From c6fc24549960f26910cd0c6e4b5f48f2f306b11d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 30 Mar 2015 17:03:00 +0800 Subject: [PATCH] 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/backref.c | 9 +-- fs/btrfs/delayed-ref.c | 156 ++++++++++++++++++++++------------------- fs/btrfs/delayed-ref.h | 18 ++++- fs/btrfs/disk-io.c | 8 +-- fs/btrfs/extent-tree.c | 46 +++--------- 5 files changed, 114 insertions(+), 123 deletions(-) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index a3316f1707e6..49bc5a41c1f8 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -574,8 +574,8 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, struct list_head *prefs, u64 *total_refs, u64 inum) { + struct btrfs_delayed_ref_node *node; struct btrfs_delayed_extent_op *extent_op = head->extent_op; - struct rb_node *n = &head->node.rb_node; struct btrfs_key key; struct btrfs_key op_key = {0}; int sgn; @@ -585,12 +585,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, btrfs_disk_key_to_cpu(&op_key, &extent_op->key); spin_lock(&head->lock); - n = rb_first(&head->ref_root); - while (n) { - struct btrfs_delayed_ref_node *node; - node = rb_entry(n, struct btrfs_delayed_ref_node, - rb_node); - n = rb_next(n); + list_for_each_entry(node, &head->ref_list, list) { if (node->seq > seq) continue; diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 8f8ed7d20bac..4dbc31636d14 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) @@ -484,6 +442,74 @@ 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); } /* diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 5eb0892396d0..362ca57cfeb7 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -24,9 +24,25 @@ #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */ #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */ +/* + * XXX: Qu: I really hate the design that ref_head and tree/data ref shares the + * same ref_node structure. + * Ref_head is in a higher logic level than tree/data ref, and duplicated + * bytenr/num_bytes in ref_node is really a waste or memory, they should be + * referred from ref_head. + * This gets more disgusting after we use list to store tree/data ref in + * ref_head. Must clean this mess up later. + */ struct btrfs_delayed_ref_node { + /* + * ref_head use rb tree, stored in ref_root->href. + * indexed by bytenr + */ struct rb_node rb_node; + /*data/tree ref use list, stored in ref_head->ref_list. */ + struct list_head list; + /* the starting bytenr of the extent */ u64 bytenr; @@ -83,7 +99,7 @@ struct btrfs_delayed_ref_head { struct mutex mutex; spinlock_t lock; - struct rb_root ref_root; + struct list_head ref_list; struct rb_node href_node; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 7f8377871283..695363ae1c28 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -4062,6 +4062,7 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans, while ((node = rb_first(&delayed_refs->href_root)) != NULL) { struct btrfs_delayed_ref_head *head; + struct btrfs_delayed_ref_node *tmp; bool pin_bytes = false; head = rb_entry(node, struct btrfs_delayed_ref_head, @@ -4077,11 +4078,10 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans, continue; } spin_lock(&head->lock); - while ((node = rb_first(&head->ref_root)) != NULL) { - ref = rb_entry(node, struct btrfs_delayed_ref_node, - rb_node); + list_for_each_entry_safe_reverse(ref, tmp, &head->ref_list, + list) { ref->in_tree = 0; - rb_erase(&ref->rb_node, &head->ref_root); + list_del(&ref->list); atomic_dec(&delayed_refs->num_entries); btrfs_put_delayed_ref(ref); } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 4eefabcc838f..adf0eedde502 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2323,28 +2323,14 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans, return ret; } -static noinline struct btrfs_delayed_ref_node * +static inline struct btrfs_delayed_ref_node * select_delayed_ref(struct btrfs_delayed_ref_head *head) { - struct rb_node *node; - struct btrfs_delayed_ref_node *ref, *last = NULL;; + if (list_empty(&head->ref_list)) + return NULL; - /* - * select delayed ref of type BTRFS_ADD_DELAYED_REF first. - * this prevents ref count from going down to zero when - * there still are pending delayed ref. - */ - node = rb_first(&head->ref_root); - while (node) { - ref = rb_entry(node, struct btrfs_delayed_ref_node, - rb_node); - if (ref->action == BTRFS_ADD_DELAYED_REF) - return ref; - else if (last == NULL) - last = ref; - node = rb_next(node); - } - return last; + return list_entry(head->ref_list.next, struct btrfs_delayed_ref_node, + list); } /* @@ -2396,16 +2382,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, } } - /* - * We need to try and merge add/drops of the same ref since we - * can run into issues with relocate dropping the implicit ref - * and then it being added back again before the drop can - * finish. If we merged anything we need to re-loop so we can - * get a good ref. - */ spin_lock(&locked_ref->lock); - btrfs_merge_delayed_refs(trans, fs_info, delayed_refs, - locked_ref); /* * locked_ref is the head node, so we have to go one @@ -2482,7 +2459,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, spin_unlock(&locked_ref->lock); spin_lock(&delayed_refs->lock); spin_lock(&locked_ref->lock); - if (rb_first(&locked_ref->ref_root) || + if (!list_empty(&locked_ref->ref_list) || locked_ref->extent_op) { spin_unlock(&locked_ref->lock); spin_unlock(&delayed_refs->lock); @@ -2496,7 +2473,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, } else { actual_count++; ref->in_tree = 0; - rb_erase(&ref->rb_node, &locked_ref->ref_root); + list_del(&ref->list); } atomic_dec(&delayed_refs->num_entries); @@ -2905,7 +2882,6 @@ static noinline int check_delayed_ref(struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_node *ref; struct btrfs_delayed_data_ref *data_ref; struct btrfs_delayed_ref_root *delayed_refs; - struct rb_node *node; int ret = 0; delayed_refs = &trans->transaction->delayed_refs; @@ -2934,11 +2910,7 @@ static noinline int check_delayed_ref(struct btrfs_trans_handle *trans, spin_unlock(&delayed_refs->lock); spin_lock(&head->lock); - node = rb_first(&head->ref_root); - while (node) { - ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node); - node = rb_next(node); - + list_for_each_entry(ref, &head->ref_list, list) { /* If it's a shared ref we know a cross reference exists */ if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) { ret = 1; @@ -6448,7 +6420,7 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans, goto out_delayed_unlock; spin_lock(&head->lock); - if (rb_first(&head->ref_root)) + if (!list_empty(&head->ref_list)) goto out; if (head->extent_op) { -- 2.39.5