Re: [Qemu-devel] [PATCH V6 0/8] add internal snapshot support at block device level

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

>    This series brings internal snapshot support at block devices
level, now we
> have two three methods to do block snapshot lively: 1) backing chain,
> 2) internal one and 3) drive-back up approach.
> 
> Comparation:
>               Advantages:                            Disadvantages:
> 1)    delta data, taken fast, export, size        performance, delete slow.
> 2)  taken fast, delete fast, performance, size       delta data, format
> 3)      performance, export, format               taken slow, delta data, size
> 
>    I think in most case, saving vmstate in an standalone file is better than
> saving it inside qcow2, So suggest treat internal snapshot as block level
> methods and not encourage user to savevm in qcow2 any more.
> 
> Implemention details:
>    To avoid trouble, this serial have hide ID in create interfaces, this make
> sure no chaos of ID and name will be introduced by these interfaces.
>    There is one patch may be common to Pavel's savvm transaction, patch 1/11,
> others are not quite related. Patch 1/11 will not set errp when no snapshot
> find, since patch 3/11 need to distinguish real error case.
> 
> Next steps to better full VM snapshot:
>    Improve internal snapshot's export capability.
>    Better vmstate saving.
> 
>    Thanks Kevin to give advisement about how add it in qmp_transaction, oldest
> version comes drom Dietmar Maurer.
> 
> v3:
>    General:
>    Rebased after Stenfan's driver-backup patch V6.
> 
>    Address Eric's comments:
>    4/9: grammar fix and better doc.
>    5/9: parameter name is mandatory now. grammar fix.
>    6/9: redesiged interface: take both id and name as optional parameter, return
> the deleted snapshot's info.
> 
>    Address Stefan's comments:
>    4/9: add '' around %s in message. drop code comments about vm_clock.
>    9/9: better doc, refined the code and add more test case.
> 
> v4:
>    Address Stefan's comments:
>    4/9: use error_setg_errno() to show error reason for bdrv_snapshot_create(),
> spell fix and better doc.
>    5/9: better doc.
>    6/9: remove spurious ';' in code, spell fix and better doc.
> 
> v5:
>    Address Kevin's comments:
>    3/8, 4/8, 8/8: remove the limit of numeric snapshot name.
>    General change:
>    4/8: use existing type as parameter in qapi schema.
> 
> v6:
>    Address Stefan's comments:
>    2/8: macro STR_PRINT_CHAR was renamed as STR_OR_NULL, and moved into patch 5,
> since implement function in this patch do not printf snapshot id any more, as
> Kevin's suggestion.
>    Address Kevin's comments:
>    2/8: remove device, id, name info in the error message, use error message in
> existing caller. A new function bdrv_snapshot_delete_by_id_or_name() is added
> to make the usage clear while keep logic unchanged.
>    3/8: remove device info in error message when name is empty. Use else if
> after call of bdrv_snapshot_find_by_id_and_name().
>    Other:
>    2/8: refined the comments in code for bdrv_snapshot_delete().
>    3/8: in error reporting, change format from "reason is: '%s'" to
> "reason is: %s".
> 
> Wenchao Xia (8):
>    1 snapshot: new function bdrv_snapshot_find_by_id_and_name()
>    2 snapshot: distinguish id and name in snapshot delete
>    3 qmp: add internal snapshot support in qmp_transaction
>    4 qmp: add interface blockdev-snapshot-internal-sync
>    5 qmp: add interface blockdev-snapshot-delete-internal-sync
>    6 hmp: add interface hmp_snapshot_blkdev_internal
>    7 hmp: add interface hmp_snapshot_delete_blkdev_internal
>    8 qemu-iotests: add 056 internal snapshot for block device test case
> 
>   block/qcow2-snapshot.c     |   55 +++++++---
>   block/qcow2.h              |    5 +-
>   block/rbd.c                |   21 ++++-
>   block/sheepdog.c           |    5 +-
>   block/snapshot.c           |  131 ++++++++++++++++++++++-
>   blockdev.c                 |  190 ++++++++++++++++++++++++++++++++
>   hmp-commands.hx            |   37 ++++++-
>   hmp.c                      |   22 ++++
>   hmp.h                      |    2 +
>   include/block/block_int.h  |    5 +-
>   include/block/snapshot.h   |   14 +++-
>   include/qemu-common.h      |    3 +
>   qapi-schema.json           |   65 +++++++++++-
>   qemu-img.c                 |   11 ++-
>   qmp-commands.hx            |  104 ++++++++++++++++--
>   savevm.c                   |   32 +++---
>   tests/qemu-iotests/056     |  259 ++++++++++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/056.out |    5 +
>   tests/qemu-iotests/group   |    1 +
>   19 files changed, 913 insertions(+), 54 deletions(-)
>   create mode 100755 tests/qemu-iotests/056
>   create mode 100644 tests/qemu-iotests/056.out
> 
> 
Hello,
  any comments for this version? I just found 056 is taken in
upstream this morning, may respin if you like.

-- 
Best Regards

Wenchao Xia