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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 | { | |
20 | struct page *page; | |
21 | struct address_space *mapping; | |
22 | __be32 *pptr, *curr, *end; | |
23 | u32 mask, start, len, n; | |
24 | __be32 val; | |
25 | int i; | |
26 | ||
27 | len = *max; | |
28 | if (!len) | |
29 | return size; | |
30 | ||
31 | dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len); | |
32 | down(&HFSPLUS_SB(sb).alloc_file->i_sem); | |
33 | mapping = HFSPLUS_SB(sb).alloc_file->i_mapping; | |
34 | page = read_cache_page(mapping, offset / PAGE_CACHE_BITS, | |
35 | (filler_t *)mapping->a_ops->readpage, NULL); | |
36 | pptr = kmap(page); | |
37 | curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; | |
38 | i = offset % 32; | |
39 | offset &= ~(PAGE_CACHE_BITS - 1); | |
40 | if ((size ^ offset) / PAGE_CACHE_BITS) | |
41 | end = pptr + PAGE_CACHE_BITS / 32; | |
42 | else | |
43 | end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; | |
44 | ||
45 | /* scan the first partial u32 for zero bits */ | |
46 | val = *curr; | |
47 | if (~val) { | |
48 | n = be32_to_cpu(val); | |
49 | mask = (1U << 31) >> i; | |
50 | for (; i < 32; mask >>= 1, i++) { | |
51 | if (!(n & mask)) | |
52 | goto found; | |
53 | } | |
54 | } | |
55 | curr++; | |
56 | ||
57 | /* scan complete u32s for the first zero bit */ | |
58 | while (1) { | |
59 | while (curr < end) { | |
60 | val = *curr; | |
61 | if (~val) { | |
62 | n = be32_to_cpu(val); | |
63 | mask = 1 << 31; | |
64 | for (i = 0; i < 32; mask >>= 1, i++) { | |
65 | if (!(n & mask)) | |
66 | goto found; | |
67 | } | |
68 | } | |
69 | curr++; | |
70 | } | |
71 | kunmap(page); | |
72 | offset += PAGE_CACHE_BITS; | |
73 | if (offset >= size) | |
74 | break; | |
75 | page = read_cache_page(mapping, offset / PAGE_CACHE_BITS, | |
76 | (filler_t *)mapping->a_ops->readpage, NULL); | |
77 | curr = pptr = kmap(page); | |
78 | if ((size ^ offset) / PAGE_CACHE_BITS) | |
79 | end = pptr + PAGE_CACHE_BITS / 32; | |
80 | else | |
81 | end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; | |
82 | } | |
83 | dprint(DBG_BITMAP, "bitmap full\n"); | |
84 | start = size; | |
85 | goto out; | |
86 | ||
87 | found: | |
88 | start = offset + (curr - pptr) * 32 + i; | |
89 | if (start >= size) { | |
90 | dprint(DBG_BITMAP, "bitmap full\n"); | |
91 | goto out; | |
92 | } | |
93 | /* do any partial u32 at the start */ | |
94 | len = min(size - start, len); | |
95 | while (1) { | |
96 | n |= mask; | |
97 | if (++i >= 32) | |
98 | break; | |
99 | mask >>= 1; | |
100 | if (!--len || n & mask) | |
101 | goto done; | |
102 | } | |
103 | if (!--len) | |
104 | goto done; | |
105 | *curr++ = cpu_to_be32(n); | |
106 | /* do full u32s */ | |
107 | while (1) { | |
108 | while (curr < end) { | |
109 | n = be32_to_cpu(*curr); | |
110 | if (len < 32) | |
111 | goto last; | |
112 | if (n) { | |
113 | len = 32; | |
114 | goto last; | |
115 | } | |
116 | *curr++ = cpu_to_be32(0xffffffff); | |
117 | len -= 32; | |
118 | } | |
119 | set_page_dirty(page); | |
120 | kunmap(page); | |
121 | offset += PAGE_CACHE_BITS; | |
