Btrfs: try to cleanup delayed refs while freeing extents

When extents are freed, it is likely that we've removed the last
delayed reference update for the extent.  This checks the delayed
ref tree when things are freed, and if no ref updates area left it
immediately processes the delayed ref.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 874565a1f634..3e7eeaf86408 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -511,6 +511,24 @@ int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans,
 }
 
 /*
+ * this does a simple search for the head node for a given extent.
+ * It must be called with the delayed ref spinlock held, and it returns
+ * the head node if any where found, or NULL if not.
+ */
+struct btrfs_delayed_ref_head *
+btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
+{
+        struct btrfs_delayed_ref_node *ref;
+        struct btrfs_delayed_ref_root *delayed_refs;
+
+        delayed_refs = &trans->transaction->delayed_refs;
+        ref = tree_search(&delayed_refs->root, bytenr, (u64)-1);
+        if (ref)
+                return btrfs_delayed_node_to_head(ref);
+        return NULL;
+}
+
+/*
  * add a delayed ref to the tree.  This does all of the accounting required
  * to make sure the delayed ref is eventually processed before this
  * transaction commits.