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   1 /*
   2  *  linux/fs/nfs/super.c
   3  *
   4  *  Copyright (C) 1992  Rick Sladkey
   5  *
   6  *  nfs superblock handling functions
   7  *
   8  *  Modularised by Alan Cox <Alan.Cox@linux.org>, while hacking some
   9  *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
  10  *
  11  *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
  12  *  J.S.Peatfield@damtp.cam.ac.uk
  13  *
  14  *  Split from inode.c by David Howells <dhowells@redhat.com>
  15  *
  16  * - superblocks are indexed on server only - all inodes, dentries, etc. associated with a
  17  *   particular server are held in the same superblock
  18  * - NFS superblocks can have several effective roots to the dentry tree
  19  * - directory type roots are spliced into the tree when a path from one root reaches the root
  20  *   of another (see nfs_lookup())
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/init.h>
  25
  26 #include <linux/time.h>
  27 #include <linux/kernel.h>
  28 #include <linux/mm.h>
  29 #include <linux/string.h>
  30 #include <linux/stat.h>
  31 #include <linux/errno.h>
  32 #include <linux/unistd.h>
  33 #include <linux/sunrpc/clnt.h>
  34 #include <linux/sunrpc/stats.h>
  35 #include <linux/sunrpc/metrics.h>
  36 #include <linux/sunrpc/xprtsock.h>
  37 #include <linux/sunrpc/xprtrdma.h>
  38 #include <linux/nfs_fs.h>
  39 #include <linux/nfs_mount.h>
  40 #include <linux/nfs4_mount.h>
  41 #include <linux/lockd/bind.h>
  42 #include <linux/smp_lock.h>
  43 #include <linux/seq_file.h>
  44 #include <linux/mount.h>
  45 #include <linux/nfs_idmap.h>
  46 #include <linux/vfs.h>
  47 #include <linux/inet.h>
  48 #include <linux/in6.h>
  49 #include <net/ipv6.h>
  50 #include <linux/nfs_xdr.h>
  51 #include <linux/magic.h>
  52 #include <linux/parser.h>
  53
  54 #include <asm/system.h>
  55 #include <asm/uaccess.h>
  56
  57 #include "nfs4_fs.h"
  58 #include "callback.h"
  59 #include "delegation.h"
  60 #include "iostat.h"
  61 #include "internal.h"
  62
  63 #define NFSDBG_FACILITY         NFSDBG_VFS
  64
  65 enum {
  66         /* Mount options that take no arguments */
  67         Opt_soft, Opt_hard,
  68         Opt_intr, Opt_nointr,
  69         Opt_posix, Opt_noposix,
  70         Opt_cto, Opt_nocto,
  71         Opt_ac, Opt_noac,
  72         Opt_lock, Opt_nolock,
  73         Opt_v2, Opt_v3,
  74         Opt_udp, Opt_tcp, Opt_rdma,
  75         Opt_acl, Opt_noacl,
  76         Opt_rdirplus, Opt_nordirplus,
  77         Opt_sharecache, Opt_nosharecache,
  78
  79         /* Mount options that take integer arguments */
  80         Opt_port,
  81         Opt_rsize, Opt_wsize, Opt_bsize,
  82         Opt_timeo, Opt_retrans,
  83         Opt_acregmin, Opt_acregmax,
  84         Opt_acdirmin, Opt_acdirmax,
  85         Opt_actimeo,
  86         Opt_namelen,
  87         Opt_mountport,
  88         Opt_mountvers,
  89         Opt_nfsvers,
  90
  91         /* Mount options that take string arguments */
  92         Opt_sec, Opt_proto, Opt_mountproto,
  93         Opt_addr, Opt_mountaddr, Opt_clientaddr,
  94
  95         /* Mount options that are ignored */
  96         Opt_userspace, Opt_deprecated,
  97
  98         Opt_err
  99 };
 100
 101 static match_table_t nfs_mount_option_tokens = {
 102         { Opt_userspace, "bg" },
 103         { Opt_userspace, "fg" },
 104         { Opt_soft, "soft" },
 105         { Opt_hard, "hard" },
 106         { Opt_intr, "intr" },
 107         { Opt_nointr, "nointr" },
 108         { Opt_posix, "posix" },
 109         { Opt_noposix, "noposix" },
 110         { Opt_cto, "cto" },
 111         { Opt_nocto, "nocto" },
 112         { Opt_ac, "ac" },
 113         { Opt_noac, "noac" },
 114         { Opt_lock, "lock" },
 115         { Opt_nolock, "nolock" },
 116         { Opt_v2, "v2" },
 117         { Opt_v3, "v3" },
 118         { Opt_udp, "udp" },
 119         { Opt_tcp, "tcp" },
 120         { Opt_rdma, "rdma" },
 121         { Opt_acl, "acl" },
 122         { Opt_noacl, "noacl" },
 123         { Opt_rdirplus, "rdirplus" },
 124         { Opt_nordirplus, "nordirplus" },
 125         { Opt_sharecache, "sharecache" },
 126         { Opt_nosharecache, "nosharecache" },
 127
 128         { Opt_port, "port=%u" },
 129         { Opt_rsize, "rsize=%u" },
 130         { Opt_wsize, "wsize=%u" },
 131         { Opt_bsize, "bsize=%u" },
 132         { Opt_timeo, "timeo=%u" },
 133         { Opt_retrans, "retrans=%u" },
 134         { Opt_acregmin, "acregmin=%u" },
 135         { Opt_acregmax, "acregmax=%u" },
 136         { Opt_acdirmin, "acdirmin=%u" },
 137         { Opt_acdirmax, "acdirmax=%u" },
 138         { Opt_actimeo, "actimeo=%u" },
 139         { Opt_userspace, "retry=%u" },
 140         { Opt_namelen, "namlen=%u" },
 141         { Opt_mountport, "mountport=%u" },
 142         { Opt_mountvers, "mountvers=%u" },
 143         { Opt_nfsvers, "nfsvers=%u" },
 144         { Opt_nfsvers, "vers=%u" },
 145
 146         { Opt_sec, "sec=%s" },
 147         { Opt_proto, "proto=%s" },
 148         { Opt_mountproto, "mountproto=%s" },
 149         { Opt_addr, "addr=%s" },
 150         { Opt_clientaddr, "clientaddr=%s" },
 151         { Opt_userspace, "mounthost=%s" },
 152         { Opt_mountaddr, "mountaddr=%s" },
 153
 154         { Opt_err, NULL }
 155 };
 156
 157 enum {
 158         Opt_xprt_udp, Opt_xprt_tcp, Opt_xprt_rdma,
 159
 160         Opt_xprt_err
 161 };
 162
 163 static match_table_t nfs_xprt_protocol_tokens = {
 164         { Opt_xprt_udp, "udp" },
 165         { Opt_xprt_tcp, "tcp" },
 166         { Opt_xprt_rdma, "rdma" },
 167
 168         { Opt_xprt_err, NULL }
 169 };
 170
 171 enum {
 172         Opt_sec_none, Opt_sec_sys,
 173         Opt_sec_krb5, Opt_sec_krb5i, Opt_sec_krb5p,
 174         Opt_sec_lkey, Opt_sec_lkeyi, Opt_sec_lkeyp,
 175         Opt_sec_spkm, Opt_sec_spkmi, Opt_sec_spkmp,
 176
 177         Opt_sec_err
 178 };
 179
 180 static match_table_t nfs_secflavor_tokens = {
 181         { Opt_sec_none, "none" },
 182         { Opt_sec_none, "null" },
 183         { Opt_sec_sys, "sys" },
 184
 185         { Opt_sec_krb5, "krb5" },
 186         { Opt_sec_krb5i, "krb5i" },
 187         { Opt_sec_krb5p, "krb5p" },
 188
 189         { Opt_sec_lkey, "lkey" },
 190         { Opt_sec_lkeyi, "lkeyi" },
 191         { Opt_sec_lkeyp, "lkeyp" },
 192
 193         { Opt_sec_err, NULL }
 194 };
 195
 196
 197 static void nfs_umount_begin(struct vfsmount *, int);
 198 static int  nfs_statfs(struct dentry *, struct kstatfs *);
 199 static int  nfs_show_options(struct seq_file *, struct vfsmount *);
 200 static int  nfs_show_stats(struct seq_file *, struct vfsmount *);
 201 static int nfs_get_sb(struct file_system_type *, int, const char *, void *, struct vfsmount *);
 202 static int nfs_xdev_get_sb(struct file_system_type *fs_type,
 203                 int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 204 static void nfs_kill_super(struct super_block *);
 205 static void nfs_put_super(struct super_block *);
 206
 207 static struct file_system_type nfs_fs_type = {
 208         .owner          = THIS_MODULE,
 209         .name           = "nfs",
 210         .get_sb         = nfs_get_sb,
 211         .kill_sb        = nfs_kill_super,
 212         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 213 };
 214
 215 struct file_system_type nfs_xdev_fs_type = {
 216         .owner          = THIS_MODULE,
 217         .name           = "nfs",
 218         .get_sb         = nfs_xdev_get_sb,
 219         .kill_sb        = nfs_kill_super,
 220         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 221 };
 222
 223 static const struct super_operations nfs_sops = {
 224         .alloc_inode    = nfs_alloc_inode,
 225         .destroy_inode  = nfs_destroy_inode,
 226         .write_inode    = nfs_write_inode,
 227         .put_super      = nfs_put_super,
 228         .statfs         = nfs_statfs,
 229         .clear_inode    = nfs_clear_inode,
 230         .umount_begin   = nfs_umount_begin,
 231         .show_options   = nfs_show_options,
 232         .show_stats     = nfs_show_stats,
 233 };
 234
 235 #ifdef CONFIG_NFS_V4
 236 static int nfs4_get_sb(struct file_system_type *fs_type,
 237         int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 238 static int nfs4_xdev_get_sb(struct file_system_type *fs_type,
 239         int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 240 static int nfs4_referral_get_sb(struct file_system_type *fs_type,
 241         int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 242 static void nfs4_kill_super(struct super_block *sb);
 243
 244 static struct file_system_type nfs4_fs_type = {
 245         .owner          = THIS_MODULE,
 246         .name           = "nfs4",
 247         .get_sb         = nfs4_get_sb,
 248         .kill_sb        = nfs4_kill_super,
 249         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 250 };
 251
 252 struct file_system_type nfs4_xdev_fs_type = {
 253         .owner          = THIS_MODULE,
 254         .name           = "nfs4",
 255         .get_sb         = nfs4_xdev_get_sb,
 256         .kill_sb        = nfs4_kill_super,
 257         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 258 };
 259
 260 struct file_system_type nfs4_referral_fs_type = {
 261         .owner          = THIS_MODULE,
 262         .name           = "nfs4",
 263         .get_sb         = nfs4_referral_get_sb,
 264         .kill_sb        = nfs4_kill_super,
 265         .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 266 };
 267
 268 static const struct super_operations nfs4_sops = {
 269         .alloc_inode    = nfs_alloc_inode,
 270         .destroy_inode  = nfs_destroy_inode,
 271         .write_inode    = nfs_write_inode,
 272         .statfs         = nfs_statfs,
 273         .clear_inode    = nfs4_clear_inode,
 274         .umount_begin   = nfs_umount_begin,
 275         .show_options   = nfs_show_options,
 276         .show_stats     = nfs_show_stats,
 277 };
 278 #endif
 279
 280 static struct shrinker acl_shrinker = {
 281         .shrink         = nfs_access_cache_shrinker,
