1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/ext2/namei.c
4 *
5 * Rewrite to pagecache. Almost all code had been changed, so blame me
6 * if the things go wrong. Please, send bug reports to
7 * viro@parcelfarce.linux.theplanet.co.uk
8 *
9 * Stuff here is basically a glue between the VFS and generic UNIXish
10 * filesystem that keeps everything in pagecache. All knowledge of the
11 * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
12 * and it's easier to debug that way. In principle we might want to
13 * generalize that a bit and turn it into a library. Or not.
14 *
15 * The only non-static object here is ext2_dir_inode_operations.
16 *
17 * TODO: get rid of kmap() use, add readahead.
18 *
19 * Copyright (C) 1992, 1993, 1994, 1995
20 * Remy Card (card@masi.ibp.fr)
21 * Laboratoire MASI - Institut Blaise Pascal
22 * Universite Pierre et Marie Curie (Paris VI)
23 *
24 * from
25 *
26 * linux/fs/minix/namei.c
27 *
28 * Copyright (C) 1991, 1992 Linus Torvalds
29 *
30 * Big-endian to little-endian byte-swapping/bitmaps by
31 * David S. Miller (davem@caip.rutgers.edu), 1995
32 */
33
34 #include <linux/pagemap.h>
35 #include <linux/quotaops.h>
36 #include "ext2.h"
37 #include "xattr.h"
38 #include "acl.h"
39
ext2_add_nondir(struct dentry * dentry,struct inode * inode)40 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
41 {
42 int err = ext2_add_link(dentry, inode);
43 if (!err) {
44 d_instantiate_new(dentry, inode);
45 return 0;
46 }
47 inode_dec_link_count(inode);
48 discard_new_inode(inode);
49 return err;
50 }
51
52 /*
53 * Methods themselves.
54 */
55
ext2_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)56 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
57 {
58 struct inode * inode;
59 ino_t ino;
60 int res;
61
62 if (dentry->d_name.len > EXT2_NAME_LEN)
63 return ERR_PTR(-ENAMETOOLONG);
64
65 res = ext2_inode_by_name(dir, &dentry->d_name, &ino);
66 if (res) {
67 if (res != -ENOENT)
68 return ERR_PTR(res);
69 inode = NULL;
70 } else {
71 inode = ext2_iget(dir->i_sb, ino);
72 if (inode == ERR_PTR(-ESTALE)) {
73 ext2_error(dir->i_sb, __func__,
74 "deleted inode referenced: %lu",
75 (unsigned long) ino);
76 return ERR_PTR(-EIO);
77 }
78 }
79 return d_splice_alias(inode, dentry);
80 }
81
ext2_get_parent(struct dentry * child)82 struct dentry *ext2_get_parent(struct dentry *child)
83 {
84 struct qstr dotdot = QSTR_INIT("..", 2);
85 ino_t ino;
86 int res;
87
88 res = ext2_inode_by_name(d_inode(child), &dotdot, &ino);
89 if (res)
90 return ERR_PTR(res);
91
92 return d_obtain_alias(ext2_iget(child->d_sb, ino));
93 }
94
95 /*
96 * By the time this is called, we already have created
97 * the directory cache entry for the new file, but it
98 * is so far negative - it has no inode.
99 *
100 * If the create succeeds, we fill in the inode information
101 * with d_instantiate().
