/*
 * Copyright (c) 2000-2004 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

#include "xfs.h"

#include "xfs_macros.h"
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_alloc.h"
#include "xfs_btree.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode_item.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_dir_leaf.h"
#include "xfs_dir2_data.h"
#include "xfs_dir2_leaf.h"
#include "xfs_dir2_block.h"
#include "xfs_dir2_node.h"
#include "xfs_error.h"
#include "xfs_bit.h"

/*
 * xfs_da_btree.c
 *
 * Routines to implement directories as Btrees of hashed names.
 */

/*========================================================================
 * Function prototypes for the kernel.
 *========================================================================*/

/*
 * Routines used for growing the Btree.
 */
STATIC int xfs_da_root_split(xfs_da_state_t *state,
					    xfs_da_state_blk_t *existing_root,
					    xfs_da_state_blk_t *new_child);
STATIC int xfs_da_node_split(xfs_da_state_t *state,
					    xfs_da_state_blk_t *existing_blk,
					    xfs_da_state_blk_t *split_blk,
					    xfs_da_state_blk_t *blk_to_add,
					    int treelevel,
					    int *result);
STATIC void xfs_da_node_rebalance(xfs_da_state_t *state,
					 xfs_da_state_blk_t *node_blk_1,
					 xfs_da_state_blk_t *node_blk_2);
STATIC void xfs_da_node_add(xfs_da_state_t *state,
				   xfs_da_state_blk_t *old_node_blk,
				   xfs_da_state_blk_t *new_node_blk);

/*
 * Routines used for shrinking the Btree.
 */
STATIC int xfs_da_root_join(xfs_da_state_t *state,
					   xfs_da_state_blk_t *root_blk);
STATIC int xfs_da_node_toosmall(xfs_da_state_t *state, int *retval);
STATIC void xfs_da_node_remove(xfs_da_state_t *state,
					      xfs_da_state_blk_t *drop_blk);
STATIC void xfs_da_node_unbalance(xfs_da_state_t *state,
					 xfs_da_state_blk_t *src_node_blk,
					 xfs_da_state_blk_t *dst_node_blk);

/*
 * Utility routines.
 */
STATIC uint	xfs_da_node_lasthash(xfs_dabuf_t *bp, int *count);
STATIC int	xfs_da_node_order(xfs_dabuf_t *node1_bp, xfs_dabuf_t *node2_bp);
STATIC xfs_dabuf_t *xfs_da_buf_make(int nbuf, xfs_buf_t **bps, inst_t *ra);


/*========================================================================
 * Routines used for growing the Btree.
 *========================================================================*/

/*
 * Create the initial contents of an intermediate node.
 */
int
xfs_da_node_create(xfs_da_args_t *args, xfs_dablk_t blkno, int level,
				 xfs_dabuf_t **bpp, int whichfork)
{
	xfs_da_intnode_t *node;
	xfs_dabuf_t *bp;
	int error;
	xfs_trans_t *tp;

	tp = args->trans;
	error = xfs_da_get_buf(tp, args->dp, blkno, -1, &bp, whichfork);
	if (error)
		return(error);
	ASSERT(bp != NULL);
	node = bp->data;
	node->hdr.info.forw = 0;
	node->hdr.info.back = 0;
	INT_SET(node->hdr.info.magic, ARCH_CONVERT, XFS_DA_NODE_MAGIC);
	node->hdr.info.pad = 0;
	node->hdr.count = 0;
	INT_SET(node->hdr.level, ARCH_CONVERT, level);

	xfs_da_log_buf(tp, bp,
		XFS_DA_LOGRANGE(node, &node->hdr, sizeof(node->hdr)));

	*bpp = bp;
	return(0);
}

/*
 * Split a leaf node, rebalance, then possibly split
 * intermediate nodes, rebalance, etc.
 */
int							/* error */
xfs_da_split(xfs_da_state_t *state)
{
	xfs_da_state_blk_t *oldblk, *newblk, *addblk;
	xfs_da_intnode_t *node;
	xfs_dabuf_t *bp;
	int max, action, error, i;

	/*
	 * Walk back up the tree splitting/inserting/adjusting as necessary.
	 * If we need to insert and there isn't room, split the node, then
	 * decide which fragment to insert the new block from below into.
	 * Note that we may split the root this way, but we need more fixup.
	 */
	max = state->path.active - 1;
	ASSERT((max >= 0) && (max < XFS_DA_NODE_MAXDEPTH));
	ASSERT(state->path.blk[max].magic == XFS_ATTR_LEAF_MAGIC ||
	       state->path.blk[max].magic == XFS_DIRX_LEAF_MAGIC(state->mp));

	addblk = &state->path.blk[max];		/* initial dummy value */
	for (i = max; (i >= 0) && addblk; state->path.active--, i--) {
		oldblk = &state->path.blk[i];
		newblk = &state->altpath.blk[i];

		/*
		 * If a leaf node then
		 *     Allocate a new leaf node, then rebalance across them.
		 * else if an intermediate node then
		 *     We split on the last layer, must we split the node?
		 */
		switch (oldblk->magic) {
		case XFS_ATTR_LEAF_MAGIC:
#ifndef __KERNEL__
			return(ENOTTY);
#else
			error = xfs_attr_leaf_split(state, oldblk, newblk);
			if ((error != 0) && (error != ENOSPC)) {
				return(error);	/* GROT: attr is inconsistent */
			}
			if (!error) {
				addblk = newblk;
				break;
			}
			/*
			 * Entry wouldn't fit, split the leaf again.
			 */
			state->extravalid = 1;
			if (state->inleaf) {
				state->extraafter = 0;	/* before newblk */
				error = xfs_attr_leaf_split(state, oldblk,
							    &state->extrablk);
			} else {
				state->extraafter = 1;	/* after newblk */
				error = xfs_attr_leaf_split(state, newblk,
							    &state->extrablk);
			}
			if (error)
				return(error);	/* GROT: attr inconsistent */
			addblk = newblk;
			break;
#endif
		case XFS_DIR_LEAF_MAGIC:
			ASSERT(XFS_DIR_IS_V1(state->mp));
			error = xfs_dir_leaf_split(state, oldblk, newblk);
			if ((error != 0) && (error != ENOSPC)) {
				return(error);	/* GROT: dir is inconsistent */
			}
			if (!error) {
				addblk = newblk;
				break;
			}
			/*
			 * Entry wouldn't fit, split the leaf again.
			 */
			state->extravalid = 1;
			if (state->inleaf) {
				state->extraafter = 0;	/* before newblk */
				error = xfs_dir_leaf_split(state, oldblk,
							   &state->extrablk);
				if (error)
					return(error);	/* GROT: dir incon. */
				addblk = newblk;
			} else {
				state->extraafter = 1;	/* after newblk */
				error = xfs_dir_leaf_split(state, newblk,
							   &state->extrablk);
				if (error)
					return(error);	/* GROT: dir incon. */
				addblk = newblk;
			}
			break;
		case XFS_DIR2_LEAFN_MAGIC:
			ASSERT(XFS_DIR_IS_V2(state->mp));
			error = xfs_dir2_leafn_split(state, oldblk, newblk);
			if (error)
				return error;
			addblk = newblk;
			break;
		case XFS_DA_NODE_MAGIC:
			error = xfs_da_node_split(state, oldblk, newblk, addblk,
							 max - i, &action);
			xfs_da_buf_done(addblk->bp);
			addblk->bp = NULL;
			if (error)
				return(error);	/* GROT: dir is inconsistent */
			/*
			 * Record the newly split block for the next time thru?
			 */
			if (action)
				addblk = newblk;
			else
				addblk = NULL;
			break;
		}

