[mirror_ubuntu-artful-kernel.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 <linux/mutex.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>

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

/*
 * A simple attribute can only be 4096 characters.  Why 4k?  Because the
 * original code limited it to PAGE_SIZE.  That's a bad idea, though,
 * because an attribute of 16k on ia64 won't work on x86.  So we limit to
 * 4k, our minimum common page size.
 */
#define SIMPLE_ATTR_SIZE 4096

struct configfs_buffer {
	size_t			count;
	loff_t			pos;
	char			* page;
	struct configfs_item_operations	* ops;
	struct mutex		mutex;
	int			needs_read_fill;
	bool			read_in_progress;
	bool			write_in_progress;
	char			*bin_buffer;
	int			bin_buffer_size;
};


/**
 *	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);
	int ret = 0;
	ssize_t count;

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

	count = attr->show(item, buffer->page);

	BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
	if (count >= 0) {
		buffer->needs_read_fill = 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;

	mutex_lock(&buffer->mutex);
	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",
		 __func__, count, *ppos, buffer->page);
	retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
					 buffer->count);
out:
	mutex_unlock(&buffer->mutex);
	return retval;
}

/**
 *	configfs_read_bin_file - read a binary attribute.
 *	@file:	file pointer.
 *	@buf:	buffer to fill.
 *	@count:	number of bytes to read.
 *	@ppos:	starting offset in file.
 *
 *	Userspace wants to read a binary attribute file. The attribute
 *	descriptor is in the file's ->d_fsdata. The target item is in the
 *	directory's ->d_fsdata.
 *
 *	We check whether we need to refill the buffer. If so we will
 *	call the attributes' attr->read() twice. The first time we
 *	will pass a NULL as a buffer pointer, which the attributes' method
 *	will use to return the size of the buffer required. If no error
 *	occurs we will allocate the buffer using vmalloc and call
 *	attr->read() again passing that buffer as an argument.
 *	Then we just copy to user-space using simple_read_from_buffer.
 */

static ssize_t
configfs_read_bin_file(struct file *file, char __user *buf,
		       size_t count, loff_t *ppos)
{
	struct configfs_buffer *buffer = file->private_data;
	struct dentry *dentry = file->f_path.dentry;
	struct config_item *item = to_item(dentry->d_parent);
	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
	ssize_t retval = 0;
	ssize_t len = min_t(size_t, count, PAGE_SIZE);

	mutex_lock(&buffer->mutex);

	/* we don't support switching read/write modes */
	if (buffer->write_in_progress) {
		retval = -ETXTBSY;
		goto out;
	}
	buffer->read_in_progress = 1;

	if (buffer->needs_read_fill) {
		/* perform first read with buf == NULL to get extent */
		len = bin_attr->read(item, NULL, 0);
		if (len <= 0) {
			retval = len;
			goto out;
		}

		/* do not exceed the maximum value */
		if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
			retval = -EFBIG;
			goto out;
		}

		buffer->bin_buffer = vmalloc(len);
		if (buffer->bin_buffer == NULL) {
			retval = -ENOMEM;
			goto out;
		}
		buffer->bin_buffer_size = len;

		/* perform second read to fill buffer */
		len = bin_attr->read(item, buffer->bin_buffer, len);
		if (len < 0) {
			retval = len;
			vfree(buffer->bin_buffer);
			buffer->bin_buffer_size = 0;
			buffer->bin_buffer = NULL;
			goto out;
		}

		buffer->needs_read_fill = 0;
	}

	retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
					buffer->bin_buffer_size);
out:
	mutex_unlock(&buffer->mutex);
	return retval;
}


/**
 *	fill_write_buffer - copy buffer from userspace.
 *	@buffer:	data buffer for file.
 *	@buf:		data from user.
 *	@count:		number of bytes in @userbuf.
 *
 *	Allocate @buffer->page if it hasn't been already, then
 *	copy the user-supplied buffer into it.
 */

static int
fill_write_buffer(struct 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 >= SIMPLE_ATTR_SIZE)
		count = SIMPLE_ATTR_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);

	return attr->store(item, 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;

	mutex_lock(&buffer->mutex);
	len = fill_write_buffer(buffer, buf, count);
	if (len > 0)
		len = flush_write_buffer(file->f_path.dentry, buffer, len);
	if (len > 0)
		*ppos += len;
	mutex_unlock(&buffer->mutex);
	return len;
}

