fs/xfs/scrub/bitmap.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2018-2023 Oracle.  All Rights Reserved.
  * Author: Darrick J. Wong <djwong@kernel.org>
  */
 #include "xfs.h"
 #include "xfs_fs.h"
 #include "xfs_shared.h"
 #include "xfs_bit.h"
 #include "xfs_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
 #include "xfs_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/bitmap.h"

 #include <linux/interval_tree_generic.h>

 /* u64 bitmap */

 struct xbitmap64_node {
 	struct rb_node	bn_rbnode;

 	/* First set bit of this interval and subtree. */
 	uint64_t	bn_start;

 	/* Last set bit of this interval. */
 	uint64_t	bn_last;

 	/* Last set bit of this subtree.  Do not touch this. */
 	uint64_t	__bn_subtree_last;
 };

 /* Define our own interval tree type with uint64_t parameters. */

 #define START(node) ((node)->bn_start)
 #define LAST(node)  ((node)->bn_last)

 /*
  * These functions are defined by the INTERVAL_TREE_DEFINE macro, but we'll
  * forward-declare them anyway for clarity.
  */
 static inline __maybe_unused void
 xbitmap64_tree_insert(struct xbitmap64_node *node, struct rb_root_cached *root);

 static inline __maybe_unused void
 xbitmap64_tree_remove(struct xbitmap64_node *node, struct rb_root_cached *root);

 static inline __maybe_unused struct xbitmap64_node *
 xbitmap64_tree_iter_first(struct rb_root_cached *root, uint64_t start,
 			uint64_t last);

 static inline __maybe_unused struct xbitmap64_node *
 xbitmap64_tree_iter_next(struct xbitmap64_node *node, uint64_t start,
 		       uint64_t last);

 INTERVAL_TREE_DEFINE(struct xbitmap64_node, bn_rbnode, uint64_t,
 		__bn_subtree_last, START, LAST, static inline __maybe_unused,
 		xbitmap64_tree)

 /* Iterate each interval of a bitmap.  Do not change the bitmap. */
 #define for_each_xbitmap64_extent(bn, bitmap) \
 	for ((bn) = rb_entry_safe(rb_first(&(bitmap)->xb_root.rb_root), \
 				   struct xbitmap64_node, bn_rbnode); \
 	     (bn) != NULL; \
 	     (bn) = rb_entry_safe(rb_next(&(bn)->bn_rbnode), \
 				   struct xbitmap64_node, bn_rbnode))

 /* Clear a range of this bitmap. */
 int
 xbitmap64_clear(
 	struct xbitmap64	*bitmap,
 	uint64_t		start,
 	uint64_t		len)
 {
 	struct xbitmap64_node	*bn;
 	struct xbitmap64_node	*new_bn;
 	uint64_t		last = start + len - 1;

 	while ((bn = xbitmap64_tree_iter_first(&bitmap->xb_root, start, last))) {
 		if (bn->bn_start < start && bn->bn_last > last) {
 			uint64_t	old_last = bn->bn_last;

 			/* overlaps with the entire clearing range */
 			xbitmap64_tree_remove(bn, &bitmap->xb_root);
 			bn->bn_last = start - 1;
 			xbitmap64_tree_insert(bn, &bitmap->xb_root);

 			/* add an extent */
 			new_bn = kmalloc(sizeof(struct xbitmap64_node),
 					XCHK_GFP_FLAGS);
 			if (!new_bn)
 				return -ENOMEM;
 			new_bn->bn_start = last + 1;
 			new_bn->bn_last = old_last;
 			xbitmap64_tree_insert(new_bn, &bitmap->xb_root);
 		} else if (bn->bn_start < start) {
 			/* overlaps with the left side of the clearing range */
 			xbitmap64_tree_remove(bn, &bitmap->xb_root);
 			bn->bn_last = start - 1;
 			xbitmap64_tree_insert(bn, &bitmap->xb_root);
 		} else if (bn->bn_last > last) {
 			/* overlaps with the right side of the clearing range */
 			xbitmap64_tree_remove(bn, &bitmap->xb_root);
 			bn->bn_start = last + 1;
 			xbitmap64_tree_insert(bn, &bitmap->xb_root);
 			break;
 		} else {
 			/* in the middle of the clearing range */
 			xbitmap64_tree_remove(bn, &bitmap->xb_root);
 			kfree(bn);
 		}
 	}

 	return 0;
 }

 /* Set a range of this bitmap. */
 int
 xbitmap64_set(
 	struct xbitmap64	*bitmap,
 	uint64_t		start,
 	uint64_t		len)
 {
 	struct xbitmap64_node	*left;
 	struct xbitmap64_node	*right;
 	uint64_t		last = start + len - 1;
 	int			error;

 	/* Is this whole range already set? */
 	left = xbitmap64_tree_iter_first(&bitmap->xb_root, start, last);
 	if (left && left->bn_start <= start && left->bn_last >= last)
 		return 0;

