f2fs: do gc in greedy mode for whole range if gc_urgent mode is set

Otherwise, f2fs conducts GC on 8GB range only based on slow cost-benefit.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/gc.c

@@ -162,12 +162,17 @@ static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
 {
 	int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
 
-	if (gc_th && gc_th->gc_idle) {
+	if (!gc_th)
+		return gc_mode;
+
+	if (gc_th->gc_idle) {
 		if (gc_th->gc_idle == 1)
 			gc_mode = GC_CB;
 		else if (gc_th->gc_idle == 2)
 			gc_mode = GC_GREEDY;
 	}
+	if (gc_th->gc_urgent)
+		gc_mode = GC_GREEDY;
 	return gc_mode;
 }
 
@@ -189,7 +194,9 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
 	}
 
 	/* we need to check every dirty segments in the FG_GC case */
-	if (gc_type != FG_GC && p->max_search > sbi->max_victim_search)
+	if (gc_type != FG_GC &&
+			(sbi->gc_thread && !sbi->gc_thread->gc_urgent) &&
+			p->max_search > sbi->max_victim_search)
 		p->max_search = sbi->max_victim_search;
 
 	/* let's select beginning hot/small space first in no_heap mode*/