Re: [PATCH v4 0/2] fs, audit: Avoid excessive dput/dget in audit_context setup and reset paths

[Waiman Long <longman@redhat.com>]

On 3/5/26 4:46 PM, Christian Brauner wrote:
> On Sat, Feb 28, 2026 at 01:27:55PM -0500, Waiman Long wrote:
>>   v4:
>>    - Add ack and review tags
>>    - Simplify put_fs_pwd_pool() in patch 1 as suggested by Paul Moore
>>
>>   v3:
>>    - https://lore.kernel.org/lkml/20260206201918.1988344-1-longman@redhat.com/
>>
>> When the audit subsystem is enabled, it can do a lot of get_fs_pwd()
>> calls to get references to fs->pwd and then releasing those references
>> back with path_put() later. That may cause a lot of spinlock contention
>> on a single pwd's dentry lock because of the constant changes to the
>> reference count when there are many processes on the same working
>> directory actively doing open/close system calls. This can cause
>> noticeable performance regresssion when compared with the case where
>> the audit subsystem is turned off especially on systems with a lot of
>> CPUs which is becoming more common these days.
>>
>> This patch series aim to avoid this type of performance regression caused
>> by audit by adding a new set of fs_struct helpers to reduce unncessary
>> path_get() and path_put() calls and the audit code is modified to use
>> these new helpers.
> Tbh, the open-coding everywhere is really not very tasteful and makes me
> not want to do this at all. Ideally we'd have a better mechanism that
> avoids all this new spaghetti in various codepaths.
>
> In it's current form I don't find it palatable. I added a few cleanups
> on top that make it at least somewhat ok.

Thanks for the cleanup patches. They all look good to me.

Reviewed-by: Waiman Long <longman@redhat.com>