[pbs-devel] applied: [RFC proxmox-backup] drop exclusive lock for verify-after-complete

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

applied

On Mon, Feb 27, 2023 at 10:50:12AM +0100, Fabian Grünbichler wrote:
> the backup is finished at that point, the only lock clash that is possible when
> dropping the exclusive and attempting to obtain a shared lock would be
> 
> - the snapshot is pruned/removed
> - the backup is in a pre-upgrade process, and the post-upgrade process opens a reader
> 
> the first case is OK, if the other invocation wins the race and removes the
> snapshot verification is pointless anyway.
> 
> the second case means the snapshot is not verified directly after completion
> (this fact would be logged in the backup task log), but usable immediately for
> pulling/restoring/..
> 
> this should decrease the chances of triggering the issues described in #4523
> 
> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
> ---
> 
> Notes:
>     right now our locking helpers don't support a direct downgrade (or attempt to
>     upgrade, for that matter). given that we don't have many use cases that require

up/downgrading existing locks is a weird thing to do anyway and either
ruins the queues (or fails) anyway...