Remove unnecessary page protects on map_split and collapse operations.

    Fix bug where an object's OBJ_WRITEABLE/OBJ_MIGHTBEDIRTY flags do
    not get set under certain circumstances ( page rename case ).

Reviewed by:	Alan Cox <alc@cs.rice.edu>, John Dyson

3 files changed, 16 insertions, 6 deletions

diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index cbb59cf..05c8c5c 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_map.c,v 1.150 1999/02/19 03:11:37 dillon Exp $
+ * $Id: vm_map.c,v 1.151 1999/02/19 14:25:36 luoqi Exp $
  */
 
 /*
@@ -2162,12 +2162,14 @@ vm_map_split(entry)
 		/*
 		 * We must wait for pending I/O to complete before we can
 		 * rename the page.
+		 *
+		 * We do not have to VM_PROT_NONE the page as mappings should
+		 * not be changed by this operation.
 		 */
 		if (vm_page_sleep_busy(m, TRUE, "spltwt"))
 			goto retry;
 			
 		vm_page_busy(m);
-		vm_page_protect(m, VM_PROT_NONE);
 		vm_page_rename(m, new_object, idx);
 		/* page automatically made dirty by rename and cache handled */
 		vm_page_busy(m);
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 686cf35..ea3b49c 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_object.c,v 1.150 1999/02/12 20:42:19 dillon Exp $
+ * $Id: vm_object.c,v 1.151 1999/02/15 02:03:40 dillon Exp $
  */
 
 /*
@@ -1086,11 +1086,12 @@ vm_object_backing_scan(vm_object_t object, int op)
 			/*
 			 * Page does not exist in parent, rename the
 			 * page from the backing object to the main object. 
+			 *
+			 * If the page was mapped to a process, it can remain 
+			 * mapped through the rename.
 			 */
 			if ((p->queue - p->pc) == PQ_CACHE)
 				vm_page_deactivate(p);
-			else
-				vm_page_protect(p, VM_PROT_NONE);
 
 			vm_page_rename(p, object, new_pindex);
 			/* page automatically made dirty by rename */
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 7cda5b4..a2e3a83 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vm_page.c	7.4 (Berkeley) 5/7/91
- *	$Id: vm_page.c,v 1.125 1999/02/08 00:37:35 dillon Exp $
+ *	$Id: vm_page.c,v 1.126 1999/02/15 06:52:14 dillon Exp $
  */
 
 /*
@@ -425,6 +425,13 @@ vm_page_insert(m, object, pindex)
 	 */
 
 	object->resident_page_count++;
+
+	/*
+	 * Since we are inserting a new and possibly dirty page,
+	 * update the object's OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY flags.
+	 */
+	if (m->flags & PG_WRITEABLE)
+	    vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
 }
 
 /*