Re: [Qemu-devel] [PATCH v3 8/9] qmp: Add support of "dirty-bitmap" sync mode for drive-backup

[Eric Blake <eblake@redhat.com>]

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On 03/17/2014 01:46 AM, Fam Zheng 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.
> 
> There are two bitmap use modes for sync=dirty-bitmap:
> 
>  - reset: backup job makes a copy of bitmap and resets the original
>    one.
>  - consume: backup job makes the original anonymous (invisible to user)
>    and releases it after use.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---

> +++ b/qapi-schema.json
> @@ -1532,7 +1532,7 @@
>  # Since: 1.3
>  ##
>  { 'enum': 'MirrorSyncMode',
> -  'data': ['top', 'full', 'none'] }
> +  'data': ['top', 'full', 'none', 'dirty-bitmap'] }

dirty-bitmap needs documentation.

>  
>  ##
>  # @BlockJobType:
> @@ -1908,6 +1908,22 @@
>    'data': { 'device': 'str', 'name': 'str' } }
>  
>  ##
> +# @BitmapUseMode
> +#
> +# An enumeration that tells QEMU what operation to take when consuming a bitmap
> +# a new image file.

s/bitmap/bitmap in/

> +#
> +# @consume: QEMU should just consume the bitmap and release it after using
> +#
> +# @reset: QEMU should keep an internal copy of the bitmap and reset the
> +#         dirty record from original one

I'm not quite sure what these terms mean when reading this in isolation;
reading the entire patch gives a better picture but I'm wondering if we
could make these two descriptions carry a bit more information.

> @@ -1058,8 +1058,9 @@ Arguments:
>              (json-string, optional)
>  - "sync": what parts of the disk image should be copied to the destination;
>    possibilities include "full" for all the disk, "top" for only the sectors
> -  allocated in the topmost image, or "none" to only replicate new I/O
> -  (MirrorSyncMode).
> +  allocated in the topmost image, "dirty-bitmap" for only sync the dirty

s/sync //

> +  sectors in the bitmap, or "none" to only replicate new I/O (MirrorSyncMode).
> +- "bitmap": bitmap name to use for sync==dirty-bitmap
>  - "mode": whether and how QEMU should create a new image
>            (NewImageMode, optional, default 'absolute-paths')
>  - "speed": the maximum speed, in bytes per second (json-int, optional)
> 

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


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