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
6 * viro@parcelfarce.linux.theplanet.co.uk
7 *
8 * Stuff here is basically a glue between the VFS and generic UNIXish
9 * filesystem that keeps everything in pagecache. All knowledge of the
10 * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
11 * and it's easier to debug that way. In principle we might want to
12 * generalize that a bit and turn it into a library. Or not.
13 *
14 * The only non-static object here is ext2_dir_inode_operations.
15 *
16 * TODO: get rid of kmap() use, add readahead.
17 *
18 * Copyright (C) 1992, 1993, 1994, 1995
19 * Remy Card (card@masi.ibp.fr)
20 * Laboratoire MASI - Institut Blaise Pascal
21 * Universite Pierre et Marie Curie (Paris VI)
22 *
23 * from
24 *
25 * linux/fs/minix/namei.c
26 *
27 * Copyright (C) 1991, 1992 Linus Torvalds
28 *
29 * Big-endian to little-endian byte-swapping/bitmaps by
30 * David S. Miller (davem@caip.rutgers.edu), 1995
31 */
32
33 #include <linux/pagemap.h>
34 #include "ext2.h"
35 #include "xattr.h"
36 #include "acl.h"
37
38 /*
39 * Couple of helper functions - make the code slightly cleaner.
40 */
41
42 static inline void ext2_inc_count(struct inode *inode)
43 {
44 inode->i_nlink++;
45 mark_inode_dirty(inode);
46 }
47
48 static inline void ext2_dec_count(struct inode *inode)
49 {
50 inode->i_nlink--;
51 mark_inode_dirty(inode);
52 }
53
54 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
55 {
56 int err = ext2_add_link(dentry, inode);
57 if (!err) {
58 d_instantiate(dentry, inode);
59 return 0;
60 }
61 ext2_dec_count(inode);
62 iput(inode);
63 return err;
64 }
65
66 /*
67 * Methods themselves.
68 */
69
70 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
71 {
72 struct inode * inode;
73 ino_t ino;
74
75 if (dentry->d_name.len > EXT2_NAME_LEN)
76 return ERR_PTR(-ENAMETOOLONG);
77
78 ino = ext2_inode_by_name(dir, dentry);
79 inode = NULL;
80 if (ino) {
81 inode = iget(dir->i_sb, ino);
82 if (!inode)
83 return ERR_PTR(-EACCES);
84 }
85 if (inode)
86 return d_splice_alias(inode, dentry);
87 d_add(dentry, inode);
88 return NULL;
89 }
90
91 struct dentry *ext2_get_parent(struct dentry *child)
92 {
93 unsigned long ino;
94 struct dentry *parent;
95 struct inode *inode;
96 struct dentry dotdot;
97
98 dotdot.d_name.name = "..";
99 dotdot.d_name.len = 2;
100
101 ino = ext2_inode_by_name(child->d_inode, &dotdot);
102 if (!ino)
103 return ERR_PTR(-ENOENT);
104 inode = iget(child->d_inode->i_sb, ino);
105
106 if (!inode)
107 return ERR_PTR(-EACCES);
108 parent = d_alloc_anon(inode);
109 if (!parent) {
110 iput(inode);
111 parent = ERR_PTR(-ENOMEM);
112 }
113 return parent;
114 }
115
116 /*
117 * By the time this is called, we already have created
118 * the directory cache entry for the new file, but it
119 * is so far negative - it has no inode.
120 *
121 * If the create succeeds, we fill in the inode information
122 * with d_instantiate().
