[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 12/18] block/backup: add 'always' bitmap sync
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH v2 12/18] block/backup: add 'always' bitmap sync policy |
Date: |
Thu, 4 Jul 2019 20:05:26 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
On 04.07.19 19:43, Max Reitz wrote:
> On 03.07.19 23:55, John Snow wrote:
>> This adds an "always" policy for bitmap synchronization. Regardless of if
>> the job succeeds or fails, the bitmap is *always* synchronized. This means
>> that for backups that fail part-way through, the bitmap retains a record of
>> which sectors need to be copied out to accomplish a new backup using the
>> old, partial result.
>>
>> In effect, this allows us to "resume" a failed backup; however the new backup
>> will be from the new point in time, so it isn't a "resume" as much as it is
>> an "incremental retry." This can be useful in the case of extremely large
>> backups that fail considerably through the operation and we'd like to not
>> waste
>> the work that was already performed.
>>
>> Signed-off-by: John Snow <address@hidden>
>> ---
>> block/backup.c | 25 +++++++++++++++++--------
>> qapi/block-core.json | 5 ++++-
>> 2 files changed, 21 insertions(+), 9 deletions(-)
>>
>> diff --git a/block/backup.c b/block/backup.c
>> index 9cc5a7f6ca..495d8f71aa 100644
>> --- a/block/backup.c
>> +++ b/block/backup.c
>> @@ -266,16 +266,25 @@ static void backup_cleanup_sync_bitmap(BackupBlockJob
>> *job, int ret)
[...]
>> + /* If we failed and synced, merge in the bits we didn't copy: */
>> + bdrv_dirty_bitmap_merge_internal(bm, job->copy_bitmap,
>> + NULL, true);
>
> I presume this is for sync=full?
Ah, no. This is necessary because the original sync bitmap was
discarded by bdrv_dirty_bitmap_abdicate(). So yep, these bits need to
go back into the sync bitmap then.
Max
signature.asc
Description: OpenPGP digital signature
- Re: [Qemu-devel] [PATCH v2 08/18] hbitmap: enable merging across granularities, (continued)
- [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, John Snow, 2019/07/03
- Re: [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, Max Reitz, 2019/07/04
- Re: [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, John Snow, 2019/07/05
- Re: [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, Max Reitz, 2019/07/08
- Re: [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, John Snow, 2019/07/08
- Re: [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, Max Reitz, 2019/07/08
- Re: [Qemu-devel] [PATCH v2 09/18] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal, John Snow, 2019/07/08
[Qemu-devel] [PATCH v2 12/18] block/backup: add 'always' bitmap sync policy, John Snow, 2019/07/03
[Qemu-devel] [PATCH v2 10/18] block/dirty-bitmap: add bdrv_dirty_bitmap_get, John Snow, 2019/07/03
[Qemu-devel] [PATCH v2 14/18] iotests: teach run_job to cancel pending jobs, John Snow, 2019/07/03
[Qemu-devel] [PATCH v2 11/18] block/backup: upgrade copy_bitmap to BdrvDirtyBitmap, John Snow, 2019/07/03