NFSv4.1: Do not call pnfs_return_layout() from an rpciod context

Move the call to pnfs_return_layout() to the read and write rpc_release()
callbacks, so that it gets called from nfsiod, which is a more appropriate
context.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 2d722db..dbf7bba 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -62,6 +62,7 @@
 	NFS_LAYOUT_RW_FAILED,		/* get rw layout failed stop trying */
 	NFS_LAYOUT_BULK_RECALL,		/* bulk recall affecting layout */
 	NFS_LAYOUT_ROC,			/* some lseg had roc bit set */
+	NFS_LAYOUT_RETURN,		/* Return this layout ASAP */
 };
 
 enum layoutdriver_policy_flags {