From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: [PATCH v3 04/11] blk-mq: Introduce blk_mq_quiesce_queue() To: Jens Axboe References: CC: Christoph Hellwig , James Bottomley , "Martin K. Petersen" , Mike Snitzer , Doug Ledford , Keith Busch , Ming Lin , Laurence Oberman , "linux-block@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "linux-nvme@lists.infradead.org" From: Bart Van Assche Message-ID: Date: Tue, 18 Oct 2016 14:50:25 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Sender: linux-scsi-owner@vger.kernel.org List-ID: blk_mq_quiesce_queue() waits until ongoing .queue_rq() invocations have finished. This function does *not* wait until all outstanding requests have finished (this means invocation of request.end_io()). Signed-off-by: Bart Van Assche Cc: Ming Lei Cc: Hannes Reinecke Cc: Johannes Thumshirn --- block/blk-mq.c | 78 ++++++++++++++++++++++++++++++++++++++++++++------ include/linux/blk-mq.h | 3 ++ include/linux/blkdev.h | 1 + 3 files changed, 73 insertions(+), 9 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 4643fa8..d41ed92 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -115,6 +115,30 @@ void blk_mq_unfreeze_queue(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue); +/** + * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished + * + * Note: this function does not prevent that the struct request end_io() + * callback function is invoked. Additionally, it is not prevented that + * new queue_rq() calls occur unless the queue has been stopped first. + */ +void blk_mq_quiesce_queue(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + bool rcu = false; + + queue_for_each_hw_ctx(q, hctx, i) { + if (hctx->flags & BLK_MQ_F_BLOCKING) + synchronize_srcu(&hctx->queue_rq_srcu); + else + rcu = true; + } + if (rcu) + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue); + void blk_mq_wake_waiters(struct request_queue *q) { struct blk_mq_hw_ctx *hctx; @@ -778,7 +802,7 @@ static inline unsigned int queued_to_index(unsigned int queued) * of IO. In particular, we'd like FIFO behaviour on handling existing * items on the hctx->dispatch list. Ignore that for now. */ -static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) +static void blk_mq_process_rq_list(struct blk_mq_hw_ctx *hctx) { struct request_queue *q = hctx->queue; struct request *rq; @@ -790,9 +814,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) if (unlikely(blk_mq_hctx_stopped(hctx))) return; - WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) && - cpu_online(hctx->next_cpu)); - hctx->run++; /* @@ -883,6 +904,24 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) } } +static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) +{ + int srcu_idx; + + WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) && + cpu_online(hctx->next_cpu)); + + if (!(hctx->flags & BLK_MQ_F_BLOCKING)) { + rcu_read_lock(); + blk_mq_process_rq_list(hctx); + rcu_read_unlock(); + } else { + srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu); + blk_mq_process_rq_list(hctx); + srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx); + } +} + /* * It'd be great if the workqueue API had a way to pass * in a mask and had some smarts for more clever placement. @@ -1278,6 +1317,14 @@ static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie) return -1; } +static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, + struct request *rq, blk_qc_t *cookie) +{ + if (blk_mq_hctx_stopped(hctx) || + blk_mq_direct_issue_request(rq, cookie) != 0) + blk_mq_insert_request(rq, false, true, true); +} + /* * Multiple hardware queue variant. This will not use per-process plugs, * but will attempt to bypass the hctx queueing if we can go straight to @@ -1289,7 +1336,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA); struct blk_map_ctx data; struct request *rq; - unsigned int request_count = 0; + unsigned int request_count = 0, srcu_idx; struct blk_plug *plug; struct request *same_queue_rq = NULL; blk_qc_t cookie; @@ -1332,7 +1379,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) blk_mq_bio_to_request(rq, bio); /* - * We do limited pluging. If the bio can be merged, do that. + * We do limited plugging. If the bio can be merged, do