fs/nfs/nfs4super.c

   1 /*
   2  * Copyright (c) 2012 Bryan Schumaker <[email protected]>
   3  */
   4 #include <linux/init.h>
   5 #include <linux/module.h>
   6 #include <linux/nfs_idmap.h>
   7 #include <linux/nfs4_mount.h>
   8 #include <linux/nfs_fs.h>
   9 #include "delegation.h"
  10 #include "internal.h"
  11 #include "nfs4_fs.h"
  12 #include "pnfs.h"
  13 #include "nfs.h"
  14
  15 #define NFSDBG_FACILITY         NFSDBG_VFS
  16
  17 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
  18 static void nfs4_evict_inode(struct inode *inode);
  19 static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type,
  20         int flags, const char *dev_name, void *raw_data);
  21 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
  22         int flags, const char *dev_name, void *raw_data);
  23 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
  24         int flags, const char *dev_name, void *raw_data);
  25
  26 static struct file_system_type nfs4_remote_fs_type = {
  27         .owner          = THIS_MODULE,
  28         .name           = "nfs4",
  29         .mount          = nfs4_remote_mount,
  30         .kill_sb        = nfs_kill_super,
  31         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  32 };
  33
  34 static struct file_system_type nfs4_remote_referral_fs_type = {
  35         .owner          = THIS_MODULE,
  36         .name           = "nfs4",
  37         .mount          = nfs4_remote_referral_mount,
  38         .kill_sb        = nfs_kill_super,
  39         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  40 };
  41
  42 struct file_system_type nfs4_referral_fs_type = {
  43         .owner          = THIS_MODULE,
  44         .name           = "nfs4",
  45         .mount          = nfs4_referral_mount,
  46         .kill_sb        = nfs_kill_super,
  47         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  48 };
  49
  50 static const struct super_operations nfs4_sops = {
  51         .alloc_inode    = nfs_alloc_inode,
  52         .destroy_inode  = nfs_destroy_inode,
  53         .write_inode    = nfs4_write_inode,
  54         .put_super      = nfs_put_super,
  55         .statfs         = nfs_statfs,
  56         .evict_inode    = nfs4_evict_inode,
  57         .umount_begin   = nfs_umount_begin,
  58         .show_options   = nfs_show_options,
  59         .show_devname   = nfs_show_devname,
  60         .show_path      = nfs_show_path,
  61         .show_stats     = nfs_show_stats,
  62         .remount_fs     = nfs_remount,
  63 };
  64
  65 struct nfs_subversion nfs_v4 = {
  66         .owner = THIS_MODULE,
  67         .nfs_fs   = &nfs4_fs_type,
  68         .rpc_vers = &nfs_version4,
  69         .rpc_ops  = &nfs_v4_clientops,
  70         .sops     = &nfs4_sops,
  71         .xattr    = nfs4_xattr_handlers,
  72 };
  73
  74 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  75 {
  76         int ret = nfs_write_inode(inode, wbc);
  77
  78         if (ret >= 0 && test_bit(NFS_INO_LAYOUTCOMMIT, &NFS_I(inode)->flags)) {
  79                 int status;
  80                 bool sync = true;
  81
  82                 if (wbc->sync_mode == WB_SYNC_NONE)
  83                         sync = false;
  84
  85                 status = pnfs_layoutcommit_inode(inode, sync);
  86                 if (status < 0)
  87                         return status;
  88         }
  89         return ret;
  90 }
  91
  92 /*
  93  * Clean out any remaining NFSv4 state that might be left over due
  94  * to open() calls that passed nfs_atomic_lookup, but failed to call
  95  * nfs_open().
  96  */
  97 static void nfs4_evict_inode(struct inode *inode)
  98 {
  99         truncate_inode_pages(&inode->i_data, 0);
 100         clear_inode(inode);
 101         pnfs_return_layout(inode);
 102         pnfs_destroy_layout(NFS_I(inode));
 103         /* If we are holding a delegation, return it! */
 104         nfs_inode_return_delegation_noreclaim(inode);
 105         /* First call standard NFS clear_inode() code */
 106         nfs_clear_inode(inode);
 107 }
 108
 109 /*
 110  * Get the superblock for the NFS4 root partition
 111  */
 112 static struct dentry *
 113 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
 114                   const char *dev_name, void *info)
 115 {
 116         struct nfs_mount_info *mount_info = info;
 117         struct nfs_server *server;
 118         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 119
 120         mount_info->set_security = nfs_set_sb_security;
 121
 122         /* Get a volume representation */
 123         server = nfs4_create_server(mount_info, &nfs_v4);
 124         if (IS_ERR(server)) {
 125                 mntroot = ERR_CAST(server);
 126                 goto out;
 127         }
 128
 129         mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, &nfs_v4);
 130
 131 out:
 132         return mntroot;
 133 }
 134
 135 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
 136                 int flags, void *data, const char *hostname)
 137 {
 138         struct vfsmount *root_mnt;
 139         char *root_devname;
 140         size_t len;
 141
 142         len = strlen(hostname) + 5;
 143         root_devname = kmalloc(len, GFP_KERNEL);
 144         if (root_devname == NULL)
 145                 return ERR_PTR(-ENOMEM);
 146         /* Does hostname needs to be enclosed in brackets? */
 147         if (strchr(hostname, ':'))
 148                 snprintf(root_devname, len, "[%s]:/", hostname);
 149         else
 150                 snprintf(root_devname, len, "%s:/", hostname);
 151         root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
 152         kfree(root_devname);
 153         return root_mnt;
 154 }
 155
 156 struct nfs_referral_count {
 157         struct list_head list;
 158         const struct task_struct *task;
 159         unsigned int referral_count;
 160 };
 161
 162 static LIST_HEAD(nfs_referral_count_list);
 163 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 164
 165 static struct nfs_referral_count *nfs_find_referral_count(void)
 166 {
 167         struct nfs_referral_count *p;
