Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

9 files changed, 2915 insertions, 0 deletions

diff --git a/fs/sysfs/Makefile b/fs/sysfs/Makefile
new file mode 100644
index 0000000..7a1ceb9
--- /dev/null
+++ b/fs/sysfs/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for the sysfs virtual filesystem
+#
+
+obj-y		:= inode.o file.o dir.o symlink.o mount.o bin.o \
+		   group.o
diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
new file mode 100644
index 0000000..f2c478c
--- /dev/null
+++ b/fs/sysfs/bin.c
@@ -0,0 +1,285 @@
+/*
+ * fs/sysfs/bin.c - sysfs binary file implementation
+ *
+ * Copyright (c) 2003 Patrick Mochel
+ * Copyright (c) 2003 Matthew Wilcox
+ * Copyright (c) 2004 Silicon Graphics, Inc.
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#undef DEBUG
+
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+
+#include <asm/uaccess.h>
+
+#include "sysfs.h"
+
+struct bin_buffer {
+	struct mutex	mutex;
+	void		*buffer;
+	int		mmapped;
+};
+
+static int
+fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
+{
+	struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	int rc;
+
+	/* need attr_sd for attr, its parent for kobj */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	rc = -EIO;
+	if (attr->read)
+		rc = attr->read(kobj, attr, buffer, off, count);
+
+	sysfs_put_active_two(attr_sd);
+
+	return rc;
+}
+
+static ssize_t
+read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
+{
+	struct bin_buffer *bb = file->private_data;
+	struct dentry *dentry = file->f_path.dentry;
+	int size = dentry->d_inode->i_size;
+	loff_t offs = *off;
+	int count = min_t(size_t, bytes, PAGE_SIZE);
+	char *temp;
+
+	if (!bytes)
+		return 0;
+
+	if (size) {
+		if (offs > size)
+			return 0;
+		if (offs + count > size)
+			count = size - offs;
+	}
+
+	temp = kmalloc(count, GFP_KERNEL);
+	if (!temp)
+		return -ENOMEM;
+
+	mutex_lock(&bb->mutex);
+
+	count = fill_read(dentry, bb->buffer, offs, count);
+	if (count < 0) {
+		mutex_unlock(&bb->mutex);
+		goto out_free;
+	}
+
+	memcpy(temp, bb->buffer, count);
+
+	mutex_unlock(&bb->mutex);
+
+	if (copy_to_user(userbuf, temp, count)) {
+		count = -EFAULT;
+		goto out_free;
+	}
+
+	pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
+
+	*off = offs + count;
+
+ out_free:
+	kfree(temp);
+	return count;
+}
+
+static int
+flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
+{
+	struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	int rc;
+
+	/* need attr_sd for attr, its parent for kobj */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	rc = -EIO;
+	if (attr->write)
+		rc = attr->write(kobj, attr, buffer, offset, count);
+
+	sysfs_put_active_two(attr_sd);
+
+	return rc;
+}
+
+static ssize_t write(struct file *file, const char __user *userbuf,
+		     size_t bytes, loff_t *off)
+{
+	struct bin_buffer *bb = file->private_data;
+	struct dentry *dentry = file->f_path.dentry;
+	int size = dentry->d_inode->i_size;
+	loff_t offs = *off;
+	int count = min_t(size_t, bytes, PAGE_SIZE);
+	char *temp;
+
+	if (!bytes)
+		return 0;
+
+	if (size) {
+		if (offs > size)
+			return 0;
+		if (offs + count > size)
+			count = size - offs;
+	}
+
+	temp = kmalloc(count, GFP_KERNEL);
+	if (!temp)
+		return -ENOMEM;
+
+	if (copy_from_user(temp, userbuf, count)) {
+		count = -EFAULT;
+		goto out_free;
+	}
+
+	mutex_lock(&bb->mutex);
+
+	memcpy(bb->buffer, temp, count);
+
+	count = flush_write(dentry, bb->buffer, offs, count);
+	mutex_unlock(&bb->mutex);
+
+	if (count > 0)
+		*off = offs + count;
+
+out_free:
+	kfree(temp);
+	return count;
+}
+
+static int mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct bin_buffer *bb = file->private_data;
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	int rc;
+
+	mutex_lock(&bb->mutex);
+
+	/* need attr_sd for attr, its parent for kobj */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	rc = -EINVAL;
+	if (attr->mmap)
+		rc = attr->mmap(kobj, attr, vma);
+
+	if (rc == 0 && !bb->mmapped)
+		bb->mmapped = 1;
+	else
+		sysfs_put_active_two(attr_sd);
+
+	mutex_unlock(&bb->mutex);
+
+	return rc;
+}
+
+static int open(struct inode * inode, struct file * file)
+{
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
+	struct bin_buffer *bb = NULL;
+	int error;
+
+	/* binary file operations requires both @sd and its parent */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	error = -EACCES;
+	if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
+		goto err_out;
+	if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
+		goto err_out;
+
+	error = -ENOMEM;
+	bb = kzalloc(sizeof(*bb), GFP_KERNEL);
+	if (!bb)
+		goto err_out;
+
+	bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!bb->buffer)
+		goto err_out;
+
+	mutex_init(&bb->mutex);
+	file->private_data = bb;
+
+	/* open succeeded, put active references */
+	sysfs_put_active_two(attr_sd);
+	return 0;
+
+ err_out:
+	sysfs_put_active_two(attr_sd);
+	kfree(bb);
+	return error;
+}
+
+static int release(struct inode * inode, struct file * file)
+{
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	struct bin_buffer *bb = file->private_data;
+
+	if (bb->mmapped)
+		sysfs_put_active_two(attr_sd);
+	kfree(bb->buffer);
+	kfree(bb);
+	return 0;
+}
+
+const struct file_operations bin_fops = {
+	.read		= read,
+	.write		= write,
+	.mmap		= mmap,
+	.llseek		= generic_file_llseek,
+	.open		= open,
+	.release	= release,
+};
+
+/**
+ *	sysfs_create_bin_file - create binary file for object.
+ *	@kobj:	object.
+ *	@attr:	attribute descriptor.
+ */
+
+int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
+{
+	BUG_ON(!kobj || !kobj->sd || !attr);
+
+	return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
+}
+
+
+/**
+ *	sysfs_remove_bin_file - remove binary file for object.
+ *	@kobj:	object.
+ *	@attr:	attribute descriptor.
+ */
+
+void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
+{
+	sysfs_hash_and_remove(kobj->sd, attr->attr.name);
+}
+
+EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
+EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
new file mode 100644
index 0000000..82d3b79
--- /dev/null
+++ b/fs/sysfs/dir.c
@@ -0,0 +1,987 @@
+/*
+ * fs/sysfs/dir.c - sysfs core and dir operation implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#undef DEBUG
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/namei.h>
+#include <linux/idr.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include "sysfs.h"
+
+DEFINE_MUTEX(sysfs_mutex);
+DEFINE_MUTEX(sysfs_rename_mutex);
+DEFINE_SPINLOCK(sysfs_assoc_lock);
+
+static DEFINE_SPINLOCK(sysfs_ino_lock);
+static DEFINE_IDA(sysfs_ino_ida);
+
+/**
+ *	sysfs_link_sibling - link sysfs_dirent into sibling list
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Link @sd into its sibling list which starts from
+ *	sd->s_parent->s_dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(sysfs_mutex)
+ */
+static void sysfs_link_sibling(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *parent_sd = sd->s_parent;
+	struct sysfs_dirent **pos;
+
+	BUG_ON(sd->s_sibling);
+
+	/* Store directory entries in order by ino.  This allows
+	 * readdir to properly restart without having to add a
+	 * cursor into the s_dir.children list.
+	 */
+	for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) {
+		if (sd->s_ino < (*pos)->s_ino)
+			break;
+	}
+	sd->s_sibling = *pos;
+	*pos = sd;
+}
+
+/**
+ *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Unlink @sd from its sibling list which starts from
+ *	sd->s_parent->s_dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(sysfs_mutex)
+ */
+static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent **pos;
+
+	for (pos = &sd->s_parent->s_dir.children; *pos;
+	     pos = &(*pos)->s_sibling) {
+		if (*pos == sd) {
+			*pos = sd->s_sibling;
+			sd->s_sibling = NULL;
+			break;
+		}
+	}
+}
+
+/**
+ *	sysfs_get_dentry - get dentry for the given sysfs_dirent
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Get dentry for @sd.  Dentry is looked up if currently not
+ *	present.  This function descends from the root looking up
+ *	dentry for each step.
+ *
+ *	LOCKING:
+ *	mutex_lock(sysfs_rename_mutex)
+ *
+ *	RETURNS:
+ *	Pointer to found dentry on success, ERR_PTR() value on error.
+ */
+struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
+{
+	struct dentry *dentry = dget(sysfs_sb->s_root);
+
+	while (dentry->d_fsdata != sd) {
+		struct sysfs_dirent *cur;
+		struct dentry *parent;
+
+		/* find the first ancestor which hasn't been looked up */
+		cur = sd;
+		while (cur->s_parent != dentry->d_fsdata)
+			cur = cur->s_parent;
+
+		/* look it up */
+		parent = dentry;
+		mutex_lock(&parent->d_inode->i_mutex);
+		dentry = lookup_one_noperm(cur->s_name, parent);
+		mutex_unlock(&parent->d_inode->i_mutex);
+		dput(parent);
+
+		if (IS_ERR(dentry))
+			break;
+	}
+	return dentry;
+}
+
+/**
+ *	sysfs_get_active - get an active reference to sysfs_dirent
+ *	@sd: sysfs_dirent to get an active reference to
+ *
+ *	Get an active reference of @sd.  This function is noop if @sd
+ *	is NULL.
