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Btrfs: delayed-refs: use rb_first_cached for ref_tree 

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href->ref_tree need to get the first entry, this
converts href->ref_tree to use rb_first_cached().

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo 2018-08-23 03:51:50 +08:00 committed by David Sterba
parent 5c9d028b3b
commit e3d0396563
5 changed files with 25 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/btrfs/backref.c
View File

@ -769,7 +769,7 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
spin_lock(&head->lock);
for (n = rb_first(&head->ref_tree); n; n = rb_next(n)) {
for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
node = rb_entry(n, struct btrfs_delayed_ref_node,
ref_node);
if (node->seq > seq)

24
fs/btrfs/delayed-ref.c
View File

@ -133,13 +133,14 @@ static struct btrfs_delayed_ref_head *htree_insert(struct rb_root_cached *root,
return NULL;
}
static struct btrfs_delayed_ref_node* tree_insert(struct rb_root *root,
static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,
struct btrfs_delayed_ref_node *ins)
{
struct rb_node **p = &root->rb_node;
struct rb_node **p = &root->rb_root.rb_node;
struct rb_node *node = &ins->ref_node;
struct rb_node *parent_node = NULL;
struct btrfs_delayed_ref_node *entry;
bool leftmost = true;
while (*p) {
int comp;
@ -148,16 +149,18 @@ static struct btrfs_delayed_ref_node* tree_insert(struct rb_root *root,
entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
ref_node);
comp = comp_refs(ins, entry, true);
if (comp < 0)
if (comp < 0) {
p = &(*p)->rb_left;
else if (comp > 0)
} else if (comp > 0) {
p = &(*p)->rb_right;
else
leftmost = false;
} else {
return entry;
}
}
rb_link_node(node, parent_node, p);
rb_insert_color(node, root);
rb_insert_color_cached(node, root, leftmost);
return NULL;
}
@ -231,7 +234,7 @@ static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_node *ref)
{
lockdep_assert_held(&head->lock);
rb_erase(&ref->ref_node, &head->ref_tree);
rb_erase_cached(&ref->ref_node, &head->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);
@ -300,7 +303,7 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
lockdep_assert_held(&head->lock);
if (RB_EMPTY_ROOT(&head->ref_tree))
if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
return;
/* We don't have too many refs to merge for data. */
@ -318,7 +321,8 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
spin_unlock(&fs_info->tree_mod_seq_lock);
again:
for (node = rb_first(&head->ref_tree); node; node = rb_next(node)) {
for (node = rb_first_cached(&head->ref_tree); node;
node = rb_next(node)) {
ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
if (seq && ref->seq >= seq)
continue;
@ -573,7 +577,7 @@ static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
head_ref->must_insert_reserved = must_insert_reserved;
head_ref->is_data = is_data;
head_ref->is_system = is_system;
head_ref->ref_tree = RB_ROOT;
head_ref->ref_tree = RB_ROOT_CACHED;
INIT_LIST_HEAD(&head_ref->ref_add_list);
RB_CLEAR_NODE(&head_ref->href_node);
head_ref->processing = 0;

2
fs/btrfs/delayed-ref.h
View File

@ -79,7 +79,7 @@ struct btrfs_delayed_ref_head {
struct mutex mutex;
spinlock_t lock;
struct rb_root ref_tree;
struct rb_root_cached ref_tree;
/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
struct list_head ref_add_list;

4
fs/btrfs/disk-io.c
View File

@ -4221,11 +4221,11 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
continue;
}
spin_lock(&head->lock);
while ((n = rb_first(&head->ref_tree)) != NULL) {
while ((n = rb_first_cached(&head->ref_tree)) != NULL) {
ref = rb_entry(n, struct btrfs_delayed_ref_node,
ref_node);
ref->in_tree = 0;
rb_erase(&ref->ref_node, &head->ref_tree);
rb_erase_cached(&ref->ref_node, &head->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);

13
fs/btrfs/extent-tree.c
View File

@ -2374,7 +2374,7 @@ select_delayed_ref(struct btrfs_delayed_ref_head *head)
{
struct btrfs_delayed_ref_node *ref;
if (RB_EMPTY_ROOT(&head->ref_tree))
if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
return NULL;
/*
@ -2387,7 +2387,7 @@ select_delayed_ref(struct btrfs_delayed_ref_head *head)
return list_first_entry(&head->ref_add_list,
struct btrfs_delayed_ref_node, add_list);
ref = rb_entry(rb_first(&head->ref_tree),
ref = rb_entry(rb_first_cached(&head->ref_tree),
struct btrfs_delayed_ref_node, ref_node);
ASSERT(list_empty(&ref->add_list));
return ref;
@ -2448,7 +2448,7 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans,
spin_unlock(&head->lock);
spin_lock(&delayed_refs->lock);
spin_lock(&head->lock);
if (!RB_EMPTY_ROOT(&head->ref_tree) || head->extent_op) {
if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root) || head->extent_op) {
spin_unlock(&head->lock);
spin_unlock(&delayed_refs->lock);
return 1;
@ -2597,7 +2597,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
actual_count++;
ref->in_tree = 0;
rb_erase(&ref->ref_node, &locked_ref->ref_tree);
rb_erase_cached(&ref->ref_node, &locked_ref->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);
@ -3040,7 +3040,8 @@ static noinline int check_delayed_ref(struct btrfs_root *root,
* XXX: We should replace this with a proper search function in the
* future.
*/
for (node = rb_first(&head->ref_tree); node; node = rb_next(node)) {
for (node = rb_first_cached(&head->ref_tree); node;
node = rb_next(node)) {
ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
/* If it's a shared ref we know a cross reference exists */
if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) {
@ -6908,7 +6909,7 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
goto out_delayed_unlock;
spin_lock(&head->lock);
if (!RB_EMPTY_ROOT(&head->ref_tree))
if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root))
goto out;
if (head->extent_op) {