--- a/fs/nfs/super.c	2007-12-19 13:28:03.000000000 -0800
+++ b/fs/nfs/super.c	2007-12-19 13:34:34.000000000 -0800
@@ -584,27 +584,71 @@
  	nfs_initialise_sb(sb);
 }
 
-static int nfs_set_super(struct super_block *s, void *_server)
-{
-	struct nfs_server *server = _server;
-	int ret;
+#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
 
-	s->s_fs_info = server;
-	ret = set_anon_super(s, server);
-	if (ret == 0)
-		server->s_dev = s->s_dev;
-	return ret;
+static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
+{
+        const struct nfs_server *a = s->s_fs_info;
+        const struct rpc_clnt *clnt_a = a->client;
+        const struct rpc_clnt *clnt_b = b->client;
+
+        if ((s->s_flags & NFS_MS_MASK) != (flags & NFS_MS_MASK))
+                goto Ebusy;
+        if (a->nfs_client != b->nfs_client)
+                goto Ebusy;
+        if (a->flags != b->flags)
+                goto Ebusy;
+        if (a->wsize != b->wsize)
+                goto Ebusy;
+        if (a->rsize != b->rsize)
+                goto Ebusy;
+        if (a->acregmin != b->acregmin)
+                goto Ebusy;
+        if (a->acregmax != b->acregmax)
+                goto Ebusy;
+        if (a->acdirmin != b->acdirmin)
+                goto Ebusy;
+        if (a->acdirmax != b->acdirmax)
+                goto Ebusy;
+        if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
+                goto Ebusy;
+        return 1;
+Ebusy:
+        return 0;
+}
+
+struct nfs_sb_mountdata {
+        struct nfs_server *server;
+        int mntflags;
+};
+
+static int nfs_set_super(struct super_block *s, void *data)
+{
+        struct nfs_sb_mountdata *sb_mntdata = data;
+        struct nfs_server *server = sb_mntdata->server;
+        int ret;
+
+        s->s_flags = sb_mntdata->mntflags;
+        s->s_fs_info = server;
+        ret = set_anon_super(s, server);
+        if (ret == 0)
+                server->s_dev = s->s_dev;
+        return ret;
 }
 
 static int nfs_compare_super(struct super_block *sb, void *data)
 {
-	struct nfs_server *server = data, *old = NFS_SB(sb);
-
-	if (old->nfs_client != server->nfs_client)
-		return 0;
-	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
-		return 0;
-	return 1;
+        struct nfs_sb_mountdata *sb_mntdata = data;
+        struct nfs_server *server = sb_mntdata->server, *old = NFS_SB(sb);
+        int mntflags = sb_mntdata->mntflags;
+
+        if (memcmp(&old->nfs_client->cl_addr,
+                                &server->nfs_client->cl_addr,
+                                sizeof(old->nfs_client->cl_addr)) != 0)
+                return 0;
+        if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
+                return 0;
+        return nfs_compare_mount_options(sb, server, mntflags);
 }
 
 static int nfs_get_sb(struct file_system_type *fs_type,
@@ -615,6 +659,9 @@
 	struct nfs_fh mntfh;
 	struct nfs_mount_data *data = raw_data;
 	struct dentry *mntroot;
+	struct nfs_sb_mountdata sb_mntdata = {
+		.mntflags = flags,
+	};
 	int error;
 
 	/* Validate the mount data */
@@ -629,8 +676,10 @@
 		goto out_err_noserver;
 	}
 
+	sb_mntdata.server = server;
+
 	/* Get a superblock - note that we may end up sharing one that already exists */
-	s = sget(fs_type, nfs_compare_super, nfs_set_super, server);
+	s = sget(fs_type, nfs_compare_super, nfs_set_super, &sb_mntdata);
 	if (IS_ERR(s)) {
 		error = PTR_ERR(s);
 		goto out_err_nosb;
@@ -643,7 +692,6 @@
 
 	if (!s->s_root) {
 		/* initial superblock/root creation */
-		s->s_flags = flags;
 		nfs_fill_super(s, data);
 	}
 
