commit 8b151497622342f6ac52a0fe9f00ddcf51e52af3
Author: Andriy Gapon <avg@icyb.net.ua>
Date:   Thu May 17 19:56:17 2012 +0300

    vm_pager_object_lookup: small optimization
    
    do not needlessly lock an object if its handle doesn't match

diff --git a/sys/vm/vm_pager.c b/sys/vm/vm_pager.c
index 8c652e2..6ed64ea 100644
--- a/sys/vm/vm_pager.c
+++ b/sys/vm/vm_pager.c
@@ -271,14 +271,15 @@ vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
 	vm_object_t object;
 
 	TAILQ_FOREACH(object, pg_list, pager_object_list) {
-		VM_OBJECT_LOCK(object);
-		if (object->handle == handle &&
-		    (object->flags & OBJ_DEAD) == 0) {
-			vm_object_reference_locked(object);
+		if (object->handle == handle) {
+			VM_OBJECT_LOCK(object);
+			if ((object->flags & OBJ_DEAD) == 0) {
+				vm_object_reference_locked(object);
+				VM_OBJECT_UNLOCK(object);
+				break;
+			}
 			VM_OBJECT_UNLOCK(object);
-			break;
 		}
-		VM_OBJECT_UNLOCK(object);
 	}
 	return (object);
 }