From c6fc24549960f26910cd0c6e4b5f48f2f306b11d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 30 Mar 2015 17:03:00 +0800 Subject: btrfs: delayed-ref: Use list to replace the ref_root in ref_head. This patch replace the rbtree used in ref_head to list. This has the following advantage: 1) Easier merge logic. With the new list implement, we only need to care merging the tail ref_node with the new ref_node. And this can be done quite easy at insert time, no need to do a indicated merge at run_delayed_refs(). Signed-off-by: Qu Wenruo Signed-off-by: Chris Mason --- fs/btrfs/delayed-ref.c | 156 ++++++++++++++++++++++++++----------------------- 1 file changed, 82 insertions(+), 74 deletions(-) (limited to 'fs/btrfs/delayed-ref.c') diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 8f8ed7d..4dbc316 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -268,7 +268,7 @@ static inline void drop_delayed_ref(struct btrfs_trans_handle *trans, rb_erase(&head->href_node, &delayed_refs->href_root); } else { assert_spin_locked(&head->lock); - rb_erase(&ref->rb_node, &head->ref_root); + list_del(&ref->list); } ref->in_tree = 0; btrfs_put_delayed_ref(ref); @@ -328,48 +328,6 @@ static int merge_ref(struct btrfs_trans_handle *trans, return done; } -void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans, - struct btrfs_fs_info *fs_info, - struct btrfs_delayed_ref_root *delayed_refs, - struct btrfs_delayed_ref_head *head) -{ - struct rb_node *node; - u64 seq = 0; - - assert_spin_locked(&head->lock); - /* - * We don't have too much refs to merge in the case of delayed data - * refs. - */ - if (head->is_data) - return; - - spin_lock(&fs_info->tree_mod_seq_lock); - if (!list_empty(&fs_info->tree_mod_seq_list)) { - struct seq_list *elem; - - elem = list_first_entry(&fs_info->tree_mod_seq_list, - struct seq_list, list); - seq = elem->seq; - } - spin_unlock(&fs_info->tree_mod_seq_lock); - - node = rb_first(&head->ref_root); - while (node) { - struct btrfs_delayed_ref_node *ref; - - ref = rb_entry(node, struct btrfs_delayed_ref_node, - rb_node); - /* We can't merge refs that are outside of our seq count */ - if (seq && ref->seq >= seq) - break; - if (merge_ref(trans, delayed_refs, head, ref, seq)) - node = rb_first(&head->ref_root); - else - node = rb_next(&ref->rb_node); - } -} - int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, struct btrfs_delayed_ref_root *delayed_refs, u64 seq) @@ -485,6 +443,74 @@ update_existing_ref(struct btrfs_trans_handle *trans, } /* + * Helper to insert the ref_node to the tail or merge with tail. + * + * Return 0 for insert. + * Return >0 for merge. + */ +static int +add_delayed_ref_tail_merge(struct btrfs_trans_handle *trans, + struct btrfs_delayed_ref_root *root, + struct btrfs_delayed_ref_head *href, + struct btrfs_delayed_ref_node *ref) +{ + struct btrfs_delayed_ref_node *exist; + int mod; + int ret = 0; + + spin_lock(&href->lock); + /* Check whether we can merge the tail node with ref */ + if (list_empty(&href->ref_list)) + goto add_tail; + exist = list_entry(href->ref_list.prev, struct btrfs_delayed_ref_node, + list); + /* No need to compare bytenr nor is_head */ + if (exist->type != ref->type || exist->no_quota != ref->no_quota || + exist->seq != ref->seq) + goto add_tail; + + if ((exist->type == BTRFS_TREE_BLOCK_REF_KEY || + exist->type == BTRFS_SHARED_BLOCK_REF_KEY) && + comp_tree_refs(btrfs_delayed_node_to_tree_ref(exist), + btrfs_delayed_node_to_tree_ref(ref), + ref->type)) + goto add_tail; + if ((exist->type == BTRFS_EXTENT_DATA_REF_KEY || + exist->type == BTRFS_SHARED_DATA_REF_KEY) && + comp_data_refs(btrfs_delayed_node_to_data_ref(exist), + btrfs_delayed_node_to_data_ref(ref))) + goto add_tail; + + /* Now we are sure we can merge */ + ret = 1; + if (exist->action == ref->action) { + mod = ref->ref_mod; + } else { + /* Need to change action */ + if (exist->ref_mod < ref->ref_mod) { + exist->action = ref->action; + mod = -exist->ref_mod; + exist->ref_mod = ref->ref_mod; + } else + mod = -ref->ref_mod; + } + exist->ref_mod += mod; + + /* remove existing tail if its ref_mod is zero */ + if (exist->ref_mod == 0) + drop_delayed_ref(trans, root, href, exist); + spin_unlock(&href->lock); + return ret; + +add_tail: + list_add_tail(&ref->list, &href->ref_list); + atomic_inc(&root->num_entries); + trans->delayed_ref_updates++; + spin_unlock(&href->lock); + return ret; +} + +/* * helper function to update the accounting in the head ref * existing and update must have the same bytenr */ @@ -618,7 +644,7 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info, head_ref = btrfs_delayed_node_to_head(ref); head_ref->must_insert_reserved = must_insert_reserved; head_ref->is_data = is_data; - head_ref->ref_root = RB_ROOT; + INIT_LIST_HEAD(&head_ref->ref_list); head_ref->processing = 0; head_ref->total_ref_mod = count_mod; @@ -659,10 +685,10 @@ add_delayed_tree_ref(struct btrfs_fs_info *fs_info, u64 num_bytes, u64 parent, u64 ref_root, int level, int action, int no_quota) { - struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_tree_ref *full_ref; struct btrfs_delayed_ref_root *delayed_refs; u64 seq = 0; + int ret; if (action == BTRFS_ADD_DELAYED_EXTENT) action = BTRFS_ADD_DELAYED_REF; @@ -693,21 +719,14 @@ add_delayed_tree_ref(struct btrfs_fs_info *fs_info, trace_add_delayed_tree_ref(ref, full_ref, action); - spin_lock(&head_ref->lock); - existing = tree_insert(&head_ref->ref_root, &ref->rb_node); - if (existing) { - update_existing_ref(trans, delayed_refs, head_ref, existing, - ref); - /* - * we've updated the existing ref, free the newly - * allocated ref - */ + ret = add_delayed_ref_tail_merge(trans, delayed_refs, head_ref, ref); + + /* + * XXX: memory should be freed at the same level allocated. + * But bad practice is anywhere... Follow it now. Need cleanup. + */ + if (ret > 0) kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref); - } else { - atomic_inc(&delayed_refs->num_entries); - trans->delayed_ref_updates++; - } - spin_unlock(&head_ref->lock); } /* @@ -721,10 +740,10 @@ add_delayed_data_ref(struct btrfs_fs_info *fs_info, u64 num_bytes, u64 parent, u64 ref_root, u64 owner, u64 offset, int action, int no_quota) { - struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_data_ref *full_ref; struct btrfs_delayed_ref_root *delayed_refs; u64 seq = 0; + int ret; if (action == BTRFS_ADD_DELAYED_EXTENT) action = BTRFS_ADD_DELAYED_REF; @@ -758,21 +777,10 @@ add_delayed_data_ref(struct btrfs_fs_info *fs_info, trace_add_delayed_data_ref(ref, full_ref, action); - spin_lock(&head_ref->lock); - existing = tree_insert(&head_ref->ref_root, &ref->rb_node); - if (existing) { - update_existing_ref(trans, delayed_refs, head_ref, existing, - ref); - /* - * we've updated the existing ref, free the newly - * allocated ref - */ + ret = add_delayed_ref_tail_merge(trans, delayed_refs, head_ref, ref); + + if (ret > 0) kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref); - } else { - atomic_inc(&delayed_refs->num_entries); - trans->delayed_ref_updates++; - } - spin_unlock(&head_ref->lock); } /* -- cgit v1.1