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 
61 	if (dentry->d_name.len > EXT2_NAME_LEN)
62 		return ERR_PTR(-ENAMETOOLONG);
63 
64 	ino = ext2_inode_by_name(dir, &dentry->d_name);
65 	inode = NULL;
66 	if (ino) {
67 		inode = ext2_iget(dir->i_sb, ino);
68 		if (inode == ERR_PTR(-ESTALE)) {
69 			ext2_error(dir->i_sb, __func__,
70 					"deleted inode referenced: %lu",
71 					(unsigned long) ino);
72 			return ERR_PTR(-EIO);
73 		}
74 	}
75 	return d_splice_alias(inode, dentry);
76 }
77 
ext2_get_parent(struct dentry * child)78 struct dentry *ext2_get_parent(struct dentry *child)
79 {
80 	struct qstr dotdot = QSTR_INIT("..", 2);
81 	unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
82 	if (!ino)
83 		return ERR_PTR(-ENOENT);
84 	return d_obtain_alias(ext2_iget(child->d_sb, ino));
85 }
86 
87 /*
88  * By the time this is called, we already have created
89  * the directory cache entry for the new file, but it
90  * is so far negative - it has no inode.
91  *
92  * If the create succeeds, we fill in the inode information
93  * with d_instantiate().
94  */
ext2_create(struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)95 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
96 {
97 	struct inode *inode;
98 	int err;
99 
100 	err = dquot_initialize(dir);
101 	if (err)
102 		return err;
103 
104 	inode = ext2_new_inode(dir, mode, &dentry->d_name);
105 	if (IS_ERR(inode))
106 		return PTR_ERR(inode);
107 
108 	ext2_set_file_ops(inode);
109 	mark_inode_dirty(inode);
110 	return ext2_add_nondir(dentry, inode);
111 }
112 
ext2_tmpfile(struct inode * dir,struct dentry * dentry,umode_t mode)113 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
114 {
115 	struct inode *inode = ext2_new_inode(dir, mode, NULL);
116 	if (IS_ERR(inode))
117 		return PTR_ERR(inode);
118 
119 	ext2_set_file_ops(inode);
120 	mark_inode_dirty(inode);
121 	d_tmpfile(dentry, inode);
122 	unlock_new_inode(inode);
123 	return 0;
124 }
125 
ext2_mknod(struct inode * dir,struct dentry * dentry,umode_t mode,dev_t rdev)126 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
127 {
128 	struct inode * inode;
129 	int err;
130 
131 	err = dquot_initialize(dir);
132 	if (err)
133 		return err;
134 
135 	inode = ext2_new_inode (dir, mode, &dentry->d_name);
136 	err = PTR_ERR(inode);
137 	if (!IS_ERR(inode)) {
138 		init_special_inode(inode, inode->i_mode, rdev);
139 #ifdef CONFIG_EXT2_FS_XATTR
140 		inode->i_op = &ext2_special_inode_operations;
141 #endif
142 		mark_inode_dirty(inode);
143 		err = ext2_add_nondir(dentry, inode);
144 	}
145 	return err;
146 }
147 
ext2_symlink(struct inode * dir,struct dentry * dentry,const char * symname)148 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
149 	const char * symname)
150 {
151 	struct super_block * sb = dir->i_sb;
152 	int err = -ENAMETOOLONG;
153 	unsigned l = strlen(symname)+1;
154 	struct inode * inode;
155 
156 	if (l > sb->s_blocksize)
157 		goto out;
158 
159 	err = dquot_initialize(dir);
160 	if (err)
161 		goto out;
162 
163 	inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
164 	err = PTR_ERR(inode);
165 	if (IS_ERR(inode))
166 		goto out;
167 
168 	if (l > sizeof (EXT2_I(inode)->i_data)) {
169 		/* slow symlink */
170 		inode->i_op = &ext2_symlink_inode_operations;
171 		inode_nohighmem(inode);
172 		if (test_opt(inode->i_sb, NOBH))
173 			inode->i_mapping->a_ops = &ext2_nobh_aops;
174 		else
175 			inode->i_mapping->a_ops = &ext2_aops;
176 		err = page_symlink(inode, symname, l);
177 		if (err)
178 			goto out_fail;
179 	} else {
180 		/* fast symlink */
181 		inode->i_op = &ext2_fast_symlink_inode_operations;
182 		inode->i_link = (char*)EXT2_I(inode)->i_data;
183 		memcpy(inode->i_link, symname, l);
184 		inode->i_size = l-1;
185 	}
186 	mark_inode_dirty(inode);
187 
188 	err = ext2_add_nondir(dentry, inode);
189 out:
190 	return err;
191 
192 out_fail:
193 	inode_dec_link_count(inode);
194 	discard_new_inode(inode);
195 	goto out;
196 }
197 
ext2_link(struct dentry * old_dentry,struct inode * dir,struct dentry * dentry)198 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
199 	struct dentry *dentry)
200 {
201 	struct inode *inode = d_inode(old_dentry);
202 	int err;
203 
204 	err = dquot_initialize(dir);
205 	if (err)
206 		return err;
207 
208 	inode->i_ctime = current_time(inode);
209 	inode_inc_link_count(inode);
210 	ihold(inode);
211 
212 	err = ext2_add_link(dentry, inode);
213 	if (!err) {
214 		d_instantiate(dentry, inode);
215 		return 0;
216 	}
217 	inode_dec_link_count(inode);
218 	iput(inode);
219 	return err;
220 }
221 
ext2_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode)222 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
223 {
224 	struct inode * inode;
225 	int err;
226 
227 	err = dquot_initialize(dir);
228 	if (err)
