@@ -572,8 +572,8 @@ 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;
@@ -583,12 +583,7 @@ 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;
@@ -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
*/
@@ -603,7 +629,7 @@ 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;
spin_lock_init(&head_ref->lock);
@@ -641,10 +667,10 @@ 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;
@@ -675,21 +701,14 @@ 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);
}
/*
@@ -703,10 +722,10 @@ 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;
@@ -740,21 +759,10 @@ 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);
}
/*
@@ -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;
@@ -4016,6 +4016,7 @@ 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,
@@ -4031,11 +4032,10 @@ 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);
}
@@ -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);
@@ -2874,7 +2851,6 @@ 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;
@@ -2903,11 +2879,7 @@ 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;
@@ -6135,7 +6107,7 @@ 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) {
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 <quwenruo@cn.fujitsu.com> --- 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(-)