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_referral_mount(struct file_system_type *fs_type,
  18         int flags, const char *dev_name, void *raw_data);
  19 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
  20         int flags, const char *dev_name, void *raw_data);
  21
  22 static struct file_system_type nfs4_fs_type = {
  23         .owner          = THIS_MODULE,
  24         .name           = "nfs4",
  25         .mount          = nfs_fs_mount,
  26         .kill_sb        = nfs_kill_super,
  27         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  28 };
  29
  30 static struct file_system_type nfs4_remote_fs_type = {
  31         .owner          = THIS_MODULE,
  32         .name           = "nfs4",
  33         .mount          = nfs4_remote_mount,
  34         .kill_sb        = nfs_kill_super,
  35         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  36 };
  37
  38 static struct file_system_type nfs4_remote_referral_fs_type = {
  39         .owner          = THIS_MODULE,
  40         .name           = "nfs4",
  41         .mount          = nfs4_remote_referral_mount,
  42         .kill_sb        = nfs_kill_super,
  43         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  44 };
  45
  46 struct file_system_type nfs4_referral_fs_type = {
  47         .owner          = THIS_MODULE,
  48         .name           = "nfs4",
  49         .mount          = nfs4_referral_mount,
  50         .kill_sb        = nfs_kill_super,
  51         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
  52 };
  53
  54 static const struct super_operations nfs4_sops = {
  55         .alloc_inode    = nfs_alloc_inode,
  56         .destroy_inode  = nfs_destroy_inode,
  57         .write_inode    = nfs4_write_inode,
  58         .put_super      = nfs_put_super,
  59         .statfs         = nfs_statfs,
  60         .evict_inode    = nfs4_evict_inode,
  61         .umount_begin   = nfs_umount_begin,
  62         .show_options   = nfs_show_options,
  63         .show_devname   = nfs_show_devname,
  64         .show_path      = nfs_show_path,
  65         .show_stats     = nfs_show_stats,
  66         .remount_fs     = nfs_remount,
  67 };
  68
  69 struct nfs_subversion nfs_v4 = {
  70         .owner = THIS_MODULE,
  71         .nfs_fs   = &nfs4_fs_type,
  72         .rpc_vers = &nfs_version4,
  73         .rpc_ops  = &nfs_v4_clientops,
  74 };
  75
  76 /*
  77  * Set up an NFS4 superblock
  78  */
  79 static void nfs4_fill_super(struct super_block *sb,
  80                             struct nfs_mount_info *mount_info)
  81 {
  82         sb->s_time_gran = 1;
  83         sb->s_op = &nfs4_sops;
  84         /*
  85          * The VFS shouldn't apply the umask to mode bits. We will do
  86          * so ourselves when necessary.
  87          */
  88         sb->s_flags  |= MS_POSIXACL;
  89         sb->s_xattr = nfs4_xattr_handlers;
  90         nfs_initialise_sb(sb);
  91 }
  92
  93 /*
  94  * Get the superblock for the NFS4 root partition
  95  */
  96 static struct dentry *
  97 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
  98                   const char *dev_name, void *info)
  99 {
 100         struct nfs_mount_info *mount_info = info;
 101         struct nfs_server *server;
 102         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 103
 104         mount_info->fill_super = nfs4_fill_super;
 105         mount_info->set_security = nfs_set_sb_security;
 106
 107         /* Get a volume representation */
 108         server = nfs4_create_server(mount_info, &nfs_v4);
 109         if (IS_ERR(server)) {
 110                 mntroot = ERR_CAST(server);
 111                 goto out;
 112         }
 113
 114         mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, &nfs_v4);
 115
 116 out:
 117         return mntroot;
 118 }
 119
 120 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
 121                 int flags, void *data, const char *hostname)
 122 {
 123         struct vfsmount *root_mnt;
 124         char *root_devname;
 125         size_t len;
 126
 127         len = strlen(hostname) + 5;
 128         root_devname = kmalloc(len, GFP_KERNEL);
 129         if (root_devname == NULL)
 130                 return ERR_PTR(-ENOMEM);
 131         /* Does hostname needs to be enclosed in brackets? */
 132         if (strchr(hostname, ':'))
 133                 snprintf(root_devname, len, "[%s]:/", hostname);
 134         else
 135                 snprintf(root_devname, len, "%s:/", hostname);
 136         root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
 137         kfree(root_devname);
 138         return root_mnt;
 139 }
 140
 141 struct nfs_referral_count {
 142         struct list_head list;
 143         const struct task_struct *task;
 144         unsigned int referral_count;
 145 };
 146
 147 static LIST_HEAD(nfs_referral_count_list);
 148 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 149
 150 static struct nfs_referral_count *nfs_find_referral_count(void)
 151 {
 152         struct nfs_referral_count *p;
 153
 154         list_for_each_entry(p, &nfs_referral_count_list, list) {
 155                 if (p->task == current)
 156                         return p;
 157         }
 158         return NULL;
 159 }
 160
 161 #define NFS_MAX_NESTED_REFERRALS 2
 162
 163 static int nfs_referral_loop_protect(void)
 164 {
 165         struct nfs_referral_count *p, *new;
 166         int ret = -ENOMEM;
 167
 168         new = kmalloc(sizeof(*new), GFP_KERNEL);
 169         if (!new)
 170                 goto out;
 171         new->task = current;
 172         new->referral_count = 1;
 173
 174         ret = 0;
