Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland...
[pandora-kernel.git] / fs / nfs / super.c
index d2d6778..0b4cbdc 100644 (file)
@@ -42,6 +42,8 @@
 #include <linux/smp_lock.h>
 #include <linux/seq_file.h>
 #include <linux/mount.h>
+#include <linux/mnt_namespace.h>
+#include <linux/namei.h>
 #include <linux/nfs_idmap.h>
 #include <linux/vfs.h>
 #include <linux/inet.h>
@@ -90,6 +92,7 @@ enum {
        Opt_mountport,
        Opt_mountvers,
        Opt_nfsvers,
+       Opt_minorversion,
 
        /* Mount options that take string arguments */
        Opt_sec, Opt_proto, Opt_mountproto, Opt_mounthost,
@@ -139,22 +142,23 @@ static const match_table_t nfs_mount_option_tokens = {
        { Opt_fscache_uniq, "fsc=%s" },
        { Opt_nofscache, "nofsc" },
 
-       { Opt_port, "port=%u" },
-       { Opt_rsize, "rsize=%u" },
-       { Opt_wsize, "wsize=%u" },
-       { Opt_bsize, "bsize=%u" },
-       { Opt_timeo, "timeo=%u" },
-       { Opt_retrans, "retrans=%u" },
-       { Opt_acregmin, "acregmin=%u" },
-       { Opt_acregmax, "acregmax=%u" },
-       { Opt_acdirmin, "acdirmin=%u" },
-       { Opt_acdirmax, "acdirmax=%u" },
-       { Opt_actimeo, "actimeo=%u" },
-       { Opt_namelen, "namlen=%u" },
-       { Opt_mountport, "mountport=%u" },
-       { Opt_mountvers, "mountvers=%u" },
-       { Opt_nfsvers, "nfsvers=%u" },
-       { Opt_nfsvers, "vers=%u" },
+       { Opt_port, "port=%s" },
+       { Opt_rsize, "rsize=%s" },
+       { Opt_wsize, "wsize=%s" },
+       { Opt_bsize, "bsize=%s" },
+       { Opt_timeo, "timeo=%s" },
+       { Opt_retrans, "retrans=%s" },
+       { Opt_acregmin, "acregmin=%s" },
+       { Opt_acregmax, "acregmax=%s" },
+       { Opt_acdirmin, "acdirmin=%s" },
+       { Opt_acdirmax, "acdirmax=%s" },
+       { Opt_actimeo, "actimeo=%s" },
+       { Opt_namelen, "namlen=%s" },
+       { Opt_mountport, "mountport=%s" },
+       { Opt_mountvers, "mountvers=%s" },
+       { Opt_nfsvers, "nfsvers=%s" },
+       { Opt_nfsvers, "vers=%s" },
+       { Opt_minorversion, "minorversion=%u" },
 
        { Opt_sec, "sec=%s" },
        { Opt_proto, "proto=%s" },
@@ -270,10 +274,14 @@ static const struct super_operations nfs_sops = {
 #ifdef CONFIG_NFS_V4
 static int nfs4_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
+static int nfs4_remote_get_sb(struct file_system_type *fs_type,
+       int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 static int nfs4_xdev_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 static int nfs4_referral_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
+static int nfs4_remote_referral_get_sb(struct file_system_type *fs_type,
+       int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 static void nfs4_kill_super(struct super_block *sb);
 
 static struct file_system_type nfs4_fs_type = {
@@ -284,6 +292,14 @@ static struct file_system_type nfs4_fs_type = {
        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 };
 
+static struct file_system_type nfs4_remote_fs_type = {
+       .owner          = THIS_MODULE,
+       .name           = "nfs4",
+       .get_sb         = nfs4_remote_get_sb,
+       .kill_sb        = nfs4_kill_super,
+       .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
 struct file_system_type nfs4_xdev_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs4",
@@ -292,6 +308,14 @@ struct file_system_type nfs4_xdev_fs_type = {
        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
 };
 
