Merge branch 'drm-forlinus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied...
[linux-2.6-microblaze.git] / 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 = kmalloc(sizeof(struct iattr), GFP_KERNEL);
58                 if (!sd_iattr)
59                         return -ENOMEM;
60                 /* assign default attributes */
61                 memset(sd_iattr, 0, sizeof(struct iattr));
62                 sd_iattr->ia_mode = sd->s_mode;
63                 sd_iattr->ia_uid = 0;
64                 sd_iattr->ia_gid = 0;
65                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
66                 sd->s_iattr = sd_iattr;
67         }
68
69         /* attributes were changed atleast once in past */
70
71         if (ia_valid & ATTR_UID)
72                 sd_iattr->ia_uid = iattr->ia_uid;
73         if (ia_valid & ATTR_GID)
74                 sd_iattr->ia_gid = iattr->ia_gid;
75         if (ia_valid & ATTR_ATIME)
76                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
77                                                 inode->i_sb->s_time_gran);
78         if (ia_valid & ATTR_MTIME)
79                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
80                                                 inode->i_sb->s_time_gran);
81         if (ia_valid & ATTR_CTIME)
82                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
83                                                 inode->i_sb->s_time_gran);
84         if (ia_valid & ATTR_MODE) {
85                 umode_t mode = iattr->ia_mode;
86
87                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
88                         mode &= ~S_ISGID;
89                 sd_iattr->ia_mode = sd->s_mode = mode;
90         }
91
92         return error;
93 }
94
95 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
96 {
97         inode->i_mode = mode;
98         inode->i_uid = 0;
99         inode->i_gid = 0;
100         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
101 }
102
103 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
104 {
105         inode->i_mode = iattr->ia_mode;
106         inode->i_uid = iattr->ia_uid;
107         inode->i_gid = iattr->ia_gid;
108         inode->i_atime = iattr->ia_atime;
109         inode->i_mtime = iattr->ia_mtime;
110         inode->i_ctime = iattr->ia_ctime;
111 }
112
113 struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
114 {
115         struct inode * inode = new_inode(sysfs_sb);
116         if (inode) {
117                 inode->i_blksize = PAGE_CACHE_SIZE;
118                 inode->i_blocks = 0;
119                 inode->i_mapping->a_ops = &sysfs_aops;
120                 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
121                 inode->i_op = &sysfs_inode_operations;
122
123                 if (sd->s_iattr) {
124                         /* sysfs_dirent has non-default attributes
125                          * get them for the new inode from persistent copy
126                          * in sysfs_dirent
127                          */
128                         set_inode_attr(inode, sd->s_iattr);
129                 } else
130                         set_default_inode_attr(inode, mode);
131         }
132         return inode;
133 }
134
135 int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
136 {
137         int error = 0;
138         struct inode * inode = NULL;
139         if (dentry) {
140                 if (!dentry->d_inode) {
141                         struct sysfs_dirent * sd = dentry->d_fsdata;
142                         if ((inode = sysfs_new_inode(mode, sd))) {
143                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
144                                         struct inode *p_inode = dentry->d_parent->d_inode;
145                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
146                                 }
147                                 goto Proceed;
148                         }
149                         else 
150                                 error = -ENOMEM;
151                 } else
152                         error = -EEXIST;
153         } else 
154                 error = -ENOENT;
155         goto Done;
156
157  Proceed:
158         if (init)
159                 error = init(inode);
160         if (!error) {
161                 d_instantiate(dentry, inode);
162                 if (S_ISDIR(mode))
163                         dget(dentry);  /* pin only directory dentry in core */
164         } else
165                 iput(inode);
166  Done:
167         return error;
168 }
169
170 /*
171  * Get the name for corresponding element represented by the given sysfs_dirent
172  */
173 const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
174 {
175         struct attribute * attr;
176         struct bin_attribute * bin_attr;
177         struct sysfs_symlink  * sl;
178
179         if (!sd || !sd->s_element)
180                 BUG();
181
182         switch (sd->s_type) {
183                 case SYSFS_DIR:
184                         /* Always have a dentry so use that */
185                         return sd->s_dentry->d_name.name;
186
187                 case SYSFS_KOBJ_ATTR:
188                         attr = sd->s_element;
189                         return attr->name;
190
191                 case SYSFS_KOBJ_BIN_ATTR:
192                         bin_attr = sd->s_element;
193                         return bin_attr->attr.name;
194
195                 case SYSFS_KOBJ_LINK:
196                         sl = sd->s_element;
197                         return sl->link_name;
198         }
199         return NULL;
200 }
201
202
203 /*
204  * Unhashes the dentry corresponding to given sysfs_dirent
205  * Called with parent inode's i_mutex held.
206  */
207 void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
208 {
209         struct dentry * dentry = sd->s_dentry;
210
211         if (dentry) {
212                 spin_lock(&dcache_lock);
213                 spin_lock(&dentry->d_lock);
214                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
215                         dget_locked(dentry);
216                         __d_drop(dentry);
217                         spin_unlock(&dentry->d_lock);
218                         spin_unlock(&dcache_lock);
219                         simple_unlink(parent->d_inode, dentry);
220                 } else {
221                         spin_unlock(&dentry->d_lock);
222                         spin_unlock(&dcache_lock);
223                 }
224         }
225 }
226
227 void sysfs_hash_and_remove(struct dentry * dir, const char * name)
228 {
229         struct sysfs_dirent * sd;
230         struct sysfs_dirent * parent_sd = dir->d_fsdata;
231
232         if (dir->d_inode == NULL)
233                 /* no inode means this hasn't been made visible yet */
234                 return;
235
236         mutex_lock(&dir->d_inode->i_mutex);
237         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
238                 if (!sd->s_element)
239                         continue;
240                 if (!strcmp(sysfs_get_name(sd), name)) {
241                         list_del_init(&sd->s_sibling);
242                         sysfs_drop_dentry(sd, dir);
243                         sysfs_put(sd);
244                         break;
245                 }
246         }
247         mutex_unlock(&dir->d_inode->i_mutex);
248 }