lxd/instance: Lock image access (from Incus) (#14546)

Cherry-picked from lxc/incus#1408 and tested
with script from #12581

Closes #12581

Author: tomponline

lxd/instance.go

@@ -179,6 +179,15 @@ func instanceCreateFromImage(s *state.State, img *api.Image, args db.InstanceArg
 		return fmt.Errorf("Failed loading instance storage pool: %w", err)
 	}
 
+	// Lock this operation to ensure that concurrent image operations don't conflict.
+	// Other operations will wait for this one to finish.
+	unlock, err := imageOperationLock(img.Fingerprint)
+	if err != nil {
+		return err
+	}
+
+	defer unlock()
+
 	err = pool.CreateInstanceFromImage(inst, img.Fingerprint, op)
 	if err != nil {
 		return fmt.Errorf("Failed creating instance from image: %w", err)