[pve-devel] VM locked after failed Snapshot

[Alexandre DERUMIER]

Hi,

my 2cents, but could it be related to the vmstate bug ? 
https://git.proxmox.com/?p=pve-qemu-kvm.git;a=commit;h=62d638ff1e9fb96ca078be2225426aaac8f909f6


(Is a a vm snasphot with vmstate ?)


----- Mail original ----- 

De: "Stefan Priebe - Profihost AG" <s.priebe at profihost.ag> 
À: pve-devel at pve.proxmox.com 
Envoyé: Lundi 8 Septembre 2014 12:06:48 
Objet: [pve-devel] VM locked after failed Snapshot 

Hi, 

today i had the following problem. 

1.) i wanted to create a snapshot of a vm 
2.) it failed for unknown reason and i had the following output (PVE 
Webgui): 

image has watchers - not removing 
Removing image: 0% complete...failed. 
rbd: error: image still has watchers 
TASK ERROR: received interrupt 

3.) The VM was than in a locked state (VM is locked (snapshot)) 

I see multiple problems here. 

1.) lock state should be removed by PVE in case of a failure. 

Currently snapshot_create calls snapshot_prepare to set the lock. And at 
the end snapshot_commit deletes the log. 

But currently in case of $err 

if ($err) { 
warn "snapshot create failed: starting cleanup\n"; 
eval { snapshot_delete($vmid, $snapname, 0, $drivehash); }; 
warn $@ if $@; 
die $err; 
} 

The lock isn't removed. 

What is the correct way to remove a lock in this case? 

2.) in case of an unexpected failure or signal ceph/rbd does not remove 
it's watcher from the image. So the snapshot_delete failed in this case. 

Output: 

image has watchers - not removing 
Removing image: 0% complete...failed. 
rbd: error: image still has watchers 

rbd has an automatic timeout after 30s should PVE handle this by waiting 
30s and try it again? 

Greets, 
Stefan 
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