Re: [PATCH v6 05/10] block: Add core atomic write support

Randy Dunlap
2024-03-26T17:11:59Z

Hi,

On 3/26/24 06:38, John Garry wrote:
> diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
> index 1fe9a553c37b..4c775f4bdefe 100644
> --- a/Documentation/ABI/stable/sysfs-block
> +++ b/Documentation/ABI/stable/sysfs-block
> @@ -21,6 +21,58 @@ Description:
> device is offset from the internal allocation unit's
> natural alignment.
>
> +What: /sys/block/<disk>/atomic_write_max_bytes
> +Date: February 2024
> +Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
> +Description:
> + [RO] This parameter specifies the maximum atomic write
> + size reported by the device. This parameter is relevant
> + for merging of writes, where a merged atomic write
> + operation must not exceed this number of bytes.
> + This parameter may be greater to the value in

than

> + atomic_write_unit_max_bytes as
> + atomic_write_unit_max_bytes will be rounded down to a
> + power-of-two and atomic_write_unit_max_bytes may also be
> + limited by some other queue limits, such as max_segments.
> + This parameter - along with atomic_write_unit_min_bytes
> + and atomic_write_unit_max_bytes - will not be larger than
> + max_hw_sectors_kb, but may be larger than max_sectors_kb.
> +
> +
> +What: /sys/block/<disk>/atomic_write_unit_min_bytes
> +Date: February 2024
> +Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
> +Description:
> + [RO] This parameter specifies the smallest block which can
> + be written atomically with an atomic write operation. All
> + atomic write operations must begin at a
> + atomic_write_unit_min boundary and must be multiples of
> + atomic_write_unit_min. This value must be a power-of-two.
> +
> +
> +What: /sys/block/<disk>/atomic_write_unit_max_bytes
> +Date: February 2024
> +Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
> +Description:
> + [RO] This parameter defines the largest block which can be
> + written atomically with an atomic write operation. This
> + value must be a multiple of atomic_write_unit_min and must
> + be a power-of-two. This value will not be larger than
> + atomic_write_max_bytes.
> +
> +
> +What: /sys/block/<disk>/atomic_write_boundary_bytes
> +Date: February 2024
> +Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
> +Description:
> + [RO] A device may need to internally split I/Os which
> + straddle a given logical block address boundary. In that
> + case a single atomic write operation will be processed as
> + one of more sub-operations which each complete atomically.

or

> + This parameter specifies the size in bytes of the atomic
> + boundary if one is reported by the device. This value must
> + be a power-of-two.

--
#Randy