From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:53791 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752121AbcDZDtp (ORCPT ); Mon, 25 Apr 2016 23:49:45 -0400 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: dsterba@suse.cz, Lu Fengqi Subject: [PATCH RFC 14/16] btrfs-progs: fsck: Introduce function to speed up fs tree check Date: Tue, 26 Apr 2016 11:49:01 +0800 Message-Id: <1461642543-4621-15-git-send-email-quwenruo@cn.fujitsu.com> In-Reply-To: <1461642543-4621-1-git-send-email-quwenruo@cn.fujitsu.com> References: <1461642543-4621-1-git-send-email-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org List-ID: From: Lu Fengqi Introduce function should_check() to reduced duplicated tree block check for fs/subvolume tree. The idea is, we only check the fs/subvolue tree block if we have the highest referencer rootid, according to extent tree. In that case, we can skip a lot of fs/subvolume tree block check if there are a lot of snapshots. Although we will do a lot of extent tree search for it. Signed-off-by: Lu Fengqi Signed-off-by: Qu Wenruo --- cmds-check.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) diff --git a/cmds-check.c b/cmds-check.c index db6fc8e..92f8aa1 100644 --- a/cmds-check.c +++ b/cmds-check.c @@ -9554,6 +9554,96 @@ next: return err; } +/* + * Helper function for later fs/subvol tree check. + * To determine if a tree block should be checked. + * This function will ensure only the directly referencer with lowest + * rootid to check a fs/subvolume tree block. + * + * Backref check at extent tree would detect error like missing subvolume + * tree, so we can do aggressive judgement to reduce duplicated check. + */ +static int should_check(struct btrfs_root *root, struct extent_buffer *eb) +{ + struct btrfs_root *extent_root = root->fs_info->extent_root; + struct btrfs_key key; + struct btrfs_path path; + struct extent_buffer *leaf; + int slot; + struct btrfs_extent_item *ei; + unsigned long ptr; + unsigned long end; + int type; + u32 item_size; + u64 offset; + struct btrfs_extent_inline_ref *iref; + int ret; + + btrfs_init_path(&path); + key.objectid = btrfs_header_bytenr(eb); + key.type = BTRFS_METADATA_ITEM_KEY; + key.offset = (u64)-1; + + /* + * Any failure in backref resolving means we can't determine + * who the tree block belongs to. + * So in that case, we need to check that tree block + */ + ret = btrfs_search_slot(NULL, extent_root, &key, &path, 0, 0); + if (ret < 0) + goto need_check; + + ret = btrfs_previous_extent_item(extent_root, &path, + btrfs_header_bytenr(eb)); + if (ret) + goto need_check; + + leaf = path.nodes[0]; + slot = path.slots[0]; + btrfs_item_key_to_cpu(leaf, &key, slot); + ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item); + + if (key.type == BTRFS_METADATA_ITEM_KEY) { + iref = (struct btrfs_extent_inline_ref *)(ei + 1); + } else { + struct btrfs_tree_block_info *info; + + info = (struct btrfs_tree_block_info *)(ei + 1); + iref = (struct btrfs_extent_inline_ref *)(info + 1); + } + + item_size = btrfs_item_size_nr(leaf, slot); + ptr = (unsigned long)iref; + end = (unsigned long)ei + item_size; + while (ptr < end) { + iref = (struct btrfs_extent_inline_ref *)ptr; + type = btrfs_extent_inline_ref_type(leaf, iref); + offset = btrfs_extent_inline_ref_offset(leaf, iref); + + /* + * We only check the tree block if current root is + * the lowest referencer of it. + */ + if (type == BTRFS_TREE_BLOCK_REF_KEY && + offset < root->objectid) { + btrfs_release_path(&path); + return 0; + } + + ptr += btrfs_extent_inline_ref_size(type); + } + /* + * Normally we should also check keyed tree block ref, + * but that may be very time consuming. + * Inlined ref should already make us skip a lot of refs now. + * So skip search keyed tree block ref. + */ + +need_check: + btrfs_release_path(&path); + return 1; +} + static int btrfs_fsck_reinit_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, int overwrite) { -- 2.8.0