@@ -691,6 +739,9 @@
 	struct super_block *s;
 	struct nfs_server *server;
 	struct dentry *mntroot;
+	struct nfs_sb_mountdata sb_mntdata = {
+		.mntflags = flags,
+	};
 	int error;
 
 	dprintk("--> nfs_xdev_get_sb()\n");
@@ -701,9 +752,10 @@
 		error = PTR_ERR(server);
 		goto out_err_noserver;
 	}
+	sb_mntdata.server = server;
 
 	/* Get a superblock - note that we may end up sharing one that already exists */
-	s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
+	s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, &sb_mntdata);
 	if (IS_ERR(s)) {
 		error = PTR_ERR(s);
 		goto out_err_nosb;
@@ -716,7 +768,6 @@
 
 	if (!s->s_root) {
 		/* initial superblock/root creation */
-		s->s_flags = flags;
 		nfs_clone_super(s, data->sb);
 	}
 
@@ -807,6 +858,9 @@
 	struct nfs_fh mntfh;
 	struct dentry *mntroot;
 	char *mntpath = NULL, *hostname = NULL, ip_addr[16];
+	struct nfs_sb_mountdata sb_mntdata = {
+		.mntflags = flags,
+	};
 	void *p;
 	int error;
 
@@ -878,9 +932,10 @@
 		error = PTR_ERR(server);
 		goto out_err_noserver;
 	}
+	sb_mntdata.server = server;
 
 	/* Get a superblock - note that we may end up sharing one that already exists */
-	s = sget(fs_type, nfs_compare_super, nfs_set_super, server);
+	s = sget(fs_type, nfs_compare_super, nfs_set_super, &sb_mntdata);
 	if (IS_ERR(s)) {
 		error = PTR_ERR(s);
 		goto out_free;
@@ -893,7 +948,6 @@
 
 	if (!s->s_root) {
 		/* initial superblock/root creation */
-		s->s_flags = flags;
 		nfs4_fill_super(s);
 	}
 
@@ -949,6 +1003,9 @@
 	struct super_block *s;
 	struct nfs_server *server;
 	struct dentry *mntroot;
+	struct nfs_sb_mountdata sb_mntdata = {
+		.mntflags = flags,
+	};
 	int error;
 
 	dprintk("--> nfs4_xdev_get_sb()\n");
@@ -959,9 +1016,10 @@
 		error = PTR_ERR(server);
 		goto out_err_noserver;
 	}
+	sb_mntdata.server = server;
 
 	/* Get a superblock - note that we may end up sharing one that already exists */
-	s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
+	s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, &sb_mntdata);
 	if (IS_ERR(s)) {
 		error = PTR_ERR(s);
 		goto out_err_nosb;
@@ -974,7 +1032,6 @@
 
 	if (!s->s_root) {
 		/* initial superblock/root creation */
-		s->s_flags = flags;
 		nfs4_clone_super(s, data->sb);
 	}
 
@@ -1016,6 +1073,9 @@
 	struct nfs_server *server;
 	struct dentry *mntroot;
 	struct nfs_fh mntfh;
+	struct nfs_sb_mountdata sb_mntdata = {
+		.mntflags = flags,
+	};
 	int error;
 
 	dprintk("--> nfs4_referral_get_sb()\n");
@@ -1026,9 +1086,10 @@
 		error = PTR_ERR(server);
 		goto out_err_noserver;
 	}
+	sb_mntdata.server = server;
 
 	/* Get a superblock - note that we may end up sharing one that already exists */
-	s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
+	s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, &sb_mntdata);
 	if (IS_ERR(s)) {
 		error = PTR_ERR(s);
 		goto out_err_nosb;
@@ -1041,7 +1102,6 @@
 
 	if (!s->s_root) {
 		/* initial superblock/root creation */
-		s->s_flags = flags;
 		nfs4_fill_super(s);
 	}