[pbs-devel] [PATCH proxmox-backup] datastore: simplify update-datastore-cache socket command

[Hannes Laimer]

... by always dropping the cache entry and not allowing it to be
re-added based on the maintenance mode. The check is only needed for
`Lookup` operations since lookups with those wouldn't fail based on
maintenance mode alone. Already running tasks won't be affected and
since they're the only ones holding a reference to a DataStore, it,
and the file handles it holds will be dropped automatically once the
(last) task finishes.

Signed-off-by: Hannes Laimer <h.laimer at proxmox.com>
---
 pbs-datastore/src/datastore.rs  | 26 ++++++++++----------------
 src/api2/config/datastore.rs    |  7 +++----
 src/bin/proxmox-backup-proxy.rs |  6 +++---
 3 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index f95da761..e1028778 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -190,10 +190,15 @@ impl DataStore {
             )?)
         };
 
+        let is_offline = config
+            .get_maintenance_mode()
+            .map_or(false, |m| m.is_offline());
         let datastore = DataStore::with_store_and_config(chunk_store, config, Some(digest))?;
 
         let datastore = Arc::new(datastore);
-        datastore_cache.insert(name.to_string(), datastore.clone());
+        if !is_offline {
+            datastore_cache.insert(name.to_string(), datastore.clone());
+        }
 
         Ok(Arc::new(Self {
             inner: datastore,
@@ -211,21 +216,10 @@ impl DataStore {
         Ok(())
     }
 
-    /// trigger clearing cache entry based on maintenance mode. Entry will only
-    /// be cleared iff there is no other task running, if there is, the end of the
-    /// last running task will trigger the clearing of the cache entry.
-    pub fn update_datastore_cache(name: &str) -> Result<(), Error> {
-        let (config, _digest) = pbs_config::datastore::config()?;
-        let datastore: DataStoreConfig = config.lookup("datastore", name)?;
-        if datastore
-            .get_maintenance_mode()
-            .map_or(false, |m| m.is_offline())
-        {
-            // the datastore drop handler does the checking if tasks are running and clears the
-            // cache entry, so we just have to trigger it here
-            let _ = DataStore::lookup_datastore(name, Some(Operation::Lookup));
-        }
-
+    /// removes datastore from cache
+    pub fn drop_from_datastore_cache(name: &str) -> Result<(), Error> {
+        let mut datastore_cache = DATASTORE_MAP.lock().unwrap();
+        datastore_cache.remove(name);
         Ok(())
     }
 
diff --git a/src/api2/config/datastore.rs b/src/api2/config/datastore.rs
index 02887b86..5cc3dfb6 100644
--- a/src/api2/config/datastore.rs
+++ b/src/api2/config/datastore.rs
@@ -398,16 +398,15 @@ pub fn update_datastore(
         data.tuning = update.tuning;
     }
 
-    let mut maintenance_mode_changed = false;
+    let mut drop_store_from_cache = false;
     if update.maintenance_mode.is_some() {
-        maintenance_mode_changed = data.maintenance_mode != update.maintenance_mode;
-
         let maintenance_mode = match update.maintenance_mode {
             Some(mode_str) => Some(MaintenanceMode::deserialize(
                 proxmox_schema::de::SchemaDeserializer::new(mode_str, &MaintenanceMode::API_SCHEMA),
             )?),
             None => None,
         };
+        drop_store_from_cache = maintenance_mode.as_ref().map_or(false, |m| m.is_offline());
         data.set_maintenance_mode(maintenance_mode)?;
     }
 
@@ -422,7 +421,7 @@ pub fn update_datastore(
     }
 
     // tell the proxy it might have to clear a cache entry
-    if maintenance_mode_changed {
+    if drop_store_from_cache {
         tokio::spawn(async move {
             if let Ok(proxy_pid) =
                 proxmox_rest_server::read_pid(pbs_buildcfg::PROXMOX_BACKUP_PROXY_PID_FN)
diff --git a/src/bin/proxmox-backup-proxy.rs b/src/bin/proxmox-backup-proxy.rs
index 15444685..4c48defc 100644
--- a/src/bin/proxmox-backup-proxy.rs
+++ b/src/bin/proxmox-backup-proxy.rs
@@ -290,11 +290,11 @@ async fn run() -> Result<(), Error> {
         Ok(Value::Null)
     })?;
 
-    // clear cache entry for datastore that is in a specific maintenance mode
+    // clear cache entry for datastore
     command_sock.register_command("update-datastore-cache".to_string(), |value| {
         if let Some(name) = value.and_then(Value::as_str) {
-            if let Err(err) = DataStore::update_datastore_cache(name) {
-                log::error!("could not trigger update datastore cache: {err}");
+            if let Err(err) = DataStore::drop_from_datastore_cache(name) {
+                log::error!("could not drop datastore from cache: {err}");
             }
         }
         Ok(Value::Null)
-- 
2.39.2