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v6.13.7
  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *	fs/bfs/dir.c
  4 *	BFS directory operations.
  5 *	Copyright (C) 1999-2018  Tigran Aivazian <aivazian.tigran@gmail.com>
  6 *  Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
  7 */
  8
  9#include <linux/time.h>
 10#include <linux/string.h>
 11#include <linux/fs.h>
 12#include <linux/buffer_head.h>
 13#include <linux/sched.h>
 14#include "bfs.h"
 15
 16#undef DEBUG
 17
 18#ifdef DEBUG
 19#define dprintf(x...)	printf(x)
 20#else
 21#define dprintf(x...)
 22#endif
 23
 24static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino);
 
 25static struct buffer_head *bfs_find_entry(struct inode *dir,
 26				const struct qstr *child,
 27				struct bfs_dirent **res_dir);
 28
 29static int bfs_readdir(struct file *f, struct dir_context *ctx)
 30{
 31	struct inode *dir = file_inode(f);
 32	struct buffer_head *bh;
 33	struct bfs_dirent *de;
 34	unsigned int offset;
 35	int block;
 36
 37	if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
 38		printf("Bad f_pos=%08lx for %s:%08lx\n",
 39					(unsigned long)ctx->pos,
 40					dir->i_sb->s_id, dir->i_ino);
 41		return -EINVAL;
 42	}
 43
 44	while (ctx->pos < dir->i_size) {
 45		offset = ctx->pos & (BFS_BSIZE - 1);
 46		block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
 47		bh = sb_bread(dir->i_sb, block);
 48		if (!bh) {
 49			ctx->pos += BFS_BSIZE - offset;
 50			continue;
 51		}
 52		do {
 53			de = (struct bfs_dirent *)(bh->b_data + offset);
 54			if (de->ino) {
 55				int size = strnlen(de->name, BFS_NAMELEN);
 56				if (!dir_emit(ctx, de->name, size,
 57						le16_to_cpu(de->ino),
 58						DT_UNKNOWN)) {
 59					brelse(bh);
 60					return 0;
 61				}
 62			}
 63			offset += BFS_DIRENT_SIZE;
 64			ctx->pos += BFS_DIRENT_SIZE;
 65		} while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
 66		brelse(bh);
 67	}
 68	return 0;
 69}
 70
 71const struct file_operations bfs_dir_operations = {
 72	.read		= generic_read_dir,
 73	.iterate_shared	= bfs_readdir,
 74	.fsync		= generic_file_fsync,
 75	.llseek		= generic_file_llseek,
 76};
 77
 78static int bfs_create(struct mnt_idmap *idmap, struct inode *dir,
 79		      struct dentry *dentry, umode_t mode, bool excl)
 80{
 81	int err;
 82	struct inode *inode;
 83	struct super_block *s = dir->i_sb;
 84	struct bfs_sb_info *info = BFS_SB(s);
 85	unsigned long ino;
 86
 87	inode = new_inode(s);
 88	if (!inode)
 89		return -ENOMEM;
 90	mutex_lock(&info->bfs_lock);
 91	ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
 92	if (ino > info->si_lasti) {
 93		mutex_unlock(&info->bfs_lock);
 94		iput(inode);
 95		return -ENOSPC;
 96	}
 97	set_bit(ino, info->si_imap);
 98	info->si_freei--;
 99	inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
100	simple_inode_init_ts(inode);
101	inode->i_blocks = 0;
102	inode->i_op = &bfs_file_inops;
103	inode->i_fop = &bfs_file_operations;
104	inode->i_mapping->a_ops = &bfs_aops;
105	inode->i_ino = ino;
106	BFS_I(inode)->i_dsk_ino = ino;
107	BFS_I(inode)->i_sblock = 0;
108	BFS_I(inode)->i_eblock = 0;
109	insert_inode_hash(inode);
110        mark_inode_dirty(inode);
111	bfs_dump_imap("create", s);
112
113	err = bfs_add_entry(dir, &dentry->d_name, inode->i_ino);
 
