md/raid10: fix a 'conf->barrier' leakage in raid10_takeover()

After commit b39f35ebe86d ("md: don't quiesce in mddev_suspend()"),
'conf->barrier' will be leaked in the case that raid10 takeover raid0:

level_store
 pers->takeover -> raid10_takeover
  raid10_takeover_raid0
   WRITE_ONCE(conf->barrier, 1)

mddev_suspend
// still raid0
mddev->pers = pers
// switch to raid10
mddev_resume
// resume without suspend

After the above commit, mddev_resume() will not decrease 'conf->barrier'
that is set in raid10_takeover_raid0().

Fix this problem by not setting 'conf->barrier' in raid10_takeover_raid0().

By the way, this problem is found while I'm trying to make
mddev_suspend/resume() to be independent from raid personalities. raid10
is the only personality to use reference count in the quiesce() callback
and this problem is only related to raid10.

Fixes: b39f35ebe86d ("md: don't quiesce in mddev_suspend()")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Link: https://lore.kernel.org/r/20230731022800.1424902-1-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 16aa9d7..7704a4c 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -4417,7 +4417,6 @@ static void *raid10_takeover_raid0(struct mddev *mddev, sector_t size, int devs)
                                rdev->new_raid_disk = rdev->raid_disk * 2;
                                rdev->sectors = size;
                        }
-               WRITE_ONCE(conf->barrier, 1);
        }
 
        return conf;