[linux-2.6-block.git] / fs / configfs / file.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * file.c - operations for regular (text) files.
 *
 * 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/uio.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;
	int			cb_max_size;
	struct config_item	*item;
	struct module		*owner;
	union {
		struct configfs_attribute	*attr;
		struct configfs_bin_attribute	*bin_attr;
	};
};

static inline struct configfs_fragment *to_frag(struct file *file)
{
	struct configfs_dirent *sd = file->f_path.dentry->d_fsdata;

	return sd->s_frag;
}

static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer)
{
	struct configfs_fragment *frag = to_frag(file);
	ssize_t count = -ENOENT;

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

	down_read(&frag->frag_sem);
	if (!frag->frag_dead)
		count = buffer->attr->show(buffer->item, buffer->page);
	up_read(&frag->frag_sem);

	if (count < 0)
		return count;
	if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))
		return -EIO;
	buffer->needs_read_fill = 0;
	buffer->count = count;
	return 0;
}

static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct file *file = iocb->ki_filp;
	struct configfs_buffer *buffer = file->private_data;
	ssize_t retval = 0;

	mutex_lock(&buffer->mutex);
	if (buffer->needs_read_fill) {
		retval = fill_read_buffer(file, buffer);
		if (retval)
			goto out;
	}
	pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
		 __func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
	if (iocb->ki_pos >= buffer->count)
		goto out;
	retval = copy_to_iter(buffer->page + iocb->ki_pos,
			      buffer->count - iocb->ki_pos, to);
	iocb->ki_pos += retval;
	if (retval == 0)
		retval = -EFAULT;
out:
	mutex_unlock(&buffer->mutex);
	return retval;
}

static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct file *file = iocb->ki_filp;
	struct configfs_fragment *frag = to_frag(file);
	struct configfs_buffer *buffer = file->private_data;
	ssize_t retval = 0;
	ssize_t len;

	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 = true;

	if (buffer->needs_read_fill) {
		/* perform first read with buf == NULL to get extent */
		down_read(&frag->frag_sem);
		if (!frag->frag_dead)
			len = buffer->bin_attr->read(buffer->item, NULL, 0);
		else
			len = -ENOENT;
		up_read(&frag->frag_sem);
		if (len <= 0) {
			retval = len;
			goto out;
		}

		/* do not exceed the maximum value */
		if (buffer->cb_max_size && len > buffer->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 */
		down_read(&frag->frag_sem);
		if (!frag->frag_dead)
			len = buffer->bin_attr->read(buffer->item,
						     buffer->bin_buffer, len);
		else
			len = -ENOENT;
		up_read(&frag->frag_sem);
		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;
	}

	if (iocb->ki_pos >= buffer->bin_buffer_size)
		goto out;
	retval = copy_to_iter(buffer->bin_buffer + iocb->ki_pos,
			      buffer->bin_buffer_size - iocb->ki_pos, to);
	iocb->ki_pos += retval;
	if (retval == 0)
		retval = -EFAULT;
out:
	mutex_unlock(&buffer->mutex);
	return retval;
}

/* Fill @buffer with data coming from @from. */
static int fill_write_buffer(struct configfs_buffer *buffer,
			     struct iov_iter *from)
{
	int copied;

	if (!buffer->page)
		buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
	if (!buffer->page)
		return -ENOMEM;

	copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
	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[copied] = 0;
	return copied ? : -EFAULT;
}

static int
flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t count)
{
	struct configfs_fragment *frag = to_frag(file);
	int res = -ENOENT;

	down_read(&frag->frag_sem);
	if (!frag->frag_dead)
		res = buffer->attr->store(buffer->item, buffer->page, count);
	up_read(&frag->frag_sem);
	return res;
}


/*
 * 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 value
 * you're changing, then write entire buffer back.
 */
static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
	struct file *file = iocb->ki_filp;
	struct configfs_buffer *buffer = file->private_data;
	int len;

	mutex_lock(&buffer->mutex);
	len = fill_write_buffer(buffer, from);
	if (len > 0)
		len = flush_write_buffer(file, buffer, len);
	if (len > 0)
		iocb->ki_pos += len;
	mutex_unlock(&buffer->mutex);
	return len;
}

static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
				       struct iov_iter *from)
{
	struct file *file = iocb->ki_filp;
	struct configfs_buffer *buffer = file->private_data;
	void *tbuf = NULL;
	size_t end_offset;
	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 = true;

