pNFS: Don't clear the layout stateid if a layout return is outstanding

commit 7b650994 upstream.

If we no longer hold any layout segments, we're normally expected to
consider the layout stateid to be invalid. However we cannot assume this
if we're about to, or in the process of sending a layoutreturn.

Fixes: 334a8f37 ("pNFS: Don't forget the layout stateid if...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/nfs/pnfs.c

@@ -364,7 +364,9 @@ pnfs_layout_remove_lseg(struct pnfs_layout_hdr *lo,
 	list_del_init(&lseg->pls_list);
 	/* Matched by pnfs_get_layout_hdr in pnfs_layout_insert_lseg */
 	atomic_dec(&lo->plh_refcount);
-	if (list_empty(&lo->plh_segs)) {
+	if (list_empty(&lo->plh_segs) &&
+	    !test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags) &&
+	    !test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
 		if (atomic_read(&lo->plh_outstanding) == 0)
 			set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
 		clear_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);