From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47DD2C2D0E7 for ; Thu, 26 Mar 2020 08:33:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20FA720719 for ; Thu, 26 Mar 2020 08:33:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727792AbgCZIdy (ORCPT ); Thu, 26 Mar 2020 04:33:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:49416 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727661AbgCZIdx (ORCPT ); Thu, 26 Mar 2020 04:33:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 0E757AC46; Thu, 26 Mar 2020 08:33:50 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: Josef Bacik Subject: [PATCH v2 13/39] btrfs: relocation: Refactor the finishing part of upper linkage into finish_upper_links() Date: Thu, 26 Mar 2020 16:32:50 +0800 Message-Id: <20200326083316.48847-14-wqu@suse.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200326083316.48847-1-wqu@suse.com> References: <20200326083316.48847-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org After handle_one_tree_backref(), all newly added (not cached) edges and nodes have the following features: - Only backref_edge::list[LOWER] is linked. This means, we can only iterate from botton to top, not the other direction. - Newly added nodes are not added to cache rb_tree yet So to finish the backref cache, we still need to finish the links and add all nodes into backref cache rb_tree. This patch will refactor the existing code into finish_upper_links(), add more comments of each branch, and why we need to do all these works. Signed-off-by: Qu Wenruo Reviewed-by: Josef Bacik --- fs/btrfs/relocation.c | 186 ++++++++++++++++++++++++++---------------- 1 file changed, 117 insertions(+), 69 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 462b6df54b11..37885d0a1d6c 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1080,6 +1080,118 @@ static int handle_one_tree_block(struct backref_cache *cache, return ret; } +/* + * In handle_one_tree_backref(), we have only linked the lower node to the edge, + * but the upper node hasn't been linked to the edge. + * This means we can only iterate through backref_node::upper to reach parent + * edges, but not through backref_node::lower to reach children edges. + * + * This function will finish the backref_node::lower to related edges, so that + * backref cache can be bi-directionally iterated. + * + * Also, this will add the nodes to backref cache for next run. + */ +static int finish_upper_links(struct backref_cache *cache, + struct backref_node *start) +{ + struct list_head *useless_node = &cache->useless_node; + struct backref_edge *edge; + struct rb_node *rb_node; + LIST_HEAD(pending_edge); + + ASSERT(start->checked); + + /* Insert this node to cache if it's not cowonly */ + if (!start->cowonly) { + rb_node = tree_insert(&cache->rb_root, start->bytenr, + &start->rb_node); + if (rb_node) + backref_tree_panic(rb_node, -EEXIST, start->bytenr); + list_add_tail(&start->lower, &cache->leaves); + } + + /* + * Use breadth first search to iterate all related edges. + * + * The start point is all the edges of this node + */ + list_for_each_entry(edge, &start->upper, list[LOWER]) + list_add_tail(&edge->list[UPPER], &pending_edge); + + while (!list_empty(&pending_edge)) { + struct backref_node *upper; + struct backref_node *lower; + struct rb_node *rb_node; + + edge = list_first_entry(&pending_edge, struct backref_edge, + list[UPPER]); + list_del_init(&edge->list[UPPER]); + upper = edge->node[UPPER]; + lower = edge->node[LOWER]; + + /* Parent is detached, no need to keep any edges */ + if (upper->detached) { + list_del(&edge->list[LOWER]); + free_backref_edge(cache, edge); + + /* Lower node is orphan, queue for cleanup */ + if (list_empty(&lower->upper)) + list_add(&lower->list, useless_node); + continue; + } + + /* + * All