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md: Fix missing release of 'active_io' for flush

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submit_flushes
 atomic_set(&mddev->flush_pending, 1);
 rdev_for_each_rcu(rdev, mddev)
  atomic_inc(&mddev->flush_pending);
  bi->bi_end_io = md_end_flush
  submit_bio(bi);
                        /* flush io is done first */
                        md_end_flush
                         if (atomic_dec_and_test(&mddev->flush_pending))
                          percpu_ref_put(&mddev->active_io)
                          -> active_io is not released

 if (atomic_dec_and_test(&mddev->flush_pending))
  -> missing release of active_io

For consequence, mddev_suspend() will wait for 'active_io' to be zero
forever.

Fix this problem by releasing 'active_io' in submit_flushes() if
'flush_pending' is decreased to zero.

Fixes: fa2bbff7b0 ("md: synchronize flush io with array reconfiguration")
Cc: stable@vger.kernel.org # v6.1+
Reported-by: Blazej Kucman <blazej.kucman@linux.intel.com>
Closes: https://lore.kernel.org/lkml/20240130172524.0000417b@linux.intel.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240201092559.910982-7-yukuai1@huaweicloud.com
This commit is contained in:
Yu Kuai 2024-02-01 17:25:51 +08:00 committed by Song Liu
parent 9f3fe29d77
commit 855678ed85
1 changed files with 5 additions and 1 deletions
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6
drivers/md/md.c
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@ -579,8 +579,12 @@ static void submit_flushes(struct work_struct *ws)
rcu_read_lock();
}
rcu_read_unlock();
if (atomic_dec_and_test(&mddev->flush_pending))
if (atomic_dec_and_test(&mddev->flush_pending)) {
/* The pair is percpu_ref_get() from md_flush_request() */
percpu_ref_put(&mddev->active_io);
queue_work(md_wq, &mddev->flush_work);
}
}
static void md_submit_flush_data(struct work_struct *ws)