fs/Kconfig       2007-05-26 21:01:26.154331240 +0200
@@ -461,6 +461,9 @@
          This option will enlarge your kernel, but it allows debugging of
          ocfs2 filesystem issues.
 
+config MINI_FO
+       tristate "Mini fanout overlay filesystem"
+
 config MINIX_FS
        tristate "Minix fs support"
        help
diff -urN linux-2.6.21.1.old/fs/Makefile linux-2.6.21.1.dev/fs/Makefile
--- linux-2.6.21.1.old/fs/Makefile      2007-05-26 19:03:45.497714200 +0200
+++ linux-2.6.21.1.dev/fs/Makefile      2007-05-26 21:01:26.160330328 +0200
@@ -76,6 +76,7 @@
 obj-$(CONFIG_RAMFS)            += ramfs/
 obj-$(CONFIG_HUGETLBFS)                += hugetlbfs/
 obj-$(CONFIG_CODA_FS)          += coda/
+obj-$(CONFIG_MINI_FO)          += mini_fo/
 obj-$(CONFIG_MINIX_FS)         += minix/
 obj-$(CONFIG_FAT_FS)           += fat/
 obj-$(CONFIG_MSDOS_FS)         += msdos/
diff -urN linux-2.6.21.1.old/fs/mini_fo/aux.c linux-2.6.21.1.dev/fs/mini_fo/aux.c
--- linux-2.6.21.1.old/fs/mini_fo/aux.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/aux.c 2007-05-26 21:01:26.160330328 +0200
@@ -0,0 +1,580 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "fist.h"
+#include "mini_fo.h"
+
+/* check if file exists in storage  */
+int exists_in_storage(dentry_t *dentry)
+{
+       check_mini_fo_dentry(dentry);
+       if(dtost(dentry) == MODIFIED || dtost(dentry) == CREATED || dtost(dentry) == DEL_REWRITTEN)
+               return 1;
+       return 0;       
+}
+
+/* check if dentry is in an existing state */
+int is_mini_fo_existant(dentry_t *dentry) 
+{
+       check_mini_fo_dentry(dentry);
+
+       if(dtost(dentry) == DELETED || dtost(dentry) == NON_EXISTANT)
+               return 0;
+       else
+               return 1;
+}
+
+/* 
+ * This function will create a negative storage dentry for 
+ * dentry, what is required for many create like options.
+ * It will create the storage structure if necessary.
+ */
+int get_neg_sto_dentry(dentry_t *dentry) 
+{
+       int err = 0;
+       unsigned int len;
+       const unsigned char *name;
+
+       if(!dentry ||
+          !dtopd(dentry) ||
+          !(dtost(dentry) == UNMODIFIED ||
+            dtost(dentry) == NON_EXISTANT ||
+            dtost(dentry) == DELETED)) {
+               printk(KERN_CRIT "mini_fo: get_neg_sto_dentry: invalid dentry passed.\n");
+               err = -1;
+               goto out;
+       }
+       /* Have we got a neg. dentry already? */
+       if(dtohd2(dentry)) {
+               err = 0;
+               goto out;
+       }
+       if(dtost(dentry->d_parent) == UNMODIFIED) {
+               /* build sto struct */
+               err = build_sto_structure(dentry->d_parent->d_parent, dentry->d_parent);
+               if(err || 
+                  dtost(dentry->d_parent) != MODIFIED) {
+                       printk(KERN_CRIT "mini_fo: get_neg_sto_dentry: ERROR building sto structure.\n");
+                       err = -1;
+                       goto out;
+               }               
+       }
+
+       len = dentry->d_name.len;
+       name = dentry->d_name.name;
+        
+       dtohd2(dentry) = 
+               lookup_one_len(name, dtohd2(dentry->d_parent), len);
+
+ out:
+       return err;
+}
+
+int check_mini_fo_dentry(dentry_t *dentry)
+{
+       ASSERT(dentry != NULL);
+       ASSERT(dtopd(dentry) != NULL);
+       ASSERT((dtohd(dentry) != NULL) || (dtohd2(dentry) != NULL));
+              
+/*     if(dtost(dentry) == MODIFIED) { */
+/*             ASSERT(dentry->d_inode != NULL); */
+/*             ASSERT(dtohd(dentry) != NULL); */
+/*             ASSERT(dtohd(dentry)->d_inode != NULL); */
+/*             ASSERT(dtohd2(dentry) != NULL); */
+/*             ASSERT(dtohd2(dentry)->d_inode != NULL); */
+/*     } */
+/*     else if(dtost(dentry) == UNMODIFIED) { */
+/*             ASSERT(dentry->d_inode != NULL); */
+/*             ASSERT( */
+/*     } */
+       return 0;              
+}
+
+int check_mini_fo_file(file_t *file)
+{
+       ASSERT(file != NULL);
+       ASSERT(ftopd(file) != NULL);
+       ASSERT(file->f_dentry != NULL);
+       
+       /* violent checking, check depending of state and type 
+        *      if(S_ISDIR(file->f_dentry->d_inode->i_mode)) {}
+        */
+       ASSERT((ftohf(file) != NULL) || (ftohf2(file) != NULL));
+       return 0;
+}
+
+int check_mini_fo_inode(inode_t *inode)
+{
+       ASSERT(inode != NULL);
+       ASSERT(itopd(inode) != NULL);
+       ASSERT((itohi(inode) != NULL) || (itohi2(inode) != NULL));
+       return 0;
+}
+
+/* 
+ * will walk a base path as provided by get_mini_fo_bpath and return
+ * the (hopefully ;-) ) positive dentry of the renamed base dir.
+ *
+ * This does some work of path_init.
+ */
+dentry_t *bpath_walk(super_block_t *sb, char *bpath) 
+{
+       int err;
+       struct nameidata nd;
+
+       /* be paranoid */
+       if(!bpath || bpath[0] != '/') {
+               printk(KERN_CRIT "mini_fo: bpath_walk: Invalid string.\n");
+               return NULL;
+       }
+       if(!sb || !stopd(sb)) {
+               printk(KERN_CRIT "mini_fo: bpath_walk: Invalid sb.\n");
+               return NULL;
+       }
+       
+       /* setup nd as path_init does */
+       nd.last_type = LAST_ROOT; /* if there are only slashes... */
+       nd.flags = LOOKUP_FOLLOW;
+       /* fix this: how do I reach this lock? 
+        * read_lock(&current->fs->lock); */
+       nd.mnt = mntget(stopd(sb)->hidden_mnt);
+       nd.dentry = dget(stopd(sb)->base_dir_dentry);
+       /* read_unlock(&current->fs->lock); */
+       
+       err = path_walk(bpath+1, &nd);
+
+       /* validate */
+       if (err || !nd.dentry || !nd.dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: bpath_walk: path_walk failed.\n");
+               return NULL;
+       }
+       return nd.dentry;
+}
+
+
+/* returns the full path of the basefile incl. its name */
+int get_mini_fo_bpath(dentry_t *dentry, char **bpath, int *bpath_len)
+{
+       char *buf_walker;
+       int len = 0;
+       dentry_t *sky_walker;
+       
+       if(!dentry || !dtohd(dentry)) {
+               printk(KERN_CRIT "mini_fo: get_mini_fo_bpath: invalid dentry passed.\n");
+               return -1;
+       }
+       sky_walker = dtohd(dentry);
+
+       do {
+               len += sky_walker->d_name.len + 1 ; /* 1 for '/' */
+               sky_walker = sky_walker->d_parent;
+       } while(sky_walker != stopd(dentry->d_inode->i_sb)->base_dir_dentry);
+
+       /* 1 to oil the loop */
+       *bpath = (char*)  kmalloc(len + 1, GFP_KERNEL);
+       if(!*bpath) {
+               printk(KERN_CRIT "mini_fo: get_mini_fo_bpath: out of mem.\n");
+               return -1;
+       }
+       buf_walker = *bpath+len; /* put it on last char */
+       *buf_walker = '\n';
+       sky_walker = dtohd(dentry);
+       
+       do {
+               buf_walker -= sky_walker->d_name.len;
+               strncpy(buf_walker, 
+                       sky_walker->d_name.name, 
+                       sky_walker->d_name.len);
+               *(--buf_walker) = '/';
+               sky_walker = sky_walker->d_parent;
+       } while(sky_walker != stopd(dentry->d_inode->i_sb)->base_dir_dentry);
+
+       /* bpath_len doesn't count newline! */
+       *bpath_len = len;
+       return 0;
+}
+
+int mini_fo_cp_cont(dentry_t *tgt_dentry, struct vfsmount *tgt_mnt,
+                   dentry_t *src_dentry, struct vfsmount *src_mnt)
+{
+       void *buf;
+       mm_segment_t old_fs;
+       file_t *tgt_file;
+       file_t *src_file;
+       int bytes, len, tmp, err;
+       err = 0;
+
+       if(!(tgt_dentry->d_inode && src_dentry->d_inode)) {
+               printk(KERN_CRIT "mini_fo_cp_cont: ERROR, neg. dentry passed.\n");
+               err = -EINVAL;
+               goto out;
+       }
+
+       dget(tgt_dentry);
+       dget(src_dentry);
+       mntget(tgt_mnt);
+       mntget(src_mnt);
+
+       /* open file write only */
+       tgt_file = dentry_open(tgt_dentry, tgt_mnt, 0x1);
+       if(!tgt_file || IS_ERR(tgt_file)) {
+               printk(KERN_CRIT "mini_fo_cp_cont: ERROR opening target file.\n");
+               err = PTR_ERR(tgt_file);
+               goto out_err;
+       }
+
+       /* open file read only */
+       src_file = dentry_open(src_dentry, src_mnt, 0x0);
+       if(!src_file || IS_ERR(src_file)) {
+               printk(KERN_CRIT "mini_fo_cp_cont: ERROR opening source file.\n");
+               err = PTR_ERR(src_file);
+
+               /* close target file */
+               fput(tgt_file);
+               goto out_err;
+       }
+
+       /* check if the filesystem(s) support read respective write */
+       if(!src_file->f_op->read || !tgt_file->f_op->write) {
+               printk(KERN_CRIT "mini_fo_cp_cont: ERROR, no fs read or write support.\n");
+               err = -EPERM;
+               goto out_close;
+       }
+
+       /* allocate a page for transfering the data */
+       buf = (void *) __get_free_page(GFP_KERNEL);
+       if(!buf) {
+               printk(KERN_CRIT "mini_fo_cp_cont: ERROR, out of kernel mem.\n");
+               goto out_err;
+       }
+
+       tgt_file->f_pos = 0;
+       src_file->f_pos = 0;
+
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+
+       /* Doing this I assume that a read operation will return a full
+        * buffer while there is still data to read, and a less than
+        * full buffer when all data has been read.
+        */
+       bytes = len = PAGE_SIZE;
+       while(bytes == len) {
+               bytes = src_file->f_op->read(src_file, buf, len, 
+                                            &src_file->f_pos);
+               tmp = tgt_file->f_op->write(tgt_file, buf, bytes, 
+                                           &tgt_file->f_pos);
+               if(tmp != bytes) {
+                       printk(KERN_CRIT "mini_fo_cp_cont: ERROR writing.\n");
+                       goto out_close_unset;
+               }
+       }
+
+       free_page((unsigned long) buf);
+       set_fs(old_fs);
+       fput(tgt_file);
+       fput(src_file);
+       goto out;
+
+ out_close_unset:
+       free_page((unsigned long) buf);
+       set_fs(old_fs);
+
+ out_close:
+       fput(tgt_file);
+       fput(src_file);
+
+ out_err:
+       dput(tgt_dentry);
+       dput(src_dentry);
+
+       /* mk: not sure if this need to be done */
+       mntput(tgt_mnt);
+       mntput(src_mnt);
+
+ out:
+       return err;
+}
+
+/* mk:
+ * ndl (no-duplicate list) stuff
+ * This is used in mini_fo_readdir, to save the storage directory contents
+ * and later when reading base, match them against the list in order
+ * to avoid duplicates.
+ */
+
+/* add a file specified by name and len to the ndl
+ * Return values: 0 on success, <0 on failure.
+ */
+int ndl_add_entry(struct readdir_data *rd, const char *name, int len)
+{
+       struct ndl_entry *tmp_entry;
+
+       tmp_entry = (struct ndl_entry *) 
+               kmalloc(sizeof(struct ndl_entry), GFP_KERNEL);
+       if(!tmp_entry) {
+                printk(KERN_CRIT "mini_fo: ndl_add_entry: out of mem.\n");
+                return -ENOMEM;
+        }
+        tmp_entry->name = (char*) kmalloc(len, GFP_KERNEL);
+        if(!tmp_entry->name) {
+                printk(KERN_CRIT "mini_fo: ndl_add_entry: out of mem.\n");
+                return -ENOMEM;
+        }
+       strncpy(tmp_entry->name, name, len);
+        tmp_entry->len = len;
+
+        list_add(&tmp_entry->list, &rd->ndl_list);
+        rd->ndl_size++;
+        return 0;
+}
+
+/* delete all list entries and free memory */
+void ndl_put_list(struct readdir_data *rd)
+{
+       struct list_head *tmp;
+       struct ndl_entry *tmp_entry;
+
+       if(rd->ndl_size <= 0)
+               return;
+       while(!list_empty(&rd->ndl_list)) {
+               tmp = rd->ndl_list.next;
+                list_del(tmp);
+                tmp_entry = list_entry(tmp, struct ndl_entry, list);
+               kfree(tmp_entry->name);
+                kfree(tmp_entry);
+        }
+       rd->ndl_size = 0;
+}
+
+/* Check if a file specified by name and len is in the ndl
+ * Return value: 0 if not in list, 1 if file is found in ndl.
+ */
+int ndl_check_entry(struct readdir_data *rd, const char *name, int len)
+{
+       struct list_head *tmp;
+       struct ndl_entry *tmp_entry;
+
+       if(rd->ndl_size <= 0)
+               return 0;
+
+       list_for_each(tmp, &rd->ndl_list) {
+                tmp_entry = list_entry(tmp, struct ndl_entry, list);
+                if(tmp_entry->len != len)
+                        continue;
+                if(!strncmp(tmp_entry->name, name, len))
+                        return 1;
+        }
+        return 0;
+}
+
+/* mk:
+ * Recursive function to create corresponding directorys in the storage fs.
+ * The function will build the storage directorys up to dentry.
+ */
+int build_sto_structure(dentry_t *dir, dentry_t *dentry)
+{
+       int err;
+       dentry_t *hidden_sto_dentry;
+       dentry_t *hidden_sto_dir_dentry;
+
+       if(dentry->d_parent != dir) {
+               printk(KERN_CRIT "mini_fo: build_sto_structure: invalid parameter or meta data corruption [1].\n");
+               return 1;
+       }
+
+               if(dtost(dir) != MODIFIED) {
+               err = build_sto_structure(dir->d_parent, dentry->d_parent);
+               if(err)
+                       return err;
+       }
+
+       /* ok, coming back again. */
+       check_mini_fo_dentry(dentry);
+       hidden_sto_dentry = dtohd2(dentry);
+
+       if(!hidden_sto_dentry) {
+               /*
+                * This is the case after creating the first 
+                * hidden_sto_dentry.
+                * After one negative storage_dentry, all pointers to 
+                * hidden_storage dentries are set to NULL. We need to
+                * create the negative dentry before we create the storage
+                * file.
+                */
+               unsigned int len;
+               const unsigned char *name;
+               len = dtohd(dentry)->d_name.len;
+               name = dtohd(dentry)->d_name.name;
+               hidden_sto_dentry = lookup_one_len(name, dtohd2(dir), len);
+               dtohd2(dentry) = hidden_sto_dentry;
+       }
+
+       /* was: hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry); */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       /* lets be safe */
+       if(dtohd2(dir) != hidden_sto_dir_dentry) {
+               printk(KERN_CRIT "mini_fo: build_sto_structure: invalid parameter or meta data corruption [2].\n");
+               return 1;
+       }
+
+       /* check for errors in lock_parent */
+       err = PTR_ERR(hidden_sto_dir_dentry);
+       if(IS_ERR(hidden_sto_dir_dentry)) {
+               printk(KERN_CRIT "mini_fo: build_sto_structure: lock_parent failed.\n");
+               return err;
+       }
+
+       err = vfs_mkdir(hidden_sto_dir_dentry->d_inode,
+                       hidden_sto_dentry,
+                       dir->d_inode->i_mode);
+
+       if(err) {
+               printk(KERN_CRIT "mini_fo: build_sto_structure: failed to create storage dir [1].\n");
+               /* was: unlock_dir(dir); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&dir->d_inode->i_mutex);
+#else
+               up(&dir->d_inode->i_sem);
+#endif
+               dput(dir);
+               return err;
+       }
+       
+       /* everything ok! */
+       if(!dtohd2(dentry)->d_inode) {
+               printk(KERN_CRIT "mini_fo: build_sto_structure: failed to create storage dir [2].\n");
+               /* was: unlock_dir(dir); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&dir->d_inode->i_mutex);
+#else
+               up(&dir->d_inode->i_sem);
+#endif
+               dput(dir);
+               return 1;
+       }
+
+       /* interpose the new inode and set new state */
+       itohi2(dentry->d_inode) = igrab(dtohd2(dentry)->d_inode);
+       dtopd(dentry)->state = MODIFIED;
+
+       /* initalize the wol list */
+       itopd(dentry->d_inode)->deleted_list_size = -1;
+       itopd(dentry->d_inode)->renamed_list_size = -1;
+       meta_build_lists(dentry);
+       
+       fist_copy_attr_all(dentry->d_inode, itohi2(dentry->d_inode));
+       fist_copy_attr_timesizes(dir->d_inode, 
+                                hidden_sto_dir_dentry->d_inode);
+       dir->d_inode->i_nlink++;
+       /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_sto_dir_dentry);
+       return 0;
+}
+
+
+#if 0 /* unused */
+
+/*
+ * Read "len" bytes from "filename" into "buf".
+ * "buf" is in kernel space.
+ */
+int
+mini_fo_read_file(const char *filename, void *buf, int len)
+{
+    file_t *filp;
+    mm_segment_t oldfs;
+    int bytes;
+    /* Chroot? Maybe NULL isn't right here */
+    filp = filp_open(filename, O_RDONLY, 0);
+    if (!filp || IS_ERR(filp)) {
+       printk("mini_fo_read_file err %d\n", (int) PTR_ERR(filp));
+       return -1;  /* or do something else */
+    }
+
+    if (!filp->f_op->read)
+       return -2;  /* file(system) doesn't allow reads */
+
+    /* now read len bytes from offset 0 */
+    filp->f_pos = 0;           /* start offset */
+    oldfs = get_fs();
+    set_fs(KERNEL_DS);
+    bytes = filp->f_op->read(filp, buf, len, &filp->f_pos);
+    set_fs(oldfs);
+
+    /* close the file */
+    fput(filp);
+
+    return bytes;
+}
+
+
+
+/*
+ * Write "len" bytes from "buf" to "filename"
+ * "buf" is in kernel space.
+ */
+int
+mini_fo_write_file(const char *filename, void *buf, int len)
+{
+    file_t *filp;
+    mm_segment_t oldfs;
+    int bytes;
+                               /* Chroot? Maybe NULL isn't right here */
+    filp = filp_open(filename, O_RDWR|O_CREAT, 0640);
+    if (!filp || IS_ERR(filp)) {
+       printk("mini_fo_write_file err %d\n", (int) PTR_ERR(filp));
+       return -1;  /* or do something else */
+    }
+
+    if (!filp->f_op->write)
+       return -2;  /* file(system) doesn't allow writes */
+
+    /* now write len bytes from offset 0 */
+    filp->f_pos = 0;           /* start offset */
+    oldfs = get_fs();
+    set_fs(KERNEL_DS);
+    bytes = filp->f_op->write(filp, buf, len, &filp->f_pos);
+    set_fs(oldfs);
+
+    /* close the file */
+    fput(filp);
+
+    return bytes;
+}
+
+#endif /* unused */
+
diff -urN linux-2.6.21.1.old/fs/mini_fo/ChangeLog linux-2.6.21.1.dev/fs/mini_fo/ChangeLog
--- linux-2.6.21.1.old/fs/mini_fo/ChangeLog     1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/ChangeLog     2007-05-26 21:01:26.161330176 +0200
@@ -0,0 +1,281 @@
+2006-01-24  Markus Klotzbuecher  <mk@mary.denx.de>
+
+       * Add tons of ugly ifdefs to Ed L. Cashin's mutex patch to
+          retain backwards compatibility.
+       
+2006-01-24  Ed L. Cashin <ecashin@coraid.com>
+
+       * Support for the new mutex infrastructure
+       (7892f2f48d165a34b0b8130c8a195dfd807b8cb6)
+
+2005-10-15  Markus Klotzbuecher  <mk@localhost.localdomain>
+
+       * Bugfix for a serious memory leak in mini_fo_follow_link.
+
+2005-09-21  Markus Klotzbuecher  <mk@mary>
+
+       * new release 0.6.1
+
+       * fix of a compiler warning due to changes in 2.6.13
+
+2005-09-21  Klaus Wenninger  <klaus.wenninger@siemens.com>
+
+       * file.c: readdir: fix for a bug that caused directory entries
+          to show up twice when using storage filesystems such as
+          minixfs or pramfs.
+
+2005-06-30  Eric Lammerts <eric@lammerts.org>
+
+       * fix for an oops when overwriting a binary thats beeing
+          executed.
+
+2005-06-09    <mk@mary>
+
+       * Renamed overlay to mini_fo-overlay.
+
+       * Added mini_fo-merge script to allow merging of storage and base
+       after making modifications.
+
+2005-05-22  root  <mk@mary>
+
+       * Added overlay script that allows to easily mount mini_fo ontop
+       of a given base directory
+
+2005-05-10    <mk@mary>
+
+       * inode.c: xattr functions return -EOPNOSUPP instead of
+          -ENOSUPP, what confuses "ls -l"
+
+       * Changed license from LGPL to GPL.
+
+2005-05-08  root  <mk@mary>
+
+       * Makefile: clean it up and added make install and make
+          uninstall.
+       
+2005-05-06    <mk@mary>
+
+       * merged devel branch back to main. [v0-6-0-pre3]
+
+       * removed unused files print.c and fist_ioctl. [devel-0-0-18]
+
+       * ioctl: removed fist_ioctl stuff, that is not needed for
+          now.
+
+2005-05-03    <mk@mary>
+
+       * file.c: simplified mini_fo_open and mini_fo_setattr using
+          new state changing functions. [devel-0-0-17]
+
+       * inode.c: Fixed getattr state bug (see below) in 2.4 function
+          mini_fo_inode revalidate.
+
+       * inode.c: found an other bug in mini_fo_getattr. States are not
+         reliable in this function, as a file can be opened, unlinked and
+         the getattr function called. This results in a deleted dentry
+         with an inode. Fix is to ignore states and simply use the inode
+         available.
+
+2005-04-29    <mk@mary>
+
+       * file.c: Bugfix and cleanup in fasync and fsync. [devel-0-0-16]
+
+       * file.c: do not use mini_fo_lock so the generic version is
+          used (I guess).
+
+       * inode.c: getattr, never call getattr on lower files, as this
+          will cause the inum to change.
+
+       * inode.c: rename_reg_file renamed to rename_nondir, as it
+          doesn't matter as long it't not a dir. Removed all
+          rename_dev_file etc.           
+
+       * tagged as devel-0-0-15
+
+       * inode.c: added support for chosing support for extended
+          attrs at compile time by XATTR define in mini_fo.h .
+
+       * inode.c: fixed mini_fo_getattr to use mini_fo inode and not
+          lower again, what avoids inode number changes that confused
+          rm again. This is the proper solution.
+
+2005-04-24    <mk@mary>
+
+       * all files: updated Copyright notive to 2005. [devel-0-0-14]
+
+       * inode.c: fixed mini_fo_getattr to not change the inode
+          number, even if lower files change.
+
+       * super.c: fixed a bug that caused deleted base file to show
+          up suddenly after some time, or after creating a special
+          file. The problem was that after some time or after special
+          file creating sync_sb_inodes is called by the vfs, that
+          called our mini_fo_put_inode. There was (wrongly) called
+          __meta_put_lists, that nuked the lists, although the inode
+          was going to continue its life. Moving __meta_put_lists to
+          mini_fo_clear_inode, where an inode is really destroyed,
+          solved the problem.
+
+
+2005-04-23    <mk@mary>
+
+       * state.c, aux.c: more cleaning up and
+          simplifications. [devel-0-0-13] 
+
+       * inode.c: implemented mini_fo_getattr, that was required for
+          2.6 because inode_revalidate has been remove there, and the
+         old "du" bug returned.
+
+
+2005-04-20    <mk@mary>
+
+       * aux.c: get_neg_sto_dentry(): allow to be called for dentries
+          in state UNMODIFIED, NON_EXISTANT _and_ DELETED.
+
+2005-04-19    <mk@mary>
+
+       * Fixed a bug under 2.6 that caused files deleted via mini_fo
+          not to be deleted properly and therefore the fs filled up
+          untill no memory was left. [devel-0-0-12]
+
+       * Added basic hard link support. This means that creating
+          hardlinks will work, but existing ones will be treated as
+          individual files. [devel-0-0-11]
+
+2005-04-17    <mk@mary>
+
+       * Bugfixes
+
+2005-04-13  root  <mk@mary>
+
+       * Added file state.c for the state transition
+          functions. Doesn't work very well yet, though...
+
+2005-04-12    <mk@mary>
+
+       * Porting to 2.6 started, which is easier than expected, also
+          due to Olivier previous work.
+
+2005-04-08    <mk@mary>
+
+       * Fixed the bug that caused du to return invalid sizes of
+          directory trees. The problem was that
+          mini_fo_inode_revalidate didn't always copy the attributes
+          from the base inode properly.
+
+2005-04-01  Markus Klotzbuecher  <mk@chasey>
+
+       * Merged devel branch back to main trunk and updated the
+          RELEASE notes. This will be 0-6-0-pre1.
+
+2005-03-31  Markus Klotzbuecher  <mk@chasey>
+
+       * Fixed some bugs in rename_reg_file, that only showed up in
+          the kernel compile test. Kernel compiles cleanly ontop of
+          mini_fo, now also make mrproper etc. work. Seems pretty stable.
+
+2005-03-28  Markus Klotzbuecher  <mk@chasey>
+
+       * Many, many directory renaming bugfixes and a lot of other
+          cleanup. Dir renaming seems to work relatively stable.
+
+2005-03-22  Markus Klotzbuecher  <mk@chasey>
+
+       * Finished implementing lightweight directory renaming. Some
+          basic testing indicates it works fine.
+         Next is to implement testcases for the testsuite and confirm
+          everything is really working ok.
+
+2005-03-18  Markus Klotzbuecher  <mk@chasey>
+
+       * Finished implementing meta.c stuff required for directory
+          renaming.
+
+2005-03-17  Markus Klotzbuecher  <mk@chasey>
+
+       * Fixed all compile warnings + an extremly old bug that
+          somehow crept in while reworking the wol stuff to the META
+          system. Turning on -Werror again... :-)
+
+       * Fixed some bugs in the new rename_reg_file function.
+
+       * Rewrote mini_fo rename and split it into several
+          subfunctions, that handle the different types
+          seperately. Rewrote the regular file function aswell, as it
+          was implemented somewhat inefficient. 
+
+2005-03-16  Markus Klotzbuecher  <mk@chasey>
+
+       * Implemented new META subsystem, removed old WOL stuff in favor 
+         if it.
+
+       * After some basic testing everything seems ok...
+
+2005-03-11  Markus Klotzbuecher  <mk@chasey>
+
+       * Renaming a non regular file caused trouble because I always
+         tried to copy the contents. Now I only do this for regular
+         files. mini_fo_rename still isn't implemented properly, renaming
+         of device files, symlinks etc. results in a empty regular file
+         instead of the proper type.
+       
+       * Directory renaming suddenly works! What a surprise! I guess
+          this is because renaming is implemented as making a copy and
+          removing the original. Still this might not work
+          everywhere...
+
+2005-03-09  Markus Klotzbuecher  <mk@chasey>
+
+       * Bugfix, when a mini_fo directory that exists in storage
+         (state: MODIFIED, CREATED and DEL_REWRITTEN) is deleted, a
+         possibly existing WOL file contained in it needs to be
+         deleted too.
+
+       * Starting cleanup: defined state names in order to get rid of
+          the state numbers.
+
+2005-03-08  Markus Klotzbuecher  <mk@chasey>
+       
+       * Makefile fix, fist_ioctl was built against wrong sources if ARCH=um
+
+       * Fixed a bug in dentry.c, mini_fo_d_hash. In state 4 =
+          DEL_REWRITTEN the hash was calculated from the base dentry,
+          which was wrong and and caused assertions in
+          __mini_fo_hidden_dentry to fail.
+
+2005-02-21    <mk@mary>
+
+       * Implemented directory deleting (inode.c)
+
+       * main.c: made mini_fo_parse_options a little more robust.
+
+2004-12-22    <mk@mary>
+
+       * Makefile cleanup and uml stuff, removed unneccessary files
+
+       * Created a new and hopefully more informative README
+
+       * CHANGELOG: created a new CHANGELOG and added old entries reversely
+
+
+2004-10-24 Gleb Natapov <gleb@nbase.co.il>
+
+       * Fix: owner and group where not correctly copied from base to
+          storage. 
+
+
+2004-10-05 Gleb Natapov <gleb@nbase.co.il>
+
+       * Implementation of fsync, fasync and lock mini_fo functions.
+       
+
+2004-09-29 Bob Lee <bob@pantasys.com>
+
+       * Fix of a serious pointer bug
+       
+
+2004-09-28 Gleb Natapov <gleb@nbase.co.il>
+
+       * Implementation of mini_fo_mknod and mini_fo_rename, support
+          for device files.
+       
diff -urN linux-2.6.21.1.old/fs/mini_fo/dentry.c linux-2.6.21.1.dev/fs/mini_fo/dentry.c
--- linux-2.6.21.1.old/fs/mini_fo/dentry.c      1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/dentry.c      2007-05-26 21:01:26.161330176 +0200
@@ -0,0 +1,244 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "fist.h"
+#include "mini_fo.h"
+
+/*
+ * THIS IS A BOOLEAN FUNCTION: returns 1 if valid, 0 otherwise.
+ */
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+mini_fo_d_revalidate(dentry_t *dentry, struct nameidata *nd)
+#else
+mini_fo_d_revalidate(dentry_t *dentry, int flags)
+#endif
+{
+       int err1 = 1; /* valid = 1, invalid = 0 */
+       int err2 = 1;
+       dentry_t *hidden_dentry;
+       dentry_t *hidden_sto_dentry;
+
+
+       check_mini_fo_dentry(dentry);
+
+       hidden_dentry  = dtohd(dentry);
+       hidden_sto_dentry = dtohd2(dentry);
+
+       if(hidden_dentry &&
+          hidden_dentry->d_op &&
+          hidden_dentry->d_op->d_revalidate) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               err1 = hidden_dentry->d_op->d_revalidate(hidden_dentry, nd);
+#else
+               err1 = hidden_dentry->d_op->d_revalidate(hidden_dentry, flags);
+#endif
+       }
+       if(hidden_sto_dentry &&
+          hidden_sto_dentry->d_op &&
+          hidden_sto_dentry->d_op->d_revalidate) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               err2 = hidden_sto_dentry->d_op->d_revalidate(hidden_sto_dentry, 
+                                                            nd);
+#else
+               err2 = hidden_sto_dentry->d_op->d_revalidate(hidden_sto_dentry, 
+                                                            flags);
+#endif
+       }
+
+       /* mk: if one of the lower level dentries are valid,
+        * the mini_fo dentry is too.