 282         .seeks          = DEFAULT_SEEKS,
 283 };
 284
 285 /*
 286  * Register the NFS filesystems
 287  */
 288 int __init register_nfs_fs(void)
 289 {
 290         int ret;
 291
 292         ret = register_filesystem(&nfs_fs_type);
 293         if (ret < 0)
 294                 goto error_0;
 295
 296         ret = nfs_register_sysctl();
 297         if (ret < 0)
 298                 goto error_1;
 299 #ifdef CONFIG_NFS_V4
 300         ret = register_filesystem(&nfs4_fs_type);
 301         if (ret < 0)
 302                 goto error_2;
 303 #endif
 304         register_shrinker(&acl_shrinker);
 305         return 0;
 306
 307 #ifdef CONFIG_NFS_V4
 308 error_2:
 309         nfs_unregister_sysctl();
 310 #endif
 311 error_1:
 312         unregister_filesystem(&nfs_fs_type);
 313 error_0:
 314         return ret;
 315 }
 316
 317 /*
 318  * Unregister the NFS filesystems
 319  */
 320 void __exit unregister_nfs_fs(void)
 321 {
 322         unregister_shrinker(&acl_shrinker);
 323 #ifdef CONFIG_NFS_V4
 324         unregister_filesystem(&nfs4_fs_type);
 325 #endif
 326         nfs_unregister_sysctl();
 327         unregister_filesystem(&nfs_fs_type);
 328 }
 329
 330 void nfs_sb_active(struct nfs_server *server)
 331 {
 332         atomic_inc(&server->active);
 333 }
 334
 335 void nfs_sb_deactive(struct nfs_server *server)
 336 {
 337         if (atomic_dec_and_test(&server->active))
 338                 wake_up(&server->active_wq);
 339 }
 340
 341 static void nfs_put_super(struct super_block *sb)
 342 {
 343         struct nfs_server *server = NFS_SB(sb);
 344         /*
 345          * Make sure there are no outstanding ops to this server.
 346          * If so, wait for them to finish before allowing the
 347          * unmount to continue.
 348          */
 349         wait_event(server->active_wq, atomic_read(&server->active) == 0);
 350 }
 351
 352 /*
 353  * Deliver file system statistics to userspace
 354  */
 355 static int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 356 {
 357         struct nfs_server *server = NFS_SB(dentry->d_sb);
 358         unsigned char blockbits;
 359         unsigned long blockres;
 360         struct nfs_fh *fh = NFS_FH(dentry->d_inode);
 361         struct nfs_fattr fattr;
 362         struct nfs_fsstat res = {
 363                         .fattr = &fattr,
 364         };
 365         int error;
 366
 367         lock_kernel();
 368
 369         error = server->nfs_client->rpc_ops->statfs(server, fh, &res);
 370         if (error < 0)
 371                 goto out_err;
 372         buf->f_type = NFS_SUPER_MAGIC;
 373
 374         /*
 375          * Current versions of glibc do not correctly handle the
 376          * case where f_frsize != f_bsize.  Eventually we want to
 377          * report the value of wtmult in this field.
 378          */
 379         buf->f_frsize = dentry->d_sb->s_blocksize;
 380
 381         /*
 382          * On most *nix systems, f_blocks, f_bfree, and f_bavail
 383          * are reported in units of f_frsize.  Linux hasn't had
 384          * an f_frsize field in its statfs struct until recently,
 385          * thus historically Linux's sys_statfs reports these
 386          * fields in units of f_bsize.
 387          */
 388         buf->f_bsize = dentry->d_sb->s_blocksize;
 389         blockbits = dentry->d_sb->s_blocksize_bits;
 390         blockres = (1 << blockbits) - 1;
 391         buf->f_blocks = (res.tbytes + blockres) >> blockbits;
 392         buf->f_bfree = (res.fbytes + blockres) >> blockbits;
 393         buf->f_bavail = (res.abytes + blockres) >> blockbits;
 394
 395         buf->f_files = res.tfiles;
 396         buf->f_ffree = res.afiles;
 397
 398         buf->f_namelen = server->namelen;
 399
 400         unlock_kernel();
 401         return 0;
 402
 403  out_err:
 404         dprintk("%s: statfs error = %d\n", __FUNCTION__, -error);
 405         unlock_kernel();
 406         return error;
 407 }
 408
 409 /*
 410  * Map the security flavour number to a name
 411  */
 412 static const char *nfs_pseudoflavour_to_name(rpc_authflavor_t flavour)
 413 {
 414         static const struct {
 415                 rpc_authflavor_t flavour;
 416                 const char *str;
 417         } sec_flavours[] = {
 418                 { RPC_AUTH_NULL, "null" },
 419                 { RPC_AUTH_UNIX, "sys" },
 420                 { RPC_AUTH_GSS_KRB5, "krb5" },
 421                 { RPC_AUTH_GSS_KRB5I, "krb5i" },
 422                 { RPC_AUTH_GSS_KRB5P, "krb5p" },
 423                 { RPC_AUTH_GSS_LKEY, "lkey" },
 424                 { RPC_AUTH_GSS_LKEYI, "lkeyi" },
 425                 { RPC_AUTH_GSS_LKEYP, "lkeyp" },
 426                 { RPC_AUTH_GSS_SPKM, "spkm" },
 427                 { RPC_AUTH_GSS_SPKMI, "spkmi" },
 428                 { RPC_AUTH_GSS_SPKMP, "spkmp" },
 429                 { UINT_MAX, "unknown" }
 430         };
 431         int i;
 432
 433         for (i = 0; sec_flavours[i].flavour != UINT_MAX; i++) {
 434                 if (sec_flavours[i].flavour == flavour)
 435                         break;
 436         }
 437         return sec_flavours[i].str;
 438 }
 439
 440 /*
 441  * Describe the mount options in force on this server representation
 442  */
 443 static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss, int showdefaults)
 444 {
 445         static const struct proc_nfs_info {
 446                 int flag;
 447                 const char *str;
 448                 const char *nostr;
 449         } nfs_info[] = {
 450                 { NFS_MOUNT_SOFT, ",soft", ",hard" },
 451                 { NFS_MOUNT_INTR, ",intr", ",nointr" },
 452                 { NFS_MOUNT_NOCTO, ",nocto", "" },
 453                 { NFS_MOUNT_NOAC, ",noac", "" },
 454                 { NFS_MOUNT_NONLM, ",nolock", "" },
 455                 { NFS_MOUNT_NOACL, ",noacl", "" },
 456                 { NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
 457                 { NFS_MOUNT_UNSHARED, ",nosharecache", ""},
 458                 { 0, NULL, NULL }
 459         };
 460         const struct proc_nfs_info *nfs_infop;
 461         struct nfs_client *clp = nfss->nfs_client;
 462
 463         seq_printf(m, ",vers=%d", clp->rpc_ops->version);
 464         seq_printf(m, ",rsize=%d", nfss->rsize);
 465         seq_printf(m, ",wsize=%d", nfss->wsize);
 466         if (nfss->acregmin != 3*HZ || showdefaults)
 467                 seq_printf(m, ",acregmin=%d", nfss->acregmin/HZ);
 468         if (nfss->acregmax != 60*HZ || showdefaults)
 469                 seq_printf(m, ",acregmax=%d", nfss->acregmax/HZ);
 470         if (nfss->acdirmin != 30*HZ || showdefaults)
 471                 seq_printf(m, ",acdirmin=%d", nfss->acdirmin/HZ);
 472         if (nfss->acdirmax != 60*HZ || showdefaults)
 473                 seq_printf(m, ",acdirmax=%d", nfss->acdirmax/HZ);
 474         for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
 475                 if (nfss->flags & nfs_infop->flag)
 476                         seq_puts(m, nfs_infop->str);
 477                 else
 478                         seq_puts(m, nfs_infop->nostr);
 479         }
 480         seq_printf(m, ",proto=%s",
 481                    rpc_peeraddr2str(nfss->client, RPC_DISPLAY_PROTO));
 482         seq_printf(m, ",timeo=%lu", 10U * clp->retrans_timeo / HZ);
 483         seq_printf(m, ",retrans=%u", clp->retrans_count);
 484         seq_printf(m, ",sec=%s", nfs_pseudoflavour_to_name(nfss->client->cl_auth->au_flavor));
 485 }
 486
 487 /*
 488  * Describe the mount options on this VFS mountpoint
 489  */
 490 static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 491 {
 492         struct nfs_server *nfss = NFS_SB(mnt->mnt_sb);
 493
 494         nfs_show_mount_options(m, nfss, 0);
 495
 496         seq_printf(m, ",addr=%s",
 497                         rpc_peeraddr2str(nfss->nfs_client->cl_rpcclient,
 498                                                         RPC_DISPLAY_ADDR));
 499
 500         return 0;
 501 }
 502
 503 /*
 504  * Present statistical information for this VFS mountpoint
 505  */
 506 static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
 507 {
 508         int i, cpu;
 509         struct nfs_server *nfss = NFS_SB(mnt->mnt_sb);
 510         struct rpc_auth *auth = nfss->client->cl_auth;
 511         struct nfs_iostats totals = { };
 512
 513         seq_printf(m, "statvers=%s", NFS_IOSTAT_VERS);
 514
 515         /*
 516          * Display all mount option settings
 517          */
 518         seq_printf(m, "\n\topts:\t");
 519         seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? "ro" : "rw");
 520         seq_puts(m, mnt->mnt_sb->s_flags & MS_SYNCHRONOUS ? ",sync" : "");
 521         seq_puts(m, mnt->mnt_sb->s_flags & MS_NOATIME ? ",noatime" : "");
 522         seq_puts(m, mnt->mnt_sb->s_flags & MS_NODIRATIME ? ",nodiratime" : "");
 523         nfs_show_mount_options(m, nfss, 1);
 524
 525         seq_printf(m, "\n\tage:\t%lu", (jiffies - nfss->mount_time) / HZ);
 526
 527         seq_printf(m, "\n\tcaps:\t");
 528         seq_printf(m, "caps=0x%x", nfss->caps);
 529         seq_printf(m, ",wtmult=%d", nfss->wtmult);
 530         seq_printf(m, ",dtsize=%d", nfss->dtsize);
 531         seq_printf(m, ",bsize=%d", nfss->bsize);
 532         seq_printf(m, ",namelen=%d", nfss->namelen);
 533
 534 #ifdef CONFIG_NFS_V4
 535         if (nfss->nfs_client->rpc_ops->version == 4) {
 536                 seq_printf(m, "\n\tnfsv4:\t");
 537                 seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
 538                 seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
 539                 seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
 540         }
 541 #endif
 542
 543         /*
 544          * Display security flavor in effect for this mount
 545          */
 546         seq_printf(m, "\n\tsec:\tflavor=%d", auth->au_ops->au_flavor);
 547         if (auth->au_flavor)
 548                 seq_printf(m, ",pseudoflavor=%d", auth->au_flavor);
 549
 550         /*
 551          * Display superblock I/O counters
 552          */
