From dece16353ef47d8d33f5302bc158072a9d65e26f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 5 Nov 2015 10:41:16 -0700 Subject: block: change ->make_request_fn() and users to return a queue cookie No functional changes in this patch, but it prepares us for returning a more useful cookie related to the IO that was queued up. Signed-off-by: Jens Axboe Acked-by: Christoph Hellwig Acked-by: Keith Busch --- block/blk-core.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'block/blk-core.c') diff --git a/block/blk-core.c b/block/blk-core.c index 89eec7965870..e93df6d386a0 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -809,7 +809,7 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) } EXPORT_SYMBOL(blk_init_queue_node); -static void blk_queue_bio(struct request_queue *q, struct bio *bio); +static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio); struct request_queue * blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, @@ -1678,7 +1678,7 @@ void init_request_from_bio(struct request *req, struct bio *bio) blk_rq_bio_prep(req->q, req, bio); } -static void blk_queue_bio(struct request_queue *q, struct bio *bio) +static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio) { const bool sync = !!(bio->bi_rw & REQ_SYNC); struct blk_plug *plug; @@ -1698,7 +1698,7 @@ static void blk_queue_bio(struct request_queue *q, struct bio *bio) if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) { bio->bi_error = -EIO; bio_endio(bio); - return; + return BLK_QC_T_NONE; } if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { @@ -1713,7 +1713,7 @@ static void blk_queue_bio(struct request_queue *q, struct bio *bio) */ if (!blk_queue_nomerges(q)) { if (blk_attempt_plug_merge(q, bio, &request_count, NULL)) - return; + return BLK_QC_T_NONE; } else request_count = blk_plug_queued_count(q); @@ -1791,6 +1791,8 @@ get_rq: out_unlock: spin_unlock_irq(q->queue_lock); } + + return BLK_QC_T_NONE; } /* @@ -1996,12 +1998,13 @@ end_io: * a lower device by calling into generic_make_request recursively, which * means the bio should NOT be touched after the call to ->make_request_fn. */ -void generic_make_request(struct bio *bio) +blk_qc_t generic_make_request(struct bio *bio) { struct bio_list bio_list_on_stack; + blk_qc_t ret = BLK_QC_T_NONE; if (!generic_make_request_checks(bio)) - return; + goto out; /* * We only want one ->make_request_fn to be active at a time, else @@ -2015,7 +2018,7 @@ void generic_make_request(struct bio *bio) */ if (current->bio_list) { bio_list_add(current->bio_list, bio); - return; + goto out; } /* following loop may be a bit non-obvious, and so deserves some @@ -2040,7 +2043,7 @@ void generic_make_request(struct bio *bio) if (likely(blk_queue_enter(q, __GFP_WAIT) == 0)) { - q->make_request_fn(q, bio); + ret = q->make_request_fn(q, bio); blk_queue_exit(q); @@ -2053,6 +2056,9 @@ void generic_make_request(struct bio *bio) } } while (bio); current->bio_list = NULL; /* deactivate */ + +out: + return ret; } EXPORT_SYMBOL(generic_make_request); @@ -2066,7 +2072,7 @@ EXPORT_SYMBOL(generic_make_request); * interfaces; @bio must be presetup and ready for I/O. * */ -void submit_bio(int rw, struct bio *bio) +blk_qc_t submit_bio(int rw, struct bio *bio) { bio->bi_rw |= rw; @@ -2100,7 +2106,7 @@ void submit_bio(int rw, struct bio *bio) } } - generic_make_request(bio); + return generic_make_request(bio); } EXPORT_SYMBOL(submit_bio); -- cgit v1.2.3 From 05229beeddf7e75e2e616ddaad4b70e7fca9528d Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 5 Nov 2015 10:44:55 -0700 Subject: block: add block polling support Add basic support for polling for specific IO to complete. This uses the cookie that blk-mq passes back, which enables the block layer to pass this cookie to the driver to spin for a specific request. This will be combined with request latency tracking, so we can make qualified decisions about when to poll and when not to. For now, for benchmark purposes, we add a sysfs file that controls whether polling is enabled or not. Signed-off-by: Jens Axboe Acked-by: Christoph Hellwig Acked-by: Keith Busch --- block/blk-core.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) (limited to 'block/blk-core.c') diff --git a/block/blk-core.c b/block/blk-core.c index e93df6d386a0..fa36b4ff7d63 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -3312,6 +3312,47 @@ void blk_finish_plug(struct blk_plug *plug) } EXPORT_SYMBOL(blk_finish_plug); +bool blk_poll(struct request_queue *q, blk_qc_t cookie) +{ + struct blk_plug *plug; + long state; + + if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) || + !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) + return false; + + plug = current->plug; + if (plug) + blk_flush_plug_list(plug, false); + + state = current->state; + while (!need_resched()) { + unsigned int queue_num = blk_qc_t_to_queue_num(cookie); + struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[queue_num]; + int ret; + + hctx->poll_invoked++; + + ret = q->mq_ops->poll(hctx, blk_qc_t_to_tag(cookie)); + if (ret > 0) { + hctx->poll_success++; + set_current_state(TASK_RUNNING); + return true; + } + + if (signal_pending_state(state, current)) + set_current_state(TASK_RUNNING); + + if (current->state == TASK_RUNNING) + return true; + if (ret < 0) + break; + cpu_relax(); + } + + return false; +} + #ifdef CONFIG_PM /** * blk_pm_runtime_init - Block layer runtime PM initialization routine -- cgit v1.2.3