Btrfs: Leaf reference cache update

This changes the reference cache to make a single cache per root
instead of one cache per transaction, and to key by the byte number
of the disk block instead of the keys inside.

This makes it much less likely to have cache misses if a snapshot
or something has an extra reference on a higher node or a leaf while
the first transaction that added the leaf into the cache is dropping.

Some throttling is added to functions that free blocks heavily so they
wait for old transactions to drop.

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

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 34ed23d64eb..4eca0aa1ce7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -594,7 +594,6 @@ struct btrfs_fs_info {
 
 	spinlock_t ref_cache_lock;
 	u64 total_ref_cache_size;
-	u64 running_ref_cache_size;
 
 	u64 avail_data_alloc_bits;
 	u64 avail_metadata_alloc_bits;
@@ -606,10 +605,18 @@ struct btrfs_fs_info {
 	void *bdev_holder;
 };
 
+struct btrfs_leaf_ref_tree {
+	struct rb_root root;
+	struct btrfs_leaf_ref *last;
+	struct list_head list;
+	spinlock_t lock;
+};
+
 /*
  * in ram representation of the tree.  extent_root is used for all allocations
  * and for the extent tree extent_root root.
  */
+struct dirty_root;
 struct btrfs_root {
 	struct extent_buffer *node;
 
@@ -618,6 +625,8 @@ struct btrfs_root {
 
 	struct extent_buffer *commit_root;
 	struct btrfs_leaf_ref_tree *ref_tree;
+	struct btrfs_leaf_ref_tree ref_tree_struct;
+	struct dirty_root *dirty_root;
 
 	struct btrfs_root_item root_item;
 	struct btrfs_key root_key;