While shadow directories appear to be a good idea, the current scheme
of controlling their creation and destruction outside of sysfs appears
to be a locking and maintenance nightmare in the face of sysfs directories
dynamically coming and going.  Which can now occur for directories containing
network devices when CONFIG_SYSFS_DEPRECATED is not set.

This patch removes everything from the initial shadow directory support
that allowed the shadow directory creation to be controlled at a higher
level.  So except for a few bits of sysfs_rename_dir everything from
commit b592fcfe7f06c15ec11774b5be7ce0de3aa86e73 is now gone.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/sysfs/dir.c          |  196 +++++++++--------------------------------------
 fs/sysfs/group.c        |    1 -
 fs/sysfs/inode.c        |   10 ---
 fs/sysfs/mount.c        |    2 +-
 fs/sysfs/sysfs.h        |    5 -
 include/linux/kobject.h |    4 -
 include/linux/sysfs.h   |   24 +-----
 lib/kobject.c           |   43 +---------
 8 files changed, 45 insertions(+), 240 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 85a6686..d6ab015 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -33,7 +33,8 @@ static struct dentry_operations sysfs_dentry_ops = {
 /*
  * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
  */
-static struct sysfs_dirent * __sysfs_new_dirent(void * element)
+static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * parent_sd,
+						void * element)
 {
 	struct sysfs_dirent * sd;
 
@@ -44,28 +45,12 @@ static struct sysfs_dirent * __sysfs_new_dirent(void * element)
 	atomic_set(&sd->s_count, 1);
 	atomic_set(&sd->s_event, 1);
 	INIT_LIST_HEAD(&sd->s_children);
-	INIT_LIST_HEAD(&sd->s_sibling);
+	list_add(&sd->s_sibling, &parent_sd->s_children);
 	sd->s_element = element;
 
 	return sd;
 }
 
-static void __sysfs_list_dirent(struct sysfs_dirent *parent_sd,
-			      struct sysfs_dirent *sd)
-{
-	if (sd)
-		list_add(&sd->s_sibling, &parent_sd->s_children);
-}
-
-static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent *parent_sd,
-						void * element)
-{
-	struct sysfs_dirent *sd;
-	sd = __sysfs_new_dirent(element);
-	__sysfs_list_dirent(parent_sd, sd);
-	return sd;
-}
-
 /*
  *
  * Return -EEXIST if there is already a sysfs element with the same name for
@@ -92,14 +77,14 @@ int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
 }
 
 
-static struct sysfs_dirent *
-__sysfs_make_dirent(struct dentry *dentry, void *element, mode_t mode, int type)
+int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
+			void * element, umode_t mode, int type)
 {
 	struct sysfs_dirent * sd;
 
-	sd = __sysfs_new_dirent(element);
+	sd = sysfs_new_dirent(parent_sd, element);
 	if (!sd)
-		goto out;
+		return -ENOMEM;
 
 	sd->s_mode = mode;
 	sd->s_type = type;
@@ -109,19 +94,7 @@ __sysfs_make_dirent(struct dentry *dentry, void *element, mode_t mode, int type)
 		dentry->d_op = &sysfs_dentry_ops;
 	}
 
-out:
-	return sd;
-}
-
-int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
-			void * element, umode_t mode, int type)
-{
-	struct sysfs_dirent *sd;
-
-	sd = __sysfs_make_dirent(dentry, element, mode, type);
-	__sysfs_list_dirent(parent_sd, sd);
-
-	return sd ? 0 : -ENOMEM;
+	return 0;
 }
 
 static int init_dir(struct inode * inode)
@@ -193,10 +166,9 @@ int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
 /**
  *	sysfs_create_dir - create a directory for an object.
  *	@kobj:		object we're creating directory for. 
- *	@shadow_parent:	parent parent object.
  */
 
-int sysfs_create_dir(struct kobject * kobj, struct dentry *shadow_parent)
+int sysfs_create_dir(struct kobject * kobj)
 {
 	struct dentry * dentry = NULL;
 	struct dentry * parent;
@@ -204,9 +176,7 @@ int sysfs_create_dir(struct kobject * kobj, struct dentry *shadow_parent)
 
 	BUG_ON(!kobj);
 
-	if (shadow_parent)
-		parent = shadow_parent;
-	else if (kobj->parent)
+	if (kobj->parent)
 		parent = kobj->parent->dentry;
 	else if (sysfs_mount && sysfs_mount->mnt_sb)
 		parent = sysfs_mount->mnt_sb->s_root;
@@ -327,12 +297,21 @@ void sysfs_remove_subdir(struct dentry * d)
 }
 
 
-static void __sysfs_remove_dir(struct dentry *dentry)
+/**
+ *	sysfs_remove_dir - remove an object's directory.
+ *	@kobj:	object.
+ *
+ *	The only thing special about this is that we remove any files in
+ *	the directory before we remove the directory, and we've inlined
+ *	what used to be sysfs_rmdir() below, instead of calling separately.
+ */
+
+void sysfs_remove_dir(struct kobject * kobj)
 {
+	struct dentry * dentry = dget(kobj->dentry);
 	struct sysfs_dirent * parent_sd;
 	struct sysfs_dirent * sd, * tmp;
 
-	dget(dentry);
 	if (!dentry)
 		return;
 
