Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1/*
2 * inode.c - basic inode and dentry operations.
3 *
4 * sysfs is Copyright (c) 2001-3 Patrick Mochel
5 *
6 * Please see Documentation/filesystems/sysfs.txt for more information.
7 */
8
9#undef DEBUG
10
11#include <linux/pagemap.h>
12#include <linux/namei.h>
13#include <linux/backing-dev.h>
14#include <linux/capability.h>
15#include <linux/errno.h>
16#include <linux/sched.h>
17#include <asm/semaphore.h>
18#include "sysfs.h"
19
20extern struct super_block * sysfs_sb;
21
22static const struct address_space_operations sysfs_aops = {
23 .readpage = simple_readpage,
24 .prepare_write = simple_prepare_write,
25 .commit_write = simple_commit_write
26};
27
28static struct backing_dev_info sysfs_backing_dev_info = {
29 .ra_pages = 0, /* No readahead */
30 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
31};
32
33static const struct inode_operations sysfs_inode_operations ={
34 .setattr = sysfs_setattr,
35};
36
37void sysfs_delete_inode(struct inode *inode)
38{
39 /* Free the shadowed directory inode operations */
40 if (sysfs_is_shadowed_inode(inode)) {
41 kfree(inode->i_op);
42 inode->i_op = NULL;
43 }
44 return generic_delete_inode(inode);
45}
46
47int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
48{
49 struct inode * inode = dentry->d_inode;
50 struct sysfs_dirent * sd = dentry->d_fsdata;
51 struct iattr * sd_iattr;
52 unsigned int ia_valid = iattr->ia_valid;
53 int error;
54
55 if (!sd)
56 return -EINVAL;
57
58 sd_iattr = sd->s_iattr;
59
60 error = inode_change_ok(inode, iattr);
61 if (error)
62 return error;
63
64 error = inode_setattr(inode, iattr);
65 if (error)
66 return error;
67
68 if (!sd_iattr) {
69 /* setting attributes for the first time, allocate now */
70 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
71 if (!sd_iattr)
72 return -ENOMEM;
73 /* assign default attributes */
74 sd_iattr->ia_mode = sd->s_mode;
75 sd_iattr->ia_uid = 0;
76 sd_iattr->ia_gid = 0;
77 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
78 sd->s_iattr = sd_iattr;
79 }
80
81 /* attributes were changed atleast once in past */
82
83 if (ia_valid & ATTR_UID)
84 sd_iattr->ia_uid = iattr->ia_uid;
85 if (ia_valid & ATTR_GID)
86 sd_iattr->ia_gid = iattr->ia_gid;
87 if (ia_valid & ATTR_ATIME)
88 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
89 inode->i_sb->s_time_gran);
90 if (ia_valid & ATTR_MTIME)
91 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
92 inode->i_sb->s_time_gran);
93 if (ia_valid & ATTR_CTIME)
94 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
95 inode->i_sb->s_time_gran);
96 if (ia_valid & ATTR_MODE) {
97 umode_t mode = iattr->ia_mode;
98
99 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
100 mode &= ~S_ISGID;
101 sd_iattr->ia_mode = sd->s_mode = mode;
102 }
103
104 return error;
105}
106
107static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
108{
109 inode->i_mode = mode;
110 inode->i_uid = 0;
111 inode->i_gid = 0;
112 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
113}
114
115static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
116{
117 inode->i_mode = iattr->ia_mode;
118 inode->i_uid = iattr->ia_uid;
119 inode->i_gid = iattr->ia_gid;
120 inode->i_atime = iattr->ia_atime;
121 inode->i_mtime = iattr->ia_mtime;
122 inode->i_ctime = iattr->ia_ctime;
123}
124
125
126/*
127 * sysfs has a different i_mutex lock order behavior for i_mutex than other
128 * filesystems; sysfs i_mutex is called in many places with subsystem locks
129 * held. At the same time, many of the VFS locking rules do not apply to
130 * sysfs at all (cross directory rename for example). To untangle this mess
131 * (which gives false positives in lockdep), we're giving sysfs inodes their
132 * own class for i_mutex.
