1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
4  */
5 
6 #include <linux/slab.h>
7 #include <asm/unaligned.h>
8 #include <linux/buffer_head.h>
9 #include <linux/blkdev.h>
10 
11 #include "exfat_raw.h"
12 #include "exfat_fs.h"
13 
exfat_mirror_bh(struct super_block * sb,sector_t sec,struct buffer_head * bh)14 static int exfat_mirror_bh(struct super_block *sb, sector_t sec,
15 		struct buffer_head *bh)
16 {
17 	struct buffer_head *c_bh;
18 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
19 	sector_t sec2;
20 	int err = 0;
21 
22 	if (sbi->FAT2_start_sector != sbi->FAT1_start_sector) {
23 		sec2 = sec - sbi->FAT1_start_sector + sbi->FAT2_start_sector;
24 		c_bh = sb_getblk(sb, sec2);
25 		if (!c_bh)
26 			return -ENOMEM;
27 		memcpy(c_bh->b_data, bh->b_data, sb->s_blocksize);
28 		set_buffer_uptodate(c_bh);
29 		mark_buffer_dirty(c_bh);
30 		if (sb->s_flags & SB_SYNCHRONOUS)
31 			err = sync_dirty_buffer(c_bh);
32 		brelse(c_bh);
33 	}
34 
35 	return err;
36 }
37 
__exfat_ent_get(struct super_block * sb,unsigned int loc,unsigned int * content)38 static int __exfat_ent_get(struct super_block *sb, unsigned int loc,
39 		unsigned int *content)
40 {
41 	unsigned int off;
42 	sector_t sec;
43 	struct buffer_head *bh;
44 
45 	sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
46 	off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
47 
48 	bh = sb_bread(sb, sec);
49 	if (!bh)
50 		return -EIO;
51 
52 	*content = le32_to_cpu(*(__le32 *)(&bh->b_data[off]));
53 
54 	/* remap reserved clusters to simplify code */
55 	if (*content > EXFAT_BAD_CLUSTER)
56 		*content = EXFAT_EOF_CLUSTER;
57 
58 	brelse(bh);
59 	return 0;
60 }
61 
exfat_ent_set(struct super_block * sb,unsigned int loc,unsigned int content)62 int exfat_ent_set(struct super_block *sb, unsigned int loc,
63 		unsigned int content)
64 {
65 	unsigned int off;
66 	sector_t sec;
67 	__le32 *fat_entry;
68 	struct buffer_head *bh;
69 
70 	sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
71 	off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
72 
73 	bh = sb_bread(sb, sec);
74 	if (!bh)
75 		return -EIO;
76 
77 	fat_entry = (__le32 *)&(bh->b_data[off]);
78 	*fat_entry = cpu_to_le32(content);
79 	exfat_update_bh(bh, sb->s_flags & SB_SYNCHRONOUS);
80 	exfat_mirror_bh(sb, sec, bh);
81 	brelse(bh);
82 	return 0;
83 }
84 
exfat_ent_get(struct super_block * sb,unsigned int loc,unsigned int * content)85 int exfat_ent_get(struct super_block *sb, unsigned int loc,
86 		unsigned int *content)
87 {
88 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
89 	int err;
90 
91 	if (!is_valid_cluster(sbi, loc)) {
92 		exfat_fs_error(sb, "invalid access to FAT (entry 0x%08x)",
93 			loc);
94 		return -EIO;
95 	}
96 
97 	err = __exfat_ent_get(sb, loc, content);
98 	if (err) {
99 		exfat_fs_error(sb,
100 			"failed to access to FAT (entry 0x%08x, err:%d)",
101 			loc, err);
102 		return err;
103 	}
104 
105 	if (*content == EXFAT_FREE_CLUSTER) {
106 		exfat_fs_error(sb,
107 			"invalid access to FAT free cluster (entry 0x%08x)",
108 			loc);
109 		return -EIO;
110 	}
111 
112 	if (*content == EXFAT_BAD_CLUSTER) {
113 		exfat_fs_error(sb,
114 			"invalid access to FAT bad cluster (entry 0x%08x)",
115 			loc);
116 		return -EIO;
117 	}
118 