 553         for_each_possible_cpu(cpu) {
 554                 struct nfs_iostats *stats;
 555
 556                 preempt_disable();
 557                 stats = per_cpu_ptr(nfss->io_stats, cpu);
 558
 559                 for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
 560                         totals.events[i] += stats->events[i];
 561                 for (i = 0; i < __NFSIOS_BYTESMAX; i++)
 562                         totals.bytes[i] += stats->bytes[i];
 563
 564                 preempt_enable();
 565         }
 566
 567         seq_printf(m, "\n\tevents:\t");
 568         for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
 569                 seq_printf(m, "%lu ", totals.events[i]);
 570         seq_printf(m, "\n\tbytes:\t");
 571         for (i = 0; i < __NFSIOS_BYTESMAX; i++)
 572                 seq_printf(m, "%Lu ", totals.bytes[i]);
 573         seq_printf(m, "\n");
 574
 575         rpc_print_iostats(m, nfss->client);
 576
 577         return 0;
 578 }
 579
 580 /*
 581  * Begin unmount by attempting to remove all automounted mountpoints we added
 582  * in response to xdev traversals and referrals
 583  */
 584 static void nfs_umount_begin(struct vfsmount *vfsmnt, int flags)
 585 {
 586         struct nfs_server *server = NFS_SB(vfsmnt->mnt_sb);
 587         struct rpc_clnt *rpc;
 588
 589         shrink_submounts(vfsmnt, &nfs_automount_list);
 590
 591         if (!(flags & MNT_FORCE))
 592                 return;
 593         /* -EIO all pending I/O */
 594         rpc = server->client_acl;
 595         if (!IS_ERR(rpc))
 596                 rpc_killall_tasks(rpc);
 597         rpc = server->client;
 598         if (!IS_ERR(rpc))
 599                 rpc_killall_tasks(rpc);
 600 }
 601
 602 /*
 603  * Sanity-check a server address provided by the mount command
 604  */
 605 static int nfs_verify_server_address(struct sockaddr *addr)
 606 {
 607         switch (addr->sa_family) {
 608         case AF_INET: {
 609                 struct sockaddr_in *sa = (struct sockaddr_in *) addr;
 610                 if (sa->sin_addr.s_addr != INADDR_ANY)
 611                         return 1;
 612                 break;
 613         }
 614         }
 615
 616         return 0;
 617 }
 618
 619 /*
 620  * Error-check and convert a string of mount options from user space into
 621  * a data structure
 622  */
 623 static int nfs_parse_mount_options(char *raw,
 624                                    struct nfs_parsed_mount_data *mnt)
 625 {
 626         char *p, *string;
 627
 628         if (!raw) {
 629                 dfprintk(MOUNT, "NFS: mount options string was NULL.\n");
 630                 return 1;
 631         }
 632         dfprintk(MOUNT, "NFS: nfs mount opts='%s'\n", raw);
 633
 634         while ((p = strsep(&raw, ",")) != NULL) {
 635                 substring_t args[MAX_OPT_ARGS];
 636                 int option, token;
 637
 638                 if (!*p)
 639                         continue;
 640
 641                 dfprintk(MOUNT, "NFS:   parsing nfs mount option '%s'\n", p);
 642
 643                 token = match_token(p, nfs_mount_option_tokens, args);
 644                 switch (token) {
 645                 case Opt_soft:
 646                         mnt->flags |= NFS_MOUNT_SOFT;
 647                         break;
 648                 case Opt_hard:
 649                         mnt->flags &= ~NFS_MOUNT_SOFT;
 650                         break;
 651                 case Opt_intr:
 652                         mnt->flags |= NFS_MOUNT_INTR;
 653                         break;
 654                 case Opt_nointr:
 655                         mnt->flags &= ~NFS_MOUNT_INTR;
 656                         break;
 657                 case Opt_posix:
 658                         mnt->flags |= NFS_MOUNT_POSIX;
 659                         break;
 660                 case Opt_noposix:
 661                         mnt->flags &= ~NFS_MOUNT_POSIX;
 662                         break;
 663                 case Opt_cto:
 664                         mnt->flags &= ~NFS_MOUNT_NOCTO;
 665                         break;
 666                 case Opt_nocto:
 667                         mnt->flags |= NFS_MOUNT_NOCTO;
 668                         break;
 669                 case Opt_ac:
 670                         mnt->flags &= ~NFS_MOUNT_NOAC;
 671                         break;
 672                 case Opt_noac:
 673                         mnt->flags |= NFS_MOUNT_NOAC;
 674                         break;
 675                 case Opt_lock:
 676                         mnt->flags &= ~NFS_MOUNT_NONLM;
 677                         break;
 678                 case Opt_nolock:
 679                         mnt->flags |= NFS_MOUNT_NONLM;
 680                         break;
 681                 case Opt_v2:
 682                         mnt->flags &= ~NFS_MOUNT_VER3;
 683                         break;
 684                 case Opt_v3:
 685                         mnt->flags |= NFS_MOUNT_VER3;
 686                         break;
 687                 case Opt_udp:
 688                         mnt->flags &= ~NFS_MOUNT_TCP;
 689                         mnt->nfs_server.protocol = XPRT_TRANSPORT_UDP;
 690                         mnt->timeo = 7;
 691                         mnt->retrans = 5;
 692                         break;
 693                 case Opt_tcp:
 694                         mnt->flags |= NFS_MOUNT_TCP;
 695                         mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
 696                         mnt->timeo = 600;
 697                         mnt->retrans = 2;
 698                         break;
 699                 case Opt_rdma:
 700                         mnt->flags |= NFS_MOUNT_TCP; /* for side protocols */
 701                         mnt->nfs_server.protocol = XPRT_TRANSPORT_RDMA;
 702                         mnt->timeo = 600;
 703                         mnt->retrans = 2;
 704                         break;
 705                 case Opt_acl:
 706                         mnt->flags &= ~NFS_MOUNT_NOACL;
 707                         break;
 708                 case Opt_noacl:
 709                         mnt->flags |= NFS_MOUNT_NOACL;
 710                         break;
 711                 case Opt_rdirplus:
 712                         mnt->flags &= ~NFS_MOUNT_NORDIRPLUS;
 713                         break;
 714                 case Opt_nordirplus:
 715                         mnt->flags |= NFS_MOUNT_NORDIRPLUS;
 716                         break;
 717                 case Opt_sharecache:
 718                         mnt->flags &= ~NFS_MOUNT_UNSHARED;
 719                         break;
 720                 case Opt_nosharecache:
 721                         mnt->flags |= NFS_MOUNT_UNSHARED;
 722                         break;
 723
 724                 case Opt_port:
 725                         if (match_int(args, &option))
 726                                 return 0;
 727                         if (option < 0 || option > 65535)
 728                                 return 0;
 729                         mnt->nfs_server.address.sin_port = htons(option);
 730                         break;
 731                 case Opt_rsize:
 732                         if (match_int(args, &mnt->rsize))
 733                                 return 0;
 734                         break;
 735                 case Opt_wsize:
 736                         if (match_int(args, &mnt->wsize))
 737                                 return 0;
 738                         break;
 739                 case Opt_bsize:
 740                         if (match_int(args, &option))
 741                                 return 0;
 742                         if (option < 0)
 743                                 return 0;
 744                         mnt->bsize = option;
 745                         break;
 746                 case Opt_timeo:
 747                         if (match_int(args, &mnt->timeo))
 748                                 return 0;
 749                         break;
 750                 case Opt_retrans:
 751                         if (match_int(args, &mnt->retrans))
 752                                 return 0;
 753                         break;
 754                 case Opt_acregmin:
 755                         if (match_int(args, &mnt->acregmin))
 756                                 return 0;
 757                         break;
 758                 case Opt_acregmax:
 759                         if (match_int(args, &mnt->acregmax))
 760                                 return 0;
 761                         break;
 762                 case Opt_acdirmin:
 763                         if (match_int(args, &mnt->acdirmin))
 764                                 return 0;
 765                         break;
 766                 case Opt_acdirmax:
 767                         if (match_int(args, &mnt->acdirmax))
 768                                 return 0;
 769                         break;
 770                 case Opt_actimeo:
 771                         if (match_int(args, &option))
 772                                 return 0;
 773                         if (option < 0)
 774                                 return 0;
 775                         mnt->acregmin =
 776                         mnt->acregmax =
 777                         mnt->acdirmin =
 778                         mnt->acdirmax = option;
 779                         break;
 780                 case Opt_namelen:
 781                         if (match_int(args, &mnt->namlen))
 782                                 return 0;
 783                         break;
 784                 case Opt_mountport:
 785                         if (match_int(args, &option))
 786                                 return 0;
 787                         if (option < 0 || option > 65535)
 788                                 return 0;
 789                         mnt->mount_server.port = option;
 790                         break;
 791                 case Opt_mountvers:
 792                         if (match_int(args, &option))
 793                                 return 0;
