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btrfs: delayed-ref: Use list to replace the ref_root in ref_head.

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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>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Qu Wenruo
2015-03-30 17:03:00 +08:00
committed by Chris Mason
parent 00db646d3f
commit c6fc245499
5 changed files with 114 additions and 123 deletions
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46
fs/btrfs/extent-tree.c
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@@ -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) {