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Re: [Qemu-block] [PATCH 05/12] hbitmap: enable merging across granularit
From: |
John Snow |
Subject: |
Re: [Qemu-block] [PATCH 05/12] hbitmap: enable merging across granularities |
Date: |
Thu, 20 Jun 2019 14:13:46 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
On 6/20/19 11:47 AM, Max Reitz wrote:
> On 20.06.19 03:03, John Snow wrote:
>> Signed-off-by: John Snow <address@hidden>
>> ---
>> util/hbitmap.c | 22 +++++++++++++++++++++-
>> 1 file changed, 21 insertions(+), 1 deletion(-)
>>
>> diff --git a/util/hbitmap.c b/util/hbitmap.c
>> index 45d1725daf..0d6724b7bc 100644
>> --- a/util/hbitmap.c
>> +++ b/util/hbitmap.c
>> @@ -777,7 +777,17 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size)
>>
>> bool hbitmap_can_merge(const HBitmap *a, const HBitmap *b)
>> {
>> - return (a->size == b->size) && (a->granularity == b->granularity);
>> + return (a->size == b->size);
>> +}
>> +
>> +static void hbitmap_sparse_merge(HBitmap *dst, const HBitmap *src)
>> +{
>> + uint64_t offset = 0;
>> + uint64_t count = src->orig_size;
>> +
>> + while (hbitmap_next_dirty_area(src, &offset, &count)) {
>> + hbitmap_set(dst, offset, count);
>> + }
>> }
>>
>> /**
>> @@ -804,6 +814,16 @@ bool hbitmap_merge(const HBitmap *a, const HBitmap *b,
>> HBitmap *result)
>> return true;
>> }
>>
>> + if (a->size != b->size) {
>
> Don’t you mean s/size/granularity/?
>
> Right now, this is dead code, which leads me to asking for a test.
> (Well, no, I would’ve asked anyway.)
>
> Max
>
Ah, crud. Caught red-handed. Yes and Yes.
As to your later question: Can we use this for backup initialization?
Also yes; but it might be the case that we want the copy bitmap to
become a full-fledged "bdrv dirty bitmap" instead of an hbitmap, which
will actually make this easier and probably eliminate the need for the
"_take" or "_claim" function I added, too.
- Re: [Qemu-block] [PATCH 02/12] block/backup: Add mirror sync mode 'bitmap', (continued)
[Qemu-block] [PATCH 05/12] hbitmap: enable merging across granularities, John Snow, 2019/06/19
[Qemu-block] [PATCH 11/12] iotests: add test 257 for bitmap-mode backups, John Snow, 2019/06/19
[Qemu-block] [PATCH 03/12] block/backup: add 'never' policy to bitmap sync mode, John Snow, 2019/06/19