[PATCH 2/5] sysfs: Remove first pass at shadow directory support

[ebiederm@xmission.com (Eric W. Biederman)]

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 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 23a48a3..7978cf2 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -23,7 +23,7 @@ static void sysfs_clear_inode(struct inode *inode);
 
 static const struct super_operations sysfs_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= sysfs_delete_inode,
+	.drop_inode	= generic_delete_inode,
 	.clear_inode	= sysfs_clear_inode,
 };
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a77c57e..ce6b3ec 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -13,7 +13,6 @@ struct sysfs_dirent {
 extern struct vfsmount * sysfs_mount;
 extern struct kmem_cache *sysfs_dir_cachep;
 
-extern void sysfs_delete_inode(struct inode *inode);
 extern struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent *);
 extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));
 
@@ -124,7 +123,3 @@ static inline void sysfs_put(struct sysfs_dirent * sd)
 		release_sysfs_dirent(sd);
 }
 
-static inline int sysfs_is_shadowed_inode(struct inode *inode)
-{
-	return S_ISDIR(inode->i_mode) && inode->i_op->follow_link;
-}
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index d37cd7f..c96d243 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -74,13 +74,9 @@ extern void kobject_init(struct kobject *);
 extern void kobject_cleanup(struct kobject *);
 
 extern int __must_check kobject_add(struct kobject *);
-extern int __must_check kobject_shadow_add(struct kobject *, struct dentry *);
 extern void kobject_del(struct kobject *);
 
 extern int __must_check kobject_rename(struct kobject *, const char *new_name);
-extern int __must_check kobject_shadow_rename(struct kobject *kobj,
-						struct dentry *new_parent,
-						const char *new_name);
 extern int __must_check kobject_move(struct kobject *, struct kobject *);
 
 extern int __must_check kobject_register(struct kobject *);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index fea9a6b..1f1bb45 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -17,8 +17,6 @@
 
 struct kobject;
 struct module;
-struct nameidata;
-struct dentry;
 
 struct attribute {
 	const char		* name;
@@ -83,13 +81,13 @@ extern int sysfs_schedule_callback(struct kobject *kobj,
 		void (*func)(void *), void *data);
 
 extern int __must_check
-sysfs_create_dir(struct kobject *, struct dentry *);
+sysfs_create_dir(struct kobject *);
 
 extern void
 sysfs_remove_dir(struct kobject *);
 
 extern int __must_check
-sysfs_rename_dir(struct kobject *, struct dentry *, const char *new_name);
+sysfs_rename_dir(struct kobject *, const char *new_name);
 
 extern int __must_check
 sysfs_move_dir(struct kobject *, struct kobject *);
@@ -126,12 +124,6 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
 
 void sysfs_notify(struct kobject * k, char *dir, char *attr);
 
-
-extern int sysfs_make_shadowed_dir(struct kobject *kobj,
-	void * (*follow_link)(struct dentry *, struct nameidata *));
-extern struct dentry *sysfs_create_shadow_dir(struct kobject *kobj);
-extern void sysfs_remove_shadow_dir(struct dentry *dir);
-
 extern int __must_check sysfs_init(void);
 
 #else /* CONFIG_SYSFS */
@@ -142,7 +134,7 @@ static inline int sysfs_schedule_callback(struct kobject *kobj,
 	return -ENOSYS;
 }
 
-static inline int sysfs_create_dir(struct kobject * k, struct dentry *shadow)
+static inline int sysfs_create_dir(struct kobject * k)
 {
 	return 0;
 }
@@ -152,9 +144,7 @@ static inline void sysfs_remove_dir(struct kobject * k)
 	;
 }
 
-static inline int sysfs_rename_dir(struct kobject * k,
-					struct dentry *new_parent,
-					const char *new_name)
+static inline int sysfs_rename_dir(struct kobject * k, const char *new_name)
 {
 	return 0;
 }
@@ -229,12 +219,6 @@ static inline void sysfs_notify(struct kobject * k, char *dir, char *attr)
 {
 }
 
-static inline int sysfs_make_shadowed_dir(struct kobject *kobj,
-	void * (*follow_link)(struct dentry *, struct nameidata *))
-{
-	return 0;
-}
-
 static inline int __must_check sysfs_init(void)
 {
 	return 0;
diff --git a/lib/kobject.c b/lib/kobject.c
index 09cb276..f590ad8 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -44,11 +44,11 @@ static int populate_dir(struct kobject * kobj)
 	return error;
 }
 
-static int create_dir(struct kobject * kobj, struct dentry *shadow_parent)
+static int create_dir(struct kobject * kobj)
 {
 	int error = 0;
 	if (kobject_name(kobj)) {
-		error = sysfs_create_dir(kobj, shadow_parent);
+		error = sysfs_create_dir(kobj);
 		if (!error) {
 			if ((error = populate_dir(kobj)))
 				sysfs_remove_dir(kobj);
@@ -159,10 +159,9 @@ static void unlink(struct kobject * kobj)
 /**
  *	kobject_add - add an object to the hierarchy.
  *	@kobj:	object.
- *	@shadow_parent: sysfs directory to add to.
  */
 
-int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
+int kobject_add(struct kobject * kobj)
 {
 	int error = 0;
 	struct kobject * parent;
@@ -193,7 +192,7 @@ int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
 	}
 	kobj->parent = parent;
 
-	error = create_dir(kobj, shadow_parent);
+	error = create_dir(kobj);
 	if (error) {
 		/* unlink does the kobject_put() for us */
 		unlink(kobj);
@@ -214,15 +213,6 @@ int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
 	return error;
 }
 
-/**
- *	kobject_add - add an object to the hierarchy.
- *	@kobj:	object.
- */
-int kobject_add(struct kobject * kobj)
-{
-	return kobject_shadow_add(kobj, NULL);
-}
-
 
 /**
  *	kobject_register - initialize and add an object.
@@ -315,30 +305,7 @@ int kobject_rename(struct kobject * kobj, const char *new_name)
 	kobj = kobject_get(kobj);
 	if (!kobj)
 		return -EINVAL;
-	if (!kobj->parent)
-		return -EINVAL;
-	error = sysfs_rename_dir(kobj, kobj->parent->dentry, new_name);
-	kobject_put(kobj);
-
-	return error;
-}
-
-/**
- *	kobject_rename - change the name of an object
- *	@kobj:	object in question.
- *	@new_parent: object's new parent
- *	@new_name: object's new name
- */
-
-int kobject_shadow_rename(struct kobject * kobj, struct dentry *new_parent,
-			  const char *new_name)
-{
-	int error = 0;
-
-	kobj = kobject_get(kobj);
-	if (!kobj)
-		return -EINVAL;
-	error = sysfs_rename_dir(kobj, new_parent, new_name);
+	error = sysfs_rename_dir(kobj, new_name);
 	kobject_put(kobj);
 
 	return error;
-- 
1.5.0.g53756