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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB5B2C6FA8F for ; Wed, 30 Aug 2023 18:44:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238990AbjH3Sji (ORCPT ); Wed, 30 Aug 2023 14:39:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243680AbjH3L1s (ORCPT ); Wed, 30 Aug 2023 07:27:48 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BD3C1B0; Wed, 30 Aug 2023 04:27:45 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4RbMNG5m90z6K6J8; Wed, 30 Aug 2023 19:22:54 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Wed, 30 Aug 2023 12:27:42 +0100 Date: Wed, 30 Aug 2023 12:27:41 +0100 From: Jonathan Cameron To: Ira Weiny CC: Dan Williams , Navneet Singh , Fan Ni , Davidlohr Bueso , Dave Jiang , Alison Schofield , Vishal Verma , , Subject: Re: [PATCH RFC v2 13/18] dax/bus: Factor out dev dax resize logic Message-ID: <20230830122741.00007628@Huawei.com> In-Reply-To: <20230604-dcd-type2-upstream-v2-13-f740c47e7916@intel.com> References: <20230604-dcd-type2-upstream-v2-0-f740c47e7916@intel.com> <20230604-dcd-type2-upstream-v2-13-f740c47e7916@intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml500002.china.huawei.com (7.191.160.78) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 28 Aug 2023 22:21:04 -0700 Ira Weiny wrote: > Dynamic Capacity regions must limit dev dax resources to those areas > which have extents backing real memory. Four alternatives were > considered to manage the intersection of region space and extents: > > 1) Create a single region resource child on region creation which > reserves the entire region. Then as extents are added punch holes in > this reservation. This requires new resource manipulation to punch > the holes and still requires an additional iteration over the extent > areas which may already have existing dev dax resources used. > > 2) Maintain an ordered xarray of extents which can be queried while > processing the resize logic. The issue is that existing region->res > children may artificially limit the allocation size sent to > alloc_dev_dax_range(). IE the resource children can't be directly > used in the resize logic to find where space in the region is. > > 3) Maintain a separate resource tree with extents. This option is the > same as 2) but with a different data structure. Most ideally we have > some unified representation of the resource tree. > > 4) Create region resource children for each extent. Manage the dax dev > resize logic in the same way as before but use a region child > (extent) resource as the parents to find space within each extent. > > Option 4 can leverage the existing resize algorithm to find space within > the extents. > > In preparation for this change, factor out the dev_dax_resize logic. > For static regions use dax_region->res as the parent to find space for > the dax ranges. Future patches will use the same algorithm with > individual extent resources as the parent. > > Signed-off-by: Ira Weiny Hi Ira, Some trivial comments on comments, but in general this indeed seems to be doing what you say and factoring out the static allocation part. Reviewed-by: Jonathan Cameron > --- > drivers/dax/bus.c | 128 +++++++++++++++++++++++++++++++++--------------------- > 1 file changed, 79 insertions(+), 49 deletions(-) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index b76e49813a39..ea7ae82b4687 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -817,11 +817,10 @@ static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id) > return 0; > } > > -static ssize_t dev_dax_resize(struct dax_region *dax_region, > - struct dev_dax *dev_dax, resource_size_t size) > +/* /** Suitable builds will then check this doc matches the function etc even if this is never included into any of the docs build. > + * dev_dax_resize_static - Expand the device into the unused portion of the > + * region. This may involve adjusting the end of an existing resource, or > + * allocating a new resource. > + * > + * @parent: parent resource to allocate this range in. > + * @dev_dax: DAX device we are creating this range for Trivial: Doesn't seem to be consistent on . or not > + * @to_alloc: amount of space to alloc; must be <= space available in @parent > + * > + * Return the amount of space allocated or -ERRNO on failure > + */ > +static ssize_t dev_dax_resize_static(struct resource *parent, > + struct dev_dax *dev_dax, > + resource_size_t to_alloc)