ext4: Fix mb_find_next_bit not to return larger than max
authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Fri, 11 Jul 2008 23:27:31 +0000 (19:27 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Fri, 11 Jul 2008 23:27:31 +0000 (19:27 -0400)
commite7dfb2463e3c1b10c38372023e0186d25dec1fa6
tree48e05520ccaf7e0c8a2f5bdfc9851069277a6a79
parentf3b35f063e9a795495fe2f7a2fe55fab11f8ab12
ext4: Fix mb_find_next_bit not to return larger than max

Some architectures implement ext4_find_next_bit and
ext4_find_next_zero_bit in such a way that they return
greater than max for some input values. Make sure
mb_find_next_bit and mb_find_next_zero_bit return the
right values.

On 2.6.25 we have include/asm-x86/bitops_32.h
static inline unsigned find_first_bit(const unsigned long *addr, unsigned size)
{
unsigned x = 0;

while (x < size) {
unsigned long val = *addr++;
if (val)
return __ffs(val) + x;
x += (sizeof(*addr)<<3);
}
return x;
}

This can return value greater than size.

Reported and fixed here for lustre

https://bugzilla.lustre.org/show_bug.cgi?id=15932
https://bugzilla.lustre.org/attachment.cgi?id=17205

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
fs/ext4/mballoc.c