/**
 *	configfs_write_bin_file - write a binary attribute.
 *	@file:	file pointer
 *	@buf:	data to write
 *	@count:	number of bytes
 *	@ppos:	starting offset
 *
 *	Writing to a binary attribute file is similar to a normal read.
 *	We buffer the consecutive writes (binary attribute files do not
 *	support lseek) in a continuously growing buffer, but we don't
 *	commit until the close of the file.
 */

static ssize_t
configfs_write_bin_file(struct file *file, const char __user *buf,
			size_t count, loff_t *ppos)
{
	struct configfs_buffer *buffer = file->private_data;
	struct dentry *dentry = file->f_path.dentry;
	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
	void *tbuf = NULL;
	ssize_t len;

	mutex_lock(&buffer->mutex);

	/* we don't support switching read/write modes */
	if (buffer->read_in_progress) {
		len = -ETXTBSY;
		goto out;
	}
	buffer->write_in_progress = 1;

	/* buffer grows? */
	if (*ppos + count > buffer->bin_buffer_size) {

		if (bin_attr->cb_max_size &&
			*ppos + count > bin_attr->cb_max_size) {
			len = -EFBIG;
			goto out;
		}

		tbuf = vmalloc(*ppos + count);
		if (tbuf == NULL) {
			len = -ENOMEM;
			goto out;
		}

		/* copy old contents */
		if (buffer->bin_buffer) {
			memcpy(tbuf, buffer->bin_buffer,
				buffer->bin_buffer_size);
			vfree(buffer->bin_buffer);
		}

		/* clear the new area */
		memset(tbuf + buffer->bin_buffer_size, 0,
			*ppos + count - buffer->bin_buffer_size);
		buffer->bin_buffer = tbuf;
		buffer->bin_buffer_size = *ppos + count;
	}

	len = simple_write_to_buffer(buffer->bin_buffer,
			buffer->bin_buffer_size, ppos, buf, count);
out:
	mutex_unlock(&buffer->mutex);
	return len;
}

static int check_perm(struct inode * inode, struct file * file, int type)
{
	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_bin_attribute *bin_attr = NULL;
	struct configfs_buffer * buffer;
	struct configfs_item_operations * ops = NULL;
	int error = 0;

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

	if (type & CONFIGFS_ITEM_BIN_ATTR)
		bin_attr = to_bin_attr(file->f_path.dentry);

	/* 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))
			goto Eaccess;

		if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
			goto Eaccess;

		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_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))
			goto Eaccess;

		if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
			goto Eaccess;

		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
			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;
	}
	mutex_init(&buffer->mutex);
	buffer->needs_read_fill = 1;
	buffer->read_in_progress = 0;
	buffer->write_in_progress = 0;
	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_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);
		mutex_destroy(&buffer->mutex);
		kfree(buffer);
	}
	return 0;
}

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

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

static int configfs_release_bin_file(struct inode *inode, struct file *filp)
{
	struct configfs_buffer *buffer = filp->private_data;
	struct dentry *dentry = filp->f_path.dentry;
	struct config_item *item = to_item(dentry->d_parent);
	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
	ssize_t len = 0;
	int ret;

	buffer->read_in_progress = 0;

	if (buffer->write_in_progress) {
		buffer->write_in_progress = 0;

		len = bin_attr->write(item, buffer->bin_buffer,
				buffer->bin_buffer_size);

		/* vfree on NULL is safe */
		vfree(buffer->bin_buffer);
		buffer->bin_buffer = NULL;
		buffer->bin_buffer_size = 0;
		buffer->needs_read_fill = 1;
	}

	ret = configfs_release(inode, filp);
	if (len < 0)
		return len;
	return ret;
}


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,
};

const struct file_operations configfs_bin_file_operations = {
	.read		= configfs_read_bin_file,
	.write		= configfs_write_bin_file,
	.llseek		= NULL,		/* bin file is not seekable */
	.open		= configfs_open_bin_file,
	.release	= configfs_release_bin_file,
};

