From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752685AbbC0VGS (ORCPT ); Fri, 27 Mar 2015 17:06:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46445 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751212AbbC0VGP (ORCPT ); Fri, 27 Mar 2015 17:06:15 -0400 Date: Fri, 27 Mar 2015 17:06:13 -0400 From: Vivek Goyal To: Tejun Heo Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, jack@suse.cz, hch@infradead.org, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com Subject: Re: [PATCH 21/48] writeback: make backing_dev_info host cgroup-specific bdi_writebacks Message-ID: <20150327210612.GA23840@redhat.com> References: <1427086499-15657-1-git-send-email-tj@kernel.org> <1427086499-15657-22-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1427086499-15657-22-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 23, 2015 at 12:54:32AM -0400, Tejun Heo wrote: [..] > +/** > + * inode_attach_wb - associate an inode with its wb > + * @inode: inode of interest > + * @page: page being dirtied (may be NULL) > + * > + * If @inode doesn't have its wb, associate it with the wb matching the > + * memcg of @page or, if @page is NULL, %current. May be called w/ or w/o > + * @inode->i_lock. > + */ > +static inline void inode_attach_wb(struct inode *inode, struct page *page) > +{ > + if (!inode->i_wb) > + __inode_attach_wb(inode, page); > +} Hi Tejun, I was curious to know that why do we need this "struct page *page" when trying to attach a inode to a bdi_writeback. Is using current's cgroup always not sufficient? Thanks Vivek