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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,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 231E9C282DD for ; Thu, 23 May 2019 04:02:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E360E2175B for ; Thu, 23 May 2019 04:02:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="oTE2W0bR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726310AbfEWECy (ORCPT ); Thu, 23 May 2019 00:02:54 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:32862 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725792AbfEWECy (ORCPT ); Thu, 23 May 2019 00:02:54 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4N3sLwU086500; Thu, 23 May 2019 04:02:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=SpnlCnP/O9ZkZqlUX+vUBOkfGqSOfQHrVg1yrZjTXDs=; b=oTE2W0bRi34AyZgfWmQVQXAA9VcxLbzdRVkX62uTll9zZaiizxf3pTqA/8pLxO6Bvtm1 5G8ay60GkxkeA1qKuLHSprf6I5n3tgxMFgPgo/29ornRWhXDrhhDFhuw2m21q/8zk8aV jOwz2AcWjgaW5wsZMfKZcS2DsyTozukLooud+NA4zAaR/E/kBf/WKN4AHl3bM2H8fI8e 4qa2CDDPJkrs/jWOUgZusfpcr/15TJjGuz1Bn00/R7PhQg8W3xFSuJ7s+DDwURpzNlgJ 7K1ebwmAMxYGh317Cx0kswnL+dEzOwdZVP3lNYXU06Y9mvMCb0vn80xYwnM292TdCVTA Rg== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2130.oracle.com with ESMTP id 2smsk5fnm1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 23 May 2019 04:02:15 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4N41YAS070556; Thu, 23 May 2019 04:02:15 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 2smsgt0ae9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 23 May 2019 04:02:15 +0000 Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x4N424Jj030507; Thu, 23 May 2019 04:02:04 GMT Received: from localhost (/10.159.244.226) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 23 May 2019 04:02:03 +0000 Date: Wed, 22 May 2019 21:02:02 -0700 From: "Darrick J. Wong" To: Goldwyn Rodrigues Cc: linux-btrfs@vger.kernel.org, kilobyte@angband.pl, linux-fsdevel@vger.kernel.org, jack@suse.cz, david@fromorbit.com, willy@infradead.org, hch@lst.de, dsterba@suse.cz, nborisov@suse.com, linux-nvdimm@lists.01.org Subject: Re: [PATCH 08/18] dax: memcpy page in case of IOMAP_DAX_COW for mmap faults Message-ID: <20190523040202.GH5125@magnolia> References: <20190429172649.8288-1-rgoldwyn@suse.de> <20190429172649.8288-9-rgoldwyn@suse.de> <20190521174625.GF5125@magnolia> <20190522191139.62v2rgby5ptjhzcd@fiona> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190522191139.62v2rgby5ptjhzcd@fiona> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9265 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905230026 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9265 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905230026 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, May 22, 2019 at 02:11:39PM -0500, Goldwyn Rodrigues wrote: > On 10:46 21/05, Darrick J. Wong wrote: > > On Mon, Apr 29, 2019 at 12:26:39PM -0500, Goldwyn Rodrigues wrote: > > > From: Goldwyn Rodrigues > > > > > > Change dax_iomap_pfn to return the address as well in order to > > > use it for performing a memcpy in case the type is IOMAP_DAX_COW. > > > We don't handle PMD because btrfs does not support hugepages. > > > > > > Question: > > > The sequence of bdev_dax_pgoff() and dax_direct_access() is > > > used multiple times to calculate address and pfn's. Would it make > > > sense to call it while calculating address as well to reduce code? > > > > > > Signed-off-by: Goldwyn Rodrigues > > > --- > > > fs/dax.c | 19 +++++++++++++++---- > > > 1 file changed, 15 insertions(+), 4 deletions(-) > > > > > > diff --git a/fs/dax.c b/fs/dax.c > > > index 610bfa861a28..718b1632a39d 100644 > > > --- a/fs/dax.c > > > +++ b/fs/dax.c > > > @@ -984,7 +984,7 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) > > > } > > > > > > static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, > > > - pfn_t *pfnp) > > > + pfn_t *pfnp, void **addr) > > > { > > > const sector_t sector = dax_iomap_sector(iomap, pos); > > > pgoff_t pgoff; > > > @@ -996,7 +996,7 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, > > > return rc; > > > id = dax_read_lock(); > > > length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), > > > - NULL, pfnp); > > > + addr, pfnp); > > > if (length < 0) { > > > rc = length; > > > goto out; > > > @@ -1286,6 +1286,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > > > XA_STATE(xas, &mapping->i_pages, vmf->pgoff); > > > struct inode *inode = mapping->host; > > > unsigned long vaddr = vmf->address; > > > + void *addr; > > > loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; > > > struct iomap iomap = { 0 }; > > > > Ugh, I had forgotten that fs/dax.c open-codes iomap_apply, probably > > because the actor returns vm_fault_t, not bytes copied. I guess that > > makes it a tiny bit more complicated to pass in two (struct iomap *) to > > the iomap_begin function... > > I am not sure I understand this. We do not use iomap_apply() in > the fault path: dax_iomap_pte_fault(). We just use iomap_begin() > and iomap_end(). So, why can we not implement your idea of using two > iomaps? Oh, sorry, I wasn't trying to say that calling ->iomap_begin made it *impossible* to implement. I was merely complaining about the increased maintenance burden that results from open coding -- now there are three places where we have to change a struct iomap declaration, not one (iomap_apply) as I had originally thought. > What does open-coding iomap-apply mean? Any function that calls (1) ->iomap_begin; (2) performs an action on the returned iomap; and (3) then calls calling ->iomap_end. That's what iomap_apply() does. Really I'm just being maintainer-cranky. Ignore me for now. :) --D > > -- > Goldwyn