Merge with git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
[linux-2.6] / fs / sysfs / inode.c
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>
14 #include <linux/capability.h>
15 #include "sysfs.h"
16
17 extern struct super_block * sysfs_sb;
18
19 static struct address_space_operations sysfs_aops = {
20         .readpage       = simple_readpage,
21         .prepare_write  = simple_prepare_write,
22         .commit_write   = simple_commit_write
23 };
24
25 static 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
30 static struct inode_operations sysfs_inode_operations ={
31         .setattr        = sysfs_setattr,
32 };
33
34 int 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 */
57                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
58                 if (!sd_iattr)
59                         return -ENOMEM;
60                 /* assign default attributes */
61                 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;
88                 sd_iattr->ia_mode = sd->s_mode = mode;
89         }
90
91         return error;
92 }
93
94 static 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
102 static 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
112 struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
113 {
114         struct inode * inode = new_inode(sysfs_sb);
115         if (inode) {
116                 inode->i_blksize = PAGE_CACHE_SIZE;
117                 inode->i_blocks = 0;
118                 inode->i_mapping->a_ops = &sysfs_aops;
119                 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
120                 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);
130         }
131         return inode;
132 }
133
134 int 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) {
140                         struct sysfs_dirent * sd = dentry->d_fsdata;
141                         if ((inode = sysfs_new_inode(mode, sd))) {
142                                 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
169 /*
170  * Get the name for corresponding element represented by the given sysfs_dirent
171  */
172 const 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
178         BUG_ON(!sd || !sd->s_element);
179
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
203  * Called with parent inode's i_mutex held.
204  */
205 void 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
225 void sysfs_hash_and_remove(struct dentry * dir, const char * name)
226 {
227         struct sysfs_dirent * sd;
228         struct sysfs_dirent * parent_sd;
229
230         if (!dir)
231                 return;
232
233         if (dir->d_inode == NULL)
234                 /* no inode means this hasn't been made visible yet */
235                 return;
236
237         parent_sd = dir->d_fsdata;
238         mutex_lock(&dir->d_inode->i_mutex);
239         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         }
249         mutex_unlock(&dir->d_inode->i_mutex);
250 }