/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * alloc.c
   *
   * Extent allocs and frees
   *
   * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/fs.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>

  #include <linux/swap.h>

  #include <linux/quotaops.h>

  #include <linux/blkdev.h>

  #include <cluster/masklog.h>
  
  #include "ocfs2.h"
  
  #include "alloc.h"

  #include "aops.h"

  #include "blockcheck.h"

  #include "dlmglue.h"
  #include "extent_map.h"
  #include "inode.h"
  #include "journal.h"
  #include "localalloc.h"
  #include "suballoc.h"
  #include "sysfile.h"
  #include "file.h"
  #include "super.h"
  #include "uptodate.h"

  #include "xattr.h"

  #include "refcounttree.h"

  #include "ocfs2_trace.h"

  
  #include "buffer_head_io.h"

  enum ocfs2_contig_type {
  	CONTIG_NONE = 0,
  	CONTIG_LEFT,
  	CONTIG_RIGHT,
  	CONTIG_LEFTRIGHT,
  };

  static enum ocfs2_contig_type
  	ocfs2_extent_rec_contig(struct super_block *sb,
  				struct ocfs2_extent_rec *ext,
  				struct ocfs2_extent_rec *insert_rec);

  /*
   * Operations for a specific extent tree type.
   *
   * To implement an on-disk btree (extent tree) type in ocfs2, add
   * an ocfs2_extent_tree_operations structure and the matching

   * ocfs2_init_<thingy>_extent_tree() function.  That's pretty much it

   * for the allocation portion of the extent tree.
   */

  struct ocfs2_extent_tree_operations {

  	/*
  	 * last_eb_blk is the block number of the right most leaf extent
  	 * block.  Most on-disk structures containing an extent tree store
  	 * this value for fast access.  The ->eo_set_last_eb_blk() and
  	 * ->eo_get_last_eb_blk() operations access this value.  They are
  	 *  both required.
  	 */

  	void (*eo_set_last_eb_blk)(struct ocfs2_extent_tree *et,
  				   u64 blkno);
  	u64 (*eo_get_last_eb_blk)(struct ocfs2_extent_tree *et);

  
  	/*
  	 * The on-disk structure usually keeps track of how many total
  	 * clusters are stored in this extent tree.  This function updates
  	 * that value.  new_clusters is the delta, and must be
  	 * added to the total.  Required.
  	 */

  	void (*eo_update_clusters)(struct ocfs2_extent_tree *et,

  				   u32 new_clusters);

  
  	/*

  	 * If this extent tree is supported by an extent map, insert
  	 * a record into the map.
  	 */
  	void (*eo_extent_map_insert)(struct ocfs2_extent_tree *et,
  				     struct ocfs2_extent_rec *rec);
  
  	/*

  	 * If this extent tree is supported by an extent map, truncate the
  	 * map to clusters,
  	 */
  	void (*eo_extent_map_truncate)(struct ocfs2_extent_tree *et,
  				       u32 clusters);
  
  	/*

  	 * If ->eo_insert_check() exists, it is called before rec is
  	 * inserted into the extent tree.  It is optional.
  	 */

  	int (*eo_insert_check)(struct ocfs2_extent_tree *et,

  			       struct ocfs2_extent_rec *rec);

  	int (*eo_sanity_check)(struct ocfs2_extent_tree *et);

  	/*
  	 * --------------------------------------------------------------
  	 * The remaining are internal to ocfs2_extent_tree and don't have
  	 * accessor functions
  	 */
  
  	/*
  	 * ->eo_fill_root_el() takes et->et_object and sets et->et_root_el.
  	 * It is required.
  	 */

  	void (*eo_fill_root_el)(struct ocfs2_extent_tree *et);

  
  	/*
  	 * ->eo_fill_max_leaf_clusters sets et->et_max_leaf_clusters if
  	 * it exists.  If it does not, et->et_max_leaf_clusters is set
  	 * to 0 (unlimited).  Optional.
  	 */

  	void (*eo_fill_max_leaf_clusters)(struct ocfs2_extent_tree *et);

  
  	/*
  	 * ->eo_extent_contig test whether the 2 ocfs2_extent_rec
  	 * are contiguous or not. Optional. Don't need to set it if use
  	 * ocfs2_extent_rec as the tree leaf.
  	 */
  	enum ocfs2_contig_type
  		(*eo_extent_contig)(struct ocfs2_extent_tree *et,
  				    struct ocfs2_extent_rec *ext,
  				    struct ocfs2_extent_rec *insert_rec);

  };

  /*
   * Pre-declare ocfs2_dinode_et_ops so we can use it as a sanity check
   * in the methods.
   */
  static u64 ocfs2_dinode_get_last_eb_blk(struct ocfs2_extent_tree *et);
  static void ocfs2_dinode_set_last_eb_blk(struct ocfs2_extent_tree *et,
  					 u64 blkno);

  static void ocfs2_dinode_update_clusters(struct ocfs2_extent_tree *et,

  					 u32 clusters);

  static void ocfs2_dinode_extent_map_insert(struct ocfs2_extent_tree *et,
  					   struct ocfs2_extent_rec *rec);

  static void ocfs2_dinode_extent_map_truncate(struct ocfs2_extent_tree *et,
  					     u32 clusters);

  static int ocfs2_dinode_insert_check(struct ocfs2_extent_tree *et,

  				     struct ocfs2_extent_rec *rec);

  static int ocfs2_dinode_sanity_check(struct ocfs2_extent_tree *et);

  static void ocfs2_dinode_fill_root_el(struct ocfs2_extent_tree *et);
  static struct ocfs2_extent_tree_operations ocfs2_dinode_et_ops = {
  	.eo_set_last_eb_blk	= ocfs2_dinode_set_last_eb_blk,
  	.eo_get_last_eb_blk	= ocfs2_dinode_get_last_eb_blk,
  	.eo_update_clusters	= ocfs2_dinode_update_clusters,

  	.eo_extent_map_insert	= ocfs2_dinode_extent_map_insert,

  	.eo_extent_map_truncate	= ocfs2_dinode_extent_map_truncate,

  	.eo_insert_check	= ocfs2_dinode_insert_check,
  	.eo_sanity_check	= ocfs2_dinode_sanity_check,
  	.eo_fill_root_el	= ocfs2_dinode_fill_root_el,
  };

  static void ocfs2_dinode_set_last_eb_blk(struct ocfs2_extent_tree *et,
  					 u64 blkno)
  {

  	struct ocfs2_dinode *di = et->et_object;

  	BUG_ON(et->et_ops != &ocfs2_dinode_et_ops);

  	di->i_last_eb_blk = cpu_to_le64(blkno);
  }
  
  static u64 ocfs2_dinode_get_last_eb_blk(struct ocfs2_extent_tree *et)
  {

  	struct ocfs2_dinode *di = et->et_object;

  	BUG_ON(et->et_ops != &ocfs2_dinode_et_ops);

  	return le64_to_cpu(di->i_last_eb_blk);
  }

  static void ocfs2_dinode_update_clusters(struct ocfs2_extent_tree *et,

  					 u32 clusters)
  {

  	struct ocfs2_inode_info *oi = cache_info_to_inode(et->et_ci);

  	struct ocfs2_dinode *di = et->et_object;

  
  	le32_add_cpu(&di->i_clusters, clusters);

  	spin_lock(&oi->ip_lock);
  	oi->ip_clusters = le32_to_cpu(di->i_clusters);
  	spin_unlock(&oi->ip_lock);

  }

  static void ocfs2_dinode_extent_map_insert(struct ocfs2_extent_tree *et,
  					   struct ocfs2_extent_rec *rec)
  {
  	struct inode *inode = &cache_info_to_inode(et->et_ci)->vfs_inode;
  
  	ocfs2_extent_map_insert_rec(inode, rec);
  }

  static void ocfs2_dinode_extent_map_truncate(struct ocfs2_extent_tree *et,
  					     u32 clusters)
  {
  	struct inode *inode = &cache_info_to_inode(et->et_ci)->vfs_inode;
  
  	ocfs2_extent_map_trunc(inode, clusters);
  }

  static int ocfs2_dinode_insert_check(struct ocfs2_extent_tree *et,

  				     struct ocfs2_extent_rec *rec)
  {

  	struct ocfs2_inode_info *oi = cache_info_to_inode(et->et_ci);
  	struct ocfs2_super *osb = OCFS2_SB(oi->vfs_inode.i_sb);

  	BUG_ON(oi->ip_dyn_features & OCFS2_INLINE_DATA_FL);

  	mlog_bug_on_msg(!ocfs2_sparse_alloc(osb) &&

  			(oi->ip_clusters != le32_to_cpu(rec->e_cpos)),

  			"Device %s, asking for sparse allocation: inode %llu, "
  			"cpos %u, clusters %u
  ",
  			osb->dev_str,

  			(unsigned long long)oi->ip_blkno,
  			rec->e_cpos, oi->ip_clusters);

  
  	return 0;
  }

  static int ocfs2_dinode_sanity_check(struct ocfs2_extent_tree *et)

  {

  	struct ocfs2_dinode *di = et->et_object;

  	BUG_ON(et->et_ops != &ocfs2_dinode_et_ops);

  	BUG_ON(!OCFS2_IS_VALID_DINODE(di));

  	return 0;

  }

  static void ocfs2_dinode_fill_root_el(struct ocfs2_extent_tree *et)
  {
  	struct ocfs2_dinode *di = et->et_object;
  
  	et->et_root_el = &di->id2.i_list;
  }

  static void ocfs2_xattr_value_fill_root_el(struct ocfs2_extent_tree *et)
  {

  	struct ocfs2_xattr_value_buf *vb = et->et_object;

  	et->et_root_el = &vb->vb_xv->xr_list;

  }

  static void ocfs2_xattr_value_set_last_eb_blk(struct ocfs2_extent_tree *et,
  					      u64 blkno)
  {

  	struct ocfs2_xattr_value_buf *vb = et->et_object;

  	vb->vb_xv->xr_last_eb_blk = cpu_to_le64(blkno);

  }
  
  static u64 ocfs2_xattr_value_get_last_eb_blk(struct ocfs2_extent_tree *et)
  {

  	struct ocfs2_xattr_value_buf *vb = et->et_object;

  	return le64_to_cpu(vb->vb_xv->xr_last_eb_blk);

  }

  static void ocfs2_xattr_value_update_clusters(struct ocfs2_extent_tree *et,

  					      u32 clusters)
  {

  	struct ocfs2_xattr_value_buf *vb = et->et_object;

  	le32_add_cpu(&vb->vb_xv->xr_clusters, clusters);

  }

  static struct ocfs2_extent_tree_operations ocfs2_xattr_value_et_ops = {

  	.eo_set_last_eb_blk	= ocfs2_xattr_value_set_last_eb_blk,
  	.eo_get_last_eb_blk	= ocfs2_xattr_value_get_last_eb_blk,
  	.eo_update_clusters	= ocfs2_xattr_value_update_clusters,

