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
11#include "exfat_raw.h"
12#include "exfat_fs.h"
13
14#if BITS_PER_LONG == 32
15#define __le_long __le32
16#define lel_to_cpu(A) le32_to_cpu(A)
17#define cpu_to_lel(A) cpu_to_le32(A)
18#elif BITS_PER_LONG == 64
19#define __le_long __le64
20#define lel_to_cpu(A) le64_to_cpu(A)
21#define cpu_to_lel(A) cpu_to_le64(A)
22#else
23#error "BITS_PER_LONG not 32 or 64"
24#endif
25
26/*
27 *  Allocation Bitmap Management Functions
28 */
29static int exfat_allocate_bitmap(struct super_block *sb,
30		struct exfat_dentry *ep)
31{
32	struct exfat_sb_info *sbi = EXFAT_SB(sb);
33	long long map_size;
34	unsigned int i, need_map_size;
35	sector_t sector;
36
37	sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
38	map_size = le64_to_cpu(ep->dentry.bitmap.size);
39	need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)
40		+ 1;
41	if (need_map_size != map_size) {
42		exfat_err(sb, "bogus allocation bitmap size(need : %u, cur : %lld)",
43			  need_map_size, map_size);
44		/*
45		 * Only allowed when bogus allocation
46		 * bitmap size is large
47		 */
48		if (need_map_size > map_size)
49			return -EIO;
50	}
51	sbi->map_sectors = ((need_map_size - 1) >>
52			(sb->s_blocksize_bits)) + 1;
53	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
54				sizeof(struct buffer_head *), GFP_KERNEL);
55	if (!sbi->vol_amap)
56		return -ENOMEM;
57
58	sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
59	for (i = 0; i < sbi->map_sectors; i++) {
60		sbi->vol_amap[i] = sb_bread(sb, sector + i);
61		if (!sbi->vol_amap[i]) {
62			/* release all buffers and free vol_amap */
63			int j = 0;
64
65			while (j < i)
66				brelse(sbi->vol_amap[j++]);
67
68			kvfree(sbi->vol_amap);
69			sbi->vol_amap = NULL;
70			return -EIO;
71		}
72	}
73
74	return 0;
75}
76
77int exfat_load_bitmap(struct super_block *sb)
78{
79	unsigned int i, type;
80	struct exfat_chain clu;
81	struct exfat_sb_info *sbi = EXFAT_SB(sb);
82
83	exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
84	while (clu.dir != EXFAT_EOF_CLUSTER) {
85		for (i = 0; i < sbi->dentries_per_clu; i++) {
86			struct exfat_dentry *ep;
87			struct buffer_head *bh;
88
89			ep = exfat_get_dentry(sb, &clu, i, &bh);
90			if (!ep)
91				return -EIO;
92
93			type = exfat_get_entry_type(ep);
94			if (type == TYPE_UNUSED)
95				break;
96			if (type != TYPE_BITMAP)
97				continue;
98			if (ep->dentry.bitmap.flags == 0x0) {
99				int err;
100
101				err = exfat_allocate_bitmap(sb, ep);
102				brelse(bh);
103				return err;
104			}
105			brelse(bh);
106		}
107
108		if (exfat_get_next_cluster(sb, &clu.dir))
109			return -EIO;
110	}
111
112	return -EINVAL;
113}
114
115void exfat_free_bitmap(struct exfat_sb_info *sbi)
116{
117	int i;
118
119	for (i = 0; i < sbi->map_sectors; i++)
120		__brelse(sbi->vol_amap[i]);
121
122	kvfree(sbi->vol_amap);
123}
124
125int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
126{
127	int i, b;
128	unsigned int ent_idx;
129	struct super_block *sb = inode->i_sb;
130	struct exfat_sb_info *sbi = EXFAT_SB(sb);
131
132	if (!is_valid_cluster(sbi, clu))
133		return -EINVAL;
134
135	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
136	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
137	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
138
139	set_bit_le(b, sbi->vol_amap[i]->b_data);
140	exfat_update_bh(sbi->vol_amap[i], sync);
141	return 0;
142}
143
144void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
145{
146	int i, b;
147	unsigned int ent_idx;
148	struct super_block *sb = inode->i_sb;
149	struct exfat_sb_info *sbi = EXFAT_SB(sb);
150	struct exfat_mount_options *opts = &sbi->options;
151
152	if (!is_valid_cluster(sbi, clu))
153		return;
154
155	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
156	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
157	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
158
159	clear_bit_le(b, sbi->vol_amap[i]->b_data);
160	exfat_update_bh(sbi->vol_amap[i], sync);
161
162	if (opts->discard) {
163		int ret_discard;
164
165		ret_discard = sb_issue_discard(sb,
166			exfat_cluster_to_sector(sbi, clu),
167			(1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
168
169		if (ret_discard == -EOPNOTSUPP) {
170			exfat_err(sb, "discard not supported by device, disabling");
171			opts->discard = 0;
172		}
173	}
174}
175
176/*
177 * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
178 * the cluster heap.
