block: drain queue before waiting for q_usage_counter becoming zero

Now we track legacy requests with .q_usage_counter in commit 055f6e18e08f
("block: Make q_usage_counter also track legacy requests"), but that
commit never runs and drains legacy queue before waiting for this counter
becoming zero, then IO hang is caused in the test of pulling disk during IO.

This patch fixes the issue by draining requests before waiting for
q_usage_counter becoming zero, both Mauricio and chenxiang reported this
issue, and observed that it can be fixed by this patch.

Link: https://marc.info/?l=linux-block&m=151192424731797&w=2
Fixes: 055f6e18e08f("block: Make q_usage_counter also track legacy requests")
Cc: Wen Xiong <wenxiong@us.ibm.com>
Tested-by: "chenxiang (M)" <chenxiang66@hisilicon.com>
Tested-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-core.c b/block/blk-core.c
index b8881750a3acd705789050c845c942673da999a8..3ba4326a63b59632fad81e686bf8229eee07320b 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -562,6 +562,13 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
        }
 }
 
+void blk_drain_queue(struct request_queue *q)
+{
+       spin_lock_irq(q->queue_lock);
+       __blk_drain_queue(q, true);
+       spin_unlock_irq(q->queue_lock);
+}
+
 /**
  * blk_queue_bypass_start - enter queue bypass mode
  * @q: queue of interest
@@ -689,8 +696,6 @@ void blk_cleanup_queue(struct request_queue *q)
         */
        blk_freeze_queue(q);
        spin_lock_irq(lock);
-       if (!q->mq_ops)
-               __blk_drain_queue(q, true);
        queue_flag_set(QUEUE_FLAG_DEAD, q);
        spin_unlock_irq(lock);
 

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 11097477eeab6591088ca817d4690535e114e699..3d379732749175ece7ae39e427e115f51621c521 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -161,6 +161,8 @@ void blk_freeze_queue(struct request_queue *q)
         * exported to drivers as the only user for unfreeze is blk_mq.
         */
        blk_freeze_queue_start(q);
+       if (!q->mq_ops)
+               blk_drain_queue(q);
        blk_mq_freeze_queue_wait(q);
 }
 

diff --git a/block/blk.h b/block/blk.h
index 3f1446937aece26f38ceb66cf4e3d159a23df871..442098aa9463a37dad0dfccb1718eea65be6cdb3 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -330,4 +330,6 @@ static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
 }
 #endif /* CONFIG_BOUNCE */
 
+extern void blk_drain_queue(struct request_queue *q);
+
 #endif /* BLK_INTERNAL_H */