From patchwork Tue Apr 5 19:19:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 12802461 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 539BBC35296 for ; Wed, 6 Apr 2022 05:19:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1447773AbiDFFTk (ORCPT ); Wed, 6 Apr 2022 01:19:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1573570AbiDETWw (ORCPT ); Tue, 5 Apr 2022 15:22:52 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D4AA47050; Tue, 5 Apr 2022 12:20:54 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 4AA77CE1FB6; Tue, 5 Apr 2022 19:20:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18778C385A1; Tue, 5 Apr 2022 19:20:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1649186450; bh=4gK8ZAn+TacGcAjwCDK5lhYYnjJ7LL+dT0yZHFaadd0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h3vPiIxfkK6OiYb/165G98js1mP4pade1hlyPqwCLOvWG47or0gv3JuZz2PzrhdeW LEGz361/FC7O/xfSPkIV/SJG0WEwEk98VAFZ3Tvk2MFbkwJsljtP1Tueh4ji9g/UpZ WfOKEqy9nSA4+mDWZl+mGCxzFyeYrQSYLvFbhEtBnk2ctUsiJsC+N63QUwbmi9YTdr C7kv5ohRf44g1IoriEV3OgQVzt7/5bWnQ2RpSESLGg1L9erv90p18H0cJ33Sm+/FyI LuATH4VtQJt47boufQaIYAOWq3jdd/BnQHnHQdHz8hD3byTOgfG5bC61qqfGM+MnQ3 aaDVyC2xxMFgw== From: Jeff Layton To: idryomov@gmail.com, xiubli@redhat.com Cc: ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org, lhenriques@suse.de Subject: [PATCH v13 20/59] ceph: make ceph_msdc_build_path use ref-walk Date: Tue, 5 Apr 2022 15:19:51 -0400 Message-Id: <20220405192030.178326-21-jlayton@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405192030.178326-1-jlayton@kernel.org> References: <20220405192030.178326-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org Encryption potentially requires allocation, at which point we'll need to be in a non-atomic context. Convert ceph_msdc_build_path to take dentry spinlocks and references instead of using rcu_read_lock to walk the path. This is slightly less efficient, and we may want to eventually allow using RCU when the leaf dentry isn't encrypted. Signed-off-by: Jeff Layton --- fs/ceph/mds_client.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 2f2f8221eb25..28315053e116 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2398,7 +2398,8 @@ static inline u64 __get_oldest_tid(struct ceph_mds_client *mdsc) char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, int stop_on_nosnap) { - struct dentry *temp; + struct dentry *cur; + struct inode *inode; char *path; int pos; unsigned seq; @@ -2415,34 +2416,35 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, path[pos] = '\0'; seq = read_seqbegin(&rename_lock); - rcu_read_lock(); - temp = dentry; + cur = dget(dentry); for (;;) { - struct inode *inode; + struct dentry *temp; - spin_lock(&temp->d_lock); - inode = d_inode(temp); + spin_lock(&cur->d_lock); + inode = d_inode(cur); if (inode && ceph_snap(inode) == CEPH_SNAPDIR) { dout("build_path path+%d: %p SNAPDIR\n", - pos, temp); - } else if (stop_on_nosnap && inode && dentry != temp && + pos, cur); + } else if (stop_on_nosnap && inode && dentry != cur && ceph_snap(inode) == CEPH_NOSNAP) { - spin_unlock(&temp->d_lock); + spin_unlock(&cur->d_lock); pos++; /* get rid of any prepended '/' */ break; } else { - pos -= temp->d_name.len; + pos -= cur->d_name.len; if (pos < 0) { - spin_unlock(&temp->d_lock); + spin_unlock(&cur->d_lock); break; } - memcpy(path + pos, temp->d_name.name, temp->d_name.len); + memcpy(path + pos, cur->d_name.name, cur->d_name.len); } + temp = cur; spin_unlock(&temp->d_lock); - temp = READ_ONCE(temp->d_parent); + cur = dget_parent(temp); + dput(temp); /* Are we at the root? */ - if (IS_ROOT(temp)) + if (IS_ROOT(cur)) break; /* Are we out of buffer? */ @@ -2451,8 +2453,9 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, path[pos] = '/'; } - base = ceph_ino(d_inode(temp)); - rcu_read_unlock(); + inode = d_inode(cur); + base = inode ? ceph_ino(inode) : 0; + dput(cur); if (read_seqretry(&rename_lock, seq)) goto retry;