From patchwork Mon Feb 27 03:27:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiubo Li X-Patchwork-Id: 657872 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 BD030C6FA8E for ; Mon, 27 Feb 2023 03:29:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229772AbjB0D3m (ORCPT ); Sun, 26 Feb 2023 22:29:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229864AbjB0D3l (ORCPT ); Sun, 26 Feb 2023 22:29:41 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFF87C171 for ; Sun, 26 Feb 2023 19:28:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677468537; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gDrUVdCXVKmyM9kgJh1IH9mSiGUAtZc+i+CpFndiDW0=; b=fzJ+Z0/HHNIEjseOI9sfNe4GUx+L1Fbrdoog1OwdpdRql6/jiAPNmwaWJoAFvJzCKpnWQZ jTBpr1pcrQ1lb7JI/PZ7m/Zp0b+VlSOLWzDGmHb54/emmqx/YpLwa5tTGalw1xOQLvMtYp WtwpJ7IOtpDPLDwh7pyRZfIWiLpl2A8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-206-_pLMxEICO3q69BS3SXVNkA-1; Sun, 26 Feb 2023 22:28:53 -0500 X-MC-Unique: _pLMxEICO3q69BS3SXVNkA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 24E6C800B23; Mon, 27 Feb 2023 03:28:53 +0000 (UTC) Received: from lxbceph1.gsslab.pek2.redhat.com (unknown [10.72.47.117]) by smtp.corp.redhat.com (Postfix) with ESMTP id 568911731B; Mon, 27 Feb 2023 03:28:50 +0000 (UTC) From: xiubli@redhat.com To: idryomov@gmail.com, ceph-devel@vger.kernel.org Cc: jlayton@kernel.org, lhenriques@suse.de, vshankar@redhat.com, mchangir@redhat.com, Xiubo Li Subject: [PATCH v16 09/68] ceph: make ceph_msdc_build_path use ref-walk Date: Mon, 27 Feb 2023 11:27:14 +0800 Message-Id: <20230227032813.337906-10-xiubli@redhat.com> In-Reply-To: <20230227032813.337906-1-xiubli@redhat.com> References: <20230227032813.337906-1-xiubli@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Jeff Layton 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. Reviewed-by: Xiubo Li 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 dcb25724b693..0aa2c97a0460 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2400,7 +2400,8 @@ 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; @@ -2417,34 +2418,35 @@ 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? */ @@ -2453,8 +2455,9 @@ 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;