[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / sysfs / file.c

/*
 * file.c - operations for regular (text) files.
 */

#include <linux/module.h>
#include <linux/fsnotify.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>

#include "sysfs.h"

#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 = -EIO;

	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 = -EIO;

	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;
	struct semaphore	sem;
	int			needs_read_fill;
};


/**
 *	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. 
 */
static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
{
	struct attribute * attr = to_attr(dentry);
	struct kobject * kobj = to_kobj(dentry->d_parent);
	struct sysfs_ops * ops = buffer->ops;
	int ret = 0;
	ssize_t count;

	if (!buffer->page)
		buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
	if (!buffer->page)
		return -ENOMEM;

	count = ops->show(kobj,attr,buffer->page);
	buffer->needs_read_fill = 0;
	BUG_ON(count > (ssize_t)PAGE_SIZE);
	if (count >= 0)
		buffer->count = count;
	else
		ret = count;
	return ret;
}


/**
 *	flush_read_buffer - push buffer to userspace.
 *	@buffer:	data buffer for file.
 *	@buf:		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 __user * buf,
			     size_t count, loff_t * ppos)
{
	int error;

	if (*ppos > buffer->count)
		return 0;

	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 __user *buf, size_t count, loff_t *ppos)
{
	struct sysfs_buffer * buffer = file->private_data;
	ssize_t retval = 0;

	down(&buffer->sem);
	if (buffer->needs_read_fill) {
		if ((retval = fill_read_buffer(file->f_dentry,buffer)))
			goto out;
	}
	pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
		 __FUNCTION__,count,*ppos,buffer->page);
	retval = flush_read_buffer(buffer,buf,count,ppos);
out:
	up(&buffer->sem);
	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;
	error = copy_from_user(buffer->page,buf,count);
	buffer->needs_read_fill = 1;
	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 attribute * attr = to_attr(dentry);
	struct kobject * kobj = to_kobj(dentry->d_parent);
	struct sysfs_ops * ops = buffer->ops;

	return ops->store(kobj,attr,buffer->page,count);
}


/**
 *	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;

	down(&buffer->sem);
	len = fill_write_buffer(buffer, buf, count);
	if (len > 0)
		len = flush_write_buffer(file->f_dentry, buffer, len);
	if (len > 0)
		*ppos += len;
	up(&buffer->sem);
	return len;
}

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

	if (!kobj || !attr)
		goto Einval;

	/* Grab the module reference for this attribute if we have one */
	if (!try_module_get(attr->owner)) {
		error = -ENODEV;
		goto Done;
	}

	/* 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 = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
	if (buffer) {
		init_MUTEX(&buffer->sem);
		buffer->needs_read_fill = 1;
		buffer->ops = ops;
		file->private_data = buffer;
	} else
		error = -ENOMEM;
	goto Done;

 Einval:
	error = -EINVAL;
	goto Done;
 Eaccess:
	error = -EACCES;
	module_put(attr->owner);
 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 = to_kobj(filp->f_dentry->d_parent);
	struct attribute * attr = to_attr(filp->f_dentry);
	struct module * owner = attr->owner;
	struct sysfs_buffer * buffer = filp->private_data;

	if (kobj) 
		kobject_put(kobj);
	/* After this point, attr should not be accessed. */
	module_put(owner);

	if (buffer) {
		if (buffer->page)
			free_page((unsigned long)buffer->page);
		kfree(buffer);
	}
	return 0;
}

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,
};


int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
{
	struct sysfs_dirent * parent_sd = dir->d_fsdata;
	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
	int error = -EEXIST;

	mutex_lock(&dir->d_inode->i_mutex);
	if (!sysfs_dirent_exist(parent_sd, attr->name))
		error = sysfs_make_dirent(parent_sd, NULL, (void *)attr,
					  mode, type);
	mutex_unlock(&dir->d_inode->i_mutex);

	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, const struct attribute * attr)
{
	BUG_ON(!kobj || !kobj->dentry || !attr);

	return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);

}


/**
 * sysfs_update_file - update the modified timestamp on an object attribute.
 * @kobj: object we're acting for.
 * @attr: attribute descriptor.
 */
int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
{
	struct dentry * dir = kobj->dentry;
	struct dentry * victim;
	int res = -ENOENT;

	mutex_lock(&dir->d_inode->i_mutex);
	victim = lookup_one_len(attr->name, dir, strlen(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;
			fsnotify_modify(victim);

			/**
			 * Drop reference from initial sysfs_get_dentry().
			 */
			dput(victim);
			res = 0;
		} else
			d_drop(victim);
		
