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 <linux/nfs_ssc.h>
  11 #include "delegation.h"
  12 #include "internal.h"
  13 #include "nfs4_fs.h"
  14 #include "nfs4idmap.h"
  15 #include "dns_resolve.h"
  16 #include "pnfs.h"
  17 #include "nfs.h"
  18
  19 #define NFSDBG_FACILITY         NFSDBG_VFS
  20
  21 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
  22 static void nfs4_evict_inode(struct inode *inode);
  23
  24 static const struct super_operations nfs4_sops = {
  25         .alloc_inode    = nfs_alloc_inode,
  26         .free_inode     = nfs_free_inode,
  27         .write_inode    = nfs4_write_inode,
  28         .drop_inode     = nfs_drop_inode,
  29         .statfs         = nfs_statfs,
  30         .evict_inode    = nfs4_evict_inode,
  31         .umount_begin   = nfs_umount_begin,
  32         .show_options   = nfs_show_options,
  33         .show_devname   = nfs_show_devname,
  34         .show_path      = nfs_show_path,
  35         .show_stats     = nfs_show_stats,
  36 };
  37
  38 struct nfs_subversion nfs_v4 = {
  39         .owner          = THIS_MODULE,
  40         .nfs_fs         = &nfs4_fs_type,
  41         .rpc_vers       = &nfs_version4,
  42         .rpc_ops        = &nfs_v4_clientops,
  43         .sops           = &nfs4_sops,
  44         .xattr          = nfs4_xattr_handlers,
  45 };
  46
  47 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
  48 {
  49         int ret = nfs_write_inode(inode, wbc);
  50
  51         if (ret == 0)
  52                 ret = pnfs_layoutcommit_inode(inode,
  53                                 wbc->sync_mode == WB_SYNC_ALL);
  54         return ret;
  55 }
  56
  57 /*
  58  * Clean out any remaining NFSv4 state that might be left over due
  59  * to open() calls that passed nfs_atomic_lookup, but failed to call
  60  * nfs_open().
  61  */
  62 static void nfs4_evict_inode(struct inode *inode)
  63 {
  64         truncate_inode_pages_final(&inode->i_data);
  65         clear_inode(inode);
  66         /* If we are holding a delegation, return and free it */
  67         nfs_inode_evict_delegation(inode);
  68         /* Note that above delegreturn would trigger pnfs return-on-close */
  69         pnfs_return_layout(inode);
  70         pnfs_destroy_layout_final(NFS_I(inode));
  71         /* First call standard NFS clear_inode() code */
  72         nfs_clear_inode(inode);
  73         nfs4_xattr_cache_zap(inode);
  74 }
  75
  76 struct nfs_referral_count {
  77         struct list_head list;
  78         const struct task_struct *task;
  79         unsigned int referral_count;
  80 };
  81
  82 static LIST_HEAD(nfs_referral_count_list);
  83 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
  84
  85 static struct nfs_referral_count *nfs_find_referral_count(void)
  86 {
  87         struct nfs_referral_count *p;
  88
  89         list_for_each_entry(p, &nfs_referral_count_list, list) {
  90                 if (p->task == current)
  91                         return p;
  92         }
  93         return NULL;
  94 }
  95
  96 #define NFS_MAX_NESTED_REFERRALS 2
  97
  98 static int nfs_referral_loop_protect(void)
  99 {
 100         struct nfs_referral_count *p, *new;
 101         int ret = -ENOMEM;
 102
 103         new = kmalloc(sizeof(*new), GFP_KERNEL);
 104         if (!new)
 105                 goto out;
 106         new->task = current;
 107         new->referral_count = 1;
 108
 109         ret = 0;
 110         spin_lock(&nfs_referral_count_list_lock);
 111         p = nfs_find_referral_count();
 112         if (p != NULL) {
 113                 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
 114                         ret = -ELOOP;
 115                 else
 116                         p->referral_count++;
 117         } else {
 118                 list_add(&new->list, &nfs_referral_count_list);
 119                 new = NULL;
 120         }
 121         spin_unlock(&nfs_referral_count_list_lock);
 122         kfree(new);
 123 out:
 124         return ret;
 125 }
 126
 127 static void nfs_referral_loop_unprotect(void)
 128 {
 129         struct nfs_referral_count *p;
 130
 131         spin_lock(&nfs_referral_count_list_lock);
 132         p = nfs_find_referral_count();
 133         p->referral_count--;
 134         if (p->referral_count == 0)
 135                 list_del(&p->list);
 136         else
 137                 p = NULL;
 138         spin_unlock(&nfs_referral_count_list_lock);
 139         kfree(p);
 140 }
 141
 142 static int do_nfs4_mount(struct nfs_server *server,
 143                          struct fs_context *fc,
 144                          const char *hostname,
 145                          const char *export_path)
 146 {
 147         struct nfs_fs_context *root_ctx;
 148         struct nfs_fs_context *ctx;
 149         struct fs_context *root_fc;
 150         struct vfsmount *root_mnt;
 151         struct dentry *dentry;
 152         size_t len;
 153         int ret;
 154
 155         struct fs_parameter param = {
 156                 .key    = "source",
 157                 .type   = fs_value_is_string,
 158                 .dirfd  = -1,
 159         };
 160
 161         struct fs_parameter param_fsc = {
 162                 .key    = "fsc",
 163                 .type   = fs_value_is_string,
 164                 .dirfd  = -1,
 165         };
 166
 167         if (IS_ERR(server))
 168                 return PTR_ERR(server);
 169
 170         root_fc = vfs_dup_fs_context(fc);
 171         if (IS_ERR(root_fc)) {
 172                 nfs_free_server(server);