/**
 *	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)
{
	struct dentry *dir = item->ci_dentry;
	struct configfs_dirent *parent_sd = dir->d_fsdata;
	umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
	int error = 0;

	inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
				     CONFIGFS_ITEM_ATTR);
	inode_unlock(d_inode(dir));

	return error;
}

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

int configfs_create_bin_file(struct config_item *item,
		const struct configfs_bin_attribute *bin_attr)
{
	struct dentry *dir = item->ci_dentry;
	struct configfs_dirent *parent_sd = dir->d_fsdata;
	umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG;
	int error = 0;

	inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
	error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
				     CONFIGFS_ITEM_BIN_ATTR);
	inode_unlock(dir->d_inode);

	return error;
}
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	29	#include <linux/slab.h>
6d748924	30	#include <linux/mutex.h>
03607ace	31	#include <linux/vmalloc.h>
7c0f6ba6	32	#include <linux/uaccess.h>
7063fbf2 JB	33
	34	#include <linux/configfs.h>
	35	#include "configfs_internal.h"
	36
b23cdde4 JB	37	/*
	38	* A simple attribute can only be 4096 characters. Why 4k? Because the
	39	* original code limited it to PAGE_SIZE. That's a bad idea, though,
	40	* because an attribute of 16k on ia64 won't work on x86. So we limit to
	41	* 4k, our minimum common page size.
	42	*/
	43	#define SIMPLE_ATTR_SIZE 4096
7063fbf2 JB	44
	45	struct configfs_buffer {
	46	size_t count;
	47	loff_t pos;
	48	char * page;
	49	struct configfs_item_operations * ops;
6d748924	50	struct mutex mutex;
7063fbf2	51	int needs_read_fill;
03607ace PA	52	bool read_in_progress;
	53	bool write_in_progress;
	54	char *bin_buffer;
	55	int bin_buffer_size;
7063fbf2 JB	56	};
	57
	58
	59	/**
	60	* fill_read_buffer - allocate and fill buffer from item.
	61	* @dentry: dentry pointer.
	62	* @buffer: data buffer for file.
	63	*
	64	* Allocate @buffer->page, if it hasn't been already, then call the
	65	* config_item's show() method to fill the buffer with this attribute's
	66	* data.
	67	* This is called only once, on the file's first read.
	68	*/
	69	static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
	70	{
	71	struct configfs_attribute * attr = to_attr(dentry);
	72	struct config_item * item = to_item(dentry->d_parent);
7063fbf2 JB	73	int ret = 0;
	74	ssize_t count;
	75
	76	if (!buffer->page)
	77	buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
	78	if (!buffer->page)
	79	return -ENOMEM;
	80
51798222	81	count = attr->show(item, buffer->page);
870823e6	82
b23cdde4	83	BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
3dc3afad TS	84	if (count >= 0) {
3dc3afad TS	85	buffer->needs_read_fill = 0;
7063fbf2	86	buffer->count = count;
3dc3afad	87	} else
7063fbf2 JB	88	ret = count;
	89	return ret;
	90	}
	91
7063fbf2 JB	92	/**
	93	* configfs_read_file - read an attribute.
	94	* @file: file pointer.
	95	* @buf: buffer to fill.
	96	* @count: number of bytes to read.
	97	* @ppos: starting offset in file.
	98	*
	99	* Userspace wants to read an attribute file. The attribute descriptor
	100	* is in the file's ->d_fsdata. The target item is in the directory's
	101	* ->d_fsdata.
	102	*
	103	* We call fill_read_buffer() to allocate and fill the buffer from the
	104	* item's show() method exactly once (if the read is happening from
	105	* the beginning of the file). That should fill the entire buffer with
	106	* all the data the item has to offer for that attribute.
	107	* We then call flush_read_buffer() to copy the buffer to userspace
	108	* in the increments specified.
	109	*/
	110
	111	static ssize_t
