linux-kernel - Re: [PATCH v3 3/7] iomap: Lift blocksize restriction on atomic writes

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Message-ID: <20250108004103.GA1306365@frogsfrogsfrogs>
Date: Tue, 7 Jan 2025 16:41:03 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: John Garry <john.g.garry@...cle.com>
Cc: brauner@...nel.org, cem@...nel.org, dchinner@...hat.com, hch@....de,
	ritesh.list@...il.com, linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	martin.petersen@...cle.com
Subject: Re: [PATCH v3 3/7] iomap: Lift blocksize restriction on atomic writes

On Thu, Jan 02, 2025 at 02:04:07PM +0000, John Garry wrote:
> From: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>
> 
> Filesystems like ext4 can submit writes in multiples of blocksizes.
> But we still can't allow the writes to be split. Hence let's check if
> the iomap_length() is same as iter->len or not.
> 
> It is the role of the FS to ensure that a single mapping may be created
> for an atomic write. The FS will also continue to check size and alignment
> legality.
> 
> Signed-off-by: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>
> jpg: Tweak commit message
> Signed-off-by: John Garry <john.g.garry@...cle.com>

Fine with me.
Reviewed-by: "Darrick J. Wong" <djwong@...nel.org>

--D

> ---
>  fs/iomap/direct-io.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 18c888f0c11f..6510bb5d5a6f 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -314,7 +314,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>  	size_t copied = 0;
>  	size_t orig_count;
>  
> -	if (atomic && length != fs_block_size)
> +	if (atomic && length != iter->len)
>  		return -EINVAL;
>  
>  	if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
> -- 
> 2.31.1
> 
>