 	/* Clear out everything in the range we want to set. */
 	error = xbitmap64_clear(bitmap, start, len);
 	if (error)
 		return error;

 	/* Do we have a left-adjacent extent? */
 	left = xbitmap64_tree_iter_first(&bitmap->xb_root, start - 1, start - 1);
 	ASSERT(!left || left->bn_last + 1 == start);

 	/* Do we have a right-adjacent extent? */
 	right = xbitmap64_tree_iter_first(&bitmap->xb_root, last + 1, last + 1);
 	ASSERT(!right || right->bn_start == last + 1);

 	if (left && right) {
 		/* combine left and right adjacent extent */
 		xbitmap64_tree_remove(left, &bitmap->xb_root);
 		xbitmap64_tree_remove(right, &bitmap->xb_root);
 		left->bn_last = right->bn_last;
 		xbitmap64_tree_insert(left, &bitmap->xb_root);
 		kfree(right);
 	} else if (left) {
 		/* combine with left extent */
 		xbitmap64_tree_remove(left, &bitmap->xb_root);
 		left->bn_last = last;
 		xbitmap64_tree_insert(left, &bitmap->xb_root);
 	} else if (right) {
 		/* combine with right extent */
 		xbitmap64_tree_remove(right, &bitmap->xb_root);
 		right->bn_start = start;
 		xbitmap64_tree_insert(right, &bitmap->xb_root);
 	} else {
 		/* add an extent */
 		left = kmalloc(sizeof(struct xbitmap64_node), XCHK_GFP_FLAGS);
 		if (!left)
 			return -ENOMEM;
 		left->bn_start = start;
 		left->bn_last = last;
 		xbitmap64_tree_insert(left, &bitmap->xb_root);
 	}

 	return 0;
 }

 /* Free everything related to this bitmap. */
 void
 xbitmap64_destroy(
 	struct xbitmap64	*bitmap)
 {
 	struct xbitmap64_node	*bn;

 	while ((bn = xbitmap64_tree_iter_first(&bitmap->xb_root, 0, -1ULL))) {
 		xbitmap64_tree_remove(bn, &bitmap->xb_root);
 		kfree(bn);
 	}
 }

 /* Set up a per-AG block bitmap. */
 void
 xbitmap64_init(
 	struct xbitmap64	*bitmap)
 {
 	bitmap->xb_root = RB_ROOT_CACHED;
 }

 /*
  * Remove all the blocks mentioned in @sub from the extents in @bitmap.
  *
  * The intent is that callers will iterate the rmapbt for all of its records
  * for a given owner to generate @bitmap; and iterate all the blocks of the
  * metadata structures that are not being rebuilt and have the same rmapbt
  * owner to generate @sub.  This routine subtracts all the extents
  * mentioned in sub from all the extents linked in @bitmap, which leaves
  * @bitmap as the list of blocks that are not accounted for, which we assume
  * are the dead blocks of the old metadata structure.  The blocks mentioned in
  * @bitmap can be reaped.
  *
  * This is the logical equivalent of bitmap &= ~sub.
  */
 int
 xbitmap64_disunion(
 	struct xbitmap64	*bitmap,
 	struct xbitmap64	*sub)
 {
 	struct xbitmap64_node	*bn;
 	int			error;

 	if (xbitmap64_empty(bitmap) || xbitmap64_empty(sub))
 		return 0;

 	for_each_xbitmap64_extent(bn, sub) {
 		error = xbitmap64_clear(bitmap, bn->bn_start,
 				bn->bn_last - bn->bn_start + 1);
 		if (error)
 			return error;
 	}

 	return 0;
 }

 /* How many bits are set in this bitmap? */
 uint64_t
 xbitmap64_hweight(
 	struct xbitmap64	*bitmap)
 {
 	struct xbitmap64_node	*bn;
 	uint64_t		ret = 0;

 	for_each_xbitmap64_extent(bn, bitmap)
 		ret += bn->bn_last - bn->bn_start + 1;

 	return ret;
 }

 /* Call a function for every run of set bits in this bitmap. */
 int
 xbitmap64_walk(
 	struct xbitmap64	*bitmap,
 	xbitmap64_walk_fn		fn,
 	void			*priv)
 {
 	struct xbitmap64_node	*bn;
 	int			error = 0;

 	for_each_xbitmap64_extent(bn, bitmap) {
 		error = fn(bn->bn_start, bn->bn_last - bn->bn_start + 1, priv);
 		if (error)
 			break;
 	}

 	return error;
 }

 /* Does this bitmap have no bits set at all? */
 bool
 xbitmap64_empty(
 	struct xbitmap64	*bitmap)
 {
 	return bitmap->xb_root.rb_root.rb_node == NULL;
 }

 /* Is the start of the range set or clear?  And for how long? */
 bool
 xbitmap64_test(
 	struct xbitmap64	*bitmap,
 	uint64_t		start,
 	uint64_t		*len)
 {
 	struct xbitmap64_node	*bn;
 	uint64_t		last = start + *len - 1;

 	bn = xbitmap64_tree_iter_first(&bitmap->xb_root, start, last);
 	if (!bn)
 		return false;
 	if (bn->bn_start <= start) {
 		if (bn->bn_last < last)
 			*len = bn->bn_last - start + 1;
 		return true;
 	}
 	*len = bn->bn_start - start;
 	return false;
 }

