text: /* -*- 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\n",
  			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\n",
  		     (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 = -ENOMEM;
  				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[le16_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:\n"
  			"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\n"
  				"left leaf blk %llu, right leaf blk %llu\n",
  				(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\n",
  				    (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)\n",
  				    (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)\n",
  				    (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\n",
  			(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\n",
  			    (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\n",
  				(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;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_block *eb;
  	u32 range;
  
  	/*
  	 * In normal tree rotation process, we will never touch the
  	 * tree branch above subtree_index and ocfs2_extend_rotate_transaction
  	 * doesn't reserve the credits for them either.
  	 *
  	 * But we do have a special case here which will update the rightmost
  	 * records for all the bh in the path.
  	 * So we have to allocate extra credits and access them.
  	 */
  	ret = ocfs2_extend_trans(handle, subtree_index);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_journal_access_path(et->et_ci, handle, path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/* Path should always be rightmost. */
  	eb = (struct ocfs2_extent_block *)path_leaf_bh(path)->b_data;
  	BUG_ON(eb->h_next_leaf_blk != 0ULL);
  
  	el = &eb->h_list;
  	BUG_ON(le16_to_cpu(el->l_next_free_rec) == 0);
  	idx = le16_to_cpu(el->l_next_free_rec) - 1;
  	rec = &el->l_recs[idx];
  	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
  
  	for (i = 0; i < path->p_tree_depth; i++) {
  		el = path->p_node[i].el;
  		idx = le16_to_cpu(el->l_next_free_rec) - 1;
  		rec = &el->l_recs[idx];
  
  		rec->e_int_clusters = cpu_to_le32(range);
  		le32_add_cpu(&rec->e_int_clusters, -le32_to_cpu(rec->e_cpos));
  
  		ocfs2_journal_dirty(handle, path->p_node[i].bh);
  	}
  out:
  	return ret;
  }
  
  static void ocfs2_unlink_path(handle_t *handle,
  			      struct ocfs2_extent_tree *et,
  			      struct ocfs2_cached_dealloc_ctxt *dealloc,
  			      struct ocfs2_path *path, int unlink_start)
  {
  	int ret, i;
  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list *el;
  	struct buffer_head *bh;
  
  	for(i = unlink_start; i < path_num_items(path); i++) {
  		bh = path->p_node[i].bh;
  
  		eb = (struct ocfs2_extent_block *)bh->b_data;
  		/*
  		 * Not all nodes might have had their final count
  		 * decremented by the caller - handle this here.
  		 */
  		el = &eb->h_list;
  		if (le16_to_cpu(el->l_next_free_rec) > 1) {
  			mlog(ML_ERROR,
  			     "Inode %llu, attempted to remove extent block "
  			     "%llu with %u records\n",
  			     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  			     (unsigned long long)le64_to_cpu(eb->h_blkno),
  			     le16_to_cpu(el->l_next_free_rec));
  
  			ocfs2_journal_dirty(handle, bh);
  			ocfs2_remove_from_cache(et->et_ci, bh);
  			continue;
  		}
  
  		el->l_next_free_rec = 0;
  		memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
  
  		ocfs2_journal_dirty(handle, bh);
  
  		ret = ocfs2_cache_extent_block_free(dealloc, eb);
  		if (ret)
  			mlog_errno(ret);
  
  		ocfs2_remove_from_cache(et->et_ci, bh);
  	}
  }
  
  static void ocfs2_unlink_subtree(handle_t *handle,
  				 struct ocfs2_extent_tree *et,
  				 struct ocfs2_path *left_path,
  				 struct ocfs2_path *right_path,
  				 int subtree_index,
  				 struct ocfs2_cached_dealloc_ctxt *dealloc)
  {
  	int i;
  	struct buffer_head *root_bh = left_path->p_node[subtree_index].bh;
  	struct ocfs2_extent_list *root_el = left_path->p_node[subtree_index].el;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_block *eb;
  
  	el = path_leaf_el(left_path);
  
  	eb = (struct ocfs2_extent_block *)right_path->p_node[subtree_index + 1].bh->b_data;
  
  	for(i = 1; i < le16_to_cpu(root_el->l_next_free_rec); i++)
  		if (root_el->l_recs[i].e_blkno == eb->h_blkno)
  			break;
  
  	BUG_ON(i >= le16_to_cpu(root_el->l_next_free_rec));
  
  	memset(&root_el->l_recs[i], 0, sizeof(struct ocfs2_extent_rec));
  	le16_add_cpu(&root_el->l_next_free_rec, -1);
  
  	eb = (struct ocfs2_extent_block *)path_leaf_bh(left_path)->b_data;
  	eb->h_next_leaf_blk = 0;
  
  	ocfs2_journal_dirty(handle, root_bh);
  	ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
  
  	ocfs2_unlink_path(handle, et, dealloc, right_path,
  			  subtree_index + 1);
  }
  
  static int ocfs2_rotate_subtree_left(handle_t *handle,
  				     struct ocfs2_extent_tree *et,
  				     struct ocfs2_path *left_path,
  				     struct ocfs2_path *right_path,
  				     int subtree_index,
  				     struct ocfs2_cached_dealloc_ctxt *dealloc,
  				     int *deleted)
  {
  	int ret, i, del_right_subtree = 0, right_has_empty = 0;
  	struct buffer_head *root_bh, *et_root_bh = path_root_bh(right_path);
  	struct ocfs2_extent_list *right_leaf_el, *left_leaf_el;
  	struct ocfs2_extent_block *eb;
  
  	*deleted = 0;
  
  	right_leaf_el = path_leaf_el(right_path);
  	left_leaf_el = path_leaf_el(left_path);
  	root_bh = left_path->p_node[subtree_index].bh;
  	BUG_ON(root_bh != right_path->p_node[subtree_index].bh);
  
  	if (!ocfs2_is_empty_extent(&left_leaf_el->l_recs[0]))
  		return 0;
  
  	eb = (struct ocfs2_extent_block *)path_leaf_bh(right_path)->b_data;
  	if (ocfs2_is_empty_extent(&right_leaf_el->l_recs[0])) {
  		/*
  		 * It's legal for us to proceed if the right leaf is
  		 * the rightmost one and it has an empty extent. There
  		 * are two cases to handle - whether the leaf will be
  		 * empty after removal or not. If the leaf isn't empty
  		 * then just remove the empty extent up front. The
  		 * next block will handle empty leaves by flagging
  		 * them for unlink.
  		 *
  		 * Non rightmost leaves will throw -EAGAIN and the
  		 * caller can manually move the subtree and retry.
  		 */
  
  		if (eb->h_next_leaf_blk != 0ULL)
  			return -EAGAIN;
  
  		if (le16_to_cpu(right_leaf_el->l_next_free_rec) > 1) {
  			ret = ocfs2_journal_access_eb(handle, et->et_ci,
  						      path_leaf_bh(right_path),
  						      OCFS2_JOURNAL_ACCESS_WRITE);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  
  			ocfs2_remove_empty_extent(right_leaf_el);
  		} else
  			right_has_empty = 1;
  	}
  
  	if (eb->h_next_leaf_blk == 0ULL &&
  	    le16_to_cpu(right_leaf_el->l_next_free_rec) == 1) {
  		/*
  		 * We have to update i_last_eb_blk during the meta
  		 * data delete.
  		 */
  		ret = ocfs2_et_root_journal_access(handle, et,
  						   OCFS2_JOURNAL_ACCESS_WRITE);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		del_right_subtree = 1;
  	}
  
  	/*
  	 * Getting here with an empty extent in the right path implies
  	 * that it's the rightmost path and will be deleted.
  	 */
  	BUG_ON(right_has_empty && !del_right_subtree);
  
  	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;
  		}
  	}
  
  	if (!right_has_empty) {
  		/*
  		 * Only do this if we're moving a real
  		 * record. Otherwise, the action is delayed until
  		 * after removal of the right path in which case we
  		 * can do a simple shift to remove the empty extent.
  		 */
  		ocfs2_rotate_leaf(left_leaf_el, &right_leaf_el->l_recs[0]);
  		memset(&right_leaf_el->l_recs[0], 0,
  		       sizeof(struct ocfs2_extent_rec));
  	}
  	if (eb->h_next_leaf_blk == 0ULL) {
  		/*
  		 * Move recs over to get rid of empty extent, decrease
  		 * next_free. This is allowed to remove the last
  		 * extent in our leaf (setting l_next_free_rec to
  		 * zero) - the delete code below won't care.
  		 */
  		ocfs2_remove_empty_extent(right_leaf_el);
  	}
  
  	ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
  	ocfs2_journal_dirty(handle, path_leaf_bh(right_path));
  
  	if (del_right_subtree) {
  		ocfs2_unlink_subtree(handle, et, left_path, right_path,
  				     subtree_index, dealloc);
  		ret = ocfs2_update_edge_lengths(handle, et, subtree_index,
  						left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		eb = (struct ocfs2_extent_block *)path_leaf_bh(left_path)->b_data;
  		ocfs2_et_set_last_eb_blk(et, le64_to_cpu(eb->h_blkno));
  
  		/*
  		 * Removal of the extent in the left leaf was skipped
  		 * above so we could delete the right path
  		 * 1st.
  		 */
  		if (right_has_empty)
  			ocfs2_remove_empty_extent(left_leaf_el);
  
  		ocfs2_journal_dirty(handle, et_root_bh);
  
  		*deleted = 1;
  	} else
  		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 right of the current one.
   *
   * Will return zero if the path passed in is already the rightmost path.
   *
   * This looks similar, but is subtly different to
   * ocfs2_find_cpos_for_left_leaf().
   */
  int ocfs2_find_cpos_for_right_leaf(struct super_block *sb,
  				   struct ocfs2_path *path, u32 *cpos)
  {
  	int i, j, ret = 0;
  	u64 blkno;
  	struct ocfs2_extent_list *el;
  
  	*cpos = 0;
  
  	if (path->p_tree_depth == 0)
  		return 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) {
  		int next_free;
  
  		el = path->p_node[i].el;
  
  		/*
  		 * Find the extent record just after the one in our
  		 * path.
  		 */
  		next_free = le16_to_cpu(el->l_next_free_rec);
  		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 == (next_free - 1)) {
  					if (i == 0) {
  						/*
  						 * We've determined that the
  						 * path specified is already
  						 * the rightmost one - return a
  						 * cpos of zero.
  						 */
  						goto out;
  					}
  					/*
  					 * The rightmost 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);
  				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\n",
  			    (unsigned long long)blkno);
  		ret = -EROFS;
  		goto out;
  
  next_node:
  		blkno = path->p_node[i].bh->b_blocknr;
  		i--;
  	}
  
  out:
  	return ret;
  }
  
  static int ocfs2_rotate_rightmost_leaf_left(handle_t *handle,
  					    struct ocfs2_extent_tree *et,
  					    struct ocfs2_path *path)
  {
  	int ret;
  	struct buffer_head *bh = path_leaf_bh(path);
  	struct ocfs2_extent_list *el = path_leaf_el(path);
  
  	if (!ocfs2_is_empty_extent(&el->l_recs[0]))
  		return 0;
  
  	ret = ocfs2_path_bh_journal_access(handle, et->et_ci, path,
  					   path_num_items(path) - 1);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ocfs2_remove_empty_extent(el);
  	ocfs2_journal_dirty(handle, bh);
  
  out:
  	return ret;
  }
  
  static int __ocfs2_rotate_tree_left(handle_t *handle,
  				    struct ocfs2_extent_tree *et,
  				    int orig_credits,
  				    struct ocfs2_path *path,
  				    struct ocfs2_cached_dealloc_ctxt *dealloc,
  				    struct ocfs2_path **empty_extent_path)
  {
  	int ret, subtree_root, deleted;
  	u32 right_cpos;
  	struct ocfs2_path *left_path = NULL;
  	struct ocfs2_path *right_path = NULL;
  	struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
  
  	BUG_ON(!ocfs2_is_empty_extent(&(path_leaf_el(path)->l_recs[0])));
  
  	*empty_extent_path = NULL;
  
  	ret = ocfs2_find_cpos_for_right_leaf(sb, path, &right_cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	left_path = ocfs2_new_path_from_path(path);
  	if (!left_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ocfs2_cp_path(left_path, path);
  
  	right_path = ocfs2_new_path_from_path(path);
  	if (!right_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	while (right_cpos) {
  		ret = ocfs2_find_path(et->et_ci, right_path, right_cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		subtree_root = ocfs2_find_subtree_root(et, left_path,
  						       right_path);
  
  		trace_ocfs2_rotate_subtree(subtree_root,
  		     (unsigned long long)
  		     right_path->p_node[subtree_root].bh->b_blocknr,
  		     right_path->p_tree_depth);
  
  		ret = ocfs2_extend_rotate_transaction(handle, subtree_root,
  						      orig_credits, left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		/*
  		 * Caller might still want to make changes to the
  		 * tree root, so re-add it to the journal here.
  		 */
  		ret = ocfs2_path_bh_journal_access(handle, et->et_ci,
  						   left_path, 0);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_rotate_subtree_left(handle, et, left_path,
  						right_path, subtree_root,
  						dealloc, &deleted);
  		if (ret == -EAGAIN) {
  			/*
  			 * The rotation has to temporarily stop due to
  			 * the right subtree having an empty
  			 * extent. Pass it back to the caller for a
  			 * fixup.
  			 */
  			*empty_extent_path = right_path;
  			right_path = NULL;
  			goto out;
  		}
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		/*
  		 * The subtree rotate might have removed records on
  		 * the rightmost edge. If so, then rotation is
  		 * complete.
  		 */
  		if (deleted)
  			break;
  
  		ocfs2_mv_path(left_path, right_path);
  
  		ret = ocfs2_find_cpos_for_right_leaf(sb, left_path,
  						     &right_cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  out:
  	ocfs2_free_path(right_path);
  	ocfs2_free_path(left_path);
  
  	return ret;
  }
  
  static int ocfs2_remove_rightmost_path(handle_t *handle,
  				struct ocfs2_extent_tree *et,
  				struct ocfs2_path *path,
  				struct ocfs2_cached_dealloc_ctxt *dealloc)
  {
  	int ret, subtree_index;
  	u32 cpos;
  	struct ocfs2_path *left_path = NULL;
  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list *el;
  
  
  	ret = ocfs2_et_sanity_check(et);
  	if (ret)
  		goto out;
  	/*
  	 * There's two ways we handle this depending on
  	 * whether path is the only existing one.
  	 */
  	ret = ocfs2_extend_rotate_transaction(handle, 0,
  					      handle->h_buffer_credits,
  					      path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_journal_access_path(et->et_ci, handle, path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_find_cpos_for_left_leaf(ocfs2_metadata_cache_get_super(et->et_ci),
  					    path, &cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (cpos) {
  		/*
  		 * We have a path to the left of this one - it needs
  		 * an update too.
  		 */
  		left_path = ocfs2_new_path_from_path(path);
  		if (!left_path) {
  			ret = -ENOMEM;
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_find_path(et->et_ci, left_path, cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_journal_access_path(et->et_ci, handle, left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		subtree_index = ocfs2_find_subtree_root(et, left_path, path);
  
  		ocfs2_unlink_subtree(handle, et, left_path, path,
  				     subtree_index, dealloc);
  		ret = ocfs2_update_edge_lengths(handle, et, subtree_index,
  						left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		eb = (struct ocfs2_extent_block *)path_leaf_bh(left_path)->b_data;
  		ocfs2_et_set_last_eb_blk(et, le64_to_cpu(eb->h_blkno));
  	} else {
  		/*
  		 * 'path' is also the leftmost path which
  		 * means it must be the only one. This gets
  		 * handled differently because we want to
  		 * revert the root back to having extents
  		 * in-line.
  		 */
  		ocfs2_unlink_path(handle, et, dealloc, path, 1);
  
  		el = et->et_root_el;
  		el->l_tree_depth = 0;
  		el->l_next_free_rec = 0;
  		memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
  
  		ocfs2_et_set_last_eb_blk(et, 0);
  	}
  
  	ocfs2_journal_dirty(handle, path_root_bh(path));
  
  out:
  	ocfs2_free_path(left_path);
  	return ret;
  }
  
  /*
   * Left rotation of btree records.
   *
   * In many ways, this is (unsurprisingly) the opposite of right
   * rotation. We start at some non-rightmost path containing an empty
   * extent in the leaf block. The code works its way to the rightmost
   * path by rotating records to the left in every subtree.
   *
   * This is used by any code which reduces the number of extent records
   * in a leaf. After removal, an empty record should be placed in the
   * leftmost list position.
   *
   * This won't handle a length update of the rightmost path records if
   * the rightmost tree leaf record is removed so the caller is
   * responsible for detecting and correcting that.
   */
  static int ocfs2_rotate_tree_left(handle_t *handle,
  				  struct ocfs2_extent_tree *et,
  				  struct ocfs2_path *path,
  				  struct ocfs2_cached_dealloc_ctxt *dealloc)
  {
  	int ret, orig_credits = handle->h_buffer_credits;
  	struct ocfs2_path *tmp_path = NULL, *restart_path = NULL;
  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list *el;
  
  	el = path_leaf_el(path);
  	if (!ocfs2_is_empty_extent(&el->l_recs[0]))
  		return 0;
  
  	if (path->p_tree_depth == 0) {
  rightmost_no_delete:
  		/*
  		 * Inline extents. This is trivially handled, so do
  		 * it up front.
  		 */
  		ret = ocfs2_rotate_rightmost_leaf_left(handle, et, path);
  		if (ret)
  			mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * Handle rightmost branch now. There's several cases:
  	 *  1) simple rotation leaving records in there. That's trivial.
  	 *  2) rotation requiring a branch delete - there's no more
  	 *     records left. Two cases of this:
  	 *     a) There are branches to the left.
  	 *     b) This is also the leftmost (the only) branch.
  	 *
  	 *  1) is handled via ocfs2_rotate_rightmost_leaf_left()
  	 *  2a) we need the left branch so that we can update it with the unlink
  	 *  2b) we need to bring the root back to inline extents.
  	 */
  
  	eb = (struct ocfs2_extent_block *)path_leaf_bh(path)->b_data;
  	el = &eb->h_list;
  	if (eb->h_next_leaf_blk == 0) {
  		/*
  		 * This gets a bit tricky if we're going to delete the
  		 * rightmost path. Get the other cases out of the way
  		 * 1st.
  		 */
  		if (le16_to_cpu(el->l_next_free_rec) > 1)
  			goto rightmost_no_delete;
  
  		if (le16_to_cpu(el->l_next_free_rec) == 0) {
  			ret = -EIO;
  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  				    "Owner %llu has empty extent block at %llu",
  				    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  				    (unsigned long long)le64_to_cpu(eb->h_blkno));
  			goto out;
  		}
  
