From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: Ext2/3 block remapping tool Date: Mon, 30 Apr 2007 14:29:21 +0200 Message-ID: <20070430122921.GI28367@duck.suse.cz> References: <20070426192953.GC2841@duck.suse.cz> <20070427180942.GB5967@schatzie.adilger.int> <20070430120930.GA10604@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org To: Theodore Tso Return-path: Content-Disposition: inline In-Reply-To: <20070430120930.GA10604@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Mon 30-04-07 08:09:30, Theodore Tso wrote: > On Fri, Apr 27, 2007 at 12:09:42PM -0600, Andreas Dilger wrote: > > I'd prefer that such functionality be integrated with Takashi's online > > defrag tool, since it needs virtually the same functionality. For that > > matter, this is also very similar to the block-mapped -> extents tool > > from Aneesh. It doesn't make sense to have so many separate tools for > > users, especially if they start interfering with each other (i.e. defrag > > undoes the remapping done by your tool). > > Yep, in fact, I'm really glad that Jan is working on the remapping > tool because if the on-line defrag kernel interfaces don't have the > right support for it, then that means we need to fix the on-line > defrag patches. :-) ;-) Exactly that was the reason why I wrote the userspace program - so that I have something in hands when we start discussing how the kernel interface will look like. > While we're at it, someone want to start thinking about on-line > shrinking of ext4 filesystems? Again, the same block remapping > interfaces for defrag and file access optimizations should also be > useful for shrinking filesystems (even if some of the files that need > to be relocated are being actively used). If not, that probably means > we got the interface wrong. Yes, that's a good idea. Currently it seems to me that block+inode relocation (we also need for defrag) would be enough to support filesystem shrinking. Actually, in some ancient times (like 6-7 years ago) I had written ext2 online filesystem shrinking. Currently, the patch is probably unusably obsolete but I can still dig it out and look what functions did I need at that time. Honza -- Jan Kara SuSE CR Labs