  	.eo_fill_root_el	= ocfs2_xattr_value_fill_root_el,

  };

  static void ocfs2_xattr_tree_fill_root_el(struct ocfs2_extent_tree *et)
  {
  	struct ocfs2_xattr_block *xb = et->et_object;
  
  	et->et_root_el = &xb->xb_attrs.xb_root.xt_list;
  }

  static void ocfs2_xattr_tree_fill_max_leaf_clusters(struct ocfs2_extent_tree *et)

  {

  	struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);

  	et->et_max_leaf_clusters =

  		ocfs2_clusters_for_bytes(sb, OCFS2_MAX_XATTR_TREE_LEAF_SIZE);

  }

  static void ocfs2_xattr_tree_set_last_eb_blk(struct ocfs2_extent_tree *et,
  					     u64 blkno)
  {

  	struct ocfs2_xattr_block *xb = et->et_object;

  	struct ocfs2_xattr_tree_root *xt = &xb->xb_attrs.xb_root;
  
  	xt->xt_last_eb_blk = cpu_to_le64(blkno);
  }
  
  static u64 ocfs2_xattr_tree_get_last_eb_blk(struct ocfs2_extent_tree *et)
  {

  	struct ocfs2_xattr_block *xb = et->et_object;

  	struct ocfs2_xattr_tree_root *xt = &xb->xb_attrs.xb_root;
  
  	return le64_to_cpu(xt->xt_last_eb_blk);
  }

  static void ocfs2_xattr_tree_update_clusters(struct ocfs2_extent_tree *et,

  					     u32 clusters)
  {

  	struct ocfs2_xattr_block *xb = et->et_object;

  
  	le32_add_cpu(&xb->xb_attrs.xb_root.xt_clusters, clusters);
  }

  static struct ocfs2_extent_tree_operations ocfs2_xattr_tree_et_ops = {

  	.eo_set_last_eb_blk	= ocfs2_xattr_tree_set_last_eb_blk,
  	.eo_get_last_eb_blk	= ocfs2_xattr_tree_get_last_eb_blk,
  	.eo_update_clusters	= ocfs2_xattr_tree_update_clusters,

  	.eo_fill_root_el	= ocfs2_xattr_tree_fill_root_el,

  	.eo_fill_max_leaf_clusters = ocfs2_xattr_tree_fill_max_leaf_clusters,

  };

  static void ocfs2_dx_root_set_last_eb_blk(struct ocfs2_extent_tree *et,
  					  u64 blkno)
  {
  	struct ocfs2_dx_root_block *dx_root = et->et_object;
  
  	dx_root->dr_last_eb_blk = cpu_to_le64(blkno);
  }
  
  static u64 ocfs2_dx_root_get_last_eb_blk(struct ocfs2_extent_tree *et)
  {
  	struct ocfs2_dx_root_block *dx_root = et->et_object;
  
  	return le64_to_cpu(dx_root->dr_last_eb_blk);
  }

  static void ocfs2_dx_root_update_clusters(struct ocfs2_extent_tree *et,

  					  u32 clusters)
  {
  	struct ocfs2_dx_root_block *dx_root = et->et_object;
  
  	le32_add_cpu(&dx_root->dr_clusters, clusters);
  }

  static int ocfs2_dx_root_sanity_check(struct ocfs2_extent_tree *et)

  {
  	struct ocfs2_dx_root_block *dx_root = et->et_object;
  
  	BUG_ON(!OCFS2_IS_VALID_DX_ROOT(dx_root));
  
  	return 0;
  }
  
  static void ocfs2_dx_root_fill_root_el(struct ocfs2_extent_tree *et)
  {
  	struct ocfs2_dx_root_block *dx_root = et->et_object;
  
  	et->et_root_el = &dx_root->dr_list;
  }
  
  static struct ocfs2_extent_tree_operations ocfs2_dx_root_et_ops = {
  	.eo_set_last_eb_blk	= ocfs2_dx_root_set_last_eb_blk,
  	.eo_get_last_eb_blk	= ocfs2_dx_root_get_last_eb_blk,
  	.eo_update_clusters	= ocfs2_dx_root_update_clusters,
  	.eo_sanity_check	= ocfs2_dx_root_sanity_check,
  	.eo_fill_root_el	= ocfs2_dx_root_fill_root_el,
  };

  static void ocfs2_refcount_tree_fill_root_el(struct ocfs2_extent_tree *et)
  {
  	struct ocfs2_refcount_block *rb = et->et_object;
  
  	et->et_root_el = &rb->rf_list;
  }
  
  static void ocfs2_refcount_tree_set_last_eb_blk(struct ocfs2_extent_tree *et,
  						u64 blkno)
  {
  	struct ocfs2_refcount_block *rb = et->et_object;
  
  	rb->rf_last_eb_blk = cpu_to_le64(blkno);
  }
  
  static u64 ocfs2_refcount_tree_get_last_eb_blk(struct ocfs2_extent_tree *et)
  {
  	struct ocfs2_refcount_block *rb = et->et_object;
  
  	return le64_to_cpu(rb->rf_last_eb_blk);
  }
  
  static void ocfs2_refcount_tree_update_clusters(struct ocfs2_extent_tree *et,
  						u32 clusters)
  {
  	struct ocfs2_refcount_block *rb = et->et_object;
  
  	le32_add_cpu(&rb->rf_clusters, clusters);
  }
  
  static enum ocfs2_contig_type
  ocfs2_refcount_tree_extent_contig(struct ocfs2_extent_tree *et,
  				  struct ocfs2_extent_rec *ext,
  				  struct ocfs2_extent_rec *insert_rec)
  {
  	return CONTIG_NONE;
  }
  
  static struct ocfs2_extent_tree_operations ocfs2_refcount_tree_et_ops = {
  	.eo_set_last_eb_blk	= ocfs2_refcount_tree_set_last_eb_blk,
  	.eo_get_last_eb_blk	= ocfs2_refcount_tree_get_last_eb_blk,
  	.eo_update_clusters	= ocfs2_refcount_tree_update_clusters,
  	.eo_fill_root_el	= ocfs2_refcount_tree_fill_root_el,
  	.eo_extent_contig	= ocfs2_refcount_tree_extent_contig,
  };

  static void __ocfs2_init_extent_tree(struct ocfs2_extent_tree *et,

  				     struct ocfs2_caching_info *ci,

  				     struct buffer_head *bh,

  				     ocfs2_journal_access_func access,

  				     void *obj,
  				     struct ocfs2_extent_tree_operations *ops)

  {

  	et->et_ops = ops;

  	et->et_root_bh = bh;

  	et->et_ci = ci;

  	et->et_root_journal_access = access;

  	if (!obj)
  		obj = (void *)bh->b_data;
  	et->et_object = obj;

  	et->et_ops->eo_fill_root_el(et);

  	if (!et->et_ops->eo_fill_max_leaf_clusters)
  		et->et_max_leaf_clusters = 0;
  	else

  		et->et_ops->eo_fill_max_leaf_clusters(et);

  }

  void ocfs2_init_dinode_extent_tree(struct ocfs2_extent_tree *et,

  				   struct ocfs2_caching_info *ci,

  				   struct buffer_head *bh)

  {

  	__ocfs2_init_extent_tree(et, ci, bh, ocfs2_journal_access_di,

  				 NULL, &ocfs2_dinode_et_ops);

  }

  void ocfs2_init_xattr_tree_extent_tree(struct ocfs2_extent_tree *et,

  				       struct ocfs2_caching_info *ci,

  				       struct buffer_head *bh)

  {

  	__ocfs2_init_extent_tree(et, ci, bh, ocfs2_journal_access_xb,

  				 NULL, &ocfs2_xattr_tree_et_ops);

  }

  void ocfs2_init_xattr_value_extent_tree(struct ocfs2_extent_tree *et,

  					struct ocfs2_caching_info *ci,

  					struct ocfs2_xattr_value_buf *vb)

  {

  	__ocfs2_init_extent_tree(et, ci, vb->vb_bh, vb->vb_access, vb,

  				 &ocfs2_xattr_value_et_ops);

  }

  void ocfs2_init_dx_root_extent_tree(struct ocfs2_extent_tree *et,

  				    struct ocfs2_caching_info *ci,

  				    struct buffer_head *bh)
  {

  	__ocfs2_init_extent_tree(et, ci, bh, ocfs2_journal_access_dr,

  				 NULL, &ocfs2_dx_root_et_ops);
  }

  void ocfs2_init_refcount_extent_tree(struct ocfs2_extent_tree *et,
  				     struct ocfs2_caching_info *ci,
  				     struct buffer_head *bh)
  {
  	__ocfs2_init_extent_tree(et, ci, bh, ocfs2_journal_access_rb,
  				 NULL, &ocfs2_refcount_tree_et_ops);
  }

  static inline void ocfs2_et_set_last_eb_blk(struct ocfs2_extent_tree *et,
  					    u64 new_last_eb_blk)

  {

  	et->et_ops->eo_set_last_eb_blk(et, new_last_eb_blk);

  }

  static inline u64 ocfs2_et_get_last_eb_blk(struct ocfs2_extent_tree *et)

  {

  	return et->et_ops->eo_get_last_eb_blk(et);

  }

  static inline void ocfs2_et_update_clusters(struct ocfs2_extent_tree *et,

  					    u32 clusters)
  {

  	et->et_ops->eo_update_clusters(et, clusters);

  }

  static inline void ocfs2_et_extent_map_insert(struct ocfs2_extent_tree *et,
  					      struct ocfs2_extent_rec *rec)
  {
  	if (et->et_ops->eo_extent_map_insert)
  		et->et_ops->eo_extent_map_insert(et, rec);
  }

  static inline void ocfs2_et_extent_map_truncate(struct ocfs2_extent_tree *et,
  						u32 clusters)
  {
  	if (et->et_ops->eo_extent_map_truncate)
  		et->et_ops->eo_extent_map_truncate(et, clusters);
  }

  static inline int ocfs2_et_root_journal_access(handle_t *handle,

  					       struct ocfs2_extent_tree *et,
  					       int type)
  {

  	return et->et_root_journal_access(handle, et->et_ci, et->et_root_bh,

  					  type);
  }

  static inline enum ocfs2_contig_type
  	ocfs2_et_extent_contig(struct ocfs2_extent_tree *et,
  			       struct ocfs2_extent_rec *rec,
  			       struct ocfs2_extent_rec *insert_rec)
  {
  	if (et->et_ops->eo_extent_contig)
  		return et->et_ops->eo_extent_contig(et, rec, insert_rec);
  
  	return ocfs2_extent_rec_contig(
  				ocfs2_metadata_cache_get_super(et->et_ci),
  				rec, insert_rec);
  }

  static inline int ocfs2_et_insert_check(struct ocfs2_extent_tree *et,

  					struct ocfs2_extent_rec *rec)
  {
  	int ret = 0;
  
  	if (et->et_ops->eo_insert_check)

  		ret = et->et_ops->eo_insert_check(et, rec);

  	return ret;
  }

  static inline int ocfs2_et_sanity_check(struct ocfs2_extent_tree *et)