		/*
		 * Update the btree to show the new hashval for this child.
		 */
		xfs_da_fixhashpath(state, &state->path);
		/*
		 * If we won't need this block again, it's getting dropped
		 * from the active path by the loop control, so we need
		 * to mark it done now.
		 */
		if (i > 0 || !addblk)
			xfs_da_buf_done(oldblk->bp);
	}
	if (!addblk)
		return(0);

	/*
	 * Split the root node.
	 */
	ASSERT(state->path.active == 0);
	oldblk = &state->path.blk[0];
	error = xfs_da_root_split(state, oldblk, addblk);
	if (error) {
		xfs_da_buf_done(oldblk->bp);
		xfs_da_buf_done(addblk->bp);
		addblk->bp = NULL;
		return(error);	/* GROT: dir is inconsistent */
	}

	/*
	 * Update pointers to the node which used to be block 0 and
	 * just got bumped because of the addition of a new root node.
	 * There might be three blocks involved if a double split occurred,
	 * and the original block 0 could be at any position in the list.
	 */

	node = oldblk->bp->data;
	if (node->hdr.info.forw) {
		if (INT_GET(node->hdr.info.forw, ARCH_CONVERT) == addblk->blkno) {
			bp = addblk->bp;
		} else {
			ASSERT(state->extravalid);
			bp = state->extrablk.bp;
		}
		node = bp->data;
		INT_SET(node->hdr.info.back, ARCH_CONVERT, oldblk->blkno);
		xfs_da_log_buf(state->args->trans, bp,
		    XFS_DA_LOGRANGE(node, &node->hdr.info,
		    sizeof(node->hdr.info)));
	}
	node = oldblk->bp->data;
	if (INT_GET(node->hdr.info.back, ARCH_CONVERT)) {
		if (INT_GET(node->hdr.info.back, ARCH_CONVERT) == addblk->blkno) {
			bp = addblk->bp;
		} else {
			ASSERT(state->extravalid);
			bp = state->extrablk.bp;
		}
		node = bp->data;
		INT_SET(node->hdr.info.forw, ARCH_CONVERT, oldblk->blkno);
		xfs_da_log_buf(state->args->trans, bp,
		    XFS_DA_LOGRANGE(node, &node->hdr.info,
		    sizeof(node->hdr.info)));
	}
	xfs_da_buf_done(oldblk->bp);
	xfs_da_buf_done(addblk->bp);
	addblk->bp = NULL;
	return(0);
}

/*
 * Split the root.  We have to create a new root and point to the two
 * parts (the split old root) that we just created.  Copy block zero to
 * the EOF, extending the inode in process.
 */
STATIC int						/* error */
xfs_da_root_split(xfs_da_state_t *state, xfs_da_state_blk_t *blk1,
				 xfs_da_state_blk_t *blk2)
{
	xfs_da_intnode_t *node, *oldroot;
	xfs_da_args_t *args;
	xfs_dablk_t blkno;
	xfs_dabuf_t *bp;
	int error, size;
	xfs_inode_t *dp;
	xfs_trans_t *tp;
	xfs_mount_t *mp;
	xfs_dir2_leaf_t *leaf;

	/*
	 * Copy the existing (incorrect) block from the root node position
	 * to a free space somewhere.
	 */
	args = state->args;
	ASSERT(args != NULL);
	error = xfs_da_grow_inode(args, &blkno);
	if (error)
		return(error);
	dp = args->dp;
	tp = args->trans;
	mp = state->mp;
	error = xfs_da_get_buf(tp, dp, blkno, -1, &bp, args->whichfork);
	if (error)
		return(error);
	ASSERT(bp != NULL);
	node = bp->data;
	oldroot = blk1->bp->data;
	if (INT_GET(oldroot->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC) {
		size = (int)((char *)&oldroot->btree[INT_GET(oldroot->hdr.count, ARCH_CONVERT)] -
			     (char *)oldroot);
	} else {
		ASSERT(XFS_DIR_IS_V2(mp));
		ASSERT(INT_GET(oldroot->hdr.info.magic, ARCH_CONVERT) == XFS_DIR2_LEAFN_MAGIC);
		leaf = (xfs_dir2_leaf_t *)oldroot;
		size = (int)((char *)&leaf->ents[INT_GET(leaf->hdr.count, ARCH_CONVERT)] -
			     (char *)leaf);
	}
	memcpy(node, oldroot, size);
	xfs_da_log_buf(tp, bp, 0, size - 1);
	xfs_da_buf_done(blk1->bp);
	blk1->bp = bp;
	blk1->blkno = blkno;

	/*
	 * Set up the new root node.
	 */
	error = xfs_da_node_create(args,
		args->whichfork == XFS_DATA_FORK &&
		XFS_DIR_IS_V2(mp) ? mp->m_dirleafblk : 0,
		INT_GET(node->hdr.level, ARCH_CONVERT) + 1, &bp, args->whichfork);
	if (error)
		return(error);
	node = bp->data;
	INT_SET(node->btree[0].hashval, ARCH_CONVERT, blk1->hashval);
	INT_SET(node->btree[0].before, ARCH_CONVERT, blk1->blkno);
	INT_SET(node->btree[1].hashval, ARCH_CONVERT, blk2->hashval);
	INT_SET(node->btree[1].before, ARCH_CONVERT, blk2->blkno);
	INT_SET(node->hdr.count, ARCH_CONVERT, 2);

#ifdef DEBUG
	if (INT_GET(oldroot->hdr.info.magic, ARCH_CONVERT) == XFS_DIR2_LEAFN_MAGIC) {
		ASSERT(blk1->blkno >= mp->m_dirleafblk &&
		       blk1->blkno < mp->m_dirfreeblk);
		ASSERT(blk2->blkno >= mp->m_dirleafblk &&
		       blk2->blkno < mp->m_dirfreeblk);
	}
#endif

	/* Header is already logged by xfs_da_node_create */
	xfs_da_log_buf(tp, bp,
		XFS_DA_LOGRANGE(node, node->btree,
			sizeof(xfs_da_node_entry_t) * 2));
	xfs_da_buf_done(bp);

	return(0);
}

/*
 * Split the node, rebalance, then add the new entry.
 */
STATIC int						/* error */
xfs_da_node_split(xfs_da_state_t *state, xfs_da_state_blk_t *oldblk,
				 xfs_da_state_blk_t *newblk,
				 xfs_da_state_blk_t *addblk,
				 int treelevel, int *result)
{
	xfs_da_intnode_t *node;
	xfs_dablk_t blkno;
	int newcount, error;
	int useextra;

	node = oldblk->bp->data;
	ASSERT(INT_GET(node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);

	/*
	 * With V2 the extra block is data or freespace.
	 */
	useextra = state->extravalid && XFS_DIR_IS_V1(state->mp);
	newcount = 1 + useextra;
	/*
	 * Do we have to split the node?
	 */
	if ((INT_GET(node->hdr.count, ARCH_CONVERT) + newcount) > state->node_ents) {
		/*
		 * Allocate a new node, add to the doubly linked chain of
		 * nodes, then move some of our excess entries into it.
		 */
		error = xfs_da_grow_inode(state->args, &blkno);
		if (error)
			return(error);	/* GROT: dir is inconsistent */

		error = xfs_da_node_create(state->args, blkno, treelevel,
					   &newblk->bp, state->args->whichfork);
		if (error)
			return(error);	/* GROT: dir is inconsistent */
		newblk->blkno = blkno;
		newblk->magic = XFS_DA_NODE_MAGIC;
		xfs_da_node_rebalance(state, oldblk, newblk);
		error = xfs_da_blk_link(state, oldblk, newblk);
		if (error)
			return(error);
		*result = 1;
	} else {
		*result = 0;
	}

	/*
	 * Insert the new entry(s) into the correct block
	 * (updating last hashval in the process).
	 *
	 * xfs_da_node_add() inserts BEFORE the given index,
	 * and as a result of using node_lookup_int() we always
	 * point to a valid entry (not after one), but a split
	 * operation always results in a new block whose hashvals
	 * FOLLOW the current block.
	 *
	 * If we had double-split op below us, then add the extra block too.
	 */
	node = oldblk->bp->data;
	if (oldblk->index <= INT_GET(node->hdr.count, ARCH_CONVERT)) {
		oldblk->index++;
		xfs_da_node_add(state, oldblk, addblk);
		if (useextra) {
			if (state->extraafter)
				oldblk->index++;
			xfs_da_node_add(state, oldblk, &state->extrablk);
			state->extravalid = 0;
		}
	} else {
		newblk->index++;
		xfs_da_node_add(state, newblk, addblk);
		if (useextra) {
			if (state->extraafter)
				newblk->index++;
			xfs_da_node_add(state, newblk, &state->extrablk);
			state->extravalid = 0;
		}
	}

	return(0);
}

/*
 * Balance the btree elements between two intermediate nodes,
 * usually one full and one empty.
 *
 * NOTE: if blk2 is empty, then it will get the upper half of blk1.
 */
STATIC void
xfs_da_node_rebalance(xfs_da_state_t *state, xfs_da_state_blk_t *blk1,
				     xfs_da_state_blk_t *blk2)
{
	xfs_da_intnode_t *node1, *node2, *tmpnode;
	xfs_da_node_entry_t *btree_s, *btree_d;
	int count, tmp;
	xfs_trans_t *tp;

	node1 = blk1->bp->data;
	node2 = blk2->bp->data;
	/*
	 * Figure out how many entries need to move, and in which direction.
	 * Swap the nodes around if that makes it simpler.
	 */
	if ((INT_GET(node1->hdr.count, ARCH_CONVERT) > 0) && (INT_GET(node2->hdr.count, ARCH_CONVERT) > 0) &&
	    ((INT_GET(node2->btree[ 0 ].hashval, ARCH_CONVERT) < INT_GET(node1->btree[ 0 ].hashval, ARCH_CONVERT)) ||
	     (INT_GET(node2->btree[ INT_GET(node2->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT) <
	      INT_GET(node1->btree[ INT_GET(node1->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT)))) {
		tmpnode = node1;
		node1 = node2;
		node2 = tmpnode;
	}
	ASSERT(INT_GET(node1->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	ASSERT(INT_GET(node2->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	count = (INT_GET(node1->hdr.count, ARCH_CONVERT) - INT_GET(node2->hdr.count, ARCH_CONVERT)) / 2;
	if (count == 0)
		return;
	tp = state->args->trans;
	/*
	 * Two cases: high-to-low and low-to-high.
	 */
	if (count > 0) {
		/*
		 * Move elements in node2 up to make a hole.
		 */
		if ((tmp = INT_GET(node2->hdr.count, ARCH_CONVERT)) > 0) {
			tmp *= (uint)sizeof(xfs_da_node_entry_t);
			btree_s = &node2->btree[0];
			btree_d = &node2->btree[count];
			memmove(btree_d, btree_s, tmp);
		}

		/*
		 * Move the req'd B-tree elements from high in node1 to
		 * low in node2.
		 */
		INT_MOD(node2->hdr.count, ARCH_CONVERT, count);
		tmp = count * (uint)sizeof(xfs_da_node_entry_t);
		btree_s = &node1->btree[INT_GET(node1->hdr.count, ARCH_CONVERT) - count];
		btree_d = &node2->btree[0];
		memcpy(btree_d, btree_s, tmp);
		INT_MOD(node1->hdr.count, ARCH_CONVERT, -(count));

	} else {
		/*
		 * Move the req'd B-tree elements from low in node2 to
		 * high in node1.
		 */
		count = -count;
		tmp = count * (uint)sizeof(xfs_da_node_entry_t);
		btree_s = &node2->btree[0];
		btree_d = &node1->btree[INT_GET(node1->hdr.count, ARCH_CONVERT)];
		memcpy(btree_d, btree_s, tmp);
		INT_MOD(node1->hdr.count, ARCH_CONVERT, count);
		xfs_da_log_buf(tp, blk1->bp,
			XFS_DA_LOGRANGE(node1, btree_d, tmp));

		/*
		 * Move elements in node2 down to fill the hole.
		 */
		tmp  = INT_GET(node2->hdr.count, ARCH_CONVERT) - count;
		tmp *= (uint)sizeof(xfs_da_node_entry_t);
		btree_s = &node2->btree[count];
		btree_d = &node2->btree[0];
		memmove(btree_d, btree_s, tmp);
		INT_MOD(node2->hdr.count, ARCH_CONVERT, -(count));
	}

	/*
	 * Log header of node 1 and all current bits of node 2.
	 */
	xfs_da_log_buf(tp, blk1->bp,
		XFS_DA_LOGRANGE(node1, &node1->hdr, sizeof(node1->hdr)));
	xfs_da_log_buf(tp, blk2->bp,
		XFS_DA_LOGRANGE(node2, &node2->hdr,
			sizeof(node2->hdr) +
			sizeof(node2->btree[0]) * INT_GET(node2->hdr.count, ARCH_CONVERT)));

	/*
	 * Record the last hashval from each block for upward propagation.
	 * (note: don't use the swapped node pointers)
	 */
	node1 = blk1->bp->data;
	node2 = blk2->bp->data;
	blk1->hashval = INT_GET(node1->btree[ INT_GET(node1->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);
	blk2->hashval = INT_GET(node2->btree[ INT_GET(node2->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);

	/*
	 * Adjust the expected index for insertion.
	 */
	if (blk1->index >= INT_GET(node1->hdr.count, ARCH_CONVERT)) {
		blk2->index = blk1->index - INT_GET(node1->hdr.count, ARCH_CONVERT);
		blk1->index = INT_GET(node1->hdr.count, ARCH_CONVERT) + 1;	/* make it invalid */
	}
}

/*
 * Add a new entry to an intermediate node.
 */
STATIC void
xfs_da_node_add(xfs_da_state_t *state, xfs_da_state_blk_t *oldblk,
			       xfs_da_state_blk_t *newblk)
{
	xfs_da_intnode_t *node;
	xfs_da_node_entry_t *btree;
	int tmp;
	xfs_mount_t *mp;

	node = oldblk->bp->data;
	mp = state->mp;
	ASSERT(INT_GET(node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	ASSERT((oldblk->index >= 0) && (oldblk->index <= INT_GET(node->hdr.count, ARCH_CONVERT)));
	ASSERT(newblk->blkno != 0);
	if (state->args->whichfork == XFS_DATA_FORK && XFS_DIR_IS_V2(mp))
		ASSERT(newblk->blkno >= mp->m_dirleafblk &&
		       newblk->blkno < mp->m_dirfreeblk);

	/*
	 * We may need to make some room before we insert the new node.
	 */
	tmp = 0;
	btree = &node->btree[ oldblk->index ];
	if (oldblk->index < INT_GET(node->hdr.count, ARCH_CONVERT)) {
		tmp = (INT_GET(node->hdr.count, ARCH_CONVERT) - oldblk->index) * (uint)sizeof(*btree);
		memmove(btree + 1, btree, tmp);
	}
	INT_SET(btree->hashval, ARCH_CONVERT, newblk->hashval);
	INT_SET(btree->before, ARCH_CONVERT, newblk->blkno);
	xfs_da_log_buf(state->args->trans, oldblk->bp,
		XFS_DA_LOGRANGE(node, btree, tmp + sizeof(*btree)));
	INT_MOD(node->hdr.count, ARCH_CONVERT, +1);
	xfs_da_log_buf(state->args->trans, oldblk->bp,
		XFS_DA_LOGRANGE(node, &node->hdr, sizeof(node->hdr)));

