linux-kernel - Re: [PATCH 02/12] xfs: set IOMAP_F

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Message-ID: <20191015180119.GQ13108@magnolia>
Date:   Tue, 15 Oct 2019 11:01:19 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Damien Le Moal <Damien.LeMoal@....com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/12] xfs: set IOMAP_F_NEW more carefully

On Tue, Oct 15, 2019 at 05:43:35PM +0200, Christoph Hellwig wrote:
> Don't set IOMAP_F_NEW if we COW over and existing allocated range, as

"..over an existing..."

> these aren't strictly new allocations.  This is required to be able to
> use IOMAP_F_NEW to zero newly allocated blocks, which is required for
> the iomap code to fully support file systems that don't do delayed
> allocations or use unwritten extents.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>

Other than that,

Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>

--D

> ---
>  fs/xfs/xfs_iomap.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 54c9ec7ad337..c0a492353826 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -707,9 +707,12 @@ xfs_file_iomap_begin_delay(
>  	 * Flag newly allocated delalloc blocks with IOMAP_F_NEW so we punch
>  	 * them out if the write happens to fail.
>  	 */
> -	iomap_flags |= IOMAP_F_NEW;
> -	trace_xfs_iomap_alloc(ip, offset, count, whichfork,
> -			whichfork == XFS_DATA_FORK ? &imap : &cmap);
> +	if (whichfork == XFS_DATA_FORK) {
> +		iomap_flags |= IOMAP_F_NEW;
> +		trace_xfs_iomap_alloc(ip, offset, count, whichfork, &imap);
> +	} else {
> +		trace_xfs_iomap_alloc(ip, offset, count, whichfork, &cmap);
> +	}
>  done:
>  	if (whichfork == XFS_COW_FORK) {
>  		if (imap.br_startoff > offset_fsb) {
> -- 
> 2.20.1
>