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Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1)
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1) |
Date: |
Fri, 23 Nov 2012 11:29:27 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 |
Am 23.11.2012 10:31, schrieb Dietmar Maurer:
>>>>> Filters would be implemented as BlockDrivers, i.e. you could
>>>>> implement
>>>>> .bdrv_co_write() in a filter to intercept all writes to an image.
>>>>
>>>> I am quite unsure if that make things easier.
>>>
>>> At least it would make for a much cleaner design compared to putting
>>> code for every feature you can think of into bdrv_co_do_readv/writev().
>>
>> So if you want to add a filter, you simply modify bs->drv to point to the
>> filter?
>
> Seems the BlockDriver struct does not contain any 'state' (I guess that is by
> design),
> so where do you store filter related dynamic data?
You wouldn't change bs->drv of the block device, you still need that one
after having processed the data in the filter.
Instead, you'd have some BlockDriverState *first_filter in bs to which
requests are forwarded. first_filter->file would point to either the
next filter or if there are no more filters to the real BlockDriverState.
Which raises the question of how to distinguish whether it's a new
request to bs that must go through the filters or whether it actually
comes from the last filter in the chain. As you can see, we don't have a
well thought out plan yet, just rough ideas (otherwise it would probably
be implemented already).
Kevin
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), (continued)
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/21
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Kevin Wolf, 2012/11/21
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/21
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/23
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Kevin Wolf, 2012/11/23
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/23
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/23
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1),
Kevin Wolf <=
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/26
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Paolo Bonzini, 2012/11/26
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/27
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/27
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Kevin Wolf, 2012/11/27
- Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/27
Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Dietmar Maurer, 2012/11/21
Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1), Stefan Hajnoczi, 2012/11/22