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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 A6504C04AB5 for ; Thu, 6 Jun 2019 19:46:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 782EE206BB for ; Thu, 6 Jun 2019 19:46:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="eoZ3O1Re" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727436AbfFFTqy (ORCPT ); Thu, 6 Jun 2019 15:46:54 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:40446 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726997AbfFFTqy (ORCPT ); Thu, 6 Jun 2019 15:46:54 -0400 Received: by mail-qt1-f194.google.com with SMTP id a15so4125915qtn.7 for ; Thu, 06 Jun 2019 12:46:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=qajFXRwDSumJ1VBt1nbVb8YwByztvxS980sXRo7osmo=; b=eoZ3O1RetGytNaHJt1/lQ055Dyp4yKlZbucZb+BvUi5davTaqNwzsojRJaEX3o7YBt pW3kUz6Q6eZ28rLtA9Jjv3JM9Jbd8rpL+tsDn7iM2UqXOLGkn166O+4yvLdC3Kj1J1Kw EN/awr72rkEt7yQR+AiRXrTbLCAXuw/PReh8Jee8gULLsUma+/gjV4ptkpnFqaWY9ScQ pfzfEEURVPjfvQ17a2N2djx/e2F+JgvAKdq7T0ZC0+SYGMwKMi53TV6yqzPwuSf8v+9u LYyAO6rl9kNxn5WFf8W3yFzNwERteSui2pJz14BOr2RQ5bfl/hj47SMCT66KbVbY4Rcp hJzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=qajFXRwDSumJ1VBt1nbVb8YwByztvxS980sXRo7osmo=; b=n3TaN9co5N1F/gRqSWmvzrUT6NJOYkTnS9IqO0OlNwxxwyFOg/6WBBWi/+MaIh/1s5 QqlVfsiLH8T3I7s+M7ihIAKjhdpPWQeIM6VGzqiUmyQ0cRnNWiLchG6QFxXkvMHSgfz3 hZGhrr+Q9XXWHQl/oxAebYAUFQjm9+d6rORGqI0AIiyuR//Tu+1+1Oz0a+S1nUOJw1pQ vH57fAVHFJegJV9nqjlMdsVEfpxB1RN0YOyO1YMydcLryEqHx6XxauJoxi0G4kf0xz/1 7037ULd5K5zApT4klsnR1R2tVdeuqy8i8IF+3EnYfJmBvX9NLvmcagx/X05adBmJYBNW 5mjQ== X-Gm-Message-State: APjAAAXWExmRdWzHWY0zR4PhgQUhep7pmmT8y9+vLl0tcv+dhflMBIAr BhWjIJZsn55cxVJXn1AEwV21IA== X-Google-Smtp-Source: APXvYqzAxBsAbtmAf/N2gWiDpLiwySAazMdlavwrTbL7etxy94AKJa3CMpYnlx0qPyIVzWATublI1w== X-Received: by 2002:a0c:d0b6:: with SMTP id z51mr27514879qvg.3.1559850413173; Thu, 06 Jun 2019 12:46:53 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-55-100.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.55.100]) by smtp.gmail.com with ESMTPSA id t197sm1407918qke.2.2019.06.06.12.46.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 06 Jun 2019 12:46:52 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hYyLc-0007zs-5h; Thu, 06 Jun 2019 16:46:52 -0300 Date: Thu, 6 Jun 2019 16:46:52 -0300 From: Jason Gunthorpe To: Ira Weiny Cc: John Hubbard , Dan Williams , Jan Kara , Theodore Ts'o , Jeff Layton , Dave Chinner , Matthew Wilcox , linux-xfs@vger.kernel.org, Andrew Morton , =?utf-8?B?SsOpcsO0bWU=?= Glisse , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH RFC 00/10] RDMA/FS DAX truncate proposal Message-ID: <20190606194652.GI17373@ziepe.ca> References: <20190606014544.8339-1-ira.weiny@intel.com> <20190606171158.GB11374@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190606171158.GB11374@iweiny-DESK2.sc.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Jun 06, 2019 at 10:11:58AM -0700, Ira Weiny wrote: > 2) This is a bit more subtle and something I almost delayed sending these out > for. Currently the implementation of a lease break actually removes the > lease from the file. I did not want this to happen and I was thinking of > delaying this patch set to implement something which keeps the lease around > but I figured I should get something out for comments. Jan has proposed > something along these lines and I agree with him so I'm going to ask you to > read my response to him about the details. > > > Anyway so the key here is that currently an app needs the SIGIO to retake > the lease if they want to map the file again or in parts based on usage. > For example, they may only want to map some of the file for when they are > using it and then map another part later. Without the SIGIO they would lose > their lease or would have to just take the lease for each GUP pin (which > adds overhead). Like I said I did not like this but I left it to get > something which works out. So to be clear.. Even though the lease is broken the GUP remains, the pages remain pined, and truncate/etc continues to fail? I like Jan's take on this actually.. see other email. Jason