fs/bfs/dir.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      fs/bfs/dir.c
   4  *      BFS directory operations.
   5  *      Copyright (C) 1999,2000  Tigran Aivazian <tigran@veritas.com>
   6  *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
   7  */
   8
   9 #include <linux/time.h>
  10 #include <linux/string.h>
  11 #include <linux/fs.h>
  12 #include <linux/buffer_head.h>
  13 #include <linux/sched.h>
  14 #include "bfs.h"
  15
  16 #undef DEBUG
  17
  18 #ifdef DEBUG
  19 #define dprintf(x...)   printf(x)
  20 #else
  21 #define dprintf(x...)
  22 #endif
  23
  24 static int bfs_add_entry(struct inode *dir, const unsigned char *name,
  25                                                 int namelen, int ino);
  26 static struct buffer_head *bfs_find_entry(struct inode *dir,
  27                                 const unsigned char *name, int namelen,
  28                                 struct bfs_dirent **res_dir);
  29
  30 static int bfs_readdir(struct file *f, struct dir_context *ctx)
  31 {
  32         struct inode *dir = file_inode(f);
  33         struct buffer_head *bh;
  34         struct bfs_dirent *de;
  35         unsigned int offset;
  36         int block;
  37
  38         if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
  39                 printf("Bad f_pos=%08lx for %s:%08lx\n",
  40                                         (unsigned long)ctx->pos,
  41                                         dir->i_sb->s_id, dir->i_ino);
  42                 return -EINVAL;
  43         }
  44
  45         while (ctx->pos < dir->i_size) {
  46                 offset = ctx->pos & (BFS_BSIZE - 1);
  47                 block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
  48                 bh = sb_bread(dir->i_sb, block);
  49                 if (!bh) {
  50                         ctx->pos += BFS_BSIZE - offset;
  51                         continue;
  52                 }
  53                 do {
  54                         de = (struct bfs_dirent *)(bh->b_data + offset);
  55                         if (de->ino) {
  56                                 int size = strnlen(de->name, BFS_NAMELEN);
  57                                 if (!dir_emit(ctx, de->name, size,
  58                                                 le16_to_cpu(de->ino),
  59                                                 DT_UNKNOWN)) {
  60                                         brelse(bh);
  61                                         return 0;
  62                                 }
  63                         }
  64                         offset += BFS_DIRENT_SIZE;
  65                         ctx->pos += BFS_DIRENT_SIZE;
  66                 } while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
  67                 brelse(bh);
  68         }
  69         return 0;
  70 }
  71
  72 const struct file_operations bfs_dir_operations = {
  73         .read           = generic_read_dir,
  74         .iterate_shared = bfs_readdir,
  75         .fsync          = generic_file_fsync,
  76         .llseek         = generic_file_llseek,
  77 };
  78
  79 static int bfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
  80                                                 bool excl)
  81 {
  82         int err;
  83         struct inode *inode;
  84         struct super_block *s = dir->i_sb;
  85         struct bfs_sb_info *info = BFS_SB(s);
  86         unsigned long ino;
  87
  88         inode = new_inode(s);
  89         if (!inode)
  90                 return -ENOMEM;
  91         mutex_lock(&info->bfs_lock);
  92         ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
  93         if (ino > info->si_lasti) {
  94                 mutex_unlock(&info->bfs_lock);
  95                 iput(inode);
  96                 return -ENOSPC;
  97         }
  98         set_bit(ino, info->si_imap);
  99         info->si_freei--;
 100         inode_init_owner(inode, dir, mode);
 101         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 102         inode->i_blocks = 0;
 103         inode->i_op = &bfs_file_inops;
 104         inode->i_fop = &bfs_file_operations;
 105         inode->i_mapping->a_ops = &bfs_aops;
 106         inode->i_ino = ino;
 107         BFS_I(inode)->i_dsk_ino = ino;
 108         BFS_I(inode)->i_sblock = 0;
 109         BFS_I(inode)->i_eblock = 0;
 110         insert_inode_hash(inode);
 111         mark_inode_dirty(inode);
 112         bfs_dump_imap("create", s);
 113
 114         err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len,
 115                                                         inode->i_ino);
 116         if (err) {
 117                 inode_dec_link_count(inode);
 118                 mutex_unlock(&info->bfs_lock);
 119                 iput(inode);
 120                 return err;
 121         }
 122         mutex_unlock(&info->bfs_lock);