114	if (err) {
115		inode_dec_link_count(inode);
116		mutex_unlock(&info->bfs_lock);
117		iput(inode);
118		return err;
119	}
120	mutex_unlock(&info->bfs_lock);
121	d_instantiate(dentry, inode);
122	return 0;
123}
124
125static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
126						unsigned int flags)
127{
128	struct inode *inode = NULL;
129	struct buffer_head *bh;
130	struct bfs_dirent *de;
131	struct bfs_sb_info *info = BFS_SB(dir->i_sb);
132
133	if (dentry->d_name.len > BFS_NAMELEN)
134		return ERR_PTR(-ENAMETOOLONG);
135
136	mutex_lock(&info->bfs_lock);
137	bh = bfs_find_entry(dir, &dentry->d_name, &de);
138	if (bh) {
139		unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
140		brelse(bh);
141		inode = bfs_iget(dir->i_sb, ino);
 
 
 
 
142	}
143	mutex_unlock(&info->bfs_lock);
144	return d_splice_alias(inode, dentry);
 
145}
146
147static int bfs_link(struct dentry *old, struct inode *dir,
148						struct dentry *new)
149{
150	struct inode *inode = d_inode(old);
151	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
152	int err;
153
154	mutex_lock(&info->bfs_lock);
155	err = bfs_add_entry(dir, &new->d_name, inode->i_ino);
 
156	if (err) {
157		mutex_unlock(&info->bfs_lock);
158		return err;
159	}
160	inc_nlink(inode);
161	inode_set_ctime_current(inode);
162	mark_inode_dirty(inode);
163	ihold(inode);
164	d_instantiate(new, inode);
165	mutex_unlock(&info->bfs_lock);
166	return 0;
167}
168
169static int bfs_unlink(struct inode *dir, struct dentry *dentry)
170{
171	int error = -ENOENT;
172	struct inode *inode = d_inode(dentry);
173	struct buffer_head *bh;
174	struct bfs_dirent *de;
175	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
176
177	mutex_lock(&info->bfs_lock);
178	bh = bfs_find_entry(dir, &dentry->d_name, &de);
179	if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
180		goto out_brelse;
181
182	if (!inode->i_nlink) {
183		printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
184					inode->i_sb->s_id, inode->i_ino,
185					inode->i_nlink);
186		set_nlink(inode, 1);
187	}
188	de->ino = 0;
189	mark_buffer_dirty_inode(bh, dir);
190	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
191	mark_inode_dirty(dir);
192	inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
193	inode_dec_link_count(inode);
194	error = 0;
195
196out_brelse:
197	brelse(bh);
198	mutex_unlock(&info->bfs_lock);
199	return error;
200}
201
202static int bfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
203		      struct dentry *old_dentry, struct inode *new_dir,
204		      struct dentry *new_dentry, unsigned int flags)
205{
206	struct inode *old_inode, *new_inode;
207	struct buffer_head *old_bh, *new_bh;
208	struct bfs_dirent *old_de, *new_de;
209	struct bfs_sb_info *info;
210	int error = -ENOENT;
211
212	if (flags & ~RENAME_NOREPLACE)
213		return -EINVAL;
214
215	old_bh = new_bh = NULL;
216	old_inode = d_inode(old_dentry);
217	if (S_ISDIR(old_inode->i_mode))
218		return -EINVAL;
219
220	info = BFS_SB(old_inode->i_sb);
221
222	mutex_lock(&info->bfs_lock);
223	old_bh = bfs_find_entry(old_dir, &old_dentry->d_name, &old_de);
 
 
224
225	if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
226		goto end_rename;
227
228	error = -EPERM;
229	new_inode = d_inode(new_dentry);
230	new_bh = bfs_find_entry(new_dir, &new_dentry->d_name, &new_de);
 
