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| author | Bart Van Assche <bvanassche@acm.org> | 2021-06-17 17:44:45 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-06-21 15:03:40 -0600 |
| commit | 46eae2e32a6adc368230b4df0501082c5233e99c (patch) | |
| tree | ae20bd8657c12065a77fff53b26910980e5eda38 | |
| parent | 556910e39249d55e23deaec479f49e7d85bc0d24 (diff) | |
| download | linux-stable-46eae2e32a6adc368230b4df0501082c5233e99c.tar.gz linux-stable-46eae2e32a6adc368230b4df0501082c5233e99c.tar.bz2 linux-stable-46eae2e32a6adc368230b4df0501082c5233e99c.zip | |
block/mq-deadline: Add several comments
Make the code easier to read by adding more comments.
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20210618004456.7280-6-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/mq-deadline.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 8eea2cbf2bf4..31418e9ce9e2 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -139,6 +139,9 @@ static void dd_request_merged(struct request_queue *q, struct request *req, } } +/* + * Callback function that is invoked after @next has been merged into @req. + */ static void dd_merged_requests(struct request_queue *q, struct request *req, struct request *next) { @@ -375,6 +378,8 @@ done: } /* + * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests(). + * * One confusing aspect here is that we get called for a specific * hardware queue, but we may return a request that is for a * different hardware queue. This is because mq-deadline has shared @@ -438,6 +443,10 @@ static int dd_init_queue(struct request_queue *q, struct elevator_type *e) return 0; } +/* + * Try to merge @bio into an existing request. If @bio has been merged into + * an existing request, store the pointer to that request into *@rq. + */ static int dd_request_merge(struct request_queue *q, struct request **rq, struct bio *bio) { @@ -461,6 +470,10 @@ static int dd_request_merge(struct request_queue *q, struct request **rq, return ELEVATOR_NO_MERGE; } +/* + * Attempt to merge a bio into an existing request. This function is called + * before @bio is associated with a request. + */ static bool dd_bio_merge(struct request_queue *q, struct bio *bio, unsigned int nr_segs) { @@ -518,6 +531,9 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, } } +/* + * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests(). + */ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, struct list_head *list, bool at_head) { @@ -544,6 +560,8 @@ static void dd_prepare_request(struct request *rq) } /* + * Callback from inside blk_mq_free_request(). + * * For zoned block devices, write unlock the target zone of * completed write requests. Do this while holding the zone lock * spinlock so that the zone is never unlocked while deadline_fifo_request() |