xref: /openbmc/linux/fs/ext2/namei.c (revision 82df5b73)
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 
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 
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 
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  */
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 
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 
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 		inode->i_op = &ext2_special_inode_operations;
140 		mark_inode_dirty(inode);
141 		err = ext2_add_nondir(dentry, inode);
142 	}
143 	return err;
144 }
145 
146 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
147 	const char * symname)
148 {
149 	struct super_block * sb = dir->i_sb;
150 	int err = -ENAMETOOLONG;
151 	unsigned l = strlen(symname)+1;
152 	struct inode * inode;
153 
154 	if (l > sb->s_blocksize)
155 		goto out;
156 
157 	err = dquot_initialize(dir);
158 	if (err)
159 		goto out;
160 
161 	inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
162 	err = PTR_ERR(inode);
163 	if (IS_ERR(inode))
164 		goto out;
165 
166 	if (l > sizeof (EXT2_I(inode)->i_data)) {
167 		/* slow symlink */
168 		inode->i_op = &ext2_symlink_inode_operations;
169 		inode_nohighmem(inode);
170 		if (test_opt(inode->i_sb, NOBH))
171 			inode->i_mapping->a_ops = &ext2_nobh_aops;
172 		else
173 			inode->i_mapping->a_ops = &ext2_aops;
174 		err = page_symlink(inode, symname, l);
175 		if (err)
176 			goto out_fail;
177 	} else {
178 		/* fast symlink */
179 		inode->i_op = &ext2_fast_symlink_inode_operations;
180 		inode->i_link = (char*)EXT2_I(inode)->i_data;
181 		memcpy(inode->i_link, symname, l);
182 		inode->i_size = l-1;
183 	}
184 	mark_inode_dirty(inode);
185 
186 	err = ext2_add_nondir(dentry, inode);
187 out:
188 	return err;
189 
190 out_fail:
191 	inode_dec_link_count(inode);
192 	discard_new_inode(inode);
193 	goto out;
194 }
195 
196 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
197 	struct dentry *dentry)
198 {
199 	struct inode *inode = d_inode(old_dentry);
200 	int err;
201 
202 	err = dquot_initialize(dir);
203 	if (err)
204 		return err;
205 
206 	inode->i_ctime = current_time(inode);
207 	inode_inc_link_count(inode);
208 	ihold(inode);
209 
210 	err = ext2_add_link(dentry, inode);
211 	if (!err) {
212 		d_instantiate(dentry, inode);
213 		return 0;
214 	}
215 	inode_dec_link_count(inode);
216 	iput(inode);
217 	return err;
218 }
219 
220 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
221 {
222 	struct inode * inode;
223 	int err;
224 
225 	err = dquot_initialize(dir);
226 	if (err)
227 		return err;
228 
229 	inode_inc_link_count(dir);
230 
231 	inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
232 	err = PTR_ERR(inode);
233 	if (IS_ERR(inode))
234 		goto out_dir;
235 
236 	inode->i_op = &ext2_dir_inode_operations;
237 	inode->i_fop = &ext2_dir_operations;
238 	if (test_opt(inode->i_sb, NOBH))
239 		inode->i_mapping->a_ops = &ext2_nobh_aops;
240 	else
241 		inode->i_mapping->a_ops = &ext2_aops;
242 
243 	inode_inc_link_count(inode);
244 
245 	err = ext2_make_empty(inode, dir);
246 	if (err)
247 		goto out_fail;
248 
249 	err = ext2_add_link(dentry, inode);
250 	if (err)
251 		goto out_fail;
252 
253 	d_instantiate_new(dentry, inode);
254 out:
255 	return err;
256 
257 out_fail:
258 	inode_dec_link_count(inode);
259 	inode_dec_link_count(inode);
260 	discard_new_inode(inode);
261 out_dir:
262 	inode_dec_link_count(dir);
263 	goto out;
264 }
265 
266 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
267 {
268 	struct inode * inode = d_inode(dentry);
269 	struct ext2_dir_entry_2 * de;
270 	struct page * page;
271 	int err;
272 