+ *
+ *	RETURNS:
+ *	Pointer to @sd on success, NULL on failure.
+ */
+static struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+{
+	if (unlikely(!sd))
+		return NULL;
+
+	while (1) {
+		int v, t;
+
+		v = atomic_read(&sd->s_active);
+		if (unlikely(v < 0))
+			return NULL;
+
+		t = atomic_cmpxchg(&sd->s_active, v, v + 1);
+		if (likely(t == v))
+			return sd;
+		if (t < 0)
+			return NULL;
+
+		cpu_relax();
+	}
+}
+
+/**
+ *	sysfs_put_active - put an active reference to sysfs_dirent
+ *	@sd: sysfs_dirent to put an active reference to
+ *
+ *	Put an active reference to @sd.  This function is noop if @sd
+ *	is NULL.
+ */
+static void sysfs_put_active(struct sysfs_dirent *sd)
+{
+	struct completion *cmpl;
+	int v;
+
+	if (unlikely(!sd))
+		return;
+
+	v = atomic_dec_return(&sd->s_active);
+	if (likely(v != SD_DEACTIVATED_BIAS))
+		return;
+
+	/* atomic_dec_return() is a mb(), we'll always see the updated
+	 * sd->s_sibling.
+	 */
+	cmpl = (void *)sd->s_sibling;
+	complete(cmpl);
+}
+
+/**
+ *	sysfs_get_active_two - get active references to sysfs_dirent and parent
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Get active reference to @sd and its parent.  Parent's active
+ *	reference is grabbed first.  This function is noop if @sd is
+ *	NULL.
+ *
+ *	RETURNS:
+ *	Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
+{
+	if (sd) {
+		if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
+			return NULL;
+		if (unlikely(!sysfs_get_active(sd))) {
+			sysfs_put_active(sd->s_parent);
+			return NULL;
+		}
+	}
+	return sd;
+}
+
+/**
+ *	sysfs_put_active_two - put active references to sysfs_dirent and parent
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Put active references to @sd and its parent.  This function is
+ *	noop if @sd is NULL.
+ */
+void sysfs_put_active_two(struct sysfs_dirent *sd)
+{
+	if (sd) {
+		sysfs_put_active(sd);
+		sysfs_put_active(sd->s_parent);
+	}
+}
+
+/**
+ *	sysfs_deactivate - deactivate sysfs_dirent
+ *	@sd: sysfs_dirent to deactivate
+ *
+ *	Deny new active references and drain existing ones.
+ */
+static void sysfs_deactivate(struct sysfs_dirent *sd)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	int v;
+
+	BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
+	sd->s_sibling = (void *)&wait;
+
+	/* atomic_add_return() is a mb(), put_active() will always see
+	 * the updated sd->s_sibling.
+	 */
+	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
+
+	if (v != SD_DEACTIVATED_BIAS)
+		wait_for_completion(&wait);
+
+	sd->s_sibling = NULL;
+}
+
+static int sysfs_alloc_ino(ino_t *pino)
+{
+	int ino, rc;
+
+ retry:
+	spin_lock(&sysfs_ino_lock);
+	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+	spin_unlock(&sysfs_ino_lock);
+
+	if (rc == -EAGAIN) {
+		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
+			goto retry;
+		rc = -ENOMEM;
+	}
+
+	*pino = ino;
+	return rc;
+}
+
+static void sysfs_free_ino(ino_t ino)
+{
+	spin_lock(&sysfs_ino_lock);
+	ida_remove(&sysfs_ino_ida, ino);
+	spin_unlock(&sysfs_ino_lock);
+}
+
+void release_sysfs_dirent(struct sysfs_dirent * sd)
+{
+	struct sysfs_dirent *parent_sd;
+
+ repeat:
+	/* Moving/renaming is always done while holding reference.
+	 * sd->s_parent won't change beneath us.
+	 */
+	parent_sd = sd->s_parent;
+
+	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
+		sysfs_put(sd->s_symlink.target_sd);
+	if (sysfs_type(sd) & SYSFS_COPY_NAME)
+		kfree(sd->s_name);
+	kfree(sd->s_iattr);
+	sysfs_free_ino(sd->s_ino);
+	kmem_cache_free(sysfs_dir_cachep, sd);
+
+	sd = parent_sd;
+	if (sd && atomic_dec_and_test(&sd->s_count))
+		goto repeat;
+}
+
+static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
+{
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+
+	sysfs_put(sd);
+	iput(inode);
+}
+
+static struct dentry_operations sysfs_dentry_ops = {
+	.d_iput		= sysfs_d_iput,
+};
+
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
+{
+	char *dup_name = NULL;
+	struct sysfs_dirent *sd;
+
+	if (type & SYSFS_COPY_NAME) {
+		name = dup_name = kstrdup(name, GFP_KERNEL);
+		if (!name)
+			return NULL;
+	}
+
+	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
+	if (!sd)
+		goto err_out1;
+
+	if (sysfs_alloc_ino(&sd->s_ino))
+		goto err_out2;
+
+	atomic_set(&sd->s_count, 1);
+	atomic_set(&sd->s_active, 0);
+
+	sd->s_name = name;
+	sd->s_mode = mode;
+	sd->s_flags = type;
+
+	return sd;
+
+ err_out2:
+	kmem_cache_free(sysfs_dir_cachep, sd);
+ err_out1:
+	kfree(dup_name);
+	return NULL;
+}
+
+static int sysfs_ilookup_test(struct inode *inode, void *arg)
+{
+	struct sysfs_dirent *sd = arg;
+	return inode->i_ino == sd->s_ino;
+}
+
+/**
+ *	sysfs_addrm_start - prepare for sysfs_dirent add/remove
+ *	@acxt: pointer to sysfs_addrm_cxt to be used
+ *	@parent_sd: parent sysfs_dirent
+ *
+ *	This function is called when the caller is about to add or
+ *	remove sysfs_dirent under @parent_sd.  This function acquires
+ *	sysfs_mutex, grabs inode for @parent_sd if available and lock
+ *	i_mutex of it.  @acxt is used to keep and pass context to
+ *	other addrm functions.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).  sysfs_mutex is locked on
+ *	return.  i_mutex of parent inode is locked on return if
+ *	available.
+ */
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
+		       struct sysfs_dirent *parent_sd)
+{
+	struct inode *inode;
+
+	memset(acxt, 0, sizeof(*acxt));
+	acxt->parent_sd = parent_sd;
+
+	/* Lookup parent inode.  inode initialization is protected by
+	 * sysfs_mutex, so inode existence can be determined by
+	 * looking up inode while holding sysfs_mutex.
+	 */
+	mutex_lock(&sysfs_mutex);
+
+	inode = ilookup5(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
+			 parent_sd);
+	if (inode) {
+		WARN_ON(inode->i_state & I_NEW);
+
+		/* parent inode available */
+		acxt->parent_inode = inode;
+
+		/* sysfs_mutex is below i_mutex in lock hierarchy.
+		 * First, trylock i_mutex.  If fails, unlock
+		 * sysfs_mutex and lock them in order.
+		 */
+		if (!mutex_trylock(&inode->i_mutex)) {
+			mutex_unlock(&sysfs_mutex);
+			mutex_lock(&inode->i_mutex);
+			mutex_lock(&sysfs_mutex);
+		}
+	}
+}
+
+/**
+ *	__sysfs_add_one - add sysfs_dirent to parent without warning
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be added
+ *
+ *	Get @acxt->parent_sd and set sd->s_parent to it and increment
+ *	nlink of parent inode if @sd is a directory and link into the
+ *	children list of the parent.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ *
+ *	RETURNS:
+ *	0 on success, -EEXIST if entry with the given name already
+ *	exists.
+ */
+int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+{
+	if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
+		return -EEXIST;
+
+	sd->s_parent = sysfs_get(acxt->parent_sd);
+
+	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
+		inc_nlink(acxt->parent_inode);
+
+	acxt->cnt++;
+
+	sysfs_link_sibling(sd);
+
+	return 0;
+}
+
+/**
+ *	sysfs_add_one - add sysfs_dirent to parent
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be added
+ *
+ *	Get @acxt->parent_sd and set sd->s_parent to it and increment
+ *	nlink of parent inode if @sd is a directory and link into the
+ *	children list of the parent.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ *
+ *	RETURNS:
+ *	0 on success, -EEXIST if entry with the given name already
+ *	exists.
+ */
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+{
+	int ret;
+
+	ret = __sysfs_add_one(acxt, sd);
+	WARN(ret == -EEXIST, KERN_WARNING "sysfs: duplicate filename '%s' "
+		       "can not be created\n", sd->s_name);
+	return ret;
+}
+
+/**
+ *	sysfs_remove_one - remove sysfs_dirent from parent
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be removed
+ *
+ *	Mark @sd removed and drop nlink of parent inode if @sd is a
+ *	directory.  @sd is unlinked from the children list.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ */
+void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+{
+	BUG_ON(sd->s_flags & SYSFS_FLAG_REMOVED);
+
+	sysfs_unlink_sibling(sd);
+
+	sd->s_flags |= SYSFS_FLAG_REMOVED;
+	sd->s_sibling = acxt->removed;
+	acxt->removed = sd;
+
+	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
+		drop_nlink(acxt->parent_inode);
+
+	acxt->cnt++;
+}
+
+/**
+ *	sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
+ *	@sd: target sysfs_dirent
+ *
+ *	Drop dentry for @sd.  @sd must have been unlinked from its
+ *	parent on entry to this function such that it can't be looked
+ *	up anymore.
