sysfs backing store - updated

diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-prepare-file_operations fs/sysfs/sysfs.h
@@ -16,14 +16,30 @@ extern int sysfs_readlink(struct dentry 
 extern int sysfs_follow_link(struct dentry *, struct nameidata *);
 extern struct rw_semaphore sysfs_rename_sem;
 
+static inline struct kobject * to_kobj(struct dentry * dentry)
+{
+	return ((struct kobject *) dentry->d_fsdata);
+}
+
+static inline struct attribute * to_attr(struct dentry * dentry)
+{
+	return ((struct attribute *) dentry->d_fsdata);
+}
+
+static inline struct bin_attribute * to_bin_attr(struct dentry * dentry)
+{
+	return ((struct bin_attribute *) dentry->d_fsdata);
+}
+
 static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
 {
 	struct kobject * kobj = NULL;
 
 	spin_lock(&dcache_lock);
 	if (!d_unhashed(dentry))
-		kobj = kobject_get(dentry->d_fsdata);
+		kobj = kobject_get(to_kobj(dentry));
 	spin_unlock(&dcache_lock);
 
 	return kobj;
 }
+

diff -puN fs/sysfs/file.c~sysfs-backing-store-prepare-file_operations fs/sysfs/file.c
@@ -67,7 +67,7 @@ struct sysfs_buffer {
 
 /**
  *	fill_read_buffer - allocate and fill buffer from object.
- *	@file:		file pointer.
+ *	@dentry:	dentry pointer.
  *	@buffer:	data buffer for file.
  *
  *	Allocate @buffer->page, if it hasn't been already, then call the

@@ -75,10 +75,10 @@ struct sysfs_buffer {
  *	data. 
  *	This is called only once, on the file's first read. 
  */
-static int fill_read_buffer(struct file * file, struct sysfs_buffer * buffer)
+static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
 {
-	struct attribute * attr = file->f_dentry->d_fsdata;
-	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+	struct attribute * attr = to_attr(dentry);
+	struct kobject * kobj = to_kobj(dentry->d_parent);
 	struct sysfs_ops * ops = buffer->ops;
 	int ret = 0;
 	ssize_t count;

@@ -150,7 +150,7 @@ sysfs_read_file(struct file *file, char 
 	ssize_t retval = 0;
 
 	if (!*ppos) {
-		if ((retval = fill_read_buffer(file,buffer)))
+		if ((retval = fill_read_buffer(file->f_dentry,buffer)))
 			return retval;
 	}
 	pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",

@@ -197,10 +197,10 @@ fill_write_buffer(struct sysfs_buffer * 
  */
 
 static int 
-flush_write_buffer(struct file * file, struct sysfs_buffer * buffer, size_t count)
+flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
 {
-	struct attribute * attr = file->f_dentry->d_fsdata;
-	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+	struct attribute * attr = to_attr(dentry);
+	struct kobject * kobj = to_kobj(dentry->d_parent);
 	struct sysfs_ops * ops = buffer->ops;
 
 	return ops->store(kobj,attr,buffer->page,count);

@@ -231,7 +231,7 @@ sysfs_write_file(struct file *file, cons
 
 	count = fill_write_buffer(buffer,buf,count);
 	if (count > 0)
-		count = flush_write_buffer(file,buffer,count);
+		count = flush_write_buffer(file->f_dentry,buffer,count);
 	if (count > 0)
 		*ppos += count;
 	return count;

@@ -240,7 +240,7 @@ sysfs_write_file(struct file *file, cons
 static int check_perm(struct inode * inode, struct file * file)
 {
 	struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
-	struct attribute * attr = file->f_dentry->d_fsdata;
+	struct attribute * attr = to_attr(file->f_dentry);
 	struct sysfs_buffer * buffer;
 	struct sysfs_ops * ops = NULL;
 	int error = 0;

@@ -321,8 +321,8 @@ static int sysfs_open_file(struct inode 
 
 static int sysfs_release(struct inode * inode, struct file * filp)
 {
-	struct kobject * kobj = filp->f_dentry->d_parent->d_fsdata;
-	struct attribute * attr = filp->f_dentry->d_fsdata;
+	struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
+	struct attribute * attr = to_attr(filp->f_dentry);
 	struct sysfs_buffer * buffer = filp->private_data;
 
 	if (kobj) 

diff -puN fs/sysfs/bin.c~sysfs-backing-store-prepare-file_operations fs/sysfs/bin.c
@@ -17,8 +17,8 @@
 static int
 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
 {
-	struct bin_attribute * attr = dentry->d_fsdata;
-	struct kobject * kobj = dentry->d_parent->d_fsdata;
+	struct bin_attribute * attr = to_bin_attr(dentry);
+	struct kobject * kobj = to_kobj(dentry->d_parent);
 
 	return attr->read(kobj, buffer, off, count);
 }

@@ -60,8 +60,8 @@ read(struct file * file, char __user * u
 static int
 flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
 {
-	struct bin_attribute *attr = dentry->d_fsdata;
-	struct kobject *kobj = dentry->d_parent->d_fsdata;
+	struct bin_attribute *attr = to_bin_attr(dentry->d_parent);
+	struct kobject *kobj = to_kobj(dentry);
 
 	return attr->write(kobj, buffer, offset, count);
 }

@@ -95,7 +95,7 @@ static ssize_t write(struct file * file,
 static int open(struct inode * inode, struct file * file)
 {
 	struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
-	struct bin_attribute * attr = file->f_dentry->d_fsdata;
+	struct bin_attribute * attr = to_bin_attr(file->f_dentry);
 	int error = -EINVAL;
 
 	if (!kobj || !attr)

@@ -130,8 +130,8 @@ static int open(struct inode * inode, st
 
 static int release(struct inode * inode, struct file * file)
 {
-	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
-	struct bin_attribute * attr = file->f_dentry->d_fsdata;
+	struct kobject * kobj = to_kobj(file->f_dentry->d_parent);
+	struct bin_attribute * attr = to_bin_attr(file->f_dentry);
 	u8 * buffer = file->private_data;
 
 	if (kobj) 

diff -puN include/linux/sysfs.h~sysfs-backing-store-add-sysfs_dirent include/linux/sysfs.h
@@ -9,6 +9,8 @@
 #ifndef _SYSFS_H_
 #define _SYSFS_H_
 
