Re: [PATCH v5 8/8] xfs: support STATX_DIOALIGN

Darrick J. Wong
2022-08-27T15:34:58Z

On Fri, Aug 26, 2022 at 11:58:51PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> Add support for STATX_DIOALIGN to xfs, so that direct I/O alignment
> restrictions are exposed to userspace in a generic way.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Looks good to me; I particularly like the adjustment to report the
device's DMA alignment. Someone should probably fix DIONINFO, or
perhaps turn it into a getattr wrapper and hoist it? IMHO none of those
suggestions are necessary to land this patch, though.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> fs/xfs/xfs_iops.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 45518b8c613c9a..f51c60d7e2054a 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -604,6 +604,16 @@ xfs_vn_getattr(
> stat->blksize = BLKDEV_IOSIZE;
> stat->rdev = inode->i_rdev;
> break;
> + case S_IFREG:
> + if (request_mask & STATX_DIOALIGN) {
> + struct xfs_buftarg *target = xfs_inode_buftarg(ip);
> + struct block_device *bdev = target->bt_bdev;
> +
> + stat->result_mask |= STATX_DIOALIGN;
> + stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
> + stat->dio_offset_align = bdev_logical_block_size(bdev);
> + }
> + fallthrough;
> default:
> stat->blksize = xfs_stat_blksize(ip);
> stat->rdev = 0;
> --
> 2.37.2
>