273 	err = dquot_initialize(dir);
274 	if (err)
275 		goto out;
276 
277 	de = ext2_find_entry (dir, &dentry->d_name, &page);
278 	if (!de) {
279 		err = -ENOENT;
280 		goto out;
281 	}
282 
283 	err = ext2_delete_entry (de, page);
284 	if (err)
285 		goto out;
286 
287 	inode->i_ctime = dir->i_ctime;
288 	inode_dec_link_count(inode);
289 	err = 0;
290 out:
291 	return err;
292 }
293 
294 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
295 {
296 	struct inode * inode = d_inode(dentry);
297 	int err = -ENOTEMPTY;
298 
299 	if (ext2_empty_dir(inode)) {
300 		err = ext2_unlink(dir, dentry);
301 		if (!err) {
302 			inode->i_size = 0;
303 			inode_dec_link_count(inode);
304 			inode_dec_link_count(dir);
305 		}
306 	}
307 	return err;
308 }
309 
310 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
311 			struct inode * new_dir,	struct dentry * new_dentry,
312 			unsigned int flags)
313 {
314 	struct inode * old_inode = d_inode(old_dentry);
315 	struct inode * new_inode = d_inode(new_dentry);
316 	struct page * dir_page = NULL;
317 	struct ext2_dir_entry_2 * dir_de = NULL;
318 	struct page * old_page;
319 	struct ext2_dir_entry_2 * old_de;
320 	int err;
321 
322 	if (flags & ~RENAME_NOREPLACE)
323 		return -EINVAL;
324 
325 	err = dquot_initialize(old_dir);
326 	if (err)
327 		goto out;
328 
329 	err = dquot_initialize(new_dir);
330 	if (err)
331 		goto out;
332 
333 	old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
334 	if (!old_de) {
335 		err = -ENOENT;
336 		goto out;
337 	}
338 
339 	if (S_ISDIR(old_inode->i_mode)) {
340 		err = -EIO;
341 		dir_de = ext2_dotdot(old_inode, &dir_page);
342 		if (!dir_de)
343 			goto out_old;
344 	}
345 
346 	if (new_inode) {
347 		struct page *new_page;
348 		struct ext2_dir_entry_2 *new_de;
349 
350 		err = -ENOTEMPTY;
351 		if (dir_de && !ext2_empty_dir (new_inode))
352 			goto out_dir;
353 
354 		err = -ENOENT;
355 		new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
356 		if (!new_de)
357 			goto out_dir;
358 		ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
359 		new_inode->i_ctime = current_time(new_inode);
360 		if (dir_de)
361 			drop_nlink(new_inode);
362 		inode_dec_link_count(new_inode);
363 	} else {
364 		err = ext2_add_link(new_dentry, old_inode);
365 		if (err)
366 			goto out_dir;
367 		if (dir_de)
368 			inode_inc_link_count(new_dir);
369 	}
370 
371 	/*
372 	 * Like most other Unix systems, set the ctime for inodes on a
373  	 * rename.
374 	 */
375 	old_inode->i_ctime = current_time(old_inode);
376 	mark_inode_dirty(old_inode);
377 
378 	ext2_delete_entry (old_de, old_page);
379 
380 	if (dir_de) {
381 		if (old_dir != new_dir)
382 			ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
383 		else {
384 			kunmap(dir_page);
385 			put_page(dir_page);
386 		}
387 		inode_dec_link_count(old_dir);
388 	}
389 	return 0;
390 
391 
392 out_dir:
393 	if (dir_de) {
394 		kunmap(dir_page);
395 		put_page(dir_page);
396 	}
397 out_old:
398 	kunmap(old_page);
399 	put_page(old_page);
400 out:
401 	return err;
402 }
403 
404 const struct inode_operations ext2_dir_inode_operations = {
405 	.create		= ext2_create,
406 	.lookup		= ext2_lookup,
407 	.link		= ext2_link,
408 	.unlink		= ext2_unlink,
409 	.symlink	= ext2_symlink,
410 	.mkdir		= ext2_mkdir,
411 	.rmdir		= ext2_rmdir,
412 	.mknod		= ext2_mknod,
413 	.rename		= ext2_rename,
414 	.listxattr	= ext2_listxattr,
415 	.getattr	= ext2_getattr,
416 	.setattr	= ext2_setattr,
417 	.get_acl	= ext2_get_acl,
418 	.set_acl	= ext2_set_acl,
419 	.tmpfile	= ext2_tmpfile,
420 };
421 
422 const struct inode_operations ext2_special_inode_operations = {
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 };
429