	112	configfs_read_file(struct file file, char __user buf, size_t count, loff_t *ppos)
	113	{
	114	struct configfs_buffer * buffer = file->private_data;
	115	ssize_t retval = 0;
	116
6d748924	117	mutex_lock(&buffer->mutex);
7063fbf2	118	if (buffer->needs_read_fill) {
867fa491	119	if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
7063fbf2 JB	120	goto out;
7063fbf2 JB	121	}
4779efca	122	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
8e24eea7	123	__func__, count, *ppos, buffer->page);
92f4c701 AM	124	retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
92f4c701 AM	125	buffer->count);
7063fbf2	126	out:
6d748924	127	mutex_unlock(&buffer->mutex);
7063fbf2 JB	128	return retval;
	129	}
	130
03607ace PA	131	/**
	132	* configfs_read_bin_file - read a binary attribute.
	133	* @file: file pointer.
	134	* @buf: buffer to fill.
	135	* @count: number of bytes to read.
	136	* @ppos: starting offset in file.
	137	*
	138	* Userspace wants to read a binary attribute file. The attribute
	139	* descriptor is in the file's ->d_fsdata. The target item is in the
	140	* directory's ->d_fsdata.
	141	*
	142	* We check whether we need to refill the buffer. If so we will
	143	* call the attributes' attr->read() twice. The first time we
	144	* will pass a NULL as a buffer pointer, which the attributes' method
	145	* will use to return the size of the buffer required. If no error
	146	* occurs we will allocate the buffer using vmalloc and call
	147	* attr->read() again passing that buffer as an argument.
	148	* Then we just copy to user-space using simple_read_from_buffer.
	149	*/
	150
	151	static ssize_t
	152	configfs_read_bin_file(struct file file, char __user buf,
	153	size_t count, loff_t *ppos)
	154	{
	155	struct configfs_buffer *buffer = file->private_data;
	156	struct dentry *dentry = file->f_path.dentry;
	157	struct config_item *item = to_item(dentry->d_parent);
	158	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
	159	ssize_t retval = 0;
	160	ssize_t len = min_t(size_t, count, PAGE_SIZE);
	161
	162	mutex_lock(&buffer->mutex);
	163
	164	/* we don't support switching read/write modes */
	165	if (buffer->write_in_progress) {
	166	retval = -ETXTBSY;
	167	goto out;
	168	}
	169	buffer->read_in_progress = 1;
	170
	171	if (buffer->needs_read_fill) {
	172	/* perform first read with buf == NULL to get extent */
	173	len = bin_attr->read(item, NULL, 0);
	174	if (len <= 0) {
	175	retval = len;
	176	goto out;
	177	}
	178
	179	/* do not exceed the maximum value */
	180	if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
	181	retval = -EFBIG;
	182	goto out;
	183	}
	184
	185	buffer->bin_buffer = vmalloc(len);
	186	if (buffer->bin_buffer == NULL) {
	187	retval = -ENOMEM;
	188	goto out;
	189	}
	190	buffer->bin_buffer_size = len;
	191
	192	/* perform second read to fill buffer */
	193	len = bin_attr->read(item, buffer->bin_buffer, len);
	194	if (len < 0) {
195	retval = len;
196	vfree(buffer->bin_buffer);
197	buffer->bin_buffer_size = 0;
198	buffer->bin_buffer = NULL;
199	goto out;
200	}
201
202	buffer->needs_read_fill = 0;
203	}
204
205	retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
206	buffer->bin_buffer_size);
207	out:
208	mutex_unlock(&buffer->mutex);
209	return retval;
210	}
211
7063fbf2 JB	212
	213	/**
	214	* fill_write_buffer - copy buffer from userspace.
	215	* @buffer: data buffer for file.
3d0f89bb	216	* @buf: data from user.
7063fbf2 JB	217	* @count: number of bytes in @userbuf.
	218	*
	219	* Allocate @buffer->page if it hasn't been already, then
	220	* copy the user-supplied buffer into it.
	221	*/
	222
	223	static int
	224	fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
	225	{
	226	int error;
	227
	228	if (!buffer->page)
