f2fs: add bitmaps for empty or full NAT blocks
This patches adds bitmaps to represent empty or full NAT blocks containing
free nid entries.
If we can find valid crc|cp_ver in the last block of checkpoint pack, we'll
use these bitmaps when building free nids. In order to avoid checkpointing
burden, up-to-date bitmaps will be flushed only during umount time. So,
normally we can get this gain, but when power-cut happens, we rely on fsck.f2fs
which recovers this bitmap again.
After this patch, we build free nids from nid #0 at mount time to make more
full NAT blocks, but in runtime, we check empty NAT blocks to load free nids
without loading any NAT pages from disk.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 3e95db5..9eb6d89 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -386,7 +386,7 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
if (!available_free_memory(sbi, FREE_NIDS))
try_to_free_nids(sbi, MAX_FREE_NIDS);
else
- build_free_nids(sbi, false);
+ build_free_nids(sbi, false, false);
if (!is_idle(sbi))
return;