loop: set dma_alignment from the backing file for direct I/O

Direct I/O user pages are forwarded to the backing file unchanged, so
the backing's DMA alignment requirement applies to them. Track the
backing's dio_mem_align and advertise it as the loop device's
dma_alignment so we advertise proper limits and misaligned I/O is
rejected here instead of being dispatched to the backend.

Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://patch.msgid.link/20260720201057.1862857-4-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions