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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D3AE0C433FE for ; Fri, 4 Nov 2022 07:06:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7wfuoqgLHu+7PG+WgqLUhnBYtbC2HW1/NOxjIygQkX4=; b=KaKZxLhY9Ud9MbV4od2PWB0BMB jo7dMfgrCGKJgO2mQ04yBEdQi2abaqIo9kjyq3svx8vZY4OfythS04SddIrxwHTkm0w6NktpSdtPE Xp0GhQlVwErM4nfyTyTuLhLYvcK/ww6nXzXgXekPPhEiJd4yIuJwX8eJzDHsgMGEpDGCv5boYadIH maUZlKLTkfcu3C8oJ7YhdnJ1ihk61vO5Fv90tlpRKw+feILwYGhrwFZCGzTHvlYKjYd1HSfRPUmo0 zsyZmgOfFhBbeULQzEtskarrbMuITk9wHc9b3R7A8ivbTxLryfNSdXeBuqKVfjMW0UXQcL4PggXer I/NiiuzA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqqmX-002iX3-S3; Fri, 04 Nov 2022 07:06:25 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqqmU-002iV1-Oe for linux-nvme@lists.infradead.org; Fri, 04 Nov 2022 07:06:24 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 6074D68AA6; Fri, 4 Nov 2022 08:06:17 +0100 (CET) Date: Fri, 4 Nov 2022 08:06:17 +0100 From: Christoph Hellwig To: "Martin K. Petersen" Cc: Christoph Hellwig , Keith Busch , sagi@grimberg.me, linux-nvme@lists.infradead.org Subject: Re: [PATCH] nvme: implement the DEAC bit for the Write Zeroes command Message-ID: <20221104070617.GB17463@lst.de> References: <20221030162906.3390-1-hch@lst.de> <20221101095804.GA13058@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221104_000622_977040_A964355B X-CRM114-Status: GOOD ( 17.62 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Nov 01, 2022 at 11:49:06AM -0400, Martin K. Petersen wrote: > Yep, but many device vendors messed that up due to the initial ambiguity > in the spec wrt. how to handle the UNMAP flag. Based on experience with > the SCSI UNMAP command being able to ignore blocks and ATA DSM TRIM > being non-deterministic, several vendors ended up not treating WRITE > SAME with the UNMAP flag set as a data integrity operation. Uh. > I was just concerned that this practice would carry over to NVMe. Bits > 2:0 being set to 1 is an indication that somebody at least thought about > this scenario during device implementation. But again, devices that > return non-zero blocks after deallocate are rare and we can always quirk > them if there's a problem. I'm fine with adding the dlfeat check - it is trivial and if the bits aren't set, sending the DEAC bit would be pointless anyway. It'll just make the people asking for names for the unnamed bits even more unhappy..