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Commit | Line | Data |
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1da177e4 LT |
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> | |
16f7e0fe | 14 | #include <linux/capability.h> |
995982ca | 15 | #include <linux/errno.h> |
e8edc6e0 | 16 | #include <linux/sched.h> |
1da177e4 LT |
17 | #include "sysfs.h" |
18 | ||
19 | extern struct super_block * sysfs_sb; | |
20 | ||
f5e54d6e | 21 | static const struct address_space_operations sysfs_aops = { |
1da177e4 LT |
22 | .readpage = simple_readpage, |
23 | .prepare_write = simple_prepare_write, | |
24 | .commit_write = simple_commit_write | |
25 | }; | |
26 | ||
27 | static 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 | ||
c5ef1c42 | 32 | static const struct inode_operations sysfs_inode_operations ={ |
988d186d MS |
33 | .setattr = sysfs_setattr, |
34 | }; | |
35 | ||
36 | int 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 */ | |
58d49283 | 59 | sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); |
988d186d MS |
60 | if (!sd_iattr) |
61 | return -ENOMEM; | |
62 | /* assign default attributes */ | |
988d186d MS |
63 | 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; | |
9ca1eb32 | 90 | sd_iattr->ia_mode = sd->s_mode = mode; |
988d186d MS |
91 | } |
92 | ||
93 | return error; | |
94 | } | |
95 | ||
8215534c MS |
96 | static 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 | ||
104 | static 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 | ||
232ba9db AV |
114 | |
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 | */ | |
123 | static struct lock_class_key sysfs_inode_imutex_key; | |
124 | ||
bc37e283 | 125 | static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode) |
1da177e4 | 126 | { |
fc9f54b9 TH |
127 | inode->i_blocks = 0; |
128 | inode->i_mapping->a_ops = &sysfs_aops; | |
129 | inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info; | |
130 | inode->i_op = &sysfs_inode_operations; | |
131 | inode->i_ino = sd->s_ino; | |
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, sd->s_mode); | |
142 | } | |
143 | ||
144 | /** | |
8312a8d7 | 145 | * sysfs_get_inode - get inode for sysfs_dirent |
fc9f54b9 TH |
146 | * @sd: sysfs_dirent to allocate inode for |
147 | * | |
8312a8d7 TH |
148 | * Get inode for @sd. If such inode doesn't exist, a new inode |
149 | * is allocated and basics are initialized. New inode is | |
150 | * returned locked. | |
fc9f54b9 TH |
151 | * |
152 | * LOCKING: | |
153 | * Kernel thread context (may sleep). | |
154 | * | |
155 | * RETURNS: | |
156 | * Pointer to allocated inode on success, NULL on failure. | |
157 | */ | |
8312a8d7 | 158 | struct inode * sysfs_get_inode(struct sysfs_dirent *sd) |
fc9f54b9 TH |
159 | { |
160 | struct inode *inode; | |
161 | ||
8312a8d7 TH |
162 | inode = iget_locked(sysfs_sb, sd->s_ino); |
163 | if (inode && (inode->i_state & I_NEW)) | |
fc9f54b9 TH |
164 | sysfs_init_inode(sd, inode); |
165 | ||
1da177e4 LT |
166 | return inode; |
167 | } | |
168 | ||
fc9f54b9 TH |
169 | /** |
170 | * sysfs_instantiate - instantiate dentry | |
171 | * @dentry: dentry to be instantiated | |
172 | * @inode: inode associated with @sd | |
173 | * | |
8312a8d7 | 174 | * Unlock @inode if locked and instantiate @dentry with @inode. |
fc9f54b9 TH |
175 | * |
176 | * LOCKING: | |
177 | * None. | |
178 | */ | |
179 | void sysfs_instantiate(struct dentry *dentry, struct inode *inode) | |
1da177e4 | 180 | { |
fc9f54b9 TH |
181 | BUG_ON(!dentry || dentry->d_inode); |
182 | ||
fb6896da | 183 | if (inode->i_state & I_NEW) |
8312a8d7 TH |
184 | unlock_new_inode(inode); |
185 | ||
fc9f54b9 | 186 | d_instantiate(dentry, inode); |
1da177e4 LT |
187 | } |
188 | ||
608e266a | 189 | int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name) |
1da177e4 | 190 | { |
fb6896da | 191 | struct sysfs_addrm_cxt acxt; |
0c73f18b | 192 | struct sysfs_dirent **pos, *sd; |
641e6f30 | 193 | |
608e266a | 194 | if (!dir_sd) |
995982ca | 195 | return -ENOENT; |
1da177e4 | 196 | |
fb6896da | 197 | sysfs_addrm_start(&acxt, dir_sd); |
608e266a | 198 | |
608e266a | 199 | for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) { |
0c73f18b TH |
200 | sd = *pos; |
201 | ||
b402d72c | 202 | if (!sysfs_type(sd)) |
1da177e4 | 203 | continue; |
0c096b50 | 204 | if (!strcmp(sd->s_name, name)) { |
0c73f18b TH |
205 | *pos = sd->s_sibling; |
206 | sd->s_sibling = NULL; | |
fb6896da | 207 | sysfs_remove_one(&acxt, sd); |
1da177e4 LT |
208 | break; |
209 | } | |
210 | } | |
3007e997 | 211 | |
fb6896da TH |
212 | if (sysfs_addrm_finish(&acxt)) |
213 | return 0; | |
214 | return -ENOENT; | |
1da177e4 | 215 | } |