 123         d_instantiate(dentry, inode);
 124         return 0;
 125 }
 126
 127 static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
 128                                                 unsigned int flags)
 129 {
 130         struct inode *inode = NULL;
 131         struct buffer_head *bh;
 132         struct bfs_dirent *de;
 133         struct bfs_sb_info *info = BFS_SB(dir->i_sb);
 134
 135         if (dentry->d_name.len > BFS_NAMELEN)
 136                 return ERR_PTR(-ENAMETOOLONG);
 137
 138         mutex_lock(&info->bfs_lock);
 139         bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
 140         if (bh) {
 141                 unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
 142                 brelse(bh);
 143                 inode = bfs_iget(dir->i_sb, ino);
 144                 if (IS_ERR(inode)) {
 145                         mutex_unlock(&info->bfs_lock);
 146                         return ERR_CAST(inode);
 147                 }
 148         }
 149         mutex_unlock(&info->bfs_lock);
 150         d_add(dentry, inode);
 151         return NULL;
 152 }
 153
 154 static int bfs_link(struct dentry *old, struct inode *dir,
 155                                                 struct dentry *new)
 156 {
 157         struct inode *inode = d_inode(old);
 158         struct bfs_sb_info *info = BFS_SB(inode->i_sb);
 159         int err;
 160
 161         mutex_lock(&info->bfs_lock);
 162         err = bfs_add_entry(dir, new->d_name.name, new->d_name.len,
 163                                                         inode->i_ino);
 164         if (err) {
 165                 mutex_unlock(&info->bfs_lock);
 166                 return err;
 167         }
 168         inc_nlink(inode);
 169         inode->i_ctime = current_time(inode);
 170         mark_inode_dirty(inode);
 171         ihold(inode);
 172         d_instantiate(new, inode);
 173         mutex_unlock(&info->bfs_lock);
 174         return 0;
 175 }
 176
 177 static int bfs_unlink(struct inode *dir, struct dentry *dentry)
 178 {
 179         int error = -ENOENT;
 180         struct inode *inode = d_inode(dentry);
 181         struct buffer_head *bh;
 182         struct bfs_dirent *de;
 183         struct bfs_sb_info *info = BFS_SB(inode->i_sb);
 184
 185         mutex_lock(&info->bfs_lock);
 186         bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
 187         if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
 188                 goto out_brelse;
 189
 190         if (!inode->i_nlink) {
 191                 printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
 192                                         inode->i_sb->s_id, inode->i_ino,
 193                                         inode->i_nlink);
 194                 set_nlink(inode, 1);
 195         }
 196         de->ino = 0;
 197         mark_buffer_dirty_inode(bh, dir);
 198         dir->i_ctime = dir->i_mtime = current_time(dir);
 199         mark_inode_dirty(dir);
 200         inode->i_ctime = dir->i_ctime;
 201         inode_dec_link_count(inode);
 202         error = 0;
 203
 204 out_brelse:
 205         brelse(bh);
 206         mutex_unlock(&info->bfs_lock);
 207         return error;
 208 }
 209
 210 static int bfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 211                       struct inode *new_dir, struct dentry *new_dentry,
 212                       unsigned int flags)
 213 {
 214         struct inode *old_inode, *new_inode;
 215         struct buffer_head *old_bh, *new_bh;
 216         struct bfs_dirent *old_de, *new_de;
 217         struct bfs_sb_info *info;
 218         int error = -ENOENT;
 219
 220         if (flags & ~RENAME_NOREPLACE)
 221                 return -EINVAL;
 222
 223         old_bh = new_bh = NULL;
 224         old_inode = d_inode(old_dentry);
 225         if (S_ISDIR(old_inode->i_mode))
 226                 return -EINVAL;
 227
 228         info = BFS_SB(old_inode->i_sb);
 229
 230         mutex_lock(&info->bfs_lock);
 231         old_bh = bfs_find_entry(old_dir,
 232                                 old_dentry->d_name.name,
 233                                 old_dentry->d_name.len, &old_de);
 234
 235         if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
 236                 goto end_rename;
 237
 238         error = -EPERM;
 239         new_inode = d_inode(new_dentry);
 240         new_bh = bfs_find_entry(new_dir,
 241                                 new_dentry->d_name.name,
 242                                 new_dentry->d_name.len, &new_de);
 243
 244         if (new_bh && !new_inode) {
 245                 brelse(new_bh);
 246                 new_bh = NULL;
 247         }
 248         if (!new_bh) {
 249                 error = bfs_add_entry(new_dir,
 250                                         new_dentry->d_name.name,
 251                                         new_dentry->d_name.len,
