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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 22C05C64E7C for ; Wed, 2 Dec 2020 18:59:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ADA752173E for ; Wed, 2 Dec 2020 18:59:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387805AbgLBS7V (ORCPT ); Wed, 2 Dec 2020 13:59:21 -0500 Received: from bedivere.hansenpartnership.com ([96.44.175.130]:51356 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726104AbgLBS7V (ORCPT ); Wed, 2 Dec 2020 13:59:21 -0500 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 1346D1280953; Wed, 2 Dec 2020 10:58:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1606935521; bh=+v7ziyHZ2mHvnsQ8vpFfQDHBJJb35PBL7WMC6T1lrWg=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=MgoimLflKbYJC+ZUKSxOqD5bRKR3xb/h2dliM3eJLAUbvDKGt3LraKVGDKMDDvzYc EZojm7/anVXUEtHGlN0YXHuebcq9nrzHAWLAr33vf2TzJgM5u2EAFZZI7Y/kTblx85 /0ch2A0pPHpFPR7atBva+1bNVL4+571t0bzpifDY= Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 4fzyhjJZWr-5; Wed, 2 Dec 2020 10:58:41 -0800 (PST) Received: from jarvis.int.hansenpartnership.com (unknown [IPv6:2601:600:8280:66d1::527]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id B9AF51280948; Wed, 2 Dec 2020 10:58:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1606935520; bh=+v7ziyHZ2mHvnsQ8vpFfQDHBJJb35PBL7WMC6T1lrWg=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=xGjIdwcGECTGIGfrS8hKkVmUf9sjcs49eZxjb31iK7bAyWrHxrHYNv8U03mXGtaMi kxv/bFPBJKAJY8bBodYBIJnmtV+oMIe52SM8UZkPRCR2Sbij/rJ7cpBj0E9UCbrEKe so6sHNXaM/fLzHe+6fbDcC7EQpcpUpnAC0E7GEs8= Message-ID: <9a72bd02bd9230cc2258065faf01eb846530fd7d.camel@HansenPartnership.com> Subject: Re: Drive reset as an EH strategy when write cache is enabled From: James Bottomley To: Phillip Susi , Christoph Hellwig Cc: linux-ide@vger.kernel.org Date: Wed, 02 Dec 2020 10:58:39 -0800 In-Reply-To: <87blfc19u5.fsf@vps.thesusis.net> References: <87r1o9phgd.fsf@vps.thesusis.net> <20201202150330.GA25031@infradead.org> <87blfc19u5.fsf@vps.thesusis.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org On Wed, 2020-12-02 at 10:55 -0500, Phillip Susi wrote: > Christoph Hellwig writes: > > > If the device drops the content of the volatile write on a reset > > we'll have much problems than that.. > > How could it not? The write cache is empty after a power on reset > and certainly a "hard" reset should be the same as a power on reset. As Christoph said it would be stupid behaviour to invalidate the cache after a hard reset because it would cause all deferred writes to fail. The SCSI standards committee did initially assume manufacturers knew this, but it was codified in SBC-4 and beyond with an explicit list of conditions under which the write back cache could be lost, which doesn't include hard reset. James