xref: /linux/fs/exfat/fatent.c (revision f0712c203862b00139b34fcbb1710b479af2b101)
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 <linux/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_ratelimit(sb,
93 			"invalid access to FAT (entry 0x%08x)",
94 			loc);
95 		return -EIO;
96 	}
97 
98 	err = __exfat_ent_get(sb, loc, content);
99 	if (err) {
100 		exfat_fs_error_ratelimit(sb,
101 			"failed to access to FAT (entry 0x%08x, err:%d)",
102 			loc, err);
103 		return err;
104 	}
105 
106 	if (*content == EXFAT_FREE_CLUSTER) {
107 		exfat_fs_error_ratelimit(sb,
108 			"invalid access to FAT free cluster (entry 0x%08x)",
109 			loc);
110 		return -EIO;
111 	}
112 
113 	if (*content == EXFAT_BAD_CLUSTER) {
114 		exfat_fs_error_ratelimit(sb,
115 			"invalid access to FAT bad cluster (entry 0x%08x)",
116 			loc);
117 		return -EIO;
118 	}
119 
120 	if (*content != EXFAT_EOF_CLUSTER && !is_valid_cluster(sbi, *content)) {
121 		exfat_fs_error_ratelimit(sb,
122 			"invalid access to FAT (entry 0x%08x) bogus content (0x%08x)",
123 			loc, *content);
124 		return -EIO;
125 	}
126 
127 	return 0;
128 }
129 
exfat_chain_cont_cluster(struct super_block * sb,unsigned int chain,unsigned int len)130 int exfat_chain_cont_cluster(struct super_block *sb, unsigned int chain,
131 		unsigned int len)
132 {
133 	if (!len)
134 		return 0;
135 
136 	while (len > 1) {
137 		if (exfat_ent_set(sb, chain, chain + 1))
138 			return -EIO;
139 		chain++;
140 		len--;
141 	}
142 
143 	if (exfat_ent_set(sb, chain, EXFAT_EOF_CLUSTER))
144 		return -EIO;
145 	return 0;
146 }
147 
exfat_discard_cluster(struct super_block * sb,unsigned int clu,unsigned int num_clusters)148 static inline void exfat_discard_cluster(struct super_block *sb,
149 		unsigned int clu, unsigned int num_clusters)
150 {
151 	int ret;
152 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
153 
154 	ret = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, clu),
155 			sbi->sect_per_clus * num_clusters, GFP_NOFS, 0);
156 	if (ret == -EOPNOTSUPP) {
157 		exfat_err(sb, "discard not supported by device, disabling");
158 		sbi->options.discard = 0;
159 	}
160 }
161 
162 /* This function must be called with bitmap_lock held */
__exfat_free_cluster(struct inode * inode,struct exfat_chain * p_chain)163 static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
164 {
165 	struct super_block *sb = inode->i_sb;
166 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
167 	int cur_cmap_i, next_cmap_i;
168 	unsigned int num_clusters = 0;
169 	unsigned int clu;
170 
171 	/* invalid cluster number */
172 	if (p_chain->dir == EXFAT_FREE_CLUSTER ||
173 	    p_chain->dir == EXFAT_EOF_CLUSTER ||
174 	    p_chain->dir < EXFAT_FIRST_CLUSTER)
175 		return 0;
176 
177 	/* no cluster to truncate */
178 	if (p_chain->size == 0)
179 		return 0;
180 
181 	/* check cluster validation */
182 	if (!is_valid_cluster(sbi, p_chain->dir)) {
183 		exfat_err(sb, "invalid start cluster (%u)", p_chain->dir);
184 		return -EIO;
185 	}
186 
187 	clu = p_chain->dir;
188 
189 	cur_cmap_i = next_cmap_i =
190 		BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu));
191 
192 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
193 		int err;
194 		unsigned int last_cluster = p_chain->dir + p_chain->size - 1;
195 		do {
196 			bool sync = false;
197 
198 			if (clu < last_cluster)
199 				next_cmap_i =
200 				  BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu+1));
201 
202 			/* flush bitmap only if index would be changed or for last cluster */
203 			if (clu == last_cluster || cur_cmap_i != next_cmap_i) {
204 				sync = true;
205 				cur_cmap_i = next_cmap_i;
206 			}
207 
208 			err = exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
209 			if (err)
210 				break;
211 			clu++;
212 			num_clusters++;
213 		} while (num_clusters < p_chain->size);
214 
215 		if (sbi->options.discard)
216 			exfat_discard_cluster(sb, p_chain->dir, p_chain->size);
217 	} else {
218 		unsigned int nr_clu = 1;
219 
220 		do {
221 			bool sync = false;
222 			unsigned int n_clu = clu;
223 			int err = exfat_get_next_cluster(sb, &n_clu);
224 
225 			if (err || n_clu == EXFAT_EOF_CLUSTER)
226 				sync = true;
227 			else
228 				next_cmap_i =
229 				  BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(n_clu));
230 
231 			if (cur_cmap_i != next_cmap_i) {
232 				sync = true;
233 				cur_cmap_i = next_cmap_i;
234 			}
235 
236 			if (exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode))))
237 				break;
238 
239 			if (sbi->options.discard) {
240 				if (n_clu == clu + 1)
241 					nr_clu++;
242 				else {
243 					exfat_discard_cluster(sb, clu - nr_clu + 1, nr_clu);
244 					nr_clu = 1;
245 				}
246 			}
247 
248 			clu = n_clu;
249 			num_clusters++;
250 
251 			if (err)
252 				break;
253 
254 			if (num_clusters >= sbi->num_clusters - EXFAT_FIRST_CLUSTER) {
255 				/*
256 				 * The cluster chain includes a loop, scan the
257 				 * bitmap to get the number of used clusters.
