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
40static 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
56static 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(error: -ENAMETOOLONG);
64
65 res = ext2_inode_by_name(dir, child: &dentry->d_name, ino: &ino);
66 if (res) {
67 if (res != -ENOENT)
68 return ERR_PTR(error: res);
69 inode = NULL;
70 } else {
71 inode = ext2_iget(dir->i_sb, ino);
72 if (inode == ERR_PTR(error: -ESTALE)) {
73 ext2_error(dir->i_sb, __func__,
74 "deleted inode referenced: %lu",
75 (unsigned long) ino);
76 return ERR_PTR(error: -EIO);
77 }
78 }
79 return d_splice_alias(inode, dentry);
80}
81
82struct dentry *ext2_get_parent(struct dentry *child)
83{
84 ino_t ino;
85 int res;
86
87 res = ext2_inode_by_name(dir: d_inode(dentry: child), child: &dotdot_name, ino: &ino);
88 if (res)
89 return ERR_PTR(error: 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 */
102static int ext2_create (struct mnt_idmap * idmap,
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(inode: dir);
110 if (err)
111 return err;
112
113 inode = ext2_new_inode(dir, mode, &dentry->d_name);
114 if (IS_ERR(ptr: inode))
115 return PTR_ERR(ptr: inode);
116
117 ext2_set_file_ops(inode);
118 mark_inode_dirty(inode);
119 return ext2_add_nondir(dentry, inode);
120}
121
122static int ext2_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
123 struct file *file, umode_t mode)
124{
125 struct inode *inode = ext2_new_inode(dir, mode, NULL);
126 if (IS_ERR(ptr: inode))
127 return PTR_ERR(ptr: inode);
128
129 ext2_set_file_ops(inode);
130 mark_inode_dirty(inode);
131 d_tmpfile(file, inode);
132 unlock_new_inode(inode);
133 return finish_open_simple(file, error: 0);
134}
135
136static int ext2_mknod (struct mnt_idmap * idmap, 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(inode: dir);
143 if (err)
144 return err;
145
146 inode = ext2_new_inode (dir, mode, &dentry->d_name);
147 err = PTR_ERR(ptr: inode);
148 if (!IS_ERR(ptr: 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
157static int ext2_symlink (struct mnt_idmap * idmap, 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(inode: 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(ptr: inode);
174 if (IS_ERR(ptr: 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 inode->i_mapping->a_ops = &ext2_aops;
182 err = page_symlink(inode, symname, len: 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);
195out:
196 return err;
197
198out_fail:
199 inode_dec_link_count(inode);
200 discard_new_inode(inode);
201 goto out;
202}
203
204static int ext2_link (struct dentry * old_dentry, struct inode * dir,
205 struct dentry *dentry)
206{
207 struct inode *inode = d_inode(dentry: old_dentry);
208 int err;
209
210 err = dquot_initialize(inode: dir);
211 if (err)
212 return err;
213
214 inode_set_ctime_current(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
228static int ext2_mkdir(struct mnt_idmap * idmap,
229 struct inode * dir, struct dentry * dentry, umode_t mode)
230{
231 struct inode * inode;
232 int err;
233
234 err = dquot_initialize(inode: dir);
235 if (err)
236 return err;
237
238 inode_inc_link_count(inode: dir);
239
240 inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
241 err = PTR_ERR(ptr: inode);
242 if (IS_ERR(ptr: inode))
243 goto out_dir;
244
245 inode->i_op = &ext2_dir_inode_operations;
246 inode->i_fop = &ext2_dir_operations;
247 inode->i_mapping->a_ops = &ext2_aops;
248
249 inode_inc_link_count(inode);
250
251 err = ext2_make_empty(inode, dir);
252 if (err)
253 goto out_fail;
254
255 err = ext2_add_link(dentry, inode);
256 if (err)
257 goto out_fail;
258
259 d_instantiate_new(dentry, inode);
260out:
261 return err;
262
263out_fail:
264 inode_dec_link_count(inode);
265 inode_dec_link_count(inode);
266 discard_new_inode(inode);
267out_dir:
268 inode_dec_link_count(inode: dir);
269 goto out;
270}
271
272static int ext2_unlink(struct inode *dir, struct dentry *dentry)
273{
274 struct inode *inode = d_inode(dentry);
275 struct ext2_dir_entry_2 *de;