that. * Otherwise the existing request in the plug list will be * issued. So the plug list will have one request at most */ @@ -1352,9 +1399,16 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) blk_mq_put_ctx(data.ctx); if (!old_rq) goto done; - if (blk_mq_hctx_stopped(data.hctx) || - blk_mq_direct_issue_request(old_rq, &cookie) != 0) - blk_mq_insert_request(old_rq, false, true, true); + + if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) { + rcu_read_lock(); + blk_mq_try_issue_directly(data.hctx, old_rq, &cookie); + rcu_read_unlock(); + } else { + srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu); + blk_mq_try_issue_directly(data.hctx, old_rq, &cookie); + srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx); + } goto done; } @@ -1633,6 +1687,9 @@ static void blk_mq_exit_hctx(struct request_queue *q, if (set->ops->exit_hctx) set->ops->exit_hctx(hctx, hctx_idx); + if (hctx->flags & BLK_MQ_F_BLOCKING) + cleanup_srcu_struct(&hctx->queue_rq_srcu); + blk_mq_remove_cpuhp(hctx); blk_free_flush_queue(hctx->fq); sbitmap_free(&hctx->ctx_map); @@ -1713,6 +1770,9 @@ static int blk_mq_init_hctx(struct request_queue *q, flush_start_tag + hctx_idx, node)) goto free_fq; + if (hctx->flags & BLK_MQ_F_BLOCKING) + init_srcu_struct(&hctx->queue_rq_srcu); + return 0; free_fq: diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 523376a..02c3918 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -3,6 +3,7 @@ #include #include +#include struct blk_mq_tags; struct blk_flush_queue; @@ -35,6 +36,8 @@ struct blk_mq_hw_ctx { struct blk_mq_tags *tags; + struct srcu_struct queue_rq_srcu; + unsigned long queued; unsigned long run; #define BLK_MQ_MAX_DISPATCH_ORDER 7 diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index c47c358..8259d87 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -824,6 +824,7 @@ extern void __blk_run_queue(struct request_queue *q); extern void __blk_run_queue_uncond(struct request_queue *q); extern void blk_run_queue(struct request_queue *); extern void blk_run_queue_async(struct request_queue *q); +extern void blk_mq_quiesce_queue(struct request_queue *q); extern int blk_rq_map_user(struct request_queue *, struct request *, struct rq_map_data *, void __user *, unsigned long, gfp_t); -- 2.10.1 From mboxrd@z Thu Jan 1 00:00:00 1970 From: bart.vanassche@sandisk.com (Bart Van Assche) Date: Tue, 18 Oct 2016 14:50:25 -0700 Subject: [PATCH v3 04/11] blk-mq: Introduce blk_mq_quiesce_queue() In-Reply-To: References: Message-ID: blk_mq_quiesce_queue() waits until ongoing .queue_rq() invocations have finished. This function does *not* wait until all outstanding requests have finished (this means invocation of request.end_io()). Signed-off-by: Bart Van Assche Cc: Ming Lei Cc: Hannes Reinecke Cc: Johannes Thumshirn --- block/blk-mq.c | 78 ++++++++++++++++++++++++++++++++++++++++++++------ include/linux/blk-mq.h | 3 ++ include/linux/blkdev.h | 1 + 3 files changed, 73 insertions(+), 9 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 4643fa8..d41ed92 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -115,6 +115,30 @@ void blk_mq_unfreeze_queue(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue); +/** + * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished + * + * Note: this function does not prevent that the struct request end_io() + * callback function is invoked. Additionally, it is not prevented that + * new queue_rq() calls occur unless the queue has been stopped first. + */ +void blk_mq_quiesce_queue(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + bool rcu = false; + + queue_for_each_hw_ctx(q, hctx, i) { + if (hctx->flags & BLK_MQ_F_BLOCKING) + synchronize_srcu(&hctx->queue_rq_srcu); + else + rcu = true; + } + if (rcu) + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue); + void blk_mq_wake_waiters(struct request_queue *q) { struct blk_mq_hw_ctx *hctx; @@ -778,7 +802,7 @@ static inline unsigned int queued_to_index(unsigned int queued) * of IO. In particular, we'd like FIFO behaviour on handling existing * items on the hctx->dispatch list. Ignore that for now. */ -static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) +static void blk_mq_process_rq_list(struct blk_mq_hw_ctx *hctx) { struct request_queue *q = hctx->queue; struct request *rq; @@ -790,9 +814,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) if (unlikely(blk_mq_hctx_stopped(hctx))) return; - WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) && - cpu_online(hctx->next_cpu)); - hctx->run++; /* @@ -883,6 +904,24 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) } } +static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) +{ + int srcu_idx; + + WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) && + cpu_online(hctx->next_cpu)); + + if (!