linux-ext4 - Re: [PATCH v4 01/22] fs: Add generic_atomic_write_valid

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Message-ID: <20240612211040.GJ2764752@frogsfrogsfrogs>
Date: Wed, 12 Jun 2024 14:10:40 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: John Garry <john.g.garry@...cle.com>
Cc: axboe@...nel.dk, tytso@....edu, dchinner@...hat.com,
	viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.com,
	chandan.babu@...cle.com, hch@....de, linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-btrfs@...r.kernel.org,
	linux-erofs@...ts.ozlabs.org, linux-ext4@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org, gfs2@...ts.linux.dev,
	linux-xfs@...r.kernel.org, catherine.hoang@...cle.com,
	ritesh.list@...il.com, mcgrof@...nel.org,
	mikulas@...ax.karlin.mff.cuni.cz, agruenba@...hat.com,
	miklos@...redi.hu, martin.petersen@...cle.com
Subject: Re: [PATCH v4 01/22] fs: Add generic_atomic_write_valid_size()

On Fri, Jun 07, 2024 at 02:38:58PM +0000, John Garry wrote:
> Add a generic helper for FSes to validate that an atomic write is
> appropriately sized (along with the other checks).
> 
> Signed-off-by: John Garry <john.g.garry@...cle.com>
> ---
>  include/linux/fs.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 069cbab62700..e13d34f8c24e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3645,4 +3645,16 @@ bool generic_atomic_write_valid(loff_t pos, struct iov_iter *iter)
>  	return true;
>  }
>  
> +static inline
> +bool generic_atomic_write_valid_size(loff_t pos, struct iov_iter *iter,
> +				unsigned int unit_min, unsigned int unit_max)
> +{
> +	size_t len = iov_iter_count(iter);
> +
> +	if (len < unit_min || len > unit_max)
> +		return false;
> +
> +	return generic_atomic_write_valid(pos, iter);
> +}

Now that I look back at "fs: Initial atomic write support" I wonder why
not pass the iocb and the iov_iter instead of pos and the iov_iter?
And can these be collapsed into a single generic_atomic_write_checks()
function?

--D

> +
>  #endif /* _LINUX_FS_H */
> -- 
> 2.31.1
> 
>