From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:46990 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752358Ab3H0G3z (ORCPT ); Tue, 27 Aug 2013 02:29:55 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1VECmo-0005G2-1Z for linux-btrfs@vger.kernel.org; Tue, 27 Aug 2013 08:29:54 +0200 Received: from ip68-231-22-224.ph.ph.cox.net ([68.231.22.224]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 27 Aug 2013 08:29:54 +0200 Received: from 1i5t5.duncan by ip68-231-22-224.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 27 Aug 2013 08:29:54 +0200 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: snapshot space available Date: Tue, 27 Aug 2013 06:29:30 +0000 (UTC) Message-ID: References: <201308262335.25871.russell@coker.com.au> < 6FCC5036-CC36-4DA3-8594-1FA23F3BB256@colorremedies.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Chris Murphy posted on Mon, 26 Aug 2013 09:15:46 -0600 as excerpted: > I'm uncertain if autodefrag avoids this problem. It does seem like in > certain instances, like this, the file system needs to be able to prune > itself somehow, like a partial balance to consolidate data chunks and > then release their space so they can become metadata chunks. Intriguing question re defrag. I hadn't thought of the possibility until you suggested it, but indeed, tracking hundreds of extents instead of one or a dozen, does sound like it could reduce metadata usage, reducing the chance of running into the issue in the first place as well as lessening the chance of a "simple" delete temporarily requiring significant new metadata resources in ordered to track all those extent frees before the final atomic root entry update. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman