sysfs: fixup merge

fs/sysfs/Makefile

@@ -2,4 +2,4 @@
 # Makefile for the sysfs virtual filesystem
 #
 
-obj-y		:= inode.o
+obj-y		:= inode.o file.o dir.o symlink.o mount.o bin.o

fs/sysfs/bin.c

+/*
+ * bin.c - binary file operations for sysfs.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+
+#include "sysfs.h"
+
+static struct file_operations bin_fops;
+
+static int fill_read(struct file * file, struct sysfs_bin_buffer * buffer)
+{
+	struct bin_attribute * attr = file->f_dentry->d_fsdata;
+	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+
+	if (!buffer->data)
+		attr->read(kobj,buffer);
+	return buffer->size ? 0 : -ENOENT;
+}
+
+static int flush_read(struct file * file, char * userbuf, 
+		      struct sysfs_bin_buffer * buffer)
+{
+	return copy_to_user(userbuf,buffer->data + buffer->offset,buffer->count) ? 
+		-EFAULT : 0;
+}
+
+static ssize_t
+read(struct file * file, char * userbuf, size_t count, loff_t * off)
+{
+	struct sysfs_bin_buffer * buffer = file->private_data;
+	int ret;
+
+	ret = fill_read(file,buffer);
+	if (ret) 
+		goto Done;
+
+	buffer->offset = *off;
+
+	if (count > (buffer->size - *off))
+		count = buffer->size - *off;
+
+	buffer->count = count;
+
+	ret = flush_read(file,userbuf,buffer);
+	if (!ret) {
+		*off += count;
+		ret = count;
+	}
+ Done:
+	return ret;
+}
+
+int alloc_buf_data(struct sysfs_bin_buffer * buffer)
+{
+	buffer->data = kmalloc(buffer->count,GFP_KERNEL);
+	if (buffer->data) {
+		memset(buffer->data,0,buffer->count);
+		return 0;
+	} else
+		return -ENOMEM;
+}
+
+static int fill_write(struct file * file, const char * userbuf, 
+		      struct sysfs_bin_buffer * buffer)
+{
+	return copy_from_user(buffer,userbuf,buffer->count) ?
+		-EFAULT : 0;
+}
+
+static int flush_write(struct file * file, const char * userbuf, 
+		       struct sysfs_bin_buffer * buffer)
+{
+	struct bin_attribute * attr = file->f_dentry->d_fsdata;
+	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+
+	return attr->write(kobj,buffer);
+}
+
+static ssize_t write(struct file * file, const char * userbuf,
+		     size_t count, loff_t * off)
+{
+	struct sysfs_bin_buffer * buffer = file->private_data;
+	int ret;
+
+	if (count > PAGE_SIZE)
+		count = PAGE_SIZE;
+	buffer->count = count;
+
+	ret = alloc_buf_data(buffer);
+	if (ret)
+		goto Done;
+
+	ret = fill_write(file,userbuf,buffer);
+	if (ret)
+		goto Done;
+
+	ret = flush_write(file,userbuf,buffer);
+	if (ret > 0)
+		*off += count;
+ Done:
+	if (buffer->data) {
+		kfree(buffer->data);
+		buffer->data = NULL;
+	}
+	return ret;
+}
+
+static int check_perm(struct inode * inode, struct file * file)
+{
+	struct kobject * kobj = kobject_get(file->f_dentry->d_parent->d_fsdata);
+	struct bin_attribute * attr = file->f_dentry->d_fsdata;
+	struct sysfs_bin_buffer * buffer;
+	int error = 0;
+
+	if (!kobj || !attr)
+		goto Einval;
+
+	/* 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) || !attr->write)
+			goto Eaccess;
+	}
+
+	/* 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) || !attr->read)
+			goto Eaccess;
+	}
+
+	buffer = kmalloc(sizeof(struct sysfs_bin_buffer),GFP_KERNEL);
+	if (buffer) {
+		memset(buffer,0,sizeof(struct sysfs_bin_buffer));
+		file->private_data = buffer;
+	} else
+		error = -ENOMEM;
+	goto Done;
+
+ Einval:
+	error = -EINVAL;
+	goto Done;
+ Eaccess:
+	error = -EACCES;
+ Done:
+	if (error && kobj)
+		kobject_put(kobj);
+	return error;
+}
+
+static int open(struct inode * inode, struct file * file)
+{
+	return check_perm(inode,file);
+}
+
+static int release(struct inode * inode, struct file * file)
+{
+	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+	u8 * buffer = file->private_data;
+
+	if (kobj) 
+		kobject_put(kobj);
+	if (buffer)
+		kfree(buffer);
+	return 0;
+}
+
+static struct file_operations bin_fops = {
+	.read		= read,
+	.write		= write,
+	.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)
+{
+	struct dentry * dentry;
+	struct dentry * parent;
+	int error = 0;
+
+	if (!kobj || !attr)
+		return -EINVAL;
+
+	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);
+		if (!error) {
+			dentry->d_inode->i_size = attr->size;
+			dentry->d_inode->i_fop = &bin_fops;
+		}
+	} else
+		error = PTR_ERR(dentry);
+	up(&parent->d_inode->i_sem);
+	return error;
+}
+
+
+/**
+ *	sysfs_remove_bin_file - remove binary file for object.
+ *	@kobj:	object.
+ *	@attr:	attribute descriptor.
+ *
+ */
+
+int sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
+{
+	sysfs_hash_and_remove(kobj->dentry,attr->attr.name);
+}
+
+EXPORT_SYMBOL(sysfs_create_bin_file);
+EXPORT_SYMBOL(sysfs_remove_bin_file);

