From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Date: Fri, 24 Jul 2020 10:19:59 +0000 Subject: Re: [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications [ver #5] Message-Id: <2003787.1595585999@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <1293241.1595501326@warthog.procyon.org.uk> <158454378820.2863966.10496767254293183123.stgit@warthog.procyon.org.uk> <158454391302.2863966.1884682840541676280.stgit@warthog.procyon.org.uk> In-Reply-To: <1293241.1595501326@warthog.procyon.org.uk> To: Miklos Szeredi Cc: dhowells@redhat.com, Linus Torvalds , Al Viro , Casey Schaufler , Stephen Smalley , nicolas.dichtel@6wind.com, Ian Kent , Christian Brauner , andres@anarazel.de, Jeff Layton , dray@redhat.com, Karel Zak , keyrings@vger.kernel.org, Linux API , linux-fsdevel@vger.kernel.org, LSM , linux-kernel@vger.kernel.org David Howells wrote: > > What guarantees that mount_id is going to remain a 32bit entity? > > You think it likely we'd have >4 billion concurrent mounts on a system? That > would require >1.2TiB of RAM just for the struct mount allocations. > > But I can expand it to __u64. That said, sys_name_to_handle_at() assumes it's a 32-bit signed integer, so we're currently limited to ~2 billion concurrent mounts:-/ David 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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 8E16FC433E0 for ; Fri, 24 Jul 2020 10:20:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CCBD2065C for ; Fri, 24 Jul 2020 10:20:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MmVbG9Mt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726742AbgGXKUM (ORCPT ); Fri, 24 Jul 2020 06:20:12 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:58948 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726271AbgGXKUL (ORCPT ); Fri, 24 Jul 2020 06:20:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595586010; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iNwJ2cEmHYj+S0Ahc6f50GridTdh2KfTtR3COy4a8r0=; b=MmVbG9MtebtRZ9rxu0KRIZz5heV5WTCt/ZQqYS3dUwXu83XQy1OPw5uAyuScyJ//+4oaGj 2waAwW1pu/B6s5Px5yHnhL2aMR3g4kPVT53y7PVyZcpTJ7PBMT8QLGjbaVDf1AOCAsm0LN H/lrnM+naSCee6TpudWCkiPqhEzLzmk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-109-tpfvniXtPBmBGWTxVCEyVQ-1; Fri, 24 Jul 2020 06:20:07 -0400 X-MC-Unique: tpfvniXtPBmBGWTxVCEyVQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 26212800597; Fri, 24 Jul 2020 10:20:04 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-112-32.rdu2.redhat.com [10.10.112.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3EF84872E5; Fri, 24 Jul 2020 10:20:00 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <1293241.1595501326@warthog.procyon.org.uk> References: <1293241.1595501326@warthog.procyon.org.uk> <158454378820.2863966.10496767254293183123.stgit@warthog.procyon.org.uk> <158454391302.2863966.1884682840541676280.stgit@warthog.procyon.org.uk> To: Miklos Szeredi Cc: dhowells@redhat.com, Linus Torvalds , Al Viro , Casey Schaufler , Stephen Smalley , nicolas.dichtel@6wind.com, Ian Kent , Christian Brauner , andres@anarazel.de, Jeff Layton , dray@redhat.com, Karel Zak , keyrings@vger.kernel.org, Linux API , linux-fsdevel@vger.kernel.org, LSM , linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications [ver #5] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2003786.1595585999.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Fri, 24 Jul 2020 11:19:59 +0100 Message-ID: <2003787.1595585999@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Howells wrote: > > What guarantees that mount_id is going to remain a 32bit entity? > = > You think it likely we'd have >4 billion concurrent mounts on a system? = That > would require >1.2TiB of RAM just for the struct mount allocations. > = > But I can expand it to __u64. That said, sys_name_to_handle_at() assumes it's a 32-bit signed integer, s= o we're currently limited to ~2 billion concurrent mounts:-/ David