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/mount.h>
   8 #include <linux/nfs4_mount.h>
   9 #include <linux/nfs_fs.h>
  10 #include "delegation.h"
  11 #include "internal.h"
  12 #include "nfs4_fs.h"
  13 #include "nfs4idmap.h"
  14 #include "dns_resolve.h"
  15 #include "pnfs.h"
  16 #include "nfs.h"
  17
  18 #define NFSDBG_FACILITY         NFSDBG_VFS
  19
  20 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
  21 static void nfs4_evict_inode(struct inode *inode);
  22
  23 static const struct super_operations nfs4_sops = {
  24         .alloc_inode    = nfs_alloc_inode,
  25         .free_inode     = nfs_free_inode,
  26         .write_inode    = nfs4_write_inode,
  27         .drop_inode     = nfs_drop_inode,
  28         .statfs         = nfs_statfs,
  29         .evict_inode    = nfs4_evict_inode,
  30         .umount_begin   = nfs_umount_begin,
  31         .show_options   = nfs_show_options,
  32         .show_devname   = nfs_show_devname,
  33         .show_path      = nfs_show_path,
  34         .show_stats     = nfs_show_stats,
  35 };
  36
  37 struct nfs_subversion nfs_v4 = {
  38         .owner          = THIS_MODULE,
  39         .nfs_fs         = &nfs4_fs_type,
  40         .rpc_vers       = &nfs_version4,
  41         .rpc_ops        = &nfs_v4_clientops,
  42         .sops           = &nfs4_sops,
  43         .xattr          = nfs4_xattr_handlers,
  44 };
  45
  46 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  47 {
  48         int ret = nfs_write_inode(inode, wbc);
  49
  50         if (ret == 0)
  51                 ret = pnfs_layoutcommit_inode(inode,
  52                                 wbc->sync_mode == WB_SYNC_ALL);
  53         return ret;
  54 }
  55
  56 /*
  57  * Clean out any remaining NFSv4 state that might be left over due
  58  * to open() calls that passed nfs_atomic_lookup, but failed to call
  59  * nfs_open().
  60  */
  61 static void nfs4_evict_inode(struct inode *inode)
  62 {
  63         truncate_inode_pages_final(&inode->i_data);
  64         clear_inode(inode);
  65         /* If we are holding a delegation, return and free it */
  66         nfs_inode_evict_delegation(inode);
  67         /* Note that above delegreturn would trigger pnfs return-on-close */
  68         pnfs_return_layout(inode);
  69         pnfs_destroy_layout(NFS_I(inode));
  70         /* First call standard NFS clear_inode() code */
  71         nfs_clear_inode(inode);
  72         nfs4_xattr_cache_zap(inode);
  73 }
  74
  75 struct nfs_referral_count {
  76         struct list_head list;
  77         const struct task_struct *task;
  78         unsigned int referral_count;
  79 };
  80
  81 static LIST_HEAD(nfs_referral_count_list);
  82 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
  83
  84 static struct nfs_referral_count *nfs_find_referral_count(void)
  85 {
  86         struct nfs_referral_count *p;
  87
  88         list_for_each_entry(p, &nfs_referral_count_list, list) {
  89                 if (p->task == current)
  90                         return p;
  91         }
  92         return NULL;
  93 }
  94
  95 #define NFS_MAX_NESTED_REFERRALS 2
  96
  97 static int nfs_referral_loop_protect(void)
  98 {
  99         struct nfs_referral_count *p, *new;
 100         int ret = -ENOMEM;
 101
 102         new = kmalloc(sizeof(*new), GFP_KERNEL);
 103         if (!new)
 104                 goto out;
 105         new->task = current;
 106         new->referral_count = 1;
 107
 108         ret = 0;
 109         spin_lock(&nfs_referral_count_list_lock);
 110         p = nfs_find_referral_count();
 111         if (p != NULL) {
 112                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 113                         ret = -ELOOP;
 114                 else
 115                         p->referral_count++;
 116         } else {
 117                 list_add(&new->list, &nfs_referral_count_list);
 118                 new = NULL;
 119         }
 120         spin_unlock(&nfs_referral_count_list_lock);
 121         kfree(new);
 122 out:
 123         return ret;
 124 }
 125
 126 static void nfs_referral_loop_unprotect(void)
 127 {
 128         struct nfs_referral_count *p;
 129
 130         spin_lock(&nfs_referral_count_list_lock);
 131         p = nfs_find_referral_count();
 132         p->referral_count--;
 133         if (p->referral_count == 0)
 134                 list_del(&p->list);
 135         else
 136                 p = NULL;
 137         spin_unlock(&nfs_referral_count_list_lock);
 138         kfree(p);
 139 }
 140
 141 static int do_nfs4_mount(struct nfs_server *server,
 142                          struct fs_context *fc,
 143                          const char *hostname,
 144                          const char *export_path)
 145 {
 146         struct nfs_fs_context *root_ctx;
 147         struct fs_context *root_fc;
 148         struct vfsmount *root_mnt;
 149         struct dentry *dentry;
 150         size_t len;
 151         int ret;
 152
 153         struct fs_parameter param = {