fs/sysfs/dir.c

+/*
+ * dir.c - Operations for sysfs directories.
+ */
+
+#undef DEBUG
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include "sysfs.h"
+
+static int init_dir(struct inode * inode)
+{
+	inode->i_op = &simple_dir_inode_operations;
+	inode->i_fop = &simple_dir_operations;
+
+	/* directory inodes start off with i_nlink == 2 (for "." entry) */
+	inode->i_nlink++;
+	return 0;
+}
+
+/**
+ *	sysfs_create_dir - create a directory for an object.
+ *	@parent:	parent parent object.
+ *	@kobj:		object we're creating directory for. 
+ */
+
+int sysfs_create_dir(struct kobject * kobj)
+{
+	struct dentry * dentry = NULL;
+	struct dentry * parent;
+	int error = 0;
+
+	if (!kobj)
+		return -EINVAL;
+
+	if (kobj->parent)
+		parent = kobj->parent->dentry;
+	else if (sysfs_mount && sysfs_mount->mnt_sb)
+		parent = sysfs_mount->mnt_sb->s_root;
+	else
+		return -EFAULT;
+
+	down(&parent->d_inode->i_sem);
+	dentry = sysfs_get_dentry(parent,kobj->name);
+	if (!IS_ERR(dentry)) {
+		dentry->d_fsdata = (void *)kobj;
+		kobj->dentry = dentry;
+		error = sysfs_create(dentry,(S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO),
+				     init_dir);
+		if (!error)
+			parent->d_inode->i_nlink++;
+	} else
+		error = PTR_ERR(dentry);
+	up(&parent->d_inode->i_sem);
+
+	return error;
+}
+
+
+
+/**
+ *	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 list_head * node, * next;
+	struct dentry * dentry = dget(kobj->dentry);
+	struct dentry * parent;
+
+	if (!dentry)
+		return;
+
+	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
+	parent = dget(dentry->d_parent);
+	down(&parent->d_inode->i_sem);
+	down(&dentry->d_inode->i_sem);
+
+	list_for_each_safe(node,next,&dentry->d_subdirs) {
+		struct dentry * d = dget(list_entry(node,struct dentry,d_child));
+		/** 
+		 * Make sure dentry is still there 
+		 */
+		pr_debug(" o %s: ",d->d_name.name);
+		if (d->d_inode) {
+
+			pr_debug("removing");
+			/**
+			 * Unlink and unhash.
+			 */
+			simple_unlink(dentry->d_inode,d);
+			d_delete(d);
+
+			/**
+			 * Drop reference from initial sysfs_get_dentry().
+			 */
+			dput(d);
+		}
+		pr_debug(" done (%d)\n",atomic_read(&d->d_count));
+		/**
+		 * drop reference from dget() above.
+		 */
+		dput(d);
+	}
+
+	up(&dentry->d_inode->i_sem);
+	d_invalidate(dentry);
+	simple_rmdir(parent->d_inode,dentry);
+	d_delete(dentry);
+
+	pr_debug(" o %s removing done (%d)\n",dentry->d_name.name,
+		 atomic_read(&dentry->d_count));
+	/**
+	 * Drop reference from initial sysfs_get_dentry().
+	 */
+	dput(dentry);
+
+	/**
+	 * Drop reference from dget() on entrance.
+	 */
+	dput(dentry);
+	up(&parent->d_inode->i_sem);
+	dput(parent);
+}
+
+
+EXPORT_SYMBOL(sysfs_create_dir);
+EXPORT_SYMBOL(sysfs_remove_dir);
+