	/*
	 * Copy the last hash value from the oldblk to propagate upwards.
	 */
	oldblk->hashval = INT_GET(node->btree[ INT_GET(node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);
}

/*========================================================================
 * Routines used for shrinking the Btree.
 *========================================================================*/

/*
 * Deallocate an empty leaf node, remove it from its parent,
 * possibly deallocating that block, etc...
 */
int
xfs_da_join(xfs_da_state_t *state)
{
	xfs_da_state_blk_t *drop_blk, *save_blk;
	int action, error;

	action = 0;
	drop_blk = &state->path.blk[ state->path.active-1 ];
	save_blk = &state->altpath.blk[ state->path.active-1 ];
	ASSERT(state->path.blk[0].magic == XFS_DA_NODE_MAGIC);
	ASSERT(drop_blk->magic == XFS_ATTR_LEAF_MAGIC ||
	       drop_blk->magic == XFS_DIRX_LEAF_MAGIC(state->mp));

	/*
	 * Walk back up the tree joining/deallocating as necessary.
	 * When we stop dropping blocks, break out.
	 */
	for (  ; state->path.active >= 2; drop_blk--, save_blk--,
		 state->path.active--) {
		/*
		 * See if we can combine the block with a neighbor.
		 *   (action == 0) => no options, just leave
		 *   (action == 1) => coalesce, then unlink
		 *   (action == 2) => block empty, unlink it
		 */
		switch (drop_blk->magic) {
		case XFS_ATTR_LEAF_MAGIC:
#ifndef __KERNEL__
			error = ENOTTY;
#else
			error = xfs_attr_leaf_toosmall(state, &action);
#endif
			if (error)
				return(error);
			if (action == 0)
				return(0);
#ifdef __KERNEL__
			xfs_attr_leaf_unbalance(state, drop_blk, save_blk);
#endif
			break;
		case XFS_DIR_LEAF_MAGIC:
			ASSERT(XFS_DIR_IS_V1(state->mp));
			error = xfs_dir_leaf_toosmall(state, &action);
			if (error)
				return(error);
			if (action == 0)
				return(0);
			xfs_dir_leaf_unbalance(state, drop_blk, save_blk);
			break;
		case XFS_DIR2_LEAFN_MAGIC:
			ASSERT(XFS_DIR_IS_V2(state->mp));
			error = xfs_dir2_leafn_toosmall(state, &action);
			if (error)
				return error;
			if (action == 0)
				return 0;
			xfs_dir2_leafn_unbalance(state, drop_blk, save_blk);
			break;
		case XFS_DA_NODE_MAGIC:
			/*
			 * Remove the offending node, fixup hashvals,
			 * check for a toosmall neighbor.
			 */
			xfs_da_node_remove(state, drop_blk);
			xfs_da_fixhashpath(state, &state->path);
			error = xfs_da_node_toosmall(state, &action);
			if (error)
				return(error);
			if (action == 0)
				return 0;
			xfs_da_node_unbalance(state, drop_blk, save_blk);
			break;
		}
		xfs_da_fixhashpath(state, &state->altpath);
		error = xfs_da_blk_unlink(state, drop_blk, save_blk);
		xfs_da_state_kill_altpath(state);
		if (error)
			return(error);
		error = xfs_da_shrink_inode(state->args, drop_blk->blkno,
							 drop_blk->bp);
		drop_blk->bp = NULL;
		if (error)
			return(error);
	}
	/*
	 * We joined all the way to the top.  If it turns out that
	 * we only have one entry in the root, make the child block
	 * the new root.
	 */
	xfs_da_node_remove(state, drop_blk);
	xfs_da_fixhashpath(state, &state->path);
	error = xfs_da_root_join(state, &state->path.blk[0]);
	return(error);
}

/*
 * We have only one entry in the root.  Copy the only remaining child of
 * the old root to block 0 as the new root node.
 */
STATIC int
xfs_da_root_join(xfs_da_state_t *state, xfs_da_state_blk_t *root_blk)
{
	xfs_da_intnode_t *oldroot;
	/* REFERENCED */
	xfs_da_blkinfo_t *blkinfo;
	xfs_da_args_t *args;
	xfs_dablk_t child;
	xfs_dabuf_t *bp;
	int error;

	args = state->args;
	ASSERT(args != NULL);
	ASSERT(root_blk->magic == XFS_DA_NODE_MAGIC);
	oldroot = root_blk->bp->data;
	ASSERT(INT_GET(oldroot->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	ASSERT(!oldroot->hdr.info.forw);
	ASSERT(!oldroot->hdr.info.back);

	/*
	 * If the root has more than one child, then don't do anything.
	 */
	if (INT_GET(oldroot->hdr.count, ARCH_CONVERT) > 1)
		return(0);

	/*
	 * Read in the (only) child block, then copy those bytes into
	 * the root block's buffer and free the original child block.
	 */
	child = INT_GET(oldroot->btree[ 0 ].before, ARCH_CONVERT);
	ASSERT(child != 0);
	error = xfs_da_read_buf(args->trans, args->dp, child, -1, &bp,
					     args->whichfork);
	if (error)
		return(error);
	ASSERT(bp != NULL);
	blkinfo = bp->data;
	if (INT_GET(oldroot->hdr.level, ARCH_CONVERT) == 1) {
		ASSERT(INT_GET(blkinfo->magic, ARCH_CONVERT) == XFS_DIRX_LEAF_MAGIC(state->mp) ||
		       INT_GET(blkinfo->magic, ARCH_CONVERT) == XFS_ATTR_LEAF_MAGIC);
	} else {
		ASSERT(INT_GET(blkinfo->magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	}
	ASSERT(!blkinfo->forw);
	ASSERT(!blkinfo->back);
	memcpy(root_blk->bp->data, bp->data, state->blocksize);
	xfs_da_log_buf(args->trans, root_blk->bp, 0, state->blocksize - 1);
	error = xfs_da_shrink_inode(args, child, bp);
	return(error);
}

/*
 * Check a node block and its neighbors to see if the block should be
 * collapsed into one or the other neighbor.  Always keep the block
 * with the smaller block number.
 * If the current block is over 50% full, don't try to join it, return 0.
 * If the block is empty, fill in the state structure and return 2.
 * If it can be collapsed, fill in the state structure and return 1.
 * If nothing can be done, return 0.
 */
STATIC int
xfs_da_node_toosmall(xfs_da_state_t *state, int *action)
{
	xfs_da_intnode_t *node;
	xfs_da_state_blk_t *blk;
	xfs_da_blkinfo_t *info;
	int count, forward, error, retval, i;
	xfs_dablk_t blkno;
	xfs_dabuf_t *bp;

	/*
	 * Check for the degenerate case of the block being over 50% full.
	 * If so, it's not worth even looking to see if we might be able
	 * to coalesce with a sibling.
	 */
	blk = &state->path.blk[ state->path.active-1 ];
	info = blk->bp->data;
	ASSERT(INT_GET(info->magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	node = (xfs_da_intnode_t *)info;
	count = INT_GET(node->hdr.count, ARCH_CONVERT);
	if (count > (state->node_ents >> 1)) {
		*action = 0;	/* blk over 50%, don't try to join */
		return(0);	/* blk over 50%, don't try to join */
	}

