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Al Viro
00b3941910
[ Upstream commit 2a8061ee5e ]
We want a class that nests outside of I_MUTEX_NORMAL (for the sake of
callbacks that might want to lock the victim) and inside I_MUTEX_PARENT
(so that a variant of that could be used with parent of the victim
held locked by the caller).
In reality, simple_recursive_removal()
* never holds two locks at once
* holds the lock on parent of dentry passed to callback
* is used only on the trees with fixed topology, so the depths
are not changing.
So the locking order is actually fine.
AFAICS, the best solution is to assign I_MUTEX_CHILD to the locks
grabbed by that thing.
Reported-by: syzbot+169de184e9defe7fe709@syzkaller.appspotmail.com
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>