 
231
232	if (new_bh && !new_inode) {
233		brelse(new_bh);
234		new_bh = NULL;
235	}
236	if (!new_bh) {
237		error = bfs_add_entry(new_dir, &new_dentry->d_name,
 
 
238					old_inode->i_ino);
239		if (error)
240			goto end_rename;
241	}
242	old_de->ino = 0;
243	inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir));
244	mark_inode_dirty(old_dir);
245	if (new_inode) {
246		inode_set_ctime_current(new_inode);
247		inode_dec_link_count(new_inode);
248	}
249	mark_buffer_dirty_inode(old_bh, old_dir);
250	error = 0;
251
252end_rename:
253	mutex_unlock(&info->bfs_lock);
254	brelse(old_bh);
255	brelse(new_bh);
256	return error;
257}
258
259const struct inode_operations bfs_dir_inops = {
260	.create			= bfs_create,
261	.lookup			= bfs_lookup,
262	.link			= bfs_link,
263	.unlink			= bfs_unlink,
264	.rename			= bfs_rename,
265};
266
267static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino)
 
268{
269	const unsigned char *name = child->name;
270	int namelen = child->len;
271	struct buffer_head *bh;
272	struct bfs_dirent *de;
273	int block, sblock, eblock, off, pos;
274	int i;
275
276	dprintf("name=%s, namelen=%d\n", name, namelen);
277
 
 
 
 
 
278	sblock = BFS_I(dir)->i_sblock;
279	eblock = BFS_I(dir)->i_eblock;
280	for (block = sblock; block <= eblock; block++) {
281		bh = sb_bread(dir->i_sb, block);
282		if (!bh)
283			return -EIO;
284		for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
285			de = (struct bfs_dirent *)(bh->b_data + off);
286			if (!de->ino) {
287				pos = (block - sblock) * BFS_BSIZE + off;
288				if (pos >= dir->i_size) {
289					dir->i_size += BFS_DIRENT_SIZE;
290					inode_set_ctime_current(dir);
291				}
292				inode_set_mtime_to_ts(dir,
293						      inode_set_ctime_current(dir));
294				mark_inode_dirty(dir);
295				de->ino = cpu_to_le16((u16)ino);
296				for (i = 0; i < BFS_NAMELEN; i++)
297					de->name[i] =
298						(i < namelen) ? name[i] : 0;
299				mark_buffer_dirty_inode(bh, dir);
300				brelse(bh);
301				return 0;
302			}
303		}
304		brelse(bh);
305	}
306	return -ENOSPC;
307}
308
309static inline int bfs_namecmp(int len, const unsigned char *name,
310							const char *buffer)
311{
312	if ((len < BFS_NAMELEN) && buffer[len])
313		return 0;
314	return !memcmp(name, buffer, len);
315}
316
317static struct buffer_head *bfs_find_entry(struct inode *dir,
318			const struct qstr *child,
319			struct bfs_dirent **res_dir)
320{
321	unsigned long block = 0, offset = 0;
322	struct buffer_head *bh = NULL;
323	struct bfs_dirent *de;
324	const unsigned char *name = child->name;
325	int namelen = child->len;
326
327	*res_dir = NULL;
328	if (namelen > BFS_NAMELEN)
329		return NULL;
330
331	while (block * BFS_BSIZE + offset < dir->i_size) {
332		if (!bh) {
333			bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
334			if (!bh) {
335				block++;
336				continue;
337			}
338		}
339		de = (struct bfs_dirent *)(bh->b_data + offset);
340		offset += BFS_DIRENT_SIZE;
341		if (le16_to_cpu(de->ino) &&
342				bfs_namecmp(namelen, name, de->name)) {
343			*res_dir = de;
344			return bh;
345		}
346		if (offset < bh->b_size)
347			continue;
348		brelse(bh);
349		bh = NULL;
350		offset = 0;
351		block++;
352	}
353	brelse(bh);
354	return NULL;
355}
v4.6
 