 /* u32 bitmap */

 struct xbitmap32_node {
 	struct rb_node	bn_rbnode;

 	/* First set bit of this interval and subtree. */
 	uint32_t	bn_start;

 	/* Last set bit of this interval. */
 	uint32_t	bn_last;

 	/* Last set bit of this subtree.  Do not touch this. */
 	uint32_t	__bn_subtree_last;
 };

 /* Define our own interval tree type with uint32_t parameters. */

 /*
  * These functions are defined by the INTERVAL_TREE_DEFINE macro, but we'll
  * forward-declare them anyway for clarity.
  */
 static inline __maybe_unused void
 xbitmap32_tree_insert(struct xbitmap32_node *node, struct rb_root_cached *root);

 static inline __maybe_unused void
 xbitmap32_tree_remove(struct xbitmap32_node *node, struct rb_root_cached *root);

 static inline __maybe_unused struct xbitmap32_node *
 xbitmap32_tree_iter_first(struct rb_root_cached *root, uint32_t start,
 			  uint32_t last);

 static inline __maybe_unused struct xbitmap32_node *
 xbitmap32_tree_iter_next(struct xbitmap32_node *node, uint32_t start,
 			 uint32_t last);

 INTERVAL_TREE_DEFINE(struct xbitmap32_node, bn_rbnode, uint32_t,
 		__bn_subtree_last, START, LAST, static inline __maybe_unused,
 		xbitmap32_tree)

 /* Iterate each interval of a bitmap.  Do not change the bitmap. */
 #define for_each_xbitmap32_extent(bn, bitmap) \
 	for ((bn) = rb_entry_safe(rb_first(&(bitmap)->xb_root.rb_root), \
 				   struct xbitmap32_node, bn_rbnode); \
 	     (bn) != NULL; \
 	     (bn) = rb_entry_safe(rb_next(&(bn)->bn_rbnode), \
 				   struct xbitmap32_node, bn_rbnode))

 /* Clear a range of this bitmap. */
 int
 xbitmap32_clear(
 	struct xbitmap32	*bitmap,
 	uint32_t		start,
 	uint32_t		len)
 {
 	struct xbitmap32_node	*bn;
 	struct xbitmap32_node	*new_bn;
 	uint32_t		last = start + len - 1;

 	while ((bn = xbitmap32_tree_iter_first(&bitmap->xb_root, start, last))) {
 		if (bn->bn_start < start && bn->bn_last > last) {
 			uint32_t	old_last = bn->bn_last;

 			/* overlaps with the entire clearing range */
 			xbitmap32_tree_remove(bn, &bitmap->xb_root);
 			bn->bn_last = start - 1;
 			xbitmap32_tree_insert(bn, &bitmap->xb_root);

 			/* add an extent */
 			new_bn = kmalloc(sizeof(struct xbitmap32_node),
 					XCHK_GFP_FLAGS);
 			if (!new_bn)
 				return -ENOMEM;
 			new_bn->bn_start = last + 1;
 			new_bn->bn_last = old_last;
 			xbitmap32_tree_insert(new_bn, &bitmap->xb_root);
 		} else if (bn->bn_start < start) {
 			/* overlaps with the left side of the clearing range */
 			xbitmap32_tree_remove(bn, &bitmap->xb_root);
 			bn->bn_last = start - 1;
 			xbitmap32_tree_insert(bn, &bitmap->xb_root);
 		} else if (bn->bn_last > last) {
 			/* overlaps with the right side of the clearing range */
 			xbitmap32_tree_remove(bn, &bitmap->xb_root);
 			bn->bn_start = last + 1;
 			xbitmap32_tree_insert(bn, &bitmap->xb_root);
 			break;
 		} else {
 			/* in the middle of the clearing range */
 			xbitmap32_tree_remove(bn, &bitmap->xb_root);
 			kfree(bn);
 		}
 	}

 	return 0;
 }

 /* Set a range of this bitmap. */
 int
 xbitmap32_set(
 	struct xbitmap32	*bitmap,
 	uint32_t		start,
 	uint32_t		len)
 {
 	struct xbitmap32_node	*left;
 	struct xbitmap32_node	*right;
 	uint32_t		last = start + len - 1;
 	int			error;

 	/* Is this whole range already set? */
 	left = xbitmap32_tree_iter_first(&bitmap->xb_root, start, last);
 	if (left && left->bn_start <= start && left->bn_last >= last)
 		return 0;

 	/* Clear out everything in the range we want to set. */
 	error = xbitmap32_clear(bitmap, start, len);
 	if (error)
 		return error;

 	/* Do we have a left-adjacent extent? */
 	left = xbitmap32_tree_iter_first(&bitmap->xb_root, start - 1, start - 1);
 	ASSERT(!left || left->bn_last + 1 == start);

