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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Tejun Heo6d66f5c2007-09-20 17:31:38 +09002 * fs/sysfs/inode.c - basic sysfs inode and dentry operations
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
Tejun Heo6d66f5c2007-09-20 17:31:38 +09004 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#undef DEBUG
14
15#include <linux/pagemap.h>
16#include <linux/namei.h>
17#include <linux/backing-dev.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080018#include <linux/capability.h>
Randy.Dunlap995982c2006-07-10 23:05:25 -070019#include <linux/errno.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040020#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include "sysfs.h"
22
23extern struct super_block * sysfs_sb;
24
Christoph Hellwigf5e54d62006-06-28 04:26:44 -070025static const struct address_space_operations sysfs_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070026 .readpage = simple_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -070027 .write_begin = simple_write_begin,
28 .write_end = simple_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -070029};
30
31static struct backing_dev_info sysfs_backing_dev_info = {
32 .ra_pages = 0, /* No readahead */
33 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
34};
35
Arjan van de Venc5ef1c42007-02-12 00:55:40 -080036static const struct inode_operations sysfs_inode_operations ={
Maneesh Soni988d1862005-05-31 10:39:14 +053037 .setattr = sysfs_setattr,
38};
39
40int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
41{
42 struct inode * inode = dentry->d_inode;
43 struct sysfs_dirent * sd = dentry->d_fsdata;
44 struct iattr * sd_iattr;
45 unsigned int ia_valid = iattr->ia_valid;
46 int error;
47
48 if (!sd)
49 return -EINVAL;
50
51 sd_iattr = sd->s_iattr;
52
53 error = inode_change_ok(inode, iattr);
54 if (error)
55 return error;
56
57 error = inode_setattr(inode, iattr);
58 if (error)
59 return error;
60
61 if (!sd_iattr) {
62 /* setting attributes for the first time, allocate now */
Eric Sesterhenn58d49282006-02-22 11:18:15 +010063 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
Maneesh Soni988d1862005-05-31 10:39:14 +053064 if (!sd_iattr)
65 return -ENOMEM;
66 /* assign default attributes */
Maneesh Soni988d1862005-05-31 10:39:14 +053067 sd_iattr->ia_mode = sd->s_mode;
68 sd_iattr->ia_uid = 0;
69 sd_iattr->ia_gid = 0;
70 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
71 sd->s_iattr = sd_iattr;
72 }
73
74 /* attributes were changed atleast once in past */
75
76 if (ia_valid & ATTR_UID)
77 sd_iattr->ia_uid = iattr->ia_uid;
78 if (ia_valid & ATTR_GID)
79 sd_iattr->ia_gid = iattr->ia_gid;
80 if (ia_valid & ATTR_ATIME)
81 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
82 inode->i_sb->s_time_gran);
83 if (ia_valid & ATTR_MTIME)
84 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
85 inode->i_sb->s_time_gran);
86 if (ia_valid & ATTR_CTIME)
87 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
88 inode->i_sb->s_time_gran);
89 if (ia_valid & ATTR_MODE) {
90 umode_t mode = iattr->ia_mode;
91
92 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
93 mode &= ~S_ISGID;
Maneesh Soni9ca1eb32005-07-29 12:14:19 -070094 sd_iattr->ia_mode = sd->s_mode = mode;
Maneesh Soni988d1862005-05-31 10:39:14 +053095 }
96
97 return error;
98}
99
Maneesh Soni82155342005-05-31 10:39:52 +0530100static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
101{
102 inode->i_mode = mode;
103 inode->i_uid = 0;
104 inode->i_gid = 0;
105 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
106}
107
108static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
109{
110 inode->i_mode = iattr->ia_mode;
111 inode->i_uid = iattr->ia_uid;
112 inode->i_gid = iattr->ia_gid;
113 inode->i_atime = iattr->ia_atime;
114 inode->i_mtime = iattr->ia_mtime;
115 inode->i_ctime = iattr->ia_ctime;
116}
117
Arjan van de Ven232ba9d2006-07-12 09:03:06 -0700118
119/*
120 * sysfs has a different i_mutex lock order behavior for i_mutex than other
121 * filesystems; sysfs i_mutex is called in many places with subsystem locks
122 * held. At the same time, many of the VFS locking rules do not apply to
123 * sysfs at all (cross directory rename for example). To untangle this mess
124 * (which gives false positives in lockdep), we're giving sysfs inodes their
125 * own class for i_mutex.