  		/*
  		 * XXX: The caller can not trust "path" any more after
  		 * this as it will have been deleted. What do we do?
  		 *
  		 * In theory the rotate-for-merge code will never get
  		 * here because it'll always ask for a rotate in a
  		 * nonempty list.
  		 */
  
  		ret = ocfs2_remove_rightmost_path(handle, et, path,
  						  dealloc);
  		if (ret)
  			mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * Now we can loop, remembering the path we get from -EAGAIN
  	 * and restarting from there.
  	 */
  try_rotate:
  	ret = __ocfs2_rotate_tree_left(handle, et, orig_credits, path,
  				       dealloc, &restart_path);
  	if (ret && ret != -EAGAIN) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	while (ret == -EAGAIN) {
  		tmp_path = restart_path;
  		restart_path = NULL;
  
  		ret = __ocfs2_rotate_tree_left(handle, et, orig_credits,
  					       tmp_path, dealloc,
  					       &restart_path);
  		if (ret && ret != -EAGAIN) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ocfs2_free_path(tmp_path);
  		tmp_path = NULL;
  
  		if (ret == 0)
  			goto try_rotate;
  	}
  
  out:
  	ocfs2_free_path(tmp_path);
  	ocfs2_free_path(restart_path);
  	return ret;
  }
  
  static void ocfs2_cleanup_merge(struct ocfs2_extent_list *el,
  				int index)
  {
  	struct ocfs2_extent_rec *rec = &el->l_recs[index];
  	unsigned int size;
  
  	if (rec->e_leaf_clusters == 0) {
  		/*
  		 * We consumed all of the merged-from record. An empty
  		 * extent cannot exist anywhere but the 1st array
  		 * position, so move things over if the merged-from
  		 * record doesn't occupy that position.
  		 *
  		 * This creates a new empty extent so the caller
  		 * should be smart enough to have removed any existing
  		 * ones.
  		 */
  		if (index > 0) {
  			BUG_ON(ocfs2_is_empty_extent(&el->l_recs[0]));
  			size = index * sizeof(struct ocfs2_extent_rec);
  			memmove(&el->l_recs[1], &el->l_recs[0], size);
  		}
  
  		/*
  		 * Always memset - the caller doesn't check whether it
  		 * created an empty extent, so there could be junk in
  		 * the other fields.
  		 */
  		memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
  	}
  }
  
  static int ocfs2_get_right_path(struct ocfs2_extent_tree *et,
  				struct ocfs2_path *left_path,
  				struct ocfs2_path **ret_right_path)
  {
  	int ret;
  	u32 right_cpos;
  	struct ocfs2_path *right_path = NULL;
  	struct ocfs2_extent_list *left_el;
  
  	*ret_right_path = NULL;
  
  	/* This function shouldn't be called for non-trees. */
  	BUG_ON(left_path->p_tree_depth == 0);
  
  	left_el = path_leaf_el(left_path);
  	BUG_ON(left_el->l_next_free_rec != left_el->l_count);
  
  	ret = ocfs2_find_cpos_for_right_leaf(ocfs2_metadata_cache_get_super(et->et_ci),
  					     left_path, &right_cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/* This function shouldn't be called for the rightmost leaf. */
  	BUG_ON(right_cpos == 0);
  
  	right_path = ocfs2_new_path_from_path(left_path);
  	if (!right_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_find_path(et->et_ci, right_path, right_cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	*ret_right_path = right_path;
  out:
  	if (ret)
  		ocfs2_free_path(right_path);
  	return ret;
  }
  
  /*
   * Remove split_rec clusters from the record at index and merge them
   * onto the beginning of the record "next" to it.
   * For index < l_count - 1, the next means the extent rec at index + 1.
   * For index == l_count - 1, the "next" means the 1st extent rec of the
   * next extent block.
   */
  static int ocfs2_merge_rec_right(struct ocfs2_path *left_path,
  				 handle_t *handle,
  				 struct ocfs2_extent_tree *et,
  				 struct ocfs2_extent_rec *split_rec,
  				 int index)
  {
  	int ret, next_free, i;
  	unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
  	struct ocfs2_extent_rec *left_rec;
  	struct ocfs2_extent_rec *right_rec;
  	struct ocfs2_extent_list *right_el;
  	struct ocfs2_path *right_path = NULL;
  	int subtree_index = 0;
  	struct ocfs2_extent_list *el = path_leaf_el(left_path);
  	struct buffer_head *bh = path_leaf_bh(left_path);
  	struct buffer_head *root_bh = NULL;
  
  	BUG_ON(index >= le16_to_cpu(el->l_next_free_rec));
  	left_rec = &el->l_recs[index];
  
  	if (index == le16_to_cpu(el->l_next_free_rec) - 1 &&
  	    le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count)) {
  		/* we meet with a cross extent block merge. */
  		ret = ocfs2_get_right_path(et, left_path, &right_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		right_el = path_leaf_el(right_path);
  		next_free = le16_to_cpu(right_el->l_next_free_rec);
  		BUG_ON(next_free <= 0);
  		right_rec = &right_el->l_recs[0];
  		if (ocfs2_is_empty_extent(right_rec)) {
  			BUG_ON(next_free <= 1);
  			right_rec = &right_el->l_recs[1];
  		}
  
  		BUG_ON(le32_to_cpu(left_rec->e_cpos) +
  		       le16_to_cpu(left_rec->e_leaf_clusters) !=
  		       le32_to_cpu(right_rec->e_cpos));
  
  		subtree_index = ocfs2_find_subtree_root(et, left_path,
  							right_path);
  
  		ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
  						      handle->h_buffer_credits,
  						      right_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		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;
  			}
  		}
  
  	} else {
  		BUG_ON(index == le16_to_cpu(el->l_next_free_rec) - 1);
  		right_rec = &el->l_recs[index + 1];
  	}
  
  	ret = ocfs2_path_bh_journal_access(handle, et->et_ci, left_path,
  					   path_num_items(left_path) - 1);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	le16_add_cpu(&left_rec->e_leaf_clusters, -split_clusters);
  
  	le32_add_cpu(&right_rec->e_cpos, -split_clusters);
  	le64_add_cpu(&right_rec->e_blkno,
  		     -ocfs2_clusters_to_blocks(ocfs2_metadata_cache_get_super(et->et_ci),
  					       split_clusters));
  	le16_add_cpu(&right_rec->e_leaf_clusters, split_clusters);
  
  	ocfs2_cleanup_merge(el, index);
  
  	ocfs2_journal_dirty(handle, bh);
  	if (right_path) {
  		ocfs2_journal_dirty(handle, path_leaf_bh(right_path));
  		ocfs2_complete_edge_insert(handle, left_path, right_path,
  					   subtree_index);
  	}
  out:
  	if (right_path)
  		ocfs2_free_path(right_path);
  	return ret;
  }
  
  static int ocfs2_get_left_path(struct ocfs2_extent_tree *et,
  			       struct ocfs2_path *right_path,
  			       struct ocfs2_path **ret_left_path)
  {
  	int ret;
  	u32 left_cpos;
  	struct ocfs2_path *left_path = NULL;
  
  	*ret_left_path = NULL;
  
  	/* This function shouldn't be called for non-trees. */
  	BUG_ON(right_path->p_tree_depth == 0);
  
  	ret = ocfs2_find_cpos_for_left_leaf(ocfs2_metadata_cache_get_super(et->et_ci),
  					    right_path, &left_cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/* This function shouldn't be called for the leftmost leaf. */
  	BUG_ON(left_cpos == 0);
  
  	left_path = ocfs2_new_path_from_path(right_path);
  	if (!left_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_find_path(et->et_ci, left_path, left_cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	*ret_left_path = left_path;
  out:
  	if (ret)
  		ocfs2_free_path(left_path);
  	return ret;
  }
  
  /*
   * Remove split_rec clusters from the record at index and merge them
   * onto the tail of the record "before" it.
   * For index > 0, the "before" means the extent rec at index - 1.
   *
   * For index == 0, the "before" means the last record of the previous
   * extent block. And there is also a situation that we may need to
   * remove the rightmost leaf extent block in the right_path and change
   * the right path to indicate the new rightmost path.
   */
  static int ocfs2_merge_rec_left(struct ocfs2_path *right_path,
  				handle_t *handle,
  				struct ocfs2_extent_tree *et,
  				struct ocfs2_extent_rec *split_rec,
  				struct ocfs2_cached_dealloc_ctxt *dealloc,
  				int index)
  {
  	int ret, i, subtree_index = 0, has_empty_extent = 0;
  	unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
  	struct ocfs2_extent_rec *left_rec;
  	struct ocfs2_extent_rec *right_rec;
  	struct ocfs2_extent_list *el = path_leaf_el(right_path);
  	struct buffer_head *bh = path_leaf_bh(right_path);
  	struct buffer_head *root_bh = NULL;
  	struct ocfs2_path *left_path = NULL;
  	struct ocfs2_extent_list *left_el;
  
  	BUG_ON(index < 0);
  
  	right_rec = &el->l_recs[index];
  	if (index == 0) {
  		/* we meet with a cross extent block merge. */
  		ret = ocfs2_get_left_path(et, right_path, &left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		left_el = path_leaf_el(left_path);
  		BUG_ON(le16_to_cpu(left_el->l_next_free_rec) !=
  		       le16_to_cpu(left_el->l_count));
  
  		left_rec = &left_el->l_recs[
  				le16_to_cpu(left_el->l_next_free_rec) - 1];
  		BUG_ON(le32_to_cpu(left_rec->e_cpos) +
  		       le16_to_cpu(left_rec->e_leaf_clusters) !=
  		       le32_to_cpu(split_rec->e_cpos));
  
  		subtree_index = ocfs2_find_subtree_root(et, left_path,
  							right_path);
  
  		ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
  						      handle->h_buffer_credits,
  						      left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		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;
  			}
  		}
  	} else {
  		left_rec = &el->l_recs[index - 1];
  		if (ocfs2_is_empty_extent(&el->l_recs[0]))
  			has_empty_extent = 1;
  	}
  
  	ret = ocfs2_path_bh_journal_access(handle, et->et_ci, right_path,
  					   path_num_items(right_path) - 1);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (has_empty_extent && index == 1) {
  		/*
  		 * The easy case - we can just plop the record right in.
  		 */
  		*left_rec = *split_rec;
  
  		has_empty_extent = 0;
  	} else
  		le16_add_cpu(&left_rec->e_leaf_clusters, split_clusters);
  
  	le32_add_cpu(&right_rec->e_cpos, split_clusters);
  	le64_add_cpu(&right_rec->e_blkno,
  		     ocfs2_clusters_to_blocks(ocfs2_metadata_cache_get_super(et->et_ci),
  					      split_clusters));
  	le16_add_cpu(&right_rec->e_leaf_clusters, -split_clusters);
  
  	ocfs2_cleanup_merge(el, index);
  
  	ocfs2_journal_dirty(handle, bh);
  	if (left_path) {
  		ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
  
  		/*
  		 * In the situation that the right_rec is empty and the extent
  		 * block is empty also,  ocfs2_complete_edge_insert can't handle
  		 * it and we need to delete the right extent block.
  		 */
  		if (le16_to_cpu(right_rec->e_leaf_clusters) == 0 &&
  		    le16_to_cpu(el->l_next_free_rec) == 1) {
  
  			ret = ocfs2_remove_rightmost_path(handle, et,
  							  right_path,
  							  dealloc);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  
  			/* Now the rightmost extent block has been deleted.
  			 * So we use the new rightmost path.
  			 */
  			ocfs2_mv_path(right_path, left_path);
  			left_path = NULL;
  		} else
  			ocfs2_complete_edge_insert(handle, left_path,
  						   right_path, subtree_index);
  	}
  out:
  	if (left_path)
  		ocfs2_free_path(left_path);
  	return ret;
  }
  
  static int ocfs2_try_to_merge_extent(handle_t *handle,
  				     struct ocfs2_extent_tree *et,
  				     struct ocfs2_path *path,
  				     int split_index,
  				     struct ocfs2_extent_rec *split_rec,
  				     struct ocfs2_cached_dealloc_ctxt *dealloc,
  				     struct ocfs2_merge_ctxt *ctxt)
  {
  	int ret = 0;
  	struct ocfs2_extent_list *el = path_leaf_el(path);
  	struct ocfs2_extent_rec *rec = &el->l_recs[split_index];
  
  	BUG_ON(ctxt->c_contig_type == CONTIG_NONE);
  
  	if (ctxt->c_split_covers_rec && ctxt->c_has_empty_extent) {
  		/*
  		 * The merge code will need to create an empty
  		 * extent to take the place of the newly
  		 * emptied slot. Remove any pre-existing empty
  		 * extents - having more than one in a leaf is
  		 * illegal.
  		 */
  		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  		split_index--;
  		rec = &el->l_recs[split_index];
  	}
  
  	if (ctxt->c_contig_type == CONTIG_LEFTRIGHT) {
  		/*
  		 * Left-right contig implies this.
  		 */
  		BUG_ON(!ctxt->c_split_covers_rec);
  
  		/*
  		 * Since the leftright insert always covers the entire
  		 * extent, this call will delete the insert record
  		 * entirely, resulting in an empty extent record added to
  		 * the extent block.
  		 *
  		 * Since the adding of an empty extent shifts
  		 * everything back to the right, there's no need to
  		 * update split_index here.
  		 *
  		 * When the split_index is zero, we need to merge it to the
  		 * prevoius extent block. It is more efficient and easier
  		 * if we do merge_right first and merge_left later.
  		 */
  		ret = ocfs2_merge_rec_right(path, handle, et, split_rec,
  					    split_index);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		/*
  		 * We can only get this from logic error above.
  		 */
  		BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));
  
  		/* The merge left us with an empty extent, remove it. */
  		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		rec = &el->l_recs[split_index];
  
  		/*
  		 * Note that we don't pass split_rec here on purpose -
  		 * we've merged it into the rec already.
  		 */
  		ret = ocfs2_merge_rec_left(path, handle, et, rec,
  					   dealloc, split_index);
  
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
  		/*
  		 * Error from this last rotate is not critical, so
  		 * print but don't bubble it up.
  		 */
  		if (ret)
  			mlog_errno(ret);
  		ret = 0;
  	} else {
  		/*
  		 * Merge a record to the left or right.
  		 *
  		 * 'contig_type' is relative to the existing record,
  		 * so for example, if we're "right contig", it's to
  		 * the record on the left (hence the left merge).
  		 */
  		if (ctxt->c_contig_type == CONTIG_RIGHT) {
  			ret = ocfs2_merge_rec_left(path, handle, et,
  						   split_rec, dealloc,
  						   split_index);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  		} else {
  			ret = ocfs2_merge_rec_right(path, handle,
  						    et, split_rec,
  						    split_index);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  		}
  
  		if (ctxt->c_split_covers_rec) {
  			/*
  			 * The merge may have left an empty extent in
  			 * our leaf. Try to rotate it away.
  			 */
  			ret = ocfs2_rotate_tree_left(handle, et, path,
  						     dealloc);
  			if (ret)
  				mlog_errno(ret);
  			ret = 0;
  		}
  	}
  
  out:
  	return ret;
  }
  
  static void ocfs2_subtract_from_rec(struct super_block *sb,
  				    enum ocfs2_split_type split,
  				    struct ocfs2_extent_rec *rec,
  				    struct ocfs2_extent_rec *split_rec)
  {
  	u64 len_blocks;
  
  	len_blocks = ocfs2_clusters_to_blocks(sb,
  				le16_to_cpu(split_rec->e_leaf_clusters));
  
  	if (split == SPLIT_LEFT) {
  		/*
  		 * Region is on the left edge of the existing
  		 * record.
  		 */
  		le32_add_cpu(&rec->e_cpos,
  			     le16_to_cpu(split_rec->e_leaf_clusters));
  		le64_add_cpu(&rec->e_blkno, len_blocks);
  		le16_add_cpu(&rec->e_leaf_clusters,
  			     -le16_to_cpu(split_rec->e_leaf_clusters));
  	} else {
  		/*
  		 * Region is on the right edge of the existing
  		 * record.
  		 */
  		le16_add_cpu(&rec->e_leaf_clusters,
  			     -le16_to_cpu(split_rec->e_leaf_clusters));
  	}
  }
  
  /*
   * Do the final bits of extent record insertion at the target leaf
   * list. If this leaf is part of an allocation tree, it is assumed
   * that the tree above has been prepared.
   */
  static void ocfs2_insert_at_leaf(struct ocfs2_extent_tree *et,
  				 struct ocfs2_extent_rec *insert_rec,
  				 struct ocfs2_extent_list *el,
  				 struct ocfs2_insert_type *insert)
  {
  	int i = insert->ins_contig_index;
  	unsigned int range;
  	struct ocfs2_extent_rec *rec;
  
  	BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);
  
  	if (insert->ins_split != SPLIT_NONE) {
  		i = ocfs2_search_extent_list(el, le32_to_cpu(insert_rec->e_cpos));
  		BUG_ON(i == -1);
  		rec = &el->l_recs[i];
  		ocfs2_subtract_from_rec(ocfs2_metadata_cache_get_super(et->et_ci),
  					insert->ins_split, rec,
  					insert_rec);
  		goto rotate;
  	}
  
  	/*
  	 * Contiguous insert - either left or right.
  	 */
  	if (insert->ins_contig != CONTIG_NONE) {
  		rec = &el->l_recs[i];
  		if (insert->ins_contig == CONTIG_LEFT) {
  			rec->e_blkno = insert_rec->e_blkno;
  			rec->e_cpos = insert_rec->e_cpos;
  		}
  		le16_add_cpu(&rec->e_leaf_clusters,
  			     le16_to_cpu(insert_rec->e_leaf_clusters));
  		return;
  	}
  
  	/*
  	 * Handle insert into an empty leaf.
  	 */
  	if (le16_to_cpu(el->l_next_free_rec) == 0 ||
  	    ((le16_to_cpu(el->l_next_free_rec) == 1) &&
  	     ocfs2_is_empty_extent(&el->l_recs[0]))) {
  		el->l_recs[0] = *insert_rec;
  		el->l_next_free_rec = cpu_to_le16(1);
  		return;
  	}
  
