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Re: [Qemu-block] [PATCH 2/5] block/qcow2-bitmap: Allow bitmap flushing
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
Re: [Qemu-block] [PATCH 2/5] block/qcow2-bitmap: Allow bitmap flushing |
Date: |
Wed, 6 Mar 2019 16:12:13 +0000 |
06.03.2019 18:59, John Snow wrote:
>
>
> On 3/6/19 7:58 AM, Eric Blake wrote:
>> On 3/5/19 5:43 PM, John Snow wrote:
>>> Usually, we only write out bitmaps when we're about to close out the file,
>>> so we always remove the bitmaps after to make it easier to determine the
>>> source of truth for migration purposes.
>>>
>>> However, there may be times we want to flush bitmap data more aggressively,
>>> like after a truncate event where we need to make the metadata consistent
>>> again.
>>
>> Or, as I've mentioned in other threads, after every
>> bitmap-add/bitmap-delete operation, so that 'qemu-img info -U' can see
>> which persistent bitmaps exist. But that's one step further than this
>> series, so I won't insist on it today.
>>
>
> Yes, I was keeping that in mind as I wrote this. I think it extends to
> those cases trivially, so long as Vladimir is OK with what I'm trying to do.
>
I still don't see the point of flushing bitmaps, the only thing is optimizing
qemu-img info --force-share, which should never used except for debugging.
So, at least, if we'll have it, I'd prefer bitmap flushing to be optional,
and other code should not rely on it.
--
Best regards,
Vladimir
- Re: [Qemu-block] [PATCH 1/5] block/qcow2-bitmap: Skip length check in some cases, (continued)
[Qemu-block] [PATCH 4/5] block/qcow2-bitmap: Allow resizes with persistent bitmaps, John Snow, 2019/03/05
- Re: [Qemu-block] [PATCH 4/5] block/qcow2-bitmap: Allow resizes with persistent bitmaps, Vladimir Sementsov-Ogievskiy, 2019/03/06
- Re: [Qemu-block] [PATCH 4/5] block/qcow2-bitmap: Allow resizes with persistent bitmaps, John Snow, 2019/03/06
- Re: [Qemu-block] [PATCH 4/5] block/qcow2-bitmap: Allow resizes with persistent bitmaps, Vladimir Sementsov-Ogievskiy, 2019/03/06
- Re: [Qemu-block] [PATCH 4/5] block/qcow2-bitmap: Allow resizes with persistent bitmaps, Vladimir Sementsov-Ogievskiy, 2019/03/06
- Re: [Qemu-block] [PATCH 4/5] block/qcow2-bitmap: Allow resizes with persistent bitmaps, John Snow, 2019/03/08
[Qemu-block] [PATCH 5/5] tests/qemu-iotests: add bitmap resize test 246, John Snow, 2019/03/05