Revert "NFSv4: Remove incorrect check in can_open_delegated()"

commit 36319608 upstream.

This reverts commit 4e379d36.

This commit opens up a race between the recovery code and the open code.
Reported-by: Olga Kornievskaia <aglo@umich.edu>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/nfs/nfs4proc.c

@@ -1152,6 +1152,8 @@ static int can_open_delegated(struct nfs_delegation *delegation, fmode_t fmode)
 		return 0;
 	if ((delegation->type & fmode) != fmode)
 		return 0;
+	if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags))
+		return 0;
 	if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
 		return 0;
 	nfs_mark_delegation_referenced(delegation);