 175         spin_lock(&nfs_referral_count_list_lock);
 176         p = nfs_find_referral_count();
 177         if (p != NULL) {
 178                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 179                         ret = -ELOOP;
 180                 else
 181                         p->referral_count++;
 182         } else {
 183                 list_add(&new->list, &nfs_referral_count_list);
 184                 new = NULL;
 185         }
 186         spin_unlock(&nfs_referral_count_list_lock);
 187         kfree(new);
 188 out:
 189         return ret;
 190 }
 191
 192 static void nfs_referral_loop_unprotect(void)
 193 {
 194         struct nfs_referral_count *p;
 195
 196         spin_lock(&nfs_referral_count_list_lock);
 197         p = nfs_find_referral_count();
 198         p->referral_count--;
 199         if (p->referral_count == 0)
 200                 list_del(&p->list);
 201         else
 202                 p = NULL;
 203         spin_unlock(&nfs_referral_count_list_lock);
 204         kfree(p);
 205 }
 206
 207 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
 208                 const char *export_path)
 209 {
 210         struct dentry *dentry;
 211         int err;
 212
 213         if (IS_ERR(root_mnt))
 214                 return ERR_CAST(root_mnt);
 215
 216         err = nfs_referral_loop_protect();
 217         if (err) {
 218                 mntput(root_mnt);
 219                 return ERR_PTR(err);
 220         }
 221
 222         dentry = mount_subtree(root_mnt, export_path);
 223         nfs_referral_loop_unprotect();
 224
 225         return dentry;
 226 }
 227
 228 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 229                               struct nfs_mount_info *mount_info,
 230                               struct nfs_subversion *nfs_mod)
 231 {
 232         char *export_path;
 233         struct vfsmount *root_mnt;
 234         struct dentry *res;
 235         struct nfs_parsed_mount_data *data = mount_info->parsed;
 236
 237         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 238
 239         mount_info->fill_super = nfs4_fill_super;
 240
 241         export_path = data->nfs_server.export_path;
 242         data->nfs_server.export_path = "/";
 243         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
 244                         data->nfs_server.hostname);
 245         data->nfs_server.export_path = export_path;
 246
 247         res = nfs_follow_remote_path(root_mnt, export_path);
 248
 249         dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n",
 250                         IS_ERR(res) ? PTR_ERR(res) : 0,
 251                         IS_ERR(res) ? " [error]" : "");
 252         return res;
 253 }
 254
 255 static struct dentry *
 256 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
 257                            const char *dev_name, void *raw_data)
 258 {
 259         struct nfs_mount_info mount_info = {
 260                 .fill_super = nfs4_fill_super,
 261                 .set_security = nfs_clone_sb_security,
 262                 .cloned = raw_data,
 263         };
 264         struct nfs_server *server;
 265         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 266
 267         dprintk("--> nfs4_referral_get_sb()\n");
 268
 269         mount_info.mntfh = nfs_alloc_fhandle();
 270         if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
 271                 goto out;
 272
 273         /* create a new volume representation */
 274         server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
 275         if (IS_ERR(server)) {
 276                 mntroot = ERR_CAST(server);
 277                 goto out;
 278         }
 279
 280         mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
 281 out:
 282         nfs_free_fhandle(mount_info.mntfh);
 283         return mntroot;
 284 }
 285
 286 /*
 287  * Create an NFS4 server record on referral traversal
 288  */
 289 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 290                 int flags, const char *dev_name, void *raw_data)
 291 {
 292         struct nfs_clone_mount *data = raw_data;
 293         char *export_path;
 294         struct vfsmount *root_mnt;
 295         struct dentry *res;
 296
 297         dprintk("--> nfs4_referral_mount()\n");
 298
 299         export_path = data->mnt_path;
 300         data->mnt_path = "/";
 301
 302         root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
 303                         flags, data, data->hostname);
 304         data->mnt_path = export_path;
 305
 306         res = nfs_follow_remote_path(root_mnt, export_path);
 307         dprintk("<-- nfs4_referral_mount() = %ld%s\n",
 308                         IS_ERR(res) ? PTR_ERR(res) : 0,
 309                         IS_ERR(res) ? " [error]" : "");
 310         return res;
 311 }
 312
 313
 314 int __init init_nfs_v4(void)
 315 {
 316         int err;
 317
 318         err = nfs_idmap_init();
 319         if (err)
 320                 goto out;
 321
 322         err = nfs4_register_sysctl();
 323         if (err)
 324                 goto out1;
 325
 326         err = register_filesystem(&nfs4_fs_type);
 327         if (err < 0)
 328                 goto out2;
 329
 330         register_nfs_version(&nfs_v4);
 331         return 0;
 332 out2:
 333         nfs4_unregister_sysctl();
 334 out1:
 335         nfs_idmap_quit();
 336 out:
 337         return err;
 338 }
 339
 340 void exit_nfs_v4(void)
 341 {
 342         unregister_nfs_version(&nfs_v4);
 343         unregister_filesystem(&nfs4_fs_type);
 344         nfs4_unregister_sysctl();
 345         nfs_idmap_quit();
 346 }