From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 9A4A26B0006 for ; Fri, 6 Apr 2018 04:07:17 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id b9so221545wrj.15 for ; Fri, 06 Apr 2018 01:07:17 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id j49si6708858wra.297.2018.04.06.01.07.16 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 06 Apr 2018 01:07:16 -0700 (PDT) Date: Fri, 6 Apr 2018 10:07:14 +0200 From: Michal Hocko Subject: Re: [PATCH] writeback: safer lock nesting Message-ID: <20180406080714.GG8286@dhcp22.suse.cz> References: <2cb713cd-0b9b-594c-31db-b4582f8ba822@meituan.com> <20180406080324.160306-1-gthelen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180406080324.160306-1-gthelen@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Greg Thelen Cc: Wang Long , Andrew Morton , Johannes Weiner , Tejun Heo , npiggin@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri 06-04-18 01:03:24, Greg Thelen wrote: [...] > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index d4d04fee568a..d51bae5a53e2 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -746,10 +746,11 @@ int inode_congested(struct inode *inode, int cong_bits) > if (inode && inode_to_wb_is_valid(inode)) { > struct bdi_writeback *wb; > bool locked, congested; > + unsigned long flags; > > - wb = unlocked_inode_to_wb_begin(inode, &locked); > + wb = unlocked_inode_to_wb_begin(inode, &locked, &flags); Wouldn't it be better to have a cookie (struct) rather than 2 parameters and let unlocked_inode_to_wb_end DTRT? > congested = wb_congested(wb, cong_bits); > - unlocked_inode_to_wb_end(inode, locked); > + unlocked_inode_to_wb_end(inode, locked, flags); > return congested; > } -- Michal Hocko SUSE Labs