[PATCH v2 3/3] md/raid1,raid10: fix bio accounting for split md cloned bios

Abd-Alrhman Masalkhi
2026-05-01T11:47:16Z

Use md_cloned_bio() to control bio accounting instead of relying
on r1bio_existed in raid1 or the io_accounting flag in raid10.

The previous logic does not reliably reflect whether a bio is an
md cloned bio. When a failed bio is split and resubmitted via
bio_submit_split_bioset() on the error path, this can lead to either
double accounting for md cloned bios, or missing accounting for bios
returned from bio_submit_split_bioset()

Fix this by using md_cloned_bio() to detect md cloned bios and
skip accounting accordingly.

Fixes: bb2a9acefaf9 ("md/raid1: switch to use md_account_bio() for io accounting")
Fixes: 820455238366 ("md/raid10: switch to use md_account_bio() for io accounting")
Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
---
This patch depends on patch 1.

Changes in v2:
- New patch.
---
drivers/md/raid1.c | 2 +-
drivers/md/raid10.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c52ecd38c163..dfaf34141325 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1396,7 +1396,7 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
}

r1_bio->read_disk = rdisk;
- if (!r1bio_existed) {
+ if (likely(!md_cloned_bio(mddev, bio))) {
md_account_bio(mddev, &bio);
r1_bio->master_bio = bio;
}
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 8c6fc398260e..93af7bbc9005 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1146,7 +1146,7 @@ static bool regular_request_wait(struct mddev *mddev, struct r10conf *conf,
}

static void raid10_read_request(struct mddev *mddev, struct bio *bio,
- struct r10bio *r10_bio, bool io_accounting)
+ struct r10bio *r10_bio)
{
struct r10conf *conf = mddev->private;
struct bio *read_bio;
@@ -1226,7 +1226,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
}
slot = r10_bio->read_slot;

- if (io_accounting) {
+ if (likely(!md_cloned_bio(mddev, bio))) {
md_account_bio(mddev, &bio);
r10_bio->master_bio = bio;
}
@@ -1552,7 +1552,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio, int sectors)
conf->geo.raid_disks);

if (bio_data_dir(bio) == READ)
- raid10_read_request(mddev, bio, r10_bio, true);
+ raid10_read_request(mddev, bio, r10_bio);
else
raid10_write_request(mddev, bio, r10_bio);
}
@@ -2872,7 +2872,7 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)

rdev_dec_pending(rdev, mddev);
r10_bio->state = 0;
- raid10_read_request(mddev, r10_bio->master_bio, r10_bio, false);
+ raid10_read_request(mddev, r10_bio->master_bio, r10_bio);
/*
* allow_barrier after re-submit to ensure no sync io
* can be issued while regular io pending.
--
2.43.0