	/* buffer grows? */
	end_offset = iocb->ki_pos + iov_iter_count(from);
	if (end_offset > buffer->bin_buffer_size) {
		if (buffer->cb_max_size && end_offset > buffer->cb_max_size) {
			len = -EFBIG;
			goto out;
		}

		tbuf = vmalloc(end_offset);
		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,
			end_offset - buffer->bin_buffer_size);
		buffer->bin_buffer = tbuf;
		buffer->bin_buffer_size = end_offset;
	}

	len = copy_from_iter(buffer->bin_buffer + iocb->ki_pos,
			     buffer->bin_buffer_size - iocb->ki_pos, from);
	iocb->ki_pos += len;
out:
	mutex_unlock(&buffer->mutex);
	return len ? : -EFAULT;
}

static int __configfs_open_file(struct inode *inode, struct file *file, int type)
{
	struct dentry *dentry = file->f_path.dentry;
	struct configfs_fragment *frag = to_frag(file);
	struct configfs_attribute *attr;
	struct configfs_buffer *buffer;
	int error;

	error = -ENOMEM;
	buffer = kzalloc(sizeof(struct configfs_buffer), GFP_KERNEL);
	if (!buffer)
		goto out;

	error = -ENOENT;
	down_read(&frag->frag_sem);
	if (unlikely(frag->frag_dead))
		goto out_free_buffer;

	error = -EINVAL;
	buffer->item = to_item(dentry->d_parent);
	if (!buffer->item)
		goto out_free_buffer;

	attr = to_attr(dentry);
	if (!attr)
		goto out_free_buffer;

	if (type & CONFIGFS_ITEM_BIN_ATTR) {
		buffer->bin_attr = to_bin_attr(dentry);
		buffer->cb_max_size = buffer->bin_attr->cb_max_size;
	} else {
		buffer->attr = attr;
	}

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

	error = -EACCES;
	if (!buffer->item->ci_type)
		goto out_put_module;

	buffer->ops = buffer->item->ci_type->ct_item_ops;

	/* 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 out_put_module;
		if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
			goto out_put_module;
		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write)
			goto out_put_module;
	}

	/* 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 out_put_module;
		if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
			goto out_put_module;
		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read)
			goto out_put_module;
	}

	mutex_init(&buffer->mutex);
	buffer->needs_read_fill = 1;
	buffer->read_in_progress = false;
	buffer->write_in_progress = false;
	file->private_data = buffer;
	up_read(&frag->frag_sem);
	return 0;

out_put_module:
	module_put(buffer->owner);
out_free_buffer:
	up_read(&frag->frag_sem);
	kfree(buffer);
out:
	return error;
}

static int configfs_release(struct inode *inode, struct file *filp)
{
	struct configfs_buffer *buffer = filp->private_data;

	module_put(buffer->owner);
	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 __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR);
}

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

static int configfs_release_bin_file(struct inode *inode, struct file *file)
{
	struct configfs_buffer *buffer = file->private_data;

	if (buffer->write_in_progress) {
		struct configfs_fragment *frag = to_frag(file);

		down_read(&frag->frag_sem);
		if (!frag->frag_dead) {
			/* result of ->release() is ignored */
			buffer->bin_attr->write(buffer->item,
					buffer->bin_buffer,
					buffer->bin_buffer_size);
		}
		up_read(&frag->frag_sem);
	}

	vfree(buffer->bin_buffer);

	configfs_release(inode, file);
	return 0;
}


const struct file_operations configfs_file_operations = {
	.read_iter	= configfs_read_iter,
	.write_iter	= configfs_write_iter,
	.llseek		= generic_file_llseek,
	.open		= configfs_open_file,
	.release	= configfs_release,
};

const struct file_operations configfs_bin_file_operations = {
	.read_iter	= configfs_bin_read_iter,
	.write_iter	= configfs_bin_write_iter,
	.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, parent_sd->s_frag);
	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.
 *	@bin_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, parent_sd->s_frag);
	inode_unlock(dir->d_inode);

