linux-kernel - Re: [PATCH] fs: use __fput

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Date:   Tue, 08 Aug 2023 12:48:05 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Christian Brauner <brauner@...nel.org>,
        Mateusz Guzik <mjguzik@...il.com>, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        oleg@...hat.com, Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH] fs: use __fput_sync in close(2)

Linus Torvalds <torvalds@...ux-foundation.org> writes:

> On Tue, 8 Aug 2023 at 10:15, Christian Brauner <brauner@...nel.org> wrote:
>>
>> I think you're at least missing the removal of the PF_KTHREAD check
>
> Yup.
>
>>                 It'd be neat to leave that in so
>> __fput_sync() doesn't get proliferated to non PF_KTHREAD without us
>> noticing. So maybe we just need a tiny primitive.
>
> Considering that over the decade we've had this, we've only grown two
> cases of actually using it, I think we're fine.

That and two cases of flush_delayed_fput() followed by task_work_run().

That combined with a maintainer who was actively against any new
calls to __fput_sync and a version of __fput_sync that called BUG_ON
if you used it.

So I am not 100% convinced that there were so few calls to __fput_sync
simply because people couldn't think of a need for it.

Eric