When try to issue request directly, if the queue is stopped or quiesced, 'bypass_insert' will be ignored and return BLK_STS_OK to caller to avoid it dispatch request again. Then the request will be inserted with blk_mq_sched_insert_request. This is not correct for dm-rq case where we should avoid to pass through the underlying paths' io scheduler.
To fix it, use blk_mq_request_bypass_insert to insert the request into hctx->dispatch directly. Signed-off-by: Jianchao Wang <[email protected]> --- block/blk-mq.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 0f6328b..e0aa068 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1729,13 +1729,14 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx, } enum mq_decision { + MQ_INSERT_DISPATCH, MQ_INSERT_QUEUE, MQ_END_REQUEST, MQ_DO_NOTHING, }; static inline enum mq_decision - blk_mq_make_dicision(blk_status_t ret, bool bypass_insert) + blk_mq_make_dicision(blk_status_t ret, bool bypass_insert, bool force) { enum mq_decision dec; @@ -1745,7 +1746,10 @@ static inline enum mq_decision break; case BLK_STS_DEV_RESOURCE: case BLK_STS_RESOURCE: - dec = bypass_insert ? MQ_DO_NOTHING : MQ_INSERT_QUEUE; + if (force) + dec = bypass_insert ? MQ_INSERT_DISPATCH : MQ_INSERT_QUEUE; + else + dec = bypass_insert ? MQ_DO_NOTHING : MQ_INSERT_QUEUE; break; default: dec = bypass_insert ? MQ_DO_NOTHING : MQ_END_REQUEST; @@ -1761,7 +1765,7 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, bool bypass_insert) { struct request_queue *q = rq->q; - bool run_queue = true; + bool run_queue = true, force = false; enum mq_decision dec; blk_status_t ret = BLK_STS_RESOURCE; int srcu_idx; @@ -1776,7 +1780,7 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, */ if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) { run_queue = false; - bypass_insert = false; + force = true; goto out_unlock; } @@ -1795,8 +1799,11 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, out_unlock: hctx_unlock(hctx, srcu_idx); - dec = blk_mq_make_dicision(ret, bypass_insert); + dec = blk_mq_make_dicision(ret, bypass_insert, force); switch(dec) { + case MQ_INSERT_DISPATCH: + blk_mq_request_bypass_insert(rq, run_queue); + break; case MQ_INSERT_QUEUE: blk_mq_sched_insert_request(rq, false, run_queue, false); break; -- 2.7.4