	return error;
}
Commit	Line	Data
328970de	1	// SPDX-License-Identifier: GPL-2.0-or-later
fa60ce2c	2	/*
7063fbf2 JB	3	* file.c - operations for regular (text) files.
7063fbf2 JB	4	*
7063fbf2 JB	5	* Based on sysfs:
	6	* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
	7	*
	8	* configfs Copyright (C) 2005 Oracle. All rights reserved.
	9	*/
	10
	11	#include <linux/fs.h>
	12	#include <linux/module.h>
7063fbf2	13	#include <linux/slab.h>
6d748924	14	#include <linux/mutex.h>
03607ace	15	#include <linux/vmalloc.h>
7c0f6ba6	16	#include <linux/uaccess.h>
7fe1e79b	17	#include <linux/uio.h>
7063fbf2 JB	18	#include <linux/configfs.h>
	19	#include "configfs_internal.h"
	20
b23cdde4 JB	21	/*
	22	* A simple attribute can only be 4096 characters. Why 4k? Because the
	23	* original code limited it to PAGE_SIZE. That's a bad idea, though,
	24	* because an attribute of 16k on ia64 won't work on x86. So we limit to
	25	* 4k, our minimum common page size.
	26	*/
	27	#define SIMPLE_ATTR_SIZE 4096
7063fbf2 JB	28
	29	struct configfs_buffer {
	30	size_t count;
	31	loff_t pos;
	32	char * page;
	33	struct configfs_item_operations * ops;
6d748924	34	struct mutex mutex;
7063fbf2	35	int needs_read_fill;
03607ace PA	36	bool read_in_progress;
	37	bool write_in_progress;
	38	char *bin_buffer;
	39	int bin_buffer_size;
ff4dd081 AV	40	int cb_max_size;
	41	struct config_item *item;
	42	struct module *owner;
	43	union {
	44	struct configfs_attribute *attr;
	45	struct configfs_bin_attribute *bin_attr;
	46	};
7063fbf2 JB	47	};
7063fbf2 JB	48
b0841eef AV	49	static inline struct configfs_fragment to_frag(struct file file)
	50	{
	51	struct configfs_dirent *sd = file->f_path.dentry->d_fsdata;
	52
	53	return sd->s_frag;
	54	}
7063fbf2	55
b0841eef	56	static int fill_read_buffer(struct file file, struct configfs_buffer buffer)
7063fbf2	57	{
b0841eef AV	58	struct configfs_fragment *frag = to_frag(file);
b0841eef AV	59	ssize_t count = -ENOENT;
7063fbf2 JB	60
	61	if (!buffer->page)
	62	buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
	63	if (!buffer->page)
	64	return -ENOMEM;
	65
b0841eef AV	66	down_read(&frag->frag_sem);
	67	if (!frag->frag_dead)
	68	count = buffer->attr->show(buffer->item, buffer->page);
	69	up_read(&frag->frag_sem);
	70
ff4dd081 AV	71	if (count < 0)
	72	return count;
	73	if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))
	74	return -EIO;
ff4dd081 AV	75	buffer->needs_read_fill = 0;
	76	buffer->count = count;
	77	return 0;
7063fbf2 JB	78	}
7063fbf2 JB	79
7fe1e79b	80	static ssize_t configfs_read_iter(struct kiocb iocb, struct iov_iter to)
7063fbf2	81	{
7fe1e79b	82	struct file *file = iocb->ki_filp;
ff4dd081	83	struct configfs_buffer *buffer = file->private_data;
7063fbf2 JB	84	ssize_t retval = 0;
7063fbf2 JB	85
6d748924	86	mutex_lock(&buffer->mutex);
7063fbf2	87	if (buffer->needs_read_fill) {
b0841eef	88	retval = fill_read_buffer(file, buffer);
ff4dd081	89	if (retval)
7063fbf2 JB	90	goto out;
7063fbf2 JB	91	}
7fe1e79b BVA	92	pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
7fe1e79b BVA	93	__func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
420405ec BVA	94	if (iocb->ki_pos >= buffer->count)
	95	goto out;
	96	retval = copy_to_iter(buffer->page + iocb->ki_pos,
	97	buffer->count - iocb->ki_pos, to);
