diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 0b6827dba25e..631e15345752 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1715,21 +1715,30 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
 	unsigned int start = 0, end = -1;
 	unsigned int secno, start_segno;
 	bool force = (cpc->reason & CP_DISCARD);
+	bool need_align = test_opt(sbi, LFS) && sbi->segs_per_sec > 1;
 
 	mutex_lock(&dirty_i->seglist_lock);
 
 	while (1) {
 		int i;
+
+		if (need_align && end != -1)
+			end--;
 		start = find_next_bit(prefree_map, MAIN_SEGS(sbi), end + 1);
 		if (start >= MAIN_SEGS(sbi))
 			break;
 		end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi),
 								start + 1);
 
-		for (i = start; i < end; i++)
-			clear_bit(i, prefree_map);
+		if (need_align) {
+			start = rounddown(start, sbi->segs_per_sec);
+			end = roundup(end, sbi->segs_per_sec);
+		}
 
-		dirty_i->nr_dirty[PRE] -= end - start;
+		for (i = start; i < end; i++) {
+			if (test_and_clear_bit(i, prefree_map))
+				dirty_i->nr_dirty[PRE]--;
+		}
 
 		if (!test_opt(sbi, DISCARD))
 			continue;
@@ -2516,6 +2525,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
 	struct discard_policy dpolicy;
 	unsigned long long trimmed = 0;
 	int err = 0;
+	bool need_align = test_opt(sbi, LFS) && sbi->segs_per_sec > 1;
 
 	if (start >= MAX_BLKADDR(sbi) || range->len < sbi->blocksize)
 		return -EINVAL;
@@ -2533,6 +2543,10 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
 	start_segno = (start <= MAIN_BLKADDR(sbi)) ? 0 : GET_SEGNO(sbi, start);
 	end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
 						GET_SEGNO(sbi, end);
+	if (need_align) {
+		start_segno = rounddown(start_segno, sbi->segs_per_sec);
+		end_segno = roundup(end_segno + 1, sbi->segs_per_sec) - 1;
+	}
 
 	cpc.reason = CP_DISCARD;
 	cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));