Re: [PATCH 5/5] xfs: report larger dio alignment for COW inodes

[John Garry <john.g.garry@oracle.com>]

On 08/01/2025 08:55, Christoph Hellwig wrote:
> For I/O to reflinked blocks we always need to write an entire new file
> system block, and the code enforces the file system block alignment for
> the entire file if it has any reflinked blocks.  Mirror the larger
> value reported in the statx in the dio_offset_align in the xfs-specific
> XFS_IOC_DIOINFO ioctl for the same reason.
> 
> Don't bother adding a new field for the read alignment to this legacy
> ioctl as all new users should use statx instead.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   fs/xfs/xfs_ioctl.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 0789c18aaa18..20f3cf5391c6 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1204,7 +1204,16 @@ xfs_file_ioctl(
>   		struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
>   		struct dioattr		da;
>   
> -		da.d_mem =  da.d_miniosz = target->bt_logical_sectorsize;
> +		da.d_mem = target->bt_logical_sectorsize;
> +
> +		/*
> +		 * See xfs_report_dioalign() why report a potential larger than
> +		 * sector sizevalue here for COW inodes.

nit: sizevalue

> +		 */
> +		if (xfs_is_cow_inode(ip))
> +			da.d_miniosz = xfs_inode_alloc_unitsize(ip);
> +		else
> +			da.d_miniosz = target->bt_logical_sectorsize;
>   		da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1);
>   
>   		if (copy_to_user(arg, &da, sizeof(da)))