fs/nfs/nfs4super.c

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