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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>
Randy.Dunlap995982c2006-07-10 23:05:25 -070015#include <linux/errno.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040016#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include "sysfs.h"
18
19extern struct super_block * sysfs_sb;
20
Christoph Hellwigf5e54d62006-06-28 04:26:44 -070021static const struct address_space_operations sysfs_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070022 .readpage = simple_readpage,
23 .prepare_write = simple_prepare_write,
24 .commit_write = simple_commit_write
25};
26
27static struct backing_dev_info sysfs_backing_dev_info = {
28 .ra_pages = 0, /* No readahead */
29 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
30};
31
Arjan van de Venc5ef1c42007-02-12 00:55:40 -080032static const struct inode_operations sysfs_inode_operations ={
Maneesh Soni988d1862005-05-31 10:39:14 +053033 .setattr = sysfs_setattr,
34};
35
36int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
37{
38 struct inode * inode = dentry->d_inode;
39 struct sysfs_dirent * sd = dentry->d_fsdata;
40 struct iattr * sd_iattr;
41 unsigned int ia_valid = iattr->ia_valid;
42 int error;
43
44 if (!sd)
45 return -EINVAL;
46
47 sd_iattr = sd->s_iattr;
48
49 error = inode_change_ok(inode, iattr);
50 if (error)
51 return error;
52
53 error = inode_setattr(inode, iattr);
54 if (error)
55 return error;
56
57 if (!sd_iattr) {
58 /* setting attributes for the first time, allocate now */
Eric Sesterhenn58d49282006-02-22 11:18:15 +010059 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
Maneesh Soni988d1862005-05-31 10:39:14 +053060 if (!sd_iattr)
61 return -ENOMEM;
62 /* assign default attributes */
Maneesh Soni988d1862005-05-31 10:39:14 +053063 sd_iattr->ia_mode = sd->s_mode;
64 sd_iattr->ia_uid = 0;
65 sd_iattr->ia_gid = 0;
66 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
67 sd->s_iattr = sd_iattr;
68 }
69
70 /* attributes were changed atleast once in past */
71
72 if (ia_valid & ATTR_UID)
73 sd_iattr->ia_uid = iattr->ia_uid;
74 if (ia_valid & ATTR_GID)
75 sd_iattr->ia_gid = iattr->ia_gid;
76 if (ia_valid & ATTR_ATIME)
77 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
78 inode->i_sb->s_time_gran);
79 if (ia_valid & ATTR_MTIME)
80 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
81 inode->i_sb->s_time_gran);
82 if (ia_valid & ATTR_CTIME)
83 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
84 inode->i_sb->s_time_gran);
85 if (ia_valid & ATTR_MODE) {
86 umode_t mode = iattr->ia_mode;
87
88 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
89 mode &= ~S_ISGID;
Maneesh Soni9ca1eb32005-07-29 12:14:19 -070090 sd_iattr->ia_mode = sd->s_mode = mode;
Maneesh Soni988d1862005-05-31 10:39:14 +053091 }
92
93 return error;
94}
95
Maneesh Soni82155342005-05-31 10:39:52 +053096static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
97{
98 inode->i_mode = mode;
99 inode->i_uid = 0;
100 inode->i_gid = 0;
101 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
102}
103
104static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
105{
106 inode->i_mode = iattr->ia_mode;
107 inode->i_uid = iattr->ia_uid;
108 inode->i_gid = iattr->ia_gid;
109 inode->i_atime = iattr->ia_atime;
110 inode->i_mtime = iattr->ia_mtime;
111 inode->i_ctime = iattr->ia_ctime;
112}
113
Arjan van de Ven232ba9d2006-07-12 09:03:06 -0700114
115/*
116 * sysfs has a different i_mutex lock order behavior for i_mutex than other
117 * filesystems; sysfs i_mutex is called in many places with subsystem locks
118 * held. At the same time, many of the VFS locking rules do not apply to
119 * sysfs at all (cross directory rename for example). To untangle this mess
120 * (which gives false positives in lockdep), we're giving sysfs inodes their
121 * own class for i_mutex.
