[dm-devel] [PATCH 1/2] dm-multipath: cleanup IO queueing after table load

[Benjamin Marzinski]

Commit e809917735ebf1b9a56c24e877ce0d320baee2ec changed the code in
multipath_busy that checked if a multipath device was initializing a path.
It returned busy if queue_io was set on the device. However queue_io is set
when the table is loaded, and as long as the device was busy, multipath_map
wouldn't run to clear it upon receiving requsts. multipath_ioctl and
reinstate_path were still able to clear queue_io. But if no paths were
reinstated and the multipath device received no ioctls after the table
reload, all requests to it would simply queue.

This patch switches the multipath_busy code to check for a pending or in
progress path initialization, without using queue_io.  This means incoming
requests will allow multipath_map to initialize paths and clear queue_io.

This patch also changes __choose_pgpath to make it clear queue_io if there
are no valid paths, since there are obviously no paths that can be
initialized.

Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
---
 drivers/md/dm-mpath.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 3f6fd9d..a0b83cb 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -317,8 +317,10 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
 	struct priority_group *pg;
 	unsigned bypassed = 1;
 
-	if (!m->nr_valid_paths)
+	if (!m->nr_valid_paths) {
+		m->queue_io = 0;
 		goto failed;
+	}
 
 	/* Were we instructed to switch PG? */
 	if (m->next_pg) {
@@ -1612,7 +1614,7 @@ static int multipath_busy(struct dm_target *ti)
 	spin_lock_irqsave(&m->lock, flags);
 
 	/* pg_init in progress, requeue until done */
-	if (!pg_ready(m)) {
+	if (m->pg_init_required || m->pg_init_in_progress) {
 		busy = 1;
 		goto out;
 	}
-- 
1.8.3.1