From patchwork Sat Feb 19 06:56:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiubo Li X-Patchwork-Id: 545315 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 7EEAAC433F5 for ; Sat, 19 Feb 2022 06:56:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240859AbiBSG4v (ORCPT ); Sat, 19 Feb 2022 01:56:51 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:38178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230412AbiBSG4u (ORCPT ); Sat, 19 Feb 2022 01:56:50 -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 ESMTP id 8C39EBF52 for ; Fri, 18 Feb 2022 22:56:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645253790; 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=/kM6FiJYJgJWvATq50TMOzbSPRzmfWZ0RPsgBjCBST4=; b=Hx5hjd5MtyWny4pNpHED4eFpqX7fPQMcdbvx2ZxjL5DUQ1/gXmSEqIihFyL75Wd4x/k/i/ Ft2dinHpzdCHKS3IruXxhWomVVn1US/9n42pxYjiUzdS++lbCdbkTtMF3VY/+5ERkUoWO2 YrbXpXNrQiYjXPp93QLouHZ8MAREI5w= 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-104-pGiF5pLuNFuj5PgaCRXGpQ-1; Sat, 19 Feb 2022 01:56:26 -0500 X-MC-Unique: pGiF5pLuNFuj5PgaCRXGpQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E2A211006AA3; Sat, 19 Feb 2022 06:56:25 +0000 (UTC) Received: from lxbceph1.gsslab.pek2.redhat.com (unknown [10.72.47.117]) by smtp.corp.redhat.com (Postfix) with ESMTP id E9FF662D75; Sat, 19 Feb 2022 06:56:19 +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 v2] ceph: eliminate the recursion when rebuilding the snap context Date: Sat, 19 Feb 2022 14:56:17 +0800 Message-Id: <20220219065617.43718-1-xiubli@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Xiubo Li Use a list instead of recursion to avoid possible stack overflow. Signed-off-by: Xiubo Li --- V2: - Do not insert the child realms when building snapc for the parents fs/ceph/snap.c | 57 +++++++++++++++++++++++++++++++++++++++++-------- fs/ceph/super.h | 2 ++ 2 files changed, 50 insertions(+), 9 deletions(-) diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index bc5ec72d958c..722ddd166013 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -127,6 +127,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm( INIT_LIST_HEAD(&realm->child_item); INIT_LIST_HEAD(&realm->empty_item); INIT_LIST_HEAD(&realm->dirty_item); + INIT_LIST_HEAD(&realm->rebuild_item); INIT_LIST_HEAD(&realm->inodes_with_caps); spin_lock_init(&realm->inodes_with_caps_lock); __insert_snap_realm(&mdsc->snap_realms, realm); @@ -320,7 +321,8 @@ 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; @@ -334,9 +336,9 @@ 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; } @@ -420,13 +422,50 @@ 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; + bool skip = false; - dout("rebuild_snap_realms %llx %p\n", realm->ino, realm); - build_snap_context(realm, dirty_realms); + list_add_tail(&realm->rebuild_item, &realm_queue); - list_for_each_entry(child, &realm->children, child_item) - rebuild_snap_realms(child, dirty_realms); + while (!list_empty(&realm_queue)) { + struct ceph_snap_realm *_realm, *child; + + _realm = list_first_entry(&realm_queue, + struct ceph_snap_realm, + rebuild_item); + + /* + * 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_init(&_realm->rebuild_item); + continue; + } + + last = build_snap_context(_realm, &realm_queue, dirty_realms); + dout("rebuild_snap_realms %llx %p, %s\n", _realm->ino, _realm, + last > 0 ? "is deferred" : !last ? "succeeded" : "failed"); + + /* is any child in the list ? */ + list_for_each_entry(child, &_realm->children, child_item) { + if (!list_empty(&child->rebuild_item)) { + skip = true; + break; + } + } + + if (!skip) { + 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_init(&_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;