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 AB011C433EF for ; Mon, 11 Jul 2022 20:24:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230036AbiGKUY6 (ORCPT ); Mon, 11 Jul 2022 16:24:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229745AbiGKUY6 (ORCPT ); Mon, 11 Jul 2022 16:24:58 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D47E2717E; Mon, 11 Jul 2022 13:24:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=GpUxC4xM2q0YHyxeurm32X0RDwIgOBVOHXbx9JCax3s=; b=qoM8VEm+ykd3JseVkxElopsHN0 HDA+4r27tlPXq4X28R6Ly4e45e7EhW1MCqP3iepZXuYstAXEyCpFmQ80OhUVx0khdSKSTcB9jaCi1 aB7U0Ona0i28+mZ5YEofqmzJoWURRdJ9WBhRcWuBs/LkTWFCmyiZXuRn72ghKOxGM4iPULOXnaF0k ACpyM168x8fsS2MFOOMPa37HgV48OQYc87dGxGwPcSG6rBeUaTrvn+eXYvQfxdoEiy6Uq/ETa6Rvg Cxwd5csG7Exks19VF1zGH68oOZB9Wr8vFp89PCKjioyC+Ueju4NRG62HlfoKZzL9bFi2n/f4lJDdQ rQyd9/PA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oAzxd-006G6r-1S; Mon, 11 Jul 2022 20:24:53 +0000 Date: Mon, 11 Jul 2022 21:24:53 +0100 From: Matthew Wilcox To: Brian Foster Cc: Christian Brauner , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ikent@redhat.com, onestero@redhat.com Subject: Re: [PATCH 1/3] radix-tree: propagate all tags in idr tree Message-ID: References: <20220614180949.102914-1-bfoster@redhat.com> <20220614180949.102914-2-bfoster@redhat.com> <20220628125511.s2frv6lw7zgyzou5@wittgenstein> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jun 28, 2022 at 10:53:50AM -0400, Brian Foster wrote: > On Tue, Jun 28, 2022 at 02:55:11PM +0200, Christian Brauner wrote: > > On Wed, Jun 15, 2022 at 05:34:02PM +0100, Matthew Wilcox wrote: > > > On Wed, Jun 15, 2022 at 10:43:33AM -0400, Brian Foster wrote: > > > > Interesting, thanks. I'll have to dig more into this to grok the current > > > > state of the radix-tree interface vs. the underlying data structure. If > > > > I follow correctly, you're saying the radix-tree api is essentially > > > > already a translation layer to the xarray these days, and we just need > > > > to move legacy users off the radix-tree api so we can eventually kill it > > > > off... > > > > > > If only it were that easy ... the XArray has a whole bunch of debugging > > > asserts to make sure the users are actually using it correctly, and a > > > lot of radix tree users don't (they're probably not buggy, but they > > > don't use the XArray's embedded lock). > > > > > > Anyway, here's a first cut at converting the PID allocator from the IDR > > > to the XArray API. It boots, but I haven't tried to do anything tricky > > > with PID namespaces or CRIU. > > > > It'd be great to see that conversion done. > > Fwiw, there's test cases for e.g. nested pid namespace creation with > > specifically requested PIDs in > > > > Ok, but I'm a little confused. Why open code the xarray usage as opposed > to work the idr bits closer to being able to use the xarray api (and/or > work the xarray to better support the idr use case)? I see 150+ callers > of idr_init(). Is the goal to eventually open code them all? That seems > a lot of potential api churn for something that is presumably a generic > interface (and perhaps inconsistent with ida, which looks like it uses > xarray directly?), but I'm probably missing details. It's not "open coding". It's "using the XArray API instead of the IDR API". The IDR API is inferior in a number of ways, and yes, I do want to be rid of it entirely.