fs/nfs/nfs4super.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
   4  */
   5 #include <linux/init.h>
   6 #include <linux/module.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 "nfs4idmap.h"
  13 #include "dns_resolve.h"
  14 #include "pnfs.h"
  15 #include "nfs.h"
  16
  17 #define NFSDBG_FACILITY         NFSDBG_VFS
  18
  19 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
  20 static void nfs4_evict_inode(struct inode *inode);
  21 static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type,
  22         int flags, const char *dev_name, void *raw_data);
  23 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
  24         int flags, const char *dev_name, void *raw_data);
  25 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
  26         int flags, const char *dev_name, void *raw_data);
  27
  28 static struct file_system_type nfs4_remote_fs_type = {
  29         .owner          = THIS_MODULE,
  30         .name           = "nfs4",
  31         .mount          = nfs4_remote_mount,
  32         .kill_sb        = nfs_kill_super,
  33         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  34 };
  35
  36 static struct file_system_type nfs4_remote_referral_fs_type = {
  37         .owner          = THIS_MODULE,
  38         .name           = "nfs4",
  39         .mount          = nfs4_remote_referral_mount,
  40         .kill_sb        = nfs_kill_super,
  41         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  42 };
  43
  44 struct file_system_type nfs4_referral_fs_type = {
  45         .owner          = THIS_MODULE,
  46         .name           = "nfs4",
  47         .mount          = nfs4_referral_mount,
  48         .kill_sb        = nfs_kill_super,
  49         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  50 };
  51
  52 static const struct super_operations nfs4_sops = {
  53         .alloc_inode    = nfs_alloc_inode,
  54         .free_inode     = nfs_free_inode,
  55         .write_inode    = nfs4_write_inode,
  56         .drop_inode     = nfs_drop_inode,
  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)
  81                 ret = pnfs_layoutcommit_inode(inode,
  82                                 wbc->sync_mode == WB_SYNC_ALL);
  83         return ret;
  84 }
  85
  86 /*
  87  * Clean out any remaining NFSv4 state that might be left over due
  88  * to open() calls that passed nfs_atomic_lookup, but failed to call
  89  * nfs_open().
  90  */
  91 static void nfs4_evict_inode(struct inode *inode)
  92 {
  93         truncate_inode_pages_final(&inode->i_data);
  94         clear_inode(inode);
  95         /* If we are holding a delegation, return it! */
  96         nfs_inode_return_delegation_noreclaim(inode);
  97         /* Note that above delegreturn would trigger pnfs return-on-close */
  98         pnfs_return_layout(inode);
  99         pnfs_destroy_layout(NFS_I(inode));
 100         /* First call standard NFS clear_inode() code */
 101         nfs_clear_inode(inode);
 102 }
 103
 104 /*
 105  * Get the superblock for the NFS4 root partition
 106  */
 107 static struct dentry *
 108 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
 109                   const char *dev_name, void *info)
 110 {
 111         struct nfs_mount_info *mount_info = info;
 112         struct nfs_server *server;
 113         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 114
 115         mount_info->set_security = nfs_set_sb_security;
 116
 117         /* Get a volume representation */
 118         server = nfs4_create_server(mount_info, &nfs_v4);
 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                               struct nfs_subversion *nfs_mod)
 241 {
 242         char *export_path;
 243         struct vfsmount *root_mnt;
 244         struct dentry *res;
 245         struct nfs_parsed_mount_data *data = mount_info->parsed;
 246
 247         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 248
 249         export_path = data->nfs_server.export_path;
 250         data->nfs_server.export_path = "/";
 251         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,
 252                         data->nfs_server.hostname);
 253         data->nfs_server.export_path = export_path;
 254
 255         res = nfs_follow_remote_path(root_mnt, export_path);
 256
 257         dfprintk(MOUNT, "<-- nfs4_try_mount() = %d%s\n",
 258                  PTR_ERR_OR_ZERO(res),
 259                  IS_ERR(res) ? " [error]" : "");
 260         return res;
 261 }
 262
 263 static struct dentry *
 264 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
 265                            const char *dev_name, void *raw_data)
 266 {
 267         struct nfs_mount_info mount_info = {
 268                 .fill_super = nfs_fill_super,
 269                 .set_security = nfs_clone_sb_security,
 270                 .cloned = raw_data,
 271         };
 272         struct nfs_server *server;
 273         struct dentry *mntroot = ERR_PTR(-ENOMEM);
 274
 275         dprintk("--> nfs4_referral_get_sb()\n");
 276
 277         mount_info.mntfh = nfs_alloc_fhandle();
 278         if (mount_info.cloned == NULL || mount_info.mntfh == NULL)
 279                 goto out;
 280
 281         /* create a new volume representation */
 282         server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh);
 283         if (IS_ERR(server)) {
 284                 mntroot = ERR_CAST(server);
 285                 goto out;
 286         }
 287
 288         mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
 289 out:
 290         nfs_free_fhandle(mount_info.mntfh);
 291         return mntroot;
 292 }
 293
 294 /*
 295  * Create an NFS4 server record on referral traversal
 296  */
 297 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 298                 int flags, const char *dev_name, void *raw_data)
 299 {
 300         struct nfs_clone_mount *data = raw_data;
 301         char *export_path;
 302         struct vfsmount *root_mnt;
 303         struct dentry *res;
 304
 305         dprintk("--> nfs4_referral_mount()\n");
 306
 307         export_path = data->mnt_path;
 308         data->mnt_path = "/";
 309
 310         root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
 311                         flags, data, data->hostname);
 312         data->mnt_path = export_path;
 313
 314         res = nfs_follow_remote_path(root_mnt, export_path);
 315         dprintk("<-- nfs4_referral_mount() = %d%s\n",
 316                 PTR_ERR_OR_ZERO(res),
 317                 IS_ERR(res) ? " [error]" : "");
 318         return res;
 319 }
 320
 321
 322 static int __init init_nfs_v4(void)
 323 {
 324         int err;
 325
 326         err = nfs_dns_resolver_init();
 327         if (err)
 328                 goto out;
 329
 330         err = nfs_idmap_init();
 331         if (err)
 332                 goto out1;
 333
 334         err = nfs4_register_sysctl();
 335         if (err)
 336                 goto out2;
 337
 338         register_nfs_version(&nfs_v4);
 339         return 0;
 340 out2:
 341         nfs_idmap_quit();
 342 out1:
 343         nfs_dns_resolver_destroy();
 344 out:
 345         return err;
 346 }
 347
 348 static void __exit exit_nfs_v4(void)
 349 {
 350         /* Not called in the _init(), conditionally loaded */
 351         nfs4_pnfs_v3_ds_connect_unload();
 352
 353         unregister_nfs_version(&nfs_v4);
 354         nfs4_unregister_sysctl();
 355         nfs_idmap_quit();
 356         nfs_dns_resolver_destroy();
 357 }
 358
 359 MODULE_LICENSE("GPL");
 360
 361 module_init(init_nfs_v4);
 362 module_exit(exit_nfs_v4);