123 */
124 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
125 {
126 struct inode * inode = ext2_new_inode (dir, mode);
127 int err = PTR_ERR(inode);
128 if (!IS_ERR(inode)) {
129 inode->i_op = &ext2_file_inode_operations;
130 inode->i_fop = &ext2_file_operations;
131 if (test_opt(inode->i_sb, NOBH))
132 inode->i_mapping->a_ops = &ext2_nobh_aops;
133 else
134 inode->i_mapping->a_ops = &ext2_aops;
135 mark_inode_dirty(inode);
136 err = ext2_add_nondir(dentry, inode);
137 }
138 return err;
139 }
140
141 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
142 {
143 struct inode * inode;
144 int err;
145
146 if (!new_valid_dev(rdev))
147 return -EINVAL;
148
149 inode = ext2_new_inode (dir, mode);
150 err = PTR_ERR(inode);
151 if (!IS_ERR(inode)) {
152 init_special_inode(inode, inode->i_mode, rdev);
153 #ifdef CONFIG_EXT2_FS_XATTR
154 inode->i_op = &ext2_special_inode_operations;
155 #endif
156 mark_inode_dirty(inode);
157 err = ext2_add_nondir(dentry, inode);
158 }
159 return err;
160 }
161
162 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
163 const char * symname)
164 {
165 struct super_block * sb = dir->i_sb;
166 int err = -ENAMETOOLONG;
167 unsigned l = strlen(symname)+1;
168 struct inode * inode;
169
170 if (l > sb->s_blocksize)
171 goto out;
172
173 inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
174 err = PTR_ERR(inode);
175 if (IS_ERR(inode))
176 goto out;
177
178 if (l > sizeof (EXT2_I(inode)->i_data)) {
179 /* slow symlink */
180 inode->i_op = &ext2_symlink_inode_operations;
181 if (test_opt(inode->i_sb, NOBH))
182 inode->i_mapping->a_ops = &ext2_nobh_aops;
183 else
184 inode->i_mapping->a_ops = &ext2_aops;
185 err = page_symlink(inode, symname, l);
186 if (err)
187 goto out_fail;
188 } else {
189 /* fast symlink */
190 inode->i_op = &ext2_fast_symlink_inode_operations;
191 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
192 inode->i_size = l-1;
193 }
194 mark_inode_dirty(inode);
195
196 err = ext2_add_nondir(dentry, inode);
197 out:
198 return err;
199
200 out_fail:
201 ext2_dec_count(inode);
202 iput (inode);
203 goto out;
204 }
205
206 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
207 struct dentry *dentry)
208 {
209 struct inode *inode = old_dentry->d_inode;
210
211 if (inode->i_nlink >= EXT2_LINK_MAX)
212 return -EMLINK;
213
214 inode->i_ctime = CURRENT_TIME_SEC;
215 ext2_inc_count(inode);
216 atomic_inc(&inode->i_count);
217
218 return ext2_add_nondir(dentry, inode);
219 }
220
221 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
222 {
223 struct inode * inode;
224 int err = -EMLINK;
225
226 if (dir->i_nlink >= EXT2_LINK_MAX)
227 goto out;
228
229 ext2_inc_count(dir);
230
231 inode = ext2_new_inode (dir, S_IFDIR | mode);
232 err = PTR_ERR(inode);
233 if (IS_ERR(inode))
234 goto out_dir;
235
236 inode->i_op = &ext2_dir_inode_operations;
237 inode->i_fop = &ext2_dir_operations;
238 if (test_opt(inode->i_sb, NOBH))
239 inode->i_mapping->a_ops = &ext2_nobh_aops;
240 else
241 inode->i_mapping->a_ops = &ext2_aops;
242
243 ext2_inc_count(inode);
244
245 err = ext2_make_empty(inode, dir);
246 if (err)
247 goto out_fail;
248
249 err = ext2_add_link(dentry, inode);
250 if (err)
251 goto out_fail;
252
253 d_instantiate(dentry, inode);
254 out:
255 return err;
256
257 out_fail:
258 ext2_dec_count(inode);
259 ext2_dec_count(inode);
260 iput(inode);
261 out_dir:
262 ext2_dec_count(dir);
263 goto out;
264 }
265
266 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
267 {
268 struct inode * inode = dentry->d_inode;
269 struct ext2_dir_entry_2 * de;
270 struct page * page;
271 int err = -ENOENT;
