Re: [Qemu-devel] [Nbd] [PATCH 2/2] NBD proto: add GET_LBA_STATUS extension

[Alex Bligh]

On 24 Mar 2016, at 09:33, Wouter Verhelst <address@hidden> wrote:

> Now I'm not saying we
> need to fully define what it means for a part of the backend to be
> "dirty" or not.  It's okay to leave part of the meaning in the dark,
> leaving that implementation-defined.

Well, the 3 possible states are:

* unallocated
* zero
* non-zero

So the possible replies are a bitfield of those, with a '1' if it 'might'
be in that state, i.e.

111 = no idea
110 = might be zero or unallocated, but isn't zero
011 = I know it's allocated, but I don't know whether it is zero or not

And '000' is not permitted!

etc.


--
Alex Bligh

signature.asc
Description: Message signed with OpenPGP using GPGMail