1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * OMFS (as used by RIO Karma) directory operations.
4 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
5 */
6
7 #include <linux/fs.h>
8 #include <linux/ctype.h>
9 #include <linux/buffer_head.h>
10 #include "omfs.h"
11
12 static int omfs_hash(const char *name, int namelen, int mod)
13 {
14 int i, hash = 0;
15 for (i = 0; i < namelen; i++)
16 hash ^= tolower(name[i]) << (i % 24);
17 return hash % mod;
18 }
19
20 /*
21 * Finds the bucket for a given name and reads the containing block;
22 * *ofs is set to the offset of the first list entry.
23 */
24 static struct buffer_head *omfs_get_bucket(struct inode *dir,
25 const char *name, int namelen, int *ofs)
26 {
27 int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
28 int bucket = omfs_hash(name, namelen, nbuckets);
29
30 *ofs = OMFS_DIR_START + bucket * 8;
31 return omfs_bread(dir->i_sb, dir->i_ino);
32 }
33
34 static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
35 const char *name, int namelen,
36 u64 *prev_block)
37 {
38 struct buffer_head *bh;
39 struct omfs_inode *oi;
40 int err = -ENOENT;
41 *prev_block = ~0;
42
43 while (block != ~0) {
44 bh = omfs_bread(dir->i_sb, block);
45 if (!bh) {
46 err = -EIO;
47 goto err;
48 }
49
50 oi = (struct omfs_inode *) bh->b_data;
51 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
52 brelse(bh);
53 goto err;
54 }
55
56 if (strncmp(oi->i_name, name, namelen) == 0)
57 return bh;
58
59 *prev_block = block;
60 block = be64_to_cpu(oi->i_sibling);
61 brelse(bh);
62 }
63 err:
64 return ERR_PTR(err);
65 }
66
67 static struct buffer_head *omfs_find_entry(struct inode *dir,
68 const char *name, int namelen)
69 {
70 struct buffer_head *bh;
71 int ofs;
72 u64 block, dummy;
73
74 bh = omfs_get_bucket(dir, name, namelen, &ofs);
75 if (!bh)
76 return ERR_PTR(-EIO);
77
78 block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
79 brelse(bh);
80
81 return omfs_scan_list(dir, block, name, namelen, &dummy);
82 }
83
84 int omfs_make_empty(struct inode *inode, struct super_block *sb)
85 {
86 struct omfs_sb_info *sbi = OMFS_SB(sb);
87 struct buffer_head *bh;
88 struct omfs_inode *oi;
89
90 bh = omfs_bread(sb, inode->i_ino);
91 if (!bh)
92 return -ENOMEM;
93
94 memset(bh->b_data, 0, sizeof(struct omfs_inode));
95
96 if (S_ISDIR(inode->i_mode)) {
97 memset(&bh->b_data[OMFS_DIR_START], 0xff,
98 sbi->s_sys_blocksize - OMFS_DIR_START);
99 } else
100 omfs_make_empty_table(bh, OMFS_EXTENT_START);
101
102 oi = (struct omfs_inode *) bh->b_data;
103 oi->i_head.h_self = cpu_to_be64(inode->i_ino);
104 oi->i_sibling = ~cpu_to_be64(0ULL);
105
106 mark_buffer_dirty(bh);
107 brelse(bh);
108 return 0;
109 }
110
111 static int omfs_add_link(struct dentry *dentry, struct inode *inode)
112 {
113 struct inode *dir = d_inode(dentry->d_parent);
114 const char *name = dentry->d_name.name;
115 int namelen = dentry->d_name.len;
116 struct omfs_inode *oi;
117 struct buffer_head *bh;
118 u64 block;
119 __be64 *entry;
120 int ofs;
121
122 /* just prepend to head of queue in proper bucket */
123 bh = omfs_get_bucket(dir, name, namelen, &ofs);
124 if (!bh)
125 goto out;
126
127 entry = (__be64 *) &bh->b_data[ofs];
128 block = be64_to_cpu(*entry);
129 *entry = cpu_to_be64(inode->i_ino);
130 mark_buffer_dirty(bh);
131 brelse(bh);
132
133 /* now set the sibling and parent pointers on the new inode */
134 bh = omfs_bread(dir->i_sb, inode->i_ino);
135 if (!bh)
136 goto out;
137
138 oi = (struct omfs_inode *) bh->b_data;
139 memcpy(oi->i_name, name, namelen);
140 memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
141 oi->i_sibling = cpu_to_be64(block);
142 oi->i_parent = cpu_to_be64(dir->i_ino);
143 mark_buffer_dirty(bh);
144 brelse(bh);
145
