From patchwork Thu Oct 20 15:43:58 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 9387247 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 00062607F0 for ; Thu, 20 Oct 2016 15:44:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E2FB229B5A for ; Thu, 20 Oct 2016 15:44:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D7A1429BB2; Thu, 20 Oct 2016 15:44:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5848E29B5A for ; Thu, 20 Oct 2016 15:44:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753343AbcJTPoB (ORCPT ); Thu, 20 Oct 2016 11:44:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55968 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751741AbcJTPoA (ORCPT ); Thu, 20 Oct 2016 11:44:00 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2D28F43A5A; Thu, 20 Oct 2016 15:44:00 +0000 (UTC) Received: from tlielax.poochiereds.net (ovpn-116-44.rdu2.redhat.com [10.10.116.44]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u9KFhx5h029634; Thu, 20 Oct 2016 11:43:59 -0400 From: Jeff Layton To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org Subject: [PATCH] nfsd: move blocked lock handling under a dedicated spinlock Date: Thu, 20 Oct 2016 11:43:58 -0400 Message-Id: <1476978238-2449-1-git-send-email-jlayton@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 20 Oct 2016 15:44:00 +0000 (UTC) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Bruce was hitting some lockdep warnings in testing, showing that we could hit a deadlock with the new CB_NOTIFY_LOCK handling, in a rather complex situation involving four different spinlocks. The crux of the matter is that we end up taking the nn->client_lock in the lm_notify handler, while we're already holding the global blocked_lock_lock. The simplest fix is to just declare a new per-nfsd_net spinlock to protect the new CB_NOTIFY_LOCK structures. Signed-off-by: Jeff Layton --- fs/nfsd/netns.h | 5 +++++ fs/nfsd/nfs4state.c | 28 +++++++++++++++------------- fs/nfsd/state.h | 2 +- 3 files changed, 21 insertions(+), 14 deletions(-) diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index b10d557f9c9e..ee36efd5aece 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -84,6 +84,8 @@ struct nfsd_net { struct list_head client_lru; struct list_head close_lru; struct list_head del_recall_lru; + + /* protected by blocked_locks_lock */ struct list_head blocked_locks_lru; struct delayed_work laundromat_work; @@ -91,6 +93,9 @@ struct nfsd_net { /* client_lock protects the client lru list and session hash table */ spinlock_t client_lock; + /* protects blocked_locks_lru */ + spinlock_t blocked_locks_lock; + struct file *rec_file; bool in_grace; const struct nfsd4_client_tracking_ops *client_tracking_ops; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 9752beb78659..95474196a17e 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -217,7 +217,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, { struct nfsd4_blocked_lock *cur, *found = NULL; - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); list_for_each_entry(cur, &lo->lo_blocked, nbl_list) { if (fh_match(fh, &cur->nbl_fh)) { list_del_init(&cur->nbl_list); @@ -226,7 +226,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, break; } } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); if (found) posix_unblock_lock(&found->nbl_lock); return found; @@ -4665,7 +4665,7 @@ nfs4_laundromat(struct nfsd_net *nn) * indefinitely once the lock does become free. */ BUG_ON(!list_empty(&reaplist)); - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); while (!list_empty(&nn->blocked_locks_lru)) { nbl = list_first_entry(&nn->blocked_locks_lru, struct nfsd4_blocked_lock, nbl_lru); @@ -4678,7 +4678,7 @@ nfs4_laundromat(struct nfsd_net *nn) list_move(&nbl->nbl_lru, &reaplist); list_del_init(&nbl->nbl_list); } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); while (!list_empty(&reaplist)) { nbl = list_first_entry(&nn->blocked_locks_lru, @@ -5439,13 +5439,13 @@ nfsd4_lm_notify(struct file_lock *fl) bool queue = false; /* An empty list means that something else is going to be using it */ - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); if (!list_empty(&nbl->nbl_list)) { list_del_init(&nbl->nbl_list); list_del_init(&nbl->nbl_lru); queue = true; } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); if (queue) nfsd4_run_cb(&nbl->nbl_cb); @@ -5868,10 +5868,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, if (fl_flags & FL_SLEEP) { nbl->nbl_time = jiffies; - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked); list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru); - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); } err = vfs_lock_file(filp, F_SETLK, file_lock, conflock); @@ -5900,10 +5900,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, if (nbl) { /* dequeue it if we queued it before */ if (fl_flags & FL_SLEEP) { - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); list_del_init(&nbl->nbl_list); list_del_init(&nbl->nbl_lru); - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); } free_blocked_lock(nbl); } @@ -6943,9 +6943,11 @@ static int nfs4_state_create_net(struct net *net) INIT_LIST_HEAD(&nn->client_lru); INIT_LIST_HEAD(&nn->close_lru); INIT_LIST_HEAD(&nn->del_recall_lru); - INIT_LIST_HEAD(&nn->blocked_locks_lru); spin_lock_init(&nn->client_lock); + spin_lock_init(&nn->blocked_locks_lock); + INIT_LIST_HEAD(&nn->blocked_locks_lru); + INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main); get_net(net); @@ -7063,14 +7065,14 @@ nfs4_state_shutdown_net(struct net *net) } BUG_ON(!list_empty(&reaplist)); - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); while (!list_empty(&nn->blocked_locks_lru)) { nbl = list_first_entry(&nn->blocked_locks_lru, struct nfsd4_blocked_lock, nbl_lru); list_move(&nbl->nbl_lru, &reaplist); list_del_init(&nbl->nbl_list); } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); while (!list_empty(&reaplist)) { nbl = list_first_entry(&nn->blocked_locks_lru, diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index c9399366f9df..bccdbe0f63d9 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -444,7 +444,7 @@ struct nfs4_openowner { */ struct nfs4_lockowner { struct nfs4_stateowner lo_owner; /* must be first element */ - struct list_head lo_blocked; /* blocked file_locks */ + struct list_head lo_blocked; /* protected by nn->blocked_locks_lock */ }; static inline struct nfs4_openowner * openowner(struct nfs4_stateowner *so)