From owner-freebsd-questions Sun Aug 27 3:35:47 2000 Delivered-To: freebsd-questions@freebsd.org Received: from relay2.inwind.it (relay2.inwind.it [212.141.53.73]) by hub.freebsd.org (Postfix) with ESMTP id 9039337B43C for ; Sun, 27 Aug 2000 03:35:41 -0700 (PDT) Received: from localhost (212.141.78.209) by relay2.inwind.it (5.1.039) id 399BF830000A6DFC; Sun, 27 Aug 2000 12:35:01 +0200 From: Salvo Bartolotta Date: Sun, 27 Aug 2000 09:35:07 GMT Message-ID: <20000827.9350700@mis.configured.host> Subject: mount -u potential problems (?) (was Re: read only / filesystem) To: Greg Lehey Cc: freebsd-questions@FreeBSD.ORG In-Reply-To: <20000827160325.D88160@wantadilla.lemis.com> References: <78875170@toto.iv> <14760.37457.359972.176638@guru.mired.org> <20000827135500.A88160@wantadilla.lemis.com> <14760.45477.402050.39137@guru.mired.org> <20000827160325.D88160@wantadilla.lemis.com> X-Mailer: SuperCalifragilis X-Priority: 3 (Normal) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<< On 8/27/00, 7:33:25 AM, Greg Lehey wrote regarding Re: = read only / filesystem: > On Sunday, 27 August 2000 at 1:13:57 -0500, Mike Meyer wrote: > > Greg Lehey writes: > >> On Saturday, 26 August 2000 at 23:00:17 -0500, Mike Meyer wrote: > >>> Greg Lehey writes: > >>>> On Thursday, 24 August 2000 at 23:49:17 -0700, R Joseph Wright=20 wrote: > >>>>> Or is it easy enough to simply remount / rw when changes to /etc= =20 are > >>>>> needed? > >>>> You can do this, but you can't go back to an ro mount. > >>> Uh - why not? > >> It's not reliable. There are some problems with dirty buffers when= > >> you make the file system read-only again. I forget whether it's da= ta > >> corruption or a panic, but the only safe way to do this is to umoun= t > >> the file system and remount it r/o, obviously not an option here. > > > > Sounds like an OS bug. The mount system call should make sure the fi= le > > system is in sync before doing the udpate mount. You could, of cours= e, > > do the sync's by hand until that happens. > Sure, it's a bug. But it's not one that interests many people, so > nobody has fixed it. Don't underestimate its complexity. > Greg > -- I seemed to understand that the reversion was **ONLY** dangerous if=20 the "-f" ("force") option had been specified; at least, that is what I=20 was expressly told not long ago. Now I am just a little more confused :-) Best regards, Salvo To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message