+#include <asm/atomic.h>
+
 struct kobject;
 struct module;
 

@@ -57,6 +59,23 @@ struct sysfs_ops {
 	ssize_t	(*store)(struct kobject *,struct attribute *,const char *, size_t);
 };
 
+struct sysfs_dirent {
+	atomic_t		s_count;
+	struct list_head	s_sibling;
+	struct list_head	s_children;
+	void 			* s_element;
+	int			s_type;
+	umode_t			s_mode;
+	struct dentry		* s_dentry;
+};
+
+#define SYSFS_ROOT		0x0001
+#define SYSFS_DIR		0x0002
+#define SYSFS_KOBJ_ATTR 	0x0004
+#define SYSFS_KOBJ_BIN_ATTR	0x0008
+#define SYSFS_KOBJ_LINK 	0x0020
+#define SYSFS_NOT_PINNED	(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
+
 #ifdef CONFIG_SYSFS
 
 extern int

135 lines not on this page · raw message

diff -puN fs/sysfs/file.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/file.c
@@ -346,19 +346,22 @@ static struct file_operations sysfs_file
 };
 
 
-int sysfs_add_file(struct dentry * dir, const struct attribute * attr)
+int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
 {
 	struct dentry * dentry;
-	int error;
+	struct sysfs_dirent * parent_sd = dir->d_fsdata;
+	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
 
 	down(&dir->d_inode->i_sem);
 	dentry = sysfs_get_dentry(dir,attr->name);
 	if (!IS_ERR(dentry)) {
-		error = sysfs_create(dentry,
-				     (attr->mode & S_IALLUGO) | S_IFREG,
-				     init_file);
+		error = sysfs_create(dentry, mode, init_file);
 		if (!error)
-			dentry->d_fsdata = (void *)attr;
+			error = sysfs_make_dirent(parent_sd, dentry, 
+						(void *) attr, mode, type);
+		if (error)
+			d_drop(dentry);
 		dput(dentry);
 	} else
 		error = PTR_ERR(dentry);

@@ -375,9 +378,10 @@ int sysfs_add_file(struct dentry * dir, 
 
 int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
 {
-	if (kobj && attr)
-		return sysfs_add_file(kobj->dentry,attr);
-	return -EINVAL;
+	BUG_ON(!kobj || !kobj->dentry || !attr);
+
+	return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
+
 }
 
 

@@ -409,7 +413,8 @@ int sysfs_update_file(struct kobject * k
 			 */
 			dput(victim);
 			res = 0;
-		}
+		} else
+			d_drop(victim);
 		
 		/**
 		 * Drop the reference acquired from sysfs_get_dentry() above.

diff -puN fs/sysfs/bin.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/bin.c
@@ -160,24 +160,26 @@ int sysfs_create_bin_file(struct kobject
 {
 	struct dentry * dentry;
 	struct dentry * parent;
+	umode_t mode = (attr->attr.mode & S_IALLUGO) | S_IFREG;
 	int error = 0;
 
-	if (!kobj || !attr)
-		return -EINVAL;
+	BUG_ON(!kobj || !kobj->dentry || !attr);
 
 	parent = kobj->dentry;
 
 	down(&parent->d_inode->i_sem);
 	dentry = sysfs_get_dentry(parent,attr->attr.name);
 	if (!IS_ERR(dentry)) {
-		dentry->d_fsdata = (void *)attr;
-		error = sysfs_create(dentry,
-				     (attr->attr.mode & S_IALLUGO) | S_IFREG,
-				     NULL);
+		error = sysfs_create(dentry, mode, NULL);
 		if (!error) {
 			dentry->d_inode->i_size = attr->size;
 			dentry->d_inode->i_fop = &bin_fops;
+			error = sysfs_make_dirent(parent->d_fsdata, dentry, 
+						  (void *) attr, mode, 
+						  SYSFS_KOBJ_BIN_ATTR);
 		}
+		if (error)
+			d_drop(dentry);
 		dput(dentry);
 	} else
 		error = PTR_ERR(dentry);

diff -puN fs/sysfs/group.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/group.c
@@ -31,7 +31,7 @@ static int create_files(struct dentry * 
 	int error = 0;
 
 	for (attr = grp->attrs; *attr && !error; attr++) {
-		error = sysfs_add_file(dir,*attr);
+		error = sysfs_add_file(dir, *attr, SYSFS_KOBJ_ATTR);
 	}
 	if (error)
 		remove_files(dir,grp);

@@ -45,6 +45,8 @@ int sysfs_create_group(struct kobject * 
 	struct dentry * dir;
 	int error;
 
+	BUG_ON(!kobj || !kobj->dentry);
+
 	if (grp->name) {
 		error = sysfs_create_subdir(kobj,grp->name,&dir);
 		if (error)

diff -puN fs/sysfs/mount.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/mount.c
@@ -22,6 +22,13 @@ static struct super_operations sysfs_ops
 	.drop_inode	= generic_delete_inode,
 };
 
+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)
 {
 	struct inode *inode;

@@ -50,6 +57,7 @@ static int sysfs_fill_super(struct super
 		iput(inode);
 		return -ENOMEM;
 	}
+	root->d_fsdata = &sysfs_root;
 	sb->s_root = root;
 	return 0;
 }

diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-add-sysfs_dirent fs/sysfs/sysfs.h
@@ -4,9 +4,11 @@ extern struct vfsmount * sysfs_mount;
 extern struct inode * sysfs_new_inode(mode_t mode);
 extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));
 
+extern int sysfs_make_dirent(struct sysfs_dirent *, struct dentry *, void *, 
+				umode_t, int);
 extern struct dentry * sysfs_get_dentry(struct dentry *, const char *);
 
-extern int sysfs_add_file(struct dentry * dir, const struct attribute * attr);
+extern int sysfs_add_file(struct dentry *, const struct attribute *, int);
 extern void sysfs_hash_and_remove(struct dentry * dir, const char * name);
 
 extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);

@@ -16,19 +18,27 @@ extern int sysfs_readlink(struct dentry 
 extern int sysfs_follow_link(struct dentry *, struct nameidata *);
 extern struct rw_semaphore sysfs_rename_sem;
 
