Reviewed: https://review.openstack.org/584999
Committed:
https://git.openstack.org/cgit/openstack/nova/commit/?id=1ba150fa5233ebeacdc02e89b2e83a1a6861bc19
Submitter: Zuul
Branch: master
commit 1ba150fa5233ebeacdc02e89b2e83a1a6861bc19
Author: Sean Mooney <w...@seanmooney.info>
Date: Tue Jul 31 21:22:52 2018 +0100
libvirt: fix disk_bus handling for root disk
- The hw_disk_bus image metadata key allows users
to specify the bus to which guest hard disk
images are attached for libvirt instances.
- In commit 7be531fe9462f2b07d4a1abf6687f649d1dfbb89
the libvirt disk mappings were refactored. As
part of that change a lossy conversion was introduced
which resulted in multiple disk buses being mapped
to the same block device prefix.
- As a result of this lossy mapping hw_disk_bus=sata
and hw_disk_bus=usb were mapped to the same prefix
as scsi "sd". this resulted in the request to use
sata or usb root disk being ignored.
- This change fixes handling of the root
disk device bus selection in libvirt blockinfo.py
by using the disk bus provided instead of inferring
it from the block device name.
- This change adds a new unit test to
assert the correct handeling
of the hw_disk_bus image metadata key
in the libvirt driver.
Change-Id: I63836f461507f4924dc8f3491ef518a4ce4d32f9
Closes-Bug: 1759420
** Changed in: nova
Status: In Progress => Fix Released
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https://bugs.launchpad.net/bugs/1759420
Title:
nova does not correctly support HW_DISK_BUS=sata or usb for kvm/qemu
Status in OpenStack Compute (nova):
Fix Released
Bug description:
Description
===========
The hw_disk_bus image metadata key
https://github.com/openstack/glance/blob/master/etc/metadefs/compute-libvirt-image.json#L13-L27
allows users to specify the bus to which guest hard disk images are attched
for libvirt instances.
The valid values of hw_disk_bus are
["scsi","virtio","uml","xen","ide","usb","fdc","sata"]
The libvirt driver also defieds the list of valid buses per virt_type
here
https://github.com/openstack/nova/blob/ef0ce4d692d28a7f5a0079e24acdbfe7d2767e8b/nova/virt/libvirt/blockinfo.py#L199-L206
valid_bus = {
'qemu': ['virtio', 'scsi', 'ide', 'usb', 'fdc', 'sata'],
'kvm': ['virtio', 'scsi', 'ide', 'usb', 'fdc', 'sata'],
'xen': ['xen', 'ide'],
'uml': ['uml'],
'lxc': ['lxc'],
'parallels': ['ide', 'scsi']
}
when setting this key to sata or usb instead of having the disk attached to
the requested bus
the disk is attached to the scsi bus instead.
this is because in nova/virt/libvirt/blockinfo.py we map form the disk bus to
a prefix
in get_dev_prefix_for_disk_bus
https://github.com/openstack/nova/blob/ef0ce4d692d28a7f5a0079e24acdbfe7d2767e8b/nova/virt/libvirt/blockinfo.py#L124-L143
then later we guess what the correct bus is from the prefix in
get_disk_bus_for_disk_dev
https://github.com/openstack/nova/blob/ef0ce4d692d28a7f5a0079e24acdbfe7d2767e8b/nova/virt/libvirt/blockinfo.py#L297-L304
this mapping form disk bus to prefix is lossy as as sata/scsi and usb
are all mapped to the sd prefix. so when we guess in
get_disk_bus_for_disk_dev for kvm that resutin the incorrect value for
images with hw_disk_bus=sata or hw_disk_bus=usb.
Steps to reproduce
==================
run devstack with default setting
source openrc
set hw_disk_bus=sata on image
e.g. openstack image set --property hw_disk_bus=sata my-image
boot a vm with that image
run virsh dumpxml on instance and check the disk bus.
Expected result
===============
instance boots and disk bus used matches hw_disk_bus image metadata value.
e.g. sata
Actual result
=============
instnace boots and disk bus used is scsi
Environment
===========
1. Exact version of OpenStack you are running. See the following
stable/pike but this is present in master and has been an issue for 5 years
since
https://github.com/openstack/nova/commit/7be531fe9462f2b07d4a1abf6687f649d1dfbb89#diff-2701504299cd384f46791e08f1849defR293
incorrectly called get_disk_bus_for_disk_dev instead of useing the disk_bus
varible.
2. Which hypervisor did you use?
Libvirt + KVM
2. Which storage type did you use?
default local image backend for nova.
3. Which networking type did you use?
Neutron with OpenVSwitch.
not related to this issue.
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