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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(inode: dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
47 bh = sb_bread(sb: 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(p: de->name, BFS_NAMELEN);
56 if (!dir_emit(ctx, name: de->name, namelen: 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(sb: s);
85 unsigned long ino;
86
87 inode = new_inode(sb: s);
88 if (!inode)
89 return -ENOMEM;
90 mutex_lock(&info->bfs_lock);
91 ino = find_first_zero_bit(addr: info->si_imap, size: info->si_lasti + 1);
92 if (ino > info->si_lasti) {
93 mutex_unlock(lock: &info->bfs_lock);
94 iput(inode);
95 return -ENOSPC;
96 }
97 set_bit(nr: ino, addr: info->si_imap);
98 info->si_freei--;
99 inode_init_owner(idmap: &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, child: &dentry->d_name, ino: inode->i_ino);
114 if (err) {
115 inode_dec_link_count(inode);
116 mutex_unlock(lock: &info->bfs_lock);
117 iput(inode);
118 return err;
119 }
120 mutex_unlock(lock: &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(sb: dir->i_sb);
132
133 if (dentry->d_name.len > BFS_NAMELEN)
134 return ERR_PTR(error: -ENAMETOOLONG);
135
136 mutex_lock(&info->bfs_lock);
137 bh = bfs_find_entry(dir, child: &dentry->d_name, res_dir: &de);
138 if (bh) {
139 unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
140 brelse(bh);
141 inode = bfs_iget(sb: dir->i_sb, ino);
142 }
143 mutex_unlock(lock: &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(dentry: old);
151 struct bfs_sb_info *info = BFS_SB(sb: inode->i_sb);
152 int err;
153
154 mutex_lock(&info->bfs_lock);
155 err = bfs_add_entry(dir, child: &new->d_name, ino: inode->i_ino);
156 if (err) {
157 mutex_unlock(lock: &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(lock: &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(sb: inode->i_sb);
176
177 mutex_lock(&info->bfs_lock);
178 bh = bfs_find_entry(dir, child: &dentry->d_name, res_dir: &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, nlink: 1);
187 }
188 de->ino = 0;
189 mark_buffer_dirty_inode(bh, inode: dir);
190 inode_set_mtime_to_ts(inode: dir, ts: inode_set_ctime_current(inode: dir));
191 mark_inode_dirty(inode: dir);
192 inode_set_ctime_to_ts(inode, ts: inode_get_ctime(inode: dir));
193 inode_dec_link_count(inode);
194 error = 0;
195
196out_brelse:
197 brelse(bh);
198 mutex_unlock(lock: &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(dentry: old_dentry);
217 if (S_ISDIR(old_inode->i_mode))
218 return -EINVAL;
219
220 info = BFS_SB(sb: old_inode->i_sb);
221
222 mutex_lock(&info->bfs_lock);
223 old_bh = bfs_find_entry(dir: old_dir, child: &old_dentry->d_name, res_dir: &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(dentry: new_dentry);
230 new_bh = bfs_find_entry(dir: new_dir, child: &new_dentry->d_name, res_dir: &new_de);
231
232 if (new_bh && !new_inode) {
233 brelse(bh: new_bh);
234 new_bh = NULL;
235 }
236 if (!new_bh) {
237 error = bfs_add_entry(dir: new_dir, child: &new_dentry->d_name,
238 ino: old_inode->i_ino);
239 if (error)
240 goto end_rename;
241 }
242 old_de->ino = 0;
243 inode_set_mtime_to_ts(inode: old_dir, ts: inode_set_ctime_current(inode: old_dir));
244 mark_inode_dirty(inode: old_dir);
245 if (new_inode) {
246 inode_set_ctime_current(inode: new_inode);
247 inode_dec_link_count(inode: new_inode);
248 }
249 mark_buffer_dirty_inode(bh: old_bh, inode: old_dir);
250 error = 0;
251
252end_rename:
253 mutex_unlock(lock: &info->bfs_lock);
254 brelse(bh: old_bh);
255 brelse(bh: 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(inode: dir)->i_sblock;
279 eblock = BFS_I(inode: dir)->i_eblock;
280 for (block = sblock; block <= eblock; block++) {
281 bh = sb_bread(sb: 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(inode: dir);
291 }
292 inode_set_mtime_to_ts(inode: dir,
293 ts: inode_set_ctime_current(inode: dir));
294 mark_inode_dirty(inode: 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, inode: 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(p: name, q: buffer, size: 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(sb: dir->i_sb, block: BFS_I(inode: 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(len: namelen, name, buffer: 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}
356

source code of linux/fs/bfs/dir.c