Re: [Qemu-devel] [PATCH COLO-BLOCK v7 00/17] Block replication for continuous checkpoints

["Michael R. Hines" <mrhines@linux.vnet.ibm.com>]

On 06/29/2015 10:34 PM, Wen Congyang wrote:
> Block replication is a very important feature which is used for
> continuous checkpoints(for example: COLO).
>
> Usage:
> Please refer to docs/block-replication.txt
>
> You can get the patch here:
> https://github.com/wencongyang/qemu-colo/commits/block-replication-v7
>
> You can get ths patch with framework here:
> https://github.com/wencongyang/qemu-colo/commits/colo_framework_v7.2
>
> TODO:
> 1. Continuous block replication. It will be started after basic functions
>     are accepted.
>
> Changs Log:
> V7:
> 1. Implement adding/removing quorum child. Remove the option non-connect.
> 2. Simplify the backing refrence option according to Stefan Hajnoczi's suggestion
> V6:
> 1. Rebase to the newest qemu.
> V5:
> 1. Address the comments from Gong Lei
> 2. Speed the failover up. The secondary vm can take over very quickly even
>     if there are too many I/O requests.
> V4:
> 1. Introduce a new driver replication to avoid touch nbd and qcow2.
> V3:
> 1: use error_setg() instead of error_set()
> 2. Add a new block job API
> 3. Active disk, hidden disk and nbd target uses the same AioContext
> 4. Add a testcase to test new hbitmap API
> V2:
> 1. Redesign the secondary qemu(use image-fleecing)
> 2. Use Error objects to return error message
> 3. Address the comments from Max Reitz and Eric Blake
>
>
> Wen Congyang (17):
>    Add new block driver interface to add/delete a BDS's child
>    quorum: implement block driver interfaces add/delete a BDS's child
>    hmp: add monitor command to add/remove a child
>    introduce a new API qemu_opts_absorb_qdict_by_index()
>    quorum: allow ignoring child errors
>    introduce a new API to enable/disable attach device model
>    introduce a new API to check if blk is attached
>    block: make bdrv_put_ref_bh_schedule() as a public API
>    Backup: clear all bitmap when doing block checkpoint
>    allow writing to the backing file
>    Allow creating backup jobs when opening BDS
>    block: Allow references for backing files
>    docs: block replication's description
>    Add new block driver interfaces to control block replication
>    skip nbd_target when starting block replication
>    quorum: implement block driver interfaces for block replication
>    Implement new driver for block replication
>
>   block.c                        | 198 +++++++++++++++++-
>   block/Makefile.objs            |   3 +-
>   block/backup.c                 |  13 ++
>   block/block-backend.c          |  33 +++
>   block/quorum.c                 | 244 ++++++++++++++++++++++-
>   block/replication.c            | 443 +++++++++++++++++++++++++++++++++++++++++
>   blockdev.c                     |  90 ++++++---
>   blockjob.c                     |  10 +
>   docs/block-replication.txt     | 179 +++++++++++++++++
>   hmp-commands.hx                |  28 +++
>   include/block/block.h          |  11 +
>   include/block/block_int.h      |  19 ++
>   include/block/blockjob.h       |  12 ++
>   include/qemu/option.h          |   2 +
>   include/sysemu/block-backend.h |   3 +
>   include/sysemu/blockdev.h      |   2 +
>   qapi/block.json                |  16 ++
>   util/qemu-option.c             |  44 ++++
>   18 files changed, 1303 insertions(+), 47 deletions(-)
>   create mode 100644 block/replication.c
>   create mode 100644 docs/block-replication.txt
>

Can you move the interfaces for 
blk_start_replication()/blk_stop_replication/blk_do_checkpoint() to this 
patch series
instead of the COLO patch series?

I don't think those functions are specific to COLO --- they should be 
available to all users.

- Michael