f2fs: do checkpoint when there's not enough free sections

We didn't do checkpoint in FG_GC case, which may cause losing to reclaim prefree
sctions in time.

Fixes: 6f8d445 ("f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/gc.c

@@ -1806,6 +1806,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
 	};
 	unsigned int skipped_round = 0, round = 0;
 	unsigned int upper_secs;
+	bool stop_gc = false;
 
 	trace_f2fs_gc_begin(sbi->sb, gc_type, gc_control->no_bg_gc,
 				gc_control->nr_free_secs,
@@ -1876,19 +1877,15 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
 				(gc_type == FG_GC) ? sec_freed : 0, 0)) {
 		if (gc_type == FG_GC && sec_freed < gc_control->nr_free_secs)
 			goto go_gc_more;
-		goto stop;
-	}
-
-	/* FG_GC stops GC by skip_count */
-	if (gc_type == FG_GC) {
+		stop_gc = true;
+	} else if (gc_type == FG_GC) {
+		/* FG_GC stops GC by skip_count */
 		if (sbi->skipped_gc_rwsem)
 			skipped_round++;
 		round++;
 		if (skipped_round > MAX_SKIP_GC_COUNT &&
-				skipped_round * 2 >= round) {
-			ret = f2fs_write_checkpoint(sbi, &cpc);
-			goto stop;
-		}
+				skipped_round * 2 >= round)
+			stop_gc = true;
 	}
 
 	__get_secs_required(sbi, NULL, &upper_secs, NULL);
@@ -1901,12 +1898,13 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
 				prefree_segments(sbi)) {
 		ret = f2fs_write_checkpoint(sbi, &cpc);
 		if (ret)
-			goto stop;
+			stop_gc = true;
 	}
 go_gc_more:
-	segno = NULL_SEGNO;
-	goto gc_more;
-
+	if (!stop_gc) {
+		segno = NULL_SEGNO;
+		goto gc_more;
+	}
 stop:
 	SIT_I(sbi)->last_victim[ALLOC_NEXT] = 0;
 	SIT_I(sbi)->last_victim[FLUSH_DEVICE] = gc_control->victim_segno;