new nodes added in current build_backref_tree() haven't + * been linked to the cache rb tree. + * So if we have upper->rb_node populated, this means a cache + * hit. We only need to link the edge, as @upper and all its + * parent have already been linked. + */ + if (!RB_EMPTY_NODE(&upper->rb_node)) { + if (upper->lowest) { + list_del_init(&upper->lower); + upper->lowest = 0; + } + + list_add_tail(&edge->list[UPPER], &upper->lower); + continue; + } + + /* Sanity check, we shouldn't have any unchecked nodes */ + if (!upper->checked) { + ASSERT(0); + return -EUCLEAN; + } + + /* Sanity check, cowonly node has non-cowonly parent */ + if (start->cowonly != upper->cowonly) { + ASSERT(0); + return -EUCLEAN; + } + + /* Only cache non-cowonly (subvolume trees) tree blocks */ + if (!upper->cowonly) { + rb_node = tree_insert(&cache->rb_root, upper->bytenr, + &upper->rb_node); + if (rb_node) { + backref_tree_panic(rb_node, -EEXIST, + upper->bytenr); + return -EUCLEAN; + } + } + + list_add_tail(&edge->list[UPPER], &upper->lower); + + /* + * Also queue all the parent edges of this uncached node + * to finish the upper linkage + */ + list_for_each_entry(edge, &upper->upper, list[LOWER]) + list_add_tail(&edge->list[UPPER], &pending_edge); + } + return 0; +} + /* * build backref tree for a given tree block. root of the backref tree * corresponds the tree block, leaves of the backref tree correspond @@ -1107,8 +1219,6 @@ struct backref_node *build_backref_tree(struct reloc_control *rc, struct backref_node *lower; struct backref_node *node = NULL; struct backref_edge *edge; - struct rb_node *rb_node; - int cowonly; int ret; int err = 0; @@ -1149,75 +1259,13 @@ struct backref_node *build_backref_tree(struct reloc_control *rc, } } while (edge); - /* - * everything goes well, connect backref nodes and insert backref nodes - * into the cache. - */ - ASSERT(node->checked); - cowonly = node->cowonly; - if (!cowonly) { - rb_node = tree_insert(&cache->rb_root, node->bytenr, - &node->rb_node); - if (rb_node) - backref_tree_panic(rb_node, -EEXIST, node->bytenr); - list_add_tail(&node->lower, &cache->leaves); + /* Finish the upper linkage of newly added edges/nodes */ + ret = finish_upper_links(cache, node); + if (ret < 0) { + err = ret; + goto out; } - list_for_each_entry(edge, &node->upper, list[LOWER]) - list_add_tail(&edge->list[UPPER], &cache->pending_edge); - - while (!list_empty(&cache->pending_edge)) { - edge = list_first_entry(&cache->pending_edge, - struct backref_edge, list[UPPER]); - list_del_init(&edge->list[UPPER]); - upper = edge->node[UPPER]; - if (upper->detached) { - list_del(&edge->list[LOWER]); - lower = edge->node[LOWER]; - free_backref_edge(cache, edge); - if (list_empty(&lower->upper)) - list_add(&lower->list, &cache->useless_node); - continue; - } - - if (!RB_EMPTY_NODE(&upper->rb_node)) { - if (upper->lowest) { - list_del_init(&upper->lower); - upper->lowest = 0; - } - - list_add_tail(&edge->list[UPPER], &upper->lower); - continue; - } - - if (!upper->checked) { - /* - * Still want to blow up for developers since this is a - * logic bug. - */ - ASSERT(0); - err = -EINVAL; - goto out; - } - if (cowonly != upper->cowonly) { - ASSERT(0); - err = -EINVAL; - goto out; - } - - if (!cowonly) { - rb_node = tree_insert(&cache->rb_root, upper->bytenr, - &upper->rb_node); - if (rb_node) - backref_tree_panic(rb_node, -EEXIST, - upper->bytenr); - } - - list_add_tail(&edge->list[UPPER], &upper->lower); - - list_for_each_entry(edge, &upper->upper, list[LOWER]) - list_add_tail(&edge->list[UPPER], &cache->pending_edge); - } /* * process useless backref nodes. backref nodes for tree leaves * are deleted from the cache. backref nodes for upper level -- 2.26.0