server/prune_job: fix locking during prune jobs

removing the backup dir must acquire the snapshot lock, else it can
happen that we remove a snapshot while it is being restored
or backed up to tape

the original commit that adds the force flag
(c9756b40d1)
mentions that the prune checks itself if the snapshot is in use,
but i could not find such code, so simply set force to false

to avoid failing and aborting the prune job, warn if it could not
and continue

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/server/prune_job.rs

@@ -8,6 +8,7 @@ use crate::{
     server::jobstate::Job,
     server::WorkerTask,
     task_log,
+    task_warn,
 };
 
 pub fn do_prune_job(
@@ -67,7 +68,14 @@ pub fn do_prune_job(
                             info.backup_dir.backup_time_string()
                         );
                         if !keep {
-                            datastore.remove_backup_dir(&info.backup_dir, true)?;
+                            if let Err(err) = datastore.remove_backup_dir(&info.backup_dir, false) {
+                                task_warn!(
+                                    worker,
+                                    "failed to remove dir {:?}: {}",
+                                    info.backup_dir.relative_path(),
+                                    err,
+                                );
+                            }
                         }
                     }
                 }