On 3/7/25 9:35 AM, Mateusz Guzik wrote:
> On Fri, Mar 7, 2025 at 5:32?PM Jens Axboe <axboe@xxxxxxxxx> wrote:
>>
>> On 3/7/25 9:25 AM, Mateusz Guzik wrote:
>>> On Fri, Mar 7, 2025 at 5:18?PM Jens Axboe <axboe@xxxxxxxxx> wrote:
>>>>
>>>>> +static inline void makeatomicname(struct filename *name)
>>>>> +{
>>>>> + VFS_BUG_ON(IS_ERR_OR_NULL(name));
>>>>> + /*
>>>>> + * The name can legitimately already be atomic if it was cached by audit.
>>>>> + * If switching the refcount to atomic, we need not to know we are the
>>>>> + * only non-atomic user.
>>>>> + */
>>>>> + VFS_BUG_ON(name->owner != current && !name->is_atomic);
>>>>> + /*
>>>>> + * Don't bother branching, this is a store to an already dirtied cacheline.
>>>>> + */
>>>>> + name->is_atomic = true;
>>>>> +}
>>>>
>>>> Should this not depend on audit being enabled? io_uring without audit is
>>>> fine.
>>>>
>>>
>>> I thought about it, but then I got worried about transitions from
>>> disabled to enabled -- will they suddenly start looking here? Should
>>> this test for audit_enabled, audit_dummy_context() or something else?
>>> I did not want to bother analyzing this.
>>
>> Let me take a look at it, the markings for when to switch atomic are not
>> accurate - it only really needs to happen for offload situations only,
>> and if audit is enabled and tracking. So I think we can great improve
>> upon this patch.
>>
>
> I aimed for this to be a NOP for io_uring, so to speak, specifically
> because I could not be arsed to deal with audit.
Hah I hear ya... But right now it seems to mark it atomic for any of the
fs based ops, which is not really necessary.
>>> I'll note though this would be an optimization on top of the current
>>> code, so I don't think it *blocks* the patch.
>>
>> Let's not go with something half-done if we can get it right the first
>> time.
>>
>
> Since you volunteered to sort this out, I'll be happy to wait.
I'll take a look start next week, don't think it should be too bad. You
already did 90% of the work.
--
Jens Axboe
