proxmox-backup-proxy: fix leftover references on datastore removal

when we remove a datastore via api/cli, the proxy
has sometimes leftover references to that datastore in its
DATASTORE_MAP which includes an open filehandle on the
'.lock' file

this prevents unmounting/exporting the datastore even after removal,
only a reload/restart of the proxy did help

add a command to our command socket, which removes all non
configured datastores from the map, dropping the open filehandle

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

src/api2/config/datastore.rs

@@ -403,7 +403,7 @@ pub fn update_datastore(
     },
 )]
 /// Remove a datastore configuration.
-pub fn delete_datastore(name: String, digest: Option<String>) -> Result<(), Error> {
+pub async fn delete_datastore(name: String, digest: Option<String>) -> Result<(), Error> {
 
     let _lock = open_file_locked(datastore::DATASTORE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
 
@@ -425,6 +425,8 @@ pub fn delete_datastore(name: String, digest: Option<String>) -> Result<(), Erro
     let _ = jobstate::remove_state_file("prune", &name);
     let _ = jobstate::remove_state_file("garbage_collection", &name);
 
+    crate::server::notify_datastore_removed().await?;
+
     Ok(())
 }