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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 9B81DC433E0 for ; Fri, 5 Feb 2021 16:47:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5387364EEF for ; Fri, 5 Feb 2021 16:47:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232133AbhBEPIE (ORCPT ); Fri, 5 Feb 2021 10:08:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:45958 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233069AbhBEPCU (ORCPT ); Fri, 5 Feb 2021 10:02:20 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2FC3C65042; Fri, 5 Feb 2021 14:12:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612534321; bh=RC4wRZDrZA0fZbK+UMQHFykRCWnDFMVXhScHL7ahyvw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g2Xc8UniRzTJ00cNICnVeU0+GAkh9mn6KpqOvL/bSHaNz+jqm95EG4LdLuBuGzq44 rOglSDhV8d8VdZIvOQchoFyl1wii2ZzoLo1U/mZ313uWq+GFRmXMW6Ppbdd82VpOrS GDwiSK3JMt3jADZB8E226QeixdwVzdQ+aXfhdyzQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , Johannes Thumshirn , ethanwu , David Sterba Subject: [PATCH 5.4 10/32] btrfs: backref, dont add refs from shared block when resolving normal backref Date: Fri, 5 Feb 2021 15:07:25 +0100 Message-Id: <20210205140652.781147189@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210205140652.348864025@linuxfoundation.org> References: <20210205140652.348864025@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: ethanwu commit ed58f2e66e849c34826083e5a6c1b506ee8a4d8e upstream. All references from the block of SHARED_DATA_REF belong to that shared block backref. For example: item 11 key (40831553536 EXTENT_ITEM 4194304) itemoff 15460 itemsize 95 extent refs 24 gen 7302 flags DATA extent data backref root 257 objectid 260 offset 65536 count 5 extent data backref root 258 objectid 265 offset 0 count 9 shared data backref parent 394985472 count 10 Block 394985472 might be leaf from root 257, and the item obejctid and (file_pos - file_extent_item::offset) in that leaf just happens to be 260 and 65536 which is equal to the first extent data backref entry. Before this patch, when we resolve backref: root 257 objectid 260 offset 65536 we will add those refs in block 394985472 and wrongly treat those as the refs we want. Fix this by checking if the leaf we are processing is shared data backref, if so, just skip this leaf. Shared data refs added into preftrees.direct have all entry value = 0 (root_id = 0, key = NULL, level = 0) except parent entry. Other refs from indirect tree will have key value and root id != 0, and these values won't be changed when their parent is resolved and added to preftrees.direct. Therefore, we could reuse the preftrees.direct and search ref with all values = 0 except parent is set to avoid getting those resolved refs block. Reviewed-by: Josef Bacik Reviewed-by: Johannes Thumshirn Signed-off-by: ethanwu Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/backref.c | 61 +++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 52 insertions(+), 9 deletions(-) --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -386,8 +386,34 @@ static int add_indirect_ref(const struct wanted_disk_byte, count, sc, gfp_mask); } +static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr) +{ + struct rb_node **p = &preftrees->direct.root.rb_root.rb_node; + struct rb_node *parent = NULL; + struct prelim_ref *ref = NULL; + struct prelim_ref target = {0}; + int result; + + target.parent = bytenr; + + while (*p) { + parent = *p; + ref = rb_entry(parent, struct prelim_ref, rbnode); + result = prelim_ref_compare(ref, &target); + + if (result < 0) + p = &(*p)->rb_left; + else if (result > 0) + p = &(*p)->rb_right; + else + return 1; + } + return 0; +} + static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, - struct ulist *parents, struct prelim_ref *ref, + struct ulist *parents, + struct preftrees *preftrees, struct prelim_ref *ref, int level, u64 time_seq, const u64 *extent_item_pos, u64 total_refs, bool ignore_offset) { @@ -412,11 +438,16 @@ static int add_all_parents(struct btrfs_ } /* - * We normally enter this function with the path already pointing to - * the first item to check. But sometimes, we may enter it with - * slot==nritems. In that case, go to the next leaf before we continue. + * 1. We normally enter this function with the path already pointing to + * the first item to check. But sometimes, we may enter it with + * slot == nritems. + * 2. We are searching for normal backref but bytenr of this leaf + * matches shared data backref + * For these cases, go to the next leaf before we continue. */ - if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { + eb = path->nodes[0]; + if (path->slots[0] >= btrfs_header_nritems(eb) || + is_shared_data_backref(preftrees, eb->start)) { if (time_seq == SEQ_LAST) ret = btrfs_next_leaf(root, path); else @@ -433,6 +464,17 @@ static int add_all_parents(struct btrfs_ key.type != BTRFS_EXTENT_DATA_KEY) break; + /* + * We are searching for normal backref but bytenr of this leaf + * matches shared data backref. + */ + if (slot == 0 && is_shared_data_backref(preftrees, eb->start)) { + if (time_seq == SEQ_LAST) + ret = btrfs_next_leaf(root, path); + else + ret = btrfs_next_old_leaf(root, path, time_seq); + continue; + } fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); data_offset = btrfs_file_extent_offset(eb, fi); @@ -484,6 +526,7 @@ next: */ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 time_seq, + struct preftrees *preftrees, struct prelim_ref *ref, struct ulist *parents, const u64 *extent_item_pos, u64 total_refs, bool ignore_offset) @@ -577,8 +620,8 @@ static int resolve_indirect_ref(struct b eb = path->nodes[level]; } - ret = add_all_parents(root, path, parents, ref, level, time_seq, - extent_item_pos, total_refs, ignore_offset); + ret = add_all_parents(root, path, parents, preftrees, ref, level, + time_seq, extent_item_pos, total_refs, ignore_offset); out: path->lowest_level = 0; btrfs_release_path(path); @@ -656,8 +699,8 @@ static int resolve_indirect_refs(struct ret = BACKREF_FOUND_SHARED; goto out; } - err = resolve_indirect_ref(fs_info, path, time_seq, ref, - parents, extent_item_pos, + err = resolve_indirect_ref(fs_info, path, time_seq, preftrees, + ref, parents, extent_item_pos, total_refs, ignore_offset); /* * we can only tolerate ENOENT,otherwise,we should catch error