  1/*
  2 *	fs/bfs/dir.c
  3 *	BFS directory operations.
  4 *	Copyright (C) 1999,2000  Tigran Aivazian <tigran@veritas.com>
  5 *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
  6 */
  7
  8#include <linux/time.h>
  9#include <linux/string.h>
 10#include <linux/fs.h>
 11#include <linux/buffer_head.h>
 12#include <linux/sched.h>
 13#include "bfs.h"
 14
 15#undef DEBUG
 16
 17#ifdef DEBUG
 18#define dprintf(x...)	printf(x)
 19#else
 20#define dprintf(x...)
 21#endif
 22
 23static int bfs_add_entry(struct inode *dir, const unsigned char *name,
 24						int namelen, int ino);
 25static struct buffer_head *bfs_find_entry(struct inode *dir,
 26				const unsigned char *name, int namelen,
 27				struct bfs_dirent **res_dir);
 28
 29static int bfs_readdir(struct file *f, struct dir_context *ctx)
 30{
 31	struct inode *dir = file_inode(f);
 32	struct buffer_head *bh;
 33	struct bfs_dirent *de;
 34	unsigned int offset;
 35	int block;
 36
 37	if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
 38		printf("Bad f_pos=%08lx for %s:%08lx\n",
 39					(unsigned long)ctx->pos,
 40					dir->i_sb->s_id, dir->i_ino);
 41		return -EINVAL;
 42	}
 43
 44	while (ctx->pos < dir->i_size) {
 45		offset = ctx->pos & (BFS_BSIZE - 1);
 46		block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
 47		bh = sb_bread(dir->i_sb, block);
 48		if (!bh) {
 49			ctx->pos += BFS_BSIZE - offset;
 50			continue;
 51		}
 52		do {
 53			de = (struct bfs_dirent *)(bh->b_data + offset);
 54			if (de->ino) {
 55				int size = strnlen(de->name, BFS_NAMELEN);
 56				if (!dir_emit(ctx, de->name, size,
 57						le16_to_cpu(de->ino),
 58						DT_UNKNOWN)) {
 59					brelse(bh);
 60					return 0;
 61				}
 62			}
 63			offset += BFS_DIRENT_SIZE;
 64			ctx->pos += BFS_DIRENT_SIZE;
 65		} while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
 66		brelse(bh);
 67	}
 68	return 0;
 69}
 70
 71const struct file_operations bfs_dir_operations = {
 72	.read		= generic_read_dir,
 73	.iterate	= bfs_readdir,
 74	.fsync		= generic_file_fsync,
 75	.llseek		= generic_file_llseek,
 76};
 77
 78static int bfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 79						bool excl)
 80{
 81	int err;
 82	struct inode *inode;
 83	struct super_block *s = dir->i_sb;
 84	struct bfs_sb_info *info = BFS_SB(s);
 85	unsigned long ino;
 86
 87	inode = new_inode(s);
 88	if (!inode)
 89		return -ENOMEM;
 90	mutex_lock(&info->bfs_lock);
 91	ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
 92	if (ino > info->si_lasti) {
 93		mutex_unlock(&info->bfs_lock);
 94		iput(inode);
 95		return -ENOSPC;
 96	}
 97	set_bit(ino, info->si_imap);
 98	info->si_freei--;
 99	inode_init_owner(inode, dir, mode);
100	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
101	inode->i_blocks = 0;
102	inode->i_op = &bfs_file_inops;
103	inode->i_fop = &bfs_file_operations;
104	inode->i_mapping->a_ops = &bfs_aops;
105	inode->i_ino = ino;
