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 "dns_resolve.h"
  13 #include "pnfs.h"
  14 #include "nfs.h"
  15
  16 #define NFSDBG_FACILITY         NFSDBG_VFS
  17
  18 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
  19 static void nfs4_evict_inode(struct inode *inode);
  20 static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type,
  21         int flags, const char *dev_name, void *raw_data);
  22 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
  23         int flags, const char *dev_name, void *raw_data);
  24 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
  25         int flags, const char *dev_name, void *raw_data);
  26
  27 static struct file_system_type nfs4_remote_fs_type = {
  28         .owner          = THIS_MODULE,
  29         .name           = "nfs4",
  30         .mount          = nfs4_remote_mount,
  31         .kill_sb        = nfs_kill_super,
  32         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  33 };
  34
  35 static struct file_system_type nfs4_remote_referral_fs_type = {
  36         .owner          = THIS_MODULE,
  37         .name           = "nfs4",
  38         .mount          = nfs4_remote_referral_mount,
  39         .kill_sb        = nfs_kill_super,
  40         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  41 };
  42
  43 struct file_system_type nfs4_referral_fs_type = {
  44         .owner          = THIS_MODULE,
  45         .name           = "nfs4",
  46         .mount          = nfs4_referral_mount,
  47         .kill_sb        = nfs_kill_super,
  48         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  49 };
  50
  51 static const struct super_operations nfs4_sops = {
  52         .alloc_inode    = nfs_alloc_inode,
  53         .destroy_inode  = nfs_destroy_inode,
  54         .write_inode    = nfs4_write_inode,
  55         .drop_inode     = nfs_drop_inode,
  56         .put_super      = nfs_put_super,
  57         .statfs         = nfs_statfs,
  58         .evict_inode    = nfs4_evict_inode,
  59         .umount_begin   = nfs_umount_begin,
  60         .show_options   = nfs_show_options,
  61         .show_devname   = nfs_show_devname,
  62         .show_path      = nfs_show_path,
  63         .show_stats     = nfs_show_stats,
  64         .remount_fs     = nfs_remount,
  65 };
  66
  67 struct nfs_subversion nfs_v4 = {
  68         .owner = THIS_MODULE,
  69         .nfs_fs   = &nfs4_fs_type,
  70         .rpc_vers = &nfs_version4,
  71         .rpc_ops  = &nfs_v4_clientops,
  72         .sops     = &nfs4_sops,
  73         .xattr    = nfs4_xattr_handlers,
  74 };
  75
  76 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  77 {
  78         int ret = nfs_write_inode(inode, wbc);
  79
  80         if (ret >= 0 && test_bit(NFS_INO_LAYOUTCOMMIT, &NFS_I(inode)->flags)) {
  81                 int status;
  82                 bool sync = true;
  83
  84                 if (wbc->sync_mode == WB_SYNC_NONE)
  85                         sync = false;
  86
  87                 status = pnfs_layoutcommit_inode(inode, sync);
  88                 if (status < 0)
  89                         return status;
  90         }
  91         return ret;
  92 }
  93
  94 /*
  95  * Clean out any remaining NFSv4 state that might be left over due
  96  * to open() calls that passed nfs_atomic_lookup, but failed to call
  97  * nfs_open().
  98  */
  99 static void nfs4_evict_inode(struct inode *inode)
 100 {
 101         truncate_inode_pages(&inode->i_data, 0);
 102         clear_inode(inode);
 103         pnfs_return_layout(inode);
 104         pnfs_destroy_layout(NFS_I(inode));
 105         /* If we are holding a delegation, return it! */
 106         nfs_inode_return_delegation_noreclaim(inode);
 107         /* First call standard NFS clear_inode() code */
 108         nfs_clear_inode(inode);
 109 }
 110
 111 /*
 112  * Get the superblock for the NFS4 root partition
 113  */
 114 static struct dentry *
 115 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
 116                   const char *dev_name, void *info)
 117 {
 118         struct nfs_mount_info *mount_info = info;
 119         struct nfs_server *server;
 120         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 121
 122         mount_info->set_security = nfs_set_sb_security;
 123
 124         /* Get a volume representation */
 125         server = nfs4_create_server(mount_info, &nfs_v4);
 126         if (IS_ERR(server)) {
 127                 mntroot = ERR_CAST(server);
 128                 goto out;
 129         }
 130
 131         mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, &nfs_v4);
 132
 133 out:
 134         return mntroot;
 135 }
 136
 137 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
 138                 int flags, void *data, const char *hostname)
 139 {
 140         struct vfsmount *root_mnt;
 141         char *root_devname;
 142         size_t len;
 143
 144         len = strlen(hostname) + 5;
 145         root_devname = kmalloc(len, GFP_KERNEL);
 146         if (root_devname == NULL)
 147                 return ERR_PTR(-ENOMEM);
 148         /* Does hostname needs to be enclosed in brackets? */
 149         if (strchr(hostname, ':'))
 150                 snprintf(root_devname, len, "[%s]:/", hostname);
 151         else
 152                 snprintf(root_devname, len, "%s:/", hostname);
 153         root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
 154         kfree(root_devname);
 155         return root_mnt;
 156 }
 157
 158 struct nfs_referral_count {
 159         struct list_head list;
 160         const struct task_struct *task;
 161         unsigned int referral_count;
 162 };
 163
 164 static LIST_HEAD(nfs_referral_count_list);
 165 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 166
 167 static struct nfs_referral_count *nfs_find_referral_count(void)
 168 {
 169         struct nfs_referral_count *p;
 170
 171         list_for_each_entry(p, &nfs_referral_count_list, list) {
 172                 if (p->task == current)
 173                         return p;
 174         }
 175         return NULL;