102 */
ext2_create(struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)103 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
104 {
105 struct inode *inode;
106 int err;
107
108 err = dquot_initialize(dir);
109 if (err)
110 return err;
111
112 inode = ext2_new_inode(dir, mode, &dentry->d_name);
113 if (IS_ERR(inode))
114 return PTR_ERR(inode);
115
116 ext2_set_file_ops(inode);
117 mark_inode_dirty(inode);
118 return ext2_add_nondir(dentry, inode);
119 }
120
ext2_tmpfile(struct inode * dir,struct dentry * dentry,umode_t mode)121 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
122 {
123 struct inode *inode = ext2_new_inode(dir, mode, NULL);
124 if (IS_ERR(inode))
125 return PTR_ERR(inode);
126
127 ext2_set_file_ops(inode);
128 mark_inode_dirty(inode);
129 d_tmpfile(dentry, inode);
130 unlock_new_inode(inode);
131 return 0;
132 }
133
ext2_mknod(struct inode * dir,struct dentry * dentry,umode_t mode,dev_t rdev)134 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
135 {
136 struct inode * inode;
137 int err;
138
139 err = dquot_initialize(dir);
140 if (err)
141 return err;
142
143 inode = ext2_new_inode (dir, mode, &dentry->d_name);
144 err = PTR_ERR(inode);
145 if (!IS_ERR(inode)) {
146 init_special_inode(inode, inode->i_mode, rdev);
147 inode->i_op = &ext2_special_inode_operations;
148 mark_inode_dirty(inode);
149 err = ext2_add_nondir(dentry, inode);
150 }
151 return err;
152 }
153
ext2_symlink(struct inode * dir,struct dentry * dentry,const char * symname)154 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
155 const char * symname)
156 {
157 struct super_block * sb = dir->i_sb;
158 int err = -ENAMETOOLONG;
159 unsigned l = strlen(symname)+1;
160 struct inode * inode;
161
162 if (l > sb->s_blocksize)
163 goto out;
164
165 err = dquot_initialize(dir);
166 if (err)
167 goto out;
168
169 inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
170 err = PTR_ERR(inode);
171 if (IS_ERR(inode))
172 goto out;
173
174 if (l > sizeof (EXT2_I(inode)->i_data)) {
175 /* slow symlink */
176 inode->i_op = &ext2_symlink_inode_operations;
177 inode_nohighmem(inode);
178 if (test_opt(inode->i_sb, NOBH))
179 inode->i_mapping->a_ops = &ext2_nobh_aops;
180 else
181 inode->i_mapping->a_ops = &ext2_aops;
182 err = page_symlink(inode, symname, l);
183 if (err)
184 goto out_fail;
185 } else {
186 /* fast symlink */
187 inode->i_op = &ext2_fast_symlink_inode_operations;
188 inode->i_link = (char*)EXT2_I(inode)->i_data;
189 memcpy(inode->i_link, symname, l);
190 inode->i_size = l-1;
191 }
192 mark_inode_dirty(inode);
193
194 err = ext2_add_nondir(dentry, inode);
195 out:
196 return err;
197
198 out_fail:
199 inode_dec_link_count(inode);
200 discard_new_inode(inode);
201 goto out;
202 }
203
ext2_link(struct dentry * old_dentry,struct inode * dir,struct dentry * dentry)204 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
205 struct dentry *dentry)
206 {
207 struct inode *inode = d_inode(old_dentry);
208 int err;
209
210 err = dquot_initialize(dir);
211 if (err)
212 return err;
213
214 inode->i_ctime = current_time(inode);
215 inode_inc_link_count(inode);
216 ihold(inode);
217
218 err = ext2_add_link(dentry, inode);
219 if (!err) {
220 d_instantiate(dentry, inode);
221 return 0;
222 }
223 inode_dec_link_count(inode);
224 iput(inode);
225 return err;
226 }
227
ext2_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode)228 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
229 {
230 struct inode * inode;
231 int err;
232
233 err = dquot_initialize(dir);
234 if (err)
235 return err;
236
237 inode_inc_link_count(dir);
238
239 inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
240 err = PTR_ERR(inode);
241 if (IS_ERR(inode))
242 goto out_dir;
243
244 inode->i_op = &ext2_dir_inode_operations;
245 inode->i_fop = &ext2_dir_operations;
246 if (test_opt(inode->i_sb, NOBH))
247 inode->i_mapping->a_ops = &ext2_nobh_aops;
248 else
249 inode->i_mapping->a_ops = &ext2_aops;
250
251 inode_inc_link_count(inode);
252
253 err = ext2_make_empty(inode, dir);
254 if (err)
255 goto out_fail;
256
257 err = ext2_add_link(dentry, inode);
258 if (err)
259 goto out_fail;
260
261 d_instantiate_new(dentry, inode);
262 out:
263 return err;
