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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 */
Miklos Szeredie4ad08f2008-04-30 00:54:37 -070033 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
Linus Torvalds1da177e2005-04-16 15:20:36 -070034};
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
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -070040int __init sysfs_inode_init(void)
41{
42 return bdi_init(&sysfs_backing_dev_info);
43}
44
Maneesh Soni988d1862005-05-31 10:39:14 +053045int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
46{
47 struct inode * inode = dentry->d_inode;
48 struct sysfs_dirent * sd = dentry->d_fsdata;
49 struct iattr * sd_iattr;
50 unsigned int ia_valid = iattr->ia_valid;
51 int error;
52
53 if (!sd)
54 return -EINVAL;
55
56 sd_iattr = sd->s_iattr;
57
58 error = inode_change_ok(inode, iattr);
59 if (error)
60 return error;
61
Ben Hutchings40a21592008-04-28 15:59:58 +010062 iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
63
Maneesh Soni988d1862005-05-31 10:39:14 +053064 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 */
Eric Sesterhenn58d49282006-02-22 11:18:15 +010070 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
Maneesh Soni988d1862005-05-31 10:39:14 +053071 if (!sd_iattr)
72 return -ENOMEM;
73 /* assign default attributes */
Maneesh Soni988d1862005-05-31 10:39:14 +053074 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;
Maneesh Soni9ca1eb32005-07-29 12:14:19 -0700101 sd_iattr->ia_mode = sd->s_mode = mode;
Maneesh Soni988d1862005-05-31 10:39:14 +0530102 }
103
104 return error;
105}
106
Maneesh Soni82155342005-05-31 10:39:52 +0530107static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
108{
109 inode->i_mode = mode;
Maneesh Soni82155342005-05-31 10:39:52 +0530110 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
111}
112
113static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
114{
115 inode->i_mode = iattr->ia_mode;
116 inode->i_uid = iattr->ia_uid;
117 inode->i_gid = iattr->ia_gid;
118 inode->i_atime = iattr->ia_atime;
119 inode->i_mtime = iattr->ia_mtime;
120 inode->i_ctime = iattr->ia_ctime;
121}
122
Arjan van de Ven232ba9d2006-07-12 09:03:06 -0700123
124/*
125 * sysfs has a different i_mutex lock order behavior for i_mutex than other
126 * filesystems; sysfs i_mutex is called in many places with subsystem locks
127 * held. At the same time, many of the VFS locking rules do not apply to
128 * sysfs at all (cross directory rename for example). To untangle this mess
129 * (which gives false positives in lockdep), we're giving sysfs inodes their
130 * own class for i_mutex.
131 */
132static struct lock_class_key sysfs_inode_imutex_key;
133
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900134static int sysfs_count_nlink(struct sysfs_dirent *sd)
135{
136 struct sysfs_dirent *child;
137 int nr = 0;
138
Tejun Heobc747f32007-09-20 16:05:12 +0900139 for (child = sd->s_dir.children; child; child = child->s_sibling)
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900140 if (sysfs_type(child) == SYSFS_DIR)
141 nr++;
142
143 return nr + 2;
144}
145
Tejun Heobc37e282007-07-18 14:30:28 +0900146static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147{
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900148 struct bin_attribute *bin_attr;
149
Eric W. Biederman04256b42009-02-11 13:20:23 -0800150 inode->i_private = sysfs_get(sd);
Tejun Heofc9f54b2007-06-14 03:45:17 +0900151 inode->i_mapping->a_ops = &sysfs_aops;
152 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
153 inode->i_op = &sysfs_inode_operations;
154 inode->i_ino = sd->s_ino;
155 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
Maneesh Soni82155342005-05-31 10:39:52 +0530156
Tejun Heofc9f54b2007-06-14 03:45:17 +0900157 if (sd->s_iattr) {