7fe1e79b BVA	98	iocb->ki_pos += retval;
	99	if (retval == 0)
	100	retval = -EFAULT;
7063fbf2	101	out:
6d748924	102	mutex_unlock(&buffer->mutex);
7063fbf2 JB	103	return retval;
	104	}
	105
7fe1e79b	106	static ssize_t configfs_bin_read_iter(struct kiocb iocb, struct iov_iter to)
03607ace	107	{
7fe1e79b	108	struct file *file = iocb->ki_filp;
b0841eef	109	struct configfs_fragment *frag = to_frag(file);
03607ace	110	struct configfs_buffer *buffer = file->private_data;
03607ace	111	ssize_t retval = 0;
7fe1e79b	112	ssize_t len;
03607ace PA	113
	114	mutex_lock(&buffer->mutex);
	115
	116	/* we don't support switching read/write modes */
	117	if (buffer->write_in_progress) {
	118	retval = -ETXTBSY;
	119	goto out;
	120	}
3f6928c3	121	buffer->read_in_progress = true;
03607ace PA	122
	123	if (buffer->needs_read_fill) {
	124	/* perform first read with buf == NULL to get extent */
b0841eef AV	125	down_read(&frag->frag_sem);
	126	if (!frag->frag_dead)
	127	len = buffer->bin_attr->read(buffer->item, NULL, 0);
	128	else
	129	len = -ENOENT;
	130	up_read(&frag->frag_sem);
03607ace PA	131	if (len <= 0) {
	132	retval = len;
	133	goto out;
	134	}
	135
	136	/* do not exceed the maximum value */
ff4dd081	137	if (buffer->cb_max_size && len > buffer->cb_max_size) {
03607ace PA	138	retval = -EFBIG;
	139	goto out;
	140	}
	141
	142	buffer->bin_buffer = vmalloc(len);
	143	if (buffer->bin_buffer == NULL) {
	144	retval = -ENOMEM;
	145	goto out;
	146	}
	147	buffer->bin_buffer_size = len;
	148
	149	/* perform second read to fill buffer */
b0841eef AV	150	down_read(&frag->frag_sem);
	151	if (!frag->frag_dead)
	152	len = buffer->bin_attr->read(buffer->item,
	153	buffer->bin_buffer, len);
	154	else
	155	len = -ENOENT;
	156	up_read(&frag->frag_sem);
03607ace PA	157	if (len < 0) {
	158	retval = len;
	159	vfree(buffer->bin_buffer);
	160	buffer->bin_buffer_size = 0;
	161	buffer->bin_buffer = NULL;
	162	goto out;
	163	}
	164
	165	buffer->needs_read_fill = 0;
	166	}
	167
420405ec BVA	168	if (iocb->ki_pos >= buffer->bin_buffer_size)
	169	goto out;
	170	retval = copy_to_iter(buffer->bin_buffer + iocb->ki_pos,
	171	buffer->bin_buffer_size - iocb->ki_pos, to);
7fe1e79b BVA	172	iocb->ki_pos += retval;
	173	if (retval == 0)
	174	retval = -EFAULT;
03607ace PA	175	out:
	176	mutex_unlock(&buffer->mutex);
	177	return retval;
	178	}
	179
769f5267 BVA	180	/* Fill @buffer with data coming from @from. */
769f5267 BVA	181	static int fill_write_buffer(struct configfs_buffer *buffer,
7fe1e79b	182	struct iov_iter *from)
7063fbf2	183	{
7fe1e79b	184	int copied;
7063fbf2 JB	185
7063fbf2 JB	186	if (!buffer->page)
ff05d1c4	187	buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
7063fbf2 JB	188	if (!buffer->page)
	189	return -ENOMEM;
	190
769f5267	191	copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
7063fbf2	192	buffer->needs_read_fill = 1;
ff05d1c4 JB	193	/* if buf is assumed to contain a string, terminate it by \0,
ff05d1c4 JB	194	* so e.g. sscanf() can scan the string easily */
769f5267	195	buffer->page[copied] = 0;
7fe1e79b	196	return copied ? : -EFAULT;
7063fbf2 JB	197	}
7063fbf2 JB	198
7063fbf2	199	static int
b0841eef	200	flush_write_buffer(struct file file, struct configfs_buffer buffer, size_t count)
7063fbf2	201	{
