dm: don't stop request queue after the dm device is suspended

For fixing queue quiesce race between driver and block layer(elevator
switch, update nr_requests, ...), we need to support concurrent quiesce
and unquiesce, which requires the two call to be balanced.

__bind() is only called from dm_swap_table() in which dm device has been
suspended already, so not necessary to stop queue again. With this way,
request queue quiesce and unquiesce can be balanced.

Reported-by: Yi Zhang <yi.zhang@redhat.com>
Fixes: e70feb8b3e68 ("blk-mq: support concurrent queue quiesce/unquiesce")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Link: https://lore.kernel.org/r/20211021145918.2691762-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8b91f4f..be0eb2e 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1927,16 +1927,6 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 
        dm_table_event_callback(t, event_callback, md);
 
-       /*
-        * The queue hasn't been stopped yet, if the old table type wasn't
-        * for request-based during suspension.  So stop it to prevent
-        * I/O mapping before resume.
-        * This must be done before setting the queue restrictions,
-        * because request-based dm may be run just after the setting.
-        */
-       if (request_based)
-               dm_stop_queue(q);
-
        if (request_based) {
                /*
                 * Leverage the fact that request-based DM targets are