264
265 out_fail:
266 inode_dec_link_count(inode);
267 inode_dec_link_count(inode);
268 discard_new_inode(inode);
269 out_dir:
270 inode_dec_link_count(dir);
271 goto out;
272 }
273
ext2_unlink(struct inode * dir,struct dentry * dentry)274 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
275 {
276 struct inode * inode = d_inode(dentry);
277 struct ext2_dir_entry_2 * de;
278 struct page * page;
279 int err;
280
281 err = dquot_initialize(dir);
282 if (err)
283 goto out;
284
285 de = ext2_find_entry(dir, &dentry->d_name, &page);
286 if (IS_ERR(de)) {
287 err = PTR_ERR(de);
288 goto out;
289 }
290
291 err = ext2_delete_entry (de, page);
292 if (err)
293 goto out;
294
295 inode->i_ctime = dir->i_ctime;
296 inode_dec_link_count(inode);
297 err = 0;
298 out:
299 return err;
300 }
301
ext2_rmdir(struct inode * dir,struct dentry * dentry)302 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
303 {
304 struct inode * inode = d_inode(dentry);
305 int err = -ENOTEMPTY;
306
307 if (ext2_empty_dir(inode)) {
308 err = ext2_unlink(dir, dentry);
309 if (!err) {
310 inode->i_size = 0;
311 inode_dec_link_count(inode);
312 inode_dec_link_count(dir);
313 }
314 }
315 return err;
316 }
317
ext2_rename(struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)318 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
319 struct inode * new_dir, struct dentry * new_dentry,
320 unsigned int flags)
321 {
322 struct inode * old_inode = d_inode(old_dentry);
323 struct inode * new_inode = d_inode(new_dentry);
324 struct page * dir_page = NULL;
325 struct ext2_dir_entry_2 * dir_de = NULL;
326 struct page * old_page;
327 struct ext2_dir_entry_2 * old_de;
328 int err;
329
330 if (flags & ~RENAME_NOREPLACE)
331 return -EINVAL;
332
333 err = dquot_initialize(old_dir);
334 if (err)
335 goto out;
336
337 err = dquot_initialize(new_dir);
338 if (err)
339 goto out;
340
341 old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_page);
342 if (IS_ERR(old_de)) {
343 err = PTR_ERR(old_de);
344 goto out;
345 }
346
347 if (S_ISDIR(old_inode->i_mode)) {
348 err = -EIO;
349 dir_de = ext2_dotdot(old_inode, &dir_page);
350 if (!dir_de)
351 goto out_old;
352 }
353
354 if (new_inode) {
355 struct page *new_page;
356 struct ext2_dir_entry_2 *new_de;
357
358 err = -ENOTEMPTY;
359 if (dir_de && !ext2_empty_dir (new_inode))
360 goto out_dir;
361
362 new_de = ext2_find_entry(new_dir, &new_dentry->d_name, &new_page);
363 if (IS_ERR(new_de)) {
364 err = PTR_ERR(new_de);
365 goto out_dir;
366 }
367 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
368 new_inode->i_ctime = current_time(new_inode);
369 if (dir_de)
370 drop_nlink(new_inode);
371 inode_dec_link_count(new_inode);
372 } else {
373 err = ext2_add_link(new_dentry, old_inode);
374 if (err)
375 goto out_dir;
376 if (dir_de)
377 inode_inc_link_count(new_dir);
378 }
379
380 /*
381 * Like most other Unix systems, set the ctime for inodes on a
382 * rename.
383 */
384 old_inode->i_ctime = current_time(old_inode);
385 mark_inode_dirty(old_inode);
386
387 ext2_delete_entry (old_de, old_page);
388
389 if (dir_de) {
390 if (old_dir != new_dir)
391 ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
392 else {
393 kunmap(dir_page);
394 put_page(dir_page);
395 }
396 inode_dec_link_count(old_dir);
397 }
398 return 0;
399
400
401 out_dir:
402 if (dir_de) {
403 kunmap(dir_page);
404 put_page(dir_page);
405 }
406 out_old:
407 kunmap(old_page);
408 put_page(old_page);
409 out:
410 return err;
411 }
412
413 const struct inode_operations ext2_dir_inode_operations = {
414 .create = ext2_create,
415 .lookup = ext2_lookup,
416 .link = ext2_link,
417 .unlink = ext2_unlink,
418 .symlink = ext2_symlink,
419 .mkdir = ext2_mkdir,
420 .rmdir = ext2_rmdir,
421 .mknod = ext2_mknod,
422 .rename = ext2_rename,
423 .listxattr = ext2_listxattr,
424 .getattr = ext2_getattr,
425 .setattr = ext2_setattr,
426 .get_acl = ext2_get_acl,
427 .set_acl = ext2_set_acl,
428 .tmpfile = ext2_tmpfile,
429 };
430
431 const struct inode_operations ext2_special_inode_operations = {
432 .listxattr = ext2_listxattr,
433 .getattr = ext2_getattr,
434 .setattr = ext2_setattr,
435 .get_acl = ext2_get_acl,
436 .set_acl = ext2_set_acl,
437 };
438