From: Greg Freemyer Subject: Re: [RFC][PATCH 0/3] ext4: online defrag (ver 1.0) Date: Fri, 30 Jan 2009 17:33:53 -0500 Message-ID: <87f94c370901301433x3e22892n5fddbb0804bddc4@mail.gmail.com> References: <49829A1D.5090002@rs.jp.nec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Theodore Tso , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Akira Fujita Return-path: In-Reply-To: <49829A1D.5090002@rs.jp.nec.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Fri, Jan 30, 2009 at 1:11 AM, Akira Fujita wrote: > Hi, > > I have rewritten ext4 online defrag patches based on the comments from Ted. > In the new defrag, create donor inode in the user space instead of kernel space, > and then allocate contiguous blocks to it with fallocate(). > In kernel space, exchange the blocks between target inode and donor inode, > and then copy the file data of target inode to donor inode every 64MB. > The EXT4_IOC_DEFRAG ioctl becomes simpler than the old one, > so it may be useful for other purposes. > > #define EXT4_IOC_DEFRAG _IOW('f', 15, struct move_extent) > Do we want the ioctl name to be specific to defrag? I thought Ted's goal was to make it more generic? I can also envision this same ioctl being implemented by other file systems so EXT4 seems an inappropriate prefix. Thoughts? > struct move_extent { > int org_fd; /* original file descriptor */ > int dest_fd; /* destination file descriptor */ > ext4_lblk_t start; /* logical offset of org_fd and dest_fd */ > ext4_lblk_t len; /* exchange block length */ > }; I would also like to see .dest_fd changed to .donor_fd. I would like to see the ABI be more flexible and have .start be broken into 2 fields: .start_orig .start_donor And I don't think they should be of type ext4_lblk_t. Something more generic seems appropriate. Thoughts? Greg -- Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com