[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when o
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening |
Date: |
Wed, 11 May 2016 10:04:12 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
"Daniel P. Berrange" <address@hidden> writes:
> On Tue, May 10, 2016 at 01:11:30PM +0100, Richard W.M. Jones wrote:
>> At no point did I say that it was safe to use libguestfs on live VMs
>> or that you would always get consistent data out.
>>
>> But the fact that it can fail is understood, the chance of failure is
>> really tiny (it has literally only happened twice that I've read
>> corrupted data, in years of daily use), and the operation is very
>> useful.
>>
>> So I think this patch series should either not lock r/o VMs, or should
>> add a nolock flag to override the locking (which libguestfs will
>> always use).
>
> If QEMU locks r/o disks, then libvirt would likely end up setting the
> "nolock" flag unconditionally too, in order to avoid breaking libguestfs
> and other application usage of libvirt.
Could a QEMU + libvirt together provide both safe and unsafe read-only
access? Safe means you get consistent data. Unsafe means you're taking
your chances.
Libguestfs could then use unsafe if the user asks for it. Or even by
default; that's really libguesfs's business.
Backward compatibility may complicate things, but getting into a
reasonable state is sometimes worth a lengthy and somewhat messy
transition.
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, (continued)
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Daniel P. Berrange, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Richard W.M. Jones, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Richard W.M. Jones, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Richard W.M. Jones, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Daniel P. Berrange, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening,
Markus Armbruster <=
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Daniel P. Berrange, 2016/05/11
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Fam Zheng, 2016/05/11
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Richard W.M. Jones, 2016/05/11
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/11
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Daniel P. Berrange, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Kevin Wolf, 2016/05/10
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening, Richard W.M. Jones, 2016/05/10
Re: [Qemu-block] [PATCH v4 00/27] block: Lock images when opening, Richard W.M. Jones, 2016/05/11