+struct sysfs_symlink {
+	char * link_name;
+	struct kobject * target_kobj;
+};
+
 static inline struct kobject * to_kobj(struct dentry * dentry)
 {
-	return ((struct kobject *) dentry->d_fsdata);
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	return ((struct kobject *) sd->s_element);
 }
 
 static inline struct attribute * to_attr(struct dentry * dentry)
 {
-	return ((struct attribute *) dentry->d_fsdata);
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	return ((struct attribute *) sd->s_element);
 }
 
 static inline struct bin_attribute * to_bin_attr(struct dentry * dentry)
 {
-	return ((struct bin_attribute *) dentry->d_fsdata);
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	return ((struct bin_attribute *) sd->s_element);
 }
 
 static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)

@@ -36,10 +46,27 @@ static inline struct kobject *sysfs_get_
 	struct kobject * kobj = NULL;
 
 	spin_lock(&dcache_lock);
-	if (!d_unhashed(dentry))
-		kobj = kobject_get(to_kobj(dentry));
+	if (!d_unhashed(dentry)) {
+		struct sysfs_dirent * sd = dentry->d_fsdata;
+		if (sd->s_type & SYSFS_KOBJ_LINK) {
+			struct sysfs_symlink * sl = sd->s_element;
+			kobj = kobject_get(sl->target_kobj);
+		} else
+			kobj = kobject_get(sd->s_element);
+	}
 	spin_unlock(&dcache_lock);
 
 	return kobj;
 }
 
+static inline void release_sysfs_dirent(struct sysfs_dirent * sd)
+{
+	if (sd->s_type & SYSFS_KOBJ_LINK) {
+		struct sysfs_symlink * sl = sd->s_element;
+		kfree(sl->link_name);
+		kobject_put(sl->target_kobj);
+		kfree(sl);
+	}
+	kfree(sd);
+}
+

diff -puN fs/sysfs/symlink.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/symlink.c
@@ -53,6 +53,36 @@ static void fill_object_path(struct kobj
 	}
 }
 
+static int sysfs_add_link(struct dentry * dentry, char * name, struct kobject * target)
+{
+	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+	struct sysfs_symlink * sl;
+	int error = 0;
+
+	error = -ENOMEM;
+	sl = kmalloc(sizeof(*sl), GFP_KERNEL);
+	if (!sl)
+		goto exit1;
+
+	sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
+	if (!sl->link_name)
+		goto exit2;
+
+	strcpy(sl->link_name, name);
+	sl->target_kobj = kobject_get(target);
+
+	error = sysfs_make_dirent(parent_sd, dentry, sl, S_IFLNK|S_IRWXUGO, 
+				SYSFS_KOBJ_LINK);
+	if (!error)
+		return 0;
+
+	kfree(sl->link_name);
+exit2:
+	kfree(sl);
+exit1:
+	return error;
+}
+
 /**
  *	sysfs_create_link - create symlink between two objects.
  *	@kobj:	object whose directory we're creating the link in.

@@ -65,15 +95,16 @@ int sysfs_create_link(struct kobject * k
 	struct dentry * d;
 	int error = 0;
 
+	BUG_ON(!kobj || !kobj->dentry || !name);
+
 	down(&dentry->d_inode->i_sem);
 	d = sysfs_get_dentry(dentry,name);
 	if (!IS_ERR(d)) {
 		error = sysfs_create(d, S_IFLNK|S_IRWXUGO, init_symlink);
 		if (!error)
-			/* 
-			 * associate the link dentry with the target kobject 
-			 */
-			d->d_fsdata = kobject_get(target);
+			error = sysfs_add_link(d, name, target);
+		if (error)
+			d_drop(d);
 		dput(d);
 	} else 
 		error = PTR_ERR(d);

diff -puN fs/sysfs/inode.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/inode.c
@@ -11,6 +11,8 @@
 #include <linux/pagemap.h>
 #include <linux/namei.h>
 #include <linux/backing-dev.h>
+#include "sysfs.h"
+
 extern struct super_block * sysfs_sb;
 
 static struct address_space_operations sysfs_aops = {

@@ -91,6 +93,7 @@ struct dentry * sysfs_get_dentry(struct 
 void sysfs_hash_and_remove(struct dentry * dir, const char * name)
 {
 	struct dentry * victim;
+	struct sysfs_dirent * sd;
 
 	down(&dir->d_inode->i_sem);
 	victim = sysfs_get_dentry(dir,name);

@@ -101,14 +104,17 @@ void sysfs_hash_and_remove(struct dentry
 			pr_debug("sysfs: Removing %s (%d)\n", victim->d_name.name,
 				 atomic_read(&victim->d_count));
 
+			sd = victim->d_fsdata;
 			d_drop(victim);
 			/* release the target kobject in case of 
 			 * a symlink
 			 */
 			if (S_ISLNK(victim->d_inode->i_mode))
-				kobject_put(victim->d_fsdata);
+				kobject_put(sd->s_element);
+			list_del_init(&sd->s_sibling);
 			simple_unlink(dir->d_inode,victim);
-		}
+		} else
+			d_drop(victim);
 		/*
 		 * Drop reference from sysfs_get_dentry() above.
 		 */

diff -puN fs/sysfs/dir.c~sysfs-backing-store-use-sysfs_dirent-tree-in-removal fs/sysfs/dir.c
@@ -19,7 +19,7 @@ static void sysfs_d_iput(struct dentry *
 	if (sd) {
 		BUG_ON(sd->s_dentry != dentry);
 		sd->s_dentry = NULL;
-		release_sysfs_dirent(sd);
+		sysfs_put(sd);
 	}
 	iput(inode);
 }

@@ -61,7 +61,7 @@ int sysfs_make_dirent(struct sysfs_diren
 	sd->s_mode = mode;
 	sd->s_type = type;
 	sd->s_dentry = dentry;
-	dentry->d_fsdata = sd;
+	dentry->d_fsdata = sysfs_get(sd);
 	dentry->d_op = &sysfs_dentry_ops;
 
 	return 0;

@@ -146,6 +146,7 @@ static void remove_dir(struct dentry * d
 	d_delete(d);
 	sd = d->d_fsdata;
  	list_del_init(&sd->s_sibling);
+	sysfs_put(sd);
 	if (d->d_inode)
 		simple_rmdir(parent->d_inode,d);
 

