Received: by 2002:ac0:a5a6:0:0:0:0:0 with SMTP id m35-v6csp13536imm; Wed, 5 Sep 2018 12:54:38 -0700 (PDT) X-Google-Smtp-Source: ANB0VdahJSGwJyBFTT8GPO0zfvGsjymT6yq0n6hudHrQGhkR8YBzReR8fgVuATcgnkj1/8+P+huy X-Received: by 2002:a63:6849:: with SMTP id d70-v6mr37570813pgc.7.1536177278676; Wed, 05 Sep 2018 12:54:38 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1536177278; cv=none; d=google.com; s=arc-20160816; b=CAmxWIitoVjiSTcYwIQBO/uWeEiojkTAf7+/qcTZdzviqraq0Gn7hJfNRHiIwvt2fZ cqzVNlYDcXp52RqvjfALo86eOFWFIaqZ+74bNB87wGifFeMBK6Dml857ANVKvzxfxRbU qeIGlfB17PSbwx0VeauundvvJlLGR7Vz2puuSTtsepuOUCG4Fru+Okc/1JCFiU9LARzS /qSfaJSkhKkaXE2FC4FEE8w8EuUD8M0C6Lf6wcLU4igAaw1UMg6mDVxvlyNI+UOzqYZI HblIDttjnzyvdwShr7NJTcJIIVS859TKUaSl6b0W/iscJ50KEcj0HCkWT0RoM8Lb7km5 TOYA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=txOcUSP4gUEl4NQgXHj4wfLnVbUAE+dbK2k6tGFTvDI=; b=c+D+T4Q899jj/KGHDabpmy3URZmsH+8OKBy5b5qBMrR9MZmvzGi7cAOMEAjbE1bKpe UukDI6lH+R1BIO/eKvOqBjLjlZ5NGqhNLTivDhwQ26PqlcJOMlQi3mnKm64yoYkpEi/N PldGQHloGaxo7T7cLeB4BenEOPg8ZrLtc91ZnIXLR6l5ERiXGObhJt33r14+ZWtIie/U 4gt0sz85LfSeR2B5Y8r1jz37VblOBLaNqbhs3ytErfIpwf3CE8a2JDLdVm3S9+PE3jHd FSzSbBk3HztNpCc3o2VNlrTrTHW8EoLGqWSQQ90lf+teHXvEGu5ZHqpWc27A/rvyY0yf rs+Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y10-v6si2899021pgf.312.2018.09.05.12.54.23; Wed, 05 Sep 2018 12:54:38 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727827AbeIFAYv (ORCPT + 99 others); Wed, 5 Sep 2018 20:24:51 -0400 Received: from verein.lst.de ([213.95.11.211]:47027 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727364AbeIFAYv (ORCPT ); Wed, 5 Sep 2018 20:24:51 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id 96C0568D40; Wed, 5 Sep 2018 21:56:47 +0200 (CEST) Date: Wed, 5 Sep 2018 21:56:47 +0200 From: Christoph Hellwig To: Jens Axboe Cc: Logan Gunthorpe , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org, Stephen Bates , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?iso-8859-1?B?Suly9G1l?= Glisse , Benjamin Herrenschmidt , Alex Williamson , Christian =?iso-8859-1?Q?K=F6nig?= Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests Message-ID: <20180905195647.GA1626@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 05, 2018 at 01:45:04PM -0600, Jens Axboe wrote: > The point is that the caller doesn't necessarily know where the bio > will end up, hence the caller can't fully check if the whole stack > supports P2P. The caller must necessarily know where the bio will end up, as for P2P support we need to query if the bio target is P2P capable vs the source of the P2P memory.