aboutsummaryrefslogtreecommitdiff
path: root/fs/hfsplus/bitmap.c
blob: 6feefc0cb48a0cf2fe9a646e9de4d0434ac7cdce (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/*
 *  linux/fs/hfsplus/bitmap.c
 *
 * Copyright (C) 2001
 * Brad Boyer (flar@allandria.com)
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 *
 * Handling of allocation file
 */

#include <linux/pagemap.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

#define PAGE_CACHE_BITS	(PAGE_CACHE_SIZE * 8)

int hfsplus_block_allocate(struct super_block *sb, u32 size,
		u32 offset, u32 *max)
{
	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
	struct page *page;
	struct address_space *mapping;
	__be32 *pptr, *curr, *end;
	u32 mask, start, len, n;
	__be32 val;
	int i;

	len = *max;
	if (!len)
		return size;

	dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
	mutex_lock(&sbi->alloc_mutex);
	mapping = sbi->alloc_file->i_mapping;
	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
	if (IS_ERR(page)) {
		start = size;
		goto out;
	}
	pptr = kmap(page);
	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	i = offset % 32;
	offset &= ~(PAGE_CACHE_BITS - 1);
	if ((size ^ offset) / PAGE_CACHE_BITS)
		end = pptr + PAGE_CACHE_BITS / 32;
	else
		end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;

	/* scan the first partial u32 for zero bits */
	val = *curr;
	if (~val) {
		n = be32_to_cpu(val);
		mask = (1U << 31) >> i;
		for (; i < 32; mask >>= 1, i++) {
			if (!(n & mask))
				goto found;
		}
	}
	curr++;

	/* scan complete u32s for the first zero bit */
	while (1) {
		while (curr < end) {
			val = *curr;
			if (~val) {
				n = be32_to_cpu(val);
				mask = 1 << 31;
				for (i = 0; i < 32; mask >>= 1, i++) {
					if (!(n & mask))
						goto found;
				}
			}
			curr++;
		}
		kunmap(page);
		offset += PAGE_CACHE_BITS;
		if (offset >= size)
			break;
		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
					 NULL);
		if (IS_ERR(page)) {
			start = size;
			goto out;
		}
		curr = pptr = kmap(page);
		if ((size ^ offset) / PAGE_CACHE_BITS)
			end = pptr + PAGE_CACHE_BITS / 32;
		else
			end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	}
	dprint(DBG_BITMAP, "bitmap full\n");
	start = size;
	goto out;

found:
	start = offset + (curr - pptr) * 32 + i;
	if (start >= size) {
		dprint(DBG_BITMAP, "bitmap full\n");
		goto out;
	}
	/* do any partial u32 at the start */
	len = min(size - start, len);
	while (1) {
		n |= mask;
		if (++i >= 32)
			break;
		mask >>= 1;
		if (!--len || n & mask)
			goto done;
	}
	if (!--len)
		goto done;
	*curr++ = cpu_to_be32(n);
	/* do full u32s */
	while (1) {
		while (curr < end) {
			n = be32_to_cpu(*curr);
			if (len < 32)
				goto last;
			if (n) {
				len = 32;
				goto last;
			}
			*curr++ = cpu_to_be32(0xffffffff);
			len -= 32;
		}
		set_page_dirty(page);
		kunmap(page);
		offset += PAGE_CACHE_BITS;
		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
					 NULL);
		if (IS_ERR(page)) {
			start = size;
			goto out;
		}
		pptr = kmap(page);
		curr = pptr;
		end = pptr + PAGE_CACHE_BITS / 32;
	}
last:
	/* do any partial u32 at end */
	mask = 1U << 31;
	for (i = 0; i < len; i++) {
		if (n & mask)
			break;
		n |= mask;
		mask >>= 1;
	}
done:
	*curr = cpu_to_be32(n);
	set_page_dirty(page);
	kunmap(page);
	*max = offset + (curr - pptr) * 32 + i - start;
	sbi->free_blocks -= *max;
	hfsplus_mark_mdb_dirty(sb);
	dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
out:
	mutex_unlock(&sbi->alloc_mutex);
	return start;
}

int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
{
	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
	struct page *page;
	struct address_space *mapping;
	__be32 *pptr, *curr, *end;
	u32 mask, len, pnr;
	int i;

	/* is there any actual work to be done? */
	if (!count)
		return 0;

	dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
	/* are all of the bits in range? */
	if ((offset + count) > sbi->total_blocks)
		return -ENOENT;

	mutex_lock(&sbi->alloc_mutex);
	mapping = sbi->alloc_file->i_mapping;
	pnr = offset / PAGE_CACHE_BITS;
	page = read_mapping_page(mapping, pnr, NULL);
	if (IS_ERR(page))
		goto kaboom;
	pptr = kmap(page);
	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	end = pptr + PAGE_CACHE_BITS / 32;
	len = count;

	/* do any partial u32 at the start */
	i = offset % 32;
	if (i) {
		int j = 32 - i;
		mask = 0xffffffffU << j;
		if (j > count) {
			mask |= 0xffffffffU >> (i + count);
			*curr++ &= cpu_to_be32(mask);
			goto out;
		}
		*curr++ &= cpu_to_be32(mask);
		count -= j;
	}

	/* do full u32s */
	while (1) {
		while (curr < end) {
			if (count < 32)
				goto done;
			*curr++ = 0;
			count -= 32;
		}
		if (!count)
			break;
		set_page_dirty(page);
		kunmap(page);
		page = read_mapping_page(mapping, ++pnr, NULL);
		if (IS_ERR(page))
			goto kaboom;
		pptr = kmap(page);
		curr = pptr;
		end = pptr + PAGE_CACHE_BITS / 32;
	}
done:
	/* do any partial u32 at end */
	if (count) {
		mask = 0xffffffffU >> count;
		*curr &= cpu_to_be32(mask);
	}
out:
	set_page_dirty(page);
	kunmap(page);
	sbi->free_blocks += len;
	hfsplus_mark_mdb_dirty(sb);
	mutex_unlock(&sbi->alloc_mutex);

	return 0;

kaboom:
	printk(KERN_CRIT "hfsplus: unable to mark blocks free: error %ld\n",
			PTR_ERR(page));
	mutex_unlock(&sbi->alloc_mutex);

	return -EIO;
}