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Subject: Re: [Qemu-devel] 'qemu-nbd' explicite flush to disk
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To: Mark Trumpold <Mark.Trumpold@tachyon.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

Il 12/09/2012 23:28, Mark Trumpold ha scritto:
> So, I've been experimenting with 'qemu-nbd --cache=writeback ..'
> This nicely eliminates the 'checkpoint' issue; however, I have as
> yet been unable to explicitely flush things to disk -- which I would like to
> do just before a 'nilfs' snapshot.

The Linux kernel driver for NBD does not support flushes.  Patches were
sent to the maintainer, but he never applied them.

You can get them at
http://thread.gmane.org/gmane.linux.drivers.nbd.general/1108 and try them.

> Subsequently I've been trying to call 'bdrv_co_flush(bs)' directly, but I can't figure out how to dereference 'bs' for the call.
> 
> I'm probably out in the weeds on this one.
> Any guidance would be greatly appreciated.
> 
> I am running:
>     qemu-1.2.0
>     linux kernel 3.3.1
> 
> Thank you,
> Mark Trumpold
> 
> 
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I doubt so, since this is a public mailing list.

Paolo