 173                 return PTR_ERR(root_fc);
 174         }
 175         kfree(root_fc->source);
 176         root_fc->source = NULL;
 177
 178         ctx = nfs_fc2context(fc);
 179         root_ctx = nfs_fc2context(root_fc);
 180         root_ctx->internal = true;
 181         root_ctx->server = server;
 182
 183         if (ctx->fscache_uniq) {
 184                 len = strlen(ctx->fscache_uniq);
 185                 param_fsc.size = len;
 186                 param_fsc.string = kmemdup_nul(ctx->fscache_uniq, len, GFP_KERNEL);
 187                 if (param_fsc.string == NULL) {
 188                         put_fs_context(root_fc);
 189                         return -ENOMEM;
 190                 }
 191                 ret = vfs_parse_fs_param(root_fc, &param_fsc);
 192                 kfree(param_fsc.string);
 193                 if (ret < 0) {
 194                         put_fs_context(root_fc);
 195                         return ret;
 196                 }
 197         }
 198         /* We leave export_path unset as it's not used to find the root. */
 199
 200         len = strlen(hostname) + 5;
 201         param.string = kmalloc(len, GFP_KERNEL);
 202         if (param.string == NULL) {
 203                 put_fs_context(root_fc);
 204                 return -ENOMEM;
 205         }
 206
 207         /* Does hostname needs to be enclosed in brackets? */
 208         if (strchr(hostname, ':'))
 209                 param.size = snprintf(param.string, len, "[%s]:/", hostname);
 210         else
 211                 param.size = snprintf(param.string, len, "%s:/", hostname);
 212         ret = vfs_parse_fs_param(root_fc, &param);
 213         kfree(param.string);
 214         if (ret < 0) {
 215                 put_fs_context(root_fc);
 216                 return ret;
 217         }
 218         root_mnt = fc_mount(root_fc);
 219         put_fs_context(root_fc);
 220
 221         if (IS_ERR(root_mnt))
 222                 return PTR_ERR(root_mnt);
 223
 224         ret = nfs_referral_loop_protect();
 225         if (ret) {
 226                 mntput(root_mnt);
 227                 return ret;
 228         }
 229
 230         dentry = mount_subtree(root_mnt, export_path);
 231         nfs_referral_loop_unprotect();
 232
 233         if (IS_ERR(dentry))
 234                 return PTR_ERR(dentry);
 235
 236         fc->root = dentry;
 237         return 0;
 238 }
 239
 240 int nfs4_try_get_tree(struct fs_context *fc)
 241 {
 242         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 243         int err;
 244
 245         dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
 246
 247         /* We create a mount for the server's root, walk to the requested
 248          * location and then create another mount for that.
 249          */
 250         err= do_nfs4_mount(nfs4_create_server(fc),
 251                            fc, ctx->nfs_server.hostname,
 252                            ctx->nfs_server.export_path);
 253         if (err) {
 254                 nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
 255                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
 256         } else {
 257                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
 258         }
 259         return err;
 260 }
 261
 262 /*
 263  * Create an NFS4 server record on referral traversal
 264  */
 265 int nfs4_get_referral_tree(struct fs_context *fc)
 266 {
 267         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 268         int err;
 269
 270         dprintk("--> nfs4_referral_mount()\n");
 271
 272         /* create a new volume representation */
 273         err = do_nfs4_mount(nfs4_create_referral_server(fc),
 274                             fc, ctx->nfs_server.hostname,
 275                             ctx->nfs_server.export_path);
 276         if (err) {
 277                 nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
 278                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
 279         } else {
 280                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
 281         }
 282         return err;
 283 }
 284
 285 static int __init init_nfs_v4(void)
 286 {
 287         int err;
 288
 289         err = nfs_dns_resolver_init();
 290         if (err)
 291                 goto out;
 292
 293         err = nfs_idmap_init();
 294         if (err)
 295                 goto out1;
 296
 297 #ifdef CONFIG_NFS_V4_2
 298         err = nfs4_xattr_cache_init();
 299         if (err)
 300                 goto out2;
 301 #endif
 302
 303         err = nfs4_register_sysctl();
 304         if (err)
 305                 goto out2;
 306
 307 #ifdef CONFIG_NFS_V4_2
 308         nfs42_ssc_register_ops();
 309 #endif
 310         register_nfs_version(&nfs_v4);
 311         return 0;
 312 out2:
 313         nfs_idmap_quit();
 314 out1:
 315         nfs_dns_resolver_destroy();
 316 out:
 317         return err;
 318 }
 319
 320 static void __exit exit_nfs_v4(void)
 321 {
 322         /* Not called in the _init(), conditionally loaded */
 323         nfs4_pnfs_v3_ds_connect_unload();
 324
 325         unregister_nfs_version(&nfs_v4);
 326 #ifdef CONFIG_NFS_V4_2
 327         nfs4_xattr_cache_exit();
 328         nfs42_ssc_unregister_ops();
 329 #endif
 330         nfs4_unregister_sysctl();
 331         nfs_idmap_quit();
 332         nfs_dns_resolver_destroy();
 333 }
 334
 335 MODULE_DESCRIPTION("NFSv4 client support");
 336 MODULE_LICENSE("GPL");
 337
 338 module_init(init_nfs_v4);
 339 module_exit(exit_nfs_v4);