Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 773 insertions, 0 deletions

diff --git a/drivers/md/persistent-data/dm-btree-remove.c b/drivers/md/persistent-data/dm-btree-remove.c
new file mode 100644
index 000000000..aeec5b9a1
--- /dev/null
+++ b/drivers/md/persistent-data/dm-btree-remove.c
@@ -0,0 +1,773 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-btree.h"
+#include "dm-btree-internal.h"
+#include "dm-transaction-manager.h"
+
+#include <linux/export.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "btree"
+
+/*
+ * Removing an entry from a btree
+ * ==============================
+ *
+ * A very important constraint for our btree is that no node, except the
+ * root, may have fewer than a certain number of entries.
+ * (MIN_ENTRIES <= nr_entries <= MAX_ENTRIES).
+ *
+ * Ensuring this is complicated by the way we want to only ever hold the
+ * locks on 2 nodes concurrently, and only change nodes in a top to bottom
+ * fashion.
+ *
+ * Each node may have a left or right sibling.  When decending the spine,
+ * if a node contains only MIN_ENTRIES then we try and increase this to at
+ * least MIN_ENTRIES + 1.  We do this in the following ways:
+ *
+ * [A] No siblings => this can only happen if the node is the root, in which
+ *     case we copy the childs contents over the root.
+ *
+ * [B] No left sibling
+ *     ==> rebalance(node, right sibling)
+ *
+ * [C] No right sibling
+ *     ==> rebalance(left sibling, node)
+ *
+ * [D] Both siblings, total_entries(left, node, right) <= DEL_THRESHOLD
+ *     ==> delete node adding it's contents to left and right
+ *
+ * [E] Both siblings, total_entries(left, node, right) > DEL_THRESHOLD
+ *     ==> rebalance(left, node, right)
+ *
+ * After these operations it's possible that the our original node no
+ * longer contains the desired sub tree.  For this reason this rebalancing
+ * is performed on the children of the current node.  This also avoids
+ * having a special case for the root.
+ *
+ * Once this rebalancing has occurred we can then step into the child node
+ * for internal nodes.  Or delete the entry for leaf nodes.
+ */
+
+/*
+ * Some little utilities for moving node data around.
+ */
+static void node_shift(struct btree_node *n, int shift)
+{
+	uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
+	uint32_t value_size = le32_to_cpu(n->header.value_size);
+
+	if (shift < 0) {
+		shift = -shift;
+		BUG_ON(shift > nr_entries);
+		BUG_ON((void *) key_ptr(n, shift) >= value_ptr(n, shift));
+		memmove(key_ptr(n, 0),
+			key_ptr(n, shift),
+			(nr_entries - shift) * sizeof(__le64));
+		memmove(value_ptr(n, 0),
+			value_ptr(n, shift),
+			(nr_entries - shift) * value_size);
+	} else {
+		BUG_ON(nr_entries + shift > le32_to_cpu(n->header.max_entries));
+		memmove(key_ptr(n, shift),
+			key_ptr(n, 0),
+			nr_entries * sizeof(__le64));
+		memmove(value_ptr(n, shift),
+			value_ptr(n, 0),
+			nr_entries * value_size);
+	}
+}
+
+static int node_copy(struct btree_node *left, struct btree_node *right, int shift)
+{
+	uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
+	uint32_t value_size = le32_to_cpu(left->header.value_size);
+
+	if (value_size != le32_to_cpu(right->header.value_size)) {
+		DMERR("mismatched value size");
+		return -EILSEQ;
+	}
+
+	if (shift < 0) {
+		shift = -shift;
+
+		if (nr_left + shift > le32_to_cpu(left->header.max_entries)) {
+			DMERR("bad shift");
+			return -EINVAL;
+		}
+
+		memcpy(key_ptr(left, nr_left),
+		       key_ptr(right, 0),
+		       shift * sizeof(__le64));
+		memcpy(value_ptr(left, nr_left),
+		       value_ptr(right, 0),
+		       shift * value_size);
+	} else {
+		if (shift > le32_to_cpu(right->header.max_entries)) {
+			DMERR("bad shift");
+			return -EINVAL;
+		}
+
+		memcpy(key_ptr(right, 0),
+		       key_ptr(left, nr_left - shift),
+		       shift * sizeof(__le64));
+		memcpy(value_ptr(right, 0),
+		       value_ptr(left, nr_left - shift),
+		       shift * value_size);
+	}
+	return 0;
+}
+
+/*
+ * Delete a specific entry from a leaf node.