+ */
+static void sysfs_drop_dentry(struct sysfs_dirent *sd)
+{
+	struct inode *inode;
+	struct dentry *dentry;
+
+	inode = ilookup(sysfs_sb, sd->s_ino);
+	if (!inode)
+		return;
+
+	/* Drop any existing dentries associated with sd.
+	 *
+	 * For the dentry to be properly freed we need to grab a
+	 * reference to the dentry under the dcache lock,  unhash it,
+	 * and then put it.  The playing with the dentry count allows
+	 * dput to immediately free the dentry  if it is not in use.
+	 */
+repeat:
+	spin_lock(&dcache_lock);
+	list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+		if (d_unhashed(dentry))
+			continue;
+		dget_locked(dentry);
+		spin_lock(&dentry->d_lock);
+		__d_drop(dentry);
+		spin_unlock(&dentry->d_lock);
+		spin_unlock(&dcache_lock);
+		dput(dentry);
+		goto repeat;
+	}
+	spin_unlock(&dcache_lock);
+
+	/* adjust nlink and update timestamp */
+	mutex_lock(&inode->i_mutex);
+
+	inode->i_ctime = CURRENT_TIME;
+	drop_nlink(inode);
+	if (sysfs_type(sd) == SYSFS_DIR)
+		drop_nlink(inode);
+
+	mutex_unlock(&inode->i_mutex);
+
+	iput(inode);
+}
+
+/**
+ *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
+ *	@acxt: addrm context to finish up
+ *
+ *	Finish up sysfs_dirent add/remove.  Resources acquired by
+ *	sysfs_addrm_start() are released and removed sysfs_dirents are
+ *	cleaned up.  Timestamps on the parent inode are updated.
+ *
+ *	LOCKING:
+ *	All mutexes acquired by sysfs_addrm_start() are released.
+ */
+void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
+{
+	/* release resources acquired by sysfs_addrm_start() */
+	mutex_unlock(&sysfs_mutex);
+	if (acxt->parent_inode) {
+		struct inode *inode = acxt->parent_inode;
+
+		/* if added/removed, update timestamps on the parent */
+		if (acxt->cnt)
+			inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+
+		mutex_unlock(&inode->i_mutex);
+		iput(inode);
+	}
+
+	/* kill removed sysfs_dirents */
+	while (acxt->removed) {
+		struct sysfs_dirent *sd = acxt->removed;
+
+		acxt->removed = sd->s_sibling;
+		sd->s_sibling = NULL;
+
+		sysfs_drop_dentry(sd);
+		sysfs_deactivate(sd);
+		sysfs_put(sd);
+	}
+}
+
+/**
+ *	sysfs_find_dirent - find sysfs_dirent with the given name
+ *	@parent_sd: sysfs_dirent to search under
+ *	@name: name to look for
+ *
+ *	Look for sysfs_dirent with name @name under @parent_sd.
+ *
+ *	LOCKING:
+ *	mutex_lock(sysfs_mutex)
+ *
+ *	RETURNS:
+ *	Pointer to sysfs_dirent if found, NULL if not.
+ */
+struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
+				       const unsigned char *name)
+{
+	struct sysfs_dirent *sd;
+
+	for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling)
+		if (!strcmp(sd->s_name, name))
+			return sd;
+	return NULL;
+}
+
+/**
+ *	sysfs_get_dirent - find and get sysfs_dirent with the given name
+ *	@parent_sd: sysfs_dirent to search under
+ *	@name: name to look for
+ *
+ *	Look for sysfs_dirent with name @name under @parent_sd and get
+ *	it if found.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).  Grabs sysfs_mutex.
+ *
+ *	RETURNS:
+ *	Pointer to sysfs_dirent if found, NULL if not.
+ */
+struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+				      const unsigned char *name)
+{
+	struct sysfs_dirent *sd;
+
+	mutex_lock(&sysfs_mutex);
+	sd = sysfs_find_dirent(parent_sd, name);
+	sysfs_get(sd);
+	mutex_unlock(&sysfs_mutex);
+
+	return sd;
+}
+EXPORT_SYMBOL_GPL(sysfs_get_dirent);
+
+static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
+		      const char *name, struct sysfs_dirent **p_sd)
+{
+	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	/* allocate */
+	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
+	if (!sd)
+		return -ENOMEM;
+	sd->s_dir.kobj = kobj;
+
+	/* link in */
+	sysfs_addrm_start(&acxt, parent_sd);
+	rc = sysfs_add_one(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
+
+	if (rc == 0)
+		*p_sd = sd;
+	else
+		sysfs_put(sd);
+
+	return rc;
+}
+
+int sysfs_create_subdir(struct kobject *kobj, const char *name,
+			struct sysfs_dirent **p_sd)
+{
+	return create_dir(kobj, kobj->sd, name, p_sd);
+}
+
+/**
+ *	sysfs_create_dir - create a directory for an object.
+ *	@kobj:		object we're creating directory for. 
+ */
+int sysfs_create_dir(struct kobject * kobj)
+{
+	struct sysfs_dirent *parent_sd, *sd;
+	int error = 0;
+
+	BUG_ON(!kobj);
+
+	if (kobj->parent)
+		parent_sd = kobj->parent->sd;
+	else
+		parent_sd = &sysfs_root;
+
+	error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
+	if (!error)
+		kobj->sd = sd;
+	return error;
+}
+
+static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
+				struct nameidata *nd)
+{
+	struct dentry *ret = NULL;
+	struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
+	struct sysfs_dirent *sd;
+	struct inode *inode;
+
+	mutex_lock(&sysfs_mutex);
+
+	sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);
+
+	/* no such entry */
+	if (!sd) {
+		ret = ERR_PTR(-ENOENT);
+		goto out_unlock;
+	}
+
+	/* attach dentry and inode */
+	inode = sysfs_get_inode(sd);
+	if (!inode) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out_unlock;
+	}
+
+	/* instantiate and hash dentry */
+	dentry->d_op = &sysfs_dentry_ops;
+	dentry->d_fsdata = sysfs_get(sd);
+	d_instantiate(dentry, inode);
+	d_rehash(dentry);
+
+ out_unlock:
+	mutex_unlock(&sysfs_mutex);
+	return ret;
+}
+
+const struct inode_operations sysfs_dir_inode_operations = {
+	.lookup		= sysfs_lookup,
+	.setattr	= sysfs_setattr,
+};
+
+static void remove_dir(struct sysfs_dirent *sd)
+{
+	struct sysfs_addrm_cxt acxt;
+
+	sysfs_addrm_start(&acxt, sd->s_parent);
+	sysfs_remove_one(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
+}
+
+void sysfs_remove_subdir(struct sysfs_dirent *sd)
+{
+	remove_dir(sd);
+}
+
+
+static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent **pos;
+
+	if (!dir_sd)
+		return;
+
+	pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
+	sysfs_addrm_start(&acxt, dir_sd);
+	pos = &dir_sd->s_dir.children;
+	while (*pos) {
+		struct sysfs_dirent *sd = *pos;
+
+		if (sysfs_type(sd) != SYSFS_DIR)
+			sysfs_remove_one(&acxt, sd);
+		else
+			pos = &(*pos)->s_sibling;
+	}
+	sysfs_addrm_finish(&acxt);
+
+	remove_dir(dir_sd);
+}
+
+/**
+ *	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 sysfs_dirent *sd = kobj->sd;
+
+	spin_lock(&sysfs_assoc_lock);
+	kobj->sd = NULL;
+	spin_unlock(&sysfs_assoc_lock);
+
+	__sysfs_remove_dir(sd);
+}
+
+int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
+{
+	struct sysfs_dirent *sd = kobj->sd;
+	struct dentry *parent = NULL;
+	struct dentry *old_dentry = NULL, *new_dentry = NULL;
+	const char *dup_name = NULL;
+	int error;
+
+	mutex_lock(&sysfs_rename_mutex);
+
+	error = 0;
+	if (strcmp(sd->s_name, new_name) == 0)
+		goto out;	/* nothing to rename */
+
+	/* get the original dentry */
+	old_dentry = sysfs_get_dentry(sd);
+	if (IS_ERR(old_dentry)) {
+		error = PTR_ERR(old_dentry);
+		old_dentry = NULL;
+		goto out;
+	}
+
+	parent = old_dentry->d_parent;
+
+	/* lock parent and get dentry for new name */
+	mutex_lock(&parent->d_inode->i_mutex);
+	mutex_lock(&sysfs_mutex);
+
+	error = -EEXIST;
+	if (sysfs_find_dirent(sd->s_parent, new_name))
+		goto out_unlock;
+
+	error = -ENOMEM;
+	new_dentry = d_alloc_name(parent, new_name);
+	if (!new_dentry)
+		goto out_unlock;
+
+	/* rename sysfs_dirent */
+	error = -ENOMEM;
+	new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
+	if (!new_name)
+		goto out_unlock;
+
+	dup_name = sd->s_name;
+	sd->s_name = new_name;
+
+	/* rename */
+	d_add(new_dentry, NULL);
+	d_move(old_dentry, new_dentry);
+
+	error = 0;
+ out_unlock:
+	mutex_unlock(&sysfs_mutex);
+	mutex_unlock(&parent->d_inode->i_mutex);
+	kfree(dup_name);
+	dput(old_dentry);
+	dput(new_dentry);
+ out:
+	mutex_unlock(&sysfs_rename_mutex);
+	return error;
+}
+
+int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
+{
+	struct sysfs_dirent *sd = kobj->sd;
+	struct sysfs_dirent *new_parent_sd;
+	struct dentry *old_parent, *new_parent = NULL;
+	struct dentry *old_dentry = NULL, *new_dentry = NULL;
