File: /usr/src/linux/fs/minix/namei.c
1 /*
2 * linux/fs/minix/namei.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 #include <linux/fs.h>
8 #include <linux/minix_fs.h>
9 #include <linux/pagemap.h>
10
11 static inline void inc_count(struct inode *inode)
12 {
13 inode->i_nlink++;
14 mark_inode_dirty(inode);
15 }
16
17 static inline void dec_count(struct inode *inode)
18 {
19 inode->i_nlink--;
20 mark_inode_dirty(inode);
21 }
22
23 static int add_nondir(struct dentry *dentry, struct inode *inode)
24 {
25 int err = minix_add_link(dentry, inode);
26 if (!err) {
27 d_instantiate(dentry, inode);
28 return 0;
29 }
30 dec_count(inode);
31 iput(inode);
32 return err;
33 }
34
35 static int minix_hash(struct dentry *dentry, struct qstr *qstr)
36 {
37 unsigned long hash;
38 int i;
39 const unsigned char *name;
40
41 i = dentry->d_inode->i_sb->u.minix_sb.s_namelen;
42 if (i >= qstr->len)
43 return 0;
44 /* Truncate the name in place, avoids having to define a compare
45 function. */
46 qstr->len = i;
47 name = qstr->name;
48 hash = init_name_hash();
49 while (i--)
50 hash = partial_name_hash(*name++, hash);
51 qstr->hash = end_name_hash(hash);
52 return 0;
53 }
54
55 struct dentry_operations minix_dentry_operations = {
56 d_hash: minix_hash,
57 };
58
59 static struct dentry *minix_lookup(struct inode * dir, struct dentry *dentry)
60 {
61 struct inode * inode = NULL;
62 ino_t ino;
63
64 dentry->d_op = dir->i_sb->s_root->d_op;
65
66 if (dentry->d_name.len > dir->i_sb->u.minix_sb.s_namelen)
67 return ERR_PTR(-ENAMETOOLONG);
68
69 ino = minix_inode_by_name(dentry);
70 if (ino) {
71 inode = iget(dir->i_sb, ino);
72
73 if (!inode)
74 return ERR_PTR(-EACCES);
75 }
76 d_add(dentry, inode);
77 return NULL;
78 }
79
80 static int minix_mknod(struct inode * dir, struct dentry *dentry, int mode, int rdev)
81 {
82 int error;
83 struct inode * inode = minix_new_inode(dir, &error);
84
85 if (inode) {
86 inode->i_mode = mode;
87 minix_set_inode(inode, rdev);
88 mark_inode_dirty(inode);
89 error = add_nondir(dentry, inode);
90 }
91 return error;
92 }
93
94 static int minix_create(struct inode * dir, struct dentry *dentry, int mode)
95 {
96 return minix_mknod(dir, dentry, mode, 0);
97 }
98
99 static int minix_symlink(struct inode * dir, struct dentry *dentry,
100 const char * symname)
101 {
102 int err = -ENAMETOOLONG;
103 int i = strlen(symname)+1;
104 struct inode * inode;
105
106 if (i > dir->i_sb->s_blocksize)
107 goto out;
108
109 inode = minix_new_inode(dir, &err);
110 if (!inode)
111 goto out;
112
113 inode->i_mode = S_IFLNK | 0777;
114 minix_set_inode(inode, 0);
115 err = block_symlink(inode, symname, i);
116 if (err)
117 goto out_fail;
118
119 err = add_nondir(dentry, inode);
120 out:
121 return err;
122
123 out_fail:
124 dec_count(inode);
125 iput(inode);
126 goto out;
127 }
128
129 static int minix_link(struct dentry * old_dentry, struct inode * dir,
130 struct dentry *dentry)
131 {
132 struct inode *inode = old_dentry->d_inode;
133
134 if (S_ISDIR(inode->i_mode))
135 return -EPERM;
136
137 if (inode->i_nlink >= inode->i_sb->u.minix_sb.s_link_max)
138 return -EMLINK;
139
140 inode->i_ctime = CURRENT_TIME;
141 inc_count(inode);
142 atomic_inc(&inode->i_count);
143 return add_nondir(dentry, inode);
144 }
145
146 static int minix_mkdir(struct inode * dir, struct dentry *dentry, int mode)
147 {
148 struct inode * inode;
149 int err = -EMLINK;
150
151 if (dir->i_nlink >= dir->i_sb->u.minix_sb.s_link_max)
152 goto out;
153
154 inc_count(dir);
155
156 inode = minix_new_inode(dir, &err);
157 if (!inode)
158 goto out_dir;
159
160 inode->i_mode = S_IFDIR | mode;
161 if (dir->i_mode & S_ISGID)
162 inode->i_mode |= S_ISGID;
163 minix_set_inode(inode, 0);
164
165 inc_count(inode);
166
167 err = minix_make_empty(inode, dir);
168 if (err)
169 goto out_fail;
170
171 err = minix_add_link(dentry, inode);
172 if (err)
173 goto out_fail;
174
175 d_instantiate(dentry, inode);
176 out:
177 return err;
178
179 out_fail:
180 dec_count(inode);
181 dec_count(inode);
182 iput(inode);
183 out_dir:
184 dec_count(dir);
185 goto out;
186 }
187
188 static int minix_unlink(struct inode * dir, struct dentry *dentry)
189 {
190 int err = -ENOENT;
191 struct inode * inode = dentry->d_inode;
192 struct page * page;
193 struct minix_dir_entry * de;
194
195 de = minix_find_entry(dentry, &page);
196 if (!de)
197 goto end_unlink;
198
199 err = minix_delete_entry(de, page);
200 if (err)
201 goto end_unlink;
202
203 inode->i_ctime = dir->i_ctime;
204 dec_count(inode);
205 end_unlink:
206 return err;
207 }
208
209 static int minix_rmdir(struct inode * dir, struct dentry *dentry)
210 {
211 struct inode * inode = dentry->d_inode;
212 int err = -ENOTEMPTY;
213
214 if (minix_empty_dir(inode)) {
215 err = minix_unlink(dir, dentry);
216 if (!err) {
217 dec_count(dir);
218 dec_count(inode);
219 }
220 }
221 return err;
222 }
223
224 static int minix_rename(struct inode * old_dir, struct dentry *old_dentry,
225 struct inode * new_dir, struct dentry *new_dentry)
226 {
227 struct minix_sb_info * info = &old_dir->i_sb->u.minix_sb;
228 struct inode * old_inode = old_dentry->d_inode;
229 struct inode * new_inode = new_dentry->d_inode;
230 struct page * dir_page = NULL;
231 struct minix_dir_entry * dir_de = NULL;
232 struct page * old_page;
233 struct minix_dir_entry * old_de;
234 int err = -ENOENT;
235
236 old_de = minix_find_entry(old_dentry, &old_page);
237 if (!old_de)
238 goto out;
239
240 if (S_ISDIR(old_inode->i_mode)) {
241 err = -EIO;
242 dir_de = minix_dotdot(old_inode, &dir_page);
243 if (!dir_de)
244 goto out_old;
245 }
246
247 if (new_inode) {
248 struct page * new_page;
249 struct minix_dir_entry * new_de;
250
251 err = -ENOTEMPTY;
252 if (dir_de && !minix_empty_dir(new_inode))
253 goto out_dir;
254
255 err = -ENOENT;
256 new_de = minix_find_entry(new_dentry, &new_page);
257 if (!new_de)
258 goto out_dir;
259 inc_count(old_inode);
260 minix_set_link(new_de, new_page, old_inode);
261 new_inode->i_ctime = CURRENT_TIME;
262 if (dir_de)
263 new_inode->i_nlink--;
264 dec_count(new_inode);
265 } else {
266 if (dir_de) {
267 err = -EMLINK;
268 if (new_dir->i_nlink >= info->s_link_max)
269 goto out_dir;
270 }
271 inc_count(old_inode);
272 err = minix_add_link(new_dentry, old_inode);
273 if (err) {
274 dec_count(old_inode);
275 goto out_dir;
276 }
277 if (dir_de)
278 inc_count(new_dir);
279 }
280
281 minix_delete_entry(old_de, old_page);
282 dec_count(old_inode);
283
284 if (dir_de) {
285 minix_set_link(dir_de, dir_page, new_dir);
286 dec_count(old_dir);
287 }
288 return 0;
289
290 out_dir:
291 if (dir_de) {
292 kunmap(dir_page);
293 page_cache_release(dir_page);
294 }
295 out_old:
296 kunmap(old_page);
297 page_cache_release(old_page);
298 out:
299 return err;
300 }
301
302 /*
303 * directories can handle most operations...
304 */
305 struct inode_operations minix_dir_inode_operations = {
306 create: minix_create,
307 lookup: minix_lookup,
308 link: minix_link,
309 unlink: minix_unlink,
310 symlink: minix_symlink,
311 mkdir: minix_mkdir,
312 rmdir: minix_rmdir,
313 mknod: minix_mknod,
314 rename: minix_rename,
315 };
316