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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 user_namespace *mnt_userns, 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(&init_user_ns, inode, dir, mode);
100 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(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->i_ctime = current_time(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 dir->i_ctime = dir->i_mtime = current_time(dir);
191 mark_inode_dirty(dir);
192 inode->i_ctime = dir->i_ctime;
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 user_namespace *mnt_userns, 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 old_dir->i_ctime = old_dir->i_mtime = current_time(old_dir);
244 mark_inode_dirty(old_dir);
245 if (new_inode) {
246 new_inode->i_ctime = current_time(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 if (!namelen)
279 return -ENOENT;
280 if (namelen > BFS_NAMELEN)
281 return -ENAMETOOLONG;
282
283 sblock = BFS_I(dir)->i_sblock;
284 eblock = BFS_I(dir)->i_eblock;
285 for (block = sblock; block <= eblock; block++) {
286 bh = sb_bread(dir->i_sb, block);
287 if (!bh)
288 return -EIO;
289 for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
290 de = (struct bfs_dirent *)(bh->b_data + off);
291 if (!de->ino) {
292 pos = (block - sblock) * BFS_BSIZE + off;
293 if (pos >= dir->i_size) {
294 dir->i_size += BFS_DIRENT_SIZE;
295 dir->i_ctime = current_time(dir);
296 }
297 dir->i_mtime = current_time(dir);
298 mark_inode_dirty(dir);
299 de->ino = cpu_to_le16((u16)ino);
300 for (i = 0; i < BFS_NAMELEN; i++)
301 de->name[i] =
302 (i < namelen) ? name[i] : 0;
303 mark_buffer_dirty_inode(bh, dir);
304 brelse(bh);
305 return 0;
306 }
307 }
308 brelse(bh);
309 }
310 return -ENOSPC;
311}
312
313static inline int bfs_namecmp(int len, const unsigned char *name,
314 const char *buffer)
315{
316 if ((len < BFS_NAMELEN) && buffer[len])
317 return 0;
318 return !memcmp(name, buffer, len);
319}
320
321static struct buffer_head *bfs_find_entry(struct inode *dir,
322 const struct qstr *child,
323 struct bfs_dirent **res_dir)
324{
325 unsigned long block = 0, offset = 0;
326 struct buffer_head *bh = NULL;
327 struct bfs_dirent *de;
328 const unsigned char *name = child->name;
329 int namelen = child->len;
330
331 *res_dir = NULL;
332 if (namelen > BFS_NAMELEN)
333 return NULL;
334
335 while (block * BFS_BSIZE + offset < dir->i_size) {
336 if (!bh) {
337 bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
338 if (!bh) {
339 block++;
340 continue;
341 }
342 }
343 de = (struct bfs_dirent *)(bh->b_data + offset);
344 offset += BFS_DIRENT_SIZE;
345 if (le16_to_cpu(de->ino) &&
346 bfs_namecmp(namelen, name, de->name)) {
347 *res_dir = de;
348 return bh;
349 }
350 if (offset < bh->b_size)
351 continue;
352 brelse(bh);
353 bh = NULL;
354 offset = 0;
355 block++;
356 }
357 brelse(bh);
358 return NULL;
359}
360