  	/*
  	 * Appending insert.
  	 */
  	if (insert->ins_appending == APPEND_TAIL) {
  		i = le16_to_cpu(el->l_next_free_rec) - 1;
  		rec = &el->l_recs[i];
  		range = le32_to_cpu(rec->e_cpos)
  			+ le16_to_cpu(rec->e_leaf_clusters);
  		BUG_ON(le32_to_cpu(insert_rec->e_cpos) < range);
  
  		mlog_bug_on_msg(le16_to_cpu(el->l_next_free_rec) >=
  				le16_to_cpu(el->l_count),
  				"owner %llu, depth %u, count %u, next free %u, "
  				"rec.cpos %u, rec.clusters %u, "
  				"insert.cpos %u, insert.clusters %u\n",
  				ocfs2_metadata_cache_owner(et->et_ci),
  				le16_to_cpu(el->l_tree_depth),
  				le16_to_cpu(el->l_count),
  				le16_to_cpu(el->l_next_free_rec),
  				le32_to_cpu(el->l_recs[i].e_cpos),
  				le16_to_cpu(el->l_recs[i].e_leaf_clusters),
  				le32_to_cpu(insert_rec->e_cpos),
  				le16_to_cpu(insert_rec->e_leaf_clusters));
  		i++;
  		el->l_recs[i] = *insert_rec;
  		le16_add_cpu(&el->l_next_free_rec, 1);
  		return;
  	}
  
  rotate:
  	/*
  	 * Ok, we have to rotate.
  	 *
  	 * At this point, it is safe to assume that inserting into an
  	 * empty leaf and appending to a leaf have both been handled
  	 * above.
  	 *
  	 * This leaf needs to have space, either by the empty 1st
  	 * extent record, or by virtue of an l_next_rec < l_count.
  	 */
  	ocfs2_rotate_leaf(el, insert_rec);
  }
  
  static void ocfs2_adjust_rightmost_records(handle_t *handle,
  					   struct ocfs2_extent_tree *et,
  					   struct ocfs2_path *path,
  					   struct ocfs2_extent_rec *insert_rec)
  {
  	int ret, i, next_free;
  	struct buffer_head *bh;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_rec *rec;
  
  	/*
  	 * Update everything except the leaf block.
  	 */
  	for (i = 0; i < path->p_tree_depth; i++) {
  		bh = path->p_node[i].bh;
  		el = path->p_node[i].el;
  
  		next_free = le16_to_cpu(el->l_next_free_rec);
  		if (next_free == 0) {
  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  				    "Owner %llu has a bad extent list",
  				    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci));
  			ret = -EIO;
  			return;
  		}
  
  		rec = &el->l_recs[next_free - 1];
  
  		rec->e_int_clusters = insert_rec->e_cpos;
  		le32_add_cpu(&rec->e_int_clusters,
  			     le16_to_cpu(insert_rec->e_leaf_clusters));
  		le32_add_cpu(&rec->e_int_clusters,
  			     -le32_to_cpu(rec->e_cpos));
  
  		ocfs2_journal_dirty(handle, bh);
  	}
  }
  
  static int ocfs2_append_rec_to_path(handle_t *handle,
  				    struct ocfs2_extent_tree *et,
  				    struct ocfs2_extent_rec *insert_rec,
  				    struct ocfs2_path *right_path,
  				    struct ocfs2_path **ret_left_path)
  {
  	int ret, next_free;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_path *left_path = NULL;
  
  	*ret_left_path = NULL;
  
  	/*
  	 * This shouldn't happen for non-trees. The extent rec cluster
  	 * count manipulation below only works for interior nodes.
  	 */
  	BUG_ON(right_path->p_tree_depth == 0);
  
  	/*
  	 * If our appending insert is at the leftmost edge of a leaf,
  	 * then we might need to update the rightmost records of the
  	 * neighboring path.
  	 */
  	el = path_leaf_el(right_path);
  	next_free = le16_to_cpu(el->l_next_free_rec);
  	if (next_free == 0 ||
  	    (next_free == 1 && ocfs2_is_empty_extent(&el->l_recs[0]))) {
  		u32 left_cpos;
  
  		ret = ocfs2_find_cpos_for_left_leaf(ocfs2_metadata_cache_get_super(et->et_ci),
  						    right_path, &left_cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		trace_ocfs2_append_rec_to_path(
  			(unsigned long long)
  			ocfs2_metadata_cache_owner(et->et_ci),
  			le32_to_cpu(insert_rec->e_cpos),
  			left_cpos);
  
  		/*
  		 * No need to worry if the append is already in the
  		 * leftmost leaf.
  		 */
  		if (left_cpos) {
  			left_path = ocfs2_new_path_from_path(right_path);
  			if (!left_path) {
  				ret = -ENOMEM;
  				mlog_errno(ret);
  				goto out;
  			}
  
  			ret = ocfs2_find_path(et->et_ci, left_path,
  					      left_cpos);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  
  			/*
  			 * ocfs2_insert_path() will pass the left_path to the
  			 * journal for us.
  			 */
  		}
  	}
  
  	ret = ocfs2_journal_access_path(et->et_ci, handle, right_path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ocfs2_adjust_rightmost_records(handle, et, right_path, insert_rec);
  
  	*ret_left_path = left_path;
  	ret = 0;
  out:
  	if (ret != 0)
  		ocfs2_free_path(left_path);
  
  	return ret;
  }
  
  static void ocfs2_split_record(struct ocfs2_extent_tree *et,
  			       struct ocfs2_path *left_path,
  			       struct ocfs2_path *right_path,
  			       struct ocfs2_extent_rec *split_rec,
  			       enum ocfs2_split_type split)
  {
  	int index;
  	u32 cpos = le32_to_cpu(split_rec->e_cpos);
  	struct ocfs2_extent_list *left_el = NULL, *right_el, *insert_el, *el;
  	struct ocfs2_extent_rec *rec, *tmprec;
  
  	right_el = path_leaf_el(right_path);
  	if (left_path)
  		left_el = path_leaf_el(left_path);
  
  	el = right_el;
  	insert_el = right_el;
  	index = ocfs2_search_extent_list(el, cpos);
  	if (index != -1) {
  		if (index == 0 && left_path) {
  			BUG_ON(ocfs2_is_empty_extent(&el->l_recs[0]));
  
  			/*
  			 * This typically means that the record
  			 * started in the left path but moved to the
  			 * right as a result of rotation. We either
  			 * move the existing record to the left, or we
  			 * do the later insert there.
  			 *
  			 * In this case, the left path should always
  			 * exist as the rotate code will have passed
  			 * it back for a post-insert update.
  			 */
  
  			if (split == SPLIT_LEFT) {
  				/*
  				 * It's a left split. Since we know
  				 * that the rotate code gave us an
  				 * empty extent in the left path, we
  				 * can just do the insert there.
  				 */
  				insert_el = left_el;
  			} else {
  				/*
  				 * Right split - we have to move the
  				 * existing record over to the left
  				 * leaf. The insert will be into the
  				 * newly created empty extent in the
  				 * right leaf.
  				 */
  				tmprec = &right_el->l_recs[index];
  				ocfs2_rotate_leaf(left_el, tmprec);
  				el = left_el;
  
  				memset(tmprec, 0, sizeof(*tmprec));
  				index = ocfs2_search_extent_list(left_el, cpos);
  				BUG_ON(index == -1);
  			}
  		}
  	} else {
  		BUG_ON(!left_path);
  		BUG_ON(!ocfs2_is_empty_extent(&left_el->l_recs[0]));
  		/*
  		 * Left path is easy - we can just allow the insert to
  		 * happen.
  		 */
  		el = left_el;
  		insert_el = left_el;
  		index = ocfs2_search_extent_list(el, cpos);
  		BUG_ON(index == -1);
  	}
  
  	rec = &el->l_recs[index];
  	ocfs2_subtract_from_rec(ocfs2_metadata_cache_get_super(et->et_ci),
  				split, rec, split_rec);
  	ocfs2_rotate_leaf(insert_el, split_rec);
  }
  
  /*
   * This function only does inserts on an allocation b-tree. For tree
   * depth = 0, ocfs2_insert_at_leaf() is called directly.
   *
   * right_path is the path we want to do the actual insert
   * in. left_path should only be passed in if we need to update that
   * portion of the tree after an edge insert.
   */
  static int ocfs2_insert_path(handle_t *handle,
  			     struct ocfs2_extent_tree *et,
  			     struct ocfs2_path *left_path,
  			     struct ocfs2_path *right_path,
  			     struct ocfs2_extent_rec *insert_rec,
  			     struct ocfs2_insert_type *insert)
  {
  	int ret, subtree_index;
  	struct buffer_head *leaf_bh = path_leaf_bh(right_path);
  
  	if (left_path) {
  		/*
  		 * There's a chance that left_path got passed back to
  		 * us without being accounted for in the
  		 * journal. Extend our transaction here to be sure we
  		 * can change those blocks.
  		 */
  		ret = ocfs2_extend_trans(handle, left_path->p_tree_depth);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_journal_access_path(et->et_ci, handle, left_path);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	/*
  	 * Pass both paths to the journal. The majority of inserts
  	 * will be touching all components anyway.
  	 */
  	ret = ocfs2_journal_access_path(et->et_ci, handle, right_path);
  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (insert->ins_split != SPLIT_NONE) {
  		/*
  		 * We could call ocfs2_insert_at_leaf() for some types
  		 * of splits, but it's easier to just let one separate
  		 * function sort it all out.
  		 */
  		ocfs2_split_record(et, left_path, right_path,
  				   insert_rec, insert->ins_split);
  
  		/*
  		 * Split might have modified either leaf and we don't
  		 * have a guarantee that the later edge insert will
  		 * dirty this for us.
  		 */
  		if (left_path)
  			ocfs2_journal_dirty(handle,
  					    path_leaf_bh(left_path));
  	} else
  		ocfs2_insert_at_leaf(et, insert_rec, path_leaf_el(right_path),
  				     insert);
  
  	ocfs2_journal_dirty(handle, leaf_bh);
  
  	if (left_path) {
  		/*
  		 * The rotate code has indicated that we need to fix
  		 * up portions of the tree after the insert.
  		 *
  		 * XXX: Should we extend the transaction here?
  		 */
  		subtree_index = ocfs2_find_subtree_root(et, left_path,
  							right_path);
  		ocfs2_complete_edge_insert(handle, left_path, right_path,
  					   subtree_index);
  	}
  
  	ret = 0;
  out:
  	return ret;
  }
  
  static int ocfs2_do_insert_extent(handle_t *handle,
  				  struct ocfs2_extent_tree *et,
  				  struct ocfs2_extent_rec *insert_rec,
  				  struct ocfs2_insert_type *type)
  {
  	int ret, rotate = 0;
  	u32 cpos;
  	struct ocfs2_path *right_path = NULL;
  	struct ocfs2_path *left_path = NULL;
  	struct ocfs2_extent_list *el;
  
  	el = et->et_root_el;
  
  	ret = ocfs2_et_root_journal_access(handle, et,
  					   OCFS2_JOURNAL_ACCESS_WRITE);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (le16_to_cpu(el->l_tree_depth) == 0) {
  		ocfs2_insert_at_leaf(et, insert_rec, el, type);
  		goto out_update_clusters;
  	}
  
  	right_path = ocfs2_new_path_from_et(et);
  	if (!right_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * Determine the path to start with. Rotations need the
  	 * rightmost path, everything else can go directly to the
  	 * target leaf.
  	 */
  	cpos = le32_to_cpu(insert_rec->e_cpos);
  	if (type->ins_appending == APPEND_NONE &&
  	    type->ins_contig == CONTIG_NONE) {
  		rotate = 1;
  		cpos = UINT_MAX;
  	}
  
  	ret = ocfs2_find_path(et->et_ci, right_path, cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * Rotations and appends need special treatment - they modify
  	 * parts of the tree's above them.
  	 *
  	 * Both might pass back a path immediate to the left of the
  	 * one being inserted to. This will be cause
  	 * ocfs2_insert_path() to modify the rightmost records of
  	 * left_path to account for an edge insert.
  	 *
  	 * XXX: When modifying this code, keep in mind that an insert
  	 * can wind up skipping both of these two special cases...
  	 */
  	if (rotate) {
  		ret = ocfs2_rotate_tree_right(handle, et, type->ins_split,
  					      le32_to_cpu(insert_rec->e_cpos),
  					      right_path, &left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		/*
  		 * ocfs2_rotate_tree_right() might have extended the
  		 * transaction without re-journaling our tree root.
  		 */
  		ret = ocfs2_et_root_journal_access(handle, et,
  						   OCFS2_JOURNAL_ACCESS_WRITE);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	} else if (type->ins_appending == APPEND_TAIL
  		   && type->ins_contig != CONTIG_LEFT) {
  		ret = ocfs2_append_rec_to_path(handle, et, insert_rec,
  					       right_path, &left_path);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	ret = ocfs2_insert_path(handle, et, left_path, right_path,
  				insert_rec, type);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  out_update_clusters:
  	if (type->ins_split == SPLIT_NONE)
  		ocfs2_et_update_clusters(et,
  					 le16_to_cpu(insert_rec->e_leaf_clusters));
  
  	ocfs2_journal_dirty(handle, et->et_root_bh);
  
  out:
  	ocfs2_free_path(left_path);
  	ocfs2_free_path(right_path);
  
  	return ret;
  }
  
  static enum ocfs2_contig_type
  ocfs2_figure_merge_contig_type(struct ocfs2_extent_tree *et,
  			       struct ocfs2_path *path,
  			       struct ocfs2_extent_list *el, int index,
  			       struct ocfs2_extent_rec *split_rec)
  {
  	int status;
  	enum ocfs2_contig_type ret = CONTIG_NONE;
  	u32 left_cpos, right_cpos;
  	struct ocfs2_extent_rec *rec = NULL;
  	struct ocfs2_extent_list *new_el;
  	struct ocfs2_path *left_path = NULL, *right_path = NULL;
  	struct buffer_head *bh;
  	struct ocfs2_extent_block *eb;
  	struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
  
  	if (index > 0) {
  		rec = &el->l_recs[index - 1];
  	} else if (path->p_tree_depth > 0) {
  		status = ocfs2_find_cpos_for_left_leaf(sb, path, &left_cpos);
  		if (status)
  			goto out;
  
  		if (left_cpos != 0) {
  			left_path = ocfs2_new_path_from_path(path);
  			if (!left_path)
  				goto out;
  
  			status = ocfs2_find_path(et->et_ci, left_path,
  						 left_cpos);
  			if (status)
  				goto out;
  
  			new_el = path_leaf_el(left_path);
  
  			if (le16_to_cpu(new_el->l_next_free_rec) !=
  			    le16_to_cpu(new_el->l_count)) {
  				bh = path_leaf_bh(left_path);
  				eb = (struct ocfs2_extent_block *)bh->b_data;
  				ocfs2_error(sb,
  					    "Extent block #%llu has an "
  					    "invalid l_next_free_rec of "
  					    "%d.  It should have "
  					    "matched the l_count of %d",
  					    (unsigned long long)le64_to_cpu(eb->h_blkno),
  					    le16_to_cpu(new_el->l_next_free_rec),
  					    le16_to_cpu(new_el->l_count));
  				status = -EINVAL;
  				goto out;
  			}
  			rec = &new_el->l_recs[
  				le16_to_cpu(new_el->l_next_free_rec) - 1];
  		}
  	}
  
  	/*
  	 * We're careful to check for an empty extent record here -
  	 * the merge code will know what to do if it sees one.
  	 */
  	if (rec) {
  		if (index == 1 && ocfs2_is_empty_extent(rec)) {
  			if (split_rec->e_cpos == el->l_recs[index].e_cpos)
  				ret = CONTIG_RIGHT;
  		} else {
  			ret = ocfs2_et_extent_contig(et, rec, split_rec);
  		}
  	}
  
  	rec = NULL;
  	if (index < (le16_to_cpu(el->l_next_free_rec) - 1))
  		rec = &el->l_recs[index + 1];
  	else if (le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count) &&
  		 path->p_tree_depth > 0) {
  		status = ocfs2_find_cpos_for_right_leaf(sb, path, &right_cpos);
  		if (status)
  			goto out;
  
  		if (right_cpos == 0)
  			goto out;
  
  		right_path = ocfs2_new_path_from_path(path);
  		if (!right_path)
  			goto out;
  
  		status = ocfs2_find_path(et->et_ci, right_path, right_cpos);
  		if (status)
  			goto out;
  
  		new_el = path_leaf_el(right_path);
  		rec = &new_el->l_recs[0];
  		if (ocfs2_is_empty_extent(rec)) {
  			if (le16_to_cpu(new_el->l_next_free_rec) <= 1) {
  				bh = path_leaf_bh(right_path);
  				eb = (struct ocfs2_extent_block *)bh->b_data;
  				ocfs2_error(sb,
  					    "Extent block #%llu has an "
  					    "invalid l_next_free_rec of %d",
  					    (unsigned long long)le64_to_cpu(eb->h_blkno),
  					    le16_to_cpu(new_el->l_next_free_rec));
  				status = -EINVAL;
  				goto out;
  			}
  			rec = &new_el->l_recs[1];
  		}
  	}
  
  	if (rec) {
  		enum ocfs2_contig_type contig_type;
  
  		contig_type = ocfs2_et_extent_contig(et, rec, split_rec);
  
  		if (contig_type == CONTIG_LEFT && ret == CONTIG_RIGHT)
  			ret = CONTIG_LEFTRIGHT;
  		else if (ret == CONTIG_NONE)
  			ret = contig_type;
  	}
  
  out:
  	if (left_path)
  		ocfs2_free_path(left_path);
  	if (right_path)
  		ocfs2_free_path(right_path);
  
  	return ret;
  }
  
  static void ocfs2_figure_contig_type(struct ocfs2_extent_tree *et,
  				     struct ocfs2_insert_type *insert,
  				     struct ocfs2_extent_list *el,
  				     struct ocfs2_extent_rec *insert_rec)
  {
  	int i;
  	enum ocfs2_contig_type contig_type = CONTIG_NONE;
  
  	BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);
  
  	for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
  		contig_type = ocfs2_et_extent_contig(et, &el->l_recs[i],
  						     insert_rec);
  		if (contig_type != CONTIG_NONE) {
  			insert->ins_contig_index = i;
  			break;
  		}
  	}
  	insert->ins_contig = contig_type;
  
  	if (insert->ins_contig != CONTIG_NONE) {
  		struct ocfs2_extent_rec *rec =
  				&el->l_recs[insert->ins_contig_index];
  		unsigned int len = le16_to_cpu(rec->e_leaf_clusters) +
  				   le16_to_cpu(insert_rec->e_leaf_clusters);
  
  		/*
  		 * Caller might want us to limit the size of extents, don't
  		 * calculate contiguousness if we might exceed that limit.
  		 */
  		if (et->et_max_leaf_clusters &&
  		    (len > et->et_max_leaf_clusters))
  			insert->ins_contig = CONTIG_NONE;
  	}
  }
  