@@ -173,49 +174,22 @@ void sysfs_remove_subdir(struct dentry *
 
 void sysfs_remove_dir(struct kobject * kobj)
 {
-	struct list_head * node;
 	struct dentry * dentry = dget(kobj->dentry);
+	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+	struct sysfs_dirent * sd, * tmp;
 
 	if (!dentry)
 		return;
 
 	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
 	down(&dentry->d_inode->i_sem);
-
-	spin_lock(&dcache_lock);
-restart:
-	node = dentry->d_subdirs.next;
-	while (node != &dentry->d_subdirs) {
-		struct dentry * d = list_entry(node,struct dentry,d_child);
-
-		node = node->next;
-		pr_debug(" o %s (%d): ",d->d_name.name,atomic_read(&d->d_count));
-		if (!d_unhashed(d) && (d->d_inode)) {
-			struct sysfs_dirent * sd = d->d_fsdata;
-			d = dget_locked(d);
-			pr_debug("removing");
-
-			/**
-			 * Unlink and unhash.
-			 */
-			__d_drop(d);
-			spin_unlock(&dcache_lock);
-			/* release the target kobject in case of 
-			 * a symlink
-			 */
-			if (S_ISLNK(d->d_inode->i_mode))
-				kobject_put(sd->s_element);
-			
-			list_del_init(&sd->s_sibling);
-			simple_unlink(dentry->d_inode,d);
-			dput(d);
-			pr_debug(" done\n");
-			spin_lock(&dcache_lock);
-			/* re-acquired dcache_lock, need to restart */
-			goto restart;
-		}
+	list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
+		if (!sd->s_element)
+			continue;
+		list_del_init(&sd->s_sibling);
+		sysfs_drop_dentry(sd, dentry);
+		sysfs_put(sd);
 	}
-	spin_unlock(&dcache_lock);
 	up(&dentry->d_inode->i_sem);
 
 	remove_dir(dentry);

116 lines not on this page · raw message

diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-use-sysfs_dirent-tree-in-removal fs/sysfs/sysfs.h
@@ -14,6 +14,8 @@ extern void sysfs_hash_and_remove(struct
 extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);
 extern void sysfs_remove_subdir(struct dentry *);
 
+extern const unsigned char * sysfs_get_name(struct sysfs_dirent *sd);
+extern void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent);
 extern int sysfs_readlink(struct dentry *, char __user *, int );
 extern int sysfs_follow_link(struct dentry *, struct nameidata *);
 extern struct rw_semaphore sysfs_rename_sem;

@@ -70,3 +72,18 @@ static inline void release_sysfs_dirent(
 	kfree(sd);
 }
 
+static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
+{
+	if (sd) {
+		WARN_ON(!atomic_read(&sd->s_count));
+		atomic_inc(&sd->s_count);
+	}
+	return sd;
+}
+
+static inline void sysfs_put(struct sysfs_dirent * sd)
+{
+	if (atomic_dec_and_test(&sd->s_count))
+		release_sysfs_dirent(sd);
+}
+

diff -puN fs/sysfs/dir.c~sysfs-backing-store-use-sysfs_dirent-tree-in-dir-file_operations fs/sysfs/dir.c
@@ -70,7 +70,7 @@ int sysfs_make_dirent(struct sysfs_diren
 static int init_dir(struct inode * inode)
 {
 	inode->i_op = &simple_dir_inode_operations;
-	inode->i_fop = &simple_dir_operations;
+	inode->i_fop = &sysfs_dir_operations;
 
 	/* directory inodes start off with i_nlink == 2 (for "." entry) */
 	inode->i_nlink++;

@@ -233,6 +233,145 @@ int sysfs_rename_dir(struct kobject * ko
 	return error;
 }
 
+static int sysfs_dir_open(struct inode *inode, struct file *file)
+{
+	struct dentry * dentry = file->f_dentry;
+	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+
+	down(&dentry->d_inode->i_sem);
+	file->private_data = sysfs_new_dirent(parent_sd, NULL);
+	up(&dentry->d_inode->i_sem);
+
+	return file->private_data ? 0 : -ENOMEM;
+
+}
+
+static int sysfs_dir_close(struct inode *inode, struct file *file)
+{
+	struct dentry * dentry = file->f_dentry;
+	struct sysfs_dirent * cursor = file->private_data;
+
+	down(&dentry->d_inode->i_sem);
+	list_del_init(&cursor->s_sibling);
+	up(&dentry->d_inode->i_sem);
+	sysfs_put(file->private_data);
+
+	return 0;
+}
+
+/* Relationship between s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct sysfs_dirent *sd)
+{
+	return (sd->s_mode >> 12) & 15;
+}
+
+static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
+{
+	struct dentry *dentry = filp->f_dentry;
+	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+	struct sysfs_dirent *cursor = filp->private_data;
+	struct list_head *p, *q = &cursor->s_sibling;
+	ino_t ino;
+	int i = filp->f_pos;
+
+	switch (i) {
+		case 0:
+			ino = dentry->d_inode->i_ino;
+			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
+				break;
+			filp->f_pos++;
+			i++;
+			/* fallthrough */
+		case 1:
+			ino = parent_ino(dentry);
+			if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
+				break;
+			filp->f_pos++;
+			i++;
+			/* fallthrough */
+		default:
+			if (filp->f_pos == 2) {
+				list_del(q);
+				list_add(q, &parent_sd->s_children);
+			}
+			for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
+				struct sysfs_dirent *next;
+				const char * name;
+				int len;
+
+				next = list_entry(p, struct sysfs_dirent,
+						   s_sibling);
+				if (!next->s_element)
+					continue;
+
+				name = sysfs_get_name(next);
+				len = strlen(name);
+				if (next->s_dentry)
+					ino = next->s_dentry->d_inode->i_ino;
+				else
+					ino = iunique(sysfs_sb, 2);
+
+				if (filldir(dirent, name, len, filp->f_pos, ino,
+						 dt_type(next)) < 0)
+					return 0;
+
+				list_del(q);
+				list_add(q, p);
+				p = q;
+				filp->f_pos++;
+			}
+	}
+	return 0;
+}
+
+static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
+{
+	struct dentry * dentry = file->f_dentry;
+
+	down(&dentry->d_inode->i_sem);
+	switch (origin) {
+		case 1:
+			offset += file->f_pos;
+		case 0:
+			if (offset >= 0)
+				break;
+		default:
+			up(&file->f_dentry->d_inode->i_sem);
+			return -EINVAL;
+	}
+	if (offset != file->f_pos) {
+		file->f_pos = offset;
+		if (file->f_pos >= 2) {
+			struct sysfs_dirent *sd = dentry->d_fsdata;
+			struct sysfs_dirent *cursor = file->private_data;
+			struct list_head *p;
+			loff_t n = file->f_pos - 2;
+
+			list_del(&cursor->s_sibling);
+			p = sd->s_children.next;
+			while (n && p != &sd->s_children) {
+				struct sysfs_dirent *next;
+				next = list_entry(p, struct sysfs_dirent,
+						   s_sibling);
+				if (next->s_element)
+					n--;
+				p = p->next;
+			}
+			list_add_tail(&cursor->s_sibling, p);
+		}
+	}
+	up(&dentry->d_inode->i_sem);
+	return offset;
+}
+
+struct file_operations sysfs_dir_operations = {
+	.open		= sysfs_dir_open,
+	.release	= sysfs_dir_close,
+	.llseek		= sysfs_dir_lseek,
+	.read		= generic_read_dir,
+	.readdir	= sysfs_readdir,
+};
+
 EXPORT_SYMBOL(sysfs_create_dir);
 EXPORT_SYMBOL(sysfs_remove_dir);
 EXPORT_SYMBOL(sysfs_rename_dir);

