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(-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
82struct 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 */
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(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
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(inode))
127		return PTR_ERR(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, 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(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
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(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		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);
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(old_dentry);
208	int err;
209
210	err = dquot_initialize(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(dir);
235	if (err)
236		return err;
237
238	inode_inc_link_count(dir);
239
240	inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
241	err = PTR_ERR(inode);
242	if (IS_ERR(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(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(dir);
280	if (err)
281		goto out;
282
283	de = ext2_find_entry(dir, &dentry->d_name, &folio);
284	if (IS_ERR(de)) {
285		err = PTR_ERR(de);
286		goto out;
287	}
288
289	err = ext2_delete_entry(de, folio);
290	folio_release_kmap(folio, de);
291	if (err)
292		goto out;
293
294	inode_set_ctime_to_ts(inode, inode_get_ctime(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(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(old_dentry);
323	struct inode * new_inode = d_inode(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	bool old_is_dir = S_ISDIR(old_inode->i_mode);
329	int err;
330
331	if (flags & ~RENAME_NOREPLACE)
332		return -EINVAL;
333
334	err = dquot_initialize(old_dir);
335	if (err)
336		return err;
337
338	err = dquot_initialize(new_dir);
339	if (err)
340		return err;
341
342	old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_folio);
343	if (IS_ERR(old_de))
344		return PTR_ERR(old_de);
345
346	if (old_is_dir && old_dir != new_dir) {
347		err = -EIO;
348		dir_de = ext2_dotdot(old_inode, &dir_folio);
349		if (!dir_de)
350			goto out_old;
351	}
352
353	if (new_inode) {
354		struct folio *new_folio;
355		struct ext2_dir_entry_2 *new_de;
356
357		err = -ENOTEMPTY;
358		if (old_is_dir && !ext2_empty_dir(new_inode))
359			goto out_dir;
360
361		new_de = ext2_find_entry(new_dir, &new_dentry->d_name,
362					 &new_folio);
363		if (IS_ERR(new_de)) {
364			err = PTR_ERR(new_de);
365			goto out_dir;
366		}
367		err = ext2_set_link(new_dir, new_de, new_folio, old_inode, true);
368		folio_release_kmap(new_folio, new_de);
369		if (err)
370			goto out_dir;
371		inode_set_ctime_current(new_inode);
372		if (old_is_dir)
373			drop_nlink(new_inode);
374		inode_dec_link_count(new_inode);
375	} else {
376		err = ext2_add_link(new_dentry, old_inode);
377		if (err)
378			goto out_dir;
379		if (old_is_dir)
380			inode_inc_link_count(new_dir);
381	}
382
383	/*
384	 * Like most other Unix systems, set the ctime for inodes on a
385 	 * rename.
386	 */
387	inode_set_ctime_current(old_inode);
388	mark_inode_dirty(old_inode);
389
390	err = ext2_delete_entry(old_de, old_folio);
391	if (!err && old_is_dir) {
392		if (old_dir != new_dir)
393			err = ext2_set_link(old_inode, dir_de, dir_folio,
394					    new_dir, false);
395
396		inode_dec_link_count(old_dir);
397	}
398out_dir:
399	if (dir_de)
400		folio_release_kmap(dir_folio, dir_de);
401out_old:
402	folio_release_kmap(old_folio, old_de);
403	return err;
404}
405
406const struct inode_operations ext2_dir_inode_operations = {
407	.create		= ext2_create,
408	.lookup		= ext2_lookup,
409	.link		= ext2_link,
410	.unlink		= ext2_unlink,
411	.symlink	= ext2_symlink,
412	.mkdir		= ext2_mkdir,
413	.rmdir		= ext2_rmdir,
414	.mknod		= ext2_mknod,
415	.rename		= ext2_rename,
416	.listxattr	= ext2_listxattr,
417	.getattr	= ext2_getattr,
418	.setattr	= ext2_setattr,
419	.get_inode_acl	= ext2_get_acl,
420	.set_acl	= ext2_set_acl,
421	.tmpfile	= ext2_tmpfile,
422	.fileattr_get	= ext2_fileattr_get,
423	.fileattr_set	= ext2_fileattr_set,
424};
425
426const struct inode_operations ext2_special_inode_operations = {
427	.listxattr	= ext2_listxattr,
428	.getattr	= ext2_getattr,
429	.setattr	= ext2_setattr,
430	.get_inode_acl	= ext2_get_acl,
431	.set_acl	= ext2_set_acl,
432};
433