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btrfs-progs: Replace homegrown bitops related functions with kernel counterparts 

Replace existing find_*_bit functions with kernel equivalent. This
reduces duplication, simplifies the code (we really have one worker
function _find_next_bit) and is quite likely faster. No functional
changes.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Nikolay Borisov 2018-10-01 17:46:14 +03:00 committed by David Sterba
parent b1a1b89029
commit aa3088632a
1 changed files with 46 additions and 96 deletions
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142
kernel-lib/bitops.h
View File

@ -2,6 +2,7 @@
#define _PERF_LINUX_BITOPS_H_
#include <linux/kernel.h>
#include "internal.h"
#ifndef DIV_ROUND_UP
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
@ -109,116 +110,65 @@ static __always_inline unsigned long __ffs(unsigned long word)
#define ffz(x) __ffs(~(x))
#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
/*
* Find the first set bit in a memory region.
* This is a common helper function for find_next_bit, find_next_zero_bit, and
* find_next_and_bit. The differences are:
* - The "invert" argument, which is XORed with each fetched word before
* searching it for one bits.
* - The optional "addr2", which is anded with "addr1" if present.
*/
static inline unsigned long
find_first_bit(const unsigned long *addr, unsigned long size)
static inline unsigned long _find_next_bit(const unsigned long *addr1,
const unsigned long *addr2, unsigned long nbits,
unsigned long start, unsigned long invert)
{
const unsigned long *p = addr;
unsigned long result = 0;
unsigned long tmp;
while (size & ~(BITS_PER_LONG-1)) {
if ((tmp = *(p++)))
goto found;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size)
return result;
if (start >= nbits)
return nbits;
tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
if (tmp == 0UL) /* Are any bits set? */
return result + size; /* Nope. */
found:
return result + __ffs(tmp);
tmp = addr1[start / BITS_PER_LONG];
if (addr2)
tmp &= addr2[start / BITS_PER_LONG];
tmp ^= invert;
/* Handle 1st word. */
tmp &= BITMAP_FIRST_WORD_MASK(start);
start = round_down(start, BITS_PER_LONG);
while (!tmp) {
start += BITS_PER_LONG;
if (start >= nbits)
return nbits;
tmp = addr1[start / BITS_PER_LONG];
if (addr2)
tmp &= addr2[start / BITS_PER_LONG];
tmp ^= invert;
}
return min(start + __ffs(tmp), nbits);
}
/*
* Find the next set bit in a memory region.
*/
static inline unsigned long
find_next_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
static inline unsigned long find_next_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;
if (offset) {
tmp = *(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)) {
if ((tmp = *(p++)))
goto found_middle;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size)
return result;
tmp = *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);
return _find_next_bit(addr, NULL, size, offset, 0UL);
}
/*
* This implementation of find_{first,next}_zero_bit was stolen from
* Linus' asm-alpha/bitops.h.
*/
static inline unsigned long
find_next_zero_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
static inline unsigned long find_next_zero_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;
if (offset) {
tmp = *(p++);
tmp |= ~0UL >> (BITS_PER_LONG - 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)) {
if (~(tmp = *(p++)))
goto found_middle;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size)
return result;
tmp = *p;
found_first:
tmp |= ~0UL << size;
if (tmp == ~0UL) /* Are any bits zero? */
return result + size; /* Nope. */
found_middle:
return result + ffz(tmp);
return _find_next_bit(addr, NULL, size, offset, ~0UL);
}
#define find_first_bit(addr, size) find_next_bit((addr), (size), 0)
#endif