Reviewed: https://review.openstack.org/523554 Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=e6ce9557f84cdcdf4ffdd12ce73a008c96c7b94a Submitter: Zuul Branch: master
commit e6ce9557f84cdcdf4ffdd12ce73a008c96c7b94a Author: Thomas Goirand <[email protected]> Date: Tue Nov 28 23:22:56 2017 +0100 qemu-img do not use cache=none if no O_DIRECT support If /var/lib/nova/instances is mounted on a filesystem like tmpfs that doesn't have support for O_DIRECT, "qemu-img convert" currently crashes because it's unconditionally using the "-t none" flag. This patch therefore: - moves the _supports_direct_io() function out of the libvirt driver, from nova/virt/libvirt/driver.py to nova/utils.py and makes it public. - uses that function to decide to use -t none or -t writethrough when converting images with qemu-img. Closes-Bug: #1734784 Co-Authored-By: melanie witt <[email protected]> Change-Id: Ifb47de00abf3f83442ca5264fbc24885df924a19 ** Changed in: nova Status: In Progress => Fix Released -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1734784 Title: Cannot boot instances on filesystem without O_DIRECT support (fails on tmpfs) Status in OpenStack Compute (nova): Fix Released Bug description: I'm trying to (tempest) validate OpenStack Pike for Debian. So I'm running Pike (nova 16.0.3) on Debian Sid. My environment for running tempest is a Debian Live system which I just boot once, install all of OpenStack on, and run tempest. As a consequence, my filesystem is a bit weirdo. It's a single root partition that is using overlayfs, which has its read/write volume on tpmfs. This worked well when validating Newton, but it seems there's a regression with Pike. Here's what happens when trying to boot an instance: Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2192, in _build_resources yield resources File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2007, in _build_and_run_instance block_device_info=block_device_info) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2802, in spawn block_device_info=block_device_info) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 3240, in _create_image fallback_from_host) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 3331, in _create_and_inject_local_root instance, size, fallback_from_host) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 6988, in _try_fetch_image_cache size=size) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 241, in cache *args, **kwargs) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 595, in create_image prepare_template(target=base, *args, **kwargs) File "/usr/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py", line 271, in inner return f(*args, **kwargs) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 237, in fetch_func_sync fetch_func(target=target, *args, **kwargs) File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/utils.py", line 446, in fetch_image images.fetch_to_raw(context, image_id, target) File "/usr/lib/python2.7/dist-packages/nova/virt/images.py", line 171, in fetch_to_raw % {'exp': exp}) ImageUnacceptable: Image f8dc206b-d5a1-4123-b26c-7216d03ab1e7 is unacceptable: Unable to convert image to raw: Image /var/lib/nova/instances/_base/c44b0b620ae7c6fd8111e0abb5a8d1fc39fcdf08.part is unacceptable: Unable to convert image to raw: Unexpected error while running command. Command: qemu-img convert -t none -O raw -f qcow2 /var/lib/nova/instances/_base/c44b0b620ae7c6fd8111e0abb5a8d1fc39fcdf08.part /var/lib/nova/instances/_base/c44b0b620ae7c6fd8111e0abb5a8d1fc39fcdf08.converted Exit code: 1 Stdout: u'' Stderr: u"qemu-img: file system may not support O_DIRECT\nqemu-img: Could not open '/var/lib/nova/instances/_base/c44b0b620ae7c6fd8111e0abb5a8d1fc39fcdf08.converted': Could not open '/var/lib/nova/instances/_base/c44b0b620ae7c6fd8111e0abb5a8d1fc39fcdf08.converted': Invalid argument\n" In this log, the important bit is: file system may not support O_DIRECT Indeed, my weirdo filesystem setup doesn't supports this. I tried to set [libvirt]/disk_cachemodes = file=writethrough, as per recommendation on #openstack-nova, but it didn't fix the problem. It looks like nova doesn't really care about this. Because I also have a small scratch disk to do some cinder tests, and wanted to make sure about this issue, I tried mounting /var/lib/nova/instances on ext4, just to see if there was still the issue. And indeed, it fixed the problem. So, here, nova should check if /var/lib/nova/instances really has O_DIRECT support and use the correct options for libvirt, but it's looking like it isn't doing things properly. This IMO deserves a fix. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1734784/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
