--- zzzz-none-000/linux-3.10.107/drivers/md/persistent-data/dm-btree-remove.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/md/persistent-data/dm-btree-remove.c	2021-02-04 17:41:59.000000000 +0000
@@ -165,9 +165,9 @@
 	return 0;
 }
 
-static int exit_child(struct dm_btree_info *info, struct child *c)
+static void exit_child(struct dm_btree_info *info, struct child *c)
 {
-	return dm_tm_unlock(info->tm, c->block);
+	dm_tm_unlock(info->tm, c->block);
 }
 
 static void shift(struct btree_node *left, struct btree_node *right, int count)
@@ -249,13 +249,10 @@
 
 	__rebalance2(info, parent, &left, &right);
 
-	r = exit_child(info, &left);
-	if (r) {
-		exit_child(info, &right);
-		return r;
-	}
+	exit_child(info, &left);
+	exit_child(info, &right);
 
-	return exit_child(info, &right);
+	return 0;
 }
 
 /*
@@ -394,49 +391,18 @@
 
 	__rebalance3(info, parent, &left, &center, &right);
 
-	r = exit_child(info, &left);
-	if (r) {
-		exit_child(info, &center);
-		exit_child(info, &right);
-		return r;
-	}
-
-	r = exit_child(info, &center);
-	if (r) {
-		exit_child(info, &right);
-		return r;
-	}
-
-	r = exit_child(info, &right);
-	if (r)
-		return r;
+	exit_child(info, &left);
+	exit_child(info, &center);
+	exit_child(info, &right);
 
 	return 0;
 }
 
-static int get_nr_entries(struct dm_transaction_manager *tm,
-			  dm_block_t b, uint32_t *result)
-{
-	int r;
-	struct dm_block *block;
-	struct btree_node *n;
-
-	r = dm_tm_read_lock(tm, b, &btree_node_validator, &block);
-	if (r)
-		return r;
-
-	n = dm_block_data(block);
-	*result = le32_to_cpu(n->header.nr_entries);
-
-	return dm_tm_unlock(tm, block);
-}
-
 static int rebalance_children(struct shadow_spine *s,
 			      struct dm_btree_info *info,
 			      struct dm_btree_value_type *vt, uint64_t key)
 {
 	int i, r, has_left_sibling, has_right_sibling;
-	uint32_t child_entries;
 	struct btree_node *n;
 
 	n = dm_block_data(shadow_current(s));
@@ -451,9 +417,7 @@
 
 		memcpy(n, dm_block_data(child),
 		       dm_bm_block_size(dm_tm_get_bm(info->tm)));
-		r = dm_tm_unlock(info->tm, child);
-		if (r)
-			return r;
+		dm_tm_unlock(info->tm, child);
 
 		dm_tm_dec(info->tm, dm_block_location(child));
 		return 0;
@@ -463,10 +427,6 @@
 	if (i < 0)
 		return -ENODATA;
 
-	r = get_nr_entries(info->tm, value64(n, i), &child_entries);
-	if (r)
-		return r;
-
 	has_left_sibling = i > 0;
 	has_right_sibling = i < (le32_to_cpu(n->header.nr_entries) - 1);
 
@@ -589,3 +549,133 @@
 	return r;
 }
 EXPORT_SYMBOL_GPL(dm_btree_remove);
+
+/*----------------------------------------------------------------*/
+
+static int remove_nearest(struct shadow_spine *s, struct dm_btree_info *info,
+			  struct dm_btree_value_type *vt, dm_block_t root,
+			  uint64_t key, int *index)
+{
+	int i = *index, r;
+	struct btree_node *n;
+
+	for (;;) {
+		r = shadow_step(s, root, vt);
+		if (r < 0)
+			break;
+
+		/*
+		 * We have to patch up the parent node, ugly, but I don't
+		 * see a way to do this automatically as part of the spine
+		 * op.
+		 */
+		if (shadow_has_parent(s)) {
+			__le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
+			memcpy(value_ptr(dm_block_data(shadow_parent(s)), i),
+			       &location, sizeof(__le64));
+		}
+
+		n = dm_block_data(shadow_current(s));
+
+		if (le32_to_cpu(n->header.flags) & LEAF_NODE) {
+			*index = lower_bound(n, key);
+			return 0;
+		}
+
+		r = rebalance_children(s, info, vt, key);
+		if (r)
+			break;
+
+		n = dm_block_data(shadow_current(s));
+		if (le32_to_cpu(n->header.flags) & LEAF_NODE) {
+			*index = lower_bound(n, key);
+			return 0;
+		}
+
+		i = lower_bound(n, key);
+
+		/*
+		 * We know the key is present, or else
+		 * rebalance_children would have returned
+		 * -ENODATA
+		 */
+		root = value64(n, i);
+	}
+
+	return r;
+}
+
+static int remove_one(struct dm_btree_info *info, dm_block_t root,
+		      uint64_t *keys, uint64_t end_key,
+		      dm_block_t *new_root, unsigned *nr_removed)
+{
+	unsigned level, last_level = info->levels - 1;
+	int index = 0, r = 0;
+	struct shadow_spine spine;
+	struct btree_node *n;
+	struct dm_btree_value_type le64_vt;
+	uint64_t k;
+
+	init_le64_type(info->tm, &le64_vt);
+	init_shadow_spine(&spine, info);
+	for (level = 0; level < last_level; level++) {
+		r = remove_raw(&spine, info, &le64_vt,
+			       root, keys[level], (unsigned *) &index);
+		if (r < 0)
+			goto out;
+
+		n = dm_block_data(shadow_current(&spine));
+		root = value64(n, index);
+	}
+
+	r = remove_nearest(&spine, info, &info->value_type,
+			   root, keys[last_level], &index);
+	if (r < 0)
+		goto out;
+
+	n = dm_block_data(shadow_current(&spine));
+
+	if (index < 0)
+		index = 0;
+
+	if (index >= le32_to_cpu(n->header.nr_entries)) {
+		r = -ENODATA;
+		goto out;
+	}
+
+	k = le64_to_cpu(n->keys[index]);
+	if (k >= keys[last_level] && k < end_key) {
+		if (info->value_type.dec)
+			info->value_type.dec(info->value_type.context,
+					     value_ptr(n, index));
+
+		delete_at(n, index);
+		keys[last_level] = k + 1ull;
+
+	} else
+		r = -ENODATA;
+
+out:
+	*new_root = shadow_root(&spine);
+	exit_shadow_spine(&spine);
+
+	return r;
+}
+
+int dm_btree_remove_leaves(struct dm_btree_info *info, dm_block_t root,
+			   uint64_t *first_key, uint64_t end_key,
+			   dm_block_t *new_root, unsigned *nr_removed)
+{
+	int r;
+
+	*nr_removed = 0;
+	do {
+		r = remove_one(info, root, first_key, end_key, &root, nr_removed);
+		if (!r)
+			(*nr_removed)++;
+	} while (!r);
+
+	*new_root = root;
+	return r == -ENODATA ? 0 : r;
+}
+EXPORT_SYMBOL_GPL(dm_btree_remove_leaves);