namei.c

  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 struct dentry *ext2_mkdir(struct mnt_idmap * idmap,
229				 struct inode * dir, struct dentry * dentry,
230				 umode_t mode)
231{
232	struct inode * inode;
233	int err;
234
235	err = dquot_initialize(dir);
236	if (err)
237		return ERR_PTR(err);
238
239	inode_inc_link_count(dir);
240
241	inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
242	err = PTR_ERR(inode);
243	if (IS_ERR(inode))
244		goto out_dir;
245
246	inode->i_op = &ext2_dir_inode_operations;
247	inode->i_fop = &ext2_dir_operations;
248	inode->i_mapping->a_ops = &ext2_aops;
249
250	inode_inc_link_count(inode);
251
252	err = ext2_make_empty(inode, dir);
253	if (err)
254		goto out_fail;
255
256	err = ext2_add_link(dentry, inode);
257	if (err)
258		goto out_fail;
259
260	d_instantiate_new(dentry, inode);
261out:
262	return ERR_PTR(err);
263
264out_fail:
265	inode_dec_link_count(inode);
266	inode_dec_link_count(inode);
267	discard_new_inode(inode);
268out_dir:
269	inode_dec_link_count(dir);
270	goto out;
271}
272
273static int ext2_unlink(struct inode *dir, struct dentry *dentry)
274{
275	struct inode *inode = d_inode(dentry);
276	struct ext2_dir_entry_2 *de;
277	struct folio *folio;
278	int err;
279
280	err = dquot_initialize(dir);
281	if (err)
282		goto out;
283
284	de = ext2_find_entry(dir, &dentry->d_name, &folio);
285	if (IS_ERR(de)) {
286		err = PTR_ERR(de);
287		goto out;
288	}
289
290	err = ext2_delete_entry(de, folio);
291	folio_release_kmap(folio, de);
292	if (err)
293		goto out;
294
295	inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
296	inode_dec_link_count(inode);
297	err = 0;
298out:
299	return err;
300}
301
302static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
303{
304	struct inode * inode = d_inode(dentry);
305	int err = -ENOTEMPTY;
306
307	if (ext2_empty_dir(inode)) {
308		err = ext2_unlink(dir, dentry);
309		if (!err) {
310			inode->i_size = 0;
311			inode_dec_link_count(inode);
312			inode_dec_link_count(dir);
313		}
314	}
315	return err;
316}
317
318static int ext2_rename (struct mnt_idmap * idmap,
319			struct inode * old_dir, struct dentry * old_dentry,
320			struct inode * new_dir, struct dentry * new_dentry,
321			unsigned int flags)
322{
323	struct inode * old_inode = d_inode(old_dentry);
324	struct inode * new_inode = d_inode(new_dentry);
325	struct folio *dir_folio = NULL;
326	struct ext2_dir_entry_2 * dir_de = NULL;
327	struct folio * old_folio;
328	struct ext2_dir_entry_2 * old_de;
329	bool old_is_dir = S_ISDIR(old_inode->i_mode);
330	int err;
331
332	if (flags & ~RENAME_NOREPLACE)
333		return -EINVAL;
334
335	err = dquot_initialize(old_dir);
336	if (err)
337		return err;
338
339	err = dquot_initialize(new_dir);
340	if (err)
341		return err;
342
343	old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_folio);
344	if (IS_ERR(old_de))
345		return PTR_ERR(old_de);
346
347	if (old_is_dir && old_dir != new_dir) {
348		err = -EIO;
349		dir_de = ext2_dotdot(old_inode, &dir_folio);
350		if (!dir_de)
351			goto out_old;
352	}
353
354	if (new_inode) {
355		struct folio *new_folio;
356		struct ext2_dir_entry_2 *new_de;
357
358		err = -ENOTEMPTY;
359		if (old_is_dir && !ext2_empty_dir(new_inode))
360			goto out_dir;
361
362		new_de = ext2_find_entry(new_dir, &new_dentry->d_name,
363					 &new_folio);
364		if (IS_ERR(new_de)) {
365			err = PTR_ERR(new_de);
366			goto out_dir;
367		}
368		err = ext2_set_link(new_dir, new_de, new_folio, old_inode, true);
369		folio_release_kmap(new_folio, new_de);
370		if (err)
371			goto out_dir;
372		inode_set_ctime_current(new_inode);
373		if (old_is_dir)
374			drop_nlink(new_inode);
375		inode_dec_link_count(new_inode);
376	} else {
377		err = ext2_add_link(new_dentry, old_inode);
378		if (err)
379			goto out_dir;
380		if (old_is_dir)
381			inode_inc_link_count(new_dir);
382	}
383
384	/*
385	 * Like most other Unix systems, set the ctime for inodes on a
386 	 * rename.
387	 */
388	inode_set_ctime_current(old_inode);
389	mark_inode_dirty(old_inode);
390
391	err = ext2_delete_entry(old_de, old_folio);
392	if (!err && old_is_dir) {
393		if (old_dir != new_dir)
394			err = ext2_set_link(old_inode, dir_de, dir_folio,
395					    new_dir, false);
396
397		inode_dec_link_count(old_dir);
398	}
399out_dir:
400	if (dir_de)
401		folio_release_kmap(dir_folio, dir_de);
402out_old:
403	folio_release_kmap(old_folio, old_de);
404	return err;
405}
406
407const struct inode_operations ext2_dir_inode_operations = {
408	.create		= ext2_create,
409	.lookup		= ext2_lookup,
410	.link		= ext2_link,
411	.unlink		= ext2_unlink,
412	.symlink	= ext2_symlink,
413	.mkdir		= ext2_mkdir,
414	.rmdir		= ext2_rmdir,
415	.mknod		= ext2_mknod,
416	.rename		= ext2_rename,
417	.listxattr	= ext2_listxattr,
418	.getattr	= ext2_getattr,
419	.setattr	= ext2_setattr,
420	.get_inode_acl	= ext2_get_acl,
421	.set_acl	= ext2_set_acl,
422	.tmpfile	= ext2_tmpfile,
423	.fileattr_get	= ext2_fileattr_get,
424	.fileattr_set	= ext2_fileattr_set,
425};
426
427const struct inode_operations ext2_special_inode_operations = {
428	.listxattr	= ext2_listxattr,
429	.getattr	= ext2_getattr,
430	.setattr	= ext2_setattr,
431	.get_inode_acl	= ext2_get_acl,
432	.set_acl	= ext2_set_acl,
433};