NFSv4.1: pnfs: full mount/umount infrastructure

Allow a module implementing a layout type to register, and
have its mount/umount routines called for filesystems that
the server declares support it.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Andy Adamson<andros@netapp.com>
Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 3f69752..d943119 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -75,13 +75,17 @@
 
 config NFS_V4_1
 	bool "NFS client support for NFSv4.1 (EXPERIMENTAL)"
-	depends on NFS_V4 && EXPERIMENTAL
+	depends on NFS_FS && NFS_V4 && EXPERIMENTAL
+	select PNFS_FILE_LAYOUT
 	help
 	  This option enables support for minor version 1 of the NFSv4 protocol
-	  (draft-ietf-nfsv4-minorversion1) in the kernel's NFS client.
+	  (RFC 5661) in the kernel's NFS client.
 
 	  If unsure, say N.
 
+config PNFS_FILE_LAYOUT
+	tristate
+
 config ROOT_NFS
 	bool "Root file system on NFS"
 	depends on NFS_FS=y && IP_PNP