[net-next-2.6.git] / fs / configfs / file.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * file.c - operations for regular (text) files.
 *
 * 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 021110-1307, USA.
 *
 * Based on sysfs:
 * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
 *
 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>

#include <linux/configfs.h>
#include "configfs_internal.h"


struct configfs_buffer {
	size_t			count;
	loff_t			pos;
	char			* page;
	struct configfs_item_operations	* ops;
	struct semaphore	sem;
	int			needs_read_fill;
};


/**
 *	fill_read_buffer - allocate and fill buffer from item.
 *	@dentry:	dentry pointer.
 *	@buffer:	data buffer for file.
 *
 *	Allocate @buffer->page, if it hasn't been already, then call the
 *	config_item'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 configfs_buffer * buffer)
{
	struct configfs_attribute * attr = to_attr(dentry);
	struct config_item * item = to_item(dentry->d_parent);
	struct configfs_item_operations * 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_attribute(item,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;
}

/**
 *	configfs_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 item is in the directory's
 *	->d_fsdata.
 *
 *	We call fill_read_buffer() to allocate and fill the buffer from the
 *	item'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 item 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
configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
	struct configfs_buffer * buffer = file->private_data;
	ssize_t retval = 0;

	down(&buffer->sem);
	if (buffer->needs_read_fill) {
		if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
			goto out;
	}
	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
		 __FUNCTION__, count, *ppos, buffer->page);
	retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
					 buffer->count);
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 configfs_buffer * buffer, const char __user * buf, size_t count)
{
	int error;

	if (!buffer->page)
		buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
	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 config_item.
 *	@dentry:	dentry to the attribute
 *	@buffer:	data buffer for file.
 *	@count:		number of bytes
 *
 *	Get the correct pointers for the config_item 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 configfs_buffer * buffer, size_t count)
{
	struct configfs_attribute * attr = to_attr(dentry);
	struct config_item * item = to_item(dentry->d_parent);
	struct configfs_item_operations * ops = buffer->ops;

	return ops->store_attribute(item,attr,buffer->page,count);
}


/**
 *	configfs_write_file - write an attribute.
 *	@file:	file pointer
 *	@buf:	data to write
 *	@count:	number of bytes
 *	@ppos:	starting offset
 *
 *	Similar to configfs_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 config_item 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
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
	struct configfs_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_path.dentry, buffer, count);
	if (len > 0)
		*ppos += len;
	up(&buffer->sem);
	return len;
}

static int check_perm(struct inode * inode, struct file * file)
{
	struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
	struct configfs_attribute * attr = to_attr(file->f_path.dentry);
	struct configfs_buffer * buffer;
	struct configfs_item_operations * ops = NULL;
	int error = 0;

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

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

	if (item->ci_type)
		ops = item->ci_type->ct_item_ops;
	else
		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_attribute)
			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_attribute)
			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 configfs_buffer),GFP_KERNEL);
	if (!buffer) {
		error = -ENOMEM;
		goto Enomem;
	}
	init_MUTEX(&buffer->sem);
	buffer->needs_read_fill = 1;
	buffer->ops = ops;
	file->private_data = buffer;
	goto Done;

 Einval:
	error = -EINVAL;
	goto Done;
 Eaccess:
	error = -EACCES;
 Enomem:
	module_put(attr->ca_owner);
 Done:
	if (error && item)
		config_item_put(item);
	return error;
}

static int configfs_open_file(struct inode * inode, struct file * filp)
{
	return check_perm(inode,filp);
}

static int configfs_release(struct inode * inode, struct file * filp)
{
	struct config_item * item = to_item(filp->f_path.dentry->d_parent);
	struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
	struct module * owner = attr->ca_owner;
	struct configfs_buffer * buffer = filp->private_data;

	if (item)
		config_item_put(item);
	/* 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 configfs_file_operations = {
	.read		= configfs_read_file,
	.write		= configfs_write_file,
	.llseek		= generic_file_llseek,
	.open		= configfs_open_file,
	.release	= configfs_release,
};


int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
{
	struct configfs_dirent * parent_sd = dir->d_fsdata;
	umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
	int error = 0;

