linux-kernel - Re: [PATCH v2 1/4] file: add fput and file_ref_put routines optimized for use when closing a fd

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Message-ID: <CAGudoHGXMzD-vpwgmT3_dejsPdG_sLxSRdhT25GeyyrNLxufdg@mail.gmail.com>
Date: Wed, 5 Mar 2025 13:40:03 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: Christian Brauner <brauner@...nel.org>
Cc: viro@...iv.linux.org.uk, jack@...e.cz, linux-kernel@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 1/4] file: add fput and file_ref_put routines optimized
 for use when closing a fd

On Wed, Mar 5, 2025 at 11:47 AM Christian Brauner <brauner@...nel.org> wrote:
>
> On Tue, Mar 04, 2025 at 07:35:03PM +0100, Mateusz Guzik wrote:
> > Vast majority of the time closing a file descriptor also operates on the
> > last reference, where a regular fput usage will result in 2 atomics.
> > This can be changed to only suffer 1.
> >
> > See commentary above file_ref_put_close() for more information.
> >
> > Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
> > ---
>
> I'm not enthused about the patches tbh because we end up with two new
> primivites and I really dislike so many new primitives with slightly
> different semantics. But it should at least all be kept private to fs/.
>

Caller-observable behavior is the same, so I don't think this is a big
deal. The intent was to keep this very much for vfs-internal usage.
The EXPORT thing was copy-pasto.

Anyhow, everyone interested can still just fput so this does not put
any burden on other people afaics. The few patched spots are very much
vfs-internal.

I sent v3 with the feedback addressed.

-- 
Mateusz Guzik <mjguzik gmail.com>