 	/* Do we have a right-adjacent extent? */
 	right = xbitmap32_tree_iter_first(&bitmap->xb_root, last + 1, last + 1);
 	ASSERT(!right || right->bn_start == last + 1);

 	if (left && right) {
 		/* combine left and right adjacent extent */
 		xbitmap32_tree_remove(left, &bitmap->xb_root);
 		xbitmap32_tree_remove(right, &bitmap->xb_root);
 		left->bn_last = right->bn_last;
 		xbitmap32_tree_insert(left, &bitmap->xb_root);
 		kfree(right);
 	} else if (left) {
 		/* combine with left extent */
 		xbitmap32_tree_remove(left, &bitmap->xb_root);
 		left->bn_last = last;
 		xbitmap32_tree_insert(left, &bitmap->xb_root);
 	} else if (right) {
 		/* combine with right extent */
 		xbitmap32_tree_remove(right, &bitmap->xb_root);
 		right->bn_start = start;
 		xbitmap32_tree_insert(right, &bitmap->xb_root);
 	} else {
 		/* add an extent */
 		left = kmalloc(sizeof(struct xbitmap32_node), XCHK_GFP_FLAGS);
 		if (!left)
 			return -ENOMEM;
 		left->bn_start = start;
 		left->bn_last = last;
 		xbitmap32_tree_insert(left, &bitmap->xb_root);
 	}

 	return 0;
 }

 /* Free everything related to this bitmap. */
 void
 xbitmap32_destroy(
 	struct xbitmap32	*bitmap)
 {
 	struct xbitmap32_node	*bn;

 	while ((bn = xbitmap32_tree_iter_first(&bitmap->xb_root, 0, -1U))) {
 		xbitmap32_tree_remove(bn, &bitmap->xb_root);
 		kfree(bn);
 	}
 }

 /* Set up a per-AG block bitmap. */
 void
 xbitmap32_init(
 	struct xbitmap32	*bitmap)
 {
 	bitmap->xb_root = RB_ROOT_CACHED;
 }

 /*
  * Remove all the blocks mentioned in @sub from the extents in @bitmap.
  *
  * The intent is that callers will iterate the rmapbt for all of its records
  * for a given owner to generate @bitmap; and iterate all the blocks of the
  * metadata structures that are not being rebuilt and have the same rmapbt
  * owner to generate @sub.  This routine subtracts all the extents
  * mentioned in sub from all the extents linked in @bitmap, which leaves
  * @bitmap as the list of blocks that are not accounted for, which we assume
  * are the dead blocks of the old metadata structure.  The blocks mentioned in
  * @bitmap can be reaped.
  *
  * This is the logical equivalent of bitmap &= ~sub.
  */
 int
 xbitmap32_disunion(
 	struct xbitmap32	*bitmap,
 	struct xbitmap32	*sub)
 {
 	struct xbitmap32_node	*bn;
 	int			error;

 	if (xbitmap32_empty(bitmap) || xbitmap32_empty(sub))
 		return 0;

 	for_each_xbitmap32_extent(bn, sub) {
 		error = xbitmap32_clear(bitmap, bn->bn_start,
 				bn->bn_last - bn->bn_start + 1);
 		if (error)
 			return error;
 	}

 	return 0;
 }

 /* How many bits are set in this bitmap? */
 uint32_t
 xbitmap32_hweight(
 	struct xbitmap32	*bitmap)
 {
 	struct xbitmap32_node	*bn;
 	uint32_t		ret = 0;

 	for_each_xbitmap32_extent(bn, bitmap)
 		ret += bn->bn_last - bn->bn_start + 1;

 	return ret;
 }

 /* Call a function for every run of set bits in this bitmap. */
 int
 xbitmap32_walk(
 	struct xbitmap32	*bitmap,
 	xbitmap32_walk_fn	fn,
 	void			*priv)
 {
 	struct xbitmap32_node	*bn;
 	int			error = 0;

 	for_each_xbitmap32_extent(bn, bitmap) {
 		error = fn(bn->bn_start, bn->bn_last - bn->bn_start + 1, priv);
 		if (error)
 			break;
 	}

 	return error;
 }

 /* Does this bitmap have no bits set at all? */
 bool
 xbitmap32_empty(
 	struct xbitmap32	*bitmap)
 {
 	return bitmap->xb_root.rb_root.rb_node == NULL;
 }

 /* Is the start of the range set or clear?  And for how long? */
 bool
 xbitmap32_test(
 	struct xbitmap32	*bitmap,
 	uint32_t		start,
 	uint32_t		*len)
 {
 	struct xbitmap32_node	*bn;
 	uint32_t		last = start + *len - 1;

 	bn = xbitmap32_tree_iter_first(&bitmap->xb_root, start, last);
 	if (!bn)
 		return false;
 	if (bn->bn_start <= start) {
 		if (bn->bn_last < last)
 			*len = bn->bn_last - start + 1;
 		return true;
 	}
 	*len = bn->bn_start - start;
 	return false;
 }

