summaryrefslogtreecommitdiff
path: root/fs/omfs/dir.c
blob: e81f06be5e7bd2262f767e6c22ab0e70e62bb4d2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
/*
 * OMFS (as used by RIO Karma) directory operations.
 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
 * Released under GPL v2.
 */

#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/buffer_head.h>
#include "omfs.h"

static int omfs_hash(const char *name, int namelen, int mod)
{
	int i, hash = 0;
	for (i = 0; i < namelen; i++)
		hash ^= tolower(name[i]) << (i % 24);
	return hash % mod;
}

/*
 * Finds the bucket for a given name and reads the containing block;
 * *ofs is set to the offset of the first list entry.
 */
static struct buffer_head *omfs_get_bucket(struct inode *dir,
		const char *name, int namelen, int *ofs)
{
	int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
	int bucket = omfs_hash(name, namelen, nbuckets);

	*ofs = OMFS_DIR_START + bucket * 8;
	return omfs_bread(dir->i_sb, dir->i_ino);
}

static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
				const char *name, int namelen,
				u64 *prev_block)
{
	struct buffer_head *bh;
	struct omfs_inode *oi;
	int err = -ENOENT;
	*prev_block = ~0;

	while (block != ~0) {
		bh = omfs_bread(dir->i_sb, block);
		if (!bh) {
			err = -EIO;
			goto err;
		}

		oi = (struct omfs_inode *) bh->b_data;
		if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
			brelse(bh);
			goto err;
		}

		if (strncmp(oi->i_name, name, namelen) == 0)
			return bh;

		*prev_block = block;
		block = be64_to_cpu(oi->i_sibling);
		brelse(bh);
	}
err:
	return ERR_PTR(err);
}

static struct buffer_head *omfs_find_entry(struct inode *dir,
					   const char *name, int namelen)
{
	struct buffer_head *bh;
	int ofs;
	u64 block, dummy;

	bh = omfs_get_bucket(dir, name, namelen, &ofs);
	if (!bh)
		return ERR_PTR(-EIO);

	block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
	brelse(bh);

	return omfs_scan_list(dir, block, name, namelen, &dummy);
}

int omfs_make_empty(struct inode *inode, struct super_block *sb)
{
	struct omfs_sb_info *sbi = OMFS_SB(sb);
	struct buffer_head *bh;
	struct omfs_inode *oi;

	bh = omfs_bread(sb, inode->i_ino);
	if (!bh)
		return -ENOMEM;

	memset(bh->b_data, 0, sizeof(struct omfs_inode));

	if (S_ISDIR(inode->i_mode)) {
		memset(&bh->b_data[OMFS_DIR_START], 0xff,
			sbi->s_sys_blocksize - OMFS_DIR_START);
	} else
		omfs_make_empty_table(bh, OMFS_EXTENT_START);

	oi = (struct omfs_inode *) bh->b_data;
	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
	oi->i_sibling = ~cpu_to_be64(0ULL);

	mark_buffer_dirty(bh);
	brelse(bh);
	return 0;
}

static int omfs_add_link(struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = d_inode(dentry->d_parent);
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct omfs_inode *oi;
	struct buffer_head *bh;
	u64 block;
	__be64 *entry;
	int ofs;

	/* just prepend to head of queue in proper bucket */
	bh = omfs_get_bucket(dir, name, namelen, &ofs);
	if (!bh)
		goto out;

	entry = (__be64 *) &bh->b_data[ofs];
	block = be64_to_cpu(*entry);
	*entry = cpu_to_be64(inode->i_ino);
	mark_buffer_dirty(bh);
	brelse(bh);

	/* now set the sibling and parent pointers on the new inode */
	bh = omfs_bread(dir->i_sb, inode->i_ino);
	if (!bh)
		goto out;

	oi = (struct omfs_inode *) bh->b_data;
	memcpy(oi->i_name, name, namelen);
	memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
	oi->i_sibling = cpu_to_be64(block);
	oi->i_parent = cpu_to_be64(dir->i_ino);
	mark_buffer_dirty(bh);
	brelse(bh);

	dir->i_ctime = CURRENT_TIME_SEC;

	/* mark affected inodes dirty to rebuild checksums */
	mark_inode_dirty(dir);
	mark_inode_dirty(inode);
	return 0;
out:
	return -ENOMEM;
}

static int omfs_delete_entry(struct dentry *dentry)
{
	struct inode *dir = d_inode(dentry->d_parent);
	struct inode *dirty;
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct omfs_inode *oi;
	struct buffer_head *bh, *bh2;
	__be64 *entry, next;
	u64 block, prev;
	int ofs;
	int err = -ENOMEM;

	/* delete the proper node in the bucket's linked list */
	bh = omfs_get_bucket(dir, name, namelen, &ofs);
	if (!bh)
		goto out;

	entry = (__be64 *) &bh->b_data[ofs];
	block = be64_to_cpu(*entry);

	bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
	if (IS_ERR(bh2)) {
		err = PTR_ERR(bh2);
		goto out_free_bh;
	}

	oi = (struct omfs_inode *) bh2->b_data;
	next = oi->i_sibling;
	brelse(bh2);

	if (prev != ~0) {
		/* found in middle of list, get list ptr */
		brelse(bh);
		bh = omfs_bread(dir->i_sb, prev);
		if (!bh)
			goto out;

		oi = (struct omfs_inode *) bh->b_data;
		entry = &oi->i_sibling;
	}

	*entry = next;
	mark_buffer_dirty(bh);

	if (prev != ~0) {
		dirty = omfs_iget(dir->i_sb, prev);
		if (!IS_ERR(dirty)) {
			mark_inode_dirty(dirty);
			iput(dirty);
		}
	}

