diff -aurpN -X /home/fletch/.diff.exclude 640-smp_boot_id/fs/sysfs/mount.c 651-sysfs_backing_store1/fs/sysfs/mount.c
--- 640-smp_boot_id/fs/sysfs/mount.c	Fri May 30 19:02:19 2003
+++ 651-sysfs_backing_store1/fs/sysfs/mount.c	Wed Feb 11 10:16:29 2004
@@ -20,6 +20,14 @@ struct super_block * sysfs_sb = NULL;
 static struct super_operations sysfs_ops = {
 	.statfs		= simple_statfs,
 	.drop_inode	= generic_delete_inode,
+	.umount_begin 	= sysfs_umount_begin,
+};
+
+struct sysfs_dirent sysfs_root = {
+	.s_sibling	= LIST_HEAD_INIT(sysfs_root.s_sibling),
+	.s_children	= LIST_HEAD_INIT(sysfs_root.s_children),
+	.s_element	= NULL,
+	.s_type		= SYSFS_ROOT,
 };
 
 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
@@ -35,8 +43,8 @@ static int sysfs_fill_super(struct super
 
 	inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO);
 	if (inode) {
-		inode->i_op = &simple_dir_inode_operations;
-		inode->i_fop = &simple_dir_operations;
+		inode->i_op = &sysfs_dir_inode_operations;
+		inode->i_fop = &sysfs_dir_operations;
 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
 		inode->i_nlink++;	
 	} else {
@@ -50,6 +58,7 @@ static int sysfs_fill_super(struct super
 		iput(inode);
 		return -ENOMEM;
 	}
+	root->d_fsdata = &sysfs_root;
 	sb->s_root = root;
 	return 0;
 }
@@ -58,6 +67,21 @@ static struct super_block *sysfs_get_sb(
 	int flags, const char *dev_name, void *data)
 {
 	return get_sb_single(fs_type, flags, data, sysfs_fill_super);
+}
+
+/* For freeing zero refenced dentries / inodes while force unmounting 
+ *
+ * Because still sysfs has dentries corresponding to the directories pinned 
+ * in memory which keeps the super block always active and ->kill_sb is never 
+ * called while unmounting, in order to free the memory used by un-used 
+ * dentries and inodes sysfs has to be "force" umounted.
+ */
+void sysfs_umount_begin(struct super_block * sb) 
+{
+	lock_super(sb);
+	if (sb->s_root) 
+		shrink_dcache_parent(sb->s_root);
+	unlock_super(sb);
 }
 
 static struct file_system_type sysfs_fs_type = {
diff -aurpN -X /home/fletch/.diff.exclude 640-smp_boot_id/include/linux/sysfs.h 651-sysfs_backing_store1/include/linux/sysfs.h
--- 640-smp_boot_id/include/linux/sysfs.h	Tue Sep  2 09:55:56 2003
+++ 651-sysfs_backing_store1/include/linux/sysfs.h	Wed Feb 11 10:16:29 2004
@@ -9,6 +9,8 @@
 #ifndef _SYSFS_H_
 #define _SYSFS_H_
 
+#include <asm/atomic.h>
+
 struct kobject;
 struct module;
 
@@ -41,6 +43,23 @@ sysfs_remove_dir(struct kobject *);
 
 extern void
 sysfs_rename_dir(struct kobject *, const char *new_name);
+
+struct sysfs_dirent {
+	atomic_t		s_count;
+	struct list_head	s_sibling;
+	struct list_head	s_children;
+	void 			* s_element;
+	int			s_type;
+	struct dentry		* s_dentry;
+};
+
+#define SYSFS_ROOT		0x0001
+#define SYSFS_KOBJECT		0x0002
+#define SYSFS_KOBJ_ATTR 	0x0004
+#define SYSFS_KOBJ_BIN_ATTR	0x0008
+#define SYSFS_KOBJ_ATTR_GROUP	0x0010
+#define SYSFS_KOBJ_LINK 	0x0020
+#define SYSFS_NOT_PINNED	(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
 
 extern int
 sysfs_create_file(struct kobject *, const struct attribute *);