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