[PATCH v2 1/2] f2fs: use per-log target_bitmap to improve lookup performace of ssr allocation

[Chao Yu]

After commit 899fee36fac0 ("f2fs: fix to avoid data corruption by
forbidding SSR overwrite"), valid block bitmap of current openned
segment is fixed, let's introduce a per-log bitmap instead of temp
bitmap to avoid unnecessary calculation overhead whenever allocating
free slot w/ SSR allocator.

Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
v2:
- rebase to last dev-test branch
 fs/f2fs/segment.c | 30 ++++++++++++++++++++++--------
 fs/f2fs/segment.h |  1 +
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 4fd76e867e0a..9039d60c989d 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2840,31 +2840,39 @@ static int new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
 	return 0;
 }
 
-static int __next_free_blkoff(struct f2fs_sb_info *sbi,
-					int segno, block_t start)
+static void __get_segment_bitmap(struct f2fs_sb_info *sbi,
+					unsigned long *target_map,
+					int segno)
 {
 	struct seg_entry *se = get_seg_entry(sbi, segno);
 	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
-	unsigned long *target_map = SIT_I(sbi)->tmp_map;
 	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
 	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
 	int i;
 
 	for (i = 0; i < entries; i++)
 		target_map[i] = ckpt_map[i] | cur_map[i];
+}
+
+static int __next_free_blkoff(struct f2fs_sb_info *sbi, unsigned long *bitmap,
+					int segno, block_t start)
+{
+	__get_segment_bitmap(sbi, bitmap, segno);
 
-	return __find_rev_next_zero_bit(target_map, BLKS_PER_SEG(sbi), start);
+	return __find_rev_next_zero_bit(bitmap, BLKS_PER_SEG(sbi), start);
 }
 
 static int f2fs_find_next_ssr_block(struct f2fs_sb_info *sbi,
-		struct curseg_info *seg)
+					struct curseg_info *seg)
 {
-	return __next_free_blkoff(sbi, seg->segno, seg->next_blkoff + 1);
+	return __find_rev_next_zero_bit(seg->target_map,
+				BLKS_PER_SEG(sbi), seg->next_blkoff + 1);
 }
 
 bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
 {
-	return __next_free_blkoff(sbi, segno, 0) < BLKS_PER_SEG(sbi);
+	return __next_free_blkoff(sbi, SIT_I(sbi)->tmp_map, segno, 0) <
+							BLKS_PER_SEG(sbi);
 }
 
 /*
@@ -2890,7 +2898,8 @@ static int change_curseg(struct f2fs_sb_info *sbi, int type)
 
 	reset_curseg(sbi, type, 1);
 	curseg->alloc_type = SSR;
-	curseg->next_blkoff = __next_free_blkoff(sbi, curseg->segno, 0);
+	curseg->next_blkoff = __next_free_blkoff(sbi, curseg->target_map,
+							curseg->segno, 0);
 
 	sum_page = f2fs_get_sum_page(sbi, new_segno);
 	if (IS_ERR(sum_page)) {
@@ -4633,6 +4642,10 @@ static int build_curseg(struct f2fs_sb_info *sbi)
 				sizeof(struct f2fs_journal), GFP_KERNEL);
 		if (!array[i].journal)
 			return -ENOMEM;
+		array[i].target_map = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE,
+								GFP_KERNEL);
+		if (!array[i].target_map)
+			return -ENOMEM;
 		if (i < NR_PERSISTENT_LOG)
 			array[i].seg_type = CURSEG_HOT_DATA + i;
 		else if (i == CURSEG_COLD_DATA_PINNED)
@@ -5451,6 +5464,7 @@ static void destroy_curseg(struct f2fs_sb_info *sbi)
 	for (i = 0; i < NR_CURSEG_TYPE; i++) {
 		kfree(array[i].sum_blk);
 		kfree(array[i].journal);
+		kfree(array[i].target_map);
 	}
 	kfree(array);
 }
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index e1c0f418aa11..10f3e44f036f 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -292,6 +292,7 @@ struct curseg_info {
 	struct f2fs_summary_block *sum_blk;	/* cached summary block */
 	struct rw_semaphore journal_rwsem;	/* protect journal area */
 	struct f2fs_journal *journal;		/* cached journal info */
+	unsigned long *target_map;		/* bitmap for SSR allocator */
 	unsigned char alloc_type;		/* current allocation type */
 	unsigned short seg_type;		/* segment type like CURSEG_XXX_TYPE */
 	unsigned int segno;			/* current segment number */
-- 
2.40.1