From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:55091 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750892AbaH1ULM (ORCPT ); Thu, 28 Aug 2014 16:11:12 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1XN62E-0002UW-7t for linux-btrfs@vger.kernel.org; Thu, 28 Aug 2014 22:11:06 +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 ; Thu, 28 Aug 2014 22:11:06 +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 ; Thu, 28 Aug 2014 22:11:06 +0200 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: fallocate fail on btrfs Date: Thu, 28 Aug 2014 20:10:54 +0000 (UTC) Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: G. Richard Bellamy posted on Thu, 28 Aug 2014 07:48:04 -0700 as excerpted: > School is in again... and my goodness I learned a lot in this go-around. Don't worry, I did too. =:^) I consider myself an admin (as I believe everyone should who administrates their own systems, it's a big responsibility!) not a coder, and tho I can and do read/modify/create an occasional patch, I don't claim to do C/C++ code either. So I rarely actually look at sources. But I'm finding more sources make sense when I do, and Holger's post along with your straces was enough to get me digging in to see what's actually going on here, and that was quite enlightening on its own. Besides looking at code and actually finding I could make sense of it, I now understand a bit more of the dynamics of file size vs allocated size. I had no idea it was possible to fallocate beyond EOF like that, and simply reading the manpage wouldn't have gotten the point across NEARLY as well as actually seeing the change in ls -s, contrasted with the file size itself staying the same, as it did here. That's some potentially rather useful information I have safely tucked under my belt for future interpretation of "strange" filesize results, now, and it's all due to your posts along with Holger's reply, stimulating my own investigation. =:^) -- 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