272
273 de = ext2_find_entry (dir, dentry, &page);
274 if (!de)
275 goto out;
276
277 err = ext2_delete_entry (de, page);
278 if (err)
279 goto out;
280
281 inode->i_ctime = dir->i_ctime;
282 ext2_dec_count(inode);
283 err = 0;
284 out:
285 return err;
286 }
287
288 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
289 {
290 struct inode * inode = dentry->d_inode;
291 int err = -ENOTEMPTY;
292
293 if (ext2_empty_dir(inode)) {
294 err = ext2_unlink(dir, dentry);
295 if (!err) {
296 inode->i_size = 0;
297 ext2_dec_count(inode);
298 ext2_dec_count(dir);
299 }
300 }
301 return err;
302 }
303
304 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
305 struct inode * new_dir, struct dentry * new_dentry )
306 {
307 struct inode * old_inode = old_dentry->d_inode;
308 struct inode * new_inode = new_dentry->d_inode;
309 struct page * dir_page = NULL;
310 struct ext2_dir_entry_2 * dir_de = NULL;
311 struct page * old_page;
312 struct ext2_dir_entry_2 * old_de;
313 int err = -ENOENT;
314
315 old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
316 if (!old_de)
317 goto out;
318
319 if (S_ISDIR(old_inode->i_mode)) {
320 err = -EIO;
321 dir_de = ext2_dotdot(old_inode, &dir_page);
322 if (!dir_de)
323 goto out_old;
324 }
325
326 if (new_inode) {
327 struct page *new_page;
328 struct ext2_dir_entry_2 *new_de;
329
330 err = -ENOTEMPTY;
331 if (dir_de && !ext2_empty_dir (new_inode))
332 goto out_dir;
333
334 err = -ENOENT;
335 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
336 if (!new_de)
337 goto out_dir;
338 ext2_inc_count(old_inode);
339 ext2_set_link(new_dir, new_de, new_page, old_inode);
340 new_inode->i_ctime = CURRENT_TIME_SEC;
341 if (dir_de)
342 new_inode->i_nlink--;
343 ext2_dec_count(new_inode);
344 } else {
345 if (dir_de) {
346 err = -EMLINK;
347 if (new_dir->i_nlink >= EXT2_LINK_MAX)
348 goto out_dir;
349 }
350 ext2_inc_count(old_inode);
351 err = ext2_add_link(new_dentry, old_inode);
352 if (err) {
353 ext2_dec_count(old_inode);
354 goto out_dir;
355 }
356 if (dir_de)
357 ext2_inc_count(new_dir);
358 }
359
360 /*
361 * Like most other Unix systems, set the ctime for inodes on a
362 * rename.
363 * ext2_dec_count() will mark the inode dirty.
364 */
365 old_inode->i_ctime = CURRENT_TIME_SEC;
366
367 ext2_delete_entry (old_de, old_page);
368 ext2_dec_count(old_inode);
369
370 if (dir_de) {
371 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
372 ext2_dec_count(old_dir);
373 }
374 return 0;
375
376
377 out_dir:
378 if (dir_de) {
379 kunmap(dir_page);
380 page_cache_release(dir_page);
381 }
382 out_old:
383 kunmap(old_page);
384 page_cache_release(old_page);
385 out:
386 return err;
387 }
388
389 struct inode_operations ext2_dir_inode_operations = {
390 .create = ext2_create,
391 .lookup = ext2_lookup,
392 .link = ext2_link,
393 .unlink = ext2_unlink,
394 .symlink = ext2_symlink,
395 .mkdir = ext2_mkdir,
396 .rmdir = ext2_rmdir,
397 .mknod = ext2_mknod,
398 .rename = ext2_rename,
399 #ifdef CONFIG_EXT2_FS_XATTR
400 .setxattr = generic_setxattr,
401 .getxattr = generic_getxattr,
402 .listxattr = ext2_listxattr,
403 .removexattr = generic_removexattr,
404 #endif
405 .setattr = ext2_setattr,
406 .permission = ext2_permission,
407 };
408
409 struct inode_operations ext2_special_inode_operations = {
410 #ifdef CONFIG_EXT2_FS_XATTR
411 .setxattr = generic_setxattr,
412 .getxattr = generic_getxattr,
413 .listxattr = ext2_listxattr,
414 .removexattr = generic_removexattr,
415 #endif
416 .setattr = ext2_setattr,
417 .permission = ext2_permission,
418 };
419
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