From: Jens Axboe <[email protected]>
To: Mateusz Guzik <[email protected]>,
[email protected], [email protected]
Cc: [email protected], [email protected],
[email protected], [email protected],
[email protected]
Subject: Re: [PATCH] fs: dodge an atomic in putname if ref == 1
Date: Wed, 12 Mar 2025 10:07:21 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 3/11/25 12:18 PM, Mateusz Guzik wrote:
> diff --git a/fs/namei.c b/fs/namei.c
> index 06765d320e7e..add90981cfcd 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -275,14 +275,19 @@ EXPORT_SYMBOL(getname_kernel);
>
> void putname(struct filename *name)
> {
> + int refcnt;
> +
> if (IS_ERR_OR_NULL(name))
> return;
>
> - if (WARN_ON_ONCE(!atomic_read(&name->refcnt)))
> - return;
> + refcnt = atomic_read(&name->refcnt);
> + if (refcnt != 1) {
> + if (WARN_ON_ONCE(!refcnt))
> + return;
>
> - if (!atomic_dec_and_test(&name->refcnt))
> - return;
> + if (!atomic_dec_and_test(&name->refcnt))
> + return;
> + }
Looks good to me, I use this trick with bitops too all the time, to
avoid a RMW when possible.
Reviewed-by: Jens Axboe <[email protected]>
--
Jens Axboe
prev parent reply other threads:[~2025-03-12 16:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-11 18:18 [PATCH] fs: dodge an atomic in putname if ref == 1 Mateusz Guzik
2025-03-12 8:36 ` Christian Brauner
2025-03-12 15:51 ` Jan Kara
2025-03-12 16:07 ` Jens Axboe [this message]
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