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_referral_mount(struct file_system_type *fs_type,
  22         int flags, const char *dev_name, void *raw_data);
  23
  24 struct file_system_type nfs4_referral_fs_type = {
  25         .owner          = THIS_MODULE,
  26         .name           = "nfs4",
  27         .mount          = nfs4_referral_mount,
  28         .kill_sb        = nfs_kill_super,
  29         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
  30 };
  31
  32 static const struct super_operations nfs4_sops = {
  33         .alloc_inode    = nfs_alloc_inode,
  34         .free_inode     = nfs_free_inode,
  35         .write_inode    = nfs4_write_inode,
  36         .drop_inode     = nfs_drop_inode,
  37         .statfs         = nfs_statfs,
  38         .evict_inode    = nfs4_evict_inode,
  39         .umount_begin   = nfs_umount_begin,
  40         .show_options   = nfs_show_options,
  41         .show_devname   = nfs_show_devname,
  42         .show_path      = nfs_show_path,
  43         .show_stats     = nfs_show_stats,
  44         .remount_fs     = nfs_remount,
  45 };
  46
  47 struct nfs_subversion nfs_v4 = {
  48         .owner = THIS_MODULE,
  49         .nfs_fs   = &nfs4_fs_type,
  50         .rpc_vers = &nfs_version4,
  51         .rpc_ops  = &nfs_v4_clientops,
  52         .sops     = &nfs4_sops,
  53         .xattr    = nfs4_xattr_handlers,
  54 };
  55
  56 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  57 {
  58         int ret = nfs_write_inode(inode, wbc);
  59
  60         if (ret == 0)
  61                 ret = pnfs_layoutcommit_inode(inode,
  62                                 wbc->sync_mode == WB_SYNC_ALL);
  63         return ret;
  64 }
  65
  66 /*
  67  * Clean out any remaining NFSv4 state that might be left over due
  68  * to open() calls that passed nfs_atomic_lookup, but failed to call
  69  * nfs_open().
  70  */
  71 static void nfs4_evict_inode(struct inode *inode)
  72 {
  73         truncate_inode_pages_final(&inode->i_data);
  74         clear_inode(inode);
  75         /* If we are holding a delegation, return and free it */
  76         nfs_inode_evict_delegation(inode);
  77         /* Note that above delegreturn would trigger pnfs return-on-close */
  78         pnfs_return_layout(inode);
  79         pnfs_destroy_layout(NFS_I(inode));
  80         /* First call standard NFS clear_inode() code */
  81         nfs_clear_inode(inode);
  82 }
  83
  84 struct nfs_referral_count {
  85         struct list_head list;
  86         const struct task_struct *task;
  87         unsigned int referral_count;
  88 };
  89
  90 static LIST_HEAD(nfs_referral_count_list);
  91 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
  92
  93 static struct nfs_referral_count *nfs_find_referral_count(void)
  94 {
  95         struct nfs_referral_count *p;
  96
  97         list_for_each_entry(p, &nfs_referral_count_list, list) {
  98                 if (p->task == current)
  99                         return p;
 100         }
 101         return NULL;
 102 }
 103
 104 #define NFS_MAX_NESTED_REFERRALS 2
 105
 106 static int nfs_referral_loop_protect(void)
 107 {
 108         struct nfs_referral_count *p, *new;
 109         int ret = -ENOMEM;
 110
 111         new = kmalloc(sizeof(*new), GFP_KERNEL);
 112         if (!new)
 113                 goto out;
 114         new->task = current;
 115         new->referral_count = 1;
 116
 117         ret = 0;
 118         spin_lock(&nfs_referral_count_list_lock);
 119         p = nfs_find_referral_count();
 120         if (p != NULL) {
 121                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 122                         ret = -ELOOP;
 123                 else
 124                         p->referral_count++;
 125         } else {
 126                 list_add(&new->list, &nfs_referral_count_list);
 127                 new = NULL;
 128         }
 129         spin_unlock(&nfs_referral_count_list_lock);
 130         kfree(new);
 131 out:
 132         return ret;
 133 }
 134
 135 static void nfs_referral_loop_unprotect(void)
 136 {
 137         struct nfs_referral_count *p;
 138
 139         spin_lock(&nfs_referral_count_list_lock);
 140         p = nfs_find_referral_count();
 141         p->referral_count--;
 142         if (p->referral_count == 0)
 143                 list_del(&p->list);
 144         else
 145                 p = NULL;
 146         spin_unlock(&nfs_referral_count_list_lock);
 147         kfree(p);
 148 }
 149
 150 static struct dentry *do_nfs4_mount(struct nfs_server *server, int flags,
 151                                     struct nfs_mount_info *info,