119 	if (*content != EXFAT_EOF_CLUSTER && !is_valid_cluster(sbi, *content)) {
120 		exfat_fs_error(sb,
121 			"invalid access to FAT (entry 0x%08x) bogus content (0x%08x)",
122 			loc, *content);
123 		return -EIO;
124 	}
125 
126 	return 0;
127 }
128 
exfat_chain_cont_cluster(struct super_block * sb,unsigned int chain,unsigned int len)129 int exfat_chain_cont_cluster(struct super_block *sb, unsigned int chain,
130 		unsigned int len)
131 {
132 	if (!len)
133 		return 0;
134 
135 	while (len > 1) {
136 		if (exfat_ent_set(sb, chain, chain + 1))
137 			return -EIO;
138 		chain++;
139 		len--;
140 	}
141 
142 	if (exfat_ent_set(sb, chain, EXFAT_EOF_CLUSTER))
143 		return -EIO;
144 	return 0;
145 }
146 
147 /* This function must be called with bitmap_lock held */
__exfat_free_cluster(struct inode * inode,struct exfat_chain * p_chain)148 static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
149 {
150 	struct super_block *sb = inode->i_sb;
151 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
152 	int cur_cmap_i, next_cmap_i;
153 	unsigned int num_clusters = 0;
154 	unsigned int clu;
155 
156 	/* invalid cluster number */
157 	if (p_chain->dir == EXFAT_FREE_CLUSTER ||
158 	    p_chain->dir == EXFAT_EOF_CLUSTER ||
159 	    p_chain->dir < EXFAT_FIRST_CLUSTER)
160 		return 0;
161 
162 	/* no cluster to truncate */
163 	if (p_chain->size == 0)
164 		return 0;
165 
166 	/* check cluster validation */
167 	if (!is_valid_cluster(sbi, p_chain->dir)) {
168 		exfat_err(sb, "invalid start cluster (%u)", p_chain->dir);
169 		return -EIO;
170 	}
171 
172 	clu = p_chain->dir;
173 
174 	cur_cmap_i = next_cmap_i =
175 		BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu));
176 
177 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
178 		unsigned int last_cluster = p_chain->dir + p_chain->size - 1;
179 		do {
180 			bool sync = false;
181 
182 			if (clu < last_cluster)
183 				next_cmap_i =
184 				  BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu+1));
185 
186 			/* flush bitmap only if index would be changed or for last cluster */
187 			if (clu == last_cluster || cur_cmap_i != next_cmap_i) {
188 				sync = true;
189 				cur_cmap_i = next_cmap_i;
190 			}
191 
192 			exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
193 			clu++;
194 			num_clusters++;
195 		} while (num_clusters < p_chain->size);
196 	} else {
197 		do {
198 			bool sync = false;
199 			unsigned int n_clu = clu;
200 			int err = exfat_get_next_cluster(sb, &n_clu);
201 
202 			if (err || n_clu == EXFAT_EOF_CLUSTER)
203 				sync = true;
204 			else
205 				next_cmap_i =
206 				  BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(n_clu));
207 
208 			if (cur_cmap_i != next_cmap_i) {
209 				sync = true;
210 				cur_cmap_i = next_cmap_i;
211 			}
212 
213 			exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
214 			clu = n_clu;
215 			num_clusters++;
216 
217 			if (err)
218 				goto dec_used_clus;
219 		} while (clu != EXFAT_EOF_CLUSTER);
220 	}
221 
222 dec_used_clus:
223 	sbi->used_clusters -= num_clusters;
224 	return 0;
225 }
226 
exfat_free_cluster(struct inode * inode,struct exfat_chain * p_chain)227 int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
228 {
229 	int ret = 0;
230 
231 	mutex_lock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
