--- linux-2.6-tmp/mm/msync.c.=K0000=.orig
+++ linux-2.6-tmp/mm/msync.c
@@ -127,13 +127,10 @@ static int filemap_sync(struct vm_area_s
 /*
  * MS_SYNC syncs the entire file - including mappings.
  *
- * MS_ASYNC does not start I/O (it used to, up to 2.5.67).  Instead, it just
- * marks the relevant pages dirty.  The application may now run fsync() to
- * write out the dirty pages and wait on the writeout and check the result.
- * Or the application may run fadvise(FADV_DONTNEED) against the fd to start
- * async writeout immediately.
- * So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to
- * applications.
+ * MS_ASYNC once again starts I/O (it did not between 2.5.68 and 2.6.4.)
+ * SingleUnix requires it.  If an application wants to queue dirty pages
+ * for normal asychronous writeback, msync with flags==0 should achieve
+ * that on all kernels at least as far back as 2.4.
  */
 static int msync_interval(struct vm_area_struct * vma,
 	unsigned long start, unsigned long end, int flags)
@@ -147,20 +144,22 @@ static int msync_interval(struct vm_area
 	if (file && (vma->vm_flags & VM_SHARED)) {
 		ret = filemap_sync(vma, start, end-start, flags);
 
-		if (!ret && (flags & MS_SYNC)) {
+		if (!ret && (flags & (MS_SYNC|MS_ASYNC))) {
 			struct address_space *mapping = file->f_mapping;
 			int err;
 
 			down(&mapping->host->i_sem);
 			ret = filemap_fdatawrite(mapping);
-			if (file->f_op && file->f_op->fsync) {
-				err = file->f_op->fsync(file,file->f_dentry,1);
-				if (err && !ret)
+			if (flags & MS_SYNC) {
+				if (file->f_op && file->f_op->fsync) {
+					err = file->f_op->fsync(file, file->f_dentry, 1);
+					if (err && !ret)
+						ret = err;
+				}
+				err = filemap_fdatawait(mapping);
+				if (!ret)
 					ret = err;
 			}
-			err = filemap_fdatawait(mapping);
-			if (!ret)
-				ret = err;
 			up(&mapping->host->i_sem);
 		}
 	}