146 inode_set_ctime_current(dir);
147
148 /* mark affected inodes dirty to rebuild checksums */
149 mark_inode_dirty(dir);
150 mark_inode_dirty(inode);
151 return 0;
152 out:
153 return -ENOMEM;
154 }
155
156 static int omfs_delete_entry(struct dentry *dentry)
157 {
158 struct inode *dir = d_inode(dentry->d_parent);
159 struct inode *dirty;
160 const char *name = dentry->d_name.name;
161 int namelen = dentry->d_name.len;
162 struct omfs_inode *oi;
163 struct buffer_head *bh, *bh2;
164 __be64 *entry, next;
165 u64 block, prev;
166 int ofs;
167 int err = -ENOMEM;
168
169 /* delete the proper node in the bucket's linked list */
170 bh = omfs_get_bucket(dir, name, namelen, &ofs);
171 if (!bh)
172 goto out;
173
174 entry = (__be64 *) &bh->b_data[ofs];
175 block = be64_to_cpu(*entry);
176
177 bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
178 if (IS_ERR(bh2)) {
179 err = PTR_ERR(bh2);
180 goto out_free_bh;
181 }
182
183 oi = (struct omfs_inode *) bh2->b_data;
184 next = oi->i_sibling;
185 brelse(bh2);
186
187 if (prev != ~0) {
188 /* found in middle of list, get list ptr */
189 brelse(bh);
190 bh = omfs_bread(dir->i_sb, prev);
191 if (!bh)
192 goto out;
193
194 oi = (struct omfs_inode *) bh->b_data;
195 entry = &oi->i_sibling;
196 }
197
198 *entry = next;
199 mark_buffer_dirty(bh);
200
201 if (prev != ~0) {
202 dirty = omfs_iget(dir->i_sb, prev);
203 if (!IS_ERR(dirty)) {
204 mark_inode_dirty(dirty);
205 iput(dirty);
206 }
207 }
208
209 err = 0;
210 out_free_bh:
211 brelse(bh);
212 out:
213 return err;
214 }
215
216 static int omfs_dir_is_empty(struct inode *inode)
217 {
218 int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
219 struct buffer_head *bh;
220 u64 *ptr;
221 int i;
222
223 bh = omfs_bread(inode->i_sb, inode->i_ino);
224
225 if (!bh)
226 return 0;
227
228 ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
229
230 for (i = 0; i < nbuckets; i++, ptr++)
231 if (*ptr != ~0)
232 break;
233
234 brelse(bh);
235 return *ptr != ~0;
236 }
237
238 static int omfs_remove(struct inode *dir, struct dentry *dentry)
239 {
240 struct inode *inode = d_inode(dentry);
241 int ret;
242
243
244 if (S_ISDIR(inode->i_mode) &&
245 !omfs_dir_is_empty(inode))
246 return -ENOTEMPTY;
247
248 ret = omfs_delete_entry(dentry);
249 if (ret)
250 return ret;
251
252 clear_nlink(inode);
253 mark_inode_dirty(inode);
254 mark_inode_dirty(dir);
255 return 0;
256 }
257
258 static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
259 {
260 int err;
261 struct inode *inode = omfs_new_inode(dir, mode);
262
263 if (IS_ERR(inode))
264 return PTR_ERR(inode);
265
266 err = omfs_make_empty(inode, dir->i_sb);
267 if (err)
268 goto out_free_inode;
269
270 err = omfs_add_link(dentry, inode);
271 if (err)
272 goto out_free_inode;
273
274 d_instantiate(dentry, inode);
275 return 0;
276
277 out_free_inode:
278 iput(inode);
279 return err;
280 }
281
282 static int omfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
283 struct dentry *dentry, umode_t mode)
284 {
285 return omfs_add_node(dir, dentry, mode | S_IFDIR);
286 }
287
288 static int omfs_create(struct mnt_idmap *idmap, struct inode *dir,
289 struct dentry *dentry, umode_t mode, bool excl)
290 {
291 return omfs_add_node(dir, dentry, mode | S_IFREG);
292 }
293
294 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
295 unsigned int flags)
296 {
297 struct buffer_head *bh;
298 struct inode *inode = NULL;
299
300 if (dentry->d_name.len > OMFS_NAMELEN)
301 return ERR_PTR(-ENAMETOOLONG);
302
303 bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
304 if (!IS_ERR(bh)) {
305 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
306 ino_t ino = be64_to_cpu(oi->i_head.h_self);
307 brelse(bh);
308 inode = omfs_iget(dir->i_sb, ino);
309 } else if (bh != ERR_PTR(-ENOENT)) {
