[Qemu-devel] [PATCH v17 0/8] Block replication for continuous checkpoints

[Changlong Xie]

Block replication is a very important feature which is used for
continuous checkpoints(for example: COLO).

You can get the detailed information about block replication from here:
http://wiki.qemu.org/Features/BlockReplication

Usage:
Please refer to docs/block-replication.txt

This patch series is based on the following patch series:
http://lists.nongnu.org/archive/html/qemu-devel/2016-03/msg02321.html

You can get the patch here:
https://github.com/Pating/qemu/tree/changlox/block-replication-v17

You can get the patch with framework here:
https://github.com/Pating/qemu/tree/changlox/colo_framework_v16

TODO:
1. Continuous block replication. It will be started after basic functions
   are accepted.

Changs Log:
V17:
1. Rebase to the lastest codes 
p2: refactor backup_do_checkpoint addressed comments from Jeff Cody
p4: fix bugs in "drive_add buddy xxx" hmp commands
p6: add "since: 2.7"
p7: fix bug in replication_close(), add missing "qapi/error.h", add 
test-replication 
p8: add "since: 2.7"
V16:
1. Rebase to the newest codes
2. Address comments from Stefan & hailiang
p3: we don't need this patch now
p4: add "top-id" parameters for secondary
p6: fix NULL pointer in replication callbacks, remove unnecessary typedefs, 
add doc comments that explain the semantics of Replication
p7: Refactor AioContext for thread-safe, remove unnecessary get_top_bs()
*Note*: I'm working on replication testcase now, will send out in V17
V15:
1. Rebase to the newest codes
2. Fix typos and coding style addresed Eric's comments
3. Address Stefan's comments
   1) Make backup_do_checkpoint public, drop the changes on BlockJobDriver
   2) Update the message and description for [PATCH 4/9]
   3) Make replication_(start/stop/do_checkpoint)_all as global interfaces
   4) Introduce AioContext lock to protect start/stop/do_checkpoint callbacks
   5) Use BdrvChild instead of holding on to BlockDriverState * pointers
4. Clear BDRV_O_INACTIVE for hidden disk's open_flags since commit 09e0c771  
5. Introduce replication_get_error_all to check replication status
6. Remove useless discard interface
V14:
1. Implement auto complete active commit
2. Implement active commit block job for replication.c
3. Address the comments from Stefan, add replication-specific API and data
   structure, also remove old block layer APIs
V13:
1. Rebase to the newest codes
2. Remove redundant marcos and semicolon in replication.c 
3. Fix typos in block-replication.txt
V12:
1. Rebase to the newest codes
2. Use backing reference to replcace 'allow-write-backing-file'
V11:
1. Reopen the backing file when starting blcok replication if it is not
   opened in R/W mode
2. Unblock BLOCK_OP_TYPE_BACKUP_SOURCE and BLOCK_OP_TYPE_BACKUP_TARGET
   when opening backing file
3. Block the top BDS so there is only one block job for the top BDS and
   its backing chain.
V10:
1. Use blockdev-remove-medium and blockdev-insert-medium to replace backing
   reference.
2. Address the comments from Eric Blake
V9:
1. Update the error messages
2. Rebase to the newest qemu
3. Split child add/delete support. These patches are sent in another patchset.
V8:
1. Address Alberto Garcia's comments
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

Changlong Xie (1):
  Introduce new APIs to do replication operation

Wen Congyang (7):
  unblock backup operations in backing file
  Backup: clear all bitmap when doing block checkpoint
  Link backup into block core
  docs: block replication's description
  auto complete active commit
  Implement new driver for block replication
  support replication driver in blockdev-add

 Makefile.objs              |   1 +
 block.c                    |  17 ++
 block/Makefile.objs        |   3 +-
 block/backup.c             |  17 ++
 block/mirror.c             |  13 +-
 block/replication.c        | 622 +++++++++++++++++++++++++++++++++++++++++++++
 blockdev.c                 |   2 +-
 docs/block-replication.txt | 239 +++++++++++++++++
 include/block/block_int.h  |   5 +-
 qapi/block-core.json       |  33 ++-
 qemu-img.c                 |   2 +-
 replication.c              |  96 +++++++
 replication.h              | 175 +++++++++++++
 tests/.gitignore           |   1 +
 tests/Makefile             |   4 +
 tests/test-replication.c   | 505 ++++++++++++++++++++++++++++++++++++
 16 files changed, 1725 insertions(+), 10 deletions(-)
 create mode 100644 block/replication.c
 create mode 100644 docs/block-replication.txt
 create mode 100644 replication.c
 create mode 100644 replication.h
 create mode 100644 tests/test-replication.c

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1.9.3