+        */
+       return (err1 || err2);
+}
+
+
+STATIC int
+mini_fo_d_hash(dentry_t *dentry, qstr_t *name)
+{
+       int err = 0;
+       dentry_t *hidden_dentry;
+       dentry_t *hidden_sto_dentry;
+
+       /* hidden_dentry = mini_fo_hidden_dentry(dentry);
+        * hidden_sto_dentry = mini_fo_hidden_sto_dentry(dentry); */
+
+       /* state 1, 3, 4, 5: build the hash for the storage dentry */
+       if((dtopd(dentry)->state == MODIFIED) ||
+          (dtopd(dentry)->state == CREATED) ||
+          (dtopd(dentry)->state == DEL_REWRITTEN) ||
+          (dtopd(dentry)->state == DELETED)) {
+               hidden_sto_dentry = dtohd2(dentry);
+               if(hidden_sto_dentry &&
+                  hidden_sto_dentry->d_op &&
+                  hidden_sto_dentry->d_op->d_hash) {
+                       err = hidden_sto_dentry->d_op->d_hash(hidden_sto_dentry, name);
+               }
+               goto out;
+       }
+       /* state 2: build the hash for the base dentry */
+       if(dtopd(dentry)->state == UNMODIFIED) {
+               hidden_dentry = dtohd(dentry);
+               if(hidden_dentry &&
+                  hidden_dentry->d_op &&
+                  hidden_dentry->d_op->d_hash) {
+                       err = hidden_dentry->d_op->d_hash(hidden_dentry, name);
+               }
+               goto out;
+       }
+       /* state 6: build hash for the dentry that exists */
+       if(dtopd(dentry)->state == NON_EXISTANT) {
+               hidden_sto_dentry = dtohd2(dentry);
+               if(hidden_sto_dentry &&
+                  hidden_sto_dentry->d_op &&
+                  hidden_sto_dentry->d_op->d_hash) {
+                       err = hidden_sto_dentry->d_op->d_hash(hidden_sto_dentry, name);
+                       goto out;
+               }
+               hidden_dentry = dtohd(dentry);
+               if(hidden_dentry &&
+                  hidden_dentry->d_op &&
+                  hidden_dentry->d_op->d_hash) {
+                       err = hidden_dentry->d_op->d_hash(hidden_dentry, name);
+                       goto out;
+               }
+       }
+
+       printk(KERN_CRIT "mini_fo: d_hash: invalid state detected.\n");
+
+ out:
+       return err;
+}
+
+
+STATIC int
+mini_fo_d_compare(dentry_t *dentry, qstr_t *a, qstr_t *b)
+{
+       int err;
+       dentry_t *hidden_dentry=NULL;
+
+       /* hidden_dentry = mini_fo_hidden_dentry(dentry); */
+       if(dtohd2(dentry))
+               hidden_dentry = dtohd2(dentry);
+       else if(dtohd(dentry))
+               hidden_dentry = dtohd(dentry);
+
+       if (hidden_dentry && hidden_dentry->d_op && hidden_dentry->d_op->d_compare) {
+               err = hidden_dentry->d_op->d_compare(hidden_dentry, a, b);
+       } else {
+               err = ((a->len != b->len) || memcmp(a->name, b->name, b->len));
+       }
+
+       return err;
+}
+
+
+int
+mini_fo_d_delete(dentry_t *dentry)
+{
+       dentry_t *hidden_dentry;
+       dentry_t *hidden_sto_dentry;
+       int err = 0;
+
+       /* this could be a negative dentry, so check first */
+       if (!dtopd(dentry)) {
+               printk(KERN_CRIT "mini_fo_d_delete: negative dentry passed.\n");
+               goto out;
+       }
+       hidden_dentry = dtohd(dentry);
+       hidden_sto_dentry = dtohd2(dentry);
+
+       if(hidden_dentry) {
+               if(hidden_dentry->d_op &&
+                  hidden_dentry->d_op->d_delete) {
+                       err = hidden_dentry->d_op->d_delete(hidden_dentry);
+               }
+       }
+       if(hidden_sto_dentry) {
+               if(hidden_sto_dentry->d_op &&
+                  hidden_sto_dentry->d_op->d_delete) {
+                       err = hidden_sto_dentry->d_op->d_delete(hidden_sto_dentry);
+               }
+       }
+
+ out:
+       return err;
+}
+
+
+void
+mini_fo_d_release(dentry_t *dentry)
+{
+       dentry_t *hidden_dentry;
+       dentry_t *hidden_sto_dentry;
+
+
+       /* this could be a negative dentry, so check first */
+       if (!dtopd(dentry)) {
+               printk(KERN_CRIT "mini_fo_d_release: no private data.\n");
+               goto out;
+       }
+       hidden_dentry = dtohd(dentry);
+       hidden_sto_dentry = dtohd2(dentry);
+
+       if(hidden_dentry) {
+               /* decrement hidden dentry's counter and free its inode */
+               dput(hidden_dentry);
+       }
+       if(hidden_sto_dentry) {
+                /* decrement hidden dentry's counter and free its inode */
+               dput(hidden_sto_dentry);
+       }
+
+       /* free private data (mini_fo_dentry_info) here */
+       kfree(dtopd(dentry));
+       __dtopd(dentry) = NULL; /* just to be safe */
+ out:
+       return;
+}
+
+
+/*
+ * we don't really need mini_fo_d_iput, because dentry_iput will call iput() if
+ * mini_fo_d_iput is not defined. We left this implemented for ease of
+ * tracing/debugging.
+ */
+void
+mini_fo_d_iput(dentry_t *dentry, inode_t *inode)
+{
+       iput(inode);
+}
+
+
+struct dentry_operations mini_fo_dops = {
+       d_revalidate:   mini_fo_d_revalidate,
+       d_hash:         mini_fo_d_hash,
+       d_compare:              mini_fo_d_compare,
+       d_release:              mini_fo_d_release,
+       d_delete:               mini_fo_d_delete,
+       d_iput:         mini_fo_d_iput,
+};
diff -urN linux-2.6.21.1.old/fs/mini_fo/file.c linux-2.6.21.1.dev/fs/mini_fo/file.c
--- linux-2.6.21.1.old/fs/mini_fo/file.c        1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/file.c        2007-05-26 21:01:26.162330024 +0200
@@ -0,0 +1,713 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "fist.h"
+#include "mini_fo.h"
+#define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
+
+/*******************
+ * File Operations *
+ *******************/
+
+STATIC loff_t
+mini_fo_llseek(file_t *file, loff_t offset, int origin)
+{
+       loff_t err;
+       file_t *hidden_file = NULL;
+
+       if(S_ISDIR(file->f_dentry->d_inode->i_mode)) {
+               /* Check if trying to llseek from a directory */
+               err = -EISDIR;
+               goto out;
+       }
+       if (ftopd(file) != NULL) {
+               if(ftohf2(file)) {
+                       hidden_file = ftohf2(file);
+               } else {
+                       hidden_file = ftohf(file);
+               }
+       }
+
+       /* always set hidden position to this one */
+       hidden_file->f_pos = file->f_pos;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+       memcpy(&(hidden_file->f_ra), 
+              &(file->f_ra), 
+              sizeof(struct file_ra_state));
+#else
+       if (file->f_reada) { /* update readahead information if needed */
+               hidden_file->f_reada = file->f_reada;
+               hidden_file->f_ramax = file->f_ramax;
+               hidden_file->f_raend = file->f_raend;
+               hidden_file->f_ralen = file->f_ralen;
+               hidden_file->f_rawin = file->f_rawin;
+       }
+#endif
+       if (hidden_file->f_op && hidden_file->f_op->llseek)
+               err = hidden_file->f_op->llseek(hidden_file, offset, origin);
+       else
+               err = generic_file_llseek(hidden_file, offset, origin);
+
+       if (err < 0)
+               goto out;
+
+       if (err != file->f_pos) {
+               file->f_pos = err;
+               // ION maybe this?
+               //      file->f_pos = hidden_file->f_pos;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+               file->f_reada = 0;
+#endif
+               file->f_version++;
+       }
+
+ out:
+       return err;
+}
+
+
+/* mk: fanout capable */
+STATIC ssize_t
+mini_fo_read(file_t *file, char *buf, size_t count, loff_t *ppos)
+{
+       int err = -EINVAL;
+       file_t *hidden_file = NULL;
+       loff_t pos = *ppos;
+
+       if(S_ISDIR(file->f_dentry->d_inode->i_mode)) {
+               /* Check if trying to read from a directory */
+               /* printk(KERN_CRIT "mini_fo_read: ERROR: trying to read data from a directory.\n"); */
+               err = -EISDIR;
+               goto out;
+       }
+
+       if (ftopd(file) != NULL) {
+               if(ftohf2(file)) {
+                       hidden_file = ftohf2(file);
+               } else {
+                       hidden_file = ftohf(file);
+               }
+       }
+
+       if (!hidden_file->f_op || !hidden_file->f_op->read)
+               goto out;
+
+       err = hidden_file->f_op->read(hidden_file, buf, count, &pos);
+       *ppos = pos;
+
+       if (err >= 0) {
+               /* atime should also be updated for reads of size zero or more */
+               fist_copy_attr_atime(file->f_dentry->d_inode,
+                                    hidden_file->f_dentry->d_inode);
+       }
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+       /*
+        * MAJOR HACK
+        * because pread() does not have any way to tell us that it is
+        * our caller, then we don't know for sure if we have to update
+        * the file positions.  This hack relies on read() having passed us
+        * the "real" pointer of its struct file's f_pos field.
+        */
+       if (ppos == &file->f_pos)
+               hidden_file->f_pos = *ppos = pos;
+       if (hidden_file->f_reada) { /* update readahead information if needed */
+               file->f_reada = hidden_file->f_reada;
+               file->f_ramax = hidden_file->f_ramax;
+               file->f_raend = hidden_file->f_raend;
+               file->f_ralen = hidden_file->f_ralen;
+               file->f_rawin = hidden_file->f_rawin;
+       }
+#else
+       memcpy(&(file->f_ra),&(hidden_file->f_ra),sizeof(struct file_ra_state));
+#endif
+
+ out:
+       return err;
+}
+
+
+/* this mini_fo_write() does not modify data pages! */
+STATIC ssize_t
+mini_fo_write(file_t *file, const char *buf, size_t count, loff_t *ppos)
+{
+       int err = -EINVAL;
+       file_t *hidden_file = NULL;
+       inode_t *inode;
+       inode_t *hidden_inode;
+       loff_t pos = *ppos;
+
+       /* mk: fan out: */
+       if (ftopd(file) != NULL) {
+               if(ftohf2(file)) {
+                       hidden_file = ftohf2(file);
+               } else {
+                       /* This is bad! We have no storage file to write to. This
+                        * should never happen because if a file is opened for
+                        * writing, a copy should have been made earlier.
+                        */
+                       printk(KERN_CRIT "mini_fo: write : ERROR, no storage file to write.\n");
+                       err = -EINVAL;
+                       goto out;
+               }
+       }
+
+       inode = file->f_dentry->d_inode;
+       hidden_inode = itohi2(inode);
+       if(!hidden_inode) {
+               printk(KERN_CRIT "mini_fo: write: no sto inode found, not good.\n");
+               goto out;
+       }
+
+       if (!hidden_file->f_op || !hidden_file->f_op->write)
+               goto out;
+
+       /* adjust for append -- seek to the end of the file */
+       if (file->f_flags & O_APPEND)
+               pos = inode->i_size;
+
+       err = hidden_file->f_op->write(hidden_file, buf, count, &pos);
+
+       /*
+        * copy ctime and mtime from lower layer attributes
+        * atime is unchanged for both layers
+        */
+       if (err >= 0)
+               fist_copy_attr_times(inode, hidden_inode);
+       
+       *ppos = pos;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+       /*
+        * XXX: MAJOR HACK
+        *
+        * because pwrite() does not have any way to tell us that it is
+        * our caller, then we don't know for sure if we have to update
+        * the file positions.  This hack relies on write() having passed us
+        * the "real" pointer of its struct file's f_pos field.
+        */
+       if (ppos == &file->f_pos)
+               hidden_file->f_pos = *ppos = pos;
+#endif
+       /* update this inode's size */
+       if (pos > inode->i_size)
+               inode->i_size = pos;
+
+ out:
+       return err;
+}
+
+/* Global variable to hold a file_t pointer.
+ * This serves to allow mini_fo_filldir function to know which file is
+ * beeing read, which is required for two reasons:
+ *
+ *   - be able to call wol functions in order to avoid listing deleted
+ *     base files.
+ *   - if we're reading a directory which is in state 1, we need to
+ *     maintain a list (in mini_fo_filldir) of which files allready 
+ *     have been copied to userspace,to detect files existing in base
+ *     and storage and not list them twice.
+ */
+filldir_t mini_fo_filldir_orig;
+file_t *mini_fo_filldir_file;
+
+/* mainly copied from fs/readdir.c */
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+mini_fo_filldir(void * __buf, const char * name, int namlen, loff_t offset,
+                 u64 ino, unsigned int d_type)
+#else
+mini_fo_filldir(void * __buf, const char * name, int namlen, loff_t offset,
+                 ino_t ino, unsigned int d_type)
+#endif
+{
+       struct getdents_callback * buf = (struct getdents_callback *) __buf;
+       file_t* file = mini_fo_filldir_file;
+
+       /* In theses states we filter meta files in storage (WOL) */
+       if(file && (dtopd(file->f_dentry)->state == MODIFIED ||
+                   dtopd(file->f_dentry)->state == CREATED ||
+                   dtopd(file->f_dentry)->state == DEL_REWRITTEN)) {
+
+               int tmp = strlen(META_FILENAME);
+               if(tmp  == namlen) {
+                       if(!strncmp(name, META_FILENAME, namlen))
+                               return 0;
+               }
+       }
+
+       /* check if we are merging the contents of storage and base */
+       if(file && dtopd(file->f_dentry)->state == MODIFIED) {
+               /* check if we are still reading storage contents, if
+                * yes, we just save the name of the file for duplicate
+                * checking later. */
+
+               if(!ftopd(file)->rd.sto_done) {
+                       /* put file into ndl list */
+                       if(ndl_add_entry(&ftopd(file)->rd, name, namlen))
+                               printk(KERN_CRIT "mini_fo_filldir: Error adding to ndl.\n");
+               } else {
+                       /* check if file has been deleted */
+                       if(meta_check_d_entry(file->f_dentry, name, namlen))
+                               return 0;
+                       
+                       /* do duplicate checking */
+                       if(ndl_check_entry(&ftopd(file)->rd, name, namlen))
+                               return 0;
+               }
+       }
+
+       return mini_fo_filldir_orig(buf, name, namlen, offset, ino, d_type);
+}
+
+
+STATIC int
+mini_fo_readdir(file_t *file, void *dirent, filldir_t filldir)
+{
+       int err = 0;/* mk: ??? -ENOTDIR; */
+       file_t *hidden_file = NULL;
+       file_t *hidden_sto_file = NULL;
+       inode_t *inode;
+       struct getdents_callback *buf;
+       int oldcount;
+
+#if defined(FIST_FILTER_NAME) || defined(FIST_FILTER_SCA)
+       struct mini_fo_getdents_callback buf;
+#endif /* FIST_FILTER_NAME || FIST_FILTER_SCA */
+
+       buf = (struct getdents_callback *) dirent;
+       oldcount = buf->count;
+       inode = file->f_dentry->d_inode;
+       mini_fo_filldir_file = file;
+       mini_fo_filldir_orig = filldir;
+
+       ftopd(file)->rd.sto_done = 0;
+       do {
+               if (ftopd(file) != NULL) {
+                       if(ftohf2(file)) { 
+                               hidden_sto_file = ftohf2(file);
+                               err = vfs_readdir(hidden_sto_file, mini_fo_filldir, dirent);
+                               file->f_pos = hidden_sto_file->f_pos;
+                               if (err > 0)
+                                       fist_copy_attr_atime(inode, hidden_sto_file->f_dentry->d_inode);
+                               /* not finshed yet, we'll be called again */
+                               if (buf->count != oldcount)
+                                       break;
+                       }
+
+                       ftopd(file)->rd.sto_done = 1;
+
+                       if(ftohf(file)) { 
+                               hidden_file = ftohf(file);
+                               err = vfs_readdir(hidden_file, mini_fo_filldir, dirent);
+                               file->f_pos = hidden_file->f_pos;
+                               if (err > 0)
+                                       fist_copy_attr_atime(inode, hidden_file->f_dentry->d_inode);
+                       }
+
+               }
+       } while (0);
+
+       /* mk:
+        * we need to check if all the directory data has been copied to userspace,
+        * or if we will be called again by userspace to complete the operation.
+        */
+       if(buf->count == oldcount) {
+               ndl_put_list(&ftopd(file)->rd);
+       }
+
+       /* unset this, safe */
+       mini_fo_filldir_file = NULL;
+       return err;
+}
+
+
+STATIC unsigned int
+mini_fo_poll(file_t *file, poll_table *wait)
+{
+       unsigned int mask = DEFAULT_POLLMASK;
+       file_t *hidden_file = NULL;
+
+       if (ftopd(file) != NULL) {
+               if(ftohf2(file)) {
+                       hidden_file = ftohf2(file);
+               } else {
+                       hidden_file = ftohf(file);
+               }
+       }
+
+       if (!hidden_file->f_op || !hidden_file->f_op->poll)
+               goto out;
+
+       mask = hidden_file->f_op->poll(hidden_file, wait);
+
+ out:
+       return mask;
+}
+
+/* FIST-LITE special version of mmap */
+STATIC int
+mini_fo_mmap(file_t *file, vm_area_t *vma)
+{
+       int err = 0;
+       file_t *hidden_file = NULL;
+
+       /* fanout capability */
+       if (ftopd(file) != NULL) {
+               if(ftohf2(file)) {
+                       hidden_file = ftohf2(file);
+               } else {
+                       hidden_file = ftohf(file);
+               }
+       }
+
+       ASSERT(hidden_file != NULL);
+       ASSERT(hidden_file->f_op != NULL);
+       ASSERT(hidden_file->f_op->mmap != NULL);
+
+       vma->vm_file = hidden_file;
+       err = hidden_file->f_op->mmap(hidden_file, vma);
+       get_file(hidden_file); /* make sure it doesn't get freed on us */
+       fput(file);            /* no need to keep extra ref on ours */
+
+       return err;
+}
+
+
+
+STATIC int
+mini_fo_open(inode_t *inode, file_t *file)
+{
+       int err = 0;
+       int hidden_flags; 
+       file_t *hidden_file = NULL;
+       dentry_t *hidden_dentry = NULL;
+
+       /* fanout stuff */
+       file_t *hidden_sto_file = NULL;
+       dentry_t *hidden_sto_dentry = NULL;
+
+       __ftopd(file) = 
+               kmalloc(sizeof(struct mini_fo_file_info), GFP_KERNEL);
+       if (!ftopd(file)) {
+               err = -ENOMEM;
+               goto out;
+       }
+
+       /* init the readdir_helper structure */
+       INIT_LIST_HEAD(&ftopd(file)->rd.ndl_list);
+       ftopd(file)->rd.ndl_size = 0;
+
+       /* In certain paths this could stay uninitalized and cause trouble */
+       ftohf(file) = NULL;
+       ftohf2(file) = NULL;
+       hidden_flags = file->f_flags;
+
+       /* create storage files? */
+       if(dtost(file->f_dentry) == UNMODIFIED) {
+               if(!IS_WRITE_FLAG(file->f_flags)) {
+                       hidden_dentry = dtohd(file->f_dentry);
+                       dget(hidden_dentry);
+                       /* dentry_open will decrement mnt refcnt if err.
+                        * otherwise fput() will do an mntput() for us upon file close. */
+                       mntget(stopd(inode->i_sb)->hidden_mnt);
+                       hidden_file = dentry_open(hidden_dentry,
+                                                 stopd(inode->i_sb)->hidden_mnt,
+                                                 hidden_flags);
+                       if (IS_ERR(hidden_file)) {
+                               err = PTR_ERR(hidden_file);
+                               dput(hidden_dentry);
+                               goto out;
+                       }
+                       ftohf(file) = hidden_file;      /* link two files */
+                       goto out;
+               }
+               else {
+                       if(S_ISDIR(file->f_dentry->d_inode->i_mode)) {
+                               err = dir_unmod_to_mod(file->f_dentry);
+                       } else
+                               err = nondir_unmod_to_mod(file->f_dentry, 1);
+
+                       if (err) {
+                               printk("mini_fo_open: ERROR creating storage file.\n");
+                               goto out;
+                       }
+               }
+       }
+       hidden_sto_dentry = dtohd2(file->f_dentry);
+       dget(hidden_sto_dentry);
+
+       if(dtopd(file->f_dentry)->state == MODIFIED) {
+               /* Directorys are special, interpose on both lower level files */
+               if(S_ISDIR(itohi(inode)->i_mode)) {
+                       /* check for invalid file types of lower level files */
+                       if(!(S_ISDIR(itohi(inode)->i_mode) && S_ISDIR(itohi2(inode)->i_mode))) {
+                               printk(KERN_CRIT "mini_fo_open: meta data corruption detected.\n");
+                               dput(hidden_sto_dentry);
+                               err = -EINVAL;
+                               goto out;
+                       }
+
+                       /* lower level directorys are ok, open the base file */
+                       hidden_dentry = dtohd(file->f_dentry);
+                       dget(hidden_dentry);
+
+                       mntget(stopd(inode->i_sb)->hidden_mnt);
+                       hidden_file = dentry_open(hidden_dentry,
+                                                 stopd(inode->i_sb)->hidden_mnt,
+                                                 hidden_flags);
+                       if (IS_ERR(hidden_file)) {
+                               err = PTR_ERR(hidden_file);
+                               dput(hidden_dentry);
+                               dput(hidden_sto_dentry);
+                               goto out;
+                       }
+                       ftohf(file) = hidden_file; /* link the two files */
+               }
+       }
+
+       if(!exists_in_storage(file->f_dentry)) {
+               printk(KERN_CRIT "mini_fo_open: invalid file state detected.\n");
+               err = -EINVAL;
+               dput(hidden_sto_dentry);
+
+               /* If the base file has been opened, we need to close it here */
+               if(ftohf(file)) {
+                       if (hidden_file->f_op && hidden_file->f_op->flush)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+                               hidden_file->f_op->flush(hidden_file, NULL);
+#else
+                               hidden_file->f_op->flush(hidden_file);
+#endif
+                       dput(hidden_dentry);
+               }
+               goto out;
+       }
+
+       /* ok, now we can safely open the storage file */
+       mntget(stopd(inode->i_sb)->hidden_mnt2);
+       hidden_sto_file = dentry_open(hidden_sto_dentry,
+                                     stopd(inode->i_sb)->hidden_mnt2,
+                                     hidden_flags);
+
+       /* dentry_open dputs the dentry if it fails */
+       if (IS_ERR(hidden_sto_file)) {
+               err = PTR_ERR(hidden_sto_file);
+               /* close base file if open */
+               if(ftohf(file)) {
+                       if (hidden_file->f_op && hidden_file->f_op->flush)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+                               hidden_file->f_op->flush(hidden_file, NULL);
+#else
+                               hidden_file->f_op->flush(hidden_file);
+#endif
+                       dput(hidden_dentry);
+               }
+               goto out;
+       }
+       ftohf2(file) = hidden_sto_file; /* link storage file */
+       
+ out:
+       if (err < 0 && ftopd(file)) {
+               kfree(ftopd(file));
+       }
+       return err;
+}
+
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+mini_fo_flush(file_t *file, fl_owner_t id)
+#else
+mini_fo_flush(file_t *file)
+#endif
+{
+       int err1 = 0;           /* assume ok (see open.c:close_fp) */
+       int err2 = 0;
+       file_t *hidden_file = NULL;
+       
+       check_mini_fo_file(file);
+
+       /* mk: we don't do any state checking here, as its not worth the time.
+        * Just flush the lower level files if they exist.
+        */
+       if(ftopd(file) != NULL) {
+               if(ftohf(file) != NULL) {
+                       hidden_file = ftohf(file);
+                       if (hidden_file->f_op && hidden_file->f_op->flush)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+                               err1 = hidden_file->f_op->flush(hidden_file, id);
+#else
+                               err1 = hidden_file->f_op->flush(hidden_file);
+#endif
+               }
+               if(ftohf2(file) != NULL) {
+                       hidden_file = ftohf2(file);
+                       if (hidden_file->f_op && hidden_file->f_op->flush)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+                               err2 = hidden_file->f_op->flush(hidden_file, id);
+#else
+                               err2 = hidden_file->f_op->flush(hidden_file);
+#endif
+               }
+       }
+       return (err1 | err2);
+}
+
+
+STATIC int
+mini_fo_release(inode_t *inode, file_t *file)
+{
+       int err = 0;
+       file_t *hidden_file = NULL;
+
+       if (ftopd(file) != NULL) {
+               if(ftohf(file)) {
+                       hidden_file = ftohf(file);
+                       fput(hidden_file);
+               }
+               if(ftohf2(file)) {
+                       hidden_file = ftohf2(file);
+                       fput(hidden_file);
+               }
+               kfree(ftopd(file));
+       }
+       return err;
+}
+
+STATIC int
+mini_fo_fsync(file_t *file, dentry_t *dentry, int datasync)
+{
+       int err1 = 0;
+       int err2 = 0;
+       file_t *hidden_file = NULL;
+       dentry_t *hidden_dentry;
+
+       check_mini_fo_file(file);
+
+       if ((hidden_file = ftohf(file)) != NULL) {
+               hidden_dentry = dtohd(dentry);
+               if (hidden_file->f_op && hidden_file->f_op->fsync) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+                       mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+                       down(&hidden_dentry->d_inode->i_sem);
+#endif
+                       err1 = hidden_file->f_op->fsync(hidden_file, hidden_dentry, datasync);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+                       mutex_unlock(&hidden_dentry->d_inode->i_mutex);
+#else
+                       up(&hidden_dentry->d_inode->i_sem);
+#endif
+               }
+       }
+
+       if ((hidden_file = ftohf2(file)) != NULL) {
+               hidden_dentry = dtohd2(dentry);
+               if (hidden_file->f_op && hidden_file->f_op->fsync) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+                       mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+                       down(&hidden_dentry->d_inode->i_sem);
+#endif
+                       err2 = hidden_file->f_op->fsync(hidden_file, hidden_dentry, datasync);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+                       mutex_unlock(&hidden_dentry->d_inode->i_mutex);
+#else
+                       up(&hidden_dentry->d_inode->i_sem);
+#endif
+               }
+       }
+       else
+               goto err;
+
+err:
+       return (err1 || err2);
+}
+
+
+STATIC int
+mini_fo_fasync(int fd, file_t *file, int flag)
+{
+       int err1 = 0;
+       int err2 = 0;
+
+       file_t *hidden_file = NULL;
+
+       check_mini_fo_file(file);
+
+       if((hidden_file = ftohf(file)) != NULL) {
+               err1 = hidden_file->f_op->fasync(fd, hidden_file, flag);
+       }
+       if((hidden_file = ftohf2(file)) != NULL) {
+               err2 = hidden_file->f_op->fasync(fd, hidden_file, flag);
+       }
+       
+       return (err1 || err2);
+}
+
+
+
+struct file_operations mini_fo_dir_fops =
+       {
+               read:   generic_read_dir,
+               write:  mini_fo_write,
+               readdir: mini_fo_readdir,
+               poll:   mini_fo_poll,
+               /* ioctl:       mini_fo_ioctl, */
+               mmap:   mini_fo_mmap,
+               open:   mini_fo_open,
+               flush:  mini_fo_flush,
+               release: mini_fo_release,
+               fsync:  mini_fo_fsync,
+               fasync: mini_fo_fasync,
+               /* not needed lock:     mini_fo_lock, */
+               /* not needed: readv */
+               /* not needed: writev */
+               /* not implemented: sendpage */
+               /* not implemented: get_unmapped_area */
+       };
+
+struct file_operations mini_fo_main_fops =
+       {
+               llseek: mini_fo_llseek,
+               read:   mini_fo_read,
+               write:  mini_fo_write,
+               readdir: mini_fo_readdir,
+               poll:   mini_fo_poll,
+               /* ioctl:       mini_fo_ioctl, */
+               mmap:   mini_fo_mmap,
+               open:   mini_fo_open,
+               flush:  mini_fo_flush,
+               release: mini_fo_release,
+               fsync:  mini_fo_fsync,
+               fasync: mini_fo_fasync,
+               /* not needed: lock:    mini_fo_lock, */
+               /* not needed: readv */
+               /* not needed: writev */
+               /* not implemented: sendpage */
+               /* not implemented: get_unmapped_area */
+       };
diff -urN linux-2.6.21.1.old/fs/mini_fo/fist.h linux-2.6.21.1.dev/fs/mini_fo/fist.h
--- linux-2.6.21.1.old/fs/mini_fo/fist.h        1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/fist.h        2007-05-26 21:01:26.162330024 +0200
@@ -0,0 +1,252 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+
+/*
+ *  $Id$
+ */
+
+#ifndef __FIST_H_
+#define __FIST_H_
+
+/*
+ * KERNEL ONLY CODE:
+ */
+#ifdef __KERNEL__
+#include <linux/version.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,19)
+#include <linux/autoconf.h>
+#else
+#include <linux/config.h>
+#endif
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+#ifdef CONFIG_MODVERSIONS
+# define MODVERSIONS
+# include <linux/modversions.h>
+#endif /* CONFIG_MODVERSIONS */
+#endif /* KERNEL_VERSION < 2.6.0 */
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/limits.h>
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+#include <linux/locks.h>
+#else
+#include <linux/buffer_head.h>
+#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/page-flags.h>
+#include <linux/writeback.h>
+#include <linux/statfs.h>
+#endif
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/poll.h>
+#include <linux/list.h>
+#include <linux/init.h>
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20)
+#include <linux/xattr.h>
+#endif
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+#include <linux/security.h>
+#endif
+
+#include <linux/swap.h>
+
+#include <asm/system.h>
+/* #include <asm/segment.h> */
+#include <asm/mman.h>
+#include <linux/seq_file.h>
+
+/*
+ * MACROS:
+ */
+
+/* those mapped to ATTR_* were copied from linux/fs.h */
+#define FA_MODE                ATTR_MODE
+#define FA_UID         ATTR_UID
+#define FA_GID         ATTR_GID
+#define FA_SIZE                ATTR_SIZE
+#define FA_ATIME       ATTR_ATIME
+#define FA_MTIME       ATTR_MTIME
+#define FA_CTIME       ATTR_CTIME
+#define FA_ATIME_SET   ATTR_ATIME_SET
+#define FA_MTIME_SET   ATTR_MTIME_SET
+#define FA_FORCE       ATTR_FORCE
+#define FA_ATTR_FLAGS  ATTR_ATTR_FLAG
+
+/* must be greater than all other ATTR_* flags! */
+#define FA_NLINK       2048
+#define FA_BLKSIZE     4096
+#define FA_BLOCKS      8192
+#define FA_TIMES       (FA_ATIME|FA_MTIME|FA_CTIME)
+#define FA_ALL         0
+
+/* macros to manage changes between kernels */
+#define INODE_DATA(i)  (&(i)->i_data)
+
+#define MIN(x,y) ((x < y) ? (x) : (y))
+#define MAX(x,y) ((x > y) ? (x) : (y))
+#define MAXPATHLEN PATH_MAX
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,4,5)
+# define lookup_one_len(a,b,c) lookup_one(a,b)
+#endif /* LINUX_VERSION_CODE < KERNEL_VERSION(2,4,5) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,4,8)
+# define generic_file_llseek default_llseek
+#endif /* LINUX_VERSION_CODE < KERNEL_VERSION(2,4,8) */
+
+#ifndef SEEK_SET
+# define SEEK_SET 0
+#endif /* not SEEK_SET */
+
+#ifndef SEEK_CUR
+# define SEEK_CUR 1
+#endif /* not SEEK_CUR */
+
+#ifndef SEEK_END
+# define SEEK_END 2
+#endif /* not SEEK_END */
+
+#ifndef DEFAULT_POLLMASK
+# define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
+#endif /* not DEFAULT_POLLMASK */
+
+/* XXX: fix this so fistgen generates kfree() code directly */
+#define kfree_s(a,b) kfree(a)
+
+/*
+ * TYPEDEFS:
+ */
+typedef struct dentry dentry_t;
+typedef struct file file_t;
+typedef struct inode inode_t;
+typedef inode_t vnode_t;
+typedef struct page page_t;
+typedef struct qstr qstr_t;
+typedef struct super_block super_block_t;
+typedef super_block_t vfs_t;
+typedef struct vm_area_struct vm_area_t;
+
+
+/*
+ * EXTERNALS:
+ */
+
+#define FPPF(str,page) printk("PPF %s 0x%x/%d: Lck:%d Err:%d Ref:%d Upd:%d Other::%d:%d:%d:%d:\n", \
+               str, \
+               (int) page, \
+               (int) page->index, \
+               (PageLocked(page) ? 1 : 0), \
+               (PageError(page) ? 1 : 0), \
+               (PageReferenced(page) ? 1 : 0), \
+               (Page_Uptodate(page) ? 1 : 0), \
+               (PageDecrAfter(page) ? 1 : 0), \
+               (PageSlab(page) ? 1 : 0), \
+               (PageSwapCache(page) ? 1 : 0), \
+               (PageReserved(page) ? 1 : 0) \
+               )
+#define EZKDBG printk("EZK %s:%d:%s\n",__FILE__,__LINE__,__FUNCTION__)
+#if 0
+# define EZKDBG1 printk("EZK %s:%d\n",__FILE__,__LINE__)
+#else
+# define EZKDBG1
+#endif
+
+extern int fist_get_debug_value(void);
+extern int fist_set_debug_value(int val);
+#if 0 /* mini_fo doesn't need these */
+extern void fist_dprint_internal(int level, char *str,...);
+extern void fist_print_dentry(char *str, const dentry_t *dentry);
+extern void fist_print_inode(char *str, const inode_t *inode);
+extern void fist_print_file(char *str, const file_t *file);
+extern void fist_print_buffer_flags(char *str, struct buffer_head *buffer);
+extern void fist_print_page_flags(char *str, page_t *page);
+extern void fist_print_page_bytes(char *str, page_t *page);
+extern void fist_print_pte_flags(char *str, const page_t *page);
+extern void fist_checkinode(inode_t *inode, char *msg);
+extern void fist_print_sb(char *str, const super_block_t *sb);
+
+/* §$% by mk: special debug functions */
+extern void fist_mk_print_dentry(char *str, const dentry_t *dentry);
+extern void fist_mk_print_inode(char *str, const inode_t *inode);
+
+extern char *add_indent(void);
+extern char *del_indent(void);
+#endif/* mini_fo doesn't need these */
+
+
+#define STATIC
+#define ASSERT(EX)     \
+do {   \
+    if (!(EX)) {       \
+       printk(KERN_CRIT "ASSERTION FAILED: %s at %s:%d (%s)\n", #EX,   \
+              __FILE__, __LINE__, __FUNCTION__);       \
+       (*((char *)0))=0;       \
+    }  \
+} while (0)
+/* same ASSERT, but tell me who was the caller of the function */
+#define ASSERT2(EX)    \
+do {   \
+    if (!(EX)) {       \
+       printk(KERN_CRIT "ASSERTION FAILED (caller): %s at %s:%d (%s)\n", #EX,  \
+              file, line, func);       \
+       (*((char *)0))=0;       \
+    }  \
+} while (0)
+
+#if 0 /* mini_fo doesn't need these */
+#define dprintk(format, args...) printk(KERN_DEBUG format, ##args)
+#define fist_dprint(level, str, args...) fist_dprint_internal(level, KERN_DEBUG str, ## args)
+#define print_entry_location() fist_dprint(4, "%sIN:  %s %s:%d\n", add_indent(), __FUNCTION__, __FILE__, __LINE__)
+#define print_exit_location() fist_dprint(4, "%s OUT: %s %s:%d\n", del_indent(), __FUNCTION__, __FILE__, __LINE__)
+#define print_exit_status(status) fist_dprint(4, "%s OUT: %s %s:%d, STATUS: %d\n", del_indent(), __FUNCTION__, __FILE__, __LINE__, status)
+#define print_exit_pointer(status) \
+do { \
+  if (IS_ERR(status)) \
+    fist_dprint(4, "%s OUT: %s %s:%d, RESULT: %ld\n", del_indent(), __FUNCTION__, __FILE__, __LINE__, PTR_ERR(status)); \
+  else \
+    fist_dprint(4, "%s OUT: %s %s:%d, RESULT: 0x%x\n", del_indent(), __FUNCTION__, __FILE__, __LINE__, PTR_ERR(status)); \
+} while (0)
+#endif/* mini_fo doesn't need these */
+
+#endif /* __KERNEL__ */
+
+
+/*
+ * DEFINITIONS FOR USER AND KERNEL CODE:
+ * (Note: ioctl numbers 1--9 are reserved for fistgen, the rest
+ *  are auto-generated automatically based on the user's .fist file.)
