fs/nfs/nfs4super.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
   4  */
   5 #include <linux/init.h>
   6 #include <linux/module.h>
   7 #include <linux/mount.h>
   8 #include <linux/nfs4_mount.h>
   9 #include <linux/nfs_fs.h>
  10 #include "delegation.h"
  11 #include "internal.h"
  12 #include "nfs4_fs.h"
  13 #include "nfs4idmap.h"
  14 #include "dns_resolve.h"
  15 #include "pnfs.h"
  16 #include "nfs.h"
  17
  18 #define NFSDBG_FACILITY         NFSDBG_VFS
  19
  20 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
  21 static void nfs4_evict_inode(struct inode *inode);
  22
  23 static const struct super_operations nfs4_sops = {
  24         .alloc_inode    = nfs_alloc_inode,
  25         .free_inode     = nfs_free_inode,
  26         .write_inode    = nfs4_write_inode,
  27         .drop_inode     = nfs_drop_inode,
  28         .statfs         = nfs_statfs,
  29         .evict_inode    = nfs4_evict_inode,
  30         .umount_begin   = nfs_umount_begin,
  31         .show_options   = nfs_show_options,
  32         .show_devname   = nfs_show_devname,
  33         .show_path      = nfs_show_path,
  34         .show_stats     = nfs_show_stats,
  35 };
  36
  37 struct nfs_subversion nfs_v4 = {
  38         .owner          = THIS_MODULE,
  39         .nfs_fs         = &nfs4_fs_type,
  40         .rpc_vers       = &nfs_version4,
  41         .rpc_ops        = &nfs_v4_clientops,
  42         .sops           = &nfs4_sops,
  43         .xattr          = nfs4_xattr_handlers,
  44 };
  45
  46 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  47 {
  48         int ret = nfs_write_inode(inode, wbc);
  49
  50         if (ret == 0)
  51                 ret = pnfs_layoutcommit_inode(inode,
  52                                 wbc->sync_mode == WB_SYNC_ALL);
  53         return ret;
  54 }
  55
  56 /*
  57  * Clean out any remaining NFSv4 state that might be left over due
  58  * to open() calls that passed nfs_atomic_lookup, but failed to call
  59  * nfs_open().
  60  */
  61 static void nfs4_evict_inode(struct inode *inode)
  62 {
  63         truncate_inode_pages_final(&inode->i_data);
  64         clear_inode(inode);
  65         /* If we are holding a delegation, return and free it */
  66         nfs_inode_evict_delegation(inode);
  67         /* Note that above delegreturn would trigger pnfs return-on-close */
  68         pnfs_return_layout(inode);
  69         pnfs_destroy_layout(NFS_I(inode));
  70         /* First call standard NFS clear_inode() code */
  71         nfs_clear_inode(inode);
  72 }
  73
  74 struct nfs_referral_count {
  75         struct list_head list;
  76         const struct task_struct *task;
  77         unsigned int referral_count;
  78 };
  79
  80 static LIST_HEAD(nfs_referral_count_list);
  81 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
  82
  83 static struct nfs_referral_count *nfs_find_referral_count(void)
  84 {
  85         struct nfs_referral_count *p;
  86
  87         list_for_each_entry(p, &nfs_referral_count_list, list) {
  88                 if (p->task == current)
  89                         return p;
  90         }
  91         return NULL;
  92 }
  93
  94 #define NFS_MAX_NESTED_REFERRALS 2
  95
  96 static int nfs_referral_loop_protect(void)
  97 {
  98         struct nfs_referral_count *p, *new;
  99         int ret = -ENOMEM;
 100
 101         new = kmalloc(sizeof(*new), GFP_KERNEL);
 102         if (!new)
 103                 goto out;
 104         new->task = current;
 105         new->referral_count = 1;
 106
 107         ret = 0;
 108         spin_lock(&nfs_referral_count_list_lock);
 109         p = nfs_find_referral_count();
 110         if (p != NULL) {
 111                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 112                         ret = -ELOOP;
 113                 else
 114                         p->referral_count++;
 115         } else {
 116                 list_add(&new->list, &nfs_referral_count_list);
 117                 new = NULL;
 118         }
 119         spin_unlock(&nfs_referral_count_list_lock);
 120         kfree(new);
 121 out:
 122         return ret;
 123 }
 124
 125 static void nfs_referral_loop_unprotect(void)
 126 {
 127         struct nfs_referral_count *p;
 128
 129         spin_lock(&nfs_referral_count_list_lock);
 130         p = nfs_find_referral_count();
 131         p->referral_count--;
 132         if (p->referral_count == 0)
 133                 list_del(&p->list);
 134         else
 135                 p = NULL;
 136         spin_unlock(&nfs_referral_count_list_lock);
 137         kfree(p);
 138 }
 139
 140 static int do_nfs4_mount(struct nfs_server *server,
 141                          struct fs_context *fc,
 142                          const char *hostname,
 143                          const char *export_path)
 144 {
 145         struct nfs_fs_context *root_ctx;
 146         struct fs_context *root_fc;
