fix(nexus-child/unplug): remove usage of block_on

Initially this block_on was added because the remove callback was running in blocking
fashion, but this has since changed and unplug is actually called from async context.
As such, we don't need the block_on and simply call the async code directly.
Also, simplify complete notification, as we can simply close the sender.

Signed-off-by: Tiago Castro <[email protected]>

io-engine/src/bdev/nexus/nexus_bdev_children.rs

@@ -900,7 +900,7 @@ impl<'n> Nexus<'n> {
                         nexus_name,
                         child_device, "Unplugging nexus child device",
                     );
-                    child.unplug();
+                    child.unplug().await;
                 }
                 None => {
                     warn!(

io-engine/src/bdev/nexus/nexus_child.rs

@@ -24,8 +24,6 @@ use crate::{
         BlockDeviceHandle,
         CoreError,
         DeviceEventSink,
-        Reactor,
-        Reactors,
         VerboseError,
     },
     eventing::replica_events::state_change_event_meta,
@@ -1109,7 +1107,7 @@ impl<'c> NexusChild<'c> {
     /// underlying device is removed.
     ///
     /// Note: The descriptor *must* be dropped for the unplug to complete.
-    pub(crate) fn unplug(&mut self) {
+    pub(crate) async fn unplug(&mut self) {
         info!("{self:?}: unplugging child...");
 
         let state = self.state();
@@ -1139,12 +1137,10 @@ impl<'c> NexusChild<'c> {
         // device-related events directly.
         if state != ChildState::Faulted(FaultReason::IoError) {
             let nexus_name = self.parent.clone();
-            Reactor::block_on(async move {
-                match nexus_lookup_mut(&nexus_name) {
-                    Some(n) => n.reconfigure(DrEvent::ChildUnplug).await,
-                    None => error!("Nexus '{nexus_name}' not found"),
-                }
-            });
+            match nexus_lookup_mut(&nexus_name) {
+                Some(n) => n.reconfigure(DrEvent::ChildUnplug).await,
+                None => error!("Nexus '{nexus_name}' not found"),
+            }
         }
 
         if is_destroying {
@@ -1153,22 +1149,16 @@ impl<'c> NexusChild<'c> {
             self.device_descriptor.take();
         }
 
-        self.unplug_complete();
-        info!("{self:?}: child successfully unplugged");
+        self.unplug_complete().await;
     }
 
     /// Signal that the child unplug is complete.
-    fn unplug_complete(&self) {
-        let sender = self.remove_channel.0.clone();
-        let name = self.name.clone();
-        Reactors::current().send_future(async move {
-            if let Err(e) = sender.send(()).await {
-                error!(
-                    "Failed to send unplug complete for child '{}': {}",
-                    name, e
-                );
-            }
-        });
+    async fn unplug_complete(&self) {
+        if let Err(error) = self.remove_channel.0.send(()).await {
+            info!("{self:?}: failed to send unplug complete: {error}");
+        } else {
+            info!("{self:?}: child successfully unplugged");
+        }
     }
 
     /// create a new nexus child