[Question] qemu-img convert block alignment

[Zhenyu Ye]

Hi all,

commit 8dcd3c9b91 ("qemu-img: align result of is_allocated_sectors")
introduces block alignment when doing qemu-img convert. However, the
alignment is:

        s.alignment = MAX(pow2floor(s.min_sparse),
                      DIV_ROUND_UP(out_bs->bl.request_alignment,
                                   BDRV_SECTOR_SIZE));

(where the default s.min_sparse is 8)
When the target device's bl.request_alignment is smaller than 4K, this
will cause additional write-zero overhead and makes the size of target
file larger.

Is this as expected?  Should we change the MAX() to MIN()?


Thanks,
zhenyu