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
  26 static struct file_system_type nfs4_remote_fs_type = {
  27         .owner          = THIS_MODULE,
  28         .name           = "nfs4",
  29         .mount          = nfs4_remote_mount,
  30         .kill_sb        = nfs_kill_super,
  31         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  32 };
  33
  34 struct file_system_type nfs4_referral_fs_type = {
  35         .owner          = THIS_MODULE,
  36         .name           = "nfs4",
  37         .mount          = nfs4_referral_mount,
  38         .kill_sb        = nfs_kill_super,
  39         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  40 };
  41
  42 static const struct super_operations nfs4_sops = {
  43         .alloc_inode    = nfs_alloc_inode,
  44         .free_inode     = nfs_free_inode,
  45         .write_inode    = nfs4_write_inode,
  46         .drop_inode     = nfs_drop_inode,
  47         .statfs         = nfs_statfs,
  48         .evict_inode    = nfs4_evict_inode,
  49         .umount_begin   = nfs_umount_begin,
  50         .show_options   = nfs_show_options,
  51         .show_devname   = nfs_show_devname,
  52         .show_path      = nfs_show_path,
  53         .show_stats     = nfs_show_stats,
  54         .remount_fs     = nfs_remount,
  55 };
  56
  57 struct nfs_subversion nfs_v4 = {
  58         .owner = THIS_MODULE,
  59         .nfs_fs   = &nfs4_fs_type,
  60         .rpc_vers = &nfs_version4,
  61         .rpc_ops  = &nfs_v4_clientops,
  62         .sops     = &nfs4_sops,
  63         .xattr    = nfs4_xattr_handlers,
  64 };
  65
  66 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  67 {
  68         int ret = nfs_write_inode(inode, wbc);
  69
  70         if (ret == 0)
  71                 ret = pnfs_layoutcommit_inode(inode,
  72                                 wbc->sync_mode == WB_SYNC_ALL);
  73         return ret;
  74 }
  75
  76 /*
  77  * Clean out any remaining NFSv4 state that might be left over due
  78  * to open() calls that passed nfs_atomic_lookup, but failed to call
  79  * nfs_open().
  80  */
  81 static void nfs4_evict_inode(struct inode *inode)
  82 {
  83         truncate_inode_pages_final(&inode->i_data);
  84         clear_inode(inode);
  85         /* If we are holding a delegation, return and free it */
  86         nfs_inode_evict_delegation(inode);
  87         /* Note that above delegreturn would trigger pnfs return-on-close */
  88         pnfs_return_layout(inode);
  89         pnfs_destroy_layout(NFS_I(inode));
  90         /* First call standard NFS clear_inode() code */
  91         nfs_clear_inode(inode);
  92 }
  93
  94 /*
  95  * Get the superblock for the NFS4 root partition
  96  */
  97 static struct dentry *
  98 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
  99                   const char *dev_name, void *info)
 100 {
 101         return nfs_fs_mount_common(flags, dev_name, info, &nfs_v4);
 102 }
 103
 104 static struct vfsmount *nfs_do_root_mount(struct nfs_server *server, int flags,
 105                                           struct nfs_mount_info *info,
 106                                           const char *hostname)
 107 {
 108         struct vfsmount *root_mnt;
 109         char *root_devname;
 110         size_t len;
 111
 112         if (IS_ERR(server))
 113                 return ERR_CAST(server);
 114
 115         len = strlen(hostname) + 5;
 116         root_devname = kmalloc(len, GFP_KERNEL);
 117         if (root_devname == NULL) {
 118                 nfs_free_server(server);
 119                 return ERR_PTR(-ENOMEM);
 120         }
 121         /* Does hostname needs to be enclosed in brackets? */
 122         if (strchr(hostname, ':'))
 123                 snprintf(root_devname, len, "[%s]:/", hostname);
 124         else
 125                 snprintf(root_devname, len, "%s:/", hostname);
 126         info->server = server;
 127         root_mnt = vfs_kern_mount(&nfs4_remote_fs_type, flags, root_devname, info);
 128         if (info->server)
 129                 nfs_free_server(info->server);
 130         info->server = NULL;
 131         kfree(root_devname);
 132         return root_mnt;
 133 }
 134
 135 struct nfs_referral_count {
 136         struct list_head list;
 137         const struct task_struct *task;
 138         unsigned int referral_count;
 139 };
 140
 141 static LIST_HEAD(nfs_referral_count_list);
 142 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 143
 144 static struct nfs_referral_count *nfs_find_referral_count(void)
 145 {
 146         struct nfs_referral_count *p;
 147
 148         list_for_each_entry(p, &nfs_referral_count_list, list) {
 149                 if (p->task == current)
 150                         return p;
 151         }
 152         return NULL;
 153 }
 154
 155 #define NFS_MAX_NESTED_REFERRALS 2
 156
 157 static int nfs_referral_loop_protect(void)
 158 {
 159         struct nfs_referral_count *p, *new;
 160         int ret = -ENOMEM;
 161
 162         new = kmalloc(sizeof(*new), GFP_KERNEL);
 163         if (!new)
 164                 goto out;
 165         new->task = current;
 166         new->referral_count = 1;
 167
 168         ret = 0;
 169         spin_lock(&nfs_referral_count_list_lock);
