linux-kernel - Re: [PATCH v3 2/4] ext4: Check for atomic writes support in write iter

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Message-ID: <20241031214218.GD21832@frogsfrogsfrogs>
Date: Thu, 31 Oct 2024 14:42:18 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>
Cc: linux-ext4@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
	Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>,
	John Garry <john.g.garry@...cle.com>,
	Ojaswin Mujoo <ojaswin@...ux.ibm.com>,
	Dave Chinner <david@...morbit.com>, linux-kernel@...r.kernel.org,
	linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v3 2/4] ext4: Check for atomic writes support in write
 iter

On Wed, Oct 30, 2024 at 09:27:39PM +0530, Ritesh Harjani (IBM) wrote:
> Let's validate the given constraints for atomic write request.
> Otherwise it will fail with -EINVAL. Currently atomic write is only
> supported on DIO, so for buffered-io it will return -EOPNOTSUPP.
> 
> Reviewed-by: John Garry <john.g.garry@...cle.com>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>

Looks decent,
Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> ---
>  fs/ext4/file.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index f14aed14b9cf..a7b9b9751a3f 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -692,6 +692,20 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	if (IS_DAX(inode))
>  		return ext4_dax_write_iter(iocb, from);
>  #endif
> +
> +	if (iocb->ki_flags & IOCB_ATOMIC) {
> +		size_t len = iov_iter_count(from);
> +		int ret;
> +
> +		if (len < EXT4_SB(inode->i_sb)->s_awu_min ||
> +		    len > EXT4_SB(inode->i_sb)->s_awu_max)
> +			return -EINVAL;
> +
> +		ret = generic_atomic_write_valid(iocb, from);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	if (iocb->ki_flags & IOCB_DIRECT)
>  		return ext4_dio_write_iter(iocb, from);
>  	else
> -- 
> 2.46.0
> 
>