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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080014#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include "sysfs.h"
16
17extern struct super_block * sysfs_sb;
18
19static 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
Maneesh Soni988d1862005-05-31 10:39:14 +053030static 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 */
Eric Sesterhenn58d49282006-02-22 11:18:15 +010057 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
Maneesh Soni988d1862005-05-31 10:39:14 +053058 if (!sd_iattr)
59 return -ENOMEM;
60 /* assign default attributes */
Maneesh Soni988d1862005-05-31 10:39:14 +053061 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;
Maneesh Soni9ca1eb32005-07-29 12:14:19 -070088 sd_iattr->ia_mode = sd->s_mode = mode;
Maneesh Soni988d1862005-05-31 10:39:14 +053089 }
90
91 return error;
92}
93
Maneesh Soni82155342005-05-31 10:39:52 +053094static 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
112struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113{
114 struct inode * inode = new_inode(sysfs_sb);
115 if (inode) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 inode->i_blksize = PAGE_CACHE_SIZE;
117 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 inode->i_mapping->a_ops = &sysfs_aops;
119 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
Maneesh Soni82155342005-05-31 10:39:52 +0530120 inode->i_op = &sysfs_inode_operations;
121
122 if (sd->s_iattr) {
123 /* sysfs_dirent has non-default attributes
124 * get them for the new inode from persistent copy
125 * in sysfs_dirent
126 */
127 set_inode_attr(inode, sd->s_iattr);
128 } else
129 set_default_inode_attr(inode, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 }
131 return inode;
132}
133
134int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
135{
136 int error = 0;
137 struct inode * inode = NULL;
138 if (dentry) {
139 if (!dentry->d_inode) {
Maneesh Soni82155342005-05-31 10:39:52 +0530140 struct sysfs_dirent * sd = dentry->d_fsdata;
141 if ((inode = sysfs_new_inode(mode, sd))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 if (dentry->d_parent && dentry->d_parent->d_inode) {
143 struct inode *p_inode = dentry->d_parent->d_inode;
144 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
145 }
146 goto Proceed;
147 }
148 else
149 error = -ENOMEM;
150 } else
151 error = -EEXIST;
152 } else
153 error = -ENOENT;
154 goto Done;
155
156 Proceed:
157 if (init)
158 error = init(inode);
159 if (!error) {
160 d_instantiate(dentry, inode);
161 if (S_ISDIR(mode))
162 dget(dentry); /* pin only directory dentry in core */
163 } else
164 iput(inode);
165 Done:
166 return error;
167}
168
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169/*
170 * Get the name for corresponding element represented by the given sysfs_dirent
171 */
172const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
173{
174 struct attribute * attr;
175 struct bin_attribute * bin_attr;
176 struct sysfs_symlink * sl;
177
Eric Sesterhenn99cee0c2006-04-01 01:18:38 +0200178 BUG_ON(!sd || !sd->s_element);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
180 switch (sd->s_type) {
181 case SYSFS_DIR:
182 /* Always have a dentry so use that */
183 return sd->s_dentry->d_name.name;
184
185 case SYSFS_KOBJ_ATTR:
186 attr = sd->s_element;
187 return attr->name;
188
189 case SYSFS_KOBJ_BIN_ATTR:
190 bin_attr = sd->s_element;
191 return bin_attr->attr.name;
192
193 case SYSFS_KOBJ_LINK:
194 sl = sd->s_element;
195 return sl->link_name;
196 }
197 return NULL;
198}
199
200
201/*
202 * Unhashes the dentry corresponding to given sysfs_dirent
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800203 * Called with parent inode's i_mutex held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 */
205void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
206{
207 struct dentry * dentry = sd->s_dentry;
208
209 if (dentry) {
210 spin_lock(&dcache_lock);
211 spin_lock(&dentry->d_lock);
212 if (!(d_unhashed(dentry) && dentry->d_inode)) {
213 dget_locked(dentry);
214 __d_drop(dentry);
215 spin_unlock(&dentry->d_lock);
216 spin_unlock(&dcache_lock);
217 simple_unlink(parent->d_inode, dentry);
218 } else {
219 spin_unlock(&dentry->d_lock);
220 spin_unlock(&dcache_lock);
221 }
222 }
223}
224
225void sysfs_hash_and_remove(struct dentry * dir, const char * name)
226{
227 struct sysfs_dirent * sd;
Greg Kroah-Hartman641e6f32006-03-16 15:44:26 -0800228 struct sysfs_dirent * parent_sd;
229
230 if (!dir)
231 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
James Bottomley36676bc2005-08-26 18:34:17 -0700233 if (dir->d_inode == NULL)
234 /* no inode means this hasn't been made visible yet */
235 return;
236
Greg Kroah-Hartman641e6f32006-03-16 15:44:26 -0800237 parent_sd = dir->d_fsdata;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800238 mutex_lock(&dir->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
240 if (!sd->s_element)
241 continue;
242 if (!strcmp(sysfs_get_name(sd), name)) {
243 list_del_init(&sd->s_sibling);
244 sysfs_drop_dentry(sd, dir);
245 sysfs_put(sd);
246 break;
247 }
248 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800249 mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250}