ff05d1c4	229	buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
7063fbf2 JB	230	if (!buffer->page)
	231	return -ENOMEM;
	232
b23cdde4 JB	233	if (count >= SIMPLE_ATTR_SIZE)
b23cdde4 JB	234	count = SIMPLE_ATTR_SIZE - 1;
7063fbf2 JB	235	error = copy_from_user(buffer->page,buf,count);
7063fbf2 JB	236	buffer->needs_read_fill = 1;
ff05d1c4 JB	237	/* if buf is assumed to contain a string, terminate it by \0,
	238	* so e.g. sscanf() can scan the string easily */
	239	buffer->page[count] = 0;
7063fbf2 JB	240	return error ? -EFAULT : count;
	241	}
	242
	243
	244	/**
	245	* flush_write_buffer - push buffer to config_item.
3d0f89bb	246	* @dentry: dentry to the attribute
7063fbf2	247	* @buffer: data buffer for file.
3d0f89bb	248	* @count: number of bytes
7063fbf2 JB	249	*
	250	* Get the correct pointers for the config_item and the attribute we're
	251	* dealing with, then call the store() method for the attribute,
	252	* passing the buffer that we acquired in fill_write_buffer().
	253	*/
	254
	255	static int
	256	flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
	257	{
	258	struct configfs_attribute * attr = to_attr(dentry);
	259	struct config_item * item = to_item(dentry->d_parent);
7063fbf2	260
870823e6	261	return attr->store(item, buffer->page, count);
7063fbf2 JB	262	}
	263
	264
	265	/**
	266	* configfs_write_file - write an attribute.
	267	* @file: file pointer
	268	* @buf: data to write
	269	* @count: number of bytes
	270	* @ppos: starting offset
	271	*
	272	* Similar to configfs_read_file(), though working in the opposite direction.
	273	* We allocate and fill the data from the user in fill_write_buffer(),
	274	* then push it to the config_item in flush_write_buffer().
	275	* There is no easy way for us to know if userspace is only doing a partial
	276	* write, so we don't support them. We expect the entire buffer to come
	277	* on the first write.
	278	* Hint: if you're writing a value, first read the file, modify only the
	279	* the value you're changing, then write entire buffer back.
	280	*/
	281
	282	static ssize_t
	283	configfs_write_file(struct file file, const char __user buf, size_t count, loff_t *ppos)
	284	{
	285	struct configfs_buffer * buffer = file->private_data;
3d0f89bb	286	ssize_t len;
7063fbf2	287
6d748924	288	mutex_lock(&buffer->mutex);
3d0f89bb JB	289	len = fill_write_buffer(buffer, buf, count);
3d0f89bb JB	290	if (len > 0)
7121064b	291	len = flush_write_buffer(file->f_path.dentry, buffer, len);
3d0f89bb JB	292	if (len > 0)
3d0f89bb JB	293	*ppos += len;
6d748924	294	mutex_unlock(&buffer->mutex);
3d0f89bb	295	return len;
7063fbf2 JB	296	}
7063fbf2 JB	297
03607ace PA	298	/**
	299	* configfs_write_bin_file - write a binary attribute.
	300	* @file: file pointer
	301	* @buf: data to write
	302	* @count: number of bytes
	303	* @ppos: starting offset
	304	*
	305	* Writing to a binary attribute file is similar to a normal read.
	306	* We buffer the consecutive writes (binary attribute files do not
	307	* support lseek) in a continuously growing buffer, but we don't
	308	* commit until the close of the file.
	309	*/
	310
	311	static ssize_t
	312	configfs_write_bin_file(struct file file, const char __user buf,
	313	size_t count, loff_t *ppos)
	314	{
	315	struct configfs_buffer *buffer = file->private_data;
	316	struct dentry *dentry = file->f_path.dentry;
	317	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
	318	void *tbuf = NULL;
	319	ssize_t len;
	320
	321	mutex_lock(&buffer->mutex);
	322
	323	/* we don't support switching read/write modes */
	324	if (buffer->read_in_progress) {
	325	len = -ETXTBSY;
	326	goto out;
	327	}
	328	buffer->write_in_progress = 1;
	329
	330	/* buffer grows? */
	331	if (*ppos + count > buffer->bin_buffer_size) {
