From a327c341dc65e38af7a2398e7313e6f2c4a813db Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 12 May 2022 22:00:10 +0800 Subject: [PATCH] blk-mq: fix passthrough plugging First we can't add request into plug list in blk_mq_request_bypass_insert which may be called when flushing plug list, so nested plug is caused. Second if polled passthrough request is inserted via blk_execute_rq(), it can't be added to plug list too since io polling needs the request to be issued to driver. Fixes the two by moving plugging into blk_execute_rq_no_wait(). Cc: Christoph Hellwig Fixes: 1c2d2fff6dc0 ("block: wire-up support for passthrough plugging") Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20220512140010.1458645-1-ming.lei@redhat.com Signed-off-by: Jens Axboe --- block/blk-mq.c | 114 +++++++++++++++++++++++++++---------------------- 1 file changed, 63 insertions(+), 51 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 2cf011b57cf9..ed1869a305c4 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1169,6 +1169,62 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t error) complete(waiting); } +/* + * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple + * queues. This is important for md arrays to benefit from merging + * requests. + */ +static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug) +{ + if (plug->multiple_queues) + return BLK_MAX_REQUEST_COUNT * 2; + return BLK_MAX_REQUEST_COUNT; +} + +static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq) +{ + struct request *last = rq_list_peek(&plug->mq_list); + + if (!plug->rq_count) { + trace_block_plug(rq->q); + } else if (plug->rq_count >= blk_plug_max_rq_count(plug) || + (!blk_queue_nomerges(rq->q) && + blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) { + blk_mq_flush_plug_list(plug, false); + trace_block_plug(rq->q); + } + + if (!plug->multiple_queues && last && last->q != rq->q) + plug->multiple_queues = true; + if (!plug->has_elevator && (rq->rq_flags & RQF_ELV)) + plug->has_elevator = true; + rq->rq_next = NULL; + rq_list_add(&plug->mq_list, rq); + plug->rq_count++; +} + +static void __blk_execute_rq_nowait(struct request *rq, bool at_head, + rq_end_io_fn *done, bool use_plug) +{ + WARN_ON(irqs_disabled()); + WARN_ON(!blk_rq_is_passthrough(rq)); + + rq->end_io = done; + + blk_account_io_start(rq); + + if (use_plug && current->plug) { + blk_add_rq_to_plug(current->plug, rq); + return; + } + /* + * don't check dying flag for MQ because the request won't + * be reused after dying flag is set + */ + blk_mq_sched_insert_request(rq, at_head, true, false); +} + + /** * blk_execute_rq_nowait - insert a request to I/O scheduler for execution * @rq: request to insert @@ -1184,18 +1240,8 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t error) */ void blk_execute_rq_nowait(struct request *rq, bool at_head, rq_end_io_fn *done) { - WARN_ON(irqs_disabled()); - WARN_ON(!blk_rq_is_passthrough(rq)); + __blk_execute_rq_nowait(rq, at_head, done, true); - rq->end_io = done; - - blk_account_io_start(rq); - - /* - * don't check dying flag for MQ because the request won't - * be reused after dying flag is set - */ - blk_mq_sched_insert_request(rq, at_head, true, false); } EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); @@ -1233,8 +1279,13 @@ blk_status_t blk_execute_rq(struct request *rq, bool at_head) DECLARE_COMPLETION_ONSTACK(wait); unsigned long hang_check; + /* + * iopoll requires request to be submitted to driver, so can't + * use plug + */ rq->end_io_data = &wait; - blk_execute_rq_nowait(rq, at_head, blk_end_sync_rq); + __blk_execute_rq_nowait(rq, at_head, blk_end_sync_rq, + !blk_rq_is_poll(rq)); /* Prevent hang_check timer from firing at us during very long I/O */ hang_check = sysctl_hung_task_timeout_secs; @@ -2340,40 +2391,6 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, blk_mq_hctx_mark_pending(hctx, ctx); } -/* - * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple - * queues. This is important for md arrays to benefit from merging - * requests. - */ -static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug) -{ - if (plug->multiple_queues) - return BLK_MAX_REQUEST_COUNT * 2; - return BLK_MAX_REQUEST_COUNT; -} - -static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq) -{ - struct request *last = rq_list_peek(&plug->mq_list); - - if (!plug->rq_count) { - trace_block_plug(rq->q); - } else if (plug->rq_count >= blk_plug_max_rq_count(plug) || - (!blk_queue_nomerges(rq->q) && - blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) { - blk_mq_flush_plug_list(plug, false); - trace_block_plug(rq->q); - } - - if (!plug->multiple_queues && last && last->q != rq->q) - plug->multiple_queues = true; - if (!plug->has_elevator && (rq->rq_flags & RQF_ELV)) - plug->has_elevator = true; - rq->rq_next = NULL; - rq_list_add(&plug->mq_list, rq); - plug->rq_count++; -} - /** * blk_mq_request_bypass_insert - Insert a request at dispatch list. * @rq: Pointer to request to be inserted. @@ -2387,12 +2404,7 @@ void blk_mq_request_bypass_insert(struct request *rq, bool at_head, bool run_queue) { struct blk_mq_hw_ctx *hctx = rq->mq_hctx; - struct blk_plug *plug = current->plug; - if (plug) { - blk_add_rq_to_plug(plug, rq); - return; - } spin_lock(&hctx->lock); if (at_head) list_add(&rq->queuelist, &hctx->dispatch);