f2fs: add gc_boost_gc_greedy sysfs node

Add this to control GC algorithm for boost GC.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: Daeho Jeong

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -877,3 +877,9 @@ Contact:	"Daeho Jeong" <daehojeong@google.com>
 Description:	Set a multiplier for the background GC migration window when F2FS GC is
 		boosted. The range should be from 1 to the segment count in a section.
 		Default: 5
+
+What:		/sys/fs/f2fs/<disk>/gc_boost_gc_greedy
+Date:		June 2025
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	Control GC algorithm for boost GC. 0: cost benefit, 1: greedy
+		Default: 1

fs/f2fs/gc.c

@@ -141,7 +141,7 @@ static int gc_thread_func(void *data)
 					FOREGROUND : BACKGROUND);
 
 		sync_mode = (F2FS_OPTION(sbi).bggc_mode == BGGC_MODE_SYNC) ||
-				gc_control.one_time;
+			(gc_control.one_time && gc_th->boost_gc_greedy);
 
 		/* foreground GC was been triggered via f2fs_balance_fs() */
 		if (foreground && !f2fs_sb_has_blkzoned(sbi))
@@ -198,6 +198,7 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 	gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
 	gc_th->valid_thresh_ratio = DEF_GC_THREAD_VALID_THRESH_RATIO;
 	gc_th->boost_gc_multiple = BOOST_GC_MULTIPLE;
+	gc_th->boost_gc_greedy = GC_GREEDY;
 
 	if (f2fs_sb_has_blkzoned(sbi)) {
 		gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME_ZONED;

fs/f2fs/gc.h

@@ -69,6 +69,7 @@ struct f2fs_gc_kthread {
 	unsigned int boost_zoned_gc_percent;
 	unsigned int valid_thresh_ratio;
 	unsigned int boost_gc_multiple;
+	unsigned int boost_gc_greedy;
 };
 
 struct gc_inode_list {

fs/f2fs/sysfs.c

@@ -859,6 +859,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
+	if (!strcmp(a->attr.name, "gc_boost_gc_greedy")) {
+		if (t > GC_GREEDY)
+			return -EINVAL;
+		sbi->gc_thread->boost_gc_greedy = (unsigned int)t;
+		return count;
+	}
+
 	*ui = (unsigned int)t;
 
 	return count;
@@ -1086,6 +1093,7 @@ 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);
 GC_THREAD_RW_ATTR(gc_boost_gc_multiple, boost_gc_multiple);
+GC_THREAD_RW_ATTR(gc_boost_gc_greedy, boost_gc_greedy);
 
 /* SM_INFO ATTR */
 SM_INFO_RW_ATTR(reclaim_segments, rec_prefree_segments);
@@ -1258,6 +1266,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(gc_boost_zoned_gc_percent),
 	ATTR_LIST(gc_valid_thresh_ratio),
 	ATTR_LIST(gc_boost_gc_multiple),
+	ATTR_LIST(gc_boost_gc_greedy),
 	ATTR_LIST(gc_idle),
 	ATTR_LIST(gc_urgent),
 	ATTR_LIST(reclaim_segments),