+static struct file_system_type nfs4_remote_referral_fs_type = {
+       .owner          = THIS_MODULE,
+       .name           = "nfs4",
+       .get_sb         = nfs4_remote_referral_get_sb,
+       .kill_sb        = nfs4_kill_super,
+       .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
 struct file_system_type nfs4_referral_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs4",
@@ -514,7 +538,6 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
                const char *nostr;
        } nfs_info[] = {
                { NFS_MOUNT_SOFT, ",soft", ",hard" },
-               { NFS_MOUNT_INTR, ",intr", ",nointr" },
                { NFS_MOUNT_POSIX, ",posix", "" },
                { NFS_MOUNT_NOCTO, ",nocto", "" },
                { NFS_MOUNT_NOAC, ",noac", "" },
@@ -943,11 +966,6 @@ static int nfs_parse_security_flavors(char *value,
        return 1;
 }
 
-static void nfs_parse_invalid_value(const char *option)
-{
-       dfprintk(MOUNT, "NFS:   bad value specified for %s option\n", option);
-}
-
 /*
  * Error-check and convert a string of mount options from user space into
  * a data structure.  The whole mount string is processed; bad options are
@@ -958,7 +976,7 @@ static int nfs_parse_mount_options(char *raw,
                                   struct nfs_parsed_mount_data *mnt)
 {
        char *p, *string, *secdata;
-       int rc, sloppy = 0, errors = 0;
+       int rc, sloppy = 0, invalid_option = 0;
 
        if (!raw) {
                dfprintk(MOUNT, "NFS: mount options string was NULL.\n");
@@ -982,7 +1000,9 @@ static int nfs_parse_mount_options(char *raw,
 
        while ((p = strsep(&raw, ",")) != NULL) {
                substring_t args[MAX_OPT_ARGS];
-               int option, token;
+               unsigned long option;
+               int int_option;
+               int token;
 