232 	ret = __exfat_free_cluster(inode, p_chain);
233 	mutex_unlock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
234 
235 	return ret;
236 }
237 
exfat_find_last_cluster(struct super_block * sb,struct exfat_chain * p_chain,unsigned int * ret_clu)238 int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
239 		unsigned int *ret_clu)
240 {
241 	unsigned int clu, next;
242 	unsigned int count = 0;
243 
244 	next = p_chain->dir;
245 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
246 		*ret_clu = next + p_chain->size - 1;
247 		return 0;
248 	}
249 
250 	do {
251 		count++;
252 		clu = next;
253 		if (exfat_ent_get(sb, clu, &next))
254 			return -EIO;
255 	} while (next != EXFAT_EOF_CLUSTER);
256 
257 	if (p_chain->size != count) {
258 		exfat_fs_error(sb,
259 			"bogus directory size (clus : ondisk(%d) != counted(%d))",
260 			p_chain->size, count);
261 		return -EIO;
262 	}
263 
264 	*ret_clu = clu;
265 	return 0;
266 }
267 
exfat_zeroed_cluster(struct inode * dir,unsigned int clu)268 int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
269 {
270 	struct super_block *sb = dir->i_sb;
271 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
272 	struct buffer_head *bh;
273 	sector_t blknr, last_blknr, i;
274 
275 	blknr = exfat_cluster_to_sector(sbi, clu);
276 	last_blknr = blknr + sbi->sect_per_clus;
277 
278 	if (last_blknr > sbi->num_sectors && sbi->num_sectors > 0) {
279 		exfat_fs_error_ratelimit(sb,
280 			"%s: out of range(sect:%llu len:%u)",
281 			__func__, (unsigned long long)blknr,
282 			sbi->sect_per_clus);
283 		return -EIO;
284 	}
285 
286 	/* Zeroing the unused blocks on this cluster */
287 	for (i = blknr; i < last_blknr; i++) {
288 		bh = sb_getblk(sb, i);
289 		if (!bh)
290 			return -ENOMEM;
291 
292 		memset(bh->b_data, 0, sb->s_blocksize);
293 		set_buffer_uptodate(bh);
294 		mark_buffer_dirty(bh);
295 		brelse(bh);
296 	}
297 
298 	if (IS_DIRSYNC(dir))
299 		return sync_blockdev_range(sb->s_bdev,
300 				EXFAT_BLK_TO_B(blknr, sb),
301 				EXFAT_BLK_TO_B(last_blknr, sb) - 1);
302 
303 	return 0;
304 }
305 
exfat_alloc_cluster(struct inode * inode,unsigned int num_alloc,struct exfat_chain * p_chain,bool sync_bmap)306 int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
307 		struct exfat_chain *p_chain, bool sync_bmap)
308 {
309 	int ret = -ENOSPC;
310 	unsigned int num_clusters = 0, total_cnt;
311 	unsigned int hint_clu, new_clu, last_clu = EXFAT_EOF_CLUSTER;
312 	struct super_block *sb = inode->i_sb;
313 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
314 
315 	total_cnt = EXFAT_DATA_CLUSTER_COUNT(sbi);
316 
317 	if (unlikely(total_cnt < sbi->used_clusters)) {
318 		exfat_fs_error_ratelimit(sb,
319 			"%s: invalid used clusters(t:%u,u:%u)\n",
320 			__func__, total_cnt, sbi->used_clusters);
321 		return -EIO;
322 	}
323 
324 	if (num_alloc > total_cnt - sbi->used_clusters)
325 		return -ENOSPC;
326 
327 	mutex_lock(&sbi->bitmap_lock);
328 
329 	hint_clu = p_chain->dir;
330 	/* find new cluster */
331 	if (hint_clu == EXFAT_EOF_CLUSTER) {
332 		if (sbi->clu_srch_ptr < EXFAT_FIRST_CLUSTER) {
333 			exfat_err(sb, "sbi->clu_srch_ptr is invalid (%u)",
334 				  sbi->clu_srch_ptr);
335 			sbi->clu_srch_ptr = EXFAT_FIRST_CLUSTER;
336 		}
337 
338 		hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
