On Sat, Aug 17, 2024 at 09:47:58AM +0000, John Garry wrote:
> Support providing info on atomic write unit min and max for an inode.
>
> For simplicity, currently we limit the min at the FS block size, but a
> lower limit could be supported in future. This is required by iomap
> DIO.
>
> The atomic write unit min and max is limited by the guaranteed extent
> alignment for the inode.
>
> Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
> ---
> fs/xfs/xfs_iops.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 6e017aa6f61d..c20becd3a7c9 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -570,6 +570,27 @@ xfs_stat_blksize(
> return PAGE_SIZE;
> }
>
> +static void
> +xfs_get_atomic_write_attr(
> + struct xfs_inode *ip,
> + unsigned int *unit_min,
> + unsigned int *unit_max)
> +{
> + struct xfs_buftarg *target = xfs_inode_buftarg(ip);
> + struct xfs_mount *mp = ip->i_mount;
> + struct xfs_sb *sbp = &mp->m_sb;
> + unsigned int extsz_bytes = XFS_FSB_TO_B(mp, ip->i_extsize);
> +
> + if (!xfs_inode_has_atomicwrites(ip)) {
Here's where you might want to check that DIFLAG2_ATOMICWRITES is sset
and stripe alignment still makes sense before handing out nonzero
STATX_WRITE_ATOMIC information. The rest of the patch looks ok to me.
--D
> + *unit_min = 0;
> + *unit_max = 0;
> + return;
> + }
> +
> + *unit_min = sbp->sb_blocksize;
> + *unit_max = min(target->bt_bdev_awu_max, extsz_bytes);
> +}
> +
> STATIC int
> xfs_vn_getattr(
> struct mnt_idmap *idmap,
> @@ -643,6 +664,13 @@ xfs_vn_getattr(
> stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
> stat->dio_offset_align = bdev_logical_block_size(bdev);
> }
> + if (request_mask & STATX_WRITE_ATOMIC) {
> + unsigned int unit_min, unit_max;
> +
> + xfs_get_atomic_write_attr(ip, &unit_min, &unit_max);
> + generic_fill_statx_atomic_writes(stat,
> + unit_min, unit_max);
> + }
> fallthrough;
> default:
> stat->blksize = xfs_stat_blksize(ip);
> --
> 2.31.1
>
>
