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/segment.h

@@ -313,6 +313,8 @@ struct sit_entry_set {
  */
 static inline struct curseg_info *CURSEG_I(struct f2fs_sb_info *sbi, int type)
 {
+	if (type == CURSEG_COLD_DATA_PINNED)
+		type = CURSEG_COLD_DATA;
 	return (struct curseg_info *)(SM_I(sbi)->curseg_array + type);
 }