blk-wbt: don't maintain inflight counts if disabled (c125311d) · Commits · 戴 / test

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: ("block: remove external dependency on wbt_flags") Reviewed-by:

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

Jens Axboe <axboe@kernel.dk>

block/blk-sysfs.c

+18 −1

Original line number	Diff line number	Diff line
		@@ -453,9 +453,26 @@ static ssize_t queue_wb_lat_store(struct request_queue q, const char page,
		else if (val >= 0)
		val *= 1000ULL;

		wbt_set_min_lat(q, val);
		/*
		* Ensure that the queue is idled, in case the latency update
		* ends up either enabling or disabling wbt completely. We can't
		* have IO inflight if that happens.
		*/
		if (q->mq_ops) {
		blk_mq_freeze_queue(q);
		blk_mq_quiesce_queue(q);
		} else
		blk_queue_bypass_start(q);

		wbt_set_min_lat(q, val);
		wbt_update_limits(q);

		if (q->mq_ops) {
		blk_mq_unquiesce_queue(q);
		blk_mq_unfreeze_queue(q);
		} else
		blk_queue_bypass_end(q);

		return count;
		}

block/blk-wbt.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -540,6 +540,9 @@ static enum wbt_flags bio_to_wbt_flags(struct rq_wb rwb, struct bio bio)
		{
		enum wbt_flags flags = 0;

		if (!rwb_enabled(rwb))
		return 0;

		if (bio_op(bio) == REQ_OP_READ) {
		flags = WBT_READ;
		} else if (wbt_should_throttle(rwb, bio)) {

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