[SRU] error deleting cloned volumes and parent at the same time when using ceph
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| Cinder |
Fix Released
|
Undecided
|
Unassigned | ||
| Ubuntu Cloud Archive |
Invalid
|
Undecided
|
Unassigned | ||
| Antelope |
Fix Released
|
Undecided
|
Unassigned | ||
| Bobcat |
Fix Released
|
Undecided
|
Unassigned | ||
| Yoga |
Fix Released
|
Undecided
|
Unassigned | ||
| Zed |
Won't Fix
|
Undecided
|
Unassigned | ||
| cinder (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
| Jammy |
Fix Released
|
Undecided
|
Unassigned | ||
Bug Description
******* SRU TEMPLATE AT THE BOTTOM **********
Affects: bobcat and older
A race condition when deleting cloned volumes at the same time as their parent results in the volumes in error_deleting state. The reason it happens is because the code that looks for the parent in [3] may find the original volume or the "<volume>.deleted" renamed volume if the parent has been marked for deletion. The race happens because by running the deletion of both the parent and the child at the same time, the child may see the parent volume before it is marked for deletion, and then in [4] it fails to find it again because it is gone (renamed to "<volume>
Steps to reproduce:
1) openstack volume create --size 1 v1
Wait for volume to be create and available
2) for i in {1..9}; do openstack volume create d$i --source v1 --size 1;done
Wait for all volumes to be created and available
3) openstack volume delete $(openstack volume list --format value -c ID | sort | xargs)
Some volumes may be in error_deleting state.
Workaround: Reset volume state and try to delete again.
Solutions:
a) The issue does not happen in caracal+ because of commit [1] which refactors the code. I tried to reproduce in Caracal with 50 volumes, including grandparent volumes, and I couldn't. If we could backport this fix as far back as Yoga this would address the problem for our users.
b) A single line of code in [2] can address the problem in bobcat and older releases by adding a retry:
@utils.
def delete_volume(self, volume: Volume) -> None:
The retry basically causes the ImageNotFound exception thrown at [4] to retry the delete_volume function, which will then find the "<volume>.deleted" at [3], solving the race condition. It is simpler than adding something more complex directly at [4] where the error happens.
[1] https:/
=======
SRU TEMPLATE
============
[Impact]
Due to a race condition, attempting to delete multiple volumes where among them there is a parent and a child can result in one or more volumes being stuck in error_deleting. The reason is because the childs get updated as the parent is deleted, and if the code had already started deleting the child then the reference changes halfway through and fails. Later, the volumes can still be deleted by resetting the state and retrying, but the user experience is cumbersome.
Upstream has fixed the issue in Caracal by refactoring the delete method with significant behavioural changes (see comment #2), and has backported the refactor to Antelope. Also the refactor code applies to Yoga, it is preferred to implement a simpler fix to address this specific problem in Yoga. The simpler fix is a retry decorator which will force the delete method to re-run, picking up the updated reference of the parent being deleted and therefore succeeding deleting the childs.
[Test case]
1) Deploy Cinder with Ceph
2) Create a parent volume
openstack volume create --size 1 v1
3) Create the child volumes
for i in {1..9}; do openstack volume create d$i --source v1 --size 1;done
4) Wait for all volumes to be created and available
5) Delete all the volumes
for item in $(openstack volume list --format value -c ID | sort | xargs); do openstack volume delete $item & done
6) Check for volumes stuck in error_deleting, if None, repeat steps 2-5
7) Confirm error message rbd.ImageNotFound in the logs
8) Install fixed package
9) Repeat steps 2-5, confirm no volumes stuck in error_deleting and the following messages in the log:
"no longer exists in backend"
"Retrying cinder.
If messages are not in the logs after the new delete command, then retry steps 2-5 until messages appear while still not having any volumes stuck in error_deleting (in other words, all volume deleted successfully).
[Regression Potential]
For Bobcat and Antelope, there is reasonable regression potential because of the complexity of refactor [1] (see comment #2), however, discussions on previous upstream meetings and upstream CI runs of Caracal, Bobcat and Antelope backports which test the refactor provide some level of reassurance. For Yoga, we consider no regression potential with the simpler retry decorator fix.
[Other Info]
None.
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #1 |
| Dan Hill (hillpd) wrote | #2 |
| no longer affects: | ubuntu |
| summary: |
- error deleting cloned volumes and parent at the same time when using - ceph + [SRU] error deleting cloned volumes and parent at the same time when + using ceph |
| description: | updated |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #3 |
| OpenStack Infra (hudson-openstack) wrote Fix proposed to cinder (unmaintained/yoga) | #4 |
| description: | updated |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #5 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #6 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #7 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #8 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #9 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #10 |
| James Page (james-page) wrote | #11 |
| Andreas Hasenack (ahasenack) wrote | #12 |
| Changed in cinder (Ubuntu): | |
| status: | New → Invalid |
| Changed in cloud-archive: | |
| status: | New → Invalid |
| Changed in cinder: | |
| status: | New → Invalid |
| Heitor Alves de Siqueira (halves) wrote | #13 |
| Changed in cinder (Ubuntu): | |
| status: | Invalid → Fix Released |
| Changed in cinder: | |
| status: | Invalid → Fix Released |
| Changed in cinder (Ubuntu Jammy): | |
| status: | New → In Progress |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #14 |
| Andreas Hasenack (ahasenack) wrote Please test proposed package | #15 |
| Changed in cinder (Ubuntu Jammy): | |
| status: | In Progress → Fix Committed |
| tags: | added: verification-needed verification-needed-jammy |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #16 |
| tags: |
added: verification-done-jammy removed: verification-needed-jammy |
| Launchpad Janitor (janitor) wrote | #18 |
| Changed in cinder (Ubuntu Jammy): | |
| status: | Fix Committed → Fix Released |
| Timo Aaltonen (tjaalton) wrote Update Released | #17 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #19 |
| Guillaume Boutry (gboutry) wrote Please test proposed package | #20 |
| tags: | added: verification-bobcat-needed |
| Guillaume Boutry (gboutry) wrote | #21 |
| tags: | added: verification-antelope-needed |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #22 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #23 |
| tags: |
added: verification-antelope-done verification-bobcat-done removed: verification-antelope-needed verification-bobcat-needed |
| Edward Hope-Morley (hopem) wrote | #24 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #25 |
| Edward Hope-Morley (hopem) wrote | #26 |
| tags: | added: verification-yoga-needed |
| Edward Hope-Morley (hopem) wrote Update Released | #27 |
| Edward Hope-Morley (hopem) wrote | #28 |
| Edward Hope-Morley (hopem) wrote | #29 |
| Edward Hope-Morley (hopem) wrote | #30 |
| Rodrigo Barbieri (rodrigo-barbieri2010) wrote | #31 |
| tags: |
added: verification-yoga-done removed: verification-yoga-needed |
| Edward Hope-Morley (hopem) wrote | #32 |
| Edward Hope-Morley (hopem) wrote | #33 |
to backport [1] cleanly to yoga it is necessary to apply the following commits [2], [3] and [4], but [3] and [4] are not necessary because the methods are completely removed in [1]. Therefore only [2] is needed to avoid unit test conflicts.
[1] https:/
[2] https:/
[3] https:/
[4] https:/