+ */
+# define FIST_IOCTL_GET_DEBUG_VALUE    _IOR(0x15, 1, int)
+# define FIST_IOCTL_SET_DEBUG_VALUE    _IOW(0x15, 2, int)
+
+#endif /* not __FIST_H_ */
diff -urN linux-2.6.21.1.old/fs/mini_fo/inode.c linux-2.6.21.1.dev/fs/mini_fo/inode.c
--- linux-2.6.21.1.old/fs/mini_fo/inode.c       1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/inode.c       2007-05-26 21:01:26.164329720 +0200
@@ -0,0 +1,1564 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif 
+
+#include "fist.h"
+#include "mini_fo.h"
+
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+mini_fo_create(inode_t *dir, dentry_t *dentry, int mode, struct nameidata *nd)
+#else
+mini_fo_create(inode_t *dir, dentry_t *dentry, int mode)
+#endif
+{
+       int err = 0;
+
+       check_mini_fo_dentry(dentry);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+       err = create_sto_reg_file(dentry, mode, nd);
+#else
+       err = create_sto_reg_file(dentry, mode);
+#endif
+       check_mini_fo_dentry(dentry);
+       return err;
+}
+
+
+STATIC dentry_t *
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+mini_fo_lookup(inode_t *dir, dentry_t *dentry, struct nameidata* nd)
+#else
+mini_fo_lookup(inode_t *dir, dentry_t *dentry)
+#endif
+{
+       int err = 0;
+       dentry_t *hidden_dir_dentry;
+       dentry_t *hidden_dentry = NULL;
+
+       dentry_t *hidden_sto_dir_dentry;
+       dentry_t *hidden_sto_dentry = NULL;
+
+       /* whiteout flag */
+       int del_flag = 0; 
+       char *bpath = NULL;
+
+       const char *name;
+       unsigned int namelen;
+
+       /* Don't allow lookups of META-files */
+       namelen = strlen(META_FILENAME);
+       if(namelen == dentry->d_name.len) {
+               if(!strncmp(dentry->d_name.name, META_FILENAME, namelen)) {
+                       err = -ENOENT;
+                       goto out;
+               }
+       }
+
+       hidden_dir_dentry = dtohd(dentry->d_parent);
+       hidden_sto_dir_dentry = dtohd2(dentry->d_parent);
+
+       name = dentry->d_name.name;
+       namelen = dentry->d_name.len;
+
+       /* must initialize dentry operations */
+       dentry->d_op = &mini_fo_dops;
+
+       /* setup the del_flag */
+       del_flag = __meta_check_d_entry(dir, name, namelen);
+       bpath = __meta_check_r_entry(dir, name, namelen);
+
+       /* perform the lookups of base and storage files:
+        *
+        * This caused some serious trouble, as a lookup_one_len passing
+        * a negative dentry oopses. Solution is to only do the lookup
+        * if the dentry is positive, else we set it to NULL
+        * More trouble, who said a *_dir_dentry can't be NULL?
+        */
+       if(bpath) {
+               /* Cross-Interposing (C), yeah! */
+               hidden_dentry = bpath_walk(dir->i_sb, bpath);
+               if(!hidden_dentry || !hidden_dentry->d_inode) {
+                       printk(KERN_CRIT "mini_fo_lookup: bpath_walk failed.\n");
+                       err= -EINVAL;
+                       goto out;
+               }
+               
+               /* this can be set up safely without fear of spaghetti
+                * interposing as it is only used for copying times */
+               hidden_dir_dentry = hidden_dentry->d_parent;
+               kfree(bpath);
+       }
+       else if(hidden_dir_dentry && hidden_dir_dentry->d_inode)
+               hidden_dentry = 
+                       lookup_one_len(name, hidden_dir_dentry, namelen);
+       else
+               hidden_dentry = NULL;
+
+       if(hidden_sto_dir_dentry && hidden_sto_dir_dentry->d_inode)
+               hidden_sto_dentry = 
+                       lookup_one_len(name, hidden_sto_dir_dentry, namelen);
+       else
+               hidden_sto_dentry =  NULL;
+
+       /* catch error in lookup */
+       if (IS_ERR(hidden_dentry) || IS_ERR(hidden_sto_dentry)) {
+               /* mk: we need to call dput on the dentry, whose 
+                * lookup_one_len operation failed, in order to avoid
+                * unmount trouble.
+                */
+               if(IS_ERR(hidden_dentry)) {
+                       printk(KERN_CRIT "mini_fo_lookup: ERR from base dentry, lookup failed.\n");
+                       err = PTR_ERR(hidden_dentry);
+               } else {
+                       dput(hidden_dentry);
+               }
+               if(IS_ERR(hidden_sto_dentry)) {
+                       printk(KERN_CRIT "mini_fo_lookup: ERR from storage dentry, lookup failed.\n");
+                       err = PTR_ERR(hidden_sto_dentry);
+               } else {
+                       dput(hidden_sto_dentry);
+               }
+               goto out;
+       }
+
+       /* allocate dentry private data */
+       __dtopd(dentry) = (struct mini_fo_dentry_info *)
+               kmalloc(sizeof(struct mini_fo_dentry_info), GFP_KERNEL);
+       
+       if (!dtopd(dentry)) {
+               err = -ENOMEM;
+               goto out_dput;
+       }
+
+       /* check for different states of the mini_fo file to be looked up. */
+       
+       /* state 1, file has been modified */
+       if(hidden_dentry && hidden_sto_dentry &&
+          hidden_dentry->d_inode && hidden_sto_dentry->d_inode && !del_flag) {
+
+               /* update parent directory's atime */
+               fist_copy_attr_atime(dir, hidden_sto_dir_dentry->d_inode);
+
+               dtopd(dentry)->state = MODIFIED;
+               dtohd(dentry) = hidden_dentry;
+               dtohd2(dentry) = hidden_sto_dentry;
+
+               err = mini_fo_tri_interpose(hidden_dentry,
+                                           hidden_sto_dentry,
+                                           dentry, dir->i_sb, 1);
+               if (err) {
+                       printk(KERN_CRIT "mini_fo_lookup: error interposing (state1).\n");
+                       goto out_free;
+               }
+               goto out;
+       }
+       /* state 2, file is unmodified */
+       if(hidden_dentry && hidden_dentry->d_inode && !del_flag) {
+
+               fist_copy_attr_atime(dir, hidden_dir_dentry->d_inode);
+
+               dtopd(dentry)->state = UNMODIFIED;
+               dtohd(dentry) = hidden_dentry;
+               dtohd2(dentry) = hidden_sto_dentry; /* could be negative */
+
+               err = mini_fo_tri_interpose(hidden_dentry,
+                                           hidden_sto_dentry,
+                                           dentry, dir->i_sb, 1);
+               if (err) {
+                       printk(KERN_CRIT "mini_fo_lookup: error interposing (state2).\n");
+                       goto out_free;
+               }
+               goto out;
+       }
+       /* state 3, file has been newly created */
+       if(hidden_sto_dentry && hidden_sto_dentry->d_inode && !del_flag) {
+
+               fist_copy_attr_atime(dir, hidden_sto_dir_dentry->d_inode);
+               dtopd(dentry)->state = CREATED;
+               dtohd(dentry) = hidden_dentry; /* could be negative */
+               dtohd2(dentry) = hidden_sto_dentry;
+
+               err = mini_fo_tri_interpose(hidden_dentry,
+                                           hidden_sto_dentry,
+                                           dentry, dir->i_sb, 1);
+               if (err) {
+                       printk(KERN_CRIT "mini_fo_lookup: error interposing (state3).\n");
+                       goto out_free;
+               }
+               goto out;
+       }
+
+       /* state 4, file has deleted and created again. */
+       if(hidden_dentry && hidden_sto_dentry &&
+          hidden_dentry->d_inode && 
+          hidden_sto_dentry->d_inode && del_flag) {
+
+               fist_copy_attr_atime(dir, hidden_sto_dir_dentry->d_inode);
+               dtopd(dentry)->state = DEL_REWRITTEN;
+               dtohd(dentry) = NULL;
+               dtohd2(dentry) = hidden_sto_dentry;
+
+               err = mini_fo_tri_interpose(NULL,
+                                           hidden_sto_dentry,
+                                           dentry, dir->i_sb, 1);
+               if (err) {
+                       printk(KERN_CRIT "mini_fo_lookup: error interposing (state4).\n");
+                       goto out_free;
+               }
+               /* We will never need this dentry again, as the file has been
+                * deleted from base */
+               dput(hidden_dentry);
+               goto out;
+       }
+       /* state 5, file has been deleted in base */
+       if(hidden_dentry && hidden_sto_dentry &&
+          hidden_dentry->d_inode && 
+          !hidden_sto_dentry->d_inode && del_flag) {
+
+               /* check which parents atime we need for updating */
+               if(hidden_sto_dir_dentry->d_inode)
+                       fist_copy_attr_atime(dir, 
+                                            hidden_sto_dir_dentry->d_inode);
+               else
+                       fist_copy_attr_atime(dir, 
+                                            hidden_dir_dentry->d_inode);
+
+               dtopd(dentry)->state = DELETED;
+               dtohd(dentry) = NULL;
+               dtohd2(dentry) = hidden_sto_dentry;
+
+               /* add negative dentry to dcache to speed up lookups */
+               d_add(dentry, NULL);
+               dput(hidden_dentry);
+               goto out;
+       }
+       /* state 6, file does not exist */
+       if(((hidden_dentry && !hidden_dentry->d_inode) ||
+           (hidden_sto_dentry && !hidden_sto_dentry->d_inode)) && !del_flag)
+               {
+                       /* check which parents atime we need for updating */
+                       if(hidden_sto_dir_dentry && hidden_sto_dir_dentry->d_inode)
+                               fist_copy_attr_atime(dir, hidden_sto_dir_dentry->d_inode);
+                       else
+                               fist_copy_attr_atime(dir, hidden_dir_dentry->d_inode);
+
+                       dtopd(dentry)->state = NON_EXISTANT;
+                       dtohd(dentry) = hidden_dentry;
+                       dtohd2(dentry) = hidden_sto_dentry;
+                       d_add(dentry, NULL);
+                       goto out;
+               }
+
+       /* if we get to here, were in an invalid state. bad. */
+       printk(KERN_CRIT "mini_fo_lookup: ERROR, meta data corruption detected.\n");
+
+       /* end state checking */
+ out_free:
+       d_drop(dentry);         /* so that our bad dentry will get destroyed */
+       kfree(dtopd(dentry));
+       __dtopd(dentry) = NULL; /* be safe */
+
+ out_dput:
+       if(hidden_dentry)
+               dput(hidden_dentry);
+       if(hidden_sto_dentry)
+               dput(hidden_sto_dentry); /* drops usage count and marks for release */
+
+ out:
+       /* initalize wol if file exists and is directory */
+       if(dentry->d_inode) {
+               if(S_ISDIR(dentry->d_inode->i_mode)) {
+                       itopd(dentry->d_inode)->deleted_list_size = -1;
+                       itopd(dentry->d_inode)->renamed_list_size = -1;
+                       meta_build_lists(dentry);
+               }
+       }
+       return ERR_PTR(err);
+}
+
+
+STATIC int
+mini_fo_link(dentry_t *old_dentry, inode_t *dir, dentry_t *new_dentry)
+{
+       int err;
+       dentry_t *hidden_old_dentry;
+       dentry_t *hidden_new_dentry;
+       dentry_t *hidden_dir_dentry;
+
+
+       check_mini_fo_dentry(old_dentry);
+       check_mini_fo_dentry(new_dentry);
+       check_mini_fo_inode(dir);
+
+       /* no links to directorys and existing targets target allowed */
+       if(S_ISDIR(old_dentry->d_inode->i_mode) ||
+          is_mini_fo_existant(new_dentry)) {
+               err = -EPERM;
+               goto out;
+       }
+
+       /* bring it directly from unmod to del_rew */
+       if(dtost(old_dentry) == UNMODIFIED) {
+               err = nondir_unmod_to_mod(old_dentry, 1);
+               if(err) {
+                       err = -EINVAL;
+                       goto out;
+               }
+               err = meta_add_d_entry(old_dentry->d_parent,
+                                      old_dentry->d_name.name,
+                                      old_dentry->d_name.len);
+               if(err) {
+                       err = -EINVAL;
+                       goto out;
+               }
+               dput(dtohd(old_dentry));
+               dtohd(old_dentry) = NULL;
+               dtost(old_dentry) = DEL_REWRITTEN;
+       }
+       
+       err = get_neg_sto_dentry(new_dentry);
+       if(err) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       hidden_old_dentry = dtohd2(old_dentry);
+       hidden_new_dentry = dtohd2(new_dentry);
+
+       dget(hidden_old_dentry);
+       dget(hidden_new_dentry);
+
+       /* was: hidden_dir_dentry = lock_parent(hidden_new_dentry); */
+       hidden_dir_dentry = dget(hidden_new_dentry->d_parent);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_dir_dentry->d_inode->i_sem);
+#endif
+
+       err = vfs_link(hidden_old_dentry,
+                      hidden_dir_dentry->d_inode,
+                      hidden_new_dentry);
+       if (err || !hidden_new_dentry->d_inode)
+               goto out_lock;
+
+       dtost(new_dentry) = CREATED;
+       err = mini_fo_tri_interpose(NULL, hidden_new_dentry, new_dentry, dir->i_sb, 0);
+       if (err)
+               goto out_lock;
+
+       fist_copy_attr_timesizes(dir, hidden_new_dentry->d_inode);
+       /* propagate number of hard-links */
+       old_dentry->d_inode->i_nlink = itohi2(old_dentry->d_inode)->i_nlink;
+
+ out_lock:
+       /* was: unlock_dir(hidden_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_dir_dentry);
+
+       dput(hidden_new_dentry);
+       dput(hidden_old_dentry);
+       if (!new_dentry->d_inode)
+               d_drop(new_dentry);
+
+ out:
+       return err;
+}
+
+
+STATIC int
+mini_fo_unlink(inode_t *dir, dentry_t *dentry)
+{
+       int err = 0;
+
+       dget(dentry);
+       if(dtopd(dentry)->state == MODIFIED) {
+               err = nondir_mod_to_del(dentry);
+               goto out;
+       }
+       else if(dtopd(dentry)->state == UNMODIFIED) {
+               err = nondir_unmod_to_del(dentry);
+               goto out;
+       }
+       else if(dtopd(dentry)->state == CREATED) {
+               err = nondir_creat_to_del(dentry);
+               goto out;
+       }
+       else if(dtopd(dentry)->state == DEL_REWRITTEN) {
+               err = nondir_del_rew_to_del(dentry);
+               goto out;
+       }
+
+       printk(KERN_CRIT "mini_fo_unlink: ERROR, invalid state detected.\n");
+
+ out:
+       fist_copy_attr_times(dir, itohi2(dentry->d_parent->d_inode));
+
+       if(!err) {
+               /* is this causing my pain? d_delete(dentry); */
+               d_drop(dentry);
+       }
+
+       dput(dentry);
+       return err;
+}
+
+
+STATIC int
+mini_fo_symlink(inode_t *dir, dentry_t *dentry, const char *symname)
+{
+       int err=0;
+       dentry_t *hidden_sto_dentry;
+       dentry_t *hidden_sto_dir_dentry;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+        umode_t mode;
+#endif
+
+       /* Fail if the symlink file exists */
+       if(!(dtost(dentry) == DELETED || 
+            dtost(dentry) == NON_EXISTANT)) {
+               err = -EEXIST;
+               goto out;
+       }
+
+       err = get_neg_sto_dentry(dentry);
+       if(err) {
+               err = -EINVAL;
+               goto out;
+       }
+       hidden_sto_dentry = dtohd2(dentry);
+
+       dget(hidden_sto_dentry);
+       /* was: hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry); */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+       mode = S_IALLUGO;
+       err = vfs_symlink(hidden_sto_dir_dentry->d_inode,
+                         hidden_sto_dentry, symname, mode);
+#else
+       err = vfs_symlink(hidden_sto_dir_dentry->d_inode,
+                         hidden_sto_dentry,
+                         symname);
+#endif
+       if (err || !hidden_sto_dentry->d_inode)
+                goto out_lock;
+
+        if(dtost(dentry) == DELETED) {
+                dtost(dentry) = DEL_REWRITTEN;
+                err = mini_fo_tri_interpose(NULL, hidden_sto_dentry, dentry, dir->i_sb, 0);
+                if(err)
+                        goto out_lock;
+        } else if(dtost(dentry) == NON_EXISTANT) {
+                dtost(dentry) = CREATED;
+                err = mini_fo_tri_interpose(dtohd(dentry), hidden_sto_dentry, dentry, dir->i_sb, 0);
+                if(err)
+                        goto out_lock;
+        }
+       fist_copy_attr_timesizes(dir, hidden_sto_dir_dentry->d_inode);
+       
+ out_lock:
+        /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_sto_dir_dentry);
+
+        dput(hidden_sto_dentry);
+        if (!dentry->d_inode)
+                d_drop(dentry);
+ out:
+        return err;
+}
+
+STATIC int
+mini_fo_mkdir(inode_t *dir, dentry_t *dentry, int mode)
+{
+       int err;
+
+       err = create_sto_dir(dentry, mode);
+
+       check_mini_fo_dentry(dentry);
+
+       return err;
+}
+
+
+STATIC int
+mini_fo_rmdir(inode_t *dir, dentry_t *dentry)
+{
+       int err = 0;
+       
+       dentry_t *hidden_sto_dentry;
+       dentry_t *hidden_sto_dir_dentry;
+       dentry_t *meta_dentry;
+       inode_t *hidden_sto_dir = NULL;
+
+       check_mini_fo_dentry(dentry);
+       check_mini_fo_inode(dir);
+
+       dget(dentry);
+       if(dtopd(dentry)->state == MODIFIED) {
+               /* XXX: disabled, because it does not bother to check files on
+                * the original filesystem - just a hack, but better than simply
+                * removing it without testing */
+               err = -EINVAL;
+               goto out;
+
+               hidden_sto_dir = itohi2(dir);
+               hidden_sto_dentry = dtohd2(dentry);
+
+               /* was:hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry); */
+               hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+               /* Delete an old WOL file contained in the storage dir */
+               meta_dentry = lookup_one_len(META_FILENAME, 
+                                            hidden_sto_dentry, 
+                                            strlen(META_FILENAME));
+               if(meta_dentry->d_inode) {
+                       err = vfs_unlink(hidden_sto_dentry->d_inode, meta_dentry);
+                       dput(meta_dentry);
+                       if(!err)
+                               d_delete(meta_dentry);
+               }
+
+               err = vfs_rmdir(hidden_sto_dir, hidden_sto_dentry);
+               dput(hidden_sto_dentry);
+               if(!err)
+                       d_delete(hidden_sto_dentry);
+
+               /* propagate number of hard-links */
+               dentry->d_inode->i_nlink = itohi2(dentry->d_inode)->i_nlink;
+
+               dput(dtohd(dentry));
+               
+               dtohd(dentry) = NULL;
+               dtopd(dentry)->state = DELETED;
+
+               /* carefull with R files */
+               if( __meta_is_r_entry(dir, 
+                                     dentry->d_name.name, 
+                                     dentry->d_name.len) == 1) {
+                       err = meta_remove_r_entry(dentry->d_parent, 
+                                                 dentry->d_name.name,
+                                                 dentry->d_name.len);
+                       if(err) {
+                               printk(KERN_CRIT "mini_fo: rmdir: meta_remove_r_entry failed.\n");
+                               goto out;
+                       }
+               }
+               else {
+                       /* ok, add deleted file to META */              
+                       meta_add_d_entry(dentry->d_parent, 
+                                        dentry->d_name.name, 
+                                        dentry->d_name.len);
+               }
+               /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+               dput(hidden_sto_dir_dentry);
+               goto out;
+       }
+       else if(dtopd(dentry)->state == UNMODIFIED) {
+               /* XXX: simply adding it to the delete list here is fscking dangerous!
+                * as a temporary hack, i will disable rmdir on unmodified directories 
+                * for now.