126 */
127static struct lock_class_key sysfs_inode_imutex_key;
128
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900129static int sysfs_count_nlink(struct sysfs_dirent *sd)
130{
131 struct sysfs_dirent *child;
132 int nr = 0;
133
Tejun Heobc747f32007-09-20 16:05:12 +0900134 for (child = sd->s_dir.children; child; child = child->s_sibling)
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900135 if (sysfs_type(child) == SYSFS_DIR)
136 nr++;
137
138 return nr + 2;
139}
140
Tejun Heobc37e282007-07-18 14:30:28 +0900141static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142{
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900143 struct bin_attribute *bin_attr;
144
Tejun Heofc9f54b2007-06-14 03:45:17 +0900145 inode->i_blocks = 0;
146 inode->i_mapping->a_ops = &sysfs_aops;
147 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
148 inode->i_op = &sysfs_inode_operations;
149 inode->i_ino = sd->s_ino;
150 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
Maneesh Soni82155342005-05-31 10:39:52 +0530151
Tejun Heofc9f54b2007-06-14 03:45:17 +0900152 if (sd->s_iattr) {
153 /* sysfs_dirent has non-default attributes
154 * get them for the new inode from persistent copy
155 * in sysfs_dirent
156 */
157 set_inode_attr(inode, sd->s_iattr);
158 } else
159 set_default_inode_attr(inode, sd->s_mode);
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900160
161
162 /* initialize inode according to type */
163 switch (sysfs_type(sd)) {
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900164 case SYSFS_DIR:
165 inode->i_op = &sysfs_dir_inode_operations;
166 inode->i_fop = &sysfs_dir_operations;
167 inode->i_nlink = sysfs_count_nlink(sd);
168 break;
169 case SYSFS_KOBJ_ATTR:
170 inode->i_size = PAGE_SIZE;
171 inode->i_fop = &sysfs_file_operations;
172 break;
173 case SYSFS_KOBJ_BIN_ATTR:
Tejun Heob1fc3d62007-09-20 16:05:11 +0900174 bin_attr = sd->s_bin_attr.bin_attr;
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900175 inode->i_size = bin_attr->size;
176 inode->i_fop = &bin_fops;
177 break;
178 case SYSFS_KOBJ_LINK:
179 inode->i_op = &sysfs_symlink_inode_operations;
180 break;
181 default:
182 BUG();
183 }
184
185 unlock_new_inode(inode);
Tejun Heofc9f54b2007-06-14 03:45:17 +0900186}
187
188/**
Tejun Heo8312a8d2007-06-14 03:45:17 +0900189 * sysfs_get_inode - get inode for sysfs_dirent
Tejun Heofc9f54b2007-06-14 03:45:17 +0900190 * @sd: sysfs_dirent to allocate inode for
191 *
Tejun Heo8312a8d2007-06-14 03:45:17 +0900192 * Get inode for @sd. If such inode doesn't exist, a new inode
193 * is allocated and basics are initialized. New inode is
194 * returned locked.
Tejun Heofc9f54b2007-06-14 03:45:17 +0900195 *
196 * LOCKING:
197 * Kernel thread context (may sleep).
198 *
199 * RETURNS:
200 * Pointer to allocated inode on success, NULL on failure.
201 */
Tejun Heo8312a8d2007-06-14 03:45:17 +0900202struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
Tejun Heofc9f54b2007-06-14 03:45:17 +0900203{
204 struct inode *inode;
205
Tejun Heo8312a8d2007-06-14 03:45:17 +0900206 inode = iget_locked(sysfs_sb, sd->s_ino);
207 if (inode && (inode->i_state & I_NEW))
Tejun Heofc9f54b2007-06-14 03:45:17 +0900208 sysfs_init_inode(sd, inode);
209
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 return inode;
211}
212
Tejun Heo608e2662007-06-14 04:27:22 +0900213int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214{
Tejun Heofb6896d2007-06-14 04:27:24 +0900215 struct sysfs_addrm_cxt acxt;
Tejun Heo41fc1c22007-08-02 21:38:03 +0900216 struct sysfs_dirent *sd;
Greg Kroah-Hartman641e6f32006-03-16 15:44:26 -0800217
Tejun Heo608e2662007-06-14 04:27:22 +0900218 if (!dir_sd)
Randy.Dunlap995982c2006-07-10 23:05:25 -0700219 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
Tejun Heofb6896d2007-06-14 04:27:24 +0900221 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900222
Tejun Heo41fc1c22007-08-02 21:38:03 +0900223 sd = sysfs_find_dirent(dir_sd, name);
224 if (sd)
225 sysfs_remove_one(&acxt, sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900226
Tejun Heo990e53f2007-08-02 21:38:03 +0900227 sysfs_addrm_finish(&acxt);
228
229 if (sd)
Tejun Heofb6896d2007-06-14 04:27:24 +0900230 return 0;
Tejun Heo990e53f2007-08-02 21:38:03 +0900231 else
232 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233}