f2fs: add valid block ratio not to do excessive GC for one time GC

We need to introduce a valid block ratio threshold not to trigger
excessive GC for zoned deivces. The initial value of it is 95%. So, F2FS
will stop the thread from intiating GC for sections having valid blocks
exceeding the ratio.
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -811,3 +811,11 @@ Contact:	"Daeho Jeong" <daehojeong@google.com>
 Description:	If the percentage of free sections over total sections is under this
 		number, F2FS boosts garbage collection for zoned devices through the
 		background GC thread. the default number is "25".
+
+What:		/sys/fs/f2fs/<disk>/gc_valid_thresh_ratio
+Date:		September 2024
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	It controls the valid block ratio threshold not to trigger excessive GC
+		for zoned deivces. The initial value of it is 95(%). F2FS will stop the
+		background GC thread from intiating GC for sections having valid blocks
+		exceeding the ratio.

fs/f2fs/f2fs.h

@@ -3922,7 +3922,7 @@ void f2fs_destroy_garbage_collection_cache(void);
 /* victim selection function for cleaning and SSR */
 int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
 			int gc_type, int type, char alloc_mode,
-			unsigned long long age);
+			unsigned long long age, bool one_time);
 
 /*
  * recovery.c

fs/f2fs/gc.c

@@ -196,6 +196,7 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 		return -ENOMEM;
 
 	gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
+	gc_th->valid_thresh_ratio = DEF_GC_THREAD_VALID_THRESH_RATIO;
 
 	if (f2fs_sb_has_blkzoned(sbi)) {
 		gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME_ZONED;
@@ -396,6 +397,11 @@ static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
 	if (p->alloc_mode == SSR)
 		return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
 
+	if (p->one_time_gc && (get_valid_blocks(sbi, segno, true) >=
+		CAP_BLKS_PER_SEC(sbi) * sbi->gc_thread->valid_thresh_ratio /
+		100))
+		return UINT_MAX;
+
 	/* alloc_mode == LFS */
 	if (p->gc_mode == GC_GREEDY)
 		return get_valid_blocks(sbi, segno, true);
@@ -770,7 +776,7 @@ static int f2fs_gc_pinned_control(struct inode *inode, int gc_type,
  */
 int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
 			int gc_type, int type, char alloc_mode,
-			unsigned long long age)
+			unsigned long long age, bool one_time)
 {
 	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 	struct sit_info *sm = SIT_I(sbi);
@@ -787,6 +793,7 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
 	p.alloc_mode = alloc_mode;
 	p.age = age;
 	p.age_threshold = sbi->am.age_threshold;
+	p.one_time_gc = one_time;
 
 retry:
 	select_policy(sbi, gc_type, type, &p);
@@ -1698,13 +1705,14 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 }
 
 static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
-			int gc_type)
+			int gc_type, bool one_time)
 {
 	struct sit_info *sit_i = SIT_I(sbi);
 	int ret;
 
 	down_write(&sit_i->sentry_lock);
-	ret = f2fs_get_victim(sbi, victim, gc_type, NO_CHECK_TYPE, LFS, 0);
+	ret = f2fs_get_victim(sbi, victim, gc_type, NO_CHECK_TYPE,
+			LFS, 0, one_time);
 	up_write(&sit_i->sentry_lock);
 	return ret;
 }
@@ -1911,7 +1919,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
 		goto stop;
 	}
 retry:
-	ret = __get_victim(sbi, &segno, gc_type);
+	ret = __get_victim(sbi, &segno, gc_type, gc_control->one_time);
 	if (ret) {
 		/* allow to search victim from sections has pinned data */
 		if (ret == -ENODATA && gc_type == FG_GC &&

fs/f2fs/gc.h

@@ -25,6 +25,7 @@
 #define DEF_GC_THREAD_CANDIDATE_RATIO		20	/* select 20% oldest sections as candidates */
 #define DEF_GC_THREAD_MAX_CANDIDATE_COUNT	10	/* select at most 10 sections as candidates */
 #define DEF_GC_THREAD_AGE_WEIGHT		60	/* age weight */
+#define DEF_GC_THREAD_VALID_THRESH_RATIO	95	/* do not GC over 95% valid block ratio for one time GC */
 #define DEFAULT_ACCURACY_CLASS			10000	/* accuracy class */
 
 #define LIMIT_INVALID_BLOCK	40 /* percentage over total user space */
@@ -65,6 +66,7 @@ struct f2fs_gc_kthread {
 	/* for gc control for zoned devices */
 	unsigned int no_zoned_gc_percent;
 	unsigned int boost_zoned_gc_percent;
+	unsigned int valid_thresh_ratio;
 };
 
 struct gc_inode_list {

fs/f2fs/segment.c

@@ -3090,7 +3090,8 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type,
 	sanity_check_seg_type(sbi, seg_type);
 
 	/* f2fs_need_SSR() already forces to do this */
-	if (!f2fs_get_victim(sbi, &segno, BG_GC, seg_type, alloc_mode, age)) {
+	if (!f2fs_get_victim(sbi, &segno, BG_GC, seg_type,
+				alloc_mode, age, false)) {
 		curseg->next_segno = segno;
 		return 1;
 	}
@@ -3117,7 +3118,8 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type,
 	for (; cnt-- > 0; reversed ? i-- : i++) {
 		if (i == seg_type)
 			continue;
-		if (!f2fs_get_victim(sbi, &segno, BG_GC, i, alloc_mode, age)) {
+		if (!f2fs_get_victim(sbi, &segno, BG_GC, i,
+					alloc_mode, age, false)) {
 			curseg->next_segno = segno;
 			return 1;
 		}

fs/f2fs/segment.h

@@ -188,6 +188,7 @@ struct victim_sel_policy {
 	unsigned int min_segno;		/* segment # having min. cost */
 	unsigned long long age;		/* mtime of GCed section*/
 	unsigned long long age_threshold;/* age threshold */
+	bool one_time_gc;		/* one time GC */
 };
 
 struct seg_entry {

fs/f2fs/sysfs.c

@@ -979,6 +979,7 @@ GC_THREAD_RW_ATTR(gc_max_sleep_time, max_sleep_time);
 GC_THREAD_RW_ATTR(gc_no_gc_sleep_time, no_gc_sleep_time);
 GC_THREAD_RW_ATTR(gc_no_zoned_gc_percent, no_zoned_gc_percent);
 GC_THREAD_RW_ATTR(gc_boost_zoned_gc_percent, boost_zoned_gc_percent);
+GC_THREAD_RW_ATTR(gc_valid_thresh_ratio, valid_thresh_ratio);
 
 /* SM_INFO ATTR */
 SM_INFO_RW_ATTR(reclaim_segments, rec_prefree_segments);
@@ -1141,6 +1142,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(gc_no_gc_sleep_time),
 	ATTR_LIST(gc_no_zoned_gc_percent),
 	ATTR_LIST(gc_boost_zoned_gc_percent),
+	ATTR_LIST(gc_valid_thresh_ratio),
 	ATTR_LIST(gc_idle),
 	ATTR_LIST(gc_urgent),
 	ATTR_LIST(reclaim_segments),