md/raid5: split reshape bios before bitmap accounting

RAID5 maps array sectors through different geometries before and after the
reshape position. During llbitmap reshape, md core cannot account one bio
against both geometries as a single bitmap range, because the old and new
bitmap mappings can cover different chunks.

Split bios that cross reshape_position before md_account_bio(), so the
bitmap only sees ranges that belong to one side of the reshape boundary.

mddev_bio_split_at_reshape_offset() uses bio_submit_split_bioset(), which
submits the remainder immediately and returns the front split bio. If that
front bio later has to wait for reshape, md_handle_request() must not retry
the original bio pointer, because after the split that pointer is the
already-submitted remainder. Track whether the split happened, clear the
temporary BLK_STS_RESOURCE status after the internal clone completion, and
resubmit the front bio directly after the reshape wait. Keep the old
return-false retry path for unsplit bios, where md_handle_request() still
owns the same bio.

Tested-by: Mykola Marzhan <mykola@meshstor.io>
Link: https://patch.msgid.link/20260802195038.164272-30-yukuai@kernel.org
Signed-off-by: Yu Kuai <yukuai@fygo.io>

0 files changed, 0 insertions, 0 deletions