1
// SPDX-License-Identifier: GPL-2.0-or-later
2
/*
3
 *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
4
 */
5

6
#include <linux/blkdev.h>
7
#include <linux/slab.h>
8
#include <linux/bitmap.h>
9
#include <linux/buffer_head.h>
10
#include <linux/backing-dev.h>
11

12
#include "exfat_raw.h"
13
#include "exfat_fs.h"
14

15
#if BITS_PER_LONG == 32
16
#define __le_long __le32
17
#define lel_to_cpu(A) le32_to_cpu(A)
18
#define cpu_to_lel(A) cpu_to_le32(A)
19
#elif BITS_PER_LONG == 64
20
#define __le_long __le64
21
#define lel_to_cpu(A) le64_to_cpu(A)
22
#define cpu_to_lel(A) cpu_to_le64(A)
23
#else
24
#error "BITS_PER_LONG not 32 or 64"
25
#endif
26

27
/*
28
 *  Allocation Bitmap Management Functions
29
 */
30
static bool exfat_test_bitmap_range(struct super_block *sb, unsigned int clu,
31
		unsigned int count)
32
{
33
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
34
	unsigned int start = clu;
35
	unsigned int end = clu + count;
36
	unsigned int ent_idx, i, b;
37
	unsigned int bit_offset, bits_to_check;
38
	__le_long *bitmap_le;
39
	unsigned long mask, word;
40

41
	if (!is_valid_cluster(sbi, start) || !is_valid_cluster(sbi, end - 1))
42
		return false;
43

44
	while (start < end) {
45
		ent_idx = CLUSTER_TO_BITMAP_ENT(start);
46
		i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
47
		b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
48

49
		bitmap_le = (__le_long *)sbi->vol_amap[i]->b_data;
50

51
		/* Calculate how many bits we can check in the current word */
52
		bit_offset = b % BITS_PER_LONG;
53
		bits_to_check = min(end - start,
54
				    (unsigned int)(BITS_PER_LONG - bit_offset));
55

56
		/* Create a bitmask for the range of bits to check */
57
		if (bits_to_check >= BITS_PER_LONG)
58
			mask = ~0UL;
59
		else
60
			mask = ((1UL << bits_to_check) - 1) << bit_offset;
61
		word = lel_to_cpu(bitmap_le[b / BITS_PER_LONG]);
62

63
		/* Check if all bits in the mask are set */
64
		if ((word & mask) != mask)
65
			return false;
66

67
		start += bits_to_check;
68
	}
69

70
	return true;
71
}
72

73
static int exfat_allocate_bitmap(struct super_block *sb,
74
		struct exfat_dentry *ep)
75
{
76
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
77
	struct blk_plug plug;
78
	long long map_size;
79
	unsigned int i, j, need_map_size;
80
	sector_t sector;
81
	unsigned int max_ra_count;
82

83
	sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
84
	map_size = le64_to_cpu(ep->dentry.bitmap.size);
85
	need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)
86
		+ 1;
87
	if (need_map_size != map_size) {
88
		exfat_err(sb, "bogus allocation bitmap size(need : %u, cur : %lld)",
89
			  need_map_size, map_size);
90
		/*
91
		 * Only allowed when bogus allocation
92
		 * bitmap size is large
93
		 */
94
		if (need_map_size > map_size)
95
			return -EIO;
96
	}
97
	sbi->map_sectors = ((need_map_size - 1) >>
98
			(sb->s_blocksize_bits)) + 1;
99
	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
100
				sizeof(struct buffer_head *), GFP_KERNEL);
101
	if (!sbi->vol_amap)
102
		return -ENOMEM;
103

104
	sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
105
	max_ra_count = min(sb->s_bdi->ra_pages, sb->s_bdi->io_pages) <<
106
		(PAGE_SHIFT - sb->s_blocksize_bits);
107
	for (i = 0; i < sbi->map_sectors; i++) {
108
		/* Trigger the next readahead in advance. */
109
		if (0 == (i % max_ra_count)) {
110
			blk_start_plug(&plug);
111
			for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++)
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				sb_breadahead(sb, sector + j);
113
			blk_finish_plug(&plug);
114
		}
115

116
		sbi->vol_amap[i] = sb_bread(sb, sector + i);
117
		if (!sbi->vol_amap[i])
118
			goto err_out;
119
	}
120

