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Date:   Tue, 26 Sep 2023 16:01:50 +0200
From:   Christian Brauner <brauner@kernel.org>
To:     Mateusz Guzik <mjguzik@gmail.com>
Cc:     viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org
Subject: Re: [PATCH] vfs: shave work on failed file open
Message-ID: <20230926-anforderungen-obgleich-47e465f0bd47@brauner>
References: <20230925205545.4135472-1-mjguzik@gmail.com>
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In-Reply-To: <20230925205545.4135472-1-mjguzik@gmail.com>
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> +void fput_badopen(struct file *file)
> +{
> +	if (unlikely(file->f_mode & (FMODE_BACKING | FMODE_OPENED))) {
> +		fput(file);
> +		return;
> +	}
> +
> +	if (WARN_ON(atomic_long_read(&file->f_count) != 1)) {
> +		fput(file);
> +		return;
> +	}
> +
> +	/* zero out the ref count to appease possible asserts */
> +	atomic_long_set(&file->f_count, 0);

Afaict this could just be:

if (WARN_ON_ONCE(atomic_long_cmpxchg(&file->f_count, 1, 0) != 1)) {

> +	file_free_badopen(file);
> +}
> +EXPORT_SYMBOL(fput_badopen);

Should definitely not be exported and only be available to core vfs
code. So this should go into fs/internal.h.