--- zzzz-none-000/linux-3.10.107/drivers/md/persistent-data/dm-btree.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/md/persistent-data/dm-btree.h	2021-02-04 17:41:59.000000000 +0000
@@ -110,6 +110,13 @@
 		    uint64_t *keys, void *value_le);
 
 /*
+ * Tries to find the first key where the bottom level key is >= to that
+ * given.  Useful for skipping empty sections of the btree.
+ */
+int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
+			 uint64_t *keys, uint64_t *rkey, void *value_le);
+
+/*
  * Insertion (or overwrite an existing value).  O(ln(n))
  */
 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
@@ -135,6 +142,24 @@
 		    uint64_t *keys, dm_block_t *new_root);
 
 /*
+ * Removes a _contiguous_ run of values starting from 'keys' and not
+ * reaching keys2 (where keys2 is keys with the final key replaced with
+ * 'end_key').  'end_key' is the one-past-the-end value.  'keys' may be
+ * altered.
+ */
+int dm_btree_remove_leaves(struct dm_btree_info *info, dm_block_t root,
+			   uint64_t *keys, uint64_t end_key,
+			   dm_block_t *new_root, unsigned *nr_removed);
+
+/*
+ * Returns < 0 on failure.  Otherwise the number of key entries that have
+ * been filled out.  Remember trees can have zero entries, and as such have
+ * no lowest key.
+ */
+int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
+			     uint64_t *result_keys);
+
+/*
  * Returns < 0 on failure.  Otherwise the number of key entries that have
  * been filled out.  Remember trees can have zero entries, and as such have
  * no highest key.