                if (!*p)
                        continue;
@@ -1091,114 +1111,156 @@ static int nfs_parse_mount_options(char *raw,
                 * options that take numeric values
                 */
                case Opt_port:
-                       if (match_int(args, &option) ||
-                           option < 0 || option > USHORT_MAX) {
-                               errors++;
-                               nfs_parse_invalid_value("port");
-                       } else
-                               mnt->nfs_server.port = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0 || option > USHORT_MAX)
+                               goto out_invalid_value;
+                       mnt->nfs_server.port = option;
                        break;
                case Opt_rsize:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("rsize");
-                       } else
-                               mnt->rsize = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->rsize = option;
                        break;
                case Opt_wsize:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("wsize");
-                       } else
-                               mnt->wsize = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->wsize = option;
                        break;
                case Opt_bsize:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("bsize");
-                       } else
-                               mnt->bsize = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->bsize = option;
                        break;
                case Opt_timeo:
-                       if (match_int(args, &option) || option <= 0) {
-                               errors++;
-                               nfs_parse_invalid_value("timeo");
-                       } else
-                               mnt->timeo = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0 || option == 0)
+                               goto out_invalid_value;
+                       mnt->timeo = option;
                        break;
                case Opt_retrans:
-                       if (match_int(args, &option) || option <= 0) {
-                               errors++;
-                               nfs_parse_invalid_value("retrans");
-                       } else
-                               mnt->retrans = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0 || option == 0)
+                               goto out_invalid_value;
+                       mnt->retrans = option;
                        break;
                case Opt_acregmin:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("acregmin");
-                       } else
-                               mnt->acregmin = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->acregmin = option;
                        break;
                case Opt_acregmax:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("acregmax");
-                       } else
-                               mnt->acregmax = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->acregmax = option;
                        break;
                case Opt_acdirmin:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("acdirmin");
-                       } else
-                               mnt->acdirmin = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->acdirmin = option;
                        break;
                case Opt_acdirmax:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("acdirmax");
-                       } else
-                               mnt->acdirmax = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->acdirmax = option;
                        break;
                case Opt_actimeo:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("actimeo");
-                       } else
-                               mnt->acregmin = mnt->acregmax =
-                               mnt->acdirmin = mnt->acdirmax = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->acregmin = mnt->acregmax =
+                       mnt->acdirmin = mnt->acdirmax = option;
                        break;
                case Opt_namelen:
-                       if (match_int(args, &option) || option < 0) {
-                               errors++;
-                               nfs_parse_invalid_value("namlen");
-                       } else
-                               mnt->namlen = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
+                       mnt->namlen = option;
                        break;
                case Opt_mountport:
-                       if (match_int(args, &option) ||
-                           option < 0 || option > USHORT_MAX) {
-                               errors++;
-                               nfs_parse_invalid_value("mountport");
-                       } else
-                               mnt->mount_server.port = option;
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0 || option > USHORT_MAX)
+                               goto out_invalid_value;
+                       mnt->mount_server.port = option;
                        break;
                case Opt_mountvers:
-                       if (match_int(args, &option) ||
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0 ||
                            option < NFS_MNT_VERSION ||
-                           option > NFS_MNT3_VERSION) {
-                               errors++;
-                               nfs_parse_invalid_value("mountvers");
-                       } else
-                               mnt->mount_server.version = option;
+                           option > NFS_MNT3_VERSION)
+                               goto out_invalid_value;
+                       mnt->mount_server.version = option;
                        break;
                case Opt_nfsvers:
-                       if (match_int(args, &option)) {
-                               errors++;
-                               nfs_parse_invalid_value("nfsvers");
-                               break;
-                       }
+                       string = match_strdup(args);
+                       if (string == NULL)
+                               goto out_nomem;
+                       rc = strict_strtoul(string, 10, &option);
+                       kfree(string);
+                       if (rc != 0)
+                               goto out_invalid_value;
                        switch (option) {
                        case NFS2_VERSION:
                                mnt->flags &= ~NFS_MOUNT_VER3;
@@ -1207,10 +1269,16 @@ static int nfs_parse_mount_options(char *raw,
                                mnt->flags |= NFS_MOUNT_VER3;
                                break;
                        default:
-                               errors++;
-                               nfs_parse_invalid_value("nfsvers");
+                               goto out_invalid_value;
                        }
                        break;
+               case Opt_minorversion:
+                       if (match_int(args, &int_option))
+                               return 0;
+                       if (int_option < 0 || int_option > NFS4_MAX_MINOR_VERSION)
+                               return 0;
+                       mnt->minorversion = int_option;
+                       break;
 
                /*
                 * options that take text values
@@ -1222,9 +1290,9 @@ static int nfs_parse_mount_options(char *raw,
                        rc = nfs_parse_security_flavors(string, mnt);
                        kfree(string);
                        if (!rc) {
-                               errors++;
                                dfprintk(MOUNT, "NFS:   unrecognized "
                                                "security flavor\n");
+                               return 0;
                        }
                        break;
                case Opt_proto:
@@ -1238,23 +1306,25 @@ static int nfs_parse_mount_options(char *raw,
                        case Opt_xprt_udp:
                                mnt->flags &= ~NFS_MOUNT_TCP;
                                mnt->nfs_server.protocol = XPRT_TRANSPORT_UDP;
+                               kfree(string);
                                break;
                        case Opt_xprt_tcp:
                                mnt->flags |= NFS_MOUNT_TCP;
                                mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
+                               kfree(string);
                                break;
                        case Opt_xprt_rdma:
                                /* vector side protocols to TCP */
                                mnt->flags |= NFS_MOUNT_TCP;
                                mnt->nfs_server.protocol = XPRT_TRANSPORT_RDMA;
                                xprt_load_transport(string);
+                               kfree(string);
                                break;
                        default:
-                               errors++;
                                dfprintk(MOUNT, "NFS:   unrecognized "
                                                "transport protocol\n");
+                               return 0;
                        }
-                       kfree(string);
                        break;
                case Opt_mountproto:
                        string = match_strdup(args);
@@ -1273,9 +1343,9 @@ static int nfs_parse_mount_options(char *raw,
                                break;
                        case Opt_xprt_rdma: /* not used for side protocols */
                        default:
-                               errors++;
                                dfprintk(MOUNT, "NFS:   unrecognized "
                                                "transport protocol\n");
+                               return 0;
                        }
                        break;
                case Opt_addr:
@@ -1331,9 +1401,9 @@ static int nfs_parse_mount_options(char *raw,
                                        mnt->flags |= NFS_MOUNT_LOOKUP_CACHE_NONEG|NFS_MOUNT_LOOKUP_CACHE_NONE;
                                        break;
                                default:
-                                       errors++;
                                        dfprintk(MOUNT, "NFS:   invalid "
                                                        "lookupcache argument\n");
+                                       return 0;
                        };
                        break;
 