122 */
123static struct lock_class_key sysfs_inode_imutex_key;
124
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900125static int sysfs_count_nlink(struct sysfs_dirent *sd)
126{
127 struct sysfs_dirent *child;
128 int nr = 0;
129
130 for (child = sd->s_children; child; child = child->s_sibling)
131 if (sysfs_type(child) == SYSFS_DIR)
132 nr++;
133
134 return nr + 2;
135}
136
Tejun Heobc37e282007-07-18 14:30:28 +0900137static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138{
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900139 struct bin_attribute *bin_attr;
140
Tejun Heofc9f54b2007-06-14 03:45:17 +0900141 inode->i_blocks = 0;
142 inode->i_mapping->a_ops = &sysfs_aops;
143 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
144 inode->i_op = &sysfs_inode_operations;
145 inode->i_ino = sd->s_ino;
146 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
Maneesh Soni82155342005-05-31 10:39:52 +0530147
Tejun Heofc9f54b2007-06-14 03:45:17 +0900148 if (sd->s_iattr) {
149 /* sysfs_dirent has non-default attributes
150 * get them for the new inode from persistent copy
151 * in sysfs_dirent
152 */
153 set_inode_attr(inode, sd->s_iattr);
154 } else
155 set_default_inode_attr(inode, sd->s_mode);
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900156
157
158 /* initialize inode according to type */
159 switch (sysfs_type(sd)) {
160 case SYSFS_ROOT:
161 inode->i_op = &sysfs_dir_inode_operations;
162 inode->i_fop = &sysfs_dir_operations;
163 inc_nlink(inode); /* directory, account for "." */
164 break;
165 case SYSFS_DIR:
166 inode->i_op = &sysfs_dir_inode_operations;
167 inode->i_fop = &sysfs_dir_operations;
168 inode->i_nlink = sysfs_count_nlink(sd);
169 break;
170 case SYSFS_KOBJ_ATTR:
171 inode->i_size = PAGE_SIZE;
172 inode->i_fop = &sysfs_file_operations;
173 break;
174 case SYSFS_KOBJ_BIN_ATTR:
175 bin_attr = sd->s_elem.bin_attr.bin_attr;
176 inode->i_size = bin_attr->size;
177 inode->i_fop = &bin_fops;
178 break;
179 case SYSFS_KOBJ_LINK:
180 inode->i_op = &sysfs_symlink_inode_operations;
181 break;
182 default:
183 BUG();
184 }
185
186 unlock_new_inode(inode);
Tejun Heofc9f54b2007-06-14 03:45:17 +0900187}
188
189/**
Tejun Heo8312a8d2007-06-14 03:45:17 +0900190 * sysfs_get_inode - get inode for sysfs_dirent
Tejun Heofc9f54b2007-06-14 03:45:17 +0900191 * @sd: sysfs_dirent to allocate inode for
192 *
Tejun Heo8312a8d2007-06-14 03:45:17 +0900193 * Get inode for @sd. If such inode doesn't exist, a new inode
194 * is allocated and basics are initialized. New inode is
195 * returned locked.
Tejun Heofc9f54b2007-06-14 03:45:17 +0900196 *
197 * LOCKING:
198 * Kernel thread context (may sleep).
199 *
200 * RETURNS:
201 * Pointer to allocated inode on success, NULL on failure.
202 */
Tejun Heo8312a8d2007-06-14 03:45:17 +0900203struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
Tejun Heofc9f54b2007-06-14 03:45:17 +0900204{
205 struct inode *inode;
206
Tejun Heo8312a8d2007-06-14 03:45:17 +0900207 inode = iget_locked(sysfs_sb, sd->s_ino);
208 if (inode && (inode->i_state & I_NEW))
Tejun Heofc9f54b2007-06-14 03:45:17 +0900209 sysfs_init_inode(sd, inode);
210
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 return inode;
212}
213
Tejun Heofc9f54b2007-06-14 03:45:17 +0900214/**
215 * sysfs_instantiate - instantiate dentry
216 * @dentry: dentry to be instantiated
217 * @inode: inode associated with @sd
218 *
Tejun Heo8312a8d2007-06-14 03:45:17 +0900219 * Unlock @inode if locked and instantiate @dentry with @inode.
Tejun Heofc9f54b2007-06-14 03:45:17 +0900220 *
221 * LOCKING:
222 * None.
223 */
224void sysfs_instantiate(struct dentry *dentry, struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225{
Tejun Heofc9f54b2007-06-14 03:45:17 +0900226 BUG_ON(!dentry || dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
Tejun Heofc9f54b2007-06-14 03:45:17 +0900228 d_instantiate(dentry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229}
230
Tejun Heo608e2662007-06-14 04:27:22 +0900231int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232{
Tejun Heofb6896d2007-06-14 04:27:24 +0900233 struct sysfs_addrm_cxt acxt;
Tejun Heo41fc1c22007-08-02 21:38:03 +0900234 struct sysfs_dirent *sd;
Greg Kroah-Hartman641e6f32006-03-16 15:44:26 -0800235
Tejun Heo608e2662007-06-14 04:27:22 +0900236 if (!dir_sd)
Randy.Dunlap995982c2006-07-10 23:05:25 -0700237 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238
Tejun Heofb6896d2007-06-14 04:27:24 +0900239 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900240
Tejun Heo41fc1c22007-08-02 21:38:03 +0900241 sd = sysfs_find_dirent(dir_sd, name);
242 if (sd)
243 sysfs_remove_one(&acxt, sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900244
Tejun Heo990e53f2007-08-02 21:38:03 +0900245 sysfs_addrm_finish(&acxt);
246
247 if (sd)
Tejun Heofb6896d2007-06-14 04:27:24 +0900248 return 0;
Tejun Heo990e53f2007-08-02 21:38:03 +0900249 else
250 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251}