pnfsblock: add blocklayout Kconfig option, Makefile, and stubs

Define a configuration variable to enable/disable compilation of the
block driver code.

Add the minimal structure for a pnfs block layout driver, and empty
list-heads that will hold the extent data

[pnfsblock: make NFS_V4_1 select PNFS_BLOCK]
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[pnfs-block: fix CONFIG_PNFS_BLOCK dependencies]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
[pnfsblock: SQUASHME: adjust to API change]
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
[pnfs: move pnfs_layout_type inline in nfs_inode]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[blocklayout: encode_layoutcommit implementation]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
[pnfsblock: layout alloc and free]
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
[pnfs: move pnfs_layout_type inline in nfs_inode]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
[pnfsblock: define module alias]
Signed-off-by: Peng Tao <peng_tao@emc.com>
[rm inode and pnfs_layout_hdr args from cleanup_layoutcommit()]
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/Kconfig

@@ -79,15 +79,21 @@ config NFS_V4_1
 	depends on NFS_FS && NFS_V4 && EXPERIMENTAL
 	select SUNRPC_BACKCHANNEL
 	select PNFS_FILE_LAYOUT
+	select PNFS_BLOCK
+	select MD
+	select BLK_DEV_DM
 	help
 	  This option enables support for minor version 1 of the NFSv4 protocol
-	  (RFC 5661) in the kernel's NFS client.
+	  (RFC 5661 and RFC 5663) in the kernel's NFS client.
 
 	  If unsure, say N.
 
 config PNFS_FILE_LAYOUT
 	tristate
 
+config PNFS_BLOCK
+	tristate
+
 config PNFS_OBJLAYOUT
 	tristate "Provide support for the pNFS Objects Layout Driver for NFSv4.1 pNFS (EXPERIMENTAL)"
 	depends on NFS_FS && NFS_V4_1 && SCSI_OSD_ULD