Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751335AbVJKBHy (ORCPT ); Mon, 10 Oct 2005 21:07:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751334AbVJKBHy (ORCPT ); Mon, 10 Oct 2005 21:07:54 -0400 Received: from smtp.osdl.org ([65.172.181.4]:17296 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751332AbVJKBHx (ORCPT ); Mon, 10 Oct 2005 21:07:53 -0400 Date: Mon, 10 Oct 2005 18:07:05 -0700 From: Andrew Morton To: Mikulas Patocka Cc: aia21@cam.ac.uk, glommer@br.ibm.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, ext2-devel@lists.sourceforge.net, hirofumi@mail.parknet.co.jp, linux-ntfs-dev@lists.sourceforge.net, aia21@cantab.net, hch@infradead.org, viro@zeniv.linux.org.uk Subject: Re: [PATCH] Use of getblk differs between locations Message-Id: <20051010180705.0b0e3920.akpm@osdl.org> In-Reply-To: References: <20051010204517.GA30867@br.ibm.com> <20051010214605.GA11427@br.ibm.com> <20051010223636.GB11427@br.ibm.com> <20051010163648.3e305b63.akpm@osdl.org> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1598 Lines: 38 Mikulas Patocka wrote: > > On Mon, 10 Oct 2005, Andrew Morton wrote: > > > Anton Altaparmakov wrote: > >> > >> > Maybe the best solution is neither one nor another. Testing and failing > >> > gracefully seems better. > >> > > >> > What do you think? > >> > >> I certainly agree with you there. I neither want a deadlock nor > >> corruption. (-: > > > > Yup. In the present implementation __getblk_slow() "cannot fail". It's > > conceivable that at some future stage we'll change __getblk_slow() so that > > it returns NULL on an out-of-memory condition. > > The question is if it is desired --- it will make bread return NULL on > out-of-memory condition, callers will treat it like an IO error, skipping > access to the affected block, causing damage on perfectly healthy > filesystem. Yes, that is a bit dumb. A filesystem might indeed want to take different action for ENOMEM versus EIO. > I liked what linux-2.0 did in this case --- if the kernel was out of > memory, getblk just took another buffer, wrote it if it was dirty and used > it. Except for writeable loopback device (where writing one buffer > generates more dirty buffers), it couldn't deadlock. Wouldn't it be better if bread() were to return ERR_PTR(-EIO) or ERR_PTR(-ENOMEM)? Big change. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/