@@ -353,46 +332,28 @@ static void __sysfs_remove_dir(struct dentry *dentry)
 	 * Drop reference from dget() on entrance.
 	 */
 	dput(dentry);
-}
-
-/**
- *	sysfs_remove_dir - remove an object's directory.
- *	@kobj:	object.
- *
- *	The only thing special about this is that we remove any files in
- *	the directory before we remove the directory, and we've inlined
- *	what used to be sysfs_rmdir() below, instead of calling separately.
- */
-
-void sysfs_remove_dir(struct kobject * kobj)
-{
-	__sysfs_remove_dir(kobj->dentry);
 	kobj->dentry = NULL;
 }
 
-int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
-		     const char *new_name)
+int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 {
 	int error = 0;
-	struct dentry * new_dentry;
+	struct inode * inode;
+	struct dentry * new_dentry, * old_parent, * new_parent;
 
-	if (!new_parent)
-		return -EFAULT;
+	if (!kobj->parent)
+		return -EINVAL;
+
+	old_parent = dget(kobj->dentry->d_parent);
+	inode = old_parent->d_inode;
 
 	down_write(&sysfs_rename_sem);
-	mutex_lock(&new_parent->d_inode->i_mutex);
+	mutex_lock(&inode->i_mutex);
 
+	new_parent = kobj->dentry->d_parent;
 	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
 	if (!IS_ERR(new_dentry)) {
-		/* By allowing two different directories with the
-		 * same d_parent we allow this routine to move
-		 * between different shadows of the same directory
-		 */
-		if (kobj->dentry->d_parent->d_inode != new_parent->d_inode)
-			return -EINVAL;
-		else if (new_dentry->d_parent->d_inode != new_parent->d_inode)
-			error = -EINVAL;
-		else if (new_dentry == kobj->dentry)
+		if (new_dentry == kobj->dentry)
 			error = -EINVAL;
 		else if (!new_dentry->d_inode) {
 			error = kobject_set_name(kobj, "%s", new_name);
@@ -414,9 +375,11 @@ int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
 			error = -EEXIST;
 		dput(new_dentry);
 	}
-	mutex_unlock(&new_parent->d_inode->i_mutex);
+	mutex_unlock(&inode->i_mutex);
 	up_write(&sysfs_rename_sem);
 
+	dput(old_parent);
+
 	return error;
 }
 
@@ -595,95 +558,6 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 	return offset;
 }
 
-
-/**
- *	sysfs_make_shadowed_dir - Setup so a directory can be shadowed
- *	@kobj:	object we're creating shadow of.
- */
-
-int sysfs_make_shadowed_dir(struct kobject *kobj,
-	void * (*follow_link)(struct dentry *, struct nameidata *))
-{
-	struct inode *inode;
-	struct inode_operations *i_op;
-
-	inode = kobj->dentry->d_inode;
-	if (inode->i_op != &sysfs_dir_inode_operations)
-		return -EINVAL;
-
-	i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
-	if (!i_op)
-		return -ENOMEM;
-
-	memcpy(i_op, &sysfs_dir_inode_operations, sizeof(*i_op));
-	i_op->follow_link = follow_link;
-
-	/* Locking of inode->i_op?
-	 * Since setting i_op is a single word write and they
-	 * are atomic we should be ok here.
-	 */
-	inode->i_op = i_op;
-	return 0;
-}
-
-/**
- *	sysfs_create_shadow_dir - create a shadow directory for an object.
- *	@kobj:	object we're creating directory for.
- *
- *	sysfs_make_shadowed_dir must already have been called on this
- *	directory.
- */
-
-struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
-{
-	struct sysfs_dirent *sd;
-	struct dentry *parent, *dir, *shadow;
-	struct inode *inode;
-
-	dir = kobj->dentry;
-	inode = dir->d_inode;
-	parent = dir->d_parent;
-	shadow = ERR_PTR(-EINVAL);
-	if (!sysfs_is_shadowed_inode(inode))
-		goto out;
-
-	shadow = d_alloc(parent, &dir->d_name);
-	if (!shadow)
-		goto nomem;
-
-	sd = __sysfs_make_dirent(shadow, kobj, inode->i_mode, SYSFS_DIR);
-	if (!sd)
-		goto nomem;
-
-	d_instantiate(shadow, igrab(inode));
-	inc_nlink(inode);
-	inc_nlink(parent->d_inode);
-	shadow->d_op = &sysfs_dentry_ops;
-
-	dget(shadow);		/* Extra count - pin the dentry in core */
-
-out:
-	return shadow;
-nomem:
-	dput(shadow);
-	shadow = ERR_PTR(-ENOMEM);
-	goto out;
-}
-
-/**
- *	sysfs_remove_shadow_dir - remove an object's directory.
- *	@shadow: dentry of shadow directory
- *
- *	The only thing special about this is that we remove any files in
- *	the directory before we remove the directory, and we've inlined
- *	what used to be sysfs_rmdir() below, instead of calling separately.
- */
-
-void sysfs_remove_shadow_dir(struct dentry *shadow)
-{
-	__sysfs_remove_dir(shadow);
-}
-
 const struct file_operations sysfs_dir_operations = {
 	.open		= sysfs_dir_open,
 	.release	= sysfs_dir_close,
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index b20951c..46a277b 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -13,7 +13,6 @@
 #include <linux/dcache.h>
 #include <linux/namei.h>
 #include <linux/err.h>
-#include <linux/fs.h>
 #include <asm/semaphore.h>
 #include "sysfs.h"
 
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 4de5c6b..69e6e9b 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -33,16 +33,6 @@ static const st