+	int error;
+
+	mutex_lock(&sysfs_rename_mutex);
+	BUG_ON(!sd->s_parent);
+	new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
+
+	error = 0;
+	if (sd->s_parent == new_parent_sd)
+		goto out;	/* nothing to move */
+
+	/* get dentries */
+	old_dentry = sysfs_get_dentry(sd);
+	if (IS_ERR(old_dentry)) {
+		error = PTR_ERR(old_dentry);
+		old_dentry = NULL;
+		goto out;
+	}
+	old_parent = old_dentry->d_parent;
+
+	new_parent = sysfs_get_dentry(new_parent_sd);
+	if (IS_ERR(new_parent)) {
+		error = PTR_ERR(new_parent);
+		new_parent = NULL;
+		goto out;
+	}
+
+again:
+	mutex_lock(&old_parent->d_inode->i_mutex);
+	if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
+		mutex_unlock(&old_parent->d_inode->i_mutex);
+		goto again;
+	}
+	mutex_lock(&sysfs_mutex);
+
+	error = -EEXIST;
+	if (sysfs_find_dirent(new_parent_sd, sd->s_name))
+		goto out_unlock;
+
+	error = -ENOMEM;
+	new_dentry = d_alloc_name(new_parent, sd->s_name);
+	if (!new_dentry)
+		goto out_unlock;
+
+	error = 0;
+	d_add(new_dentry, NULL);
+	d_move(old_dentry, new_dentry);
+
+	/* Remove from old parent's list and insert into new parent's list. */
+	sysfs_unlink_sibling(sd);
+	sysfs_get(new_parent_sd);
+	sysfs_put(sd->s_parent);
+	sd->s_parent = new_parent_sd;
+	sysfs_link_sibling(sd);
+
+ out_unlock:
+	mutex_unlock(&sysfs_mutex);
+	mutex_unlock(&new_parent->d_inode->i_mutex);
+	mutex_unlock(&old_parent->d_inode->i_mutex);
+ out:
+	dput(new_parent);
+	dput(old_dentry);
+	dput(new_dentry);
+	mutex_unlock(&sysfs_rename_mutex);
+	return error;
+}
+
+/* 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_path.dentry;
+	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+	struct sysfs_dirent *pos;
+	ino_t ino;
+
+	if (filp->f_pos == 0) {
+		ino = parent_sd->s_ino;
+		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
+			filp->f_pos++;
+	}
+	if (filp->f_pos == 1) {
+		if (parent_sd->s_parent)
+			ino = parent_sd->s_parent->s_ino;
+		else
+			ino = parent_sd->s_ino;
+		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
+			filp->f_pos++;
+	}
+	if ((filp->f_pos > 1) && (filp->f_pos < INT_MAX)) {
+		mutex_lock(&sysfs_mutex);
+
+		/* Skip the dentries we have already reported */
+		pos = parent_sd->s_dir.children;
+		while (pos && (filp->f_pos > pos->s_ino))
+			pos = pos->s_sibling;
+
+		for ( ; pos; pos = pos->s_sibling) {
+			const char * name;
+			int len;
+
+			name = pos->s_name;
+			len = strlen(name);
+			filp->f_pos = ino = pos->s_ino;
+
+			if (filldir(dirent, name, len, filp->f_pos, ino,
+					 dt_type(pos)) < 0)
+				break;
+		}
+		if (!pos)
+			filp->f_pos = INT_MAX;
+		mutex_unlock(&sysfs_mutex);
+	}
+	return 0;
+}
+
+
+const struct file_operations sysfs_dir_operations = {
+	.read		= generic_read_dir,
+	.readdir	= sysfs_readdir,
+	.llseek		= generic_file_llseek,
+};
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
new file mode 100644
index 0000000..1f4a3f8
--- /dev/null
+++ b/fs/sysfs/file.c
@@ -0,0 +1,725 @@
+/*
+ * fs/sysfs/file.c - sysfs regular (text) file implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/kallsyms.h>
+#include <linux/slab.h>
+#include <linux/fsnotify.h>
+#include <linux/namei.h>
+#include <linux/poll.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/limits.h>
+#include <asm/uaccess.h>
+
+#include "sysfs.h"
+
+/* used in crash dumps to help with debugging */
+static char last_sysfs_file[PATH_MAX];
+void sysfs_printk_last_file(void)
+{
+	printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file);
+}
+
+/*
+ * There's one sysfs_buffer for each open file and one
+ * sysfs_open_dirent for each sysfs_dirent with one or more open
+ * files.
+ *
+ * filp->private_data points to sysfs_buffer and
+ * sysfs_dirent->s_attr.open points to sysfs_open_dirent.  s_attr.open
+ * is protected by sysfs_open_dirent_lock.
+ */
+static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
+
+struct sysfs_open_dirent {
+	atomic_t		refcnt;
+	atomic_t		event;
+	wait_queue_head_t	poll;
+	struct list_head	buffers; /* goes through sysfs_buffer.list */
+};
+
+struct sysfs_buffer {
+	size_t			count;
+	loff_t			pos;
+	char			* page;
+	struct sysfs_ops	* ops;
+	struct mutex		mutex;
+	int			needs_read_fill;
+	int			event;
+	struct list_head	list;
+};
+
+/**
+ *	fill_read_buffer - allocate and fill buffer from object.
+ *	@dentry:	dentry pointer.
+ *	@buffer:	data buffer for file.
+ *
+ *	Allocate @buffer->page, if it hasn't been already, then call the
+ *	kobject's show() method to fill the buffer with this attribute's 
+ *	data. 
+ *	This is called only once, on the file's first read unless an error
+ *	is returned.
+ */
+static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
+{
+	struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	struct sysfs_ops * ops = buffer->ops;
+	int ret = 0;
+	ssize_t count;
+
+	if (!buffer->page)
+		buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	/* need attr_sd for attr and ops, its parent for kobj */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	buffer->event = atomic_read(&attr_sd->s_attr.open->event);
+	count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
+
+	sysfs_put_active_two(attr_sd);
+
+	/*
+	 * The code works fine with PAGE_SIZE return but it's likely to
+	 * indicate truncated result or overflow in normal use cases.
+	 */
+	if (count >= (ssize_t)PAGE_SIZE) {
+		print_symbol("fill_read_buffer: %s returned bad count\n",
+			(unsigned long)ops->show);
+		/* Try to struggle along */
+		count = PAGE_SIZE - 1;
+	}
+	if (count >= 0) {
+		buffer->needs_read_fill = 0;
+		buffer->count = count;
+	} else {
+		ret = count;
+	}
+	return ret;
+}
+
+/**
+ *	sysfs_read_file - read an attribute. 
+ *	@file:	file pointer.
+ *	@buf:	buffer to fill.
+ *	@count:	number of bytes to read.
+ *	@ppos:	starting offset in file.
+ *
+ *	Userspace wants to read an attribute file. The attribute descriptor
+ *	is in the file's ->d_fsdata. The target object is in the directory's
+ *	->d_fsdata.
+ *
+ *	We call fill_read_buffer() to allocate and fill the buffer from the
+ *	object's show() method exactly once (if the read is happening from
+ *	the beginning of the file). That should fill the entire buffer with
+ *	all the data the object has to offer for that attribute.
+ *	We then call flush_read_buffer() to copy the buffer to userspace
+ *	in the increments specified.
+ */
+
+static ssize_t
+sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct sysfs_buffer * buffer = file->private_data;
+	ssize_t retval = 0;
+
+	mutex_lock(&buffer->mutex);
+	if (buffer->needs_read_fill || *ppos == 0) {
+		retval = fill_read_buffer(file->f_path.dentry,buffer);
+		if (retval)
+			goto out;
+	}
+	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
+		 __func__, count, *ppos, buffer->page);
+	retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
+					 buffer->count);
+out:
+	mutex_unlock(&buffer->mutex);
+	return retval;
+}
+
+/**
+ *	fill_write_buffer - copy buffer from userspace.
+ *	@buffer:	data buffer for file.
+ *	@buf:		data from user.
+ *	@count:		number of bytes in @userbuf.
+ *
+ *	Allocate @buffer->page if it hasn't been already, then
+ *	copy the user-supplied buffer into it.
+ */
+
+static int 
+fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
+{
+	int error;
+
+	if (!buffer->page)
+		buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	if (count >= PAGE_SIZE)
+		count = PAGE_SIZE - 1;
+	error = copy_from_user(buffer->page,buf,count);
+	buffer->needs_read_fill = 1;
+	/* if buf is assumed to contain a string, terminate it by \0,
+	   so e.g. sscanf() can scan the string easily */
+	buffer->page[count] = 0;
+	return error ? -EFAULT : count;
+}
+
+
+/**
+ *	flush_write_buffer - push buffer to kobject.
+ *	@dentry:	dentry to the attribute
+ *	@buffer:	data buffer for file.
+ *	@count:		number of bytes
+ *
+ *	Get the correct pointers for the kobject and the attribute we're
+ *	dealing with, then call the store() method for the attribute, 
+ *	passing the buffer that we acquired in fill_write_buffer().