fs/sysfs/file.c

+/*
+ * file.c - operations for regular (text) files.
+ */
+
+#include <linux/module.h>
+#include <linux/dnotify.h>
+#include <linux/kobject.h>
+
+#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)
+
+/**
+ * Subsystem file operations.
+ * These operations allow subsystems to have files that can be 
+ * read/written. 
+ */
+static ssize_t 
+subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
+{
+	struct subsystem * s = to_subsys(kobj);
+	struct subsys_attribute * sattr = to_sattr(attr);
+	ssize_t ret = 0;
+
+	if (sattr->show)
+		ret = sattr->show(s,page);
+	return ret;
+}
+
+static ssize_t 
+subsys_attr_store(struct kobject * kobj, struct attribute * attr, 
+		  const char * page, size_t count)
+{
+	struct subsystem * s = to_subsys(kobj);
+	struct subsys_attribute * sattr = to_sattr(attr);
+	ssize_t ret = 0;
+
+	if (sattr->store)
+		ret = sattr->store(s,page,count);
+	return ret;
+}
+
+static struct sysfs_ops subsys_sysfs_ops = {
+	.show	= subsys_attr_show,
+	.store	= subsys_attr_store,
+};
+
+
+struct sysfs_buffer {
+	size_t			count;
+	loff_t			pos;
+	char			* page;
+	struct sysfs_ops	* ops;
+};
+
+
+/**
+ *	fill_read_buffer - allocate and fill buffer from object.
+ *	@file:		file 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. 
+ */
+static int fill_read_buffer(struct file * file, struct sysfs_buffer * buffer)
+{
+	struct attribute * attr = file->f_dentry->d_fsdata;
+	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+	struct sysfs_ops * ops = buffer->ops;
+	int ret = 0;
+	size_t count;
+
+	if (!buffer->page)
+		buffer->page = (char *) __get_free_page(GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	count = ops->show(kobj,attr,buffer->page);
+	if (count >= 0)
+		buffer->count = count;
+	else
+		ret = count;
+	return ret;
+}
+
+
+/**
+ *	flush_read_buffer - push buffer to userspace.
+ *	@buffer:	data buffer for file.
+ *	@userbuf:	user-passed buffer.
+ *	@count:		number of bytes requested.
+ *	@ppos:		file position.
+ *
+ *	Copy the buffer we filled in fill_read_buffer() to userspace.
+ *	This is done at the reader's leisure, copying and advancing 
+ *	the amount they specify each time.
+ *	This may be called continuously until the buffer is empty.
+ */
+static int flush_read_buffer(struct sysfs_buffer * buffer, char * buf, 
+			     size_t count, loff_t * ppos)
+{
+	int error;
+
+	if (count > (buffer->count - *ppos))
+		count = buffer->count - *ppos;
+
+	error = copy_to_user(buf,buffer->page + *ppos,count);
+	if (!error)
+		*ppos += count;
+	return error ? -EFAULT : count;
+}
+
+/**
+ *	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 *buf, size_t count, loff_t *ppos)
+{
+	struct sysfs_buffer * buffer = file->private_data;
+	ssize_t retval = 0;
+
+	if (!*ppos) {
+		if ((retval = fill_read_buffer(file,buffer)))
+			return retval;
+	}
+	pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
+		 __FUNCTION__,count,*ppos,buffer->page);
+	return flush_read_buffer(buffer,buf,count,ppos);
+}
+
+
+/**
+ *	fill_write_buffer - copy buffer from userspace.
+ *	@buffer:	data buffer for file.
+ *	@userbuf:	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 * buf, size_t count)
+{
+	int error;
+
+	if (!buffer->page)
+		buffer->page = (char *)__get_free_page(GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	if (count >= PAGE_SIZE)
+		count = PAGE_SIZE - 1;
+	error = copy_from_user(buffer->page,buf,count);
+	return error ? -EFAULT : count;
+}
+
+
+/**
+ *	flush_write_buffer - push buffer to kobject.
+ *	@file:		file pointer.
+ *	@buffer:	data buffer for file.
+ *
+ *	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 file * file, 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 sysfs_ops * ops = buffer->ops;
+
+	return ops->store(kobj,attr,buffer->page,count);
+}
+
+
+/**
+ *	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 *buf, size_t count, loff_t *ppos)
+{
+	struct sysfs_buffer * buffer = file->private_data;
+
+	count = fill_write_buffer(buffer,buf,count);
+	if (count > 0)
+		count = flush_write_buffer(file,buffer,count);
+	if (count > 0)
+		*ppos += count;
+	return count;
+}
+
+static int check_perm(struct inode * inode, struct file * file)
+{
+	struct kobject * kobj = kobject_get(file->f_dentry->d_parent->d_fsdata);
+	struct attribute * attr = file->f_dentry->d_fsdata;
+	struct sysfs_buffer * buffer;
+	struct sysfs_ops * ops = NULL;
+	int error = 0;
+
+	if (!kobj || !attr)
+		goto Einval;
+
+	/* if the kobject has no ktype, then we assume that it is a subsystem
+	 * itself, and use ops for it.
+	 */
+	if (kobj->kset && kobj->kset->ktype)
+		ops = kobj->kset->ktype->sysfs_ops;
+	else if (kobj->ktype)
+		ops = kobj->ktype->sysfs_ops;
+	else
+		ops = &subsys_sysfs_ops;
+
+	/* No sysfs operations, either from having no subsystem,
+	 * or the subsystem have no operations.
+	 */
+	if (!ops)
+		goto Eaccess;
+
+	/* 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 Eaccess;
+
+	}
+
+	/* 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 Eaccess;
+	}
+
+	/* No error? Great, allocate a buffer for the file, and store it
+	 * it in file->private_data for easy access.
+	 */
+	buffer = kmalloc(sizeof(struct sysfs_buffer),GFP_KERNEL);
+	if (buffer) {
+		memset(buffer,0,sizeof(struct sysfs_buffer));
+		buffer->ops = ops;
+		file->private_data = buffer;
+	} else
+		error = -ENOMEM;
+	goto Done;
+
+ Einval:
+	error = -EINVAL;
+	goto Done;
+ Eaccess:
+	error = -EACCES;
+ Done:
+	if (error && kobj)
+		kobject_put(kobj);
+	return error;
+}
+
+static int sysfs_open_file(struct inode * inode, struct file * filp)
+{
+	return check_perm(inode,filp);
+}
+
+static int sysfs_release(struct inode * inode, struct file * filp)
+{
+	struct kobject * kobj = filp->f_dentry->d_parent->d_fsdata;
+	struct sysfs_buffer * buffer = filp->private_data;
+
+	if (kobj) 
+		kobject_put(kobj);
+
+	if (buffer) {
+		if (buffer->page)
+			free_page((unsigned long)buffer->page);
+		kfree(buffer);
+	}
+	return 0;
+}
+
+static 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,
+};
+
+/**
+ *	sysfs_create_file - create an attribute file for an object.
+ *	@kobj:	object we're creating for. 
+ *	@attr:	atrribute descriptor.
+ */
+
+int sysfs_create_file(struct kobject * kobj, struct attribute * attr)
+{
+	struct dentry * dentry;
+	struct dentry * parent;
+	int error = 0;
+
+	if (!kobj || !attr)
+		return -EINVAL;
+
+	parent = kobj->dentry;
+
+	down(&parent->d_inode->i_sem);
+	dentry = sysfs_get_dentry(parent,attr->name);
+	if (!IS_ERR(dentry)) {
+		dentry->d_fsdata = (void *)attr;
+		error = sysfs_create(dentry,(attr->mode & S_IALLUGO) | S_IFREG,init_file);
+	} else
+		error = PTR_ERR(dentry);
+	up(&parent->d_inode->i_sem);
+	return error;
+}
+
+
+/**
+ * sysfs_update_file - update the modified timestamp on an object attribute.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ *
+ * Also call dnotify for the dentry, which lots of userspace programs
+ * use.
+ */
+int sysfs_update_file(struct kobject * kobj, struct attribute * attr)
+{
+	struct dentry * dir = kobj->dentry;
+	struct dentry * victim;
+	int res = -ENOENT;
+
+	down(&dir->d_inode->i_sem);
+	victim = sysfs_get_dentry(dir, attr->name);
+	if (!IS_ERR(victim)) {
+		/* make sure dentry is really there */
+		if (victim->d_inode && 
+		    (victim->d_parent->d_inode == dir->d_inode)) {
+			victim->d_inode->i_mtime = CURRENT_TIME;
+			dnotify_parent(victim, DN_MODIFY);
+
+			/**
+			 * Drop reference from initial sysfs_get_dentry().
+			 */
+			dput(victim);
+			res = 0;
+		}
+		
+		/**
+		 * Drop the reference acquired from sysfs_get_dentry() above.
+		 */
+		dput(victim);
+	}
+	up(&dir->d_inode->i_sem);
+
+	return res;
+}
+
+
+/**
+ *	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, struct attribute * attr)
+{
+	sysfs_hash_and_remove(kobj->dentry,attr->name);
+}
+
+
+EXPORT_SYMBOL(sysfs_create_file);
+EXPORT_SYMBOL(sysfs_remove_file);
+EXPORT_SYMBOL(sysfs_update_file);
+