 /* Count the number of set regions in this bitmap. */
 uint32_t
 xbitmap32_count_set_regions(
 	struct xbitmap32	*bitmap)
 {
 	struct xbitmap32_node	*bn;
 	uint32_t		nr = 0;

 	for_each_xbitmap32_extent(bn, bitmap)
 		nr++;

 	return nr;
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Copyright (C) 2018-2023 Oracle. All Rights Reserved.
	* Author: Darrick J. Wong <djwong@kernel.org>
	*/
	#include "xfs.h"
	#include "xfs_fs.h"
	#include "xfs_shared.h"
	#include "xfs_bit.h"
	#include "xfs_format.h"
	#include "xfs_trans_resv.h"
	#include "xfs_mount.h"
	#include "xfs_btree.h"
	#include "scrub/scrub.h"
	#include "scrub/bitmap.h"

	#include <linux/interval_tree_generic.h>

	/* u64 bitmap */

	struct xbitmap64_node {
	struct rb_node bn_rbnode;

	/* First set bit of this interval and subtree. */
	uint64_t bn_start;

	/* Last set bit of this interval. */
	uint64_t bn_last;

	/* Last set bit of this subtree. Do not touch this. */
	uint64_t __bn_subtree_last;
	};

	/* Define our own interval tree type with uint64_t parameters. */

	#define START(node) ((node)->bn_start)
	#define LAST(node) ((node)->bn_last)

	/*
	* These functions are defined by the INTERVAL_TREE_DEFINE macro, but we'll
	* forward-declare them anyway for clarity.
	*/
	static inline __maybe_unused void
	xbitmap64_tree_insert(struct xbitmap64_node node, struct rb_root_cached root);

	static inline __maybe_unused void
	xbitmap64_tree_remove(struct xbitmap64_node node, struct rb_root_cached root);

	static inline __maybe_unused struct xbitmap64_node *
	xbitmap64_tree_iter_first(struct rb_root_cached *root, uint64_t start,
	uint64_t last);

	static inline __maybe_unused struct xbitmap64_node *
	xbitmap64_tree_iter_next(struct xbitmap64_node *node, uint64_t start,
	uint64_t last);

	INTERVAL_TREE_DEFINE(struct xbitmap64_node, bn_rbnode, uint64_t,
	__bn_subtree_last, START, LAST, static inline __maybe_unused,
	xbitmap64_tree)

	/* Iterate each interval of a bitmap. Do not change the bitmap. */
	#define for_each_xbitmap64_extent(bn, bitmap) \
	for ((bn) = rb_entry_safe(rb_first(&(bitmap)->xb_root.rb_root), \
	struct xbitmap64_node, bn_rbnode); \
	(bn) != NULL; \
	(bn) = rb_entry_safe(rb_next(&(bn)->bn_rbnode), \
	struct xbitmap64_node, bn_rbnode))

	/* Clear a range of this bitmap. */
	int
	xbitmap64_clear(
	struct xbitmap64 *bitmap,
	uint64_t start,
	uint64_t len)
	{
	struct xbitmap64_node *bn;
	struct xbitmap64_node *new_bn;
	uint64_t last = start + len - 1;

	while ((bn = xbitmap64_tree_iter_first(&bitmap->xb_root, start, last))) {
	if (bn->bn_start < start && bn->bn_last > last) {
	uint64_t old_last = bn->bn_last;

	/* overlaps with the entire clearing range */
	xbitmap64_tree_remove(bn, &bitmap->xb_root);
	bn->bn_last = start - 1;
	xbitmap64_tree_insert(bn, &bitmap->xb_root);

	/* add an extent */
	new_bn = kmalloc(sizeof(struct xbitmap64_node),
	XCHK_GFP_FLAGS);
	if (!new_bn)
	return -ENOMEM;
	new_bn->bn_start = last + 1;
	new_bn->bn_last = old_last;
	xbitmap64_tree_insert(new_bn, &bitmap->xb_root);
	} else if (bn->bn_start < start) {
	/* overlaps with the left side of the clearing range */
	xbitmap64_tree_remove(bn, &bitmap->xb_root);
	bn->bn_last = start - 1;
	xbitmap64_tree_insert(bn, &bitmap->xb_root);
	} else if (bn->bn_last > last) {
	/* overlaps with the right side of the clearing range */
	xbitmap64_tree_remove(bn, &bitmap->xb_root);
	bn->bn_start = last + 1;
	xbitmap64_tree_insert(bn, &bitmap->xb_root);
	break;
	} else {
	/* in the middle of the clearing range */
	xbitmap64_tree_remove(bn, &bitmap->xb_root);
	kfree(bn);
	}
	}

	return 0;
	}

	/* Set a range of this bitmap. */
	int
	xbitmap64_set(
	struct xbitmap64 *bitmap,
	uint64_t start,
	uint64_t len)
	{
	struct xbitmap64_node *left;
	struct xbitmap64_node *right;
	uint64_t last = start + len - 1;
	int error;