  {

  	int ret = 0;
  
  	if (et->et_ops->eo_sanity_check)

  		ret = et->et_ops->eo_sanity_check(et);

  	return ret;

  }

  static int ocfs2_cache_extent_block_free(struct ocfs2_cached_dealloc_ctxt *ctxt,
  					 struct ocfs2_extent_block *eb);

  static void ocfs2_adjust_rightmost_records(handle_t *handle,
  					   struct ocfs2_extent_tree *et,

  					   struct ocfs2_path *path,
  					   struct ocfs2_extent_rec *insert_rec);

  /*
   * Reset the actual path elements so that we can re-use the structure
   * to build another path. Generally, this involves freeing the buffer
   * heads.
   */

  void ocfs2_reinit_path(struct ocfs2_path *path, int keep_root)

  {
  	int i, start = 0, depth = 0;
  	struct ocfs2_path_item *node;

  	if (keep_root)
  		start = 1;

  	for(i = start; i < path_num_items(path); i++) {
  		node = &path->p_node[i];
  
  		brelse(node->bh);
  		node->bh = NULL;
  		node->el = NULL;
  	}
  
  	/*
  	 * Tree depth may change during truncate, or insert. If we're
  	 * keeping the root extent list, then make sure that our path
  	 * structure reflects the proper depth.
  	 */
  	if (keep_root)
  		depth = le16_to_cpu(path_root_el(path)->l_tree_depth);

  	else
  		path_root_access(path) = NULL;

  
  	path->p_tree_depth = depth;
  }

  void ocfs2_free_path(struct ocfs2_path *path)

  {
  	if (path) {
  		ocfs2_reinit_path(path, 0);
  		kfree(path);
  	}
  }
  
  /*

   * All the elements of src into dest. After this call, src could be freed
   * without affecting dest.
   *
   * Both paths should have the same root. Any non-root elements of dest
   * will be freed.
   */
  static void ocfs2_cp_path(struct ocfs2_path *dest, struct ocfs2_path *src)
  {
  	int i;
  
  	BUG_ON(path_root_bh(dest) != path_root_bh(src));
  	BUG_ON(path_root_el(dest) != path_root_el(src));

  	BUG_ON(path_root_access(dest) != path_root_access(src));

  
  	ocfs2_reinit_path(dest, 1);
  
  	for(i = 1; i < OCFS2_MAX_PATH_DEPTH; i++) {
  		dest->p_node[i].bh = src->p_node[i].bh;
  		dest->p_node[i].el = src->p_node[i].el;
  
  		if (dest->p_node[i].bh)
  			get_bh(dest->p_node[i].bh);
  	}
  }
  
  /*

   * Make the *dest path the same as src and re-initialize src path to
   * have a root only.
   */
  static void ocfs2_mv_path(struct ocfs2_path *dest, struct ocfs2_path *src)
  {
  	int i;
  
  	BUG_ON(path_root_bh(dest) != path_root_bh(src));

  	BUG_ON(path_root_access(dest) != path_root_access(src));

  
  	for(i = 1; i < OCFS2_MAX_PATH_DEPTH; i++) {
  		brelse(dest->p_node[i].bh);
  
  		dest->p_node[i].bh = src->p_node[i].bh;
  		dest->p_node[i].el = src->p_node[i].el;
  
  		src->p_node[i].bh = NULL;
  		src->p_node[i].el = NULL;
  	}
  }
  
  /*
   * Insert an extent block at given index.
   *
   * This will not take an additional reference on eb_bh.
   */
  static inline void ocfs2_path_insert_eb(struct ocfs2_path *path, int index,
  					struct buffer_head *eb_bh)
  {
  	struct ocfs2_extent_block *eb = (struct ocfs2_extent_block *)eb_bh->b_data;
  
  	/*
  	 * Right now, no root bh is an extent block, so this helps
  	 * catch code errors with dinode trees. The assertion can be
  	 * safely removed if we ever need to insert extent block
  	 * structures at the root.
  	 */
  	BUG_ON(index == 0);
  
  	path->p_node[index].bh = eb_bh;
  	path->p_node[index].el = &eb->h_list;
  }
  
  static struct ocfs2_path *ocfs2_new_path(struct buffer_head *root_bh,

  					 struct ocfs2_extent_list *root_el,
  					 ocfs2_journal_access_func access)

  {
  	struct ocfs2_path *path;

  	BUG_ON(le16_to_cpu(root_el->l_tree_depth) >= OCFS2_MAX_PATH_DEPTH);
  
  	path = kzalloc(sizeof(*path), GFP_NOFS);
  	if (path) {
  		path->p_tree_depth = le16_to_cpu(root_el->l_tree_depth);
  		get_bh(root_bh);
  		path_root_bh(path) = root_bh;
  		path_root_el(path) = root_el;

  		path_root_access(path) = access;

  	}
  
  	return path;
  }

  struct ocfs2_path *ocfs2_new_path_from_path(struct ocfs2_path *path)

  {

  	return ocfs2_new_path(path_root_bh(path), path_root_el(path),
  			      path_root_access(path));

  }

  struct ocfs2_path *ocfs2_new_path_from_et(struct ocfs2_extent_tree *et)

  {

  	return ocfs2_new_path(et->et_root_bh, et->et_root_el,
  			      et->et_root_journal_access);
  }
  
  /*
   * Journal the buffer at depth idx.  All idx>0 are extent_blocks,
   * otherwise it's the root_access function.
   *
   * I don't like the way this function's name looks next to
   * ocfs2_journal_access_path(), but I don't have a better one.
   */

  int ocfs2_path_bh_journal_access(handle_t *handle,
  				 struct ocfs2_caching_info *ci,
  				 struct ocfs2_path *path,
  				 int idx)

  {
  	ocfs2_journal_access_func access = path_root_access(path);
  
  	if (!access)
  		access = ocfs2_journal_access;
  
  	if (idx)
  		access = ocfs2_journal_access_eb;

  	return access(handle, ci, path->p_node[idx].bh,

  		      OCFS2_JOURNAL_ACCESS_WRITE);

  }

  /*

   * Convenience function to journal all components in a path.
   */

  int ocfs2_journal_access_path(struct ocfs2_caching_info *ci,
  			      handle_t *handle,
  			      struct ocfs2_path *path)

  {
  	int i, ret = 0;
  
  	if (!path)
  		goto out;
  
  	for(i = 0; i < path_num_items(path); i++) {

  		ret = ocfs2_path_bh_journal_access(handle, ci, path, i);

  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  out:
  	return ret;
  }

  /*
   * Return the index of the extent record which contains cluster #v_cluster.
   * -1 is returned if it was not found.
   *
   * Should work fine on interior and exterior nodes.
   */
  int ocfs2_search_extent_list(struct ocfs2_extent_list *el, u32 v_cluster)
  {
  	int ret = -1;
  	int i;
  	struct ocfs2_extent_rec *rec;
  	u32 rec_end, rec_start, clusters;
  
  	for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
  		rec = &el->l_recs[i];
  
  		rec_start = le32_to_cpu(rec->e_cpos);
  		clusters = ocfs2_rec_clusters(el, rec);
  
  		rec_end = rec_start + clusters;
  
  		if (v_cluster >= rec_start && v_cluster < rec_end) {
  			ret = i;
  			break;
  		}
  	}
  
  	return ret;
  }

  /*
   * NOTE: ocfs2_block_extent_contig(), ocfs2_extents_adjacent() and

   * ocfs2_extent_rec_contig only work properly against leaf nodes!

   */

  static int ocfs2_block_extent_contig(struct super_block *sb,
  				     struct ocfs2_extent_rec *ext,
  				     u64 blkno)

  {

  	u64 blk_end = le64_to_cpu(ext->e_blkno);
  
  	blk_end += ocfs2_clusters_to_blocks(sb,
  				    le16_to_cpu(ext->e_leaf_clusters));
  
  	return blkno == blk_end;

  }

  static int ocfs2_extents_adjacent(struct ocfs2_extent_rec *left,
  				  struct ocfs2_extent_rec *right)
  {

  	u32 left_range;
  
  	left_range = le32_to_cpu(left->e_cpos) +
  		le16_to_cpu(left->e_leaf_clusters);
  
  	return (left_range == le32_to_cpu(right->e_cpos));

  }
  
  static enum ocfs2_contig_type

  	ocfs2_extent_rec_contig(struct super_block *sb,
  				struct ocfs2_extent_rec *ext,
  				struct ocfs2_extent_rec *insert_rec)

  {
  	u64 blkno = le64_to_cpu(insert_rec->e_blkno);

  	/*
  	 * Refuse to coalesce extent records with different flag
  	 * fields - we don't want to mix unwritten extents with user
  	 * data.
  	 */
  	if (ext->e_flags != insert_rec->e_flags)
  		return CONTIG_NONE;

  	if (ocfs2_extents_adjacent(ext, insert_rec) &&

  	    ocfs2_block_extent_contig(sb, ext, blkno))

  			return CONTIG_RIGHT;
  
  	blkno = le64_to_cpu(ext->e_blkno);
  	if (ocfs2_extents_adjacent(insert_rec, ext) &&

  	    ocfs2_block_extent_contig(sb, insert_rec, blkno))

  		return CONTIG_LEFT;
  
  	return CONTIG_NONE;
  }
  
  /*
   * NOTE: We can have pretty much any combination of contiguousness and
   * appending.
   *
   * The usefulness of APPEND_TAIL is more in that it lets us know that
   * we'll have to update the path to that leaf.
   */
  enum ocfs2_append_type {
  	APPEND_NONE = 0,
  	APPEND_TAIL,
  };

  enum ocfs2_split_type {
  	SPLIT_NONE = 0,
  	SPLIT_LEFT,
  	SPLIT_RIGHT,
  };

  struct ocfs2_insert_type {

  	enum ocfs2_split_type	ins_split;

  	enum ocfs2_append_type	ins_appending;
  	enum ocfs2_contig_type	ins_contig;
  	int			ins_contig_index;

  	int			ins_tree_depth;
  };

  struct ocfs2_merge_ctxt {
  	enum ocfs2_contig_type	c_contig_type;
  	int			c_has_empty_extent;
  	int			c_split_covers_rec;

  };

  static int ocfs2_validate_extent_block(struct super_block *sb,
  				       struct buffer_head *bh)
  {

  	int rc;

  	struct ocfs2_extent_block *eb =
  		(struct ocfs2_extent_block *)bh->b_data;

  	trace_ocfs2_validate_extent_block((unsigned long long)bh->b_blocknr);

