path: root/block/blk-sysfs.c
diff options
authorJeffle Xu <>2021-02-22 14:54:52 +0800
committerJens Axboe <>2021-02-22 06:40:02 -0700
commit6b09b4d33bd964f49d07d3cabfb4204d58cf9811 (patch)
tree7b69248f21d2b2c7db0e8b6f9e8131d8c45515ed /block/blk-sysfs.c
parentb357e4a694ac4b95096715df253548f7e1f2723f (diff)
block: fix potential IO hang when turning off io_poll
QUEUE_FLAG_POLL flag will be cleared when turning off 'io_poll', while at that moment there may be IOs stuck in hw queue uncompleted. The following polling routine won't help reap these IOs, since blk_poll() will return immediately because of cleared QUEUE_FLAG_POLL flag. Thus these IOs will hang until they finnaly time out. The hang out can be observed by 'fio --engine=io_uring iodepth=1', while turning off 'io_poll' at the same time. To fix this, freeze and flush the request queue first when turning off 'io_poll'. Signed-off-by: Jeffle Xu <> Signed-off-by: Jens Axboe <>
Diffstat (limited to 'block/blk-sysfs.c')
1 files changed, 5 insertions, 2 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index ae39c7f3d83d..0f4f0c8a7825 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -434,10 +434,13 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page,
if (ret < 0)
return ret;
- if (poll_on)
+ if (poll_on) {
blk_queue_flag_set(QUEUE_FLAG_POLL, q);
- else
+ } else {
+ blk_mq_freeze_queue(q);
blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
+ blk_mq_unfreeze_queue(q);
+ }
return ret;