	err = 0;
out_free_bh:
	brelse(bh);
out:
	return err;
}

static int omfs_dir_is_empty(struct inode *inode)
{
	int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
	struct buffer_head *bh;
	u64 *ptr;
	int i;

	bh = omfs_bread(inode->i_sb, inode->i_ino);

	if (!bh)
		return 0;

	ptr = (u64 *) &bh->b_data[OMFS_DIR_START];

	for (i = 0; i < nbuckets; i++, ptr++)
		if (*ptr != ~0)
			break;

	brelse(bh);
	return *ptr != ~0;
}

static int omfs_remove(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);
	int ret;


	if (S_ISDIR(inode->i_mode) &&
	    !omfs_dir_is_empty(inode))
		return -ENOTEMPTY;

	ret = omfs_delete_entry(dentry);
	if (ret)
		return ret;
	
	clear_nlink(inode);
	mark_inode_dirty(inode);
	mark_inode_dirty(dir);
	return 0;
}

static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
{
	int err;
	struct inode *inode = omfs_new_inode(dir, mode);

	if (IS_ERR(inode))
		return PTR_ERR(inode);

	err = omfs_make_empty(inode, dir->i_sb);
	if (err)
		goto out_free_inode;

	err = omfs_add_link(dentry, inode);
	if (err)
		goto out_free_inode;

	d_instantiate(dentry, inode);
	return 0;

out_free_inode:
	iput(inode);
	return err;
}

static int omfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
	return omfs_add_node(dir, dentry, mode | S_IFDIR);
}

static int omfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
		bool excl)
{
	return omfs_add_node(dir, dentry, mode | S_IFREG);
}

static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
				  unsigned int flags)
{
	struct buffer_head *bh;
	struct inode *inode = NULL;

	if (dentry->d_name.len > OMFS_NAMELEN)
		return ERR_PTR(-ENAMETOOLONG);

	bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
	if (!IS_ERR(bh)) {
		struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
		ino_t ino = be64_to_cpu(oi->i_head.h_self);
		brelse(bh);
		inode = omfs_iget(dir->i_sb, ino);
		if (IS_ERR(inode))
			return ERR_CAST(inode);
	}
	d_add(dentry, inode);
	return NULL;
}

/* sanity check block's self pointer */
int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
	u64 fsblock)
{
	int is_bad;
	u64 ino = be64_to_cpu(header->h_self);
	is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
		(ino > sbi->s_num_blocks));

	if (is_bad)
		printk(KERN_WARNING "omfs: bad hash chain detected\n");

	return is_bad;
}

static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
		u64 fsblock, int hindex)
{
	/* follow chain in this bucket */
	while (fsblock != ~0) {
		struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
		struct omfs_inode *oi;
		u64 self;
		unsigned char d_type;

		if (!bh)
			return true;

		oi = (struct omfs_inode *) bh->b_data;
		if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
			brelse(bh);
			return true;
		}

		self = fsblock;
		fsblock = be64_to_cpu(oi->i_sibling);

		/* skip visited nodes */
		if (hindex) {
			hindex--;
			brelse(bh);
			continue;
		}

		d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;

		if (!dir_emit(ctx, oi->i_name,
			      strnlen(oi->i_name, OMFS_NAMELEN),
			      self, d_type)) {
			brelse(bh);
			return false;
		}
		brelse(bh);
		ctx->pos++;
	}
	return true;
}

static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
		       struct inode *new_dir, struct dentry *new_dentry,
		       unsigned int flags)
{
	struct inode *new_inode = d_inode(new_dentry);
	struct inode *old_inode = d_inode(old_dentry);
	int err;

	if (flags & ~RENAME_NOREPLACE)
		return -EINVAL;

	if (new_inode) {
		/* overwriting existing file/dir */
		err = omfs_remove(new_dir, new_dentry);
		if (err)
			goto out;
	}

	/* since omfs locates files by name, we need to unlink _before_
	 * adding the new link or we won't find the old one */
	err = omfs_delete_entry(old_dentry);
	if (err)
		goto out;

	mark_inode_dirty(old_dir);
	err = omfs_add_link(new_dentry, old_inode);
	if (err)
		goto out;

	old_inode->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(old_inode);
out:
	return err;
}

static int omfs_readdir(struct file *file, struct dir_context *ctx)
{
	struct inode *dir = file_inode(file);
	struct buffer_head *bh;
	__be64 *p;
	unsigned int hchain, hindex;
	int nbuckets;

	if (ctx->pos >> 32)
		return -EINVAL;

	if (ctx->pos < 1 << 20) {
		if (!dir_emit_dots(file, ctx))
			return 0;
		ctx->pos = 1 << 20;
	}

	nbuckets = (dir->i_size - OMFS_DIR_START) / 8;

	/* high 12 bits store bucket + 1 and low 20 bits store hash index */
	hchain = (ctx->pos >> 20) - 1;
	hindex = ctx->pos & 0xfffff;

	bh = omfs_bread(dir->i_sb, dir->i_ino);
	if (!bh)
		return -EINVAL;

	p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;

	for (; hchain < nbuckets; hchain++) {
		__u64 fsblock = be64_to_cpu(*p++);
		if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
			break;
		hindex = 0;
		ctx->pos = (hchain+2) << 20;
	}
	brelse(bh);
	return 0;
}

const struct inode_operations omfs_dir_inops = {
	.lookup = omfs_lookup,
	.mkdir = omfs_mkdir,
	.rename = omfs_rename,
	.create = omfs_create,
	.unlink = omfs_remove,
	.rmdir = omfs_remove,
};

const struct file_operations omfs_dir_operations = {
	.read = generic_read_dir,
	.iterate_shared = omfs_readdir,
	.llseek = generic_file_llseek,
};