From: Yu Kuai Date: Sat, 7 Oct 2023 11:21:05 +0000 (+0800) Subject: md/raid1: don't split discard io for write behind X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9e55a22fce1384837c213274d1a3b93be16ed9d7;p=linux.git md/raid1: don't split discard io for write behind Currently, discad io is treated the same as normal write io, and for write behind case, io size is limited to: BIO_MAX_VECS * (PAGE_SIZE >> 9) For 0.5KB sector size and 4KB PAGE_SIZE, this is just 1MB. For consequence, if 'WriteMostly' is set to one of the underlying disks, then diskcard io will be splited into 1MB and it will take a long time for the diskcard to finish. Fix this problem by disable write behind for discard io. Reported-by: Roman Mamedov Closes: https://lore.kernel.org/all/6a1165f7-c792-c054-b8f0-1ad4f7b8ae01@ultracoder.org/ Reported-and-tested-by: Kirill Kirilenko Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231007112105.407449-1-yukuai1@huaweicloud.com --- diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 3a78f79ee6d5d..35d12948e0a96 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1345,6 +1345,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, int first_clone; int max_sectors; bool write_behind = false; + bool is_discard = (bio_op(bio) == REQ_OP_DISCARD); if (mddev_is_clustered(mddev) && md_cluster_ops->area_resyncing(mddev, WRITE, @@ -1405,7 +1406,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, * write-mostly, which means we could allocate write behind * bio later. */ - if (rdev && test_bit(WriteMostly, &rdev->flags)) + if (!is_discard && rdev && test_bit(WriteMostly, &rdev->flags)) write_behind = true; if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {