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 fs_context *root_fc;
 149         struct vfsmount *root_mnt;
 150         struct dentry *dentry;
 151         size_t len;
 152         int ret;
 153
 154         struct fs_parameter param = {
 155                 .key    = "source",
 156                 .type   = fs_value_is_string,
 157                 .dirfd  = -1,
 158         };
 159
 160         if (IS_ERR(server))
 161                 return PTR_ERR(server);
 162
 163         root_fc = vfs_dup_fs_context(fc);
 164         if (IS_ERR(root_fc)) {
 165                 nfs_free_server(server);
 166                 return PTR_ERR(root_fc);
 167         }
 168         kfree(root_fc->source);
 169         root_fc->source = NULL;
 170
 171         root_ctx = nfs_fc2context(root_fc);
 172         root_ctx->internal = true;
 173         root_ctx->server = server;
 174         /* We leave export_path unset as it's not used to find the root. */
 175
 176         len = strlen(hostname) + 5;
 177         param.string = kmalloc(len, GFP_KERNEL);
 178         if (param.string == NULL) {
 179                 put_fs_context(root_fc);
 180                 return -ENOMEM;
 181         }
 182
 183         /* Does hostname needs to be enclosed in brackets? */
 184         if (strchr(hostname, ':'))
 185                 param.size = snprintf(param.string, len, "[%s]:/", hostname);
 186         else
 187                 param.size = snprintf(param.string, len, "%s:/", hostname);
 188         ret = vfs_parse_fs_param(root_fc, &param);
 189         kfree(param.string);
 190         if (ret < 0) {
 191                 put_fs_context(root_fc);
 192                 return ret;
 193         }
 194         root_mnt = fc_mount(root_fc);
 195         put_fs_context(root_fc);
 196
 197         if (IS_ERR(root_mnt))
 198                 return PTR_ERR(root_mnt);
 199
 200         ret = nfs_referral_loop_protect();
 201         if (ret) {
 202                 mntput(root_mnt);
 203                 return ret;
 204         }
 205
 206         dentry = mount_subtree(root_mnt, export_path);
 207         nfs_referral_loop_unprotect();
 208
 209         if (IS_ERR(dentry))
 210                 return PTR_ERR(dentry);
 211
 212         fc->root = dentry;
 213         return 0;
 214 }
 215
 216 int nfs4_try_get_tree(struct fs_context *fc)
 217 {
 218         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 219         int err;
 220
 221         dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
 222
 223         /* We create a mount for the server's root, walk to the requested
 224          * location and then create another mount for that.
 225          */
 226         err= do_nfs4_mount(nfs4_create_server(fc),
 227                            fc, ctx->nfs_server.hostname,
 228                            ctx->nfs_server.export_path);
 229         if (err) {
 230                 nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 231                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
 232         } else {
 233                 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
 234         }
 235         return err;
 236 }
 237
 238 /*
 239  * Create an NFS4 server record on referral traversal
 240  */
 241 int nfs4_get_referral_tree(struct fs_context *fc)
 242 {
 243         struct nfs_fs_context *ctx = nfs_fc2context(fc);
 244         int err;
 245
 246         dprintk("--> nfs4_referral_mount()\n");
 247
 248         /* create a new volume representation */
 249         err = do_nfs4_mount(nfs4_create_referral_server(fc),
 250                             fc, ctx->nfs_server.hostname,
 251                             ctx->nfs_server.export_path);
 252         if (err) {
 253                 nfs_errorf(fc, "NFS4: Couldn't follow remote path");
 254                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
 255         } else {
 256                 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
 257         }
 258         return err;
 259 }
 260
 261 static int __init init_nfs_v4(void)
 262 {
 263         int err;
 264
 265         err = nfs_dns_resolver_init();
 266         if (err)
 267                 goto out;
 268
 269         err = nfs_idmap_init();
 270         if (err)
 271                 goto out1;
 272
 273 #ifdef CONFIG_NFS_V4_2
 274         err = nfs4_xattr_cache_init();
 275         if (err)
 276                 goto out2;
 277 #endif
 278
 279         err = nfs4_register_sysctl();
 280         if (err)
 281                 goto out2;
 282
 283 #ifdef CONFIG_NFS_V4_2
 284         nfs42_ssc_register_ops();
 285 #endif
 286         register_nfs_version(&nfs_v4);
 287         return 0;
 288 out2:
 289         nfs_idmap_quit();
 290 out1:
 291         nfs_dns_resolver_destroy();
 292 out:
 293         return err;
 294 }
 295
 296 static void __exit exit_nfs_v4(void)
 297 {
 298         /* Not called in the _init(), conditionally loaded */
 299         nfs4_pnfs_v3_ds_connect_unload();
 300
 301         unregister_nfs_version(&nfs_v4);
 302 #ifdef CONFIG_NFS_V4_2
 303         nfs4_xattr_cache_exit();
 304         nfs42_ssc_unregister_ops();
 305 #endif
 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);