f2fs: refactor next blk selection

Remove __refresh_next_blkoff by opencoding the SSR vs LFS segment check
in the only caller, and then add helpers for SSR block selection and
blkoff randomization instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -2632,30 +2632,10 @@ static int __next_free_blkoff(struct f2fs_sb_info *sbi,
 	return __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, start);
 }
 
-/*
- * If a segment is written by LFS manner, next block offset is just obtained
- * by increasing the current block offset. However, if a segment is written by
- * SSR manner, next block offset obtained by calling __next_free_blkoff
- */
-static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
+static int f2fs_find_next_ssr_block(struct f2fs_sb_info *sbi,
 		struct curseg_info *seg)
 {
-	if (seg->alloc_type == SSR) {
-		seg->next_blkoff =
-			__next_free_blkoff(sbi, seg->segno,
-						seg->next_blkoff + 1);
-	} else {
-		seg->next_blkoff++;
-		if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK) {
-			/* To allocate block chunks in different sizes, use random number */
-			if (--seg->fragment_remained_chunk <= 0) {
-				seg->fragment_remained_chunk =
-				   get_random_u32_inclusive(1, sbi->max_fragment_chunk);
-				seg->next_blkoff +=
-				   get_random_u32_inclusive(1, sbi->max_fragment_hole);
-			}
-		}
-	}
+	return __next_free_blkoff(sbi, seg->segno, seg->next_blkoff + 1);
 }
 
 bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
@@ -3232,6 +3212,19 @@ static int __get_segment_type(struct f2fs_io_info *fio)
 	return type;
 }
 
+static void f2fs_randomize_chunk(struct f2fs_sb_info *sbi,
+		struct curseg_info *seg)
+{
+	/* To allocate block chunks in different sizes, use random number */
+	if (--seg->fragment_remained_chunk > 0)
+		return;
+
+	seg->fragment_remained_chunk =
+		get_random_u32_inclusive(1, sbi->max_fragment_chunk);
+	seg->next_blkoff +=
+		get_random_u32_inclusive(1, sbi->max_fragment_hole);
+}
+
 void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
 		block_t old_blkaddr, block_t *new_blkaddr,
 		struct f2fs_summary *sum, int type,
@@ -3261,8 +3254,13 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
 	f2fs_wait_discard_bio(sbi, *new_blkaddr);
 
 	curseg->sum_blk->entries[curseg->next_blkoff] = *sum;
-	__refresh_next_blkoff(sbi, curseg);
-
+	if (curseg->alloc_type == SSR) {
+		curseg->next_blkoff = f2fs_find_next_ssr_block(sbi, curseg);
+	} else {
+		curseg->next_blkoff++;
+		if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK)
+			f2fs_randomize_chunk(sbi, curseg);
+	}
 	stat_inc_block_count(sbi, curseg);
 
 	if (from_gc) {