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 struct nfs_referral_count {
 105         struct list_head list;
 106         const struct task_struct *task;
 107         unsigned int referral_count;
 108 };
 109
 110 static LIST_HEAD(nfs_referral_count_list);
 111 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
 112
 113 static struct nfs_referral_count *nfs_find_referral_count(void)
 114 {
 115         struct nfs_referral_count *p;
 116
 117         list_for_each_entry(p, &nfs_referral_count_list, list) {
 118                 if (p->task == current)
 119                         return p;
 120         }
 121         return NULL;
 122 }
 123
 124 #define NFS_MAX_NESTED_REFERRALS 2
 125
 126 static int nfs_referral_loop_protect(void)
 127 {
 128         struct nfs_referral_count *p, *new;
 129         int ret = -ENOMEM;
 130
 131         new = kmalloc(sizeof(*new), GFP_KERNEL);
 132         if (!new)
 133                 goto out;
 134         new->task = current;
 135         new->referral_count = 1;
 136
 137         ret = 0;
 138         spin_lock(&nfs_referral_count_list_lock);
 139         p = nfs_find_referral_count();
 140         if (p != NULL) {
 141                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 142                         ret = -ELOOP;
 143                 else
 144                         p->referral_count++;
 145         } else {
 146                 list_add(&new->list, &nfs_referral_count_list);
 147                 new = NULL;
 148         }
 149         spin_unlock(&nfs_referral_count_list_lock);
 150         kfree(new);
 151 out:
 152         return ret;
 153 }
 154
 155 static void nfs_referral_loop_unprotect(void)
 156 {
 157         struct nfs_referral_count *p;
 158
 159         spin_lock(&nfs_referral_count_list_lock);
 160         p = nfs_find_referral_count();
 161         p->referral_count--;
 162         if (p->referral_count == 0)
 163                 list_del(&p->list);
 164         else
 165                 p = NULL;
 166         spin_unlock(&nfs_referral_count_list_lock);
 167         kfree(p);
 168 }
 169
 170 static struct dentry *do_nfs4_mount(struct nfs_server *server, int flags,
 171                                     struct nfs_mount_info *info,
 172                                     const char *hostname,
 173                                     const char *export_path)
 174 {
 175         struct vfsmount *root_mnt;
 176         struct dentry *dentry;
 177         char *root_devname;
 178         int err;
 179         size_t len;
 180
 181         if (IS_ERR(server))
 182                 return ERR_CAST(server);
 183
 184         len = strlen(hostname) + 5;
 185         root_devname = kmalloc(len, GFP_KERNEL);
 186         if (root_devname == NULL) {
 187                 nfs_free_server(server);
 188                 return ERR_PTR(-ENOMEM);
 189         }
 190
 191         /* Does hostname needs to be enclosed in brackets? */
 192         if (strchr(hostname, ':'))
 193                 snprintf(root_devname, len, "[%s]:/", hostname);
 194         else
 195                 snprintf(root_devname, len, "%s:/", hostname);
 196         info->server = server;
 197         root_mnt = vfs_kern_mount(&nfs4_remote_fs_type, flags, root_devname, info);
 198         if (info->server)
 199                 nfs_free_server(info->server);
 200         info->server = NULL;
 201         kfree(root_devname);
 202
 203         if (IS_ERR(root_mnt))
 204                 return ERR_CAST(root_mnt);
 205
 206         err = nfs_referral_loop_protect();
 207         if (err) {
 208                 mntput(root_mnt);
 209                 return ERR_PTR(err);
 210         }
 211
 212         dentry = mount_subtree(root_mnt, export_path);
 213         nfs_referral_loop_unprotect();
 214
 215         return dentry;
 216 }
 217
 218 struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 219                               struct nfs_mount_info *mount_info,
 220                               struct nfs_subversion *nfs_mod)
 221 {
 222         struct nfs_parsed_mount_data *data = mount_info->parsed;
 223         struct dentry *res;
 224
 225         mount_info->set_security = nfs_set_sb_security;
 226
 227         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 228
 229         res = do_nfs4_mount(nfs4_create_server(mount_info, &nfs_v4),
 230                             flags, mount_info,
 231                             data->nfs_server.hostname,
 232                             data->nfs_server.export_path);
 233
 234         dfprintk(MOUNT, "<-- nfs4_try_mount() = %d%s\n",
 235                  PTR_ERR_OR_ZERO(res),
 236                  IS_ERR(res) ? " [error]" : "");
 237         return res;
 238 }
 239
 240 /*
 241  * Create an NFS4 server record on referral traversal
 242  */
 243 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 244                 int flags, const char *dev_name, void *raw_data)
 245 {
 246         struct nfs_clone_mount *data = raw_data;
 247         struct nfs_mount_info mount_info = {
 248                 .fill_super = nfs_fill_super,
 249                 .set_security = nfs_clone_sb_security,
 250                 .cloned = data,
 251                 .nfs_mod = &nfs_v4,
 252         };
 253         struct dentry *res;
 254
 255         dprintk("--> nfs4_referral_mount()\n");
 256
 257         mount_info.mntfh = nfs_alloc_fhandle();
 258         if (!mount_info.mntfh)
 259                 return ERR_PTR(-ENOMEM);
 260
 261         res = do_nfs4_mount(nfs4_create_referral_server(mount_info.cloned,
 262                                                         mount_info.mntfh),
 263                             flags, &mount_info, data->hostname, data->mnt_path);
 264
 265         dprintk("<-- nfs4_referral_mount() = %d%s\n",
 266                 PTR_ERR_OR_ZERO(res),
 267                 IS_ERR(res) ? " [error]" : "");
 268
 269         nfs_free_fhandle(mount_info.mntfh);
 270         return res;
 271 }
 272
 273
 274 static int __init init_nfs_v4(void)
 275 {
 276         int err;
 277
 278         err = nfs_dns_resolver_init();
 279         if (err)
 280                 goto out;
 281
 282         err = nfs_idmap_init();
 283         if (err)
 284                 goto out1;
 285
 286         err = nfs4_register_sysctl();
 287         if (err)
 288                 goto out2;
 289
 290         register_nfs_version(&nfs_v4);
 291         return 0;
 292 out2:
 293         nfs_idmap_quit();
 294 out1:
 295         nfs_dns_resolver_destroy();
 296 out:
 297         return err;
 298 }
 299
 300 static void __exit exit_nfs_v4(void)
 301 {
 302         /* Not called in the _init(), conditionally loaded */
 303         nfs4_pnfs_v3_ds_connect_unload();
 304
 305         unregister_nfs_version(&nfs_v4);
 306         nfs4_unregister_sysctl();
 307         nfs_idmap_quit();
 308         nfs_dns_resolver_destroy();
 309 }
 310
 311 MODULE_LICENSE("GPL");
 312
 313 module_init(init_nfs_v4);
 314 module_exit(exit_nfs_v4);