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From: Alberto Garcia <berto@igalia.com>
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Date: Fri, 02 Feb 2018 11:10:27 +0100
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Subject: Re: [Qemu-devel] [PATCH v3 31/39] qcow2: Update qcow2_truncate() to
 support L2 slices
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To: Max Reitz <mreitz@redhat.com>, qemu-devel@nongnu.org
Cc: qemu-block@nongnu.org, Kevin Wolf <kwolf@redhat.com>, Eric Blake <eblake@redhat.com>, Anton Nefedov <anton.nefedov@virtuozzo.com>, "Denis V . Lunev" <den@openvz.org>

On Thu 01 Feb 2018 08:46:46 PM CET, Max Reitz <mreitz@redhat.com> wrote:
>> @@ -3261,8 +3261,9 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset,
>>          guest_offset = old_length;
>>          while (nb_new_data_clusters) {
>>              int64_t guest_cluster = guest_offset >> s->cluster_bits;
>> -            int64_t nb_clusters = MIN(nb_new_data_clusters,
>> -                                      s->l2_size - guest_cluster % s->l2_size);
>> +            int64_t nb_clusters = MIN(
>> +                nb_new_data_clusters,
>> +                s->l2_slice_size - guest_cluster % s->l2_slice_size);
>
> An alternative would be the
> "s->l2_slice_size - offset_to_l2_slice_index(s, guest_offset)" we
> basically have elsewhere, but that's longer and doesn't really matter:

It's a bit longer but it looks better and we can get rid of
guest_cluster, so I think I'll change it.

Berto