From 2b9a4dc9df515e5f28f7b3de03203f5b31e01f47 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 17 May 2023 10:42:27 -0700 Subject: [PATCH] FROMGIT: block: mq-deadline: Track the dispatch position Track the position (sector_t) of the most recently dispatched request instead of tracking a pointer to the next request to dispatch. This patch is the basis for patch "Handle requeued requests correctly". Without this patch it would be significantly more complicated to make sure that zoned writes are dispatched in LBA order per zone. Reviewed-by: Christoph Hellwig Reviewed-by: Damien Le Moal Cc: Ming Lei Change-Id: I7ea38c43ae4e80b3a2257b631b58754c60aff4df Signed-off-by: Bart Van Assche Link: https://lore.kernel.org/r/20230517174230.897144-10-bvanassche@acm.org Signed-off-by: Jens Axboe Bug: 275581839 (cherry picked from commit 83c46ed675579fe84354bd07b0d81b525a2b1ebb https://git.kernel.dk/cgit/linux/) Signed-off-by: Bart Van Assche --- block/mq-deadline.c | 45 +++++++++++++++++++++++++++++++-------------- 1 file changed, 31 insertions(+), 14 deletions(-) diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 3978555d959b..765a4faada22 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -76,8 +76,8 @@ struct dd_per_prio { struct list_head dispatch; struct rb_root sort_list[DD_DIR_COUNT]; struct list_head fifo_list[DD_DIR_COUNT]; - /* Next request in FIFO order. Read, write or both are NULL. */ - struct request *next_rq[DD_DIR_COUNT]; + /* Position of the most recently dispatched request. */ + sector_t latest_pos[DD_DIR_COUNT]; struct io_stats_per_prio stats; }; @@ -158,6 +158,25 @@ deadline_latter_request(struct request *rq) return NULL; } +/* Return the first request for which blk_rq_pos() >= pos. */ +static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio, + enum dd_data_dir data_dir, sector_t pos) +{ + struct rb_node *node = per_prio->sort_list[data_dir].rb_node; + struct request *rq, *res = NULL; + + while (node) { + rq = rb_entry_rq(node); + if (blk_rq_pos(rq) >= pos) { + res = rq; + node = node->rb_left; + } else { + node = node->rb_right; + } + } + return res; +} + static void deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq) { @@ -169,11 +188,6 @@ deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq) static inline void deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq) { - const enum dd_data_dir data_dir = rq_data_dir(rq); - - if (per_prio->next_rq[data_dir] == rq) - per_prio->next_rq[data_dir] = deadline_latter_request(rq); - elv_rb_del(deadline_rb_root(per_prio, rq), rq); } @@ -253,10 +267,6 @@ static void deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio, struct request *rq) { - const enum dd_data_dir data_dir = rq_data_dir(rq); - - per_prio->next_rq[data_dir] = deadline_latter_request(rq); - /* * take it off the sort and fifo list */ @@ -366,7 +376,8 @@ deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio, struct request *rq; unsigned long flags; - rq = per_prio->next_rq[data_dir]; + rq = deadline_from_pos(per_prio, data_dir, + per_prio->latest_pos[data_dir]); if (!rq) return NULL; @@ -430,6 +441,7 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, if (started_after(dd, rq, latest_start)) return NULL; list_del_init(&rq->queuelist); + data_dir = rq_data_dir(rq); goto done; } @@ -437,9 +449,11 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, * batches are currently reads XOR writes */ rq = deadline_next_request(dd, per_prio, dd->last_dir); - if (rq && dd->batching < dd->fifo_batch) + if (rq && dd->batching < dd->fifo_batch) { /* we have a next request and are still entitled to batch */ + data_dir = rq_data_dir(rq); goto dispatch_request; + } /* * at this point we are not running a batch. select the appropriate @@ -518,6 +532,7 @@ dispatch_request: done: ioprio_class = dd_rq_ioclass(rq); prio = ioprio_class_to_prio[ioprio_class]; + dd->per_prio[prio].latest_pos[data_dir] = blk_rq_pos(rq); dd->per_prio[prio].stats.dispatched++; /* * If the request needs its target zone locked, do it. @@ -1028,8 +1043,10 @@ static int deadline_##name##_next_rq_show(void *data, \ struct request_queue *q = data; \ struct deadline_data *dd = q->elevator->elevator_data; \ struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ - struct request *rq = per_prio->next_rq[data_dir]; \ + struct request *rq; \ \ + rq = deadline_from_pos(per_prio, data_dir, \ + per_prio->latest_pos[data_dir]); \ if (rq) \ __blk_mq_debugfs_rq_show(m, rq); \ return 0; \