+ */
+
+static int
+flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
+{
+	struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	struct sysfs_ops * ops = buffer->ops;
+	int rc;
+
+	/* need attr_sd for attr and ops, its parent for kobj */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
+
+	sysfs_put_active_two(attr_sd);
+
+	return rc;
+}
+
+
+/**
+ *	sysfs_write_file - write an attribute.
+ *	@file:	file pointer
+ *	@buf:	data to write
+ *	@count:	number of bytes
+ *	@ppos:	starting offset
+ *
+ *	Similar to sysfs_read_file(), though working in the opposite direction.
+ *	We allocate and fill the data from the user in fill_write_buffer(),
+ *	then push it to the kobject in flush_write_buffer().
+ *	There is no easy way for us to know if userspace is only doing a partial
+ *	write, so we don't support them. We expect the entire buffer to come
+ *	on the first write. 
+ *	Hint: if you're writing a value, first read the file, modify only the
+ *	the value you're changing, then write entire buffer back. 
+ */
+
+static ssize_t
+sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct sysfs_buffer * buffer = file->private_data;
+	ssize_t len;
+
+	mutex_lock(&buffer->mutex);
+	len = fill_write_buffer(buffer, buf, count);
+	if (len > 0)
+		len = flush_write_buffer(file->f_path.dentry, buffer, len);
+	if (len > 0)
+		*ppos += len;
+	mutex_unlock(&buffer->mutex);
+	return len;
+}
+
+/**
+ *	sysfs_get_open_dirent - get or create sysfs_open_dirent
+ *	@sd: target sysfs_dirent
+ *	@buffer: sysfs_buffer for this instance of open
+ *
+ *	If @sd->s_attr.open exists, increment its reference count;
+ *	otherwise, create one.  @buffer is chained to the buffers
+ *	list.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
+				 struct sysfs_buffer *buffer)
+{
+	struct sysfs_open_dirent *od, *new_od = NULL;
+
+ retry:
+	spin_lock(&sysfs_open_dirent_lock);
+
+	if (!sd->s_attr.open && new_od) {
+		sd->s_attr.open = new_od;
+		new_od = NULL;
+	}
+
+	od = sd->s_attr.open;
+	if (od) {
+		atomic_inc(&od->refcnt);
+		list_add_tail(&buffer->list, &od->buffers);
+	}
+
+	spin_unlock(&sysfs_open_dirent_lock);
+
+	if (od) {
+		kfree(new_od);
+		return 0;
+	}
+
+	/* not there, initialize a new one and retry */
+	new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
+	if (!new_od)
+		return -ENOMEM;
+
+	atomic_set(&new_od->refcnt, 0);
+	atomic_set(&new_od->event, 1);
+	init_waitqueue_head(&new_od->poll);
+	INIT_LIST_HEAD(&new_od->buffers);
+	goto retry;
+}
+
+/**
+ *	sysfs_put_open_dirent - put sysfs_open_dirent
+ *	@sd: target sysfs_dirent
+ *	@buffer: associated sysfs_buffer
+ *
+ *	Put @sd->s_attr.open and unlink @buffer from the buffers list.
+ *	If reference count reaches zero, disassociate and free it.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
+				  struct sysfs_buffer *buffer)
+{
+	struct sysfs_open_dirent *od = sd->s_attr.open;
+
+	spin_lock(&sysfs_open_dirent_lock);
+
+	list_del(&buffer->list);
+	if (atomic_dec_and_test(&od->refcnt))
+		sd->s_attr.open = NULL;
+	else
+		od = NULL;
+
+	spin_unlock(&sysfs_open_dirent_lock);
+
+	kfree(od);
+}
+
+static int sysfs_open_file(struct inode *inode, struct file *file)
+{
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	struct sysfs_buffer *buffer;
+	struct sysfs_ops *ops;
+	int error = -EACCES;
+	char *p;
+
+	p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file));
+	if (p)
+		memmove(last_sysfs_file, p, strlen(p) + 1);
+
+	/* need attr_sd for attr and ops, its parent for kobj */
+	if (!sysfs_get_active_two(attr_sd))
+		return -ENODEV;
+
+	/* every kobject with an attribute needs a ktype assigned */
+	if (kobj->ktype && kobj->ktype->sysfs_ops)
+		ops = kobj->ktype->sysfs_ops;
+	else {
+		WARN(1, KERN_ERR "missing sysfs attribute operations for "
+		       "kobject: %s\n", kobject_name(kobj));
+		goto err_out;
+	}
+
+	/* File needs write support.
+	 * The inode's perms must say it's ok, 
+	 * and we must have a store method.
+	 */
+	if (file->f_mode & FMODE_WRITE) {
+		if (!(inode->i_mode & S_IWUGO) || !ops->store)
+			goto err_out;
+	}
+
+	/* File needs read support.
+	 * The inode's perms must say it's ok, and we there
+	 * must be a show method for it.
+	 */
+	if (file->f_mode & FMODE_READ) {
+		if (!(inode->i_mode & S_IRUGO) || !ops->show)
+			goto err_out;
+	}
+
+	/* No error? Great, allocate a buffer for the file, and store it
+	 * it in file->private_data for easy access.
+	 */
+	error = -ENOMEM;
+	buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
+	if (!buffer)
+		goto err_out;
+
+	mutex_init(&buffer->mutex);
+	buffer->needs_read_fill = 1;
+	buffer->ops = ops;
+	file->private_data = buffer;
+
+	/* make sure we have open dirent struct */
+	error = sysfs_get_open_dirent(attr_sd, buffer);
+	if (error)
+		goto err_free;
+
+	/* open succeeded, put active references */
+	sysfs_put_active_two(attr_sd);
+	return 0;
+
+ err_free:
+	kfree(buffer);
+ err_out:
+	sysfs_put_active_two(attr_sd);
+	return error;
+}
+
+static int sysfs_release(struct inode *inode, struct file *filp)
+{
+	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
+	struct sysfs_buffer *buffer = filp->private_data;
+
+	sysfs_put_open_dirent(sd, buffer);
+
+	if (buffer->page)
+		free_page((unsigned long)buffer->page);
+	kfree(buffer);
+
+	return 0;
+}
+
+/* Sysfs attribute files are pollable.  The idea is that you read
+ * the content and then you use 'poll' or 'select' to wait for
+ * the content to change.  When the content changes (assuming the
+ * manager for the kobject supports notification), poll will
+ * return POLLERR|POLLPRI, and select will return the fd whether
+ * it is waiting for read, write, or exceptions.
+ * Once poll/select indicates that the value has changed, you
+ * need to close and re-open the file, or seek to 0 and read again.
+ * Reminder: this only works for attributes which actively support
+ * it, and it is not possible to test an attribute from userspace
+ * to see if it supports poll (Neither 'poll' nor 'select' return
+ * an appropriate error code).  When in doubt, set a suitable timeout value.
+ */
+static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
+{
+	struct sysfs_buffer * buffer = filp->private_data;
+	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
+	struct sysfs_open_dirent *od = attr_sd->s_attr.open;
+
+	/* need parent for the kobj, grab both */
+	if (!sysfs_get_active_two(attr_sd))
+		goto trigger;
+
+	poll_wait(filp, &od->poll, wait);
+
+	sysfs_put_active_two(attr_sd);
+
+	if (buffer->event != atomic_read(&od->event))
+		goto trigger;
+
+	return 0;
+
+ trigger:
+	buffer->needs_read_fill = 1;
+	return POLLERR|POLLPRI;
+}
+
+void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+	struct sysfs_open_dirent *od;
+
+	spin_lock(&sysfs_open_dirent_lock);
+
+	od = sd->s_attr.open;
+	if (od) {
+		atomic_inc(&od->event);
+		wake_up_interruptible(&od->poll);
+	}
+
+	spin_unlock(&sysfs_open_dirent_lock);
+}
+EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
+
+void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
+{
+	struct sysfs_dirent *sd = k->sd;
+
+	mutex_lock(&sysfs_mutex);
+
+	if (sd && dir)
+		sd = sysfs_find_dirent(sd, dir);
+	if (sd && attr)
+		sd = sysfs_find_dirent(sd, attr);
+	if (sd)
+		sysfs_notify_dirent(sd);
+
+	mutex_unlock(&sysfs_mutex);
+}
+EXPORT_SYMBOL_GPL(sysfs_notify);
+
+const struct file_operations sysfs_file_operations = {
+	.read		= sysfs_read_file,
+	.write		= sysfs_write_file,
+	.llseek		= generic_file_llseek,
+	.open		= sysfs_open_file,
+	.release	= sysfs_release,
+	.poll		= sysfs_poll,
+};
+
+int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
+			const struct attribute *attr, int type, mode_t amode)
+{
+	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	sd = sysfs_new_dirent(attr->name, mode, type);
+	if (!sd)
+		return -ENOMEM;
+	sd->s_attr.attr = (void *)attr;
+
+	sysfs_addrm_start(&acxt, dir_sd);
+	rc = sysfs_add_one(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
+
+	if (rc)
+		sysfs_put(sd);
+
+	return rc;
+}
+
+
+int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
+		   int type)
+{
+	return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
+}
+
+
+/**
+ *	sysfs_create_file - create an attribute file for an object.
+ *	@kobj:	object we're creating for. 
+ *	@attr:	attribute descriptor.
+ */
+
+int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
+{
+	BUG_ON(!kobj || !kobj->sd || !attr);
+
+	return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
+
+}
+
+
+/**
+ * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ * @group: group name.