229 		return err;
230 
231 	inode_inc_link_count(dir);
232 
233 	inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
234 	err = PTR_ERR(inode);
235 	if (IS_ERR(inode))
236 		goto out_dir;
237 
238 	inode->i_op = &ext2_dir_inode_operations;
239 	inode->i_fop = &ext2_dir_operations;
240 	if (test_opt(inode->i_sb, NOBH))
241 		inode->i_mapping->a_ops = &ext2_nobh_aops;
242 	else
243 		inode->i_mapping->a_ops = &ext2_aops;
244 
245 	inode_inc_link_count(inode);
246 
247 	err = ext2_make_empty(inode, dir);
248 	if (err)
249 		goto out_fail;
250 
251 	err = ext2_add_link(dentry, inode);
252 	if (err)
253 		goto out_fail;
254 
255 	d_instantiate_new(dentry, inode);
256 out:
257 	return err;
258 
259 out_fail:
260 	inode_dec_link_count(inode);
261 	inode_dec_link_count(inode);
262 	discard_new_inode(inode);
263 out_dir:
264 	inode_dec_link_count(dir);
265 	goto out;
266 }
267 
ext2_unlink(struct inode * dir,struct dentry * dentry)268 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
269 {
270 	struct inode * inode = d_inode(dentry);
271 	struct ext2_dir_entry_2 * de;
272 	struct page * page;
273 	int err;
274 
275 	err = dquot_initialize(dir);
276 	if (err)
277 		goto out;
278 
279 	de = ext2_find_entry (dir, &dentry->d_name, &page);
280 	if (!de) {
281 		err = -ENOENT;
282 		goto out;
283 	}
284 
285 	err = ext2_delete_entry (de, page);
286 	if (err)
287 		goto out;
288 
289 	inode->i_ctime = dir->i_ctime;
290 	inode_dec_link_count(inode);
291 	err = 0;
292 out:
293 	return err;
294 }
295 
ext2_rmdir(struct inode * dir,struct dentry * dentry)296 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
297 {
298 	struct inode * inode = d_inode(dentry);
299 	int err = -ENOTEMPTY;
300 
301 	if (ext2_empty_dir(inode)) {
302 		err = ext2_unlink(dir, dentry);
303 		if (!err) {
304 			inode->i_size = 0;
305 			inode_dec_link_count(inode);
306 			inode_dec_link_count(dir);
307 		}
308 	}
309 	return err;
310 }
311 
ext2_rename(struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)312 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
313 			struct inode * new_dir,	struct dentry * new_dentry,
314 			unsigned int flags)
315 {
316 	struct inode * old_inode = d_inode(old_dentry);
317 	struct inode * new_inode = d_inode(new_dentry);
318 	struct page * dir_page = NULL;
319 	struct ext2_dir_entry_2 * dir_de = NULL;
320 	struct page * old_page;
321 	struct ext2_dir_entry_2 * old_de;
322 	int err;
323 
324 	if (flags & ~RENAME_NOREPLACE)
325 		return -EINVAL;
326 
327 	err = dquot_initialize(old_dir);
328 	if (err)
329 		goto out;
330 
331 	err = dquot_initialize(new_dir);
332 	if (err)
333 		goto out;
334 
335 	old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
336 	if (!old_de) {
337 		err = -ENOENT;
338 		goto out;
339 	}
340 
341 	if (S_ISDIR(old_inode->i_mode)) {
342 		err = -EIO;
343 		dir_de = ext2_dotdot(old_inode, &dir_page);
344 		if (!dir_de)
345 			goto out_old;
346 	}
347 
348 	if (new_inode) {
349 		struct page *new_page;
350 		struct ext2_dir_entry_2 *new_de;
351 
352 		err = -ENOTEMPTY;
353 		if (dir_de && !ext2_empty_dir (new_inode))
354 			goto out_dir;
355 
356 		err = -ENOENT;
357 		new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
358 		if (!new_de)
359 			goto out_dir;
360 		ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
361 		new_inode->i_ctime = current_time(new_inode);
362 		if (dir_de)
363 			drop_nlink(new_inode);
364 		inode_dec_link_count(new_inode);
365 	} else {
366 		err = ext2_add_link(new_dentry, old_inode);
367 		if (err)
368 			goto out_dir;
369 		if (dir_de)
370 			inode_inc_link_count(new_dir);
371 	}
372 
373 	/*
374 	 * Like most other Unix systems, set the ctime for inodes on a
375  	 * rename.
376 	 */
377 	old_inode->i_ctime = current_time(old_inode);
378 	mark_inode_dirty(old_inode);
379 
380 	ext2_delete_entry (old_de, old_page);
381 
382 	if (dir_de) {
383 		if (old_dir != new_dir)
384 			ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
385 		else {
386 			kunmap(dir_page);
387 			put_page(dir_page);
388 		}
389 		inode_dec_link_count(old_dir);
390 	}
391 	return 0;
392 
393 
394 out_dir:
395 	if (dir_de) {
396 		kunmap(dir_page);
397 		put_page(dir_page);
398 	}
399 out_old:
400 	kunmap(old_page);
401 	put_page(old_page);
402 out:
403 	return err;
404 }
405 
406 const 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 #ifdef CONFIG_EXT2_FS_XATTR
417 	.listxattr	= ext2_listxattr,
418 #endif
419 	.setattr	= ext2_setattr,
420 	.get_acl	= ext2_get_acl,
421 	.set_acl	= ext2_set_acl,
422 	.tmpfile	= ext2_tmpfile,
423 };
424 
425 const struct inode_operations ext2_special_inode_operations = {
426 #ifdef CONFIG_EXT2_FS_XATTR
427 	.listxattr	= ext2_listxattr,
428 #endif
429 	.setattr	= ext2_setattr,
430 	.get_acl	= ext2_get_acl,
431 	.set_acl	= ext2_set_acl,
432 };
433