158 /* sysfs_dirent has non-default attributes
159 * get them for the new inode from persistent copy
160 * in sysfs_dirent
161 */
162 set_inode_attr(inode, sd->s_iattr);
163 } else
164 set_default_inode_attr(inode, sd->s_mode);
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900165
166
167 /* initialize inode according to type */
168 switch (sysfs_type(sd)) {
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900169 case SYSFS_DIR:
170 inode->i_op = &sysfs_dir_inode_operations;
171 inode->i_fop = &sysfs_dir_operations;
172 inode->i_nlink = sysfs_count_nlink(sd);
173 break;
174 case SYSFS_KOBJ_ATTR:
175 inode->i_size = PAGE_SIZE;
176 inode->i_fop = &sysfs_file_operations;
177 break;
178 case SYSFS_KOBJ_BIN_ATTR:
Tejun Heob1fc3d62007-09-20 16:05:11 +0900179 bin_attr = sd->s_bin_attr.bin_attr;
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900180 inode->i_size = bin_attr->size;
181 inode->i_fop = &bin_fops;
182 break;
183 case SYSFS_KOBJ_LINK:
184 inode->i_op = &sysfs_symlink_inode_operations;
185 break;
186 default:
187 BUG();
188 }
189
190 unlock_new_inode(inode);
Tejun Heofc9f54b2007-06-14 03:45:17 +0900191}
192
193/**
Tejun Heo8312a8d2007-06-14 03:45:17 +0900194 * sysfs_get_inode - get inode for sysfs_dirent
Tejun Heofc9f54b2007-06-14 03:45:17 +0900195 * @sd: sysfs_dirent to allocate inode for
196 *
Tejun Heo8312a8d2007-06-14 03:45:17 +0900197 * Get inode for @sd. If such inode doesn't exist, a new inode
198 * is allocated and basics are initialized. New inode is
199 * returned locked.
Tejun Heofc9f54b2007-06-14 03:45:17 +0900200 *
201 * LOCKING:
202 * Kernel thread context (may sleep).
203 *
204 * RETURNS:
205 * Pointer to allocated inode on success, NULL on failure.
206 */
Tejun Heo8312a8d2007-06-14 03:45:17 +0900207struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
Tejun Heofc9f54b2007-06-14 03:45:17 +0900208{
209 struct inode *inode;
210
Tejun Heo8312a8d2007-06-14 03:45:17 +0900211 inode = iget_locked(sysfs_sb, sd->s_ino);
212 if (inode && (inode->i_state & I_NEW))
Tejun Heofc9f54b2007-06-14 03:45:17 +0900213 sysfs_init_inode(sd, inode);
214
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 return inode;
216}
217
Eric W. Biederman04256b42009-02-11 13:20:23 -0800218/*
219 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
220 * To prevent the sysfs inode numbers from being freed prematurely we take a
221 * reference to sysfs_dirent from the sysfs inode. A
222 * super_operations.delete_inode() implementation is needed to drop that
223 * reference upon inode destruction.
224 */
225void sysfs_delete_inode(struct inode *inode)
226{
227 struct sysfs_dirent *sd = inode->i_private;
228
229 truncate_inode_pages(&inode->i_data, 0);
230 clear_inode(inode);
231 sysfs_put(sd);
232}
233
Tejun Heo608e2662007-06-14 04:27:22 +0900234int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235{
Tejun Heofb6896d2007-06-14 04:27:24 +0900236 struct sysfs_addrm_cxt acxt;
Tejun Heo41fc1c22007-08-02 21:38:03 +0900237 struct sysfs_dirent *sd;
Greg Kroah-Hartman641e6f32006-03-16 15:44:26 -0800238
Tejun Heo608e2662007-06-14 04:27:22 +0900239 if (!dir_sd)
Randy.Dunlap995982c2006-07-10 23:05:25 -0700240 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241
Tejun Heofb6896d2007-06-14 04:27:24 +0900242 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900243
Tejun Heo41fc1c22007-08-02 21:38:03 +0900244 sd = sysfs_find_dirent(dir_sd, name);
245 if (sd)
246 sysfs_remove_one(&acxt, sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900247
Tejun Heo990e53f2007-08-02 21:38:03 +0900248 sysfs_addrm_finish(&acxt);
249
250 if (sd)
Tejun Heofb6896d2007-06-14 04:27:24 +0900251 return 0;
Tejun Heo990e53f2007-08-02 21:38:03 +0900252 else
253 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254}