f2fs: adjust the way of calculating nat block
use a slightly simpler expression to calculate nat block with nid.
Signed-off-by: Fan Li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index 2f9603f..ebed024 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -200,13 +200,16 @@
struct f2fs_nm_info *nm_i = NM_I(sbi);
pgoff_t block_off;
pgoff_t block_addr;
- int seg_off;
+ /*
+ * block_off = segment_off * 512 + off_in_segment
+ * OLD = (segment_off * 512) * 2 + off_in_segment
+ * NEW = 2 * (segment_off * 512 + off_in_segment) - off_in_segment
+ */
block_off = NAT_BLOCK_OFFSET(start);
- seg_off = block_off >> sbi->log_blocks_per_seg;
block_addr = (pgoff_t)(nm_i->nat_blkaddr +
- (seg_off << sbi->log_blocks_per_seg << 1) +
+ (block_off << 1) -
(block_off & (sbi->blocks_per_seg - 1)));
if (f2fs_test_bit(block_off, nm_i->nat_bitmap))