diff -puN fs/sysfs/mount.c~sysfs-backing-store-use-sysfs_dirent-tree-in-dir-file_operations fs/sysfs/mount.c
@@ -43,7 +43,7 @@ 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_fop = &sysfs_dir_operations;
 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
 		inode->i_nlink++;	
 	} else {

diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-use-sysfs_dirent-tree-in-dir-file_operations fs/sysfs/sysfs.h
@@ -19,6 +19,8 @@ extern void sysfs_drop_dentry(struct sys
 extern int sysfs_readlink(struct dentry *, char __user *, int );
 extern int sysfs_follow_link(struct dentry *, struct nameidata *);
 extern struct rw_semaphore sysfs_rename_sem;
+extern struct super_block * sysfs_sb;
+extern struct file_operations sysfs_dir_operations;
 
 struct sysfs_symlink {
 	char * link_name;

diff -puN fs/sysfs/dir.c~sysfs-backing-store-stop-pinning-dentries-inodes-for-leaves fs/sysfs/dir.c
@@ -61,15 +61,17 @@ int sysfs_make_dirent(struct sysfs_diren
 	sd->s_mode = mode;
 	sd->s_type = type;
 	sd->s_dentry = dentry;
-	dentry->d_fsdata = sysfs_get(sd);
-	dentry->d_op = &sysfs_dentry_ops;
+	if (dentry) {
+		dentry->d_fsdata = sysfs_get(sd);
+		dentry->d_op = &sysfs_dentry_ops;
+	}
 
 	return 0;
 }
 
 static int init_dir(struct inode * inode)
 {
-	inode->i_op = &simple_dir_inode_operations;
+	inode->i_op = &sysfs_dir_inode_operations;
 	inode->i_fop = &sysfs_dir_operations;
 
 	/* directory inodes start off with i_nlink == 2 (for "." entry) */

@@ -77,6 +79,18 @@ static int init_dir(struct inode * inode
 	return 0;
 }
 
+static int init_file(struct inode * inode)
+{
+	inode->i_size = PAGE_SIZE;
+	inode->i_fop = &sysfs_file_operations;
+	return 0;
+}
+
+static int init_symlink(struct inode * inode)
+{
+	inode->i_op = &sysfs_symlink_inode_operations;
+	return 0;
+}
 
 static int create_dir(struct kobject * k, struct dentry * p,
 		      const char * n, struct dentry ** d)

@@ -91,8 +105,11 @@ static int create_dir(struct kobject * k
 		if (!error) {
 			error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
 						SYSFS_DIR);
-			if (!error)
+			if (!error) {
 				p->d_inode->i_nlink++;
+				(*d)->d_op = &sysfs_dentry_ops;
+				d_rehash(*d);
+			}
 		}
 		if (error)
 			d_drop(*d);

@@ -136,6 +153,82 @@ int sysfs_create_dir(struct kobject * ko
 	return error;
 }
 
+/* attaches attribute's sysfs_dirent to the dentry corresponding to the
+ * attribute file
+ */
+static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
+{
+	struct attribute * attr = NULL;
+	struct bin_attribute * bin_attr = NULL;
+	int (* init) (struct inode *) = NULL;
+	int error = 0;
+
+        if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
+                bin_attr = sd->s_element;
+                attr = &bin_attr->attr;
+        } else {
+                attr = sd->s_element;
+                init = init_file;
+        }
+
+	error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
+	if (error)
+		return error;
+
+        if (bin_attr) {
+		dentry->d_inode->i_size = bin_attr->size;
+		dentry->d_inode->i_fop = &bin_fops;
+	}
+	dentry->d_op = &sysfs_dentry_ops;
+	dentry->d_fsdata = sysfs_get(sd);
+	sd->s_dentry = dentry;
+	d_rehash(dentry);
+
+	return 0;
+}
+
+static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
+{
+	int err = 0;
+
+	err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
+	if (!err) {
+		dentry->d_op = &sysfs_dentry_ops;
+		dentry->d_fsdata = sysfs_get(sd);
+		sd->s_dentry = dentry;
+		d_rehash(dentry);
+	}
+	return err;
+}
+
+struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
+				struct nameidata *nd)
+{
+	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+	struct sysfs_dirent * sd;
+	int err = 0;
+
+	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+		if (sd->s_type & SYSFS_NOT_PINNED) {
+			const unsigned char * name = sysfs_get_name(sd);
+
+			if (strcmp(name, dentry->d_name.name))
+				continue;
+
+			if (sd->s_type & SYSFS_KOBJ_LINK)
+				err = sysfs_attach_link(sd, dentry);
+			else
+				err = sysfs_attach_attr(sd, dentry);
+			break;
+		}
+	}
+
+	return ERR_PTR(err);
+}
+
+struct inode_operations sysfs_dir_inode_operations = {
+	.lookup		= sysfs_lookup,
+};
 
 static void remove_dir(struct dentry * d)
 {

@@ -219,8 +312,10 @@ int sysfs_rename_dir(struct kobject * ko
 	if (!IS_ERR(new_dentry)) {
   		if (!new_dentry->d_inode) {
 			error = kobject_set_name(kobj,new_name);
-			if (!error)
+			if (!error) {
+				d_add(new_dentry, NULL);
 				d_move(kobj->dentry, new_dentry);
+			}
 			else
 				d_drop(new_dentry);
 		} else