+ */
+int sysfs_add_file_to_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group)
+{
+	struct sysfs_dirent *dir_sd;
+	int error;
+
+	if (group)
+		dir_sd = sysfs_get_dirent(kobj->sd, group);
+	else
+		dir_sd = sysfs_get(kobj->sd);
+
+	if (!dir_sd)
+		return -ENOENT;
+
+	error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
+	sysfs_put(dir_sd);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
+
+/**
+ * sysfs_chmod_file - update the modified mode value on an object attribute.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ * @mode: file permissions.
+ *
+ */
+int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
+{
+	struct sysfs_dirent *victim_sd = NULL;
+	struct dentry *victim = NULL;
+	struct inode * inode;
+	struct iattr newattrs;
+	int rc;
+
+	rc = -ENOENT;
+	victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
+	if (!victim_sd)
+		goto out;
+
+	mutex_lock(&sysfs_rename_mutex);
+	victim = sysfs_get_dentry(victim_sd);
+	mutex_unlock(&sysfs_rename_mutex);
+	if (IS_ERR(victim)) {
+		rc = PTR_ERR(victim);
+		victim = NULL;
+		goto out;
+	}
+
+	inode = victim->d_inode;
+
+	mutex_lock(&inode->i_mutex);
+
+	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
+	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
+	newattrs.ia_ctime = current_fs_time(inode->i_sb);
+	rc = sysfs_setattr(victim, &newattrs);
+
+	if (rc == 0) {
+		fsnotify_change(victim, newattrs.ia_valid);
+		mutex_lock(&sysfs_mutex);
+		victim_sd->s_mode = newattrs.ia_mode;
+		mutex_unlock(&sysfs_mutex);
+	}
+
+	mutex_unlock(&inode->i_mutex);
+ out:
+	dput(victim);
+	sysfs_put(victim_sd);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(sysfs_chmod_file);
+
+
+/**
+ *	sysfs_remove_file - remove an object attribute.
+ *	@kobj:	object we're acting for.
+ *	@attr:	attribute descriptor.
+ *
+ *	Hash the attribute name and kill the victim.
+ */
+
+void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
+{
+	sysfs_hash_and_remove(kobj->sd, attr->name);
+}
+
+
+/**
+ * sysfs_remove_file_from_group - remove an attribute file from a group.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ * @group: group name.
+ */
+void sysfs_remove_file_from_group(struct kobject *kobj,
+		const struct attribute *attr, const char *group)
+{
+	struct sysfs_dirent *dir_sd;
+
+	if (group)
+		dir_sd = sysfs_get_dirent(kobj->sd, group);
+	else
+		dir_sd = sysfs_get(kobj->sd);
+	if (dir_sd) {
+		sysfs_hash_and_remove(dir_sd, attr->name);
+		sysfs_put(dir_sd);
+	}
+}
+EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
+
+struct sysfs_schedule_callback_struct {
+	struct kobject 		*kobj;
+	void			(*func)(void *);
+	void			*data;
+	struct module		*owner;
+	struct work_struct	work;
+};
+
+static void sysfs_schedule_callback_work(struct work_struct *work)
+{
+	struct sysfs_schedule_callback_struct *ss = container_of(work,
+			struct sysfs_schedule_callback_struct, work);
+
+	(ss->func)(ss->data);
+	kobject_put(ss->kobj);
+	module_put(ss->owner);
+	kfree(ss);
+}
+
+/**
+ * sysfs_schedule_callback - helper to schedule a callback for a kobject
+ * @kobj: object we're acting for.
+ * @func: callback function to invoke later.
+ * @data: argument to pass to @func.
+ * @owner: module owning the callback code
+ *
+ * sysfs attribute methods must not unregister themselves or their parent
+ * kobject (which would amount to the same thing).  Attempts to do so will
+ * deadlock, since unregistration is mutually exclusive with driver
+ * callbacks.
+ *
+ * Instead methods can call this routine, which will attempt to allocate
+ * and schedule a workqueue request to call back @func with @data as its
+ * argument in the workqueue's process context.  @kobj will be pinned
+ * until @func returns.
+ *
+ * Returns 0 if the request was submitted, -ENOMEM if storage could not
+ * be allocated, -ENODEV if a reference to @owner isn't available.
+ */
+int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
+		void *data, struct module *owner)
+{
+	struct sysfs_schedule_callback_struct *ss;
+
+	if (!try_module_get(owner))
+		return -ENODEV;
+	ss = kmalloc(sizeof(*ss), GFP_KERNEL);
+	if (!ss) {
+		module_put(owner);
+		return -ENOMEM;
+	}
+	kobject_get(kobj);
+	ss->kobj = kobj;
+	ss->func = func;
+	ss->data = data;
+	ss->owner = owner;
+	INIT_WORK(&ss->work, sysfs_schedule_callback_work);
+	schedule_work(&ss->work);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
+
+
+EXPORT_SYMBOL_GPL(sysfs_create_file);
+EXPORT_SYMBOL_GPL(sysfs_remove_file);
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
new file mode 100644
index 0000000..fe61194
--- /dev/null
+++ b/fs/sysfs/group.c
@@ -0,0 +1,154 @@
+/*
+ * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
+ *
+ * Copyright (c) 2003 Patrick Mochel
+ * Copyright (c) 2003 Open Source Development Lab
+ *
+ * This file is released undert the GPL v2. 
+ *
+ */
+
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/dcache.h>
+#include <linux/namei.h>
+#include <linux/err.h>
+#include "sysfs.h"
+
+
+static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
+			 const struct attribute_group *grp)
+{
+	struct attribute *const* attr;
+	int i;
+
+	for (i = 0, attr = grp->attrs; *attr; i++, attr++)
+		sysfs_hash_and_remove(dir_sd, (*attr)->name);
+}
+
+static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
+			const struct attribute_group *grp, int update)
+{
+	struct attribute *const* attr;
+	int error = 0, i;
+
+	for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
+		mode_t mode = 0;
+
+		/* in update mode, we're changing the permissions or
+		 * visibility.  Do this by first removing then
+		 * re-adding (if required) the file */
+		if (update)
+			sysfs_hash_and_remove(dir_sd, (*attr)->name);
+		if (grp->is_visible) {
+			mode = grp->is_visible(kobj, *attr, i);
+			if (!mode)
+				continue;
+		}
+		error = sysfs_add_file_mode(dir_sd, *attr, SYSFS_KOBJ_ATTR,
+					    (*attr)->mode | mode);
+		if (unlikely(error))
+			break;
+	}
+	if (error)
+		remove_files(dir_sd, kobj, grp);
+	return error;
+}
+
+
+static int internal_create_group(struct kobject *kobj, int update,
+				 const struct attribute_group *grp)
+{
+	struct sysfs_dirent *sd;
+	int error;
+
+	BUG_ON(!kobj || (!update && !kobj->sd));
+
+	/* Updates may happen before the object has been instantiated */
+	if (unlikely(update && !kobj->sd))
+		return -EINVAL;
+
+	if (grp->name) {
+		error = sysfs_create_subdir(kobj, grp->name, &sd);
+		if (error)
+			return error;
+	} else
+		sd = kobj->sd;
+	sysfs_get(sd);
+	error = create_files(sd, kobj, grp, update);
+	if (error) {
+		if (grp->name)
+			sysfs_remove_subdir(sd);
+	}
+	sysfs_put(sd);
+	return error;
+}
+
+/**
+ * sysfs_create_group - given a directory kobject, create an attribute group
+ * @kobj:	The kobject to create the group on
+ * @grp:	The attribute group to create
+ *
+ * This function creates a group for the first time.  It will explicitly
+ * warn and error if any of the attribute files being created already exist.
+ *
+ * Returns 0 on success or error.
+ */
+int sysfs_create_group(struct kobject *kobj,
+		       const struct attribute_group *grp)
+{
+	return internal_create_group(kobj, 0, grp);
+}
+
+/**
+ * sysfs_update_group - given a directory kobject, create an attribute group
+ * @kobj:	The kobject to create the group on
+ * @grp:	The attribute group to create
+ *
+ * This function updates an attribute group.  Unlike
+ * sysfs_create_group(), it will explicitly not warn or error if any
+ * of the attribute files being created already exist.  Furthermore,
+ * if the visibility of the files has changed through the is_visible()
+ * callback, it will update the permissions and add or remove the
+ * relevant files.
+ *
+ * The primary use for this function is to call it after making a change
+ * that affects group visibility.
+ *
+ * Returns 0 on success or error.
