Subject: [PATCH] nethost sysfs: Refactor the sysfs support so it actually works.
From: Eric W. Biederman <ebiederman@lnxi.com>
Date: 1137525766 -0700

The current code introduces helpers that need to move out of
net-sysfs but the code works, and it works for all of the
right reasons.

---

 net/core/net-sysfs.c |   88 +++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 76 insertions(+), 12 deletions(-)

ccde72a811cba810a5434df676eb8a6513b9d85a
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index aaf0f48..b596d1c 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -18,6 +18,10 @@
 #include <linux/wireless.h>
 #include <linux/pspace.h>
 #include <linux/nethost.h>
+#if 1 
+#include <linux/namei.h>
+#include "../../fs/sysfs/sysfs.h"
+#endif
 
 #define to_class_dev(obj) container_of(obj,struct class_device,kobj)
 #define to_net_dev(class) container_of(class, struct net_device, class_dev)
@@ -503,22 +507,82 @@ out:
 	return ret;
 }
 
-void netdev_move_sysfs(struct net_device *net)
+static int sysfs_reparent(struct kobject *kobj)
 {
-	struct class_device *class_dev = &(net->class_dev);
-	struct class *parent;
-	struct kobject *kobj_parent;
+	struct dentry *old_dentry = dget(kobj->dentry);
+	struct dentry *old_dir = dget(old_dentry->d_parent);
+	struct dentry *new_dir = dget(kobj->parent->dentry);
+	struct dentry *new_dentry;
+	struct dentry *trap;
+	struct sysfs_dirent *sd, *parent_sd;
+	int error;
+
+	trap = lock_rename(new_dir, old_dir);
+
+	/* source shold not be ancestor of target */
+	error = -EINVAL;
+	if (old_dentry == trap)
+		goto out;
+
+	new_dentry = lookup_one_len(old_dentry->d_name.name, new_dir, old_dentry->d_name.len);
+	error = PTR_ERR(new_dentry);
+	if (IS_ERR(new_dentry))
+		goto out;
 
-	parent = class_dev->class;
-	kobj_parent = class_dev->kobj.parent;
+	/* Target should not exist */
+	error = -ENOTEMPTY;
+	if (new_dentry->d_inode)
+		goto out2;
+
+	/* Move the directory entry */
+	parent_sd = new_dir->d_fsdata;
+	sd = old_dentry->d_fsdata;
+	list_del_init(&sd->s_sibling);
+	list_add(&sd->s_sibling, &parent_sd->s_children);
+
+	/* Move the dcache entry */
+	d_move(old_dentry, new_dentry);
+out2:
+	dput(new_dentry);
+out:
+	unlock_rename(new_dir, old_dir);
+	dput(old_dentry);
+	dput(old_dir);
+	dput(new_dir);
+	return error;
+}
+
+static void kobject_reparent(struct kobject *kobj, struct kobject *new_parent)
+{
+	struct kobject *old_parent;
+
+	old_parent = kobj->parent;
 
-	class_dev->class = &net->host->net_class;
-	class_get(class_dev->class);
-	class_dev->kobj.parent = &class_dev->class->subsys.kset.kobj;
-	kobject_get(class_dev->kobj.parent);
+	kobj->parent = new_parent;
+	kobject_get(kobj->parent);
 
-	class_put(parent);
-	kobject_put(kobj_parent);
+	sysfs_reparent(kobj);
+	
+	kobject_put(old_parent);
+}
+
+static void class_device_reparent(struct class_device *class_dev, struct class *new_parent)
+{
+	struct class *old_parent;
+
+	old_parent = class_dev->class;
+	class_dev->class = new_parent;
+	class_get(new_parent);
+
+	kobject_reparent(&class_dev->kobj, &class_dev->class->subsys.kset.kobj);
+
+	class_put(old_parent);
+}
+
+void netdev_move_sysfs(struct net_device *net)
+{
+	struct class_device *class_dev = &(net->class_dev);
+	class_device_reparent(class_dev, &net->host->net_class);
 }
 
 int netdev_sysfs_init(struct nethost *host)
-- 
1.0.GIT