From c125311d96b1bfcce0f5930a4f0fdfe39ea14f7c Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 23 Aug 2018 09:34:46 -0600 Subject: [PATCH] blk-wbt: don't maintain inflight counts if disabled 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: c1c80384c8f ("block: remove external dependency on wbt_flags") Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe --- block/blk-sysfs.c | 19 ++++++++++++++++++- block/blk-wbt.c | 3 +++ 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index bb109bb..3772671 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -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; } diff --git a/block/blk-wbt.c b/block/blk-wbt.c index c9358f1..84507d3 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -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)) { -- 2.7.4