GFS2: use memchr_inv

Use memchr_inv to verify that the specified memory range is cleared.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: cluster-devel@redhat.com
Cc: Christine Caulfield <ccaulfie@redhat.com>
Cc: David Teigland <teigland@redhat.com>

fs/gfs2/lock_dlm.c

@@ -483,12 +483,8 @@ static void control_lvb_write(struct lm_lockstruct *ls, uint32_t lvb_gen,
 
 static int all_jid_bits_clear(char *lvb)
 {
-	int i;
-	for (i = JID_BITMAP_OFFSET; i < GDLM_LVB_SIZE; i++) {
-		if (lvb[i])
-			return 0;
-	}
-	return 1;
+	return !memchr_inv(lvb + JID_BITMAP_OFFSET, 0,
+			GDLM_LVB_SIZE - JID_BITMAP_OFFSET);
 }
 
 static void sync_wait_cb(void *arg)