  	BUG_ON(!buffer_uptodate(bh));
  
  	/*
  	 * If the ecc fails, we return the error but otherwise
  	 * leave the filesystem running.  We know any error is
  	 * local to this block.
  	 */
  	rc = ocfs2_validate_meta_ecc(sb, bh->b_data, &eb->h_check);

  	if (rc) {
  		mlog(ML_ERROR, "Checksum failed for extent block %llu
  ",
  		     (unsigned long long)bh->b_blocknr);

  		return rc;

  	}

  
  	/*
  	 * Errors after here are fatal.
  	 */

  	if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
  		ocfs2_error(sb,
  			    "Extent block #%llu has bad signature %.*s",
  			    (unsigned long long)bh->b_blocknr, 7,
  			    eb->h_signature);
  		return -EINVAL;
  	}
  
  	if (le64_to_cpu(eb->h_blkno) != bh->b_blocknr) {
  		ocfs2_error(sb,
  			    "Extent block #%llu has an invalid h_blkno "
  			    "of %llu",
  			    (unsigned long long)bh->b_blocknr,
  			    (unsigned long long)le64_to_cpu(eb->h_blkno));
  		return -EINVAL;
  	}
  
  	if (le32_to_cpu(eb->h_fs_generation) != OCFS2_SB(sb)->fs_generation) {
  		ocfs2_error(sb,
  			    "Extent block #%llu has an invalid "
  			    "h_fs_generation of #%u",
  			    (unsigned long long)bh->b_blocknr,
  			    le32_to_cpu(eb->h_fs_generation));
  		return -EINVAL;
  	}
  
  	return 0;
  }

  int ocfs2_read_extent_block(struct ocfs2_caching_info *ci, u64 eb_blkno,

  			    struct buffer_head **bh)
  {
  	int rc;
  	struct buffer_head *tmp = *bh;

  	rc = ocfs2_read_block(ci, eb_blkno, &tmp,

  			      ocfs2_validate_extent_block);

  
  	/* If ocfs2_read_block() got us a new bh, pass it up. */

  	if (!rc && !*bh)

  		*bh = tmp;

  	return rc;
  }

  /*
   * How many free extents have we got before we need more meta data?
   */
  int ocfs2_num_free_extents(struct ocfs2_super *osb,

  			   struct ocfs2_extent_tree *et)

  {
  	int retval;

  	struct ocfs2_extent_list *el = NULL;

  	struct ocfs2_extent_block *eb;
  	struct buffer_head *eb_bh = NULL;

  	u64 last_eb_blk = 0;

  	el = et->et_root_el;
  	last_eb_blk = ocfs2_et_get_last_eb_blk(et);

  	if (last_eb_blk) {

  		retval = ocfs2_read_extent_block(et->et_ci, last_eb_blk,
  						 &eb_bh);

  		if (retval < 0) {
  			mlog_errno(retval);
  			goto bail;
  		}
  		eb = (struct ocfs2_extent_block *) eb_bh->b_data;
  		el = &eb->h_list;

  	}

  
  	BUG_ON(el->l_tree_depth != 0);
  
  	retval = le16_to_cpu(el->l_count) - le16_to_cpu(el->l_next_free_rec);
  bail:

  	brelse(eb_bh);

  	trace_ocfs2_num_free_extents(retval);

  	return retval;
  }
  
  /* expects array to already be allocated
   *
   * sets h_signature, h_blkno, h_suballoc_bit, h_suballoc_slot, and
   * l_count for you
   */

  static int ocfs2_create_new_meta_bhs(handle_t *handle,
  				     struct ocfs2_extent_tree *et,

  				     int wanted,
  				     struct ocfs2_alloc_context *meta_ac,
  				     struct buffer_head *bhs[])
  {
  	int count, status, i;
  	u16 suballoc_bit_start;
  	u32 num_got;

  	u64 suballoc_loc, first_blkno;

  	struct ocfs2_super *osb =
  		OCFS2_SB(ocfs2_metadata_cache_get_super(et->et_ci));

  	struct ocfs2_extent_block *eb;

  	count = 0;
  	while (count < wanted) {

  		status = ocfs2_claim_metadata(handle,

  					      meta_ac,
  					      wanted - count,

  					      &suballoc_loc,

  					      &suballoc_bit_start,
  					      &num_got,
  					      &first_blkno);
  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  
  		for(i = count;  i < (num_got + count); i++) {
  			bhs[i] = sb_getblk(osb->sb, first_blkno);
  			if (bhs[i] == NULL) {
  				status = -EIO;
  				mlog_errno(status);
  				goto bail;
  			}

  			ocfs2_set_new_buffer_uptodate(et->et_ci, bhs[i]);

  			status = ocfs2_journal_access_eb(handle, et->et_ci,
  							 bhs[i],

  							 OCFS2_JOURNAL_ACCESS_CREATE);

  			if (status < 0) {
  				mlog_errno(status);
  				goto bail;
  			}
  
  			memset(bhs[i]->b_data, 0, osb->sb->s_blocksize);
  			eb = (struct ocfs2_extent_block *) bhs[i]->b_data;
  			/* Ok, setup the minimal stuff here. */
  			strcpy(eb->h_signature, OCFS2_EXTENT_BLOCK_SIGNATURE);
  			eb->h_blkno = cpu_to_le64(first_blkno);
  			eb->h_fs_generation = cpu_to_le32(osb->fs_generation);

  			eb->h_suballoc_slot =
  				cpu_to_le16(meta_ac->ac_alloc_slot);

  			eb->h_suballoc_loc = cpu_to_le64(suballoc_loc);

  			eb->h_suballoc_bit = cpu_to_le16(suballoc_bit_start);
  			eb->h_list.l_count =
  				cpu_to_le16(ocfs2_extent_recs_per_eb(osb->sb));
  
  			suballoc_bit_start++;
  			first_blkno++;
  
  			/* We'll also be dirtied by the caller, so
  			 * this isn't absolutely necessary. */

  			ocfs2_journal_dirty(handle, bhs[i]);

  		}
  
  		count += num_got;
  	}
  
  	status = 0;
  bail:
  	if (status < 0) {
  		for(i = 0; i < wanted; i++) {

  			brelse(bhs[i]);

  			bhs[i] = NULL;
  		}

  		mlog_errno(status);

  	}

  	return status;
  }
  
  /*

   * Helper function for ocfs2_add_branch() and ocfs2_shift_tree_depth().
   *
   * Returns the sum of the rightmost extent rec logical offset and
   * cluster count.
   *
   * ocfs2_add_branch() uses this to determine what logical cluster
   * value should be populated into the leftmost new branch records.
   *
   * ocfs2_shift_tree_depth() uses this to determine the # clusters
   * value for the new topmost tree record.
   */
  static inline u32 ocfs2_sum_rightmost_rec(struct ocfs2_extent_list  *el)
  {
  	int i;
  
  	i = le16_to_cpu(el->l_next_free_rec) - 1;
  
  	return le32_to_cpu(el->l_recs[i].e_cpos) +

  		ocfs2_rec_clusters(el, &el->l_recs[i]);

  }
  
  /*

   * Change range of the branches in the right most path according to the leaf
   * extent block's rightmost record.
   */
  static int ocfs2_adjust_rightmost_branch(handle_t *handle,

  					 struct ocfs2_extent_tree *et)
  {
  	int status;
  	struct ocfs2_path *path = NULL;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_rec *rec;
  
  	path = ocfs2_new_path_from_et(et);
  	if (!path) {
  		status = -ENOMEM;
  		return status;
  	}

  	status = ocfs2_find_path(et->et_ci, path, UINT_MAX);

  	if (status < 0) {
  		mlog_errno(status);
  		goto out;
  	}

  	status = ocfs2_extend_trans(handle, path_num_items(path));

  	if (status < 0) {
  		mlog_errno(status);
  		goto out;
  	}

  	status = ocfs2_journal_access_path(et->et_ci, handle, path);

  	if (status < 0) {
  		mlog_errno(status);
  		goto out;
  	}
  
  	el = path_leaf_el(path);
  	rec = &el->l_recs[le32_to_cpu(el->l_next_free_rec) - 1];

  	ocfs2_adjust_rightmost_records(handle, et, path, rec);

  
  out:
  	ocfs2_free_path(path);
  	return status;
  }
  
  /*

   * Add an entire tree branch to our inode. eb_bh is the extent block

   * to start at, if we don't want to start the branch at the root

   * structure.
   *
   * last_eb_bh is required as we have to update it's next_leaf pointer
   * for the new last extent block.
   *
   * the new branch will be 'empty' in the sense that every block will

   * contain a single record with cluster count == 0.

   */

  static int ocfs2_add_branch(handle_t *handle,

  			    struct ocfs2_extent_tree *et,

  			    struct buffer_head *eb_bh,

  			    struct buffer_head **last_eb_bh,

  			    struct ocfs2_alloc_context *meta_ac)
  {
  	int status, new_blocks, i;
  	u64 next_blkno, new_last_eb_blk;
  	struct buffer_head *bh;
  	struct buffer_head **new_eb_bhs = NULL;

  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list  *eb_el;
  	struct ocfs2_extent_list  *el;

  	u32 new_cpos, root_end;

  	BUG_ON(!last_eb_bh || !*last_eb_bh);

  	if (eb_bh) {
  		eb = (struct ocfs2_extent_block *) eb_bh->b_data;
  		el = &eb->h_list;
  	} else

  		el = et->et_root_el;

  
  	/* we never add a branch to a leaf. */
  	BUG_ON(!el->l_tree_depth);
  
  	new_blocks = le16_to_cpu(el->l_tree_depth);

  	eb = (struct ocfs2_extent_block *)(*last_eb_bh)->b_data;
  	new_cpos = ocfs2_sum_rightmost_rec(&eb->h_list);
  	root_end = ocfs2_sum_rightmost_rec(et->et_root_el);
  
  	/*
  	 * If there is a gap before the root end and the real end
  	 * of the righmost leaf block, we need to remove the gap
  	 * between new_cpos and root_end first so that the tree
  	 * is consistent after we add a new branch(it will start
  	 * from new_cpos).
  	 */
  	if (root_end > new_cpos) {

  		trace_ocfs2_adjust_rightmost_branch(
  			(unsigned long long)
  			ocfs2_metadata_cache_owner(et->et_ci),
  			root_end, new_cpos);

  		status = ocfs2_adjust_rightmost_branch(handle, et);

  		if (status) {
  			mlog_errno(status);
  			goto bail;
  		}
  	}

  	/* allocate the number of new eb blocks we need */
  	new_eb_bhs = kcalloc(new_blocks, sizeof(struct buffer_head *),
  			     GFP_KERNEL);
  	if (!new_eb_bhs) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}

  	status = ocfs2_create_new_meta_bhs(handle, et, new_blocks,

  					   meta_ac, new_eb_bhs);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	/* Note: new_eb_bhs[new_blocks - 1] is the guy which will be
  	 * linked with the rest of the tree.
  	 * conversly, new_eb_bhs[0] is the new bottommost leaf.
  	 *
  	 * when we leave the loop, new_last_eb_blk will point to the
  	 * newest leaf, and next_blkno will point to the topmost extent
  	 * block. */
  	next_blkno = new_last_eb_blk = 0;
  	for(i = 0; i < new_blocks; i++) {
  		bh = new_eb_bhs[i];
  		eb = (struct ocfs2_extent_block *) bh->b_data;

