From jefflexu@linux.alibaba.com Wed Mar 3 06:58:04 2021 Date: Wed, 3 Mar 2021 19:57:31 +0800 From: Jeffle Xu To: msnitzer@redhat.com, axboe@kernel.dk Cc: io-uring@vger.kernel.org, dm-devel@redhat.com, linux-block@vger.kernel.org, mpatocka@redhat.com, caspar@linux.alibaba.com, joseph.qi@linux.alibaba.com Subject: [PATCH v5 03/12] block: add poll method to support bio-based IO polling ->poll_fn was introduced in commit ea435e1b9392 ("block: add a poll_fn callback to struct request_queue") to support bio-based queues such as nvme multipath, but was later removed in commit 529262d56dbe ("block: remove ->poll_fn"). Given commit c62b37d96b6e ("block: move ->make_request_fn to struct block_device_operations") restore the possibility of bio-based IO polling support by adding an ->poll method to gendisk->fops. Make blk_mq_poll() specific to blk-mq, while blk_bio_poll() is originally a copy from blk_mq_poll(), and is specific to bio-based polling. Currently hybrid polling is not supported by bio-based polling. Signed-off-by: Jeffle Xu --- block/blk-core.c | 58 ++++++++++++++++++++++++++++++++++++++++++ block/blk-mq.c | 22 +--------------- include/linux/blk-mq.h | 1 + include/linux/blkdev.h | 1 + 4 files changed, 61 insertions(+), 21 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index fc60ff208497..6d7d53030d7c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1119,6 +1119,64 @@ blk_qc_t submit_bio(struct bio *bio) } EXPORT_SYMBOL(submit_bio); + +static int blk_bio_poll(struct request_queue *q, blk_qc_t cookie, bool spin) +{ + long state; + struct gendisk *disk = queue_to_disk(q); + + state = current->state; + do { + int ret; + + ret = disk->fops->poll(q, cookie); + if (ret > 0) { + __set_current_state(TASK_RUNNING); + return ret; + } + + if (signal_pending_state(state, current)) + __set_current_state(TASK_RUNNING); + + if (current->state == TASK_RUNNING) + return 1; + if (ret < 0 || !spin) + break; + cpu_relax(); + } while (!need_resched()); + + __set_current_state(TASK_RUNNING); + return 0; +} + +/** + * 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. 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, bool spin) +{ + if (!blk_qc_t_valid(cookie) || + !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) + return 0; + + if (current->plug) + blk_flush_plug_list(current->plug, false); + + if (queue_is_mq(q)) + return blk_mq_poll(q, cookie, spin); + else + return blk_bio_poll(q, cookie, spin); +} +EXPORT_SYMBOL_GPL(blk_poll); + /** * blk_cloned_rq_check_limits - Helper function to check a cloned request * for the new queue limits diff --git a/block/blk-mq.c b/block/blk-mq.c index d4d7c1caa439..214fa30b460a 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3852,30 +3852,11 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, return blk_mq_poll_hybrid_sleep(q, rq); } -/** - * 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. 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, bool spin) +int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin) { struct blk_mq_hw_ctx *hctx; long state; - if (!blk_qc_t_valid(cookie) || - !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) - return 0; - - if (current->plug) - blk_flush_plug_list(current->plug, false); - hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; /* @@ -3917,7 +3898,6 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) __set_current_state(TASK_RUNNING); return 0; } -EXPORT_SYMBOL_GPL(blk_poll); unsigned int blk_mq_rq_cpu(struct request *rq) { diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 2c473c9b8990..6a7b693b9917 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -615,6 +615,7 @@ static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio, } blk_qc_t blk_mq_submit_bio(struct bio *bio); +int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin); void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, struct lock_class_key *key); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index b81a9fe015ab..9dc83c30e7bc 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1866,6 +1866,7 @@ static inline void blk_ksm_unregister(struct request_queue *q) { } struct block_device_operations { blk_qc_t (*submit_bio) (struct bio *bio); + int (*poll)(struct request_queue *q, blk_qc_t cookie); int (*open) (struct block_device *, fmode_t); void (*release) (struct gendisk *, fmode_t); int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int); -- 2.27.0