106	BFS_I(inode)->i_dsk_ino = ino;
107	BFS_I(inode)->i_sblock = 0;
108	BFS_I(inode)->i_eblock = 0;
109	insert_inode_hash(inode);
110        mark_inode_dirty(inode);
111	bfs_dump_imap("create", s);
112
113	err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len,
114							inode->i_ino);
115	if (err) {
116		inode_dec_link_count(inode);
117		mutex_unlock(&info->bfs_lock);
118		iput(inode);
119		return err;
120	}
121	mutex_unlock(&info->bfs_lock);
122	d_instantiate(dentry, inode);
123	return 0;
124}
125
126static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
127						unsigned int flags)
128{
129	struct inode *inode = NULL;
130	struct buffer_head *bh;
131	struct bfs_dirent *de;
132	struct bfs_sb_info *info = BFS_SB(dir->i_sb);
133
134	if (dentry->d_name.len > BFS_NAMELEN)
135		return ERR_PTR(-ENAMETOOLONG);
136
137	mutex_lock(&info->bfs_lock);
138	bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
139	if (bh) {
140		unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
141		brelse(bh);
142		inode = bfs_iget(dir->i_sb, ino);
143		if (IS_ERR(inode)) {
144			mutex_unlock(&info->bfs_lock);
145			return ERR_CAST(inode);
146		}
147	}
148	mutex_unlock(&info->bfs_lock);
149	d_add(dentry, inode);
150	return NULL;
151}
152
153static int bfs_link(struct dentry *old, struct inode *dir,
154						struct dentry *new)
155{
156	struct inode *inode = d_inode(old);
157	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
158	int err;
159
160	mutex_lock(&info->bfs_lock);
161	err = bfs_add_entry(dir, new->d_name.name, new->d_name.len,
162							inode->i_ino);
163	if (err) {
164		mutex_unlock(&info->bfs_lock);
165		return err;
166	}
167	inc_nlink(inode);
168	inode->i_ctime = CURRENT_TIME_SEC;
169	mark_inode_dirty(inode);
170	ihold(inode);
171	d_instantiate(new, inode);
172	mutex_unlock(&info->bfs_lock);
173	return 0;
174}
175
176static int bfs_unlink(struct inode *dir, struct dentry *dentry)
177{
178	int error = -ENOENT;
179	struct inode *inode = d_inode(dentry);
180	struct buffer_head *bh;
181	struct bfs_dirent *de;
182	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
183
184	mutex_lock(&info->bfs_lock);
185	bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
186	if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
187		goto out_brelse;
188
189	if (!inode->i_nlink) {
190		printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
191					inode->i_sb->s_id, inode->i_ino,
192					inode->i_nlink);
193		set_nlink(inode, 1);
194	}
195	de->ino = 0;
196	mark_buffer_dirty_inode(bh, dir);
197	dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
198	mark_inode_dirty(dir);
199	inode->i_ctime = dir->i_ctime;
200	inode_dec_link_count(inode);
201	error = 0;
202
203out_brelse:
204	brelse(bh);
205	mutex_unlock(&info->bfs_lock);
206	return error;
207}
208
209static int bfs_rename(struct inode *old_dir, struct dentry *old_dentry,
210			struct inode *new_dir, struct dentry *new_dentry)
 