+                */
+               err = -EINVAL;
+               goto out;
+
+               err = get_neg_sto_dentry(dentry);
+               if(err) {
+                       err = -EINVAL;
+                       goto out;
+               }
+               
+               /* dput base dentry, this will relase the inode and free the
+                * dentry, as we will never need it again. */
+               dput(dtohd(dentry));
+               dtohd(dentry) = NULL;
+               dtopd(dentry)->state = DELETED;
+
+               /* add deleted file to META-file */
+               meta_add_d_entry(dentry->d_parent, 
+                                dentry->d_name.name, 
+                                dentry->d_name.len);
+               goto out;
+       }
+       else if(dtopd(dentry)->state == CREATED) {
+               hidden_sto_dir = itohi2(dir);
+               hidden_sto_dentry = dtohd2(dentry);
+
+               /* was: hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry);*/
+               hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+               /* Delete an old WOL file contained in the storage dir */
+               meta_dentry = lookup_one_len(META_FILENAME, 
+                                            hidden_sto_dentry, 
+                                            strlen(META_FILENAME));
+               if(meta_dentry->d_inode) {
+                       /* is this necessary? dget(meta_dentry); */
+                       err = vfs_unlink(hidden_sto_dentry->d_inode, 
+                                        meta_dentry);
+                       dput(meta_dentry);
+                       if(!err)
+                               d_delete(meta_dentry);
+               }
+
+               err = vfs_rmdir(hidden_sto_dir, hidden_sto_dentry);
+               dput(hidden_sto_dentry);
+               if(!err)
+                       d_delete(hidden_sto_dentry);
+
+               /* propagate number of hard-links */
+               dentry->d_inode->i_nlink = itohi2(dentry->d_inode)->i_nlink;
+               dtopd(dentry)->state = NON_EXISTANT;
+
+               /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+               dput(hidden_sto_dir_dentry);
+
+               goto out;
+       }
+       else if(dtopd(dentry)->state == DEL_REWRITTEN) {
+               hidden_sto_dir = itohi2(dir);
+               hidden_sto_dentry = dtohd2(dentry);
+
+               /* was: hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry);*/
+               hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+               /* Delete an old WOL file contained in the storage dir */
+               meta_dentry = lookup_one_len(META_FILENAME, 
+                                            hidden_sto_dentry, 
+                                            strlen(META_FILENAME));
+               if(meta_dentry->d_inode) {
+                       /* is this necessary? dget(meta_dentry); */
+                       err = vfs_unlink(hidden_sto_dentry->d_inode,
+                                        meta_dentry);
+                       dput(meta_dentry);
+                       if(!err)
+                               d_delete(meta_dentry);
+               }
+
+               err = vfs_rmdir(hidden_sto_dir, hidden_sto_dentry);
+               dput(hidden_sto_dentry);
+               if(!err)
+                       d_delete(hidden_sto_dentry);
+
+               /* propagate number of hard-links */
+               dentry->d_inode->i_nlink = itohi2(dentry->d_inode)->i_nlink;
+               dtopd(dentry)->state = DELETED;
+               /* was: unlock_dir(hidden_sto_dir_dentry); */
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+               dput(hidden_sto_dir_dentry);
+               goto out;
+       }
+
+       printk(KERN_CRIT "mini_fo_rmdir: ERROR, invalid state detected.\n");
+
+ out:
+       if(!err) {
+               d_drop(dentry);
+       }
+               
+       fist_copy_attr_times(dir, itohi2(dentry->d_parent->d_inode));
+       dput(dentry);
+
+       return err;
+}
+
+
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+mini_fo_mknod(inode_t *dir, dentry_t *dentry, int mode, dev_t dev)
+#else
+mini_fo_mknod(inode_t *dir, dentry_t *dentry, int mode, int dev)
+#endif
+{
+       int err = 0;
+
+       check_mini_fo_dentry(dentry);
+
+       err = create_sto_nod(dentry, mode, dev);
+       if(err) {
+               printk(KERN_CRIT "mini_fo_mknod: creating sto nod failed.\n");
+               err = -EINVAL;
+       }
+       
+       check_mini_fo_dentry(dentry);
+       return err;
+}
+
+
+STATIC int
+mini_fo_rename(inode_t *old_dir, dentry_t *old_dentry,
+              inode_t *new_dir, dentry_t *new_dentry)
+{
+       /* dispatch */
+       if(S_ISDIR(old_dentry->d_inode->i_mode))
+               return rename_directory(old_dir, old_dentry, new_dir, new_dentry);
+       return rename_nondir(old_dir, old_dentry, new_dir, new_dentry);
+       
+}
+
+int rename_directory(inode_t *old_dir, dentry_t *old_dentry,
+                    inode_t *new_dir, dentry_t *new_dentry)
+{
+       int err, bpath_len;
+       char *bpath;
+
+       dentry_t *hidden_old_dentry;
+       dentry_t *hidden_new_dentry;
+       dentry_t *hidden_old_dir_dentry;
+       dentry_t *hidden_new_dir_dentry;
+
+       err = 0;
+       bpath = NULL;
+       bpath_len = 0;
+
+       /* this is a test, chuck out if it works */
+       if(!(dtopd(new_dentry)->state == DELETED ||
+            dtopd(new_dentry)->state == NON_EXISTANT)) {
+               printk(KERN_CRIT "mini_fo: rename_directory: \
+                                  uh, ah, new_dentry not negative.\n");
+               /* return -1; */
+       }
+       
+       /* state = UNMODIFIED */
+       if(dtopd(old_dentry)->state == UNMODIFIED) {
+               err = dir_unmod_to_mod(old_dentry);
+               if (err) 
+                       goto out;
+       }
+
+       /* state = MODIFIED */
+       if(dtopd(old_dentry)->state == MODIFIED) {
+               bpath = meta_check_r_entry(old_dentry->d_parent, 
+                                          old_dentry->d_name.name,
+                                          old_dentry->d_name.len);
+               if(bpath) {
+                       err = meta_remove_r_entry(old_dentry->d_parent,
+                                                 old_dentry->d_name.name,
+                                                 old_dentry->d_name.len);
+                       if(err) {
+                               printk(KERN_CRIT "mini_fo: rename_directory:\
+                                                   meta_remove_r_entry \
+                                                  failed.\n");
+                               goto out;
+                       }
+                       err = meta_add_r_entry(new_dentry->d_parent,
+                                              bpath,
+                                              strlen(bpath),
+                                              new_dentry->d_name.name,
+                                              new_dentry->d_name.len);
+                       kfree(bpath);
+               }
+               else {/* wol it */
+                       err = meta_add_d_entry(old_dentry->d_parent, 
+                                              old_dentry->d_name.name,
+                                              old_dentry->d_name.len);
+                       if (err) 
+                               goto out;
+                       /* put it on rename list */
+                       err = get_mini_fo_bpath(old_dentry,
+                                               &bpath, 
+                                               &bpath_len);
+                       if (err) 
+                               goto out;
+                       err = meta_add_r_entry(new_dentry->d_parent,
+                                              bpath, bpath_len,
+                                              new_dentry->d_name.name,
+                                              new_dentry->d_name.len);
+                       if (err) 
+                               goto out;
+               }
+               /* no state change, MODIFIED stays MODIFIED */
+       }
+       /* state = CREATED */
+       if(dtopd(old_dentry)->state == CREATED ||
+          dtopd(old_dentry)->state == DEL_REWRITTEN) {
+               if(dtohd(old_dentry))
+                       dput(dtohd(old_dentry));
+               
+               if(dtopd(new_dentry)->state == DELETED) {
+                       dtopd(old_dentry)->state = DEL_REWRITTEN;
+                       dtohd(old_dentry) = NULL;
+               } 
+               else if(dtopd(new_dentry)->state == NON_EXISTANT) {
+                       dtopd(old_dentry)->state = CREATED;
+                       /* steal new dentry's neg. base dentry */
+                       dtohd(old_dentry) = dtohd(new_dentry);
+                       dtohd(new_dentry) = NULL;
+               }
+       }               
+       if(dtopd(new_dentry)->state == UNMODIFIED ||
+          dtopd(new_dentry)->state == NON_EXISTANT) {
+               err = get_neg_sto_dentry(new_dentry);
+               if(err)
+                       goto out;
+       }
+                       
+       /* now move sto file */
+       hidden_old_dentry = dtohd2(old_dentry);
+       hidden_new_dentry = dtohd2(new_dentry);
+       
+       dget(hidden_old_dentry);
+       dget(hidden_new_dentry);
+       
+       hidden_old_dir_dentry = dget(hidden_old_dentry->d_parent);
+       hidden_new_dir_dentry = dget(hidden_new_dentry->d_parent);
+       double_lock(hidden_old_dir_dentry, hidden_new_dir_dentry);
+       
+       err = vfs_rename(hidden_old_dir_dentry->d_inode, hidden_old_dentry,
+                        hidden_new_dir_dentry->d_inode, hidden_new_dentry);
+       if(err)
+               goto out_lock;
+       
+       fist_copy_attr_all(new_dir, hidden_new_dir_dentry->d_inode);
+       if (new_dir != old_dir)
+               fist_copy_attr_all(old_dir, 
+                                  hidden_old_dir_dentry->d_inode);
+       
+ out_lock:
+       /* double_unlock will dput the new/old parent dentries
+        * whose refcnts were incremented via get_parent above. */
+       double_unlock(hidden_old_dir_dentry, hidden_new_dir_dentry);
+       dput(hidden_new_dentry);
+       dput(hidden_old_dentry);
+       
+ out:
+       return err;
+}
+
+int rename_nondir(inode_t *old_dir, dentry_t *old_dentry,
+                 inode_t *new_dir, dentry_t *new_dentry)
+{
+       int err=0;
+
+       check_mini_fo_dentry(old_dentry);
+       check_mini_fo_dentry(new_dentry);
+       check_mini_fo_inode(old_dir);
+       check_mini_fo_inode(new_dir);
+
+       /* state: UNMODIFIED */
+       if(dtost(old_dentry) == UNMODIFIED) {
+               err = nondir_unmod_to_mod(old_dentry, 1);
+               if(err) {
+                       err = -EINVAL;
+                       goto out;
+               }
+       }
+
+       /* the easy states */
+       if(exists_in_storage(old_dentry)) {
+               
+               dentry_t *hidden_old_dentry;
+               dentry_t *hidden_new_dentry;
+               dentry_t *hidden_old_dir_dentry;
+               dentry_t *hidden_new_dir_dentry;
+
+               /* if old file is MODIFIED, add it to the deleted_list */
+               if(dtopd(old_dentry)->state == MODIFIED) {
+                       meta_add_d_entry(old_dentry->d_parent,
+                                        old_dentry->d_name.name,
+                                        old_dentry->d_name.len);
+
+                       dput(dtohd(old_dentry));
+               }
+               /* if old file is CREATED, we only release the base dentry */
+               if(dtopd(old_dentry)->state == CREATED) {
+                       if(dtohd(old_dentry))
+                               dput(dtohd(old_dentry));
+               }
+
+               /* now setup the new states (depends on new_dentry state) */
+               /* new dentry state =  MODIFIED */
+               if(dtopd(new_dentry)->state == MODIFIED) {
+                       meta_add_d_entry(new_dentry->d_parent,
+                                        new_dentry->d_name.name,
+                                        new_dentry->d_name.len);
+
+                       /* new dentry will be d_put'ed later by the vfs
+                        * so don't do it here
+                        * dput(dtohd(new_dentry));
+                        */
+                       dtohd(old_dentry) = NULL;
+                       dtopd(old_dentry)->state = DEL_REWRITTEN;
+               }
+               /* new dentry state =  UNMODIFIED */
+               else if(dtopd(new_dentry)->state == UNMODIFIED) {
+                       if(get_neg_sto_dentry(new_dentry))
+                               return -EINVAL;
+
+                       meta_add_d_entry(new_dentry->d_parent,
+                                        new_dentry->d_name.name,
+                                        new_dentry->d_name.len);
+
+                       /* is this right??? */
+                       /*dput(dtohd(new_dentry));*/
+                       dtohd(old_dentry) = NULL;
+                       dtopd(old_dentry)->state = DEL_REWRITTEN;
+               }
+               /* new dentry state =  CREATED */
+               else if(dtopd(new_dentry)->state == CREATED) {
+                       /* we keep the neg. base dentry (if exists) */
+                       dtohd(old_dentry) = dtohd(new_dentry);
+                       /* ...and set it to Null, or we'll get
+                        * dcache.c:345 if it gets dput twice... */
+                       dtohd(new_dentry) = NULL;
+                       dtopd(old_dentry)->state = CREATED;
+               }
+               /* new dentry state =  NON_EXISTANT */
+               else if(dtopd(new_dentry)->state == NON_EXISTANT) {
+                       if(get_neg_sto_dentry(new_dentry))
+                               return -EINVAL;
+
+                       /* we keep the neg. base dentry (if exists) */
+                       dtohd(old_dentry) = dtohd(new_dentry);
+                       /* ...and set it to Null, or we'll get 
+                        * Dr. dcache.c:345 if it gets dput twice... */
+                       dtohd(new_dentry) = NULL;
+                       dtopd(old_dentry)->state = CREATED;
+               }
+               /* new dentry state =  DEL_REWRITTEN or DELETED */
+               else if(dtopd(new_dentry)->state == DEL_REWRITTEN ||
+                       dtopd(new_dentry)->state == DELETED) {
+                       dtohd(old_dentry) = NULL;
+                       dtopd(old_dentry)->state = DEL_REWRITTEN;
+               }
+               else { /* not possible, uhh, ahh */
+                       printk(KERN_CRIT 
+                              "mini_fo: rename_reg_file: invalid state detected [1].\n");
+                       return -1;
+               }
+               
+               /* now we definitely have a sto file */
+               hidden_old_dentry = dtohd2(old_dentry);
+               hidden_new_dentry = dtohd2(new_dentry);
+
+               dget(hidden_old_dentry);
+               dget(hidden_new_dentry);
+               
+               hidden_old_dir_dentry = dget(hidden_old_dentry->d_parent);
+               hidden_new_dir_dentry = dget(hidden_new_dentry->d_parent);
+               double_lock(hidden_old_dir_dentry, hidden_new_dir_dentry);
+
+               err = vfs_rename(hidden_old_dir_dentry->d_inode, 
+                                hidden_old_dentry,
+                                hidden_new_dir_dentry->d_inode, 
+                                hidden_new_dentry);
+               if(err) 
+                       goto out_lock;
+
+               fist_copy_attr_all(new_dir, hidden_new_dir_dentry->d_inode);
+               if (new_dir != old_dir)
+                       fist_copy_attr_all(old_dir, hidden_old_dir_dentry->d_inode);
+               
+       out_lock:
+               /* double_unlock will dput the new/old parent dentries 
+                * whose refcnts were incremented via get_parent above.
+                */
+               double_unlock(hidden_old_dir_dentry, hidden_new_dir_dentry);
+               dput(hidden_new_dentry);
+               dput(hidden_old_dentry);
+       out:            
+               return err;
+       }
+       else { /* invalid state */
+               printk(KERN_CRIT "mini_fo: rename_reg_file: ERROR: invalid state detected [2].\n");
+               return -1;
+       }
+}
+
+
+STATIC int
+mini_fo_readlink(dentry_t *dentry, char *buf, int bufsiz)
+{
+       int err=0;
+       dentry_t *hidden_dentry = NULL;
+
+       if(dtohd2(dentry) && dtohd2(dentry)->d_inode) {
+               hidden_dentry = dtohd2(dentry);
+       } else if(dtohd(dentry) && dtohd(dentry)->d_inode) {
+               hidden_dentry = dtohd(dentry);
+       } else {
+               goto out;
+       }
+
+       if (!hidden_dentry->d_inode->i_op ||
+           !hidden_dentry->d_inode->i_op->readlink) {
+               err = -EINVAL;          goto out;
+       }
+
+       err = hidden_dentry->d_inode->i_op->readlink(hidden_dentry,
+                                                    buf,
+                                                    bufsiz);
+       if (err > 0)
+               fist_copy_attr_atime(dentry->d_inode, hidden_dentry->d_inode);
+
+ out:
+       return err;
+}
+
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,13)
+static int mini_fo_follow_link(dentry_t *dentry, struct nameidata *nd)
+#else
+static void* mini_fo_follow_link(dentry_t *dentry, struct nameidata *nd)
+#endif
+{
+       char *buf;
+       int len = PAGE_SIZE, err;
+       mm_segment_t old_fs;
+
+       /* in 2.6 this is freed by mini_fo_put_link called by __do_follow_link */
+       buf = kmalloc(len, GFP_KERNEL);
+       if (!buf) {
+               err = -ENOMEM;
+               goto out;
+       }
+
+       /* read the symlink, and then we will follow it */
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+       err = dentry->d_inode->i_op->readlink(dentry, buf, len);
+       set_fs(old_fs);
+       if (err < 0) {
+               kfree(buf);
+               buf = NULL;
+               goto out;
+       }
+       buf[err] = 0;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+        nd_set_link(nd, buf);
+        err = 0;
+#else
+       err = vfs_follow_link(nd, buf);
+#endif
+
+ out:
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+       kfree(buf);
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,13)
+        return err;
+#else
+        return ERR_PTR(err);
+#endif
+}
+
+STATIC
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,13)
+void mini_fo_put_link(struct dentry *dentry, struct nameidata *nd)
+#else
+void mini_fo_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
+#endif
+{
+        char *link;
+        link = nd_get_link(nd);
+        kfree(link);
+}
+#endif
+
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+mini_fo_permission(inode_t *inode, int mask, struct nameidata *nd)
+#else
+mini_fo_permission(inode_t *inode, int mask)
+#endif
+{
+       inode_t *hidden_inode;
+       int mode;
+       int err;
+
+       if(itohi2(inode)) {
+               hidden_inode = itohi2(inode);
+       } else {
+               hidden_inode = itohi(inode);
+       }
+       mode = inode->i_mode;
+
+       /* not really needed, as permission handles everything:
+        *      err = vfs_permission(inode, mask);
+        *      if (err)
+        *              goto out;
+        */
+       
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+       err = permission(hidden_inode, mask, nd);
+#else
+       err = permission(hidden_inode, mask);
+#endif
+       
+       /*  out: */
+       return err;
+}
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+STATIC int
+mini_fo_inode_revalidate(dentry_t *dentry)
+{
+       int err = 0;
+       dentry_t *hidden_dentry;
+       inode_t *hidden_inode;
+
+       ASSERT(dentry->d_inode);
+       ASSERT(itopd(dentry->d_inode));
+
+       if(itohi2(dentry->d_inode)) {
+                hidden_dentry = dtohd2(dentry);
+               hidden_inode = hidden_dentry->d_inode;
+       } else if(itohi(dentry->d_inode)) {
+                hidden_dentry = dtohd(dentry);
+               hidden_inode = hidden_dentry->d_inode;
+       } else {
+                printk(KERN_CRIT "mini_fo_inode_revalidate: ERROR, invalid state detected.\n");
+                err = -ENOENT;
+                goto out;
+        }
+       if (hidden_inode && hidden_inode->i_op && hidden_inode->i_op->revalidate){
+               err = hidden_inode->i_op->revalidate(hidden_dentry);
+               if (err)
+                       goto out;
+       }
+       fist_copy_attr_all(dentry->d_inode, hidden_inode);
+ out:
+       return err;
+}
+#endif
+
+STATIC int
+mini_fo_setattr(dentry_t *dentry, struct iattr *ia)
+{
+       int err = 0;
+
+       check_mini_fo_dentry(dentry);
+       
+       if(!is_mini_fo_existant(dentry)) {
+               printk(KERN_CRIT "mini_fo_setattr: ERROR, invalid state detected [1].\n");
+               goto out;
+       }
+
+       if(dtost(dentry) == UNMODIFIED) {
+               if(!IS_COPY_FLAG(ia->ia_valid))
+                       goto out; /* we ignore these changes to base */
+
+               if(S_ISDIR(dentry->d_inode->i_mode)) {
+                       err = dir_unmod_to_mod(dentry);
+               } else {
+                       /* we copy contents if file is not beeing truncated */
+                       if(S_ISREG(dentry->d_inode->i_mode) && 
+                          !(ia->ia_size == 0 && (ia->ia_valid & ATTR_SIZE))) {
+                               err = nondir_unmod_to_mod(dentry, 1);
+                       } else
+                               err = nondir_unmod_to_mod(dentry, 0);
+               }
+               if(err) {
+                       err = -EINVAL;
+                       printk(KERN_CRIT "mini_fo_setattr: ERROR changing states.\n");
+                       goto out;
+               }
+       }
+       if(!exists_in_storage(dentry)) {
+               printk(KERN_CRIT "mini_fo_setattr: ERROR, invalid state detected [2].\n");
+               err = -EINVAL;
+               goto out;
+       }
+       ASSERT(dentry->d_inode);
+       ASSERT(dtohd2(dentry));
+       ASSERT(itopd(dentry->d_inode));
+       ASSERT(itohi2(dentry->d_inode));
+       
+       err = notify_change(dtohd2(dentry), ia);
+       fist_copy_attr_all(dentry->d_inode, itohi2(dentry->d_inode));
+ out:
+       return err;
+}
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+STATIC int
+mini_fo_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+       int err = 0;
+        dentry_t *hidden_dentry;
+
+       ASSERT(dentry->d_inode);
+       ASSERT(itopd(dentry->d_inode));
+
+       if(itohi2(dentry->d_inode)) {
+                hidden_dentry = dtohd2(dentry);
+       } else if(itohi(dentry->d_inode)) {
+                hidden_dentry = dtohd(dentry);
+       } else {
+                printk(KERN_CRIT "mini_fo_getattr: ERROR, invalid state detected.\n");
+                err = -ENOENT;
+                goto out;
+        }
+       fist_copy_attr_all(dentry->d_inode, hidden_dentry->d_inode);
+
+       ASSERT(hidden_dentry);
+       ASSERT(hidden_dentry->d_inode);
+       ASSERT(hidden_dentry->d_inode->i_op);
+
+       generic_fillattr(dentry->d_inode, stat);
+       if (!stat->blksize) {
+               struct super_block *s = hidden_dentry->d_inode->i_sb;
+               unsigned blocks;
+               blocks = (stat->size+s->s_blocksize-1) >> s->s_blocksize_bits;
+               stat->blocks = (s->s_blocksize / 512) * blocks;
+               stat->blksize = s->s_blocksize;
+       }
+ out:
+        return err;
+}
+#endif
+
+#if defined(XATTR) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20))
+#if 0 /* no xattr_alloc() and xattr_free() */
+/* This is lifted from fs/xattr.c */
+static void *
+xattr_alloc(size_t size, size_t limit)
+{
+       void *ptr;
+
+       if (size > limit)
+               return ERR_PTR(-E2BIG);
+
+       if (!size)      /* size request, no buffer is needed */
+               return NULL;
+       else if (size <= PAGE_SIZE)
+               ptr = kmalloc((unsigned long) size, GFP_KERNEL);
+       else
+               ptr = vmalloc((unsigned long) size);
+       if (!ptr)
+               return ERR_PTR(-ENOMEM);
+       return ptr;
+}
+
+static void
+xattr_free(void *ptr, size_t size)
+{
+       if (!size)      /* size request, no buffer was needed */
+               return;
+       else if (size <= PAGE_SIZE)
+               kfree(ptr);
+       else
+               vfree(ptr);
+}
+#endif /* no xattr_alloc() and xattr_free() */
+
+/* BKL held by caller.
+ * dentry->d_inode->i_sem down
+ */
+STATIC int
+mini_fo_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) {
+       struct dentry *hidden_dentry = NULL;
+       int err = -EOPNOTSUPP;
+       /* Define these anyway so we don't need as much ifdef'ed code. */
+       char *encoded_name = NULL;
+       char *encoded_value = NULL;
+
+       check_mini_fo_dentry(dentry);
+
+       if(exists_in_storage(dentry))
+               hidden_dentry = dtohd2(dentry);
+       else
+               hidden_dentry = dtohd(dentry);
+          
+       ASSERT(hidden_dentry);
+       ASSERT(hidden_dentry->d_inode);
+       ASSERT(hidden_dentry->d_inode->i_op);
+
+       if (hidden_dentry->d_inode->i_op->getxattr) {
+               encoded_name = (char *)name;
+               encoded_value = (char *)value;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_dentry->d_inode->i_sem);
+#endif
+               /* lock_kernel() already done by caller. */
+               err = hidden_dentry->d_inode->i_op->getxattr(hidden_dentry, encoded_name, encoded_value, size);
+               /* unlock_kernel() will be done by caller. */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_dentry->d_inode->i_sem);
+#endif
+       }
+       return err;
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_sem down
+ */
+STATIC int
+#if ((LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,21) \
+     && LINUX_VERSION_CODE <= KERNEL_VERSION(2,4,23)) \
+     || LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0))
+mini_fo_setxattr(struct dentry *dentry, const char *name, 
+                const void *value, size_t size, int flags)
+#else
+mini_fo_setxattr(struct dentry *dentry, const char *name, 
+                void *value, size_t size, int flags)
+#endif
+
+{
+       struct dentry *hidden_dentry = NULL;
+       int err = -EOPNOTSUPP;
+
+       /* Define these anyway, so we don't have as much ifdef'ed code. */
+       char *encoded_value = NULL;
+       char *encoded_name = NULL;
+
+       check_mini_fo_dentry(dentry);
+
+       if(exists_in_storage(dentry))
+               hidden_dentry = dtohd2(dentry);
+       else
+               hidden_dentry = dtohd(dentry);
+       
+       ASSERT(hidden_dentry);
+       ASSERT(hidden_dentry->d_inode);
+       ASSERT(hidden_dentry->d_inode->i_op);
+
+       if (hidden_dentry->d_inode->i_op->setxattr) {
+               encoded_name = (char *)name;
+               encoded_value = (char *)value;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_dentry->d_inode->i_sem);
+#endif
+               /* lock_kernel() already done by caller. */
+               err = hidden_dentry->d_inode->i_op->setxattr(hidden_dentry, encoded_name, encoded_value, size, flags);
+               /* unlock_kernel() will be done by caller. */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_dentry->d_inode->i_sem);
+#endif
+       }
+       return err;
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_sem down
+ */
+STATIC int
+mini_fo_removexattr(struct dentry *dentry, const char *name) {
+       struct dentry *hidden_dentry = NULL;
+       int err = -EOPNOTSUPP;
+       char *encoded_name;
+
+       check_mini_fo_dentry(dentry);
+
+       if(exists_in_storage(dentry))
+               hidden_dentry = dtohd2(dentry);
+       else
+               hidden_dentry = dtohd(dentry);
+       
+       ASSERT(hidden_dentry);
+       ASSERT(hidden_dentry->d_inode);
+       ASSERT(hidden_dentry->d_inode->i_op);
+
+       if (hidden_dentry->d_inode->i_op->removexattr) {
+               encoded_name = (char *)name;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_dentry->d_inode->i_sem);
+#endif
+               /* lock_kernel() already done by caller. */
+               err = hidden_dentry->d_inode->i_op->removexattr(hidden_dentry, encoded_name);
+               /* unlock_kernel() will be done by caller. */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_dentry->d_inode->i_sem);
+#endif
+       }
+       return err;
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_sem down
+ */
+STATIC int
+mini_fo_listxattr(struct dentry *dentry, char *list, size_t size) {
+       struct dentry *hidden_dentry = NULL;
+       int err = -EOPNOTSUPP;
+       char *encoded_list = NULL;
+
+       check_mini_fo_dentry(dentry);
+
+       if(exists_in_storage(dentry))
+               hidden_dentry = dtohd2(dentry);
+       else
+               hidden_dentry = dtohd(dentry);
+
+       ASSERT(hidden_dentry);
+       ASSERT(hidden_dentry->d_inode);
+       ASSERT(hidden_dentry->d_inode->i_op);
+
+       if (hidden_dentry->d_inode->i_op->listxattr) {
+               encoded_list = list;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&hidden_dentry->d_inode->i_mutex);
+#else
+               down(&hidden_dentry->d_inode->i_sem);
+#endif
+               /* lock_kernel() already done by caller. */
+               err = hidden_dentry->d_inode->i_op->listxattr(hidden_dentry, encoded_list, size);
+               /* unlock_kernel() will be done by caller. */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_dentry->d_inode->i_sem);
+#endif
+       }
+       return err;
+}
+# endif /* defined(XATTR) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20)) */
+
+struct inode_operations mini_fo_symlink_iops =
+       {
+               readlink:       mini_fo_readlink,
+               follow_link: mini_fo_follow_link,
+               /* mk: permission:      mini_fo_permission, */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+               revalidate:     mini_fo_inode_revalidate,
+#endif
+               setattr:        mini_fo_setattr,
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               getattr:        mini_fo_getattr,
+               put_link:       mini_fo_put_link,
+#endif
+
+#if defined(XATTR) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20))
+               setxattr:       mini_fo_setxattr,
+               getxattr:       mini_fo_getxattr,
+               listxattr:      mini_fo_listxattr,
+               removexattr: mini_fo_removexattr
+# endif /* defined(XATTR) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20)) */
+       };
+
+struct inode_operations mini_fo_dir_iops =
+       {
+               create: mini_fo_create,
+               lookup: mini_fo_lookup,
+               link:   mini_fo_link,
+               unlink: mini_fo_unlink,
+               symlink:        mini_fo_symlink,
+               mkdir:  mini_fo_mkdir,
+               rmdir:  mini_fo_rmdir,
+               mknod:  mini_fo_mknod,
+               rename: mini_fo_rename,
+               /* no readlink/follow_link for non-symlinks */
+               // off because we have setattr
+               //    truncate: mini_fo_truncate,
+               /* mk:permission:       mini_fo_permission, */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+               revalidate:     mini_fo_inode_revalidate,
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               getattr:        mini_fo_getattr,
+#endif
+               setattr:        mini_fo_setattr,
+#if defined(XATTR) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20))
+               setxattr:       mini_fo_setxattr,
+               getxattr:       mini_fo_getxattr,
+               listxattr:      mini_fo_listxattr,
+               removexattr: mini_fo_removexattr
+# endif /* XATTR && LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20) */
+       };
+
+struct inode_operations mini_fo_main_iops =
+       {
+               /* permission:  mini_fo_permission, */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+               revalidate:     mini_fo_inode_revalidate,
+#endif
+               setattr:        mini_fo_setattr,
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               getattr:        mini_fo_getattr,
+#endif
+#if defined(XATTR) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20))
+               setxattr:       mini_fo_setxattr,
+               getxattr:       mini_fo_getxattr,
+               listxattr:      mini_fo_listxattr,
+               removexattr:    mini_fo_removexattr
+# endif /* XATTR && LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,20) */
+       };
diff -urN linux-2.6.21.1.old/fs/mini_fo/main.c linux-2.6.21.1.dev/fs/mini_fo/main.c
--- linux-2.6.21.1.old/fs/mini_fo/main.c        1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/main.c        2007-05-26 21:01:26.164329720 +0200
@@ -0,0 +1,423 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "fist.h"
+#include "mini_fo.h"
+#include <linux/module.h>
+
+/* This definition must only appear after we include <linux/module.h> */
+#ifndef MODULE_LICENSE
+# define MODULE_LICENSE(bison)
+#endif /* not MODULE_LICENSE */
+
+/*
+ * This is the mini_fo tri interpose function, which extends the
+ * functionality of the regular interpose by interposing a higher
+ * level inode on top of two lower level ones: the base filesystem
+ * inode and the storage filesystem inode.
+ *
+ *  sb we pass is mini_fo's super_block
+ */
+int
+mini_fo_tri_interpose(dentry_t *hidden_dentry,
+                     dentry_t *hidden_sto_dentry,
+                     dentry_t *dentry, super_block_t *sb, int flag)
+{
+       inode_t *hidden_inode = NULL;
+       inode_t *hidden_sto_inode = NULL; /* store corresponding storage inode */
+       int err = 0;
+       inode_t *inode;
+
+       /* Pointer to hidden_sto_inode if exists, else to hidden_inode.
+        * This is used to copy the attributes of the correct inode. */
+       inode_t *master_inode;
+
+       if(hidden_dentry)
+               hidden_inode = hidden_dentry->d_inode;
+       if(hidden_sto_dentry)
+               hidden_sto_inode = hidden_sto_dentry->d_inode;
+
+       ASSERT(dentry->d_inode == NULL);
+
+       /* mk: One of the inodes associated with the dentrys is likely to
+        * be NULL, so carefull:
+        */
+       ASSERT((hidden_inode != NULL) || (hidden_sto_inode != NULL));
+
+       if(hidden_sto_inode)
+               master_inode = hidden_sto_inode;
+       else
+               master_inode = hidden_inode;
+
+       /*
+        * We allocate our new inode below, by calling iget.
+        * iget will call our read_inode which will initialize some
+        * of the new inode's fields
+        */
+
+       /*
+        * original: inode = iget(sb, hidden_inode->i_ino);
+        */
+       inode = iget(sb, iunique(sb, 25));
+       if (!inode) {
+               err = -EACCES;          /* should be impossible??? */
+               goto out;
+       }
+
+       /*
+        * interpose the inode if not already interposed
+        *   this is possible if the inode is being reused
+        * XXX: what happens if we get_empty_inode() but there's another already?
+        * for now, ASSERT() that this can't happen; fix later.
+        */
+       if (itohi(inode) != NULL) {
+               printk(KERN_CRIT "mini_fo_tri_interpose: itohi(inode) != NULL.\n");
+       }
+       if (itohi2(inode) != NULL) {
+               printk(KERN_CRIT "mini_fo_tri_interpose: itohi2(inode) != NULL.\n");
+       }
+
+       /* mk: Carefull, igrab can't handle NULL inodes (ok, why should it?), so
+        * we need to check here:
+        */
+       if(hidden_inode)
+               itohi(inode) = igrab(hidden_inode);
+       else
+               itohi(inode) = NULL;
+
+       if(hidden_sto_inode)
+               itohi2(inode) = igrab(hidden_sto_inode);
+       else
+               itohi2(inode) = NULL;
+
+
+       /* Use different set of inode ops for symlinks & directories*/
+       if (S_ISLNK(master_inode->i_mode))
+               inode->i_op = &mini_fo_symlink_iops;
+       else if (S_ISDIR(master_inode->i_mode))
+               inode->i_op = &mini_fo_dir_iops;
+
+       /* Use different set of file ops for directories */
+       if (S_ISDIR(master_inode->i_mode))
+               inode->i_fop = &mini_fo_dir_fops;
+
+       /* properly initialize special inodes */
+       if (S_ISBLK(master_inode->i_mode) || S_ISCHR(master_inode->i_mode) ||
+           S_ISFIFO(master_inode->i_mode) || S_ISSOCK(master_inode->i_mode)) {
+               init_special_inode(inode, master_inode->i_mode, master_inode->i_rdev);
+       }
+
+       /* Fix our inode's address operations to that of the lower inode */
+       if (inode->i_mapping->a_ops != master_inode->i_mapping->a_ops) {
+               inode->i_mapping->a_ops = master_inode->i_mapping->a_ops;
+       }
+
+       /* only (our) lookup wants to do a d_add */
+       if (flag)
+               d_add(dentry, inode);
+       else
+               d_instantiate(dentry, inode);
+
+       ASSERT(dtopd(dentry) != NULL);
+
+       /* all well, copy inode attributes */
+       fist_copy_attr_all(inode, master_inode);
+
+ out:
+       return err;
+}
+
+/* parse mount options "base=" and "sto=" */
+dentry_t *
+mini_fo_parse_options(super_block_t *sb, char *options)
+{
+       dentry_t *hidden_root = ERR_PTR(-EINVAL);
+       dentry_t *hidden_root2 = ERR_PTR(-EINVAL);
+       struct nameidata nd, nd2; 
+       char *name, *tmp, *end;
+       int err = 0;
+
+       /* We don't want to go off the end of our arguments later on. */
+       for (end = options; *end; end++);
+
+       while (options < end) {
+               tmp = options;
+               while (*tmp && *tmp != ',')
+                       tmp++;
+               *tmp = '\0';
+               if (!strncmp("base=", options, 5)) {
+                       name = options + 5;
+                       printk(KERN_INFO "mini_fo: using base directory: %s\n", name);
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+                       if (path_init(name, LOOKUP_FOLLOW, &nd))
+                               err = path_walk(name, &nd);
+#else
+                       err = path_lookup(name, LOOKUP_FOLLOW, &nd);
+#endif
+                       if (err) {
+                               printk(KERN_CRIT "mini_fo: error accessing hidden directory '%s'\n", name);
+                               hidden_root = ERR_PTR(err);
+                               goto out;
+                       }
+                       hidden_root = nd.dentry;
+                       stopd(sb)->base_dir_dentry = nd.dentry;
+                       stopd(sb)->hidden_mnt = nd.mnt;
+
+               } else if(!strncmp("sto=", options, 4)) {
+                       /* parse the storage dir */
+                       name = options + 4;
+                       printk(KERN_INFO "mini_fo: using storage directory: %s\n", name);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+                       if(path_init(name, LOOKUP_FOLLOW, &nd2))
+                               err = path_walk(name, &nd2);
+#else
+                        err = path_lookup(name, LOOKUP_FOLLOW, &nd2);
+#endif
+                       if(err) {
+                               printk(KERN_CRIT "mini_fo: error accessing hidden storage directory '%s'\n", name);
+
+                               hidden_root2 = ERR_PTR(err);
+                               goto out;
+                       }
+                       hidden_root2 = nd2.dentry;
+                       stopd(sb)->storage_dir_dentry = nd2.dentry;
+                       stopd(sb)->hidden_mnt2 = nd2.mnt;
+                       stohs2(sb) = hidden_root2->d_sb;
+
+                       /* validate storage dir, this is done in 
+                        * mini_fo_read_super for the base directory.