339 		if (hint_clu == EXFAT_EOF_CLUSTER) {
340 			ret = -ENOSPC;
341 			goto unlock;
342 		}
343 	}
344 
345 	/* check cluster validation */
346 	if (!is_valid_cluster(sbi, hint_clu)) {
347 		exfat_err(sb, "hint_cluster is invalid (%u)",
348 			hint_clu);
349 		hint_clu = EXFAT_FIRST_CLUSTER;
350 		if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
351 			if (exfat_chain_cont_cluster(sb, p_chain->dir,
352 					num_clusters)) {
353 				ret = -EIO;
354 				goto unlock;
355 			}
356 			p_chain->flags = ALLOC_FAT_CHAIN;
357 		}
358 	}
359 
360 	p_chain->dir = EXFAT_EOF_CLUSTER;
361 
362 	while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
363 	       EXFAT_EOF_CLUSTER) {
364 		if (new_clu != hint_clu &&
365 		    p_chain->flags == ALLOC_NO_FAT_CHAIN) {
366 			if (exfat_chain_cont_cluster(sb, p_chain->dir,
367 					num_clusters)) {
368 				ret = -EIO;
369 				goto free_cluster;
370 			}
371 			p_chain->flags = ALLOC_FAT_CHAIN;
372 		}
373 
374 		/* update allocation bitmap */
375 		if (exfat_set_bitmap(inode, new_clu, sync_bmap)) {
376 			ret = -EIO;
377 			goto free_cluster;
378 		}
379 
380 		num_clusters++;
381 
382 		/* update FAT table */
383 		if (p_chain->flags == ALLOC_FAT_CHAIN) {
384 			if (exfat_ent_set(sb, new_clu, EXFAT_EOF_CLUSTER)) {
385 				ret = -EIO;
386 				goto free_cluster;
387 			}
388 		}
389 
390 		if (p_chain->dir == EXFAT_EOF_CLUSTER) {
391 			p_chain->dir = new_clu;
392 		} else if (p_chain->flags == ALLOC_FAT_CHAIN) {
393 			if (exfat_ent_set(sb, last_clu, new_clu)) {
394 				ret = -EIO;
395 				goto free_cluster;
396 			}
397 		}
398 		last_clu = new_clu;
399 
400 		if (--num_alloc == 0) {
401 			sbi->clu_srch_ptr = hint_clu;
402 			sbi->used_clusters += num_clusters;
403 
404 			p_chain->size += num_clusters;
405 			mutex_unlock(&sbi->bitmap_lock);
406 			return 0;
407 		}
408 
409 		hint_clu = new_clu + 1;
410 		if (hint_clu >= sbi->num_clusters) {
411 			hint_clu = EXFAT_FIRST_CLUSTER;
412 
413 			if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
414 				if (exfat_chain_cont_cluster(sb, p_chain->dir,
415 						num_clusters)) {
416 					ret = -EIO;
417 					goto free_cluster;
418 				}
419 				p_chain->flags = ALLOC_FAT_CHAIN;
420 			}
421 		}
422 	}
423 free_cluster:
424 	if (num_clusters)
425 		__exfat_free_cluster(inode, p_chain);
426 unlock:
427 	mutex_unlock(&sbi->bitmap_lock);
428 	return ret;
429 }
430 
exfat_count_num_clusters(struct super_block * sb,struct exfat_chain * p_chain,unsigned int * ret_count)431 int exfat_count_num_clusters(struct super_block *sb,
432 		struct exfat_chain *p_chain, unsigned int *ret_count)
433 {
434 	unsigned int i, count;
435 	unsigned int clu;
436 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
437 
438 	if (!p_chain->dir || p_chain->dir == EXFAT_EOF_CLUSTER) {
439 		*ret_count = 0;
440 		return 0;
441 	}
442 
443 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
444 		*ret_count = p_chain->size;
445 		return 0;
446 	}
447 
448 	clu = p_chain->dir;
449 	count = 0;
450 	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters; i++) {
451 		count++;
452 		if (exfat_ent_get(sb, clu, &clu))
453 			return -EIO;
454 		if (clu == EXFAT_EOF_CLUSTER)
455 			break;
456 	}
457 
458 	*ret_count = count;
459 	return 0;
460 }
461