On 04/18/2017 05:15 PM, John Snow wrote:
>> @@ -279,9 +280,9 @@ static int mig_save_device_bulk(QEMUFile *f,
>> BlkMigDevState *bmds)
>> /* Skip unallocated sectors; intentionally treats failure as
>> * an allocated sector */
>> while (cur_sector < total_sectors &&
>> - !bdrv_is_allocated(blk_bs(bb), cur_sector,
>> - MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {
>> - cur_sector += nr_sectors;
>> + !bdrv_is_allocated(blk_bs(bb), cur_sector * BDRV_SECTOR_SIZE,
>> + MAX_IS_ALLOCATED_SEARCH, &count)) {
>> + cur_sector += DIV_ROUND_UP(count, BDRV_SECTOR_SIZE);
>
> Hm, what's the story here, why are we rounding this up? If, in theory,
> we have a partially allocated cluster won't we advance past that?This is rounding to sectors, not clusters (that is, the code is supposed to advance cur_sector identically pre- and post-patch). As to whether the overall algorithm makes sense, or could use some tweaking by converting migration/block.c to do everything by bytes instead of by sectors, I haven't yet given that any serious time. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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