 152                                     const char *hostname,
 153                                     const char *export_path)
 154 {
 155         struct vfsmount *root_mnt;
 156         struct dentry *dentry;
 157         char *root_devname;
 158         int err;
 159         size_t len;
 160
 161         if (IS_ERR(server))
 162                 return ERR_CAST(server);
 163
 164         len = strlen(hostname) + 5;
 165         root_devname = kmalloc(len, GFP_KERNEL);
 166         if (root_devname == NULL) {
 167                 nfs_free_server(server);
 168                 return ERR_PTR(-ENOMEM);
 169         }
 170
 171         /* Does hostname needs to be enclosed in brackets? */
 172         if (strchr(hostname, ':'))
 173                 snprintf(root_devname, len, "[%s]:/", hostname);
 174         else
 175                 snprintf(root_devname, len, "%s:/", hostname);
 176         info->server = server;
 177         root_mnt = vfs_kern_mount(&nfs_prepared_fs_type, flags, root_devname, info);
 178         if (info->server)
 179                 nfs_free_server(info->server);
 180         info->server = NULL;
 181         kfree(root_devname);
 182
 183         if (IS_ERR(root_mnt))
 184                 return ERR_CAST(root_mnt);
 185
 186         err = nfs_referral_loop_protect();
 187         if (err) {
 188                 mntput(root_mnt);
 189                 return ERR_PTR(err);
 190         }
 191
 192         dentry = mount_subtree(root_mnt, export_path);
 193         nfs_referral_loop_unprotect();
 194
 195         return dentry;
 196 }
 197
 198 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 199                               struct nfs_mount_info *mount_info)
 200 {
 201         struct nfs_parsed_mount_data *data = mount_info->parsed;
 202         struct dentry *res;
 203
 204         mount_info->set_security = nfs_set_sb_security;
 205
 206         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 207
 208         res = do_nfs4_mount(nfs4_create_server(mount_info, &nfs_v4),
 209                             flags, mount_info,
 210                             data->nfs_server.hostname,
 211                             data->nfs_server.export_path);
 212
 213         dfprintk(MOUNT, "<-- nfs4_try_mount() = %d%s\n",
 214                  PTR_ERR_OR_ZERO(res),
 215                  IS_ERR(res) ? " [error]" : "");
 216         return res;
 217 }
 218
 219 /*
 220  * Create an NFS4 server record on referral traversal
 221  */
 222 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 223                 int flags, const char *dev_name, void *raw_data)
 224 {
 225         struct nfs_clone_mount *data = raw_data;
 226         struct nfs_mount_info mount_info = {
 227                 .fill_super = nfs_fill_super,
 228                 .set_security = nfs_clone_sb_security,
 229                 .cloned = data,
 230                 .nfs_mod = &nfs_v4,
 231         };
 232         struct dentry *res;
 233
 234         dprintk("--> nfs4_referral_mount()\n");
 235
 236         mount_info.mntfh = nfs_alloc_fhandle();
 237         if (!mount_info.mntfh)
 238                 return ERR_PTR(-ENOMEM);
 239
 240         res = do_nfs4_mount(nfs4_create_referral_server(mount_info.cloned,
 241                                                         mount_info.mntfh),
 242                             flags, &mount_info, data->hostname, data->mnt_path);
 243
 244         dprintk("<-- nfs4_referral_mount() = %d%s\n",
 245                 PTR_ERR_OR_ZERO(res),
 246                 IS_ERR(res) ? " [error]" : "");
 247
 248         nfs_free_fhandle(mount_info.mntfh);
 249         return res;
 250 }
 251
 252
 253 static int __init init_nfs_v4(void)
 254 {
 255         int err;
 256
 257         err = nfs_dns_resolver_init();
 258         if (err)
 259                 goto out;
 260
 261         err = nfs_idmap_init();
 262         if (err)
 263                 goto out1;
 264
 265         err = nfs4_register_sysctl();
 266         if (err)
 267                 goto out2;
 268
 269         register_nfs_version(&nfs_v4);
 270         return 0;
 271 out2:
 272         nfs_idmap_quit();
 273 out1:
 274         nfs_dns_resolver_destroy();
 275 out:
 276         return err;
 277 }
 278
 279 static void __exit exit_nfs_v4(void)
 280 {
 281         /* Not called in the _init(), conditionally loaded */
 282         nfs4_pnfs_v3_ds_connect_unload();
 283
 284         unregister_nfs_version(&nfs_v4);
 285         nfs4_unregister_sysctl();
 286         nfs_idmap_quit();
 287         nfs_dns_resolver_destroy();
 288 }
 289
 290 MODULE_LICENSE("GPL");
 291
 292 module_init(init_nfs_v4);
 293 module_exit(exit_nfs_v4);