@@ -254,7 +349,6 @@ static int sysfs_dir_close(struct inode 
 	down(&dentry->d_inode->i_sem);
 	list_del_init(&cursor->s_sibling);
 	up(&dentry->d_inode->i_sem);
-	sysfs_put(file->private_data);
 
 	return 0;
 }

diff -puN fs/sysfs/file.c~sysfs-backing-store-stop-pinning-dentries-inodes-for-leaves fs/sysfs/file.c
@@ -9,15 +9,6 @@
 
 #include "sysfs.h"
 
-static struct file_operations sysfs_file_operations;
-
-static int init_file(struct inode * inode)
-{
-	inode->i_size = PAGE_SIZE;
-	inode->i_fop = &sysfs_file_operations;
-	return 0;
-}
-
 #define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
 #define to_sattr(a) container_of(a,struct subsys_attribute,attr)
 

@@ -337,7 +328,7 @@ static int sysfs_release(struct inode * 
 	return 0;
 }
 
-static struct file_operations sysfs_file_operations = {
+struct file_operations sysfs_file_operations = {
 	.read		= sysfs_read_file,
 	.write		= sysfs_write_file,
 	.llseek		= generic_file_llseek,

@@ -348,24 +339,14 @@ static struct file_operations sysfs_file
 
 int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
 {
-	struct dentry * dentry;
 	struct sysfs_dirent * parent_sd = dir->d_fsdata;
 	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
 	int error = 0;
 
 	down(&dir->d_inode->i_sem);
-	dentry = sysfs_get_dentry(dir,attr->name);
-	if (!IS_ERR(dentry)) {
-		error = sysfs_create(dentry, mode, init_file);
-		if (!error)
-			error = sysfs_make_dirent(parent_sd, dentry, 
-						(void *) attr, mode, type);
-		if (error)
-			d_drop(dentry);
-		dput(dentry);
-	} else
-		error = PTR_ERR(dentry);
+	error = sysfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
 	up(&dir->d_inode->i_sem);
+
 	return error;
 }
 

diff -puN fs/sysfs/bin.c~sysfs-backing-store-stop-pinning-dentries-inodes-for-leaves fs/sysfs/bin.c
@@ -141,7 +141,7 @@ static int release(struct inode * inode,
 	return 0;
 }
 
-static struct file_operations bin_fops = {
+struct file_operations bin_fops = {
 	.read		= read,
 	.write		= write,
 	.llseek		= generic_file_llseek,

@@ -158,33 +158,9 @@ static struct file_operations bin_fops =
 
 int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 {
-	struct dentry * dentry;
-	struct dentry * parent;
-	umode_t mode = (attr->attr.mode & S_IALLUGO) | S_IFREG;
-	int error = 0;
-
 	BUG_ON(!kobj || !kobj->dentry || !attr);
 
-	parent = kobj->dentry;
-
-	down(&parent->d_inode->i_sem);
-	dentry = sysfs_get_dentry(parent,attr->attr.name);
-	if (!IS_ERR(dentry)) {
-		error = sysfs_create(dentry, mode, NULL);
-		if (!error) {
-			dentry->d_inode->i_size = attr->size;
-			dentry->d_inode->i_fop = &bin_fops;
-			error = sysfs_make_dirent(parent->d_fsdata, dentry, 
-						  (void *) attr, mode, 
-						  SYSFS_KOBJ_BIN_ATTR);
-		}
-		if (error)
-			d_drop(dentry);
-		dput(dentry);
-	} else
-		error = PTR_ERR(dentry);
-	up(&parent->d_inode->i_sem);
-	return error;
+	return sysfs_add_file(kobj->dentry, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 }
 
 

diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-stop-pinning-dentries-inodes-for-leaves fs/sysfs/sysfs.h
@@ -21,6 +21,10 @@ extern int sysfs_follow_link(struct dent
 extern struct rw_semaphore sysfs_rename_sem;
 extern struct super_block * sysfs_sb;
 extern struct file_operations sysfs_dir_operations;
+extern struct file_operations sysfs_file_operations;
+extern struct file_operations bin_fops;
+extern struct inode_operations sysfs_dir_inode_operations;
+extern struct inode_operations sysfs_symlink_inode_operations;
 
 struct sysfs_symlink {
 	char * link_name;

diff -puN fs/sysfs/symlink.c~sysfs-backing-store-stop-pinning-dentries-inodes-for-leaves fs/sysfs/symlink.c
@@ -8,17 +8,11 @@
 
 #include "sysfs.h"
 
-static struct inode_operations sysfs_symlink_inode_operations = {
+struct inode_operations sysfs_symlink_inode_operations = {
 	.readlink = sysfs_readlink,
 	.follow_link = sysfs_follow_link,
 };
 
-static int init_symlink(struct inode * inode)
-{
-	inode->i_op = &sysfs_symlink_inode_operations;
-	return 0;
-}
-
 static int object_depth(struct kobject * kobj)
 {
 	struct kobject * p = kobj;

@@ -53,9 +47,9 @@ static void fill_object_path(struct kobj
 	}
 }
 
-static int sysfs_add_link(struct dentry * dentry, char * name, struct kobject * target)
+static int sysfs_add_link(struct dentry * parent, char * name, struct kobject * target)
 {
-	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+	struct sysfs_dirent * parent_sd = parent->d_fsdata;
 	struct sysfs_symlink * sl;
 	int error = 0;
 

@@ -71,7 +65,7 @@ static int sysfs_add_link(struct dentry 
 	strcpy(sl->link_name, name);
 	sl->target_kobj = kobject_get(target);
 
-	error = sysfs_make_dirent(parent_sd, dentry, sl, S_IFLNK|S_IRWXUGO, 
+	error = sysfs_make_dirent(parent_sd, NULL, sl, S_IFLNK|S_IRWXUGO, 
 				SYSFS_KOBJ_LINK);
 	if (!error)
 		return 0;

@@ -92,22 +86,12 @@ exit1:
 int sysfs_create_link(struct kobject * kobj, struct kobject * target, char * name)
 {
 	struct dentry * dentry = kobj->dentry;
-	struct dentry * d;
 	int error = 0;
 
