f2fs: return correct errno in f2fs_gc

[ Upstream commit 61f7725aa148ee870436a29d3a24d5c00ab7e9af ]

This fixes overriding error number in f2fs_gc.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>

fs/f2fs/gc.c

@@ -1244,7 +1244,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
 
 	put_gc_inode(&gc_list);
 
-	if (sync)
+	if (sync && !ret)
 		ret = sec_freed ? 0 : -EAGAIN;
 	return ret;
 }