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1da177e4 LT |
1 | /* |
2 | * linux/fs/hfsplus/bitmap.c | |
3 | * | |
4 | * Copyright (C) 2001 | |
5 | * Brad Boyer (flar@allandria.com) | |
6 | * (C) 2003 Ardis Technologies <roman@ardistech.com> | |
7 | * | |
8 | * Handling of allocation file | |
9 | */ | |
10 | ||
11 | #include <linux/pagemap.h> | |
12 | ||
13 | #include "hfsplus_fs.h" | |
14 | #include "hfsplus_raw.h" | |
15 | ||
16 | #define PAGE_CACHE_BITS (PAGE_CACHE_SIZE * 8) | |
17 | ||
18 | int hfsplus_block_allocate(struct super_block *sb, u32 size, u32 offset, u32 *max) | |
19 | { | |
dd73a01a | 20 | struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
1da177e4 LT |
21 | struct page *page; |
22 | struct address_space *mapping; | |
23 | __be32 *pptr, *curr, *end; | |
24 | u32 mask, start, len, n; | |
25 | __be32 val; | |
26 | int i; | |
27 | ||
28 | len = *max; | |
29 | if (!len) | |
30 | return size; | |
31 | ||
32 | dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len); | |
dd73a01a CH |
33 | mutex_lock(&sbi->alloc_mutex); |
34 | mapping = sbi->alloc_file->i_mapping; | |
090d2b18 | 35 | page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL); |
649f1ee6 ES |
36 | if (IS_ERR(page)) { |
37 | start = size; | |
38 | goto out; | |
39 | } | |
1da177e4 LT |
40 | pptr = kmap(page); |
41 | curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; | |
42 | i = offset % 32; | |
43 | offset &= ~(PAGE_CACHE_BITS - 1); | |
44 | if ((size ^ offset) / PAGE_CACHE_BITS) | |
45 | end = pptr + PAGE_CACHE_BITS / 32; | |
46 | else | |
47 | end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; | |
48 | ||
49 | /* scan the first partial u32 for zero bits */ | |
50 | val = *curr; | |
51 | if (~val) { | |
52 | n = be32_to_cpu(val); | |
53 | mask = (1U << 31) >> i; | |
54 | for (; i < 32; mask >>= 1, i++) { | |
55 | if (!(n & mask)) | |
56 | goto found; | |
57 | } | |
58 | } | |
59 | curr++; | |
60 | ||
61 | /* scan complete u32s for the first zero bit */ | |
62 | while (1) { | |
63 | while (curr < end) { | |
64 | val = *curr; | |
65 | if (~val) { | |
66 | n = be32_to_cpu(val); | |
67 | mask = 1 << 31; | |
68 | for (i = 0; i < 32; mask >>= 1, i++) { | |
69 | if (!(n & mask)) | |
70 | goto found; | |
71 | } | |
72 | } | |
73 | curr++; | |
74 | } | |
75 | kunmap(page); | |
76 | offset += PAGE_CACHE_BITS; | |
77 | if (offset >= size) | |
78 | break; | |
090d2b18 PE |
79 | page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, |
80 | NULL); | |
649f1ee6 ES |
81 | if (IS_ERR(page)) { |
82 | start = size; | |
83 | goto out; | |
84 | } | |
1da177e4 LT |
85 | curr = pptr = kmap(page); |
86 | if ((size ^ offset) / PAGE_CACHE_BITS) | |
87 | end = pptr + PAGE_CACHE_BITS / 32; | |
88 | else | |
89 | end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; | |
90 | } | |
91 | dprint(DBG_BITMAP, "bitmap full\n"); | |
92 | start = size; | |
93 | goto out; | |
94 | ||
95 | found: | |
96 | start = offset + (curr - pptr) * 32 + i; | |
97 | if (start >= size) { | |
98 | dprint(DBG_BITMAP, "bitmap full\n"); | |
99 | goto out; | |
100 | } | |
101 | /* do any partial u32 at the start */ | |
102 | len = min(size - start, len); | |
103 | while (1) { | |
104 | n |= mask; | |
105 | if (++i >= 32) | |
106 | break; | |
107 | mask >>= 1; | |
108 | if (!--len || n & mask) | |
109 | goto done; | |
110 | } | |
111 | if (!--len) | |
112 | goto done; | |
113 | *curr++ = cpu_to_be32(n); | |
114 | /* do full u32s */ | |
115 | while (1) { | |
116 | while (curr < end) { | |
117 | n = be32_to_cpu(*curr); | |
118 | if (len < 32) | |