	/*
	 * Check for the degenerate case of the block being empty.
	 * If the block is empty, we'll simply delete it, no need to
	 * coalesce it with a sibling block.  We choose (aribtrarily)
	 * to merge with the forward block unless it is NULL.
	 */
	if (count == 0) {
		/*
		 * Make altpath point to the block we want to keep and
		 * path point to the block we want to drop (this one).
		 */
		forward = info->forw;
		memcpy(&state->altpath, &state->path, sizeof(state->path));
		error = xfs_da_path_shift(state, &state->altpath, forward,
						 0, &retval);
		if (error)
			return(error);
		if (retval) {
			*action = 0;
		} else {
			*action = 2;
		}
		return(0);
	}

	/*
	 * Examine each sibling block to see if we can coalesce with
	 * at least 25% free space to spare.  We need to figure out
	 * whether to merge with the forward or the backward block.
	 * We prefer coalescing with the lower numbered sibling so as
	 * to shrink a directory over time.
	 */
	/* start with smaller blk num */
	forward = (INT_GET(info->forw, ARCH_CONVERT)
				< INT_GET(info->back, ARCH_CONVERT));
	for (i = 0; i < 2; forward = !forward, i++) {
		if (forward)
			blkno = INT_GET(info->forw, ARCH_CONVERT);
		else
			blkno = INT_GET(info->back, ARCH_CONVERT);
		if (blkno == 0)
			continue;
		error = xfs_da_read_buf(state->args->trans, state->args->dp,
					blkno, -1, &bp, state->args->whichfork);
		if (error)
			return(error);
		ASSERT(bp != NULL);

		node = (xfs_da_intnode_t *)info;
		count  = state->node_ents;
		count -= state->node_ents >> 2;
		count -= INT_GET(node->hdr.count, ARCH_CONVERT);
		node = bp->data;
		ASSERT(INT_GET(node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
		count -= INT_GET(node->hdr.count, ARCH_CONVERT);
		xfs_da_brelse(state->args->trans, bp);
		if (count >= 0)
			break;	/* fits with at least 25% to spare */
	}
	if (i >= 2) {
		*action = 0;
		return(0);
	}

	/*
	 * Make altpath point to the block we want to keep (the lower
	 * numbered block) and path point to the block we want to drop.
	 */
	memcpy(&state->altpath, &state->path, sizeof(state->path));
	if (blkno < blk->blkno) {
		error = xfs_da_path_shift(state, &state->altpath, forward,
						 0, &retval);
		if (error) {
			return(error);
		}
		if (retval) {
			*action = 0;
			return(0);
		}
	} else {
		error = xfs_da_path_shift(state, &state->path, forward,
						 0, &retval);
		if (error) {
			return(error);
		}
		if (retval) {
			*action = 0;
			return(0);
		}
	}
	*action = 1;
	return(0);
}

/*
 * Walk back up the tree adjusting hash values as necessary,
 * when we stop making changes, return.
 */
void
xfs_da_fixhashpath(xfs_da_state_t *state, xfs_da_state_path_t *path)
{
	xfs_da_state_blk_t *blk;
	xfs_da_intnode_t *node;
	xfs_da_node_entry_t *btree;
	xfs_dahash_t lasthash=0;
	int level, count;

	level = path->active-1;
	blk = &path->blk[ level ];
	switch (blk->magic) {
#ifdef __KERNEL__
	case XFS_ATTR_LEAF_MAGIC:
		lasthash = xfs_attr_leaf_lasthash(blk->bp, &count);
		if (count == 0)
			return;
		break;
#endif
	case XFS_DIR_LEAF_MAGIC:
		ASSERT(XFS_DIR_IS_V1(state->mp));
		lasthash = xfs_dir_leaf_lasthash(blk->bp, &count);
		if (count == 0)
			return;
		break;
	case XFS_DIR2_LEAFN_MAGIC:
		ASSERT(XFS_DIR_IS_V2(state->mp));
		lasthash = xfs_dir2_leafn_lasthash(blk->bp, &count);
		if (count == 0)
			return;
		break;
	case XFS_DA_NODE_MAGIC:
		lasthash = xfs_da_node_lasthash(blk->bp, &count);
		if (count == 0)
			return;
		break;
	}
	for (blk--, level--; level >= 0; blk--, level--) {
		node = blk->bp->data;
		ASSERT(INT_GET(node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
		btree = &node->btree[ blk->index ];
		if (INT_GET(btree->hashval, ARCH_CONVERT) == lasthash)
			break;
		blk->hashval = lasthash;
		INT_SET(btree->hashval, ARCH_CONVERT, lasthash);
		xfs_da_log_buf(state->args->trans, blk->bp,
				  XFS_DA_LOGRANGE(node, btree, sizeof(*btree)));

		lasthash = INT_GET(node->btree[ INT_GET(node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);
	}
}

/*
 * Remove an entry from an intermediate node.
 */
STATIC void
xfs_da_node_remove(xfs_da_state_t *state, xfs_da_state_blk_t *drop_blk)
{
	xfs_da_intnode_t *node;
	xfs_da_node_entry_t *btree;
	int tmp;

	node = drop_blk->bp->data;
	ASSERT(drop_blk->index < INT_GET(node->hdr.count, ARCH_CONVERT));
	ASSERT(drop_blk->index >= 0);

	/*
	 * Copy over the offending entry, or just zero it out.
	 */
	btree = &node->btree[drop_blk->index];
	if (drop_blk->index < (INT_GET(node->hdr.count, ARCH_CONVERT)-1)) {
		tmp  = INT_GET(node->hdr.count, ARCH_CONVERT) - drop_blk->index - 1;
		tmp *= (uint)sizeof(xfs_da_node_entry_t);
		memmove(btree, btree + 1, tmp);
		xfs_da_log_buf(state->args->trans, drop_blk->bp,
		    XFS_DA_LOGRANGE(node, btree, tmp));
		btree = &node->btree[ INT_GET(node->hdr.count, ARCH_CONVERT)-1 ];
	}
	memset((char *)btree, 0, sizeof(xfs_da_node_entry_t));
	xfs_da_log_buf(state->args->trans, drop_blk->bp,
	    XFS_DA_LOGRANGE(node, btree, sizeof(*btree)));
	INT_MOD(node->hdr.count, ARCH_CONVERT, -1);
	xfs_da_log_buf(state->args->trans, drop_blk->bp,
	    XFS_DA_LOGRANGE(node, &node->hdr, sizeof(node->hdr)));

	/*
	 * Copy the last hash value from the block to propagate upwards.
	 */
	btree--;
	drop_blk->hashval = INT_GET(btree->hashval, ARCH_CONVERT);
}

/*
 * Unbalance the btree elements between two intermediate nodes,
 * move all Btree elements from one node into another.
 */
STATIC void
xfs_da_node_unbalance(xfs_da_state_t *state, xfs_da_state_blk_t *drop_blk,
				     xfs_da_state_blk_t *save_blk)
{
	xfs_da_intnode_t *drop_node, *save_node;
	xfs_da_node_entry_t *btree;
	int tmp;
	xfs_trans_t *tp;

	drop_node = drop_blk->bp->data;
	save_node = save_blk->bp->data;
	ASSERT(INT_GET(drop_node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	ASSERT(INT_GET(save_node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	tp = state->args->trans;

