From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Marshall Subject: Re: fs compression Date: Wed, 20 May 2015 12:50:24 -0700 Message-ID: <20150520195024.GA3961@eden.sea.cyngn.com> References: <1431145253-2019-1-git-send-email-jaegeuk@kernel.org> <1431145253-2019-3-git-send-email-jaegeuk@kernel.org> <20150513020208.GK15721@dastard> <20150513064802.GA48682@jaegeuk-mac02.hsd1.ca.comcast.net> <20150514003721.GN15721@dastard> <20150516132403.GA2998@thunk.org> <20150516171326.GA24795@eden.sea.cyngn.com> <20150520174635.GA17651@eden.sea.cyngn.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Theodore Ts'o , Jaegeuk Kim , linux-fsdevel@vger.kernel.org Return-path: Received: from mail-pd0-f174.google.com ([209.85.192.174]:33354 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754040AbbETTu1 (ORCPT ); Wed, 20 May 2015 15:50:27 -0400 Received: by pdbqa5 with SMTP id qa5so80252867pdb.0 for ; Wed, 20 May 2015 12:50:27 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20150520174635.GA17651@eden.sea.cyngn.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: > The compression code must be able to read pages from the underlying > filesystem. This involves using the pagecache. But the uncompressed data > is what ultimately should end up in the pagecache. This is where I'm > currently stuck. How do I implement the code such that the underlying > compressed data may be read (using the pagecache or not) while not > disturbing the pagecache for the uncompressed data? I'm wondering if I need > to create an internal address_space to pass down into the underlying > readpage? Or is there another way to do this? I created a private address_space for the inode that is passed into the lower readpage. That seems to be working. Is this a cool thing to do (hopefully)?