Return-Path: linux-nfs-owner@vger.kernel.org Received: from smtp-out-04.shaw.ca ([64.59.134.12]:51978 "EHLO smtp-out-04.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754136Ab2EKJD4 convert rfc822-to-8bit (ORCPT ); Fri, 11 May 2012 05:03:56 -0400 Subject: Re: Extended file stat: Splitting file- and fs-specific info? Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii From: Andreas Dilger In-Reply-To: <20120510171016.B45BA2C096@topped-with-meat.com> Date: Fri, 11 May 2012 02:54:13 -0600 Cc: David Howells , Dave Chinner , "bfields@fieldses.org Fields" , "smfrench@gmail.com French" , "ben@decadent.org.uk Hutchings" , "Trond.Myklebust@netapp.com Myklebust" , "linux-fsdevel@vger.kernel.org Devel" , linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, "linux-ext4@vger.kernel.org List" , linux-api@vger.kernel.org, libc-alpha@sourceware.org Message-Id: <258C4ED4-2FB3-4E3F-A99E-842D231BA869@dilger.ca> References: <73759631-F1E4-4352-9FE6-E9F576F793FB@gmail.com> <20120419140558.17272.74360.stgit@warthog.procyon.org.uk> <16281.1336508382@redhat.com> <20120509002420.GL5091@dastard> <14477.1336641794@redhat.com> <20120510171016.B45BA2C096@topped-with-meat.com> To: Roland McGrath Sender: linux-nfs-owner@vger.kernel.org List-ID: On 2012-05-10, at 11:10 AM, Roland McGrath wrote: > POSIX specifies st_blksize thusly: "A file system-specific preferred > I/O block size for this object. In some file system types, this may > vary from file to file." > > Since there is only one available to POSIX applications, it should map > to the one that's described as "preferred IO size for general usage". Sure, but statxat() isn't a POSIX API. While I agree with the idea that there should be enough information about the underlying layout for applications to be able to submit good IO, it doesn't help if we have a bunch of extra fields that have vague meanings. They will get filled in by the filesystem in a haphazard way, and will not be used by application developers that don't understand what they mean. Cheers, Andreas