b0841eef AV	202	struct configfs_fragment *frag = to_frag(file);
	203	int res = -ENOENT;
	204
	205	down_read(&frag->frag_sem);
	206	if (!frag->frag_dead)
	207	res = buffer->attr->store(buffer->item, buffer->page, count);
	208	up_read(&frag->frag_sem);
	209	return res;
7063fbf2 JB	210	}
	211
	212
44b9a000 CH	213	/*
	214	* There is no easy way for us to know if userspace is only doing a partial
	215	* write, so we don't support them. We expect the entire buffer to come on the
	216	* first write.
	217	* Hint: if you're writing a value, first read the file, modify only the value
	218	* you're changing, then write entire buffer back.
7063fbf2	219	*/
7fe1e79b	220	static ssize_t configfs_write_iter(struct kiocb iocb, struct iov_iter from)
7063fbf2	221	{
7fe1e79b	222	struct file *file = iocb->ki_filp;
ff4dd081	223	struct configfs_buffer *buffer = file->private_data;
769f5267	224	int len;
7063fbf2	225
6d748924	226	mutex_lock(&buffer->mutex);
769f5267	227	len = fill_write_buffer(buffer, from);
3d0f89bb	228	if (len > 0)
b0841eef	229	len = flush_write_buffer(file, buffer, len);
3d0f89bb	230	if (len > 0)
7fe1e79b	231	iocb->ki_pos += len;
6d748924	232	mutex_unlock(&buffer->mutex);
3d0f89bb	233	return len;
7063fbf2 JB	234	}
7063fbf2 JB	235
7fe1e79b BVA	236	static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
7fe1e79b BVA	237	struct iov_iter *from)
03607ace	238	{
7fe1e79b	239	struct file *file = iocb->ki_filp;
03607ace	240	struct configfs_buffer *buffer = file->private_data;
03607ace	241	void *tbuf = NULL;
7fe1e79b	242	size_t end_offset;
03607ace PA	243	ssize_t len;
	244
	245	mutex_lock(&buffer->mutex);
	246
	247	/* we don't support switching read/write modes */
	248	if (buffer->read_in_progress) {
	249	len = -ETXTBSY;
	250	goto out;
	251	}
3f6928c3	252	buffer->write_in_progress = true;
03607ace PA	253
03607ace PA	254	/* buffer grows? */
7fe1e79b BVA	255	end_offset = iocb->ki_pos + iov_iter_count(from);
	256	if (end_offset > buffer->bin_buffer_size) {
	257	if (buffer->cb_max_size && end_offset > buffer->cb_max_size) {
03607ace	258	len = -EFBIG;
42857cf5	259	goto out;
03607ace PA	260	}
03607ace PA	261
7fe1e79b	262	tbuf = vmalloc(end_offset);
03607ace PA	263	if (tbuf == NULL) {
	264	len = -ENOMEM;
	265	goto out;
	266	}
	267
	268	/* copy old contents */
	269	if (buffer->bin_buffer) {
	270	memcpy(tbuf, buffer->bin_buffer,
	271	buffer->bin_buffer_size);
	272	vfree(buffer->bin_buffer);
	273	}
	274
	275	/* clear the new area */
	276	memset(tbuf + buffer->bin_buffer_size, 0,
7fe1e79b	277	end_offset - buffer->bin_buffer_size);
03607ace	278	buffer->bin_buffer = tbuf;
7fe1e79b	279	buffer->bin_buffer_size = end_offset;
03607ace PA	280	}
03607ace PA	281
420405ec BVA	282	len = copy_from_iter(buffer->bin_buffer + iocb->ki_pos,
	283	buffer->bin_buffer_size - iocb->ki_pos, from);
	284	iocb->ki_pos += len;
03607ace PA	285	out:
03607ace PA	286	mutex_unlock(&buffer->mutex);
7fe1e79b	287	return len ? : -EFAULT;
03607ace PA	288	}
03607ace PA	289
ff4dd081	290	static int __configfs_open_file(struct inode inode, struct file file, int type)
7063fbf2	291	{
ff4dd081	292	struct dentry *dentry = file->f_path.dentry;
b0841eef	293	struct configfs_fragment *frag = to_frag(file);
ff4dd081 AV	294	struct configfs_attribute *attr;