		/**
		 * Drop the reference acquired from sysfs_get_dentry() above.
		 */
		dput(victim);
	}
	mutex_unlock(&dir->d_inode->i_mutex);

	return res;
}


/**
 * 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 dentry *dir = kobj->dentry;
	struct dentry *victim;
	struct inode * inode;
	struct iattr newattrs;
	int res = -ENOENT;

	mutex_lock(&dir->d_inode->i_mutex);
	victim = lookup_one_len(attr->name, dir, strlen(attr->name));
	if (!IS_ERR(victim)) {
		if (victim->d_inode &&
		    (victim->d_parent->d_inode == dir->d_inode)) {
			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;
			res = notify_change(victim, &newattrs);
			mutex_unlock(&inode->i_mutex);
		}
		dput(victim);
	}
	mutex_unlock(&dir->d_inode->i_mutex);

	return res;
}
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->dentry,attr->name);
}


EXPORT_SYMBOL_GPL(sysfs_create_file);
EXPORT_SYMBOL_GPL(sysfs_remove_file);
EXPORT_SYMBOL_GPL(sysfs_update_file);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* file.c - operations for regular (text) files.
	3	*/
	4
	5	#include <linux/module.h>
0eeca283	6	#include <linux/fsnotify.h>
1da177e4	7	#include <linux/kobject.h>
5f45f1a7	8	#include <linux/namei.h>
1da177e4 LT	9	#include <asm/uaccess.h>
	10	#include <asm/semaphore.h>
	11
	12	#include "sysfs.h"
	13
	14	#define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
	15	#define to_sattr(a) container_of(a,struct subsys_attribute,attr)
	16
3d41088f	17	/*
1da177e4 LT	18	* Subsystem file operations.
	19	* These operations allow subsystems to have files that can be
	20	* read/written.
	21	*/
	22	static ssize_t
	23	subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
	24	{
	25	struct subsystem * s = to_subsys(kobj);
	26	struct subsys_attribute * sattr = to_sattr(attr);
c76d0abd	27	ssize_t ret = -EIO;
1da177e4 LT	28
	29	if (sattr->show)
	30	ret = sattr->show(s,page);
	31	return ret;
	32	}
	33
	34	static ssize_t
	35	subsys_attr_store(struct kobject * kobj, struct attribute * attr,
	36	const char * page, size_t count)
	37	{
	38	struct subsystem * s = to_subsys(kobj);
	39	struct subsys_attribute * sattr = to_sattr(attr);
c76d0abd	40	ssize_t ret = -EIO;
1da177e4 LT	41
	42	if (sattr->store)
	43	ret = sattr->store(s,page,count);
	44	return ret;
	45	}
	46
	47	static struct sysfs_ops subsys_sysfs_ops = {
	48	.show = subsys_attr_show,
	49	.store = subsys_attr_store,
	50	};
	51
	52
	53	struct sysfs_buffer {
	54	size_t count;
	55	loff_t pos;
	56	char * page;
	57	struct sysfs_ops * ops;
	58	struct semaphore sem;
	59	int needs_read_fill;
	60	};
	61
	62
	63	/**
	64	* fill_read_buffer - allocate and fill buffer from object.
	65	* @dentry: dentry pointer.
	66	* @buffer: data buffer for file.
	67	*
	68	* Allocate @buffer->page, if it hasn't been already, then call the
	69	* kobject's show() method to fill the buffer with this attribute's
	70	* data.
	71	* This is called only once, on the file's first read.
	72	*/
	73	static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
	74	{
	75	struct attribute * attr = to_attr(dentry);
	76	struct kobject * kobj = to_kobj(dentry->d_parent);
	77	struct sysfs_ops * ops = buffer->ops;
	78	int ret = 0;
	79	ssize_t count;
	80
	81	if (!buffer->page)
	82	buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
	83	if (!buffer->page)
	84	return -ENOMEM;
	85
	86	count = ops->show(kobj,attr,buffer->page);
	87	buffer->needs_read_fill = 0;
	88	BUG_ON(count > (ssize_t)PAGE_SIZE);
	89	if (count >= 0)
	90	buffer->count = count;
	91	else
	92	ret = count;
	93	return ret;
	94	}
	95
	96
	97	/**
	98	* flush_read_buffer - push buffer to userspace.
	99	* @buffer: data buffer for file.
67be2dd1	100	* @buf: user-passed buffer.
1da177e4 LT	101	* @count: number of bytes requested.
	102	* @ppos: file position.
	103	*
	104	* Copy the buffer we filled in fill_read_buffer() to userspace.
