From patchwork Tue Jul 5 16:27:48 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 9214827 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 7E56E60B16 for ; Tue, 5 Jul 2016 16:28:07 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 701DC27572 for ; Tue, 5 Jul 2016 16:28:07 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 64F7B276AE; Tue, 5 Jul 2016 16:28:07 +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=unavailable 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 15247275A2 for ; Tue, 5 Jul 2016 16:28:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755419AbcGEQ2D (ORCPT ); Tue, 5 Jul 2016 12:28:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36396 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754596AbcGEQ1x (ORCPT ); Tue, 5 Jul 2016 12:27:53 -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 A07F6C049D59; Tue, 5 Jul 2016 16:27:53 +0000 (UTC) Received: from tlielax.poochiereds.net (ovpn-116-49.rdu2.redhat.com [10.10.116.49]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u65GRn4U005394; Tue, 5 Jul 2016 12:27:52 -0400 From: Jeff Layton To: Ilya Dryomov , zyan@redhat.com Cc: Sage Weil , ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Al Viro Subject: [PATCH 3/4] ceph: allow dentry_lease_is_valid to work under RCU walk Date: Tue, 5 Jul 2016 12:27:48 -0400 Message-Id: <1467736069-27140-4-git-send-email-jlayton@redhat.com> In-Reply-To: <1467736069-27140-1-git-send-email-jlayton@redhat.com> References: <1467736069-27140-1-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 [10.5.110.31]); Tue, 05 Jul 2016 16:27:53 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Under rcuwalk, we need to take extra care when dereferencing d_parent. We want to do that once and pass a pointer to dentry_lease_is_valid. Also, we must ensure that that function can handle the case where we're racing with d_release. Check whether "di" is NULL under the d_lock, and just return 0 if so. Finally, we still need to kick off a renewal job if the lease is getting close to expiration. If that's the case, then just drop out of rcuwalk mode since that could block. Signed-off-by: Jeff Layton --- fs/ceph/dir.c | 41 ++++++++++++++++++++++++++--------------- 1 file changed, 26 insertions(+), 15 deletions(-) diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 904dc671580f..60dcca163ba0 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -1133,7 +1133,8 @@ void ceph_invalidate_dentry_lease(struct dentry *dentry) * Check if dentry lease is valid. If not, delete the lease. Try to * renew if the least is more than half up. */ -static int dentry_lease_is_valid(struct dentry *dentry) +static int dentry_lease_is_valid(struct dentry *dentry, unsigned int flags, + struct inode *dir) { struct ceph_dentry_info *di; struct ceph_mds_session *s; @@ -1141,12 +1142,11 @@ static int dentry_lease_is_valid(struct dentry *dentry) u32 gen; unsigned long ttl; struct ceph_mds_session *session = NULL; - struct inode *dir = NULL; u32 seq = 0; spin_lock(&dentry->d_lock); di = ceph_dentry(dentry); - if (di->lease_session) { + if (di && di->lease_session) { s = di->lease_session; spin_lock(&s->s_gen_ttl_lock); gen = s->s_cap_gen; @@ -1159,12 +1159,19 @@ static int dentry_lease_is_valid(struct dentry *dentry) valid = 1; if (di->lease_renew_after && time_after(jiffies, di->lease_renew_after)) { - /* we should renew */ - dir = d_inode(dentry->d_parent); - session = ceph_get_mds_session(s); - seq = di->lease_seq; - di->lease_renew_after = 0; - di->lease_renew_from = jiffies; + /* + * We should renew. If we're in RCU walk mode + * though, we can't do that so just return + * -ECHILD. + */ + if (flags & LOOKUP_RCU) { + valid = -ECHILD; + } else { + session = ceph_get_mds_session(s); + seq = di->lease_seq; + di->lease_renew_after = 0; + di->lease_renew_from = jiffies; + } } } } @@ -1224,12 +1231,16 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags) } else if (d_really_is_positive(dentry) && ceph_snap(d_inode(dentry)) == CEPH_SNAPDIR) { valid = 1; - } else if (dentry_lease_is_valid(dentry) || - dir_lease_is_valid(dir, dentry)) { - if (d_really_is_positive(dentry)) - valid = ceph_is_any_caps(d_inode(dentry)); - else - valid = 1; + } else { + valid = dentry_lease_is_valid(dentry, flags, dir); + if (valid == -ECHILD) + return valid; + if (valid || dir_lease_is_valid(dir, dentry)) { + if (d_really_is_positive(dentry)) + valid = ceph_is_any_caps(d_inode(dentry)); + else + valid = 1; + } } if (!valid) {