[Nbd] Issues with the blocksize

[Goswin von Brederlow <goswin-v-b@...186...>]

Hi,

I start a NBD device under Linux with:

    % nbd-client localhost /dev/nbd0 -block-size 4096 -name test
    Negotiation: ..size = 16MB
    bs=4096, sz=16777216 bytes

I would expect that the blocksize would work the same as with physical
disks with 4k sectors. Specifically that programs like GNU Parted would
recognise them:

    (parted) p                                                                
    Model: Unknown (unknown)
    Disk /dev/nbd0: 16.8MB
    Sector size (logical/physical): 512B/512B
    ...

Parted should see a physical sector size of 4096B there.


The other issue I have is that I would like the server and client to
negotiate the blocksize during the handshake. If the server is exporting
a disk with 4k it should be able to tell the client that fact so it can
communicate that to its kernel. Can we add a new option for this to the
new style handshake?

MfG
        Goswin