	mutex_lock(&dir->d_inode->i_mutex);
	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
	mutex_unlock(&dir->d_inode->i_mutex);

	return error;
}


/**
 *	configfs_create_file - create an attribute file for an item.
 *	@item:	item we're creating for.
 *	@attr:	atrribute descriptor.
 */

int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
{
	BUG_ON(!item || !item->ci_dentry || !attr);

	return configfs_add_file(item->ci_dentry, attr,
				 CONFIGFS_ITEM_ATTR);
}
Commit	Line	Data
7063fbf2 JB	1	/* -- mode: c; c-basic-offset: 8; --
	2	* vim: noexpandtab sw=8 ts=8 sts=0:
	3	*
	4	* file.c - operations for regular (text) files.
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public
	8	* License as published by the Free Software Foundation; either
	9	* version 2 of the License, or (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public
	17	* License along with this program; if not, write to the
	18	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	19	* Boston, MA 021110-1307, USA.
	20	*
	21	* Based on sysfs:
	22	* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
	23	*
	24	* configfs Copyright (C) 2005 Oracle. All rights reserved.
	25	*/
	26
	27	#include <linux/fs.h>
	28	#include <linux/module.h>
7063fbf2 JB	29	#include <linux/slab.h>
	30	#include <asm/uaccess.h>
	31	#include <asm/semaphore.h>
	32
	33	#include <linux/configfs.h>
	34	#include "configfs_internal.h"
	35
	36
	37	struct configfs_buffer {
	38	size_t count;
	39	loff_t pos;
	40	char * page;
	41	struct configfs_item_operations * ops;
	42	struct semaphore sem;
	43	int needs_read_fill;
	44	};
	45
	46
	47	/**
	48	* fill_read_buffer - allocate and fill buffer from item.
	49	* @dentry: dentry pointer.
	50	* @buffer: data buffer for file.
	51	*
	52	* Allocate @buffer->page, if it hasn't been already, then call the
	53	* config_item's show() method to fill the buffer with this attribute's
	54	* data.
	55	* This is called only once, on the file's first read.
	56	*/
	57	static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
	58	{
	59	struct configfs_attribute * attr = to_attr(dentry);
	60	struct config_item * item = to_item(dentry->d_parent);
	61	struct configfs_item_operations * ops = buffer->ops;
	62	int ret = 0;
	63	ssize_t count;
	64
	65	if (!buffer->page)
	66	buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
	67	if (!buffer->page)
	68	return -ENOMEM;
	69
	70	count = ops->show_attribute(item,attr,buffer->page);
	71	buffer->needs_read_fill = 0;
	72	BUG_ON(count > (ssize_t)PAGE_SIZE);
	73	if (count >= 0)
	74	buffer->count = count;
	75	else
	76	ret = count;
	77	return ret;
	78	}
	79
7063fbf2 JB	80	/**
	81	* configfs_read_file - read an attribute.
	82	* @file: file pointer.
	83	* @buf: buffer to fill.
	84	* @count: number of bytes to read.
	85	* @ppos: starting offset in file.
	86	*
	87	* Userspace wants to read an attribute file. The attribute descriptor
	88	* is in the file's ->d_fsdata. The target item is in the directory's
	89	* ->d_fsdata.
	90	*
	91	* We call fill_read_buffer() to allocate and fill the buffer from the
	92	* item's show() method exactly once (if the read is happening from
	93	* the beginning of the file). That should fill the entire buffer with
	94	* all the data the item has to offer for that attribute.
	95	* We then call flush_read_buffer() to copy the buffer to userspace
	96	* in the increments specified.
	97	*/
	98
	99	static ssize_t
	100	configfs_read_file(struct file file, char __user buf, size_t count, loff_t *ppos)
	101	{
	102	struct configfs_buffer * buffer = file->private_data;
	103	ssize_t retval = 0;
	104
	105	down(&buffer->sem);
	106	if (buffer->needs_read_fill) {