  /*
   * This should only be called against the righmost leaf extent list.
   *
   * ocfs2_figure_appending_type() will figure out whether we'll have to
   * insert at the tail of the rightmost leaf.
   *
   * This should also work against the root extent list for tree's with 0
   * depth. If we consider the root extent list to be the rightmost leaf node
   * then the logic here makes sense.
   */
  static void ocfs2_figure_appending_type(struct ocfs2_insert_type *insert,
  					struct ocfs2_extent_list *el,
  					struct ocfs2_extent_rec *insert_rec)
  {
  	int i;
  	u32 cpos = le32_to_cpu(insert_rec->e_cpos);
  	struct ocfs2_extent_rec *rec;
  
  	insert->ins_appending = APPEND_NONE;
  
  	BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);
  
  	if (!el->l_next_free_rec)
  		goto set_tail_append;
  
  	if (ocfs2_is_empty_extent(&el->l_recs[0])) {
  		/* Were all records empty? */
  		if (le16_to_cpu(el->l_next_free_rec) == 1)
  			goto set_tail_append;
  	}
  
  	i = le16_to_cpu(el->l_next_free_rec) - 1;
  	rec = &el->l_recs[i];
  
  	if (cpos >=
  	    (le32_to_cpu(rec->e_cpos) + le16_to_cpu(rec->e_leaf_clusters)))
  		goto set_tail_append;
  
  	return;
  
  set_tail_append:
  	insert->ins_appending = APPEND_TAIL;
  }
  
  /*
   * Helper function called at the beginning of an insert.
   *
   * This computes a few things that are commonly used in the process of
   * inserting into the btree:
   *   - Whether the new extent is contiguous with an existing one.
   *   - The current tree depth.
   *   - Whether the insert is an appending one.
   *   - The total # of free records in the tree.
   *
   * All of the information is stored on the ocfs2_insert_type
   * structure.
   */
  static int ocfs2_figure_insert_type(struct ocfs2_extent_tree *et,
  				    struct buffer_head **last_eb_bh,
  				    struct ocfs2_extent_rec *insert_rec,
  				    int *free_records,
  				    struct ocfs2_insert_type *insert)
  {
  	int ret;
  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_path *path = NULL;
  	struct buffer_head *bh = NULL;
  
  	insert->ins_split = SPLIT_NONE;
  
  	el = et->et_root_el;
  	insert->ins_tree_depth = le16_to_cpu(el->l_tree_depth);
  
  	if (el->l_tree_depth) {
  		/*
  		 * If we have tree depth, we read in the
  		 * rightmost extent block ahead of time as
  		 * ocfs2_figure_insert_type() and ocfs2_add_branch()
  		 * may want it later.
  		 */
  		ret = ocfs2_read_extent_block(et->et_ci,
  					      ocfs2_et_get_last_eb_blk(et),
  					      &bh);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  		eb = (struct ocfs2_extent_block *) bh->b_data;
  		el = &eb->h_list;
  	}
  
  	/*
  	 * Unless we have a contiguous insert, we'll need to know if
  	 * there is room left in our allocation tree for another
  	 * extent record.
  	 *
  	 * XXX: This test is simplistic, we can search for empty
  	 * extent records too.
  	 */
  	*free_records = le16_to_cpu(el->l_count) -
  		le16_to_cpu(el->l_next_free_rec);
  
  	if (!insert->ins_tree_depth) {
  		ocfs2_figure_contig_type(et, insert, el, insert_rec);
  		ocfs2_figure_appending_type(insert, el, insert_rec);
  		return 0;
  	}
  
  	path = ocfs2_new_path_from_et(et);
  	if (!path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * In the case that we're inserting past what the tree
  	 * currently accounts for, ocfs2_find_path() will return for
  	 * us the rightmost tree path. This is accounted for below in
  	 * the appending code.
  	 */
  	ret = ocfs2_find_path(et->et_ci, path, le32_to_cpu(insert_rec->e_cpos));
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	el = path_leaf_el(path);
  
  	/*
  	 * Now that we have the path, there's two things we want to determine:
  	 * 1) Contiguousness (also set contig_index if this is so)
  	 *
  	 * 2) Are we doing an append? We can trivially break this up
           *     into two types of appends: simple record append, or a
           *     rotate inside the tail leaf.
  	 */
  	ocfs2_figure_contig_type(et, insert, el, insert_rec);
  
  	/*
  	 * The insert code isn't quite ready to deal with all cases of
  	 * left contiguousness. Specifically, if it's an insert into
  	 * the 1st record in a leaf, it will require the adjustment of
  	 * cluster count on the last record of the path directly to it's
  	 * left. For now, just catch that case and fool the layers
  	 * above us. This works just fine for tree_depth == 0, which
  	 * is why we allow that above.
  	 */
  	if (insert->ins_contig == CONTIG_LEFT &&
  	    insert->ins_contig_index == 0)
  		insert->ins_contig = CONTIG_NONE;
  
  	/*
  	 * Ok, so we can simply compare against last_eb to figure out
  	 * whether the path doesn't exist. This will only happen in
  	 * the case that we're doing a tail append, so maybe we can
  	 * take advantage of that information somehow.
  	 */
  	if (ocfs2_et_get_last_eb_blk(et) ==
  	    path_leaf_bh(path)->b_blocknr) {
  		/*
  		 * Ok, ocfs2_find_path() returned us the rightmost
  		 * tree path. This might be an appending insert. There are
  		 * two cases:
  		 *    1) We're doing a true append at the tail:
  		 *	-This might even be off the end of the leaf
  		 *    2) We're "appending" by rotating in the tail
  		 */
  		ocfs2_figure_appending_type(insert, el, insert_rec);
  	}
  
  out:
  	ocfs2_free_path(path);
  
  	if (ret == 0)
  		*last_eb_bh = bh;
  	else
  		brelse(bh);
  	return ret;
  }
  
  /*
   * Insert an extent into a btree.
   *
   * The caller needs to update the owning btree's cluster count.
   */
  int ocfs2_insert_extent(handle_t *handle,
  			struct ocfs2_extent_tree *et,
  			u32 cpos,
  			u64 start_blk,
  			u32 new_clusters,
  			u8 flags,
  			struct ocfs2_alloc_context *meta_ac)
  {
  	int status;
  	int uninitialized_var(free_records);
  	struct buffer_head *last_eb_bh = NULL;
  	struct ocfs2_insert_type insert = {0, };
  	struct ocfs2_extent_rec rec;
  
  	trace_ocfs2_insert_extent_start(
  		(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  		cpos, new_clusters);
  
  	memset(&rec, 0, sizeof(rec));
  	rec.e_cpos = cpu_to_le32(cpos);
  	rec.e_blkno = cpu_to_le64(start_blk);
  	rec.e_leaf_clusters = cpu_to_le16(new_clusters);
  	rec.e_flags = flags;
  	status = ocfs2_et_insert_check(et, &rec);
  	if (status) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	status = ocfs2_figure_insert_type(et, &last_eb_bh, &rec,
  					  &free_records, &insert);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	trace_ocfs2_insert_extent(insert.ins_appending, insert.ins_contig,
  				  insert.ins_contig_index, free_records,
  				  insert.ins_tree_depth);
  
  	if (insert.ins_contig == CONTIG_NONE && free_records == 0) {
  		status = ocfs2_grow_tree(handle, et,
  					 &insert.ins_tree_depth, &last_eb_bh,
  					 meta_ac);
  		if (status) {
  			mlog_errno(status);
  			goto bail;
  		}
  	}
  
  	/* Finally, we can add clusters. This might rotate the tree for us. */
  	status = ocfs2_do_insert_extent(handle, et, &rec, &insert);
  	if (status < 0)
  		mlog_errno(status);
  	else
  		ocfs2_et_extent_map_insert(et, &rec);
  
  bail:
  	brelse(last_eb_bh);
  
  	return status;
  }
  
  /*
   * Allcate and add clusters into the extent b-tree.
   * The new clusters(clusters_to_add) will be inserted at logical_offset.
   * The extent b-tree's root is specified by et, and
   * it is not limited to the file storage. Any extent tree can use this
   * function if it implements the proper ocfs2_extent_tree.
   */
  int ocfs2_add_clusters_in_btree(handle_t *handle,
  				struct ocfs2_extent_tree *et,
  				u32 *logical_offset,
  				u32 clusters_to_add,
  				int mark_unwritten,
  				struct ocfs2_alloc_context *data_ac,
  				struct ocfs2_alloc_context *meta_ac,
  				enum ocfs2_alloc_restarted *reason_ret)
  {
  	int status = 0, err = 0;
  	int need_free = 0;
  	int free_extents;
  	enum ocfs2_alloc_restarted reason = RESTART_NONE;
  	u32 bit_off, num_bits;
  	u64 block;
  	u8 flags = 0;
  	struct ocfs2_super *osb =
  		OCFS2_SB(ocfs2_metadata_cache_get_super(et->et_ci));
  
  	BUG_ON(!clusters_to_add);
  
  	if (mark_unwritten)
  		flags = OCFS2_EXT_UNWRITTEN;
  
  	free_extents = ocfs2_num_free_extents(osb, et);
  	if (free_extents < 0) {
  		status = free_extents;
  		mlog_errno(status);
  		goto leave;
  	}
  
  	/* there are two cases which could cause us to EAGAIN in the
  	 * we-need-more-metadata case:
  	 * 1) we haven't reserved *any*
  	 * 2) we are so fragmented, we've needed to add metadata too
  	 *    many times. */
  	if (!free_extents && !meta_ac) {
  		err = -1;
  		status = -EAGAIN;
  		reason = RESTART_META;
  		goto leave;
  	} else if ((!free_extents)
  		   && (ocfs2_alloc_context_bits_left(meta_ac)
  		       < ocfs2_extend_meta_needed(et->et_root_el))) {
  		err = -2;
  		status = -EAGAIN;
  		reason = RESTART_META;
  		goto leave;
  	}
  
  	status = __ocfs2_claim_clusters(handle, data_ac, 1,
  					clusters_to_add, &bit_off, &num_bits);
  	if (status < 0) {
  		if (status != -ENOSPC)
  			mlog_errno(status);
  		goto leave;
  	}
  
  	BUG_ON(num_bits > clusters_to_add);
  
  	/* reserve our write early -- insert_extent may update the tree root */
  	status = ocfs2_et_root_journal_access(handle, et,
  					      OCFS2_JOURNAL_ACCESS_WRITE);
  	if (status < 0) {
  		mlog_errno(status);
  		need_free = 1;
  		goto bail;
  	}
  
  	block = ocfs2_clusters_to_blocks(osb->sb, bit_off);
  	trace_ocfs2_add_clusters_in_btree(
  	     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  	     bit_off, num_bits);
  	status = ocfs2_insert_extent(handle, et, *logical_offset, block,
  				     num_bits, flags, meta_ac);
  	if (status < 0) {
  		mlog_errno(status);
  		need_free = 1;
  		goto bail;
  	}
  
  	ocfs2_journal_dirty(handle, et->et_root_bh);
  
  	clusters_to_add -= num_bits;
  	*logical_offset += num_bits;
  
  	if (clusters_to_add) {
  		err = clusters_to_add;
  		status = -EAGAIN;
  		reason = RESTART_TRANS;
  	}
  
  bail:
  	if (need_free) {
  		if (data_ac->ac_which == OCFS2_AC_USE_LOCAL)
  			ocfs2_free_local_alloc_bits(osb, handle, data_ac,
  					bit_off, num_bits);
  		else
  			ocfs2_free_clusters(handle,
  					data_ac->ac_inode,
  					data_ac->ac_bh,
  					ocfs2_clusters_to_blocks(osb->sb, bit_off),
  					num_bits);
  	}
  
  leave:
  	if (reason_ret)
  		*reason_ret = reason;
  	trace_ocfs2_add_clusters_in_btree_ret(status, reason, err);
  	return status;
  }
  
  static void ocfs2_make_right_split_rec(struct super_block *sb,
  				       struct ocfs2_extent_rec *split_rec,
  				       u32 cpos,
  				       struct ocfs2_extent_rec *rec)
  {
  	u32 rec_cpos = le32_to_cpu(rec->e_cpos);
  	u32 rec_range = rec_cpos + le16_to_cpu(rec->e_leaf_clusters);
  
  	memset(split_rec, 0, sizeof(struct ocfs2_extent_rec));
  
  	split_rec->e_cpos = cpu_to_le32(cpos);
  	split_rec->e_leaf_clusters = cpu_to_le16(rec_range - cpos);
  
  	split_rec->e_blkno = rec->e_blkno;
  	le64_add_cpu(&split_rec->e_blkno,
  		     ocfs2_clusters_to_blocks(sb, cpos - rec_cpos));
  
  	split_rec->e_flags = rec->e_flags;
  }
  
  static int ocfs2_split_and_insert(handle_t *handle,
  				  struct ocfs2_extent_tree *et,
  				  struct ocfs2_path *path,
  				  struct buffer_head **last_eb_bh,
  				  int split_index,
  				  struct ocfs2_extent_rec *orig_split_rec,
  				  struct ocfs2_alloc_context *meta_ac)
  {
  	int ret = 0, depth;
  	unsigned int insert_range, rec_range, do_leftright = 0;
  	struct ocfs2_extent_rec tmprec;
  	struct ocfs2_extent_list *rightmost_el;
  	struct ocfs2_extent_rec rec;
  	struct ocfs2_extent_rec split_rec = *orig_split_rec;
  	struct ocfs2_insert_type insert;
  	struct ocfs2_extent_block *eb;
  
  leftright:
  	/*
  	 * Store a copy of the record on the stack - it might move
  	 * around as the tree is manipulated below.
  	 */
  	rec = path_leaf_el(path)->l_recs[split_index];
  
  	rightmost_el = et->et_root_el;
  
  	depth = le16_to_cpu(rightmost_el->l_tree_depth);
  	if (depth) {
  		BUG_ON(!(*last_eb_bh));
  		eb = (struct ocfs2_extent_block *) (*last_eb_bh)->b_data;
  		rightmost_el = &eb->h_list;
  	}
  
  	if (le16_to_cpu(rightmost_el->l_next_free_rec) ==
  	    le16_to_cpu(rightmost_el->l_count)) {
  		ret = ocfs2_grow_tree(handle, et,
  				      &depth, last_eb_bh, meta_ac);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	memset(&insert, 0, sizeof(struct ocfs2_insert_type));
  	insert.ins_appending = APPEND_NONE;
  	insert.ins_contig = CONTIG_NONE;
  	insert.ins_tree_depth = depth;
  
  	insert_range = le32_to_cpu(split_rec.e_cpos) +
  		le16_to_cpu(split_rec.e_leaf_clusters);
  	rec_range = le32_to_cpu(rec.e_cpos) +
  		le16_to_cpu(rec.e_leaf_clusters);
  
  	if (split_rec.e_cpos == rec.e_cpos) {
  		insert.ins_split = SPLIT_LEFT;
  	} else if (insert_range == rec_range) {
  		insert.ins_split = SPLIT_RIGHT;
  	} else {
  		/*
  		 * Left/right split. We fake this as a right split
  		 * first and then make a second pass as a left split.
  		 */
  		insert.ins_split = SPLIT_RIGHT;
  
  		ocfs2_make_right_split_rec(ocfs2_metadata_cache_get_super(et->et_ci),
  					   &tmprec, insert_range, &rec);
  
  		split_rec = tmprec;
  
  		BUG_ON(do_leftright);
  		do_leftright = 1;
  	}
  
  	ret = ocfs2_do_insert_extent(handle, et, &split_rec, &insert);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (do_leftright == 1) {
  		u32 cpos;
  		struct ocfs2_extent_list *el;
  
  		do_leftright++;
  		split_rec = *orig_split_rec;
  
  		ocfs2_reinit_path(path, 1);
  
  		cpos = le32_to_cpu(split_rec.e_cpos);
  		ret = ocfs2_find_path(et->et_ci, path, cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		el = path_leaf_el(path);
  		split_index = ocfs2_search_extent_list(el, cpos);
  		if (split_index == -1) {
  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  					"Owner %llu has an extent at cpos %u "
  					"which can no longer be found.\n",
  					(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  					cpos);
  			ret = -EROFS;
  			goto out;
  		}
  		goto leftright;
  	}
  out:
  
  	return ret;
  }
  
  static int ocfs2_replace_extent_rec(handle_t *handle,
  				    struct ocfs2_extent_tree *et,
  				    struct ocfs2_path *path,
  				    struct ocfs2_extent_list *el,
  				    int split_index,
  				    struct ocfs2_extent_rec *split_rec)
  {
  	int ret;
  
  	ret = ocfs2_path_bh_journal_access(handle, et->et_ci, path,
  					   path_num_items(path) - 1);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	el->l_recs[split_index] = *split_rec;
  
  	ocfs2_journal_dirty(handle, path_leaf_bh(path));
  out:
  	return ret;
  }
  
  /*
   * Split part or all of the extent record at split_index in the leaf
   * pointed to by path. Merge with the contiguous extent record if needed.
   *
   * Care is taken to handle contiguousness so as to not grow the tree.
   *
   * meta_ac is not strictly necessary - we only truly need it if growth
   * of the tree is required. All other cases will degrade into a less
   * optimal tree layout.
   *
   * last_eb_bh should be the rightmost leaf block for any extent
   * btree. Since a split may grow the tree or a merge might shrink it,
   * the caller cannot trust the contents of that buffer after this call.
   *
   * This code is optimized for readability - several passes might be
   * made over certain portions of the tree. All of those blocks will
   * have been brought into cache (and pinned via the journal), so the
   * extra overhead is not expressed in terms of disk reads.
   */
  int ocfs2_split_extent(handle_t *handle,
  		       struct ocfs2_extent_tree *et,
  		       struct ocfs2_path *path,
  		       int split_index,
  		       struct ocfs2_extent_rec *split_rec,
  		       struct ocfs2_alloc_context *meta_ac,
  		       struct ocfs2_cached_dealloc_ctxt *dealloc)
  {
  	int ret = 0;
  	struct ocfs2_extent_list *el = path_leaf_el(path);
  	struct buffer_head *last_eb_bh = NULL;
  	struct ocfs2_extent_rec *rec = &el->l_recs[split_index];
  	struct ocfs2_merge_ctxt ctxt;
  	struct ocfs2_extent_list *rightmost_el;
  
  	if (le32_to_cpu(rec->e_cpos) > le32_to_cpu(split_rec->e_cpos) ||
  	    ((le32_to_cpu(rec->e_cpos) + le16_to_cpu(rec->e_leaf_clusters)) <
  	     (le32_to_cpu(split_rec->e_cpos) + le16_to_cpu(split_rec->e_leaf_clusters)))) {
  		ret = -EIO;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ctxt.c_contig_type = ocfs2_figure_merge_contig_type(et, path, el,
  							    split_index,
  							    split_rec);
  