 794                         if (option < 0)
 795                                 return 0;
 796                         mnt->mount_server.version = option;
 797                         break;
 798                 case Opt_nfsvers:
 799                         if (match_int(args, &option))
 800                                 return 0;
 801                         switch (option) {
 802                         case 2:
 803                                 mnt->flags &= ~NFS_MOUNT_VER3;
 804                                 break;
 805                         case 3:
 806                                 mnt->flags |= NFS_MOUNT_VER3;
 807                                 break;
 808                         default:
 809                                 goto out_unrec_vers;
 810                         }
 811                         break;
 812
 813                 case Opt_sec:
 814                         string = match_strdup(args);
 815                         if (string == NULL)
 816                                 goto out_nomem;
 817                         token = match_token(string, nfs_secflavor_tokens, args);
 818                         kfree(string);
 819
 820                         /*
 821                          * The flags setting is for v2/v3.  The flavor_len
 822                          * setting is for v4.  v2/v3 also need to know the
 823                          * difference between NULL and UNIX.
 824                          */
 825                         switch (token) {
 826                         case Opt_sec_none:
 827                                 mnt->flags &= ~NFS_MOUNT_SECFLAVOUR;
 828                                 mnt->auth_flavor_len = 0;
 829                                 mnt->auth_flavors[0] = RPC_AUTH_NULL;
 830                                 break;
 831                         case Opt_sec_sys:
 832                                 mnt->flags &= ~NFS_MOUNT_SECFLAVOUR;
 833                                 mnt->auth_flavor_len = 0;
 834                                 mnt->auth_flavors[0] = RPC_AUTH_UNIX;
 835                                 break;
 836                         case Opt_sec_krb5:
 837                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 838                                 mnt->auth_flavor_len = 1;
 839                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_KRB5;
 840                                 break;
 841                         case Opt_sec_krb5i:
 842                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 843                                 mnt->auth_flavor_len = 1;
 844                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_KRB5I;
 845                                 break;
 846                         case Opt_sec_krb5p:
 847                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 848                                 mnt->auth_flavor_len = 1;
 849                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_KRB5P;
 850                                 break;
 851                         case Opt_sec_lkey:
 852                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 853                                 mnt->auth_flavor_len = 1;
 854                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_LKEY;
 855                                 break;
 856                         case Opt_sec_lkeyi:
 857                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 858                                 mnt->auth_flavor_len = 1;
 859                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_LKEYI;
 860                                 break;
 861                         case Opt_sec_lkeyp:
 862                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 863                                 mnt->auth_flavor_len = 1;
 864                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_LKEYP;
 865                                 break;
 866                         case Opt_sec_spkm:
 867                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 868                                 mnt->auth_flavor_len = 1;
 869                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_SPKM;
 870                                 break;
 871                         case Opt_sec_spkmi:
 872                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 873                                 mnt->auth_flavor_len = 1;
 874                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_SPKMI;
 875                                 break;
 876                         case Opt_sec_spkmp:
 877                                 mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 878                                 mnt->auth_flavor_len = 1;
 879                                 mnt->auth_flavors[0] = RPC_AUTH_GSS_SPKMP;
 880                                 break;
 881                         default:
 882                                 goto out_unrec_sec;
 883                         }
 884                         break;
 885                 case Opt_proto:
 886                         string = match_strdup(args);
 887                         if (string == NULL)
 888                                 goto out_nomem;
 889                         token = match_token(string,
 890                                             nfs_xprt_protocol_tokens, args);
 891                         kfree(string);
 892
 893                         switch (token) {
 894                         case Opt_xprt_udp:
 895                                 mnt->flags &= ~NFS_MOUNT_TCP;
 896                                 mnt->nfs_server.protocol = XPRT_TRANSPORT_UDP;
 897                                 mnt->timeo = 7;
 898                                 mnt->retrans = 5;
 899                                 break;
 900                         case Opt_xprt_tcp:
 901                                 mnt->flags |= NFS_MOUNT_TCP;
 902                                 mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
 903                                 mnt->timeo = 600;
 904                                 mnt->retrans = 2;
 905                                 break;
 906                         case Opt_xprt_rdma:
 907                                 /* vector side protocols to TCP */
 908                                 mnt->flags |= NFS_MOUNT_TCP;
 909                                 mnt->nfs_server.protocol = XPRT_TRANSPORT_RDMA;
 910                                 mnt->timeo = 600;
 911                                 mnt->retrans = 2;
 912                                 break;
 913                         default:
 914                                 goto out_unrec_xprt;
 915                         }
 916                         break;
 917                 case Opt_mountproto:
 918                         string = match_strdup(args);
 919                         if (string == NULL)
 920                                 goto out_nomem;
 921                         token = match_token(string,
 922                                             nfs_xprt_protocol_tokens, args);
 923                         kfree(string);
 924
 925                         switch (token) {
 926                         case Opt_xprt_udp:
 927                                 mnt->mount_server.protocol = XPRT_TRANSPORT_UDP;
 928                                 break;
 929                         case Opt_xprt_tcp:
 930                                 mnt->mount_server.protocol = XPRT_TRANSPORT_TCP;
 931                                 break;
 932                         case Opt_xprt_rdma: /* not used for side protocols */
 933                         default:
 934                                 goto out_unrec_xprt;
 935                         }
 936                         break;
 937                 case Opt_addr:
 938                         string = match_strdup(args);
 939                         if (string == NULL)
 940                                 goto out_nomem;
 941                         mnt->nfs_server.address.sin_family = AF_INET;
 942                         mnt->nfs_server.address.sin_addr.s_addr =
 943                                                         in_aton(string);
 944                         kfree(string);
 945                         break;
 946                 case Opt_clientaddr:
 947                         string = match_strdup(args);
 948                         if (string == NULL)
 949                                 goto out_nomem;
 950                         mnt->client_address = string;
 951                         break;
 952                 case Opt_mountaddr:
 953                         string = match_strdup(args);
 954                         if (string == NULL)
 955                                 goto out_nomem;
 956                         mnt->mount_server.address.sin_family = AF_INET;
 957                         mnt->mount_server.address.sin_addr.s_addr =
 958                                                         in_aton(string);
 959                         kfree(string);
 960                         break;
 961
 962                 case Opt_userspace:
 963                 case Opt_deprecated:
 964                         break;
 965
 966                 default:
 967                         goto out_unknown;
 968                 }
 969         }
 970
 971         return 1;
 972
 973 out_nomem:
 974         printk(KERN_INFO "NFS: not enough memory to parse option\n");
 975         return 0;
 976
 977 out_unrec_vers:
 978         printk(KERN_INFO "NFS: unrecognized NFS version number\n");
 979         return 0;
 980
 981 out_unrec_xprt:
 982         printk(KERN_INFO "NFS: unrecognized transport protocol\n");
 983         return 0;
 984
 985 out_unrec_sec:
 986         printk(KERN_INFO "NFS: unrecognized security flavor\n");
 987         return 0;
 988
 989 out_unknown:
 990         printk(KERN_INFO "NFS: unknown mount option: %s\n", p);
 991         return 0;
 992 }
 993
 994 /*
 995  * Use the remote server's MOUNT service to request the NFS file handle
 996  * corresponding to the provided path.
