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=-5.8 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,URIBL_BLOCKED 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 7A67CC4361B for ; Tue, 8 Dec 2020 12:58:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B4E623A3C for ; Tue, 8 Dec 2020 12:58:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728306AbgLHM6i (ORCPT ); Tue, 8 Dec 2020 07:58:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:29293 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727709AbgLHM6i (ORCPT ); Tue, 8 Dec 2020 07:58:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607432231; 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: in-reply-to:in-reply-to:references:references; bh=oYSrhl7On3ek4AmuwFnsO6QT9IbADxIiRQU6iafFmC8=; b=IkJbYe+fV1v2H5e3C06H1DyYhECAcLFNXyaoRBGbninvf11jvqgqM5cuLh63Hj2Dl+RtH2 VkvgEE/dL6ReLjCkYVXv2MfOjQpVgrU1+9+wmeGWR+ipACP6NCO8wJpYQvxW67FNCcvbfH cM5SJs74P2w5QJfCjW9sGXQhmlX1Pxw= 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-62-rrPQhd1BOtuur6_XxFWmXA-1; Tue, 08 Dec 2020 07:57:07 -0500 X-MC-Unique: rrPQhd1BOtuur6_XxFWmXA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F2C9C28A; Tue, 8 Dec 2020 12:57:05 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-116-67.rdu2.redhat.com [10.10.116.67]) by smtp.corp.redhat.com (Postfix) with ESMTP id E77195C1BB; Tue, 8 Dec 2020 12:57:03 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20201208003117.342047-4-krisman@collabora.com> References: <20201208003117.342047-4-krisman@collabora.com> <20201208003117.342047-1-krisman@collabora.com> To: Gabriel Krisman Bertazi Cc: dhowells@redhat.com, viro@zeniv.linux.org.uk, tytso@mit.edu, khazhy@google.com, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel@collabora.com Subject: Re: [PATCH 3/8] watch_queue: Support a text field at the end of the notification MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <953178.1607432223.1@warthog.procyon.org.uk> Date: Tue, 08 Dec 2020 12:57:03 +0000 Message-ID: <953179.1607432223@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Gabriel Krisman Bertazi wrote: > This allow notifications to send text information to userspace without > having to copy it to a temporary buffer to then copy to the ring. One > use case to pass text information in notifications is for error > reporting, where more debug information might be needed, but we don't > want to explode the number of subtypes of notifications. For instance, > ext4 can have a single inode error notification subtype, and pass more > information on the cause of the error in this field. I'm generally okay with this, but you really need to note that if you make use of this for a subtype, you don't get to add more fields for that subtype unless there's an offset to it. Speaking of that, you need to update: Documentation/watch_queue.rst since you're changing the API. The "Watch Sources" section will also need altering to indicate that superblock events are now a thing. David