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/buffer_head.h>
9 
10 #include "exfat_raw.h"
11 #include "exfat_fs.h"
12 
13 static const unsigned char free_bit[] = {
14 	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*  0 ~  19*/
15 	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/* 20 ~  39*/
16 	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/* 40 ~  59*/
17 	0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/* 60 ~  79*/
18 	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/* 80 ~  99*/
19 	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3,/*100 ~ 119*/
20 	0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*120 ~ 139*/
21 	0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5,/*140 ~ 159*/
22 	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*160 ~ 179*/
23 	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3,/*180 ~ 199*/
24 	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*200 ~ 219*/
25 	0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*220 ~ 239*/
26 	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0                /*240 ~ 254*/
27 };
28 
29 static const unsigned char used_bit[] = {
30 	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3,/*  0 ~  19*/
31 	2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/* 20 ~  39*/
32 	2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/* 40 ~  59*/
33 	4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/* 60 ~  79*/
34 	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/* 80 ~  99*/
35 	3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,/*100 ~ 119*/
36 	4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4,/*120 ~ 139*/
37 	3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,/*140 ~ 159*/
38 	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,/*160 ~ 179*/
39 	4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5,/*180 ~ 199*/
40 	3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6,/*200 ~ 219*/
41 	5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,/*220 ~ 239*/
42 	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8             /*240 ~ 255*/
43 };
44 
45 /*
46  *  Allocation Bitmap Management Functions
47  */
exfat_allocate_bitmap(struct super_block * sb,struct exfat_dentry * ep)48 static int exfat_allocate_bitmap(struct super_block *sb,
49 		struct exfat_dentry *ep)
50 {
51 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
52 	long long map_size;
53 	unsigned int i, need_map_size;
54 	sector_t sector;
55 
56 	sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
57 	map_size = le64_to_cpu(ep->dentry.bitmap.size);
58 	need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)
59 		+ 1;
60 	if (need_map_size != map_size) {
61 		exfat_err(sb, "bogus allocation bitmap size(need : %u, cur : %lld)",
62 			  need_map_size, map_size);
63 		/*
64 		 * Only allowed when bogus allocation
65 		 * bitmap size is large
66 		 */
67 		if (need_map_size > map_size)
68 			return -EIO;
69 	}
70 	sbi->map_sectors = ((need_map_size - 1) >>
71 			(sb->s_blocksize_bits)) + 1;
72 	sbi->vol_amap = kvmalloc_array(sbi->map_sectors,
73 				sizeof(struct buffer_head *), GFP_KERNEL);
74 	if (!sbi->vol_amap)
75 		return -ENOMEM;
76 
77 	sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
78 	for (i = 0; i < sbi->map_sectors; i++) {
79 		sbi->vol_amap[i] = sb_bread(sb, sector + i);
80 		if (!sbi->vol_amap[i]) {
81 			/* release all buffers and free vol_amap */
82 			int j = 0;
83 
84 			while (j < i)
85 				brelse(sbi->vol_amap[j++]);
86 
87 			kvfree(sbi->vol_amap);
88 			sbi->vol_amap = NULL;
89 			return -EIO;
90 		}
91 	}
92 
93 	return 0;
94 }
95 
exfat_load_bitmap(struct super_block * sb)96 int exfat_load_bitmap(struct super_block *sb)
97 {
98 	unsigned int i, type;
99 	struct exfat_chain clu;
100 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
101 
102 	exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
103 	while (clu.dir != EXFAT_EOF_CLUSTER) {
104 		for (i = 0; i < sbi->dentries_per_clu; i++) {
105 			struct exfat_dentry *ep;
106 			struct buffer_head *bh;
107 
108 			ep = exfat_get_dentry(sb, &clu, i, &bh);
109 			if (!ep)
110 				return -EIO;
111 
112 			type = exfat_get_entry_type(ep);
113 			if (type == TYPE_UNUSED)
114 				break;
115 			if (type != TYPE_BITMAP)
116 				continue;
117 			if (ep->dentry.bitmap.flags == 0x0) {
118 				int err;
119 
120 				err = exfat_allocate_bitmap(sb, ep);
121 				brelse(bh);
122 				return err;
123 			}
124 			brelse(bh);
125 		}
126 
127 		if (exfat_get_next_cluster(sb, &clu.dir))
128 			return -EIO;
129 	}
130 
131 	return -EINVAL;
132 }
133 
exfat_free_bitmap(struct exfat_sb_info * sbi)134 void exfat_free_bitmap(struct exfat_sb_info *sbi)
135 {
136 	int i;
137 
138 	for (i = 0; i < sbi->map_sectors; i++)
139 		__brelse(sbi->vol_amap[i]);
140 
141 	kvfree(sbi->vol_amap);
142 }
143 
exfat_set_bitmap(struct inode * inode,unsigned int clu,bool sync)144 int exfat_set_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 
151 	if (!is_valid_cluster(sbi, clu))
152 		return -EINVAL;
153 
154 	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
155 	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
156 	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
157 
158 	set_bit_le(b, sbi->vol_amap[i]->b_data);
159 	exfat_update_bh(sbi->vol_amap[i], sync);
160 	return 0;
161 }
162 
exfat_clear_bitmap(struct inode * inode,unsigned int clu,bool sync)163 void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
164 {
165 	int i, b;
166 	unsigned int ent_idx;
167 	struct super_block *sb = inode->i_sb;
168 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
169 	struct exfat_mount_options *opts = &sbi->options;
170 
171 	if (!is_valid_cluster(sbi, clu))
172 		return;
173 
174 	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
175 	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
176 	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
177 
178 	clear_bit_le(b, sbi->vol_amap[i]->b_data);
179 	exfat_update_bh(sbi->vol_amap[i], sync);
180 
181 	if (opts->discard) {
182 		int ret_discard;
183 
184 		ret_discard = sb_issue_discard(sb,
185 			exfat_cluster_to_sector(sbi, clu),
186 			(1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
187 
188 		if (ret_discard == -EOPNOTSUPP) {
189 			exfat_err(sb, "discard not supported by device, disabling");
190 			opts->discard = 0;
191 		}
192 	}
193 }
194 
195 /*
196  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
197  * the cluster heap.