 997  */
 998 static int nfs_try_mount(struct nfs_parsed_mount_data *args,
 999                          struct nfs_fh *root_fh)
1000 {
1001         struct sockaddr_in sin;
1002         int status;
1003
1004         if (args->mount_server.version == 0) {
1005                 if (args->flags & NFS_MOUNT_VER3)
1006                         args->mount_server.version = NFS_MNT3_VERSION;
1007                 else
1008                         args->mount_server.version = NFS_MNT_VERSION;
1009         }
1010
1011         /*
1012          * Construct the mount server's address.
1013          */
1014         if (args->mount_server.address.sin_addr.s_addr != INADDR_ANY)
1015                 sin = args->mount_server.address;
1016         else
1017                 sin = args->nfs_server.address;
1018         /*
1019          * autobind will be used if mount_server.port == 0
1020          */
1021         sin.sin_port = htons(args->mount_server.port);
1022
1023         /*
1024          * Now ask the mount server to map our export path
1025          * to a file handle.
1026          */
1027         status = nfs_mount((struct sockaddr *) &sin,
1028                            sizeof(sin),
1029                            args->nfs_server.hostname,
1030                            args->nfs_server.export_path,
1031                            args->mount_server.version,
1032                            args->mount_server.protocol,
1033                            root_fh);
1034         if (status == 0)
1035                 return 0;
1036
1037         dfprintk(MOUNT, "NFS: unable to mount server " NIPQUAD_FMT
1038                         ", error %d\n", NIPQUAD(sin.sin_addr.s_addr), status);
1039         return status;
1040 }
1041
1042 /*
1043  * Validate the NFS2/NFS3 mount data
1044  * - fills in the mount root filehandle
1045  *
1046  * For option strings, user space handles the following behaviors:
1047  *
1048  * + DNS: mapping server host name to IP address ("addr=" option)
1049  *
1050  * + failure mode: how to behave if a mount request can't be handled
1051  *   immediately ("fg/bg" option)
1052  *
1053  * + retry: how often to retry a mount request ("retry=" option)
1054  *
1055  * + breaking back: trying proto=udp after proto=tcp, v2 after v3,
1056  *   mountproto=tcp after mountproto=udp, and so on
1057  */
1058 static int nfs_validate_mount_data(void *options,
1059                                    struct nfs_parsed_mount_data *args,
1060                                    struct nfs_fh *mntfh,
1061                                    const char *dev_name)
1062 {
1063         struct nfs_mount_data *data = (struct nfs_mount_data *)options;
1064
1065         memset(args, 0, sizeof(*args));
1066
1067         if (data == NULL)
1068                 goto out_no_data;
1069
1070         args->flags             = (NFS_MOUNT_VER3 | NFS_MOUNT_TCP);
1071         args->rsize             = NFS_MAX_FILE_IO_SIZE;
1072         args->wsize             = NFS_MAX_FILE_IO_SIZE;
1073         args->timeo             = 600;
1074         args->retrans           = 2;
1075         args->acregmin          = 3;
1076         args->acregmax          = 60;
1077         args->acdirmin          = 30;
1078         args->acdirmax          = 60;
1079         args->mount_server.protocol = XPRT_TRANSPORT_UDP;
1080         args->nfs_server.protocol = XPRT_TRANSPORT_TCP;
1081
1082         switch (data->version) {
1083         case 1:
1084                 data->namlen = 0;
1085         case 2:
1086                 data->bsize = 0;
1087         case 3:
1088                 if (data->flags & NFS_MOUNT_VER3)
1089                         goto out_no_v3;
1090                 data->root.size = NFS2_FHSIZE;
1091                 memcpy(data->root.data, data->old_root.data, NFS2_FHSIZE);
1092         case 4:
1093                 if (data->flags & NFS_MOUNT_SECFLAVOUR)
1094                         goto out_no_sec;
1095         case 5:
1096                 memset(data->context, 0, sizeof(data->context));
1097         case 6:
1098                 if (data->flags & NFS_MOUNT_VER3)
1099                         mntfh->size = data->root.size;
1100                 else
1101                         mntfh->size = NFS2_FHSIZE;
1102
1103                 if (mntfh->size > sizeof(mntfh->data))
1104                         goto out_invalid_fh;
1105
1106                 memcpy(mntfh->data, data->root.data, mntfh->size);
1107                 if (mntfh->size < sizeof(mntfh->data))
1108                         memset(mntfh->data + mntfh->size, 0,
1109                                sizeof(mntfh->data) - mntfh->size);
1110
1111                 if (!nfs_verify_server_address((struct sockaddr *) &data->addr))
1112                         goto out_no_address;
1113
1114                 /*
1115                  * Translate to nfs_parsed_mount_data, which nfs_fill_super
1116                  * can deal with.
