Currently rcu is used to protect iterating rdev from submit_flushes():
submit_flushes remove_and_add_spares
synchronize_rcu
pers->hot_remove_disk()
rcu_read_lock()
rdev_for_each_rcu
if (rdev->raid_disk >= 0)
rdev->radi_disk = -1;
atomic_inc(&rdev->nr_pending)
rcu_read_unlock()
bi = bio_alloc_bioset()
bi->bi_end_io = md_end_flush
bi->private = rdev
submit_bio
// issue io for removed rdev
Fix this problem by grabbing 'acive_io' before iterating rdev, make sure
that remove_and_add_spares() won't concurrent with submit_flushes().
Fixes: a2826aa92e ("md: support barrier requests on all personalities.")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231129020234.1586910-1-yukuai1@huaweicloud.com
fa2bbff7b0