fs/sysfs/inode.c

 /*
- * sysfs.c - The filesystem to export kernel objects.
+ * inode.c - basic inode and dentry operations.
  *
- * Copyright (c) 2001, 2002 Patrick Mochel
- *
- *  This program is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; either version 2 of the License, or
- *  (at your option) any later version.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- *
- * This is a simple, ramfs-based filesystem, designed to export kernel 
- * objects, their attributes, and the linkgaes between each other.
+ * sysfs is Copyright (c) 2001-3 Patrick Mochel
  *
  * Please see Documentation/filesystems/sysfs.txt for more information.
  */
 
 #undef DEBUG 
 
-#include <linux/list.h>
-#include <linux/init.h>
 #include <linux/pagemap.h>
-#include <linux/stat.h>
-#include <linux/fs.h>
-#include <linux/dcache.h>
 #include <linux/namei.h>
-#include <linux/module.h>
-#include <linux/slab.h>
 #include <linux/backing-dev.h>
-#include <linux/kobject.h>
-#include <linux/mount.h>
-#include <linux/dnotify.h>
-#include <asm/uaccess.h>
-
-/* Random magic number */
-#define SYSFS_MAGIC 0x62656572
+extern struct super_block * sysfs_sb;
 
-static struct super_operations sysfs_ops;
-static struct file_operations sysfs_file_operations;
-static struct address_space_operations sysfs_aops;
-
-static struct vfsmount *sysfs_mount;
+static struct address_space_operations sysfs_aops = {
+	.readpage	= simple_readpage,
+	.prepare_write	= simple_prepare_write,
+	.commit_write	= simple_commit_write
+};
 
 static struct backing_dev_info sysfs_backing_dev_info = {
 	.ra_pages	= 0,	/* No readahead */
 	.memory_backed	= 1,	/* Does not contribute to dirty memory */
 };
 
-static struct inode *sysfs_get_inode(struct super_block *sb, int mode, int dev)
+struct inode * sysfs_new_inode(mode_t mode)
 {
-	struct inode *inode = new_inode(sb);
-
+	struct inode * inode = new_inode(sysfs_sb);
 	if (inode) {
 		inode->i_mode = mode;
 		inode->i_uid = current->fsuid;
@@ -68,471 +37,42 @@ static struct inode *sysfs_get_inode(struct super_block *sb, int mode, int dev)
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inode->i_mapping->a_ops = &sysfs_aops;
 		inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
-		switch (mode & S_IFMT) {
-		default:
-			init_special_inode(inode, mode, dev);
-			break;
-		case S_IFREG:
-			inode->i_size = PAGE_SIZE;
-			inode->i_fop = &sysfs_file_operations;
-			break;
-		case S_IFDIR:
-			inode->i_op = &simple_dir_inode_operations;
-			inode->i_fop = &simple_dir_operations;
-
-			/* directory inodes start off with i_nlink == 2 (for "." entry) */
-			inode->i_nlink++;
-			break;
-		case S_IFLNK:
-			inode->i_op = &page_symlink_inode_operations;
-			break;
-		}
 	}
 	return inode;
 }
 