 168
 169         list_for_each_entry(p, &nfs_referral_count_list, list) {
 170                 if (p->task == current)
 171                         return p;
 172         }
 173         return NULL;
 174 }
 175
 176 #define NFS_MAX_NESTED_REFERRALS 2
 177
 178 static int nfs_referral_loop_protect(void)
 179 {
 180         struct nfs_referral_count *p, *new;
 181         int ret = -ENOMEM;
 182
 183         new = kmalloc(sizeof(*new), GFP_KERNEL);
 184         if (!new)
 185                 goto out;
 186         new->task = current;
 187         new->referral_count = 1;
 188
 189         ret = 0;
 190         spin_lock(&nfs_referral_count_list_lock);
 191         p = nfs_find_referral_count();
 192         if (p != NULL) {
 193                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 194                         ret = -ELOOP;
 195                 else
 196                         p->referral_count++;
 197         } else {
 198                 list_add(&new->list, &nfs_referral_count_list);
 199                 new = NULL;
 200         }
 201         spin_unlock(&nfs_referral_count_list_lock);
 202         kfree(new);
 203 out:
 204         return ret;
 205 }
 206
 207 static void nfs_referral_loop_unprotect(void)
 208 {
 209         struct nfs_referral_count *p;
 210
 211         spin_lock(&nfs_referral_count_list_lock);
 212         p = nfs_find_referral_count();
 213         p->referral_count--;
 214         if (p->referral_count == 0)
 215                 list_del(&p->list);
 216         else
 217                 p = NULL;
 218         spin_unlock(&nfs_referral_count_list_lock);
 219         kfree(p);
 220 }
 221
 222 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
 223                 const char *export_path)
 224 {
 225         struct dentry *dentry;
 226         int err;
 227
 228         if (IS_ERR(root_mnt))
 229                 return ERR_CAST(root_mnt);
 230
 231         err = nfs_referral_loop_protect();
 232         if (err) {
 233                 mntput(root_mnt);
 234                 return ERR_PTR(err);
 235         }
 236
 237         dentry = mount_subtree(root_mnt, export_path);
 238         nfs_referral_loop_unprotect();
 239
 240         return dentry;
 241 }
 242
 243 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 244                               struct nfs_mount_info *mount_info,
 245                               struct nfs_subversion *nfs_mod)
 246 {
 247         char *export_path;
 248         struct vfsmount *root_mnt;
 249         struct dentry *res;
 250         struct nfs_parsed_mount_data *data = mount_info->parsed;
 251
 252         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 253
 254         export_path = data->nfs_server.export_path;
 255         data->nfs_server.export_path = "/";
 256         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
 257                         data->nfs_server.hostname);
 258         data->nfs_server.export_path = export_path;
 259
 260         res = nfs_follow_remote_path(root_mnt, export_path);
 261
 262         dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n",
 263                         IS_ERR(res) ? PTR_ERR(res) : 0,
 264                         IS_ERR(res) ? " [error]" : "");
 265         return res;
 266 }
 267
 268 static struct dentry *
 269 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
 270                            const char *dev_name, void *raw_data)
 271 {
 272         struct nfs_mount_info mount_info = {
 273                 .fill_super = nfs_fill_super,
 274                 .set_security = nfs_clone_sb_security,
 275                 .cloned = raw_data,
 276         };
 277         struct nfs_server *server;
 278         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 279
 280         dprintk("--> nfs4_referral_get_sb()\n");
 281
 282         mount_info.mntfh = nfs_alloc_fhandle();
 283         if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
 284                 goto out;
 285
 286         /* create a new volume representation */
 287         server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
 288         if (IS_ERR(server)) {
 289                 mntroot = ERR_CAST(server);
 290                 goto out;
 291         }
 292
 293         mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
 294 out:
 295         nfs_free_fhandle(mount_info.mntfh);
 296         return mntroot;
 297 }
 298
 299 /*
 300  * Create an NFS4 server record on referral traversal
 301  */
 302 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 303                 int flags, const char *dev_name, void *raw_data)
 304 {
 305         struct nfs_clone_mount *data = raw_data;
 306         char *export_path;
 307         struct vfsmount *root_mnt;
 308         struct dentry *res;
 309
 310         dprintk("--> nfs4_referral_mount()\n");
 311
 312         export_path = data->mnt_path;
 313         data->mnt_path = "/";
 314
 315         root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
 316                         flags, data, data->hostname);
 317         data->mnt_path = export_path;
 318
 319         res = nfs_follow_remote_path(root_mnt, export_path);
 320         dprintk("<-- nfs4_referral_mount() = %ld%s\n",
 321                         IS_ERR(res) ? PTR_ERR(res) : 0,
 322                         IS_ERR(res) ? " [error]" : "");
 323         return res;
 324 }
 325
 326
 327 static int __init init_nfs_v4(void)
 328 {
 329         int err;
 330
 331         err = nfs_idmap_init();
 332         if (err)
 333                 goto out;
 334
 335         err = nfs4_register_sysctl();
 336         if (err)
 337                 goto out1;
 338
 339         register_nfs_version(&nfs_v4);
 340         return 0;
 341 out1:
 342         nfs_idmap_quit();
 343 out:
 344         return err;
 345 }
 346
 347 static void __exit exit_nfs_v4(void)
 348 {
 349         unregister_nfs_version(&nfs_v4);
 350         nfs4_unregister_sysctl();
 351         nfs_idmap_quit();
 352 }
 353
 354 MODULE_LICENSE("GPL");
 355
 356 module_init(init_nfs_v4);
 357 module_exit(exit_nfs_v4);