 154                 .key    = "source",
 155                 .type   = fs_value_is_string,
 156                 .dirfd  = -1,
 157         };
 158
 159         if (IS_ERR(server))
 160                 return PTR_ERR(server);
 161
 162         root_fc = vfs_dup_fs_context(fc);
 163         if (IS_ERR(root_fc)) {
 164                 nfs_free_server(server);
 165                 return PTR_ERR(root_fc);
 166         }
 167         kfree(root_fc->source);
 168         root_fc->source = NULL;
 169
 170         root_ctx = nfs_fc2context(root_fc);
 171         root_ctx->internal = true;
 172         root_ctx->server = server;
 173         /* We leave export_path unset as it's not used to find the root. */
 174
 175         len = strlen(hostname) + 5;
 176         param.string = kmalloc(len, GFP_KERNEL);
 177         if (param.string == NULL) {
 178                 put_fs_context(root_fc);
 179                 return -ENOMEM;
 180         }
 181
 182         /* Does hostname needs to be enclosed in brackets? */
 183         if (strchr(hostname, ':'))
 184                 param.size = snprintf(param.string, len, "[%s]:/", hostname);
 185         else
 186                 param.size = snprintf(param.string, len, "%s:/", hostname);
 187         ret = vfs_parse_fs_param(root_fc, &param);
 188         kfree(param.string);
 189         if (ret < 0) {
 190                 put_fs_context(root_fc);
 191                 return ret;
 192         }
 193         root_mnt = fc_mount(root_fc);
 194         put_fs_context(root_fc);
 195
 196         if (IS_ERR(root_mnt))
 197                 return PTR_ERR(root_mnt);
 198
 199         ret = nfs_referral_loop_protect();
 200         if (ret) {
 201                 mntput(root_mnt);
 202                 return ret;
 203         }
 204
 205         dentry = mount_subtree(root_mnt, export_path);
 206         nfs_referral_loop_unprotect();
 207
 208         if (IS_ERR(dentry))
 209                 return PTR_ERR(dentry);
 210
 211         fc->root = dentry;
 212         return 0;
 213 }
 214
 215 int nfs4_try_get_tree(struct fs_context *fc)
 216 {
 217         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 218         int err;
 219
 220         dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
 221
 222         /* We create a mount for the server's root, walk to the requested
 223          * location and then create another mount for that.
 224          */
 225         err= do_nfs4_mount(nfs4_create_server(fc),
 226                            fc, ctx->nfs_server.hostname,
 227                            ctx->nfs_server.export_path);
 228         if (err) {
 229                 nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 230                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
 231         } else {
 232                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
 233         }
 234         return err;
 235 }
 236
 237 /*
 238  * Create an NFS4 server record on referral traversal
 239  */
 240 int nfs4_get_referral_tree(struct fs_context *fc)
 241 {
 242         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 243         int err;
 244
 245         dprintk("--> nfs4_referral_mount()\n");
 246
 247         /* create a new volume representation */
 248         err = do_nfs4_mount(nfs4_create_referral_server(fc),
 249                             fc, ctx->nfs_server.hostname,
 250                             ctx->nfs_server.export_path);
 251         if (err) {
 252                 nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 253                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
 254         } else {
 255                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
 256         }
 257         return err;
 258 }
 259
 260 static int __init init_nfs_v4(void)
 261 {
 262         int err;
 263
 264         err = nfs_dns_resolver_init();
 265         if (err)
 266                 goto out;
 267
 268         err = nfs_idmap_init();
 269         if (err)
 270                 goto out1;
 271
 272 #ifdef CONFIG_NFS_V4_2
 273         err = nfs4_xattr_cache_init();
 274         if (err)
 275                 goto out2;
 276 #endif
 277
 278         err = nfs4_register_sysctl();
 279         if (err)
 280                 goto out2;
 281
 282         register_nfs_version(&nfs_v4);
 283         return 0;
 284 out2:
 285         nfs_idmap_quit();
 286 out1:
 287         nfs_dns_resolver_destroy();
 288 out:
 289         return err;
 290 }
 291
 292 static void __exit exit_nfs_v4(void)
 293 {
 294         /* Not called in the _init(), conditionally loaded */
 295         nfs4_pnfs_v3_ds_connect_unload();
 296
 297         unregister_nfs_version(&nfs_v4);
 298 #ifdef CONFIG_NFS_V4_2
 299         nfs4_xattr_cache_exit();
 300 #endif
 301         nfs4_unregister_sysctl();
 302         nfs_idmap_quit();
 303         nfs_dns_resolver_destroy();
 304 }
 305
 306 MODULE_LICENSE("GPL");
 307
 308 module_init(init_nfs_v4);
 309 module_exit(exit_nfs_v4);