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f2fs: enhance the bit operation for SSR

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This patch enhances the existing bit operation when f2fs allocates SSR
blocks.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim 2015-12-04 16:51:13 -08:00
parent 0cab80ee0c
commit 80609448cd
1 changed files with 18 additions and 28 deletions
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46
fs/f2fs/segment.c
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@ -132,47 +132,37 @@ static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
unsigned long size, unsigned long offset) unsigned long size, unsigned long offset)
{ {
const unsigned long *p = addr + BIT_WORD(offset); const unsigned long *p = addr + BIT_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG - 1); unsigned long result = size;
unsigned long tmp; unsigned long tmp;
if (offset >= size) if (offset >= size)
return size; return size;
size -= result; size -= (offset & ~(BITS_PER_LONG - 1));
offset %= BITS_PER_LONG; offset %= BITS_PER_LONG;
if (!offset)
goto aligned;
tmp = __reverse_ulong((unsigned char *)p); while (1) {
tmp |= ~((~0UL << offset) >> offset); if (*p == ~0UL)
goto pass;
if (size < BITS_PER_LONG)
goto found_first;
if (tmp != ~0UL)
goto found_middle;
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
p++;
aligned:
while (size & ~(BITS_PER_LONG - 1)) {
tmp = __reverse_ulong((unsigned char *)p); tmp = __reverse_ulong((unsigned char *)p);
if (offset)
tmp |= ~0UL << (BITS_PER_LONG - offset);
if (size < BITS_PER_LONG)
tmp |= ~0UL >> size;
if (tmp != ~0UL) if (tmp != ~0UL)
goto found_middle; goto found;
result += BITS_PER_LONG; pass:
if (size <= BITS_PER_LONG)
break;
size -= BITS_PER_LONG; size -= BITS_PER_LONG;
offset = 0;
p++; p++;
} }
if (!size) return result;
return result; found:
return result - size + __reverse_ffz(tmp);
tmp = __reverse_ulong((unsigned char *)p);
found_first:
tmp |= ~(~0UL << (BITS_PER_LONG - size));
if (tmp == ~0UL) /* Are any bits zero? */
return result + size; /* Nope. */
found_middle:
return result + __reverse_ffz(tmp);
} }
void register_inmem_page(struct inode *inode, struct page *page) void register_inmem_page(struct inode *inode, struct page *page)