From patchwork Wed Feb 16 05:43:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiubo Li X-Patchwork-Id: 12747968 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 CBC44C433F5 for ; Wed, 16 Feb 2022 05:43:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344620AbiBPFoB (ORCPT ); Wed, 16 Feb 2022 00:44:01 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:57844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230002AbiBPFoA (ORCPT ); Wed, 16 Feb 2022 00:44:00 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C9967B0EBD for ; Tue, 15 Feb 2022 21:43:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1644990227; 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; bh=3qtyVLDG05ny/uzuANYvGAaQBP251KYWShf9Vkqp6bg=; b=TpvNtV2sUSUCPcyo0MfT6AYritYI8RYtBhuTXRsCFbC5Z+2JDi/ts5tCpizzkcZGD80Pao Dz25TXSKuOEPInxMbOkl/zZGYqOjxKvnxA29+Zj+z99O/OYKBJ9+1o+YSCVxTPItl7LZiC xlBHSEKYoWW7j08eJeiNhPUgtrgpPlI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-477-Mm-IkUc0NgKb1zBKI47TmA-1; Wed, 16 Feb 2022 00:43:42 -0500 X-MC-Unique: Mm-IkUc0NgKb1zBKI47TmA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F0E9A1800D50; Wed, 16 Feb 2022 05:43:40 +0000 (UTC) Received: from lxbceph1.gsslab.pek2.redhat.com (unknown [10.72.47.117]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2D852795AD; Wed, 16 Feb 2022 05:43:38 +0000 (UTC) From: xiubli@redhat.com To: jlayton@kernel.org Cc: idryomov@gmail.com, vshankar@redhat.com, ceph-devel@vger.kernel.org, Xiubo Li Subject: [PATCH] ceph: eliminate the recursion when rebuilding the snap context Date: Wed, 16 Feb 2022 13:43:35 +0800 Message-Id: <20220216054335.32015-1-xiubli@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Xiubo Li Use a list instead of recuresion to avoid possible stack overflow. Signed-off-by: Xiubo Li --- fs/ceph/snap.c | 44 +++++++++++++++++++++++++++++++++++--------- fs/ceph/super.h | 2 ++ 2 files changed, 37 insertions(+), 9 deletions(-) diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 6939307d41cb..808add7dca9e 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -319,7 +319,8 @@ static int cmpu64_rev(const void *a, const void *b) * build the snap context for a given realm. */ static int build_snap_context(struct ceph_snap_realm *realm, - struct list_head* dirty_realms) + struct list_head *realm_queue, + struct list_head *dirty_realms) { struct ceph_snap_realm *parent = realm->parent; struct ceph_snap_context *snapc; @@ -333,9 +334,9 @@ static int build_snap_context(struct ceph_snap_realm *realm, */ if (parent) { if (!parent->cached_context) { - err = build_snap_context(parent, dirty_realms); - if (err) - goto fail; + /* add to the queue head */ + list_add(&parent->rebuild_item, realm_queue); + return 1; } num += parent->cached_context->num_snaps; } @@ -418,13 +419,38 @@ static int build_snap_context(struct ceph_snap_realm *realm, static void rebuild_snap_realms(struct ceph_snap_realm *realm, struct list_head *dirty_realms) { - struct ceph_snap_realm *child; + LIST_HEAD(realm_queue); + int last = 0; - dout("%s %llx %p\n", __func__, realm->ino, realm); - build_snap_context(realm, dirty_realms); + list_add_tail(&realm->rebuild_item, &realm_queue); + + while (!list_empty(&realm_queue)) { + struct ceph_snap_realm *_realm, *child; + + /* + * If the last building failed dues to memory + * issue, just empty the realm_queue and return + * to avoid infinite loop. + */ + if (last < 0) { + list_del(&_realm->rebuild_item); + continue; + } + + _realm = list_first_entry(&realm_queue, + struct ceph_snap_realm, + rebuild_item); + last = build_snap_context(_realm, &realm_queue, dirty_realms); + dout("%s %llx %p, %s\n", __func__, _realm->ino, _realm, + last > 0 ? "is deferred" : !last ? "succeeded" : "failed"); - list_for_each_entry(child, &realm->children, child_item) - rebuild_snap_realms(child, dirty_realms); + list_for_each_entry(child, &_realm->children, child_item) + list_add_tail(&child->rebuild_item, &realm_queue); + + /* last == 1 means need to build parent first */ + if (last <= 0) + list_del(&_realm->rebuild_item); + } } diff --git a/fs/ceph/super.h b/fs/ceph/super.h index a17bd01a8957..baac800a6d11 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -885,6 +885,8 @@ struct ceph_snap_realm { struct list_head dirty_item; /* if realm needs new context */ + struct list_head rebuild_item; /* rebuild snap realms _downward_ in hierarchy */ + /* the current set of snaps for this realm */ struct ceph_snap_context *cached_context;