+                        */
+                       if (IS_ERR(hidden_root2)) {
+                               printk(KERN_WARNING "mini_fo_parse_options: storage dentry lookup failed (err = %ld)\n", PTR_ERR(hidden_root2));
+                               goto out;
+                       }
+                       if (!hidden_root2->d_inode) {
+                               printk(KERN_WARNING "mini_fo_parse_options: no storage dir to interpose on.\n");
+                               goto out;
+                       }
+                       stohs2(sb) = hidden_root2->d_sb;
+               } else {
+                       printk(KERN_WARNING "mini_fo: unrecognized option '%s'\n", options);
+                       hidden_root = ERR_PTR(-EINVAL);
+                       goto out;
+               }
+               options = tmp + 1;
+       }
+
+ out:
+       if(IS_ERR(hidden_root2))
+               return hidden_root2;
+       return hidden_root;
+}
+
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+static int
+#else
+super_block_t *
+#endif
+mini_fo_read_super(super_block_t *sb, void *raw_data, int silent)
+{
+       dentry_t *hidden_root;
+       int err = 0;
+
+       if (!raw_data) {
+               printk(KERN_WARNING "mini_fo_read_super: missing argument\n");
+               err = -EINVAL;
+               goto out;
+       }
+       /*
+        * Allocate superblock private data
+        */
+       __stopd(sb) = kmalloc(sizeof(struct mini_fo_sb_info), GFP_KERNEL);
+       if (!stopd(sb)) {
+               printk(KERN_WARNING "%s: out of memory\n", __FUNCTION__);
+               err = -ENOMEM;
+               goto out;
+       }
+       stohs(sb) = NULL;
+
+       hidden_root = mini_fo_parse_options(sb, raw_data);
+       if (IS_ERR(hidden_root)) {
+               printk(KERN_WARNING "mini_fo_read_super: lookup_dentry failed (err = %ld)\n", PTR_ERR(hidden_root));
+               err = PTR_ERR(hidden_root);
+               goto out_free;
+       }
+       if (!hidden_root->d_inode) {
+               printk(KERN_WARNING "mini_fo_read_super: no directory to interpose on\n");
+               goto out_free;
+       }
+       stohs(sb) = hidden_root->d_sb;
+
+       /*
+        * Linux 2.4.2-ac3 and beyond has code in
+        * mm/filemap.c:generic_file_write() that requires sb->s_maxbytes
+        * to be populated.  If not set, all write()s under that sb will
+        * return 0.
+        *
+        * Linux 2.4.4+ automatically sets s_maxbytes to MAX_NON_LFS;
+        * the filesystem should override it only if it supports LFS.
+        */
+       /* non-SCA code is good to go with LFS */
+       sb->s_maxbytes = hidden_root->d_sb->s_maxbytes;
+
+       sb->s_op = &mini_fo_sops;
+       /*
+        * we can't use d_alloc_root if we want to use
+        * our own interpose function unchanged,
+        * so we simply replicate *most* of the code in d_alloc_root here
+        */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+       sb->s_root = d_alloc(NULL, &(const struct qstr) { "/", 1, 0 });
+#else
+       sb->s_root = d_alloc(NULL, &(const struct qstr){hash: 0, name: "/", len : 1});
+#endif
+       if (IS_ERR(sb->s_root)) {
+               printk(KERN_WARNING "mini_fo_read_super: d_alloc failed\n");
+               err = -ENOMEM;
+               goto out_dput;
+       }
+
+       sb->s_root->d_op = &mini_fo_dops;
+       sb->s_root->d_sb = sb;
+       sb->s_root->d_parent = sb->s_root;
+
+       /* link the upper and lower dentries */
+       __dtopd(sb->s_root) = (struct mini_fo_dentry_info *) 
+               kmalloc(sizeof(struct mini_fo_dentry_info), GFP_KERNEL);
+       if (!dtopd(sb->s_root)) {
+               err = -ENOMEM;
+               goto out_dput2;
+       }
+       dtopd(sb->s_root)->state = MODIFIED;
+       dtohd(sb->s_root) = hidden_root;
+
+       /* fanout relevant, interpose on storage root dentry too */
+       dtohd2(sb->s_root) = stopd(sb)->storage_dir_dentry;
+
+       /* ...and call tri-interpose to interpose root dir inodes
+        * if (mini_fo_interpose(hidden_root, sb->s_root, sb, 0))
+        */
+       if(mini_fo_tri_interpose(hidden_root, dtohd2(sb->s_root), sb->s_root, sb, 0))
+               goto out_dput2;
+
+       /* initalize the wol list */
+       itopd(sb->s_root->d_inode)->deleted_list_size = -1;
+       itopd(sb->s_root->d_inode)->renamed_list_size = -1;
+       meta_build_lists(sb->s_root);
+
+       goto out;
+
+ out_dput2:
+       dput(sb->s_root);
+ out_dput:
+       dput(hidden_root);
+       dput(dtohd2(sb->s_root)); /* release the hidden_sto_dentry too */
+ out_free:
+       kfree(stopd(sb));
+       __stopd(sb) = NULL;
+ out:
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+        return err;
+#else
+        if (err) {
+               return ERR_PTR(err);
+        } else {
+               return sb;
+        }
+#endif
+}
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+static int mini_fo_get_sb(struct file_system_type *fs_type,
+                                         int flags, const char *dev_name,
+                                         void *raw_data, struct vfsmount *mnt) 
+{
+       return get_sb_nodev(fs_type, flags, raw_data, mini_fo_read_super, mnt);
+}
+#else
+static struct super_block *mini_fo_get_sb(struct file_system_type *fs_type,
+                                         int flags, const char *dev_name,
+                                         void *raw_data) 
+{
+       return get_sb_nodev(fs_type, flags, raw_data, mini_fo_read_super);
+}
+#endif
+
+void mini_fo_kill_block_super(struct super_block *sb)
+{
+       generic_shutdown_super(sb);
+       /*
+        *      XXX: BUG: Halcrow: Things get unstable sometime after this point:
+        *      lib/rwsem-spinlock.c:127: spin_is_locked on uninitialized
+        *      fs/fs-writeback.c:402: spin_lock(fs/super.c:a0381828) already
+        *      locked by fs/fs-writeback.c/402
+        *
+        *      Apparently, someone's not releasing a lock on sb_lock...
+        */
+}
+
+static struct file_system_type mini_fo_fs_type = {
+       .owner          = THIS_MODULE,
+       .name           = "mini_fo",
+       .get_sb         = mini_fo_get_sb,
+       .kill_sb        = mini_fo_kill_block_super,
+       .fs_flags       = 0,
+};
+
+
+#else
+static DECLARE_FSTYPE(mini_fo_fs_type, "mini_fo", mini_fo_read_super, 0);
+#endif
+
+static int __init init_mini_fo_fs(void)
+{
+       printk("Registering mini_fo version $Id$\n");
+       return register_filesystem(&mini_fo_fs_type);
+}
+static void __exit exit_mini_fo_fs(void)
+{
+       printk("Unregistering mini_fo version $Id$\n");
+       unregister_filesystem(&mini_fo_fs_type);
+}
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+EXPORT_NO_SYMBOLS;
+#endif
+
+MODULE_AUTHOR("Erez Zadok <ezk@cs.sunysb.edu>");
+MODULE_DESCRIPTION("FiST-generated mini_fo filesystem");
+MODULE_LICENSE("GPL");
+
+/* MODULE_PARM(fist_debug_var, "i"); */
+/* MODULE_PARM_DESC(fist_debug_var, "Debug level"); */
+
+module_init(init_mini_fo_fs)
+module_exit(exit_mini_fo_fs)
diff -urN linux-2.6.21.1.old/fs/mini_fo/Makefile linux-2.6.21.1.dev/fs/mini_fo/Makefile
--- linux-2.6.21.1.old/fs/mini_fo/Makefile      1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/Makefile      2007-05-26 21:01:26.164329720 +0200
@@ -0,0 +1,17 @@
+#
+# Makefile for mini_fo 2.4 and 2.6 Linux kernels
+#
+# Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version
+# 2 of the License, or (at your option) any later version.
+#
+
+obj-$(CONFIG_MINI_FO) := mini_fo.o
+mini_fo-objs   := meta.o dentry.o file.o inode.o main.o super.o state.o aux.o
+
+# dependencies
+${mini_fo-objs}: mini_fo.h fist.h
+
diff -urN linux-2.6.21.1.old/fs/mini_fo/meta.c linux-2.6.21.1.dev/fs/mini_fo/meta.c
--- linux-2.6.21.1.old/fs/mini_fo/meta.c        1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/meta.c        2007-05-26 21:01:26.166329416 +0200
@@ -0,0 +1,1000 @@
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif /* HAVE_CONFIG_H */
+#include "fist.h"
+#include "mini_fo.h"
+
+int meta_build_lists(dentry_t *dentry) 
+{
+       struct mini_fo_inode_info *inode_info;
+
+       dentry_t *meta_dentry = 0;
+       file_t *meta_file = 0;
+       mm_segment_t old_fs;
+       void *buf;
+
+       int bytes, len;
+       struct vfsmount *meta_mnt;
+       char *entry;
+
+       inode_info = itopd(dentry->d_inode);
+       if(!(inode_info->deleted_list_size == -1 &&
+            inode_info->renamed_list_size == -1)) {
+               printk(KERN_CRIT "mini_fo: meta_build_lists: \
+                                  Error, list(s) not virgin.\n");
+               return -1;
+       }
+
+       /* init our meta lists */
+       INIT_LIST_HEAD(&inode_info->deleted_list);
+       inode_info->deleted_list_size = 0;
+
+       INIT_LIST_HEAD(&inode_info->renamed_list);
+       inode_info->renamed_list_size = 0;
+
+       /* might there be a META-file? */
+       if(dtohd2(dentry) && dtohd2(dentry)->d_inode) {
+               meta_dentry = lookup_one_len(META_FILENAME,
+                                            dtohd2(dentry), 
+                                            strlen(META_FILENAME));
+               if(!meta_dentry->d_inode) {
+                       dput(meta_dentry);
+                       goto out_ok;
+               }
+               /* $%& err, is this correct? */
+               meta_mnt = stopd(dentry->d_inode->i_sb)->hidden_mnt2;
+               mntget(meta_mnt);
+               
+
+               /* open META-file for reading */
+               meta_file = dentry_open(meta_dentry, meta_mnt, 0x0);
+               if(!meta_file || IS_ERR(meta_file)) {
+                       printk(KERN_CRIT "mini_fo: meta_build_lists: \
+                                          ERROR opening META file.\n");
+                       goto out_err;
+               }
+
+               /* check if fs supports reading */
+               if(!meta_file->f_op->read) {
+                       printk(KERN_CRIT "mini_fo: meta_build_lists: \
+                                          ERROR, fs does not support reading.\n");
+                       goto out_err_close;
+               }
+
+               /* allocate a page for transfering the data */
+               buf = (void *) __get_free_page(GFP_KERNEL);
+               if(!buf) {
+                       printk(KERN_CRIT "mini_fo: meta_build_lists: \
+                                          ERROR, out of mem.\n");
+                       goto out_err_close;
+               }
+               meta_file->f_pos = 0;
+               old_fs = get_fs();
+               set_fs(KERNEL_DS);
+               do {
+                       char *c;
+                       bytes = meta_file->f_op->read(meta_file, buf, PAGE_SIZE, &meta_file->f_pos);
+                       if(bytes == PAGE_SIZE) {
+                               /* trim a cut off filename and adjust f_pos to get it next time */
+                               for(c = (char*) buf+PAGE_SIZE;
+                                   *c != '\n';
+                                   c--, bytes--, meta_file->f_pos--);
+                       }
+                       entry = (char *) buf;
+                       while(entry < (char *) buf+bytes) {
+
+                               char *old_path;
+                               char *dir_name;
+                               int old_len, new_len;
+
+                               /* len without '\n'*/
+                               len = (int) (strchr(entry, '\n') - entry);
+                               switch (*entry) {
+                               case 'D':
+                                       /* format: "D filename" */
+                                       meta_list_add_d_entry(dentry, 
+                                                             entry+2, 
+                                                             len-2);
+                                       break;
+                               case 'R':
+                                       /* format: "R path/xy/dir newDir" */
+                                       old_path = entry+2;
+                                       dir_name = strchr(old_path, ' ') + 1;
+                                       old_len =  dir_name - old_path - 1;
+                                       new_len = ((int) entry) + len - ((int ) dir_name);
+                                       meta_list_add_r_entry(dentry, 
+                                                             old_path, 
+                                                             old_len,
+                                                             dir_name, 
+                                                             new_len);
+                                       break;
+                               default:
+                                       /* unknown entry type detected */
+                                       break;
+                               }
+                               entry += len+1;
+                       }
+
+               } while(meta_file->f_pos < meta_dentry->d_inode->i_size);
+
+               free_page((unsigned long) buf);
+               set_fs(old_fs);
+               fput(meta_file);
+       }
+       goto out_ok;
+
+ out_err_close:
+       fput(meta_file);
+ out_err:
+       mntput(meta_mnt);
+       dput(meta_dentry);
+       return -1;
+ out_ok:
+       return 1; /* check this!!! inode_info->wol_size; */ 
+}
+
+/* cleanups up all lists and free's the mem by dentry */
+int meta_put_lists(dentry_t *dentry) 
+{
+       if(!dentry || !dentry->d_inode) {
+               printk("mini_fo: meta_put_lists: invalid dentry passed.\n");
+               return -1;
+       }
+       return __meta_put_lists(dentry->d_inode);
+}
+
+/* cleanups up all lists and free's the mem by inode */
+int __meta_put_lists(inode_t *inode) 
+{
+       int err = 0;
+       if(!inode || !itopd(inode)) {
+               printk("mini_fo: __meta_put_lists: invalid inode passed.\n");
+               return -1;
+       }
+       err = __meta_put_d_list(inode);
+       err |= __meta_put_r_list(inode);
+       return err;
+}
+
+int meta_sync_lists(dentry_t *dentry)
+{
+       int err = 0;
+       if(!dentry || !dentry->d_inode) {
+               printk("mini_fo: meta_sync_lists: \
+                        invalid dentry passed.\n");
+               return -1;
+       }
+       err = meta_sync_d_list(dentry, 0);
+       err |= meta_sync_r_list(dentry, 1);
+       return err;
+}
+
+
+/* remove all D entries from the renamed list and free the mem */
+int __meta_put_d_list(inode_t *inode) 
+{
+       struct list_head *tmp;
+        struct deleted_entry *del_entry;
+        struct mini_fo_inode_info *inode_info;
+       
+       if(!inode || !itopd(inode)) {
+               printk(KERN_CRIT "mini_fo: __meta_put_d_list: \
+                                  invalid inode passed.\n");
+               return -1;
+       }
+       inode_info = itopd(inode);
+       
+        /* nuke the DELETED-list */
+        if(inode_info->deleted_list_size <= 0)
+               return 0;
+
+       while(!list_empty(&inode_info->deleted_list)) {
+               tmp = inode_info->deleted_list.next;
+               list_del(tmp);
+               del_entry = list_entry(tmp, struct deleted_entry, list);
+               kfree(del_entry->name);
+               kfree(del_entry);
+       }
+       inode_info->deleted_list_size = 0;
+       
+       return 0;
+}
+
+/* remove all R entries from the renamed list and free the mem */
+int __meta_put_r_list(inode_t *inode) 
+{
+       struct list_head *tmp;
+       struct renamed_entry *ren_entry;
+        struct mini_fo_inode_info *inode_info;
+       
+       if(!inode || !itopd(inode)) {
+               printk(KERN_CRIT "mini_fo: meta_put_r_list: invalid inode.\n");
+               return -1;
+       }
+       inode_info = itopd(inode);
+       
+        /* nuke the RENAMED-list */
+        if(inode_info->renamed_list_size <= 0) 
+               return 0;
+
+       while(!list_empty(&inode_info->renamed_list)) {
+               tmp = inode_info->renamed_list.next;
+               list_del(tmp);
+               ren_entry = list_entry(tmp, struct renamed_entry, list);
+               kfree(ren_entry->new_name);
+               kfree(ren_entry->old_name);
+               kfree(ren_entry);
+       }
+       inode_info->renamed_list_size = 0;
+       
+       return 0;
+}
+
+int meta_add_d_entry(dentry_t *dentry, const char *name, int len)
+{
+       int err = 0;
+       err = meta_list_add_d_entry(dentry, name, len);
+       err |= meta_write_d_entry(dentry,name,len);
+       return err;     
+}
+
+/* add a D entry to the deleted list */
+int meta_list_add_d_entry(dentry_t *dentry, const char *name, int len) 
+{
+        struct deleted_entry *del_entry;
+        struct mini_fo_inode_info *inode_info;
+
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: meta_list_add_d_entry: \
+                                  invalid dentry passed.\n");
+               return -1;
+       }
+       inode_info = itopd(dentry->d_inode);
+
+        if(inode_info->deleted_list_size < 0)
+                return -1;
+
+        del_entry = (struct deleted_entry *) 
+               kmalloc(sizeof(struct deleted_entry), GFP_KERNEL);
+        del_entry->name = (char*) kmalloc(len, GFP_KERNEL);
+        if(!del_entry || !del_entry->name) {
+                printk(KERN_CRIT "mini_fo: meta_list_add_d_entry: \
+                                  out of mem.\n");
+               kfree(del_entry->name);
+               kfree(del_entry);
+                return -ENOMEM;
+        }
+
+        strncpy(del_entry->name, name, len);
+        del_entry->len = len;
+
+        list_add(&del_entry->list, &inode_info->deleted_list);
+        inode_info->deleted_list_size++;
+        return 0;
+}
+
+int meta_add_r_entry(dentry_t *dentry, 
+                         const char *old_name, int old_len, 
+                         const char *new_name, int new_len)
+{
+       int err = 0;
+       err = meta_list_add_r_entry(dentry, 
+                                   old_name, old_len,
+                                   new_name, new_len);
+       err |= meta_write_r_entry(dentry,
+                                 old_name, old_len,
+                                 new_name, new_len);
+       return err;
+}
+
+/* add a R entry to the renamed list */
+int meta_list_add_r_entry(dentry_t *dentry, 
+                         const char *old_name, int old_len, 
+                         const char *new_name, int new_len)
+{
+        struct renamed_entry *ren_entry;
+        struct mini_fo_inode_info *inode_info;
+
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: meta_list_add_r_entry: \
+                                  invalid dentry passed.\n");
+               return -1;
+       }
+       inode_info = itopd(dentry->d_inode);
+
+        if(inode_info->renamed_list_size < 0)
+                return -1;
+
+        ren_entry = (struct renamed_entry *) 
+               kmalloc(sizeof(struct renamed_entry), GFP_KERNEL);
+        ren_entry->old_name = (char*) kmalloc(old_len, GFP_KERNEL);
+        ren_entry->new_name = (char*) kmalloc(new_len, GFP_KERNEL);
+
+        if(!ren_entry || !ren_entry->old_name || !ren_entry->new_name) {
+                printk(KERN_CRIT "mini_fo: meta_list_add_r_entry: \
+                                  out of mem.\n");
+               kfree(ren_entry->new_name);
+               kfree(ren_entry->old_name);
+               kfree(ren_entry);
+                return -ENOMEM;
+        }
+
+        strncpy(ren_entry->old_name, old_name, old_len);
+        ren_entry->old_len = old_len;
+        strncpy(ren_entry->new_name, new_name, new_len);
+        ren_entry->new_len = new_len;
+
+        list_add(&ren_entry->list, &inode_info->renamed_list);
+        inode_info->renamed_list_size++;
+        return 0;
+}
+
+
+int meta_remove_r_entry(dentry_t *dentry, const char *name, int len)
+{
+       int err = 0;
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT 
+                      "mini_fo: meta_remove_r_entry: \
+                        invalid dentry passed.\n");
+               return -1;
+       }
+
+       err = meta_list_remove_r_entry(dentry, name, len);
+       err |= meta_sync_lists(dentry);
+       return err;
+}
+
+int meta_list_remove_r_entry(dentry_t *dentry, const char *name, int len)
+{
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT 
+                      "mini_fo: meta_list_remove_r_entry: \
+                        invalid dentry passed.\n");
+               return -1;
+       }
+       return __meta_list_remove_r_entry(dentry->d_inode, name, len);
+}
+
+int __meta_list_remove_r_entry(inode_t *inode, const char *name, int len)
+{
+       struct list_head *tmp;
+        struct renamed_entry *ren_entry;
+        struct mini_fo_inode_info *inode_info;
+
+       if(!inode || !itopd(inode))
+               printk(KERN_CRIT 
+                      "mini_fo: __meta_list_remove_r_entry: \
+                        invalid inode passed.\n");
+       inode_info = itopd(inode);
+
+        if(inode_info->renamed_list_size < 0)
+                return -1;
+        if(inode_info->renamed_list_size == 0)
+                return 1;
+       
+       list_for_each(tmp, &inode_info->renamed_list) {
+               ren_entry = list_entry(tmp, struct renamed_entry, list);
+               if(ren_entry->new_len != len)
+                       continue;
+               
+               if(!strncmp(ren_entry->new_name, name, len)) {
+                       list_del(tmp);
+                       kfree(ren_entry->new_name);
+                       kfree(ren_entry->old_name);
+                       kfree(ren_entry);
+                       inode_info->renamed_list_size--;
+                       return 0;
+               }
+       }
+       return 1;
+}
+
+
+/* append a single D entry to the meta file */
+int meta_write_d_entry(dentry_t *dentry, const char *name, int len) 
+{
+       dentry_t *meta_dentry = 0;
+        file_t *meta_file = 0;
+        mm_segment_t old_fs;
+
+        int bytes, err;
+        struct vfsmount *meta_mnt = 0;
+        char *buf;
+
+       err = 0;
+
+       if(itopd(dentry->d_inode)->deleted_list_size < 0) {
+               err = -1;
+               goto out;
+       }
+
+       if(dtopd(dentry)->state == UNMODIFIED) {
+                err = build_sto_structure(dentry->d_parent, dentry);
+                if(err) {
+                        printk(KERN_CRIT "mini_fo: meta_write_d_entry: \
+                                          build_sto_structure failed.\n");
+                       goto out;
+                }
+        }
+       meta_dentry = lookup_one_len(META_FILENAME, 
+                                    dtohd2(dentry), strlen (META_FILENAME));
+
+       /* We need to create a META-file */
+        if(!meta_dentry->d_inode) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               vfs_create(dtohd2(dentry)->d_inode,
+                          meta_dentry, 
+                          S_IRUSR | S_IWUSR,
+                          NULL);
+#else
+                vfs_create(dtohd2(dentry)->d_inode,
+                          meta_dentry, 
+                          S_IRUSR | S_IWUSR);
+#endif
+       }
+        /* open META-file for writing */
+        meta_file = dentry_open(meta_dentry, meta_mnt, 0x1);
+        if(!meta_file || IS_ERR(meta_file)) {
+                printk(KERN_CRIT "mini_fo: meta_write_d_entry: \
+                                  ERROR opening meta file.\n");
+                mntput(meta_mnt); /* $%& is this necessary? */
+                dput(meta_dentry);
+               err = -1;
+                goto out;
+        }
+
+        /* check if fs supports writing */
+        if(!meta_file->f_op->write) {
+                printk(KERN_CRIT "mini_fo: meta_write_d_entry: \
+                                  ERROR, fs does not support writing.\n");
+                goto out_err_close;
+        }
+
+       meta_file->f_pos = meta_dentry->d_inode->i_size; /* append */
+        old_fs = get_fs();
+        set_fs(KERNEL_DS);
+
+       /* size: len for name, 1 for \n and 2 for "D " */
+       buf = (char *) kmalloc(len+3, GFP_KERNEL);
+       if (!buf) {
+               printk(KERN_CRIT "mini_fo: meta_write_d_entry: \
+                                  out of mem.\n");
+               return -ENOMEM;
+       }
+                     
+       buf[0] = 'D';
+       buf[1] = ' ';
+       strncpy(buf+2, name, len);
+       buf[len+2] = '\n';
+       bytes = meta_file->f_op->write(meta_file, buf, len+3, 
+                                      &meta_file->f_pos);
+       if(bytes != len+3) {
+               printk(KERN_CRIT "mini_fo: meta_write_d_entry: \
+                                  ERROR writing.\n");
+               err = -1;
+       }
+       kfree(buf);
+       set_fs(old_fs);
+
+ out_err_close:
+       fput(meta_file);
+ out:
+       return err;
+}
+
+/* append a single R entry to the meta file */
+int meta_write_r_entry(dentry_t *dentry, 
+                      const char *old_name, int old_len, 
+                      const char *new_name, int new_len) 
+{
+       dentry_t *meta_dentry = 0;
+        file_t *meta_file = 0;
+        mm_segment_t old_fs;
+
+        int bytes, err, buf_len;
+       struct vfsmount *meta_mnt = 0;
+        char *buf;
+
+
+       err = 0;
+
+       if(itopd(dentry->d_inode)->renamed_list_size < 0) {
+               err = -1;
+               goto out;
+       }
+
+       /* build the storage structure? */
+       if(dtopd(dentry)->state == UNMODIFIED) {
+                err = build_sto_structure(dentry->d_parent, dentry);
+                if(err) {
+                        printk(KERN_CRIT "mini_fo: meta_write_r_entry: \
+                                          build_sto_structure failed.\n");
+                       goto out;
+                }
+        }
+       meta_dentry = lookup_one_len(META_FILENAME, 
+                                    dtohd2(dentry), 
+                                    strlen (META_FILENAME));
+        if(!meta_dentry->d_inode) {
+                /* We need to create a META-file */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+                vfs_create(dtohd2(dentry)->d_inode, 
+                          meta_dentry, S_IRUSR | S_IWUSR, NULL);
+#else
+                vfs_create(dtohd2(dentry)->d_inode, 
+                          meta_dentry, S_IRUSR | S_IWUSR);
+#endif
+       }
+        /* open META-file for writing */
+        meta_file = dentry_open(meta_dentry, meta_mnt, 0x1);
+        if(!meta_file || IS_ERR(meta_file)) {
+                printk(KERN_CRIT "mini_fo: meta_write_r_entry: \
+                                  ERROR opening meta file.\n");
+                mntput(meta_mnt);
+                dput(meta_dentry);
+               err = -1;
+                goto out;
+        }
+
+        /* check if fs supports writing */
+        if(!meta_file->f_op->write) {
+                printk(KERN_CRIT "mini_fo: meta_write_r_entry: \
+                                  ERROR, fs does not support writing.\n");
+                goto out_err_close;
+        }
+
+       meta_file->f_pos = meta_dentry->d_inode->i_size; /* append */
+        old_fs = get_fs();
+        set_fs(KERNEL_DS);
+
+       /* size: 2 for "R ", old_len+new_len for names, 1 blank+1 \n */
+       buf_len = old_len + new_len + 4;
+       buf = (char *) kmalloc(buf_len, GFP_KERNEL);
+       if (!buf) {
+               printk(KERN_CRIT "mini_fo: meta_write_r_entry: out of mem.\n");
+               return -ENOMEM;
+       }
+                     
+       buf[0] = 'R';
+       buf[1] = ' ';
+       strncpy(buf + 2, old_name, old_len);
+       buf[old_len + 2] = ' ';
+       strncpy(buf + old_len + 3, new_name, new_len);
+       buf[buf_len -1] = '\n';
+       bytes = meta_file->f_op->write(meta_file, buf, buf_len, &meta_file->f_pos);
+       if(bytes != buf_len) {
+               printk(KERN_CRIT "mini_fo: meta_write_r_entry: ERROR writing.\n");
+               err = -1;
+       }
+       
+       kfree(buf);
+       set_fs(old_fs);
+
+ out_err_close:
+       fput(meta_file);
+ out:
+       return err;
+}
+
+/* sync D list to disk, append data if app_flag is 1 */
+/* check the meta_mnt, which seems not to be used (properly)  */
+
+int meta_sync_d_list(dentry_t *dentry, int app_flag)
+{
+       dentry_t *meta_dentry;
+        file_t *meta_file;
+        mm_segment_t old_fs;
+       
+        int bytes, err;
+        struct vfsmount *meta_mnt;
+        char *buf;
+
+       struct list_head *tmp;
+        struct deleted_entry *del_entry;
+        struct mini_fo_inode_info *inode_info;
+
+       err = 0;
+       meta_file=0;
+       meta_mnt=0;
+       
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                  invalid inode passed.\n");
+               err = -1;
+               goto out;
+       }
+       inode_info = itopd(dentry->d_inode);
+       
+        if(inode_info->deleted_list_size < 0) {
+               err = -1;
+               goto out;
+       }
+       
+       /* ok, there is something to sync */
+
+       /* build the storage structure? */
+        if(!dtohd2(dentry) && !itohi2(dentry->d_inode)) {
+                err = build_sto_structure(dentry->d_parent, dentry);
+                if(err) {
+                        printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                          build_sto_structure failed.\n");
+                       goto out;
+                }
+        }
+       meta_dentry = lookup_one_len(META_FILENAME, 
+                                    dtohd2(dentry), 
+                                    strlen(META_FILENAME));
+        if(!meta_dentry->d_inode) {
+                /* We need to create a META-file */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+                vfs_create(dtohd2(dentry)->d_inode, 
+                          meta_dentry, S_IRUSR | S_IWUSR, NULL);
+#else
+                vfs_create(dtohd2(dentry)->d_inode, 
+                          meta_dentry, S_IRUSR | S_IWUSR);
+#endif
+               app_flag = 0;
+       }
+       /* need we truncate the meta file? */
+       if(!app_flag) {
+               struct iattr newattrs;
+                newattrs.ia_size = 0;
+                newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&meta_dentry->d_inode->i_mutex);
+#else
+                down(&meta_dentry->d_inode->i_sem);
+#endif
+                err = notify_change(meta_dentry, &newattrs);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&meta_dentry->d_inode->i_mutex);
+#else
+                up(&meta_dentry->d_inode->i_sem);
+#endif
+
+                if(err || meta_dentry->d_inode->i_size != 0) {
+                        printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                          ERROR truncating meta file.\n");
+                        goto out_err_close;
+               }
+       }
+
+        /* open META-file for writing */
+        meta_file = dentry_open(meta_dentry, meta_mnt, 0x1);
+        if(!meta_file || IS_ERR(meta_file)) {
+                printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                  ERROR opening meta file.\n");
+               /* we don't mntget so we dont't mntput (for now)
+                * mntput(meta_mnt); 
+                */
+               dput(meta_dentry);
+               err = -1;
+                goto out;
+        }
+
+        /* check if fs supports writing */
+        if(!meta_file->f_op->write) {
+                printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                  ERROR, fs does not support writing.\n");
+                goto out_err_close;
+        }
+       
+       meta_file->f_pos = meta_dentry->d_inode->i_size; /* append */
+        old_fs = get_fs();
+        set_fs(KERNEL_DS);
+
+       /* here we go... */
+        list_for_each(tmp, &inode_info->deleted_list) {
+               del_entry = list_entry(tmp, struct deleted_entry, list);
+               
+               /* size: len for name, 1 for \n and 2 for "D " */
+               buf = (char *) kmalloc(del_entry->len+3, GFP_KERNEL);
+               if (!buf) {
+                       printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                          out of mem.\n");
+                       return -ENOMEM;
+               }
+                     
+               buf[0] = 'D';
+               buf[1] = ' ';
+               strncpy(buf+2, del_entry->name, del_entry->len);
+               buf[del_entry->len+2] = '\n';
+               bytes = meta_file->f_op->write(meta_file, buf, 
+                                              del_entry->len+3, 
+                                              &meta_file->f_pos);
+               if(bytes != del_entry->len+3) {
+                       printk(KERN_CRIT "mini_fo: meta_sync_d_list: \
+                                          ERROR writing.\n");
+                       err |= -1;
+               }
+               kfree(buf);
+       }
+       set_fs(old_fs);
+       
+ out_err_close:
+       fput(meta_file);
+ out:
+       return err;
+
+}
+
+int meta_sync_r_list(dentry_t *dentry, int app_flag)
+{
+       dentry_t *meta_dentry;
+        file_t *meta_file;
+        mm_segment_t old_fs;
+       
+        int bytes, err, buf_len;
+        struct vfsmount *meta_mnt;
+        char *buf;
+       
+       struct list_head *tmp;
+        struct renamed_entry *ren_entry;
+        struct mini_fo_inode_info *inode_info;
+       
+       err = 0;
+       meta_file=0;
+       meta_mnt=0;
+       
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                  invalid dentry passed.\n");
+               err = -1;
+               goto out;
+       }
+       inode_info = itopd(dentry->d_inode);
+       
+        if(inode_info->deleted_list_size < 0) {
+               err = -1;
+               goto out;
+       }
+       
+       /* ok, there is something to sync */
+
+       /* build the storage structure? */
+        if(!dtohd2(dentry) && !itohi2(dentry->d_inode)) {
+                err = build_sto_structure(dentry->d_parent, dentry);
+                if(err) {
+                        printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                          build_sto_structure failed.\n");
+                       goto out;
+                }
+        }
+       meta_dentry = lookup_one_len(META_FILENAME, 
+                                    dtohd2(dentry), 
+                                    strlen(META_FILENAME));
+        if(!meta_dentry->d_inode) {
+                /* We need to create a META-file */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+                vfs_create(dtohd2(dentry)->d_inode, 
+                          meta_dentry, S_IRUSR | S_IWUSR, NULL);
+#else
+                vfs_create(dtohd2(dentry)->d_inode, 
+                          meta_dentry, S_IRUSR | S_IWUSR);
+#endif
+               app_flag = 0;
+       }
+       /* need we truncate the meta file? */
+       if(!app_flag) {
+               struct iattr newattrs;
+                newattrs.ia_size = 0;
+                newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_lock(&meta_dentry->d_inode->i_mutex);
+#else
+                down(&meta_dentry->d_inode->i_sem);
+#endif
+                err = notify_change(meta_dentry, &newattrs);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&meta_dentry->d_inode->i_mutex);
+#else
+                up(&meta_dentry->d_inode->i_sem);
+#endif
+                if(err || meta_dentry->d_inode->i_size != 0) {
+                        printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                          ERROR truncating meta file.\n");
+                        goto out_err_close;
+               }
+       }
+
+        /* open META-file for writing */
+        meta_file = dentry_open(meta_dentry, meta_mnt, 0x1);
+        if(!meta_file || IS_ERR(meta_file)) {
+                printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                  ERROR opening meta file.\n");
+               /* we don't mntget so we dont't mntput (for now)
+                * mntput(meta_mnt); 
+                */
+               dput(meta_dentry);
+               err = -1;
+                goto out;
+        }
+
+        /* check if fs supports writing */
+        if(!meta_file->f_op->write) {
+                printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                  ERROR, fs does not support writing.\n");
+                goto out_err_close;
+        }
+       
+       meta_file->f_pos = meta_dentry->d_inode->i_size; /* append */
+        old_fs = get_fs();
+        set_fs(KERNEL_DS);
+
+       /* here we go... */
+        list_for_each(tmp, &inode_info->renamed_list) {
+               ren_entry = list_entry(tmp, struct renamed_entry, list);
+               /* size: 
+                * 2 for "R ", old_len+new_len for names, 1 blank+1 \n */
+               buf_len = ren_entry->old_len + ren_entry->new_len + 4;
+               buf = (char *) kmalloc(buf_len, GFP_KERNEL);
+               if (!buf) {
+                       printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                          out of mem.\n");
+                       return -ENOMEM;
+               }
+               buf[0] = 'R';
+               buf[1] = ' ';
+               strncpy(buf + 2, ren_entry->old_name, ren_entry->old_len);
+               buf[ren_entry->old_len + 2] = ' ';
+               strncpy(buf + ren_entry->old_len + 3, 
+                       ren_entry->new_name, ren_entry->new_len);
+               buf[buf_len - 1] = '\n';
+               bytes = meta_file->f_op->write(meta_file, buf, 
+                                              buf_len, &meta_file->f_pos);
+               if(bytes != buf_len) {
+                       printk(KERN_CRIT "mini_fo: meta_sync_r_list: \
+                                          ERROR writing.\n");
+                       err |= -1;
+               }               
+               kfree(buf);
+       }
+       set_fs(old_fs);
+       
+ out_err_close:
+       fput(meta_file);
+ out:
+       return err;
+}
+
+int meta_check_d_entry(dentry_t *dentry, const char *name, int len) 
+{
+       if(!dentry || !dentry->d_inode)
+               printk(KERN_CRIT "mini_fo: meta_check_d_dentry: \
+                                  invalid dentry passed.\n");
+       return __meta_check_d_entry(dentry->d_inode, name, len);        
+}
+
+int __meta_check_d_entry(inode_t *inode, const char *name, int len) 
+{
+       struct list_head *tmp;
+        struct deleted_entry *del_entry;
+        struct mini_fo_inode_info *inode_info;
+
+       if(!inode || !itopd(inode))
+               printk(KERN_CRIT "mini_fo: __meta_check_d_dentry: \
+                                  invalid inode passed.\n");
+
+        inode_info = itopd(inode);
+       
+        if(inode_info->deleted_list_size <= 0)
+                return 0;
+
+        list_for_each(tmp, &inode_info->deleted_list) {
+               del_entry = list_entry(tmp, struct deleted_entry, list);
+               if(del_entry->len != len)
+                       continue;
+               
+               if(!strncmp(del_entry->name, name, len))
+                       return 1;
+       }
+       return 0;
+}
+
+/* 
+ * check if file has been renamed and return path to orig. base dir.
