3 files changed, 61 insertions, 9 deletions
diff --git a/libdiskfs/diskfs.h b/libdiskfs/diskfs.h
index ae1a1502..2c68aa34 100644
--- a/libdiskfs/diskfs.h
+++ b/libdiskfs/diskfs.h
@@ -686,6 +686,33 @@ diskfs_notice_filechange (struct node *np, enum file_changed_type type,
    The new node will have one hard reference and no light references.  */
 struct node *diskfs_make_node (struct disknode *dn);
 
+/* Create a new node structure.  Also allocate SIZE bytes for the
+   disknode.  The address of the disknode can be obtained using
+   diskfs_node_disknode.  The new node will have one hard reference
+   and no light references.  */
+struct node *diskfs_make_node_alloc (size_t size);
+
+/* To avoid breaking the ABI whenever sizeof (struct node) changes, we
+   explicitly provide the size.  The following two functions will use
+   this value for offset calculations.  */
+extern const size_t _diskfs_sizeof_struct_node;
+
+/* Return the address of the disknode for NODE.  NODE must have been
+   allocated using diskfs_make_node_alloc.  */
+static inline struct disknode *
+diskfs_node_disknode (struct node *node)
+{
+  return (struct disknode *) ((char *) node + _diskfs_sizeof_struct_node);
+}
+
+/* Return the address of the node for DISKNODE.  DISKNODE must have
+   been allocated using diskfs_make_node_alloc.  */
+static inline struct node *
+diskfs_disknode_node (struct disknode *disknode)
+{
+  return (struct node *) ((char *) disknode - _diskfs_sizeof_struct_node);
+}
+
 
 /* The library also exports the following functions; they are not generally
    useful unless you are redefining other functions the library provides. */
diff --git a/libdiskfs/init-init.c b/libdiskfs/init-init.c
index 35be7edd..7a7f2485 100644
--- a/libdiskfs/init-init.c
+++ b/libdiskfs/init-init.c
@@ -25,6 +25,10 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #include <stdio.h>
 #include <maptime.h>
 
+/* For safe inlining of diskfs_node_disknode and
+   diskfs_disknode_node.  */
+size_t const _diskfs_sizeof_struct_node = sizeof (struct node);
+
 mach_port_t diskfs_default_pager;
 mach_port_t diskfs_auth_server_port;
 volatile struct mapped_time_value *diskfs_mtime;
diff --git a/libdiskfs/node-make.c b/libdiskfs/node-make.c
index 2b6ef2af..ff0cc0d4 100644
--- a/libdiskfs/node-make.c
+++ b/libdiskfs/node-make.c
@@ -19,16 +19,9 @@
 #include <fcntl.h>
 
 
-/* Create a and return new node structure with DN as its physical disknode.
-   The node will have one hard reference and no light references.  */
-struct node *
-diskfs_make_node (struct disknode *dn)
+static struct node *
+init_node (struct node *np, struct disknode *dn)
 {
-  struct node *np = malloc (sizeof (struct node));
-
-  if (np == 0)
-    return 0;
-
   np->dn = dn;
   np->dn_set_ctime = 0;
   np->dn_set_atime = 0;
@@ -52,3 +45,31 @@ diskfs_make_node (struct disknode *dn)
 
   return np;
 }
+
+/* Create a and return new node structure with DN as its physical disknode.
+   The node will have one hard reference and no light references.  */
+struct node *
+diskfs_make_node (struct disknode *dn)
+{
+  struct node *np = malloc (sizeof (struct node));
+
+  if (np == 0)
+    return 0;
+
+  return init_node (np, dn);
+}
+
+/* Create a new node structure.  Also allocate SIZE bytes for the
+   disknode.  The address of the disknode can be obtained using
+   diskfs_node_disknode.  The new node will have one hard reference
+   and no light references.  */
+struct node *
+diskfs_make_node_alloc (size_t size)
+{
+  struct node *np = malloc (sizeof (struct node) + size);
+
+  if (np == NULL)
+    return NULL;
+
+  return init_node (np, diskfs_node_disknode (np));
+}