  	/*
  	 * The core merge / split code wants to know how much room is
  	 * left in this allocation tree, so we pass the
  	 * rightmost extent list.
  	 */
  	if (path->p_tree_depth) {
  		struct ocfs2_extent_block *eb;
  
  		ret = ocfs2_read_extent_block(et->et_ci,
  					      ocfs2_et_get_last_eb_blk(et),
  					      &last_eb_bh);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
  		rightmost_el = &eb->h_list;
  	} else
  		rightmost_el = path_root_el(path);
  
  	if (rec->e_cpos == split_rec->e_cpos &&
  	    rec->e_leaf_clusters == split_rec->e_leaf_clusters)
  		ctxt.c_split_covers_rec = 1;
  	else
  		ctxt.c_split_covers_rec = 0;
  
  	ctxt.c_has_empty_extent = ocfs2_is_empty_extent(&el->l_recs[0]);
  
  	trace_ocfs2_split_extent(split_index, ctxt.c_contig_type,
  				 ctxt.c_has_empty_extent,
  				 ctxt.c_split_covers_rec);
  
  	if (ctxt.c_contig_type == CONTIG_NONE) {
  		if (ctxt.c_split_covers_rec)
  			ret = ocfs2_replace_extent_rec(handle, et, path, el,
  						       split_index, split_rec);
  		else
  			ret = ocfs2_split_and_insert(handle, et, path,
  						     &last_eb_bh, split_index,
  						     split_rec, meta_ac);
  		if (ret)
  			mlog_errno(ret);
  	} else {
  		ret = ocfs2_try_to_merge_extent(handle, et, path,
  						split_index, split_rec,
  						dealloc, &ctxt);
  		if (ret)
  			mlog_errno(ret);
  	}
  
  out:
  	brelse(last_eb_bh);
  	return ret;
  }
  
  /*
   * Change the flags of the already-existing extent at cpos for len clusters.
   *
   * new_flags: the flags we want to set.
   * clear_flags: the flags we want to clear.
   * phys: the new physical offset we want this new extent starts from.
   *
   * If the existing extent is larger than the request, initiate a
   * split. An attempt will be made at merging with adjacent extents.
   *
   * The caller is responsible for passing down meta_ac if we'll need it.
   */
  int ocfs2_change_extent_flag(handle_t *handle,
  			     struct ocfs2_extent_tree *et,
  			     u32 cpos, u32 len, u32 phys,
  			     struct ocfs2_alloc_context *meta_ac,
  			     struct ocfs2_cached_dealloc_ctxt *dealloc,
  			     int new_flags, int clear_flags)
  {
  	int ret, index;
  	struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
  	u64 start_blkno = ocfs2_clusters_to_blocks(sb, phys);
  	struct ocfs2_extent_rec split_rec;
  	struct ocfs2_path *left_path = NULL;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_rec *rec;
  
  	left_path = ocfs2_new_path_from_et(et);
  	if (!left_path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_find_path(et->et_ci, left_path, cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  	el = path_leaf_el(left_path);
  
  	index = ocfs2_search_extent_list(el, cpos);
  	if (index == -1) {
  		ocfs2_error(sb,
  			    "Owner %llu has an extent at cpos %u which can no "
  			    "longer be found.\n",
  			     (unsigned long long)
  			     ocfs2_metadata_cache_owner(et->et_ci), cpos);
  		ret = -EROFS;
  		goto out;
  	}
  
  	ret = -EIO;
  	rec = &el->l_recs[index];
  	if (new_flags && (rec->e_flags & new_flags)) {
  		mlog(ML_ERROR, "Owner %llu tried to set %d flags on an "
  		     "extent that already had them",
  		     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  		     new_flags);
  		goto out;
  	}
  
  	if (clear_flags && !(rec->e_flags & clear_flags)) {
  		mlog(ML_ERROR, "Owner %llu tried to clear %d flags on an "
  		     "extent that didn't have them",
  		     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  		     clear_flags);
  		goto out;
  	}
  
  	memset(&split_rec, 0, sizeof(struct ocfs2_extent_rec));
  	split_rec.e_cpos = cpu_to_le32(cpos);
  	split_rec.e_leaf_clusters = cpu_to_le16(len);
  	split_rec.e_blkno = cpu_to_le64(start_blkno);
  	split_rec.e_flags = rec->e_flags;
  	if (new_flags)
  		split_rec.e_flags |= new_flags;
  	if (clear_flags)
  		split_rec.e_flags &= ~clear_flags;
  
  	ret = ocfs2_split_extent(handle, et, left_path,
  				 index, &split_rec, meta_ac,
  				 dealloc);
  	if (ret)
  		mlog_errno(ret);
  
  out:
  	ocfs2_free_path(left_path);
  	return ret;
  
  }
  
  /*
   * Mark the already-existing extent at cpos as written for len clusters.
   * This removes the unwritten extent flag.
   *
   * If the existing extent is larger than the request, initiate a
   * split. An attempt will be made at merging with adjacent extents.
   *
   * The caller is responsible for passing down meta_ac if we'll need it.
   */
  int ocfs2_mark_extent_written(struct inode *inode,
  			      struct ocfs2_extent_tree *et,
  			      handle_t *handle, u32 cpos, u32 len, u32 phys,
  			      struct ocfs2_alloc_context *meta_ac,
  			      struct ocfs2_cached_dealloc_ctxt *dealloc)
  {
  	int ret;
  
  	trace_ocfs2_mark_extent_written(
  		(unsigned long long)OCFS2_I(inode)->ip_blkno,
  		cpos, len, phys);
  
  	if (!ocfs2_writes_unwritten_extents(OCFS2_SB(inode->i_sb))) {
  		ocfs2_error(inode->i_sb, "Inode %llu has unwritten extents "
  			    "that are being written to, but the feature bit "
  			    "is not set in the super block.",
  			    (unsigned long long)OCFS2_I(inode)->ip_blkno);
  		ret = -EROFS;
  		goto out;
  	}
  
  	/*
  	 * XXX: This should be fixed up so that we just re-insert the
  	 * next extent records.
  	 */
  	ocfs2_et_extent_map_truncate(et, 0);
  
  	ret = ocfs2_change_extent_flag(handle, et, cpos,
  				       len, phys, meta_ac, dealloc,
  				       0, OCFS2_EXT_UNWRITTEN);
  	if (ret)
  		mlog_errno(ret);
  
  out:
  	return ret;
  }
  
  static int ocfs2_split_tree(handle_t *handle, struct ocfs2_extent_tree *et,
  			    struct ocfs2_path *path,
  			    int index, u32 new_range,
  			    struct ocfs2_alloc_context *meta_ac)
  {
  	int ret, depth, credits;
  	struct buffer_head *last_eb_bh = NULL;
  	struct ocfs2_extent_block *eb;
  	struct ocfs2_extent_list *rightmost_el, *el;
  	struct ocfs2_extent_rec split_rec;
  	struct ocfs2_extent_rec *rec;
  	struct ocfs2_insert_type insert;
  
  	/*
  	 * Setup the record to split before we grow the tree.
  	 */
  	el = path_leaf_el(path);
  	rec = &el->l_recs[index];
  	ocfs2_make_right_split_rec(ocfs2_metadata_cache_get_super(et->et_ci),
  				   &split_rec, new_range, rec);
  
  	depth = path->p_tree_depth;
  	if (depth > 0) {
  		ret = ocfs2_read_extent_block(et->et_ci,
  					      ocfs2_et_get_last_eb_blk(et),
  					      &last_eb_bh);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
  		rightmost_el = &eb->h_list;
  	} else
  		rightmost_el = path_leaf_el(path);
  
  	credits = path->p_tree_depth +
  		  ocfs2_extend_meta_needed(et->et_root_el);
  	ret = ocfs2_extend_trans(handle, credits);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (le16_to_cpu(rightmost_el->l_next_free_rec) ==
  	    le16_to_cpu(rightmost_el->l_count)) {
  		ret = ocfs2_grow_tree(handle, et, &depth, &last_eb_bh,
  				      meta_ac);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	memset(&insert, 0, sizeof(struct ocfs2_insert_type));
  	insert.ins_appending = APPEND_NONE;
  	insert.ins_contig = CONTIG_NONE;
  	insert.ins_split = SPLIT_RIGHT;
  	insert.ins_tree_depth = depth;
  
  	ret = ocfs2_do_insert_extent(handle, et, &split_rec, &insert);
  	if (ret)
  		mlog_errno(ret);
  
  out:
  	brelse(last_eb_bh);
  	return ret;
  }
  
  static int ocfs2_truncate_rec(handle_t *handle,
  			      struct ocfs2_extent_tree *et,
  			      struct ocfs2_path *path, int index,
  			      struct ocfs2_cached_dealloc_ctxt *dealloc,
  			      u32 cpos, u32 len)
  {
  	int ret;
  	u32 left_cpos, rec_range, trunc_range;
  	int wants_rotate = 0, is_rightmost_tree_rec = 0;
  	struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
  	struct ocfs2_path *left_path = NULL;
  	struct ocfs2_extent_list *el = path_leaf_el(path);
  	struct ocfs2_extent_rec *rec;
  	struct ocfs2_extent_block *eb;
  
  	if (ocfs2_is_empty_extent(&el->l_recs[0]) && index > 0) {
  		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		index--;
  	}
  
  	if (index == (le16_to_cpu(el->l_next_free_rec) - 1) &&
  	    path->p_tree_depth) {
  		/*
  		 * Check whether this is the rightmost tree record. If
  		 * we remove all of this record or part of its right
  		 * edge then an update of the record lengths above it
  		 * will be required.
  		 */
  		eb = (struct ocfs2_extent_block *)path_leaf_bh(path)->b_data;
  		if (eb->h_next_leaf_blk == 0)
  			is_rightmost_tree_rec = 1;
  	}
  
  	rec = &el->l_recs[index];
  	if (index == 0 && path->p_tree_depth &&
  	    le32_to_cpu(rec->e_cpos) == cpos) {
  		/*
  		 * Changing the leftmost offset (via partial or whole
  		 * record truncate) of an interior (or rightmost) path
  		 * means we have to update the subtree that is formed
  		 * by this leaf and the one to it's left.
  		 *
  		 * There are two cases we can skip:
  		 *   1) Path is the leftmost one in our btree.
  		 *   2) The leaf is rightmost and will be empty after
  		 *      we remove the extent record - the rotate code
  		 *      knows how to update the newly formed edge.
  		 */
  
  		ret = ocfs2_find_cpos_for_left_leaf(sb, path, &left_cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		if (left_cpos && le16_to_cpu(el->l_next_free_rec) > 1) {
  			left_path = ocfs2_new_path_from_path(path);
  			if (!left_path) {
  				ret = -ENOMEM;
  				mlog_errno(ret);
  				goto out;
  			}
  
  			ret = ocfs2_find_path(et->et_ci, left_path,
  					      left_cpos);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  		}
  	}
  
  	ret = ocfs2_extend_rotate_transaction(handle, 0,
  					      handle->h_buffer_credits,
  					      path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_journal_access_path(et->et_ci, handle, path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_journal_access_path(et->et_ci, handle, left_path);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	rec_range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
  	trunc_range = cpos + len;
  
  	if (le32_to_cpu(rec->e_cpos) == cpos && rec_range == trunc_range) {
  		int next_free;
  
  		memset(rec, 0, sizeof(*rec));
  		ocfs2_cleanup_merge(el, index);
  		wants_rotate = 1;
  
  		next_free = le16_to_cpu(el->l_next_free_rec);
  		if (is_rightmost_tree_rec && next_free > 1) {
  			/*
  			 * We skip the edge update if this path will
  			 * be deleted by the rotate code.
  			 */
  			rec = &el->l_recs[next_free - 1];
  			ocfs2_adjust_rightmost_records(handle, et, path,
  						       rec);
  		}
  	} else if (le32_to_cpu(rec->e_cpos) == cpos) {
  		/* Remove leftmost portion of the record. */
  		le32_add_cpu(&rec->e_cpos, len);
  		le64_add_cpu(&rec->e_blkno, ocfs2_clusters_to_blocks(sb, len));
  		le16_add_cpu(&rec->e_leaf_clusters, -len);
  	} else if (rec_range == trunc_range) {
  		/* Remove rightmost portion of the record */
  		le16_add_cpu(&rec->e_leaf_clusters, -len);
  		if (is_rightmost_tree_rec)
  			ocfs2_adjust_rightmost_records(handle, et, path, rec);
  	} else {
  		/* Caller should have trapped this. */
  		mlog(ML_ERROR, "Owner %llu: Invalid record truncate: (%u, %u) "
  		     "(%u, %u)\n",
  		     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  		     le32_to_cpu(rec->e_cpos),
  		     le16_to_cpu(rec->e_leaf_clusters), cpos, len);
  		BUG();
  	}
  
  	if (left_path) {
  		int subtree_index;
  
  		subtree_index = ocfs2_find_subtree_root(et, left_path, path);
  		ocfs2_complete_edge_insert(handle, left_path, path,
  					   subtree_index);
  	}
  
  	ocfs2_journal_dirty(handle, path_leaf_bh(path));
  
  	ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  out:
  	ocfs2_free_path(left_path);
  	return ret;
  }
  
  int ocfs2_remove_extent(handle_t *handle,
  			struct ocfs2_extent_tree *et,
  			u32 cpos, u32 len,
  			struct ocfs2_alloc_context *meta_ac,
  			struct ocfs2_cached_dealloc_ctxt *dealloc)
  {
  	int ret, index;
  	u32 rec_range, trunc_range;
  	struct ocfs2_extent_rec *rec;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_path *path = NULL;
  
  	/*
  	 * XXX: Why are we truncating to 0 instead of wherever this
  	 * affects us?
  	 */
  	ocfs2_et_extent_map_truncate(et, 0);
  
  	path = ocfs2_new_path_from_et(et);
  	if (!path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_find_path(et->et_ci, path, cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	el = path_leaf_el(path);
  	index = ocfs2_search_extent_list(el, cpos);
  	if (index == -1) {
  		ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  			    "Owner %llu has an extent at cpos %u which can no "
  			    "longer be found.\n",
  			    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  			    cpos);
  		ret = -EROFS;
  		goto out;
  	}
  
  	/*
  	 * We have 3 cases of extent removal:
  	 *   1) Range covers the entire extent rec
  	 *   2) Range begins or ends on one edge of the extent rec
  	 *   3) Range is in the middle of the extent rec (no shared edges)
  	 *
  	 * For case 1 we remove the extent rec and left rotate to
  	 * fill the hole.
  	 *
  	 * For case 2 we just shrink the existing extent rec, with a
  	 * tree update if the shrinking edge is also the edge of an
  	 * extent block.
  	 *
  	 * For case 3 we do a right split to turn the extent rec into
  	 * something case 2 can handle.
  	 */
  	rec = &el->l_recs[index];
  	rec_range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
  	trunc_range = cpos + len;
  
  	BUG_ON(cpos < le32_to_cpu(rec->e_cpos) || trunc_range > rec_range);
  
  	trace_ocfs2_remove_extent(
  		(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  		cpos, len, index, le32_to_cpu(rec->e_cpos),
  		ocfs2_rec_clusters(el, rec));
  
  	if (le32_to_cpu(rec->e_cpos) == cpos || rec_range == trunc_range) {
  		ret = ocfs2_truncate_rec(handle, et, path, index, dealloc,
  					 cpos, len);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	} else {
  		ret = ocfs2_split_tree(handle, et, path, index,
  				       trunc_range, meta_ac);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		/*
  		 * The split could have manipulated the tree enough to
  		 * move the record location, so we have to look for it again.
  		 */
  		ocfs2_reinit_path(path, 1);
  
  		ret = ocfs2_find_path(et->et_ci, path, cpos);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		el = path_leaf_el(path);
  		index = ocfs2_search_extent_list(el, cpos);
  		if (index == -1) {
  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  				    "Owner %llu: split at cpos %u lost record.",
  				    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  				    cpos);
  			ret = -EROFS;
  			goto out;
  		}
  
  		/*
  		 * Double check our values here. If anything is fishy,
  		 * it's easier to catch it at the top level.
  		 */
  		rec = &el->l_recs[index];
  		rec_range = le32_to_cpu(rec->e_cpos) +
  			ocfs2_rec_clusters(el, rec);
  		if (rec_range != trunc_range) {
  			ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
  				    "Owner %llu: error after split at cpos %u"
  				    "trunc len %u, existing record is (%u,%u)",
  				    (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
  				    cpos, len, le32_to_cpu(rec->e_cpos),
  				    ocfs2_rec_clusters(el, rec));
  			ret = -EROFS;
  			goto out;
  		}
  
  		ret = ocfs2_truncate_rec(handle, et, path, index, dealloc,
  					 cpos, len);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  out:
  	ocfs2_free_path(path);
  	return ret;
  }
  
