From 7244851b406749561344f0d9093e1a2c1b825ebd Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 26 Nov 2018 08:24:43 -0700 Subject: [PATCH] block: make blk_poll() take a parameter on whether to spin or not commit 0a1b8b87d064a47fad9ec475316002da28559207 upstream. blk_poll() has always kept spinning until it found an IO. This is fine for SYNC polling, since we need to find one request we have pending, but in preparation for ASYNC polling it can be beneficial to just check if we have any entries available or not. Existing callers are converted to pass in 'spin == true', to retain the old behavior. Signed-off-by: Jens Axboe Signed-off-by: Joseph Qi Reviewed-by: Xiaoguang Wang Acked-by: Caspar Zhang --- block/blk-core.c | 9 ++++++--- block/blk-mq.c | 6 +++--- drivers/nvme/host/multipath.c | 4 ++-- drivers/nvme/target/io-cmd-bdev.c | 2 +- fs/block_dev.c | 4 ++-- fs/direct-io.c | 2 +- fs/iomap.c | 2 +- include/linux/blkdev.h | 4 ++-- mm/page_io.c | 2 +- 9 files changed, 19 insertions(+), 16 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index dd5056c421eb..3d5892aab710 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2578,19 +2578,22 @@ EXPORT_SYMBOL(submit_bio); * blk_poll - poll for IO completions * @q: the queue * @cookie: cookie passed back at IO submission time + * @spin: whether to spin for completions * * Description: * Poll for completions on the passed in queue. Returns number of - * completed entries found. + * completed entries found. If @spin is true, then blk_poll will continue + * looping until at least one completion is found, unless the task is + * otherwise marked running (or we need to reschedule). */ -int blk_poll(struct request_queue *q, blk_qc_t cookie) +int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) { if (!q->poll_fn || !blk_qc_t_valid(cookie)) return 0; if (current->plug) blk_flush_plug_list(current->plug, false); - return q->poll_fn(q, cookie); + return q->poll_fn(q, cookie, spin); } EXPORT_SYMBOL_GPL(blk_poll); diff --git a/block/blk-mq.c b/block/blk-mq.c index a091e3e9d7b5..5fd8315b0d82 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -37,7 +37,7 @@ #include "blk-mq-sched.h" #include "blk-rq-qos.h" -static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie); +static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin); static void blk_mq_poll_stats_start(struct request_queue *q); static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb); @@ -3179,7 +3179,7 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, return blk_mq_poll_hybrid_sleep(q, hctx, rq); } -static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie) +static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin) { struct blk_mq_hw_ctx *hctx; long state; @@ -3219,7 +3219,7 @@ static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie) if (current->state == TASK_RUNNING) return 1; - if (ret < 0) + if (ret < 0 || !spin) break; cpu_relax(); } diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index cc44d5ea2e12..3b284574cb35 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -217,7 +217,7 @@ static blk_qc_t nvme_ns_head_make_request(struct request_queue *q, return ret; } -static int nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc) +static int nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc, bool spin) { struct nvme_ns_head *head = q->queuedata; struct nvme_ns *ns; @@ -227,7 +227,7 @@ static int nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc) srcu_idx = srcu_read_lock(&head->srcu); ns = srcu_dereference(head->current_path, &head->srcu); if (likely(ns && nvme_path_is_optimized(ns))) - found = ns->queue->poll_fn(q, qc); + found = ns->queue->poll_fn(q, qc, spin); srcu_read_unlock(&head->srcu, srcu_idx); return found; } diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c index 1096dd01ca22..4fc66336a4ea 100644 --- a/drivers/nvme/target/io-cmd-bdev.c +++ b/drivers/nvme/target/io-cmd-bdev.c @@ -108,7 +108,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req) cookie = submit_bio(bio); - blk_poll(bdev_get_queue(req->ns->bdev), cookie); + blk_poll(bdev_get_queue(req->ns->bdev), cookie, true); } static void nvmet_bdev_execute_flush(struct nvmet_req *req) diff --git a/fs/block_dev.c b/fs/block_dev.c index cc222471a6b8..c783f7b5e56f 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -255,7 +255,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, if (!READ_ONCE(bio.bi_private)) break; if (!(iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(bdev_get_queue(bdev), qc)) + !blk_poll(bdev_get_queue(bdev), qc, true)) io_schedule(); } __set_current_state(TASK_RUNNING); @@ -425,7 +425,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) break; if (!(iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(bdev_get_queue(bdev), qc)) + !blk_poll(bdev_get_queue(bdev), qc, true)) io_schedule(); } __set_current_state(TASK_RUNNING); diff --git a/fs/direct-io.c b/fs/direct-io.c index 8109855b5134..ec2fb6fe6d37 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -518,7 +518,7 @@ static struct bio *dio_await_one(struct dio *dio) dio->waiter = current; spin_unlock_irqrestore(&dio->bio_lock, flags); if (!(dio->iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(dio->bio_disk->queue, dio->bio_cookie)) + !blk_poll(dio->bio_disk->queue, dio->bio_cookie, true)) io_schedule(); /* wake up sets us TASK_RUNNING */ spin_lock_irqsave(&dio->bio_lock, flags); diff --git a/fs/iomap.c b/fs/iomap.c index 30ca354fb1b6..2cc38c922a7d 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -1963,7 +1963,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (!(iocb->ki_flags & IOCB_HIPRI) || !dio->submit.last_queue || !blk_poll(dio->submit.last_queue, - dio->submit.cookie)) + dio->submit.cookie, true)) io_schedule(); } __set_current_state(TASK_RUNNING); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 46215eb99d3f..4710e45984ab 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -317,7 +317,7 @@ struct blk_queue_ctx; typedef void (request_fn_proc) (struct request_queue *q); typedef blk_qc_t (make_request_fn) (struct request_queue *q, struct bio *bio); -typedef int (poll_q_fn) (struct request_queue *q, blk_qc_t); +typedef int (poll_q_fn) (struct request_queue *q, blk_qc_t, bool spin); typedef int (prep_rq_fn) (struct request_queue *, struct request *); typedef void (unprep_rq_fn) (struct request_queue *, struct request *); @@ -1033,7 +1033,7 @@ extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *, int blk_status_to_errno(blk_status_t status); blk_status_t errno_to_blk_status(int errno); -int blk_poll(struct request_queue *q, blk_qc_t cookie); +int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin); static inline struct request_queue *bdev_get_queue(struct block_device *bdev) { diff --git a/mm/page_io.c b/mm/page_io.c index 687517fce7d1..e0616fdb4b17 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -409,7 +409,7 @@ int swap_readpage(struct page *page, bool synchronous) if (!READ_ONCE(bio->bi_private)) break; - if (!blk_poll(disk->queue, qc)) + if (!blk_poll(disk->queue, qc, true)) break; } __set_current_state(TASK_RUNNING); -- GitLab