From patchwork Fri May 30 13:09:33 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 4270641 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 9749CBEEA7 for ; Fri, 30 May 2014 13:10:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 851E520379 for ; Fri, 30 May 2014 13:10:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF13B2037B for ; Fri, 30 May 2014 13:10:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932674AbaE3NJ6 (ORCPT ); Fri, 30 May 2014 09:09:58 -0400 Received: from mail-qg0-f49.google.com ([209.85.192.49]:42408 "EHLO mail-qg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932498AbaE3NJ6 (ORCPT ); Fri, 30 May 2014 09:09:58 -0400 Received: by mail-qg0-f49.google.com with SMTP id a108so5113934qge.8 for ; Fri, 30 May 2014 06:09:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; bh=b9A3RKqdrBEsS2AEuhvolD2r1xdIWMp2SmdGYMeO4jQ=; b=Q153QqeEVwB/iCLXD3XYoPUlbp1n/PI05v1KC6t9OCAegY8JE373zkNdIHD1uCD3mI Aau3CMGfyiAJF0Xg5lNinIfuzyF1t+UMnFOSH8EusD71wU5xYHDLVXDRd3Sxt7+96yl3 Hml5sIepQ6U5+nZUOVPUCwkyy2X/1laDEelH9uMnCtXc/LSo3UKjGXA1NNLp51MnZs0T ufcfzGyJ/aFGQ8SEGb5Jr4fR9oHg/fWdP5l6E+3OVZWBgueT0jJ5ZFISBEYjIgqud303 IcaCqeb84IsHaU39DBnR9uQrdx27UnEknA3pAC+0dBq/OB90FnHG2rxuZ51Kb9a+8DDP A+bw== X-Gm-Message-State: ALoCoQkvlSK+J11AtGEAvNpBWEWb/E+BNLk7waIfYh5jfELUVKcKuuTtQucBhyAGdqaSJf9QbyOn X-Received: by 10.224.112.74 with SMTP id v10mr20788564qap.28.1401455397619; Fri, 30 May 2014 06:09:57 -0700 (PDT) Received: from tlielax.poochiereds.net ([2001:470:8:d63:3a60:77ff:fe93:a95d]) by mx.google.com with ESMTPSA id j3sm6169861qaf.6.2014.05.30.06.09.56 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 30 May 2014 06:09:56 -0700 (PDT) From: Jeff Layton To: bfields@fieldses.org Cc: trond.myklebust@primarydata.com, bhalevy@primarydata.com, linux-nfs@vger.kernel.org Subject: [PATCH 9/9] NFSd: protect delegation setup with the i_lock Date: Fri, 30 May 2014 09:09:33 -0400 Message-Id: <1401455373-18207-10-git-send-email-jlayton@primarydata.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1401455373-18207-1-git-send-email-jlayton@primarydata.com> References: <1401455373-18207-1-git-send-email-jlayton@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham 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: Trond Myklebust state_lock is a heavily contended global lock. We don't want to grab that while simultaneously holding the inode->i_lock. Avoid doing that in the delegation break callback by ensuring that we add/remove the dl_perfile under the inode->i_lock. This however, can cause an ABBA deadlock between the state_lock and the i_lock. Work around that by doing the list manipulation in the delegation recall from the workqueue context prior to starting the rpc call. Signed-off-by: Trond Myklebust Signed-off-by: Jeff Layton --- fs/nfsd/nfs4callback.c | 18 ++++++++++++++++-- fs/nfsd/nfs4state.c | 41 +++++++++++++++++++++++++++-------------- fs/nfsd/state.h | 1 + 3 files changed, 44 insertions(+), 16 deletions(-) diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index 2c73cae9899d..3d67bbf26cee 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -1011,9 +1011,8 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb) run_nfsd4_cb(cb); } -static void nfsd4_do_callback_rpc(struct work_struct *w) +static void nfsd4_run_callback_rpc(struct nfsd4_callback *cb) { - struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work); struct nfs4_client *clp = cb->cb_clp; struct rpc_clnt *clnt; @@ -1031,11 +1030,25 @@ static void nfsd4_do_callback_rpc(struct work_struct *w) cb->cb_ops, cb); } +static void nfsd4_do_callback_rpc(struct work_struct *w) +{ + struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work); + nfsd4_run_callback_rpc(cb); +} + void