File: /usr/src/linux/fs/sysv/namei.c
1 /*
2 * linux/fs/sysv/namei.c
3 *
4 * minix/namei.c
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * coh/namei.c
8 * Copyright (C) 1993 Pascal Haible, Bruno Haible
9 *
10 * sysv/namei.c
11 * Copyright (C) 1993 Bruno Haible
12 * Copyright (C) 1997, 1998 Krzysztof G. Baranowski
13 */
14
15 #include <linux/fs.h>
16 #include <linux/sysv_fs.h>
17 #include <linux/pagemap.h>
18
19 static inline void inc_count(struct inode *inode)
20 {
21 inode->i_nlink++;
22 mark_inode_dirty(inode);
23 }
24
25 static inline void dec_count(struct inode *inode)
26 {
27 inode->i_nlink--;
28 mark_inode_dirty(inode);
29 }
30
31 static int add_nondir(struct dentry *dentry, struct inode *inode)
32 {
33 int err = sysv_add_link(dentry, inode);
34 if (!err) {
35 d_instantiate(dentry, inode);
36 return 0;
37 }
38 dec_count(inode);
39 iput(inode);
40 return err;
41 }
42
43 static int sysv_hash(struct dentry *dentry, struct qstr *qstr)
44 {
45 unsigned long hash;
46 int i;
47 const unsigned char *name;
48
49 i = SYSV_NAMELEN;
50 if (i >= qstr->len)
51 return 0;
52 /* Truncate the name in place, avoids having to define a compare
53 function. */
54 qstr->len = i;
55 name = qstr->name;
56 hash = init_name_hash();
57 while (i--)
58 hash = partial_name_hash(*name++, hash);
59 qstr->hash = end_name_hash(hash);
60 return 0;
61 }
62
63 struct dentry_operations sysv_dentry_operations = {
64 d_hash: sysv_hash,
65 };
66
67 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry)
68 {
69 struct inode * inode = NULL;
70 ino_t ino;
71
72 dentry->d_op = dir->i_sb->s_root->d_op;
73 if (dentry->d_name.len > SYSV_NAMELEN)
74 return ERR_PTR(-ENAMETOOLONG);
75 ino = sysv_inode_by_name(dentry);
76
77 if (ino) {
78 inode = iget(dir->i_sb, ino);
79 if (!inode)
80 return ERR_PTR(-EACCES);
81 }
82 d_add(dentry, inode);
83 return NULL;
84 }
85
86 static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, int rdev)
87 {
88 struct inode * inode = sysv_new_inode(dir, mode);
89 int err = PTR_ERR(inode);
90
91 if (!IS_ERR(inode)) {
92 sysv_set_inode(inode, rdev);
93 mark_inode_dirty(inode);
94 err = add_nondir(dentry, inode);
95 }
96 return err;
97 }
98
99 static int sysv_create(struct inode * dir, struct dentry * dentry, int mode)
100 {
101 return sysv_mknod(dir, dentry, mode, 0);
102 }
103
104 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
105 const char * symname)
106 {
107 int err = -ENAMETOOLONG;
108 int l = strlen(symname)+1;
109 struct inode * inode;
110
111 if (l > dir->i_sb->s_blocksize)
112 goto out;
113
114 inode = sysv_new_inode(dir, S_IFLNK|0777);
115 err = PTR_ERR(inode);
116 if (IS_ERR(inode))
117 goto out;
118
119 sysv_set_inode(inode, 0);
120 err = block_symlink(inode, symname, l);
121 if (err)
122 goto out_fail;
123
124 mark_inode_dirty(inode);
125 err = add_nondir(dentry, inode);
126 out:
127 return err;
128
129 out_fail:
130 dec_count(inode);
131 iput(inode);
132 goto out;
133 }
134
135 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
136 struct dentry * dentry)
137 {
138 struct inode *inode = old_dentry->d_inode;
139
140 if (S_ISDIR(inode->i_mode))
141 return -EPERM;
142
143 if (inode->i_nlink >= inode->i_sb->sv_link_max)
144 return -EMLINK;
145
146 inode->i_ctime = CURRENT_TIME;
147 inc_count(inode);
148 atomic_inc(&inode->i_count);
149
150 return add_nondir(dentry, inode);
151 }
152
153 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
154 {
155 struct inode * inode;
156 int err = -EMLINK;
157
158 if (dir->i_nlink >= dir->i_sb->sv_link_max)
159 goto out;
160 inc_count(dir);
161
