Return-Path: Received: from mail-wi0-f171.google.com ([209.85.212.171]:46781 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752748AbaKLLqk (ORCPT ); Wed, 12 Nov 2014 06:46:40 -0500 Received: by mail-wi0-f171.google.com with SMTP id r20so4583047wiv.16 for ; Wed, 12 Nov 2014 03:46:38 -0800 (PST) Date: Wed, 12 Nov 2014 11:46:31 +0000 From: Steve Capper To: Chandan Rajendra Cc: clm@fb.com, jbacik@fb.com, bo.li.liu@oracle.com, dsterba@suse.cz, aneesh.kumar@linux.vnet.ibm.com, linux-btrfs@vger.kernel.org, chandan@mykolab.com, jcm@redhat.com Subject: Re: [RFC PATCH V8 00/16] Btrfs: Subpagesize-blocksize: Get rid of whole page I/O. Message-ID: <20141112114630.GA27082@linaro.org> References: <1415780268-2017-1-git-send-email-chandan@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1415780268-2017-1-git-send-email-chandan@linux.vnet.ibm.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, Nov 12, 2014 at 01:47:32PM +0530, Chandan Rajendra wrote: [...] > > Chandan Rajendra (14): > Btrfs: subpagesize-blocksize: Get rid of whole page reads. > Btrfs: subpagesize-blocksize: Get rid of whole page writes. > Btrfs: subpagesize-blocksize: __btrfs_buffered_write: Reserve/release > extents aligned to block size. > Btrfs: subpagesize-blocksize: Read tree blocks whose size is > Btrfs: subpagesize-blocksize: Write only dirty extent buffers > belonging to a page > Btrfs: subpagesize-blocksize: Compute and look up csums based on > sectorsized blocks. > Btrfs: subpagesize-blocksize: __extent_writepage: Write only dirty > blocks of a page. > Btrfs: subpagesize-blocksize: fallocate: Work with sectorsized units. > Btrfs: subpagesize-blocksize: btrfs_page_mkwrite: Reserve space in > sectorsized units. > Btrfs: subpagesize-blocksize: Search for all ordered extents that > could span across a page. > Btrfs: subpagesize-blocksize: Deal with partial ordered extent > allocations. > Btrfs: subpagesize-blocksize: Explicitly Track I/O status of blocks of > an ordered extent. > Btrfs: subpagesize-blocksize: Revert commit > fc4adbff823f76577ece26dcb88bf6f8392dbd43. > Btrfs: subpagesize-blocksize: Track blocks of ordered extent submitted > for write I/O. > > Chandra Seetharaman (2): > Btrfs: subpagesize-blocksize: Define extent_buffer_head. > Btrfs: subpagesize-blocksize: Allow mounting filesystems where > sectorsize != PAGE_SIZE Thank you for posting this series Chandan, it's incredibly useful for us, I'll give it a go on arm64. For arm64, one can run with a 4KB or 64KB PAGE_SIZE (userspace is 64KB aligned and can cope with the switch), thus the inability of btrfs to cope with a change in PAGE_SIZE is close to being a showstopper. One could, for instance, have an installer running with a 4KB kernel which installs a server kernel running 64KB, then on reboot..... Another use case would be to simply move data disks from a machine running $ARCH to $ANOTHERARCH. Cheers, -- Steve