-static int sysfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 {
-	struct inode *inode;
 	int error = 0;
-
+	struct inode * inode = NULL;
+	if (dentry) {
 		if (!dentry->d_inode) {
-		inode = sysfs_get_inode(dir->i_sb, mode, dev);
-		if (inode)
-			d_instantiate(dentry, inode);
+			if ((inode = sysfs_new_inode(mode)))
+				goto Proceed;
 			else 
-			error = -ENOSPC;
-	} else
+				error = -ENOMEM;
 			error = -EEXIST;
-	return error;
-}
-
-static int sysfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
-{
-	int res;
-	mode = (mode & (S_IRWXUGO|S_ISVTX)) | S_IFDIR;
- 	res = sysfs_mknod(dir, dentry, mode, 0);
- 	if (!res)
- 		dir->i_nlink++;
-	return res;
-}
-
-static int sysfs_create(struct inode *dir, struct dentry *dentry, int mode)
-{
-	int res;
-	mode = (mode & S_IALLUGO) | S_IFREG;
- 	res = sysfs_mknod(dir, dentry, mode, 0);
-	return res;
-}
-
-static int sysfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
-{
-	struct inode *inode;
-	int error = -ENOSPC;
-
-	if (dentry->d_inode)
-		return -EEXIST;
-
-	inode = sysfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
-	if (inode) {
-		int l = strlen(symname)+1;
-		error = page_symlink(inode, symname, l);
-		if (!error) {
-			d_instantiate(dentry, inode);
-			dget(dentry);
 	} else 
-			iput(inode);
-	}
-	return error;
-}
-
-#define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
-#define to_sattr(a) container_of(a,struct subsys_attribute,attr)
-
-/**
- * Subsystem file operations.
- * These operations allow subsystems to have files that can be 
- * read/written. 
- */
-static ssize_t 
-subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
-{
-	struct subsystem * s = to_subsys(kobj);
-	struct subsys_attribute * sattr = to_sattr(attr);
-	ssize_t ret = 0;
-
-	if (sattr->show)
-		ret = sattr->show(s,page);
-	return ret;
-}
-
-static ssize_t 
-subsys_attr_store(struct kobject * kobj, struct attribute * attr, 
-		  const char * page, size_t count)
-{
-	struct subsystem * s = to_subsys(kobj);
-	struct subsys_attribute * sattr = to_sattr(attr);
-	ssize_t ret = 0;
-
-	if (sattr->store)
-		ret = sattr->store(s,page,count);
-	return ret;
-}
-
-static struct sysfs_ops subsys_sysfs_ops = {
-	.show	= subsys_attr_show,
-	.store	= subsys_attr_store,
-};
-
-
-struct sysfs_buffer {
-	size_t			count;
-	loff_t			pos;
-	char			* page;
-	struct sysfs_ops	* ops;
-};
-
-
-/**
- *	fill_read_buffer - allocate and fill buffer from object.
- *	@file:		file 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. 
- */
-static int fill_read_buffer(struct file * file, struct sysfs_buffer * buffer)
-{
-	struct attribute * attr = file->f_dentry->d_fsdata;
-	struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
-	struct sysfs_ops * ops = buffer->ops;
-	int ret = 0;
-	ssize_t count;
-
-	if (!buffer->page)
-		buffer->page = (char *) __get_free_page(GFP_KERNEL);
-	if (!buffer->page)
-		return -ENOMEM;
-
-	count = ops->show(kobj,attr,buffer->page);
-	if (count >= 0)
-		buffer->count = count;
-	else
-		ret = count;
-	return ret;
-}
-
-
-/**
- *	flush_read_buffer - push buffer to userspace.
- *	@buffer:	data buffer for file.
- *	@userbuf:	user-passed buffer.
- *	@count:		number of bytes requested.
- *	@ppos:		file position.
- *
- *	Copy the buffer we filled in fill_read_buffer() to userspace.
- *	This is done at the reader's leisure, copying and advancing 
- *	the amount they specify each time.
- *	This may be called continuously until the buffer is empty.
- */
-static int flush_read_buffer(struct sysfs_buffer * buffer, char * buf, 
-			     size_t count, loff_t * ppos)
-{
-	int error;
-
-	if (count > (buffer->count - *ppos))
-		count = buffer->count - *ppos;
+		error = -ENOENT;
+	goto Done;
 
-	error = copy_to_user(buf,buffer->page + *ppos,count);
+ Proceed:
+	if (init)
+		error = init(inode);
 	if (!error)
-		*ppos += count;
-	return error ? -EFAULT : count;
-}
-
-/**
- *	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 *buf, size_t count, loff_t *ppos)
-{
-	struct sysfs_buffer * buffer = file->private_data;
-	ssize_t retval = 0;
-
-	if (!*ppos) {
-		if ((retval = fill_read_buffer(file,buffer)))
-			return retval;
-	}
-	pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
-		 __FUNCTION__,count,*ppos,buffer->page);
-	return flush_read_buffer(buffer,buf,count,ppos);
-}
-
-
-/**
- *	fill_write_buffer - copy buffer from userspace.
- *	@buffer:	data buffer for file.
- *	@userbuf:	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 * buf, size_t count)
-{
-	int error;
-
-	if (!buffer->page)
-		buffer->page = (char *)__get_free_page(GFP_KERNEL);
-	if (!buffer->page)
-		return -ENOMEM;
-
-	if (count >= PAGE_SIZE)
-		count = PAGE_SIZE - 1;
-	error = copy_from_user(buffer->page,buf,count);
-	return error ? -EFAULT : count;
-}
-
-
-/**
- *	flush_write_buffer - push buffer to kobject.
- *	@file:		file pointer.
- *	@buffer:	data buffer for file.
- *
- *	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 file * file, 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 sysfs_ops * ops = buffer->ops;
-
-	return ops->store(kobj,attr,buffer->page,count);
-}
-
-
-/**
- *	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 *buf, size_t count, loff_t *ppos)
-{
-	struct sysfs_buffer * buffer = file->private_data;
-
-	count = fill_write_buffer(buffer,buf,count);
-	if (count > 0)
-		count = flush_write_buffer(file,buffer,count);
-	if (count > 0)
-		*ppos += count;
-	return count;
-}
-
-static int check_perm(struct inode * inode, struct file * file)
-{
-	struct kobject * kobj = kobject_get(file->f_dentry->d_parent->d_fsdata);
-	struct attribute * attr = file->f_dentry->d_fsdata;
-	struct sysfs_buffer * buffer;
-	struct sysfs_ops * ops = NULL;
-	int error = 0;
-
-	if (!kobj || !attr)
-		goto Einval;
-
-	/* if the kobject has no ktype, then we assume that it is a subsystem
-	 * itself, and use ops for it.
-	 */
-	if (kobj->kset && kobj->kset->ktype)
-		ops = kobj->kset->ktype->sysfs_ops;
-	else if (kobj->ktype)
-		ops = kobj->ktype->sysfs_ops;
+		d_instantiate(dentry, inode);
 	else
-		ops = &subsys_sysfs_ops;
-
-	/* No sysfs operations, either from having no subsystem,
-	 * or the subsystem have no operations.
-	 */
-	if (!ops)
-		goto Eaccess;
-
-	/* 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 Eaccess;
-
-	}
-
-	/* 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 Eaccess;
-	}
-
-	/* No error? Great, allocate a buffer for the file, and store it
-	 * it in file->private_data for easy access.
-	 */
-	buffer = kmalloc(sizeof(struct sysfs_buffer),GFP_KERNEL);
-	if (buffer) {
-		memset(buffer,0,sizeof(struct sysfs_buffer));
-		buffer->ops = ops;
-		file->private_data = buffer;
-	} else
-		error = -ENOMEM;
-	goto Done;
-
- Einval:
-	error = -EINVAL;
-	goto Done;
- Eaccess:
-	error = -EACCES;
+		iput(inode);
  Done:
-	if (error && kobj)
-		kobject_put(kobj);
 	return error;
 }
 
