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f2fs: refactor __find_rev_next_{zero}_bit 

This patch refactors __find_rev_next_{zero}_bit which was disabled previously
due to bugs.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim 2015-10-20 15:17:19 -07:00
parent 67f8cf3cee
commit f96999c35f
1 changed files with 49 additions and 57 deletions
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106
fs/f2fs/segment.c
View File

@ -29,6 +29,21 @@ static struct kmem_cache *discard_entry_slab;
static struct kmem_cache *sit_entry_set_slab;
static struct kmem_cache *inmem_entry_slab;
static unsigned long __reverse_ulong(unsigned char *str)
{
unsigned long tmp = 0;
int shift = 24, idx = 0;
#if BITS_PER_LONG == 64
shift = 56;
#endif
while (shift >= 0) {
tmp |= (unsigned long)str[idx++] << shift;
shift -= BITS_PER_BYTE;
}
return tmp;
}
/*
* __reverse_ffs is copied from include/asm-generic/bitops/__ffs.h since
* MSB and LSB are reversed in a byte by f2fs_set_bit.
@ -38,27 +53,31 @@ static inline unsigned long __reverse_ffs(unsigned long word)
int num = 0;
#if BITS_PER_LONG == 64
if ((word & 0xffffffff) == 0) {
if ((word & 0xffffffff00000000UL) == 0)
num += 32;
else
word >>= 32;
}
#endif
if ((word & 0xffff) == 0) {
if ((word & 0xffff0000) == 0)
num += 16;
else
word >>= 16;
}
if ((word & 0xff) == 0) {
if ((word & 0xff00) == 0)
num += 8;
else
word >>= 8;
}
if ((word & 0xf0) == 0)
num += 4;
else
word >>= 4;
if ((word & 0xc) == 0)
num += 2;
else
word >>= 2;
if ((word & 0x2) == 0)
num += 1;
return num;
@ -68,26 +87,16 @@ static inline unsigned long __reverse_ffs(unsigned long word)
* __find_rev_next(_zero)_bit is copied from lib/find_next_bit.c because
* f2fs_set_bit makes MSB and LSB reversed in a byte.
* Example:
* LSB <--> MSB
* f2fs_set_bit(0, bitmap) => 0000 0001
* f2fs_set_bit(7, bitmap) => 1000 0000
* MSB <--> LSB
* f2fs_set_bit(0, bitmap) => 1000 0000
* f2fs_set_bit(7, bitmap) => 0000 0001
*/
static unsigned long __find_rev_next_bit(const unsigned long *addr,
unsigned long size, unsigned long offset)
{
while (!f2fs_test_bit(offset, (unsigned char *)addr))
offset++;
if (offset > size)
offset = size;
return offset;
#if 0
const unsigned long *p = addr + BIT_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG - 1);
unsigned long tmp;
unsigned long mask, submask;
unsigned long quot, rest;
if (offset >= size)
return size;
@ -97,14 +106,9 @@ static unsigned long __find_rev_next_bit(const unsigned long *addr,
if (!offset)
goto aligned;
tmp = *(p++);
quot = (offset >> 3) << 3;
rest = offset & 0x7;
mask = ~0UL << quot;
submask = (unsigned char)(0xff << rest) >> rest;
submask <<= quot;
mask &= submask;
tmp &= mask;
tmp = __reverse_ulong((unsigned char *)p);
tmp &= ~0UL >> offset;
if (size < BITS_PER_LONG)
goto found_first;
if (tmp)
@ -112,42 +116,34 @@ static unsigned long __find_rev_next_bit(const unsigned long *addr,
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
p++;
aligned:
while (size & ~(BITS_PER_LONG-1)) {
tmp = *(p++);
tmp = __reverse_ulong((unsigned char *)p);
if (tmp)
goto found_middle;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
p++;
}
if (!size)
return result;
tmp = *p;
tmp = __reverse_ulong((unsigned char *)p);
found_first:
tmp &= (~0UL >> (BITS_PER_LONG - size));
if (tmp == 0UL) /* Are any bits set? */
tmp &= (~0UL << (BITS_PER_LONG - size));
if (!tmp) /* Are any bits set? */
return result + size; /* Nope. */
found_middle:
return result + __reverse_ffs(tmp);
#endif
}
static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
unsigned long size, unsigned long offset)
{
while (f2fs_test_bit(offset, (unsigned char *)addr))
offset++;
if (offset > size)
offset = size;
return offset;
#if 0
const unsigned long *p = addr + BIT_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG - 1);
unsigned long tmp;
unsigned long mask, submask;
unsigned long quot, rest;
if (offset >= size)
return size;
@ -157,40 +153,36 @@ static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
if (!offset)
goto aligned;
tmp = *(p++);
quot = (offset >> 3) << 3;
rest = offset & 0x7;
mask = ~(~0UL << quot);
submask = (unsigned char)~((unsigned char)(0xff << rest) >> rest);
submask <<= quot;
mask += submask;
tmp |= mask;
tmp = __reverse_ulong((unsigned char *)p);
tmp |= ~((~0UL << offset) >> offset);
if (size < BITS_PER_LONG)
goto found_first;
if (~tmp)
if (tmp != ~0UL)
goto found_middle;
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
p++;
aligned:
while (size & ~(BITS_PER_LONG - 1)) {
tmp = *(p++);
if (~tmp)
tmp = __reverse_ulong((unsigned char *)p);
if (tmp != ~0UL)
goto found_middle;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
p++;
}
if (!size)
return result;
tmp = *p;
tmp = __reverse_ulong((unsigned char *)p);
found_first:
tmp |= ~0UL << size;
if (tmp == ~0UL) /* Are any bits zero? */
tmp |= ~(~0UL << (BITS_PER_LONG - size));
if (tmp == ~0UL) /* Are any bits zero? */
return result + size; /* Nope. */
found_middle:
return result + __reverse_ffz(tmp);
#endif
}
void register_inmem_page(struct inode *inode, struct page *page)