133 */
134static struct lock_class_key sysfs_inode_imutex_key;
135
136struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
137{
138 struct inode * inode = new_inode(sysfs_sb);
139 if (inode) {
140 inode->i_blocks = 0;
141 inode->i_mapping->a_ops = &sysfs_aops;
142 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
143 inode->i_op = &sysfs_inode_operations;
144 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
145
146 if (sd->s_iattr) {
147 /* sysfs_dirent has non-default attributes
148 * get them for the new inode from persistent copy
149 * in sysfs_dirent
150 */
151 set_inode_attr(inode, sd->s_iattr);
152 } else
153 set_default_inode_attr(inode, mode);
154 }
155 return inode;
156}
157
158int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
159{
160 int error = 0;
161 struct inode * inode = NULL;
162 if (dentry) {
163 if (!dentry->d_inode) {
164 struct sysfs_dirent * sd = dentry->d_fsdata;
165 if ((inode = sysfs_new_inode(mode, sd))) {
166 if (dentry->d_parent && dentry->d_parent->d_inode) {
167 struct inode *p_inode = dentry->d_parent->d_inode;
168 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
169 }
170 goto Proceed;
171 }
172 else
173 error = -ENOMEM;
174 } else
175 error = -EEXIST;
176 } else
177 error = -ENOENT;
178 goto Done;
179
180 Proceed:
181 if (init)
182 error = init(inode);
183 if (!error) {
184 d_instantiate(dentry, inode);
185 if (S_ISDIR(mode))
186 dget(dentry); /* pin only directory dentry in core */
187 } else
188 iput(inode);
189 Done:
190 return error;
191}
192
193/*
194 * Get the name for corresponding element represented by the given sysfs_dirent
195 */
196const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
197{
198 struct attribute * attr;
199 struct bin_attribute * bin_attr;
200 struct sysfs_symlink * sl;
201
202 BUG_ON(!sd || !sd->s_element);
203
204 switch (sd->s_type) {
205 case SYSFS_DIR:
206 /* Always have a dentry so use that */
207 return sd->s_dentry->d_name.name;
208
209 case SYSFS_KOBJ_ATTR:
210 attr = sd->s_element;
211 return attr->name;
212
213 case SYSFS_KOBJ_BIN_ATTR:
214 bin_attr = sd->s_element;
215 return bin_attr->attr.name;
216
217 case SYSFS_KOBJ_LINK:
218 sl = sd->s_element;
219 return sl->link_name;
220 }
221 return NULL;
222}
223
224static inline void orphan_all_buffers(struct inode *node)
225{
226 struct sysfs_buffer_collection *set;
227 struct sysfs_buffer *buf;
228
229 mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD);
230 set = node->i_private;
231 if (set) {
232 list_for_each_entry(buf, &set->associates, associates) {
233 down(&buf->sem);
234 buf->orphaned = 1;
235 up(&buf->sem);
236 }
237 }
238 mutex_unlock(&node->i_mutex);
239}
240
241
242/*
243 * Unhashes the dentry corresponding to given sysfs_dirent
244 * Called with parent inode's i_mutex held.
245 */
246void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
247{
248 struct dentry * dentry = sd->s_dentry;
249 struct inode *inode;
250
251 if (dentry) {
252 spin_lock(&dcache_lock);
253 spin_lock(&dentry->d_lock);
254 if (!(d_unhashed(dentry) && dentry->d_inode)) {
255 inode = dentry->d_inode;
256 spin_lock(&inode->i_lock);
257 __iget(inode);
258 spin_unlock(&inode->i_lock);
259 dget_locked(dentry);
260 __d_drop(dentry);
261 spin_unlock(&dentry->d_lock);
262 spin_unlock(&dcache_lock);
263 simple_unlink(parent->d_inode, dentry);
264 orphan_all_buffers(inode);
265 iput(inode);
266 } else {
267 spin_unlock(&dentry->d_lock);
268 spin_unlock(&dcache_lock);
269 }
270 }
271}
272
273int sysfs_hash_and_remove(struct dentry * dir, const char * name)
274{
275 struct sysfs_dirent * sd;
276 struct sysfs_dirent * parent_sd;
277 int found = 0;
278
279 if (!dir)
280 return -ENOENT;
281
282 if (dir->d_inode == NULL)
283 /* no inode means this hasn't been made visible yet */
284 return -ENOENT;
285
286 parent_sd = dir->d_fsdata;
287 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
288 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
289 if (!sd->s_element)
290 continue;
291 if (!strcmp(sysfs_get_name(sd), name)) {
292 list_del_init(&sd->s_sibling);
293 sysfs_drop_dentry(sd, dir);
294 sysfs_put(sd);
295 found = 1;
296 break;
297 }
298 }
299 mutex_unlock(&dir->d_inode->i_mutex);
300
301 return found ? 0 : -ENOENT;
302}