nfs41: Correct offset for LAYOUTCOMMIT

A client sends offset to MDS as it was seen by DS. As result,
file size after copy is only half of original file size in case
of 2 DS.
Signed-off-by: NVitaliy Gusev <gusev.vitaliy@nexenta.com>
Cc: stable@kernel.org [2.6.39]
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pnfs.c

@@ -1009,7 +1009,7 @@ void
 pnfs_set_layoutcommit(struct nfs_write_data *wdata)
 {
 	struct nfs_inode *nfsi = NFS_I(wdata->inode);
-	loff_t end_pos = wdata->args.offset + wdata->res.count;
+	loff_t end_pos = wdata->mds_offset + wdata->res.count;
 	bool mark_as_dirty = false;
 
 	spin_lock(&nfsi->vfs_inode.i_lock);