	105	* This is done at the reader's leisure, copying and advancing
	106	* the amount they specify each time.
	107	* This may be called continuously until the buffer is empty.
	108	*/
	109	static int flush_read_buffer(struct sysfs_buffer * buffer, char __user * buf,
	110	size_t count, loff_t * ppos)
	111	{
	112	int error;
	113
	114	if (*ppos > buffer->count)
	115	return 0;
	116
	117	if (count > (buffer->count - *ppos))
	118	count = buffer->count - *ppos;
	119
	120	error = copy_to_user(buf,buffer->page + *ppos,count);
	121	if (!error)
	122	*ppos += count;
	123	return error ? -EFAULT : count;
	124	}
	125
	126	/**
	127	* sysfs_read_file - read an attribute.
	128	* @file: file pointer.
	129	* @buf: buffer to fill.
	130	* @count: number of bytes to read.
	131	* @ppos: starting offset in file.
	132	*
	133	* Userspace wants to read an attribute file. The attribute descriptor
	134	* is in the file's ->d_fsdata. The target object is in the directory's
	135	* ->d_fsdata.
	136	*
	137	* We call fill_read_buffer() to allocate and fill the buffer from the
	138	* object's show() method exactly once (if the read is happening from
	139	* the beginning of the file). That should fill the entire buffer with
	140	* all the data the object has to offer for that attribute.
	141	* We then call flush_read_buffer() to copy the buffer to userspace
	142	* in the increments specified.
	143	*/
	144
	145	static ssize_t
	146	sysfs_read_file(struct file file, char __user buf, size_t count, loff_t *ppos)
	147	{
	148	struct sysfs_buffer * buffer = file->private_data;
	149	ssize_t retval = 0;
	150
	151	down(&buffer->sem);
	152	if (buffer->needs_read_fill) {
	153	if ((retval = fill_read_buffer(file->f_dentry,buffer)))
	154	goto out;
	155	}
	156	pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
	157	__FUNCTION__,count,*ppos,buffer->page);
	158	retval = flush_read_buffer(buffer,buf,count,ppos);
	159	out:
	160	up(&buffer->sem);
	161	return retval;
	162	}
	163
	164
165	/**
166	* fill_write_buffer - copy buffer from userspace.
167	* @buffer: data buffer for file.
67be2dd1	168	* @buf: data from user.
1da177e4 LT	169	* @count: number of bytes in @userbuf.
	170	*
	171	* Allocate @buffer->page if it hasn't been already, then
	172	* copy the user-supplied buffer into it.
	173	*/
	174
	175	static int
	176	fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
	177	{
	178	int error;
	179
	180	if (!buffer->page)
	181	buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
	182	if (!buffer->page)
	183	return -ENOMEM;
	184
	185	if (count >= PAGE_SIZE)
9d9d27fb	186	count = PAGE_SIZE;
1da177e4 LT	187	error = copy_from_user(buffer->page,buf,count);
	188	buffer->needs_read_fill = 1;
	189	return error ? -EFAULT : count;
	190	}
	191
	192
	193	/**
	194	* flush_write_buffer - push buffer to kobject.
3d41088f	195	* @dentry: dentry to the attribute
1da177e4	196	* @buffer: data buffer for file.
3d41088f	197	* @count: number of bytes
1da177e4 LT	198	*
	199	* Get the correct pointers for the kobject and the attribute we're
	200	* dealing with, then call the store() method for the attribute,
	201	* passing the buffer that we acquired in fill_write_buffer().
	202	*/
	203
	204	static int
	205	flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
	206	{
	207	struct attribute * attr = to_attr(dentry);
	208	struct kobject * kobj = to_kobj(dentry->d_parent);
	209	struct sysfs_ops * ops = buffer->ops;
	210
	211	return ops->store(kobj,attr,buffer->page,count);
	212	}
	213
	214
	215	/**
	216	* sysfs_write_file - write an attribute.
	217	* @file: file pointer
	218	* @buf: data to write
	219	* @count: number of bytes
	220	* @ppos: starting offset
	221	*
	222	* Similar to sysfs_read_file(), though working in the opposite direction.
	223	* We allocate and fill the data from the user in fill_write_buffer(),
