f2fs: support aligned pinned file

This patch supports 2MB-aligned pinned file, which can guarantee no GC at all
by allocating fully valid 2MB segment.

Check free segments by has_not_enough_free_secs() with large budget.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/recovery.c

@@ -711,7 +711,7 @@ next:
 		f2fs_put_page(page, 1);
 	}
 	if (!err)
-		f2fs_allocate_new_segments(sbi);
+		f2fs_allocate_new_segments(sbi, NO_CHECK_TYPE);
 	return err;
 }