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>
---
These patches are against 2.6.22-rc4-mm2  Hopefully that is new enough
to catch all of the in flight sysfs patches.

 fs/sysfs/dir.c          |  172 ++++++++++-------------------------------------
 fs/sysfs/group.c        |    1 -
 fs/sysfs/inode.c        |   10 ---
 fs/sysfs/mount.c        |    2 +-
 fs/sysfs/sysfs.h        |    6 --
 include/linux/kobject.h |    4 -
 include/linux/sysfs.h   |   24 +------
 lib/kobject.c           |   44 ++----------
 8 files changed, 48 insertions(+), 215 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index b4074ad..b1da4fc 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -415,10 +415,9 @@ 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;
@@ -426,9 +425,7 @@ 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;
@@ -516,12 +513,26 @@ 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 = kobj->dentry;
 	struct sysfs_dirent *removed = NULL;
 	struct sysfs_dirent *parent_sd;
 	struct sysfs_dirent **pos;
 
+	spin_lock(&kobj_sysfs_assoc_lock);
+	kobj->dentry = NULL;
+	spin_unlock(&kobj_sysfs_assoc_lock);
+
 	if (!dentry)
 		return;
 
@@ -555,55 +566,35 @@ static void __sysfs_remove_dir(struct dentry *dentry)
 	remove_dir(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 *d = kobj->dentry;
-
-	spin_lock(&kobj_sysfs_assoc_lock);
-	kobj->dentry = NULL;
-	spin_unlock(&kobj_sysfs_assoc_lock);
-
-	__sysfs_remove_dir(d);
-}
-
-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)
 {
-	struct sysfs_dirent *sd = kobj->dentry->d_fsdata;
-	struct sysfs_dirent *parent_sd = new_parent->d_fsdata;
-	struct dentry *new_dentry;
+	struct sysfs_dirent *sd;
+	struct sysfs_dirent *parent_sd;
+	struct inode *inode;
+	struct dentry *new_dentry, *parent;
 	char *dup_name;
 	int error;
 
-	if (!new_parent)
-		return -EFAULT;
+	if (!kobj->parent)
+		return -EINVAL;
+
+	parent = dget(kobj->dentry->d_parent);
+	inode = parent->d_inode;
+
+	sd = kobj->dentry->d_fsdata;
 
 	down_write(&sysfs_rename_sem);
-	mutex_lock(&new_parent->d_inode->i_mutex);
+	mutex_lock(&inode->i_mutex);
 
-	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
+	parent_sd = parent->d_fsdata;
+	new_dentry = lookup_one_len(new_name, parent_sd->s_dentry, strlen(new_name));
 	if (IS_ERR(new_dentry)) {
 		error = PTR_ERR(new_dentry);
 		goto out_unlock;
 	}
 
-	/* By allowing two different directories with the same
-	 * d_parent we allow this routine to move between different
-	 * shadows of the same directory
-	 */
 	error = -EINVAL;
-	if (kobj->dentry->d_parent->d_inode != new_parent->d_inode ||
-	    new_dentry->d_parent->d_inode != new_parent->d_inode ||
-	    new_dentry == kobj->dentry)
+	if (new_dentry == kobj->dentry)
 		goto out_dput;
 
 	error = -EEXIST;
@@ -643,8 +634,11 @@ int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
  out_dput:
 	dput(new_dentry);
  out_unlock:
-	mutex_unlock(&new_parent->d_inode->i_mutex);
+	mutex_unlock(&inode->i_mutex);
 	up_write(&sysfs_rename_sem);
+
+	dput(parent);
+
 	return error;
 }
 
@@ -837,98 +831,6 @@ 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 dentry *dir = kobj->dentry;
-	struct inode *inode = dir->d_inode;
-	struct dentry *parent = dir->d_parent;
-	struct sysfs_dirent *parent_sd = parent->d_fsdata;
-	struct dentry *shadow;
-	struct sysfs_dirent *sd;
-
-	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_new_dirent("_SHADOW_", inode->i_mode, SYSFS_DIR);
-	if (!sd)
-		goto nomem;
-	sd->s_elem.dir.kobj = kobj;
-	/* point to parent_sd but don't attach to it */
-	sd->s_parent = sysfs_get(parent_sd);
-	sysfs_attach_dirent(sd, NULL, shadow);
-
-	d_instantiate(shadow, igrab(inode));
-	inc_nlink(inode);
-	inc_nlink(parent->d_inode);
-
-	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 52eed2a..82e0f55 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 b1a4527..8181c49 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -34,16 +34,6 @@ static const struct inode_operations sysfs_inode_operations ={
 	.setattr	= sysfs_setattr,
 };
 
-void sysfs_delete_inode(struct inode *inode)
-{
-	/* Free the shadowed directory inode operations */
-	if (sysfs_is_shadowed_inode(inode)) {
-		kfree(inode->i_op);
-		inode->i_op = NULL;
-	}
-	return generic_delete_inode(inode);
-}
-
 int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
 {
 	struct inode * inode = dentry->d_inode;
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 4be9593..c8126ab 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -21,7 +21,7 @@ struct kmem_cache *sysfs_dir_cachep;
 
 static const struct super_operations sysfs_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= sysfs_delete_inode,
+	.drop_inode	= generic_delete_inode,
 };
 
 static struct sysfs_dirent sysfs_root = {
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6f8aaf3..6258462 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -53,7 +53,6 @@ extern struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
 extern void sysfs_put_active_two(struct sysfs_dirent *sd);
 extern void sysfs_deactivate(struct sysfs_dirent *sd);
 
-extern void sysfs_delete_inode(struct inode *inode);
 extern void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode);
 extern struct inode * sysfs_get_inode(struct sysfs_dirent *sd);
 extern void sysfs_instantiate(struct dentry *dentry, struct inode *inode);
@@ -100,8 +99,3 @@ static inline void sysfs_put(struct sysfs_dirent * sd)
 	if (sd && atomic_dec_and_te