  		/* ocfs2_create_new_meta_bhs() should create it right! */
  		BUG_ON(!OCFS2_IS_VALID_EXTENT_BLOCK(eb));

  		eb_el = &eb->h_list;

  		status = ocfs2_journal_access_eb(handle, et->et_ci, bh,

  						 OCFS2_JOURNAL_ACCESS_CREATE);

  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  
  		eb->h_next_leaf_blk = 0;
  		eb_el->l_tree_depth = cpu_to_le16(i);
  		eb_el->l_next_free_rec = cpu_to_le16(1);

  		/*
  		 * This actually counts as an empty extent as
  		 * c_clusters == 0
  		 */
  		eb_el->l_recs[0].e_cpos = cpu_to_le32(new_cpos);

  		eb_el->l_recs[0].e_blkno = cpu_to_le64(next_blkno);

  		/*
  		 * eb_el isn't always an interior node, but even leaf
  		 * nodes want a zero'd flags and reserved field so
  		 * this gets the whole 32 bits regardless of use.
  		 */
  		eb_el->l_recs[0].e_int_clusters = cpu_to_le32(0);

  		if (!eb_el->l_tree_depth)
  			new_last_eb_blk = le64_to_cpu(eb->h_blkno);

  		ocfs2_journal_dirty(handle, bh);

  		next_blkno = le64_to_cpu(eb->h_blkno);
  	}
  
  	/* This is a bit hairy. We want to update up to three blocks
  	 * here without leaving any of them in an inconsistent state
  	 * in case of error. We don't have to worry about
  	 * journal_dirty erroring as it won't unless we've aborted the
  	 * handle (in which case we would never be here) so reserving
  	 * the write with journal_access is all we need to do. */

  	status = ocfs2_journal_access_eb(handle, et->et_ci, *last_eb_bh,

  					 OCFS2_JOURNAL_ACCESS_WRITE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}

  	status = ocfs2_et_root_journal_access(handle, et,

  					      OCFS2_JOURNAL_ACCESS_WRITE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  	if (eb_bh) {

  		status = ocfs2_journal_access_eb(handle, et->et_ci, eb_bh,

  						 OCFS2_JOURNAL_ACCESS_WRITE);

  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  	}
  
  	/* Link the new branch into the rest of the tree (el will

  	 * either be on the root_bh, or the extent block passed in. */

  	i = le16_to_cpu(el->l_next_free_rec);
  	el->l_recs[i].e_blkno = cpu_to_le64(next_blkno);

  	el->l_recs[i].e_cpos = cpu_to_le32(new_cpos);

  	el->l_recs[i].e_int_clusters = 0;

  	le16_add_cpu(&el->l_next_free_rec, 1);
  
  	/* fe needs a new last extent block pointer, as does the
  	 * next_leaf on the previously last-extent-block. */

  	ocfs2_et_set_last_eb_blk(et, new_last_eb_blk);

  	eb = (struct ocfs2_extent_block *) (*last_eb_bh)->b_data;

  	eb->h_next_leaf_blk = cpu_to_le64(new_last_eb_blk);

  	ocfs2_journal_dirty(handle, *last_eb_bh);
  	ocfs2_journal_dirty(handle, et->et_root_bh);
  	if (eb_bh)
  		ocfs2_journal_dirty(handle, eb_bh);

  	/*
  	 * Some callers want to track the rightmost leaf so pass it
  	 * back here.
  	 */
  	brelse(*last_eb_bh);
  	get_bh(new_eb_bhs[0]);
  	*last_eb_bh = new_eb_bhs[0];

  	status = 0;
  bail:
  	if (new_eb_bhs) {
  		for (i = 0; i < new_blocks; i++)

  			brelse(new_eb_bhs[i]);

  		kfree(new_eb_bhs);
  	}

  	return status;
  }
  
  /*
   * adds another level to the allocation tree.
   * returns back the new extent block so you can add a branch to it
   * after this call.
   */

  static int ocfs2_shift_tree_depth(handle_t *handle,

  				  struct ocfs2_extent_tree *et,

  				  struct ocfs2_alloc_context *meta_ac,
  				  struct buffer_head **ret_new_eb_bh)
  {
  	int status, i;

  	u32 new_clusters;

  	struct buffer_head *new_eb_bh = NULL;

  	struct ocfs2_extent_block *eb;

  	struct ocfs2_extent_list  *root_el;

  	struct ocfs2_extent_list  *eb_el;

  	status = ocfs2_create_new_meta_bhs(handle, et, 1, meta_ac,

  					   &new_eb_bh);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	eb = (struct ocfs2_extent_block *) new_eb_bh->b_data;

  	/* ocfs2_create_new_meta_bhs() should create it right! */
  	BUG_ON(!OCFS2_IS_VALID_EXTENT_BLOCK(eb));

  
  	eb_el = &eb->h_list;

  	root_el = et->et_root_el;

  	status = ocfs2_journal_access_eb(handle, et->et_ci, new_eb_bh,

  					 OCFS2_JOURNAL_ACCESS_CREATE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}

  	/* copy the root extent list data into the new extent block */
  	eb_el->l_tree_depth = root_el->l_tree_depth;
  	eb_el->l_next_free_rec = root_el->l_next_free_rec;
  	for (i = 0; i < le16_to_cpu(root_el->l_next_free_rec); i++)
  		eb_el->l_recs[i] = root_el->l_recs[i];

  	ocfs2_journal_dirty(handle, new_eb_bh);

  	status = ocfs2_et_root_journal_access(handle, et,

  					      OCFS2_JOURNAL_ACCESS_WRITE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}

  	new_clusters = ocfs2_sum_rightmost_rec(eb_el);

  	/* update root_bh now */
  	le16_add_cpu(&root_el->l_tree_depth, 1);
  	root_el->l_recs[0].e_cpos = 0;
  	root_el->l_recs[0].e_blkno = eb->h_blkno;
  	root_el->l_recs[0].e_int_clusters = cpu_to_le32(new_clusters);
  	for (i = 1; i < le16_to_cpu(root_el->l_next_free_rec); i++)
  		memset(&root_el->l_recs[i], 0, sizeof(struct ocfs2_extent_rec));
  	root_el->l_next_free_rec = cpu_to_le16(1);

  
  	/* If this is our 1st tree depth shift, then last_eb_blk
  	 * becomes the allocated extent block */

  	if (root_el->l_tree_depth == cpu_to_le16(1))

  		ocfs2_et_set_last_eb_blk(et, le64_to_cpu(eb->h_blkno));

  	ocfs2_journal_dirty(handle, et->et_root_bh);

  
  	*ret_new_eb_bh = new_eb_bh;
  	new_eb_bh = NULL;
  	status = 0;
  bail:

  	brelse(new_eb_bh);

  	return status;
  }
  
  /*

   * Should only be called when there is no space left in any of the
   * leaf nodes. What we want to do is find the lowest tree depth
   * non-leaf extent block with room for new records. There are three
   * valid results of this search:
   *
   * 1) a lowest extent block is found, then we pass it back in
   *    *lowest_eb_bh and return '0'
   *

   * 2) the search fails to find anything, but the root_el has room. We

   *    pass NULL back in *lowest_eb_bh, but still return '0'
   *

   * 3) the search fails to find anything AND the root_el is full, in

   *    which case we return > 0
   *
   * return status < 0 indicates an error.
   */

  static int ocfs2_find_branch_target(struct ocfs2_extent_tree *et,

  				    struct buffer_head **target_bh)
  {
  	int status = 0, i;
  	u64 blkno;

  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list  *el;
  	struct buffer_head *bh = NULL;
  	struct buffer_head *lowest_bh = NULL;

  	*target_bh = NULL;

  	el = et->et_root_el;

  
  	while(le16_to_cpu(el->l_tree_depth) > 1) {
  		if (le16_to_cpu(el->l_next_free_rec) == 0) {

  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  				    "Owner %llu has empty "

  				    "extent list (next_free_rec == 0)",

  				    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci));

  			status = -EIO;
  			goto bail;
  		}
  		i = le16_to_cpu(el->l_next_free_rec) - 1;
  		blkno = le64_to_cpu(el->l_recs[i].e_blkno);
  		if (!blkno) {

  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  				    "Owner %llu has extent "

  				    "list where extent # %d has no physical "
  				    "block start",

  				    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci), i);

  			status = -EIO;
  			goto bail;
  		}

  		brelse(bh);
  		bh = NULL;

  		status = ocfs2_read_extent_block(et->et_ci, blkno, &bh);

  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}

  
  		eb = (struct ocfs2_extent_block *) bh->b_data;

  		el = &eb->h_list;
  
  		if (le16_to_cpu(el->l_next_free_rec) <
  		    le16_to_cpu(el->l_count)) {

  			brelse(lowest_bh);

  			lowest_bh = bh;
  			get_bh(lowest_bh);
  		}
  	}
  
  	/* If we didn't find one and the fe doesn't have any room,
  	 * then return '1' */

  	el = et->et_root_el;

  	if (!lowest_bh && (el->l_next_free_rec == el->l_count))

  		status = 1;
  
  	*target_bh = lowest_bh;
  bail:

  	brelse(bh);

  	return status;
  }

  /*

   * Grow a b-tree so that it has more records.
   *
   * We might shift the tree depth in which case existing paths should
   * be considered invalid.
   *
   * Tree depth after the grow is returned via *final_depth.

   *
   * *last_eb_bh will be updated by ocfs2_add_branch().