	224	* then push it to the kobject in flush_write_buffer().
	225	* There is no easy way for us to know if userspace is only doing a partial
	226	* write, so we don't support them. We expect the entire buffer to come
	227	* on the first write.
	228	* Hint: if you're writing a value, first read the file, modify only the
	229	* the value you're changing, then write entire buffer back.
	230	*/
	231
	232	static ssize_t
	233	sysfs_write_file(struct file file, const char __user buf, size_t count, loff_t *ppos)
	234	{
	235	struct sysfs_buffer * buffer = file->private_data;
	236	ssize_t len;
	237
	238	down(&buffer->sem);
	239	len = fill_write_buffer(buffer, buf, count);
	240	if (len > 0)
	241	len = flush_write_buffer(file->f_dentry, buffer, len);
	242	if (len > 0)
	243	*ppos += len;
	244	up(&buffer->sem);
	245	return len;
	246	}
	247
	248	static int check_perm(struct inode * inode, struct file * file)
	249	{
	250	struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
	251	struct attribute * attr = to_attr(file->f_dentry);
	252	struct sysfs_buffer * buffer;
	253	struct sysfs_ops * ops = NULL;
	254	int error = 0;
	255
	256	if (!kobj \|\| !attr)
	257	goto Einval;
	258
	259	/* Grab the module reference for this attribute if we have one */
	260	if (!try_module_get(attr->owner)) {
	261	error = -ENODEV;
262	goto Done;
263	}
264
265	/* if the kobject has no ktype, then we assume that it is a subsystem
266	* itself, and use ops for it.
267	*/
268	if (kobj->kset && kobj->kset->ktype)
269	ops = kobj->kset->ktype->sysfs_ops;
270	else if (kobj->ktype)
271	ops = kobj->ktype->sysfs_ops;
272	else
273	ops = &subsys_sysfs_ops;
274
275	/* No sysfs operations, either from having no subsystem,
276	* or the subsystem have no operations.
277	*/
278	if (!ops)
279	goto Eaccess;
280
281	/* File needs write support.
282	* The inode's perms must say it's ok,
283	* and we must have a store method.
284	*/
285	if (file->f_mode & FMODE_WRITE) {
286
287	if (!(inode->i_mode & S_IWUGO) \|\| !ops->store)
288	goto Eaccess;
289
290	}
291
292	/* File needs read support.
293	* The inode's perms must say it's ok, and we there
294	* must be a show method for it.
295	*/
296	if (file->f_mode & FMODE_READ) {
297	if (!(inode->i_mode & S_IRUGO) \|\| !ops->show)
298	goto Eaccess;
299	}
300
301	/* No error? Great, allocate a buffer for the file, and store it
302	* it in file->private_data for easy access.
303	*/
58d49283	304	buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
1da177e4	305	if (buffer) {
1da177e4 LT	306	init_MUTEX(&buffer->sem);
	307	buffer->needs_read_fill = 1;
	308	buffer->ops = ops;
	309	file->private_data = buffer;
	310	} else
	311	error = -ENOMEM;
	312	goto Done;
	313
	314	Einval:
	315	error = -EINVAL;
	316	goto Done;
	317	Eaccess:
	318	error = -EACCES;
	319	module_put(attr->owner);
	320	Done:
	321	if (error && kobj)
	322	kobject_put(kobj);
	323	return error;
	324	}
	325
	326	static int sysfs_open_file(struct inode * inode, struct file * filp)
	327	{
	328	return check_perm(inode,filp);
	329	}
	330
	331	static int sysfs_release(struct inode * inode, struct file * filp)
	332	{
	333	struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
	334	struct attribute * attr = to_attr(filp->f_dentry);
	335	struct module * owner = attr->owner;
	336	struct sysfs_buffer * buffer = filp->private_data;
	337
	338	if (kobj)
	339	kobject_put(kobj);
	340	/* After this point, attr should not be accessed. */
	341	module_put(owner);
	342
	343	if (buffer) {
	344	if (buffer->page)
	345	free_page((unsigned long)buffer->page);
	346	kfree(buffer);
	347	}
	348	return 0;
	349	}
	350
4b6f5d20	351	const struct file_operations sysfs_file_operations = {
1da177e4 LT	352	.read = sysfs_read_file,
	353	.write = sysfs_write_file,
	354	.llseek = generic_file_llseek,
	355	.open = sysfs_open_file,
