From patchwork Fri Aug 21 21:41:55 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 7054161 Return-Path: X-Original-To: patchwork-ocfs2-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 8335CC05AC for ; Fri, 21 Aug 2015 21:42:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7C0CE203B1 for ; Fri, 21 Aug 2015 21:42:17 +0000 (UTC) Received: from userp1040.oracle.com (userp1040.oracle.com [156.151.31.81]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3DB1E203B0 for ; Fri, 21 Aug 2015 21:42:16 +0000 (UTC) Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id t7LLg0xU000696 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 21 Aug 2015 21:42:01 GMT Received: from oss.oracle.com (oss-old-reserved.oracle.com [137.254.22.2]) by aserv0022.oracle.com (8.13.8/8.13.8) with ESMTP id t7LLg0sJ029927 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 21 Aug 2015 21:42:00 GMT Received: from localhost ([127.0.0.1] helo=lb-oss.oracle.com) by oss.oracle.com with esmtp (Exim 4.63) (envelope-from ) id 1ZSu4W-00032f-A0; Fri, 21 Aug 2015 14:42:00 -0700 Received: from userv0021.oracle.com ([156.151.31.71]) by oss.oracle.com with esmtp (Exim 4.63) (envelope-from ) id 1ZSu4U-00031l-03 for ocfs2-devel@oss.oracle.com; Fri, 21 Aug 2015 14:41:58 -0700 Received: from userp1030.oracle.com (userp1030.oracle.com [156.151.31.80]) by userv0021.oracle.com (8.13.8/8.13.8) with ESMTP id t7LLfv63000843 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 21 Aug 2015 21:41:57 GMT Received: from userp2030.oracle.com (userp2030.oracle.com [156.151.31.89]) by userp1030.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id t7LLfv85014337 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Fri, 21 Aug 2015 21:41:57 GMT Received: from pps.filterd (userp2030.oracle.com [127.0.0.1]) by userp2030.oracle.com (8.15.0.59/8.15.0.59) with SMTP id t7LLdOjQ031599 for ; Fri, 21 Aug 2015 21:41:57 GMT Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) by userp2030.oracle.com with ESMTP id 1wbka4fkyk-1 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 21 Aug 2015 21:41:57 +0000 Received: from akpm3.mtv.corp.google.com (unknown [216.239.45.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 458218FE; Fri, 21 Aug 2015 21:41:56 +0000 (UTC) Date: Fri, 21 Aug 2015 14:41:55 -0700 From: akpm@linux-foundation.org To: ocfs2-devel@oss.oracle.com, akpm@linux-foundation.org, ghe@suse.com, jlbec@evilplan.org, mfasheh@suse.com, rgoldwyn@suse.de Message-ID: <55d79b23.qR7bB4BZE9qp+53p%akpm@linux-foundation.org> User-Agent: Heirloom mailx 12.5 6/20/10 MIME-Version: 1.0 X-ServerName: mail.linuxfoundation.org X-Proofpoint-Virus-Version: vendor=nai engine=5700 definitions=7900 signatures=670626 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1507310000 definitions=main-1508210305 Subject: [Ocfs2-devel] [patch 24/24] ocfs2: add feature document for online file check X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Source-IP: aserv0022.oracle.com [141.146.126.234] X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Gang He Subject: ocfs2: add feature document for online file check This document describes the OCFS2 online file check feature. OCFS2 is often used in high-availaibility systems. However, OCFS2 usually converts the filesystem to read-only on errors. This may not be necessary, since turning the filesystem read-only would affect other running processes as well, decreasing availability. Then, a mount option (errors=continue) was introduced, which would return the EIO to the calling process and terminate furhter processing so that the filesystem is not corrupted further. The filesystem is not converted to read-only, and the problematic file's inode number is reported in the kernel log. The user can try to check/fix this file via online filecheck feature. Signed-off-by: Gang He Cc: Goldwyn Rodrigues Cc: Mark Fasheh Cc: Joel Becker Signed-off-by: Andrew Morton --- Documentation/filesystems/ocfs2-online-filecheck.txt | 95 ++++++++++ 1 file changed, 95 insertions(+) diff -puN /dev/null Documentation/filesystems/ocfs2-online-filecheck.txt --- /dev/null +++ a/Documentation/filesystems/ocfs2-online-filecheck.txt @@ -0,0 +1,95 @@ + OCFS2 online file check + ----------------------- + +This document will describe OCFS2 online file check feature. + +Introduction +============ +OCFS2 is often used in high-availaibility systems. However, OCFS2 usually +converts the filesystem to read-only on errors. This may not be necessary, since +turning the filesystem read-only would affect other running processes as well, +decreasing availability. Then, a mount option (errors=continue) was introduced, +which would return the EIO to the calling process and terminate furhter +processing so that the filesystem is not corrupted further. The filesystem is +not converted to read-only, and the problematic file's inode number is reported +in the kernel log. The user can try to check/fix this file via online filecheck +feature. + +Scope +===== +This effort is to check/fix small issues which may hinder day-to-day operations +of a cluster filesystem by turning the filesystem read-only. The scope of +checking/fixing is at the file level, initially for regular files and eventually +to all files (including system files) of the filesystem. + +In case of directory to file links is incorrect, the directory inode is +reported as erroneous. + +This feature is not suited for extravagant checks which involve dependency of +other components of the filesystem, such as but not limited to, checking if the +bits for file blocks in the allocation has been set. In case of such an error, +the offline fsck should/would be recommended. + +Finally, such an operation/feature should not be automated lest the filesystem +may end up with more damage than before the repair attempt. So, this has to +be performed using user interaction and consent. + +User interface +============== +When there are errors in the OCFS2 filesystem, they are usually accompanied +by the inode number which caused the error. This inode number would be the +input to check/fix the file. + +There is a sysfs file for each OCFS2 file system mounting: + + /sys/fs/ocfs2//filecheck + +Here, indicates the name of OCFS2 volumn device which has been already +mounted. The file above would accept inode numbers. This could be used to +communicate with kernel space, tell which file(inode number) will be checked or +fixed. Currently, three operations are supported, which includes checking +inode, fixing inode and setting the size of result record history. + +1. If you want to know what error exactly happened to before fixing, do + + # echo "CHECK " > /sys/fs/ocfs2//filecheck + # cat /sys/fs/ocfs2//filecheck + +The output is like this: + INO TYPE DONE ERROR +39502 0 1 GENERATION + + lists the inode numbers. + is what kind of operation you've done, 0 for inode check,1 for inode fix. + indicates whether the operation has been finished. + says what kind of errors was found. For the detailed error numbers, +please refer to the file linux/fs/ocfs2/filecheck.h. + +2. If you determine to fix this inode, do + + # echo "FIX " > /sys/fs/ocfs2//filecheck + # cat /sys/fs/ocfs2//filecheck + +The output is like this: + INO TYPE DONE ERROR +39502 1 1 SUCCESS + +This time, the column indicates whether this fix is successful or not. + +3. The record cache is used to store the history of check/fix result. Its +defalut size is 10, and can be adjust between the range of 10 ~ 100. You can +adjust the size like this: + + # echo "SET " > /sys/fs/ocfs2//filecheck + +Fixing stuff +============ +On receivng the inode, the filesystem would read the inode and the +file metadata. In case of errors, the filesystem would fix the errors +and report the problems it fixed in the kernel log. As a precautionary measure, +the inode must first be checked for errors before performing a final fix. + +The inode and the result history will be maintained temporarily in a +small linked list buffer which would contain the last (N) inodes +fixed/checked, the detailed errors which were fixed/checked are printed in the +kernel log.