1117                  */
1118                 args->flags             = data->flags;
1119                 args->rsize             = data->rsize;
1120                 args->wsize             = data->wsize;
1121                 args->flags             = data->flags;
1122                 args->timeo             = data->timeo;
1123                 args->retrans           = data->retrans;
1124                 args->acregmin          = data->acregmin;
1125                 args->acregmax          = data->acregmax;
1126                 args->acdirmin          = data->acdirmin;
1127                 args->acdirmax          = data->acdirmax;
1128                 args->nfs_server.address = data->addr;
1129                 if (!(data->flags & NFS_MOUNT_TCP))
1130                         args->nfs_server.protocol = XPRT_TRANSPORT_UDP;
1131                 /* N.B. caller will free nfs_server.hostname in all cases */
1132                 args->nfs_server.hostname = kstrdup(data->hostname, GFP_KERNEL);
1133                 args->namlen            = data->namlen;
1134                 args->bsize             = data->bsize;
1135                 args->auth_flavors[0]   = data->pseudoflavor;
1136                 break;
1137         default: {
1138                 unsigned int len;
1139                 char *c;
1140                 int status;
1141
1142                 if (nfs_parse_mount_options((char *)options, args) == 0)
1143                         return -EINVAL;
1144
1145                 if (!nfs_verify_server_address((struct sockaddr *)
1146                                                 &args->nfs_server.address))
1147                         goto out_no_address;
1148
1149                 c = strchr(dev_name, ':');
1150                 if (c == NULL)
1151                         return -EINVAL;
1152                 len = c - dev_name;
1153                 /* N.B. caller will free nfs_server.hostname in all cases */
1154                 args->nfs_server.hostname = kstrndup(dev_name, len, GFP_KERNEL);
1155
1156                 c++;
1157                 if (strlen(c) > NFS_MAXPATHLEN)
1158                         return -ENAMETOOLONG;
1159                 args->nfs_server.export_path = c;
1160
1161                 status = nfs_try_mount(args, mntfh);
1162                 if (status)
1163                         return status;
1164
1165                 break;
1166                 }
1167         }
1168
1169         if (!(args->flags & NFS_MOUNT_SECFLAVOUR))
1170                 args->auth_flavors[0] = RPC_AUTH_UNIX;
1171
1172 #ifndef CONFIG_NFS_V3
1173         if (args->flags & NFS_MOUNT_VER3)
1174                 goto out_v3_not_compiled;
1175 #endif /* !CONFIG_NFS_V3 */
1176
1177         return 0;
1178
1179 out_no_data:
1180         dfprintk(MOUNT, "NFS: mount program didn't pass any mount data\n");
1181         return -EINVAL;
1182
1183 out_no_v3:
1184         dfprintk(MOUNT, "NFS: nfs_mount_data version %d does not support v3\n",
1185                  data->version);
1186         return -EINVAL;
1187
1188 out_no_sec:
1189         dfprintk(MOUNT, "NFS: nfs_mount_data version supports only AUTH_SYS\n");
1190         return -EINVAL;
1191
1192 #ifndef CONFIG_NFS_V3
1193 out_v3_not_compiled:
1194         dfprintk(MOUNT, "NFS: NFSv3 is not compiled into kernel\n");
1195         return -EPROTONOSUPPORT;
1196 #endif /* !CONFIG_NFS_V3 */
1197
1198 out_no_address:
1199         dfprintk(MOUNT, "NFS: mount program didn't pass remote address\n");
1200         return -EINVAL;
1201
1202 out_invalid_fh:
1203         dfprintk(MOUNT, "NFS: invalid root filehandle\n");
1204         return -EINVAL;
1205 }
1206
1207 /*
1208  * Initialise the common bits of the superblock
1209  */
1210 static inline void nfs_initialise_sb(struct super_block *sb)
1211 {
1212         struct nfs_server *server = NFS_SB(sb);
1213
1214         sb->s_magic = NFS_SUPER_MAGIC;
1215
1216         /* We probably want something more informative here */
1217         snprintf(sb->s_id, sizeof(sb->s_id),
1218                  "%x:%x", MAJOR(sb->s_dev), MINOR(sb->s_dev));
1219
1220         if (sb->s_blocksize == 0)
1221                 sb->s_blocksize = nfs_block_bits(server->wsize,
1222                                                  &sb->s_blocksize_bits);
1223
1224         if (server->flags & NFS_MOUNT_NOAC)
1225                 sb->s_flags |= MS_SYNCHRONOUS;
1226
1227         nfs_super_set_maxbytes(sb, server->maxfilesize);
1228 }
1229
1230 /*
1231  * Finish setting up an NFS2/3 superblock
1232  */
1233 static void nfs_fill_super(struct super_block *sb,
1234                            struct nfs_parsed_mount_data *data)
1235 {
1236         struct nfs_server *server = NFS_SB(sb);
1237
1238         sb->s_blocksize_bits = 0;
1239         sb->s_blocksize = 0;
1240         if (data->bsize)
1241                 sb->s_blocksize = nfs_block_size(data->bsize, &sb->s_blocksize_bits);
1242
1243         if (server->flags & NFS_MOUNT_VER3) {
1244                 /* The VFS shouldn't apply the umask to mode bits. We will do
1245                  * so ourselves when necessary.
1246                  */
1247                 sb->s_flags |= MS_POSIXACL;
1248                 sb->s_time_gran = 1;
1249         }
1250
1251         sb->s_op = &nfs_sops;
1252         nfs_initialise_sb(sb);
1253 }
1254
1255 /*
1256  * Finish setting up a cloned NFS2/3 superblock
1257  */
1258 static void nfs_clone_super(struct super_block *sb,
1259                             const struct super_block *old_sb)
1260 {
1261         struct nfs_server *server = NFS_SB(sb);
1262
1263         sb->s_blocksize_bits = old_sb->s_blocksize_bits;
1264         sb->s_blocksize = old_sb->s_blocksize;
1265         sb->s_maxbytes = old_sb->s_maxbytes;
1266
1267         if (server->flags & NFS_MOUNT_VER3) {
1268                 /* The VFS shouldn't apply the umask to mode bits. We will do
1269                  * so ourselves when necessary.
1270                  */
1271                 sb->s_flags |= MS_POSIXACL;
1272                 sb->s_time_gran = 1;
1273         }
1274
1275         sb->s_op = old_sb->s_op;
1276         nfs_initialise_sb(sb);
1277 }
1278
1279 #define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
1280
1281 static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
1282 {
1283         const struct nfs_server *a = s->s_fs_info;
1284         const struct rpc_clnt *clnt_a = a->client;
1285         const struct rpc_clnt *clnt_b = b->client;
1286
1287         if ((s->s_flags & NFS_MS_MASK) != (flags & NFS_MS_MASK))
1288                 goto Ebusy;
1289         if (a->nfs_client != b->nfs_client)
1290                 goto Ebusy;
1291         if (a->flags != b->flags)
1292                 goto Ebusy;
1293         if (a->wsize != b->wsize)
1294                 goto Ebusy;
1295         if (a->rsize != b->rsize)
1296                 goto Ebusy;
1297         if (a->acregmin != b->acregmin)
1298                 goto Ebusy;
1299         if (a->acregmax != b->acregmax)
1300                 goto Ebusy;
1301         if (a->acdirmin != b->acdirmin)
1302                 goto Ebusy;
1303         if (a->acdirmax != b->acdirmax)
1304                 goto Ebusy;
1305         if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
1306                 goto Ebusy;
1307         return 1;
1308 Ebusy:
1309         return 0;
1310 }
1311
1312 struct nfs_sb_mountdata {
1313         struct nfs_server *server;
1314         int mntflags;
1315 };
1316
1317 static int nfs_set_super(struct super_block *s, void *data)
1318 {
1319         struct nfs_sb_mountdata *sb_mntdata = data;
1320         struct nfs_server *server = sb_mntdata->server;
1321         int ret;
1322
1323         s->s_flags = sb_mntdata->mntflags;
1324         s->s_fs_info = server;
1325         ret = set_anon_super(s, server);
1326         if (ret == 0)
1327                 server->s_dev = s->s_dev;
1328         return ret;
1329 }
1330
1331 static int nfs_compare_super_address(struct nfs_server *server1,
1332                                      struct nfs_server *server2)
1333 {
1334         struct sockaddr *sap1, *sap2;
1335
1336         sap1 = (struct sockaddr *)&server1->nfs_client->cl_addr;
1337         sap2 = (struct sockaddr *)&server2->nfs_client->cl_addr;
1338
1339         if (sap1->sa_family != sap2->sa_family)
1340                 return 0;
1341
1342         switch (sap1->sa_family) {
1343         case AF_INET: {
1344                 struct sockaddr_in *sin1 = (struct sockaddr_in *)sap1;
1345                 struct sockaddr_in *sin2 = (struct sockaddr_in *)sap2;
1346                 if (sin1->sin_addr.s_addr != sin2->sin_addr.s_addr)
1347                         return 0;
1348                 if (sin1->sin_port != sin2->sin_port)
1349                         return 0;
1350                 break;
1351         }
1352         case AF_INET6: {
1353                 struct sockaddr_in6 *sin1 = (struct sockaddr_in6 *)sap1;
1354                 struct sockaddr_in6 *sin2 = (struct sockaddr_in6 *)sap2;
1355                 if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
1356                         return 0;
1357                 if (sin1->sin6_port != sin2->sin6_port)
1358                         return 0;
1359                 break;
1360         }
1361         default:
1362                 return 0;
1363         }
1364
1365         return 1;
1366 }
1367
1368 static int nfs_compare_super(struct super_block *sb, void *data)
1369 {
1370         struct nfs_sb_mountdata *sb_mntdata = data;
1371         struct nfs_server *server = sb_mntdata->server, *old = NFS_SB(sb);
1372         int mntflags = sb_mntdata->mntflags;
1373
1374         if (!nfs_compare_super_address(old, server))
1375                 return 0;
1376         /* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
1377         if (old->flags & NFS_MOUNT_UNSHARED)
1378                 return 0;
1379         if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
1380                 return 0;
1381         return nfs_compare_mount_options(sb, server, mntflags);
1382 }
1383
1384 static int nfs_get_sb(struct file_system_type *fs_type,
1385         int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
1386 {
1387         struct nfs_server *server = NULL;
1388         struct super_block *s;
1389         struct nfs_fh mntfh;
1390         struct nfs_parsed_mount_data data;
1391         struct dentry *mntroot;
1392         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