211{
212	struct inode *old_inode, *new_inode;
213	struct buffer_head *old_bh, *new_bh;
214	struct bfs_dirent *old_de, *new_de;
215	struct bfs_sb_info *info;
216	int error = -ENOENT;
217
 
 
 
218	old_bh = new_bh = NULL;
219	old_inode = d_inode(old_dentry);
220	if (S_ISDIR(old_inode->i_mode))
221		return -EINVAL;
222
223	info = BFS_SB(old_inode->i_sb);
224
225	mutex_lock(&info->bfs_lock);
226	old_bh = bfs_find_entry(old_dir, 
227				old_dentry->d_name.name, 
228				old_dentry->d_name.len, &old_de);
229
230	if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
231		goto end_rename;
232
233	error = -EPERM;
234	new_inode = d_inode(new_dentry);
235	new_bh = bfs_find_entry(new_dir, 
236				new_dentry->d_name.name, 
237				new_dentry->d_name.len, &new_de);
238
239	if (new_bh && !new_inode) {
240		brelse(new_bh);
241		new_bh = NULL;
242	}
243	if (!new_bh) {
244		error = bfs_add_entry(new_dir, 
245					new_dentry->d_name.name,
246					new_dentry->d_name.len,
247					old_inode->i_ino);
248		if (error)
249			goto end_rename;
250	}
251	old_de->ino = 0;
252	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
253	mark_inode_dirty(old_dir);
254	if (new_inode) {
255		new_inode->i_ctime = CURRENT_TIME_SEC;
256		inode_dec_link_count(new_inode);
257	}
258	mark_buffer_dirty_inode(old_bh, old_dir);
259	error = 0;
260
261end_rename:
262	mutex_unlock(&info->bfs_lock);
263	brelse(old_bh);
264	brelse(new_bh);
265	return error;
266}
267
268const struct inode_operations bfs_dir_inops = {
269	.create			= bfs_create,
270	.lookup			= bfs_lookup,
271	.link			= bfs_link,
272	.unlink			= bfs_unlink,
273	.rename			= bfs_rename,
274};
275
276static int bfs_add_entry(struct inode *dir, const unsigned char *name,
277							int namelen, int ino)
278{
 
 
279	struct buffer_head *bh;
280	struct bfs_dirent *de;
281	int block, sblock, eblock, off, pos;
282	int i;
283
284	dprintf("name=%s, namelen=%d\n", name, namelen);
285
286	if (!namelen)
287		return -ENOENT;
288	if (namelen > BFS_NAMELEN)
289		return -ENAMETOOLONG;
290
291	sblock = BFS_I(dir)->i_sblock;
292	eblock = BFS_I(dir)->i_eblock;
293	for (block = sblock; block <= eblock; block++) {
294		bh = sb_bread(dir->i_sb, block);
295		if (!bh)
296			return -EIO;
297		for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
298			de = (struct bfs_dirent *)(bh->b_data + off);
299			if (!de->ino) {
300				pos = (block - sblock) * BFS_BSIZE + off;
301				if (pos >= dir->i_size) {
302					dir->i_size += BFS_DIRENT_SIZE;
303					dir->i_ctime = CURRENT_TIME_SEC;
304				}
305				dir->i_mtime = CURRENT_TIME_SEC;
 
306				mark_inode_dirty(dir);
307				de->ino = cpu_to_le16((u16)ino);
308				for (i = 0; i < BFS_NAMELEN; i++)
309					de->name[i] =
310						(i < namelen) ? name[i] : 0;
311				mark_buffer_dirty_inode(bh, dir);
312				brelse(bh);
313				return 0;
314			}
315		}
316		brelse(bh);
317	}
318	return -ENOSPC;
319}
320
321static inline int bfs_namecmp(int len, const unsigned char *name,
322							const char *buffer)
323{
324	if ((len < BFS_NAMELEN) && buffer[len])
325		return 0;
326	return !memcmp(name, buffer, len);
327}
328
329static struct buffer_head *bfs_find_entry(struct inode *dir,
330			const unsigned char *name, int namelen,
331			struct bfs_dirent **res_dir)
332{
333	unsigned long block = 0, offset = 0;
334	struct buffer_head *bh = NULL;
335	struct bfs_dirent *de;
 
 
336
337	*res_dir = NULL;
338	if (namelen > BFS_NAMELEN)
339		return NULL;
340
341	while (block * BFS_BSIZE + offset < dir->i_size) {
342		if (!bh) {
343			bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
344			if (!bh) {
345				block++;
346				continue;
347			}
348		}
349		de = (struct bfs_dirent *)(bh->b_data + offset);
350		offset += BFS_DIRENT_SIZE;
351		if (le16_to_cpu(de->ino) &&
352				bfs_namecmp(namelen, name, de->name)) {
353			*res_dir = de;
354			return bh;
355		}
356		if (offset < bh->b_size)
357			continue;
358		brelse(bh);
359		bh = NULL;
360		offset = 0;
361		block++;
362	}
363	brelse(bh);
364	return NULL;
365}