linux-kernel - Re: [PATCH] xfs: Do not fallback to buffered-io for DIO atomic write

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Message-ID: <20241025183100.GN2386201@frogsfrogsfrogs>
Date: Fri, 25 Oct 2024 11:31:00 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>
Cc: linux-xfs@...r.kernel.org, Christoph Hellwig <hch@...radead.org>,
	John Garry <john.g.garry@...cle.com>,
	Ojaswin Mujoo <ojaswin@...ux.ibm.com>,
	Dave Chinner <david@...morbit.com>,
	Carlos Maiolino <cem@...nel.org>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] xfs: Do not fallback to buffered-io for DIO atomic write

On Fri, Oct 25, 2024 at 11:48:05PM +0530, Ritesh Harjani (IBM) wrote:
> iomap can return -ENOTBLK if pagecache invalidation fails.
> Let's make sure if -ENOTBLK is ever returned for atomic
> writes than we fail the write request (-EIO) instead of
> fallback to buffered-io.
> 
> Suggested-by: Darrick J. Wong <djwong@...nel.org>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>

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

--D

> ---
> 
> This should be on top of John's atomic write series [1].
> [1]: https://lore.kernel.org/linux-xfs/20241019125113.369994-1-john.g.garry@oracle.com/
> 
>  fs/xfs/xfs_file.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index ca47cae5a40a..b819a9273511 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -876,6 +876,14 @@ xfs_file_write_iter(
>  		ret = xfs_file_dio_write(iocb, from);
>  		if (ret != -ENOTBLK)
>  			return ret;
> +		/*
> +		 * iomap can return -ENOTBLK if pagecache invalidation fails.
> +		 * Let's make sure if -ENOTBLK is ever returned for atomic
> +		 * writes than we fail the write request instead of fallback
> +		 * to buffered-io.
> +		 */
> +		if (iocb->ki_flags & IOCB_ATOMIC)
> +			return -EIO;
>  	}
> 
>  	return xfs_file_buffered_write(iocb, from);
> --
> 2.39.5
> 
>