Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-bk0-f47.google.com ([209.85.214.47]:58066 "EHLO mail-bk0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754230Ab3J3OnH (ORCPT ); Wed, 30 Oct 2013 10:43:07 -0400 Received: by mail-bk0-f47.google.com with SMTP id d7so303428bkh.34 for ; Wed, 30 Oct 2013 07:43:05 -0700 (PDT) Message-ID: <52711AF7.4070100@primarydata.com> Date: Wed, 30 Oct 2013 16:43:03 +0200 From: Benny Halevy MIME-Version: 1.0 To: "J. Bruce Fields" CC: bfields@redhat.com, linux-nfs@vger.kernel.org Subject: Re: [PATCH 1/7] nfsd4: fix recall_lock use in unhash_delegation References: <526F81DE.6060704@primarydata.com> <1383039544-27157-1-git-send-email-bhalevy@primarydata.com> <20131029144658.GR31322@fieldses.org> <52711187.10202@primarydata.com> <20131030143552.GE3227@fieldses.org> In-Reply-To: <20131030143552.GE3227@fieldses.org> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 2013-10-30 16:35, J. Bruce Fields wrote: > On Wed, Oct 30, 2013 at 04:02:47PM +0200, Benny Halevy wrote: >> On 2013-10-29 16:46, J. Bruce Fields wrote: >>> On Tue, Oct 29, 2013 at 11:39:04AM +0200, Benny Halevy wrote: >>>> Access to dp->dl_perclnt must be synchronized by the recall_lock >>> >>> Are you sure? recall_lock is for stuff that's needed in the delegation >>> break callback (nfsd_break_deleg_cb() and any of the subsequent callback >>> handling). I don't think that includes dl_perclnt. >> >> I was mislead by the fact that destroy_client and nfs4_state_shutdown_net >> care to acquire the recall_lock for traversing the clp->cl_delegations >> and nn->del_recall_lru lists, respectively. >> >> Now nfs4_state_shutdown_net, although its comment says it should be >> called with the state lock held (SHOULD or should, or should it be MUST? :) >> It doesn't seem like nfsd_shutdown_net acquires the state lock. > > Good point. > >> Therefore, we either need to grab the state lock in nfs4_state_shutdown_net >> which adds yet another problem to fix, > > That sounds simplest as the short-term fix.... What problem do you see? Nothing specific, just the general use of the global state lock... > > --b. > > commit 2c9407ae694dad8a1ad6394d9bf6077024b9fae7 > Author: J. Bruce Fields > Date: Wed Oct 30 10:33:09 2013 -0400 > > nfsd4: nfsd_shutdown_net needs state lock > > A comment claims the caller should take it, but that's not being done. > Note we don't want it around the cancel_delayed_work_sync since that may > wait on work which holds the client lock. > > Signed-off-by: J. Bruce Fields Ack > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 21eb678..e03e8ef 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -5124,7 +5124,6 @@ out_recovery: > return ret; > } > > -/* should be called with the state lock held */ > void > nfs4_state_shutdown_net(struct net *net) > { > @@ -5135,6 +5134,7 @@ nfs4_state_shutdown_net(struct net *net) > cancel_delayed_work_sync(&nn->laundromat_work); > locks_end_grace(&nn->nfsd4_manager); > > + nfs4_lock_state(); > INIT_LIST_HEAD(&reaplist); > spin_lock(&recall_lock); > list_for_each_safe(pos, next, &nn->del_recall_lru) { > @@ -5149,6 +5149,7 @@ nfs4_state_shutdown_net(struct net *net) > > nfsd4_client_tracking_exit(net); > nfs4_state_destroy_net(net); > + nfs4_unlock_state(); > } > > void > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >