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 ino_t ino;
85 int res;
86
87 res = ext2_inode_by_name(d_inode(child), &dotdot_name, &ino);
88 if (res)
89 return ERR_PTR(res);
90
91 return d_obtain_alias(ext2_iget(child->d_sb, ino));
92 }
93
94 /*
95 * By the time this is called, we already have created
96 * the directory cache entry for the new file, but it
97 * is so far negative - it has no inode.
98 *
99 * If the create succeeds, we fill in the inode information
100 * with d_instantiate().
101 */
ext2_create(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)102 static int ext2_create (struct user_namespace * mnt_userns,
103 struct inode * dir, struct dentry * dentry,
104 umode_t mode, bool excl)
105 {
106 struct inode *inode;
107 int err;
108
109 err = dquot_initialize(dir);
110 if (err)
111 return err;
112
113 inode = ext2_new_inode(dir, mode, &dentry->d_name);
114 if (IS_ERR(inode))
115 return PTR_ERR(inode);
116
117 ext2_set_file_ops(inode);
118 mark_inode_dirty(inode);
119 return ext2_add_nondir(dentry, inode);
120 }
121
ext2_tmpfile(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode)122 static int ext2_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
123 struct dentry *dentry, umode_t mode)
124 {
125 struct inode *inode = ext2_new_inode(dir, mode, NULL);
126 if (IS_ERR(inode))
127 return PTR_ERR(inode);
128
129 ext2_set_file_ops(inode);
130 mark_inode_dirty(inode);
131 d_tmpfile(dentry, inode);
132 unlock_new_inode(inode);
133 return 0;
134 }
135
ext2_mknod(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode,dev_t rdev)136 static int ext2_mknod (struct user_namespace * mnt_userns, struct inode * dir,
137 struct dentry *dentry, umode_t mode, dev_t rdev)
138 {
139 struct inode * inode;
140 int err;
141
142 err = dquot_initialize(dir);
143 if (err)
144 return err;
145
146 inode = ext2_new_inode (dir, mode, &dentry->d_name);
147 err = PTR_ERR(inode);
148 if (!IS_ERR(inode)) {
149 init_special_inode(inode, inode->i_mode, rdev);
150 inode->i_op = &ext2_special_inode_operations;
151 mark_inode_dirty(inode);
152 err = ext2_add_nondir(dentry, inode);
153 }
154 return err;
155 }
156
ext2_symlink(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,const char * symname)157 static int ext2_symlink (struct user_namespace * mnt_userns, struct inode * dir,
158 struct dentry * dentry, const char * symname)
159 {
160 struct super_block * sb = dir->i_sb;
161 int err = -ENAMETOOLONG;
162 unsigned l = strlen(symname)+1;
163 struct inode * inode;
164
165 if (l > sb->s_blocksize)
166 goto out;
167
168 err = dquot_initialize(dir);
169 if (err)
170 goto out;
171
172 inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
173 err = PTR_ERR(inode);
174 if (IS_ERR(inode))
175 goto out;
176
177 if (l > sizeof (EXT2_I(inode)->i_data)) {
178 /* slow symlink */
179 inode->i_op = &ext2_symlink_inode_operations;
180 inode_nohighmem(inode);
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 inode->i_link = (char*)EXT2_I(inode)->i_data;
192 memcpy(inode->i_link, symname, l);
193 inode->i_size = l-1;
194 }
195 mark_inode_dirty(inode);
196
197 err = ext2_add_nondir(dentry, inode);
198 out:
199 return err;
200
201 out_fail:
202 inode_dec_link_count(inode);
203 discard_new_inode(inode);
204 goto out;
205 }
206
ext2_link(struct dentry * old_dentry,struct inode * dir,struct dentry * dentry)207 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
208 struct dentry *dentry)
209 {
210 struct inode *inode = d_inode(old_dentry);
211 int err;
212
213 err = dquot_initialize(dir);
214 if (err)
215 return err;
216
217 inode->i_ctime = current_time(inode);
218 inode_inc_link_count(inode);
219 ihold(inode);
220
221 err = ext2_add_link(dentry, inode);
222 if (!err) {
223 d_instantiate(dentry, inode);
224 return 0;
225 }
226 inode_dec_link_count(inode);
227 iput(inode);
228 return err;
229 }
230
ext2_mkdir(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode)231 static int ext2_mkdir(struct user_namespace * mnt_userns,
232 struct inode * dir, struct dentry * dentry, umode_t mode)
233 {
234 struct inode * inode;
235 int err;
236
237 err = dquot_initialize(dir);
238 if (err)
239 return err;
240
241 inode_inc_link_count(dir);
242
243 inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
244 err = PTR_ERR(inode);
245 if (IS_ERR(inode))
246 goto out_dir;
247
248 inode->i_op = &ext2_dir_inode_operations;
249 inode->i_fop = &ext2_dir_operations;
250 if (test_opt(inode->i_sb, NOBH))
251 inode->i_mapping->a_ops = &ext2_nobh_aops;
252 else
253 inode->i_mapping->a_ops = &ext2_aops;
254
255 inode_inc_link_count(inode);
256
257 err = ext2_make_empty(inode, dir);
258 if (err)
259 goto out_fail;
260
261 err = ext2_add_link(dentry, inode);
262 if (err)
263 goto out_fail;
264
265 d_instantiate_new(dentry, inode);
266 out:
267 return err;
268
269 out_fail:
270 inode_dec_link_count(inode);
271 inode_dec_link_count(inode);
272 discard_new_inode(inode);
273 out_dir:
274 inode_dec_link_count(dir);
275 goto out;
276 }
277
ext2_unlink(struct inode * dir,struct dentry * dentry)278 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
279 {
280 struct inode * inode = d_inode(dentry);
281 struct ext2_dir_entry_2 * de;
282 struct page * page;
283 void *page_addr;
284 int err;
285
286 err = dquot_initialize(dir);
287 if (err)
288 goto out;
289
290 de = ext2_find_entry(dir, &dentry->d_name, &page, &page_addr);
291 if (IS_ERR(de)) {
292 err = PTR_ERR(de);
293 goto out;
294 }
295
296 err = ext2_delete_entry (de, page, page_addr);
297 ext2_put_page(page, page_addr);
298 if (err)
299 goto out;
300
301 inode->i_ctime = dir->i_ctime;
302 inode_dec_link_count(inode);
303 err = 0;
304 out:
305 return err;
306 }
307
ext2_rmdir(struct inode * dir,struct dentry * dentry)308 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
309 {
310 struct inode * inode = d_inode(dentry);
311 int err = -ENOTEMPTY;
312
313 if (ext2_empty_dir(inode)) {
314 err = ext2_unlink(dir, dentry);
315 if (!err) {
316 inode->i_size = 0;
317 inode_dec_link_count(inode);
318 inode_dec_link_count(dir);
319 }
320 }
321 return err;
322 }
323
ext2_rename(struct user_namespace * mnt_userns,struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)324 static int ext2_rename (struct user_namespace * mnt_userns,
325 struct inode * old_dir, struct dentry * old_dentry,
326 struct inode * new_dir, struct dentry * new_dentry,
327 unsigned int flags)
328 {
329 struct inode * old_inode = d_inode(old_dentry);
330 struct inode * new_inode = d_inode(new_dentry);
331 struct page * dir_page = NULL;
332 void *dir_page_addr;
333 struct ext2_dir_entry_2 * dir_de = NULL;
334 struct page * old_page;
335 void *old_page_addr;
336 struct ext2_dir_entry_2 * old_de;
337 int err;
338
339 if (flags & ~RENAME_NOREPLACE)
340 return -EINVAL;
341
342 err = dquot_initialize(old_dir);
343 if (err)
344 goto out;
345
346 err = dquot_initialize(new_dir);
347 if (err)
348 goto out;
349
350 old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_page,
351 &old_page_addr);
352 if (IS_ERR(old_de)) {
353 err = PTR_ERR(old_de);
354 goto out;
355 }
356
357 if (S_ISDIR(old_inode->i_mode)) {
358 err = -EIO;
359 dir_de = ext2_dotdot(old_inode, &dir_page, &dir_page_addr);
360 if (!dir_de)
361 goto out_old;
362 }
363
364 if (new_inode) {
365 void *page_addr;
366 struct page *new_page;
367 struct ext2_dir_entry_2 *new_de;
368
369 err = -ENOTEMPTY;
370 if (dir_de && !ext2_empty_dir (new_inode))
371 goto out_dir;
372
373 new_de = ext2_find_entry(new_dir, &new_dentry->d_name,
374 &new_page, &page_addr);
375 if (IS_ERR(new_de)) {
376 err = PTR_ERR(new_de);
377 goto out_dir;
378 }
379 ext2_set_link(new_dir, new_de, new_page, page_addr, old_inode, 1);
380 ext2_put_page(new_page, page_addr);
381 new_inode->i_ctime = current_time(new_inode);
382 if (dir_de)
383 drop_nlink(new_inode);
384 inode_dec_link_count(new_inode);
385 } else {
386 err = ext2_add_link(new_dentry, old_inode);
387 if (err)
388 goto out_dir;
389 if (dir_de)
390 inode_inc_link_count(new_dir);
391 }
392
393 /*
394 * Like most other Unix systems, set the ctime for inodes on a
395 * rename.
396 */
397 old_inode->i_ctime = current_time(old_inode);
398 mark_inode_dirty(old_inode);
399
400 ext2_delete_entry(old_de, old_page, old_page_addr);
401
402 if (dir_de) {
403 if (old_dir != new_dir)
404 ext2_set_link(old_inode, dir_de, dir_page,
405 dir_page_addr, new_dir, 0);
406
407 ext2_put_page(dir_page, dir_page_addr);
408 inode_dec_link_count(old_dir);
409 }
410
411 ext2_put_page(old_page, old_page_addr);
412 return 0;
413
414 out_dir:
415 if (dir_de)
416 ext2_put_page(dir_page, dir_page_addr);
417 out_old:
418 ext2_put_page(old_page, old_page_addr);
419 out:
420 return err;
421 }
422
423 const struct inode_operations ext2_dir_inode_operations = {
424 .create = ext2_create,
425 .lookup = ext2_lookup,
426 .link = ext2_link,
427 .unlink = ext2_unlink,
428 .symlink = ext2_symlink,
429 .mkdir = ext2_mkdir,
430 .rmdir = ext2_rmdir,
431 .mknod = ext2_mknod,
432 .rename = ext2_rename,
433 .listxattr = ext2_listxattr,
434 .getattr = ext2_getattr,
435 .setattr = ext2_setattr,
436 .get_acl = ext2_get_acl,
437 .set_acl = ext2_set_acl,
438 .tmpfile = ext2_tmpfile,
439 .fileattr_get = ext2_fileattr_get,
440 .fileattr_set = ext2_fileattr_set,
441 };
442
443 const struct inode_operations ext2_special_inode_operations = {
444 .listxattr = ext2_listxattr,
445 .getattr = ext2_getattr,
446 .setattr = ext2_setattr,
447 .get_acl = ext2_get_acl,
448 .set_acl = ext2_set_acl,
449 };
450