+ */
+int sysfs_update_group(struct kobject *kobj,
+		       const struct attribute_group *grp)
+{
+	return internal_create_group(kobj, 1, grp);
+}
+
+
+
+void sysfs_remove_group(struct kobject * kobj, 
+			const struct attribute_group * grp)
+{
+	struct sysfs_dirent *dir_sd = kobj->sd;
+	struct sysfs_dirent *sd;
+
+	if (grp->name) {
+		sd = sysfs_get_dirent(dir_sd, grp->name);
+		if (!sd) {
+			WARN(!sd, KERN_WARNING "sysfs group %p not found for "
+				"kobject '%s'\n", grp, kobject_name(kobj));
+			return;
+		}
+	} else
+		sd = sysfs_get(dir_sd);
+
+	remove_files(sd, kobj, grp);
+	if (grp->name)
+		sysfs_remove_subdir(sd);
+
+	sysfs_put(sd);
+}
+
+
+EXPORT_SYMBOL_GPL(sysfs_create_group);
+EXPORT_SYMBOL_GPL(sysfs_update_group);
+EXPORT_SYMBOL_GPL(sysfs_remove_group);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
new file mode 100644
index 0000000..eb53c63
--- /dev/null
+++ b/fs/sysfs/inode.c
@@ -0,0 +1,240 @@
+/*
+ * fs/sysfs/inode.c - basic sysfs inode and dentry operations
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#undef DEBUG 
+
+#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include "sysfs.h"
+
+extern struct super_block * sysfs_sb;
+
+static const struct address_space_operations sysfs_aops = {
+	.readpage	= simple_readpage,
+	.write_begin	= simple_write_begin,
+	.write_end	= simple_write_end,
+};
+
+static struct backing_dev_info sysfs_backing_dev_info = {
+	.ra_pages	= 0,	/* No readahead */
+	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
+static const struct inode_operations sysfs_inode_operations ={
+	.setattr	= sysfs_setattr,
+};
+
+int __init sysfs_inode_init(void)
+{
+	return bdi_init(&sysfs_backing_dev_info);
+}
+
+int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
+{
+	struct inode * inode = dentry->d_inode;
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	struct iattr * sd_iattr;
+	unsigned int ia_valid = iattr->ia_valid;
+	int error;
+
+	if (!sd)
+		return -EINVAL;
+
+	sd_iattr = sd->s_iattr;
+
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		return error;
+
+	iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
+
+	error = inode_setattr(inode, iattr);
+	if (error)
+		return error;
+
+	if (!sd_iattr) {
+		/* setting attributes for the first time, allocate now */
+		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
+		if (!sd_iattr)
+			return -ENOMEM;
+		/* assign default attributes */
+		sd_iattr->ia_mode = sd->s_mode;
+		sd_iattr->ia_uid = 0;
+		sd_iattr->ia_gid = 0;
+		sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
+		sd->s_iattr = sd_iattr;
+	}
+
+	/* attributes were changed atleast once in past */
+
+	if (ia_valid & ATTR_UID)
+		sd_iattr->ia_uid = iattr->ia_uid;
+	if (ia_valid & ATTR_GID)
+		sd_iattr->ia_gid = iattr->ia_gid;
+	if (ia_valid & ATTR_ATIME)
+		sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_MTIME)
+		sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_CTIME)
+		sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = iattr->ia_mode;
+
+		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+			mode &= ~S_ISGID;
+		sd_iattr->ia_mode = sd->s_mode = mode;
+	}
+
+	return error;
+}
+
+static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
+{
+	inode->i_mode = mode;
+	inode->i_uid = 0;
+	inode->i_gid = 0;
+	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+
+static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
+{
+	inode->i_mode = iattr->ia_mode;
+	inode->i_uid = iattr->ia_uid;
+	inode->i_gid = iattr->ia_gid;
+	inode->i_atime = iattr->ia_atime;
+	inode->i_mtime = iattr->ia_mtime;
+	inode->i_ctime = iattr->ia_ctime;
+}
+
+
+/*
+ * sysfs has a different i_mutex lock order behavior for i_mutex than other
+ * filesystems; sysfs i_mutex is called in many places with subsystem locks
+ * held. At the same time, many of the VFS locking rules do not apply to
+ * sysfs at all (cross directory rename for example). To untangle this mess
+ * (which gives false positives in lockdep), we're giving sysfs inodes their
+ * own class for i_mutex.
+ */
+static struct lock_class_key sysfs_inode_imutex_key;
+
+static int sysfs_count_nlink(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *child;
+	int nr = 0;
+
+	for (child = sd->s_dir.children; child; child = child->s_sibling)
+		if (sysfs_type(child) == SYSFS_DIR)
+			nr++;
+
+	return nr + 2;
+}
+
+static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+	struct bin_attribute *bin_attr;
+
+	inode->i_blocks = 0;
+	inode->i_mapping->a_ops = &sysfs_aops;
+	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
+	inode->i_op = &sysfs_inode_operations;
+	inode->i_ino = sd->s_ino;
+	lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
+
+	if (sd->s_iattr) {
+		/* sysfs_dirent has non-default attributes
+		 * get them for the new inode from persistent copy
+		 * in sysfs_dirent
+		 */
+		set_inode_attr(inode, sd->s_iattr);
+	} else
+		set_default_inode_attr(inode, sd->s_mode);
+
+
+	/* initialize inode according to type */
+	switch (sysfs_type(sd)) {
+	case SYSFS_DIR:
+		inode->i_op = &sysfs_dir_inode_operations;
+		inode->i_fop = &sysfs_dir_operations;
+		inode->i_nlink = sysfs_count_nlink(sd);
+		break;
+	case SYSFS_KOBJ_ATTR:
+		inode->i_size = PAGE_SIZE;
+		inode->i_fop = &sysfs_file_operations;
+		break;
+	case SYSFS_KOBJ_BIN_ATTR:
+		bin_attr = sd->s_bin_attr.bin_attr;
+		inode->i_size = bin_attr->size;
+		inode->i_fop = &bin_fops;
+		break;
+	case SYSFS_KOBJ_LINK:
+		inode->i_op = &sysfs_symlink_inode_operations;
+		break;
+	default:
+		BUG();
+	}
+
+	unlock_new_inode(inode);
+}
+
+/**
+ *	sysfs_get_inode - get inode for sysfs_dirent
+ *	@sd: sysfs_dirent to allocate inode for
+ *
+ *	Get inode for @sd.  If such inode doesn't exist, a new inode
+ *	is allocated and basics are initialized.  New inode is
+ *	returned locked.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Pointer to allocated inode on success, NULL on failure.
+ */
+struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
+{
+	struct inode *inode;
+
+	inode = iget_locked(sysfs_sb, sd->s_ino);
+	if (inode && (inode->i_state & I_NEW))
+		sysfs_init_inode(sd, inode);
+
+	return inode;
+}
+
+int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+
+	if (!dir_sd)
+		return -ENOENT;
+
+	sysfs_addrm_start(&acxt, dir_sd);
+
+	sd = sysfs_find_dirent(dir_sd, name);
+	if (sd)
+		sysfs_remove_one(&acxt, sd);
+
+	sysfs_addrm_finish(&acxt);
+
+	if (sd)
+		return 0;
+	else
+		return -ENOENT;
+}
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
new file mode 100644
index 0000000..ab343e3
--- /dev/null
+++ b/fs/sysfs/mount.c
@@ -0,0 +1,132 @@
+/*
+ * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#define DEBUG 
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include "sysfs.h"
+
+/* Random magic number */
+#define SYSFS_MAGIC 0x62656572
+
+static struct vfsmount *sysfs_mount;
+struct super_block * sysfs_sb = NULL;
+struct kmem_cache *sysfs_dir_cachep;
+
+static const struct super_operations sysfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+};
+
+struct sysfs_dirent sysfs_root = {
+	.s_name		= "",
+	.s_count	= ATOMIC_INIT(1),
+	.s_flags	= SYSFS_DIR,
+	.s_mode		= S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
+	.s_ino		= 1,
+};
+
+static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+	struct dentry *root;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = SYSFS_MAGIC;
+	sb->s_op = &sysfs_ops;
+	sb->s_time_gran = 1;
+	sysfs_sb = sb;
+
+	/* get root inode, initialize and unlock it */
+	inode = sysfs_get_inode(&sysfs_root);
+	if (!inode) {
+		pr_debug("sysfs: could not get root inode\n");
+		return -ENOMEM;
+	}
+
+	/* instantiate and link root dentry */
+	root = d_alloc_root(inode);
+	if (!root) {
+		pr_debug("%s: could not get root dentry!\n",__func__);
+		iput(inode);
+		return -ENOMEM;
+	}
+	root->d_fsdata = &sysfs_root;
+	sb->s_root = root;
+	return 0;
+}
+
+static int sysfs_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+	return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
+}
+
+static struct file_system_type sysfs_fs_type = {
+	.name		= "sysfs",
+	.get_sb		= sysfs_get_sb,
+	.kill_sb	= kill_anon_super,
+};
+
+int __init sysfs_init(void)
+{
+	int err = -ENOMEM;
+
+	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
+					      sizeof(struct sysfs_dirent),
+					      0, 0, NULL);
+	if (!sysfs_dir_cachep)
+		goto out;
+
+	err = sysfs_inode_init();
+	if (err)
+		goto out_err;
+
+	err = register_filesystem(&sysfs_fs_type);
+	if (!err) {
+		sysfs_mount = kern_mount(&sysfs_fs_type);
+		if (IS_ERR(sysfs_mount)) {
+			printk(KERN_ERR "sysfs: could not mount!\n");
+			err = PTR_ERR(sysfs_mount);
+			sysfs_mount = NULL;
+			unregister_filesystem(&sysfs_fs_type);
+			goto out_err;
+		}
+	} else
+		goto out_err;
+out:
+	return err;
+out_err:
+	kmem_cache_destroy(sysfs_dir_cachep);
+	sysfs_dir_cachep = NULL;
+	goto out;
+}
+
+#undef sysfs_get
+struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
+{
+	return __sysfs_get(sd);
+}
+EXPORT_SYMBOL_GPL(sysfs_get);
+
+#undef sysfs_put
+void sysfs_put(struct sysfs_dirent *sd)
+{
+	__sysfs_put(sd);
+}
+EXPORT_SYMBOL_GPL(sysfs_put);
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
new file mode 100644
index 0000000..a3ba217
--- /dev/null
+++ b/fs/sysfs/symlink.c
@@ -0,0 +1,216 @@
+/*
+ * fs/sysfs/symlink.c - sysfs symlink implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/namei.h>
+#include <linux/mutex.h>
+
+#include "sysfs.h"
+
+static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
+				const char *name, int warn)
+{
+	struct sysfs_dirent *parent_sd = NULL;
+	struct sysfs_dirent *target_sd = NULL;
+	struct sysfs_dirent *sd = NULL;
+	struct sysfs_addrm_cxt acxt;
+	int error;
+
+	BUG_ON(!name);
+
+	if (!kobj)
+		parent_sd = &sysfs_root;
+	else
+		parent_sd = kobj->sd;
+
+	error = -EFAULT;
+	if (!parent_sd)
+		goto out_put;
+
+	/* target->sd can go away beneath us but is protected with
+	 * sysfs_assoc_lock.  Fetch target_sd from it.