	295	struct configfs_buffer *buffer;
	296	int error;
7063fbf2	297
ff4dd081 AV	298	error = -ENOMEM;
	299	buffer = kzalloc(sizeof(struct configfs_buffer), GFP_KERNEL);
	300	if (!buffer)
	301	goto out;
7063fbf2	302
b0841eef AV	303	error = -ENOENT;
	304	down_read(&frag->frag_sem);
	305	if (unlikely(frag->frag_dead))
	306	goto out_free_buffer;
	307
ff4dd081	308	error = -EINVAL;
b0841eef	309	buffer->item = to_item(dentry->d_parent);
ff4dd081 AV	310	if (!buffer->item)
	311	goto out_free_buffer;
	312
	313	attr = to_attr(dentry);
	314	if (!attr)
14fbbc82	315	goto out_free_buffer;
ff4dd081 AV	316
	317	if (type & CONFIGFS_ITEM_BIN_ATTR) {
	318	buffer->bin_attr = to_bin_attr(dentry);
	319	buffer->cb_max_size = buffer->bin_attr->cb_max_size;
	320	} else {
	321	buffer->attr = attr;
	322	}
03607ace	323
ff4dd081	324	buffer->owner = attr->ca_owner;
7063fbf2	325	/* Grab the module reference for this attribute if we have one */
ff4dd081 AV	326	error = -ENODEV;
ff4dd081 AV	327	if (!try_module_get(buffer->owner))
14fbbc82	328	goto out_free_buffer;
7063fbf2	329
ff4dd081 AV	330	error = -EACCES;
	331	if (!buffer->item->ci_type)
	332	goto out_put_module;
	333
	334	buffer->ops = buffer->item->ci_type->ct_item_ops;
7063fbf2 JB	335
	336	/* File needs write support.
	337	* The inode's perms must say it's ok,
	338	* and we must have a store method.
	339	*/
	340	if (file->f_mode & FMODE_WRITE) {
03607ace	341	if (!(inode->i_mode & S_IWUGO))
ff4dd081	342	goto out_put_module;
03607ace	343	if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
ff4dd081 AV	344	goto out_put_module;
	345	if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write)
	346	goto out_put_module;
7063fbf2 JB	347	}
	348
	349	/* File needs read support.
	350	* The inode's perms must say it's ok, and we there
	351	* must be a show method for it.
	352	*/
	353	if (file->f_mode & FMODE_READ) {
03607ace	354	if (!(inode->i_mode & S_IRUGO))
ff4dd081	355	goto out_put_module;
03607ace	356	if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
ff4dd081 AV	357	goto out_put_module;
	358	if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read)
	359	goto out_put_module;
7063fbf2 JB	360	}
7063fbf2 JB	361
6d748924	362	mutex_init(&buffer->mutex);
559c9ac3	363	buffer->needs_read_fill = 1;
3f6928c3 TM	364	buffer->read_in_progress = false;
3f6928c3 TM	365	buffer->write_in_progress = false;
559c9ac3	366	file->private_data = buffer;
b0841eef	367	up_read(&frag->frag_sem);
ff4dd081	368	return 0;
7063fbf2	369
ff4dd081 AV	370	out_put_module:
ff4dd081 AV	371	module_put(buffer->owner);
ff4dd081	372	out_free_buffer:
b0841eef	373	up_read(&frag->frag_sem);
ff4dd081 AV	374	kfree(buffer);
ff4dd081 AV	375	out:
7063fbf2 JB	376	return error;
	377	}
	378
03607ace	379	static int configfs_release(struct inode inode, struct file filp)
7063fbf2	380	{
ff4dd081 AV	381	struct configfs_buffer *buffer = filp->private_data;
ff4dd081 AV	382
ff4dd081 AV	383	module_put(buffer->owner);
	384	if (buffer->page)
	385	free_page((unsigned long)buffer->page);
	386	mutex_destroy(&buffer->mutex);
	387	kfree(buffer);
7063fbf2 JB	388	return 0;
	389	}
	390
03607ace PA	391	static int configfs_open_file(struct inode inode, struct file filp)
03607ace PA	392	{
