From patchwork Fri May 21 02:41:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gabriel Krisman Bertazi X-Patchwork-Id: 12271725 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT 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 80814C433ED for ; Fri, 21 May 2021 02:42:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 646EC611AB for ; Fri, 21 May 2021 02:42:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238721AbhEUCoC (ORCPT ); Thu, 20 May 2021 22:44:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231681AbhEUCoC (ORCPT ); Thu, 20 May 2021 22:44:02 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EEAEC061574; Thu, 20 May 2021 19:42:40 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id BAB551F43D3C From: Gabriel Krisman Bertazi To: amir73il@gmail.com Cc: Gabriel Krisman Bertazi , kernel@collabora.com, "Darrick J . Wong" , Theodore Ts'o , Dave Chinner , jack@suse.com, dhowells@redhat.com, khazhy@google.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: [PATCH 11/11] Documentation: Document the FAN_ERROR event Date: Thu, 20 May 2021 22:41:34 -0400 Message-Id: <20210521024134.1032503-12-krisman@collabora.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210521024134.1032503-1-krisman@collabora.com> References: <20210521024134.1032503-1-krisman@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Signed-off-by: Gabriel Krisman Bertazi --- .../admin-guide/filesystem-monitoring.rst | 52 +++++++++++++++++++ Documentation/admin-guide/index.rst | 1 + 2 files changed, 53 insertions(+) create mode 100644 Documentation/admin-guide/filesystem-monitoring.rst diff --git a/Documentation/admin-guide/filesystem-monitoring.rst b/Documentation/admin-guide/filesystem-monitoring.rst new file mode 100644 index 000000000000..81e632f8e1de --- /dev/null +++ b/Documentation/admin-guide/filesystem-monitoring.rst @@ -0,0 +1,52 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================================== +File system Monitoring with fanotify +==================================== + +fanotify supports the FAN_ERROR mark for file system-wide error +reporting. It is meant to be used by file system health monitoring +daemons who listen on that interface and take actions (notify sysadmin, +start recovery) when a file system problem is detected by the kernel. + +By design, A FAN_ERROR notification exposes sufficient information for a +monitoring tool to know a problem in the file system has happened. It +doesn't necessarily provide a user space application with semantics to +verify an IO operation was successfully executed. That is outside of +scope of this feature. Instead, it is only meant as a framework for +early file system problem detection and reporting recovery tools. + +At the time of this writing, the only file system that emits this +FAN_ERROR notifications is ext4. + +A user space example code is provided at ``samples/fanotify/fs-monitor.c``. + +Usage +===== + +Notification structure +====================== + +A FAN_ERROR Notification has the following format:: + + [ Notification Metadata (Mandatory) ] + [ Generic Error Record (Mandatory) ] + +With the exception of the notification metadata and the generic +information, all information records are optional. Each record type is +identified by its unique ``struct fanotify_event_info_header.info_type``. + +Generic error Location +---------------------- + +The Generic error record provides enough information for a file system +agnostic tool to learn about a problem in the file system, without +requiring any details about the problem.:: + + struct fanotify_event_info_error { + struct fanotify_event_info_header hdr; + int error; + __kernel_fsid_t fsid; + unsigned long inode; + __u32 error_count; + }; diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst index dc00afcabb95..1bedab498104 100644 --- a/Documentation/admin-guide/index.rst +++ b/Documentation/admin-guide/index.rst @@ -82,6 +82,7 @@ configure specific aspects of kernel behavior to your liking. edid efi-stub ext4 + filesystem-monitoring nfs/index gpio/index highuid