   */

  static int ocfs2_grow_tree(handle_t *handle, struct ocfs2_extent_tree *et,
  			   int *final_depth, struct buffer_head **last_eb_bh,

  			   struct ocfs2_alloc_context *meta_ac)
  {
  	int ret, shift;

  	struct ocfs2_extent_list *el = et->et_root_el;

  	int depth = le16_to_cpu(el->l_tree_depth);

  	struct buffer_head *bh = NULL;
  
  	BUG_ON(meta_ac == NULL);

  	shift = ocfs2_find_branch_target(et, &bh);

  	if (shift < 0) {
  		ret = shift;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/* We traveled all the way to the bottom of the allocation tree
  	 * and didn't find room for any more extents - we need to add
  	 * another tree level */
  	if (shift) {
  		BUG_ON(bh);

  		trace_ocfs2_grow_tree(
  			(unsigned long long)
  			ocfs2_metadata_cache_owner(et->et_ci),
  			depth);

  
  		/* ocfs2_shift_tree_depth will return us a buffer with
  		 * the new extent block (so we can pass that to
  		 * ocfs2_add_branch). */

  		ret = ocfs2_shift_tree_depth(handle, et, meta_ac, &bh);

  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  		depth++;

  		if (depth == 1) {
  			/*
  			 * Special case: we have room now if we shifted from
  			 * tree_depth 0, so no more work needs to be done.
  			 *
  			 * We won't be calling add_branch, so pass
  			 * back *last_eb_bh as the new leaf. At depth
  			 * zero, it should always be null so there's
  			 * no reason to brelse.
  			 */
  			BUG_ON(*last_eb_bh);
  			get_bh(bh);
  			*last_eb_bh = bh;

  			goto out;

  		}

  	}
  
  	/* call ocfs2_add_branch to add the final part of the tree with
  	 * the new data. */

  	ret = ocfs2_add_branch(handle, et, bh, last_eb_bh,

  			       meta_ac);
  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  out:
  	if (final_depth)
  		*final_depth = depth;
  	brelse(bh);
  	return ret;
  }
  
  /*

   * This function will discard the rightmost extent record.
   */
  static void ocfs2_shift_records_right(struct ocfs2_extent_list *el)
  {
  	int next_free = le16_to_cpu(el->l_next_free_rec);
  	int count = le16_to_cpu(el->l_count);
  	unsigned int num_bytes;
  
  	BUG_ON(!next_free);
  	/* This will cause us to go off the end of our extent list. */
  	BUG_ON(next_free >= count);
  
  	num_bytes = sizeof(struct ocfs2_extent_rec) * next_free;
  
  	memmove(&el->l_recs[1], &el->l_recs[0], num_bytes);
  }
  
  static void ocfs2_rotate_leaf(struct ocfs2_extent_list *el,
  			      struct ocfs2_extent_rec *insert_rec)
  {
  	int i, insert_index, next_free, has_empty, num_bytes;
  	u32 insert_cpos = le32_to_cpu(insert_rec->e_cpos);
  	struct ocfs2_extent_rec *rec;
  
  	next_free = le16_to_cpu(el->l_next_free_rec);
  	has_empty = ocfs2_is_empty_extent(&el->l_recs[0]);
  
  	BUG_ON(!next_free);
  
  	/* The tree code before us didn't allow enough room in the leaf. */

  	BUG_ON(el->l_next_free_rec == el->l_count && !has_empty);

  
  	/*
  	 * The easiest way to approach this is to just remove the
  	 * empty extent and temporarily decrement next_free.
  	 */
  	if (has_empty) {
  		/*
  		 * If next_free was 1 (only an empty extent), this
  		 * loop won't execute, which is fine. We still want
  		 * the decrement above to happen.
  		 */
  		for(i = 0; i < (next_free - 1); i++)
  			el->l_recs[i] = el->l_recs[i+1];
  
  		next_free--;
  	}
  
  	/*
  	 * Figure out what the new record index should be.
  	 */
  	for(i = 0; i < next_free; i++) {
  		rec = &el->l_recs[i];
  
  		if (insert_cpos < le32_to_cpu(rec->e_cpos))
  			break;
  	}
  	insert_index = i;

  	trace_ocfs2_rotate_leaf(insert_cpos, insert_index,
  				has_empty, next_free,
  				le16_to_cpu(el->l_count));

  
  	BUG_ON(insert_index < 0);
  	BUG_ON(insert_index >= le16_to_cpu(el->l_count));
  	BUG_ON(insert_index > next_free);
  
  	/*
  	 * No need to memmove if we're just adding to the tail.
  	 */
  	if (insert_index != next_free) {
  		BUG_ON(next_free >= le16_to_cpu(el->l_count));
  
  		num_bytes = next_free - insert_index;
  		num_bytes *= sizeof(struct ocfs2_extent_rec);
  		memmove(&el->l_recs[insert_index + 1],
  			&el->l_recs[insert_index],
  			num_bytes);
  	}
  
  	/*
  	 * Either we had an empty extent, and need to re-increment or
  	 * there was no empty extent on a non full rightmost leaf node,
  	 * in which case we still need to increment.
  	 */
  	next_free++;
  	el->l_next_free_rec = cpu_to_le16(next_free);
  	/*
  	 * Make sure none of the math above just messed up our tree.
  	 */
  	BUG_ON(le16_to_cpu(el->l_next_free_rec) > le16_to_cpu(el->l_count));
  
  	el->l_recs[insert_index] = *insert_rec;
  
  }

  static void ocfs2_remove_empty_extent(struct ocfs2_extent_list *el)
  {
  	int size, num_recs = le16_to_cpu(el->l_next_free_rec);
  
  	BUG_ON(num_recs == 0);
  
  	if (ocfs2_is_empty_extent(&el->l_recs[0])) {
  		num_recs--;
  		size = num_recs * sizeof(struct ocfs2_extent_rec);
  		memmove(&el->l_recs[0], &el->l_recs[1], size);
  		memset(&el->l_recs[num_recs], 0,
  		       sizeof(struct ocfs2_extent_rec));
  		el->l_next_free_rec = cpu_to_le16(num_recs);
  	}
  }

  /*
   * Create an empty extent record .
   *
   * l_next_free_rec may be updated.
   *
   * If an empty extent already exists do nothing.
   */
  static void ocfs2_create_empty_extent(struct ocfs2_extent_list *el)
  {
  	int next_free = le16_to_cpu(el->l_next_free_rec);

  	BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);

  	if (next_free == 0)
  		goto set_and_inc;
  
  	if (ocfs2_is_empty_extent(&el->l_recs[0]))
  		return;
  
  	mlog_bug_on_msg(el->l_count == el->l_next_free_rec,
  			"Asked to create an empty extent in a full list:
  "
  			"count = %u, tree depth = %u",
  			le16_to_cpu(el->l_count),
  			le16_to_cpu(el->l_tree_depth));
  
  	ocfs2_shift_records_right(el);
  
  set_and_inc:
  	le16_add_cpu(&el->l_next_free_rec, 1);
  	memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
  }
  
  /*
   * For a rotation which involves two leaf nodes, the "root node" is
   * the lowest level tree node which contains a path to both leafs. This
   * resulting set of information can be used to form a complete "subtree"
   *
   * This function is passed two full paths from the dinode down to a
   * pair of adjacent leaves. It's task is to figure out which path
   * index contains the subtree root - this can be the root index itself
   * in a worst-case rotation.
   *
   * The array index of the subtree root is passed back.
   */

  int ocfs2_find_subtree_root(struct ocfs2_extent_tree *et,
  			    struct ocfs2_path *left,
  			    struct ocfs2_path *right)

  {
  	int i = 0;
  
  	/*
  	 * Check that the caller passed in two paths from the same tree.
  	 */
  	BUG_ON(path_root_bh(left) != path_root_bh(right));
  
  	do {
  		i++;
  
  		/*
  		 * The caller didn't pass two adjacent paths.
  		 */
  		mlog_bug_on_msg(i > left->p_tree_depth,

  				"Owner %llu, left depth %u, right depth %u
  "

  				"left leaf blk %llu, right leaf blk %llu
  ",

  				(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  				left->p_tree_depth, right->p_tree_depth,

  				(unsigned long long)path_leaf_bh(left)->b_blocknr,
  				(unsigned long long)path_leaf_bh(right)->b_blocknr);
  	} while (left->p_node[i].bh->b_blocknr ==
  		 right->p_node[i].bh->b_blocknr);
  
  	return i - 1;
  }
  
  typedef void (path_insert_t)(void *, struct buffer_head *);
  
  /*
   * Traverse a btree path in search of cpos, starting at root_el.
   *
   * This code can be called with a cpos larger than the tree, in which
   * case it will return the rightmost path.
   */

  static int __ocfs2_find_path(struct ocfs2_caching_info *ci,

  			     struct ocfs2_extent_list *root_el, u32 cpos,
  			     path_insert_t *func, void *data)
  {
  	int i, ret = 0;
  	u32 range;
  	u64 blkno;
  	struct buffer_head *bh = NULL;
  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_rec *rec;

  
  	el = root_el;
  	while (el->l_tree_depth) {
  		if (le16_to_cpu(el->l_next_free_rec) == 0) {

  			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
  				    "Owner %llu has empty extent list at "

  				    "depth %u
  ",

  				    (unsigned long long)ocfs2_metadata_cache_owner(ci),

  				    le16_to_cpu(el->l_tree_depth));
  			ret = -EROFS;
  			goto out;
  
  		}
  
  		for(i = 0; i < le16_to_cpu(el->l_next_free_rec) - 1; i++) {
  			rec = &el->l_recs[i];
  
  			/*
  			 * In the case that cpos is off the allocation
  			 * tree, this should just wind up returning the
  			 * rightmost record.
  			 */
  			range = le32_to_cpu(rec->e_cpos) +

  				ocfs2_rec_clusters(el, rec);

  			if (cpos >= le32_to_cpu(rec->e_cpos) && cpos < range)
  			    break;
  		}
  
  		blkno = le64_to_cpu(el->l_recs[i].e_blkno);
  		if (blkno == 0) {

  			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
  				    "Owner %llu has bad blkno in extent list "

  				    "at depth %u (index %d)
  ",

  				    (unsigned long long)ocfs2_metadata_cache_owner(ci),

  				    le16_to_cpu(el->l_tree_depth), i);
  			ret = -EROFS;
  			goto out;
  		}
  
  		brelse(bh);
  		bh = NULL;

  		ret = ocfs2_read_extent_block(ci, blkno, &bh);

  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		eb = (struct ocfs2_extent_block *) bh->b_data;
  		el = &eb->h_list;

  
  		if (le16_to_cpu(el->l_next_free_rec) >
  		    le16_to_cpu(el->l_count)) {

  			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
  				    "Owner %llu has bad count in extent list "

  				    "at block %llu (next free=%u, count=%u)
  ",

  				    (unsigned long long)ocfs2_metadata_cache_owner(ci),

  				    (unsigned long long)bh->b_blocknr,
  				    le16_to_cpu(el->l_next_free_rec),
  				    le16_to_cpu(el->l_count));
  			ret = -EROFS;
  			goto out;
  		}
  
  		if (func)
  			func(data, bh);
  	}
  
  out:
  	/*
  	 * Catch any trailing bh that the loop didn't handle.
  	 */
  	brelse(bh);
  
  	return ret;
  }
  
  /*
   * Given an initialized path (that is, it has a valid root extent
   * list), this function will traverse the btree in search of the path
   * which would contain cpos.
   *
   * The path traveled is recorded in the path structure.
   *
   * Note that this will not do any comparisons on leaf node extent
   * records, so it will work fine in the case that we just added a tree
   * branch.
   */
  struct find_path_data {
  	int index;
  	struct ocfs2_path *path;
  };
  static void find_path_ins(void *data, struct buffer_head *bh)
  {
  	struct find_path_data *fp = data;
  
  	get_bh(bh);
  	ocfs2_path_insert_eb(fp->path, fp->index, bh);
  	fp->index++;
  }

  int ocfs2_find_path(struct ocfs2_caching_info *ci,
  		    struct ocfs2_path *path, u32 cpos)