 176 }
 177
 178 #define NFS_MAX_NESTED_REFERRALS 2
 179
 180 static int nfs_referral_loop_protect(void)
 181 {
 182         struct nfs_referral_count *p, *new;
 183         int ret = -ENOMEM;
 184
 185         new = kmalloc(sizeof(*new), GFP_KERNEL);
 186         if (!new)
 187                 goto out;
 188         new->task = current;
 189         new->referral_count = 1;
 190
 191         ret = 0;
 192         spin_lock(&nfs_referral_count_list_lock);
 193         p = nfs_find_referral_count();
 194         if (p != NULL) {
 195                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 196                         ret = -ELOOP;
 197                 else
 198                         p->referral_count++;
 199         } else {
 200                 list_add(&new->list, &nfs_referral_count_list);
 201                 new = NULL;
 202         }
 203         spin_unlock(&nfs_referral_count_list_lock);
 204         kfree(new);
 205 out:
 206         return ret;
 207 }
 208
 209 static void nfs_referral_loop_unprotect(void)
 210 {
 211         struct nfs_referral_count *p;
 212
 213         spin_lock(&nfs_referral_count_list_lock);
 214         p = nfs_find_referral_count();
 215         p->referral_count--;
 216         if (p->referral_count == 0)
 217                 list_del(&p->list);
 218         else
 219                 p = NULL;
 220         spin_unlock(&nfs_referral_count_list_lock);
 221         kfree(p);
 222 }
 223
 224 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
 225                 const char *export_path)
 226 {
 227         struct dentry *dentry;
 228         int err;
 229
 230         if (IS_ERR(root_mnt))
 231                 return ERR_CAST(root_mnt);
 232
 233         err = nfs_referral_loop_protect();
 234         if (err) {
 235                 mntput(root_mnt);
 236                 return ERR_PTR(err);
 237         }
 238
 239         dentry = mount_subtree(root_mnt, export_path);
 240         nfs_referral_loop_unprotect();
 241
 242         return dentry;
 243 }
 244
 245 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 246                               struct nfs_mount_info *mount_info,
 247                               struct nfs_subversion *nfs_mod)
 248 {
 249         char *export_path;
 250         struct vfsmount *root_mnt;
 251         struct dentry *res;
 252         struct nfs_parsed_mount_data *data = mount_info->parsed;
 253
 254         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 255
 256         export_path = data->nfs_server.export_path;
 257         data->nfs_server.export_path = "/";
 258         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
 259                         data->nfs_server.hostname);
 260         data->nfs_server.export_path = export_path;
 261
 262         res = nfs_follow_remote_path(root_mnt, export_path);
 263
 264         dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n",
 265                         IS_ERR(res) ? PTR_ERR(res) : 0,
 266                         IS_ERR(res) ? " [error]" : "");
 267         return res;
 268 }
 269
 270 static struct dentry *
 271 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
 272                            const char *dev_name, void *raw_data)
 273 {
 274         struct nfs_mount_info mount_info = {
 275                 .fill_super = nfs_fill_super,
 276                 .set_security = nfs_clone_sb_security,
 277                 .cloned = raw_data,
 278         };
 279         struct nfs_server *server;
 280         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 281
 282         dprintk("--> nfs4_referral_get_sb()\n");
 283
 284         mount_info.mntfh = nfs_alloc_fhandle();
 285         if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
 286                 goto out;
 287
 288         /* create a new volume representation */
 289         server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
 290         if (IS_ERR(server)) {
 291                 mntroot = ERR_CAST(server);
 292                 goto out;
 293         }
 294
 295         mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
 296 out:
 297         nfs_free_fhandle(mount_info.mntfh);
 298         return mntroot;
 299 }
 300
 301 /*
 302  * Create an NFS4 server record on referral traversal
 303  */
 304 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 305                 int flags, const char *dev_name, void *raw_data)
 306 {
 307         struct nfs_clone_mount *data = raw_data;
 308         char *export_path;
 309         struct vfsmount *root_mnt;
 310         struct dentry *res;
 311
 312         dprintk("--> nfs4_referral_mount()\n");
 313
 314         export_path = data->mnt_path;
 315         data->mnt_path = "/";
 316
 317         root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
 318                         flags, data, data->hostname);
 319         data->mnt_path = export_path;
 320
 321         res = nfs_follow_remote_path(root_mnt, export_path);
 322         dprintk("<-- nfs4_referral_mount() = %ld%s\n",
 323                         IS_ERR(res) ? PTR_ERR(res) : 0,
 324                         IS_ERR(res) ? " [error]" : "");
 325         return res;
 326 }
 327
 328
 329 static int __init init_nfs_v4(void)
 330 {
 331         int err;
 332
 333         err = nfs_dns_resolver_init();
 334         if (err)
 335                 goto out;
 336
 337         err = nfs_idmap_init();
 338         if (err)
 339                 goto out1;
 340
 341         err = nfs4_register_sysctl();
 342         if (err)
 343                 goto out2;
 344
 345         register_nfs_version(&nfs_v4);
 346         return 0;
 347 out2:
 348         nfs_idmap_quit();
 349 out1:
 350         nfs_dns_resolver_destroy();
 351 out:
 352         return err;
 353 }
 354
 355 static void __exit exit_nfs_v4(void)
 356 {
 357         unregister_nfs_version(&nfs_v4);
 358         nfs4_unregister_sysctl();
 359         nfs_idmap_quit();
 360         nfs_dns_resolver_destroy();
 361 }
 362
 363 MODULE_LICENSE("GPL");
 364
 365 module_init(init_nfs_v4);
 366 module_exit(exit_nfs_v4);