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=-9.8 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 1F120C32751 for ; Wed, 31 Jul 2019 10:24:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1FDA206A2 for ; Wed, 31 Jul 2019 10:24:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728303AbfGaKYD (ORCPT ); Wed, 31 Jul 2019 06:24:03 -0400 Received: from mx2.suse.de ([195.135.220.15]:32924 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728098AbfGaKYC (ORCPT ); Wed, 31 Jul 2019 06:24:02 -0400 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 BAF63AFD4 for ; Wed, 31 Jul 2019 10:24:00 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH RFC 3/3] btrfs: Pause and resume qgroup for snapshot drop Date: Wed, 31 Jul 2019 18:23:52 +0800 Message-Id: <20190731102352.6028-4-wqu@suse.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190731102352.6028-1-wqu@suse.com> References: <20190731102352.6028-1-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 Btrfs qgroup has one big performance overhead for certain snapshot drop. Current btrfs_drop_snapshot() will try its best to find the highest shared node, and just drop one ref of that common node. This behavior is good for minimize extent tree modification, but a disaster for qgroup. Example: Root 300 Root 301 A B | \ / | | X | | / \ | C D / \ / \ E F G H / \ / \ / \ / \ I J K L M N O P In above case, if we're dropping root 301, btrfs_drop_snapshot() will only drop one ref for tree block C and D. But for qgroup, tree blocks E~P also have their owner changed, from 300, 301 to 300 only. Currently we use btrfs_qgroup_trace_subtree() to manually re-dirty tree block E~P. And since such ref change happens in one transaction for each ref drop, we can't split the overhead to different transactions. This could cause qgroup extent record flood, hugely damage performance or even cause OOM for too many qgroup extent records. This patch will try to solve it in a different method, since we can't split the overhead into different transactions, instead of doing such heavy work, we just pause qgroup at the very beginning of btrfs_drop_snapshot(). So later owner change won't trigger qgroup subtree trace, and after all subvolumes get removed, we just trigger a qgroup rescan to rebuild qgroup accounting. Also, to co-operate previous qgroup balance optimization, we don't need to pause qgroup to balance, thus introduce a new parameter for btrfs_drop_snapshot() to inform caller that we have other optimization to handle balance. Signed-off-by: Qu Wenruo --- fs/btrfs/ctree.h | 3 ++- fs/btrfs/disk-io.c | 2 ++ fs/btrfs/extent-tree.c | 13 ++++++++++++- fs/btrfs/relocation.c | 4 ++-- fs/btrfs/transaction.c | 4 ++-- 5 files changed, 20 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 0a61dff27f57..ef6db258e75d 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -3016,7 +3016,8 @@ static inline int btrfs_next_item(struct btrfs_root *root, struct btrfs_path *p) int btrfs_leaf_free_space(struct extent_buffer *leaf); int __must_check btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_block_rsv *block_rsv, - int update_ref, int for_reloc); + int update_ref, int for_reloc, + int pause_qgroup); int btrfs_drop_subtree(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *node, diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9c11ac5edef5..106b2bfff794 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1747,6 +1747,8 @@ static int cleaner_kthread(void *arg) if (kthread_should_stop()) return 0; if (!again) { + if (btrfs_quota_is_paused(fs_info)) + btrfs_quota_resume(fs_info); set_current_state(TASK_INTERRUPTIBLE); schedule(); __set_current_state(TASK_RUNNING); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 5faf057f6f37..a0b5de3216c8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -9236,7 +9236,7 @@ static noinline int walk_up_tree(struct btrfs_trans_handle *trans, */ int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_block_rsv *block_rsv, int update_ref, - int for_reloc) + int for_reloc, int pause_qgroup) { struct btrfs_fs_info *fs_info = root->fs_info; struct btrfs_path *path; @@ -9343,6 +9343,17 @@ int btrfs_drop_snapshot(struct btrfs_root *root, } } + /* + * If this subvolume is shared, and pretty high, we tend to pause + * qgroup to avoid qgroup extent records flood due to sudden subtree + * owner change happened in one transaction. + */ + if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) && + pause_qgroup && (root->root_key.offset || + btrfs_root_last_snapshot(&root->root_item)) && + btrfs_header_level(root->node)) + btrfs_quota_pause(trans); + wc->restarted = test_bit(BTRFS_ROOT_DEAD_TREE, &root->state); wc->level = level; wc->shared_level = -1; diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 22a3c69864fa..ceacf1155495 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2190,14 +2190,14 @@ static int clean_dirty_subvols(struct reloc_control *rc) root->reloc_root = NULL; if (reloc_root) { - ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1); + ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1, 0); if (ret2 < 0 && !ret) ret = ret2; } btrfs_put_fs_root(root); } else { /* Orphan reloc tree, just clean it up */ - ret2 = btrfs_drop_snapshot(root, NULL, 0, 1); + ret2 = btrfs_drop_snapshot(root, NULL, 0, 1, 0); if (ret2 < 0 && !ret) ret = ret2; } diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 48d3b5123129..7fe318318e28 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -2317,9 +2317,9 @@ int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info) if (btrfs_header_backref_rev(root->node) < BTRFS_MIXED_BACKREF_REV) - ret = btrfs_drop_snapshot(root, NULL, 0, 0); + ret = btrfs_drop_snapshot(root, NULL, 0, 0, 1); else - ret = btrfs_drop_snapshot(root, NULL, 1, 0); + ret = btrfs_drop_snapshot(root, NULL, 1, 0, 1); return (ret < 0) ? 0 : 1; } -- 2.22.0