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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - fs/hfsplus/bitmap.c
2 * linux/fs/hfsplus/bitmap.c
5 * Brad Boyer (flar@allandria.com)
6 * (C) 2003 Ardis Technologies <roman@ardistech.com>
8 * Handling of allocation file
11 #include <linux/pagemap.h>
13 #include "hfsplus_fs.h"
14 #include "hfsplus_raw.h"
16 #define PAGE_CACHE_BITS (PAGE_CACHE_SIZE * 8)
18 int hfsplus_block_allocate(struct super_block
*sb
, u32 size
, u32 offset
, u32
*max
)
21 struct address_space
*mapping
;
22 __be32
*pptr
, *curr
, *end
;
23 u32 mask
, start
, len
, n
;
31 dprint(DBG_BITMAP
, "block_allocate: %u,%u,%u\n", size
, offset
, len
);
32 mutex_lock(&HFSPLUS_SB(sb
).alloc_file
->i_mutex
);
33 mapping
= HFSPLUS_SB(sb
).alloc_file
->i_mapping
;
34 page
= read_mapping_page(mapping
, offset
/ PAGE_CACHE_BITS
, NULL
);
40 curr
= pptr
+ (offset
& (PAGE_CACHE_BITS
- 1)) / 32;
42 offset
&= ~(PAGE_CACHE_BITS
- 1);
43 if ((size
^ offset
) / PAGE_CACHE_BITS
)
44 end
= pptr
+ PAGE_CACHE_BITS
/ 32;
46 end
= pptr
+ ((size
+ 31) & (PAGE_CACHE_BITS
- 1)) / 32;
48 /* scan the first partial u32 for zero bits */
52 mask
= (1U << 31) >> i
;
53 for (; i
< 32; mask
>>= 1, i
++) {
60 /* scan complete u32s for the first zero bit */
67 for (i
= 0; i
< 32; mask
>>= 1, i
++) {
75 offset
+= PAGE_CACHE_BITS
;
78 page
= read_mapping_page(mapping
, offset
/ PAGE_CACHE_BITS
,
84 curr
= pptr
= kmap(page
);
85 if ((size
^ offset
) / PAGE_CACHE_BITS
)
86 end
= pptr
+ PAGE_CACHE_BITS
/ 32;
88 end
= pptr
+ ((size
+ 31) & (PAGE_CACHE_BITS
- 1)) / 32;
90 dprint(DBG_BITMAP
, "bitmap full\n");
95 start
= offset
+ (curr
- pptr
) * 32 + i
;
97 dprint(DBG_BITMAP
, "bitmap full\n");
100 /* do any partial u32 at the start */
101 len
= min(size
- start
, len
);
107 if (!--len
|| n
& mask
)
112 *curr
++ = cpu_to_be32(n
);
116 n
= be32_to_cpu(*curr
);
123 *curr
++ = cpu_to_be32(0xffffffff);
126 set_page_dirty(page
);
128 offset
+= PAGE_CACHE_BITS
;
129 page
= read_mapping_page(mapping
, offset
/ PAGE_CACHE_BITS
,
137 end
= pptr
+ PAGE_CACHE_BITS
/ 32;
140 /* do any partial u32 at end */
142 for (i
= 0; i
< len
; i
++) {
149 *curr
= cpu_to_be32(n
);
150 set_page_dirty(page
);
152 *max
= offset
+ (curr
- pptr
) * 32 + i
- start
;
153 HFSPLUS_SB(sb
).free_blocks
-= *max
;
155 dprint(DBG_BITMAP
, "-> %u,%u\n", start
, *max
);
157 mutex_unlock(&HFSPLUS_SB(sb
).alloc_file
->i_mutex
);
161 int hfsplus_block_free(struct super_block
*sb
, u32 offset
, u32 count
)
164 struct address_space
*mapping
;
165 __be32
*pptr
, *curr
, *end
;
169 /* is there any actual work to be done? */
173 dprint(DBG_BITMAP
, "block_free: %u,%u\n", offset
, count
);
174 /* are all of the bits in range? */
175 if ((offset
+ count
) > HFSPLUS_SB(sb
).total_blocks
)
178 mutex_lock(&HFSPLUS_SB(sb
).alloc_file
->i_mutex
);
179 mapping
= HFSPLUS_SB(sb
).alloc_file
->i_mapping
;
180 pnr
= offset
/ PAGE_CACHE_BITS
;
181 page
= read_mapping_page(mapping
, pnr
, NULL
);
183 curr
= pptr
+ (offset
& (PAGE_CACHE_BITS
- 1)) / 32;
184 end
= pptr
+ PAGE_CACHE_BITS
/ 32;
187 /* do any partial u32 at the start */
191 mask
= 0xffffffffU
<< j
;
193 mask
|= 0xffffffffU
>> (i
+ count
);
194 *curr
++ &= cpu_to_be32(mask
);
197 *curr
++ &= cpu_to_be32(mask
);
211 set_page_dirty(page
);
213 page
= read_mapping_page(mapping
, ++pnr
, NULL
);
216 end
= pptr
+ PAGE_CACHE_BITS
/ 32;
219 /* do any partial u32 at end */
221 mask
= 0xffffffffU
>> count
;
222 *curr
&= cpu_to_be32(mask
);
225 set_page_dirty(page
);
227 HFSPLUS_SB(sb
).free_blocks
+= len
;
229 mutex_unlock(&HFSPLUS_SB(sb
).alloc_file
->i_mutex
);