From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: Max Reitz <mreitz@redhat.com>,
"qemu-block@nongnu.org" <qemu-block@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 3/3] vpc: Do not return RAW from block_status
Date: Mon, 12 Aug 2019 16:50:11 +0000 [thread overview]
Message-ID: <eaf85ded-c537-ceb3-9277-6765bb672daa@virtuozzo.com> (raw)
In-Reply-To: <f50d585c-ac91-5dfa-365b-efda321aeffa@redhat.com>
12.08.2019 18:56, Max Reitz wrote:
> On 12.08.19 17:33, Vladimir Sementsov-Ogievskiy wrote:
>> 25.07.2019 18:55, Max Reitz wrote:
>>> vpc is not really a passthrough driver, even when using the fixed
>>> subformat (where host and guest offsets are equal). It should handle
>>> preallocation like all other drivers do, namely by returning
>>> DATA | RECURSE instead of RAW.
>>>
>>> There is no tangible difference but the fact that bdrv_is_allocated() no
>>> longer falls through to the protocol layer.
>>
>> Hmm. Isn't a real bug (fixed by this patch) ?
>>
>> Assume vpc->file is qcow2 with backing, which have "unallocated" region, which is
>> backed by actual data in backing file.
>
> Come on now.
>
>> So, this region will be reported as not allocated and will be skipped by any copying
>> loop using block-status? Is it a bug of BDRV_BLOCK_RAW itself? Or I don't understand
>> something..
>
> I think what you don’t understand is that if you have a vpc file inside
> of a qcow2 file, you’re doing basically everything wrong. ;-)
>
> But maybe we should drop BDRV_BLOCK_RAW... Does it do anything good for
> us in the raw driver? Shouldn’t it too just return DATA | RECURSE?
>
And if I have raw driver above qcow2, it will not work, like I've described above..
--
Best regards,
Vladimir
next prev parent reply other threads:[~2019-08-12 16:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 15:55 [Qemu-devel] [PATCH 0/3] block: Make various formats' block_status recurse again Max Reitz
2019-07-25 15:55 ` [Qemu-devel] [PATCH 1/3] vdi: Make block_status recurse for fixed images Max Reitz
2019-08-12 14:47 ` Vladimir Sementsov-Ogievskiy
2019-07-25 15:55 ` [Qemu-devel] [PATCH 2/3] vmdk: Make block_status recurse for flat extents Max Reitz
2019-08-12 14:59 ` Vladimir Sementsov-Ogievskiy
2019-07-25 15:55 ` [Qemu-devel] [PATCH 3/3] vpc: Do not return RAW from block_status Max Reitz
2019-08-12 15:33 ` Vladimir Sementsov-Ogievskiy
2019-08-12 15:56 ` Max Reitz
2019-08-12 16:50 ` Vladimir Sementsov-Ogievskiy [this message]
2019-08-12 19:07 ` Max Reitz
2019-08-13 10:38 ` Kevin Wolf
2019-08-13 14:49 ` Max Reitz
2019-08-12 18:39 ` [Qemu-devel] [Qemu-block] [PATCH 0/3] block: Make various formats' block_status recurse again John Snow
2019-08-12 19:11 ` Max Reitz
2019-08-12 21:45 ` John Snow
2019-08-13 14:48 ` Max Reitz
2019-08-13 22:35 ` John Snow
2019-08-15 15:49 ` [Qemu-devel] " Max Reitz
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