nfsd4_init_callback(struct nfsd4_callback *cb) { INIT_WORK(&cb->cb_work, nfsd4_do_callback_rpc); } +static void nfsd4_do_cb_recall(struct work_struct *w) +{ + struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work); + + nfsd4_prepare_cb_recall(cb->cb_op); + nfsd4_run_callback_rpc(cb); +} + void nfsd4_cb_recall(struct nfs4_delegation *dp) { struct nfsd4_callback *cb = &dp->dl_recall; @@ -1052,6 +1065,7 @@ void nfsd4_cb_recall(struct nfs4_delegation *dp) INIT_LIST_HEAD(&cb->cb_per_client); cb->cb_done = true; + INIT_WORK(&cb->cb_work, nfsd4_do_cb_recall); run_nfsd4_cb(&dp->dl_recall); } diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 553c2d6d48dc..c249c5261640 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -438,7 +438,9 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) lockdep_assert_held(&state_lock); dp->dl_stid.sc_type = NFS4_DELEG_STID; + spin_lock(&fp->fi_inode->i_lock); list_add(&dp->dl_perfile, &fp->fi_delegations); + spin_unlock(&fp->fi_inode->i_lock); list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations); } @@ -446,14 +448,20 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) static void unhash_delegation(struct nfs4_delegation *dp) { + struct nfs4_file *fp = dp->dl_file; + spin_lock(&state_lock); list_del_init(&dp->dl_perclnt); - list_del_init(&dp->dl_perfile); list_del_init(&dp->dl_recall_lru); + if (!list_empty(&dp->dl_perfile)) { + spin_lock(&fp->fi_inode->i_lock); + list_del_init(&dp->dl_perfile); + spin_unlock(&fp->fi_inode->i_lock); + } spin_unlock(&state_lock); - if (dp->dl_file) { - nfs4_put_deleg_lease(dp->dl_file); - put_nfs4_file(dp->dl_file); + if (fp) { + nfs4_put_deleg_lease(fp); + put_nfs4_file(fp); dp->dl_file = NULL; } } @@ -2766,24 +2774,31 @@ out: return ret; } -static void nfsd_break_one_deleg(struct nfs4_delegation *dp) +void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp) { struct nfs4_client *clp = dp->dl_stid.sc_client; struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id); - lockdep_assert_held(&state_lock); + /* + * We can't do this in nfsd_break_deleg_cb because it is + * already holding inode->i_lock + */ + spin_lock(&state_lock); + if (list_empty(&dp->dl_recall_lru)) { + dp->dl_time = get_seconds(); + list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru); + } + spin_unlock(&state_lock); +} + +static void nfsd_break_one_deleg(struct nfs4_delegation *dp) +{ /* We're assuming the state code never drops its reference * without first removing the lease. Since we're in this lease * callback (and since the lease code is serialized by the kernel * lock) we know the server hasn't removed the lease yet, we know * it's safe to take a reference: */ atomic_inc(&dp->dl_count); - - list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru); - - /* Only place dl_time is set; protected by i_lock: */ - dp->dl_time = get_seconds(); - nfsd4_cb_recall(dp); } @@ -2808,11 +2823,9 @@ static void nfsd_break_deleg_cb(struct file_lock *fl) */ fl->fl_break_time = 0; - spin_lock(&state_lock); fp->fi_had_conflict = true; list_for_each_entry(dp, &fp->fi_delegations, dl_perfile) nfsd_break_one_deleg(dp); - spin_unlock(&state_lock); } static diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 374c66283ac5..aacccb2a476c 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -472,6 +472,7 @@ extern void nfsd4_cb_recall(struct nfs4_delegation *dp); extern int nfsd4_create_callback_queue(void); extern void nfsd4_destroy_callback_queue(void); extern void nfsd4_shutdown_callback(struct nfs4_client *); +extern void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp); extern void nfs4_put_delegation(struct nfs4_delegation *dp); extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name, struct nfsd_net *nn);