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 "internal.h"
  10 #include "nfs4_fs.h"
  11 #include "nfs.h"
  12
  13 #define NFSDBG_FACILITY         NFSDBG_VFS
  14
  15 static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type,
  16         int flags, const char *dev_name, void *raw_data);
  17 static struct dentry *nfs4_xdev_mount(struct file_system_type *fs_type,
  18         int flags, const char *dev_name, void *raw_data);
  19 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
  20         int flags, const char *dev_name, void *raw_data);
  21 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
  22         int flags, const char *dev_name, void *raw_data);
  23
  24 static struct file_system_type nfs4_fs_type = {
  25         .owner          = THIS_MODULE,
  26         .name           = "nfs4",
  27         .mount          = nfs_fs_mount,
  28         .kill_sb        = nfs_kill_super,
  29         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  30 };
  31
  32 static struct file_system_type nfs4_remote_fs_type = {
  33         .owner          = THIS_MODULE,
  34         .name           = "nfs4",
  35         .mount          = nfs4_remote_mount,
  36         .kill_sb        = nfs_kill_super,
  37         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  38 };
  39
  40 struct file_system_type nfs4_xdev_fs_type = {
  41         .owner          = THIS_MODULE,
  42         .name           = "nfs4",
  43         .mount          = nfs4_xdev_mount,
  44         .kill_sb        = nfs_kill_super,
  45         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  46 };
  47
  48 static struct file_system_type nfs4_remote_referral_fs_type = {
  49         .owner          = THIS_MODULE,
  50         .name           = "nfs4",
  51         .mount          = nfs4_remote_referral_mount,
  52         .kill_sb        = nfs_kill_super,
  53         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  54 };
  55
  56 struct file_system_type nfs4_referral_fs_type = {
  57         .owner          = THIS_MODULE,
  58         .name           = "nfs4",
  59         .mount          = nfs4_referral_mount,
  60         .kill_sb        = nfs_kill_super,
  61         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  62 };
  63
  64 static const struct super_operations nfs4_sops = {
  65         .alloc_inode    = nfs_alloc_inode,
  66         .destroy_inode  = nfs_destroy_inode,
  67         .write_inode    = nfs4_write_inode,
  68         .put_super      = nfs_put_super,
  69         .statfs         = nfs_statfs,
  70         .evict_inode    = nfs4_evict_inode,
  71         .umount_begin   = nfs_umount_begin,
  72         .show_options   = nfs_show_options,
  73         .show_devname   = nfs_show_devname,
  74         .show_path      = nfs_show_path,
  75         .show_stats     = nfs_show_stats,
  76         .remount_fs     = nfs_remount,
  77 };
  78
  79 struct nfs_subversion nfs_v4 = {
  80         .owner = THIS_MODULE,
  81         .nfs_fs   = &nfs4_fs_type,
  82         .rpc_vers = &nfs_version4,
  83         .rpc_ops  = &nfs_v4_clientops,
  84 };
  85
  86 /*
  87  * Set up an NFS4 superblock
  88  */
  89 static void nfs4_fill_super(struct super_block *sb,
  90                             struct nfs_mount_info *mount_info)
  91 {
  92         sb->s_time_gran = 1;
  93         sb->s_op = &nfs4_sops;
  94         /*
  95          * The VFS shouldn't apply the umask to mode bits. We will do
  96          * so ourselves when necessary.
  97          */
  98         sb->s_flags  |= MS_POSIXACL;
  99         sb->s_xattr = nfs4_xattr_handlers;
 100         nfs_initialise_sb(sb);
 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->fill_super = nfs4_fill_super;
 115         mount_info->set_security = nfs_set_sb_security;
 116
 117         /* Get a volume representation */
 118         server = nfs4_create_server(mount_info->parsed, mount_info->mntfh);
 119         if (IS_ERR(server)) {
 120                 mntroot = ERR_CAST(server);
 121                 goto out;
 122         }
 123
 124         mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, &nfs_v4);
 125
 126 out:
 127         return mntroot;
 128 }
 129
 130 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
 131                 int flags, void *data, const char *hostname)
 132 {
 133         struct vfsmount *root_mnt;
 134         char *root_devname;
 135         size_t len;
 136
 137         len = strlen(hostname) + 5;
 138         root_devname = kmalloc(len, GFP_KERNEL);
 139         if (root_devname == NULL)
 140                 return ERR_PTR(-ENOMEM);
 141         /* Does hostname needs to be enclosed in brackets? */
 142         if (strchr(hostname, ':'))
 143                 snprintf(root_devname, len, "[%s]:/", hostname);
 144         else
 145                 snprintf(root_devname, len, "%s:/", hostname);
 146         root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
 147         kfree(root_devname);
 148         return root_mnt;
 149 }
 150
 151 struct nfs_referral_count {
 152         struct list_head list;
 153         const struct task_struct *task;
 154         unsigned int referral_count;
 155 };
 156
 157 static LIST_HEAD(nfs_referral_count_list);
 158 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 159
 160 static struct nfs_referral_count *nfs_find_referral_count(void)
 161 {
 162         struct nfs_referral_count *p;
 163
 164         list_for_each_entry(p, &nfs_referral_count_list, list) {
 165                 if (p->task == current)
 166                         return p;
 167         }
 168         return NULL;
 169 }
 170
 171 #define NFS_MAX_NESTED_REFERRALS 2
 172
 173 static int nfs_referral_loop_protect(void)
 174 {
 175         struct nfs_referral_count *p, *new;
 176         int ret = -ENOMEM;
 177
 178         new = kmalloc(sizeof(*new), GFP_KERNEL);
 179         if (!new)
 180                 goto out;
 181         new->task = current;
