From owner-freebsd-hackers Sat Oct 19 21:57:43 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6AB0537B401; Sat, 19 Oct 2002 21:57:42 -0700 (PDT) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 16A2C43E9C; Sat, 19 Oct 2002 21:57:42 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.5/8.12.4) with ESMTP id g9K4vdPQ030664; Sat, 19 Oct 2002 21:57:39 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.5/8.12.4/Submit) id g9K4vbAE030661; Sat, 19 Oct 2002 21:57:37 -0700 (PDT) (envelope-from dillon) Date: Sat, 19 Oct 2002 21:57:37 -0700 (PDT) From: Matthew Dillon Message-Id: <200210200457.g9K4vbAE030661@apollo.backplane.com> To: David Schultz Cc: Poul-Henning Kamp , Maxim Sobolev , hackers@FreeBSD.ORG Subject: Re: Patch to allow a driver to report unrecoverable write errors to the buf layer References: <3DB048B5.21097613@FreeBSD.org> <28472.1035014051@critter.freebsd.dk> <20021020043706.GA23972@HAL9000.homeunix.com> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG :filesystem corruption because the vnode layer would be unaware :that some buffers had been dropped. How hard would it be to fix this? Extremely difficult, which is why this is all fantasy and no action. By the time the filesystem layer gets the notification there is insufficient information to unwind the original operation(s) without a huge amount of work. A bitmap write failed? Great! Find the file that the related bitmap blocks are related to. Good luck! And that is just one case out of dozens that would require a sophisticated solution. It might be possible via softupdates, but I shudder at the level of complexity of code required to support such a beast. Not to mention the fact that pulling a floppy out a bad time could destroy far more data then whatever pending write operations might have failed. It's a waste of time. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message