From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel <qemu-devel@nongnu.org>, Chunyan Liu <cyliu@suse.com>
Subject: Re: [Qemu-devel] [PATCH V2] Add -f option to qemu-nbd
Date: Fri, 18 Nov 2011 09:59:12 +0100 [thread overview]
Message-ID: <4EC61E60.2040405@redhat.com> (raw)
In-Reply-To: <4EC64EC90200006600006BCD@novprvlin0050.provo.novell.com>
On 11/18/2011 02:25 AM, Chun Yan Liu wrote:
> Yes. I have tested using same device twice as described in my previous
> mail. Without lock:
>
> If issuing "qemu-nbd -c /dev/nbd0 disk.img" and "qemu-nbd -c /dev/nbd0
> disk1.img" almost at the same time, both can pass nbd_init() and get to
> nbd_client(), then the latter one will fail and exit, but the first one
> does not work well either (fail to show partitions.) That's why I think
> we should add a lock in an earlier time.
This is an initialization problem. As Stefan wrote, functionality for
atomic acquisition of NBD devices is provided by the kernel; the problem
is simply that QEMU does not use it. :)
Paolo
next prev parent reply other threads:[~2011-11-18 8:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-17 11:36 [Qemu-devel] [PATCH V2] Add -f option to qemu-nbd Chunyan Liu
2011-11-17 13:41 ` Paolo Bonzini
2011-11-17 13:52 ` Stefan Hajnoczi
2011-11-18 1:25 ` Chun Yan Liu
2011-11-18 8:59 ` Paolo Bonzini [this message]
2011-11-23 6:51 ` Chun Yan Liu
2011-11-23 7:24 ` Paolo Bonzini
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