 	BUG_ON(!kobj || !kobj->dentry || !name);
 
 	down(&dentry->d_inode->i_sem);
-	d = sysfs_get_dentry(dentry,name);
-	if (!IS_ERR(d)) {
-		error = sysfs_create(d, S_IFLNK|S_IRWXUGO, init_symlink);
-		if (!error)
-			error = sysfs_add_link(d, name, target);
-		if (error)
-			d_drop(d);
-		dput(d);
-	} else 
-		error = PTR_ERR(d);
+	error = sysfs_add_link(dentry, name, target);
 	up(&dentry->d_inode->i_sem);
 	return error;
 }

diff -puN fs/sysfs/mount.c~sysfs-backing-store-stop-pinning-dentries-inodes-for-leaves fs/sysfs/mount.c
@@ -42,7 +42,7 @@ 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_op = &sysfs_dir_inode_operations;
 		inode->i_fop = &sysfs_dir_operations;
 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
 		inode->i_nlink++;	

diff -puN include/linux/sysfs.h~sysfs-backing-store-add-sysfs_dirent include/linux/sysfs.h
@@ -9,6 +9,8 @@
 #ifndef _SYSFS_H_
 #define _SYSFS_H_
 
+#include <asm/atomic.h>
+
 struct kobject;
 struct module;
 

@@ -57,6 +59,23 @@ struct sysfs_ops {
 	ssize_t	(*store)(struct kobject *,struct attribute *,const char *, size_t);
 };
 
+struct sysfs_dirent {
+	atomic_t		s_count;
+	struct list_head	s_sibling;
+	struct list_head	s_children;
+	void 			* s_element;
+	int			s_type;
+	umode_t			s_mode;
+	struct dentry		* s_dentry;
+};
+
+#define SYSFS_ROOT		0x0001
+#define SYSFS_DIR		0x0002
+#define SYSFS_KOBJ_ATTR 	0x0004
+#define SYSFS_KOBJ_BIN_ATTR	0x0008
+#define SYSFS_KOBJ_LINK 	0x0020
+#define SYSFS_NOT_PINNED	(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
+
 #ifdef CONFIG_SYSFS
 
 extern int

135 lines not on this page · raw message

diff -puN fs/sysfs/file.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/file.c
@@ -346,19 +346,22 @@ static struct file_operations sysfs_file
 };
 
 
-int sysfs_add_file(struct dentry * dir, const struct attribute * attr)
+int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
 {
 	struct dentry * dentry;
-	int error;
+	struct sysfs_dirent * parent_sd = dir->d_fsdata;
+	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
 
 	down(&dir->d_inode->i_sem);
 	dentry = sysfs_get_dentry(dir,attr->name);
 	if (!IS_ERR(dentry)) {
-		error = sysfs_create(dentry,
-				     (attr->mode & S_IALLUGO) | S_IFREG,
-				     init_file);
+		error = sysfs_create(dentry, mode, init_file);
 		if (!error)
-			dentry->d_fsdata = (void *)attr;
+			error = sysfs_make_dirent(parent_sd, dentry, 
+						(void *) attr, mode, type);
+		if (error)
+			d_drop(dentry);
 		dput(dentry);
 	} else
 		error = PTR_ERR(dentry);

@@ -375,9 +378,10 @@ int sysfs_add_file(struct dentry * dir, 
 
 int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
 {
-	if (kobj && attr)
-		return sysfs_add_file(kobj->dentry,attr);
-	return -EINVAL;
+	BUG_ON(!kobj || !kobj->dentry || !attr);
+
+	return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
+
 }
 
 

@@ -409,7 +413,8 @@ int sysfs_update_file(struct kobject * k
 			 */
 			dput(victim);
 			res = 0;
-		}
+		} else
+			d_drop(victim);
 		
 		/**
 		 * Drop the reference acquired from sysfs_get_dentry() above.

diff -puN fs/sysfs/bin.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/bin.c
@@ -160,24 +160,26 @@ int sysfs_create_bin_file(struct kobject
 {
 	struct dentry * dentry;
 	struct dentry * parent;
+	umode_t mode = (attr->attr.mode & S_IALLUGO) | S_IFREG;
 	int error = 0;
 
-	if (!kobj || !attr)
-		return -EINVAL;
+	BUG_ON(!kobj || !kobj->dentry || !attr);
 
 	parent = kobj->dentry;
 
 	down(&parent->d_inode->i_sem);
 	dentry = sysfs_get_dentry(parent,attr->attr.name);
 	if (!IS_ERR(dentry)) {
-		dentry->d_fsdata = (void *)attr;
-		error = sysfs_create(dentry,
-				     (attr->attr.mode & S_IALLUGO) | S_IFREG,
-				     NULL);
+		error = sysfs_create(dentry, mode, NULL);
 		if (!error) {
 			dentry->d_inode->i_size = attr->size;
 			dentry->d_inode->i_fop = &bin_fops;
+			error = sysfs_make_dirent(parent->d_fsdata, dentry, 
+						  (void *) attr, mode, 
+						  SYSFS_KOBJ_BIN_ATTR);
 		}
+		if (error)
+			d_drop(dentry);
 		dput(dentry);
 	} else
 		error = PTR_ERR(dentry);

diff -puN fs/sysfs/group.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/group.c
@@ -31,7 +31,7 @@ static int create_files(struct dentry * 
 	int error = 0;
 
 	for (attr = grp->attrs; *attr && !error; attr++) {
-		error = sysfs_add_file(dir,*attr);
+		error = sysfs_add_file(dir, *attr, SYSFS_KOBJ_ATTR);
 	}
 	if (error)
 		remove_files(dir,grp);

@@ -45,6 +45,8 @@ int sysfs_create_group(struct kobject * 
 	struct dentry * dir;
 	int error;
 
+	BUG_ON(!kobj || !kobj->dentry);
+
 	if (grp->name) {
 		error = sysfs_create_subdir(kobj,grp->name,&dir);
 		if (error)

diff -puN fs/sysfs/mount.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/mount.c
@@ -22,6 +22,13 @@ static struct super_operations sysfs_ops
 	.drop_inode	= generic_delete_inode,
 };
 
+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)
 {
 	struct inode *inode;