	/* Is this whole range already set? */
	left = xbitmap64_tree_iter_first(&bitmap->xb_root, start, last);
	if (left && left->bn_start <= start && left->bn_last >= last)
	return 0;

	/* Clear out everything in the range we want to set. */
	error = xbitmap64_clear(bitmap, start, len);
	if (error)
	return error;

	/* Do we have a left-adjacent extent? */
	left = xbitmap64_tree_iter_first(&bitmap->xb_root, start - 1, start - 1);
	ASSERT(!left \|\| left->bn_last + 1 == start);

	/* Do we have a right-adjacent extent? */
	right = xbitmap64_tree_iter_first(&bitmap->xb_root, last + 1, last + 1);
	ASSERT(!right \|\| right->bn_start == last + 1);

	if (left && right) {
	/* combine left and right adjacent extent */
	xbitmap64_tree_remove(left, &bitmap->xb_root);
	xbitmap64_tree_remove(right, &bitmap->xb_root);
	left->bn_last = right->bn_last;
	xbitmap64_tree_insert(left, &bitmap->xb_root);
	kfree(right);
	} else if (left) {
	/* combine with left extent */
	xbitmap64_tree_remove(left, &bitmap->xb_root);
	left->bn_last = last;
	xbitmap64_tree_insert(left, &bitmap->xb_root);
	} else if (right) {
	/* combine with right extent */
	xbitmap64_tree_remove(right, &bitmap->xb_root);
	right->bn_start = start;
	xbitmap64_tree_insert(right, &bitmap->xb_root);
	} else {
	/* add an extent */
	left = kmalloc(sizeof(struct xbitmap64_node), XCHK_GFP_FLAGS);
	if (!left)
	return -ENOMEM;
	left->bn_start = start;
	left->bn_last = last;
	xbitmap64_tree_insert(left, &bitmap->xb_root);
	}

	return 0;
	}

	/* Free everything related to this bitmap. */
	void
	xbitmap64_destroy(
	struct xbitmap64 *bitmap)
	{
	struct xbitmap64_node *bn;

	while ((bn = xbitmap64_tree_iter_first(&bitmap->xb_root, 0, -1ULL))) {
	xbitmap64_tree_remove(bn, &bitmap->xb_root);
	kfree(bn);
	}
	}

	/* Set up a per-AG block bitmap. */
	void
	xbitmap64_init(
	struct xbitmap64 *bitmap)
	{
	bitmap->xb_root = RB_ROOT_CACHED;
	}

	/*
	* Remove all the blocks mentioned in @sub from the extents in @bitmap.
	*
	* The intent is that callers will iterate the rmapbt for all of its records
	* for a given owner to generate @bitmap; and iterate all the blocks of the
	* metadata structures that are not being rebuilt and have the same rmapbt
	* owner to generate @sub. This routine subtracts all the extents
	* mentioned in sub from all the extents linked in @bitmap, which leaves
	* @bitmap as the list of blocks that are not accounted for, which we assume
	* are the dead blocks of the old metadata structure. The blocks mentioned in
	* @bitmap can be reaped.
	*
	* This is the logical equivalent of bitmap &= ~sub.
	*/
	int
	xbitmap64_disunion(
	struct xbitmap64 *bitmap,
	struct xbitmap64 *sub)
	{
	struct xbitmap64_node *bn;
	int error;

	if (xbitmap64_empty(bitmap) \|\| xbitmap64_empty(sub))
	return 0;

	for_each_xbitmap64_extent(bn, sub) {
	error = xbitmap64_clear(bitmap, bn->bn_start,
	bn->bn_last - bn->bn_start + 1);
	if (error)
	return error;
	}

	return 0;
	}

	/* How many bits are set in this bitmap? */
	uint64_t
	xbitmap64_hweight(
	struct xbitmap64 *bitmap)
	{
	struct xbitmap64_node *bn;
	uint64_t ret = 0;

	for_each_xbitmap64_extent(bn, bitmap)
	ret += bn->bn_last - bn->bn_start + 1;

	return ret;
	}

	/* Call a function for every run of set bits in this bitmap. */
	int
	xbitmap64_walk(
	struct xbitmap64 *bitmap,
	xbitmap64_walk_fn fn,
	void *priv)
	{
	struct xbitmap64_node *bn;
	int error = 0;

	for_each_xbitmap64_extent(bn, bitmap) {
	error = fn(bn->bn_start, bn->bn_last - bn->bn_start + 1, priv);
	if (error)
	break;
	}

	return error;
	}

	/* Does this bitmap have no bits set at all? */
	bool
	xbitmap64_empty(
	struct xbitmap64 *bitmap)
	{
	return bitmap->xb_root.rb_root.rb_node == NULL;
	}

