Fixed a few bugs in vm_object_page_clean, mostly related to not syncing

pages that are in FS buffers. This fixes the (believed to already have been
fixed) problem with msync() not doing it's job...in other words, the
stuff that Andrew has continuously been complaining about.

Submitted by:	John Dyson, w/minor changes by me.

1 files changed, 21 insertions, 11 deletions

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index ba5c985..66acf44 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 1.40 1995/03/25 08:42:14 davidg Exp $
+ * $Id: vm_object.c,v 1.41 1995/04/09 06:03:49 davidg Exp $
  */
 
 /*
@@ -470,6 +470,7 @@ _vm_object_page_clean(object, start, end, syncio)
 	int pass;
 	int pgcount, s;
 	int allclean;
+	int entireobj;
 
 	if (object->pager == NULL || (object->flags & OBJ_WRITEABLE) == 0)
 		return;
@@ -479,8 +480,6 @@ _vm_object_page_clean(object, start, end, syncio)
 		end = round_page(end);
 	}
 
-	object->flags &= ~OBJ_WRITEABLE;
-
 	pass = 0;
 startover:
 	tstart = start;
@@ -489,6 +488,11 @@ startover:
 	} else {
 		tend = end;
 	}
+	entireobj = 0;
+	if (tstart == 0 && tend == object->size) {
+		object->flags &= ~OBJ_WRITEABLE;
+		entireobj = 1;
+	}
 	/*
 	 * Wait until potential collapse operation is complete
 	 */
@@ -504,7 +508,7 @@ startover:
 	pgcount = object->resident_page_count;
 
 	if (pass == 0 &&
-		(pgcount < 128 || pgcount > (object->size / (8 * PAGE_SIZE)))) {
+	    (pgcount < 128 || pgcount > (object->size / (8 * PAGE_SIZE)))) {
 		allclean = 1;
 		for(; pgcount && (tstart < tend); tstart += PAGE_SIZE) {
 			p = vm_page_lookup(object, tstart);
@@ -515,8 +519,10 @@ startover:
 			TAILQ_REMOVE(&object->memq, p, listq);
 			TAILQ_INSERT_TAIL(&object->memq, p, listq);
 			splx(s);
-			if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy || p->valid == 0 ||
-			    p->bmapped) {
+			if (entireobj)
+				vm_page_protect(p, VM_PROT_READ);
+			if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy ||
+				p->valid == 0) {
 				continue;
 			}
 			vm_page_test_dirty(p);
@@ -533,7 +539,6 @@ startover:
 			pass = 1;
 			goto startover;
 		}
-		object->flags &= ~OBJ_WRITEABLE;
 		return;
 	}
 
@@ -544,8 +549,11 @@ startover:
 			goto donext;
 		}
 
-		if (p->offset >= tstart && p->offset < tend) {
-			if (p->valid == 0 || p->bmapped) {
+		if (entireobj || (p->offset >= tstart && p->offset < tend)) {
+			if (entireobj)
+				vm_page_protect(p, VM_PROT_READ);
+
+			if (p->valid == 0) {
 				goto donext;
 			}
 
@@ -580,9 +588,11 @@ startover:
 		TAILQ_INSERT_TAIL(&object->memq, p, listq);
 		pgcount--;
 	}
-	if ((!allclean && (pass == 0)) || (object->flags & OBJ_WRITEABLE)) {
+	if ((!allclean && (pass == 0)) ||	
+	    (entireobj && (object->flags & OBJ_WRITEABLE))) {
 		pass = 1;
-		object->flags &= ~OBJ_WRITEABLE;
+		if (entireobj)
+			object->flags &= ~OBJ_WRITEABLE;
 		goto startover;
 	}
 	return;