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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,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 26CB1C282C5 for ; Wed, 23 Jan 2019 07:15:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E93F621019 for ; Wed, 23 Jan 2019 07:15:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726772AbfAWHPp (ORCPT ); Wed, 23 Jan 2019 02:15:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:47444 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726611AbfAWHPo (ORCPT ); Wed, 23 Jan 2019 02:15:44 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 9CC83B055 for ; Wed, 23 Jan 2019 07:15:42 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: dsterba@suse.cz Subject: [Patch v5 6/7] btrfs: qgroup: Use delayed subtree rescan for balance Date: Wed, 23 Jan 2019 15:15:17 +0800 Message-Id: <20190123071518.2528-7-wqu@suse.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190123071518.2528-1-wqu@suse.com> References: <20190123071518.2528-1-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 Before this patch, qgroup code trace the whole subtree of subvolume and reloc trees unconditionally. This makes qgroup numbers consistent, but it could cause tons of unnecessary extent trace, which cause a lot of overhead. However for subtree swap of balance, since both subtree contains the same content and tree structures, just swap them won't change qgroup numbers. It's the race window between subtree swap and transaction commit could cause qgroup number change. This patch will delay the qgroup subtree scan until CoW happens for the subtree root. So if there is no other operations for the fs, balance won't cause extra qgroup overhead. (best case scenario) And depends on the workload, most of the subtree scan can still be avoided. Only for worst case scenario, it will fall back to old subtree swap overhead. (scan all swapped subtrees) [[Benchmark]] Hardware: VM 4G vRAM, 8 vCPUs, disk is using 'unsafe' cache mode, backing device is SAMSUNG 850 evo SSD. Host has 16G ram. Mkfs parameter: --nodesize 4K (To bump up tree size) Initial subvolume contents: 4G data copied from /usr and /lib. (With enough regular small files) Snapshots: 16 snapshots of the original subvolume. each snapshot has 3 random files modified. balance parameter: -m So the content should be pretty similar to a real world root fs layout. And after file system population, there is no other activity, so it should be the best case scenario. | v4.20-rc1 | w/ patchset | diff ----------------------------------------------------------------------- relocated extents | 22615 | 22457 | -0.1% qgroup dirty extents | 163457 | 121606 | -25.6% time (sys) | 22.884s | 18.842s | -17.6% time (real) | 27.724s | 22.884s | -17.5% Signed-off-by: Qu Wenruo --- fs/btrfs/ctree.c | 8 ++++ fs/btrfs/qgroup.c | 88 +++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/qgroup.h | 2 + fs/btrfs/relocation.c | 14 +++---- 4 files changed, 103 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index d92462fe66c8..ed28aa7c5f5c 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -13,6 +13,7 @@ #include "print-tree.h" #include "locking.h" #include "volumes.h" +#include "qgroup.h" static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level); @@ -1465,6 +1466,13 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, btrfs_set_lock_blocking(parent); btrfs_set_lock_blocking(buf); + /* + * Before CoWing this block for later modification, check if it's + * the subtree root and do the delayed subtree trace if needed. + * + * Also We don't care about the error, as it's handled internally. + */ + btrfs_qgroup_trace_subtree_after_cow(trans, root, buf); ret = __btrfs_cow_block(trans, root, buf, parent, parent_slot, cow_ret, search_start, 0); diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 2ac32cad5e0c..a518dcae83b4 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -3980,3 +3980,91 @@ int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans, BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT; return ret; } + +/* + * Check if the tree block is a subtree root, and if so do the needed + * delayed subtree trace for qgroup. + * + * This is called during btrfs_cow_block(). + */ +int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *subvol_eb) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_qgroup_swapped_blocks *blocks = &root->swapped_blocks; + struct btrfs_qgroup_swapped_block *block; + struct extent_buffer *reloc_eb = NULL; + struct rb_node *node; + bool found = false; + bool swapped = false; + int level = btrfs_header_level(subvol_eb); + int ret = 0; + int i; + + if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) + return 0; + if (!is_fstree(root->root_key.objectid) || !root->reloc_root) + return 0; + + spin_lock(&blocks->lock); + if (!blocks->swapped) { + spin_unlock(&blocks->lock); + return 0; + } + node = blocks->blocks[level].rb_node; + + while (node) { + block = rb_entry(node, struct btrfs_qgroup_swapped_block, node); + if (block->subvol_bytenr < subvol_eb->start) { + node = node->rb_left; + } else if (block->subvol_bytenr > subvol_eb->start) { + node = node->rb_right; + } else { + found = true; + break; + } + } + if (!found) { + spin_unlock(&blocks->lock); + goto out; + } + /* Found one, remove it from @blocks first and update blocks->swapped */ + rb_erase(&block->node, &blocks->blocks[level]); + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + if (RB_EMPTY_ROOT(&blocks->blocks[i])) { + swapped = true; + break; + } + } + blocks->swapped = swapped; + spin_unlock(&blocks->lock); + + /* Read out reloc subtree root */ + reloc_eb = read_tree_block(fs_info, block->reloc_bytenr, + block->reloc_generation, block->level, + &block->first_key); + if (IS_ERR(reloc_eb)) { + ret = PTR_ERR(subvol_eb); + reloc_eb = NULL; + goto free_out; + } + if (!extent_buffer_uptodate(reloc_eb)) { + ret = -EIO; + goto free_out; + } + + ret = qgroup_trace_subtree_swap(trans, reloc_eb, subvol_eb, + block->last_snapshot, block->trace_leaf); +free_out: + kfree(block); + free_extent_buffer(reloc_eb); +out: + if (ret < 0) { + btrfs_err_rl(fs_info, + "failed to account subtree at bytenr %llu: %d", + subvol_eb->start, ret); + fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT; + } + return ret; +} diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h index 539528d6c1c1..ad3ab67c7aad 100644 --- a/fs/btrfs/qgroup.h +++ b/fs/btrfs/qgroup.h @@ -418,5 +418,7 @@ int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans, struct extent_buffer *subvol_parent, int subvol_slot, struct extent_buffer *reloc_parent, int reloc_slot, u64 last_snapshot); +int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct extent_buffer *eb); #endif diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index cc55249eadb1..c91caeb58035 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1889,16 +1889,12 @@ int replace_path(struct btrfs_trans_handle *trans, struct reloc_control *rc, * If not traced, we will leak data numbers * 2) Fs subtree * If not traced, we will double count old data - * and tree block numbers, if current trans doesn't free - * data reloc tree inode. + * + * We don't scan the subtree right now, but only record + * the swapped tree blocks. + * The real subtree rescan is delayed until we have new + * CoW on the subtree root node before transaction commit. */ - ret = btrfs_qgroup_trace_subtree_swap(trans, rc->block_group, - parent, slot, path->nodes[level], - path->slots[level], last_snapshot); - if (ret < 0) - break; - - btrfs_node_key_to_cpu(parent, &first_key, slot); ret = btrfs_qgroup_add_swapped_blocks(trans, dest, rc->block_group, parent, slot, path->nodes[level], path->slots[level], -- 2.20.1