f2fs: use for_each_set_bit to simplify the code

index b90dbe5..d7947d9 100644
@@ -186,7 +186,6 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
 static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
 {
 	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
-	unsigned int hint = 0;
 	unsigned int secno;
 
 	/*

@@ -194,11 +193,9 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
 	 * selected by background GC before.
 	 * Those segments guarantee they have small valid blocks.
 	 */
-next:
-	secno = find_next_bit(dirty_i->victim_secmap, TOTAL_SECS(sbi), hint++);
-	if (secno < TOTAL_SECS(sbi)) {
+	for_each_set_bit(secno, dirty_i->victim_secmap, TOTAL_SECS(sbi)) {
 		if (sec_usage_check(sbi, secno))
-			goto next;
+			continue;
 		clear_bit(secno, dirty_i->victim_secmap);
 		return secno * sbi->segs_per_sec;
 	}

index c3b76d0..0dfeeba 100644
@@ -439,17 +439,12 @@ static void add_discard_addrs(struct f2fs_sb_info *sbi,
 static void set_prefree_as_free_segments(struct f2fs_sb_info *sbi)
 {
 	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
-	unsigned int segno = -1;
+	unsigned int segno;
 	unsigned int total_segs = TOTAL_SEGS(sbi);
 
 	mutex_lock(&dirty_i->seglist_lock);
-	while (1) {
-		segno = find_next_bit(dirty_i->dirty_segmap[PRE], total_segs,
-				segno + 1);
-		if (segno >= total_segs)
-			break;
+	for_each_set_bit(segno, dirty_i->dirty_segmap[PRE], total_segs)
 		__set_test_and_free(sbi, segno);
-	}
 	mutex_unlock(&dirty_i->seglist_lock);
 }
 

@@ -1531,7 +1526,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi)
 	struct page *page = NULL;
 	struct f2fs_sit_block *raw_sit = NULL;
 	unsigned int start = 0, end = 0;
-	unsigned int segno = -1;
+	unsigned int segno;
 	bool flushed;
 
 	mutex_lock(&curseg->curseg_mutex);

@@ -1543,7 +1538,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi)
 	 */
 	flushed = flush_sits_in_journal(sbi);
 
-	while ((segno = find_next_bit(bitmap, nsegs, segno + 1)) < nsegs) {
+	for_each_set_bit(segno, bitmap, nsegs) {
 		struct seg_entry *se = get_seg_entry(sbi, segno);
 		int sit_offset, offset;