f2fs: avoid to ra unneeded blocks in recover flow

To improve recovery speed, f2fs try to readahead many contiguous blocks in warm
node segment, but for most time, abnormal power-off do not occur frequently, so
when mount a normal power-off f2fs image, by contrary ra so many blocks and then
invalid them will hurt the performance of mount.
It's better to just ra the first next-block for normal condition.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 2695d78..ec58bb2 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1431,8 +1431,8 @@
  */
 struct page *grab_meta_page(struct f2fs_sb_info *, pgoff_t);
 struct page *get_meta_page(struct f2fs_sb_info *, pgoff_t);
-struct page *get_meta_page_ra(struct f2fs_sb_info *, pgoff_t);
 int ra_meta_pages(struct f2fs_sb_info *, block_t, int, int);
+void ra_meta_pages_cond(struct f2fs_sb_info *, pgoff_t);
 long sync_meta_pages(struct f2fs_sb_info *, enum page_type, long);
 void add_dirty_inode(struct f2fs_sb_info *, nid_t, int type);
 void remove_dirty_inode(struct f2fs_sb_info *, nid_t, int type);