From c6699d6fe0ffe4d9fdc652d1acf5a94b4f9627ba Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 12 Oct 2021 13:12:16 +0200 Subject: blk-mq: factor out a "classic" poll helper Factor the code to do the classic full metal polling out of blk_poll into a separate blk_mq_poll_classic helper. Signed-off-by: Christoph Hellwig Reviewed-by: Sagi Grimberg Tested-by: Mark Wunderlich Link: https://lore.kernel.org/r/20211012111226.760968-7-hch@lst.de Signed-off-by: Jens Axboe --- block/blk-mq.c | 120 +++++++++++++++++++++++++++------------------------------ 1 file changed, 56 insertions(+), 64 deletions(-) (limited to 'block') diff --git a/block/blk-mq.c b/block/blk-mq.c index 35b2ab0a373a..636773056874 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -71,6 +71,14 @@ static inline struct blk_mq_hw_ctx *blk_qc_to_hctx(struct request_queue *q, return q->queue_hw_ctx[(qc & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT]; } +static inline struct request *blk_qc_to_rq(struct blk_mq_hw_ctx *hctx, + blk_qc_t qc) +{ + if (blk_qc_t_is_internal(qc)) + return blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(qc)); + return blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(qc)); +} + /* * Check if any of the ctx, dispatch list or elevator * have pending work in this hardware queue. @@ -3975,15 +3983,20 @@ static unsigned long blk_mq_poll_nsecs(struct request_queue *q, return ret; } -static bool blk_mq_poll_hybrid_sleep(struct request_queue *q, - struct request *rq) +static bool blk_mq_poll_hybrid(struct request_queue *q, blk_qc_t qc) { + struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, qc); + struct request *rq = blk_qc_to_rq(hctx, qc); struct hrtimer_sleeper hs; enum hrtimer_mode mode; unsigned int nsecs; ktime_t kt; - if (rq->rq_flags & RQF_MQ_POLL_SLEPT) + /* + * If a request has completed on queue that uses an I/O scheduler, we + * won't get back a request from blk_qc_to_rq. + */ + if (!rq || (rq->rq_flags & RQF_MQ_POLL_SLEPT)) return false; /* @@ -4025,32 +4038,48 @@ static bool blk_mq_poll_hybrid_sleep(struct request_queue *q, __set_current_state(TASK_RUNNING); destroy_hrtimer_on_stack(&hs.timer); + + /* + * If we sleep, have the caller restart the poll loop to reset the + * state. Like for the other success return cases, the caller is + * responsible for checking if the IO completed. If the IO isn't + * complete, we'll get called again and will go straight to the busy + * poll loop. + */ return true; } -static bool blk_mq_poll_hybrid(struct request_queue *q, - struct blk_mq_hw_ctx *hctx, blk_qc_t cookie) +static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie, + bool spin) { - struct request *rq; + struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, cookie); + long state = get_current_state(); + int ret; - if (q->poll_nsec == BLK_MQ_POLL_CLASSIC) - return false; + hctx->poll_considered++; - if (!blk_qc_t_is_internal(cookie)) - rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie)); - else { - rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie)); - /* - * With scheduling, if the request has completed, we'll - * get a NULL return here, as we clear the sched tag when - * that happens. The request still remains valid, like always, - * so we should be safe with just the NULL check. - */ - if (!rq) - return false; - } + do { + hctx->poll_invoked++; - return blk_mq_poll_hybrid_sleep(q, rq); + ret = q->mq_ops->poll(hctx); + if (ret > 0) { + hctx->poll_success++; + __set_current_state(TASK_RUNNING); + return ret; + } + + if (signal_pending_state(state, current)) + __set_current_state(TASK_RUNNING); + if (task_is_running(current)) + return 1; + + if (ret < 0 || !spin) + break; + cpu_relax(); + } while (!need_resched()); + + __set_current_state(TASK_RUNNING); + return 0; } /** @@ -4067,9 +4096,6 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, */ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) { - struct blk_mq_hw_ctx *hctx; - unsigned int state; - if (!blk_qc_t_valid(cookie) || !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) return 0; @@ -4077,46 +4103,12 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) if (current->plug) blk_flush_plug_list(current->plug, false); - hctx = blk_qc_to_hctx(q, cookie); - - /* - * If we sleep, have the caller restart the poll loop to reset - * the state. Like for the other success return cases, the - * caller is responsible for checking if the IO completed. If - * the IO isn't complete, we'll get called again and will go - * straight to the busy poll loop. If specified not to spin, - * we also should not sleep. - */ - if (spin && blk_mq_poll_hybrid(q, hctx, cookie)) - return 1; - - hctx->poll_considered++; - - state = get_current_state(); - do { - int ret; - - hctx->poll_invoked++; - - ret = q->mq_ops->poll(hctx); - if (ret > 0) { - hctx->poll_success++; - __set_current_state(TASK_RUNNING); - return ret; - } - - if (signal_pending_state(state, current)) - __set_current_state(TASK_RUNNING); - - if (task_is_running(current)) + /* If specified not to spin, we also should not sleep. */ + if (spin && q->poll_nsec != BLK_MQ_POLL_CLASSIC) { + if (blk_mq_poll_hybrid(q, cookie)) return 1; - if (ret < 0 || !spin) - break; - cpu_relax(); - } while (!need_resched()); - - __set_current_state(TASK_RUNNING); - return 0; + } + return blk_mq_poll_classic(q, cookie, spin); } EXPORT_SYMBOL_GPL(blk_poll); -- cgit v1.2.3