From: "J. Bruce Fields" Subject: Re: [RFC][PATCH 0/5] NFS: trace points added to mounting path Date: Fri, 23 Jan 2009 13:09:59 -0500 Message-ID: <20090123180959.GA32186@fieldses.org> References: <5B2817A2-B0FF-4FB5-9244-9E13C55EF6B2@oracle.com> <497757D1.7090908@RedHat.com> <49777988.6010401@RedHat.com> <4977A385.8000406@melbourne.sgi.com> <20090121225619.GI4295@fieldses.org> <497897F5.9030005@RedHat.com> <20090122164503.GC13129@fieldses.org> <4978F91C.4090208@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Steve Dickson , Linux NFS Mailing list , SystemTAP , Linux NFSv4 mailing list To: Greg Banks Return-path: Received: from mail.fieldses.org ([141.211.133.115]:35569 "EHLO pickle.fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753035AbZAWSJ7 (ORCPT ); Fri, 23 Jan 2009 13:09:59 -0500 In-Reply-To: <4978F91C.4090208-cP1dWloDopni96+mSzHFpQC/G2K4zDHf@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Jan 23, 2009 at 09:54:20AM +1100, Greg Banks wrote: > J. Bruce Fields wrote: > > On Thu, Jan 22, 2009 at 10:59:49AM -0500, Steve Dickson wrote: > > > >> J. Bruce Fields wrote: > >> > >> > >> Interesting.... Store something like a reason code (similar to what they have > >> in he Kerberos) > >> > > > > Maybe. > > > > > >> in somewhere in the proc file system? > >> > > > > But then I don't know how you'd associate it with a particular mount > > attempt. > > > > > > > You could do something truly awful like add a new code in the unused > bits of the errno value returned from mount. It would confuse an > unmodified userspace, but reporting "Unknown Error" isn't much less > useful than "I/O Error". There must be cases where the existing error gives us some information, but not as much as we'd like, so the "Unknown Error" could be a step backwards for unmodified userspace. An extra mount option (normally hidden from the user) could be used to tell the kernel that the application doing the mount was capable of handling the new error codes. Ugh. --b.