(hctx->flags & BLK_MQ_F_BLOCKING)) { + rcu_read_lock(); + blk_mq_process_rq_list(hctx); + rcu_read_unlock(); + } else { + srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu); + blk_mq_process_rq_list(hctx); + srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx); + } +} + /* * It'd be great if the workqueue API had a way to pass * in a mask and had some smarts for more clever placement. @@ -1278,6 +1317,14 @@ static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie) return -1; } +static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, + struct request *rq, blk_qc_t *cookie) +{ + if (blk_mq_hctx_stopped(hctx) || + blk_mq_direct_issue_request(rq, cookie) != 0) + blk_mq_insert_request(rq, false, true, true); +} + /* * Multiple hardware queue variant. This will not use per-process plugs, * but will attempt to bypass the hctx queueing if we can go straight to @@ -1289,7 +1336,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA); struct blk_map_ctx data; struct request *rq; - unsigned int request_count = 0; + unsigned int request_count = 0, srcu_idx; struct blk_plug *plug; struct request *same_queue_rq = NULL; blk_qc_t cookie; @@ -1332,7 +1379,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) blk_mq_bio_to_request(rq, bio); /* - * We do limited pluging. If the bio can be merged, do that. + * We do limited plugging. If the bio can be merged, do that. * Otherwise the existing request in the plug list will be * issued. So the plug list will have one request at most */ @@ -1352,9 +1399,16 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) blk_mq_put_ctx(data.ctx); if (!old_rq) goto done; - if (blk_mq_hctx_stopped(data.hctx) || - blk_mq_direct_issue_request(old_rq, &cookie) != 0) - blk_mq_insert_request(old_rq, false, true, true); + + if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) { + rcu_read_lock(); + blk_mq_try_issue_directly(data.hctx, old_rq, &cookie); + rcu_read_unlock(); + } else { + srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu); + blk_mq_try_issue_directly(data.hctx, old_rq, &cookie); + srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx); + } goto done; } @@ -1633,6 +1687,9 @@ static void blk_mq_exit_hctx(struct request_queue *q, if (set->ops->exit_hctx) set->ops->exit_hctx(hctx, hctx_idx); + if (hctx->flags & BLK_MQ_F_BLOCKING) + cleanup_srcu_struct(&hctx->queue_rq_srcu); + blk_mq_remove_cpuhp(hctx); blk_free_flush_queue(hctx->fq); sbitmap_free(&hctx->ctx_map); @@ -1713,6 +1770,9 @@ static int blk_mq_init_hctx(struct request_queue *q, flush_start_tag + hctx_idx, node)) goto free_fq; + if (hctx->flags & BLK_MQ_F_BLOCKING) + init_srcu_struct(&hctx->queue_rq_srcu); + return 0; free_fq: diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 523376a..02c3918 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -3,6 +3,7 @@ #include #include +#include struct blk_mq_tags; struct blk_flush_queue; @@ -35,6 +36,8 @@ struct blk_mq_hw_ctx { struct blk_mq_tags *tags; + struct srcu_struct queue_rq_srcu; + unsigned long queued; unsigned long run; #define BLK_MQ_MAX_DISPATCH_ORDER 7 diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index c47c358..8259d87 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -824,6 +824,7 @@ extern void __blk_run_queue(struct request_queue *q); extern void __blk_run_queue_uncond(struct request_queue *q); extern void blk_run_queue(struct request_queue *); extern void blk_run_queue_async(struct request_queue *q); +extern void blk_mq_quiesce_queue(struct request_queue *q); extern int blk_rq_map_user(struct request_queue *, struct request *, struct rq_map_data *, void __user *, unsigned long, gfp_t); -- 2.10.1