867fa491	107	if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
7063fbf2 JB	108	goto out;
7063fbf2 JB	109	}
4779efca ZB	110	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
4779efca ZB	111	__FUNCTION__, count, *ppos, buffer->page);
92f4c701 AM	112	retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
92f4c701 AM	113	buffer->count);
7063fbf2 JB	114	out:
	115	up(&buffer->sem);
	116	return retval;
	117	}
	118
	119
	120	/**
	121	* fill_write_buffer - copy buffer from userspace.
	122	* @buffer: data buffer for file.
3d0f89bb	123	* @buf: data from user.
7063fbf2 JB	124	* @count: number of bytes in @userbuf.
	125	*
	126	* Allocate @buffer->page if it hasn't been already, then
	127	* copy the user-supplied buffer into it.
	128	*/
	129
	130	static int
	131	fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
	132	{
	133	int error;
	134
	135	if (!buffer->page)
ff05d1c4	136	buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
7063fbf2 JB	137	if (!buffer->page)
	138	return -ENOMEM;
	139
ff05d1c4 JB	140	if (count >= PAGE_SIZE)
ff05d1c4 JB	141	count = PAGE_SIZE - 1;
7063fbf2 JB	142	error = copy_from_user(buffer->page,buf,count);
7063fbf2 JB	143	buffer->needs_read_fill = 1;
ff05d1c4 JB	144	/* if buf is assumed to contain a string, terminate it by \0,
	145	* so e.g. sscanf() can scan the string easily */
	146	buffer->page[count] = 0;
7063fbf2 JB	147	return error ? -EFAULT : count;
	148	}
	149
	150
	151	/**
	152	* flush_write_buffer - push buffer to config_item.
3d0f89bb	153	* @dentry: dentry to the attribute
7063fbf2	154	* @buffer: data buffer for file.
3d0f89bb	155	* @count: number of bytes
7063fbf2 JB	156	*
	157	* Get the correct pointers for the config_item and the attribute we're
	158	* dealing with, then call the store() method for the attribute,
	159	* passing the buffer that we acquired in fill_write_buffer().
	160	*/
	161
	162	static int
	163	flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
	164	{
	165	struct configfs_attribute * attr = to_attr(dentry);
	166	struct config_item * item = to_item(dentry->d_parent);
	167	struct configfs_item_operations * ops = buffer->ops;
	168
	169	return ops->store_attribute(item,attr,buffer->page,count);
	170	}
	171
	172
	173	/**
	174	* configfs_write_file - write an attribute.
	175	* @file: file pointer
	176	* @buf: data to write
	177	* @count: number of bytes
	178	* @ppos: starting offset
	179	*
	180	* Similar to configfs_read_file(), though working in the opposite direction.
	181	* We allocate and fill the data from the user in fill_write_buffer(),
	182	* then push it to the config_item in flush_write_buffer().
	183	* There is no easy way for us to know if userspace is only doing a partial
	184	* write, so we don't support them. We expect the entire buffer to come
	185	* on the first write.
	186	* Hint: if you're writing a value, first read the file, modify only the
	187	* the value you're changing, then write entire buffer back.
	188	*/
	189
	190	static ssize_t
	191	configfs_write_file(struct file file, const char __user buf, size_t count, loff_t *ppos)
	192	{
	193	struct configfs_buffer * buffer = file->private_data;
3d0f89bb	194	ssize_t len;
7063fbf2 JB	195
7063fbf2 JB	196	down(&buffer->sem);
3d0f89bb JB	197	len = fill_write_buffer(buffer, buf, count);
3d0f89bb JB	198	if (len > 0)
867fa491	199	len = flush_write_buffer(file->f_path.dentry, buffer, count);
3d0f89bb JB	200	if (len > 0)
3d0f89bb JB	201	*ppos += len;
7063fbf2	202	up(&buffer->sem);
3d0f89bb	203	return len;
7063fbf2 JB	204	}
	205
	206	static int check_perm(struct inode * inode, struct file * file)
	207	{