	/*
	 * If the dying block has lower hashvals, then move all the
	 * elements in the remaining block up to make a hole.
	 */
	if ((INT_GET(drop_node->btree[ 0 ].hashval, ARCH_CONVERT) < INT_GET(save_node->btree[ 0 ].hashval, ARCH_CONVERT)) ||
	    (INT_GET(drop_node->btree[ INT_GET(drop_node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT) <
	     INT_GET(save_node->btree[ INT_GET(save_node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT)))
	{
		btree = &save_node->btree[ INT_GET(drop_node->hdr.count, ARCH_CONVERT) ];
		tmp = INT_GET(save_node->hdr.count, ARCH_CONVERT) * (uint)sizeof(xfs_da_node_entry_t);
		memmove(btree, &save_node->btree[0], tmp);
		btree = &save_node->btree[0];
		xfs_da_log_buf(tp, save_blk->bp,
			XFS_DA_LOGRANGE(save_node, btree,
				(INT_GET(save_node->hdr.count, ARCH_CONVERT) + INT_GET(drop_node->hdr.count, ARCH_CONVERT)) *
				sizeof(xfs_da_node_entry_t)));
	} else {
		btree = &save_node->btree[ INT_GET(save_node->hdr.count, ARCH_CONVERT) ];
		xfs_da_log_buf(tp, save_blk->bp,
			XFS_DA_LOGRANGE(save_node, btree,
				INT_GET(drop_node->hdr.count, ARCH_CONVERT) *
				sizeof(xfs_da_node_entry_t)));
	}

	/*
	 * Move all the B-tree elements from drop_blk to save_blk.
	 */
	tmp = INT_GET(drop_node->hdr.count, ARCH_CONVERT) * (uint)sizeof(xfs_da_node_entry_t);
	memcpy(btree, &drop_node->btree[0], tmp);
	INT_MOD(save_node->hdr.count, ARCH_CONVERT, INT_GET(drop_node->hdr.count, ARCH_CONVERT));

	xfs_da_log_buf(tp, save_blk->bp,
		XFS_DA_LOGRANGE(save_node, &save_node->hdr,
			sizeof(save_node->hdr)));

	/*
	 * Save the last hashval in the remaining block for upward propagation.
	 */
	save_blk->hashval = INT_GET(save_node->btree[ INT_GET(save_node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);
}

/*========================================================================
 * Routines used for finding things in the Btree.
 *========================================================================*/

/*
 * Walk down the Btree looking for a particular filename, filling
 * in the state structure as we go.
 *
 * We will set the state structure to point to each of the elements
 * in each of the nodes where either the hashval is or should be.
 *
 * We support duplicate hashval's so for each entry in the current
 * node that could contain the desired hashval, descend.  This is a
 * pruned depth-first tree search.
 */
int							/* error */
xfs_da_node_lookup_int(xfs_da_state_t *state, int *result)
{
	xfs_da_state_blk_t *blk;
	xfs_da_blkinfo_t *curr;
	xfs_da_intnode_t *node;
	xfs_da_node_entry_t *btree;
	xfs_dablk_t blkno;
	int probe, span, max, error, retval;
	xfs_dahash_t hashval;
	xfs_da_args_t *args;

	args = state->args;

	/*
	 * Descend thru the B-tree searching each level for the right
	 * node to use, until the right hashval is found.
	 */
	if (args->whichfork == XFS_DATA_FORK && XFS_DIR_IS_V2(state->mp))
		blkno = state->mp->m_dirleafblk;
	else
		blkno = 0;
	for (blk = &state->path.blk[0], state->path.active = 1;
			 state->path.active <= XFS_DA_NODE_MAXDEPTH;
			 blk++, state->path.active++) {
		/*
		 * Read the next node down in the tree.
		 */
		blk->blkno = blkno;
		error = xfs_da_read_buf(args->trans, args->dp, blkno,
					-1, &blk->bp, args->whichfork);
		if (error) {
			blk->blkno = 0;
			state->path.active--;
			return(error);
		}
		curr = blk->bp->data;
		ASSERT(INT_GET(curr->magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC ||
		       INT_GET(curr->magic, ARCH_CONVERT) == XFS_DIRX_LEAF_MAGIC(state->mp) ||
		       INT_GET(curr->magic, ARCH_CONVERT) == XFS_ATTR_LEAF_MAGIC);

		/*
		 * Search an intermediate node for a match.
		 */
		blk->magic = INT_GET(curr->magic, ARCH_CONVERT);
		if (INT_GET(curr->magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC) {
			node = blk->bp->data;
			blk->hashval = INT_GET(node->btree[ INT_GET(node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);

			/*
			 * Binary search.  (note: small blocks will skip loop)
			 */
			max = INT_GET(node->hdr.count, ARCH_CONVERT);
			probe = span = max / 2;
			hashval = args->hashval;
			for (btree = &node->btree[probe]; span > 4;
				   btree = &node->btree[probe]) {
				span /= 2;
				if (INT_GET(btree->hashval, ARCH_CONVERT) < hashval)
					probe += span;
				else if (INT_GET(btree->hashval, ARCH_CONVERT) > hashval)
					probe -= span;
				else
					break;
			}
			ASSERT((probe >= 0) && (probe < max));
			ASSERT((span <= 4) || (INT_GET(btree->hashval, ARCH_CONVERT) == hashval));

			/*
			 * Since we may have duplicate hashval's, find the first
			 * matching hashval in the node.
			 */
			while ((probe > 0) && (INT_GET(btree->hashval, ARCH_CONVERT) >= hashval)) {
				btree--;
				probe--;
			}
			while ((probe < max) && (INT_GET(btree->hashval, ARCH_CONVERT) < hashval)) {
				btree++;
				probe++;
			}

			/*
			 * Pick the right block to descend on.
			 */
			if (probe == max) {
				blk->index = max-1;
				blkno = INT_GET(node->btree[ max-1 ].before, ARCH_CONVERT);
			} else {
				blk->index = probe;
				blkno = INT_GET(btree->before, ARCH_CONVERT);
			}
		}
#ifdef __KERNEL__
		else if (INT_GET(curr->magic, ARCH_CONVERT) == XFS_ATTR_LEAF_MAGIC) {
			blk->hashval = xfs_attr_leaf_lasthash(blk->bp, NULL);
			break;
		}
#endif
		else if (INT_GET(curr->magic, ARCH_CONVERT) == XFS_DIR_LEAF_MAGIC) {
			blk->hashval = xfs_dir_leaf_lasthash(blk->bp, NULL);
			break;
		}
		else if (INT_GET(curr->magic, ARCH_CONVERT) == XFS_DIR2_LEAFN_MAGIC) {
			blk->hashval = xfs_dir2_leafn_lasthash(blk->bp, NULL);
			break;
		}
	}

	/*
	 * A leaf block that ends in the hashval that we are interested in
	 * (final hashval == search hashval) means that the next block may
	 * contain more entries with the same hashval, shift upward to the
	 * next leaf and keep searching.
	 */
	for (;;) {
		if (blk->magic == XFS_DIR_LEAF_MAGIC) {
			ASSERT(XFS_DIR_IS_V1(state->mp));
			retval = xfs_dir_leaf_lookup_int(blk->bp, args,
								  &blk->index);
		} else if (blk->magic == XFS_DIR2_LEAFN_MAGIC) {
			ASSERT(XFS_DIR_IS_V2(state->mp));
			retval = xfs_dir2_leafn_lookup_int(blk->bp, args,
							&blk->index, state);
		}
#ifdef __KERNEL__
		else if (blk->magic == XFS_ATTR_LEAF_MAGIC) {
			retval = xfs_attr_leaf_lookup_int(blk->bp, args);
			blk->index = args->index;
			args->blkno = blk->blkno;
		}
#endif
		if (((retval == ENOENT) || (retval == ENOATTR)) &&
		    (blk->hashval == args->hashval)) {
			error = xfs_da_path_shift(state, &state->path, 1, 1,
							 &retval);
			if (error)
				return(error);
			if (retval == 0) {
				continue;
			}
#ifdef __KERNEL__
			else if (blk->magic == XFS_ATTR_LEAF_MAGIC) {
				/* path_shift() gives ENOENT */
				retval = XFS_ERROR(ENOATTR);
			}
#endif
		}
		break;
	}
	*result = retval;
	return(0);
}