179 */
180unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
181{
182	unsigned int i, map_i, map_b, ent_idx;
183	unsigned int clu_base, clu_free;
184	unsigned long clu_bits, clu_mask;
185	struct exfat_sb_info *sbi = EXFAT_SB(sb);
186	__le_long bitval;
187
188	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
189	ent_idx = ALIGN_DOWN(CLUSTER_TO_BITMAP_ENT(clu), BITS_PER_LONG);
190	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx);
191	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
192
193	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
194	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
195
196	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
197	     i += BITS_PER_LONG) {
198		bitval = *(__le_long *)(sbi->vol_amap[map_i]->b_data + map_b);
199		if (clu_mask > 0) {
200			bitval |= cpu_to_lel(clu_mask);
201			clu_mask = 0;
202		}
203		if (lel_to_cpu(bitval) != ULONG_MAX) {
204			clu_bits = lel_to_cpu(bitval);
205			clu_free = clu_base + ffz(clu_bits);
206			if (clu_free < sbi->num_clusters)
207				return clu_free;
208		}
209		clu_base += BITS_PER_LONG;
210		map_b += sizeof(long);
211
212		if (map_b >= sb->s_blocksize ||
213		    clu_base >= sbi->num_clusters) {
214			if (++map_i >= sbi->map_sectors) {
215				clu_base = EXFAT_FIRST_CLUSTER;
216				map_i = 0;
217			}
218			map_b = 0;
219		}
220	}
221
222	return EXFAT_EOF_CLUSTER;
223}
224
225int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
226{
227	struct exfat_sb_info *sbi = EXFAT_SB(sb);
228	unsigned int count = 0;
229	unsigned int i, map_i = 0, map_b = 0;
230	unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
231	unsigned int last_mask = total_clus & (BITS_PER_LONG - 1);
232	unsigned long *bitmap, clu_bits;
233
234	total_clus &= ~last_mask;
235	for (i = 0; i < total_clus; i += BITS_PER_LONG) {
236		bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
237		count += hweight_long(*bitmap);
238		map_b += sizeof(long);
239		if (map_b >= (unsigned int)sb->s_blocksize) {
240			map_i++;
241			map_b = 0;
242		}
243	}
244
245	if (last_mask) {
246		bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
247		clu_bits = lel_to_cpu(*(__le_long *)bitmap);
248		count += hweight_long(clu_bits & BITMAP_LAST_WORD_MASK(last_mask));
249	}
250
251	*ret_count = count;
252	return 0;
253}
254
255int exfat_trim_fs(struct inode *inode, struct fstrim_range *range)
256{
257	unsigned int trim_begin, trim_end, count, next_free_clu;
258	u64 clu_start, clu_end, trim_minlen, trimmed_total = 0;
259	struct super_block *sb = inode->i_sb;
260	struct exfat_sb_info *sbi = EXFAT_SB(sb);
261	int err = 0;
262
263	clu_start = max_t(u64, range->start >> sbi->cluster_size_bits,
264				EXFAT_FIRST_CLUSTER);
265	clu_end = clu_start + (range->len >> sbi->cluster_size_bits) - 1;
266	trim_minlen = range->minlen >> sbi->cluster_size_bits;
267
268	if (clu_start >= sbi->num_clusters || range->len < sbi->cluster_size)
269		return -EINVAL;
270
271	if (clu_end >= sbi->num_clusters)
272		clu_end = sbi->num_clusters - 1;
273
274	mutex_lock(&sbi->bitmap_lock);
275
276	trim_begin = trim_end = exfat_find_free_bitmap(sb, clu_start);
277	if (trim_begin == EXFAT_EOF_CLUSTER)
278		goto unlock;
279
280	next_free_clu = exfat_find_free_bitmap(sb, trim_end + 1);
281	if (next_free_clu == EXFAT_EOF_CLUSTER)
282		goto unlock;
283
284	do {
285		if (next_free_clu == trim_end + 1) {
286			/* extend trim range for continuous free cluster */
287			trim_end++;
288		} else {
289			/* trim current range if it's larger than trim_minlen */
290			count = trim_end - trim_begin + 1;
291			if (count >= trim_minlen) {
292				err = sb_issue_discard(sb,
293					exfat_cluster_to_sector(sbi, trim_begin),
294					count * sbi->sect_per_clus, GFP_NOFS, 0);
295				if (err)
296					goto unlock;
297
298				trimmed_total += count;
299			}
300
301			/* set next start point of the free hole */
302			trim_begin = trim_end = next_free_clu;
303		}
304
305		if (next_free_clu >= clu_end)
306			break;
307
308		if (fatal_signal_pending(current)) {
309			err = -ERESTARTSYS;
310			goto unlock;
311		}
312
313		next_free_clu = exfat_find_free_bitmap(sb, next_free_clu + 1);
314	} while (next_free_clu != EXFAT_EOF_CLUSTER &&
315			next_free_clu > trim_end);
316
317	/* try to trim remainder */
318	count = trim_end - trim_begin + 1;
319	if (count >= trim_minlen) {
320		err = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, trim_begin),
321			count * sbi->sect_per_clus, GFP_NOFS, 0);
322		if (err)
323			goto unlock;
324
325		trimmed_total += count;
326	}
327
328unlock:
329	mutex_unlock(&sbi->bitmap_lock);
330	range->len = trimmed_total << sbi->cluster_size_bits;
331
332	return err;
333}
334