kernel/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/nfs4_mount.h>
   7 #include <linux/nfs_fs.h>
   8 #include "delegation.h"
   9 #include "internal.h"
  10 #include "nfs4_fs.h"
  11 #include "nfs4idmap.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         .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)
  80                 ret = pnfs_layoutcommit_inode(inode,
  81                                 wbc->sync_mode == WB_SYNC_ALL);
  82         return ret;
  83 }
  84
  85 /*
  86  * Clean out any remaining NFSv4 state that might be left over due
  87  * to open() calls that passed nfs_atomic_lookup, but failed to call
  88  * nfs_open().
  89  */
  90 static void nfs4_evict_inode(struct inode *inode)
  91 {
  92         truncate_inode_pages_final(&inode->i_data);
  93         clear_inode(inode);
  94         /* If we are holding a delegation, return it! */
  95         nfs_inode_return_delegation_noreclaim(inode);
  96         /* Note that above delegreturn would trigger pnfs return-on-close */
  97         pnfs_return_layout(inode);
  98         pnfs_destroy_layout(NFS_I(inode));
  99         /* First call standard NFS clear_inode() code */
 100         nfs_clear_inode(inode);
 101 }
 102
 103 /*
 104  * Get the superblock for the NFS4 root partition
 105  */
 106 static struct dentry *
 107 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
 108                   const char *dev_name, void *info)
 109 {
 110         struct nfs_mount_info *mount_info = info;
 111         struct nfs_server *server;
 112         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 113
 114         mount_info->set_security = nfs_set_sb_security;
 115
 116         /* Get a volume representation */
 117         server = nfs4_create_server(mount_info, &nfs_v4);
 118         if (IS_ERR(server)) {
 119                 mntroot = ERR_CAST(server);
 120                 goto out;
 121         }
 122
 123         mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, &nfs_v4);
 124
 125 out:
 126         return mntroot;
 127 }
 128
 129 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
 130                 int flags, void *data, const char *hostname)
 131 {
 132         struct vfsmount *root_mnt;
 133         char *root_devname;
 134         size_t len;
 135
 136         len = strlen(hostname) + 5;
 137         root_devname = kmalloc(len, GFP_KERNEL);
 138         if (root_devname == NULL)
 139                 return ERR_PTR(-ENOMEM);
 140         /* Does hostname needs to be enclosed in brackets? */
 141         if (strchr(hostname, ':'))
 142                 snprintf(root_devname, len, "[%s]:/", hostname);
 143         else
 144                 snprintf(root_devname, len, "%s:/", hostname);
 145         root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
 146         kfree(root_devname);
 147         return root_mnt;
 148 }
 149
 150 struct nfs_referral_count {
 151         struct list_head list;
 152         const struct task_struct *task;
 153         unsigned int referral_count;
 154 };
 155
 156 static LIST_HEAD(nfs_referral_count_list);
 157 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 158
 159 static struct nfs_referral_count *nfs_find_referral_count(void)
 160 {
 161         struct nfs_referral_count *p;
 162
 163         list_for_each_entry(p, &nfs_referral_count_list, list) {
 164                 if (p->task == current)
 165                         return p;
 166         }
 167         return NULL;
 168 }
 169
 170 #define NFS_MAX_NESTED_REFERRALS 2
 171
 172 static int nfs_referral_loop_protect(void)
 173 {
 174         struct nfs_referral_count *p, *new;
 175         int ret = -ENOMEM;
 176
 177         new = kmalloc(sizeof(*new), GFP_KERNEL);
 178         if (!new)
 179                 goto out;
 180         new->task = current;
 181         new->referral_count = 1;
 182
 183         ret = 0;
 184         spin_lock(&nfs_referral_count_list_lock);
 185         p = nfs_find_referral_count();
 186         if (p != NULL) {
 187                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 188                         ret = -ELOOP;
 189                 else
 190                         p->referral_count++;
 191         } else {
 192                 list_add(&new->list, &nfs_referral_count_list);
 193                 new = NULL;
 194         }
 195         spin_unlock(&nfs_referral_count_list_lock);
 196         kfree(new);
 197 out:
 198         return ret;
 199 }
 200
 201 static void nfs_referral_loop_unprotect(void)
 202 {
 203         struct nfs_referral_count *p;
 204
 205         spin_lock(&nfs_referral_count_list_lock);
 206         p = nfs_find_referral_count();
 207         p->referral_count--;
 208         if (p->referral_count == 0)
 209                 list_del(&p->list);
 210         else