+ * Implements no error return values so far, what of course sucks.
+ * String is null terminated.'
+ */
+char* meta_check_r_entry(dentry_t *dentry, const char *name, int len) 
+{
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: meta_check_r_dentry: \
+                                  invalid dentry passed.\n");
+               return NULL;
+       }
+       return __meta_check_r_entry(dentry->d_inode, name, len);        
+}
+
+char* __meta_check_r_entry(inode_t *inode, const char *name, int len)
+{
+       struct list_head *tmp;
+        struct renamed_entry *ren_entry;
+        struct mini_fo_inode_info *inode_info;
+       char *old_path;
+       
+       if(!inode || !itopd(inode)) {
+               printk(KERN_CRIT "mini_fo: meta_check_r_dentry: \
+                                  invalid inode passed.\n");
+               return NULL;
+       }
+       inode_info = itopd(inode);
+       
+        if(inode_info->renamed_list_size <= 0)
+                return NULL;
+       
+        list_for_each(tmp, &inode_info->renamed_list) {
+               ren_entry = list_entry(tmp, struct renamed_entry, list);
+               if(ren_entry->new_len != len)
+                       continue;
+               
+               if(!strncmp(ren_entry->new_name, name, len)) {
+                       old_path = (char *) 
+                               kmalloc(ren_entry->old_len+1, GFP_KERNEL);
+                       strncpy(old_path, 
+                               ren_entry->old_name, 
+                               ren_entry->old_len);
+                       old_path[ren_entry->old_len]='\0';
+                       return old_path;
+               }
+       }
+       return NULL;
+}
+
+/*
+ * This version only checks if entry exists and return:
+ *     1 if exists,
+ *     0 if not,
+ *    -1 if error.
+ */
+int meta_is_r_entry(dentry_t *dentry, const char *name, int len) 
+{
+       if(!dentry || !dentry->d_inode) {
+               printk(KERN_CRIT "mini_fo: meta_check_r_dentry [2]: \
+                                  invalid dentry passed.\n");
+               return -1;
+       }
+       return __meta_is_r_entry(dentry->d_inode, name, len);   
+}
+
+int __meta_is_r_entry(inode_t *inode, const char *name, int len)
+{
+       struct list_head *tmp;
+        struct renamed_entry *ren_entry;
+        struct mini_fo_inode_info *inode_info;
+       
+       if(!inode || !itopd(inode)) {
+               printk(KERN_CRIT "mini_fo: meta_check_r_dentry [2]: \
+                                  invalid inode passed.\n");
+               return -1;
+       }
+       inode_info = itopd(inode);
+       
+        if(inode_info->renamed_list_size <= 0)
+                return -1;
+       
+        list_for_each(tmp, &inode_info->renamed_list) {
+               ren_entry = list_entry(tmp, struct renamed_entry, list);
+               if(ren_entry->new_len != len)
+                       continue;
+               
+               if(!strncmp(ren_entry->new_name, name, len)) 
+                       return 1;
+       }
+       return 0;
+}
+
diff -urN linux-2.6.21.1.old/fs/mini_fo/mini_fo.h linux-2.6.21.1.dev/fs/mini_fo/mini_fo.h
--- linux-2.6.21.1.old/fs/mini_fo/mini_fo.h     1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/mini_fo.h     2007-05-26 21:01:26.167329264 +0200
@@ -0,0 +1,510 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifndef __MINI_FO_H_
+#define __MINI_FO_H_
+
+#ifdef __KERNEL__
+
+/* META stuff */
+#define META_FILENAME "META_dAfFgHE39ktF3HD2sr"
+
+/* use xattrs? */
+#define XATTR
+
+/* File attributes that when changed, result in a file beeing copied to storage */
+#define COPY_FLAGS ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_SIZE
+
+/*
+ * mini_fo filestates
+ */
+#define MODIFIED       1
+#define UNMODIFIED     2
+#define CREATED        3
+#define DEL_REWRITTEN  4
+#define DELETED        5
+#define NON_EXISTANT   6
+
+/* fist file systems superblock magic */
+# define MINI_FO_SUPER_MAGIC 0xf15f
+
+/*
+ * STRUCTURES:
+ */
+
+/* mini_fo inode data in memory */
+struct mini_fo_inode_info {
+       inode_t *wii_inode;
+       inode_t *wii_inode2; /* pointer to storage inode */
+
+       /* META-data lists */
+       /* deleted list, ex wol */
+       struct list_head deleted_list;
+       int deleted_list_size;
+
+       /* renamed list */
+       struct list_head renamed_list;
+       int renamed_list_size;
+
+       /* add other lists here ... */
+};
+
+/* mini_fo dentry data in memory */
+struct mini_fo_dentry_info {
+       dentry_t *wdi_dentry;
+       dentry_t *wdi_dentry2; /* pointer to  storage dentry */
+       unsigned int state;  /* state of the mini_fo dentry */
+};
+
+
+/* mini_fo super-block data in memory */
+struct mini_fo_sb_info {
+       super_block_t *wsi_sb, *wsi_sb2; /* mk: might point to the same sb */
+       struct vfsmount *hidden_mnt, *hidden_mnt2;
+       dentry_t *base_dir_dentry;
+       dentry_t *storage_dir_dentry;
+       ;
+};
+
+/* readdir_data, readdir helper struct */
+struct readdir_data {
+       struct list_head ndl_list; /* linked list head ptr */
+       int ndl_size; /* list size */
+       int sto_done; /* flag to show that the storage dir entries have
+                      * all been read an now follow base entries */
+};
+
+/* file private data. */
+struct mini_fo_file_info {
+       struct file *wfi_file;
+       struct file *wfi_file2; /* pointer to storage file */
+       struct readdir_data rd;
+};
+
+/* struct ndl_entry */
+struct ndl_entry {
+       struct list_head list;
+       char *name;
+       int len;
+};
+
+/********************************
+ *  META-data structures
+ ********************************/
+
+/* deleted entry */
+struct deleted_entry {
+       struct list_head list;
+       char *name;
+       int len;
+};
+
+/* renamed entry */
+struct renamed_entry {
+       struct list_head list;
+       char *old_name;     /* old directory with full path */
+       int old_len;        /* length of above string */
+       char *new_name;     /* new directory name */
+       int new_len;        /* length of above string */
+};
+
+/* attr_change entry */
+struct attr_change_entry {
+       struct list_head list;
+       char *name;
+       int len;
+};
+
+/* link entry */
+struct link_entry {
+       struct list_head list;
+       int links_moved;
+       int inum_base;
+       int inum_sto;
+       char *weird_name;
+       int weird_name_len;
+};
+
+
+/* Some other stuff required for mini_fo_filldir64, copied from
+ * fs/readdir.c
+ */
+
+#define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
+#define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
+
+
+struct linux_dirent64 {
+        u64             d_ino;
+        s64             d_off;
+        unsigned short  d_reclen;
+        unsigned char   d_type;
+        char            d_name[0];
+};
+
+
+struct getdents_callback64 {
+        struct linux_dirent64 * current_dir;
+        struct linux_dirent64 * previous;
+        int count;
+        int error;
+};
+
+struct linux_dirent {
+       unsigned long   d_ino;
+       unsigned long   d_off;
+       unsigned short  d_reclen;
+       char            d_name[1];
+};
+
+struct getdents_callback {
+       struct linux_dirent * current_dir;
+       struct linux_dirent * previous;
+       int count;
+       int error;
+};
+
+
+/*
+ * MACROS:
+ */
+
+/* file TO private_data */
+# define ftopd(file) ((struct mini_fo_file_info *)((file)->private_data))
+# define __ftopd(file) ((file)->private_data)
+/* file TO hidden_file */
+# define ftohf(file) ((ftopd(file))->wfi_file)
+# define ftohf2(file) ((ftopd(file))->wfi_file2) 
+
+/* inode TO private_data */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+# define itopd(ino) ((struct mini_fo_inode_info *)(ino)->i_private)
+# define __itopd(ino) ((ino)->i_private)
+#else
+# define itopd(ino) ((struct mini_fo_inode_info *)(ino)->u.generic_ip)
+# define __itopd(ino) ((ino)->u.generic_ip)
+#endif
+/* inode TO hidden_inode */
+# define itohi(ino) (itopd(ino)->wii_inode)
+# define itohi2(ino) (itopd(ino)->wii_inode2)
+
+/* superblock TO private_data */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+# define stopd(super) ((struct mini_fo_sb_info *)(super)->s_fs_info)
+# define __stopd(super) ((super)->s_fs_info)
+#else
+# define stopd(super) ((struct mini_fo_sb_info *)(super)->u.generic_sbp)
+# define __stopd(super) ((super)->u.generic_sbp)
+#endif
+
+/* unused? # define vfs2priv stopd */
+/* superblock TO hidden_superblock */
+
+# define stohs(super) (stopd(super)->wsi_sb)
+# define stohs2(super) (stopd(super)->wsi_sb2)
+
+/* dentry TO private_data */
+# define dtopd(dentry) ((struct mini_fo_dentry_info *)(dentry)->d_fsdata)
+# define __dtopd(dentry) ((dentry)->d_fsdata)
+/* dentry TO hidden_dentry */
+# define dtohd(dent) (dtopd(dent)->wdi_dentry)
+# define dtohd2(dent) (dtopd(dent)->wdi_dentry2)
+
+/* dentry to state */
+# define dtost(dent) (dtopd(dent)->state)
+# define sbt(sb) ((sb)->s_type->name)
+
+#define IS_WRITE_FLAG(flag) (flag & (O_RDWR | O_WRONLY | O_APPEND))
+#define IS_COPY_FLAG(flag) (flag & (COPY_FLAGS))
+
+/* macros to simplify non-SCA code */
+#  define MALLOC_PAGE_POINTERS(hidden_pages, num_hidden_pages)
+#  define MALLOC_PAGEDATA_POINTERS(hidden_pages_data, num_hidden_pages)
+#  define FREE_PAGE_POINTERS(hidden_pages, num)
+#  define FREE_PAGEDATA_POINTERS(hidden_pages_data, num)
+#  define FOR_EACH_PAGE
+#  define CURRENT_HIDDEN_PAGE hidden_page
+#  define CURRENT_HIDDEN_PAGEDATA hidden_page_data
+#  define CURRENT_HIDDEN_PAGEINDEX page->index
+
+/*
+ * EXTERNALS:
+ */
+extern struct file_operations mini_fo_main_fops;
+extern struct file_operations mini_fo_dir_fops;
+extern struct inode_operations mini_fo_main_iops;
+extern struct inode_operations mini_fo_dir_iops;
+extern struct inode_operations mini_fo_symlink_iops;
+extern struct super_operations mini_fo_sops;
+extern struct dentry_operations mini_fo_dops;
+extern struct vm_operations_struct mini_fo_shared_vmops;
+extern struct vm_operations_struct mini_fo_private_vmops;
+extern struct address_space_operations mini_fo_aops;
+
+#if 0 /* unused by mini_fo */
+extern int mini_fo_interpose(dentry_t *hidden_dentry, dentry_t *this_dentry, super_block_t *sb, int flag);
+#if defined(FIST_FILTER_DATA) || defined(FIST_FILTER_SCA)
+extern page_t *mini_fo_get1page(file_t *file, int index);
+extern int mini_fo_fill_zeros(file_t *file, page_t *page, unsigned from);
+# endif /* FIST_FILTER_DATA || FIST_FILTER_SCA */
+
+
+#  define mini_fo_hidden_dentry(d) __mini_fo_hidden_dentry(__FILE__,__FUNCTION__,__LINE__,(d))
+#  define mini_fo_hidden_sto_dentry(d) __mini_fo_hidden_sto_dentry(__FILE__,__FUNCTION__,__LINE__,(d))
+
+extern dentry_t *__mini_fo_hidden_dentry(char *file, char *func, int line, dentry_t *this_dentry);
+extern dentry_t *__mini_fo_hidden_sto_dentry(char *file, char *func, int line, dentry_t *this_dentry);
+
+extern int mini_fo_read_file(const char *filename, void *buf, int len);
+extern int mini_fo_write_file(const char *filename, void *buf, int len);
+extern dentry_t *fist_lookup(dentry_t *dir, const char *name, vnode_t **out, uid_t uid, gid_t gid);
+#endif /* unused by mini_fo */
+
+/* state transition functions */
+extern int nondir_unmod_to_mod(dentry_t *dentry, int cp_flag);
+extern int nondir_del_rew_to_del(dentry_t *dentry);
+extern int nondir_creat_to_del(dentry_t *dentry);
+extern int nondir_mod_to_del(dentry_t *dentry);
+extern int nondir_unmod_to_del(dentry_t *dentry);
+
+extern int dir_unmod_to_mod(dentry_t *dentry);
+
+/* rename specials */
+extern int rename_directory(inode_t *old_dir, dentry_t *old_dentry, inode_t *new_dir, dentry_t *new_dentry);
+extern int rename_nondir(inode_t *old_dir, dentry_t *old_dentry, inode_t *new_dir, dentry_t *new_dentry);
+
+/* misc stuff */
+extern int mini_fo_tri_interpose(dentry_t *hidden_dentry,
+                                dentry_t *hidden_sto_dentry,
+                                dentry_t *dentry, 
+                                super_block_t *sb, int flag);
+
+extern int mini_fo_cp_cont(dentry_t *tgt_dentry, struct vfsmount *tgt_mnt,
+                          dentry_t *src_dentry, struct vfsmount *src_mnt);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+extern int mini_fo_create(inode_t *dir, dentry_t *dentry, int mode, struct nameidata *nd);
+
+extern int create_sto_nod(dentry_t *dentry, int mode, dev_t dev);
+extern int create_sto_reg_file(dentry_t *dentry, int mode, struct nameidata *nd);
+#else
+extern int mini_fo_create(inode_t *dir, dentry_t *dentry, int mode);
+
+extern int create_sto_nod(dentry_t *dentry, int mode, int dev);
+extern int create_sto_reg_file(dentry_t *dentry, int mode);
+#endif
+
+extern int create_sto_dir(dentry_t *dentry, int mode);
+
+extern int exists_in_storage(dentry_t *dentry);
+extern int is_mini_fo_existant(dentry_t *dentry);
+extern int get_neg_sto_dentry(dentry_t *dentry);
+extern int build_sto_structure(dentry_t *dir, dentry_t *dentry);
+extern int get_mini_fo_bpath(dentry_t *dentry, char **bpath, int *bpath_len);
+extern dentry_t *bpath_walk(super_block_t *sb, char *bpath);
+extern int bpath_put(dentry_t *dentry);
+
+/* check_mini_fo types functions */
+extern int check_mini_fo_dentry(dentry_t *dentry);
+extern int check_mini_fo_file(file_t *file);
+extern int check_mini_fo_inode(inode_t *inode);
+
+/* General meta functions, can be called from outside of meta.c */
+extern int meta_build_lists(dentry_t *dentry);
+extern int meta_put_lists(dentry_t *dentry);
+extern int __meta_put_lists(inode_t *inode);
+
+extern int meta_add_d_entry(dentry_t *dentry, const char *name, int len);
+extern int meta_add_r_entry(dentry_t *dentry, 
+                           const char *old_name, int old_len, 
+                           const char *new_name, int new_len);
+
+extern int meta_remove_r_entry(dentry_t *dentry, const char *name, int len);
+
+extern int meta_check_d_entry(dentry_t *dentry, const char *name, int len);
+extern int __meta_check_d_entry(inode_t *inode, const char *name, int len);
+
+extern char* meta_check_r_entry(dentry_t *dentry, const char *name, int len);
+extern char* __meta_check_r_entry(inode_t *inode, const char *name, int len);
+extern int meta_is_r_entry(dentry_t *dentry, const char *name, int len);
+extern int __meta_is_r_entry(inode_t *inode, const char *name, int len);
+
+/* Specific meta functions, should be called only inside meta.c */
+extern int __meta_put_d_list(inode_t *inode);
+extern int __meta_put_r_list(inode_t *inode);
+
+extern int meta_list_add_d_entry(dentry_t *dentry, 
+                                const char *name, int len);
+extern int meta_list_add_r_entry(dentry_t *dentry, 
+                                const char *old_name, int old_len, 
+                                const char *new_name, int new_len);
+
+extern int meta_list_remove_r_entry(dentry_t *dentry, 
+                                   const char *name, int len);
+
+extern int __meta_list_remove_r_entry(inode_t *inode, 
+                                     const char *name, int len);
+
+extern int meta_write_d_entry(dentry_t *dentry, const char *name, int len);
+extern int meta_write_r_entry(dentry_t *dentry, 
+                             const char *old_name, int old_len, 
+                             const char *new_name, int new_len);
+
+extern int meta_sync_lists(dentry_t *dentry);
+extern int meta_sync_d_list(dentry_t *dentry, int app_flag);
+extern int meta_sync_r_list(dentry_t *dentry, int app_flag);
+
+/* ndl stuff */
+extern int ndl_add_entry(struct readdir_data *rd, const char *name, int len);
+extern void ndl_put_list(struct readdir_data *rd);
+extern int ndl_check_entry(struct readdir_data *rd, 
+                          const char *name, int len);
+
+
+# define copy_inode_size(dst, src) \
+    dst->i_size = src->i_size; \
+    dst->i_blocks = src->i_blocks;
+
+static inline void
+fist_copy_attr_atime(inode_t *dest, const inode_t *src)
+{
+       ASSERT(dest != NULL);
+       ASSERT(src != NULL);
+       dest->i_atime = src->i_atime;
+}
+static inline void
+fist_copy_attr_times(inode_t *dest, const inode_t *src)
+{
+       ASSERT(dest != NULL);
+       ASSERT(src != NULL);
+       dest->i_atime = src->i_atime;
+       dest->i_mtime = src->i_mtime;
+       dest->i_ctime = src->i_ctime;
+}
+static inline void
+fist_copy_attr_timesizes(inode_t *dest, const inode_t *src)
+{
+       ASSERT(dest != NULL);
+       ASSERT(src != NULL);
+       dest->i_atime = src->i_atime;
+       dest->i_mtime = src->i_mtime;
+       dest->i_ctime = src->i_ctime;
+       copy_inode_size(dest, src);
+}
+static inline void
+fist_copy_attr_all(inode_t *dest, const inode_t *src)
+{
+       ASSERT(dest != NULL);
+       ASSERT(src != NULL);
+       dest->i_mode = src->i_mode;
+       dest->i_nlink = src->i_nlink;
+       dest->i_uid = src->i_uid;
+       dest->i_gid = src->i_gid;
+       dest->i_rdev = src->i_rdev;
+       dest->i_atime = src->i_atime;
+       dest->i_mtime = src->i_mtime;
+       dest->i_ctime = src->i_ctime;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
+       dest->i_blksize = src->i_blksize;
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,12)
+       dest->i_blkbits = src->i_blkbits;
+# endif /* linux 2.4.12 and newer */
+       copy_inode_size(dest, src);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
+       dest->i_attr_flags = src->i_attr_flags;
+#else
+       dest->i_flags = src->i_flags;
+#endif
+}
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+/* copied from linux/fs.h */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+static inline void double_lock(struct dentry *d1, struct dentry *d2)
+{
+       struct mutex *m1 = &d1->d_inode->i_mutex;
+       struct mutex *m2 = &d2->d_inode->i_mutex;
+       if (m1 != m2) {
+               if ((unsigned long) m1 < (unsigned long) m2) {
+                       struct mutex *tmp = m2;
+                       m2 = m1; m1 = tmp;
+               }
+               mutex_lock(m1);
+       }
+       mutex_lock(m2);
+}
+
+static inline void double_unlock(struct dentry *d1, struct dentry *d2)
+{
+       struct mutex *m1 = &d1->d_inode->i_mutex;
+       struct mutex *m2 = &d2->d_inode->i_mutex;
+       mutex_unlock(m1);
+       if (m1 != m2)
+               mutex_unlock(m2);
+       dput(d1);
+       dput(d2);
+}
+
+#else
+static inline void double_down(struct semaphore *s1, struct semaphore *s2)
+{
+        if (s1 != s2) {
+                if ((unsigned long) s1 < (unsigned long) s2) {
+                        struct semaphore *tmp = s2;
+                        s2 = s1; s1 = tmp;
+                }
+                down(s1);
+        }
+        down(s2);
+}
+
+static inline void double_up(struct semaphore *s1, struct semaphore *s2)
+{
+        up(s1);
+        if (s1 != s2)
+                up(s2);
+}
+
+static inline void double_lock(struct dentry *d1, struct dentry *d2)
+{
+        double_down(&d1->d_inode->i_sem, &d2->d_inode->i_sem);
+}
+
+static inline void double_unlock(struct dentry *d1, struct dentry *d2)
+{
+        double_up(&d1->d_inode->i_sem,&d2->d_inode->i_sem);
+        dput(d1);
+        dput(d2);
+}
+#endif   /* if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) */
+#endif  /* if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0) */
+#endif /* __KERNEL__ */
+
+/*
+ * Definitions for user and kernel code
+ */
+
+/* ioctls */
+
+#endif /* not __MINI_FO_H_ */
diff -urN linux-2.6.21.1.old/fs/mini_fo/mini_fo-merge linux-2.6.21.1.dev/fs/mini_fo/mini_fo-merge
--- linux-2.6.21.1.old/fs/mini_fo/mini_fo-merge 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/mini_fo-merge 2007-05-26 21:01:26.167329264 +0200
@@ -0,0 +1,180 @@
+#!/bin/bash
+#
+# Copyright (C) 2005 Markus Klotzbuecher <mk@creamnet.de>
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version
+# 2 of the License, or (at your option) any later version.
+#
+
+BASE=
+STO=
+HELP=
+DRYRUN=
+VERBOSE=
+TMP="/tmp/"
+META_NAME="META_dAfFgHE39ktF3HD2sr"
+SKIP_DEL_LIST="skip-delete-list.mini_fo-merge"
+
+COMMAND=
+exec_command()
+{
+    if [ x$DRYRUN == "xset" ]; then
+       echo "  would run: $COMMAND"
+    elif ! [ x$DRYRUN == "xset" ]; then
+       if [ x$VERBOSE == "xset" ]; then
+           echo "  running: $COMMAND"
+       fi
+       eval $COMMAND
+    fi
+}
+
+usage()
+{
+cat <<EOF
+
+USAGE: $0 -b <base dir> -s <storage dir>
+Version 0.1
+
+This script merges the contents of a mini_fo storage file system back
+to the base file system.
+
+!!! Warning: This will modify the base filesystem and can destroy data
+             if used wrongly.
+
+Options:
+     -b <base dir>
+          the directory of the base file system.
+
+     -s <storage dir>
+          the directory of the storage file system.
+
+     -d   dry run, will not change anything and print the commands that
+          would be executed.
+
+     -t   tmp dir for storing temporary file. default: $TMP
+
+     -v   show what operations are performed.
+
+     -h   displays this message.
+
+EOF
+}
+
+# parse parameters
+while getopts hdvt:b:s: OPTS
+  do
+  case $OPTS in
+      h)  HELP="set";;
+      d)  DRYRUN="set";;
+      v)  VERBOSE="set";;
+      b)  BASE="$OPTARG";;
+      s)  STO="$OPTARG";;
+      t)  TMP="$OPTARG";;
+      ?)  usage
+         exit 1;;
+  esac
+done
+
+if [ "x$HELP" == "xset" ]; then
+    usage
+    exit -1
+fi
+
+if ! [ -d "$BASE" ] || ! [ -d "$STO" ]; then
+    echo -e "$0:\n Error, -s and/or -b argument missing. type $0 -h for help."
+    exit -1;
+fi
+
+# get full paths
+pushd $STO; STO=`pwd`; popd
+pushd $BASE; BASE=`pwd`; popd
+TMP=${TMP%/}
+
+
+cat<<EOF
+###############################################################################
+# mini_fo-merge
+#
+# base dir:       $BASE
+# storage dir:    $STO
+# meta filename:  $META_NAME
+# dry run:        $DRYRUN
+# verbose:        $VERBOSE     
+# tmp files:      $TMP
+###############################################################################
+
+EOF
+
+rm $TMP/$SKIP_DEL_LIST
+
+# first process all renamed dirs
+echo "Merging renamed directories..."
+pushd $STO &> /dev/null
+find . -name $META_NAME -type f -print0  | xargs -0 -e grep  -e '^R ' | tr -s ':R' ' ' | while read ENTRY; do 
+    echo "entry: $ENTRY"
+    META_FILE=`echo $ENTRY | cut -d ' ' -f 1`
+    OLD_B_DIR=`echo $ENTRY | cut -d ' ' -f 2 | sed -e 's/\///'`
+    NEW_NAME=`echo $ENTRY | cut -d ' ' -f 3`
+    NEW_B_DIR=`echo $META_FILE | sed -e "s/$META_NAME/$NEW_NAME/" | sed -e 's/^\.\///'`
+    echo "META_FILE: $META_FILE"
+    echo "OLD_B_DIR: $OLD_B_DIR"
+    echo "NEW_NAME: $NEW_NAME"
+    echo  "NEW_B_DIR: $NEW_B_DIR"
+
+    pushd $BASE &> /dev/null
+    # remove an existing dir in storage
+    COMMAND="rm -rf $NEW_B_DIR"; exec_command
+    COMMAND="cp -R $OLD_B_DIR $NEW_B_DIR"; exec_command
+    echo ""
+    popd &> /dev/null
+
+    # remember this dir to exclude it from deleting later
+    echo $NEW_B_DIR >> $TMP/$SKIP_DEL_LIST
+done
+
+# delete all whiteouted files from base
+echo -e "\nDeleting whiteout'ed files from base file system..."
+find . -name $META_NAME -type f -print0  | xargs -0 -e grep  -e '^D ' | sed -e 's/:D//' | while read ENTRY; do 
+    META_FILE=`echo $ENTRY | cut -d ' ' -f 1`
+    DEL_NAME=`echo $ENTRY | cut -d ' ' -f 2`
+    DEL_FILE=`echo $META_FILE | sed -e "s/$META_NAME/$DEL_NAME/" | sed -e 's/^\.\///'`
+    grep -x $DEL_FILE $TMP/$SKIP_DEL_LIST &> /dev/null
+    if [ $? -ne 0 ]; then
+       pushd $BASE &> /dev/null
+       COMMAND="rm -rf $DEL_FILE"; exec_command
+       popd &> /dev/null
+    else
+       echo "  excluding: $DEL_FILE as in skip-del-list."
