From 5edfd9fdc644bf426a8bf9192d9c1a3680d75862 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 27 Feb 2017 15:10:34 +0800 Subject: [PATCH] btrfs: qgroup: Add quick exit for non-fs extents Modify btrfs_qgroup_account_extent() to exit quicker for non-fs extents. The quick exit condition is: 1) The extent belongs to a non-fs tree Only fs-tree extents can affect qgroup numbers and is the only case where extent can be shared between different trees. Although strictly speaking extent in data-reloc or tree-reloc tree can be shared, data/tree-reloc root won't appear in the result of btrfs_find_all_roots(), so we can ignore such case. So we can check the first root in old_roots/new_roots ulist. - if we find the 1st root is a not a fs/subvol root, then we can skip the extent - if we find the 1st root is a fs/subvol root, then we must continue calculation OR 2) both 'nr_old_roots' and 'nr_new_roots' are 0 This means either such extent got allocated then freed in current transaction or it's a new reloc tree extent, whose nr_new_roots is 0. Either way it won't affect qgroup accounting and can be skipped safely. Such quick exit can make trace output more quite and less confusing: (example with fs uuid and time stamp removed) Before: ------ add_delayed_tree_ref: bytenr=29556736 num_bytes=16384 action=ADD_DELAYED_REF parent=0(-) ref_root=2(EXTENT_TREE) level=0 type=TREE_BLOCK_REF seq=0 btrfs_qgroup_account_extent: bytenr=29556736 num_bytes=16384 nr_old_roots=0 nr_new_roots=1 ------ Extent tree block will trigger btrfs_qgroup_account_extent() trace point while no qgroup number is changed, as extent tree won't affect qgroup accounting. After: ------ add_delayed_tree_ref: bytenr=29556736 num_bytes=16384 action=ADD_DELAYED_REF parent=0(-) ref_root=2(EXTENT_TREE) level=0 type=TREE_BLOCK_REF seq=0 ------ Now such unrelated extent won't trigger btrfs_qgroup_account_extent() trace point, making the trace less noisy. Signed-off-by: Qu Wenruo [ changelog and comment adjustments ] Signed-off-by: David Sterba --- fs/btrfs/qgroup.c | 43 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 41 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 7d16f0692d73..34116f6cb5d5 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1919,6 +1919,35 @@ static int qgroup_update_counters(struct btrfs_fs_info *fs_info, return 0; } +/* + * Check if the @roots potentially is a list of fs tree roots + * + * Return 0 for definitely not a fs/subvol tree roots ulist + * Return 1 for possible fs/subvol tree roots in the list (considering an empty + * one as well) + */ +static int maybe_fs_roots(struct ulist *roots) +{ + struct ulist_node *unode; + struct ulist_iterator uiter; + + /* Empty one, still possible for fs roots */ + if (!roots || roots->nnodes == 0) + return 1; + + ULIST_ITER_INIT(&uiter); + unode = ulist_next(roots, &uiter); + if (!unode) + return 1; + + /* + * If it contains fs tree roots, then it must belong to fs/subvol + * trees. + * If it contains a non-fs tree, it won't be shared with fs/subvol trees. + */ + return is_fstree(unode->val); +} + int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, @@ -1935,10 +1964,20 @@ btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) return 0; - if (new_roots) + if (new_roots) { + if (!maybe_fs_roots(new_roots)) + goto out_free; nr_new_roots = new_roots->nnodes; - if (old_roots) + } + if (old_roots) { + if (!maybe_fs_roots(old_roots)) + goto out_free; nr_old_roots = old_roots->nnodes; + } + + /* Quick exit, either not fs tree roots, or won't affect any qgroup */ + if (nr_old_roots == 0 && nr_new_roots == 0) + goto out_free; BUG_ON(!fs_info->quota_root); -- 2.20.1