@@ -50,6 +57,7 @@ static int sysfs_fill_super(struct super
 		iput(inode);
 		return -ENOMEM;
 	}
+	root->d_fsdata = &sysfs_root;
 	sb->s_root = root;
 	return 0;
 }

diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-add-sysfs_dirent fs/sysfs/sysfs.h
@@ -4,9 +4,11 @@ extern struct vfsmount * sysfs_mount;
 extern struct inode * sysfs_new_inode(mode_t mode);
 extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));
 
+extern int sysfs_make_dirent(struct sysfs_dirent *, struct dentry *, void *, 
+				umode_t, int);
 extern struct dentry * sysfs_get_dentry(struct dentry *, const char *);
 
-extern int sysfs_add_file(struct dentry * dir, const struct attribute * attr);
+extern int sysfs_add_file(struct dentry *, const struct attribute *, int);
 extern void sysfs_hash_and_remove(struct dentry * dir, const char * name);
 
 extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);

@@ -16,19 +18,27 @@ extern int sysfs_readlink(struct dentry 
 extern int sysfs_follow_link(struct dentry *, struct nameidata *);
 extern struct rw_semaphore sysfs_rename_sem;
 
+struct sysfs_symlink {
+	char * link_name;
+	struct kobject * target_kobj;
+};
+
 static inline struct kobject * to_kobj(struct dentry * dentry)
 {
-	return ((struct kobject *) dentry->d_fsdata);
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	return ((struct kobject *) sd->s_element);
 }
 
 static inline struct attribute * to_attr(struct dentry * dentry)
 {
-	return ((struct attribute *) dentry->d_fsdata);
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	return ((struct attribute *) sd->s_element);
 }
 
 static inline struct bin_attribute * to_bin_attr(struct dentry * dentry)
 {
-	return ((struct bin_attribute *) dentry->d_fsdata);
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	return ((struct bin_attribute *) sd->s_element);
 }
 
 static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)

@@ -36,10 +46,27 @@ static inline struct kobject *sysfs_get_
 	struct kobject * kobj = NULL;
 
 	spin_lock(&dcache_lock);
-	if (!d_unhashed(dentry))
-		kobj = kobject_get(to_kobj(dentry));
+	if (!d_unhashed(dentry)) {
+		struct sysfs_dirent * sd = dentry->d_fsdata;
+		if (sd->s_type & SYSFS_KOBJ_LINK) {
+			struct sysfs_symlink * sl = sd->s_element;
+			kobj = kobject_get(sl->target_kobj);
+		} else
+			kobj = kobject_get(sd->s_element);
+	}
 	spin_unlock(&dcache_lock);
 
 	return kobj;
 }
 
+static inline void release_sysfs_dirent(struct sysfs_dirent * sd)
+{
+	if (sd->s_type & SYSFS_KOBJ_LINK) {
+		struct sysfs_symlink * sl = sd->s_element;
+		kfree(sl->link_name);
+		kobject_put(sl->target_kobj);
+		kfree(sl);
+	}
+	kfree(sd);
+}
+

diff -puN fs/sysfs/symlink.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/symlink.c
@@ -53,6 +53,36 @@ static void fill_object_path(struct kobj
 	}
 }
 
+static int sysfs_add_link(struct dentry * dentry, char * name, struct kobject * target)
+{
+	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+	struct sysfs_symlink * sl;
+	int error = 0;
+
+	error = -ENOMEM;
+	sl = kmalloc(sizeof(*sl), GFP_KERNEL);
+	if (!sl)
+		goto exit1;
+
+	sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
+	if (!sl->link_name)
+		goto exit2;
+
+	strcpy(sl->link_name, name);
+	sl->target_kobj = kobject_get(target);
+
+	error = sysfs_make_dirent(parent_sd, dentry, sl, S_IFLNK|S_IRWXUGO, 
+				SYSFS_KOBJ_LINK);
+	if (!error)
+		return 0;
+
+	kfree(sl->link_name);
+exit2:
+	kfree(sl);
+exit1:
+	return error;
+}
+
 /**
  *	sysfs_create_link - create symlink between two objects.
  *	@kobj:	object whose directory we're creating the link in.

@@ -65,15 +95,16 @@ int sysfs_create_link(struct kobject * k
 	struct dentry * d;
 	int error = 0;
 
+	BUG_ON(!kobj || !kobj->dentry || !name);
+
 	down(&dentry->d_inode->i_sem);
 	d = sysfs_get_dentry(dentry,name);
 	if (!IS_ERR(d)) {
 		error = sysfs_create(d, S_IFLNK|S_IRWXUGO, init_symlink);
 		if (!error)
-			/* 
-			 * associate the link dentry with the target kobject 
-			 */
-			d->d_fsdata = kobject_get(target);
+			error = sysfs_add_link(d, name, target);
+		if (error)
+			d_drop(d);
 		dput(d);
 	} else 
 		error = PTR_ERR(d);

diff -puN fs/sysfs/inode.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/inode.c
@@ -11,6 +11,8 @@
 #include <linux/pagemap.h>
 #include <linux/namei.h>
 #include <linux/backing-dev.h>
+#include "sysfs.h"
+
 extern struct super_block * sysfs_sb;
 
 static struct address_space_operations sysfs_aops = {

@@ -91,6 +93,7 @@ struct dentry * sysfs_get_dentry(struct 
 void sysfs_hash_and_remove(struct dentry * dir, const char * name)
 {
 	struct dentry * victim;
+	struct sysfs_dirent * sd;
 
 	down(&dir->d_inode->i_sem);
 	victim = sysfs_get_dentry(dir,name);

@@ -101,14 +104,17 @@ void sysfs_hash_and_remove(struct dentry
 			pr_debug("sysfs: Removing %s (%d)\n", victim->d_name.name,
 				 atomic_read(&victim->d_count));
 
+			sd = victim->d_fsdata;
 			d_drop(victim);
 			/* release the target kobject in case of 
 			 * a symlink
 			 */
 			if (S_ISLNK(victim->d_inode->i_mode))
-				kobject_put(victim->d_fsdata);
+				kobject_put(sd->s_element);
+			list_del_init(&sd->s_sibling);
 			simple_unlink(dir->d_inode,victim);
-		}
+		} else
+			d_drop(victim);
 		/*
 		 * Drop reference from sysfs_get_dentry() above.
 		 */