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Date: Thu, 28 Apr 2011 16:42:20 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2 1/1] Add QMP bits for
	blockdev-snapshot-sync.
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To: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>

Am 28.04.2011 15:46, schrieb Jes Sorensen:
> On 04/28/11 15:41, Kevin Wolf wrote:
>>>> Finally, what's the expect behavior when -snapshot is used? I'm getting
>>>>>> this:
>>>>>>
>>>>>>  (qemu) snapshot_blkdev ide0-hd0 snap-test
>>>>>>  Could not open '/tmp/vl.6w8YXA'
>>>>>>  (qemu)
>>>>
>>>> What type of file system is your /tmp? You need to provide full path to
>>>> the snapshot file if you don't want it created next to where your qemu
>>>> binary is being executed.
>> I think the problem is that this is a temporary file, i.e. unlinked
>> directly after it has been opened. Trying to reopen a deleted file is a
>> bad idea.
> 
> True, but if /tmp is tmpfs, it isn't possible to open things O_DIRECT,
> which could also be the source of the problem here.

Not really, -snapshot is very clearly the problem here. Note that what's
failing here is not opening the new snapshot but the old temporary image
created by -snapshot.

Kevin