From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:54146 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752143AbbFZRAi (ORCPT ); Fri, 26 Jun 2015 13:00:38 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Z8WzR-0005X1-0r for linux-btrfs@vger.kernel.org; Fri, 26 Jun 2015 19:00:33 +0200 Received: from barriere.frankfurter-softwarefabrik.de ([217.11.197.1]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 26 Jun 2015 19:00:32 +0200 Received: from lvml by barriere.frankfurter-softwarefabrik.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 26 Jun 2015 19:00:32 +0200 To: linux-btrfs@vger.kernel.org From: Lutz Vieweg Subject: btrfs filesystem defrag fails with "Resource temporarily unavailable" when strace'd Date: Fri, 26 Jun 2015 19:00:27 +0200 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: I started... btrfs filesystem defragment -v /some/directory and this took (unexpectedly, for just 150M of data) a long time (minutes). So I wondered whether I could see via "strace -p PID" what was going on with the process. Immediately when strace tries to attach, the btrfs process dies with this error message: > ERROR: defrag failed on /some/directory - Resource temporarily unavailable This is 100% reproducable. The strace output looks like this: > Process 1402 attached > brk(0) = 0x1468000 > brk(0) = 0x1468000 > brk(0x1460000) = 0x1460000 > brk(0) = 0x1460000 > close(3) = 0 > write(2, "ERROR: defrag failed on /some/d"..., 84) = 84 > write(1, "btrfs-progs v4.1\n", 17) = 17 > write(2, "total 1 failures\n", 17) = 17 > exit_group(1) = ? > +++ exited with 1 +++ This is the first time I see a prozess crash upon strace being attached - is this intended behaviour? If so... why? (Tried again without strace, "the btrfs filesystem defragment" command later finished ok, albeight after a loong time.) Regards, Lutz Vieweg