  /*
   * ocfs2_reserve_blocks_for_rec_trunc() would look basically the
   * same as ocfs2_lock_alloctors(), except for it accepts a blocks
   * number to reserve some extra blocks, and it only handles meta
   * data allocations.
   *
   * Currently, only ocfs2_remove_btree_range() uses it for truncating
   * and punching holes.
   */
  static int ocfs2_reserve_blocks_for_rec_trunc(struct inode *inode,
  					      struct ocfs2_extent_tree *et,
  					      u32 extents_to_split,
  					      struct ocfs2_alloc_context **ac,
  					      int extra_blocks)
  {
  	int ret = 0, num_free_extents;
  	unsigned int max_recs_needed = 2 * extents_to_split;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	*ac = NULL;
  
  	num_free_extents = ocfs2_num_free_extents(osb, et);
  	if (num_free_extents < 0) {
  		ret = num_free_extents;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (!num_free_extents ||
  	    (ocfs2_sparse_alloc(osb) && num_free_extents < max_recs_needed))
  		extra_blocks += ocfs2_extend_meta_needed(et->et_root_el);
  
  	if (extra_blocks) {
  		ret = ocfs2_reserve_new_metadata_blocks(osb, extra_blocks, ac);
  		if (ret < 0) {
  			if (ret != -ENOSPC)
  				mlog_errno(ret);
  			goto out;
  		}
  	}
  
  out:
  	if (ret) {
  		if (*ac) {
  			ocfs2_free_alloc_context(*ac);
  			*ac = NULL;
  		}
  	}
  
  	return ret;
  }
  
  int ocfs2_remove_btree_range(struct inode *inode,
  			     struct ocfs2_extent_tree *et,
  			     u32 cpos, u32 phys_cpos, u32 len, int flags,
  			     struct ocfs2_cached_dealloc_ctxt *dealloc,
  			     u64 refcount_loc)
  {
  	int ret, credits = 0, extra_blocks = 0;
  	u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct inode *tl_inode = osb->osb_tl_inode;
  	handle_t *handle;
  	struct ocfs2_alloc_context *meta_ac = NULL;
  	struct ocfs2_refcount_tree *ref_tree = NULL;
  
  	if ((flags & OCFS2_EXT_REFCOUNTED) && len) {
  		BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
  			 OCFS2_HAS_REFCOUNT_FL));
  
  		ret = ocfs2_lock_refcount_tree(osb, refcount_loc, 1,
  					       &ref_tree, NULL);
  		if (ret) {
  			mlog_errno(ret);
  			goto bail;
  		}
  
  		ret = ocfs2_prepare_refcount_change_for_del(inode,
  							    refcount_loc,
  							    phys_blkno,
  							    len,
  							    &credits,
  							    &extra_blocks);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto bail;
  		}
  	}
  
  	ret = ocfs2_reserve_blocks_for_rec_trunc(inode, et, 1, &meta_ac,
  						 extra_blocks);
  	if (ret) {
  		mlog_errno(ret);
  		goto bail;
  	}
  
  	mutex_lock(&tl_inode->i_mutex);
  
  	if (ocfs2_truncate_log_needs_flush(osb)) {
  		ret = __ocfs2_flush_truncate_log(osb);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	handle = ocfs2_start_trans(osb,
  			ocfs2_remove_extent_credits(osb->sb) + credits);
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_et_root_journal_access(handle, et,
  					   OCFS2_JOURNAL_ACCESS_WRITE);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	dquot_free_space_nodirty(inode,
  				  ocfs2_clusters_to_bytes(inode->i_sb, len));
  
  	ret = ocfs2_remove_extent(handle, et, cpos, len, meta_ac, dealloc);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	ocfs2_et_update_clusters(et, -len);
  	ocfs2_update_inode_fsync_trans(handle, inode, 1);
  
  	ocfs2_journal_dirty(handle, et->et_root_bh);
  
  	if (phys_blkno) {
  		if (flags & OCFS2_EXT_REFCOUNTED)
  			ret = ocfs2_decrease_refcount(inode, handle,
  					ocfs2_blocks_to_clusters(osb->sb,
  								 phys_blkno),
  					len, meta_ac,
  					dealloc, 1);
  		else
  			ret = ocfs2_truncate_log_append(osb, handle,
  							phys_blkno, len);
  		if (ret)
  			mlog_errno(ret);
  
  	}
  
  out_commit:
  	ocfs2_commit_trans(osb, handle);
  out:
  	mutex_unlock(&tl_inode->i_mutex);
  bail:
  	if (meta_ac)
  		ocfs2_free_alloc_context(meta_ac);
  
  	if (ref_tree)
  		ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
  
  	return ret;
  }
  
  int ocfs2_truncate_log_needs_flush(struct ocfs2_super *osb)
  {
  	struct buffer_head *tl_bh = osb->osb_tl_bh;
  	struct ocfs2_dinode *di;
  	struct ocfs2_truncate_log *tl;
  
  	di = (struct ocfs2_dinode *) tl_bh->b_data;
  	tl = &di->id2.i_dealloc;
  
  	mlog_bug_on_msg(le16_to_cpu(tl->tl_used) > le16_to_cpu(tl->tl_count),
  			"slot %d, invalid truncate log parameters: used = "
  			"%u, count = %u\n", osb->slot_num,
  			le16_to_cpu(tl->tl_used), le16_to_cpu(tl->tl_count));
  	return le16_to_cpu(tl->tl_used) == le16_to_cpu(tl->tl_count);
  }
  
  static int ocfs2_truncate_log_can_coalesce(struct ocfs2_truncate_log *tl,
  					   unsigned int new_start)
  {
  	unsigned int tail_index;
  	unsigned int current_tail;
  
  	/* No records, nothing to coalesce */
  	if (!le16_to_cpu(tl->tl_used))
  		return 0;
  
  	tail_index = le16_to_cpu(tl->tl_used) - 1;
  	current_tail = le32_to_cpu(tl->tl_recs[tail_index].t_start);
  	current_tail += le32_to_cpu(tl->tl_recs[tail_index].t_clusters);
  
  	return current_tail == new_start;
  }
  
  int ocfs2_truncate_log_append(struct ocfs2_super *osb,
  			      handle_t *handle,
  			      u64 start_blk,
  			      unsigned int num_clusters)
  {
  	int status, index;
  	unsigned int start_cluster, tl_count;
  	struct inode *tl_inode = osb->osb_tl_inode;
  	struct buffer_head *tl_bh = osb->osb_tl_bh;
  	struct ocfs2_dinode *di;
  	struct ocfs2_truncate_log *tl;
  
  	BUG_ON(mutex_trylock(&tl_inode->i_mutex));
  
  	start_cluster = ocfs2_blocks_to_clusters(osb->sb, start_blk);
  
  	di = (struct ocfs2_dinode *) tl_bh->b_data;
  
  	/* tl_bh is loaded from ocfs2_truncate_log_init().  It's validated
  	 * by the underlying call to ocfs2_read_inode_block(), so any
  	 * corruption is a code bug */
  	BUG_ON(!OCFS2_IS_VALID_DINODE(di));
  
  	tl = &di->id2.i_dealloc;
  	tl_count = le16_to_cpu(tl->tl_count);
  	mlog_bug_on_msg(tl_count > ocfs2_truncate_recs_per_inode(osb->sb) ||
  			tl_count == 0,
  			"Truncate record count on #%llu invalid "
  			"wanted %u, actual %u\n",
  			(unsigned long long)OCFS2_I(tl_inode)->ip_blkno,
  			ocfs2_truncate_recs_per_inode(osb->sb),
  			le16_to_cpu(tl->tl_count));
  
  	/* Caller should have known to flush before calling us. */
  	index = le16_to_cpu(tl->tl_used);
  	if (index >= tl_count) {
  		status = -ENOSPC;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	status = ocfs2_journal_access_di(handle, INODE_CACHE(tl_inode), tl_bh,
  					 OCFS2_JOURNAL_ACCESS_WRITE);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	trace_ocfs2_truncate_log_append(
  		(unsigned long long)OCFS2_I(tl_inode)->ip_blkno, index,
  		start_cluster, num_clusters);
  	if (ocfs2_truncate_log_can_coalesce(tl, start_cluster)) {
  		/*
  		 * Move index back to the record we are coalescing with.
  		 * ocfs2_truncate_log_can_coalesce() guarantees nonzero
  		 */
  		index--;
  
  		num_clusters += le32_to_cpu(tl->tl_recs[index].t_clusters);
  		trace_ocfs2_truncate_log_append(
  			(unsigned long long)OCFS2_I(tl_inode)->ip_blkno,
  			index, le32_to_cpu(tl->tl_recs[index].t_start),
  			num_clusters);
  	} else {
  		tl->tl_recs[index].t_start = cpu_to_le32(start_cluster);
  		tl->tl_used = cpu_to_le16(index + 1);
  	}
  	tl->tl_recs[index].t_clusters = cpu_to_le32(num_clusters);
  
  	ocfs2_journal_dirty(handle, tl_bh);
  
  	osb->truncated_clusters += num_clusters;
  bail:
  	return status;
  }
  
  static int ocfs2_replay_truncate_records(struct ocfs2_super *osb,
  					 handle_t *handle,
  					 struct inode *data_alloc_inode,
  					 struct buffer_head *data_alloc_bh)
  {
  	int status = 0;
  	int i;
  	unsigned int num_clusters;
  	u64 start_blk;
  	struct ocfs2_truncate_rec rec;
  	struct ocfs2_dinode *di;
  	struct ocfs2_truncate_log *tl;
  	struct inode *tl_inode = osb->osb_tl_inode;
  	struct buffer_head *tl_bh = osb->osb_tl_bh;
  
  	di = (struct ocfs2_dinode *) tl_bh->b_data;
  	tl = &di->id2.i_dealloc;
  	i = le16_to_cpu(tl->tl_used) - 1;
  	while (i >= 0) {
  		/* Caller has given us at least enough credits to
  		 * update the truncate log dinode */
  		status = ocfs2_journal_access_di(handle, INODE_CACHE(tl_inode), tl_bh,
  						 OCFS2_JOURNAL_ACCESS_WRITE);
  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  
  		tl->tl_used = cpu_to_le16(i);
  
  		ocfs2_journal_dirty(handle, tl_bh);
  
  		/* TODO: Perhaps we can calculate the bulk of the
  		 * credits up front rather than extending like
  		 * this. */
  		status = ocfs2_extend_trans(handle,
  					    OCFS2_TRUNCATE_LOG_FLUSH_ONE_REC);
  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  
  		rec = tl->tl_recs[i];
  		start_blk = ocfs2_clusters_to_blocks(data_alloc_inode->i_sb,
  						    le32_to_cpu(rec.t_start));
  		num_clusters = le32_to_cpu(rec.t_clusters);
  
  		/* if start_blk is not set, we ignore the record as
  		 * invalid. */
  		if (start_blk) {
  			trace_ocfs2_replay_truncate_records(
  				(unsigned long long)OCFS2_I(tl_inode)->ip_blkno,
  				i, le32_to_cpu(rec.t_start), num_clusters);
  
  			status = ocfs2_free_clusters(handle, data_alloc_inode,
  						     data_alloc_bh, start_blk,
  						     num_clusters);
  			if (status < 0) {
  				mlog_errno(status);
  				goto bail;
  			}
  		}
  		i--;
  	}
  
  	osb->truncated_clusters = 0;
  
  bail:
  	return status;
  }
  
  /* Expects you to already be holding tl_inode->i_mutex */
  int __ocfs2_flush_truncate_log(struct ocfs2_super *osb)
  {
  	int status;
  	unsigned int num_to_flush;
  	handle_t *handle;
  	struct inode *tl_inode = osb->osb_tl_inode;
  	struct inode *data_alloc_inode = NULL;
  	struct buffer_head *tl_bh = osb->osb_tl_bh;
  	struct buffer_head *data_alloc_bh = NULL;
  	struct ocfs2_dinode *di;
  	struct ocfs2_truncate_log *tl;
  
  	BUG_ON(mutex_trylock(&tl_inode->i_mutex));
  
  	di = (struct ocfs2_dinode *) tl_bh->b_data;
  
  	/* tl_bh is loaded from ocfs2_truncate_log_init().  It's validated
  	 * by the underlying call to ocfs2_read_inode_block(), so any
  	 * corruption is a code bug */
  	BUG_ON(!OCFS2_IS_VALID_DINODE(di));
  
  	tl = &di->id2.i_dealloc;
  	num_to_flush = le16_to_cpu(tl->tl_used);
  	trace_ocfs2_flush_truncate_log(
  		(unsigned long long)OCFS2_I(tl_inode)->ip_blkno,
  		num_to_flush);
  	if (!num_to_flush) {
  		status = 0;
  		goto out;
  	}
  
  	data_alloc_inode = ocfs2_get_system_file_inode(osb,
  						       GLOBAL_BITMAP_SYSTEM_INODE,
  						       OCFS2_INVALID_SLOT);
  	if (!data_alloc_inode) {
  		status = -EINVAL;
  		mlog(ML_ERROR, "Could not get bitmap inode!\n");
  		goto out;
  	}
  
  	mutex_lock(&data_alloc_inode->i_mutex);
  
  	status = ocfs2_inode_lock(data_alloc_inode, &data_alloc_bh, 1);
  	if (status < 0) {
  		mlog_errno(status);
  		goto out_mutex;
  	}
  
  	handle = ocfs2_start_trans(osb, OCFS2_TRUNCATE_LOG_UPDATE);
  	if (IS_ERR(handle)) {
  		status = PTR_ERR(handle);
  		mlog_errno(status);
  		goto out_unlock;
  	}
  
  	status = ocfs2_replay_truncate_records(osb, handle, data_alloc_inode,
  					       data_alloc_bh);
  	if (status < 0)
  		mlog_errno(status);
  
  	ocfs2_commit_trans(osb, handle);
  
  out_unlock:
  	brelse(data_alloc_bh);
  	ocfs2_inode_unlock(data_alloc_inode, 1);
  
  out_mutex:
  	mutex_unlock(&data_alloc_inode->i_mutex);
  	iput(data_alloc_inode);
  
  out:
  	return status;
  }
  
  int ocfs2_flush_truncate_log(struct ocfs2_super *osb)
  {
  	int status;
  	struct inode *tl_inode = osb->osb_tl_inode;
  
  	mutex_lock(&tl_inode->i_mutex);
  	status = __ocfs2_flush_truncate_log(osb);
  	mutex_unlock(&tl_inode->i_mutex);
  
  	return status;
  }
  
  static void ocfs2_truncate_log_worker(struct work_struct *work)
  {
  	int status;
  	struct ocfs2_super *osb =
  		container_of(work, struct ocfs2_super,
  			     osb_truncate_log_wq.work);
  
  	status = ocfs2_flush_truncate_log(osb);
  	if (status < 0)
  		mlog_errno(status);
  	else
  		ocfs2_init_steal_slots(osb);
  }
  
  #define OCFS2_TRUNCATE_LOG_FLUSH_INTERVAL (2 * HZ)
  void ocfs2_schedule_truncate_log_flush(struct ocfs2_super *osb,
  				       int cancel)
  {
  	if (osb->osb_tl_inode &&
  			atomic_read(&osb->osb_tl_disable) == 0) {
  		/* We want to push off log flushes while truncates are
  		 * still running. */
  		if (cancel)
  			cancel_delayed_work(&osb->osb_truncate_log_wq);
  
  		queue_delayed_work(ocfs2_wq, &osb->osb_truncate_log_wq,
  				   OCFS2_TRUNCATE_LOG_FLUSH_INTERVAL);
  	}
  }
  
  static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb,
  				       int slot_num,
  				       struct inode **tl_inode,
  				       struct buffer_head **tl_bh)
  {
  	int status;
  	struct inode *inode = NULL;
  	struct buffer_head *bh = NULL;
  
  	inode = ocfs2_get_system_file_inode(osb,
  					   TRUNCATE_LOG_SYSTEM_INODE,
  					   slot_num);
  	if (!inode) {
  		status = -EINVAL;
  		mlog(ML_ERROR, "Could not get load truncate log inode!\n");
  		goto bail;
  	}
  
  	status = ocfs2_read_inode_block(inode, &bh);
  	if (status < 0) {
  		iput(inode);
  		mlog_errno(status);
  		goto bail;
  	}
  
  	*tl_inode = inode;
  	*tl_bh    = bh;
  bail:
  	return status;
  }
  
  /* called during the 1st stage of node recovery. we stamp a clean
   * truncate log and pass back a copy for processing later. if the
   * truncate log does not require processing, a *tl_copy is set to
   * NULL. */
  int ocfs2_begin_truncate_log_recovery(struct ocfs2_super *osb,
  				      int slot_num,
  				      struct ocfs2_dinode **tl_copy)
  {
  	int status;
  	struct inode *tl_inode = NULL;
  	struct buffer_head *tl_bh = NULL;
  	struct ocfs2_dinode *di;
  	struct ocfs2_truncate_log *tl;
  
  	*tl_copy = NULL;
  
  	trace_ocfs2_begin_truncate_log_recovery(slot_num);
  
  	status = ocfs2_get_truncate_log_info(osb, slot_num, &tl_inode, &tl_bh);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	di = (struct ocfs2_dinode *) tl_bh->b_data;
  
  	/* tl_bh is loaded from ocfs2_get_truncate_log_info().  It's
  	 * validated by the underlying call to ocfs2_read_inode_block(),
  	 * so any corruption is a code bug */
  	BUG_ON(!OCFS2_IS_VALID_DINODE(di));
  
  	tl = &di->id2.i_dealloc;
  	if (le16_to_cpu(tl->tl_used)) {
  		trace_ocfs2_truncate_log_recovery_num(le16_to_cpu(tl->tl_used));
  
  		*tl_copy = kmalloc(tl_bh->b_size, GFP_KERNEL);
  		if (!(*tl_copy)) {
  			status = -ENOMEM;
  			mlog_errno(status);
  			goto bail;
  		}
  
  		/* Assuming the write-out below goes well, this copy
  		 * will be passed back to recovery for processing. */
  		memcpy(*tl_copy, tl_bh->b_data, tl_bh->b_size);
  
