From 9a42891c35d50a8472b42c61256867b4dfcc1941 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Wed, 22 May 2024 04:03:08 +0800 Subject: block: fix lost bio for plug enabled bio based device With the following two conditions, bio will be lost: 1) blk plug is not enabled, for example, __blkdev_direct_IO_simple() and __blkdev_direct_IO_async(); 2) bio plug is enabled, for example write IO for raid1/raid10 while bitmap is enabled; Root cause is that blk_finish_plug() will add the bio to curent->bio_list, while such bio will not be handled: __submit_bio_noacct current->bio_list = bio_list_on_stack; blk_start_plug do { dm_submit_bio md_handle_request raid10_write_request -> generate new bio for underlying disks raid1_add_bio_to_plug -> bio is added to plug } while ((bio = bio_list_pop(&bio_list_on_stack[0]))) -> previous bio are all handled blk_finish_plug raid10_unplug raid1_submit_write submit_bio_noacct if (current->bio_list) bio_list_add(¤t->bio_list[0], bio) -> add new bio current->bio_list = NULL -> new bio is lost Fix the problem by moving the plug into the while loop, so that current->bio_list will still be handled after blk_finish_plug(). By the way, enable plug for raid1/raid10 in this case will also prevent delay IO handling into daemon thread, which should also improve IO performance. Fixes: 060406c61c7c ("block: add plug while submitting IO") Reported-by: Changhui Zhong Closes: https://lore.kernel.org/all/CAGVVp+Xsmzy2G9YuEatfMT6qv1M--YdOCQ0g7z7OVmcTbBxQAg@mail.gmail.com/ Signed-off-by: Yu Kuai Tested-by: Changhui Zhong Link: https://lore.kernel.org/r/20240521200308.983986-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe --- block/blk-core.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'block/blk-core.c') diff --git a/block/blk-core.c b/block/blk-core.c index 01186333c88e..dd29d5465af6 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -613,9 +613,14 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q, static void __submit_bio(struct bio *bio) { + /* If plug is not used, add new plug here to cache nsecs time. */ + struct blk_plug plug; + if (unlikely(!blk_crypto_bio_prep(&bio))) return; + blk_start_plug(&plug); + if (!bio->bi_bdev->bd_has_submit_bio) { blk_mq_submit_bio(bio); } else if (likely(bio_queue_enter(bio) == 0)) { @@ -624,6 +629,8 @@ static void __submit_bio(struct bio *bio) disk->fops->submit_bio(bio); blk_queue_exit(disk->queue); } + + blk_finish_plug(&plug); } /* @@ -648,13 +655,11 @@ static void __submit_bio(struct bio *bio) static void __submit_bio_noacct(struct bio *bio) { struct bio_list bio_list_on_stack[2]; - struct blk_plug plug; BUG_ON(bio->bi_next); bio_list_init(&bio_list_on_stack[0]); current->bio_list = bio_list_on_stack; - blk_start_plug(&plug); do { struct request_queue *q = bdev_get_queue(bio->bi_bdev); @@ -688,23 +693,19 @@ static void __submit_bio_noacct(struct bio *bio) bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); - blk_finish_plug(&plug); current->bio_list = NULL; } static void __submit_bio_noacct_mq(struct bio *bio) { struct bio_list bio_list[2] = { }; - struct blk_plug plug; current->bio_list = bio_list; - blk_start_plug(&plug); do { __submit_bio(bio); } while ((bio = bio_list_pop(&bio_list[0]))); - blk_finish_plug(&plug); current->bio_list = NULL; } -- cgit v1.2.3