121
	if (exfat_test_bitmap_range(sb, sbi->map_clu,
122
		EXFAT_B_TO_CLU_ROUND_UP(map_size, sbi)) == false)
123
		goto err_out;
124

125
	return 0;
126

127
err_out:
128
	j = 0;
129
	/* release all buffers and free vol_amap */
130
	while (j < i)
131
		brelse(sbi->vol_amap[j++]);
132

133
	kvfree(sbi->vol_amap);
134
	sbi->vol_amap = NULL;
135
	return -EIO;
136
}
137

138
int exfat_load_bitmap(struct super_block *sb)
139
{
140
	unsigned int i, type;
141
	struct exfat_chain clu;
142
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
143

144
	exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
145
	while (clu.dir != EXFAT_EOF_CLUSTER) {
146
		for (i = 0; i < sbi->dentries_per_clu; i++) {
147
			struct exfat_dentry *ep;
148
			struct buffer_head *bh;
149

150
			ep = exfat_get_dentry(sb, &clu, i, &bh);
151
			if (!ep)
152
				return -EIO;
153

154
			type = exfat_get_entry_type(ep);
155
			if (type == TYPE_BITMAP &&
156
			    ep->dentry.bitmap.flags == 0x0) {
157
				int err;
158

159
				err = exfat_allocate_bitmap(sb, ep);
160
				brelse(bh);
161
				return err;
162
			}
163
			brelse(bh);
164

165
			if (type == TYPE_UNUSED)
166
				return -EINVAL;
167
		}
168

169
		if (exfat_get_next_cluster(sb, &clu.dir))
170
			return -EIO;
171
	}
172

173
	return -EINVAL;
174
}
175

176
void exfat_free_bitmap(struct exfat_sb_info *sbi)
177
{
178
	int i;
179

180
	for (i = 0; i < sbi->map_sectors; i++)
181
		__brelse(sbi->vol_amap[i]);
182

183
	kvfree(sbi->vol_amap);
184
}
185

186
int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
187
{
188
	int i, b;
189
	unsigned int ent_idx;
190
	struct super_block *sb = inode->i_sb;
191
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
192

193
	if (!is_valid_cluster(sbi, clu))
194
		return -EINVAL;
195

196
	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
197
	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
198
	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
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200
	set_bit_le(b, sbi->vol_amap[i]->b_data);
201
	exfat_update_bh(sbi->vol_amap[i], sync);
202
	return 0;
203
}
204

205
int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
206
{
207
	int i, b;
208
	unsigned int ent_idx;
209
	struct super_block *sb = inode->i_sb;
210
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
211

212
	if (!is_valid_cluster(sbi, clu))
213
		return -EIO;
214

215
	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
216
	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
217
	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
218

219
	if (!test_bit_le(b, sbi->vol_amap[i]->b_data))
220
		return -EIO;
221

222
	clear_bit_le(b, sbi->vol_amap[i]->b_data);
223

224
	exfat_update_bh(sbi->vol_amap[i], sync);
225

226
	return 0;
227
}
228

229
/*
230
 * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
231
 * the cluster heap.
232
 */
233
unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
234
{
235
	unsigned int i, map_i, map_b, ent_idx;
236
	unsigned int clu_base, clu_free;
237
	unsigned long clu_bits, clu_mask;
238
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
239
	__le_long bitval;
240

241
	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
242
	ent_idx = ALIGN_DOWN(CLUSTER_TO_BITMAP_ENT(clu), BITS_PER_LONG);
243
	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx);
244
	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
245

246
	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
247
	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
248

249
	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
250
	     i += BITS_PER_LONG) {
251
		bitval = *(__le_long *)(sbi->vol_amap[map_i]->b_data + map_b);
252
		if (clu_mask > 0) {
253
			bitval |= cpu_to_lel(clu_mask);
254
			clu_mask = 0;
255
		}
256
		if (lel_to_cpu(bitval) != ULONG_MAX) {
257
			clu_bits = lel_to_cpu(bitval);
258
			clu_free = clu_base + ffz(clu_bits);
259
			if (clu_free < sbi->num_clusters)
260
				return clu_free;
261
		}
262
		clu_base += BITS_PER_LONG;
263
		map_b += sizeof(long);
264

