From c4140cbf35b90422be6589024f47e132eb2298b1 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 4 Apr 2019 14:45:37 +0800 Subject: [PATCH] btrfs: qgroup: Don't scan leaf if we're modifying reloc tree Since reloc tree doesn't contribute to qgroup numbers, just skip them. This should catch the final cause of unnecessary data ref processing when running balance of metadata with qgroups on. The 4G data 16 snapshots test (*) should explain it pretty well: | delayed subtree | refactor delayed ref | this patch --------------------------------------------------------------------- relocated | 22653 | 22673 | 22744 qgroup dirty | 122792 | 48360 | 70 time | 24.494 | 11.606 | 3.944 Finally, we're at the stage where qgroup + metadata balance cost no obvious overhead. Test environment: Test VM: - vRAM 8G - vCPU 8 - block dev vitrio-blk, 'unsafe' cache mode - host block 850evo Test workload: - Copy 4G data from /usr/ to one subvolume - Create 16 snapshots of that subvolume, and modify 3 files in each snapshot - Enable quota, rescan - Time "btrfs balance start -m" Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 2e69e67a6ae9..34078f302538 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -9141,11 +9141,13 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans, else ret = btrfs_dec_ref(trans, root, eb, 0); BUG_ON(ret); /* -ENOMEM */ - ret = btrfs_qgroup_trace_leaf_items(trans, eb); - if (ret) { - btrfs_err_rl(fs_info, - "error %d accounting leaf items. Quota is out of sync, rescan required.", + if (is_fstree(root->root_key.objectid)) { + ret = btrfs_qgroup_trace_leaf_items(trans, eb); + if (ret) { + btrfs_err_rl(fs_info, + "error %d accounting leaf items, quota is out of sync, rescan required", ret); + } } } /* make block locked assertion in btrfs_clean_tree_block happy */ -- 2.30.2