Loading...
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>
29#include <linux/slab.h>
30#include <linux/mutex.h>
31#include <asm/uaccess.h>
32
33#include <linux/configfs.h>
34#include "configfs_internal.h"
35
36/*
37 * A simple attribute can only be 4096 characters. Why 4k? Because the
38 * original code limited it to PAGE_SIZE. That's a bad idea, though,
39 * because an attribute of 16k on ia64 won't work on x86. So we limit to
40 * 4k, our minimum common page size.
41 */
42#define SIMPLE_ATTR_SIZE 4096
43
44struct configfs_buffer {
45 size_t count;
46 loff_t pos;
47 char * page;
48 struct configfs_item_operations * ops;
49 struct mutex mutex;
50 int needs_read_fill;
51};
52
53
54/**
55 * fill_read_buffer - allocate and fill buffer from item.
56 * @dentry: dentry pointer.
57 * @buffer: data buffer for file.
58 *
59 * Allocate @buffer->page, if it hasn't been already, then call the
60 * config_item's show() method to fill the buffer with this attribute's
61 * data.
62 * This is called only once, on the file's first read.
63 */
64static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
65{
66 struct configfs_attribute * attr = to_attr(dentry);
67 struct config_item * item = to_item(dentry->d_parent);
68 struct configfs_item_operations * ops = buffer->ops;
69 int ret = 0;
70 ssize_t count;
71
72 if (!buffer->page)
73 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
74 if (!buffer->page)
75 return -ENOMEM;
76
77 count = ops->show_attribute(item,attr,buffer->page);
78 buffer->needs_read_fill = 0;
79 BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
80 if (count >= 0)
81 buffer->count = count;
82 else
83 ret = count;
84 return ret;
85}
86
87/**
88 * configfs_read_file - read an attribute.
89 * @file: file pointer.
90 * @buf: buffer to fill.
91 * @count: number of bytes to read.
92 * @ppos: starting offset in file.
93 *
94 * Userspace wants to read an attribute file. The attribute descriptor
95 * is in the file's ->d_fsdata. The target item is in the directory's
96 * ->d_fsdata.
97 *
98 * We call fill_read_buffer() to allocate and fill the buffer from the
99 * item's show() method exactly once (if the read is happening from
100 * the beginning of the file). That should fill the entire buffer with
101 * all the data the item has to offer for that attribute.
102 * We then call flush_read_buffer() to copy the buffer to userspace
103 * in the increments specified.
104 */
105
106static ssize_t
107configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
108{
109 struct configfs_buffer * buffer = file->private_data;
110 ssize_t retval = 0;
111
112 mutex_lock(&buffer->mutex);
113 if (buffer->needs_read_fill) {
114 if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
115 goto out;
116 }
117 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
118 __func__, count, *ppos, buffer->page);
119 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
120 buffer->count);
121out:
122 mutex_unlock(&buffer->mutex);
123 return retval;
124}
125
126
127/**
128 * fill_write_buffer - copy buffer from userspace.
129 * @buffer: data buffer for file.
130 * @buf: data from user.
131 * @count: number of bytes in @userbuf.
132 *
133 * Allocate @buffer->page if it hasn't been already, then
134 * copy the user-supplied buffer into it.
135 */
136
137static int
138fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
139{
140 int error;
141
142 if (!buffer->page)
143 buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
144 if (!buffer->page)
145 return -ENOMEM;
146
147 if (count >= SIMPLE_ATTR_SIZE)
148 count = SIMPLE_ATTR_SIZE - 1;
149 error = copy_from_user(buffer->page,buf,count);
150 buffer->needs_read_fill = 1;
151 /* if buf is assumed to contain a string, terminate it by \0,
152 * so e.g. sscanf() can scan the string easily */
153 buffer->page[count] = 0;
154 return error ? -EFAULT : count;
155}
156
157
158/**
159 * flush_write_buffer - push buffer to config_item.
160 * @dentry: dentry to the attribute
161 * @buffer: data buffer for file.
162 * @count: number of bytes
163 *
164 * Get the correct pointers for the config_item and the attribute we're
165 * dealing with, then call the store() method for the attribute,
166 * passing the buffer that we acquired in fill_write_buffer().
167 */
168
169static int
170flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
171{
172 struct configfs_attribute * attr = to_attr(dentry);
173 struct config_item * item = to_item(dentry->d_parent);
174 struct configfs_item_operations * ops = buffer->ops;
175
176 return ops->store_attribute(item,attr,buffer->page,count);
177}
178
179
180/**
181 * configfs_write_file - write an attribute.
182 * @file: file pointer
183 * @buf: data to write
184 * @count: number of bytes
185 * @ppos: starting offset
186 *
187 * Similar to configfs_read_file(), though working in the opposite direction.