	/* Is the start of the range set or clear? And for how long? */
	bool
	xbitmap64_test(
	struct xbitmap64 *bitmap,
	uint64_t start,
	uint64_t *len)
	{
	struct xbitmap64_node *bn;
	uint64_t last = start + *len - 1;

	bn = xbitmap64_tree_iter_first(&bitmap->xb_root, start, last);
	if (!bn)
	return false;
	if (bn->bn_start <= start) {
	if (bn->bn_last < last)
	*len = bn->bn_last - start + 1;
	return true;
	}
	*len = bn->bn_start - start;
	return false;
	}

	/* u32 bitmap */

	struct xbitmap32_node {
	struct rb_node bn_rbnode;

	/* First set bit of this interval and subtree. */
	uint32_t bn_start;

	/* Last set bit of this interval. */
	uint32_t bn_last;

	/* Last set bit of this subtree. Do not touch this. */
	uint32_t __bn_subtree_last;
	};

	/* Define our own interval tree type with uint32_t parameters. */

	/*
	* These functions are defined by the INTERVAL_TREE_DEFINE macro, but we'll
	* forward-declare them anyway for clarity.
	*/
	static inline __maybe_unused void
	xbitmap32_tree_insert(struct xbitmap32_node node, struct rb_root_cached root);

	static inline __maybe_unused void
	xbitmap32_tree_remove(struct xbitmap32_node node, struct rb_root_cached root);

	static inline __maybe_unused struct xbitmap32_node *
	xbitmap32_tree_iter_first(struct rb_root_cached *root, uint32_t start,
	uint32_t last);

	static inline __maybe_unused struct xbitmap32_node *
	xbitmap32_tree_iter_next(struct xbitmap32_node *node, uint32_t start,
	uint32_t last);

	INTERVAL_TREE_DEFINE(struct xbitmap32_node, bn_rbnode, uint32_t,
	__bn_subtree_last, START, LAST, static inline __maybe_unused,
	xbitmap32_tree)

	/* Iterate each interval of a bitmap. Do not change the bitmap. */
	#define for_each_xbitmap32_extent(bn, bitmap) \
	for ((bn) = rb_entry_safe(rb_first(&(bitmap)->xb_root.rb_root), \
	struct xbitmap32_node, bn_rbnode); \
	(bn) != NULL; \
	(bn) = rb_entry_safe(rb_next(&(bn)->bn_rbnode), \
	struct xbitmap32_node, bn_rbnode))

	/* Clear a range of this bitmap. */
	int
	xbitmap32_clear(
	struct xbitmap32 *bitmap,
	uint32_t start,
	uint32_t len)
	{
	struct xbitmap32_node *bn;
	struct xbitmap32_node *new_bn;
	uint32_t last = start + len - 1;

	while ((bn = xbitmap32_tree_iter_first(&bitmap->xb_root, start, last))) {
	if (bn->bn_start < start && bn->bn_last > last) {
	uint32_t old_last = bn->bn_last;

	/* overlaps with the entire clearing range */
	xbitmap32_tree_remove(bn, &bitmap->xb_root);
	bn->bn_last = start - 1;
	xbitmap32_tree_insert(bn, &bitmap->xb_root);

	/* add an extent */
	new_bn = kmalloc(sizeof(struct xbitmap32_node),
	XCHK_GFP_FLAGS);
	if (!new_bn)
	return -ENOMEM;
	new_bn->bn_start = last + 1;
	new_bn->bn_last = old_last;
	xbitmap32_tree_insert(new_bn, &bitmap->xb_root);
	} else if (bn->bn_start < start) {
	/* overlaps with the left side of the clearing range */
	xbitmap32_tree_remove(bn, &bitmap->xb_root);
	bn->bn_last = start - 1;
	xbitmap32_tree_insert(bn, &bitmap->xb_root);
	} else if (bn->bn_last > last) {
	/* overlaps with the right side of the clearing range */
	xbitmap32_tree_remove(bn, &bitmap->xb_root);
	bn->bn_start = last + 1;
	xbitmap32_tree_insert(bn, &bitmap->xb_root);
	break;
	} else {
	/* in the middle of the clearing range */
	xbitmap32_tree_remove(bn, &bitmap->xb_root);
	kfree(bn);
	}
	}

	return 0;
	}

	/* Set a range of this bitmap. */
	int
	xbitmap32_set(
	struct xbitmap32 *bitmap,
	uint32_t start,
	uint32_t len)
	{
	struct xbitmap32_node *left;
	struct xbitmap32_node *right;
	uint32_t last = start + len - 1;
	int error;

	/* Is this whole range already set? */
	left = xbitmap32_tree_iter_first(&bitmap->xb_root, start, last);
	if (left && left->bn_start <= start && left->bn_last >= last)
	return 0;

	/* Clear out everything in the range we want to set. */
	error = xbitmap32_clear(bitmap, start, len);
	if (error)
	return error;

	/* Do we have a left-adjacent extent? */
	left = xbitmap32_tree_iter_first(&bitmap->xb_root, start - 1, start - 1);
	ASSERT(!left \|\| left->bn_last + 1 == start);

