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| author | Jeffle Xu <jefflexu@linux.alibaba.com> | 2021-02-22 14:54:52 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-02-22 06:40:02 -0700 |
| commit | 6b09b4d33bd964f49d07d3cabfb4204d58cf9811 (patch) | |
| tree | 7b69248f21d2b2c7db0e8b6f9e8131d8c45515ed /block/blk-sysfs.c | |
| parent | b357e4a694ac4b95096715df253548f7e1f2723f (diff) | |
| download | lwn-6b09b4d33bd964f49d07d3cabfb4204d58cf9811.tar.gz lwn-6b09b4d33bd964f49d07d3cabfb4204d58cf9811.zip | |
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 <jefflexu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-sysfs.c')
| -rw-r--r-- | block/blk-sysfs.c | 7 |
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; } |