diff options
| author | Li Nan <linan122@huawei.com> | 2024-09-19 14:30:48 +0800 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2024-10-17 11:35:36 -0700 |
| commit | 62ce0782bbacd32ec10292b9bdd127330e9b6968 (patch) | |
| tree | ccdbe69c2a7b6aac66e186454c945eb15105d2c0 /drivers/md | |
| parent | 42aafd8b48adac1c3b20fe5892b1b91b80c1a1e6 (diff) | |
md: ensure child flush IO does not affect origin bio->bi_status
When a flush is issued to an RAID array, a child flush IO is created and
issued for each member disk in the RAID array. Since commit b75197e86e6d
("md: Remove flush handling"), each child flush IO has been chained with
the original bio. As a result, the failure of any child IO could modify
the bi_status of the original bio, potentially impacting the upper-layer
filesystem.
Fix the issue by preventing child flush IO from altering the original
bio->bi_status as before. However, this design introduces a known
issue: in the event of a power failure, if a flush IO on a member
disk fails, the upper layers may not be informed. This issue is not easy
to fix and will not be addressed for the time being in this issue.
Fixes: b75197e86e6d ("md: Remove flush handling")
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240919063048.2887579-1-linan666@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/md.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 179ee4afe937..67108c397c5a 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -546,6 +546,26 @@ static int mddev_set_closing_and_sync_blockdev(struct mddev *mddev, int opener_n return 0; } +/* + * The only difference from bio_chain_endio() is that the current + * bi_status of bio does not affect the bi_status of parent. + */ +static void md_end_flush(struct bio *bio) +{ + struct bio *parent = bio->bi_private; + + /* + * If any flush io error before the power failure, + * disk data may be lost. + */ + if (bio->bi_status) + pr_err("md: %pg flush io error %d\n", bio->bi_bdev, + blk_status_to_errno(bio->bi_status)); + + bio_put(bio); + bio_endio(parent); +} + bool md_flush_request(struct mddev *mddev, struct bio *bio) { struct md_rdev *rdev; @@ -565,7 +585,9 @@ bool md_flush_request(struct mddev *mddev, struct bio *bio) new = bio_alloc_bioset(rdev->bdev, 0, REQ_OP_WRITE | REQ_PREFLUSH, GFP_NOIO, &mddev->bio_set); - bio_chain(new, bio); + new->bi_private = bio; + new->bi_end_io = md_end_flush; + bio_inc_remaining(bio); submit_bio(new); } |