Re: [PATCH 2/2] userns: don't clear the install target map on map_write() failure

[Tao Cui]

在 2026/8/31 18:08, Christian Brauner 写道:
> On Fri, Aug 28, 2026 at 11:51:10AM +0200, Jan Kara wrote:
>> On Fri 28-08-26 17:16:59, Tao Cui wrote:
>>> From: Tao Cui <cuitao@xxxxxxxxxx>
>>>
>>> At the out: label of map_write() the destination map is also cleared
>>> (map->forward = NULL; map->reverse = NULL; map->nr_extents = 0)
>>> whenever the write failed and the extent arrays had to be freed.
>>>
>>> However, the destination map is written by the successful install
>>> block above, which has no failure exit; every error path reaches
>>> out: without having touched it.  A second write to a mapped
>>> namespace is also rejected with -EPERM before any parsing happens,
>>> so the clearing can never roll back a previously installed map
>>> either.
>>>
>>> The three assignments just zero an already-zero map.  Remove them.
>>>
>>> Signed-off-by: Tao Cui <cuitao@xxxxxxxxxx>
>>
>> I agree this is a dead code but it kind of makes it easier to argue about
>> the correctness of the error handling branch. I guess I'll leave it to for
>> Christian to decide whether he wants to take this or not.
> 
> Nah, let's leave this as is. :)

Understood, that's a fair point.  I'm fine dropping this one.

Thanks for the review, Jan.  Thanks for picking up 1/2, Christian.
And thanks for the Reviewed-by tag, Bradley.

--
Tao