From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CBCFC43334 for ; Tue, 4 Sep 2018 21:02:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC91C20836 for ; Tue, 4 Sep 2018 21:02:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NDtkyT27" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC91C20836 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727586AbeIEB3f (ORCPT ); Tue, 4 Sep 2018 21:29:35 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:49494 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726426AbeIEB3f (ORCPT ); Tue, 4 Sep 2018 21:29:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=SqTaK0f+gPcLglrLxtx08/OQOZukSmXCToV/jY2maik=; b=NDtkyT27IBvTjW0MQLQByTyIe 2v8+nVFjVGXqKB97SfemFixBc2lJa2d/0VlS9cZDBpt/waONewN+Z/1V+61uDgA3wWIxxcybcafU1 VN8N0sTcLuTb+EKs11ceOeMZmNMAQ4GQfBcoy9zgNDXM2uZ/fWXIRu4nMkgtF8+s2zT+8S62/Q7qD U/GHIuyuxSc/n8/qV0ZIqkhNeeDqKh6RDaJ187aWKbmTPtNYJeOeiMeg3jCReb20ZKQ7r9bVcPg5x rZaFk7kFmmoq3fep1XZNZlMz1Nx+oiRe1LNzbDhduRGP9kRsSRisAzGz9PjHqwFDJF2M6He1/gswR ezDobFBYQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fxIT7-0004vr-H7; Tue, 04 Sep 2018 21:02:37 +0000 Date: Tue, 4 Sep 2018 14:02:37 -0700 From: Matthew Wilcox To: Vito Caputo Cc: Jeff Layton , "J. Bruce Fields" , Rogier Wolff , =?utf-8?B?54Sm5pmT5Yas?= , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: POSIX violation by writeback error Message-ID: <20180904210237.GA12303@bombadil.infradead.org> References: <20180904075347.GH11854@BitWizard.nl> <82ffc434137c2ca47a8edefbe7007f5cbecd1cca.camel@redhat.com> <20180904161203.GD17478@fieldses.org> <20180904162348.GN17123@BitWizard.nl> <20180904185411.GA22166@fieldses.org> <20180904203534.yumaest6v5p6izln@shells.gnugeneration.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180904203534.yumaest6v5p6izln@shells.gnugeneration.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 04, 2018 at 01:35:34PM -0700, Vito Caputo wrote: > Implement a new class of swap space for backing dirty pages which fail > to write back. Pages in this space survive reboots, essentially backing > the implicit commitment POSIX establishes in the face of asynchronous > writeback errors. Rather than evicting these pages as clean, they are > swapped out to the persistent swap. You not only need to track which index within a file this swapped page belongs to but also which file. And that starts to get tricky. It may or may not have a name; it may or may not have a persistent inode number; it may or may not have a persistent fhandle. If it's on network storage, it may have been modified by another machine. If it's on removable storage, it may have been modified by another machine.