On Wed, Jan 24, 2024 at 02:26:43PM +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.
>
> 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 | 45 +++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_iops.h | 4 ++++
> 2 files changed, 49 insertions(+)
>
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index a0d77f5f512e..0890d2f70f4d 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -546,6 +546,44 @@ xfs_stat_blksize(
> return PAGE_SIZE;
> }
>
> +void xfs_get_atomic_write_attr(
static void?
> + struct xfs_inode *ip,
> + unsigned int *unit_min,
> + unsigned int *unit_max)
Weird indenting here.
> +{
> + xfs_extlen_t extsz = xfs_get_extsz(ip);
> + struct xfs_buftarg *target = xfs_inode_buftarg(ip);
> + struct block_device *bdev = target->bt_bdev;
> + unsigned int awu_min, awu_max, align;
> + struct request_queue *q = bdev->bd_queue;
> + struct xfs_mount *mp = ip->i_mount;
> +
> + /*
> + * Convert to multiples of the BLOCKSIZE (as we support a minimum
> + * atomic write unit of BLOCKSIZE).
> + */
> + awu_min = queue_atomic_write_unit_min_bytes(q);
> + awu_max = queue_atomic_write_unit_max_bytes(q);
> +
> + awu_min &= ~mp->m_blockmask;
Why do you round /down/ the awu_min value here?
> + awu_max &= ~mp->m_blockmask;
Actually -- since the atomic write units have to be powers of 2, why is
rounding needed here at all?
> +
> + align = XFS_FSB_TO_B(mp, extsz);
> +
> + if (!awu_max || !xfs_inode_atomicwrites(ip) || !align ||
> + !is_power_of_2(align)) {
...and if you take my suggestion to make a common helper to validate the
atomic write unit parameters, this can collapse into:
alloc_unit_bytes = xfs_inode_alloc_unitsize(ip);
if (!xfs_inode_has_atomicwrites(ip) ||
!bdev_validate_atomic_write(bdev, alloc_unit_bytes)) {
/* not supported, return zeroes */
*unit_min = 0;
*unit_max = 0;
return;
}
*unit_min = max(alloc_unit_bytes, awu_min);
*unit_max = min(alloc_unit_bytes, awu_max);
--D
> + *unit_min = 0;
> + *unit_max = 0;
> + } else {
> + if (awu_min)
> + *unit_min = min(awu_min, align);
> + else
> + *unit_min = mp->m_sb.sb_blocksize;
> +
> + *unit_max = min(awu_max, align);
> + }
> +}
> +
> STATIC int
> xfs_vn_getattr(
> struct mnt_idmap *idmap,
> @@ -619,6 +657,13 @@ 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);
> diff --git a/fs/xfs/xfs_iops.h b/fs/xfs/xfs_iops.h
> index 7f84a0843b24..76dd4c3687aa 100644
> --- a/fs/xfs/xfs_iops.h
> +++ b/fs/xfs/xfs_iops.h
> @@ -19,4 +19,8 @@ int xfs_vn_setattr_size(struct mnt_idmap *idmap,
> int xfs_inode_init_security(struct inode *inode, struct inode *dir,
> const struct qstr *qstr);
>
> +void xfs_get_atomic_write_attr(struct xfs_inode *ip,
> + unsigned int *unit_min,
> + unsigned int *unit_max);
> +
> #endif /* __XFS_IOPS_H__ */
> --
> 2.31.1
>
>