	332
	333	if (bin_attr->cb_max_size &&
	334	*ppos + count > bin_attr->cb_max_size) {
	335	len = -EFBIG;
42857cf5	336	goto out;
03607ace PA	337	}
	338
	339	tbuf = vmalloc(*ppos + count);
	340	if (tbuf == NULL) {
	341	len = -ENOMEM;
	342	goto out;
	343	}
	344
	345	/* copy old contents */
	346	if (buffer->bin_buffer) {
	347	memcpy(tbuf, buffer->bin_buffer,
	348	buffer->bin_buffer_size);
	349	vfree(buffer->bin_buffer);
	350	}
	351
	352	/* clear the new area */
	353	memset(tbuf + buffer->bin_buffer_size, 0,
	354	*ppos + count - buffer->bin_buffer_size);
	355	buffer->bin_buffer = tbuf;
	356	buffer->bin_buffer_size = *ppos + count;
	357	}
	358
	359	len = simple_write_to_buffer(buffer->bin_buffer,
	360	buffer->bin_buffer_size, ppos, buf, count);
03607ace PA	361	out:
	362	mutex_unlock(&buffer->mutex);
	363	return len;
	364	}
	365
	366	static int check_perm(struct inode * inode, struct file * file, int type)
7063fbf2	367	{
867fa491 JJS	368	struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
867fa491 JJS	369	struct configfs_attribute * attr = to_attr(file->f_path.dentry);
03607ace	370	struct configfs_bin_attribute *bin_attr = NULL;
7063fbf2 JB	371	struct configfs_buffer * buffer;
	372	struct configfs_item_operations * ops = NULL;
	373	int error = 0;
	374
	375	if (!item \|\| !attr)
	376	goto Einval;
	377
03607ace PA	378	if (type & CONFIGFS_ITEM_BIN_ATTR)
	379	bin_attr = to_bin_attr(file->f_path.dentry);
	380
7063fbf2 JB	381	/* Grab the module reference for this attribute if we have one */
	382	if (!try_module_get(attr->ca_owner)) {
	383	error = -ENODEV;
	384	goto Done;
	385	}
	386
	387	if (item->ci_type)
	388	ops = item->ci_type->ct_item_ops;
	389	else
	390	goto Eaccess;
	391
	392	/* File needs write support.
	393	* The inode's perms must say it's ok,
	394	* and we must have a store method.
	395	*/
	396	if (file->f_mode & FMODE_WRITE) {
03607ace PA	397	if (!(inode->i_mode & S_IWUGO))
	398	goto Eaccess;
	399
	400	if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
7063fbf2 JB	401	goto Eaccess;
7063fbf2 JB	402
03607ace PA	403	if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
03607ace PA	404	goto Eaccess;
7063fbf2 JB	405	}
	406
	407	/* File needs read support.
	408	* The inode's perms must say it's ok, and we there
	409	* must be a show method for it.
	410	*/
	411	if (file->f_mode & FMODE_READ) {
03607ace PA	412	if (!(inode->i_mode & S_IRUGO))
	413	goto Eaccess;
	414
	415	if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
	416	goto Eaccess;
	417
	418	if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
7063fbf2 JB	419	goto Eaccess;
	420	}
	421
	422	/* No error? Great, allocate a buffer for the file, and store it
	423	* it in file->private_data for easy access.
	424	*/
f8314dc6	425	buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
559c9ac3	426	if (!buffer) {
7063fbf2	427	error = -ENOMEM;
559c9ac3 CS	428	goto Enomem;
559c9ac3 CS	429	}
6d748924	430	mutex_init(&buffer->mutex);
559c9ac3	431	buffer->needs_read_fill = 1;
03607ace PA	432	buffer->read_in_progress = 0;
03607ace PA	433	buffer->write_in_progress = 0;
559c9ac3 CS	434	buffer->ops = ops;
559c9ac3 CS	435	file->private_data = buffer;
7063fbf2 JB	436	goto Done;
	437
	438	Einval:
	439	error = -EINVAL;
	440	goto Done;
	441	Eaccess:
	442	error = -EACCES;
559c9ac3	443	Enomem:
7063fbf2 JB	444	module_put(attr->ca_owner);
	445	Done:
	446	if (error && item)
	447	config_item_put(item);
	448	return error;
	449	}
	450
03607ace	451	static int configfs_release(struct inode inode, struct file filp)
7063fbf2	452	{
867fa491 JJS	453	struct config_item * item = to_item(filp->f_path.dentry->d_parent);
867fa491 JJS	454	struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
