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md/raid5: split reshape bios before bitmap accounting

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RAID5 maps array sectors through different geometries before and after the
reshape position. During llbitmap reshape, md core cannot account one bio
against both geometries as a single bitmap range, because the old and new
bitmap mappings can cover different chunks.

Split bios that cross reshape_position before md_account_bio(), so the
bitmap only sees ranges that belong to one side of the reshape boundary.

mddev_bio_split_at_reshape_offset() uses bio_submit_split_bioset(), which
submits the remainder immediately and returns the front split bio. If that
front bio later has to wait for reshape, md_handle_request() must not retry
the original bio pointer, because after the split that pointer is the
already-submitted remainder. Track whether the split happened, clear the
temporary BLK_STS_RESOURCE status after the internal clone completion, and
resubmit the front bio directly after the reshape wait. Keep the old
return-false retry path for unsplit bios, where md_handle_request() still
owns the same bio.

Tested-by: Mykola Marzhan <mykola@meshstor.io>
Link: https://patch.msgid.link/20260802195038.164272-30-yukuai@kernel.org
Signed-off-by: Yu Kuai <yukuai@fygo.io>
This commit is contained in:
Yu Kuai 2026-08-03 03:50:38 +08:00
parent 816b25aca5
commit 661102bb87
1 changed files with 19 additions and 0 deletions
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19
drivers/md/raid5.c
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@ -6221,9 +6221,11 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
struct r5conf *conf = mddev->private;
const int rw = bio_data_dir(bi);
struct stripe_request_ctx *ctx;
struct bio *front_bio;
sector_t logical_sector;
enum stripe_result res;
int s, stripe_cnt;
bool split = false;
bool on_wq;
if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
@ -6257,6 +6259,18 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
return true;
}
front_bio = bi;
bi = mddev_bio_split_at_reshape_offset(mddev, bi, NULL,
&conf->bio_split);
if (!bi) {
if (rw == WRITE)
md_write_end(mddev);
return true;
}
if (bi != front_bio)
split = true;
front_bio = bi;
logical_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
bi->bi_next = NULL;
@ -6348,6 +6362,11 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
bio_endio(bi);
wait_for_completion(&done);
front_bio->bi_status = BLK_STS_OK;
if (split) {
submit_bio_noacct(front_bio);
return true;
}
return false;
}