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Re: [PATCH v5 1/4] block: support compressed write at generic layer
From: |
Andrey Shinkevich |
Subject: |
Re: [PATCH v5 1/4] block: support compressed write at generic layer |
Date: |
Thu, 24 Oct 2019 12:56:44 +0000 |
On 24/10/2019 12:34, Max Reitz wrote:
> On 22.10.19 15:53, Andrey Shinkevich wrote:
>
> [...]
>
>> If the support of COW for compressed writes is found feasible, will it
>> make a sense to implement? Then this series will follow.
>
> Hm, what exactly do you mean by support of COW for compressed writes?
>
I spoke in terms of the commit message with the following ID:
b0b6862e5e1a1394e0ab3d5da94ba8b0da8664e2
"qcow2: Fail write_compressed when overwriting data"
"...qcow2_write_compressed() doesn't perform COW as it would have to do..."
So, I suggest that we implement writing compressed data to the allocated
clusters rather than qcow2_alloc_compressed_cluster_offset() returns the
error. Particularly, when it comes to NBD server connection failure for
writhing a compressed cluster, it may not be rewritten after the
connection is restored.
Are there any issues with that implementation idea?
Andrey
>> A comment for the option would warn a user that guest writing will work
>> slower for if compress selected.
>
> I’m not sure whether that’s necessary. As a user, I would assume that
> enabling compression will always make something slower.
>
> Max
>
- [PATCH v5 0/4] qcow2: advanced compression options, Andrey Shinkevich, 2019/10/20
- [PATCH v5 1/4] block: support compressed write at generic layer, Andrey Shinkevich, 2019/10/20
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Max Reitz, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Andrey Shinkevich, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Vladimir Sementsov-Ogievskiy, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Max Reitz, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Vladimir Sementsov-Ogievskiy, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Max Reitz, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Andrey Shinkevich, 2019/10/22
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Max Reitz, 2019/10/24
- Re: [PATCH v5 1/4] block: support compressed write at generic layer,
Andrey Shinkevich <=
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Max Reitz, 2019/10/24
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Andrey Shinkevich, 2019/10/24
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Max Reitz, 2019/10/24
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Andrey Shinkevich, 2019/10/24
- Re: [PATCH v5 1/4] block: support compressed write at generic layer, Vladimir Sementsov-Ogievskiy, 2019/10/22
[PATCH v5 3/4] tests/qemu-iotests: add case to write compressed data of multiple clusters, Andrey Shinkevich, 2019/10/20
[PATCH v5 2/4] qcow2: Allow writing compressed data of multiple clusters, Andrey Shinkevich, 2019/10/20
[PATCH v5 4/4] tests/qemu-iotests: add case for block-stream compress, Andrey Shinkevich, 2019/10/20