Re: [Qemu-devel] [PATCH v5 10/21] qmp: Add support of "dirty-bitmap" sync mode for drive-backup

[Eric Blake <eblake@redhat.com>]

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On 04/08/2015 04:19 PM, John Snow wrote:
> For "dirty-bitmap" sync mode, the block job will iterate through the
> given dirty bitmap to decide if a sector needs backup (backup all the
> dirty clusters and skip clean ones), just as allocation conditions of
> "top" sync mode.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  block.c                   |   9 +++
>  block/backup.c            | 156 +++++++++++++++++++++++++++++++++++++++-------
>  block/mirror.c            |   4 ++
>  blockdev.c                |  18 +++++-
>  hmp.c                     |   3 +-
>  include/block/block.h     |   1 +
>  include/block/block_int.h |   2 +
>  qapi/block-core.json      |  13 ++--
>  qmp-commands.hx           |   7 ++-
>  9 files changed, 180 insertions(+), 33 deletions(-)
> 

Just reviewing the interface...

> +++ b/qapi/block-core.json
> @@ -512,10 +512,12 @@
>  #
>  # @none: only copy data written from now on
>  #
> +# @dirty-bitmap: only copy data described by the dirty bitmap. Since: 2.4
> +#
>  # Since: 1.3
>  ##
>  { 'enum': 'MirrorSyncMode',
> -  'data': ['top', 'full', 'none'] }
> +  'data': ['top', 'full', 'none', 'dirty-bitmap'] }
>  
>  ##
>  # @BlockJobType:
> @@ -690,14 +692,17 @@
>  #          probe if @mode is 'existing', else the format of the source
>  #
>  # @sync: what parts of the disk image should be copied to the destination
> -#        (all the disk, only the sectors allocated in the topmost image, or
> -#        only new I/O).
> +#        (all the disk, only the sectors allocated in the topmost image, from a
> +#        dirty bitmap, or only new I/O).
>  #
>  # @mode: #optional whether and how QEMU should create a new image, default is
>  #        'absolute-paths'.
>  #
>  # @speed: #optional the maximum speed, in bytes per second
>  #
> +# @bitmap: #optional the name of dirty bitmap if sync is "dirty-bitmap"
> +#          (Since 2.4)
> +#
>  # @on-source-error: #optional the action to take on an error on the source,
>  #                   default 'report'.  'stop' and 'enospc' can only be used
>  #                   if the block device supports io-status (see BlockInfo).
> @@ -715,7 +720,7 @@
>  { 'type': 'DriveBackup',
>    'data': { 'device': 'str', 'target': 'str', '*format': 'str',
>              'sync': 'MirrorSyncMode', '*mode': 'NewImageMode',
> -            '*speed': 'int',
> +            '*speed': 'int', '*bitmap': 'str',

Looks okay.  Is it an error if bitmap is supplied, but mode is not
dirty-bitmap?  Likewise, if mode is dirty-bitmap but bitmap is not supplied?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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