-static int sysfs_open_file(struct inode * inode, struct file * filp)
-{
-	return check_perm(inode,filp);
-}
-
-static int sysfs_release(struct inode * inode, struct file * filp)
-{
-	struct kobject * kobj = filp->f_dentry->d_parent->d_fsdata;
-	struct sysfs_buffer * buffer = filp->private_data;
-
-	if (kobj) 
-		kobject_put(kobj);
-
-	if (buffer) {
-		if (buffer->page)
-			free_page((unsigned long)buffer->page);
-		kfree(buffer);
-	}
-	return 0;
-}
-
-static 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,
-};
-
-static struct address_space_operations sysfs_aops = {
-	.readpage	= simple_readpage,
-	.prepare_write	= simple_prepare_write,
-	.commit_write	= simple_commit_write
-};
-
-static struct super_operations sysfs_ops = {
-	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
-};
-
-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;
-	inode = sysfs_get_inode(sb, S_IFDIR | 0755, 0);
-
-	if (!inode) {
-		pr_debug("%s: could not get inode!\n",__FUNCTION__);
-		return -ENOMEM;
-	}
-
-	root = d_alloc_root(inode);
-	if (!root) {
-		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
-		iput(inode);
-		return -ENOMEM;
-	}
-	sb->s_root = root;
-	return 0;
-}
-
-static struct super_block *sysfs_get_sb(struct file_system_type *fs_type,
-	int flags, char *dev_name, void *data)
+int sysfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 {
-	return get_sb_single(fs_type, flags, data, sysfs_fill_super);
+	return sysfs_create(dentry, mode, NULL);
 }
 
-static struct file_system_type sysfs_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "sysfs",
-	.get_sb		= sysfs_get_sb,
-	.kill_sb	= kill_litter_super,
-};
-
-static int __init sysfs_init(void)
-{
-	int 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;
-		}
-	}
-	return err;
-}
-
-core_initcall(sysfs_init);
-
-
-static struct dentry * get_dentry(struct dentry * parent, const char * name)
+struct dentry * sysfs_get_dentry(struct dentry * parent, const char * name)
 {
 	struct qstr qstr;
 
@@ -542,157 +82,12 @@ static struct dentry * get_dentry(struct dentry * parent, const char * name)
 	return lookup_hash(&qstr,parent);
 }
 
-
-/**
- *	sysfs_create_dir - create a directory for an object.
- *	@parent:	parent parent object.
- *	@kobj:		object we're creating directory for. 
- */
-
-int sysfs_create_dir(struct kobject * kobj)
-{
-	struct dentry * dentry = NULL;
-	struct dentry * parent;
-	int error = 0;
-
-	if (!kobj)
-		return -EINVAL;
-
-	if (kobj->parent)
-		parent = kobj->parent->dentry;
-	else if (sysfs_mount && sysfs_mount->mnt_sb)
-		parent = sysfs_mount->mnt_sb->s_root;
-	else
-		return -EFAULT;
-
-	down(&parent->d_inode->i_sem);
-	dentry = get_dentry(parent,kobj->name);
-	if (!IS_ERR(dentry)) {
-		dentry->d_fsdata = (void *)kobj;
-		kobj->dentry = dentry;
-		error = sysfs_mkdir(parent->d_inode,dentry,
-				    (S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO));
-	} else
-		error = PTR_ERR(dentry);
-	up(&parent->d_inode->i_sem);
-
-	return error;
-}
-
-
-/**
- *	sysfs_create_file - create an attribute file for an object.
- *	@kobj:	object we're creating for. 
- *	@attr:	atrribute descriptor.
- */
-
-int sysfs_create_file(struct kobject * kobj, struct attribute * attr)
-{
-	struct dentry * dentry;
-	struct dentry * parent;
-	int error = 0;
-
-	if (!kobj || !attr)
-		return -EINVAL;
-
-	parent = kobj->dentry;
-
-	down(&parent->d_inode->i_sem);
-	dentry = get_dentry(parent,attr->name);
-	if (!IS_ERR(dentry)) {
-		dentry->d_fsdata = (void *)attr;
-		error = sysfs_create(parent->d_inode,dentry,attr->mode);
-	} else
-		error = PTR_ERR(dentry);
-	up(&parent->d_inode->i_sem);
-	return error;
-}
-
-
-static int object_depth(struct kobject * kobj)
-{
-	struct kobject * p = kobj;
-	int depth = 0;
-	do { depth++; } while ((p = p->parent));
-	return depth;
-}
-
-static int object_path_length(struct kobject * kobj)
-{
-	struct kobject * p = kobj;
-	int length = 1;
-	do {
-		length += strlen(p->name) + 1;
-		p = p->parent;
-	} while (p);
-	return length;
-}
-
-static void fill_object_path(struct kobject * kobj, char * buffer, int length)
-{
-	struct kobject * p;
-
-	--length;
-	for (p = kobj; p; p = p->parent) {
-		int cur = strlen(p->name);
-
-		/* back up enough to print this bus id with '/' */
-		length -= cur;
-		strncpy(buffer + length,p->name,cur);
-		*(buffer + --length) = '/';
-	}
-}
-
-/**
- *	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, char * name)
-{
-	struct dentry * dentry = kobj->dentry;
-	struct dentry * d;
-	int error = 0;
-	int size;
-	int depth;
-	char * path;
-	char * s;
-
-	depth = object_depth(kobj);
-	size = object_path_length(target) + depth * 3 - 1;
-	if (size > PATH_MAX)
-		return -ENAMETOOLONG;
-	pr_debug("%s: depth = %d, size = %d\n",__FUNCTION__,depth,size);
-
-	path = kmalloc(size,GFP_KERNEL);
-	if (!path)
-		return -ENOMEM;
-	memset(path,0,size);
-
-	for (s = path; depth--; s += 3)
-		strcpy(s,"../");
-
-	fill_object_path(target,path,size);
-	pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
-
-	down(&dentry->d_inode->i_sem);
-	d = get_dentry(dentry,name);
-	if (!IS_ERR(d))
-		error = sysfs_symlink(dentry->d_inode,d,path);
-	else
-		error = PTR_ERR(d);
-	up(&dentry->d_inode->i_sem);
-	kfree(path);
-	return error;
-}
-
-static void hash_and_remove(struct dentry * dir, const char * name)
+void sysfs_hash_and_remove(struct dentry * dir, const char * name)
 {
 	struct dentry * victim;
 