+ */
+static void delete_at(struct btree_node *n, unsigned int index)
+{
+	unsigned int nr_entries = le32_to_cpu(n->header.nr_entries);
+	unsigned int nr_to_copy = nr_entries - (index + 1);
+	uint32_t value_size = le32_to_cpu(n->header.value_size);
+
+	BUG_ON(index >= nr_entries);
+
+	if (nr_to_copy) {
+		memmove(key_ptr(n, index),
+			key_ptr(n, index + 1),
+			nr_to_copy * sizeof(__le64));
+
+		memmove(value_ptr(n, index),
+			value_ptr(n, index + 1),
+			nr_to_copy * value_size);
+	}
+
+	n->header.nr_entries = cpu_to_le32(nr_entries - 1);
+}
+
+static unsigned int merge_threshold(struct btree_node *n)
+{
+	return le32_to_cpu(n->header.max_entries) / 3;
+}
+
+struct child {
+	unsigned int index;
+	struct dm_block *block;
+	struct btree_node *n;
+};
+
+static int init_child(struct dm_btree_info *info, struct dm_btree_value_type *vt,
+		      struct btree_node *parent,
+		      unsigned int index, struct child *result)
+{
+	int r, inc;
+	dm_block_t root;
+
+	result->index = index;
+	root = value64(parent, index);
+
+	r = dm_tm_shadow_block(info->tm, root, &btree_node_validator,
+			       &result->block, &inc);
+	if (r)
+		return r;
+
+	result->n = dm_block_data(result->block);
+
+	if (inc)
+		inc_children(info->tm, result->n, vt);
+
+	*((__le64 *) value_ptr(parent, index)) =
+		cpu_to_le64(dm_block_location(result->block));
+
+	return 0;
+}
+
+static void exit_child(struct dm_btree_info *info, struct child *c)
+{
+	dm_tm_unlock(info->tm, c->block);
+}
+
+static int shift(struct btree_node *left, struct btree_node *right, int count)
+{
+	int r;
+	uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
+	uint32_t nr_right = le32_to_cpu(right->header.nr_entries);
+	uint32_t max_entries = le32_to_cpu(left->header.max_entries);
+	uint32_t r_max_entries = le32_to_cpu(right->header.max_entries);
+
+	if (max_entries != r_max_entries) {
+		DMERR("node max_entries mismatch");
+		return -EILSEQ;
+	}
+
+	if (nr_left - count > max_entries) {
+		DMERR("node shift out of bounds");
+		return -EINVAL;
+	}
+
+	if (nr_right + count > max_entries) {
+		DMERR("node shift out of bounds");
+		return -EINVAL;
+	}
+
+	if (!count)
+		return 0;
+
+	if (count > 0) {
+		node_shift(right, count);
+		r = node_copy(left, right, count);
+		if (r)
+			return r;
+	} else {
+		r = node_copy(left, right, count);
+		if (r)
+			return r;
+		node_shift(right, count);
+	}
+
+	left->header.nr_entries = cpu_to_le32(nr_left - count);
+	right->header.nr_entries = cpu_to_le32(nr_right + count);
+
+	return 0;
+}
+
+static int __rebalance2(struct dm_btree_info *info, struct btree_node *parent,
+			struct child *l, struct child *r)
+{
+	int ret;
+	struct btree_node *left = l->n;
+	struct btree_node *right = r->n;
+	uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
+	uint32_t nr_right = le32_to_cpu(right->header.nr_entries);
+	/*
+	 * Ensure the number of entries in each child will be greater
+	 * than or equal to (max_entries / 3 + 1), so no matter which
+	 * child is used for removal, the number will still be not
+	 * less than (max_entries / 3).
+	 */
+	unsigned int threshold = 2 * (merge_threshold(left) + 1);
+
+	if (nr_left + nr_right < threshold) {
+		/*
+		 * Merge
+		 */
+		node_copy(left, right, -nr_right);
+		left->header.nr_entries = cpu_to_le32(nr_left + nr_right);
+		delete_at(parent, r->index);
+
+		/*
+		 * We need to decrement the right block, but not it's
+		 * children, since they're still referenced by left.
+		 */
+		dm_tm_dec(info->tm, dm_block_location(r->block));
+	} else {
+		/*
+		 * Rebalance.
+		 */
+		unsigned int target_left = (nr_left + nr_right) / 2;
+
+		ret = shift(left, right, nr_left - target_left);
+		if (ret)
+			return ret;
+		*key_ptr(parent, r->index) = right->keys[0];
+	}
+	return 0;
+}
+
+static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info,
+		      struct dm_btree_value_type *vt, unsigned int left_index)
+{
+	int r;
+	struct btree_node *parent;
+	struct child left, right;
+
+	parent = dm_block_data(shadow_current(s));
+
+	r = init_child(info, vt, parent, left_index, &left);
+	if (r)
+		return r;
+
+	r = init_child(info, vt, parent, left_index + 1, &right);
+	if (r) {
+		exit_child(info, &left);
+		return r;
+	}
+
+	r = __rebalance2(info, parent, &left, &right);
+
+	exit_child(info, &left);
+	exit_child(info, &right);
+
+	return r;
+}
+
+/*
+ * We dump as many entries from center as possible into left, then the rest
+ * in right, then rebalance2.  This wastes some cpu, but I want something
+ * simple atm.
