Comment 20 for bug 1556819

I've been digging into this issue
- with other images (official cirros release)
- with downgraded qemu packages

and got the same situation - time by time not all files were injected.

I guess that root cause is in nbd module.
On compute node /var/log/sudo.log or /var/log/nova/nova-compute.log (with debug=true) have sequence of commands

qemu-nbd -c /dev/nbd12 /var/lib/nova/instances/16e7efb2-ccbb-411d-83f4-c629dffcc152/disk
mount /dev/nbd12p1 /tmp/openstack-vfs-localfsXC7IqB
readlink -nm /tmp/openstack-vfs-localfsXC7IqB/etc
readlink -e /tmp/openstack-vfs-localfsXC7IqB/etc
readlink -nm /tmp/openstack-vfs-localfsXC7IqB/etc/test0.txt
tee /tmp/openstack-vfs-localfsXC7IqB/etc/test0.txt
readlink -nm /tmp/openstack-vfs-localfsXC7IqB/etc
readlink -e /tmp/openstack-vfs-localfsXC7IqB/etc
...
blockdev --flushbufs /dev/nbd12
umount /dev/nbd12p1
qemu-nbd -d /dev/nbd12

with return code 0 for all, but at the same time we get errors in /var/log/syslog - attempts to send on closed socket.
So socket is closing earlier than "blockdev" and "umoutn" flush buffers into the disk.

But, now this test is 100% passed on MOS 9.0 (build 376) and even old ISOs (where it failed before) with different images.
So as we can't reproduce this issue - I moved to Incomplite. Please, reopen ticket if issue is reproduced again.