1393         struct nfs_sb_mountdata sb_mntdata = {
1394                 .mntflags = flags,
1395         };
1396         int error;
1397
1398         /* Validate the mount data */
1399         error = nfs_validate_mount_data(raw_data, &data, &mntfh, dev_name);
1400         if (error < 0)
1401                 goto out;
1402
1403         /* Get a volume representation */
1404         server = nfs_create_server(&data, &mntfh);
1405         if (IS_ERR(server)) {
1406                 error = PTR_ERR(server);
1407                 goto out;
1408         }
1409         sb_mntdata.server = server;
1410
1411         if (server->flags & NFS_MOUNT_UNSHARED)
1412                 compare_super = NULL;
1413
1414         /* Get a superblock - note that we may end up sharing one that already exists */
1415         s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);
1416         if (IS_ERR(s)) {
1417                 error = PTR_ERR(s);
1418                 goto out_err_nosb;
1419         }
1420
1421         if (s->s_fs_info != server) {
1422                 nfs_free_server(server);
1423                 server = NULL;
1424         }
1425
1426         if (!s->s_root) {
1427                 /* initial superblock/root creation */
1428                 nfs_fill_super(s, &data);
1429         }
1430
1431         mntroot = nfs_get_root(s, &mntfh);
1432         if (IS_ERR(mntroot)) {
1433                 error = PTR_ERR(mntroot);
1434                 goto error_splat_super;
1435         }
1436
1437         s->s_flags |= MS_ACTIVE;
1438         mnt->mnt_sb = s;
1439         mnt->mnt_root = mntroot;
1440         error = 0;
1441
1442 out:
1443         kfree(data.nfs_server.hostname);
1444         return error;
1445
1446 out_err_nosb:
1447         nfs_free_server(server);
1448         goto out;
1449
1450 error_splat_super:
1451         up_write(&s->s_umount);
1452         deactivate_super(s);
1453         goto out;
1454 }
1455
1456 /*
1457  * Destroy an NFS2/3 superblock
1458  */
1459 static void nfs_kill_super(struct super_block *s)
1460 {
1461         struct nfs_server *server = NFS_SB(s);
1462
1463         kill_anon_super(s);
1464         nfs_free_server(server);
1465 }
1466
1467 /*
1468  * Clone an NFS2/3 server record on xdev traversal (FSID-change)
1469  */
1470 static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags,
1471                            const char *dev_name, void *raw_data,
1472                            struct vfsmount *mnt)
1473 {
1474         struct nfs_clone_mount *data = raw_data;
1475         struct super_block *s;
1476         struct nfs_server *server;
1477         struct dentry *mntroot;
1478         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
1479         struct nfs_sb_mountdata sb_mntdata = {
1480                 .mntflags = flags,
1481         };
1482         int error;
1483
1484         dprintk("--> nfs_xdev_get_sb()\n");
1485
1486         /* create a new volume representation */
1487         server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
1488         if (IS_ERR(server)) {
1489                 error = PTR_ERR(server);
1490                 goto out_err_noserver;
1491         }
1492         sb_mntdata.server = server;
1493
1494         if (server->flags & NFS_MOUNT_UNSHARED)
1495                 compare_super = NULL;
1496
1497         /* Get a superblock - note that we may end up sharing one that already exists */
1498         s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);
1499         if (IS_ERR(s)) {
1500                 error = PTR_ERR(s);
1501                 goto out_err_nosb;
1502         }
1503
1504         if (s->s_fs_info != server) {
1505                 nfs_free_server(server);
1506                 server = NULL;
1507         }
1508
1509         if (!s->s_root) {
1510                 /* initial superblock/root creation */
1511                 nfs_clone_super(s, data->sb);
1512         }
1513
1514         mntroot = nfs_get_root(s, data->fh);
1515         if (IS_ERR(mntroot)) {
1516                 error = PTR_ERR(mntroot);
1517                 goto error_splat_super;
1518         }
1519         if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
1520                 dput(mntroot);
1521                 error = -ESTALE;
1522                 goto error_splat_super;
1523         }
1524
1525         s->s_flags |= MS_ACTIVE;
1526         mnt->mnt_sb = s;
1527         mnt->mnt_root = mntroot;
1528
1529         dprintk("<-- nfs_xdev_get_sb() = 0\n");
1530         return 0;
1531
1532 out_err_nosb:
1533         nfs_free_server(server);
1534 out_err_noserver:
1535         dprintk("<-- nfs_xdev_get_sb() = %d [error]\n", error);
1536         return error;
1537
1538 error_splat_super:
1539         up_write(&s->s_umount);
1540         deactivate_super(s);
1541         dprintk("<-- nfs_xdev_get_sb() = %d [splat]\n", error);
1542         return error;
1543 }
1544
1545 #ifdef CONFIG_NFS_V4
1546
1547 /*
1548  * Finish setting up a cloned NFS4 superblock
1549  */
1550 static void nfs4_clone_super(struct super_block *sb,
1551                             const struct super_block *old_sb)
1552 {
1553         sb->s_blocksize_bits = old_sb->s_blocksize_bits;
1554         sb->s_blocksize = old_sb->s_blocksize;
1555         sb->s_maxbytes = old_sb->s_maxbytes;
1556         sb->s_time_gran = 1;
1557         sb->s_op = old_sb->s_op;
1558         nfs_initialise_sb(sb);
1559 }
1560
1561 /*
1562  * Set up an NFS4 superblock
1563  */
1564 static void nfs4_fill_super(struct super_block *sb)
1565 {
1566         sb->s_time_gran = 1;
1567         sb->s_op = &nfs4_sops;
1568         nfs_initialise_sb(sb);
1569 }
1570
1571 /*
1572  * Validate NFSv4 mount options
1573  */
1574 static int nfs4_validate_mount_data(void *options,
1575                                     struct nfs_parsed_mount_data *args,
1576                                     const char *dev_name)
1577 {
1578         struct nfs4_mount_data *data = (struct nfs4_mount_data *)options;
1579         char *c;
1580
1581         memset(args, 0, sizeof(*args));
1582
1583         if (data == NULL)
1584                 goto out_no_data;
1585
1586         args->rsize             = NFS_MAX_FILE_IO_SIZE;
1587         args->wsize             = NFS_MAX_FILE_IO_SIZE;
1588         args->timeo             = 600;
1589         args->retrans           = 2;
1590         args->acregmin          = 3;
1591         args->acregmax          = 60;
1592         args->acdirmin          = 30;
1593         args->acdirmax          = 60;
1594         args->nfs_server.protocol = XPRT_TRANSPORT_TCP;
1595
1596         switch (data->version) {
1597         case 1:
1598                 if (data->host_addrlen != sizeof(args->nfs_server.address))
1599                         goto out_no_address;
1600                 if (copy_from_user(&args->nfs_server.address,
1601                                    data->host_addr,
1602                                    sizeof(args->nfs_server.address)))
1603                         return -EFAULT;
1604                 if (args->nfs_server.address.sin_port == 0)
1605                         args->nfs_server.address.sin_port = htons(NFS_PORT);
1606                 if (!nfs_verify_server_address((struct sockaddr *)
1607                                                 &args->nfs_server.address))
1608                         goto out_no_address;
1609
1610                 switch (data->auth_flavourlen) {
1611                 case 0:
1612                         args->auth_flavors[0] = RPC_AUTH_UNIX;
1613                         break;
1614                 case 1:
1615                         if (copy_from_user(&args->auth_flavors[0],
1616                                            data->auth_flavours,
1617                                            sizeof(args->auth_flavors[0])))
1618                                 return -EFAULT;
1619                         break;
1620                 default:
1621                         goto out_inval_auth;
1622                 }
1623
1624                 c = strndup_user(data->hostname.data, NFS4_MAXNAMLEN);
1625                 if (IS_ERR(c))
1626                         return PTR_ERR(c);
1627                 args->nfs_server.hostname = c;
1628
1629                 c = strndup_user(data->mnt_path.data, NFS4_MAXPATHLEN);
1630                 if (IS_ERR(c))
1631                         return PTR_ERR(c);
1632                 args->nfs_server.export_path = c;
1633                 dfprintk(MOUNT, "NFS: MNTPATH: '%s'\n", c);
1634
1635                 c = strndup_user(data->client_addr.data, 16);
1636                 if (IS_ERR(c))
1637                         return PTR_ERR(c);
1638                 args->client_address = c;
1639
1640                 /*
1641                  * Translate to nfs_parsed_mount_data, which nfs4_fill_super
1642                  * can deal with.
1643                  */
1644
1645                 args->flags     = data->flags & NFS4_MOUNT_FLAGMASK;
1646                 args->rsize     = data->rsize;
1647                 args->wsize     = data->wsize;
1648                 args->timeo     = data->timeo;
1649                 args->retrans   = data->retrans;
1650                 args->acregmin  = data->acregmin;
1651                 args->acregmax  = data->acregmax;
1652                 args->acdirmin  = data->acdirmin;
1653                 args->acdirmax  = data->acdirmax;
1654                 args->nfs_server.protocol = data->proto;
1655
1656                 break;
1657         default: {
1658                 unsigned int len;
1659
1660                 if (nfs_parse_mount_options((char *)options, args) == 0)
1661                         return -EINVAL;
1662
1663                 if (args->nfs_server.address.sin_port == 0)
1664                         args->nfs_server.address.sin_port = htons(NFS_PORT);
1665                 if (!nfs_verify_server_address((struct sockaddr *)
1666                                                 &args->nfs_server.address))
1667                         return -EINVAL;
1668
1669                 switch (args->auth_flavor_len) {
1670                 case 0:
1671                         args->auth_flavors[0] = RPC_AUTH_UNIX;
1672                         break;
1673                 case 1:
1674                         break;
1675                 default:
1676                         goto out_inval_auth;
1677                 }
1678
1679                 /*
1680                  * Split "dev_name" into "hostname:mntpath".