188 * We allocate and fill the data from the user in fill_write_buffer(),
189 * then push it to the config_item in flush_write_buffer().
190 * There is no easy way for us to know if userspace is only doing a partial
191 * write, so we don't support them. We expect the entire buffer to come
192 * on the first write.
193 * Hint: if you're writing a value, first read the file, modify only the
194 * the value you're changing, then write entire buffer back.
195 */
196
197static ssize_t
198configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
199{
200 struct configfs_buffer * buffer = file->private_data;
201 ssize_t len;
202
203 mutex_lock(&buffer->mutex);
204 len = fill_write_buffer(buffer, buf, count);
205 if (len > 0)
206 len = flush_write_buffer(file->f_path.dentry, buffer, count);
207 if (len > 0)
208 *ppos += len;
209 mutex_unlock(&buffer->mutex);
210 return len;
211}
212
213static int check_perm(struct inode * inode, struct file * file)
214{
215 struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
216 struct configfs_attribute * attr = to_attr(file->f_path.dentry);
217 struct configfs_buffer * buffer;
218 struct configfs_item_operations * ops = NULL;
219 int error = 0;
220
221 if (!item || !attr)
222 goto Einval;
223
224 /* Grab the module reference for this attribute if we have one */
225 if (!try_module_get(attr->ca_owner)) {
226 error = -ENODEV;
227 goto Done;
228 }
229
230 if (item->ci_type)
231 ops = item->ci_type->ct_item_ops;
232 else
233 goto Eaccess;
234
235 /* File needs write support.
236 * The inode's perms must say it's ok,
237 * and we must have a store method.
238 */
239 if (file->f_mode & FMODE_WRITE) {
240
241 if (!(inode->i_mode & S_IWUGO) || !ops->store_attribute)
242 goto Eaccess;
243
244 }
245
246 /* File needs read support.
247 * The inode's perms must say it's ok, and we there
248 * must be a show method for it.
249 */
250 if (file->f_mode & FMODE_READ) {
251 if (!(inode->i_mode & S_IRUGO) || !ops->show_attribute)
252 goto Eaccess;
253 }
254
255 /* No error? Great, allocate a buffer for the file, and store it
256 * it in file->private_data for easy access.
257 */
258 buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
259 if (!buffer) {
260 error = -ENOMEM;
261 goto Enomem;
262 }
263 mutex_init(&buffer->mutex);
264 buffer->needs_read_fill = 1;
265 buffer->ops = ops;
266 file->private_data = buffer;
267 goto Done;
268
269 Einval:
270 error = -EINVAL;
271 goto Done;
272 Eaccess:
273 error = -EACCES;
274 Enomem:
275 module_put(attr->ca_owner);
276 Done:
277 if (error && item)
278 config_item_put(item);
279 return error;
280}
281
282static int configfs_open_file(struct inode * inode, struct file * filp)
283{
284 return check_perm(inode,filp);
285}
286
287static int configfs_release(struct inode * inode, struct file * filp)
288{
289 struct config_item * item = to_item(filp->f_path.dentry->d_parent);
290 struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
291 struct module * owner = attr->ca_owner;
292 struct configfs_buffer * buffer = filp->private_data;
293
294 if (item)
295 config_item_put(item);
296 /* After this point, attr should not be accessed. */
297 module_put(owner);
298
299 if (buffer) {
300 if (buffer->page)
301 free_page((unsigned long)buffer->page);
302 mutex_destroy(&buffer->mutex);
303 kfree(buffer);
304 }
305 return 0;
306}
307
308const struct file_operations configfs_file_operations = {
309 .read = configfs_read_file,
310 .write = configfs_write_file,
311 .llseek = generic_file_llseek,
312 .open = configfs_open_file,
313 .release = configfs_release,
314};
315
316
317int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
318{
319 struct configfs_dirent * parent_sd = dir->d_fsdata;
320 umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
321 int error = 0;
322
323 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_NORMAL);
324 error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
325 mutex_unlock(&dir->d_inode->i_mutex);
326
327 return error;
328}
329
330
331/**
332 * configfs_create_file - create an attribute file for an item.
333 * @item: item we're creating for.
334 * @attr: atrribute descriptor.