	356	.release = sysfs_release,
	357	};
	358
	359
	360	int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
	361	{
	362	struct sysfs_dirent * parent_sd = dir->d_fsdata;
	363	umode_t mode = (attr->mode & S_IALLUGO) \| S_IFREG;
c516865c	364	int error = -EEXIST;
1da177e4	365
1b1dcc1b	366	mutex_lock(&dir->d_inode->i_mutex);
c516865c MS	367	if (!sysfs_dirent_exist(parent_sd, attr->name))
	368	error = sysfs_make_dirent(parent_sd, NULL, (void *)attr,
	369	mode, type);
1b1dcc1b	370	mutex_unlock(&dir->d_inode->i_mutex);
1da177e4 LT	371
	372	return error;
	373	}
	374
	375
	376	/**
	377	* sysfs_create_file - create an attribute file for an object.
	378	* @kobj: object we're creating for.
	379	* @attr: atrribute descriptor.
	380	*/
	381
	382	int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
	383	{
	384	BUG_ON(!kobj \|\| !kobj->dentry \|\| !attr);
	385
	386	return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
	387
	388	}
	389
	390
	391	/**
	392	* sysfs_update_file - update the modified timestamp on an object attribute.
	393	* @kobj: object we're acting for.
	394	* @attr: attribute descriptor.
1da177e4 LT	395	*/
	396	int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
	397	{
	398	struct dentry * dir = kobj->dentry;
	399	struct dentry * victim;
	400	int res = -ENOENT;
	401
1b1dcc1b	402	mutex_lock(&dir->d_inode->i_mutex);
5f45f1a7	403	victim = lookup_one_len(attr->name, dir, strlen(attr->name));
1da177e4 LT	404	if (!IS_ERR(victim)) {
	405	/* make sure dentry is really there */
	406	if (victim->d_inode &&
	407	(victim->d_parent->d_inode == dir->d_inode)) {
	408	victim->d_inode->i_mtime = CURRENT_TIME;
0eeca283	409	fsnotify_modify(victim);
1da177e4 LT	410
	411	/**
	412	* Drop reference from initial sysfs_get_dentry().
	413	*/
	414	dput(victim);
	415	res = 0;
	416	} else
	417	d_drop(victim);
	418
	419	/**
	420	* Drop the reference acquired from sysfs_get_dentry() above.
	421	*/
	422	dput(victim);
	423	}
1b1dcc1b	424	mutex_unlock(&dir->d_inode->i_mutex);
1da177e4 LT	425
	426	return res;
	427	}
	428
	429
31e5abe9 KS	430	/**
	431	* sysfs_chmod_file - update the modified mode value on an object attribute.
	432	* @kobj: object we're acting for.
	433	* @attr: attribute descriptor.
	434	* @mode: file permissions.
	435	*
	436	*/
	437	int sysfs_chmod_file(struct kobject kobj, struct attribute attr, mode_t mode)
	438	{
	439	struct dentry *dir = kobj->dentry;
	440	struct dentry *victim;
bc062b1b MS	441	struct inode * inode;
bc062b1b MS	442	struct iattr newattrs;
31e5abe9 KS	443	int res = -ENOENT;
31e5abe9 KS	444
1b1dcc1b	445	mutex_lock(&dir->d_inode->i_mutex);
5f45f1a7	446	victim = lookup_one_len(attr->name, dir, strlen(attr->name));
31e5abe9 KS	447	if (!IS_ERR(victim)) {
	448	if (victim->d_inode &&
	449	(victim->d_parent->d_inode == dir->d_inode)) {
bc062b1b	450	inode = victim->d_inode;
1b1dcc1b	451	mutex_lock(&inode->i_mutex);
bc062b1b MS	452	newattrs.ia_mode = (mode & S_IALLUGO) \|
	453	(inode->i_mode & ~S_IALLUGO);
	454	newattrs.ia_valid = ATTR_MODE \| ATTR_CTIME;
	455	res = notify_change(victim, &newattrs);
1b1dcc1b	456	mutex_unlock(&inode->i_mutex);
31e5abe9	457	}
bc062b1b	458	dput(victim);
31e5abe9	459	}
1b1dcc1b	460	mutex_unlock(&dir->d_inode->i_mutex);
31e5abe9 KS	461
	462	return res;
	463	}
	464	EXPORT_SYMBOL_GPL(sysfs_chmod_file);
	465
	466
1da177e4 LT	467	/**
	468	* sysfs_remove_file - remove an object attribute.
	469	* @kobj: object we're acting for.
	470	* @attr: attribute descriptor.
	471	*
	472	* Hash the attribute name and kill the victim.
	473	*/
	474
	475	void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
	476	{
	477	sysfs_hash_and_remove(kobj->dentry,attr->name);
	478	}
	479
	480
	481	EXPORT_SYMBOL_GPL(sysfs_create_file);
	482	EXPORT_SYMBOL_GPL(sysfs_remove_file);
	483	EXPORT_SYMBOL_GPL(sysfs_update_file);