7063fbf2 JB	455	struct module * owner = attr->ca_owner;
	456	struct configfs_buffer * buffer = filp->private_data;
	457
	458	if (item)
	459	config_item_put(item);
	460	/* After this point, attr should not be accessed. */
	461	module_put(owner);
	462
	463	if (buffer) {
	464	if (buffer->page)
	465	free_page((unsigned long)buffer->page);
6d748924	466	mutex_destroy(&buffer->mutex);
7063fbf2 JB	467	kfree(buffer);
	468	}
	469	return 0;
	470	}
	471
03607ace PA	472	static int configfs_open_file(struct inode inode, struct file filp)
	473	{
	474	return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
	475	}
	476
	477	static int configfs_open_bin_file(struct inode inode, struct file filp)
	478	{
	479	return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
	480	}
	481
	482	static int configfs_release_bin_file(struct inode inode, struct file filp)
	483	{
	484	struct configfs_buffer *buffer = filp->private_data;
	485	struct dentry *dentry = filp->f_path.dentry;
	486	struct config_item *item = to_item(dentry->d_parent);
	487	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
	488	ssize_t len = 0;
	489	int ret;
	490
	491	buffer->read_in_progress = 0;
	492
	493	if (buffer->write_in_progress) {
	494	buffer->write_in_progress = 0;
	495
	496	len = bin_attr->write(item, buffer->bin_buffer,
	497	buffer->bin_buffer_size);
	498
	499	/* vfree on NULL is safe */
	500	vfree(buffer->bin_buffer);
	501	buffer->bin_buffer = NULL;
	502	buffer->bin_buffer_size = 0;
	503	buffer->needs_read_fill = 1;
	504	}
	505
	506	ret = configfs_release(inode, filp);
	507	if (len < 0)
	508	return len;
	509	return ret;
	510	}
	511
	512
4b6f5d20	513	const struct file_operations configfs_file_operations = {
7063fbf2 JB	514	.read = configfs_read_file,
	515	.write = configfs_write_file,
	516	.llseek = generic_file_llseek,
	517	.open = configfs_open_file,
	518	.release = configfs_release,
	519	};
	520
03607ace PA	521	const struct file_operations configfs_bin_file_operations = {
	522	.read = configfs_read_bin_file,
	523	.write = configfs_write_bin_file,
	524	.llseek = NULL, /* bin file is not seekable */
	525	.open = configfs_open_bin_file,
	526	.release = configfs_release_bin_file,
	527	};
	528
7063fbf2 JB	529	/**
	530	* configfs_create_file - create an attribute file for an item.
	531	* @item: item we're creating for.
	532	* @attr: atrribute descriptor.
	533	*/
	534
	535	int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
	536	{
28444a2b AV	537	struct dentry *dir = item->ci_dentry;
	538	struct configfs_dirent *parent_sd = dir->d_fsdata;
	539	umode_t mode = (attr->ca_mode & S_IALLUGO) \| S_IFREG;
	540	int error = 0;
7063fbf2	541
5955102c	542	inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
28444a2b AV	543	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
28444a2b AV	544	CONFIGFS_ITEM_ATTR);
5955102c	545	inode_unlock(d_inode(dir));
28444a2b AV	546
28444a2b AV	547	return error;
7063fbf2 JB	548	}
7063fbf2 JB	549
03607ace PA	550	/**
	551	* configfs_create_bin_file - create a binary attribute file for an item.
	552	* @item: item we're creating for.
	553	* @attr: atrribute descriptor.
	554	*/
	555
	556	int configfs_create_bin_file(struct config_item *item,
	557	const struct configfs_bin_attribute *bin_attr)
	558	{
	559	struct dentry *dir = item->ci_dentry;
	560	struct configfs_dirent *parent_sd = dir->d_fsdata;
	561	umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) \| S_IFREG;
	562	int error = 0;
	563
5955102c	564	inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
03607ace PA	565	error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
03607ace PA	566	CONFIGFS_ITEM_BIN_ATTR);
5955102c	567	inode_unlock(dir->d_inode);
03607ace PA	568
	569	return error;
	570	}