162 inode = sysv_new_inode(dir, S_IFDIR|mode);
163 err = PTR_ERR(inode);
164 if (IS_ERR(inode))
165 goto out_dir;
166
167 sysv_set_inode(inode, 0);
168
169 inc_count(inode);
170
171 err = sysv_make_empty(inode, dir);
172 if (err)
173 goto out_fail;
174
175 err = sysv_add_link(dentry, inode);
176 if (err)
177 goto out_fail;
178
179 d_instantiate(dentry, inode);
180 out:
181 return err;
182
183 out_fail:
184 dec_count(inode);
185 dec_count(inode);
186 iput(inode);
187 out_dir:
188 dec_count(dir);
189 goto out;
190 }
191
192 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
193 {
194 struct inode * inode = dentry->d_inode;
195 struct page * page;
196 struct sysv_dir_entry * de;
197 int err = -ENOENT;
198
199 de = sysv_find_entry(dentry, &page);
200 if (!de)
201 goto out;
202
203 err = sysv_delete_entry (de, page);
204 if (err)
205 goto out;
206
207 inode->i_ctime = dir->i_ctime;
208 dec_count(inode);
209 out:
210 return err;
211 }
212
213 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
214 {
215 struct inode *inode = dentry->d_inode;
216 int err = -ENOTEMPTY;
217
218 if (sysv_empty_dir(inode)) {
219 err = sysv_unlink(dir, dentry);
220 if (!err) {
221 inode->i_size = 0;
222 dec_count(inode);
223 dec_count(dir);
224 }
225 }
226 return err;
227 }
228
229 /*
230 * Anybody can rename anything with this: the permission checks are left to the
231 * higher-level routines.
232 */
233 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
234 struct inode * new_dir, struct dentry * new_dentry)
235 {
236 struct inode * old_inode = old_dentry->d_inode;
237 struct inode * new_inode = new_dentry->d_inode;
238 struct page * dir_page = NULL;
239 struct sysv_dir_entry * dir_de = NULL;
240 struct page * old_page;
241 struct sysv_dir_entry * old_de;
242 int err = -ENOENT;
243
244 old_de = sysv_find_entry(old_dentry, &old_page);
245 if (!old_de)
246 goto out;
247
248 if (S_ISDIR(old_inode->i_mode)) {
249 err = -EIO;
250 dir_de = sysv_dotdot(old_inode, &dir_page);
251 if (!dir_de)
252 goto out_old;
253 }
254
255 if (new_inode) {
256 struct page * new_page;
257 struct sysv_dir_entry * new_de;
258
259 err = -ENOTEMPTY;
260 if (dir_de && !sysv_empty_dir(new_inode))
261 goto out_dir;
262
263 err = -ENOENT;
264 new_de = sysv_find_entry(new_dentry, &new_page);
265 if (!new_de)
266 goto out_dir;
267 inc_count(old_inode);
268 sysv_set_link(new_de, new_page, old_inode);
269 new_inode->i_ctime = CURRENT_TIME;
270 if (dir_de)
271 new_inode->i_nlink--;
272 dec_count(new_inode);
273 } else {
274 if (dir_de) {
275 err = -EMLINK;
276 if (new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
277 goto out_dir;
278 }
279 inc_count(old_inode);
280 err = sysv_add_link(new_dentry, old_inode);
281 if (err) {
282 dec_count(old_inode);
283 goto out_dir;
284 }
285 if (dir_de)
286 inc_count(new_dir);
287 }
288
289 sysv_delete_entry(old_de, old_page);
290 dec_count(old_inode);
291
292 if (dir_de) {
293 sysv_set_link(dir_de, dir_page, new_dir);
294 dec_count(old_dir);
295 }
296 return 0;
297
298 out_dir:
299 if (dir_de) {
300 kunmap(dir_page);
301 page_cache_release(dir_page);
302 }
303 out_old:
304 kunmap(old_page);
305 page_cache_release(old_page);
306 out:
307 return err;
308 }
309
310 /*
311 * directories can handle most operations...
312 */
313 struct inode_operations sysv_dir_inode_operations = {
314 create: sysv_create,
315 lookup: sysv_lookup,
316 link: sysv_link,
317 unlink: sysv_unlink,
318 symlink: sysv_symlink,
319 mkdir: sysv_mkdir,
320 rmdir: sysv_rmdir,
321 mknod: sysv_mknod,
322 rename: sysv_rename,
323 setattr: sysv_notify_change,
324 };
325