 170         p = nfs_find_referral_count();
 171         if (p != NULL) {
 172                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 173                         ret = -ELOOP;
 174                 else
 175                         p->referral_count++;
 176         } else {
 177                 list_add(&new->list, &nfs_referral_count_list);
 178                 new = NULL;
 179         }
 180         spin_unlock(&nfs_referral_count_list_lock);
 181         kfree(new);
 182 out:
 183         return ret;
 184 }
 185
 186 static void nfs_referral_loop_unprotect(void)
 187 {
 188         struct nfs_referral_count *p;
 189
 190         spin_lock(&nfs_referral_count_list_lock);
 191         p = nfs_find_referral_count();
 192         p->referral_count--;
 193         if (p->referral_count == 0)
 194                 list_del(&p->list);
 195         else
 196                 p = NULL;
 197         spin_unlock(&nfs_referral_count_list_lock);
 198         kfree(p);
 199 }
 200
 201 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
 202                 const char *export_path)
 203 {
 204         struct dentry *dentry;
 205         int err;
 206
 207         if (IS_ERR(root_mnt))
 208                 return ERR_CAST(root_mnt);
 209
 210         err = nfs_referral_loop_protect();
 211         if (err) {
 212                 mntput(root_mnt);
 213                 return ERR_PTR(err);
 214         }
 215
 216         dentry = mount_subtree(root_mnt, export_path);
 217         nfs_referral_loop_unprotect();
 218
 219         return dentry;
 220 }
 221
 222 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 223                               struct nfs_mount_info *mount_info,
 224                               struct nfs_subversion *nfs_mod)
 225 {
 226         char *export_path;
 227         struct vfsmount *root_mnt;
 228         struct dentry *res;
 229         struct nfs_parsed_mount_data *data = mount_info->parsed;
 230
 231         mount_info->set_security = nfs_set_sb_security;
 232
 233         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 234
 235         export_path = data->nfs_server.export_path;
 236         data->nfs_server.export_path = "/";
 237         root_mnt = nfs_do_root_mount(
 238                         nfs4_create_server(mount_info, &nfs_v4),
 239                         flags, mount_info,
 240                         data->nfs_server.hostname);
 241         data->nfs_server.export_path = export_path;
 242
 243         res = nfs_follow_remote_path(root_mnt, export_path);
 244
 245         dfprintk(MOUNT, "<-- nfs4_try_mount() = %d%s\n",
 246                  PTR_ERR_OR_ZERO(res),
 247                  IS_ERR(res) ? " [error]" : "");
 248         return res;
 249 }
 250
 251 /*
 252  * Create an NFS4 server record on referral traversal
 253  */
 254 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 255                 int flags, const char *dev_name, void *raw_data)
 256 {
 257         struct nfs_clone_mount *data = raw_data;
 258         struct nfs_mount_info mount_info = {
 259                 .fill_super = nfs_fill_super,
 260                 .set_security = nfs_clone_sb_security,
 261                 .cloned = data,
 262         };
 263         char *export_path;
 264         struct vfsmount *root_mnt;
 265         struct dentry *res;
 266
 267         dprintk("--> nfs4_referral_mount()\n");
 268
 269         mount_info.mntfh = nfs_alloc_fhandle();
 270         if (!mount_info.mntfh)
 271                 return ERR_PTR(-ENOMEM);
 272
 273         export_path = data->mnt_path;
 274         data->mnt_path = "/";
 275         root_mnt = nfs_do_root_mount(
 276                         nfs4_create_referral_server(mount_info.cloned,
 277                                                     mount_info.mntfh),
 278                         flags, &mount_info, data->hostname);
 279         data->mnt_path = export_path;
 280
 281         res = nfs_follow_remote_path(root_mnt, export_path);
 282         dprintk("<-- nfs4_referral_mount() = %d%s\n",
 283                 PTR_ERR_OR_ZERO(res),
 284                 IS_ERR(res) ? " [error]" : "");
 285
 286         nfs_free_fhandle(mount_info.mntfh);
 287         return res;
 288 }
 289
 290
 291 static int __init init_nfs_v4(void)
 292 {
 293         int err;
 294
 295         err = nfs_dns_resolver_init();
 296         if (err)
 297                 goto out;
 298
 299         err = nfs_idmap_init();
 300         if (err)
 301                 goto out1;
 302
 303         err = nfs4_register_sysctl();
 304         if (err)
 305                 goto out2;
 306
 307         register_nfs_version(&nfs_v4);
 308         return 0;
 309 out2:
 310         nfs_idmap_quit();
 311 out1:
 312         nfs_dns_resolver_destroy();
 313 out:
 314         return err;
 315 }
 316
 317 static void __exit exit_nfs_v4(void)
 318 {
 319         /* Not called in the _init(), conditionally loaded */
 320         nfs4_pnfs_v3_ds_connect_unload();
 321
 322         unregister_nfs_version(&nfs_v4);
 323         nfs4_unregister_sysctl();
 324         nfs_idmap_quit();
 325         nfs_dns_resolver_destroy();
 326 }
 327
 328 MODULE_LICENSE("GPL");
 329
 330 module_init(init_nfs_v4);
 331 module_exit(exit_nfs_v4);