 252                                         old_inode->i_ino);
 253                 if (error)
 254                         goto end_rename;
 255         }
 256         old_de->ino = 0;
 257         old_dir->i_ctime = old_dir->i_mtime = current_time(old_dir);
 258         mark_inode_dirty(old_dir);
 259         if (new_inode) {
 260                 new_inode->i_ctime = current_time(new_inode);
 261                 inode_dec_link_count(new_inode);
 262         }
 263         mark_buffer_dirty_inode(old_bh, old_dir);
 264         error = 0;
 265
 266 end_rename:
 267         mutex_unlock(&info->bfs_lock);
 268         brelse(old_bh);
 269         brelse(new_bh);
 270         return error;
 271 }
 272
 273 const struct inode_operations bfs_dir_inops = {
 274         .create                 = bfs_create,
 275         .lookup                 = bfs_lookup,
 276         .link                   = bfs_link,
 277         .unlink                 = bfs_unlink,
 278         .rename                 = bfs_rename,
 279 };
 280
 281 static int bfs_add_entry(struct inode *dir, const unsigned char *name,
 282                                                         int namelen, int ino)
 283 {
 284         struct buffer_head *bh;
 285         struct bfs_dirent *de;
 286         int block, sblock, eblock, off, pos;
 287         int i;
 288
 289         dprintf("name=%s, namelen=%d\n", name, namelen);
 290
 291         if (!namelen)
 292                 return -ENOENT;
 293         if (namelen > BFS_NAMELEN)
 294                 return -ENAMETOOLONG;
 295
 296         sblock = BFS_I(dir)->i_sblock;
 297         eblock = BFS_I(dir)->i_eblock;
 298         for (block = sblock; block <= eblock; block++) {
 299                 bh = sb_bread(dir->i_sb, block);
 300                 if (!bh)
 301                         return -EIO;
 302                 for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
 303                         de = (struct bfs_dirent *)(bh->b_data + off);
 304                         if (!de->ino) {
 305                                 pos = (block - sblock) * BFS_BSIZE + off;
 306                                 if (pos >= dir->i_size) {
 307                                         dir->i_size += BFS_DIRENT_SIZE;
 308                                         dir->i_ctime = current_time(dir);
 309                                 }
 310                                 dir->i_mtime = current_time(dir);
 311                                 mark_inode_dirty(dir);
 312                                 de->ino = cpu_to_le16((u16)ino);
 313                                 for (i = 0; i < BFS_NAMELEN; i++)
 314                                         de->name[i] =
 315                                                 (i < namelen) ? name[i] : 0;
 316                                 mark_buffer_dirty_inode(bh, dir);
 317                                 brelse(bh);
 318                                 return 0;
 319                         }
 320                 }
 321                 brelse(bh);
 322         }
 323         return -ENOSPC;
 324 }
 325
 326 static inline int bfs_namecmp(int len, const unsigned char *name,
 327                                                         const char *buffer)
 328 {
 329         if ((len < BFS_NAMELEN) && buffer[len])
 330                 return 0;
 331         return !memcmp(name, buffer, len);
 332 }
 333
 334 static struct buffer_head *bfs_find_entry(struct inode *dir,
 335                         const unsigned char *name, int namelen,
 336                         struct bfs_dirent **res_dir)
 337 {
 338         unsigned long block = 0, offset = 0;
 339         struct buffer_head *bh = NULL;
 340         struct bfs_dirent *de;
 341
 342         *res_dir = NULL;
 343         if (namelen > BFS_NAMELEN)
 344                 return NULL;
 345
 346         while (block * BFS_BSIZE + offset < dir->i_size) {
 347                 if (!bh) {
 348                         bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
 349                         if (!bh) {
 350                                 block++;
 351                                 continue;
 352                         }
 353                 }
 354                 de = (struct bfs_dirent *)(bh->b_data + offset);
 355                 offset += BFS_DIRENT_SIZE;
 356                 if (le16_to_cpu(de->ino) &&
 357                                 bfs_namecmp(namelen, name, de->name)) {
 358                         *res_dir = de;
 359                         return bh;
 360                 }
 361                 if (offset < bh->b_size)
 362                         continue;
 363                 brelse(bh);
 364                 bh = NULL;
 365                 offset = 0;
 366                 block++;
 367         }
 368         brelse(bh);
 369         return NULL;
 370 }