@@ -1351,20 +1421,20 @@ static int nfs_parse_mount_options(char *raw,
                        break;
 
                default:
-                       errors++;
+                       invalid_option = 1;
                        dfprintk(MOUNT, "NFS:   unrecognized mount option "
                                        "'%s'\n", p);
                }
        }
 
-       if (errors > 0) {
-               dfprintk(MOUNT, "NFS: parsing encountered %d error%s\n",
-                               errors, (errors == 1 ? "" : "s"));
-               if (!sloppy)
-                       return 0;
-       }
+       if (!sloppy && invalid_option)
+               return 0;
+
        return 1;
 
+out_invalid_value:
+       printk(KERN_INFO "NFS: bad mount option value specified: %s \n", p);
+       return 0;
 out_nomem:
        printk(KERN_INFO "NFS: not enough memory to parse option\n");
        return 0;
@@ -1381,6 +1451,7 @@ out_security_failure:
 static int nfs_try_mount(struct nfs_parsed_mount_data *args,
                         struct nfs_fh *root_fh)
 {
+       unsigned int auth_flavor_len = 0;
        struct nfs_mount_request request = {
                .sap            = (struct sockaddr *)
                                                &args->mount_server.address,
@@ -1388,6 +1459,7 @@ static int nfs_try_mount(struct nfs_parsed_mount_data *args,
                .protocol       = args->mount_server.protocol,
                .fh             = root_fh,
                .noresvport     = args->flags & NFS_MOUNT_NORESVPORT,
+               .auth_flav_len  = &auth_flavor_len,
        };
        int status;
 
@@ -1813,6 +1885,7 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
        if (data == NULL)
                return -ENOMEM;
 
+       lock_kernel();
        /* fill out struct with values from existing mount */
        data->flags = nfss->flags;
        data->rsize = nfss->rsize;
@@ -1837,6 +1910,7 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
        error = nfs_compare_remount_data(nfss, data);
 out:
        kfree(data);
+       unlock_kernel();
        return error;
 }
 
@@ -2238,6 +2312,11 @@ static void nfs4_fill_super(struct super_block *sb)
        nfs_initialise_sb(sb);
 }
 
+static void nfs4_validate_mount_flags(struct nfs_parsed_mount_data *args)
+{
+       args->flags &= ~(NFS_MOUNT_NONLM|NFS_MOUNT_NOACL|NFS_MOUNT_VER3);
+}
+
 /*
  * Validate NFSv4 mount options
  */
@@ -2261,6 +2340,7 @@ static int nfs4_validate_mount_data(void *options,
        args->nfs_server.port   = NFS_PORT; /* 2049 unless user set port= */
        args->auth_flavors[0]   = RPC_AUTH_UNIX;
        args->auth_flavor_len   = 0;
+       args->minorversion      = 0;
 
        switch (data->version) {
        case 1:
@@ -2334,6 +2414,8 @@ static int nfs4_validate_mount_data(void *options,
 
                nfs_validate_transport_protocol(args);
 