 147         struct vfsmount *root_mnt;
 148         struct dentry *dentry;
 149         size_t len;
 150         int ret;
 151
 152         struct fs_parameter param = {
 153                 .key    = "source",
 154                 .type   = fs_value_is_string,
 155                 .dirfd  = -1,
 156         };
 157
 158         if (IS_ERR(server))
 159                 return PTR_ERR(server);
 160
 161         root_fc = vfs_dup_fs_context(fc);
 162         if (IS_ERR(root_fc)) {
 163                 nfs_free_server(server);
 164                 return PTR_ERR(root_fc);
 165         }
 166         kfree(root_fc->source);
 167         root_fc->source = NULL;
 168
 169         root_ctx = nfs_fc2context(root_fc);
 170         root_ctx->internal = true;
 171         root_ctx->server = server;
 172         /* We leave export_path unset as it's not used to find the root. */
 173
 174         len = strlen(hostname) + 5;
 175         param.string = kmalloc(len, GFP_KERNEL);
 176         if (param.string == NULL) {
 177                 put_fs_context(root_fc);
 178                 return -ENOMEM;
 179         }
 180
 181         /* Does hostname needs to be enclosed in brackets? */
 182         if (strchr(hostname, ':'))
 183                 param.size = snprintf(param.string, len, "[%s]:/", hostname);
 184         else
 185                 param.size = snprintf(param.string, len, "%s:/", hostname);
 186         ret = vfs_parse_fs_param(root_fc, &param);
 187         kfree(param.string);
 188         if (ret < 0) {
 189                 put_fs_context(root_fc);
 190                 return ret;
 191         }
 192         root_mnt = fc_mount(root_fc);
 193         put_fs_context(root_fc);
 194
 195         if (IS_ERR(root_mnt))
 196                 return PTR_ERR(root_mnt);
 197
 198         ret = nfs_referral_loop_protect();
 199         if (ret) {
 200                 mntput(root_mnt);
 201                 return ret;
 202         }
 203
 204         dentry = mount_subtree(root_mnt, export_path);
 205         nfs_referral_loop_unprotect();
 206
 207         if (IS_ERR(dentry))
 208                 return PTR_ERR(dentry);
 209
 210         fc->root = dentry;
 211         return 0;
 212 }
 213
 214 int nfs4_try_get_tree(struct fs_context *fc)
 215 {
 216         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 217         int err;
 218
 219         dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
 220
 221         /* We create a mount for the server's root, walk to the requested
 222          * location and then create another mount for that.
 223          */
 224         err= do_nfs4_mount(nfs4_create_server(fc),
 225                            fc, ctx->nfs_server.hostname,
 226                            ctx->nfs_server.export_path);
 227         if (err) {
 228                 nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 229                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
 230         } else {
 231                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
 232         }
 233         return err;
 234 }
 235
 236 /*
 237  * Create an NFS4 server record on referral traversal
 238  */
 239 int nfs4_get_referral_tree(struct fs_context *fc)
 240 {
 241         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 242         int err;
 243
 244         dprintk("--> nfs4_referral_mount()\n");
 245
 246         /* create a new volume representation */
 247         err = do_nfs4_mount(nfs4_create_referral_server(fc),
 248                             fc, ctx->nfs_server.hostname,
 249                             ctx->nfs_server.export_path);
 250         if (err) {
 251                 nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 252                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
 253         } else {
 254                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
 255         }
 256         return err;
 257 }
 258
 259 static int __init init_nfs_v4(void)
 260 {
 261         int err;
 262
 263         err = nfs_dns_resolver_init();
 264         if (err)
 265                 goto out;
 266
 267         err = nfs_idmap_init();
 268         if (err)
 269                 goto out1;
 270
 271         err = nfs4_register_sysctl();
 272         if (err)
 273                 goto out2;
 274
 275         register_nfs_version(&nfs_v4);
 276         return 0;
 277 out2:
 278         nfs_idmap_quit();
 279 out1:
 280         nfs_dns_resolver_destroy();
 281 out:
 282         return err;
 283 }
 284
 285 static void __exit exit_nfs_v4(void)
 286 {
 287         /* Not called in the _init(), conditionally loaded */
 288         nfs4_pnfs_v3_ds_connect_unload();
 289
 290         unregister_nfs_version(&nfs_v4);
 291         nfs4_unregister_sysctl();
 292         nfs_idmap_quit();
 293         nfs_dns_resolver_destroy();
 294 }
 295
 296 MODULE_LICENSE("GPL");
 297
 298 module_init(init_nfs_v4);
 299 module_exit(exit_nfs_v4);