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 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B0D83C27C40 for ; Wed, 23 Aug 2023 21:46:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692827180; h=from:from:sender:sender: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:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=pJjn0CQwyqlhlZhAb4qX8Pfq4Wy5CGCCkFzUT+vOXgU=; b=B+6VbxQU6FWQDoBFenVVO3jV7JAMqqoOHDFt2xq61ThlwiAd5PnKOcXJUL/tLoFbbofi8E nKF2bUMm37/knqvz7NBwEOaobPOO7VC+wSYt32Vs37uM6Fnu5OWKMsjeKWffj/iIaHmZLt Sy91xs4dHTDLA+2P08bD56Tsn+LYh2g= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-593-_VP2lZUFPVWqmQAMhp9YGg-1; Wed, 23 Aug 2023 17:46:17 -0400 X-MC-Unique: _VP2lZUFPVWqmQAMhp9YGg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5C54D800193; Wed, 23 Aug 2023 21:46:16 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 45CFE492C13; Wed, 23 Aug 2023 21:46:16 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (localhost [IPv6:::1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id E457C194658C; Wed, 23 Aug 2023 21:46:10 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id D53F71946589 for ; Wed, 23 Aug 2023 21:33:54 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id B5BD640C6E8A; Wed, 23 Aug 2023 21:33:54 +0000 (UTC) Received: from fs-i40c-03.fs.lab.eng.bos.redhat.com (fs-i40c-03.fs.lab.eng.bos.redhat.com [10.16.224.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6915D400E02F; Wed, 23 Aug 2023 21:33:54 +0000 (UTC) From: Alexander Aring To: linux-nfs@vger.kernel.org Date: Wed, 23 Aug 2023 17:33:48 -0400 Message-Id: <20230823213352.1971009-4-aahringo@redhat.com> In-Reply-To: <20230823213352.1971009-1-aahringo@redhat.com> References: <20230823213352.1971009-1-aahringo@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Subject: [Cluster-devel] [PATCH 3/7] lockd: fix race in async lock request handling X-BeenThere: cluster-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: "\[Cluster devel\]" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jlayton@kernel.org, cluster-devel@redhat.com, ocfs2-devel@lists.linux.dev, chuck.lever@oracle.com, anna@kernel.org, linux-fsdevel@vger.kernel.org, trond.myklebust@hammerspace.com Errors-To: cluster-devel-bounces@redhat.com Sender: "Cluster-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true This patch fixes a race in async lock request handling between adding the relevant struct nlm_block to nlm_blocked list after the request was sent by vfs_lock_file() and nlmsvc_grant_deferred() does a lookup of the nlm_block in the nlm_blocked list. It could be that the async request is completed before the nlm_block was added to the list. This would end in a -ENOENT and a kernel log message of "lockd: grant for unknown block". To solve this issue we add the nlm_block before the vfs_lock_file() call to be sure it has been added when a possible nlmsvc_grant_deferred() is called. If the vfs_lock_file() results in an case when it wouldn't be added to nlm_blocked list, the nlm_block struct will be removed from this list again. The introducing of the new B_PENDING_CALLBACK nlm_block flag will handle async lock requests on a pending lock requests as a retry on the caller level to hit the -EAGAIN case. Signed-off-by: Alexander Aring --- fs/lockd/svclock.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index aa4174fbaf5b..3b158446203b 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -546,6 +546,9 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, ret = nlm_lck_blocked; goto out; } + + /* Append to list of blocked */ + nlmsvc_insert_block_locked(block, NLM_NEVER); spin_unlock(&nlm_blocked_lock); if (!wait) @@ -557,9 +560,12 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, dprintk("lockd: vfs_lock_file returned %d\n", error); switch (error) { case 0: + nlmsvc_remove_block(block); ret = nlm_granted; goto out; case -EAGAIN: + if (!wait) + nlmsvc_remove_block(block); ret = async_block ? nlm_lck_blocked : nlm_lck_denied; goto out; case FILE_LOCK_DEFERRED: @@ -570,17 +576,16 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, ret = nlmsvc_defer_lock_rqst(rqstp, block); goto out; case -EDEADLK: + nlmsvc_remove_block(block); ret = nlm_deadlock; goto out; default: /* includes ENOLCK */ + nlmsvc_remove_block(block); ret = nlm_lck_denied_nolocks; goto out; } ret = nlm_lck_blocked; - - /* Append to list of blocked */ - nlmsvc_insert_block(block, NLM_NEVER); out: mutex_unlock(&file->f_mutex); nlmsvc_release_block(block); -- 2.31.1