1/*
2 * linux/fs/ext2/namei.c
3 *
4 * Rewrite to pagecache. Almost all code had been changed, so blame me
5 * if the things go wrong. Please, send bug reports to
6 * viro@parcelfarce.linux.theplanet.co.uk
7 *
8 * Stuff here is basically a glue between the VFS and generic UNIXish
9 * filesystem that keeps everything in pagecache. All knowledge of the
10 * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
11 * and it's easier to debug that way. In principle we might want to
12 * generalize that a bit and turn it into a library. Or not.
13 *
14 * The only non-static object here is ext2_dir_inode_operations.
15 *
16 * TODO: get rid of kmap() use, add readahead.
17 *
18 * Copyright (C) 1992, 1993, 1994, 1995
19 * Remy Card (card@masi.ibp.fr)
20 * Laboratoire MASI - Institut Blaise Pascal
21 * Universite Pierre et Marie Curie (Paris VI)
22 *
23 *  from
24 *
25 *  linux/fs/minix/namei.c
26 *
27 *  Copyright (C) 1991, 1992  Linus Torvalds
28 *
29 *  Big-endian to little-endian byte-swapping/bitmaps by
30 *        David S. Miller (davem@caip.rutgers.edu), 1995
31 */
32
33#include <linux/pagemap.h>
34#include <linux/quotaops.h>
35#include "ext2.h"
36#include "xattr.h"
37#include "acl.h"
38#include "xip.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		unlock_new_inode(inode);
45		d_instantiate(dentry, inode);
46		return 0;
47	}
48	inode_dec_link_count(inode);
49	unlock_new_inode(inode);
50	iput(inode);
51	return err;
52}
53
54/*
55 * Methods themselves.
56 */
57
58static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
59{
60	struct inode * inode;
61	ino_t ino;
62
63	if (dentry->d_name.len > EXT2_NAME_LEN)
64		return ERR_PTR(-ENAMETOOLONG);
65
66	ino = ext2_inode_by_name(dir, &dentry->d_name);
67	inode = NULL;
68	if (ino) {
69		inode = ext2_iget(dir->i_sb, ino);
70		if (inode == ERR_PTR(-ESTALE)) {
71			ext2_error(dir->i_sb, __func__,
72					"deleted inode referenced: %lu",
73					(unsigned long) ino);
74			return ERR_PTR(-EIO);
75		}
76	}
77	return d_splice_alias(inode, dentry);
78}
79
80struct dentry *ext2_get_parent(struct dentry *child)
81{
82	struct qstr dotdot = QSTR_INIT("..", 2);
83	unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
84	if (!ino)
85		return ERR_PTR(-ENOENT);
86	return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
87}
88
89/*
90 * By the time this is called, we already have created
91 * the directory cache entry for the new file, but it
92 * is so far negative - it has no inode.
93 *
94 * If the create succeeds, we fill in the inode information
95 * with d_instantiate().
96 */
97static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
98{
99	struct inode *inode;
100
101	dquot_initialize(dir);
102
103	inode = ext2_new_inode(dir, mode, &dentry->d_name);
104	if (IS_ERR(inode))
105		return PTR_ERR(inode);
106
107	inode->i_op = &ext2_file_inode_operations;
108	if (ext2_use_xip(inode->i_sb)) {
109		inode->i_mapping->a_ops = &ext2_aops_xip;
110		inode->i_fop = &ext2_xip_file_operations;
111	} else if (test_opt(inode->i_sb, NOBH)) {
112		inode->i_mapping->a_ops = &ext2_nobh_aops;
113		inode->i_fop = &ext2_file_operations;
114	} else {
115		inode->i_mapping->a_ops = &ext2_aops;
116		inode->i_fop = &ext2_file_operations;
117	}
118	mark_inode_dirty(inode);
119	return ext2_add_nondir(dentry, inode);
120}
121
122static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
123{
124	struct inode *inode = ext2_new_inode(dir, mode, NULL);
125	if (IS_ERR(inode))
126		return PTR_ERR(inode);
127
128	inode->i_op = &ext2_file_inode_operations;
129	if (ext2_use_xip(inode->i_sb)) {
130		inode->i_mapping->a_ops = &ext2_aops_xip;
131		inode->i_fop = &ext2_xip_file_operations;
132	} else if (test_opt(inode->i_sb, NOBH)) {
133		inode->i_mapping->a_ops = &ext2_nobh_aops;
134		inode->i_fop = &ext2_file_operations;
135	} else {
136		inode->i_mapping->a_ops = &ext2_aops;
137		inode->i_fop = &ext2_file_operations;
138	}
139	mark_inode_dirty(inode);
140	d_tmpfile(dentry, inode);
141	unlock_new_inode(inode);
142	return 0;
143}
144
145static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
146{
147	struct inode * inode;
148	int err;
149
150	if (!new_valid_dev(rdev))
151		return -EINVAL;
152
153	dquot_initialize(dir);
154
155	inode = ext2_new_inode (dir, mode, &dentry->d_name);
156	err = PTR_ERR(inode);
157	if (!IS_ERR(inode)) {
158		init_special_inode(inode, inode->i_mode, rdev);
159#ifdef CONFIG_EXT2_FS_XATTR
160		inode->i_op = &ext2_special_inode_operations;
161#endif
162		mark_inode_dirty(inode);
163		err = ext2_add_nondir(dentry, inode);
164	}
165	return err;
166}
167
168static int ext2_symlink (struct inode * dir, struct dentry * dentry,
169	const char * symname)
170{
171	struct super_block * sb = dir->i_sb;
172	int err = -ENAMETOOLONG;
173	unsigned l = strlen(symname)+1;
174	struct inode * inode;
175
176	if (l > sb->s_blocksize)
177		goto out;
178
179	dquot_initialize(dir);
180
