From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Layton Subject: Re: [PATCH] ceph: properly wake up cap waiter after releasing revoked caps Date: Mon, 11 May 2020 07:28:55 -0400 Message-ID: <53aab39a79f468514cc836ef0081066376ce7d8c.camel@kernel.org> References: <20200511082512.4375-1-zyan@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.kernel.org ([198.145.29.99]:47424 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730062AbgEKL25 (ORCPT ); Mon, 11 May 2020 07:28:57 -0400 In-Reply-To: <20200511082512.4375-1-zyan@redhat.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: "Yan, Zheng" , ceph-devel@vger.kernel.org On Mon, 2020-05-11 at 16:25 +0800, Yan, Zheng wrote: > arg->wake can never be true. the bug was introduced by commit > 0c4b255369bcf "ceph: reorganize __send_cap for less spinlock abuse" > > Signed-off-by: "Yan, Zheng" > --- > fs/ceph/caps.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c > index b3e65c89ba6e..a2a2cda117e0 100644 > --- a/fs/ceph/caps.c > +++ b/fs/ceph/caps.c > @@ -1376,6 +1376,12 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap, > ci->i_ceph_flags &= ~CEPH_I_FLUSH; > > cap->issued &= retain; /* drop bits we don't want */ > + /* > + * Wake up any waiters on wanted -> needed transition. This is due to > + * the weird transition from buffered to sync IO... we need to flush > + * dirty pages _before_ allowing sync writes to avoid reordering. > + */ > + arg->wake = cap->implemented & ~cap->issued; > cap->implemented &= cap->issued | used; > cap->mds_wanted = want; > > @@ -1439,13 +1445,6 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap, > } > } > arg->flags = flags; > - > - /* > - * Wake up any waiters on wanted -> needed transition. This is due to > - * the weird transition from buffered to sync IO... we need to flush > - * dirty pages _before_ allowing sync writes to avoid reordering. > - */ > - arg->wake = cap->implemented & ~cap->issued; > } > > /* Good catch! Merged (with a small revision to the commit message). -- Jeff Layton