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/*
* 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;
sb->s_dirt = 1;
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 -2;
mutex_lock(&sbi->alloc_mutex);
mapping = sbi->alloc_file->i_mapping;
pnr = offset / PAGE_CACHE_BITS;
page = read_mapping_page(mapping, pnr, NULL);
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);
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;
sb->s_dirt = 1;
mutex_unlock(&sbi->alloc_mutex);
return 0;
}
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