+    fi
+done
+
+# create all dirs and update permissions
+echo -e "\nSetting up directory structures in base file system..."
+find . -type d | sed -e 's/^\.\///' | while read DIR; do
+    PERMS=`stat -c %a $DIR`
+    DIR_UID=`stat -c %u $DIR`
+    DIR_GID=`stat -c %g $DIR`
+    pushd $BASE &> /dev/null
+    if ! [ -d $DIR ]; then
+       COMMAND="mkdir -p $DIR"; exec_command
+    fi
+    COMMAND="chmod $PERMS $DIR"; exec_command
+    COMMAND="chown $DIR_UID:$DIR_GID $DIR"; exec_command
+    popd &> /dev/null
+done
+
+# merge all non-directory files
+echo -e "\nMerging all non-directory files...."
+for i in b c p f l s; do
+    find . -type $i | sed -e 's/^\.\///' | grep -v "$META_NAME" | while read FILE; do
+       pushd $BASE #&> /dev/null
+       COMMAND="cp -df $STO/$FILE $BASE/$FILE"; exec_command
+       popd &> /dev/null
+    done   
+done
+popd &> /dev/null
+
+#rm $TMP/$SKIP_DEL_LIST 
+
+echo "Done!"
diff -urN linux-2.6.21.1.old/fs/mini_fo/mini_fo-overlay linux-2.6.21.1.dev/fs/mini_fo/mini_fo-overlay
--- linux-2.6.21.1.old/fs/mini_fo/mini_fo-overlay       1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/mini_fo-overlay       2007-05-26 21:01:26.167329264 +0200
@@ -0,0 +1,130 @@
+#!/bin/bash
+#
+# Copyright (C) 2005 Markus Klotzbuecher <mk@creamnet.de>
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version
+# 2 of the License, or (at your option) any later version.
+#
+
+HELP=
+SUFF=
+MNTP=
+MNT_DIR="/mnt"
+STO=
+STO_DIR="/tmp"
+BASE=
+
+usage() 
+{
+cat <<EOF
+
+Usage: $0 [-s suffix] [-d sto_dir_dir] [-m mount point] base_dir
+Version 0.1
+
+This script overlays the given base directory using the mini_fo file
+system. If only the base directory base_dir is given, $0 
+will use a storage directory called "sto-<base_dir_name>" in $STO_DIR,
+and mount point "mini_fo-<base_dir_dir>" in $MNT_DIR.
+
+Options:
+     -s <suffix>
+          add given suffix to storage directory and the mount
+          point. This is usefull for overlaying one base directory
+          several times and avoiding conflicts with storage directory
+          names and mount points.
+
+     -d <sto_dir_dir>
+          change the directory in which the storage directory will be
+          created (default is currently "$STO_DIR".
+
+     -m <mount point>
+          use an alternative directory to create the mini_fo
+          mountpoint (default is currently "$MNT_DIR".
+
+     -h   displays this message.
+
+EOF
+exit 1;
+}
+
+while getopts hm:s:d: OPTS
+  do
+  case $OPTS in
+      s)  SUFF="$OPTARG";;
+      d)  STO_DIR="$OPTARG";;
+      m)  MNT_DIR="$OPTARG";;
+      h)  HELP="set";;
+      ?)  usage
+         exit 1;;
+  esac
+done
+shift $(($OPTIND - 1))
+
+BASE="$1"
+
+if [ "x$HELP" == "xset" ]; then
+    usage
+    exit -1
+fi
+
+# fix suffix 
+if [ "x$SUFF" != "x" ]; then
+    SUFF="-$SUFF"
+fi
+
+# kill trailing slashes
+MNT_DIR=${MNT_DIR%/}
+STO_DIR=${STO_DIR%/}
+BASE=${BASE%/}
+
+
+if ! [ -d "$BASE" ]; then
+    echo "invalid base dir $BASE, run $0 -h for help."
+    exit -1
+fi
+
+# check opts
+if ! [ -d "$MNT_DIR" ]; then
+    echo "invalid mount dir $MNT_DIR, run $0 -h for help."
+    exit -1
+fi
+
+if ! [ -d "$STO_DIR" ]; then
+    echo "invalid sto_dir_dir $STO_DIR, run $0 -h for help."
+    exit -1
+fi
+
+MNTP="$MNT_DIR/mini_fo-`basename $BASE`$SUFF"
+STO="$STO_DIR/sto-`basename $BASE`$SUFF"
+
+# create the mount point if it doesn't exist
+mkdir -p $MNTP
+if [ $? -ne 0 ]; then
+    echo "Error, failed to create mount point $MNTP"
+fi
+
+mkdir -p $STO
+if [ $? -ne 0 ]; then
+    echo "Error, failed to create storage dir $STO"
+fi
+
+# check if fs is already mounted
+mount | grep mini_fo | grep $MNTP &> /dev/null
+if [ $? -eq 0 ]; then
+    echo "Error, existing mini_fo mount at $MNTP."
+    exit -1
+fi
+
+mount | grep mini_fo | grep $STO &> /dev/null
+if [ $? -eq 0 ]; then
+    echo "Error, $STO seems to be used already."
+    exit -1
+fi
+
+# mount 
+mount -t mini_fo -o base=$BASE,sto=$STO $BASE $MNTP
+
+if [ $? -ne 0 ]; then
+    echo "Error, mounting failed, maybe no permisson to mount?"
+fi
diff -urN linux-2.6.21.1.old/fs/mini_fo/mmap.c linux-2.6.21.1.dev/fs/mini_fo/mmap.c
--- linux-2.6.21.1.old/fs/mini_fo/mmap.c        1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/mmap.c        2007-05-26 21:01:26.168329112 +0200
@@ -0,0 +1,637 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif /* HAVE_CONFIG_H */
+
+#include "fist.h"
+#include "mini_fo.h"
+
+
+#ifdef FIST_COUNT_WRITES
+/* for counting writes in the middle vs. regular writes */
+unsigned long count_writes = 0, count_writes_middle = 0;
+#endif /* FIST_COUNT_WRITES */
+
+/* forward declaration of commit write and prepare write */
+STATIC int mini_fo_commit_write(file_t *file, page_t *page, unsigned from, unsigned to);
+STATIC int mini_fo_prepare_write(file_t *file, page_t *page, unsigned from, unsigned to);
+
+
+/*
+ * Function for handling creation of holes when lseek-ing past the
+ * end of the file and then writing some data.
+ */
+int
+mini_fo_fill_zeros(file_t* file, page_t *page, unsigned from)
+{
+       int err = 0;
+       dentry_t *dentry = file->f_dentry;
+       inode_t *inode = dentry->d_inode;
+       page_t *tmp_page;
+       int index;
+
+       print_entry_location();
+
+       for (index = inode->i_size >> PAGE_CACHE_SHIFT; index < page->index; index++) {
+               tmp_page = mini_fo_get1page(file, index);
+               if (IS_ERR(tmp_page)) {
+                       err = PTR_ERR(tmp_page);
+                       goto out;
+               }
+
+               /*
+                * zero out rest of the contents of the page between the appropriate
+                * offsets.
+                */
+               memset((char*)page_address(tmp_page) + (inode->i_size & ~PAGE_CACHE_MASK), 0, PAGE_CACHE_SIZE - (inode->i_size & ~PAGE_CACHE_MASK));
+
+               if (! (err = mini_fo_prepare_write(file, tmp_page, 0, PAGE_CACHE_SIZE)))
+                       err = mini_fo_commit_write(file, tmp_page, 0, PAGE_CACHE_SIZE);
+
+               page_cache_release(tmp_page);
+               if (err < 0)
+                       goto out;
+               if (current->need_resched)
+                       schedule();
+       }
+
+       /* zero out appropriate parts of last page */
+
+       /*
+        * if the encoding type is block, then adjust the 'from' (where the
+        * zeroing will start) offset appropriately
+        */
+       from = from & (~(FIST_ENCODING_BLOCKSIZE - 1));
+
+       if ((from - (inode->i_size & ~PAGE_CACHE_MASK)) > 0) {
+
+               memset((char*)page_address(page) + (inode->i_size & ~PAGE_CACHE_MASK), 0, from - (inode->i_size & ~PAGE_CACHE_MASK));
+               if (! (err = mini_fo_prepare_write(file, page, 0, PAGE_CACHE_SIZE)))
+                       err = mini_fo_commit_write(file, page, 0, PAGE_CACHE_SIZE);
+
+               if (err < 0)
+                       goto out;
+               if (current->need_resched)
+                       schedule();
+       }
+
+ out:
+       print_exit_status(err);
+       return err;
+}
+
+
+
+STATIC int
+mini_fo_writepage(page_t *page)
+{
+       int err = -EIO;
+       inode_t *inode;
+       inode_t *hidden_inode;
+       page_t *hidden_page;
+       char *kaddr, *hidden_kaddr;
+
+       print_entry_location();
+
+       inode = page->mapping->host;
+       hidden_inode = itohi(inode);
+
+       /*
+        * writepage is called when shared mmap'ed files need to write
+        * their pages, while prepare/commit_write are called from the
+        * non-paged write() interface.  (However, in 2.3 the two interfaces
+        * share the same cache, while in 2.2 they didn't.)
+        *
+        * So we pretty much have to duplicate much of what commit_write does.
+        */
+
+       /* find lower page (returns a locked page) */
+       hidden_page = grab_cache_page(hidden_inode->i_mapping, page->index);
+       if (!hidden_page)
+               goto out;
+
+       /* get page address, and encode it */
+       kaddr = (char *) kmap(page);
+       hidden_kaddr = (char*) kmap(hidden_page);
+       mini_fo_encode_block(kaddr, hidden_kaddr, PAGE_CACHE_SIZE, inode, inode->i_sb, page->index);
+       /* if encode_block could fail, then return error */
+       kunmap(page);
+       kunmap(hidden_page);
+
+       /* call lower writepage (expects locked page) */
+       err = hidden_inode->i_mapping->a_ops->writepage(hidden_page);
+
+       /*
+        * update mtime and ctime of lower level file system
+        * mini_fo' mtime and ctime are updated by generic_file_write
+        */
+       hidden_inode->i_mtime = hidden_inode->i_ctime = CURRENT_TIME;
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,4,1)
+       UnlockPage(hidden_page);        /* b/c grab_cache_page locked it */
+# endif /* kernel older than 2.4.1 */
+       page_cache_release(hidden_page); /* b/c grab_cache_page increased refcnt */
+
+       if (err)
+               ClearPageUptodate(page);
+       else
+               SetPageUptodate(page);
+ out:
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,1)
+       UnlockPage(page);
+# endif /* kernel 2.4.1 and newer */
+       print_exit_status(err);
+       return err;
+}
+
+
+/*
+ * get one page from cache or lower f/s, return error otherwise.
+ * returns unlocked, up-to-date page (if ok), with increased refcnt.
+ */
+page_t *
+mini_fo_get1page(file_t *file, int index)
+{
+       page_t *page;
+       dentry_t *dentry;
+       inode_t *inode;
+       struct address_space *mapping;
+       int err;
+
+       print_entry_location();
+
+       dentry = file->f_dentry; /* CPW: Moved below print_entry_location */
+       inode = dentry->d_inode;
+       mapping = inode->i_mapping;
+
+       fist_dprint(8, "%s: read page index %d pid %d\n", __FUNCTION__, index, current->pid);
+       if (index < 0) {
+               printk("%s BUG: index=%d\n", __FUNCTION__, index);
+               page = ERR_PTR(-EIO);
+               goto out;
+       }
+       page = read_cache_page(mapping,
+                              index,
+                              (filler_t *) mapping->a_ops->readpage,
+                              (void *) file);
+       if (IS_ERR(page))
+               goto out;
+       wait_on_page(page);
+       if (!Page_Uptodate(page)) {
+               lock_page(page);
+               err = mapping->a_ops->readpage(file, page);
+               if (err) {
+                       page = ERR_PTR(err);
+                       goto out;
+               }
+               wait_on_page(page);
+               if (!Page_Uptodate(page)) {
+                       page = ERR_PTR(-EIO);
+                       goto out;
+               }
+       }
+
+ out:
+       print_exit_pointer(page);
+       return page;
+}
+
+
+/*
+ * get one page from cache or lower f/s, return error otherwise.
+ * similar to get1page, but doesn't guarantee that it will return
+ * an unlocked page.
+ */
+page_t *
+mini_fo_get1page_cached(file_t *file, int index)
+{
+       page_t *page;
+       dentry_t *dentry;
+       inode_t *inode;
+       struct address_space *mapping;
+       int err;
+
+       print_entry_location();
+
+       dentry = file->f_dentry; /* CPW: Moved below print_entry_location */
+       inode = dentry->d_inode;
+       mapping = inode->i_mapping;
+
+       fist_dprint(8, "%s: read page index %d pid %d\n", __FUNCTION__, index, current->pid);
+       if (index < 0) {
+               printk("%s BUG: index=%d\n", __FUNCTION__, index);
+               page = ERR_PTR(-EIO);
+               goto out;
+       }
+       page = read_cache_page(mapping,
+                              index,
+                              (filler_t *) mapping->a_ops->readpage,
+                              (void *) file);
+       if (IS_ERR(page))
+               goto out;
+
+ out:
+       print_exit_pointer(page);
+       return page;
+}
+
+
+/*
+ * readpage is called from generic_page_read and the fault handler.
+ * If your file system uses generic_page_read for the read op, it
+ * must implement readpage.
+ *
+ * Readpage expects a locked page, and must unlock it.
+ */
+STATIC int
+mini_fo_do_readpage(file_t *file, page_t *page)
+{
+       int err = -EIO;
+       dentry_t *dentry;
+       file_t *hidden_file = NULL;
+       dentry_t *hidden_dentry;
+       inode_t *inode;
+       inode_t *hidden_inode;
+       char *page_data;
+       page_t *hidden_page;
+       char *hidden_page_data;
+       int real_size;
+
+       print_entry_location();
+
+       dentry = file->f_dentry; /* CPW: Moved below print_entry_location */
+       if (ftopd(file) != NULL)
+               hidden_file = ftohf(file);
+       hidden_dentry = dtohd(dentry);
+       inode = dentry->d_inode;
+       hidden_inode = itohi(inode);
+
+       fist_dprint(7, "%s: requesting page %d from file %s\n", __FUNCTION__, page->index, dentry->d_name.name);
+
+       MALLOC_PAGE_POINTERS(hidden_pages, num_hidden_pages);
+       MALLOC_PAGEDATA_POINTERS(hidden_pages_data, num_hidden_pages);
+       FOR_EACH_PAGE
+               CURRENT_HIDDEN_PAGE = NULL;
+
+       /* find lower page (returns a locked page) */
+       FOR_EACH_PAGE {
+               fist_dprint(8, "%s: Current page index = %d\n", __FUNCTION__, CURRENT_HIDDEN_PAGEINDEX);
+               CURRENT_HIDDEN_PAGE = read_cache_page(hidden_inode->i_mapping,
+                                                     CURRENT_HIDDEN_PAGEINDEX,
+                                                     (filler_t *) hidden_inode->i_mapping->a_ops->readpage,
+                                                     (void *) hidden_file);
+               if (IS_ERR(CURRENT_HIDDEN_PAGE)) {
+                       err = PTR_ERR(CURRENT_HIDDEN_PAGE);
+                       CURRENT_HIDDEN_PAGE = NULL;
+                       goto out_release;
+               }
+       }
+
+       /*
+        * wait for the page data to show up
+        * (signaled by readpage as unlocking the page)
+        */
+       FOR_EACH_PAGE {
+               wait_on_page(CURRENT_HIDDEN_PAGE);
+               if (!Page_Uptodate(CURRENT_HIDDEN_PAGE)) {
+                       /*
+                        * call readpage() again if we returned from wait_on_page with a
+                        * page that's not up-to-date; that can happen when a partial
+                        * page has a few buffers which are ok, but not the whole
+                        * page.
+                        */
+                       lock_page(CURRENT_HIDDEN_PAGE);
+                       err = hidden_inode->i_mapping->a_ops->readpage(hidden_file,
+                                                                      CURRENT_HIDDEN_PAGE);
+                       if (err) {
+                               CURRENT_HIDDEN_PAGE = NULL;
+                               goto out_release;
+                       }
+                       wait_on_page(CURRENT_HIDDEN_PAGE);
+                       if (!Page_Uptodate(CURRENT_HIDDEN_PAGE)) {
+                               err = -EIO;
+                               goto out_release;
+                       }
+               }
+       }
+
+       /* map pages, get their addresses */
+       page_data = (char *) kmap(page);
+       FOR_EACH_PAGE
+               CURRENT_HIDDEN_PAGEDATA = (char *) kmap(CURRENT_HIDDEN_PAGE);
+
+       /* if decode_block could fail, then return error */
+       err = 0;
+       real_size = hidden_inode->i_size - (page->index << PAGE_CACHE_SHIFT);
+       if (real_size <= 0)
+               memset(page_data, 0, PAGE_CACHE_SIZE);
+       else if (real_size < PAGE_CACHE_SIZE) {
+               mini_fo_decode_block(hidden_page_data, page_data, real_size, inode, inode->i_sb, page->index);
+               memset(page_data + real_size, 0, PAGE_CACHE_SIZE - real_size);
+       } else
+               mini_fo_decode_block(hidden_page_data, page_data, PAGE_CACHE_SIZE, inode, inode->i_sb, page->index);
+
+       FOR_EACH_PAGE
+               kunmap(CURRENT_HIDDEN_PAGE);
+       kunmap(page);
+
+ out_release:
+       FOR_EACH_PAGE
+               if (CURRENT_HIDDEN_PAGE)
+                       page_cache_release(CURRENT_HIDDEN_PAGE); /* undo read_cache_page */
+
+       FREE_PAGE_POINTERS(hidden_pages, num_hidden_pages);
+       FREE_PAGEDATA_POINTERS(hidden_pages_data, num_hidden_pages);
+
+ out:
+       if (err == 0)
+               SetPageUptodate(page);
+       else
+               ClearPageUptodate(page);
+
+       print_exit_status(err);
+       return err;
+}
+
+
+STATIC int
+mini_fo_readpage(file_t *file, page_t *page)
+{
+       int err;
+       print_entry_location();
+
+       err = mini_fo_do_readpage(file, page);
+
+       /*
+        * we have to unlock our page, b/c we _might_ have gotten a locked page.
+        * but we no longer have to wakeup on our page here, b/c UnlockPage does
+        * it
+        */
+       UnlockPage(page);
+
+       print_exit_status(err);
+       return err;
+}
+
+
+STATIC int
+mini_fo_prepare_write(file_t *file, page_t *page, unsigned from, unsigned to)
+{
+       int err = 0;
+
+       print_entry_location();
+
+       /*
+        * we call kmap(page) only here, and do the kunmap
+        * and the actual downcalls, including unlockpage and uncache
+        * in commit_write.
+        */
+       kmap(page);
+
+       /* fast path for whole page writes */
+       if (from == 0 && to == PAGE_CACHE_SIZE)
+               goto out;
+       /* read the page to "revalidate" our data */
+       /* call the helper function which doesn't unlock the page */
+       if (!Page_Uptodate(page))
+               err = mini_fo_do_readpage(file, page);
+
+ out:
+       print_exit_status(err);
+       return err;
+}
+
+
+
+STATIC int
+mini_fo_commit_write(file_t *file, page_t *page, unsigned from, unsigned to)
+{
+       int err = -ENOMEM;
+       inode_t *inode;
+       inode_t *hidden_inode;
+       page_t *hidden_page;
+       file_t *hidden_file = NULL;
+       loff_t pos;
+       unsigned bytes = to - from;
+       unsigned hidden_from, hidden_to, hidden_bytes;
+
+       print_entry_location();
+
+       inode = page->mapping->host; /* CPW: Moved below print_entry_location */
+       hidden_inode = itohi(inode);
+
+       ASSERT(file != NULL);
+       /*
+        * here we have a kmapped page, with data from the user copied
+        * into it.  we need to encode_block it, and then call the lower
+        * commit_write.  We also need to simulate same behavior of
+        * generic_file_write, and call prepare_write on the lower f/s first.
+        */
+#ifdef FIST_COUNT_WRITES
+       count_writes++;
+# endif /* FIST_COUNT_WRITES */
+
+       /* this is append and/or extend -- we can't have holes so fill them in */
+       if (page->index > (hidden_inode->i_size >> PAGE_CACHE_SHIFT)) {
+               page_t *tmp_page;
+               int index;
+               for (index = hidden_inode->i_size >> PAGE_CACHE_SHIFT; index < page->index; index++) {
+                       tmp_page = mini_fo_get1page(file, index);
+                       if (IS_ERR(tmp_page)) {
+                               err = PTR_ERR(tmp_page);
+                               goto out;
+                       }
+                       /* zero out the contents of the page at the appropriate offsets */
+                       memset((char*)page_address(tmp_page) + (inode->i_size & ~PAGE_CACHE_MASK), 0, PAGE_CACHE_SIZE - (inode->i_size & ~PAGE_CACHE_MASK));
+                       if (!(err = mini_fo_prepare_write(file, tmp_page, 0, PAGE_CACHE_SIZE)))
+                               err = mini_fo_commit_write(file, tmp_page, 0, PAGE_CACHE_SIZE);
+                       page_cache_release(tmp_page);
+                       if (err < 0)
+                               goto out;
+                       if (current->need_resched)
+                               schedule();
+               }
+       }
+
+       if (ftopd(file) != NULL)
+               hidden_file = ftohf(file);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_inode->i_mutex);
+#else
+       down(&hidden_inode->i_sem);
+#endif
+       /* find lower page (returns a locked page) */
+       hidden_page = grab_cache_page(hidden_inode->i_mapping, page->index);
+       if (!hidden_page)
+               goto out;
+
+#if FIST_ENCODING_BLOCKSIZE > 1
+#  error encoding_blocksize greater than 1 is not yet supported
+# endif /* FIST_ENCODING_BLOCKSIZE > 1 */
+
+       hidden_from = from & (~(FIST_ENCODING_BLOCKSIZE - 1));
+       hidden_to = ((to + FIST_ENCODING_BLOCKSIZE - 1) & (~(FIST_ENCODING_BLOCKSIZE - 1)));
+       if ((page->index << PAGE_CACHE_SHIFT) + to > hidden_inode->i_size) {
+
+               /*
+                * if this call to commit_write had introduced holes and the code
+                * for handling holes was invoked, then the beginning of this page
+                * must be zeroed out
+                * zero out bytes from 'size_of_file%pagesize' to 'from'.
+                */
+               if ((hidden_from - (inode->i_size & ~PAGE_CACHE_MASK)) > 0)
+                       memset((char*)page_address(page) + (inode->i_size & ~PAGE_CACHE_MASK), 0, hidden_from - (inode->i_size & ~PAGE_CACHE_MASK));
+
+       }
+       hidden_bytes = hidden_to - hidden_from;
+
+       /* call lower prepare_write */
+       err = -EINVAL;
+       if (hidden_inode->i_mapping &&
+           hidden_inode->i_mapping->a_ops &&
+           hidden_inode->i_mapping->a_ops->prepare_write)
+               err = hidden_inode->i_mapping->a_ops->prepare_write(hidden_file,
+                                                                   hidden_page,
+                                                                   hidden_from,
+                                                                   hidden_to);
+       if (err)
+               /* don't leave locked pages behind, esp. on an ENOSPC */
+               goto out_unlock;
+
+       fist_dprint(8, "%s: encoding %d bytes\n", __FUNCTION__, hidden_bytes);
+       mini_fo_encode_block((char *) page_address(page) + hidden_from, (char*) page_address(hidden_page) + hidden_from, hidden_bytes, inode, inode->i_sb, page->index);
+       /* if encode_block could fail, then goto unlock and return error */
+
+       /* call lower commit_write */
+       err = hidden_inode->i_mapping->a_ops->commit_write(hidden_file,
+                                                          hidden_page,
+                                                          hidden_from,
+                                                          hidden_to);
+
+       if (err < 0)
+               goto out_unlock;
+
+       err = bytes;    /* convert error to no. of bytes */
+
+       inode->i_blocks = hidden_inode->i_blocks;
+       /* we may have to update i_size */
+       pos = (page->index << PAGE_CACHE_SHIFT) + to;
+       if (pos > inode->i_size)
+               inode->i_size = pos;
+
+       /*
+        * update mtime and ctime of lower level file system
+        * mini_fo' mtime and ctime are updated by generic_file_write
+        */
+       hidden_inode->i_mtime = hidden_inode->i_ctime = CURRENT_TIME;
+
+       mark_inode_dirty_sync(inode);
+
+ out_unlock:
+       UnlockPage(hidden_page);
+       page_cache_release(hidden_page);
+       kunmap(page);           /* kmap was done in prepare_write */
+ out:
+       /* we must set our page as up-to-date */
+       if (err < 0)
+               ClearPageUptodate(page);
+       else
+               SetPageUptodate(page);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_inode->i_mutex);
+#else
+       up(&hidden_inode->i_sem);
+#endif
+       print_exit_status(err);
+       return err;                     /* assume all is ok */
+}
+
+
+STATIC int
+mini_fo_bmap(struct address_space *mapping, long block)
+{
+       int err = 0;
+       inode_t *inode;
+       inode_t *hidden_inode;
+
+       print_entry_location();
+
+       inode = (inode_t *) mapping->host;
+       hidden_inode = itohi(inode);
+
+       if (hidden_inode->i_mapping->a_ops->bmap)
+               err = hidden_inode->i_mapping->a_ops->bmap(hidden_inode->i_mapping, block);
+       print_exit_location();
+       return err;
+}
+
+
+/*
+ * This function is copied verbatim from mm/filemap.c.
+ * XXX: It should be simply moved to some header file instead -- bug Al about it!
+ */
+static inline int sync_page(struct page *page)
+{
+       struct address_space *mapping = page->mapping;
+
+       if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
+               return mapping->a_ops->sync_page(page);
+       return 0;
+}
+
+
+/*
+ * XXX: we may not need this function if not FIST_FILTER_DATA.
+ * FIXME: for FIST_FILTER_SCA, get all lower pages and sync them each.
+ */
+STATIC int
+mini_fo_sync_page(page_t *page)
+{
+       int err = 0;
+       inode_t *inode;
+       inode_t *hidden_inode;
+       page_t *hidden_page;
+
+       print_entry_location();
+
+       inode = page->mapping->host; /* CPW: Moved below print_entry_location */
+       hidden_inode = itohi(inode);
+
+       /* find lower page (returns a locked page) */
+       hidden_page = grab_cache_page(hidden_inode->i_mapping, page->index);
+       if (!hidden_page)
+               goto out;
+
+       err = sync_page(hidden_page);
+
+       UnlockPage(hidden_page);        /* b/c grab_cache_page locked it */
+       page_cache_release(hidden_page); /* b/c grab_cache_page increased refcnt */
+
+ out:
+       print_exit_status(err);
+       return err;
+}
diff -urN linux-2.6.21.1.old/fs/mini_fo/README linux-2.6.21.1.dev/fs/mini_fo/README
--- linux-2.6.21.1.old/fs/mini_fo/README        1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/README        2007-05-26 21:01:26.168329112 +0200
@@ -0,0 +1,163 @@
+README for the mini_fo overlay file system
+=========================================
+
+
+WHAT IS MINI_FO?
+----------------
+
+mini_fo is a virtual kernel file system that can make read-only
+file systems writable. This is done by redirecting modifying operations
+to a writeable location called "storage directory", and leaving the
+original data in the "base directory" untouched. When reading, the
+file system merges the modifed and original data so that only the
+newest versions will appear. This occurs transparently to the user,
+who can access the data like on any other read-write file system.
+
+Base and storage directories may be located on the same or on
+different partitions and may be of different file system types. While
+the storage directory obviously needs to be writable, the base may or
+may not be writable, what doesn't matter as it will no be modified
+anyway.
+
+
+WHAT IS GOOD FOR?
+-----------------
+
+The primary purpose of the mini_fo file system is to allow easy
+software updates to embedded systems, that often store their root
+file system in a read-only flash file system, but there are many
+more as for example sandboxing, or for allowing live-cds to
+permanently store information.
+
+
+BUILDING
+--------
+This should be simple. Adjust the Makefile to point to the correct
+kernel headers you want to build the module for. Then:
+
+    # make
+
+should build "mini_fo.o" for a 2.4 kernel or "mini_fo.ko" for a 2.6
+kernel.
+
+If you are building the module for you current kernel, you can install
+the module (as root):
+
+    # make install
+
+or uninstall with
+
+    # make uninstall
+
+
+USING THE FILE SYSTEM
+--------------------
+
+the general mount syntax is:
+
+   mount -t mini_fo -o base=<base directory>,sto=<storage directory>\
+                            <base directory> <mount point>
+
+Example:
+
+You have mounted a cdrom to /mnt/cdrom and want to modifiy some files
+on it:
+
+load the module (as root)
+    
+    # insmod mini_fo.o for a 2.4 kernel or
+ 
+    # insmod mini_fo.ko for a 2.6 kernel
+
+
+create a storage dir in tmp and a mountpoint for mini_fo:
+
+    # mkdir /tmp/sto
+    # mkdir /mnt/mini_fo
+
+and mount the mini_fo file system:
+
+    # mount -t mini_fo -o base=/mnt/cdrom,sto=/tmp/sto /mnt/cdrom /mnt/mini_fo
+
+
+Now the data stored on the cd can be accessed via the mini_fo
+mountpoint just like any read-write file system, files can be modified
+and deleted, new ones can be created and so on. When done unmount the
+file system:
+
+    # unmount /mnt/mini_fo
+
+Note that if the file system is mounted again using the same storage
+file system, of course it will appear in the modified state again. If
+you remount it using an new empty storage directory, it will be
+unmodified. Therefore by executing:
+
+    # cd /tmp/sto
+    # rm -rf *
+
+you can nuke all the changes you made to the original file system. But
+ remember NEVER do this while the mini_fo file system is mounted!
+
+
+Alternatively you can use the mini_fo-overlay bash script, that
+simplifies managing mini_fo mounts. See TOOLS Section.
+
+
+TOOLS
+-----
+
+mini_fo-merge (experimental):
+
+This is a bash script that will merge changes contained in the storage
+directory back to the base directory. This allows mini_fo to function
+as a cache file system by overlaying a slow (network, ...) file system
+and using a fast (ramdisk, ...) as storage. When done, changes can be
+merged back to the (slow) base with mini_fo-merge. See "mini_fo-merge
+-h" for details.
+
+It can be usefull for merging changes back after a successfull test
+(patches, software updates...)
+
+
+mini_fo-overlay:
+
+This bash script simplifies managing one or more mini_fo mounts. For
+overlaying a directory called "basedir1", you can just call:
+
+    # mini_fo-overlay basedir1
+
+This will mount mini_fo with "basedir1" as base, "/tmp/sto-basedir1/"
+as storage to "/mnt/mini_fo-basedir1/". It has more options though,
+type "mini_fo-overlay -h" for details.
+
+
+DOCUMENTATION, REPORTING BUGS, GETTING HELP
+-------------------------------------------
+
+Please visit the mini_fo project page at:
+
+http://www.denx.de/twiki/bin/view/Know/MiniFOHome
+
+
+WARNINGS
+--------
+
+Never modify the base or the storage directorys while the mini_fo
+file system is mounted, or you might crash you system. Simply accessing
+and reading should not cause any trouble.
+
+Exporting a mini_fo mount point via NFS has not been tested, and may
+or may not work.
+
+Check the RELEASE_NOTES for details on bugs and features.
+
+
+
+Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version
+2 of the License, or (at your option) any later version.
