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