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Commit f96999c3 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

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: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 67f8cf3c

fs/f2fs/segment.c

+49 −57
Original line number Diff line number Diff line
@@ -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;

	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)