/*========================================================================
 * Utility routines.
 *========================================================================*/

/*
 * Link a new block into a doubly linked list of blocks (of whatever type).
 */
int							/* error */
xfs_da_blk_link(xfs_da_state_t *state, xfs_da_state_blk_t *old_blk,
			       xfs_da_state_blk_t *new_blk)
{
	xfs_da_blkinfo_t *old_info, *new_info, *tmp_info;
	xfs_da_args_t *args;
	int before=0, error;
	xfs_dabuf_t *bp;

	/*
	 * Set up environment.
	 */
	args = state->args;
	ASSERT(args != NULL);
	old_info = old_blk->bp->data;
	new_info = new_blk->bp->data;
	ASSERT(old_blk->magic == XFS_DA_NODE_MAGIC ||
	       old_blk->magic == XFS_DIRX_LEAF_MAGIC(state->mp) ||
	       old_blk->magic == XFS_ATTR_LEAF_MAGIC);
	ASSERT(old_blk->magic == INT_GET(old_info->magic, ARCH_CONVERT));
	ASSERT(new_blk->magic == INT_GET(new_info->magic, ARCH_CONVERT));
	ASSERT(old_blk->magic == new_blk->magic);

	switch (old_blk->magic) {
#ifdef __KERNEL__
	case XFS_ATTR_LEAF_MAGIC:
		before = xfs_attr_leaf_order(old_blk->bp, new_blk->bp);
		break;
#endif
	case XFS_DIR_LEAF_MAGIC:
		ASSERT(XFS_DIR_IS_V1(state->mp));
		before = xfs_dir_leaf_order(old_blk->bp, new_blk->bp);
		break;
	case XFS_DIR2_LEAFN_MAGIC:
		ASSERT(XFS_DIR_IS_V2(state->mp));
		before = xfs_dir2_leafn_order(old_blk->bp, new_blk->bp);
		break;
	case XFS_DA_NODE_MAGIC:
		before = xfs_da_node_order(old_blk->bp, new_blk->bp);
		break;
	}

	/*
	 * Link blocks in appropriate order.
	 */
	if (before) {
		/*
		 * Link new block in before existing block.
		 */
		INT_SET(new_info->forw, ARCH_CONVERT, old_blk->blkno);
		new_info->back = old_info->back; /* INT_: direct copy */
		if (INT_GET(old_info->back, ARCH_CONVERT)) {
			error = xfs_da_read_buf(args->trans, args->dp,
						INT_GET(old_info->back,
							ARCH_CONVERT), -1, &bp,
						args->whichfork);
			if (error)
				return(error);
			ASSERT(bp != NULL);
			tmp_info = bp->data;
			ASSERT(INT_GET(tmp_info->magic, ARCH_CONVERT) == INT_GET(old_info->magic, ARCH_CONVERT));
			ASSERT(INT_GET(tmp_info->forw, ARCH_CONVERT) == old_blk->blkno);
			INT_SET(tmp_info->forw, ARCH_CONVERT, new_blk->blkno);
			xfs_da_log_buf(args->trans, bp, 0, sizeof(*tmp_info)-1);
			xfs_da_buf_done(bp);
		}
		INT_SET(old_info->back, ARCH_CONVERT, new_blk->blkno);
	} else {
		/*
		 * Link new block in after existing block.
		 */
		new_info->forw = old_info->forw; /* INT_: direct copy */
		INT_SET(new_info->back, ARCH_CONVERT, old_blk->blkno);
		if (INT_GET(old_info->forw, ARCH_CONVERT)) {
			error = xfs_da_read_buf(args->trans, args->dp,
						INT_GET(old_info->forw, ARCH_CONVERT), -1, &bp,
						args->whichfork);
			if (error)
				return(error);
			ASSERT(bp != NULL);
			tmp_info = bp->data;
			ASSERT(INT_GET(tmp_info->magic, ARCH_CONVERT)
				    == INT_GET(old_info->magic, ARCH_CONVERT));
			ASSERT(INT_GET(tmp_info->back, ARCH_CONVERT)
				    == old_blk->blkno);
			INT_SET(tmp_info->back, ARCH_CONVERT, new_blk->blkno);
			xfs_da_log_buf(args->trans, bp, 0, sizeof(*tmp_info)-1);
			xfs_da_buf_done(bp);
		}
		INT_SET(old_info->forw, ARCH_CONVERT, new_blk->blkno);
	}

	xfs_da_log_buf(args->trans, old_blk->bp, 0, sizeof(*tmp_info) - 1);
	xfs_da_log_buf(args->trans, new_blk->bp, 0, sizeof(*tmp_info) - 1);
	return(0);
}

/*
 * Compare two intermediate nodes for "order".
 */
STATIC int
xfs_da_node_order(xfs_dabuf_t *node1_bp, xfs_dabuf_t *node2_bp)
{
	xfs_da_intnode_t *node1, *node2;

	node1 = node1_bp->data;
	node2 = node2_bp->data;
	ASSERT((INT_GET(node1->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC) &&
	       (INT_GET(node2->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC));
	if ((INT_GET(node1->hdr.count, ARCH_CONVERT) > 0) && (INT_GET(node2->hdr.count, ARCH_CONVERT) > 0) &&
	    ((INT_GET(node2->btree[ 0 ].hashval, ARCH_CONVERT) <
	      INT_GET(node1->btree[ 0 ].hashval, ARCH_CONVERT)) ||
	     (INT_GET(node2->btree[ INT_GET(node2->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT) <
	      INT_GET(node1->btree[ INT_GET(node1->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT)))) {
		return(1);
	}
	return(0);
}

/*
 * Pick up the last hashvalue from an intermediate node.
 */
STATIC uint
xfs_da_node_lasthash(xfs_dabuf_t *bp, int *count)
{
	xfs_da_intnode_t *node;

	node = bp->data;
	ASSERT(INT_GET(node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
	if (count)
		*count = INT_GET(node->hdr.count, ARCH_CONVERT);
	if (!node->hdr.count)
		return(0);
	return(INT_GET(node->btree[ INT_GET(node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT));
}

/*
 * Unlink a block from a doubly linked list of blocks.
 */
int							/* error */
xfs_da_blk_unlink(xfs_da_state_t *state, xfs_da_state_blk_t *drop_blk,
				 xfs_da_state_blk_t *save_blk)
{
	xfs_da_blkinfo_t *drop_info, *save_info, *tmp_info;
	xfs_da_args_t *args;
	xfs_dabuf_t *bp;
	int error;

	/*
	 * Set up environment.
	 */
	args = state->args;
	ASSERT(args != NULL);
	save_info = save_blk->bp->data;
	drop_info = drop_blk->bp->data;
	ASSERT(save_blk->magic == XFS_DA_NODE_MAGIC ||
	       save_blk->magic == XFS_DIRX_LEAF_MAGIC(state->mp) ||
	       save_blk->magic == XFS_ATTR_LEAF_MAGIC);
	ASSERT(save_blk->magic == INT_GET(save_info->magic, ARCH_CONVERT));
	ASSERT(drop_blk->magic == INT_GET(drop_info->magic, ARCH_CONVERT));
	ASSERT(save_blk->magic == drop_blk->magic);
	ASSERT((INT_GET(save_info->forw, ARCH_CONVERT) == drop_blk->blkno) ||
	       (INT_GET(save_info->back, ARCH_CONVERT) == drop_blk->blkno));
	ASSERT((INT_GET(drop_info->forw, ARCH_CONVERT) == save_blk->blkno) ||
	       (INT_GET(drop_info->back, ARCH_CONVERT) == save_blk->blkno));

