[PATCH] device-mapper: Fix queue_if_no_path initialisation

When creating a multipath device, if the queue_if_no_path parameter is
specified it gets ignored.

While the queue_if_no_path variable is correctly set to 1, the
saved_queue_if_no_path gets set to 0.  When the device is subsequently made
live (resumed), the saved value (0) always overwrites the live value (1) so
the option *always* gets turned off.

The fix adds a parameter to the queue_if_no_path() function to indicate
whether the previous value should be preserved or not - if not, as when the
device is being set up, the saved value is set to the new value (1).
Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/dm-mpath.c

@@ -329,13 +329,17 @@ static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio,
 /*
  * If we run out of usable paths, should we queue I/O or error it?
  */
-static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path)
+static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
+			    unsigned save_old_value)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
 
-	m->saved_queue_if_no_path = m->queue_if_no_path;
+	if (save_old_value)
+		m->saved_queue_if_no_path = m->queue_if_no_path;
+	else
+		m->saved_queue_if_no_path = queue_if_no_path;
 	m->queue_if_no_path = queue_if_no_path;
 	if (!m->queue_if_no_path && m->queue_size)
 		queue_work(kmultipathd, &m->process_queued_ios);
@@ -677,7 +681,7 @@ static int parse_features(struct arg_set *as, struct multipath *m,
 		return 0;
 
 	if (!strnicmp(shift(as), MESG_STR("queue_if_no_path")))
-		return queue_if_no_path(m, 1);
+		return queue_if_no_path(m, 1, 0);
 	else {
 		ti->error = "Unrecognised multipath feature request";
 		return -EINVAL;
@@ -1077,7 +1081,7 @@ static void multipath_presuspend(struct dm_target *ti)
 {
 	struct multipath *m = (struct multipath *) ti->private;
 
-	queue_if_no_path(m, 0);
+	queue_if_no_path(m, 0, 1);
 }
 
 /*
@@ -1222,9 +1226,9 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 
 	if (argc == 1) {
 		if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
-			return queue_if_no_path(m, 1);
+			return queue_if_no_path(m, 1, 0);
 		else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
-			return queue_if_no_path(m, 0);
+			return queue_if_no_path(m, 0, 0);
 	}
 
 	if (argc != 2)