f2fs: handle bug cases by letting fsck.f2fs initiate

This patch adds to handle corner buggy cases for fsck.f2fs.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -317,6 +317,10 @@ static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
 		struct seg_entry *sentry = get_seg_entry(sbi, segno);
 		enum dirty_type t = sentry->type;
 
+		if (unlikely(t >= DIRTY)) {
+			f2fs_bug_on(sbi, 1);
+			return;
+		}
 		if (!test_and_set_bit(segno, dirty_i->dirty_segmap[t]))
 			dirty_i->nr_dirty[t]++;
 	}
@@ -1745,8 +1749,12 @@ static void init_dirty_segmap(struct f2fs_sb_info *sbi)
 			break;
 		offset = segno + 1;
 		valid_blocks = get_valid_blocks(sbi, segno, 0);
-		if (valid_blocks >= sbi->blocks_per_seg || !valid_blocks)
+		if (valid_blocks == sbi->blocks_per_seg || !valid_blocks)
 			continue;
+		if (valid_blocks > sbi->blocks_per_seg) {
+			f2fs_bug_on(sbi, 1);
+			continue;
+		}
 		mutex_lock(&dirty_i->seglist_lock);
 		__locate_dirty_segment(sbi, segno, DIRTY);
 		mutex_unlock(&dirty_i->seglist_lock);