[PATCH 6.19 358/781] dm: use bio_clone_blkg_association

Greg Kroah-Hartman
2026-02-25T01:33:29Z

From: Mikulas Patocka <mpatocka@redhat.com>

[ Upstream commit 2df8b310bcfe76827fd71092f58a2493ee6590b0 ]

The origin bio carries blk-cgroup information which could be set from
foreground(task_css(css) - wbc->wb->blkcg_css), so the blkcg won't
control buffer io since commit ca522482e3eaf ("dm: pass NULL bdev to
bio_alloc_clone"). The synchronous io is still under control by blkcg,
because 'bio->bi_blkg' is set by io submitting task which has been added
into 'cgroup.procs'.

Fix it by using bio_clone_blkg_association when submitting a cloned bio.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=220985
Fixes: ca522482e3eaf ("dm: pass NULL bdev to bio_alloc_clone")
Reported-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Tested-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b632792022601..8e029f6289c10 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1364,6 +1364,8 @@ void dm_submit_bio_remap(struct bio *clone, struct bio *tgt_clone)
if (!tgt_clone)
tgt_clone = clone;

+ bio_clone_blkg_association(tgt_clone, io->orig_bio);
+
/*
* Account io->origin_bio to DM dev on behalf of target
* that took ownership of IO with DM_MAPIO_SUBMITTED.
--
2.51.0