+ */
+static int delete_center_node(struct dm_btree_info *info, struct btree_node *parent,
+			      struct child *l, struct child *c, struct child *r,
+			      struct btree_node *left, struct btree_node *center, struct btree_node *right,
+			      uint32_t nr_left, uint32_t nr_center, uint32_t nr_right)
+{
+	uint32_t max_entries = le32_to_cpu(left->header.max_entries);
+	unsigned int shift = min(max_entries - nr_left, nr_center);
+
+	if (nr_left + shift > max_entries) {
+		DMERR("node shift out of bounds");
+		return -EINVAL;
+	}
+
+	node_copy(left, center, -shift);
+	left->header.nr_entries = cpu_to_le32(nr_left + shift);
+
+	if (shift != nr_center) {
+		shift = nr_center - shift;
+
+		if ((nr_right + shift) > max_entries) {
+			DMERR("node shift out of bounds");
+			return -EINVAL;
+		}
+
+		node_shift(right, shift);
+		node_copy(center, right, shift);
+		right->header.nr_entries = cpu_to_le32(nr_right + shift);
+	}
+	*key_ptr(parent, r->index) = right->keys[0];
+
+	delete_at(parent, c->index);
+	r->index--;
+
+	dm_tm_dec(info->tm, dm_block_location(c->block));
+	return __rebalance2(info, parent, l, r);
+}
+
+/*
+ * Redistributes entries among 3 sibling nodes.
+ */
+static int redistribute3(struct dm_btree_info *info, struct btree_node *parent,
+			 struct child *l, struct child *c, struct child *r,
+			 struct btree_node *left, struct btree_node *center, struct btree_node *right,
+			 uint32_t nr_left, uint32_t nr_center, uint32_t nr_right)
+{
+	int s, ret;
+	uint32_t max_entries = le32_to_cpu(left->header.max_entries);
+	unsigned int total = nr_left + nr_center + nr_right;
+	unsigned int target_right = total / 3;
+	unsigned int remainder = (target_right * 3) != total;
+	unsigned int target_left = target_right + remainder;
+
+	BUG_ON(target_left > max_entries);
+	BUG_ON(target_right > max_entries);
+
+	if (nr_left < nr_right) {
+		s = nr_left - target_left;
+
+		if (s < 0 && nr_center < -s) {
+			/* not enough in central node */
+			ret = shift(left, center, -nr_center);
+			if (ret)
+				return ret;
+
+			s += nr_center;
+			ret = shift(left, right, s);
+			if (ret)
+				return ret;
+
+			nr_right += s;
+		} else {
+			ret = shift(left, center, s);
+			if (ret)
+				return ret;
+		}
+
+		ret = shift(center, right, target_right - nr_right);
+		if (ret)
+			return ret;
+	} else {
+		s = target_right - nr_right;
+		if (s > 0 && nr_center < s) {
+			/* not enough in central node */
+			ret = shift(center, right, nr_center);
+			if (ret)
+				return ret;
+			s -= nr_center;
+			ret = shift(left, right, s);
+			if (ret)
+				return ret;
+			nr_left -= s;
+		} else {
+			ret = shift(center, right, s);
+			if (ret)
+				return ret;
+		}
+
+		ret = shift(left, center, nr_left - target_left);
+		if (ret)
+			return ret;
+	}
+
+	*key_ptr(parent, c->index) = center->keys[0];
+	*key_ptr(parent, r->index) = right->keys[0];
+	return 0;
+}
+
+static int __rebalance3(struct dm_btree_info *info, struct btree_node *parent,
+			struct child *l, struct child *c, struct child *r)
+{
+	struct btree_node *left = l->n;
+	struct btree_node *center = c->n;
+	struct btree_node *right = r->n;
+
+	uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
+	uint32_t nr_center = le32_to_cpu(center->header.nr_entries);
+	uint32_t nr_right = le32_to_cpu(right->header.nr_entries);
+
+	unsigned int threshold = merge_threshold(left) * 4 + 1;
+
+	if ((left->header.max_entries != center->header.max_entries) ||
+	    (center->header.max_entries != right->header.max_entries)) {
+		DMERR("bad btree metadata, max_entries differ");
+		return -EILSEQ;
+	}
+
+	if ((nr_left + nr_center + nr_right) < threshold) {
+		return delete_center_node(info, parent, l, c, r, left, center, right,
+					  nr_left, nr_center, nr_right);
+	}
+
+	return redistribute3(info, parent, l, c, r, left, center, right,
+			     nr_left, nr_center, nr_right);
+}
+
+static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info,
+		      struct dm_btree_value_type *vt, unsigned int left_index)
+{
+	int r;
+	struct btree_node *parent = dm_block_data(shadow_current(s));
+	struct child left, center, right;
+
+	/*
+	 * FIXME: fill out an array?