+               nfs4_validate_mount_flags(args);
+
                if (args->auth_flavor_len > 1)
                        goto out_inval_auth;
 
@@ -2373,12 +2455,12 @@ out_no_client_address:
 }
 
 /*
- * Get the superblock for an NFS4 mountpoint
+ * Get the superblock for the NFS4 root partition
  */
-static int nfs4_get_sb(struct file_system_type *fs_type,
+static int nfs4_remote_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
 {
-       struct nfs_parsed_mount_data *data;
+       struct nfs_parsed_mount_data *data = raw_data;
        struct super_block *s;
        struct nfs_server *server;
        struct nfs_fh *mntfh;
@@ -2389,18 +2471,12 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
        };
        int error = -ENOMEM;
 
-       data = kzalloc(sizeof(*data), GFP_KERNEL);
        mntfh = kzalloc(sizeof(*mntfh), GFP_KERNEL);
        if (data == NULL || mntfh == NULL)
                goto out_free_fh;
 
        security_init_mnt_opts(&data->lsm_opts);
 
-       /* Validate the mount data */
-       error = nfs4_validate_mount_data(raw_data, data, dev_name);
-       if (error < 0)
-               goto out;
-
        /* Get a volume representation */
        server = nfs4_create_server(data, mntfh);
        if (IS_ERR(server)) {
@@ -2413,7 +2489,7 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
                compare_super = NULL;
 
        /* Get a superblock - note that we may end up sharing one that already exists */
-       s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);
+       s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata);
        if (IS_ERR(s)) {
                error = PTR_ERR(s);
                goto out_free;
@@ -2450,14 +2526,9 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
        error = 0;
 
 out:
-       kfree(data->client_address);
-       kfree(data->nfs_server.export_path);
-       kfree(data->nfs_server.hostname);
-       kfree(data->fscache_uniq);
        security_free_mnt_opts(&data->lsm_opts);
 out_free_fh:
        kfree(mntfh);
-       kfree(data);
        return error;
 