 	down(&dir->d_inode->i_sem);
-	victim = get_dentry(dir,name);
+	victim = sysfs_get_dentry(dir,name);
 	if (!IS_ERR(victim)) {
 		/* make sure dentry is really there */
 		if (victim->d_inode && 
@@ -702,156 +97,17 @@ static void hash_and_remove(struct dentry * dir, const char * name)
 
 			pr_debug("sysfs: Removing %s (%d)\n", victim->d_name.name,
 				 atomic_read(&victim->d_count));
-		}
-		
-		/**
-		 * Drop the reference acquired from get_dentry() above.
-		 */
-		dput(victim);
-	}
-	up(&dir->d_inode->i_sem);
-}
-
-/**
- * sysfs_update_file - update the modified timestamp on an object attribute.
- * @kobj: object we're acting for.
- * @attr: attribute descriptor.
- *
- * Also call dnotify for the dentry, which lots of userspace programs
- * use.
- */
-int sysfs_update_file(struct kobject * kobj, struct attribute * attr)
-{
-	struct dentry * dir = kobj->dentry;
-	struct dentry * victim;
-	int res = -ENOENT;
-
-	down(&dir->d_inode->i_sem);
-	victim = get_dentry(dir, attr->name);
-	if (!IS_ERR(victim)) {
-		/* make sure dentry is really there */
-		if (victim->d_inode && 
-		    (victim->d_parent->d_inode == dir->d_inode)) {
-			victim->d_inode->i_mtime = CURRENT_TIME;
-			dnotify_parent(victim, DN_MODIFY);
-
-			/**
-			 * Drop reference from initial get_dentry().
+			 * Drop reference from initial sysfs_get_dentry().
 			 */
 			dput(victim);
-			res = 0;
 		}
 		
 		/**
-		 * Drop the reference acquired from get_dentry() above.
+		 * Drop the reference acquired from sysfs_get_dentry() above.
 		 */
 		dput(victim);
 	}
 	up(&dir->d_inode->i_sem);
-
-	return res;
-}
-
-
-/**
- *	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, struct attribute * attr)
-{
-	hash_and_remove(kobj->dentry,attr->name);
 }
 
 
-/**
- *	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, char * name)
-{
-	hash_and_remove(kobj->dentry,name);
-}
-
-
-/**
- *	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 list_head * node;
-	struct dentry * dentry = dget(kobj->dentry);
-	struct dentry * parent;
-
-	if (!dentry)
-		return;
-
-	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
-	parent = dget(dentry->d_parent);
-	down(&parent->d_inode->i_sem);
-	down(&dentry->d_inode->i_sem);
-
-	spin_lock(&dcache_lock);
-	node = dentry->d_subdirs.next;
-	while (node != &dentry->d_subdirs) {
-		struct dentry * d = list_entry(node,struct dentry,d_child);
-		list_del_init(node);
-
-		pr_debug(" o %s (%d): ",d->d_name.name,atomic_read(&d->d_count));
-		if (d->d_inode) {
-			d = dget_locked(d);
-			pr_debug("removing");
-
-			/**
-			 * Unlink and unhash.
-			 */
-			spin_unlock(&dcache_lock);
-			d_delete(d);
-			simple_unlink(dentry->d_inode,d);
-			dput(d);
-			spin_lock(&dcache_lock);
-		}
-		pr_debug(" done\n");
-
-		node = dentry->d_subdirs.next;
-	}
-	spin_unlock(&dcache_lock);
-
-	up(&dentry->d_inode->i_sem);
-	d_invalidate(dentry);
-	simple_rmdir(parent->d_inode,dentry);
-	d_delete(dentry);
-
-	pr_debug(" o %s removing done (%d)\n",dentry->d_name.name,
-		 atomic_read(&dentry->d_count));
-	/**
-	 * Drop reference from initial get_dentry().
-	 */
-	dput(dentry);
-
-	/**
-	 * Drop reference from dget() on entrance.
-	 */
-	dput(dentry);
-	up(&parent->d_inode->i_sem);
-	dput(parent);
-}
-
-EXPORT_SYMBOL(sysfs_create_file);
-EXPORT_SYMBOL(sysfs_update_file);
-EXPORT_SYMBOL(sysfs_remove_file);
-EXPORT_SYMBOL(sysfs_create_link);
-EXPORT_SYMBOL(sysfs_remove_link);
-EXPORT_SYMBOL(sysfs_create_dir);
-EXPORT_SYMBOL(sysfs_remove_dir);