  		/* All we need to do to clear the truncate log is set
  		 * tl_used. */
  		tl->tl_used = 0;
  
  		ocfs2_compute_meta_ecc(osb->sb, tl_bh->b_data, &di->i_check);
  		status = ocfs2_write_block(osb, tl_bh, INODE_CACHE(tl_inode));
  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  	}
  
  bail:
  	if (tl_inode)
  		iput(tl_inode);
  	brelse(tl_bh);
  
  	if (status < 0 && (*tl_copy)) {
  		kfree(*tl_copy);
  		*tl_copy = NULL;
  		mlog_errno(status);
  	}
  
  	return status;
  }
  
  int ocfs2_complete_truncate_log_recovery(struct ocfs2_super *osb,
  					 struct ocfs2_dinode *tl_copy)
  {
  	int status = 0;
  	int i;
  	unsigned int clusters, num_recs, start_cluster;
  	u64 start_blk;
  	handle_t *handle;
  	struct inode *tl_inode = osb->osb_tl_inode;
  	struct ocfs2_truncate_log *tl;
  
  	if (OCFS2_I(tl_inode)->ip_blkno == le64_to_cpu(tl_copy->i_blkno)) {
  		mlog(ML_ERROR, "Asked to recover my own truncate log!\n");
  		return -EINVAL;
  	}
  
  	tl = &tl_copy->id2.i_dealloc;
  	num_recs = le16_to_cpu(tl->tl_used);
  	trace_ocfs2_complete_truncate_log_recovery(
  		(unsigned long long)le64_to_cpu(tl_copy->i_blkno),
  		num_recs);
  
  	mutex_lock(&tl_inode->i_mutex);
  	for(i = 0; i < num_recs; i++) {
  		if (ocfs2_truncate_log_needs_flush(osb)) {
  			status = __ocfs2_flush_truncate_log(osb);
  			if (status < 0) {
  				mlog_errno(status);
  				goto bail_up;
  			}
  		}
  
  		handle = ocfs2_start_trans(osb, OCFS2_TRUNCATE_LOG_UPDATE);
  		if (IS_ERR(handle)) {
  			status = PTR_ERR(handle);
  			mlog_errno(status);
  			goto bail_up;
  		}
  
  		clusters = le32_to_cpu(tl->tl_recs[i].t_clusters);
  		start_cluster = le32_to_cpu(tl->tl_recs[i].t_start);
  		start_blk = ocfs2_clusters_to_blocks(osb->sb, start_cluster);
  
  		status = ocfs2_truncate_log_append(osb, handle,
  						   start_blk, clusters);
  		ocfs2_commit_trans(osb, handle);
  		if (status < 0) {
  			mlog_errno(status);
  			goto bail_up;
  		}
  	}
  
  bail_up:
  	mutex_unlock(&tl_inode->i_mutex);
  
  	return status;
  }
  
  void ocfs2_truncate_log_shutdown(struct ocfs2_super *osb)
  {
  	int status;
  	struct inode *tl_inode = osb->osb_tl_inode;
  
  	atomic_set(&osb->osb_tl_disable, 1);
  
  	if (tl_inode) {
  		cancel_delayed_work(&osb->osb_truncate_log_wq);
  		flush_workqueue(ocfs2_wq);
  
  		status = ocfs2_flush_truncate_log(osb);
  		if (status < 0)
  			mlog_errno(status);
  
  		brelse(osb->osb_tl_bh);
  		iput(osb->osb_tl_inode);
  	}
  }
  
  int ocfs2_truncate_log_init(struct ocfs2_super *osb)
  {
  	int status;
  	struct inode *tl_inode = NULL;
  	struct buffer_head *tl_bh = NULL;
  
  	status = ocfs2_get_truncate_log_info(osb,
  					     osb->slot_num,
  					     &tl_inode,
  					     &tl_bh);
  	if (status < 0)
  		mlog_errno(status);
  
  	/* ocfs2_truncate_log_shutdown keys on the existence of
  	 * osb->osb_tl_inode so we don't set any of the osb variables
  	 * until we're sure all is well. */
  	INIT_DELAYED_WORK(&osb->osb_truncate_log_wq,
  			  ocfs2_truncate_log_worker);
  	atomic_set(&osb->osb_tl_disable, 0);
  	osb->osb_tl_bh    = tl_bh;
  	osb->osb_tl_inode = tl_inode;
  
  	return status;
  }
  
  /*
   * Delayed de-allocation of suballocator blocks.
   *
   * Some sets of block de-allocations might involve multiple suballocator inodes.
   *
   * The locking for this can get extremely complicated, especially when
   * the suballocator inodes to delete from aren't known until deep
   * within an unrelated codepath.
   *
   * ocfs2_extent_block structures are a good example of this - an inode
   * btree could have been grown by any number of nodes each allocating
   * out of their own suballoc inode.
   *
   * These structures allow the delay of block de-allocation until a
   * later time, when locking of multiple cluster inodes won't cause
   * deadlock.
   */
  
  /*
   * Describe a single bit freed from a suballocator.  For the block
   * suballocators, it represents one block.  For the global cluster
   * allocator, it represents some clusters and free_bit indicates
   * clusters number.
   */
  struct ocfs2_cached_block_free {
  	struct ocfs2_cached_block_free		*free_next;
  	u64					free_bg;
  	u64					free_blk;
  	unsigned int				free_bit;
  };
  
  struct ocfs2_per_slot_free_list {
  	struct ocfs2_per_slot_free_list		*f_next_suballocator;
  	int					f_inode_type;
  	int					f_slot;
  	struct ocfs2_cached_block_free		*f_first;
  };
  
  static int ocfs2_free_cached_blocks(struct ocfs2_super *osb,
  				    int sysfile_type,
  				    int slot,
  				    struct ocfs2_cached_block_free *head)
  {
  	int ret;
  	u64 bg_blkno;
  	handle_t *handle;
  	struct inode *inode;
  	struct buffer_head *di_bh = NULL;
  	struct ocfs2_cached_block_free *tmp;
  
  	inode = ocfs2_get_system_file_inode(osb, sysfile_type, slot);
  	if (!inode) {
  		ret = -EINVAL;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	mutex_lock(&inode->i_mutex);
  
  	ret = ocfs2_inode_lock(inode, &di_bh, 1);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_mutex;
  	}
  
  	handle = ocfs2_start_trans(osb, OCFS2_SUBALLOC_FREE);
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		mlog_errno(ret);
  		goto out_unlock;
  	}
  
  	while (head) {
  		if (head->free_bg)
  			bg_blkno = head->free_bg;
  		else
  			bg_blkno = ocfs2_which_suballoc_group(head->free_blk,
  							      head->free_bit);
  		trace_ocfs2_free_cached_blocks(
  		     (unsigned long long)head->free_blk, head->free_bit);
  
  		ret = ocfs2_free_suballoc_bits(handle, inode, di_bh,
  					       head->free_bit, bg_blkno, 1);
  		if (ret) {
  			mlog_errno(ret);
  			goto out_journal;
  		}
  
  		ret = ocfs2_extend_trans(handle, OCFS2_SUBALLOC_FREE);
  		if (ret) {
  			mlog_errno(ret);
  			goto out_journal;
  		}
  
  		tmp = head;
  		head = head->free_next;
  		kfree(tmp);
  	}
  
  out_journal:
  	ocfs2_commit_trans(osb, handle);
  
  out_unlock:
  	ocfs2_inode_unlock(inode, 1);
  	brelse(di_bh);
  out_mutex:
  	mutex_unlock(&inode->i_mutex);
  	iput(inode);
  out:
  	while(head) {
  		/* Premature exit may have left some dangling items. */
  		tmp = head;
  		head = head->free_next;
  		kfree(tmp);
  	}
  
  	return ret;
  }
  
  int ocfs2_cache_cluster_dealloc(struct ocfs2_cached_dealloc_ctxt *ctxt,
  				u64 blkno, unsigned int bit)
  {
  	int ret = 0;
  	struct ocfs2_cached_block_free *item;
  
  	item = kzalloc(sizeof(*item), GFP_NOFS);
  	if (item == NULL) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		return ret;
  	}
  
  	trace_ocfs2_cache_cluster_dealloc((unsigned long long)blkno, bit);
  
  	item->free_blk = blkno;
  	item->free_bit = bit;
  	item->free_next = ctxt->c_global_allocator;
  
  	ctxt->c_global_allocator = item;
  	return ret;
  }
  
  static int ocfs2_free_cached_clusters(struct ocfs2_super *osb,
  				      struct ocfs2_cached_block_free *head)
  {
  	struct ocfs2_cached_block_free *tmp;
  	struct inode *tl_inode = osb->osb_tl_inode;
  	handle_t *handle;
  	int ret = 0;
  
  	mutex_lock(&tl_inode->i_mutex);
  
  	while (head) {
  		if (ocfs2_truncate_log_needs_flush(osb)) {
  			ret = __ocfs2_flush_truncate_log(osb);
  			if (ret < 0) {
  				mlog_errno(ret);
  				break;
  			}
  		}
  
  		handle = ocfs2_start_trans(osb, OCFS2_TRUNCATE_LOG_UPDATE);
  		if (IS_ERR(handle)) {
  			ret = PTR_ERR(handle);
  			mlog_errno(ret);
  			break;
  		}
  
  		ret = ocfs2_truncate_log_append(osb, handle, head->free_blk,
  						head->free_bit);
  
  		ocfs2_commit_trans(osb, handle);
  		tmp = head;
  		head = head->free_next;
  		kfree(tmp);
  
  		if (ret < 0) {
  			mlog_errno(ret);
  			break;
  		}
  	}
  
  	mutex_unlock(&tl_inode->i_mutex);
  
  	while (head) {
  		/* Premature exit may have left some dangling items. */
  		tmp = head;
  		head = head->free_next;
  		kfree(tmp);
  	}
  
  	return ret;
  }
  
  int ocfs2_run_deallocs(struct ocfs2_super *osb,
  		       struct ocfs2_cached_dealloc_ctxt *ctxt)
  {
  	int ret = 0, ret2;
  	struct ocfs2_per_slot_free_list *fl;
  
  	if (!ctxt)
  		return 0;
  
  	while (ctxt->c_first_suballocator) {
  		fl = ctxt->c_first_suballocator;
  
  		if (fl->f_first) {
  			trace_ocfs2_run_deallocs(fl->f_inode_type,
  						 fl->f_slot);
  			ret2 = ocfs2_free_cached_blocks(osb,
  							fl->f_inode_type,
  							fl->f_slot,
  							fl->f_first);
  			if (ret2)
  				mlog_errno(ret2);
  			if (!ret)
  				ret = ret2;
  		}
  
  		ctxt->c_first_suballocator = fl->f_next_suballocator;
  		kfree(fl);
  	}
  
  	if (ctxt->c_global_allocator) {
  		ret2 = ocfs2_free_cached_clusters(osb,
  						  ctxt->c_global_allocator);
  		if (ret2)
  			mlog_errno(ret2);
  		if (!ret)
  			ret = ret2;
  
  		ctxt->c_global_allocator = NULL;
  	}
  
  	return ret;
  }
  
  static struct ocfs2_per_slot_free_list *
  ocfs2_find_per_slot_free_list(int type,
  			      int slot,
  			      struct ocfs2_cached_dealloc_ctxt *ctxt)
  {
  	struct ocfs2_per_slot_free_list *fl = ctxt->c_first_suballocator;
  
  	while (fl) {
  		if (fl->f_inode_type == type && fl->f_slot == slot)
  			return fl;
  
  		fl = fl->f_next_suballocator;
  	}
  
  	fl = kmalloc(sizeof(*fl), GFP_NOFS);
  	if (fl) {
  		fl->f_inode_type = type;
  		fl->f_slot = slot;
  		fl->f_first = NULL;
  		fl->f_next_suballocator = ctxt->c_first_suballocator;
  
  		ctxt->c_first_suballocator = fl;
  	}
  	return fl;
  }
  
  int ocfs2_cache_block_dealloc(struct ocfs2_cached_dealloc_ctxt *ctxt,
  			      int type, int slot, u64 suballoc,
  			      u64 blkno, unsigned int bit)
  {
  	int ret;
  	struct ocfs2_per_slot_free_list *fl;
  	struct ocfs2_cached_block_free *item;
  
  	fl = ocfs2_find_per_slot_free_list(type, slot, ctxt);
  	if (fl == NULL) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	item = kzalloc(sizeof(*item), GFP_NOFS);
  	if (item == NULL) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	trace_ocfs2_cache_block_dealloc(type, slot,
  					(unsigned long long)suballoc,
  					(unsigned long long)blkno, bit);
  
  	item->free_bg = suballoc;
  	item->free_blk = blkno;
  	item->free_bit = bit;
  	item->free_next = fl->f_first;
  
  	fl->f_first = item;
  
  	ret = 0;
  out:
  	return ret;
  }
  
  static int ocfs2_cache_extent_block_free(struct ocfs2_cached_dealloc_ctxt *ctxt,
  					 struct ocfs2_extent_block *eb)
  {
  	return ocfs2_cache_block_dealloc(ctxt, EXTENT_ALLOC_SYSTEM_INODE,
  					 le16_to_cpu(eb->h_suballoc_slot),
  					 le64_to_cpu(eb->h_suballoc_loc),
  					 le64_to_cpu(eb->h_blkno),
  					 le16_to_cpu(eb->h_suballoc_bit));
  }
  
  static int ocfs2_zero_func(handle_t *handle, struct buffer_head *bh)
  {
  	set_buffer_uptodate(bh);
  	mark_buffer_dirty(bh);
  	return 0;
  }
  
  void ocfs2_map_and_dirty_page(struct inode *inode, handle_t *handle,
  			      unsigned int from, unsigned int to,
  			      struct page *page, int zero, u64 *phys)
  {
  	int ret, partial = 0;
  
  	ret = ocfs2_map_page_blocks(page, phys, inode, from, to, 0);
  	if (ret)
  		mlog_errno(ret);
  
  	if (zero)
  		zero_user_segment(page, from, to);
  
  	/*
  	 * Need to set the buffers we zero'd into uptodate
  	 * here if they aren't - ocfs2_map_page_blocks()
  	 * might've skipped some
  	 */
  	ret = walk_page_buffers(handle, page_buffers(page),
  				from, to, &partial,
  				ocfs2_zero_func);
  	if (ret < 0)
  		mlog_errno(ret);
  	else if (ocfs2_should_order_data(inode)) {
  		ret = ocfs2_jbd2_file_inode(handle, inode);
  		if (ret < 0)
  			mlog_errno(ret);
  	}
  
  	if (!partial)
  		SetPageUptodate(page);
  
  	flush_dcache_page(page);
  }
  
  static void ocfs2_zero_cluster_pages(struct inode *inode, loff_t start,
  				     loff_t end, struct page **pages,
  				     int numpages, u64 phys, handle_t *handle)
  {
  	int i;
  	struct page *page;
  	unsigned int from, to = PAGE_CACHE_SIZE;
  	struct super_block *sb = inode->i_sb;
  
  	BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(sb)));
  
  	if (numpages == 0)
  		goto out;
  
  	to = PAGE_CACHE_SIZE;
  	for(i = 0; i < numpages; i++) {
  		page = pages[i];
  
  		from = start & (PAGE_CACHE_SIZE - 1);
  		if ((end >> PAGE_CACHE_SHIFT) == page->index)
  			to = end & (PAGE_CACHE_SIZE - 1);
  
  		BUG_ON(from > PAGE_CACHE_SIZE);
  		BUG_ON(to > PAGE_CACHE_SIZE);
  
  		ocfs2_map_and_dirty_page(inode, handle, from, to, page, 1,
  					 &phys);
  
  		start = (page->index + 1) << PAGE_CACHE_SHIFT;
  	}
  out:
  	if (pages)
  		ocfs2_unlock_and_free_pages(pages, numpages);
  }
  
  int ocfs2_grab_pages(struct inode *inode, loff_t start, loff_t end,
  		     struct page **pages, int *num)
  {
  	int numpages, ret = 0;
  	struct address_space *mapping = inode->i_mapping;
  	unsigned long index;
  	loff_t last_page_bytes;
  
  	BUG_ON(start > end);
  
  	numpages = 0;
  	last_page_bytes = PAGE_ALIGN(end);
  	index = start >> PAGE_CACHE_SHIFT;
  	do {
  		pages[numpages] = find_or_create_page(mapping, index, GFP_NOFS);
  		if (!pages[numpages]) {
  			ret = -ENOMEM;
  			mlog_errno(ret);
  			goto out;
  		}
  
  		numpages++;
  		index++;
  	} while (index < (last_page_bytes >> PAGE_CACHE_SHIFT));
  
  out:
  	if (ret != 0) {
  		if (pages)
  			ocfs2_unlock_and_free_pages(pages, numpages);
  		numpages = 0;
  	}
  
  	*num = numpages;
  
  	return ret;
  }
  
  static int ocfs2_grab_eof_pages(struct inode *inode, loff_t start, loff_t end,
  				struct page **pages, int *num)
  {
  	struct super_block *sb = inode->i_sb;
  
  	BUG_ON(start >> OCFS2_SB(sb)->s_clustersize_bits !=
  	       (end - 1) >> OCFS2_SB(sb)->s_clustersize_bits);
  
  	return ocfs2_grab_pages(inode, start, end, pages, num);
  }
  
  /*
   * Zero the area past i_size but still within an allocated
   * cluster. This avoids exposing nonzero data on subsequent file
   * extends.
   *
   * We need to call this before i_size is updated on the inode because
   * otherwise block_write_full_page() will skip writeout of pages past
   * i_size. The new_i_size parameter is passed for this reason.
   */
  int ocfs2_zero_range_for_truncate(struct inode *inode, handle_t *handle,
  				  u64 range_start, u64 range_end)
  {
  	int ret = 0, numpages;
  	struct page **pages = NULL;
  	u64 phys;
  	unsigned int ext_flags;
  	struct super_block *sb = inode->i_sb;
  
  	/*
  	 * File systems which don't support sparse files zero on every
  	 * extend.
  	 */
  	if (!ocfs2_sparse_alloc(OCFS2_SB(sb)))
  		return 0;
  
  	pages = kcalloc(ocfs2_pages_per_cluster(sb),
  			sizeof(struct page *), GFP_NOFS);
  	if (pages == NULL) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (range_start == range_end)
  		goto out;
  
  	ret = ocfs2_extent_map_get_blocks(inode,
  					  range_start >> sb->s_blocksize_bits,
  					  &phys, NULL, &ext_flags);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * Tail is a hole, or is marked unwritten. In either case, we
  	 * can count on read and write to return/push zero's.
  	 */
  	if (phys == 0 || ext_flags & OCFS2_EXT_UNWRITTEN)
  		goto out;
  
  	ret = ocfs2_grab_eof_pages(inode, range_start, range_end, pages,
  				   &numpages);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ocfs2_zero_cluster_pages(inode, range_start, range_end, pages,
  				 numpages, phys, handle);
  
  	/*
  	 * Initiate writeout of the pages we zero'd here. We don't
  	 * wait on them - the truncate_inode_pages() call later will
  	 * do that for us.
  	 */
  	ret = filemap_fdatawrite_range(inode->i_mapping, range_start,
  				       range_end - 1);
  	if (ret)
  		mlog_errno(ret);
  
  out:
  	kfree(pages);
  
  	return ret;
  }
  
  static void ocfs2_zero_dinode_id2_with_xattr(struct inode *inode,
  					     struct ocfs2_dinode *di)
  {
  	unsigned int blocksize = 1 << inode->i_sb->s_blocksize_bits;
  	unsigned int xattrsize = le16_to_cpu(di->i_xattr_inline_size);
  
  	if (le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_XATTR_FL)
  		memset(&di->id2, 0, blocksize -
  				    offsetof(struct ocfs2_dinode, id2) -
  				    xattrsize);
  	else
  		memset(&di->id2, 0, blocksize -
  				    offsetof(struct ocfs2_dinode, id2));
  }
  
  void ocfs2_dinode_new_extent_list(struct inode *inode,
  				  struct ocfs2_dinode *di)
  {
  	ocfs2_zero_dinode_id2_with_xattr(inode, di);
  	di->id2.i_list.l_tree_depth = 0;
  	di->id2.i_list.l_next_free_rec = 0;
  	di->id2.i_list.l_count = cpu_to_le16(
  		ocfs2_extent_recs_per_inode_with_xattr(inode->i_sb, di));
  }
  
  void ocfs2_set_inode_data_inline(struct inode *inode, struct ocfs2_dinode *di)
  {
  	struct ocfs2_inode_info *oi = OCFS2_I(inode);
  	struct ocfs2_inline_data *idata = &di->id2.i_data;
  
  	spin_lock(&oi->ip_lock);
  	oi->ip_dyn_features |= OCFS2_INLINE_DATA_FL;
  	di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
  	spin_unlock(&oi->ip_lock);
  
