md/raid5: reject llbitmap reshape when md chunk shrinks

llbitmap reshape keeps one live bitmap and cannot safely make an
existing bitmap bit cover a smaller data range.

The llbitmap chunksize itself will not shrink when mddev->chunk_sectors
stays the same or grows. However, shrinking mddev->chunk_sectors shrinks
sectors_per_chunk used by raid5_bitmap_sector_map(). That can shrink the
effective data range covered by each bit across the old and new RAID5
geometry. Reject that reshape while llbitmap is active.

Tested-by: Mykola Marzhan <mykola@meshstor.io>
Link: https://patch.msgid.link/20260802195038.164272-28-yukuai@kernel.org
Signed-off-by: Yu Kuai <yukuai@fygo.io>

0 files changed, 0 insertions, 0 deletions