From: Andrew Morton Subject: Re: [PATCH 0/3] Fiemap, an extent mapping ioctl Date: Wed, 10 Sep 2008 11:46:12 -0700 Message-ID: <20080910114612.314978a8.akpm@linux-foundation.org> References: <20080825202250.GY3392@webber.adilger.int> <20080910124005.GA4563@wotan.suse.de> <20080910124934.GB4563@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , Eric Sandeen , linux-ext4@vger.kernel.org To: Mark Fasheh Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:55200 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751377AbYIJSqb (ORCPT ); Wed, 10 Sep 2008 14:46:31 -0400 In-Reply-To: <20080910124934.GB4563@wotan.suse.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, 10 Sep 2008 05:49:34 -0700 Mark Fasheh wrote: > Hello, > > The following patches are the latest attempt at implementing a > fiemap ioctl, which can be used by userspace software to get extent > information for an inode in an efficient manner. As these are applicable to all filesystems, Cc:ing only linux-ext4 is not sufficient. All filesystem developers (at least) need an opportunity to review and understand these changes. > > ... > > The fiemap ioctl is an efficient method for userspace to get file > extent mappings. Instead of block-by-block mapping (such as bmap), fiemap > returns a list of extents. > The above is, afacit, the only offered rationale for the addition of these new feature. I don't recall seeing anyone complain about bmap() inefficiency. In fact I rarely hear of anyone using bmap() at all. This rationale needs expanding, please. A lot.