pnfs: use lwb as layoutcommit length

commit 3557c6c3be5b2ca0b11365db7f8a813253eb520b upstream.

Using NFS4_MAX_UINT64 will break current protocol.

[Needed in v3.0]
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index e6e8f3b..fc97fd5 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1888,7 +1888,7 @@
 	*p++ = cpu_to_be32(OP_LAYOUTCOMMIT);
 	/* Only whole file layouts */
 	p = xdr_encode_hyper(p, 0); /* offset */
-	p = xdr_encode_hyper(p, NFS4_MAX_UINT64); /* length */
+	p = xdr_encode_hyper(p, args->lastbytewritten + 1);	/* length */
 	*p++ = cpu_to_be32(0); /* reclaim */
 	p = xdr_encode_opaque_fixed(p, args->stateid.data, NFS4_STATEID_SIZE);
 	*p++ = cpu_to_be32(1); /* newoffset = TRUE */