From: Avi Kivity <avi@qumranet.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Signal handling and qcow2 image corruption
Date: Thu, 06 Mar 2008 08:57:22 +0200 [thread overview]
Message-ID: <47CF95D2.4070704@qumranet.com> (raw)
In-Reply-To: <47CF16C5.6040102@codemonkey.ws>
Anthony Liguori wrote:
> David Barrett wrote:
>> I'm tracking down a image corruption issue and I'm curious if you can
>> answer the following:
>>
>> 1) Is there any difference between sending a "TERM" signal to the
>> QEMU process and typing "quit" at the monitor?
>
> Yes. Since QEMU is single threaded, when you issue a quit, you know
> you aren't in the middle of writing qcow2 meta data to disk.
>
That's not enough. If you write a metadata pointer before allocating
and writing the block, and you terminate between these two operations,
the next write allocation will leave two pointers pointing to the same
block.
I don't know if qemu is susceptible to this.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2008-03-06 7:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-05 21:18 [Qemu-devel] Signal handling and qcow2 image corruption David Barrett
2008-03-05 21:55 ` Anthony Liguori
2008-03-05 23:48 ` David Barrett
2008-03-06 6:57 ` Avi Kivity [this message]
2008-07-21 18:10 ` [Qemu-devel] qcow2 - safe on kill? safe on power fail? Jamie Lokier
2008-07-21 19:43 ` Anthony Liguori
2008-07-21 21:26 ` Jamie Lokier
2008-07-21 22:14 ` Anthony Liguori
2008-07-21 23:47 ` Jamie Lokier
2008-07-22 6:06 ` Avi Kivity
2008-07-22 14:08 ` Anthony Liguori
2008-07-22 14:46 ` Jamie Lokier
2008-07-22 19:11 ` Avi Kivity
2008-07-22 14:32 ` Jamie Lokier
2008-07-21 22:00 ` Andreas Schwab
2008-07-21 22:15 ` Anthony Liguori
2008-07-21 22:22 ` David Barrett
2008-07-21 22:50 ` Anthony Liguori
2008-07-22 6:07 ` Avi Kivity
2008-07-22 14:11 ` Anthony Liguori
2008-07-22 14:36 ` Avi Kivity
2008-07-22 16:16 ` Jamie Lokier
2008-07-22 19:13 ` Avi Kivity
2008-07-22 20:04 ` Jamie Lokier
2008-07-22 21:25 ` Avi Kivity
2008-07-22 14:22 ` Jamie Lokier
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