122 | page = read_cache_page(mapping, offset / PAGE_CACHE_BITS, | |
123 | (filler_t *)mapping->a_ops->readpage, NULL); | |
124 | pptr = kmap(page); | |
125 | curr = pptr; | |
126 | end = pptr + PAGE_CACHE_BITS / 32; | |
127 | } | |
128 | last: | |
129 | /* do any partial u32 at end */ | |
130 | mask = 1U << 31; | |
131 | for (i = 0; i < len; i++) { | |
132 | if (n & mask) | |
133 | break; | |
134 | n |= mask; | |
135 | mask >>= 1; | |
136 | } | |
137 | done: | |
138 | *curr = cpu_to_be32(n); | |
139 | set_page_dirty(page); | |
140 | kunmap(page); | |
141 | *max = offset + (curr - pptr) * 32 + i - start; | |
142 | HFSPLUS_SB(sb).free_blocks -= *max; | |
143 | sb->s_dirt = 1; | |
144 | dprint(DBG_BITMAP, "-> %u,%u\n", start, *max); | |
145 | out: | |
146 | up(&HFSPLUS_SB(sb).alloc_file->i_sem); | |
147 | return start; | |
148 | } | |
149 | ||
150 | int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count) | |
151 | { | |
152 | struct page *page; | |
153 | struct address_space *mapping; | |
154 | __be32 *pptr, *curr, *end; | |
155 | u32 mask, len, pnr; | |
156 | int i; | |
157 | ||
158 | /* is there any actual work to be done? */ | |
159 | if (!count) | |
160 | return 0; | |
161 | ||
162 | dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count); | |
163 | /* are all of the bits in range? */ | |
164 | if ((offset + count) > HFSPLUS_SB(sb).total_blocks) | |
165 | return -2; | |
166 | ||
167 | down(&HFSPLUS_SB(sb).alloc_file->i_sem); | |
168 | mapping = HFSPLUS_SB(sb).alloc_file->i_mapping; | |
169 | pnr = offset / PAGE_CACHE_BITS; | |
170 | page = read_cache_page(mapping, pnr, (filler_t *)mapping->a_ops->readpage, NULL); | |
171 | pptr = kmap(page); | |
172 | curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; | |
173 | end = pptr + PAGE_CACHE_BITS / 32; | |
174 | len = count; | |
175 | ||
176 | /* do any partial u32 at the start */ | |
177 | i = offset % 32; | |
178 | if (i) { | |
179 | int j = 32 - i; | |
180 | mask = 0xffffffffU << j; | |
181 | if (j > count) { | |
182 | mask |= 0xffffffffU >> (i + count); | |
183 | *curr++ &= cpu_to_be32(mask); | |
184 | goto out; | |
185 | } | |
186 | *curr++ &= cpu_to_be32(mask); | |
187 | count -= j; | |
188 | } | |
189 | ||
190 | /* do full u32s */ | |
191 | while (1) { | |
192 | while (curr < end) { | |
193 | if (count < 32) | |
194 | goto done; | |
195 | *curr++ = 0; | |
196 | count -= 32; | |
197 | } | |
198 | if (!count) | |
199 | break; | |
200 | set_page_dirty(page); | |
201 | kunmap(page); | |
202 | page = read_cache_page(mapping, ++pnr, (filler_t *)mapping->a_ops->readpage, NULL); | |
203 | pptr = kmap(page); | |
204 | curr = pptr; | |
205 | end = pptr + PAGE_CACHE_BITS / 32; | |
206 | } | |
207 | done: | |
208 | /* do any partial u32 at end */ | |
209 | if (count) { | |
210 | mask = 0xffffffffU >> count; | |
211 | *curr &= cpu_to_be32(mask); | |
212 | } | |
213 | out: | |
214 | set_page_dirty(page); | |
215 | kunmap(page); | |
216 | HFSPLUS_SB(sb).free_blocks += len; | |
217 | sb->s_dirt = 1; | |
218 | up(&HFSPLUS_SB(sb).alloc_file->i_sem); | |
219 | ||
220 | return 0; | |
221 | } |