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Wed, 23 Mar 2016 20:12:23 GMT Received: from pps.filterd (userp2040.oracle.com [127.0.0.1]) by userp2040.oracle.com (8.15.0.59/8.15.0.59) with SMTP id u2NKCGBb023169 for ; Wed, 23 Mar 2016 20:12:22 GMT Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) by userp2040.oracle.com with ESMTP id 21u828gvgm-1 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 23 Mar 2016 20:12:22 +0000 Received: from akpm3.mtv.corp.google.com (unknown [104.132.1.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 8D5659A; Wed, 23 Mar 2016 20:12:20 +0000 (UTC) Date: Wed, 23 Mar 2016 13:12:20 -0700 From: akpm@linux-foundation.org To: mfasheh@suse.de, jlbec@evilplan.org, junxiao.bi@oracle.com, joseph.qi@huawei.com, ocfs2-devel@oss.oracle.com, akpm@linux-foundation.org, jiangyiwen@huawei.com, stable@vger.kernel.org, tariq.x.saeed@oracle.com Message-ID: <56f2f8a4.kIIVWyzxHkbroR3G%akpm@linux-foundation.org> User-Agent: Heirloom mailx 12.5 6/20/10 MIME-Version: 1.0 X-Proofpoint-SPF-Result: pass X-Proofpoint-SPF-Record: v=spf1 ip4:140.211.169.12/30 include:_spf.google.com ~all X-ServerName: mail.linuxfoundation.org X-Proofpoint-Virus-Version: vendor=nai engine=5800 definitions=8113 signatures=670704 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=8.0.1-1601100000 definitions=main-1603230309 Subject: [Ocfs2-devel] [patch 13/25] ocfs2/dlm: fix race between convert and recovery 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: aserv0021.oracle.com [141.146.126.233] X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_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: Joseph Qi Subject: ocfs2/dlm: fix race between convert and recovery There is a race window between dlmconvert_remote and dlm_move_lockres_to_recovery_list, which will cause a lock with OCFS2_LOCK_BUSY in grant list, thus system hangs. dlmconvert_remote { spin_lock(&res->spinlock); list_move_tail(&lock->list, &res->converting); lock->convert_pending = 1; spin_unlock(&res->spinlock); status = dlm_send_remote_convert_request(); >>>>>> race window, master has queued ast and return DLM_NORMAL, and then down before sending ast. this node detects master down and calls dlm_move_lockres_to_recovery_list, which will revert the lock to grant list. Then OCFS2_LOCK_BUSY won't be cleared as new master won't send ast any more because it thinks already be authorized. spin_lock(&res->spinlock); lock->convert_pending = 0; if (status != DLM_NORMAL) dlm_revert_pending_convert(res, lock); spin_unlock(&res->spinlock); } In this case, check if res->state has DLM_LOCK_RES_RECOVERING bit set (res is still in recovering) or res master changed (new master has finished recovery), reset the status to DLM_RECOVERING, then it will retry convert. Signed-off-by: Joseph Qi Reported-by: Yiwen Jiang Reviewed-by: Junxiao Bi Cc: Mark Fasheh Cc: Joel Becker Cc: Tariq Saeed Cc: Junxiao Bi Cc: Signed-off-by: Andrew Morton --- fs/ocfs2/dlm/dlmconvert.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff -puN fs/ocfs2/dlm/dlmconvert.c~ocfs2-dlm-fix-race-between-convert-and-recovery fs/ocfs2/dlm/dlmconvert.c --- a/fs/ocfs2/dlm/dlmconvert.c~ocfs2-dlm-fix-race-between-convert-and-recovery +++ a/fs/ocfs2/dlm/dlmconvert.c @@ -262,6 +262,7 @@ enum dlm_status dlmconvert_remote(struct struct dlm_lock *lock, int flags, int type) { enum dlm_status status; + u8 old_owner = res->owner; mlog(0, "type=%d, convert_type=%d, busy=%d\n", lock->ml.type, lock->ml.convert_type, res->state & DLM_LOCK_RES_IN_PROGRESS); @@ -316,11 +317,19 @@ enum dlm_status dlmconvert_remote(struct spin_lock(&res->spinlock); res->state &= ~DLM_LOCK_RES_IN_PROGRESS; lock->convert_pending = 0; - /* if it failed, move it back to granted queue */ + /* if it failed, move it back to granted queue. + * if master returns DLM_NORMAL and then down before sending ast, + * it may have already been moved to granted queue, reset to + * DLM_RECOVERING and retry convert */ if (status != DLM_NORMAL) { if (status != DLM_NOTQUEUED) dlm_error(status); dlm_revert_pending_convert(res, lock); + } else if ((res->state & DLM_LOCK_RES_RECOVERING) || + (old_owner != res->owner)) { + mlog(0, "res %.*s is in recovering or has been recovered.\n", + res->lockname.len, res->lockname.name); + status = DLM_RECOVERING; } bail: spin_unlock(&res->spinlock);