1681                  */
1682                 c = strchr(dev_name, ':');
1683                 if (c == NULL)
1684                         return -EINVAL;
1685                 /* while calculating len, pretend ':' is '\0' */
1686                 len = c - dev_name;
1687                 if (len > NFS4_MAXNAMLEN)
1688                         return -ENAMETOOLONG;
1689                 /* N.B. caller will free nfs_server.hostname in all cases */
1690                 args->nfs_server.hostname = kstrndup(dev_name, len, GFP_KERNEL);
1691
1692                 c++;                    /* step over the ':' */
1693                 len = strlen(c);
1694                 if (len > NFS4_MAXPATHLEN)
1695                         return -ENAMETOOLONG;
1696                 args->nfs_server.export_path = kstrndup(c, len, GFP_KERNEL);
1697
1698                 dprintk("NFS: MNTPATH: '%s'\n", args->nfs_server.export_path);
1699
1700                 if (args->client_address == NULL)
1701                         goto out_no_client_address;
1702
1703                 break;
1704                 }
1705         }
1706
1707         return 0;
1708
1709 out_no_data:
1710         dfprintk(MOUNT, "NFS4: mount program didn't pass any mount data\n");
1711         return -EINVAL;
1712
1713 out_inval_auth:
1714         dfprintk(MOUNT, "NFS4: Invalid number of RPC auth flavours %d\n",
1715                  data->auth_flavourlen);
1716         return -EINVAL;
1717
1718 out_no_address:
1719         dfprintk(MOUNT, "NFS4: mount program didn't pass remote address\n");
1720         return -EINVAL;
1721
1722 out_no_client_address:
1723         dfprintk(MOUNT, "NFS4: mount program didn't pass callback address\n");
1724         return -EINVAL;
1725 }
1726
1727 /*
1728  * Get the superblock for an NFS4 mountpoint
1729  */
1730 static int nfs4_get_sb(struct file_system_type *fs_type,
1731         int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
1732 {
1733         struct nfs_parsed_mount_data data;
1734         struct super_block *s;
1735         struct nfs_server *server;
1736         struct nfs_fh mntfh;
1737         struct dentry *mntroot;
1738         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
1739         struct nfs_sb_mountdata sb_mntdata = {
1740                 .mntflags = flags,
1741         };
1742         int error;
1743
1744         /* Validate the mount data */
1745         error = nfs4_validate_mount_data(raw_data, &data, dev_name);
1746         if (error < 0)
1747                 goto out;
1748
1749         /* Get a volume representation */
1750         server = nfs4_create_server(&data, &mntfh);
1751         if (IS_ERR(server)) {
1752                 error = PTR_ERR(server);
1753                 goto out;
1754         }
1755         sb_mntdata.server = server;
1756
1757         if (server->flags & NFS4_MOUNT_UNSHARED)
1758                 compare_super = NULL;
1759
1760         /* Get a superblock - note that we may end up sharing one that already exists */
1761         s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);
1762         if (IS_ERR(s)) {
1763                 error = PTR_ERR(s);
1764                 goto out_free;
1765         }
1766
1767         if (s->s_fs_info != server) {
1768                 nfs_free_server(server);
1769                 server = NULL;
1770         }
1771
1772         if (!s->s_root) {
1773                 /* initial superblock/root creation */
1774                 nfs4_fill_super(s);
1775         }
1776
1777         mntroot = nfs4_get_root(s, &mntfh);
1778         if (IS_ERR(mntroot)) {
1779                 error = PTR_ERR(mntroot);
1780                 goto error_splat_super;
1781         }
1782
1783         s->s_flags |= MS_ACTIVE;
1784         mnt->mnt_sb = s;
1785         mnt->mnt_root = mntroot;
1786         error = 0;
1787
1788 out:
1789         kfree(data.client_address);
1790         kfree(data.nfs_server.export_path);
1791         kfree(data.nfs_server.hostname);
1792         return error;
1793
1794 out_free:
1795         nfs_free_server(server);
1796         goto out;
1797
1798 error_splat_super:
1799         up_write(&s->s_umount);
1800         deactivate_super(s);
1801         goto out;
1802 }
1803
1804 static void nfs4_kill_super(struct super_block *sb)
1805 {
1806         struct nfs_server *server = NFS_SB(sb);
1807
1808         nfs_return_all_delegations(sb);
1809         kill_anon_super(sb);
1810
1811         nfs4_renewd_prepare_shutdown(server);
1812         nfs_free_server(server);
1813 }
1814
1815 /*
1816  * Clone an NFS4 server record on xdev traversal (FSID-change)
1817  */
1818 static int nfs4_xdev_get_sb(struct file_system_type *fs_type, int flags,
1819                             const char *dev_name, void *raw_data,
1820                             struct vfsmount *mnt)
1821 {
1822         struct nfs_clone_mount *data = raw_data;
1823         struct super_block *s;
1824         struct nfs_server *server;
1825         struct dentry *mntroot;
1826         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
1827         struct nfs_sb_mountdata sb_mntdata = {
1828                 .mntflags = flags,
1829         };
1830         int error;
1831
1832         dprintk("--> nfs4_xdev_get_sb()\n");
1833
1834         /* create a new volume representation */
1835         server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
1836         if (IS_ERR(server)) {
1837                 error = PTR_ERR(server);
1838                 goto out_err_noserver;
1839         }
1840         sb_mntdata.server = server;
1841
1842         if (server->flags & NFS4_MOUNT_UNSHARED)
1843                 compare_super = NULL;
1844
1845         /* Get a superblock - note that we may end up sharing one that already exists */
1846         s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);
1847         if (IS_ERR(s)) {
1848                 error = PTR_ERR(s);
1849                 goto out_err_nosb;
1850         }
1851
1852         if (s->s_fs_info != server) {
1853                 nfs_free_server(server);
1854                 server = NULL;
1855         }
1856
1857         if (!s->s_root) {
1858                 /* initial superblock/root creation */
1859                 nfs4_clone_super(s, data->sb);
1860         }
1861
1862         mntroot = nfs4_get_root(s, data->fh);
1863         if (IS_ERR(mntroot)) {
1864                 error = PTR_ERR(mntroot);
1865                 goto error_splat_super;
1866         }
1867         if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
1868                 dput(mntroot);
1869                 error = -ESTALE;
1870                 goto error_splat_super;
1871         }
1872
1873         s->s_flags |= MS_ACTIVE;
1874         mnt->mnt_sb = s;
1875         mnt->mnt_root = mntroot;
1876
1877         dprintk("<-- nfs4_xdev_get_sb() = 0\n");
1878         return 0;
1879
1880 out_err_nosb:
1881         nfs_free_server(server);
1882 out_err_noserver:
1883         dprintk("<-- nfs4_xdev_get_sb() = %d [error]\n", error);
1884         return error;
1885
1886 error_splat_super:
1887         up_write(&s->s_umount);
1888         deactivate_super(s);
1889         dprintk("<-- nfs4_xdev_get_sb() = %d [splat]\n", error);
1890         return error;
1891 }
1892
1893 /*
1894  * Create an NFS4 server record on referral traversal
1895  */
1896 static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags,
1897                                 const char *dev_name, void *raw_data,
1898                                 struct vfsmount *mnt)
1899 {
1900         struct nfs_clone_mount *data = raw_data;
1901         struct super_block *s;
1902         struct nfs_server *server;
1903         struct dentry *mntroot;
1904         struct nfs_fh mntfh;
1905         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
1906         struct nfs_sb_mountdata sb_mntdata = {
1907                 .mntflags = flags,
1908         };
1909         int error;
1910
1911         dprintk("--> nfs4_referral_get_sb()\n");
1912
1913         /* create a new volume representation */
1914         server = nfs4_create_referral_server(data, &mntfh);
1915         if (IS_ERR(server)) {
1916                 error = PTR_ERR(server);
1917                 goto out_err_noserver;
1918         }
1919         sb_mntdata.server = server;
1920
1921         if (server->flags & NFS4_MOUNT_UNSHARED)
1922                 compare_super = NULL;
1923
1924         /* Get a superblock - note that we may end up sharing one that already exists */
1925         s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);
1926         if (IS_ERR(s)) {
1927                 error = PTR_ERR(s);
1928                 goto out_err_nosb;
1929         }
1930
1931         if (s->s_fs_info != server) {
1932                 nfs_free_server(server);
1933                 server = NULL;
1934         }
1935
1936         if (!s->s_root) {
1937                 /* initial superblock/root creation */
1938                 nfs4_fill_super(s);
1939         }
1940
1941         mntroot = nfs4_get_root(s, &mntfh);
1942         if (IS_ERR(mntroot)) {
1943                 error = PTR_ERR(mntroot);
1944                 goto error_splat_super;
1945         }
1946         if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
1947                 dput(mntroot);
1948                 error = -ESTALE;
1949                 goto error_splat_super;
1950         }
1951
1952         s->s_flags |= MS_ACTIVE;
1953         mnt->mnt_sb = s;
1954         mnt->mnt_root = mntroot;
1955
1956         dprintk("<-- nfs4_referral_get_sb() = 0\n");
1957         return 0;
1958
1959 out_err_nosb:
1960         nfs_free_server(server);
1961 out_err_noserver:
1962         dprintk("<-- nfs4_referral_get_sb() = %d [error]\n", error);
1963         return error;
1964
1965 error_splat_super:
1966         up_write(&s->s_umount);
1967         deactivate_super(s);
1968         dprintk("<-- nfs4_referral_get_sb() = %d [splat]\n", error);
1969         return error;
1970 }
1971
1972 #endif /* CONFIG_NFS_V4 */