181	inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
182	err = PTR_ERR(inode);
183	if (IS_ERR(inode))
184		goto out;
185
186	if (l > sizeof (EXT2_I(inode)->i_data)) {
187		/* slow symlink */
188		inode->i_op = &ext2_symlink_inode_operations;
189		if (test_opt(inode->i_sb, NOBH))
190			inode->i_mapping->a_ops = &ext2_nobh_aops;
191		else
192			inode->i_mapping->a_ops = &ext2_aops;
193		err = page_symlink(inode, symname, l);
194		if (err)
195			goto out_fail;
196	} else {
197		/* fast symlink */
198		inode->i_op = &ext2_fast_symlink_inode_operations;
199		memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
200		inode->i_size = l-1;
201	}
202	mark_inode_dirty(inode);
203
204	err = ext2_add_nondir(dentry, inode);
205out:
206	return err;
207
208out_fail:
209	inode_dec_link_count(inode);
210	unlock_new_inode(inode);
211	iput (inode);
212	goto out;
213}
214
215static int ext2_link (struct dentry * old_dentry, struct inode * dir,
216	struct dentry *dentry)
217{
218	struct inode *inode = old_dentry->d_inode;
219	int err;
220
221	dquot_initialize(dir);
222
223	inode->i_ctime = CURRENT_TIME_SEC;
224	inode_inc_link_count(inode);
225	ihold(inode);
226
227	err = ext2_add_link(dentry, inode);
228	if (!err) {
229		d_instantiate(dentry, inode);
230		return 0;
231	}
232	inode_dec_link_count(inode);
233	iput(inode);
234	return err;
235}
236
237static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
238{
239	struct inode * inode;
240	int err;
241
242	dquot_initialize(dir);
243
244	inode_inc_link_count(dir);
245
246	inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
247	err = PTR_ERR(inode);
248	if (IS_ERR(inode))
249		goto out_dir;
250
251	inode->i_op = &ext2_dir_inode_operations;
252	inode->i_fop = &ext2_dir_operations;
253	if (test_opt(inode->i_sb, NOBH))
254		inode->i_mapping->a_ops = &ext2_nobh_aops;
255	else
256		inode->i_mapping->a_ops = &ext2_aops;
257
258	inode_inc_link_count(inode);
259
260	err = ext2_make_empty(inode, dir);
261	if (err)
262		goto out_fail;
263
264	err = ext2_add_link(dentry, inode);
265	if (err)
266		goto out_fail;
267
268	unlock_new_inode(inode);
269	d_instantiate(dentry, inode);
270out:
271	return err;
272
273out_fail:
274	inode_dec_link_count(inode);
275	inode_dec_link_count(inode);
276	unlock_new_inode(inode);
277	iput(inode);
278out_dir:
279	inode_dec_link_count(dir);
280	goto out;
281}
282
283static int ext2_unlink(struct inode * dir, struct dentry *dentry)
284{
285	struct inode * inode = dentry->d_inode;
286	struct ext2_dir_entry_2 * de;
287	struct page * page;
288	int err = -ENOENT;
289
290	dquot_initialize(dir);
291
292	de = ext2_find_entry (dir, &dentry->d_name, &page);
293	if (!de)
294		goto out;
295
296	err = ext2_delete_entry (de, page);
297	if (err)
298		goto out;
299
300	inode->i_ctime = dir->i_ctime;
301	inode_dec_link_count(inode);
302	err = 0;
303out:
304	return err;
305}
306
307static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
308{
309	struct inode * inode = dentry->d_inode;
310	int err = -ENOTEMPTY;
311
312	if (ext2_empty_dir(inode)) {
313		err = ext2_unlink(dir, dentry);
314		if (!err) {
315			inode->i_size = 0;
316			inode_dec_link_count(inode);
317			inode_dec_link_count(dir);
318		}
319	}
320	return err;
321}
322
323static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
324	struct inode * new_dir,	struct dentry * new_dentry )
325{
326	struct inode * old_inode = old_dentry->d_inode;
327	struct inode * new_inode = new_dentry->d_inode;
328	struct page * dir_page = NULL;
329	struct ext2_dir_entry_2 * dir_de = NULL;
330	struct page * old_page;
331	struct ext2_dir_entry_2 * old_de;
332	int err = -ENOENT;
333
334	dquot_initialize(old_dir);
335	dquot_initialize(new_dir);
336
337	old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
338	if (!old_de)
339		goto out;
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_SEC;
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_SEC;
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			page_cache_release(dir_page);
388		}
389		inode_dec_link_count(old_dir);
390	}
391	return 0;
392
393
394out_dir:
395	if (dir_de) {
396		kunmap(dir_page);
397		page_cache_release(dir_page);
398	}
399out_old:
400	kunmap(old_page);
401	page_cache_release(old_page);
402out:
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#ifdef CONFIG_EXT2_FS_XATTR
417	.setxattr	= generic_setxattr,
418	.getxattr	= generic_getxattr,
419	.listxattr	= ext2_listxattr,
420	.removexattr	= generic_removexattr,
421#endif
422	.setattr	= ext2_setattr,
423	.get_acl	= ext2_get_acl,
424	.set_acl	= ext2_set_acl,
425	.tmpfile	= ext2_tmpfile,
426};
427
428const struct inode_operations ext2_special_inode_operations = {
429#ifdef CONFIG_EXT2_FS_XATTR
430	.setxattr	= generic_setxattr,
431	.getxattr	= generic_getxattr,
432	.listxattr	= ext2_listxattr,
433	.removexattr	= generic_removexattr,
434#endif
435	.setattr	= ext2_setattr,
436	.get_acl	= ext2_get_acl,
437	.set_acl	= ext2_set_acl,
438};
439