dm-raid: fix lockdep waring in "pers->hot_add_disk"

BugLink: https://bugs.launchpad.net/bugs/2065435

[ Upstream commit 95009ae ]

The lockdep assert is added by commit a448af2 ("md/raid10: remove
rcu protection to access rdev from conf") in print_conf(). And I didn't
notice that dm-raid is calling "pers->hot_add_disk" without holding
'reconfig_mutex'.

"pers->hot_add_disk" read and write many fields that is protected by
'reconfig_mutex', and raid_resume() already grab the lock in other
contex. Hence fix this problem by protecting "pers->host_add_disk"
with the lock.

Fixes: 9092c02 ("DM RAID: Add ability to restore transiently failed devices on resume")
Fixes: a448af2 ("md/raid10: remove rcu protection to access rdev from conf")
Cc: [email protected] # v6.7+
Signed-off-by: Yu Kuai <[email protected]>
Signed-off-by: Xiao Ni <[email protected]>
Acked-by: Mike Snitzer <[email protected]>
Signed-off-by: Song Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Manuel Diewald <[email protected]>
Signed-off-by: Roxana Nicolescu <[email protected]>

Author: YuKuai-huawei

drivers/md/dm-raid.c

@@ -4049,7 +4049,9 @@ static void raid_resume(struct dm_target *ti)
 		 * Take this opportunity to check whether any failed
 		 * devices are reachable again.
 		 */
+		mddev_lock_nointr(mddev);
 		attempt_restore_of_faulty_devices(rs);
+		mddev_unlock(mddev);
 	}
 
 	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {