f2fs: enhance the bit operation for SSR
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>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 74c4748..5fa519f 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -132,47 +132,37 @@
unsigned long size, unsigned long offset)
{
const unsigned long *p = addr + BIT_WORD(offset);
- unsigned long result = offset & ~(BITS_PER_LONG - 1);
+ unsigned long result = size;
unsigned long tmp;
if (offset >= size)
return size;
- size -= result;
+ size -= (offset & ~(BITS_PER_LONG - 1));
offset %= BITS_PER_LONG;
- if (!offset)
- goto aligned;
- tmp = __reverse_ulong((unsigned char *)p);
- tmp |= ~((~0UL << offset) >> offset);
+ while (1) {
+ 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);
+
+ if (offset)
+ tmp |= ~0UL << (BITS_PER_LONG - offset);
+ if (size < BITS_PER_LONG)
+ tmp |= ~0UL >> size;
if (tmp != ~0UL)
- goto found_middle;
- result += BITS_PER_LONG;
+ goto found;
+pass:
+ if (size <= BITS_PER_LONG)
+ break;
size -= BITS_PER_LONG;
+ offset = 0;
p++;
}
- if (!size)
- return result;
-
- 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);
+ return result;
+found:
+ return result - size + __reverse_ffz(tmp);
}
void register_inmem_page(struct inode *inode, struct page *page)