[PATCH proxmox-backup] api: backup: cleanup backup group created by benchmark

[Christian Ebner <c.ebner@proxmox.com>]

The benchmark creates it's own backup group host/benchmark, failed
however to auto-cleanup the group after itself, because since commit
23be00a42 ("fix #3336: datastore: remove group if the last snapshot
is removed"), cleanup requires an exclusive lock on the backup group
for destroying it. The backup environment however already holds the
exclusive lock to disallow concurrent backups to the same group.

To fix this, drop the locks held in the backup environment by
dropping the environment itself and rely on the cleanup to reacquire
them again.

Fixes: https://forum.proxmox.com/threads/183138/
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
---
 src/api2/backup/mod.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/api2/backup/mod.rs b/src/api2/backup/mod.rs
index 86ec49487..8848ca99c 100644
--- a/src/api2/backup/mod.rs
+++ b/src/api2/backup/mod.rs
@@ -288,9 +288,14 @@ fn upgrade_to_backup_protocol(
                 if benchmark {
                     env.log("benchmark finished successfully");
                     proxmox_async::runtime::block_in_place(|| {
-                        env.datastore.remove_backup_dir(
-                            env.backup_dir.backup_ns(),
-                            env.backup_dir.as_ref(),
+                        let datastore = env.datastore.clone();
+                        let namespace = env.backup_dir.backup_ns().clone();
+                        let snapshot = env.backup_dir.dir().clone();
+                        // draps all locks
+                        drop(env);
+                        datastore.remove_backup_dir(
+                            &namespace,
+                            &snapshot,
                             true,
                         )
                     })?;
-- 
2.47.3