Comment 116 for bug 1505564

Testing patches I have attached above:

inaddy@sf00090138trusty(~)$ sudo qemu-img create -f qcow2 -o preallocation=metadata ./test.qcow2 1G
Formatting './test.qcow2', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 preallocation='metadata' lazy_refcounts=off

inaddy@sf00090138trusty(~)$ sudo qemu-nbd --connect=/dev/nbd0 ./test.qcow2

[ 34.348125] nbd: registered device at major 43
[ 317.034493] nbd0: unknown partition table

inaddy@sf00090138trusty(~)$ sudo fdisk /dev/nbd0

     Device Boot Start End Blocks Id System
/dev/nbd0p1 2048 2097151 1047552 83 Linux

inaddy@sf00090138trusty(~)$ sudo mkfs.ext3 /dev/nbd0p1

inaddy@sf00090138trusty(~)$ sudo mkfs.ext3 /dev/nbd0p1

inaddy@sf00090138trusty(~)$ sudo mount /dev/nbd0p1 /mnt

inaddy@sf00090138trusty(/mnt)$ dd if=/dev/zero of=./teste bs=1M count=256 oflag=direct
256+0 records in
256+0 records out
268435456 bytes (268 MB) copied, 1.15586 s, 232 MB/s

Hopefully they won't cause any regression the PPA to be provided soon.