198  */
exfat_find_free_bitmap(struct super_block * sb,unsigned int clu)199 unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
200 {
201 	unsigned int i, map_i, map_b, ent_idx;
202 	unsigned int clu_base, clu_free;
203 	unsigned char k, clu_mask;
204 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
205 
206 	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
207 	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
208 	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));
209 	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
210 
211 	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
212 	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
213 
214 	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
215 	     i += BITS_PER_BYTE) {
216 		k = *(sbi->vol_amap[map_i]->b_data + map_b);
217 		if (clu_mask > 0) {
218 			k |= clu_mask;
219 			clu_mask = 0;
220 		}
221 		if (k < 0xFF) {
222 			clu_free = clu_base + free_bit[k];
223 			if (clu_free < sbi->num_clusters)
224 				return clu_free;
225 		}
226 		clu_base += BITS_PER_BYTE;
227 
228 		if (++map_b >= sb->s_blocksize ||
229 		    clu_base >= sbi->num_clusters) {
230 			if (++map_i >= sbi->map_sectors) {
231 				clu_base = EXFAT_FIRST_CLUSTER;
232 				map_i = 0;
233 			}
234 			map_b = 0;
235 		}
236 	}
237 
238 	return EXFAT_EOF_CLUSTER;
239 }
240 
exfat_count_used_clusters(struct super_block * sb,unsigned int * ret_count)241 int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
242 {
243 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
244 	unsigned int count = 0;
245 	unsigned int i, map_i = 0, map_b = 0;
246 	unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
247 	unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
248 	unsigned char clu_bits;
249 	const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
250 		0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
251 
252 	total_clus &= ~last_mask;
253 	for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
254 		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
255 		count += used_bit[clu_bits];
256 		if (++map_b >= (unsigned int)sb->s_blocksize) {
257 			map_i++;
258 			map_b = 0;
259 		}
260 	}
261 
262 	if (last_mask) {
263 		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
264 		clu_bits &= last_bit_mask[last_mask];
265 		count += used_bit[clu_bits];
266 	}
267 
268 	*ret_count = count;
269 	return 0;
270 }
271 
exfat_trim_fs(struct inode * inode,struct fstrim_range * range)272 int exfat_trim_fs(struct inode *inode, struct fstrim_range *range)
273 {
274 	unsigned int trim_begin, trim_end, count, next_free_clu;
275 	u64 clu_start, clu_end, trim_minlen, trimmed_total = 0;
276 	struct super_block *sb = inode->i_sb;
277 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
278 	int err = 0;
279 
280 	clu_start = max_t(u64, range->start >> sbi->cluster_size_bits,
281 				EXFAT_FIRST_CLUSTER);
282 	clu_end = clu_start + (range->len >> sbi->cluster_size_bits) - 1;
283 	trim_minlen = range->minlen >> sbi->cluster_size_bits;
284 
285 	if (clu_start >= sbi->num_clusters || range->len < sbi->cluster_size)
286 		return -EINVAL;
287 
288 	if (clu_end >= sbi->num_clusters)
289 		clu_end = sbi->num_clusters - 1;
290 
291 	mutex_lock(&sbi->bitmap_lock);
292 
293 	trim_begin = trim_end = exfat_find_free_bitmap(sb, clu_start);
294 	if (trim_begin == EXFAT_EOF_CLUSTER)
295 		goto unlock;
296 
297 	next_free_clu = exfat_find_free_bitmap(sb, trim_end + 1);
298 	if (next_free_clu == EXFAT_EOF_CLUSTER)
299 		goto unlock;
300 
301 	do {
302 		if (next_free_clu == trim_end + 1) {
303 			/* extend trim range for continuous free cluster */
304 			trim_end++;
305 		} else {
306 			/* trim current range if it's larger than trim_minlen */
307 			count = trim_end - trim_begin + 1;
308 			if (count >= trim_minlen) {
309 				err = sb_issue_discard(sb,
310 					exfat_cluster_to_sector(sbi, trim_begin),
311 					count * sbi->sect_per_clus, GFP_NOFS, 0);
312 				if (err)
313 					goto unlock;
314 
315 				trimmed_total += count;
316 			}
317 
318 			/* set next start point of the free hole */
319 			trim_begin = trim_end = next_free_clu;
320 		}
321 
322 		if (next_free_clu >= clu_end)
323 			break;
324 
325 		if (fatal_signal_pending(current)) {
326 			err = -ERESTARTSYS;
327 			goto unlock;
328 		}
329 
330 		next_free_clu = exfat_find_free_bitmap(sb, next_free_clu + 1);
331 	} while (next_free_clu != EXFAT_EOF_CLUSTER &&
332 			next_free_clu > trim_end);
333 
334 	/* try to trim remainder */
335 	count = trim_end - trim_begin + 1;
336 	if (count >= trim_minlen) {
337 		err = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, trim_begin),
338 			count * sbi->sect_per_clus, GFP_NOFS, 0);
339 		if (err)
340 			goto unlock;
341 
342 		trimmed_total += count;
343 	}
344 
345 unlock:
346 	mutex_unlock(&sbi->bitmap_lock);
347 	range->len = trimmed_total << sbi->cluster_size_bits;
348 
349 	return err;
350 }
351