From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Fri, 15 Jun 2018 09:31:26 +0100 Subject: [Cluster-devel] iomap preparations for GFS2 v2 In-Reply-To: <20180615080326.GB19525@lst.de> References: <20180614120457.28285-1-hch@lst.de> <20180615080326.GB19525@lst.de> Message-ID: <5a1e303b-e96e-7faf-1bcd-36d63a237514@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, On 15/06/18 09:03, Christoph Hellwig wrote: > On Thu, Jun 14, 2018 at 03:04:38PM +0200, Andreas Gruenbacher wrote: >> I saw that you've pushed this onto the gfs2-iomap branch in your xfs >> repository. I've rebased the gfs2 iomap-write branch onto that; >> there's a trivial patch for adding a private pointer to struct iomap >> at the head of that branch that would sense to move to the shared >> branch as well now. > Please send that patch out ASAP. > >> The next step would probably be to start using iomap_readpage / >> iomap_readpages in gfs2 for block size == page size. This requires >> adding inline data support to iomap_readpage which is trivial, but >> because of gfs2's reliance on buffer heads, that alone isn't enough. > Is it? At least for block size == page size we will only call > readpage on a pristine, newly allocated page. So buffer heads won't > be in the game at that point, and the iomap buffered write code will > just allocate them for you once we start a write operation, or take > a page fault that makes the page writable. > Yes, for block size == page size, it should not be an issue to drop the use of buffer heads on reads in GFS2. I was fairly sure that we already did that in ->readpages() anyway, but it is a while since I looked at the code and my memory may be playing tricks on me, Steve.