Commit 580c10a4 authored Aug 05, 2021 by Yu Kuai Committed by Greg Kroah-Hartman Aug 12, 2021

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



[ Upstream commit 8d75d0eff6887bcac7225e12b9c75595e523d92d ]

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: 8c772a9b ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent ed169b05

block/blk-iolatency.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -832,7 +832,11 @@ 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);
		}