block: drain queue before waiting for q_usage_counter becoming zero

[ Upstream commit 454be724f6f99cc7e7bbf15067128be9868186c6 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/blk-core.c b/block/blk-core.c
index f3750389e351e1726bacfa00f6e5852608e949c1..95b7ea996ac2e694f5237c8f464d796dd612184b 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -531,6 +531,13 @@ 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
@@ -655,8 +662,6 @@ 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 98a18609755e94494b4239012f3c57c1503635bf..b60798a30ea20ad95f965e34c6cb843766138da0 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -159,6 +159,8 @@ 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 85be8b232b373b3f69ac829f374e550f06725460..b2c287c2c6a3bbf5a064fd49de7e6baa06ffc482 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -362,4 +362,6 @@ 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 */