265
		if (map_b >= sb->s_blocksize ||
266
		    clu_base >= sbi->num_clusters) {
267
			if (++map_i >= sbi->map_sectors) {
268
				clu_base = EXFAT_FIRST_CLUSTER;
269
				map_i = 0;
270
			}
271
			map_b = 0;
272
		}
273
	}
274

275
	return EXFAT_EOF_CLUSTER;
276
}
277

278
int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
279
{
280
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
281
	unsigned int count = 0;
282
	unsigned int i, map_i = 0, map_b = 0;
283
	unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
284
	unsigned int last_mask = total_clus & (BITS_PER_LONG - 1);
285
	unsigned long *bitmap, clu_bits;
286

287
	total_clus &= ~last_mask;
288
	for (i = 0; i < total_clus; i += BITS_PER_LONG) {
289
		bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
290
		count += hweight_long(*bitmap);
291
		map_b += sizeof(long);
292
		if (map_b >= (unsigned int)sb->s_blocksize) {
293
			map_i++;
294
			map_b = 0;
295
		}
296
	}
297

298
	if (last_mask) {
299
		bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
300
		clu_bits = lel_to_cpu(*(__le_long *)bitmap);
301
		count += hweight_long(clu_bits & BITMAP_LAST_WORD_MASK(last_mask));
302
	}
303

304
	*ret_count = count;
305
	return 0;
306
}
307

308
int exfat_trim_fs(struct inode *inode, struct fstrim_range *range)
309
{
310
	unsigned int trim_begin, trim_end, count, next_free_clu;
311
	u64 clu_start, clu_end, trim_minlen, trimmed_total = 0;
312
	struct super_block *sb = inode->i_sb;
313
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
314
	int err = 0;
315

316
	clu_start = max_t(u64, range->start >> sbi->cluster_size_bits,
317
				EXFAT_FIRST_CLUSTER);
318
	clu_end = clu_start + (range->len >> sbi->cluster_size_bits) - 1;
319
	trim_minlen = range->minlen >> sbi->cluster_size_bits;
320

321
	if (clu_start >= sbi->num_clusters || range->len < sbi->cluster_size)
322
		return -EINVAL;
323

324
	if (clu_end >= sbi->num_clusters)
325
		clu_end = sbi->num_clusters - 1;
326

327
	mutex_lock(&sbi->bitmap_lock);
328

329
	trim_begin = trim_end = exfat_find_free_bitmap(sb, clu_start);
330
	if (trim_begin == EXFAT_EOF_CLUSTER)
331
		goto unlock;
332

333
	next_free_clu = exfat_find_free_bitmap(sb, trim_end + 1);
334
	if (next_free_clu == EXFAT_EOF_CLUSTER)
335
		goto unlock;
336

337
	do {
338
		if (next_free_clu == trim_end + 1) {
339
			/* extend trim range for continuous free cluster */
340
			trim_end++;
341
		} else {
342
			/* trim current range if it's larger than trim_minlen */
343
			count = trim_end - trim_begin + 1;
344
			if (count >= trim_minlen) {
345
				err = sb_issue_discard(sb,
346
					exfat_cluster_to_sector(sbi, trim_begin),
347
					count * sbi->sect_per_clus, GFP_NOFS, 0);
348
				if (err)
349
					goto unlock;
350

351
				trimmed_total += count;
352
			}
353

354
			/* set next start point of the free hole */
355
			trim_begin = trim_end = next_free_clu;
356
		}
357

358
		if (next_free_clu >= clu_end)
359
			break;
360

361
		if (fatal_signal_pending(current)) {
362
			err = -ERESTARTSYS;
363
			goto unlock;
364
		}
365

366
		next_free_clu = exfat_find_free_bitmap(sb, next_free_clu + 1);
367
	} while (next_free_clu != EXFAT_EOF_CLUSTER &&
368
			next_free_clu > trim_end);
369

370
	/* try to trim remainder */
371
	count = trim_end - trim_begin + 1;
372
	if (count >= trim_minlen) {
373
		err = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, trim_begin),
374
			count * sbi->sect_per_clus, GFP_NOFS, 0);
375
		if (err)
376
			goto unlock;
377

378
		trimmed_total += count;
379
	}
380

381
unlock:
382
	mutex_unlock(&sbi->bitmap_lock);
383
	range->len = trimmed_total << sbi->cluster_size_bits;
384

385
	return err;
386
}
387

388