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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 5247EC04AAF for ; Tue, 21 May 2019 20:00:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 197F4217F9 for ; Tue, 21 May 2019 20:00:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="QiopMVtd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727634AbfEUUAJ (ORCPT ); Tue, 21 May 2019 16:00:09 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:54340 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727222AbfEUUAJ (ORCPT ); Tue, 21 May 2019 16:00:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=2WyprSMw0XFiETzAPNoNDTntzyZkEUNNpfxivfnIFag=; b=QiopMVtd93jBeeZmGnTEUvoiY vTPJBvJYi5LOSLhmJkqq10H0GkG3Ybuyy2GgEBBiF6ACrbhxxgV/cxaVIjW/Rpjp1yKFHUZAv1Rzs o1M82BikP7PxF4SKNxlHxXnX3FiPFbC3GuT6o/Xx4fpryP3q4N96k+ORmXqwzQ/wBAmTBfLHHeQeL pscG03ZyLkH3VoNLwDaRa2+XwwmT02a/YpHBEuyfMmby5LJOqSKTeZ4/HIghH62m/WrVueaUx5gSn gGeLrAOgfYQfm1X7Wem5prlIJSsG2MzhdkQt9r9wKpMJDj01yDP86ICLz49twvNvu10nerPb/M0CU bnqNZlgRg==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hTAv2-0006w6-9U; Tue, 21 May 2019 19:59:28 +0000 Date: Tue, 21 May 2019 12:59:28 -0700 From: Matthew Wilcox To: Al Viro Cc: David Howells , Christian Brauner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, jannh@google.com, fweimer@redhat.com, oleg@redhat.com, tglx@linutronix.de, torvalds@linux-foundation.org, arnd@arndb.de, shuah@kernel.org, tkjos@android.com, ldv@altlinux.org, miklos@szeredi.hu, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 1/2] open: add close_range() Message-ID: <20190521195928.GB6738@bombadil.infradead.org> References: <20190521150006.GJ17978@ZenIV.linux.org.uk> <20190521113448.20654-1-christian@brauner.io> <28114.1558456227@warthog.procyon.org.uk> <20190521192009.GK17978@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190521192009.GK17978@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, May 21, 2019 at 08:20:09PM +0100, Al Viro wrote: > On Tue, May 21, 2019 at 05:30:27PM +0100, David Howells wrote: > > > If we can live with close_from(int first) rather than close_range(), then this > > can perhaps be done a lot more efficiently by: > > > > new = alloc_fdtable(first); > > spin_lock(&files->file_lock); > > old = files_fdtable(files); > > copy_fds(new, old, 0, first - 1); > > rcu_assign_pointer(files->fdt, new); > > spin_unlock(&files->file_lock); > > clear_fds(old, 0, first - 1); > > close_fdt_from(old, first); > > kfree_rcu(old); > > I really hate to think how that would interact with POSIX locks... POSIX locks store current->files in fl_owner; David's resizing the underlying files->fdt, just like growing from 64 to 256 fds.