258 				 */
259 				exfat_count_used_clusters(sb, &sbi->used_clusters);
260 
261 				return 0;
262 			}
263 		} while (clu != EXFAT_EOF_CLUSTER);
264 	}
265 
266 	sbi->used_clusters -= num_clusters;
267 	return 0;
268 }
269 
exfat_free_cluster(struct inode * inode,struct exfat_chain * p_chain)270 int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
271 {
272 	int ret = 0;
273 
274 	mutex_lock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
275 	ret = __exfat_free_cluster(inode, p_chain);
276 	mutex_unlock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
277 
278 	return ret;
279 }
280 
exfat_find_last_cluster(struct super_block * sb,struct exfat_chain * p_chain,unsigned int * ret_clu)281 int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
282 		unsigned int *ret_clu)
283 {
284 	unsigned int clu, next;
285 	unsigned int count = 0;
286 
287 	next = p_chain->dir;
288 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
289 		*ret_clu = next + p_chain->size - 1;
290 		return 0;
291 	}
292 
293 	do {
294 		count++;
295 		clu = next;
296 		if (exfat_ent_get(sb, clu, &next))
297 			return -EIO;
298 	} while (next != EXFAT_EOF_CLUSTER && count <= p_chain->size);
299 
300 	if (p_chain->size != count) {
301 		exfat_fs_error(sb,
302 			"bogus directory size (clus : ondisk(%d) != counted(%d))",
303 			p_chain->size, count);
304 		return -EIO;
305 	}
306 
307 	*ret_clu = clu;
308 	return 0;
309 }
310 
exfat_zeroed_cluster(struct inode * dir,unsigned int clu)311 int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
312 {
313 	struct super_block *sb = dir->i_sb;
314 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
315 	struct buffer_head *bh;
316 	sector_t blknr, last_blknr, i;
317 
318 	blknr = exfat_cluster_to_sector(sbi, clu);
319 	last_blknr = blknr + sbi->sect_per_clus;
320 
321 	if (last_blknr > sbi->num_sectors && sbi->num_sectors > 0) {
322 		exfat_fs_error_ratelimit(sb,
323 			"%s: out of range(sect:%llu len:%u)",
324 			__func__, (unsigned long long)blknr,
325 			sbi->sect_per_clus);
326 		return -EIO;
327 	}
328 
329 	/* Zeroing the unused blocks on this cluster */
330 	for (i = blknr; i < last_blknr; i++) {
331 		bh = sb_getblk(sb, i);
332 		if (!bh)
333 			return -ENOMEM;
334 
335 		memset(bh->b_data, 0, sb->s_blocksize);
336 		set_buffer_uptodate(bh);
337 		mark_buffer_dirty(bh);
338 		brelse(bh);
339 	}
340 
341 	if (IS_DIRSYNC(dir))
342 		return sync_blockdev_range(sb->s_bdev,
343 				EXFAT_BLK_TO_B(blknr, sb),
344 				EXFAT_BLK_TO_B(last_blknr, sb) - 1);
345 
346 	return 0;
347 }
348 
exfat_alloc_cluster(struct inode * inode,unsigned int num_alloc,struct exfat_chain * p_chain,bool sync_bmap)349 int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
350 		struct exfat_chain *p_chain, bool sync_bmap)
351 {
352 	int ret = -ENOSPC;
353 	unsigned int total_cnt;
354 	unsigned int hint_clu, new_clu, last_clu = EXFAT_EOF_CLUSTER;
355 	struct super_block *sb = inode->i_sb;
356 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
357 
358 	total_cnt = EXFAT_DATA_CLUSTER_COUNT(sbi);
359 
360 	if (unlikely(total_cnt < sbi->used_clusters)) {
361 		exfat_fs_error_ratelimit(sb,
362 			"%s: invalid used clusters(t:%u,u:%u)\n",
363 			__func__, total_cnt, sbi->used_clusters);
364 		return -EIO;
365 	}
366 
367 	if (num_alloc > total_cnt - sbi->used_clusters)
368 		return -ENOSPC;
369 
370 	mutex_lock(&sbi->bitmap_lock);
371 
372 	hint_clu = p_chain->dir;
373 	/* find new cluster */
374 	if (hint_clu == EXFAT_EOF_CLUSTER) {
375 		if (sbi->clu_srch_ptr < EXFAT_FIRST_CLUSTER) {