335 */
336
337int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
338{
339 BUG_ON(!item || !item->ci_dentry || !attr);
340
341 return configfs_add_file(item->ci_dentry, attr,
342 CONFIGFS_ITEM_ATTR);
343}
344
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>
29#include <linux/slab.h>
30#include <linux/mutex.h>
31#include <linux/vmalloc.h>
32#include <linux/uaccess.h>
33
34#include <linux/configfs.h>
35#include "configfs_internal.h"
36
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
44
45struct configfs_buffer {
46 size_t count;
47 loff_t pos;
48 char * page;
49 struct configfs_item_operations * ops;
50 struct mutex mutex;
51 int needs_read_fill;
52 bool read_in_progress;
53 bool write_in_progress;
54 char *bin_buffer;
55 int bin_buffer_size;
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 */
69static 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);
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
81 count = attr->show(item, buffer->page);
82
83 BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
84 if (count >= 0) {
85 buffer->needs_read_fill = 0;
86 buffer->count = count;
87 } else
88 ret = count;
89 return ret;
90}
91
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
111static ssize_t
112configfs_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
117 mutex_lock(&buffer->mutex);
118 if (buffer->needs_read_fill) {
119 if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
120 goto out;
121 }
122 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
123 __func__, count, *ppos, buffer->page);
124 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
125 buffer->count);
126out:
127 mutex_unlock(&buffer->mutex);
128 return retval;
129}
130
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
151static ssize_t
152configfs_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);
207out:
208 mutex_unlock(&buffer->mutex);
209 return retval;
210}
211
212
213/**
214 * fill_write_buffer - copy buffer from userspace.
215 * @buffer: data buffer for file.
216 * @buf: data from user.
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
223static int
224fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
225{
226 int error;
227
228 if (!buffer->page)
229 buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
230 if (!buffer->page)
231 return -ENOMEM;
232
233 if (count >= SIMPLE_ATTR_SIZE)
234 count = SIMPLE_ATTR_SIZE - 1;
235 error = copy_from_user(buffer->page,buf,count);
236 buffer->needs_read_fill = 1;
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;
240 return error ? -EFAULT : count;
241}
242
243
244/**
245 * flush_write_buffer - push buffer to config_item.
246 * @dentry: dentry to the attribute
247 * @buffer: data buffer for file.
248 * @count: number of bytes
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
255static int
256flush_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);
260
261 return attr->store(item, buffer->page, count);
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
282static ssize_t
283configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
284{
285 struct configfs_buffer * buffer = file->private_data;
286 ssize_t len;
287
288 mutex_lock(&buffer->mutex);
289 len = fill_write_buffer(buffer, buf, count);
290 if (len > 0)
291 len = flush_write_buffer(file->f_path.dentry, buffer, len);
292 if (len > 0)
293 *ppos += len;
294 mutex_unlock(&buffer->mutex);
295 return len;
296}
297
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
311static ssize_t
312configfs_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;
336 goto out;
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);
361out:
362 mutex_unlock(&buffer->mutex);
363 return len;
364}
365
366static int check_perm(struct inode * inode, struct file * file, int type)
367{
368 struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
369 struct configfs_attribute * attr = to_attr(file->f_path.dentry);
370 struct configfs_bin_attribute *bin_attr = NULL;
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
378 if (type & CONFIGFS_ITEM_BIN_ATTR)
379 bin_attr = to_bin_attr(file->f_path.dentry);
380
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) {
397 if (!(inode->i_mode & S_IWUGO))
398 goto Eaccess;
399
400 if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
401 goto Eaccess;
402
403 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
404 goto Eaccess;
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) {
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)
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 */
425 buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
426 if (!buffer) {
427 error = -ENOMEM;
428 goto Enomem;
429 }
430 mutex_init(&buffer->mutex);
431 buffer->needs_read_fill = 1;
432 buffer->read_in_progress = 0;
433 buffer->write_in_progress = 0;
434 buffer->ops = ops;
435 file->private_data = buffer;
436 goto Done;
437
438 Einval:
439 error = -EINVAL;
440 goto Done;
441 Eaccess:
442 error = -EACCES;
443 Enomem:
444 module_put(attr->ca_owner);
445 Done:
446 if (error && item)
447 config_item_put(item);
448 return error;
449}
450
451static int configfs_release(struct inode *inode, struct file *filp)
452{
453 struct config_item * item = to_item(filp->f_path.dentry->d_parent);
454 struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
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);
466 mutex_destroy(&buffer->mutex);
467 kfree(buffer);
468 }
469 return 0;
470}
471
472static int configfs_open_file(struct inode *inode, struct file *filp)
473{
474 return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
475}
476
477static int configfs_open_bin_file(struct inode *inode, struct file *filp)
478{
479 return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
480}
481
482static 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
513const struct file_operations configfs_file_operations = {
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
521const 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
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
535int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
536{
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;
541
542 inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
543 error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
544 CONFIGFS_ITEM_ATTR);
545 inode_unlock(d_inode(dir));
546
547 return error;
548}
549
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
556int 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
564 inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
565 error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
566 CONFIGFS_ITEM_BIN_ATTR);
567 inode_unlock(dir->d_inode);
568
569 return error;
570}