	/*
	 * Unlink the leaf block from the doubly linked chain of leaves.
	 */
	if (INT_GET(save_info->back, ARCH_CONVERT) == drop_blk->blkno) {
		save_info->back = drop_info->back; /* INT_: direct copy */
		if (INT_GET(drop_info->back, ARCH_CONVERT)) {
			error = xfs_da_read_buf(args->trans, args->dp,
						INT_GET(drop_info->back,
							ARCH_CONVERT), -1, &bp,
						args->whichfork);
			if (error)
				return(error);
			ASSERT(bp != NULL);
			tmp_info = bp->data;
			ASSERT(INT_GET(tmp_info->magic, ARCH_CONVERT) == INT_GET(save_info->magic, ARCH_CONVERT));
			ASSERT(INT_GET(tmp_info->forw, ARCH_CONVERT) == drop_blk->blkno);
			INT_SET(tmp_info->forw, ARCH_CONVERT, save_blk->blkno);
			xfs_da_log_buf(args->trans, bp, 0,
						    sizeof(*tmp_info) - 1);
			xfs_da_buf_done(bp);
		}
	} else {
		save_info->forw = drop_info->forw; /* INT_: direct copy */
		if (INT_GET(drop_info->forw, ARCH_CONVERT)) {
			error = xfs_da_read_buf(args->trans, args->dp,
						INT_GET(drop_info->forw, ARCH_CONVERT), -1, &bp,
						args->whichfork);
			if (error)
				return(error);
			ASSERT(bp != NULL);
			tmp_info = bp->data;
			ASSERT(INT_GET(tmp_info->magic, ARCH_CONVERT)
				    == INT_GET(save_info->magic, ARCH_CONVERT));
			ASSERT(INT_GET(tmp_info->back, ARCH_CONVERT)
				    == drop_blk->blkno);
			INT_SET(tmp_info->back, ARCH_CONVERT, save_blk->blkno);
			xfs_da_log_buf(args->trans, bp, 0,
						    sizeof(*tmp_info) - 1);
			xfs_da_buf_done(bp);
		}
	}

	xfs_da_log_buf(args->trans, save_blk->bp, 0, sizeof(*save_info) - 1);
	return(0);
}

/*
 * Move a path "forward" or "!forward" one block at the current level.
 *
 * This routine will adjust a "path" to point to the next block
 * "forward" (higher hashvalues) or "!forward" (lower hashvals) in the
 * Btree, including updating pointers to the intermediate nodes between
 * the new bottom and the root.
 */
int							/* error */
xfs_da_path_shift(xfs_da_state_t *state, xfs_da_state_path_t *path,
				 int forward, int release, int *result)
{
	xfs_da_state_blk_t *blk;
	xfs_da_blkinfo_t *info;
	xfs_da_intnode_t *node;
	xfs_da_args_t *args;
	xfs_dablk_t blkno=0;
	int level, error;

	/*
	 * Roll up the Btree looking for the first block where our
	 * current index is not at the edge of the block.  Note that
	 * we skip the bottom layer because we want the sibling block.
	 */
	args = state->args;
	ASSERT(args != NULL);
	ASSERT(path != NULL);
	ASSERT((path->active > 0) && (path->active < XFS_DA_NODE_MAXDEPTH));
	level = (path->active-1) - 1;	/* skip bottom layer in path */
	for (blk = &path->blk[level]; level >= 0; blk--, level--) {
		ASSERT(blk->bp != NULL);
		node = blk->bp->data;
		ASSERT(INT_GET(node->hdr.info.magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC);
		if (forward && (blk->index < INT_GET(node->hdr.count, ARCH_CONVERT)-1)) {
			blk->index++;
			blkno = INT_GET(node->btree[ blk->index ].before, ARCH_CONVERT);
			break;
		} else if (!forward && (blk->index > 0)) {
			blk->index--;
			blkno = INT_GET(node->btree[ blk->index ].before, ARCH_CONVERT);
			break;
		}
	}
	if (level < 0) {
		*result = XFS_ERROR(ENOENT);	/* we're out of our tree */
		ASSERT(args->oknoent);
		return(0);
	}

	/*
	 * Roll down the edge of the subtree until we reach the
	 * same depth we were at originally.
	 */
	for (blk++, level++; level < path->active; blk++, level++) {
		/*
		 * Release the old block.
		 * (if it's dirty, trans won't actually let go)
		 */
		if (release)
			xfs_da_brelse(args->trans, blk->bp);

		/*
		 * Read the next child block.
		 */
		blk->blkno = blkno;
		error = xfs_da_read_buf(args->trans, args->dp, blkno, -1,
						     &blk->bp, args->whichfork);
		if (error)
			return(error);
		ASSERT(blk->bp != NULL);
		info = blk->bp->data;
		ASSERT(INT_GET(info->magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC ||
		       INT_GET(info->magic, ARCH_CONVERT) == XFS_DIRX_LEAF_MAGIC(state->mp) ||
		       INT_GET(info->magic, ARCH_CONVERT) == XFS_ATTR_LEAF_MAGIC);
		blk->magic = INT_GET(info->magic, ARCH_CONVERT);
		if (INT_GET(info->magic, ARCH_CONVERT) == XFS_DA_NODE_MAGIC) {
			node = (xfs_da_intnode_t *)info;
			blk->hashval = INT_GET(node->btree[ INT_GET(node->hdr.count, ARCH_CONVERT)-1 ].hashval, ARCH_CONVERT);
			if (forward)
				blk->index = 0;
			else
				blk->index = INT_GET(node->hdr.count, ARCH_CONVERT)-1;
			blkno = INT_GET(node->btree[ blk->index ].before, ARCH_CONVERT);
		} else {
			ASSERT(level == path->active-1);
			blk->index = 0;
			switch(blk->magic) {
#ifdef __KERNEL__
			case XFS_ATTR_LEAF_MAGIC:
				blk->hashval = xfs_attr_leaf_lasthash(blk->bp,
								      NULL);
				break;
#endif
			case XFS_DIR_LEAF_MAGIC:
				ASSERT(XFS_DIR_IS_V1(state->mp));
				blk->hashval = xfs_dir_leaf_lasthash(blk->bp,
								     NULL);
				break;
			case XFS_DIR2_LEAFN_MAGIC:
				ASSERT(XFS_DIR_IS_V2(state->mp));
				blk->hashval = xfs_dir2_leafn_lasthash(blk->bp,
								       NULL);
				break;
			default:
				ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC ||
				       blk->magic ==
				       XFS_DIRX_LEAF_MAGIC(state->mp));
				break;
			}
		}
	}
	*result = 0;
	return(0);
}


/*========================================================================
 * Utility routines.
 *========================================================================*/

/*
 * Implement a simple hash on a character string.
 * Rotate the hash value by 7 bits, then XOR each character in.
 * This is implemented with some source-level loop unrolling.
 */
xfs_dahash_t
xfs_da_hashname(uchar_t *name, int namelen)
{
	xfs_dahash_t hash;

#ifdef SLOWVERSION
	/*
	 * This is the old one-byte-at-a-time version.
	 */
	for (hash = 0; namelen > 0; namelen--)
		hash = *name++ ^ rol32(hash, 7);

	return(hash);
#else
	/*
	 * Do four characters at a time as long as we can.
	 */
	for (hash = 0; namelen >= 4; namelen -= 4,…