File: /usr/src/linux/fs/ext2/namei.c
1 /*
2 * linux/fs/ext2/namei.c
3 *
4 * Rewrite to pagecache. Almost all code had been changed, so blame me
5 * if the things go wrong. Please, send bug reports to viro@math.psu.edu
6 *
7 * Stuff here is basically a glue between the VFS and generic UNIXish
8 * filesystem that keeps everything in pagecache. All knowledge of the
9 * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
10 * and it's easier to debug that way. In principle we might want to
11 * generalize that a bit and turn it into a library. Or not.
12 *
13 * The only non-static object here is ext2_dir_inode_operations.
14 *
15 * TODO: get rid of kmap() use, add readahead.
16 *
17 * Copyright (C) 1992, 1993, 1994, 1995
18 * Remy Card (card@masi.ibp.fr)
19 * Laboratoire MASI - Institut Blaise Pascal
20 * Universite Pierre et Marie Curie (Paris VI)
21 *
22 * from
23 *
24 * linux/fs/minix/namei.c
25 *
26 * Copyright (C) 1991, 1992 Linus Torvalds
27 *
28 * Big-endian to little-endian byte-swapping/bitmaps by
29 * David S. Miller (davem@caip.rutgers.edu), 1995
30 */
31
32 #include <linux/fs.h>
33 #include <linux/ext2_fs.h>
34 #include <linux/pagemap.h>
35
36 /*
37 * Couple of helper functions - make the code slightly cleaner.
38 */
39
40 static inline void ext2_inc_count(struct inode *inode)
41 {
42 inode->i_nlink++;
43 mark_inode_dirty(inode);
44 }
45
46 static inline void ext2_dec_count(struct inode *inode)
47 {
48 inode->i_nlink--;
49 mark_inode_dirty(inode);
50 }
51
52 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
53 {
54 int err = ext2_add_link(dentry, inode);
55 if (!err) {
56 d_instantiate(dentry, inode);
57 return 0;
58 }
59 ext2_dec_count(inode);
60 iput(inode);
61 return err;
62 }
63
64 /*
65 * Methods themselves.
66 */
67
68 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry)
69 {
70 struct inode * inode;
71 ino_t ino;
72
73 if (dentry->d_name.len > EXT2_NAME_LEN)
74 return ERR_PTR(-ENAMETOOLONG);
75
76 ino = ext2_inode_by_name(dir, dentry);
77 inode = NULL;
78 if (ino) {
79 inode = iget(dir->i_sb, ino);
80 if (!inode)
81 return ERR_PTR(-EACCES);
82 }
83 d_add(dentry, inode);
84 return NULL;
85 }
86
87 /*
88 * By the time this is called, we already have created
89 * the directory cache entry for the new file, but it
90 * is so far negative - it has no inode.
91 *
92 * If the create succeeds, we fill in the inode information
93 * with d_instantiate().
94 */
95 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode)
96 {
97 struct inode * inode = ext2_new_inode (dir, mode);
98 int err = PTR_ERR(inode);
99 if (!IS_ERR(inode)) {
100 inode->i_op = &ext2_file_inode_operations;
101 inode->i_fop = &ext2_file_operations;
102 inode->i_mapping->a_ops = &ext2_aops;
103 mark_inode_dirty(inode);
104 err = ext2_add_nondir(dentry, inode);
105 }
106 return err;
107 }
108
109 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, int rdev)
110 {
111 struct inode * inode = ext2_new_inode (dir, mode);
112 int err = PTR_ERR(inode);
113 if (!IS_ERR(inode)) {
114 init_special_inode(inode, mode, rdev);
115 mark_inode_dirty(inode);
116 err = ext2_add_nondir(dentry, inode);
117 }
118 return err;
119 }
120
121 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
122 const char * symname)
123 {
124 struct super_block * sb = dir->i_sb;
125 int err = -ENAMETOOLONG;
126 unsigned l = strlen(symname)+1;
127 struct inode * inode;
128
129 if (l > sb->s_blocksize)
130 goto out;
131
132 inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
133 err = PTR_ERR(inode);
134 if (IS_ERR(inode))
135 goto out;
136
137 if (l > sizeof (inode->u.ext2_i.i_data)) {
138 /* slow symlink */
139 inode->i_op = &page_symlink_inode_operations;
140 inode->i_mapping->a_ops = &ext2_aops;
141 err = block_symlink(inode, symname, l);
142 if (err)
143 goto out_fail;
144 } else {
145 /* fast symlink */
146 inode->i_op = &ext2_fast_symlink_inode_operations;
147 memcpy((char*)&inode->u.ext2_i.i_data,symname,l);
148 inode->i_size = l-1;
149 }
150 mark_inode_dirty(inode);
151
152 err = ext2_add_nondir(dentry, inode);
153 out:
154 return err;
155
156 out_fail:
157 ext2_dec_count(inode);
158 iput (inode);
159 goto out;
160 }
161
