Re: [Qemu-devel] [PATCH 0/8] block: persistent dirty bitmaps (RFC)

[John Snow <jsnow@redhat.com>]

On 02/04/2015 10:07 AM, Vladimir Sementsov-Ogievskiy wrote:
> On 13.01.2015 20:02, Vladimir Sementsov-Ogievskiy wrote:
>> The bitmaps are saved into qcow2 file format. It provides both
>> 'internal' and 'external' dirty bitmaps feature:
>>   - for qcow2 drives we can store bitmaps in the same file
>>   - for other formats we can store bitmaps in the separate qcow2 file
>>
>> QCow2 header is extended by fields 'nb_dirty_bitmaps' and
>> 'dirty_bitmaps_offset' like with snapshots.
>>
>> Proposed command line syntax is the following:
>>
>> -dirty-bitmap [option1=val1][,option2=val2]...
>>      Available options are:
>>      name         The name for the bitmap (necessary).
>>
>>      file         The file to load the bitmap from.
>>
>>      file_id      When specified with 'file' option, then this file will
>>                   be available through this id for other -dirty-bitmap
>>                   options when specified without 'file' option, then it
>>                   is a reference to 'file', specified with another
>>                   -dirty-bitmap option, and it will be used to load the
>>                   bitmap from.
>>
>>      drive        The drive to bind the bitmap to. It should be specified
>>                   as 'id' suboption of one of -drive options. If nor
>>                   'file' neither 'file_id' are specified, then the bitmap
>>                   will be loaded from that drive (internal dirty bitmap).
>>
>>      granularity  The granularity for the bitmap. Not necessary, the
>>                   default value may be used.
>>
>>      enabled      on|off. Default is 'on'. Disabled bitmaps are not
>>                   changing regardless of writes to corresponding drive.
>>
>> Examples:
>>
>> qemu -drive file=a.qcow2,id=disk -dirty-bitmap name=b,drive=disk
>> qemu -drive file=a.raw,id=disk \
>>       -dirty-bitmap name=b,drive=disk,file=b.qcow2,enabled=off
>>
>> Vladimir Sementsov-Ogievskiy (8):
>>    spec: add qcow2-dirty-bitmaps specification
>>    hbitmap: store / restore
>>    qcow2: add dirty-bitmaps feature
>>    block: store persistent dirty bitmaps
>>    block: add bdrv_load_dirty_bitmap
>>    qemu: command line option for dirty bitmaps
>>    qmp: print dirty bitmap
>>    iotests: test internal persistent dirty bitmap
>>
>>   block.c                    | 113 ++++++++++
>>   block/Makefile.objs        |   2 +-
>>   block/qcow2-dirty-bitmap.c | 514
>> +++++++++++++++++++++++++++++++++++++++++++++
>>   block/qcow2.c              |  26 +++
>>   block/qcow2.h              |  48 +++++
>>   blockdev.c                 |  51 +++++
>>   docs/specs/qcow2.txt       |  59 ++++++
>>   hmp-commands.hx            |  15 ++
>>   hmp.c                      |   8 +
>>   hmp.h                      |   1 +
>>   include/block/block.h      |   9 +
>>   include/block/block_int.h  |  10 +
>>   include/qemu/hbitmap.h     |  49 +++++
>>   include/sysemu/blockdev.h  |   1 +
>>   include/sysemu/sysemu.h    |   1 +
>>   qapi-schema.json           |   3 +-
>>   qapi/block-core.json       |   3 +
>>   qemu-options.hx            |  37 ++++
>>   qmp-commands.hx            |   5 +
>>   tests/qemu-iotests/115     |  96 +++++++++
>>   tests/qemu-iotests/115.out |  64 ++++++
>>   tests/qemu-iotests/group   |   1 +
>>   util/hbitmap.c             |  87 ++++++++
>>   vl.c                       | 100 +++++++++
>>   24 files changed, 1301 insertions(+), 2 deletions(-)
>>   create mode 100644 block/qcow2-dirty-bitmap.c
>>   create mode 100755 tests/qemu-iotests/115
>>   create mode 100644 tests/qemu-iotests/115.out
>>
>
> Ping. I've already done (locally):
> 1) using qcow2 header extension instead of changing the header
> 2) normal qmp query request instead of "print dirty bitmap"
>   - thanks to Eric and Markus
>
> Now I'm waiting for some comments on the concept and it's realization to
> roll v3.
>

My apologies, I've been sick for a while. I'll get going on finishing 
review of these two series.

I assume you'd like to merge the bitmaps migration first?

--js