+
+
diff -urN linux-2.6.21.1.old/fs/mini_fo/RELEASE_NOTES linux-2.6.21.1.dev/fs/mini_fo/RELEASE_NOTES
--- linux-2.6.21.1.old/fs/mini_fo/RELEASE_NOTES 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/RELEASE_NOTES 2007-05-26 21:01:26.168329112 +0200
@@ -0,0 +1,111 @@
+Release:       mini_fo-0.6.1 (v0-6-1)
+Date:          21.09.2005
+
+
+Changes:
+--------
+v0-6-1:
+
+- bugfixes (see ChangeLog)
+
+- two helper scripts "mini_fo_merge" and "mini_fo_overlay" (see
+  README for details).
+
+v0-6-0:
+
+- Support for 2.4 and 2.6 (see Makefile)
+
+- Partial hard link support (creating works as expected, but already
+  existing links in the base file system will be treated as if they
+  were individual files).
+
+- Various bugfixes and cleanups.
+
+
+v0-6-0-pre1:
+
+- This is mini_fo-0-6-0-pre1! This release is a complete rewrite of
+  many vital mini_fo parts such as the old whiteout list code which
+  has been replaced by the new META subsystem.
+
+- Light weight directory renaming implemented. This means if a
+  directory is renamed via the mini_fo filesystem this will no longer
+  result in a complete copy in storage, instead only one empty
+  directory will be created. All base filed contained in the original
+  directory stay there until modified.
+
+- Special files (creating, renaming, deleting etc.) now working.
+
+- Many bugfixes and cleanup, mini_fo is now a lot more stable.
+
+
+v0-5-10:
+
+- Final release of the 0-5-* versions. Next will be a complete rewrite
+  of many features. This release contains several bugfixes related to
+  directory renaming.
+
+
+v0-5-10-pre6:
+
+- Lots of cleanup and several bugfixes related to directory deleting
+
+- Directory renaming suddenly works, what is most likely due to the
+  fact tha that "mv" is smart: if the classic rename doesn't work it
+  will assume that source and target file are on different fs and will
+  copy the directory and try to remove the source directory. Until
+  directory removing wasn't implemented, it would fail to do this and
+  rollback.
+  So, directory renaming works for now, but it doesn't yet do what you
+  would expect from a overlay fs, so use with care.
+
+
+v0-5-10-pre5:
+
+- implemented directory deleting 
+- made parsing of mount options more stable
+- New format of mount options! (See README)
+- I can't reproduce the unknown panic with 2.4.25 anymore, so I'll
+  happily assume it never existed!
+
+
+Implemented features:
+---------------------
+
+- creating hard links (see BUGS on already existing hard links)        
+- lightweight directory renaming
+- renaming device files, pipes, sockets, etc.  
+- creating, renaming, deleting of special files 
+- deleting directorys
+- general directory reading (simple "ls" )
+- creating files in existing directorys
+- creating directorys
+- renaming files.
+- reading and writing files (involves opening)
+- appending to files (creates copy in storage)
+- deleting files
+- llseek works too, what allows editors to work
+- persistency (a deleted file stay deleted over remounts)
+- use of symbolic links
+- creating of device files
+
+
+Not (yet) implemented features:
+-------------------------------
+
+- full hard link support.
+
+
+
+BUGS:
+-----
+
+Hard links in the base file system will be treated as individual
+files, not as links to one inode.
+
+The main problem with hard links isn't allowing to create them, but
+their pure existence. If you modify a base hard link, the changes made
+will only show up on this link, the other link will remain in the
+original state. I hope to fix this someday. Please note that this does
+not effect the special hard links '.' and '..', that are handled
+seperately by the lower fs.
diff -urN linux-2.6.21.1.old/fs/mini_fo/state.c linux-2.6.21.1.dev/fs/mini_fo/state.c
--- linux-2.6.21.1.old/fs/mini_fo/state.c       1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/state.c       2007-05-26 21:01:26.169328960 +0200
@@ -0,0 +1,620 @@
+/*
+ * Copyright (C) 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif /* HAVE_CONFIG_H */
+
+#include "fist.h"
+#include "mini_fo.h"
+
+
+/* create the storage file, setup new states */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+int create_sto_reg_file(dentry_t *dentry, int mode, struct nameidata *nd)
+#else
+int create_sto_reg_file(dentry_t *dentry, int mode)
+#endif
+{
+       int err = 0;
+       inode_t *dir;
+       dentry_t *hidden_sto_dentry;
+       dentry_t *hidden_sto_dir_dentry;
+
+       if(exists_in_storage(dentry)) {
+               printk(KERN_CRIT "mini_fo: create_sto_file: wrong type or state.\n");
+               err = -EINVAL;
+               goto out;
+       }
+       err = get_neg_sto_dentry(dentry);
+
+       if (err) {
+               printk(KERN_CRIT "mini_fo: create_sto_file: ERROR getting neg. sto dentry.\n");
+               goto out;
+       }
+       
+       dir = dentry->d_parent->d_inode;
+       hidden_sto_dentry = dtohd2(dentry);
+
+       /* lock parent */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+        down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+       err = PTR_ERR(hidden_sto_dir_dentry);
+        if (IS_ERR(hidden_sto_dir_dentry))
+                goto out;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+       err = vfs_create(hidden_sto_dir_dentry->d_inode,
+                        hidden_sto_dentry,
+                        mode, nd);
+#else
+       err = vfs_create(hidden_sto_dir_dentry->d_inode,
+                        hidden_sto_dentry,
+                        mode);
+#endif
+        if(err) {
+               printk(KERN_CRIT "mini_fo: create_sto_file: ERROR creating sto file.\n");
+                goto out_lock;
+       }
+
+       if(!dtohd2(dentry)->d_inode) {
+               printk(KERN_CRIT "mini_fo: create_sto_file: ERROR creating sto file [2].\n");
+                err = -EINVAL;
+                goto out_lock;
+        }
+
+        /* interpose the new inode */
+        if(dtost(dentry) == DELETED) {
+                dtost(dentry) = DEL_REWRITTEN;
+                err = mini_fo_tri_interpose(NULL, hidden_sto_dentry, dentry, dir->i_sb, 0);
+                if(err)
+                        goto out_lock;
+        }
+        else if(dtost(dentry) == NON_EXISTANT) {
+                dtost(dentry) = CREATED;
+                err = mini_fo_tri_interpose(dtohd(dentry), hidden_sto_dentry, dentry, dir->i_sb, 0);
+                if(err)
+                        goto out_lock;
+        }
+        else if(dtost(dentry) == UNMODIFIED) {
+                dtost(dentry) = MODIFIED;
+                /* interpose on new inode */
+                if(itohi2(dentry->d_inode) != NULL) {
+                        printk(KERN_CRIT "mini_fo: create_sto_file: invalid inode detected.\n");
+                        err = -EINVAL;
+                        goto out_lock;
+                }
+                itohi2(dentry->d_inode) = igrab(dtohd2(dentry)->d_inode);
+       }
+       fist_copy_attr_timesizes(dentry->d_parent->d_inode, 
+                                hidden_sto_dir_dentry->d_inode);
+
+ out_lock:
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+        dput(hidden_sto_dir_dentry);
+ out:
+       return err;
+}
+
+/* create the sto dir, setup states */
+int create_sto_dir(dentry_t *dentry, int mode)
+{
+       int err = 0;
+       inode_t *dir;
+       dentry_t *hidden_sto_dentry;
+        dentry_t *hidden_sto_dir_dentry;
+
+       /* had to take the "!S_ISDIR(mode))" check out, because it failed */
+       if(exists_in_storage(dentry)) {
+                printk(KERN_CRIT "mini_fo: create_sto_dir: wrong type or state.\\
+n");
+                err = -EINVAL;
+                goto out;
+        }
+       
+       err = get_neg_sto_dentry(dentry);
+       if(err) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       dir = dentry->d_parent->d_inode;
+       hidden_sto_dentry = dtohd2(dentry);
+
+       /* was: hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry); */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+       err = PTR_ERR(hidden_sto_dir_dentry);
+       if (IS_ERR(hidden_sto_dir_dentry))
+               goto out;
+       
+       err = vfs_mkdir(hidden_sto_dir_dentry->d_inode,
+                       hidden_sto_dentry,
+                       mode);
+       if(err) {
+               printk(KERN_CRIT "mini_fo: create_sto_dir: ERROR creating sto dir.\n");
+               goto out_lock;
+       }
+
+       if(!dtohd2(dentry)->d_inode) {
+               printk(KERN_CRIT "mini_fo: create_sto_dir: ERROR creating sto dir [2].\n");
+               err = -EINVAL;
+               goto out_lock;
+       }
+
+       /* interpose the new inode */
+       if(dtost(dentry) == DELETED) {
+               dtost(dentry) = DEL_REWRITTEN;
+               err = mini_fo_tri_interpose(NULL, hidden_sto_dentry, dentry, dir->i_sb, 0);
+               if(err)
+                       goto out_lock;
+       }
+       else if(dtopd(dentry)->state == NON_EXISTANT) {
+               dtopd(dentry)->state = CREATED;
+               err = mini_fo_tri_interpose(dtohd(dentry), hidden_sto_dentry, dentry, dir->i_sb, 0);
+               if(err)
+                       goto out_lock;
+       }
+       else if(dtopd(dentry)->state == UNMODIFIED) {
+               dtopd(dentry)->state = MODIFIED;
+               /* interpose on new inode */
+               if(itohi2(dentry->d_inode) != NULL) {
+                       printk(KERN_CRIT "mini_fo:  create_sto_dir: ERROR, invalid inode detected.\n");
+                       err = -EINVAL;
+                       goto out_lock;
+               }
+               itohi2(dentry->d_inode) = igrab(dtohd2(dentry)->d_inode);
+       }
+
+       fist_copy_attr_timesizes(dir, hidden_sto_dir_dentry->d_inode);
+
+       /* initalize the wol list */
+       itopd(dentry->d_inode)->deleted_list_size = -1;
+       itopd(dentry->d_inode)->renamed_list_size = -1;
+       meta_build_lists(dentry);
+
+
+ out_lock:
+       /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_sto_dir_dentry);
+ out:
+       return err;
+}
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+int create_sto_nod(dentry_t *dentry, int mode, dev_t dev) 
+#else
+int create_sto_nod(dentry_t *dentry, int mode, int dev) 
+#endif
+{
+       int err = 0;
+       inode_t *dir;
+       dentry_t *hidden_sto_dentry;
+       dentry_t *hidden_sto_dir_dentry;
+
+       if(exists_in_storage(dentry)) {
+               err = -EEXIST;
+               goto out;
+       }
+       err = get_neg_sto_dentry(dentry);
+
+       if (err) {
+                printk(KERN_CRIT "mini_fo: create_sto_nod: ERROR getting neg. sto dentry.\n");
+                goto out;
+        }      
+
+       dir = dentry->d_parent->d_inode;
+       hidden_sto_dentry = dtohd2(dentry);
+       
+       /* lock parent */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       
+       err = PTR_ERR(hidden_sto_dir_dentry);
+       if (IS_ERR(hidden_sto_dir_dentry))
+               goto out;
+
+       err = vfs_mknod(hidden_sto_dir_dentry->d_inode, hidden_sto_dentry, mode, dev);
+       if(err)
+               goto out_lock;
+
+       if(!dtohd2(dentry)->d_inode) {
+               printk(KERN_CRIT "mini_fo: create_sto_nod: creating storage inode failed [1].\n");
+               err = -EINVAL; /* return something indicating failure */
+               goto out_lock;
+       }
+
+       /* interpose the new inode */
+       if(dtost(dentry) == DELETED) {
+               dtost(dentry) = DEL_REWRITTEN;
+               err = mini_fo_tri_interpose(NULL, hidden_sto_dentry, dentry, dir->i_sb, 0);
+               if(err)
+                       goto out_lock;
+       }
+       else if(dtost(dentry) == NON_EXISTANT) {
+               dtost(dentry) = CREATED;
+               err = mini_fo_tri_interpose(dtohd(dentry), hidden_sto_dentry, dentry, dir->i_sb, 0);
+               if(err)
+                       goto out_lock;
+       }
+       else if(dtost(dentry) == UNMODIFIED) {
+               dtost(dentry) = MODIFIED;
+               /* interpose on new inode */
+               if(itohi2(dentry->d_inode) != NULL) {
+                       printk(KERN_CRIT "mini_fo: create_sto_nod: error, invalid inode detected.\n");
+                       err = -EINVAL;
+                       goto out_lock;
+               }
+               itohi2(dentry->d_inode) = igrab(dtohd2(dentry)->d_inode);
+       }
+
+       fist_copy_attr_timesizes(dir, hidden_sto_dir_dentry->d_inode);
+
+ out_lock:
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_sto_dir_dentry);
+ out:
+       return err;
+}
+
+
+/* unimplemented (and possibly not usefull): 
+
+   nondir-del_to_del_rew
+   nondir-non_exist_to_creat
+
+   dir-unmod_to_del
+   dir-mod_to_del
+   dir-creat_to_del
+   dir-del_rew_to_del
+   dir-del_to_del_rew
+   dir-non_exist_to_creat
+*/
+
+
+/* bring a file of any type from state UNMODIFIED to MODIFIED */
+int nondir_unmod_to_mod(dentry_t *dentry, int cp_flag) 
+{
+       int err = 0;
+       struct vfsmount *tgt_mnt;
+       struct vfsmount *src_mnt;
+       dentry_t *tgt_dentry;
+       dentry_t *src_dentry;
+       dentry_t *hidden_sto_dentry;
+       dentry_t *hidden_sto_dir_dentry;
+
+       check_mini_fo_dentry(dentry);
+
+       if((dtost(dentry) != UNMODIFIED) ||
+          S_ISDIR(dentry->d_inode->i_mode)) {
+               printk(KERN_CRIT "mini_fo: nondir_unmod_to_mod: \
+                                  wrong type or state.\n");
+               err = -1;
+               goto out;
+       }
+       err = get_neg_sto_dentry(dentry);
+
+       if (err) {
+               printk(KERN_CRIT "mini_fo: nondir_unmod_to_mod: \
+                                  ERROR getting neg. sto dentry.\n");
+               goto out;
+       }
+       
+       /* create sto file */
+       hidden_sto_dentry = dtohd2(dentry);
+
+       /* lock parent */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+        down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+       err = PTR_ERR(hidden_sto_dir_dentry);
+        if (IS_ERR(hidden_sto_dir_dentry))
+                goto out;
+
+       /* handle different types of nondirs */
+       if(S_ISCHR(dentry->d_inode->i_mode) ||
+          S_ISBLK(dentry->d_inode->i_mode)) {
+               err = vfs_mknod(hidden_sto_dir_dentry->d_inode,
+                               hidden_sto_dentry,
+                               dtohd(dentry)->d_inode->i_mode,
+                               dtohd(dentry)->d_inode->i_rdev);
+       }
+       
+       else if(S_ISREG(dentry->d_inode->i_mode)) {
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+               err = vfs_create(hidden_sto_dir_dentry->d_inode,
+                                hidden_sto_dentry,
+                                dtohd(dentry)->d_inode->i_mode, NULL);
+#else
+               err = vfs_create(hidden_sto_dir_dentry->d_inode,
+                                hidden_sto_dentry,
+                                dtohd(dentry)->d_inode->i_mode);
+#endif
+       }
+        if(err) {
+               printk(KERN_CRIT "mini_fo: nondir_unmod_to_mod: \
+                                  ERROR creating sto file.\n");
+                goto out_lock;
+       }
+
+       /* interpose on new inode */
+       if(itohi2(dentry->d_inode) != NULL) {
+               printk(KERN_CRIT "mini_fo: nondir_unmod_to_mod: \
+                                  ERROR, invalid inode detected.\n");
+               err = -EINVAL;
+               goto out_lock;
+       }
+
+       itohi2(dentry->d_inode) = igrab(dtohd2(dentry)->d_inode);
+        
+        fist_copy_attr_timesizes(dentry->d_parent->d_inode, 
+                                hidden_sto_dir_dentry->d_inode);
+       dtost(dentry) = MODIFIED;
+
+       /* copy contents if regular file and cp_flag = 1 */
+       if((cp_flag == 1) && S_ISREG(dentry->d_inode->i_mode)) {
+
+               /* unlock first */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+               mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+               up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+
+               dput(hidden_sto_dir_dentry);
+
+               tgt_dentry = dtohd2(dentry);
+               tgt_mnt = stopd(dentry->d_inode->i_sb)->hidden_mnt2;
+               src_dentry = dtohd(dentry);
+               src_mnt = stopd(dentry->d_inode->i_sb)->hidden_mnt;
+               
+               err = mini_fo_cp_cont(tgt_dentry, tgt_mnt, 
+                                     src_dentry, src_mnt);
+               if(err) {
+                       printk(KERN_CRIT "mini_fo: nondir_unmod_to_mod: \
+                                          ERROR copying contents.\n");
+               }
+               goto out;       
+       }
+
+ out_lock:
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+        dput(hidden_sto_dir_dentry);
+ out:
+       return err;
+}
+
+/* this function is currently identical to nondir_creat_to_del */
+int nondir_del_rew_to_del(dentry_t *dentry)
+{
+       return nondir_creat_to_del(dentry);
+}
+
+int nondir_creat_to_del(dentry_t *dentry) 
+{
+       int err = 0;
+
+       inode_t *hidden_sto_dir_inode;
+       dentry_t *hidden_sto_dir_dentry;
+       dentry_t *hidden_sto_dentry;
+       
+       check_mini_fo_dentry(dentry);
+
+       /* for now this function serves for both state DEL_REWRITTEN and 
+        * CREATED */
+       if(!(dtost(dentry) == CREATED || (dtost(dentry) == DEL_REWRITTEN)) ||
+          S_ISDIR(dentry->d_inode->i_mode)) {
+               printk(KERN_CRIT "mini_fo: nondir_mod_to_del/del_rew_to_del: \
+                                  wrong type or state.\n");
+               err = -1;
+               goto out;
+       }
+       
+       hidden_sto_dir_inode = itohi2(dentry->d_parent->d_inode);
+       hidden_sto_dentry = dtohd2(dentry);
+       
+       /* was: hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry);*/
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       
+       /* avoid destroying the hidden inode if the file is in use */
+       dget(hidden_sto_dentry);
+       err = vfs_unlink(hidden_sto_dir_inode, hidden_sto_dentry);
+       dput(hidden_sto_dentry);
+       if(!err)
+               d_delete(hidden_sto_dentry);
+       
+       /* propagate number of hard-links */
+       dentry->d_inode->i_nlink = itohi2(dentry->d_inode)->i_nlink;
+       
+       dtost(dentry) = NON_EXISTANT;
+       
+       /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_sto_dir_dentry);
+       
+ out:
+       return err;
+}
+
+int nondir_mod_to_del(dentry_t *dentry)
+{
+       int err;
+       dentry_t *hidden_sto_dentry;
+       inode_t *hidden_sto_dir_inode;
+       dentry_t *hidden_sto_dir_dentry;
+       
+       check_mini_fo_dentry(dentry);
+
+       if(dtost(dentry) != MODIFIED ||
+          S_ISDIR(dentry->d_inode->i_mode)) {
+               printk(KERN_CRIT "mini_fo: nondir_mod_to_del: \
+                                  wrong type or state.\n");
+               err = -1;
+               goto out;
+       }
+
+       hidden_sto_dir_inode = itohi2(dentry->d_parent->d_inode);
+       hidden_sto_dentry = dtohd2(dentry);
+       
+       /* was hidden_sto_dir_dentry = lock_parent(hidden_sto_dentry); */
+       hidden_sto_dir_dentry = dget(hidden_sto_dentry->d_parent);
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_lock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       down(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       
+       /* avoid destroying the hidden inode if the file is in use */
+       dget(hidden_sto_dentry);
+       err = vfs_unlink(hidden_sto_dir_inode, hidden_sto_dentry);
+       dput(hidden_sto_dentry);
+       if(!err)
+               d_delete(hidden_sto_dentry);
+       
+       /* propagate number of hard-links */
+       dentry->d_inode->i_nlink = itohi2(dentry->d_inode)->i_nlink;
+       
+       /* dput base dentry, this will relase the inode and free the
+        * dentry, as we will never need it again. */
+       dput(dtohd(dentry));
+       dtohd(dentry) = NULL;
+       dtost(dentry) = DELETED;
+
+       /* add deleted file to META-file */
+       meta_add_d_entry(dentry->d_parent, 
+                        dentry->d_name.name, 
+                        dentry->d_name.len);
+       
+       /* was: unlock_dir(hidden_sto_dir_dentry); */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+       mutex_unlock(&hidden_sto_dir_dentry->d_inode->i_mutex);
+#else
+       up(&hidden_sto_dir_dentry->d_inode->i_sem);
+#endif
+       dput(hidden_sto_dir_dentry);
+
+ out:
+       return err;
+}
+
+int nondir_unmod_to_del(dentry_t *dentry)
+{
+       int err = 0;
+
+       check_mini_fo_dentry(dentry);
+
+       if(dtost(dentry) != UNMODIFIED ||
+          S_ISDIR(dentry->d_inode->i_mode)) {
+               printk(KERN_CRIT "mini_fo: nondir_unmod_to_del: \
+                                  wrong type or state.\n");
+               err = -1;
+               goto out;
+       }
+       
+        /* next we have to get a negative dentry for the storage file */
+       err = get_neg_sto_dentry(dentry);
+
+       if(err)
+               goto out;               
+
+       /* add deleted file to META lists */
+       err = meta_add_d_entry(dentry->d_parent, 
+                              dentry->d_name.name, 
+                              dentry->d_name.len);
+
+       if(err)
+               goto out;
+       
+       /* dput base dentry, this will relase the inode and free the
+        * dentry, as we will never need it again. */
+       dput(dtohd(dentry));
+       dtohd(dentry) = NULL;
+       dtost(dentry) = DELETED;
+       
+ out:
+       return err;
+}
+
+/* bring a dir from state UNMODIFIED to MODIFIED */
+int dir_unmod_to_mod(dentry_t *dentry) 
+{
+       int err;
+
+       check_mini_fo_dentry(dentry);
+
+       if(dtost(dentry) != UNMODIFIED ||
+          !S_ISDIR(dentry->d_inode->i_mode)) {
+               printk(KERN_CRIT "mini_fo: dir_unmod_to_mod: \
+                                  wrong type or state.\n");
+               err = -1;
+               goto out;
+       }
+
+       /* this creates our dir incl. sto. structure */
+       err = build_sto_structure(dentry->d_parent, dentry);
+       if(err) {
+               printk(KERN_CRIT "mini_fo: dir_unmod_to_mod: \
+                                  build_sto_structure failed.\n");
+               goto out;
+       }
+ out:
+       return err;
+}
+
diff -urN linux-2.6.21.1.old/fs/mini_fo/super.c linux-2.6.21.1.dev/fs/mini_fo/super.c
--- linux-2.6.21.1.old/fs/mini_fo/super.c       1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.21.1.dev/fs/mini_fo/super.c       2007-05-26 21:01:26.169328960 +0200
@@ -0,0 +1,281 @@
+/*
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
+ *
+ * This Copyright notice must be kept intact and distributed with all
+ * fistgen sources INCLUDING sources generated by fistgen.
+ */
+/*
+ * Copyright (C) 2004, 2005 Markus Klotzbuecher <mk@creamnet.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif 
+
+#include "fist.h"
+#include "mini_fo.h"
+
+
+STATIC void
+mini_fo_read_inode(inode_t *inode)
+{
+       static struct address_space_operations mini_fo_empty_aops;
+
+       __itopd(inode) = kmalloc(sizeof(struct mini_fo_inode_info), GFP_KERNEL);
+       if (!itopd(inode)) {
+               printk("<0>%s:%s:%d: No kernel memory!\n", __FILE__, __FUNCTION__, __LINE__);
+               ASSERT(NULL);
+       }
+       itohi(inode) = NULL;
+       itohi2(inode) = NULL;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+       inode->i_version++;
+#else
+       inode->i_version = ++event;     /* increment inode version */
+#endif
+       inode->i_op = &mini_fo_main_iops;
+       inode->i_fop = &mini_fo_main_fops;
+#if 0
+       /*
+        * XXX: To export a file system via NFS, it has to have the
+        * FS_REQUIRES_DEV flag, so turn it on.  But should we inherit it from
+        * the lower file system, or can we allow our file system to be exported
+        * even if the lower one cannot be natively exported.
+        */
+       inode->i_sb->s_type->fs_flags |= FS_REQUIRES_DEV;
+       /*
+        * OK, the above was a hack, which is now turned off because it may
+        * cause a panic/oops on some systems.  The correct way to export a
+        * "nodev" filesystem is via using nfs-utils > 1.0 and the "fsid=" export
+        * parameter, which requires 2.4.20 or later.
+        */
+#endif
+       /* I don't think ->a_ops is ever allowed to be NULL */
+       inode->i_mapping->a_ops = &mini_fo_empty_aops;
+}
+
+
+#if defined(FIST_DEBUG) || defined(FIST_FILTER_SCA)
+/*
+ * No need to call write_inode() on the lower inode, as it
+ * will have been marked 'dirty' anyway. But we might need
+ * to write some of our own stuff to disk.
+ */
+STATIC void
+mini_fo_write_inode(inode_t *inode, int sync)
+{
+       print_entry_location();
+       print_exit_location();
+}
+#endif /* defined(FIST_DEBUG) || defined(FIST_FILTER_SCA) */
+
+
+STATIC void
+mini_fo_put_inode(inode_t *inode)
+{
+       /*
+        * This is really funky stuff:
+        * Basically, if i_count == 1, iput will then decrement it and this inode will be destroyed.
+        * It is currently holding a reference to the hidden inode.
+        * Therefore, it needs to release that reference by calling iput on the hidden inode.
+        * iput() _will_ do it for us (by calling our clear_inode), but _only_ if i_nlink == 0.
+        * The problem is, NFS keeps i_nlink == 1 for silly_rename'd files.
+        * So we must for our i_nlink to 0 here to trick iput() into calling our clear_inode.
+        */
+       if (atomic_read(&inode->i_count) == 1)
+               inode->i_nlink = 0;
+}
+
+
+#if defined(FIST_DEBUG) || defined(FIST_FILTER_SCA)
+/*
+ * we now define delete_inode, because there are two VFS paths that may
+ * destroy an inode: one of them calls clear inode before doing everything
+ * else that's needed, and the other is fine.  This way we truncate the inode
+ * size (and its pages) and then clear our own inode, which will do an iput
+ * on our and the lower inode.
+ */
+STATIC void
+mini_fo_delete_inode(inode_t *inode)
+{
+       print_entry_location();
+
+       fist_checkinode(inode, "mini_fo_delete_inode IN");
+       inode->i_size = 0;              /* every f/s seems to do that */
+       clear_inode(inode);
+
+       print_exit_location();
+}
+#endif /* defined(FIST_DEBUG) || defined(FIST_FILTER_SCA) */
+
+
+/* final actions when unmounting a file system */
+STATIC void
+mini_fo_put_super(super_block_t *sb)
+{
+       if (stopd(sb)) {
+               mntput(stopd(sb)->hidden_mnt);
+               mntput(stopd(sb)->hidden_mnt2);
+
+               /* mk: no! dput(stopd(sb)->base_dir_dentry); 
+                  dput(stopd(sb)->storage_dir_dentry); */
+
+               kfree(stopd(sb));
+               __stopd(sb) = NULL;
+       }
+}
+
+
+#ifdef NOT_NEEDED
+/*
+ * This is called in do_umount before put_super.
+ * The superblock lock is not held yet.
+ * We probably do not need to define this or call write_super
+ * on the hidden_sb, because sync_supers() will get to hidden_sb
+ * sooner or later.  But it is also called from file_fsync()...
+ */
+STATIC void
+mini_fo_write_super(super_block_t *sb)
+{
+       return;
+}
+#endif /* NOT_NEEDED */
+
+
+STATIC int
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+mini_fo_statfs(struct dentry *d, struct kstatfs *buf)
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+mini_fo_statfs(super_block_t *sb, struct kstatfs *buf)
+#else
+mini_fo_statfs(super_block_t *sb, struct statfs *buf)
+#endif
+{
+       int err = 0;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+       struct dentry *hidden_d;
+
+       hidden_d = dtohd(d);
+       err = vfs_statfs(hidden_d, buf);
+#else
+       super_block_t *hidden_sb;
+
+       hidden_sb = stohs(sb);
+       err = vfs_statfs(hidden_sb, buf);
+#endif
+
+       return err;
+}
+
+
+/*
+ * XXX: not implemented.  This is not allowed yet.
+ * Should we call this on the hidden_sb?  Probably not.
+ */
+STATIC int
+mini_fo_remount_fs(super_block_t *sb, int *flags, char *data)
+{
+       //printk(KERN_CRIT "mini_fo_remount_fs: WARNING, this function is umimplemented.\n");
+       return -ENOSYS;
+}
+
+
+/*
+ * Called by iput() when the inode reference count reached zero
+ * and the inode is not hashed anywhere.  Used to clear anything
+ * that needs to be, before the inode is completely destroyed and put
+ * on the inode free list.
+ */
+STATIC void
+mini_fo_clear_inode(inode_t *inode)
+{
+       /*
+        * Decrement a reference to a hidden_inode, which was incremented
+        * by our read_inode when it was created initially.
+        */
+
+       /* release the wol_list */
+       if(S_ISDIR(inode->i_mode)) {
+               __meta_put_lists(inode);
+       }
+
+       /* mk: fan out fun */
+       if(itohi(inode))
+               iput(itohi(inode));
+       if(itohi2(inode))
+               iput(itohi2(inode));
+
+       // XXX: why this assertion fails?
+       // because it doesn't like us
+       // ASSERT((inode->i_state & I_DIRTY) == 0);
+       kfree(itopd(inode));
+       __itopd(inode) = NULL;
+}
+
+
+/*
+ * Called in do_umount() if the MNT_FORCE flag was used and this
+ * function is defined.  See comment in linux/fs/super.c:do_umount().
+ * Used only in nfs, to kill any pending RPC tasks, so that subsequent
+ * code can actually succeed and won't leave tasks that need handling.
+ *
+ * PS. I wonder if this is somehow useful to undo damage that was
+ * left in the kernel after a user level file server (such as amd)
+ * dies.
+ */
+STATIC void
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+mini_fo_umount_begin(struct vfsmount *mnt, int flags)
+{
+       struct vfsmount *hidden_mnt;
+
+       hidden_mnt = stopd(mnt->mnt_sb)->hidden_mnt;
+
+       if (hidden_mnt->mnt_sb->s_op->umount_begin)
+               hidden_mnt->mnt_sb->s_op->umount_begin(hidden_mnt, flags);
+
+}
+#else
+mini_fo_umount_begin(super_block_t *sb)
+{
+       super_block_t *hidden_sb;
+
+       hidden_sb = stohs(sb);
+
+       if (hidden_sb->s_op->umount_begin)
+               hidden_sb->s_op->umount_begin(hidden_sb);
+
+}
+#endif
+
+
+struct super_operations mini_fo_sops =
+{
+       read_inode:             mini_fo_read_inode,
+#if defined(FIST_DEBUG) || defined(FIST_FILTER_SCA)
+       write_inode:    mini_fo_write_inode,
+#endif /* defined(FIST_DEBUG) || defined(FIST_FILTER_SCA) */
+       put_inode:              mini_fo_put_inode,
+#if defined(FIST_DEBUG) || defined(FIST_FILTER_SCA)
+       delete_inode:   mini_fo_delete_inode,
+#endif /* defined(FIST_DEBUG) || defined(FIST_FILTER_SCA) */
+       put_super:              mini_fo_put_super,
+       statfs:         mini_fo_statfs,
+       remount_fs:             mini_fo_remount_fs,
+       clear_inode:    mini_fo_clear_inode,
+       umount_begin:   mini_fo_umount_begin,
+};