119 | goto last; | |
120 | if (n) { | |
121 | len = 32; | |
122 | goto last; | |
123 | } | |
124 | *curr++ = cpu_to_be32(0xffffffff); | |
125 | len -= 32; | |
126 | } | |
127 | set_page_dirty(page); | |
128 | kunmap(page); | |
129 | offset += PAGE_CACHE_BITS; | |
090d2b18 PE |
130 | page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, |
131 | NULL); | |
649f1ee6 ES |
132 | if (IS_ERR(page)) { |
133 | start = size; | |
134 | goto out; | |
135 | } | |
1da177e4 LT |
136 | pptr = kmap(page); |
137 | curr = pptr; | |
138 | end = pptr + PAGE_CACHE_BITS / 32; | |
139 | } | |
140 | last: | |
141 | /* do any partial u32 at end */ | |
142 | mask = 1U << 31; | |
143 | for (i = 0; i < len; i++) { | |
144 | if (n & mask) | |
145 | break; | |
146 | n |= mask; | |
147 | mask >>= 1; | |
148 | } | |
149 | done: | |
150 | *curr = cpu_to_be32(n); | |
151 | set_page_dirty(page); | |
152 | kunmap(page); | |
153 | *max = offset + (curr - pptr) * 32 + i - start; | |
dd73a01a | 154 | sbi->free_blocks -= *max; |
1da177e4 LT |
155 | sb->s_dirt = 1; |
156 | dprint(DBG_BITMAP, "-> %u,%u\n", start, *max); | |
157 | out: | |
dd73a01a | 158 | mutex_unlock(&sbi->alloc_mutex); |
1da177e4 LT |
159 | return start; |
160 | } | |
161 | ||
162 | int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count) | |
163 | { | |
dd73a01a | 164 | struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
1da177e4 LT |
165 | struct page *page; |
166 | struct address_space *mapping; | |
167 | __be32 *pptr, *curr, *end; | |
168 | u32 mask, len, pnr; | |
169 | int i; | |
170 | ||
171 | /* is there any actual work to be done? */ | |
172 | if (!count) | |
173 | return 0; | |
174 | ||
175 | dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count); | |
176 | /* are all of the bits in range? */ | |
dd73a01a | 177 | if ((offset + count) > sbi->total_blocks) |
1da177e4 LT |
178 | return -2; |
179 | ||
dd73a01a CH |
180 | mutex_lock(&sbi->alloc_mutex); |
181 | mapping = sbi->alloc_file->i_mapping; | |
1da177e4 | 182 | pnr = offset / PAGE_CACHE_BITS; |
090d2b18 | 183 | page = read_mapping_page(mapping, pnr, NULL); |
1da177e4 LT |
184 | pptr = kmap(page); |
185 | curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; | |
186 | end = pptr + PAGE_CACHE_BITS / 32; | |
187 | len = count; | |
188 | ||
189 | /* do any partial u32 at the start */ | |
190 | i = offset % 32; | |
191 | if (i) { | |
192 | int j = 32 - i; | |
193 | mask = 0xffffffffU << j; | |
194 | if (j > count) { | |
195 | mask |= 0xffffffffU >> (i + count); | |
196 | *curr++ &= cpu_to_be32(mask); | |
197 | goto out; | |
198 | } | |
199 | *curr++ &= cpu_to_be32(mask); | |
200 | count -= j; | |
201 | } | |
202 | ||
203 | /* do full u32s */ | |
204 | while (1) { | |
205 | while (curr < end) { | |
206 | if (count < 32) | |
207 | goto done; | |
208 | *curr++ = 0; | |
209 | count -= 32; | |
210 | } | |
211 | if (!count) | |
212 | break; | |
213 | set_page_dirty(page); | |
214 | kunmap(page); | |
090d2b18 | 215 | page = read_mapping_page(mapping, ++pnr, NULL); |
1da177e4 LT |
216 | pptr = kmap(page); |
217 | curr = pptr; | |
218 | end = pptr + PAGE_CACHE_BITS / 32; | |
219 | } | |
220 | done: | |
221 | /* do any partial u32 at end */ | |
222 | if (count) { | |
223 | mask = 0xffffffffU >> count; | |
224 | *curr &= cpu_to_be32(mask); | |
225 | } | |
226 | out: | |
227 | set_page_dirty(page); | |
228 | kunmap(page); | |
dd73a01a | 229 | sbi->free_blocks += len; |
1da177e4 | 230 | sb->s_dirt = 1; |
dd73a01a | 231 | mutex_unlock(&sbi->alloc_mutex); |
1da177e4 LT |
232 | |
233 | return 0; | |
234 | } |