Re: [PATCH v3 0/3] md/md-llbitmap: add CleanUnwritten support

["Yu Kuai" <yukuai@fnnas.com>]

在 2026/3/23 13:46, Yu Kuai 写道:

> Patch 1 improves compatibility with older mdadm versions by detecting
> on-disk bitmap version and falling back to the correct bitmap_ops when
> there's a version mismatch.
>
> Patch 2 adds support for proactive XOR parity building in RAID-456 arrays.
> This allows users to pre-build parity for unwritten regions via sysfs
> before any user data is written, which can improve write performance for
> workloads that will eventually use all storage. New states (CleanUnwritten,
> NeedSyncUnwritten, SyncingUnwritten) are added to track these regions
> separately from normal dirty/syncing states.
>
> Patch 3 optimizes initial array sync for RAID-456 arrays on devices that
> support write_zeroes with unmap. By zeroing all disks upfront, parity is
> automatically consistent (0 XOR 0 = 0), allowing the bitmap to be
> initialized to BitCleanUnwritten and skipping the initial sync entirely.
> This significantly reduces array initialization time on modern NVMe SSDs.
>
> Yu Kuai (3):
>    md: add fallback to correct bitmap_ops on version mismatch
>    md/md-llbitmap: add CleanUnwritten state for RAID-5 proactive parity
>      building
>    md/md-llbitmap: optimize initial sync with write_zeroes_unmap support
>
>   drivers/md/md-llbitmap.c | 202 ++++++++++++++++++++++++++++++++++++---
>   drivers/md/md.c          | 111 ++++++++++++++++++++-
>   2 files changed, 299 insertions(+), 14 deletions(-)
Applied to md-7.1

-- 
Thansk,
Kuai