 211                 p = NULL;
 212         spin_unlock(&nfs_referral_count_list_lock);
 213         kfree(p);
 214 }
 215
 216 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
 217                 const char *export_path)
 218 {
 219         struct dentry *dentry;
 220         int err;
 221
 222         if (IS_ERR(root_mnt))
 223                 return ERR_CAST(root_mnt);
 224
 225         err = nfs_referral_loop_protect();
 226         if (err) {
 227                 mntput(root_mnt);
 228                 return ERR_PTR(err);
 229         }
 230
 231         dentry = mount_subtree(root_mnt, export_path);
 232         nfs_referral_loop_unprotect();
 233
 234         return dentry;
 235 }
 236
 237 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 238                               struct nfs_mount_info *mount_info,
 239                               struct nfs_subversion *nfs_mod)
 240 {
 241         char *export_path;
 242         struct vfsmount *root_mnt;
 243         struct dentry *res;
 244         struct nfs_parsed_mount_data *data = mount_info->parsed;
 245
 246         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 247
 248         export_path = data->nfs_server.export_path;
 249         data->nfs_server.export_path = "/";
 250         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
 251                         data->nfs_server.hostname);
 252         data->nfs_server.export_path = export_path;
 253
 254         res = nfs_follow_remote_path(root_mnt, export_path);
 255
 256         dfprintk(MOUNT, "<-- nfs4_try_mount() = %d%s\n",
 257                  PTR_ERR_OR_ZERO(res),
 258                  IS_ERR(res) ? " [error]" : "");
 259         return res;
 260 }
 261
 262 static struct dentry *
 263 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
 264                            const char *dev_name, void *raw_data)
 265 {
 266         struct nfs_mount_info mount_info = {
 267                 .fill_super = nfs_fill_super,
 268                 .set_security = nfs_clone_sb_security,
 269                 .cloned = raw_data,
 270         };
 271         struct nfs_server *server;
 272         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 273
 274         dprintk("--> nfs4_referral_get_sb()\n");
 275
 276         mount_info.mntfh = nfs_alloc_fhandle();
 277         if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
 278                 goto out;
 279
 280         /* create a new volume representation */
 281         server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
 282         if (IS_ERR(server)) {
 283                 mntroot = ERR_CAST(server);
 284                 goto out;
 285         }
 286
 287         mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
 288 out:
 289         nfs_free_fhandle(mount_info.mntfh);
 290         return mntroot;
 291 }
 292
 293 /*
 294  * Create an NFS4 server record on referral traversal
 295  */
 296 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 297                 int flags, const char *dev_name, void *raw_data)
 298 {
 299         struct nfs_clone_mount *data = raw_data;
 300         char *export_path;
 301         struct vfsmount *root_mnt;
 302         struct dentry *res;
 303
 304         dprintk("--> nfs4_referral_mount()\n");
 305
 306         export_path = data->mnt_path;
 307         data->mnt_path = "/";
 308
 309         root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
 310                         flags, data, data->hostname);
 311         data->mnt_path = export_path;
 312
 313         res = nfs_follow_remote_path(root_mnt, export_path);
 314         dprintk("<-- nfs4_referral_mount() = %d%s\n",
 315                 PTR_ERR_OR_ZERO(res),
 316                 IS_ERR(res) ? " [error]" : "");
 317         return res;
 318 }
 319
 320
 321 static int __init init_nfs_v4(void)
 322 {
 323         int err;
 324
 325         err = nfs_dns_resolver_init();
 326         if (err)
 327                 goto out;
 328
 329         err = nfs_idmap_init();
 330         if (err)
 331                 goto out1;
 332
 333         err = nfs4_register_sysctl();
 334         if (err)
 335                 goto out2;
 336
 337         register_nfs_version(&nfs_v4);
 338         return 0;
 339 out2:
 340         nfs_idmap_quit();
 341 out1:
 342         nfs_dns_resolver_destroy();
 343 out:
 344         return err;
 345 }
 346
 347 static void __exit exit_nfs_v4(void)
 348 {
 349         /* Not called in the _init(), conditionally loaded */
 350         nfs4_pnfs_v3_ds_connect_unload();
 351
 352         unregister_nfs_version(&nfs_v4);
 353         nfs4_unregister_sysctl();
 354         nfs_idmap_quit();
 355         nfs_dns_resolver_destroy();
 356 }
 357
 358 MODULE_LICENSE("GPL");
 359
 360 module_init(init_nfs_v4);
 361 module_exit(exit_nfs_v4);