+	 */
+	r = init_child(info, vt, parent, left_index, &left);
+	if (r)
+		return r;
+
+	r = init_child(info, vt, parent, left_index + 1, &center);
+	if (r) {
+		exit_child(info, &left);
+		return r;
+	}
+
+	r = init_child(info, vt, parent, left_index + 2, &right);
+	if (r) {
+		exit_child(info, &left);
+		exit_child(info, &center);
+		return r;
+	}
+
+	r = __rebalance3(info, parent, &left, &center, &right);
+
+	exit_child(info, &left);
+	exit_child(info, &center);
+	exit_child(info, &right);
+
+	return r;
+}
+
+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;
+	struct btree_node *n;
+
+	n = dm_block_data(shadow_current(s));
+
+	if (le32_to_cpu(n->header.nr_entries) == 1) {
+		struct dm_block *child;
+		int is_shared;
+		dm_block_t b = value64(n, 0);
+
+		r = dm_tm_block_is_shared(info->tm, b, &is_shared);
+		if (r)
+			return r;
+
+		r = dm_tm_read_lock(info->tm, b, &btree_node_validator, &child);
+		if (r)
+			return r;
+
+		if (is_shared)
+			inc_children(info->tm, dm_block_data(child), vt);
+
+		memcpy(n, dm_block_data(child),
+		       dm_bm_block_size(dm_tm_get_bm(info->tm)));
+
+		dm_tm_dec(info->tm, dm_block_location(child));
+		dm_tm_unlock(info->tm, child);
+		return 0;
+	}
+
+	i = lower_bound(n, key);
+	if (i < 0)
+		return -ENODATA;
+
+	has_left_sibling = i > 0;
+	has_right_sibling = i < (le32_to_cpu(n->header.nr_entries) - 1);
+
+	if (!has_left_sibling)
+		r = rebalance2(s, info, vt, i);
+
+	else if (!has_right_sibling)
+		r = rebalance2(s, info, vt, i - 1);
+
+	else
+		r = rebalance3(s, info, vt, i - 1);
+
+	return r;
+}
+
+static int do_leaf(struct btree_node *n, uint64_t key, unsigned int *index)
+{
+	int i = lower_bound(n, key);
+
+	if ((i < 0) ||
+	    (i >= le32_to_cpu(n->header.nr_entries)) ||
+	    (le64_to_cpu(n->keys[i]) != key))
+		return -ENODATA;
+
+	*index = i;
+
+	return 0;
+}
+
+/*
+ * Prepares for removal from one level of the hierarchy.  The caller must
+ * call delete_at() to remove the entry at index.
+ */
+static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info,
+		      struct dm_btree_value_type *vt, dm_block_t root,
+		      uint64_t key, unsigned 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)
+			return do_leaf(n, key, index);
+
+		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)
+			return do_leaf(n, key, index);
+
+		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;
+}
+
+int dm_btree_remove(struct dm_btree_info *info, dm_block_t root,
+		    uint64_t *keys, dm_block_t *new_root)
+{
+	unsigned int 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;
+
+	init_le64_type(info->tm, &le64_vt);
+	init_shadow_spine(&spine, info);
+	for (level = 0; level < info->levels; level++) {
+		r = remove_raw(&spine, info,
+			       (level == last_level ?
+				&info->value_type : &le64_vt),
+			       root, keys[level], (unsigned int *)&index);
+		if (r < 0)
+			break;
+
+		n = dm_block_data(shadow_current(&spine));
+		if (level != last_level) {
+			root = value64(n, index);
+			continue;
+		}
+
+		BUG_ON(index < 0 || index >= le32_to_cpu(n->header.nr_entries));
+
+		if (info->value_type.dec)
+			info->value_type.dec(info->value_type.context,
+					     value_ptr(n, index), 1);
+
+		delete_at(n, index);
+	}
+
+	if (!r)
+		*new_root = shadow_root(&spine);
+	exit_shadow_spine(&spine);
+
+	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 int *nr_removed)
+{
+	unsigned int 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 int *) &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), 1);
+
+		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 int *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);