867fa491 JJS	208	struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
867fa491 JJS	209	struct configfs_attribute * attr = to_attr(file->f_path.dentry);
7063fbf2 JB	210	struct configfs_buffer * buffer;
	211	struct configfs_item_operations * ops = NULL;
	212	int error = 0;
	213
	214	if (!item \|\| !attr)
	215	goto Einval;
	216
	217	/* Grab the module reference for this attribute if we have one */
	218	if (!try_module_get(attr->ca_owner)) {
	219	error = -ENODEV;
	220	goto Done;
	221	}
	222
	223	if (item->ci_type)
	224	ops = item->ci_type->ct_item_ops;
	225	else
	226	goto Eaccess;
	227
	228	/* File needs write support.
	229	* The inode's perms must say it's ok,
	230	* and we must have a store method.
	231	*/
	232	if (file->f_mode & FMODE_WRITE) {
	233
	234	if (!(inode->i_mode & S_IWUGO) \|\| !ops->store_attribute)
	235	goto Eaccess;
	236
	237	}
	238
	239	/* File needs read support.
	240	* The inode's perms must say it's ok, and we there
	241	* must be a show method for it.
	242	*/
	243	if (file->f_mode & FMODE_READ) {
	244	if (!(inode->i_mode & S_IRUGO) \|\| !ops->show_attribute)
	245	goto Eaccess;
	246	}
	247
	248	/* No error? Great, allocate a buffer for the file, and store it
	249	* it in file->private_data for easy access.
	250	*/
f8314dc6	251	buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
559c9ac3	252	if (!buffer) {
7063fbf2	253	error = -ENOMEM;
559c9ac3 CS	254	goto Enomem;
	255	}
	256	init_MUTEX(&buffer->sem);
	257	buffer->needs_read_fill = 1;
	258	buffer->ops = ops;
	259	file->private_data = buffer;
7063fbf2 JB	260	goto Done;
	261
	262	Einval:
	263	error = -EINVAL;
	264	goto Done;
	265	Eaccess:
	266	error = -EACCES;
559c9ac3	267	Enomem:
7063fbf2 JB	268	module_put(attr->ca_owner);
	269	Done:
	270	if (error && item)
	271	config_item_put(item);
	272	return error;
	273	}
	274
	275	static int configfs_open_file(struct inode * inode, struct file * filp)
	276	{
	277	return check_perm(inode,filp);
	278	}
	279
	280	static int configfs_release(struct inode * inode, struct file * filp)
	281	{
867fa491 JJS	282	struct config_item * item = to_item(filp->f_path.dentry->d_parent);
867fa491 JJS	283	struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
7063fbf2 JB	284	struct module * owner = attr->ca_owner;
	285	struct configfs_buffer * buffer = filp->private_data;
	286
	287	if (item)
	288	config_item_put(item);
	289	/* After this point, attr should not be accessed. */
	290	module_put(owner);
	291
	292	if (buffer) {
	293	if (buffer->page)
	294	free_page((unsigned long)buffer->page);
	295	kfree(buffer);
	296	}
	297	return 0;
	298	}
	299
4b6f5d20	300	const struct file_operations configfs_file_operations = {
7063fbf2 JB	301	.read = configfs_read_file,
	302	.write = configfs_write_file,
	303	.llseek = generic_file_llseek,
	304	.open = configfs_open_file,
	305	.release = configfs_release,
	306	};
	307
	308
	309	int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
	310	{
	311	struct configfs_dirent * parent_sd = dir->d_fsdata;
	312	umode_t mode = (attr->ca_mode & S_IALLUGO) \| S_IFREG;
	313	int error = 0;
	314
1b1dcc1b	315	mutex_lock(&dir->d_inode->i_mutex);
7063fbf2	316	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
1b1dcc1b	317	mutex_unlock(&dir->d_inode->i_mutex);
7063fbf2 JB	318
	319	return error;
	320	}
	321
	322
	323	/**
	324	* configfs_create_file - create an attribute file for an item.
	325	* @item: item we're creating for.
	326	* @attr: atrribute descriptor.
	327	*/
	328
	329	int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
	330	{
	331	BUG_ON(!item \|\| !item->ci_dentry \|\| !attr);
	332
	333	return configfs_add_file(item->ci_dentry, attr,
	334	CONFIGFS_ITEM_ATTR);
	335	}
	336