  {
  	struct find_path_data data;
  
  	data.index = 1;
  	data.path = path;

  	return __ocfs2_find_path(ci, path_root_el(path), cpos,

  				 find_path_ins, &data);
  }
  
  static void find_leaf_ins(void *data, struct buffer_head *bh)
  {
  	struct ocfs2_extent_block *eb =(struct ocfs2_extent_block *)bh->b_data;
  	struct ocfs2_extent_list *el = &eb->h_list;
  	struct buffer_head **ret = data;
  
  	/* We want to retain only the leaf block. */
  	if (le16_to_cpu(el->l_tree_depth) == 0) {
  		get_bh(bh);
  		*ret = bh;
  	}
  }
  /*
   * Find the leaf block in the tree which would contain cpos. No
   * checking of the actual leaf is done.
   *
   * Some paths want to call this instead of allocating a path structure
   * and calling ocfs2_find_path().
   *
   * This function doesn't handle non btree extent lists.
   */

  int ocfs2_find_leaf(struct ocfs2_caching_info *ci,
  		    struct ocfs2_extent_list *root_el, u32 cpos,
  		    struct buffer_head **leaf_bh)

  {
  	int ret;
  	struct buffer_head *bh = NULL;

  	ret = __ocfs2_find_path(ci, root_el, cpos, find_leaf_ins, &bh);

  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	*leaf_bh = bh;
  out:
  	return ret;
  }
  
  /*
   * Adjust the adjacent records (left_rec, right_rec) involved in a rotation.
   *
   * Basically, we've moved stuff around at the bottom of the tree and
   * we need to fix up the extent records above the changes to reflect
   * the new changes.
   *
   * left_rec: the record on the left.
   * left_child_el: is the child list pointed to by left_rec
   * right_rec: the record to the right of left_rec
   * right_child_el: is the child list pointed to by right_rec
   *
   * By definition, this only works on interior nodes.
   */
  static void ocfs2_adjust_adjacent_records(struct ocfs2_extent_rec *left_rec,
  				  struct ocfs2_extent_list *left_child_el,
  				  struct ocfs2_extent_rec *right_rec,
  				  struct ocfs2_extent_list *right_child_el)
  {
  	u32 left_clusters, right_end;
  
  	/*
  	 * Interior nodes never have holes. Their cpos is the cpos of
  	 * the leftmost record in their child list. Their cluster
  	 * count covers the full theoretical range of their child list
  	 * - the range between their cpos and the cpos of the record
  	 * immediately to their right.
  	 */
  	left_clusters = le32_to_cpu(right_child_el->l_recs[0].e_cpos);

  	if (!ocfs2_rec_clusters(right_child_el, &right_child_el->l_recs[0])) {
  		BUG_ON(right_child_el->l_tree_depth);

  		BUG_ON(le16_to_cpu(right_child_el->l_next_free_rec) <= 1);
  		left_clusters = le32_to_cpu(right_child_el->l_recs[1].e_cpos);
  	}

  	left_clusters -= le32_to_cpu(left_rec->e_cpos);

  	left_rec->e_int_clusters = cpu_to_le32(left_clusters);

  
  	/*
  	 * Calculate the rightmost cluster count boundary before

  	 * moving cpos - we will need to adjust clusters after

  	 * updating e_cpos to keep the same highest cluster count.
  	 */
  	right_end = le32_to_cpu(right_rec->e_cpos);

  	right_end += le32_to_cpu(right_rec->e_int_clusters);

  
  	right_rec->e_cpos = left_rec->e_cpos;
  	le32_add_cpu(&right_rec->e_cpos, left_clusters);
  
  	right_end -= le32_to_cpu(right_rec->e_cpos);

  	right_rec->e_int_clusters = cpu_to_le32(right_end);

  }
  
  /*
   * Adjust the adjacent root node records involved in a
   * rotation. left_el_blkno is passed in as a key so that we can easily
   * find it's index in the root list.
   */
  static void ocfs2_adjust_root_records(struct ocfs2_extent_list *root_el,
  				      struct ocfs2_extent_list *left_el,
  				      struct ocfs2_extent_list *right_el,
  				      u64 left_el_blkno)
  {
  	int i;
  
  	BUG_ON(le16_to_cpu(root_el->l_tree_depth) <=
  	       le16_to_cpu(left_el->l_tree_depth));
  
  	for(i = 0; i < le16_to_cpu(root_el->l_next_free_rec) - 1; i++) {
  		if (le64_to_cpu(root_el->l_recs[i].e_blkno) == left_el_blkno)
  			break;
  	}
  
  	/*
  	 * The path walking code should have never returned a root and
  	 * two paths which are not adjacent.
  	 */
  	BUG_ON(i >= (le16_to_cpu(root_el->l_next_free_rec) - 1));
  
  	ocfs2_adjust_adjacent_records(&root_el->l_recs[i], left_el,
  				      &root_el->l_recs[i + 1], right_el);
  }
  
  /*
   * We've changed a leaf block (in right_path) and need to reflect that
   * change back up the subtree.
   *
   * This happens in multiple places:
   *   - When we've moved an extent record from the left path leaf to the right
   *     path leaf to make room for an empty extent in the left path leaf.
   *   - When our insert into the right path leaf is at the leftmost edge
   *     and requires an update of the path immediately to it's left. This
   *     can occur at the end of some types of rotation and appending inserts.

   *   - When we've adjusted the last extent record in the left path leaf and the
   *     1st extent record in the right path leaf during cross extent block merge.

   */

  static void ocfs2_complete_edge_insert(handle_t *handle,

  				       struct ocfs2_path *left_path,
  				       struct ocfs2_path *right_path,
  				       int subtree_index)
  {

  	int i, idx;

  	struct ocfs2_extent_list *el, *left_el, *right_el;
  	struct ocfs2_extent_rec *left_rec, *right_rec;
  	struct buffer_head *root_bh = left_path->p_node[subtree_index].bh;
  
  	/*
  	 * Update the counts and position values within all the
  	 * interior nodes to reflect the leaf rotation we just did.
  	 *
  	 * The root node is handled below the loop.
  	 *
  	 * We begin the loop with right_el and left_el pointing to the
  	 * leaf lists and work our way up.
  	 *
  	 * NOTE: within this loop, left_el and right_el always refer
  	 * to the *child* lists.
  	 */
  	left_el = path_leaf_el(left_path);
  	right_el = path_leaf_el(right_path);
  	for(i = left_path->p_tree_depth - 1; i > subtree_index; i--) {

  		trace_ocfs2_complete_edge_insert(i);

  
  		/*
  		 * One nice property of knowing that all of these
  		 * nodes are below the root is that we only deal with
  		 * the leftmost right node record and the rightmost
  		 * left node record.
  		 */
  		el = left_path->p_node[i].el;
  		idx = le16_to_cpu(left_el->l_next_free_rec) - 1;
  		left_rec = &el->l_recs[idx];
  
  		el = right_path->p_node[i].el;
  		right_rec = &el->l_recs[0];
  
  		ocfs2_adjust_adjacent_records(left_rec, left_el, right_rec,
  					      right_el);

  		ocfs2_journal_dirty(handle, left_path->p_node[i].bh);
  		ocfs2_journal_dirty(handle, right_path->p_node[i].bh);

  
  		/*
  		 * Setup our list pointers now so that the current
  		 * parents become children in the next iteration.
  		 */
  		left_el = left_path->p_node[i].el;
  		right_el = right_path->p_node[i].el;
  	}
  
  	/*
  	 * At the root node, adjust the two adjacent records which
  	 * begin our path to the leaves.
  	 */
  
  	el = left_path->p_node[subtree_index].el;
  	left_el = left_path->p_node[subtree_index + 1].el;
  	right_el = right_path->p_node[subtree_index + 1].el;
  
  	ocfs2_adjust_root_records(el, left_el, right_el,
  				  left_path->p_node[subtree_index + 1].bh->b_blocknr);
  
  	root_bh = left_path->p_node[subtree_index].bh;

  	ocfs2_journal_dirty(handle, root_bh);

  }

  static int ocfs2_rotate_subtree_right(handle_t *handle,
  				      struct ocfs2_extent_tree *et,

  				      struct ocfs2_path *left_path,
  				      struct ocfs2_path *right_path,
  				      int subtree_index)
  {
  	int ret, i;
  	struct buffer_head *right_leaf_bh;
  	struct buffer_head *left_leaf_bh = NULL;
  	struct buffer_head *root_bh;
  	struct ocfs2_extent_list *right_el, *left_el;
  	struct ocfs2_extent_rec move_rec;
  
  	left_leaf_bh = path_leaf_bh(left_path);
  	left_el = path_leaf_el(left_path);
  
  	if (left_el->l_next_free_rec != left_el->l_count) {

  		ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),

  			    "Inode %llu has non-full interior leaf node %llu"
  			    "(next free = %u)",

  			    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),

  			    (unsigned long long)left_leaf_bh->b_blocknr,
  			    le16_to_cpu(left_el->l_next_free_rec));
  		return -EROFS;
  	}
  
  	/*
  	 * This extent block may already have an empty record, so we
  	 * return early if so.
  	 */
  	if (ocfs2_is_empty_extent(&left_el->l_recs[0]))
  		return 0;
  
  	root_bh = left_path->p_node[subtree_index].bh;
  	BUG_ON(root_bh != right_path->p_node[subtree_index].bh);

  	ret = ocfs2_path_bh_journal_access(handle, et->et_ci, right_path,

  					   subtree_index);

  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	for(i = subtree_index + 1; i < path_num_items(right_path); i++) {

  		ret = ocfs2_path_bh_journal_access(handle, et->et_ci,

  						   right_path, i);

  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}

  		ret = ocfs2_path_bh_journal_access(handle, et->et_ci,

  						   left_path, i);

  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	right_leaf_bh = path_leaf_bh(right_path);
  	right_el = path_leaf_el(right_path);
  
  	/* This is a code error, not a disk corruption. */
  	mlog_bug_on_msg(!right_el->l_next_free_rec, "Inode %llu: Rotate fails "
  			"because rightmost leaf block %llu is empty
  ",

