server: improve comments

Author: gjcolombo

bin/propolis-server/src/lib/vm/request_queue.rs

@@ -332,7 +332,7 @@ impl ExternalRequestQueue {
             // its state are ignored.
             //
             // Requests to change Crucible volume configuration can still be
-            // queued if they were previously alloewd. This allows the state
+            // queued if they were previously allowed. This allows the state
             // driver to accept VCR mutations that are needed to allow an
             // activation to complete even if the instance is slated to stop
             // immediately after starting.

bin/propolis-server/src/lib/vm/state_driver.rs

@@ -644,14 +644,18 @@ impl StateDriver {
                 biased;
 
                 res = &mut block_backend_fut => {
+                    // If the VM started up successfully, publish that it is
+                    // running and queue up any external requests that were
+                    // deferred while startup was ongoing.
+                    //
+                    // If startup failed, just return the error without changing
+                    // any state or processing any additional requests. The
+                    // caller will move the instance to the appropriate terminal
+                    // state and clean up the VM as needed.
                     if res.is_ok() {
                         let objects = &self.objects;
                         objects.lock_exclusive().await.resume_vcpus();
                         self.publish_steady_state(InstanceState::Running);
-
-                        // If a stop request was seen while in the startup
-                        // sequence, self-request a stop for the main event
-                        // loop to handle.
                         if stopped_while_starting {
                             self.input_queue.push_self_request(
                                 ExternalRequest::Stop