o Migrate vm_map_split() from vm_map.c to vm_object.c, renaming it

   to vm_object_split().  Its interface should still be changed
   to resemble vm_object_shadow().

1 files changed, 91 insertions, 0 deletions

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 2760eba..d046941 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1180,6 +1180,97 @@ vm_object_shadow(
 	mtx_unlock(&Giant);
 }
 
+/*
+ *	vm_object_split:
+ *
+ * Split the pages in a map entry into a new object.  This affords
+ * easier removal of unused pages, and keeps object inheritance from
+ * being a negative impact on memory usage.
+ */
+void
+vm_object_split(vm_map_entry_t entry)
+{
+	vm_page_t m;
+	vm_object_t orig_object, new_object, source;
+	vm_offset_t s, e;
+	vm_pindex_t offidxstart, offidxend, idx;
+	vm_size_t size;
+	vm_ooffset_t offset;
+
+	GIANT_REQUIRED;
+
+	orig_object = entry->object.vm_object;
+	if (orig_object->type != OBJT_DEFAULT && orig_object->type != OBJT_SWAP)
+		return;
+	if (orig_object->ref_count <= 1)
+		return;
+
+	offset = entry->offset;
+	s = entry->start;
+	e = entry->end;
+
+	offidxstart = OFF_TO_IDX(offset);
+	offidxend = offidxstart + OFF_TO_IDX(e - s);
+	size = offidxend - offidxstart;
+
+	new_object = vm_pager_allocate(orig_object->type,
+		NULL, IDX_TO_OFF(size), VM_PROT_ALL, 0LL);
+	if (new_object == NULL)
+		return;
+
+	source = orig_object->backing_object;
+	if (source != NULL) {
+		vm_object_reference(source);	/* Referenced by new_object */
+		TAILQ_INSERT_TAIL(&source->shadow_head,
+				  new_object, shadow_list);
+		vm_object_clear_flag(source, OBJ_ONEMAPPING);
+		new_object->backing_object_offset = 
+			orig_object->backing_object_offset + IDX_TO_OFF(offidxstart);
+		new_object->backing_object = source;
+		source->shadow_count++;
+		source->generation++;
+	}
+	for (idx = 0; idx < size; idx++) {
+	retry:
+		m = vm_page_lookup(orig_object, offidxstart + idx);
+		if (m == NULL)
+			continue;
+
+		/*
+		 * 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_rename(m, new_object, idx);
+		/* page automatically made dirty by rename and cache handled */
+		vm_page_busy(m);
+	}
+	if (orig_object->type == OBJT_SWAP) {
+		vm_object_pip_add(orig_object, 1);
+		/*
+		 * copy orig_object pages into new_object
+		 * and destroy unneeded pages in
+		 * shadow object.
+		 */
+		swap_pager_copy(orig_object, new_object, offidxstart, 0);
+		vm_object_pip_wakeup(orig_object);
+	}
+	for (idx = 0; idx < size; idx++) {
+		m = vm_page_lookup(new_object, idx);
+		if (m != NULL)
+			vm_page_wakeup(m);
+	}
+	entry->object.vm_object = new_object;
+	entry->offset = 0LL;
+	vm_object_deallocate(orig_object);
+}
+
 #define	OBSC_TEST_ALL_SHADOWED	0x0001
 #define	OBSC_COLLAPSE_NOWAIT	0x0002
 #define	OBSC_COLLAPSE_WAIT	0x0004