fs/sysfs/mount.c

+/*
+ * mount.c - operations for initializing and mounting sysfs.
+ */
+
+#define DEBUG 
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+
+#include "sysfs.h"
+
+/* Random magic number */
+#define SYSFS_MAGIC 0x62656572
+
+struct vfsmount *sysfs_mount;
+struct super_block * sysfs_sb = NULL;
+
+static struct super_operations sysfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+};
+
+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;
+	sysfs_sb = sb;
+
+	inode = sysfs_new_inode(S_IFDIR | S_IRUGO | S_IWUSR);
+	if (inode) {
+		inode->i_op = &simple_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+		/* directory inodes start off with i_nlink == 2 (for "." entry) */
+		inode->i_nlink++;	
+	} else {
+		pr_debug("sysfs: could not get root inode\n");
+		return -ENOMEM;
+	}
+
+	root = d_alloc_root(inode);
+	if (!root) {
+		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
+		iput(inode);
+		return -ENOMEM;
+	}
+	sb->s_root = root;
+	return 0;
+}
+
+static struct super_block *sysfs_get_sb(struct file_system_type *fs_type,
+	int flags, char *dev_name, void *data)
+{
+	return get_sb_single(fs_type, flags, data, sysfs_fill_super);
+}
+
+static struct file_system_type sysfs_fs_type = {
+	.name		= "sysfs",
+	.get_sb		= sysfs_get_sb,
+	.kill_sb	= kill_litter_super,
+};
+
+static int __init sysfs_init(void)
+{
+	int 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;
+		}
+	}
+	return err;
+}
+
+core_initcall(sysfs_init);

fs/sysfs/symlink.c

+/*
+ * symlink.c - operations for sysfs symlinks.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+
+#include "sysfs.h"
+
+
+static int init_symlink(struct inode * inode)
+{
+	inode->i_op = &page_symlink_inode_operations;
+	return 0;
+}
+
+static int sysfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
+{
+	int error;
+
+	error = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
+	if (!error) {
+		int l = strlen(symname)+1;
+		error = page_symlink(dentry->d_inode, symname, l);
+		if (error)
+			iput(dentry->d_inode);
+	}
+	return error;
+}
+
+static int object_depth(struct kobject * kobj)
+{
+	struct kobject * p = kobj;
+	int depth = 0;
+	do { depth++; } while ((p = p->parent));
+	return depth;
+}
+
+static int object_path_length(struct kobject * kobj)
+{
+	struct kobject * p = kobj;
+	int length = 1;
+	do {
+		length += strlen(p->name) + 1;
+		p = p->parent;
+	} while (p);
+	return length;
+}
+
+static void fill_object_path(struct kobject * kobj, char * buffer, int length)
+{
+	struct kobject * p;
+
+	--length;
+	for (p = kobj; p; p = p->parent) {
+		int cur = strlen(p->name);
+
+		/* back up enough to print this bus id with '/' */
+		length -= cur;
+		strncpy(buffer + length,p->name,cur);
+		*(buffer + --length) = '/';
+	}
+}
+
+/**
+ *	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, char * name)
+{
+	struct dentry * dentry = kobj->dentry;
+	struct dentry * d;
+	int error = 0;
+	int size;
+	int depth;
+	char * path;
+	char * s;
+
+	depth = object_depth(kobj);
+	size = object_path_length(target) + depth * 3 - 1;
+	if (size > PATH_MAX)
+		return -ENAMETOOLONG;
+	pr_debug("%s: depth = %d, size = %d\n",__FUNCTION__,depth,size);
+
+	path = kmalloc(size,GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+	memset(path,0,size);
+
+	for (s = path; depth--; s += 3)
+		strcpy(s,"../");
+
+	fill_object_path(target,path,size);
+	pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
+
+	down(&dentry->d_inode->i_sem);
+	d = sysfs_get_dentry(dentry,name);
+	if (!IS_ERR(d))
+		error = sysfs_symlink(dentry->d_inode,d,path);
+	else
+		error = PTR_ERR(d);
+	up(&dentry->d_inode->i_sem);
+	kfree(path);
+	return error;
+}
+
+
+/**
+ *	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, char * name)
+{
+	sysfs_hash_and_remove(kobj->dentry,name);
+}
+
+
+EXPORT_SYMBOL(sysfs_create_link);
+EXPORT_SYMBOL(sysfs_remove_link);
+

fs/sysfs/sysfs.h

+
+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 struct dentry * sysfs_get_dentry(struct dentry *, char *);
+
+extern void sysfs_hash_and_remove(struct dentry * dir, const char * name);
+

include/linux/sysfs.h

@@ -16,6 +16,20 @@ struct attribute {
 	mode_t			mode;
 };
 
+struct sysfs_bin_buffer {
+	u8 * 	data;
+	size_t	size;
+	size_t	count;
+	loff_t	offset;
+};
+
+struct bin_attribute {
+	struct attribute	attr;
+	size_t			size;
+	ssize_t (*read)(struct kobject *, struct sysfs_bin_buffer *);
+	ssize_t (*write)(struct kobject *, struct sysfs_bin_buffer *);
+};
+
 struct sysfs_ops {
 	ssize_t	(*show)(struct kobject *, struct attribute *,char *);
 	ssize_t	(*store)(struct kobject *,struct attribute *,const char *, size_t);