NFSv4.x: Fix handling of partially delegated locks

If a NFS client receives a delegation for a file after it has taken
a lock on that file, we can currently end up in a situation where
we mistakenly skip unlocking that file.

The following patch swaps an erroneous check in nfs4_proc_unlck for
whether or not the file has a delegation to one which checks whether
or not we hold a lock stateid for that file.

Reported-by: Chuck Lever <Chuck.Lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org [>=3.7]
Tested-by: Chuck Lever <Chuck.Lever@oracle.com>

fs/nfs/nfs4proc.c

@@ -4766,9 +4766,9 @@ static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *
 	if (status != 0)
 		goto out;
 	/* Is this a delegated lock? */
-	if (test_bit(NFS_DELEGATED_STATE, &state->flags))
-		goto out;
 	lsp = request->fl_u.nfs4_fl.owner;
+	if (test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags) == 0)
+		goto out;
 	seqid = nfs_alloc_seqid(&lsp->ls_seqid, GFP_KERNEL);
 	status = -ENOMEM;
 	if (seqid == NULL)