balloc.c

  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 */
 30static 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
 73static 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 (max_ra_count && 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++)
112				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
127err_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
138int 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
176void 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
186int exfat_set_bitmap(struct super_block *sb, unsigned int clu, bool sync)
187{
188	int i, b;
189	unsigned int ent_idx;
190	struct exfat_sb_info *sbi = EXFAT_SB(sb);
191
192	if (!is_valid_cluster(sbi, clu))
193		return -EINVAL;
194
195	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
196	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
197	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
198
199	set_bit_le(b, sbi->vol_amap[i]->b_data);
200	exfat_update_bh(sbi->vol_amap[i], sync);
201	return 0;
202}
203
204int exfat_clear_bitmap(struct super_block *sb, unsigned int clu, bool sync)
205{
206	int i, b;
207	unsigned int ent_idx;
208	struct exfat_sb_info *sbi = EXFAT_SB(sb);
209
210	if (!is_valid_cluster(sbi, clu))
211		return -EIO;
212
213	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
214	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
215	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
216
217	if (!test_bit_le(b, sbi->vol_amap[i]->b_data))
218		return -EIO;
219
220	clear_bit_le(b, sbi->vol_amap[i]->b_data);
221
222	exfat_update_bh(sbi->vol_amap[i], sync);
223
224	return 0;
225}
226
227bool exfat_test_bitmap(struct super_block *sb, unsigned int clu)
228{
229	int i, b;
230	unsigned int ent_idx;
231	struct exfat_sb_info *sbi = EXFAT_SB(sb);
232
233	if (!sbi->vol_amap)
234		return true;
235
236	if (!is_valid_cluster(sbi, clu))
237		return false;
238
239	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
240	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
241	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
242
243	if (!test_bit_le(b, sbi->vol_amap[i]->b_data))
244		return false;
245
246	return true;
247}
248
249/*
250 * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
251 * the cluster heap.
252 */
253unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
254{
255	unsigned int i, map_i, map_b, ent_idx;
256	unsigned int clu_base, clu_free;
257	unsigned long clu_bits, clu_mask;
258	struct exfat_sb_info *sbi = EXFAT_SB(sb);
259	__le_long bitval;
260
261	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
262	ent_idx = ALIGN_DOWN(CLUSTER_TO_BITMAP_ENT(clu), BITS_PER_LONG);
263	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx);
264	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
265
266	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
267	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
268
269	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
270	     i += BITS_PER_LONG) {
271		bitval = *(__le_long *)(sbi->vol_amap[map_i]->b_data + map_b);
272		if (clu_mask > 0) {
273			bitval |= cpu_to_lel(clu_mask);
274			clu_mask = 0;
275		}
276		if (lel_to_cpu(bitval) != ULONG_MAX) {
277			clu_bits = lel_to_cpu(bitval);
278			clu_free = clu_base + ffz(clu_bits);
279			if (clu_free < sbi->num_clusters)
280				return clu_free;
281		}
282		clu_base += BITS_PER_LONG;
283		map_b += sizeof(long);
284
285		if (map_b >= sb->s_blocksize ||
286		    clu_base >= sbi->num_clusters) {
287			if (++map_i >= sbi->map_sectors) {
288				clu_base = EXFAT_FIRST_CLUSTER;
289				map_i = 0;
290			}
291			map_b = 0;
292		}
293	}
294
295	return EXFAT_EOF_CLUSTER;
296}
297
298int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
299{
300	struct exfat_sb_info *sbi = EXFAT_SB(sb);
301	unsigned int count = 0;
302	unsigned int i, map_i = 0, map_b = 0;
303	unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
304	unsigned int last_mask = total_clus & (BITS_PER_LONG - 1);
305	unsigned long *bitmap, clu_bits;
306
307	total_clus &= ~last_mask;
308	for (i = 0; i < total_clus; i += BITS_PER_LONG) {
309		bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
310		count += hweight_long(*bitmap);
311		map_b += sizeof(long);
312		if (map_b >= (unsigned int)sb->s_blocksize) {
313			map_i++;
314			map_b = 0;
315		}
316	}
317
318	if (last_mask) {
319		bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
320		clu_bits = lel_to_cpu(*(__le_long *)bitmap);
321		count += hweight_long(clu_bits & BITMAP_LAST_WORD_MASK(last_mask));
322	}
323
324	*ret_count = count;
325	return 0;
326}
327
328int exfat_trim_fs(struct inode *inode, struct fstrim_range *range)
329{
330	unsigned int trim_begin, trim_end, count, next_free_clu;
331	u64 clu_start, clu_end, trim_minlen, trimmed_total = 0;
332	struct super_block *sb = inode->i_sb;
333	struct exfat_sb_info *sbi = EXFAT_SB(sb);
334	int err = 0;
335
336	clu_start = max_t(u64, range->start >> sbi->cluster_size_bits,
337				EXFAT_FIRST_CLUSTER);
338	clu_end = clu_start + (range->len >> sbi->cluster_size_bits) - 1;
339	trim_minlen = range->minlen >> sbi->cluster_size_bits;
340
341	if (clu_start >= sbi->num_clusters || range->len < sbi->cluster_size)
342		return -EINVAL;
343
344	if (clu_end >= sbi->num_clusters)
345		clu_end = sbi->num_clusters - 1;
346
347	mutex_lock(&sbi->bitmap_lock);
348
349	trim_begin = trim_end = exfat_find_free_bitmap(sb, clu_start);
350	if (trim_begin == EXFAT_EOF_CLUSTER)
351		goto unlock;
352
353	next_free_clu = exfat_find_free_bitmap(sb, trim_end + 1);
354	if (next_free_clu == EXFAT_EOF_CLUSTER)
355		goto unlock;
356
357	do {
358		if (next_free_clu == trim_end + 1) {
359			/* extend trim range for continuous free cluster */
360			trim_end++;
361		} else {
362			/* trim current range if it's larger than trim_minlen */
363			count = trim_end - trim_begin + 1;
364			if (count >= trim_minlen) {
365				err = sb_issue_discard(sb,
366					exfat_cluster_to_sector(sbi, trim_begin),
367					count * sbi->sect_per_clus, GFP_NOFS, 0);
368				if (err)
369					goto unlock;
370
371				trimmed_total += count;
372			}
373
374			/* set next start point of the free hole */
375			trim_begin = trim_end = next_free_clu;
376		}
377
378		if (next_free_clu >= clu_end)
379			break;
380
381		if (fatal_signal_pending(current)) {
382			err = -ERESTARTSYS;
383			goto unlock;
384		}
385
386		next_free_clu = exfat_find_free_bitmap(sb, next_free_clu + 1);
387	} while (next_free_clu != EXFAT_EOF_CLUSTER &&
388			next_free_clu > trim_end);
389
390	/* try to trim remainder */
391	count = trim_end - trim_begin + 1;
392	if (count >= trim_minlen) {
393		err = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, trim_begin),
394			count * sbi->sect_per_clus, GFP_NOFS, 0);
395		if (err)
396			goto unlock;
397
398		trimmed_total += count;
399	}
400
401unlock:
402	mutex_unlock(&sbi->bitmap_lock);
403	range->len = trimmed_total << sbi->cluster_size_bits;
404
405	return err;
406}