	/* Do we have a right-adjacent extent? */
	right = xbitmap32_tree_iter_first(&bitmap->xb_root, last + 1, last + 1);
	ASSERT(!right \|\| right->bn_start == last + 1);

	if (left && right) {
	/* combine left and right adjacent extent */
	xbitmap32_tree_remove(left, &bitmap->xb_root);
	xbitmap32_tree_remove(right, &bitmap->xb_root);
	left->bn_last = right->bn_last;
	xbitmap32_tree_insert(left, &bitmap->xb_root);
	kfree(right);
	} else if (left) {
	/* combine with left extent */
	xbitmap32_tree_remove(left, &bitmap->xb_root);
	left->bn_last = last;
	xbitmap32_tree_insert(left, &bitmap->xb_root);
	} else if (right) {
	/* combine with right extent */
	xbitmap32_tree_remove(right, &bitmap->xb_root);
	right->bn_start = start;
	xbitmap32_tree_insert(right, &bitmap->xb_root);
	} else {
	/* add an extent */
	left = kmalloc(sizeof(struct xbitmap32_node), XCHK_GFP_FLAGS);
	if (!left)
	return -ENOMEM;
	left->bn_start = start;
	left->bn_last = last;
	xbitmap32_tree_insert(left, &bitmap->xb_root);
	}

	return 0;
	}

	/* Free everything related to this bitmap. */
	void
	xbitmap32_destroy(
	struct xbitmap32 *bitmap)
	{
	struct xbitmap32_node *bn;

	while ((bn = xbitmap32_tree_iter_first(&bitmap->xb_root, 0, -1U))) {
	xbitmap32_tree_remove(bn, &bitmap->xb_root);
	kfree(bn);
	}
	}

	/* Set up a per-AG block bitmap. */
	void
	xbitmap32_init(
	struct xbitmap32 *bitmap)
	{
	bitmap->xb_root = RB_ROOT_CACHED;
	}

	/*
	* Remove all the blocks mentioned in @sub from the extents in @bitmap.
	*
	* The intent is that callers will iterate the rmapbt for all of its records
	* for a given owner to generate @bitmap; and iterate all the blocks of the
	* metadata structures that are not being rebuilt and have the same rmapbt
	* owner to generate @sub. This routine subtracts all the extents
	* mentioned in sub from all the extents linked in @bitmap, which leaves
	* @bitmap as the list of blocks that are not accounted for, which we assume
	* are the dead blocks of the old metadata structure. The blocks mentioned in
	* @bitmap can be reaped.
	*
	* This is the logical equivalent of bitmap &= ~sub.
	*/
	int
	xbitmap32_disunion(
	struct xbitmap32 *bitmap,
	struct xbitmap32 *sub)
	{
	struct xbitmap32_node *bn;
	int error;

	if (xbitmap32_empty(bitmap) \|\| xbitmap32_empty(sub))
	return 0;

	for_each_xbitmap32_extent(bn, sub) {
	error = xbitmap32_clear(bitmap, bn->bn_start,
	bn->bn_last - bn->bn_start + 1);
	if (error)
	return error;
	}

	return 0;
	}

	/* How many bits are set in this bitmap? */
	uint32_t
	xbitmap32_hweight(
	struct xbitmap32 *bitmap)
	{
	struct xbitmap32_node *bn;
	uint32_t ret = 0;

	for_each_xbitmap32_extent(bn, bitmap)
	ret += bn->bn_last - bn->bn_start + 1;

	return ret;
	}

	/* Call a function for every run of set bits in this bitmap. */
	int
	xbitmap32_walk(
	struct xbitmap32 *bitmap,
	xbitmap32_walk_fn fn,
	void *priv)
	{
	struct xbitmap32_node *bn;
	int error = 0;

	for_each_xbitmap32_extent(bn, bitmap) {
	error = fn(bn->bn_start, bn->bn_last - bn->bn_start + 1, priv);
	if (error)
	break;
	}

	return error;
	}

	/* Does this bitmap have no bits set at all? */
	bool
	xbitmap32_empty(
	struct xbitmap32 *bitmap)
	{
	return bitmap->xb_root.rb_root.rb_node == NULL;
	}

	/* Is the start of the range set or clear? And for how long? */
	bool
	xbitmap32_test(
	struct xbitmap32 *bitmap,
	uint32_t start,
	uint32_t *len)
	{
	struct xbitmap32_node *bn;
	uint32_t last = start + *len - 1;

	bn = xbitmap32_tree_iter_first(&bitmap->xb_root, start, last);
	if (!bn)
	return false;
	if (bn->bn_start <= start) {
	if (bn->bn_last < last)
	*len = bn->bn_last - start + 1;
	return true;
	}
	*len = bn->bn_start - start;
	return false;
	}

	/* Count the number of set regions in this bitmap. */
	uint32_t
	xbitmap32_count_set_regions(
	struct xbitmap32 *bitmap)
	{
	struct xbitmap32_node *bn;
	uint32_t nr = 0;

	for_each_xbitmap32_extent(bn, bitmap)
	nr++;

	return nr;
	}