+	 */
+	spin_lock(&sysfs_assoc_lock);
+	if (target->sd)
+		target_sd = sysfs_get(target->sd);
+	spin_unlock(&sysfs_assoc_lock);
+
+	error = -ENOENT;
+	if (!target_sd)
+		goto out_put;
+
+	error = -ENOMEM;
+	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+	if (!sd)
+		goto out_put;
+
+	sd->s_symlink.target_sd = target_sd;
+	target_sd = NULL;	/* reference is now owned by the symlink */
+
+	sysfs_addrm_start(&acxt, parent_sd);
+	if (warn)
+		error = sysfs_add_one(&acxt, sd);
+	else
+		error = __sysfs_add_one(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
+
+	if (error)
+		goto out_put;
+
+	return 0;
+
+ out_put:
+	sysfs_put(target_sd);
+	sysfs_put(sd);
+	return error;
+}
+
+/**
+ *	sysfs_create_link - create symlink between two objects.
+ *	@kobj:	object whose directory we're creating the link in.
+ *	@target:	object we're pointing to.
+ *	@name:		name of the symlink.
+ */
+int sysfs_create_link(struct kobject *kobj, struct kobject *target,
+		      const char *name)
+{
+	return sysfs_do_create_link(kobj, target, name, 1);
+}
+
+/**
+ *	sysfs_create_link_nowarn - create symlink between two objects.
+ *	@kobj:	object whose directory we're creating the link in.
+ *	@target:	object we're pointing to.
+ *	@name:		name of the symlink.
+ *
+ *	This function does the same as sysf_create_link(), but it
+ *	doesn't warn if the link already exists.
+ */
+int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
+			     const char *name)
+{
+	return sysfs_do_create_link(kobj, target, name, 0);
+}
+
+/**
+ *	sysfs_remove_link - remove symlink in object's directory.
+ *	@kobj:	object we're acting for.
+ *	@name:	name of the symlink to remove.
+ */
+
+void sysfs_remove_link(struct kobject * kobj, const char * name)
+{
+	struct sysfs_dirent *parent_sd = NULL;
+
+	if (!kobj)
+		parent_sd = &sysfs_root;
+	else
+		parent_sd = kobj->sd;
+
+	sysfs_hash_and_remove(parent_sd, name);
+}
+
+static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
+				 struct sysfs_dirent *target_sd, char *path)
+{
+	struct sysfs_dirent *base, *sd;
+	char *s = path;
+	int len = 0;
+
+	/* go up to the root, stop at the base */
+	base = parent_sd;
+	while (base->s_parent) {
+		sd = target_sd->s_parent;
+		while (sd->s_parent && base != sd)
+			sd = sd->s_parent;
+
+		if (base == sd)
+			break;
+
+		strcpy(s, "../");
+		s += 3;
+		base = base->s_parent;
+	}
+
+	/* determine end of target string for reverse fillup */
+	sd = target_sd;
+	while (sd->s_parent && sd != base) {
+		len += strlen(sd->s_name) + 1;
+		sd = sd->s_parent;
+	}
+
+	/* check limits */
+	if (len < 2)
+		return -EINVAL;
+	len--;
+	if ((s - path) + len > PATH_MAX)
+		return -ENAMETOOLONG;
+
+	/* reverse fillup of target string from target to base */
+	sd = target_sd;
+	while (sd->s_parent && sd != base) {
+		int slen = strlen(sd->s_name);
+
+		len -= slen;
+		strncpy(s + len, sd->s_name, slen);
+		if (len)
+			s[--len] = '/';
+
+		sd = sd->s_parent;
+	}
+
+	return 0;
+}
+
+static int sysfs_getlink(struct dentry *dentry, char * path)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	struct sysfs_dirent *parent_sd = sd->s_parent;
+	struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
+	int error;
+
+	mutex_lock(&sysfs_mutex);
+	error = sysfs_get_target_path(parent_sd, target_sd, path);
+	mutex_unlock(&sysfs_mutex);
+
+	return error;
+}
+
+static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	int error = -ENOMEM;
+	unsigned long page = get_zeroed_page(GFP_KERNEL);
+	if (page)
+		error = sysfs_getlink(dentry, (char *) page); 
+	nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
+	return NULL;
+}
+
+static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
+{
+	char *page = nd_get_link(nd);
+	if (!IS_ERR(page))
+		free_page((unsigned long)page);
+}
+
+const struct inode_operations sysfs_symlink_inode_operations = {
+	.readlink = generic_readlink,
+	.follow_link = sysfs_follow_link,
+	.put_link = sysfs_put_link,
+};
+
+
+EXPORT_SYMBOL_GPL(sysfs_create_link);
+EXPORT_SYMBOL_GPL(sysfs_remove_link);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
new file mode 100644
index 0000000..93c6d6b
--- /dev/null
+++ b/fs/sysfs/sysfs.h
@@ -0,0 +1,170 @@
+/*
+ * fs/sysfs/sysfs.h - sysfs internal header file
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ */
+
+struct sysfs_open_dirent;
+
+/* type-specific structures for sysfs_dirent->s_* union members */
+struct sysfs_elem_dir {
+	struct kobject		*kobj;
+	/* children list starts here and goes through sd->s_sibling */
+	struct sysfs_dirent	*children;
+};
+
+struct sysfs_elem_symlink {
+	struct sysfs_dirent	*target_sd;
+};
+
+struct sysfs_elem_attr {
+	struct attribute	*attr;
+	struct sysfs_open_dirent *open;
+};
+
+struct sysfs_elem_bin_attr {
+	struct bin_attribute	*bin_attr;
+};
+
+/*
+ * sysfs_dirent - the building block of sysfs hierarchy.  Each and
+ * every sysfs node is represented by single sysfs_dirent.
+ *
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible.  Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
+struct sysfs_dirent {
+	atomic_t		s_count;
+	atomic_t		s_active;
+	struct sysfs_dirent	*s_parent;
+	struct sysfs_dirent	*s_sibling;
+	const char		*s_name;
+
+	union {
+		struct sysfs_elem_dir		s_dir;
+		struct sysfs_elem_symlink	s_symlink;
+		struct sysfs_elem_attr		s_attr;
+		struct sysfs_elem_bin_attr	s_bin_attr;
+	};
+
+	unsigned int		s_flags;
+	ino_t			s_ino;
+	umode_t			s_mode;
+	struct iattr		*s_iattr;
+};
+
+#define SD_DEACTIVATED_BIAS		INT_MIN
+
+#define SYSFS_TYPE_MASK			0x00ff
+#define SYSFS_DIR			0x0001
+#define SYSFS_KOBJ_ATTR			0x0002
+#define SYSFS_KOBJ_BIN_ATTR		0x0004
+#define SYSFS_KOBJ_LINK			0x0008
+#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
+
+#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_REMOVED		0x0200
+
+static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
+/*
+ * Context structure to be used while adding/removing nodes.
+ */
+struct sysfs_addrm_cxt {
+	struct sysfs_dirent	*parent_sd;
+	struct inode		*parent_inode;
+	struct sysfs_dirent	*removed;
+	int			cnt;
+};
+
+/*
+ * mount.c
+ */
+extern struct sysfs_dirent sysfs_root;
+extern struct super_block *sysfs_sb;
+extern struct kmem_cache *sysfs_dir_cachep;
+
+/*
+ * dir.c
+ */
+extern struct mutex sysfs_mutex;
+extern struct mutex sysfs_rename_mutex;
+extern spinlock_t sysfs_assoc_lock;
+
+extern const struct file_operations sysfs_dir_operations;
+extern const struct inode_operations sysfs_dir_inode_operations;
+
+struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
+struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
+void sysfs_put_active_two(struct sysfs_dirent *sd);
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
+		       struct sysfs_dirent *parent_sd);
+int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
+void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
+void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
+
+struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
+				       const unsigned char *name);
+struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+				      const unsigned char *name);
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
+
+void release_sysfs_dirent(struct sysfs_dirent *sd);
+
+int sysfs_create_subdir(struct kobject *kobj, const char *name,
+			struct sysfs_dirent **p_sd);
+void sysfs_remove_subdir(struct sysfs_dirent *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;
+}
+#define sysfs_get(sd) __sysfs_get(sd)
+
+static inline void __sysfs_put(struct sysfs_dirent *sd)
+{
+	if (sd && atomic_dec_and_test(&sd->s_count))
+		release_sysfs_dirent(sd);
+}
+#define sysfs_put(sd) __sysfs_put(sd)
+
+/*
+ * inode.c
+ */
+struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
+int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
+int sysfs_inode_init(void);
+
+/*
+ * file.c
+ */
+extern const struct file_operations sysfs_file_operations;
+
+int sysfs_add_file(struct sysfs_dirent *dir_sd,
+		   const struct attribute *attr, int type);
+
+int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
+			const struct attribute *attr, int type, mode_t amode);
+/*
+ * bin.c
+ */
+extern const struct file_operations bin_fops;
+
+/*
+ * symlink.c
+ */
+extern const struct inode_operations sysfs_symlink_inode_operations;