376 			exfat_err(sb, "sbi->clu_srch_ptr is invalid (%u)",
377 				  sbi->clu_srch_ptr);
378 			sbi->clu_srch_ptr = EXFAT_FIRST_CLUSTER;
379 		}
380 
381 		hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
382 		if (hint_clu == EXFAT_EOF_CLUSTER) {
383 			ret = -ENOSPC;
384 			goto unlock;
385 		}
386 	}
387 
388 	/* check cluster validation */
389 	if (!is_valid_cluster(sbi, hint_clu)) {
390 		if (hint_clu != sbi->num_clusters)
391 			exfat_err(sb, "hint_cluster is invalid (%u), rewind to the first cluster",
392 					hint_clu);
393 		hint_clu = EXFAT_FIRST_CLUSTER;
394 		p_chain->flags = ALLOC_FAT_CHAIN;
395 	}
396 
397 	p_chain->dir = EXFAT_EOF_CLUSTER;
398 
399 	while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
400 	       EXFAT_EOF_CLUSTER) {
401 		if (new_clu != hint_clu &&
402 		    p_chain->flags == ALLOC_NO_FAT_CHAIN) {
403 			if (exfat_chain_cont_cluster(sb, p_chain->dir,
404 					p_chain->size)) {
405 				ret = -EIO;
406 				goto free_cluster;
407 			}
408 			p_chain->flags = ALLOC_FAT_CHAIN;
409 		}
410 
411 		/* update allocation bitmap */
412 		if (exfat_set_bitmap(inode, new_clu, sync_bmap)) {
413 			ret = -EIO;
414 			goto free_cluster;
415 		}
416 
417 		/* update FAT table */
418 		if (p_chain->flags == ALLOC_FAT_CHAIN) {
419 			if (exfat_ent_set(sb, new_clu, EXFAT_EOF_CLUSTER)) {
420 				ret = -EIO;
421 				goto free_cluster;
422 			}
423 		}
424 
425 		if (p_chain->dir == EXFAT_EOF_CLUSTER) {
426 			p_chain->dir = new_clu;
427 		} else if (p_chain->flags == ALLOC_FAT_CHAIN) {
428 			if (exfat_ent_set(sb, last_clu, new_clu)) {
429 				ret = -EIO;
430 				goto free_cluster;
431 			}
432 		}
433 		p_chain->size++;
434 
435 		last_clu = new_clu;
436 
437 		if (p_chain->size == num_alloc) {
438 			sbi->clu_srch_ptr = hint_clu;
439 			sbi->used_clusters += num_alloc;
440 
441 			mutex_unlock(&sbi->bitmap_lock);
442 			return 0;
443 		}
444 
445 		hint_clu = new_clu + 1;
446 		if (hint_clu >= sbi->num_clusters) {
447 			hint_clu = EXFAT_FIRST_CLUSTER;
448 
449 			if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
450 				if (exfat_chain_cont_cluster(sb, p_chain->dir,
451 						p_chain->size)) {
452 					ret = -EIO;
453 					goto free_cluster;
454 				}
455 				p_chain->flags = ALLOC_FAT_CHAIN;
456 			}
457 		}
458 	}
459 free_cluster:
460 	__exfat_free_cluster(inode, p_chain);
461 unlock:
462 	mutex_unlock(&sbi->bitmap_lock);
463 	return ret;
464 }
465 
exfat_count_num_clusters(struct super_block * sb,struct exfat_chain * p_chain,unsigned int * ret_count)466 int exfat_count_num_clusters(struct super_block *sb,
467 		struct exfat_chain *p_chain, unsigned int *ret_count)
468 {
469 	unsigned int i, count;
470 	unsigned int clu;
471 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
472 
473 	if (!p_chain->dir || p_chain->dir == EXFAT_EOF_CLUSTER) {
474 		*ret_count = 0;
475 		return 0;
476 	}
477 
478 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
479 		*ret_count = p_chain->size;
480 		return 0;
481 	}
482 
483 	clu = p_chain->dir;
484 	count = 0;
485 	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters; i++) {
486 		count++;
487 		if (exfat_ent_get(sb, clu, &clu))
488 			return -EIO;
489 		if (clu == EXFAT_EOF_CLUSTER)
490 			break;
491 	}
492 
493 	*ret_count = count;
494 
495 	/*
496 	 * since exfat_count_used_clusters() is not called, sbi->used_clusters
497 	 * cannot be used here.
498 	 */
499 	if (unlikely(i == sbi->num_clusters && clu != EXFAT_EOF_CLUSTER)) {
500 		exfat_fs_error(sb, "The cluster chain has a loop");
501 		return -EIO;
502 	}
503 
504 	return 0;
505 }
506