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blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit()

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If queue is dying while iolatency_set_limit() is in progress,
blk_get_queue() won't increment the refcount of the queue. However,
blk_put_queue() will still decrement the refcount later, which will
cause the refcout to be unbalanced.

Thus error out in such case to fix the problem.

Fixes: 8c772a9bfc ("blk-iolatency: fix IO hang due to negative inflight counter")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210805124645.543797-1-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Yu Kuai 2021-08-05 20:46:45 +08:00 committed by Jens Axboe
parent cc396d27d8
commit 8d75d0eff6
1 changed files with 5 additions and 1 deletions
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6
block/blk-iolatency.c
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@ -833,7 +833,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
enable = iolatency_set_min_lat_nsec(blkg, lat_val);
if (enable) {
WARN_ON_ONCE(!blk_get_queue(blkg->q));
if (!blk_get_queue(blkg->q)) {
ret = -ENODEV;
goto out;
}
blkg_get(blkg);
}