Re: userspace block driver?

Paulo Marques
2005-11-09T12:42:38Z

Jeff Garzik wrote:
> Jens Axboe wrote:
>> On Wed, Nov 09 2005, Jeff Garzik wrote:
>>> Neil Brown wrote:
>>>> On Wednesday November 9, jgarzik@pobox.com wrote:
>>>>
>>>>> Has anybody put any thought towards how a userspace block driver
>>>>> would work?
>>>>
>>>> Isn't this was enbd does? http://www.it.uc3m.es/~ptb/nbd/
>>>
>>> Is there something there relevant for modern kernels? I would sure
>>> hope I could come up with something more lightweight than that.
>>
>> I was going to say drbd, but then you did say more lightweight :-)
>[...]
>
> loop is a closer model to a generic userspace block device than nbd, I
> think.

That got me thinking... theoretically we should be able to do a FUSE
server that served a single file that could be used by a loopback
device, couldn't we?

IIRC, Miklos Szeredi tried hard to avoid the deadlock scenarios that nbd
suffers from in FUSE, but I don't know if it would stand being called by
the loopback device.

If it works, it should be extremely simple to do the server. Just check
the FUSE hello world server example:

http://fuse.sourceforge.net/helloworld.html

I've CC'ed Miklos Szeredi to see if he can shed some light on the
loopback <-> FUSE combination...

--
Paulo Marques - www.grupopie.com

The rule is perfect: in all matters of opinion our
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