162 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
163 struct dentry *dentry)
164 {
165 struct inode *inode = old_dentry->d_inode;
166
167 if (S_ISDIR(inode->i_mode))
168 return -EPERM;
169
170 if (inode->i_nlink >= EXT2_LINK_MAX)
171 return -EMLINK;
172
173 inode->i_ctime = CURRENT_TIME;
174 ext2_inc_count(inode);
175 atomic_inc(&inode->i_count);
176
177 return ext2_add_nondir(dentry, inode);
178 }
179
180 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
181 {
182 struct inode * inode;
183 int err = -EMLINK;
184
185 if (dir->i_nlink >= EXT2_LINK_MAX)
186 goto out;
187
188 ext2_inc_count(dir);
189
190 inode = ext2_new_inode (dir, S_IFDIR | mode);
191 err = PTR_ERR(inode);
192 if (IS_ERR(inode))
193 goto out_dir;
194
195 inode->i_op = &ext2_dir_inode_operations;
196 inode->i_fop = &ext2_dir_operations;
197 inode->i_mapping->a_ops = &ext2_aops;
198
199 ext2_inc_count(inode);
200
201 err = ext2_make_empty(inode, dir);
202 if (err)
203 goto out_fail;
204
205 err = ext2_add_link(dentry, inode);
206 if (err)
207 goto out_fail;
208
209 d_instantiate(dentry, inode);
210 out:
211 return err;
212
213 out_fail:
214 ext2_dec_count(inode);
215 ext2_dec_count(inode);
216 iput(inode);
217 out_dir:
218 ext2_dec_count(dir);
219 goto out;
220 }
221
222 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
223 {
224 struct inode * inode = dentry->d_inode;
225 struct ext2_dir_entry_2 * de;
226 struct page * page;
227 int err = -ENOENT;
228
229 de = ext2_find_entry (dir, dentry, &page);
230 if (!de)
231 goto out;
232
233 err = ext2_delete_entry (de, page);
234 if (err)
235 goto out;
236
237 inode->i_ctime = dir->i_ctime;
238 ext2_dec_count(inode);
239 err = 0;
240 out:
241 return err;
242 }
243
244 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
245 {
246 struct inode * inode = dentry->d_inode;
247 int err = -ENOTEMPTY;
248
249 if (ext2_empty_dir(inode)) {
250 err = ext2_unlink(dir, dentry);
251 if (!err) {
252 inode->i_size = 0;
253 ext2_dec_count(inode);
254 ext2_dec_count(dir);
255 }
256 }
257 return err;
258 }
259
260 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
261 struct inode * new_dir, struct dentry * new_dentry )
262 {
263 struct inode * old_inode = old_dentry->d_inode;
264 struct inode * new_inode = new_dentry->d_inode;
265 struct page * dir_page = NULL;
266 struct ext2_dir_entry_2 * dir_de = NULL;
267 struct page * old_page;
268 struct ext2_dir_entry_2 * old_de;
269 int err = -ENOENT;
270
271 old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
272 if (!old_de)
273 goto out;
274
275 if (S_ISDIR(old_inode->i_mode)) {
276 err = -EIO;
277 dir_de = ext2_dotdot(old_inode, &dir_page);
278 if (!dir_de)
279 goto out_old;
280 }
281
282 if (new_inode) {
283 struct page *new_page;
284 struct ext2_dir_entry_2 *new_de;
285
286 err = -ENOTEMPTY;
287 if (dir_de && !ext2_empty_dir (new_inode))
288 goto out_dir;
289
290 err = -ENOENT;
291 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
292 if (!new_de)
293 goto out_dir;
294 ext2_inc_count(old_inode);
295 ext2_set_link(new_dir, new_de, new_page, old_inode);
296 new_inode->i_ctime = CURRENT_TIME;
297 if (dir_de)
298 new_inode->i_nlink--;
299 ext2_dec_count(new_inode);
300 } else {
301 if (dir_de) {
302 err = -EMLINK;
303 if (new_dir->i_nlink >= EXT2_LINK_MAX)
304 goto out_dir;
305 }
306 ext2_inc_count(old_inode);
307 err = ext2_add_link(new_dentry, old_inode);
308 if (err) {
309 ext2_dec_count(old_inode);
310 goto out_dir;
311 }
312 if (dir_de)
313 ext2_inc_count(new_dir);
314 }
315
316 ext2_delete_entry (old_de, old_page);
317 ext2_dec_count(old_inode);
318
319 if (dir_de) {
320 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
321 ext2_dec_count(old_dir);
322 }
323 return 0;
324
325
326 out_dir:
327 if (dir_de) {
328 kunmap(dir_page);
329 page_cache_release(dir_page);
330 }
331 out_old:
332 kunmap(old_page);
333 page_cache_release(old_page);
334 out:
335 return err;
336 }
337
338 struct inode_operations ext2_dir_inode_operations = {
339 create: ext2_create,
340 lookup: ext2_lookup,
341 link: ext2_link,
342 unlink: ext2_unlink,
343 symlink: ext2_symlink,
344 mkdir: ext2_mkdir,
345 rmdir: ext2_rmdir,
346 mknod: ext2_mknod,
347 rename: ext2_rename,
348 };
349