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md/raid1: restrict atomic write limits and handle runtime constraints

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Restrict the RAID1 atomic write limits by setting chunk_sectors to
BARRIER_UNIT_SECTOR_SIZE so that atomic writes never straddle a barrier
unit.

A bio that passes block-layer validation may still become unserviceable
within RAID1 due to bad blocks or write-behind constraints. In the former
case, complete the bio with EIO. In the latter case, disable
write-behind rather than failing the bio with EIO.

Fixes: f2a38abf5f ("md/raid1: Atomic write support")
Fixes: a4c55c9026 ("md/raid1: simplify raid1_write_request() error handling")
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Reviewed-by: Yu Kuai <yukuai@fygo.io>
Link: https://patch.msgid.link/20260710101521.1714-3-abd.masalkhi@gmail.com
Signed-off-by: Yu Kuai <yukuai@fygo.io>
This commit is contained in:
Abd-Alrhman Masalkhi 2026-07-10 10:15:16 +00:00 committed by Yu Kuai
parent c7d34d17ea
commit 86d801e895
1 changed files with 9 additions and 13 deletions
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22
drivers/md/raid1.c
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@ -1485,6 +1485,7 @@ static bool raid1_write_request(struct mddev *mddev, struct bio *bio,
unsigned long flags;
int first_clone;
bool write_behind = false;
bool atomic = bio->bi_opf & REQ_ATOMIC;
bool is_discard = op_is_discard(bio->bi_opf);
sector_t sector = bio->bi_iter.bi_sector;
@ -1531,6 +1532,8 @@ static bool raid1_write_request(struct mddev *mddev, struct bio *bio,
*/
if (!is_discard && rdev && test_bit(WriteMostly, &rdev->flags))
write_behind = true;
if (atomic && max_sectors > BIO_MAX_VECS * (PAGE_SIZE >> 9))
write_behind = false;
r1_bio->bios[i] = NULL;
if (!rdev || test_bit(Faulty, &rdev->flags))
@ -1556,19 +1559,6 @@ static bool raid1_write_request(struct mddev *mddev, struct bio *bio,
if (is_bad) {
int good_sectors;
/*
* We cannot atomically write this, so just
* error in that case. It could be possible to
* atomically write other mirrors, but the
* complexity of supporting that is not worth
* the benefit.
*/
if (bio->bi_opf & REQ_ATOMIC) {
bio->bi_status = BLK_STS_NOTSUPP;
bio_endio(bio);
goto err_dec_pending;
}
good_sectors = first_bad - sector;
if (good_sectors < max_sectors)
max_sectors = good_sectors;
@ -1589,6 +1579,11 @@ static bool raid1_write_request(struct mddev *mddev, struct bio *bio,
max_sectors = min_t(int, max_sectors,
BIO_MAX_VECS * (PAGE_SIZE >> 9));
if (max_sectors < bio_sectors(bio)) {
if (atomic) {
bio_io_error(bio);
goto err_dec_pending;
}
bio = bio_submit_split_bioset(bio, max_sectors,
&conf->bio_split);
if (!bio)
@ -3177,6 +3172,7 @@ static int raid1_set_limits(struct mddev *mddev)
md_init_stacking_limits(&lim);
lim.max_write_zeroes_sectors = 0;
lim.max_hw_wzeroes_unmap_sectors = 0;
lim.chunk_sectors = BARRIER_UNIT_SECTOR_SIZE;
lim.logical_block_size = mddev->logical_block_size;
lim.features |= BLK_FEAT_ATOMIC_WRITES;
lim.features |= BLK_FEAT_PCI_P2PDMA;