  			(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),

  			(unsigned long long)right_leaf_bh->b_blocknr);
  
  	ocfs2_create_empty_extent(right_el);

  	ocfs2_journal_dirty(handle, right_leaf_bh);

  
  	/* Do the copy now. */
  	i = le16_to_cpu(left_el->l_next_free_rec) - 1;
  	move_rec = left_el->l_recs[i];
  	right_el->l_recs[0] = move_rec;
  
  	/*
  	 * Clear out the record we just copied and shift everything
  	 * over, leaving an empty extent in the left leaf.
  	 *
  	 * We temporarily subtract from next_free_rec so that the
  	 * shift will lose the tail record (which is now defunct).
  	 */
  	le16_add_cpu(&left_el->l_next_free_rec, -1);
  	ocfs2_shift_records_right(left_el);
  	memset(&left_el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
  	le16_add_cpu(&left_el->l_next_free_rec, 1);

  	ocfs2_journal_dirty(handle, left_leaf_bh);

  	ocfs2_complete_edge_insert(handle, left_path, right_path,
  				   subtree_index);

  
  out:
  	return ret;
  }
  
  /*
   * Given a full path, determine what cpos value would return us a path
   * containing the leaf immediately to the left of the current one.
   *
   * Will return zero if the path passed in is already the leftmost path.
   */

  int ocfs2_find_cpos_for_left_leaf(struct super_block *sb,
  				  struct ocfs2_path *path, u32 *cpos)

  {
  	int i, j, ret = 0;
  	u64 blkno;
  	struct ocfs2_extent_list *el;

  	BUG_ON(path->p_tree_depth == 0);

  	*cpos = 0;
  
  	blkno = path_leaf_bh(path)->b_blocknr;
  
  	/* Start at the tree node just above the leaf and work our way up. */
  	i = path->p_tree_depth - 1;
  	while (i >= 0) {
  		el = path->p_node[i].el;
  
  		/*
  		 * Find the extent record just before the one in our
  		 * path.
  		 */
  		for(j = 0; j < le16_to_cpu(el->l_next_free_rec); j++) {
  			if (le64_to_cpu(el->l_recs[j].e_blkno) == blkno) {
  				if (j == 0) {
  					if (i == 0) {
  						/*
  						 * We've determined that the
  						 * path specified is already
  						 * the leftmost one - return a
  						 * cpos of zero.
  						 */
  						goto out;
  					}
  					/*
  					 * The leftmost record points to our
  					 * leaf - we need to travel up the
  					 * tree one level.
  					 */
  					goto next_node;
  				}
  
  				*cpos = le32_to_cpu(el->l_recs[j - 1].e_cpos);

  				*cpos = *cpos + ocfs2_rec_clusters(el,
  							   &el->l_recs[j - 1]);
  				*cpos = *cpos - 1;

  				goto out;
  			}
  		}
  
  		/*
  		 * If we got here, we never found a valid node where
  		 * the tree indicated one should be.
  		 */
  		ocfs2_error(sb,
  			    "Invalid extent tree at extent block %llu
  ",
  			    (unsigned long long)blkno);
  		ret = -EROFS;
  		goto out;
  
  next_node:
  		blkno = path->p_node[i].bh->b_blocknr;
  		i--;
  	}
  
  out:
  	return ret;
  }

  /*
   * Extend the transaction by enough credits to complete the rotation,
   * and still leave at least the original number of credits allocated
   * to this transaction.
   */

  static int ocfs2_extend_rotate_transaction(handle_t *handle, int subtree_depth,

  					   int op_credits,

  					   struct ocfs2_path *path)
  {

  	int ret = 0;

  	int credits = (path->p_tree_depth - subtree_depth) * 2 + 1 + op_credits;

  	if (handle->h_buffer_credits < credits)

  		ret = ocfs2_extend_trans(handle,
  					 credits - handle->h_buffer_credits);

  	return ret;

  }
  
  /*
   * Trap the case where we're inserting into the theoretical range past
   * the _actual_ left leaf range. Otherwise, we'll rotate a record
   * whose cpos is less than ours into the right leaf.
   *
   * It's only necessary to look at the rightmost record of the left
   * leaf because the logic that calls us should ensure that the
   * theoretical ranges in the path components above the leaves are
   * correct.
   */
  static int ocfs2_rotate_requires_path_adjustment(struct ocfs2_path *left_path,
  						 u32 insert_cpos)
  {
  	struct ocfs2_extent_list *left_el;
  	struct ocfs2_extent_rec *rec;
  	int next_free;
  
  	left_el = path_leaf_el(left_path);
  	next_free = le16_to_cpu(left_el->l_next_free_rec);
  	rec = &left_el->l_recs[next_free - 1];
  
  	if (insert_cpos > le32_to_cpu(rec->e_cpos))
  		return 1;
  	return 0;
  }

  static int ocfs2_leftmost_rec_contains(struct ocfs2_extent_list *el, u32 cpos)
  {
  	int next_free = le16_to_cpu(el->l_next_free_rec);
  	unsigned int range;
  	struct ocfs2_extent_rec *rec;
  
  	if (next_free == 0)
  		return 0;
  
  	rec = &el->l_recs[0];
  	if (ocfs2_is_empty_extent(rec)) {
  		/* Empty list. */
  		if (next_free == 1)
  			return 0;
  		rec = &el->l_recs[1];
  	}
  
  	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
  	if (cpos >= le32_to_cpu(rec->e_cpos) && cpos < range)
  		return 1;
  	return 0;
  }

  /*
   * Rotate all the records in a btree right one record, starting at insert_cpos.
   *
   * The path to the rightmost leaf should be passed in.
   *
   * The array is assumed to be large enough to hold an entire path (tree depth).
   *

   * Upon successful return from this function:

   *
   * - The 'right_path' array will contain a path to the leaf block
   *   whose range contains e_cpos.
   * - That leaf block will have a single empty extent in list index 0.
   * - In the case that the rotation requires a post-insert update,
   *   *ret_left_path will contain a valid path which can be passed to
   *   ocfs2_insert_path().
   */

  static int ocfs2_rotate_tree_right(handle_t *handle,

  				   struct ocfs2_extent_tree *et,

  				   enum ocfs2_split_type split,

  				   u32 insert_cpos,
  				   struct ocfs2_path *right_path,
  				   struct ocfs2_path **ret_left_path)
  {

  	int ret, start, orig_credits = handle->h_buffer_credits;

  	u32 cpos;
  	struct ocfs2_path *left_path = NULL;

  	struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);

  
  	*ret_left_path = NULL;

  	left_path = ocfs2_new_path_from_path(right_path);

  	if (!left_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}

  	ret = ocfs2_find_cpos_for_left_leaf(sb, right_path, &cpos);

  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}

  	trace_ocfs2_rotate_tree_right(
  		(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  		insert_cpos, cpos);

  
  	/*
  	 * What we want to do here is:
  	 *
  	 * 1) Start with the rightmost path.
  	 *
  	 * 2) Determine a path to the leaf block directly to the left
  	 *    of that leaf.
  	 *
  	 * 3) Determine the 'subtree root' - the lowest level tree node
  	 *    which contains a path to both leaves.
  	 *
  	 * 4) Rotate the subtree.
  	 *
  	 * 5) Find the next subtree by considering the left path to be
  	 *    the new right path.
  	 *
  	 * The check at the top of this while loop also accepts
  	 * insert_cpos == cpos because cpos is only a _theoretical_
  	 * value to get us the left path - insert_cpos might very well
  	 * be filling that hole.
  	 *
  	 * Stop at a cpos of '0' because we either started at the
  	 * leftmost branch (i.e., a tree with one branch and a
  	 * rotation inside of it), or we've gone as far as we can in
  	 * rotating subtrees.
  	 */
  	while (cpos && insert_cpos <= cpos) {

  		trace_ocfs2_rotate_tree_right(
  			(unsigned long long)
  			ocfs2_metadata_cache_owner(et->et_ci),
  			insert_cpos, cpos);

  		ret = ocfs2_find_path(et->et_ci, left_path, cpos);

  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		mlog_bug_on_msg(path_leaf_bh(left_path) ==
  				path_leaf_bh(right_path),

  				"Owner %llu: error during insert of %u "

  				"(left path cpos %u) results in two identical "
  				"paths ending at %llu
  ",

  				(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  				insert_cpos, cpos,

  				(unsigned long long)
  				path_leaf_bh(left_path)->b_blocknr);

  		if (split == SPLIT_NONE &&
  		    ocfs2_rotate_requires_path_adjustment(left_path,

  							  insert_cpos)) {

  
  			/*
  			 * We've rotated the tree as much as we
  			 * should. The rest is up to
  			 * ocfs2_insert_path() to complete, after the
  			 * record insertion. We indicate this
  			 * situation by returning the left path.
  			 *
  			 * The reason we don't adjust the records here
  			 * before the record insert is that an error
  			 * later might break the rule where a parent
  			 * record e_cpos will reflect the actual
  			 * e_cpos of the 1st nonempty record of the
  			 * child list.
  			 */
  			*ret_left_path = left_path;
  			goto out_ret_path;
  		}

  		start = ocfs2_find_subtree_root(et, left_path, right_path);

  		trace_ocfs2_rotate_subtree(start,
  			(unsigned long long)
  			right_path->p_node[start].bh->b_blocknr,
  			right_path->p_tree_depth);

  
  		ret = ocfs2_extend_rotate_transaction(handle, start,

  						      orig_credits, right_path);

  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}

  		ret = ocfs2_rotate_subtree_right(handle, et, left_path,

  						 right_path, start);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}

  		if (split != SPLIT_NONE &&
  		    ocfs2_leftmost_rec_contains(path_leaf_el(right_path),
  						insert_cpos)) {
  			/*
  			 * A rotate moves the rightmost left leaf
  			 * record over to the leftmost right leaf
  			 * slot. If we're doing an extent split
  			 * instead of a real insert, then we have to
  			 * check that the extent to be split wasn't
  			 * just moved over. If it was, then we can
  			 * exit here, passing left_path back -
  			 * ocfs2_split_extent() is smart enough to
  			 * search both leaves.
  			 */
  			*ret_left_path = left_path;
  			goto out_ret_path;
  		}

  		/*
  		 * There is no need to re-read the next right path
  		 * as we know that it'll be our current left
  		 * path. Optimize by copying values instead.
  		 */
  		ocfs2_mv_path(right_path, left_path);

  		ret = ocfs2_find_cpos_for_left_leaf(sb, right_path, &cpos);

  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  out:
  	ocfs2_free_path(left_path);
  
  out_ret_path:
  	return ret;
  }

  static int ocfs2_update_edge_lengths(handle_t *handle,
  				     struct ocfs2_extent_tree *et,

  				     int subtree_index, struct ocfs2_path *path)

  {

  	int i, idx, ret;

  	struct ocfs2_extent_rec *rec;