310 inode = ERR_CAST(bh);
311 }
312 return d_splice_alias(inode, dentry);
313 }
314
315 /* sanity check block's self pointer */
316 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
317 u64 fsblock)
318 {
319 int is_bad;
320 u64 ino = be64_to_cpu(header->h_self);
321 is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
322 (ino > sbi->s_num_blocks));
323
324 if (is_bad)
325 printk(KERN_WARNING "omfs: bad hash chain detected\n");
326
327 return is_bad;
328 }
329
330 static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
331 u64 fsblock, int hindex)
332 {
333 /* follow chain in this bucket */
334 while (fsblock != ~0) {
335 struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
336 struct omfs_inode *oi;
337 u64 self;
338 unsigned char d_type;
339
340 if (!bh)
341 return true;
342
343 oi = (struct omfs_inode *) bh->b_data;
344 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
345 brelse(bh);
346 return true;
347 }
348
349 self = fsblock;
350 fsblock = be64_to_cpu(oi->i_sibling);
351
352 /* skip visited nodes */
353 if (hindex) {
354 hindex--;
355 brelse(bh);
356 continue;
357 }
358
359 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
360
361 if (!dir_emit(ctx, oi->i_name,
362 strnlen(oi->i_name, OMFS_NAMELEN),
363 self, d_type)) {
364 brelse(bh);
365 return false;
366 }
367 brelse(bh);
368 ctx->pos++;
369 }
370 return true;
371 }
372
373 static int omfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
374 struct dentry *old_dentry, struct inode *new_dir,
375 struct dentry *new_dentry, unsigned int flags)
376 {
377 struct inode *new_inode = d_inode(new_dentry);
378 struct inode *old_inode = d_inode(old_dentry);
379 int err;
380
381 if (flags & ~RENAME_NOREPLACE)
382 return -EINVAL;
383
384 if (new_inode) {
385 /* overwriting existing file/dir */
386 err = omfs_remove(new_dir, new_dentry);
387 if (err)
388 goto out;
389 }
390
391 /* since omfs locates files by name, we need to unlink _before_
392 * adding the new link or we won't find the old one */
393 err = omfs_delete_entry(old_dentry);
394 if (err)
395 goto out;
396
397 mark_inode_dirty(old_dir);
398 err = omfs_add_link(new_dentry, old_inode);
399 if (err)
400 goto out;
401
402 inode_set_ctime_current(old_inode);
403 mark_inode_dirty(old_inode);
404 out:
405 return err;
406 }
407
408 static int omfs_readdir(struct file *file, struct dir_context *ctx)
409 {
410 struct inode *dir = file_inode(file);
411 struct buffer_head *bh;
412 __be64 *p;
413 unsigned int hchain, hindex;
414 int nbuckets;
415
416 if (ctx->pos >> 32)
417 return -EINVAL;
418
419 if (ctx->pos < 1 << 20) {
420 if (!dir_emit_dots(file, ctx))
421 return 0;
422 ctx->pos = 1 << 20;
423 }
424
425 nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
426
427 /* high 12 bits store bucket + 1 and low 20 bits store hash index */
428 hchain = (ctx->pos >> 20) - 1;
429 hindex = ctx->pos & 0xfffff;
430
431 bh = omfs_bread(dir->i_sb, dir->i_ino);
432 if (!bh)
433 return -EINVAL;
434
435 p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;
436
437 for (; hchain < nbuckets; hchain++) {
438 __u64 fsblock = be64_to_cpu(*p++);
439 if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
440 break;
441 hindex = 0;
442 ctx->pos = (hchain+2) << 20;
443 }
444 brelse(bh);
445 return 0;
446 }
447
448 const struct inode_operations omfs_dir_inops = {
449 .lookup = omfs_lookup,
450 .mkdir = omfs_mkdir,
451 .rename = omfs_rename,
452 .create = omfs_create,
453 .unlink = omfs_remove,
454 .rmdir = omfs_remove,
455 };
456
457 const struct file_operations omfs_dir_operations = {
458 .read = generic_read_dir,
459 .iterate_shared = omfs_readdir,
460 .llseek = generic_file_llseek,
461 };
462
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.