3 files changed, 24 insertions, 0 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 143149db3440..92aed2e08bd5 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -752,6 +752,8 @@ static int nfs_init_server(struct nfs_server *server,
                         data->timeo, data->retrans);
         if (data->flags & NFS_MOUNT_NORESVPORT)
                 set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
+        if (server->options & NFS_OPTION_MIGRATION)
+                set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);
 
         /* Allocate or find a client reference we can use */
         clp = nfs_get_client(&cl_init, &timeparms, NULL, RPC_AUTH_UNIX);
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index b8eda700584b..056138d45c11 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -88,6 +88,7 @@ enum {
         Opt_sharecache, Opt_nosharecache,
         Opt_resvport, Opt_noresvport,
         Opt_fscache, Opt_nofscache,
+        Opt_migration, Opt_nomigration,
 
         /* Mount options that take integer arguments */
         Opt_port,
@@ -147,6 +148,8 @@ static const match_table_t nfs_mount_option_tokens = {
         { Opt_noresvport, "noresvport" },
         { Opt_fscache, "fsc" },
         { Opt_nofscache, "nofsc" },
+        { Opt_migration, "migration" },
+        { Opt_nomigration, "nomigration" },
 
         { Opt_port, "port=%s" },
         { Opt_rsize, "rsize=%s" },
@@ -676,6 +679,9 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
         if (nfss->options & NFS_OPTION_FSCACHE)
                 seq_printf(m, ",fsc");
 
+        if (nfss->options & NFS_OPTION_MIGRATION)
+                seq_printf(m, ",migration");
+
         if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
                 if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
                         seq_printf(m, ",lookupcache=none");
@@ -1243,6 +1249,12 @@ static int nfs_parse_mount_options(char *raw,
                         kfree(mnt->fscache_uniq);
                         mnt->fscache_uniq = NULL;
                         break;
+                case Opt_migration:
+                        mnt->options |= NFS_OPTION_MIGRATION;
+                        break;
+                case Opt_nomigration:
+                        mnt->options &= NFS_OPTION_MIGRATION;
+                        break;
 
                 /*
                  * options that take numeric values
@@ -1535,6 +1547,10 @@ static int nfs_parse_mount_options(char *raw,
         if (mnt->minorversion && mnt->version != 4)
                 goto out_minorversion_mismatch;
 
+        if (mnt->options & NFS_OPTION_MIGRATION &&
+            mnt->version != 4 && mnt->minorversion != 0)
+                goto out_migration_misuse;
+
         /*
          * verify that any proto=/mountproto= options match the address
          * familiies in the addr=/mountaddr= options.
@@ -1572,6 +1588,10 @@ out_minorversion_mismatch:
         printk(KERN_INFO "NFS: mount option vers=%u does not support "
                          "minorversion=%u\n", mnt->version, mnt->minorversion);
         return 0;
+out_migration_misuse:
+        printk(KERN_INFO
+                "NFS: 'migration' not supported for this NFS version\n");
+        return 0;
 out_nomem:
         printk(KERN_INFO "NFS: not enough memory to parse option\n");
         return 0;
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 310c63c8ab2c..2e22fc7e47cf 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -39,6 +39,7 @@ struct nfs_client {
         unsigned long           cl_flags;       /* behavior switches */
 #define NFS_CS_NORESVPORT       0               /* - use ephemeral src port */
 #define NFS_CS_DISCRTRY         1               /* - disconnect on RPC retry */
+#define NFS_CS_MIGRATION        2               /* - transparent state migr */
         struct sockaddr_storage cl_addr;        /* server identifier */
         size_t                  cl_addrlen;
         char *                  cl_hostname;    /* hostname of server */
@@ -125,6 +126,7 @@ struct nfs_server {
         unsigned int            namelen;
         unsigned int            options;        /* extra options enabled by mount */
 #define NFS_OPTION_FSCACHE      0x00000001      /* - local caching enabled */
+#define NFS_OPTION_MIGRATION    0x00000002      /* - NFSv4 migration enabled */
 
         struct nfs_fsid         fsid;
         __u64                   maxfilesize;    /* maximum file size */