On Thu, Aug 23, 2018 at 09:15:27AM -0600, Jens Axboe wrote:

A previous commit removed the ability to have per-rq flags. We used
those flags to maintain inflight counts. Since we don't have those
anymore, we have to always maintain inflight counts, even if wbt is
disabled. This is clearly suboptimal.

Add a queue quiesce around changing the wbt latency settings from sysfs
to work around this. With that, we can reliably put the enabled check in
our bio_to_wbt_flags(), since we know the WBT_TRACKED flag will be
consistent for the lifetime of the request.

Fixes: Fixes: c1c80384c8f ("block: remove external dependency on wbt_flags")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Sorry about that,

Josef