276 struct folio *folio;
277 int err;
278
279 err = dquot_initialize(inode: dir);
280 if (err)
281 goto out;
282
283 de = ext2_find_entry(dir, &dentry->d_name, foliop: &folio);
284 if (IS_ERR(ptr: de)) {
285 err = PTR_ERR(ptr: de);
286 goto out;
287 }
288
289 err = ext2_delete_entry(dir: de, folio);
290 folio_release_kmap(folio, addr: de);
291 if (err)
292 goto out;
293
294 inode_set_ctime_to_ts(inode, ts: inode_get_ctime(inode: dir));
295 inode_dec_link_count(inode);
296 err = 0;
297out:
298 return err;
299}
300
301static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
302{
303 struct inode * inode = d_inode(dentry);
304 int err = -ENOTEMPTY;
305
306 if (ext2_empty_dir(inode)) {
307 err = ext2_unlink(dir, dentry);
308 if (!err) {
309 inode->i_size = 0;
310 inode_dec_link_count(inode);
311 inode_dec_link_count(inode: dir);
312 }
313 }
314 return err;
315}
316
317static int ext2_rename (struct mnt_idmap * idmap,
318 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(dentry: old_dentry);
323 struct inode * new_inode = d_inode(dentry: new_dentry);
324 struct folio *dir_folio = NULL;
325 struct ext2_dir_entry_2 * dir_de = NULL;
326 struct folio * old_folio;
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(inode: old_dir);
334 if (err)
335 return err;
336
337 err = dquot_initialize(inode: new_dir);
338 if (err)
339 return err;
340
341 old_de = ext2_find_entry(old_dir, &old_dentry->d_name, foliop: &old_folio);
342 if (IS_ERR(ptr: old_de))
343 return PTR_ERR(ptr: old_de);
344
345 if (S_ISDIR(old_inode->i_mode)) {
346 err = -EIO;
347 dir_de = ext2_dotdot(dir: old_inode, foliop: &dir_folio);
348 if (!dir_de)
349 goto out_old;
350 }
351
352 if (new_inode) {
353 struct folio *new_folio;
354 struct ext2_dir_entry_2 *new_de;
355
356 err = -ENOTEMPTY;
357 if (dir_de && !ext2_empty_dir (new_inode))
358 goto out_dir;
359
360 new_de = ext2_find_entry(new_dir, &new_dentry->d_name,
361 foliop: &new_folio);
362 if (IS_ERR(ptr: new_de)) {
363 err = PTR_ERR(ptr: new_de);
364 goto out_dir;
365 }
366 err = ext2_set_link(dir: new_dir, de: new_de, folio: new_folio, inode: old_inode, update_times: true);
367 folio_release_kmap(folio: new_folio, addr: new_de);
368 if (err)
369 goto out_dir;
370 inode_set_ctime_current(inode: new_inode);
371 if (dir_de)
372 drop_nlink(inode: new_inode);
373 inode_dec_link_count(inode: new_inode);
374 } else {
375 err = ext2_add_link(new_dentry, old_inode);
376 if (err)
377 goto out_dir;
378 if (dir_de)
379 inode_inc_link_count(inode: new_dir);
380 }
381
382 /*
383 * Like most other Unix systems, set the ctime for inodes on a
384 * rename.
385 */
386 inode_set_ctime_current(inode: old_inode);
387 mark_inode_dirty(inode: old_inode);
388
389 err = ext2_delete_entry(dir: old_de, folio: old_folio);
390 if (!err && dir_de) {
391 if (old_dir != new_dir)
392 err = ext2_set_link(dir: old_inode, de: dir_de, folio: dir_folio,
393 inode: new_dir, update_times: false);
394
395 inode_dec_link_count(inode: old_dir);
396 }
397out_dir:
398 if (dir_de)
399 folio_release_kmap(folio: dir_folio, addr: dir_de);
400out_old:
401 folio_release_kmap(folio: old_folio, addr: old_de);
402 return err;
403}
404
405const struct inode_operations ext2_dir_inode_operations = {
406 .create = ext2_create,
407 .lookup = ext2_lookup,
408 .link = ext2_link,
409 .unlink = ext2_unlink,
410 .symlink = ext2_symlink,
411 .mkdir = ext2_mkdir,
412 .rmdir = ext2_rmdir,
413 .mknod = ext2_mknod,
414 .rename = ext2_rename,
415 .listxattr = ext2_listxattr,
416 .getattr = ext2_getattr,
417 .setattr = ext2_setattr,
418 .get_inode_acl = ext2_get_acl,
419 .set_acl = ext2_set_acl,
420 .tmpfile = ext2_tmpfile,
421 .fileattr_get = ext2_fileattr_get,
422 .fileattr_set = ext2_fileattr_set,
423};
424
425const struct inode_operations ext2_special_inode_operations = {
426 .listxattr = ext2_listxattr,
427 .getattr = ext2_getattr,
428 .setattr = ext2_setattr,
429 .get_inode_acl = ext2_get_acl,
430 .set_acl = ext2_set_acl,
431};
432

source code of linux/fs/ext2/namei.c