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 85607C47258 for ; Thu, 25 Jan 2024 08:13:01 +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=PH3OTw5I1+Rw/5v3dWuEHJc9vjwt6dMfoe5KVEFKi0E=; b=x3TIfqHNjtcrCJWy4v5MYN51As l6RTIsn/g0r4FDlZEAVLe0G2AYPIU5Cm9caK89IhLyTvD8RhhLIjFtxwjUdi4q5NfK5Gm5Aj8+O63 gVJOmM57Si9v4xGzClWtrKusBYHZZlx+ay0ly4SAzXa92Tx8i3e6Xinn1no42tFx2I5JcYoCxRzBp x43eBm+33cTKj4l58IVQLtqgJKKNy8Y6sIqj3+6+CcxUp3GxbwKZGhOFBKrYZwIC1wGLXhG7xuV7B ufC9Ptrp20oD02raFhbMT4nbkhCkZcop6IUSx/PC8oOR6p0LQZ+o1GdEVO/0kuPVO2x4Uuk+jKUeV hToQ+paw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rSur3-007Flw-1X; Thu, 25 Jan 2024 08:12:57 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rSuqz-007FjA-2N for linux-nvme@lists.infradead.org; Thu, 25 Jan 2024 08:12:55 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 6FB1D67373; Thu, 25 Jan 2024 09:12:42 +0100 (CET) Date: Thu, 25 Jan 2024 09:12:42 +0100 From: Christoph Hellwig To: Keith Busch Cc: Christoph Hellwig , Jens Axboe , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Paolo Bonzini , Stefan Hajnoczi , "Martin K. Petersen" , Damien Le Moal , Sagi Grimberg , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, virtualization@lists.linux.dev Subject: Re: [PATCH 05/15] block: add a max_user_discard_sectors queue limit Message-ID: <20240125081242.GB21006@lst.de> References: <20240122173645.1686078-1-hch@lst.de> <20240122173645.1686078-6-hch@lst.de> <20240122183857.GA7029@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-20240125_001253_943220_D29D9441 X-CRM114-Status: GOOD ( 16.37 ) 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 Wed, Jan 24, 2024 at 08:44:16AM -0700, Keith Busch wrote: > > > > + min_not_zero(q->limits.max_hw_discard_sectors, > > > > + q->limits.max_user_discard_sectors); > > > > > > Shouldn't writing 0 disable discards? > > > > I mirror the max_user_sectors behavior here, where 0 disables the > > user limiting. But yes, that would be a behavior change. > > But a user should be able to disable discards, right? Unless you really > want to match max_user_sectors, I think you could default the user > setting here to UINT_MAX and use "min" instead of "min_not_zero". Not a fan of having different semantics for the different attributes, but given that we've had this or 9 years we better stick to it, so I'll change it.