  	/*
  	 * We clear the entire i_data structure here so that all
  	 * fields can be properly initialized.
  	 */
  	ocfs2_zero_dinode_id2_with_xattr(inode, di);
  
  	idata->id_count = cpu_to_le16(
  			ocfs2_max_inline_data_with_xattr(inode->i_sb, di));
  }
  
  int ocfs2_convert_inline_data_to_extents(struct inode *inode,
  					 struct buffer_head *di_bh)
  {
  	int ret, i, has_data, num_pages = 0;
  	int need_free = 0;
  	u32 bit_off, num;
  	handle_t *handle;
  	u64 uninitialized_var(block);
  	struct ocfs2_inode_info *oi = OCFS2_I(inode);
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
  	struct ocfs2_alloc_context *data_ac = NULL;
  	struct page **pages = NULL;
  	loff_t end = osb->s_clustersize;
  	struct ocfs2_extent_tree et;
  	int did_quota = 0;
  
  	has_data = i_size_read(inode) ? 1 : 0;
  
  	if (has_data) {
  		pages = kcalloc(ocfs2_pages_per_cluster(osb->sb),
  				sizeof(struct page *), GFP_NOFS);
  		if (pages == NULL) {
  			ret = -ENOMEM;
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_reserve_clusters(osb, 1, &data_ac);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	handle = ocfs2_start_trans(osb,
  				   ocfs2_inline_to_extents_credits(osb->sb));
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
  				      OCFS2_JOURNAL_ACCESS_WRITE);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	if (has_data) {
  		unsigned int page_end;
  		u64 phys;
  
  		ret = dquot_alloc_space_nodirty(inode,
  				       ocfs2_clusters_to_bytes(osb->sb, 1));
  		if (ret)
  			goto out_commit;
  		did_quota = 1;
  
  		data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
  
  		ret = ocfs2_claim_clusters(handle, data_ac, 1, &bit_off,
  					   &num);
  		if (ret) {
  			mlog_errno(ret);
  			goto out_commit;
  		}
  
  		/*
  		 * Save two copies, one for insert, and one that can
  		 * be changed by ocfs2_map_and_dirty_page() below.
  		 */
  		block = phys = ocfs2_clusters_to_blocks(inode->i_sb, bit_off);
  
  		/*
  		 * Non sparse file systems zero on extend, so no need
  		 * to do that now.
  		 */
  		if (!ocfs2_sparse_alloc(osb) &&
  		    PAGE_CACHE_SIZE < osb->s_clustersize)
  			end = PAGE_CACHE_SIZE;
  
  		ret = ocfs2_grab_eof_pages(inode, 0, end, pages, &num_pages);
  		if (ret) {
  			mlog_errno(ret);
  			need_free = 1;
  			goto out_commit;
  		}
  
  		/*
  		 * This should populate the 1st page for us and mark
  		 * it up to date.
  		 */
  		ret = ocfs2_read_inline_data(inode, pages[0], di_bh);
  		if (ret) {
  			mlog_errno(ret);
  			need_free = 1;
  			goto out_unlock;
  		}
  
  		page_end = PAGE_CACHE_SIZE;
  		if (PAGE_CACHE_SIZE > osb->s_clustersize)
  			page_end = osb->s_clustersize;
  
  		for (i = 0; i < num_pages; i++)
  			ocfs2_map_and_dirty_page(inode, handle, 0, page_end,
  						 pages[i], i > 0, &phys);
  	}
  
  	spin_lock(&oi->ip_lock);
  	oi->ip_dyn_features &= ~OCFS2_INLINE_DATA_FL;
  	di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
  	spin_unlock(&oi->ip_lock);
  
  	ocfs2_update_inode_fsync_trans(handle, inode, 1);
  	ocfs2_dinode_new_extent_list(inode, di);
  
  	ocfs2_journal_dirty(handle, di_bh);
  
  	if (has_data) {
  		/*
  		 * An error at this point should be extremely rare. If
  		 * this proves to be false, we could always re-build
  		 * the in-inode data from our pages.
  		 */
  		ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
  		ret = ocfs2_insert_extent(handle, &et, 0, block, 1, 0, NULL);
  		if (ret) {
  			mlog_errno(ret);
  			need_free = 1;
  			goto out_unlock;
  		}
  
  		inode->i_blocks = ocfs2_inode_sector_count(inode);
  	}
  
  out_unlock:
  	if (pages)
  		ocfs2_unlock_and_free_pages(pages, num_pages);
  
  out_commit:
  	if (ret < 0 && did_quota)
  		dquot_free_space_nodirty(inode,
  					  ocfs2_clusters_to_bytes(osb->sb, 1));
  
  	if (need_free) {
  		if (data_ac->ac_which == OCFS2_AC_USE_LOCAL)
  			ocfs2_free_local_alloc_bits(osb, handle, data_ac,
  					bit_off, num);
  		else
  			ocfs2_free_clusters(handle,
  					data_ac->ac_inode,
  					data_ac->ac_bh,
  					ocfs2_clusters_to_blocks(osb->sb, bit_off),
  					num);
  	}
  
  	ocfs2_commit_trans(osb, handle);
  
  out:
  	if (data_ac)
  		ocfs2_free_alloc_context(data_ac);
  	if (pages)
  		kfree(pages);
  
  	return ret;
  }
  
  /*
   * It is expected, that by the time you call this function,
   * inode->i_size and fe->i_size have been adjusted.
   *
   * WARNING: This will kfree the truncate context
   */
  int ocfs2_commit_truncate(struct ocfs2_super *osb,
  			  struct inode *inode,
  			  struct buffer_head *di_bh)
  {
  	int status = 0, i, flags = 0;
  	u32 new_highest_cpos, range, trunc_cpos, trunc_len, phys_cpos, coff;
  	u64 blkno = 0;
  	struct ocfs2_extent_list *el;
  	struct ocfs2_extent_rec *rec;
  	struct ocfs2_path *path = NULL;
  	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
  	struct ocfs2_extent_list *root_el = &(di->id2.i_list);
  	u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
  	struct ocfs2_extent_tree et;
  	struct ocfs2_cached_dealloc_ctxt dealloc;
  
  	ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
  	ocfs2_init_dealloc_ctxt(&dealloc);
  
  	new_highest_cpos = ocfs2_clusters_for_bytes(osb->sb,
  						     i_size_read(inode));
  
  	path = ocfs2_new_path(di_bh, &di->id2.i_list,
  			      ocfs2_journal_access_di);
  	if (!path) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	ocfs2_extent_map_trunc(inode, new_highest_cpos);
  
  start:
  	/*
  	 * Check that we still have allocation to delete.
  	 */
  	if (OCFS2_I(inode)->ip_clusters == 0) {
  		status = 0;
  		goto bail;
  	}
  
  	/*
  	 * Truncate always works against the rightmost tree branch.
  	 */
  	status = ocfs2_find_path(INODE_CACHE(inode), path, UINT_MAX);
  	if (status) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	trace_ocfs2_commit_truncate(
  		(unsigned long long)OCFS2_I(inode)->ip_blkno,
  		new_highest_cpos,
  		OCFS2_I(inode)->ip_clusters,
  		path->p_tree_depth);
  
  	/*
  	 * By now, el will point to the extent list on the bottom most
  	 * portion of this tree. Only the tail record is considered in
  	 * each pass.
  	 *
  	 * We handle the following cases, in order:
  	 * - empty extent: delete the remaining branch
  	 * - remove the entire record
  	 * - remove a partial record
  	 * - no record needs to be removed (truncate has completed)
  	 */
  	el = path_leaf_el(path);
  	if (le16_to_cpu(el->l_next_free_rec) == 0) {
  		ocfs2_error(inode->i_sb,
  			    "Inode %llu has empty extent block at %llu\n",
  			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
  			    (unsigned long long)path_leaf_bh(path)->b_blocknr);
  		status = -EROFS;
  		goto bail;
  	}
  
  	i = le16_to_cpu(el->l_next_free_rec) - 1;
  	rec = &el->l_recs[i];
  	flags = rec->e_flags;
  	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
  
  	if (i == 0 && ocfs2_is_empty_extent(rec)) {
  		/*
  		 * Lower levels depend on this never happening, but it's best
  		 * to check it up here before changing the tree.
  		*/
  		if (root_el->l_tree_depth && rec->e_int_clusters == 0) {
  			ocfs2_error(inode->i_sb, "Inode %lu has an empty "
  				    "extent record, depth %u\n", inode->i_ino,
  				    le16_to_cpu(root_el->l_tree_depth));
  			status = -EROFS;
  			goto bail;
  		}
  		trunc_cpos = le32_to_cpu(rec->e_cpos);
  		trunc_len = 0;
  		blkno = 0;
  	} else if (le32_to_cpu(rec->e_cpos) >= new_highest_cpos) {
  		/*
  		 * Truncate entire record.
  		 */
  		trunc_cpos = le32_to_cpu(rec->e_cpos);
  		trunc_len = ocfs2_rec_clusters(el, rec);
  		blkno = le64_to_cpu(rec->e_blkno);
  	} else if (range > new_highest_cpos) {
  		/*
  		 * Partial truncate. it also should be
  		 * the last truncate we're doing.
  		 */
  		trunc_cpos = new_highest_cpos;
  		trunc_len = range - new_highest_cpos;
  		coff = new_highest_cpos - le32_to_cpu(rec->e_cpos);
  		blkno = le64_to_cpu(rec->e_blkno) +
  				ocfs2_clusters_to_blocks(inode->i_sb, coff);
  	} else {
  		/*
  		 * Truncate completed, leave happily.
  		 */
  		status = 0;
  		goto bail;
  	}
  
  	phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
  
  	status = ocfs2_remove_btree_range(inode, &et, trunc_cpos,
  					  phys_cpos, trunc_len, flags, &dealloc,
  					  refcount_loc);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	ocfs2_reinit_path(path, 1);
  
  	/*
  	 * The check above will catch the case where we've truncated
  	 * away all allocation.
  	 */
  	goto start;
  
  bail:
  
  	ocfs2_schedule_truncate_log_flush(osb, 1);
  
  	ocfs2_run_deallocs(osb, &dealloc);
  
  	ocfs2_free_path(path);
  
  	return status;
  }
  
  /*
   * 'start' is inclusive, 'end' is not.
   */
  int ocfs2_truncate_inline(struct inode *inode, struct buffer_head *di_bh,
  			  unsigned int start, unsigned int end, int trunc)
  {
  	int ret;
  	unsigned int numbytes;
  	handle_t *handle;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
  	struct ocfs2_inline_data *idata = &di->id2.i_data;
  
  	if (end > i_size_read(inode))
  		end = i_size_read(inode);
  
  	BUG_ON(start > end);
  
  	if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) ||
  	    !(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL) ||
  	    !ocfs2_supports_inline_data(osb)) {
  		ocfs2_error(inode->i_sb,
  			    "Inline data flags for inode %llu don't agree! "
  			    "Disk: 0x%x, Memory: 0x%x, Superblock: 0x%x\n",
  			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
  			    le16_to_cpu(di->i_dyn_features),
  			    OCFS2_I(inode)->ip_dyn_features,
  			    osb->s_feature_incompat);
  		ret = -EROFS;
  		goto out;
  	}
  
  	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
  				      OCFS2_JOURNAL_ACCESS_WRITE);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	numbytes = end - start;
  	memset(idata->id_data + start, 0, numbytes);
  
  	/*
  	 * No need to worry about the data page here - it's been
  	 * truncated already and inline data doesn't need it for
  	 * pushing zero's to disk, so we'll let readpage pick it up
  	 * later.
  	 */
  	if (trunc) {
  		i_size_write(inode, start);
  		di->i_size = cpu_to_le64(start);
  	}
  
  	inode->i_blocks = ocfs2_inode_sector_count(inode);
  	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
  
  	di->i_ctime = di->i_mtime = cpu_to_le64(inode->i_ctime.tv_sec);
  	di->i_ctime_nsec = di->i_mtime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
  
  	ocfs2_update_inode_fsync_trans(handle, inode, 1);
  	ocfs2_journal_dirty(handle, di_bh);
  
  out_commit:
  	ocfs2_commit_trans(osb, handle);
  
  out:
  	return ret;
  }
  
  static int ocfs2_trim_extent(struct super_block *sb,
  			     struct ocfs2_group_desc *gd,
  			     u64 group, u32 start, u32 count)
  {
  	u64 discard, bcount;
  	struct ocfs2_super *osb = OCFS2_SB(sb);
  
  	bcount = ocfs2_clusters_to_blocks(sb, count);
  	discard = ocfs2_clusters_to_blocks(sb, start);
  
  	/*
  	 * For the first cluster group, the gd->bg_blkno is not at the start
  	 * of the group, but at an offset from the start. If we add it while
  	 * calculating discard for first group, we will wrongly start fstrim a
  	 * few blocks after the desried start block and the range can cross
  	 * over into the next cluster group. So, add it only if this is not
  	 * the first cluster group.
  	 */
  	if (group != osb->first_cluster_group_blkno)
  		discard += le64_to_cpu(gd->bg_blkno);
  
  	trace_ocfs2_trim_extent(sb, (unsigned long long)discard, bcount);
  
  	return sb_issue_discard(sb, discard, bcount, GFP_NOFS, 0);
  }
  
  static int ocfs2_trim_group(struct super_block *sb,
  			    struct ocfs2_group_desc *gd, u64 group,
  			    u32 start, u32 max, u32 minbits)
  {
  	int ret = 0, count = 0, next;
  	void *bitmap = gd->bg_bitmap;
  
  	if (le16_to_cpu(gd->bg_free_bits_count) < minbits)
  		return 0;
  
  	trace_ocfs2_trim_group((unsigned long long)le64_to_cpu(gd->bg_blkno),
  			       start, max, minbits);
  
  	while (start < max) {
  		start = ocfs2_find_next_zero_bit(bitmap, max, start);
  		if (start >= max)
  			break;
  		next = ocfs2_find_next_bit(bitmap, max, start);
  
  		if ((next - start) >= minbits) {
  			ret = ocfs2_trim_extent(sb, gd, group,
  						start, next - start);
  			if (ret < 0) {
  				mlog_errno(ret);
  				break;
  			}
  			count += next - start;
  		}
  		start = next + 1;
  
  		if (fatal_signal_pending(current)) {
  			count = -ERESTARTSYS;
  			break;
  		}
  
  		if ((le16_to_cpu(gd->bg_free_bits_count) - count) < minbits)
  			break;
  	}
  
  	if (ret < 0)
  		count = ret;
  
  	return count;
  }
  
  int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
  {
  	struct ocfs2_super *osb = OCFS2_SB(sb);
  	u64 start, len, trimmed, first_group, last_group, group;
  	int ret, cnt;
  	u32 first_bit, last_bit, minlen;
  	struct buffer_head *main_bm_bh = NULL;
  	struct inode *main_bm_inode = NULL;
  	struct buffer_head *gd_bh = NULL;
  	struct ocfs2_dinode *main_bm;
  	struct ocfs2_group_desc *gd = NULL;
  
  	start = range->start >> osb->s_clustersize_bits;
  	len = range->len >> osb->s_clustersize_bits;
  	minlen = range->minlen >> osb->s_clustersize_bits;
  
  	if (minlen >= osb->bitmap_cpg || range->len < sb->s_blocksize)
  		return -EINVAL;
  
  	main_bm_inode = ocfs2_get_system_file_inode(osb,
  						    GLOBAL_BITMAP_SYSTEM_INODE,
  						    OCFS2_INVALID_SLOT);
  	if (!main_bm_inode) {
  		ret = -EIO;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	mutex_lock(&main_bm_inode->i_mutex);
  
  	ret = ocfs2_inode_lock(main_bm_inode, &main_bm_bh, 0);
  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out_mutex;
  	}
  	main_bm = (struct ocfs2_dinode *)main_bm_bh->b_data;
  
  	if (start >= le32_to_cpu(main_bm->i_clusters)) {
  		ret = -EINVAL;
  		goto out_unlock;
  	}
  
  	len = range->len >> osb->s_clustersize_bits;
  	if (start + len > le32_to_cpu(main_bm->i_clusters))
  		len = le32_to_cpu(main_bm->i_clusters) - start;
  
  	trace_ocfs2_trim_fs(start, len, minlen);
  
  	/* Determine first and last group to examine based on start and len */
  	first_group = ocfs2_which_cluster_group(main_bm_inode, start);
  	if (first_group == osb->first_cluster_group_blkno)
  		first_bit = start;
  	else
  		first_bit = start - ocfs2_blocks_to_clusters(sb, first_group);
  	last_group = ocfs2_which_cluster_group(main_bm_inode, start + len - 1);
  	last_bit = osb->bitmap_cpg;
  
  	trimmed = 0;
  	for (group = first_group; group <= last_group;) {
  		if (first_bit + len >= osb->bitmap_cpg)
  			last_bit = osb->bitmap_cpg;
  		else
  			last_bit = first_bit + len;
  
  		ret = ocfs2_read_group_descriptor(main_bm_inode,
  						  main_bm, group,
  						  &gd_bh);
  		if (ret < 0) {
  			mlog_errno(ret);
  			break;
  		}
  
  		gd = (struct ocfs2_group_desc *)gd_bh->b_data;
  		cnt = ocfs2_trim_group(sb, gd, group,
  				       first_bit, last_bit, minlen);
  		brelse(gd_bh);
  		gd_bh = NULL;
  		if (cnt < 0) {
  			ret = cnt;
  			mlog_errno(ret);
  			break;
  		}
  
  		trimmed += cnt;
  		len -= osb->bitmap_cpg - first_bit;
  		first_bit = 0;
  		if (group == osb->first_cluster_group_blkno)
  			group = ocfs2_clusters_to_blocks(sb, osb->bitmap_cpg);
  		else
  			group += ocfs2_clusters_to_blocks(sb, osb->bitmap_cpg);
  	}
  	range->len = trimmed * sb->s_blocksize;
  out_unlock:
  	ocfs2_inode_unlock(main_bm_inode, 0);
  	brelse(main_bm_bh);
  out_mutex:
  	mutex_unlock(&main_bm_inode->i_mutex);
  	iput(main_bm_inode);
  out:
  	return ret;
  }
  