Move a call to wakeup() from vm_object_terminate() to vnode_pager_dealloc()

because this call is only needed to wake threads that slept when they
discovered a dead object connected to a vnode.  To eliminate unnecessary
calls to wakeup() by vnode_pager_dealloc(), introduce a new flag,
OBJ_DISCONNECTWNT.

Reviewed by: tegge@

3 files changed, 6 insertions, 2 deletions

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 3a28325..4df862b 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -642,8 +642,6 @@ vm_object_terminate(vm_object_t object)
 	TAILQ_REMOVE(&vm_object_list, object, object_list);
 	mtx_unlock(&vm_object_list_mtx);
 
-	wakeup(object);
-
 	/*
 	 * Free the space for the object.
 	 */
diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
index 64e4d76..1f1acb6 100644
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -148,6 +148,7 @@ struct vm_object {
 #define OBJ_MIGHTBEDIRTY 0x0100		/* object might be dirty */
 #define OBJ_CLEANING	0x0200
 #define	OBJ_ONEMAPPING	0x2000		/* One USE (a single, non-forked) mapping flag */
+#define	OBJ_DISCONNECTWNT 0x4000	/* disconnect from vnode wanted */
 
 #define IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
 #define OFF_TO_IDX(off) ((vm_pindex_t)(((vm_ooffset_t)(off)) >> PAGE_SHIFT))
diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index b09559b..c9634e0 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -143,6 +143,7 @@ vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 		VM_OBJECT_LOCK(object);
 		if ((object->flags & OBJ_DEAD) == 0)
 			break;
+		vm_object_set_flag(object, OBJ_DISCONNECTWNT);
 		msleep(object, VM_OBJECT_MTX(object), PDROP | PVM, "vadead", 0);
 	}
 
@@ -191,6 +192,10 @@ vnode_pager_dealloc(object)
 
 	object->handle = NULL;
 	object->type = OBJT_DEAD;
+	if (object->flags & OBJ_DISCONNECTWNT) {
+		vm_object_clear_flag(object, OBJ_DISCONNECTWNT);
+		wakeup(object);
+	}
 	ASSERT_VOP_LOCKED(vp, "vnode_pager_dealloc");
 	vp->v_object = NULL;
 	vp->v_vflag &= ~(VV_TEXT | VV_OBJBUF);