[Qemu-devel] How to find backing file for qemu-nbd?

[Qemu-devel] How to find backing file for qemu-nbd?

[Nikolay Ivanets]

Is there any way to find source file supplied for qemu-nbd similar to loop
device:

cat /sys/block/loop0/loop/backing_file

?

--
    Nikolay Ivanets
    Mobile: +380979184774
    Skype: n_ivanets

Re: [Qemu-devel] How to find backing file for qemu-nbd?

[Daniel P. Berrange]

On Tue, Feb 07, 2017 at 04:25:27PM +0200, Nikolay Ivanets wrote:
> Is there any way to find source file supplied for qemu-nbd similar to loop
> device:
> 
> cat /sys/block/loop0/loop/backing_file

Nothing simple like that - you have to find the qemu-nbd process and see
what file(s) it has open I'm afraid and figure out which is the image file
from there.

Regards,
Daniel
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Re: [Qemu-devel] How to find backing file for qemu-nbd?

[Eric Blake]

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On 02/07/2017 08:25 AM, Nikolay Ivanets wrote:
> Is there any way to find source file supplied for qemu-nbd similar to loop
> device:
> 
> cat /sys/block/loop0/loop/backing_file

qemu-nbd is userspace, so there's no way it will be found in /sys/.  But
since it is userspace, is it not sufficient to just use 'ps' or
/proc/$n/cmdline to determine what command line qemu-nbd was started with?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] How to find backing file for qemu-nbd?

[Nikolay Ivanets]

Yes, it is what i'm doing now: ps -C qemu-nbd -o cmd='.

Thanks!

--
    Nikolay Ivanets
    Mobile: +380979184774
    Skype: n_ivanets

2017-02-07 17:36 GMT+02:00 Eric Blake <eblake@redhat.com>:

> On 02/07/2017 08:25 AM, Nikolay Ivanets wrote:
> > Is there any way to find source file supplied for qemu-nbd similar to
> loop
> > device:
> >
> > cat /sys/block/loop0/loop/backing_file
>
> qemu-nbd is userspace, so there's no way it will be found in /sys/.  But
> since it is userspace, is it not sufficient to just use 'ps' or
> /proc/$n/cmdline to determine what command line qemu-nbd was started with?
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>