ff4dd081	393	return __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR);
03607ace PA	394	}
	395
	396	static int configfs_open_bin_file(struct inode inode, struct file filp)
	397	{
ff4dd081	398	return __configfs_open_file(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
03607ace PA	399	}
03607ace PA	400
ff4dd081	401	static int configfs_release_bin_file(struct inode inode, struct file file)
03607ace	402	{
ff4dd081	403	struct configfs_buffer *buffer = file->private_data;
03607ace	404
03607ace	405	if (buffer->write_in_progress) {
b0841eef	406	struct configfs_fragment *frag = to_frag(file);
03607ace	407
b0841eef AV	408	down_read(&frag->frag_sem);
	409	if (!frag->frag_dead) {
	410	/* result of ->release() is ignored */
	411	buffer->bin_attr->write(buffer->item,
	412	buffer->bin_buffer,
	413	buffer->bin_buffer_size);
	414	}
	415	up_read(&frag->frag_sem);
03607ace PA	416	}
03607ace PA	417
3c252b08	418	vfree(buffer->bin_buffer);
3c252b08	419
ff4dd081 AV	420	configfs_release(inode, file);
ff4dd081 AV	421	return 0;
03607ace PA	422	}
	423
	424
4b6f5d20	425	const struct file_operations configfs_file_operations = {
7fe1e79b BVA	426	.read_iter = configfs_read_iter,
7fe1e79b BVA	427	.write_iter = configfs_write_iter,
7063fbf2 JB	428	.llseek = generic_file_llseek,
	429	.open = configfs_open_file,
	430	.release = configfs_release,
	431	};
	432
03607ace	433	const struct file_operations configfs_bin_file_operations = {
7fe1e79b BVA	434	.read_iter = configfs_bin_read_iter,
7fe1e79b BVA	435	.write_iter = configfs_bin_write_iter,
03607ace PA	436	.llseek = NULL, /* bin file is not seekable */
	437	.open = configfs_open_bin_file,
	438	.release = configfs_release_bin_file,
	439	};
	440
7063fbf2 JB	441	/**
	442	* configfs_create_file - create an attribute file for an item.
	443	* @item: item we're creating for.
	444	* @attr: atrribute descriptor.
	445	*/
	446
	447	int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
	448	{
28444a2b AV	449	struct dentry *dir = item->ci_dentry;
	450	struct configfs_dirent *parent_sd = dir->d_fsdata;
	451	umode_t mode = (attr->ca_mode & S_IALLUGO) \| S_IFREG;
	452	int error = 0;
7063fbf2	453
5955102c	454	inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
28444a2b	455	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
47320fbe	456	CONFIGFS_ITEM_ATTR, parent_sd->s_frag);
5955102c	457	inode_unlock(d_inode(dir));
28444a2b AV	458
28444a2b AV	459	return error;
7063fbf2 JB	460	}
7063fbf2 JB	461
03607ace PA	462	/**
	463	* configfs_create_bin_file - create a binary attribute file for an item.
	464	* @item: item we're creating for.
dd33f1f7	465	* @bin_attr: atrribute descriptor.
03607ace PA	466	*/
	467
	468	int configfs_create_bin_file(struct config_item *item,
	469	const struct configfs_bin_attribute *bin_attr)
	470	{
	471	struct dentry *dir = item->ci_dentry;
	472	struct configfs_dirent *parent_sd = dir->d_fsdata;
	473	umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) \| S_IFREG;
	474	int error = 0;
	475
5955102c	476	inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
03607ace	477	error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
47320fbe	478	CONFIGFS_ITEM_BIN_ATTR, parent_sd->s_frag);
5955102c	479	inode_unlock(dir->d_inode);
03607ace PA	480
	481	return error;
	482	}