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Re: [Qemu-devel] [PATCH v2 5/7] QAPI: add command for live block commit,
From: |
Jeff Cody |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/7] QAPI: add command for live block commit, 'block-commit' |
Date: |
Wed, 26 Sep 2012 10:25:14 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0 |
On 09/26/2012 10:13 AM, Kevin Wolf wrote:
> Am 25.09.2012 18:29, schrieb Jeff Cody:
>> The command for live block commit is added, which has the following
>> arguments:
>>
>> device: the block device to perform the commit on (mandatory)
>> base: the base image to commit into; optional (if not specified,
>> it is the underlying original image)
>> top: the top image of the commit - all data from inside top down
>> to base will be committed into base. optional (if not specified,
>> it is one below the active image) - see note below
>> speed: maximum speed, in bytes/sec
>>
>> note: eventually this will support merging down the active layer,
>> but that code is not yet complete. If the active layer is passed
>> in currently as top, or top is left to the default, then an error
>> will be returned.
>>
>> The is done as a block job, so upon completion a BLOCK_JOB_COMPLETED will
>> be emitted.
>>
>> Signed-off-by: Jeff Cody <address@hidden>
>
>> diff --git a/qapi-schema.json b/qapi-schema.json
>> index 14e4419..e614453 100644
>> --- a/qapi-schema.json
>> +++ b/qapi-schema.json
>> @@ -1468,6 +1468,41 @@
>> 'returns': 'str' }
>>
>> ##
>> +# @block-commit
>> +#
>> +# Live commit of data from overlay image nodes into backing nodes - i.e.,
>> +# writes data between 'top' and 'base' into 'base'.
>> +#
>> +# @device: the name of the device
>> +#
>> +# @base: #optional The file name of the backing image to write data into.
>> +# If not specified, this is the deepest backing image
>> +#
>> +# @top: #optional The file name of the backing image within the image
>> chain,
>> +# which contains the topmost data to be committed down.
>> +# If not specified, this is one layer below the active
>> +# layer (i.e. active->backing_hd).
>
> Why isn't active the default any more? I know, we don't support it yet,
> but long term this is what makes most sense as a default.
>
Eric had a similar question, and asked if anyone had any preference -
this was my response:
---
I guess I don't have a strong preference either - I originally had it
the other way, but then that meant the default in the current
implementation was actually an error.
Also, I assumed (danger!) that the most common use of commit would be a
snapshot, followed by a commit of active->backing_hd. With that
assumption, it seemed like a sane default.
---
I can certainly revert back to having the active layer be the top, if
that is the preference.
>> +#
>> +# If top == base, that is an error.
>> +#
>> +#
>> +# @speed: #optional the maximum speed, in bytes per second
>> +#
>> +# Returns: Nothing on success
>> +# If commit or stream is already active on this device, DeviceInUse
>> +# If @device does not exist, DeviceNotFound
>> +# If image commit is not supported by this device, NotSupported
>> +# If @base does not exist, a generic error is returned
>> +# If @top does not exist, a generic error is returned
>> +# If @speed is invalid, InvalidParameter
>> +#
>> +# Since: 1.3
>> +#
>> +##
>> +{ 'command': 'block-commit',
>> + 'data': { 'device': 'str', '*base': 'str', '*top': 'str',
>> + '*speed': 'int' } }
>
> Kevin
>
- [Qemu-devel] [PATCH v2 1/7] block: add support functions for live commit, to find and delete images., (continued)
- [Qemu-devel] [PATCH v2 1/7] block: add support functions for live commit, to find and delete images., Jeff Cody, 2012/09/25
- [Qemu-devel] [PATCH v2 3/7] blockdev: rename block_stream_cb to a generic block_job_cb, Jeff Cody, 2012/09/25
- [Qemu-devel] [PATCH v2 4/7] block: helper function, to find the base image of a chain, Jeff Cody, 2012/09/25
- [Qemu-devel] [PATCH v2 5/7] QAPI: add command for live block commit, 'block-commit', Jeff Cody, 2012/09/25
- [Qemu-devel] [PATCH v2 6/7] qemu-iotests: add initial tests for live block commit, Jeff Cody, 2012/09/25
- [Qemu-devel] [PATCH v2 7/7] block: after creating a live snapshot, make old image read-only, Jeff Cody, 2012/09/25