 out_free:
@@ -2471,16 +2542,137 @@ error_splat_super:
        goto out;
 }
 
+static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
+               int flags, void *data, const char *hostname)
+{
+       struct vfsmount *root_mnt;
+       char *root_devname;
+       size_t len;
+
+       len = strlen(hostname) + 3;
+       root_devname = kmalloc(len, GFP_KERNEL);
+       if (root_devname == NULL)
+               return ERR_PTR(-ENOMEM);
+       snprintf(root_devname, len, "%s:/", hostname);
+       root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
+       kfree(root_devname);
+       return root_mnt;
+}
+
+static void nfs_fix_devname(const struct path *path, struct vfsmount *mnt)
+{
+       char *page = (char *) __get_free_page(GFP_KERNEL);
+       char *devname, *tmp;
+
+       if (page == NULL)
+               return;
+       devname = nfs_path(path->mnt->mnt_devname,
+                       path->mnt->mnt_root, path->dentry,
+                       page, PAGE_SIZE);
+       if (devname == NULL)
+               goto out_freepage;
+       tmp = kstrdup(devname, GFP_KERNEL);
+       if (tmp == NULL)
+               goto out_freepage;
+       kfree(mnt->mnt_devname);
+       mnt->mnt_devname = tmp;
+out_freepage:
+       free_page((unsigned long)page);
+}
+
+static int nfs_follow_remote_path(struct vfsmount *root_mnt,
+               const char *export_path, struct vfsmount *mnt_target)
+{
+       struct mnt_namespace *ns_private;
+       struct nameidata nd;
+       struct super_block *s;
+       int ret;
+
+       ns_private = create_mnt_ns(root_mnt);
+       ret = PTR_ERR(ns_private);
+       if (IS_ERR(ns_private))
+               goto out_mntput;
+
+       ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt,
+                       export_path, LOOKUP_FOLLOW, &nd);
+
+       put_mnt_ns(ns_private);
+
+       if (ret != 0)
+               goto out_err;
+
+       s = nd.path.mnt->mnt_sb;
+       atomic_inc(&s->s_active);
+       mnt_target->mnt_sb = s;
+       mnt_target->mnt_root = dget(nd.path.dentry);
+
+       /* Correct the device pathname */
+       nfs_fix_devname(&nd.path, mnt_target);
+
+       path_put(&nd.path);
+       down_write(&s->s_umount);
+       return 0;
+out_mntput:
+       mntput(root_mnt);
+out_err:
+       return ret;
+}
+
+/*
+ * Get the superblock for an NFS4 mountpoint
+ */
+static int nfs4_get_sb(struct file_system_type *fs_type,
+       int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
+{
+       struct nfs_parsed_mount_data *data;
+       char *export_path;
+       struct vfsmount *root_mnt;
+       int error = -ENOMEM;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (data == NULL)
+               goto out_free_data;
+
+       /* Validate the mount data */
+       error = nfs4_validate_mount_data(raw_data, data, dev_name);
+       if (error < 0)
+               goto out;
+
+       export_path = data->nfs_server.export_path;
+       data->nfs_server.export_path = "/";
+       root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, data,
+                       data->nfs_server.hostname);
+       data->nfs_server.export_path = export_path;
+
+       error = PTR_ERR(root_mnt);
+       if (IS_ERR(root_mnt))
+               goto out;
+
+       error = nfs_follow_remote_path(root_mnt, export_path, mnt);
+
+out:
+       kfree(data->client_address);
+       kfree(data->nfs_server.export_path);
+       kfree(data->nfs_server.hostname);
+       kfree(data->fscache_uniq);
+out_free_data:
+       kfree(data);
+       dprintk("<-- nfs4_get_sb() = %d%s\n", error,
+                       error != 0 ? " [error]" : "");
+       return error;
+}
+
 static void nfs4_kill_super(struct super_block *sb)
 {
        struct nfs_server *server = NFS_SB(sb);
 
+       dprintk("--> %s\n", __func__);
        nfs_super_return_all_delegations(sb);
        kill_anon_super(sb);
-
        nfs4_renewd_prepare_shutdown(server);
        nfs_fscache_release_super_cookie(sb);
        nfs_free_server(server);
+       dprintk("<-- %s\n", __func__);
 }
 
 /*
@@ -2566,12 +2758,9 @@ error_splat_super:
        return error;
 }
 
-/*
- * Create an NFS4 server record on referral traversal
- */
-static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags,
-                               const char *dev_name, void *raw_data,
-                               struct vfsmount *mnt)
+static int nfs4_remote_referral_get_sb(struct file_system_type *fs_type,
+               int flags, const char *dev_name, void *raw_data,
+               struct vfsmount *mnt)
 {
        struct nfs_clone_mount *data = raw_data;
        struct super_block *s;
@@ -2650,4 +2839,36 @@ error_splat_super:
        return error;
 }
 
+/*
+ * Create an NFS4 server record on referral traversal
+ */
+static int nfs4_referral_get_sb(struct file_system_type *fs_type,
+               int flags, const char *dev_name, void *raw_data,
+               struct vfsmount *mnt)
+{
+       struct nfs_clone_mount *data = raw_data;
+       char *export_path;
+       struct vfsmount *root_mnt;
+       int error;
+
+       dprintk("--> nfs4_referral_get_sb()\n");
+
+       export_path = data->mnt_path;
+       data->mnt_path = "/";
+
+       root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
+                       flags, data, data->hostname);
+       data->mnt_path = export_path;
+
+       error = PTR_ERR(root_mnt);
+       if (IS_ERR(root_mnt))
+               goto out;
+
+       error = nfs_follow_remote_path(root_mnt, export_path, mnt);
+out:
+       dprintk("<-- nfs4_referral_get_sb() = %d%s\n", error,
+                       error != 0 ? " [error]" : "");
+       return error;
+}
+
 #endif /* CONFIG_NFS_V4 */