 182         new->referral_count = 1;
 183
 184         ret = 0;
 185         spin_lock(&nfs_referral_count_list_lock);
 186         p = nfs_find_referral_count();
 187         if (p != NULL) {
 188                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 189                         ret = -ELOOP;
 190                 else
 191                         p->referral_count++;
 192         } else {
 193                 list_add(&new->list, &nfs_referral_count_list);
 194                 new = NULL;
 195         }
 196         spin_unlock(&nfs_referral_count_list_lock);
 197         kfree(new);
 198 out:
 199         return ret;
 200 }
 201
 202 static void nfs_referral_loop_unprotect(void)
 203 {
 204         struct nfs_referral_count *p;
 205
 206         spin_lock(&nfs_referral_count_list_lock);
 207         p = nfs_find_referral_count();
 208         p->referral_count--;
 209         if (p->referral_count == 0)
 210                 list_del(&p->list);
 211         else
 212                 p = NULL;
 213         spin_unlock(&nfs_referral_count_list_lock);
 214         kfree(p);
 215 }
 216
 217 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
 218                 const char *export_path)
 219 {
 220         struct dentry *dentry;
 221         int err;
 222
 223         if (IS_ERR(root_mnt))
 224                 return ERR_CAST(root_mnt);
 225
 226         err = nfs_referral_loop_protect();
 227         if (err) {
 228                 mntput(root_mnt);
 229                 return ERR_PTR(err);
 230         }
 231
 232         dentry = mount_subtree(root_mnt, export_path);
 233         nfs_referral_loop_unprotect();
 234
 235         return dentry;
 236 }
 237
 238 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 239                          struct nfs_mount_info *mount_info)
 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         mount_info->fill_super = nfs4_fill_super;
 249
 250         export_path = data->nfs_server.export_path;
 251         data->nfs_server.export_path = "/";
 252         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
 253                         data->nfs_server.hostname);
 254         data->nfs_server.export_path = export_path;
 255
 256         res = nfs_follow_remote_path(root_mnt, export_path);
 257
 258         dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n",
 259                         IS_ERR(res) ? PTR_ERR(res) : 0,
 260                         IS_ERR(res) ? " [error]" : "");
 261         return res;
 262 }
 263
 264 /*
 265  * Clone an NFS4 server record on xdev traversal (FSID-change)
 266  */
 267 static struct dentry *
 268 nfs4_xdev_mount(struct file_system_type *fs_type, int flags,
 269                  const char *dev_name, void *raw_data)
 270 {
 271         struct nfs_mount_info mount_info = {
 272                 .fill_super = nfs_clone_super,
 273                 .set_security = nfs_clone_sb_security,
 274                 .cloned = raw_data,
 275         };
 276         return nfs_xdev_mount_common(&nfs4_fs_type, flags, dev_name, &mount_info);
 277 }
 278
 279 static struct dentry *
 280 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
 281                            const char *dev_name, void *raw_data)
 282 {
 283         struct nfs_mount_info mount_info = {
 284                 .fill_super = nfs4_fill_super,
 285                 .set_security = nfs_clone_sb_security,
 286                 .cloned = raw_data,
 287         };
 288         struct nfs_server *server;
 289         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 290
 291         dprintk("--> nfs4_referral_get_sb()\n");
 292
 293         mount_info.mntfh = nfs_alloc_fhandle();
 294         if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
 295                 goto out;
 296
 297         /* create a new volume representation */
 298         server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
 299         if (IS_ERR(server)) {
 300                 mntroot = ERR_CAST(server);
 301                 goto out;
 302         }
 303
 304         mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
 305 out:
 306         nfs_free_fhandle(mount_info.mntfh);
 307         return mntroot;
 308 }
 309
 310 /*
 311  * Create an NFS4 server record on referral traversal
 312  */
 313 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 314                 int flags, const char *dev_name, void *raw_data)
 315 {
 316         struct nfs_clone_mount *data = raw_data;
 317         char *export_path;
 318         struct vfsmount *root_mnt;
 319         struct dentry *res;
 320
 321         dprintk("--> nfs4_referral_mount()\n");
 322
 323         export_path = data->mnt_path;
 324         data->mnt_path = "/";
 325
 326         root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
 327                         flags, data, data->hostname);
 328         data->mnt_path = export_path;
 329
 330         res = nfs_follow_remote_path(root_mnt, export_path);
 331         dprintk("<-- nfs4_referral_mount() = %ld%s\n",
 332                         IS_ERR(res) ? PTR_ERR(res) : 0,
 333                         IS_ERR(res) ? " [error]" : "");
 334         return res;
 335 }
 336
 337
 338 int __init init_nfs_v4(void)
 339 {
 340         int err;
 341
 342         err = nfs_idmap_init();
 343         if (err)
 344                 goto out;
 345
 346         err = nfs4_register_sysctl();
 347         if (err)
 348                 goto out1;
 349
 350         err = register_filesystem(&nfs4_fs_type);
 351         if (err < 0)
 352                 goto out2;
 353
 354         register_nfs_version(&nfs_v4);
 355         return 0;
 356 out2:
 357         nfs4_unregister_sysctl();
 358 out1:
 359         nfs_idmap_quit();
 360 out:
 361         return err;
 362 }
 363
 364 void exit_nfs_v4(void)
 365 {
 366         unregister_nfs_version(&nfs_v4);
 367         unregister_filesystem(&nfs4_fs_type);
 368         nfs4_unregister_sysctl();
 369         nfs_idmap_quit();
 370 }