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ext4: Add ext4_find_next_bit()

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This function is used by the ext4 multi block allocator patches.

Also add generic_find_next_le_bit

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Aneesh Kumar K.V 2008-01-28 23:58:27 -05:00 • committed by Theodore Ts'o
parent c549a95d40
commit aa02ad67d9
9 changed files with 62 additions and 0 deletions
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43
lib/find_next_bit.c
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@ -178,4 +178,47 @@ found_middle_swap:
EXPORT_SYMBOL(generic_find_next_zero_le_bit);
unsigned long generic_find_next_le_bit(const unsigned long *addr, unsigned
long size, unsigned long offset)
{
const unsigned long *p = addr + BITOP_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG - 1);
unsigned long tmp;
if (offset >= size)
return size;
size -= result;
offset &= (BITS_PER_LONG - 1UL);
if (offset) {
tmp = ext2_swabp(p++);
tmp &= (~0UL << offset);
if (size < BITS_PER_LONG)
goto found_first;
if (tmp)
goto found_middle;
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG - 1)) {
tmp = *(p++);
if (tmp)
goto found_middle_swap;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size)
return result;
tmp = ext2_swabp(p);
found_first:
tmp &= (~0UL >> (BITS_PER_LONG - size));
if (tmp == 0UL) /* Are any bits set? */
return result + size; /* Nope. */
found_middle:
return result + __ffs(tmp);
found_middle_swap:
return result + __ffs(ext2_swab(tmp));
}
EXPORT_SYMBOL(generic_find_next_le_bit);
#endif /* __BIG_ENDIAN */