[PATCH] OCFS2: The Second Oracle Cluster Filesystem

The OCFS2 file system module.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>

1 files changed, 2040 insertions, 0 deletions

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
new file mode 100644
index 0000000..465f797
--- /dev/null
+++ b/fs/ocfs2/alloc.c
@@ -0,0 +1,2040 @@
+/* -*- 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>
+
+#define MLOG_MASK_PREFIX ML_DISK_ALLOC
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+
+#include "alloc.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 "buffer_head_io.h"
+
+static int ocfs2_extent_contig(struct inode *inode,
+			       struct ocfs2_extent_rec *ext,
+			       u64 blkno);
+
+static int ocfs2_create_new_meta_bhs(struct ocfs2_super *osb,
+				     struct ocfs2_journal_handle *handle,
+				     struct inode *inode,
+				     int wanted,
+				     struct ocfs2_alloc_context *meta_ac,
+				     struct buffer_head *bhs[]);
+
+static int ocfs2_add_branch(struct ocfs2_super *osb,
+			    struct ocfs2_journal_handle *handle,
+			    struct inode *inode,
+			    struct buffer_head *fe_bh,
+			    struct buffer_head *eb_bh,
+			    struct buffer_head *last_eb_bh,
+			    struct ocfs2_alloc_context *meta_ac);
+
+static int ocfs2_shift_tree_depth(struct ocfs2_super *osb,
+				  struct ocfs2_journal_handle *handle,
+				  struct inode *inode,
+				  struct buffer_head *fe_bh,
+				  struct ocfs2_alloc_context *meta_ac,
+				  struct buffer_head **ret_new_eb_bh);
+
+static int ocfs2_do_insert_extent(struct ocfs2_super *osb,
+				  struct ocfs2_journal_handle *handle,
+				  struct inode *inode,
+				  struct buffer_head *fe_bh,
+				  u64 blkno,
+				  u32 new_clusters);
+
+static int ocfs2_find_branch_target(struct ocfs2_super *osb,
+				    struct inode *inode,
+				    struct buffer_head *fe_bh,
+				    struct buffer_head **target_bh);
+
+static int ocfs2_find_new_last_ext_blk(struct ocfs2_super *osb,
+				       struct inode *inode,
+				       struct ocfs2_dinode *fe,
+				       unsigned int new_i_clusters,
+				       struct buffer_head *old_last_eb,
+				       struct buffer_head **new_last_eb);
+
+static void ocfs2_free_truncate_context(struct ocfs2_truncate_context *tc);
+
+static int ocfs2_extent_contig(struct inode *inode,
+			       struct ocfs2_extent_rec *ext,
+			       u64 blkno)
+{
+	return blkno == (le64_to_cpu(ext->e_blkno) +
+			 ocfs2_clusters_to_blocks(inode->i_sb,
+						  le32_to_cpu(ext->e_clusters)));
+}
+
+/*
+ * How many free extents have we got before we need more meta data?
+ */
+int ocfs2_num_free_extents(struct ocfs2_super *osb,
+			   struct inode *inode,
+			   struct ocfs2_dinode *fe)
+{
+	int retval;
+	struct ocfs2_extent_list *el;
+	struct ocfs2_extent_block *eb;
+	struct buffer_head *eb_bh = NULL;
+
+	mlog_entry_void();
+
+	if (!OCFS2_IS_VALID_DINODE(fe)) {
+		OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, fe);
+		retval = -EIO;
+		goto bail;
+	}
+
+	if (fe->i_last_eb_blk) {
+		retval = ocfs2_read_block(osb, le64_to_cpu(fe->i_last_eb_blk),
+					  &eb_bh, OCFS2_BH_CACHED, inode);
+		if (retval < 0) {
+			mlog_errno(retval);
+			goto bail;
+		}
+		eb = (struct ocfs2_extent_block *) eb_bh->b_data;
+		el = &eb->h_list;
+	} else
+		el = &fe->id2.i_list;
+
+	BUG_ON(el->l_tree_depth != 0);
+
+	retval = le16_to_cpu(el->l_count) - le16_to_cpu(el->l_next_free_rec);
+bail:
+	if (eb_bh)
+		brelse(eb_bh);
+
+	mlog_exit(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(struct ocfs2_super *osb,
+				     struct ocfs2_journal_handle *handle,
+				     struct inode *inode,
+				     int wanted,
+				     struct ocfs2_alloc_context *meta_ac,
+				     struct buffer_head *bhs[])
+{
+	int count, status, i;
+	u16 suballoc_bit_start;
+	u32 num_got;
+	u64 first_blkno;
+	struct ocfs2_extent_block *eb;
+
+	mlog_entry_void();
+
+	count = 0;
+	while (count < wanted) {
+		status = ocfs2_claim_metadata(osb,
+					      handle,
+					      meta_ac,
+					      wanted - count,
+					      &suballoc_bit_start,
+					      &num_got,
+					      &first_blkno);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		for(i = count;  i < (num_got + count); i++) {
+			bhs[i] = sb_getblk(osb->sb, first_blkno);
+			if (bhs[i] == NULL) {
+				status = -EIO;
+				mlog_errno(status);
+				goto bail;
+			}
+			ocfs2_set_new_buffer_uptodate(inode, bhs[i]);
+
+			status = ocfs2_journal_access(handle, inode, 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);
+
+#ifndef OCFS2_USE_ALL_METADATA_SUBALLOCATORS
+			/* we always use slot zero's suballocator */
+			eb->h_suballoc_slot = 0;
+#else
+			eb->h_suballoc_slot = cpu_to_le16(osb->slot_num);
+#endif
+			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. */
+			status = ocfs2_journal_dirty(handle, bhs[i]);
+			if (status < 0) {
+				mlog_errno(status);
+				goto bail;
+			}
+		}
+
+		count += num_got;
+	}
+
+	status = 0;
+bail:
+	if (status < 0) {
+		for(i = 0; i < wanted; i++) {
+			if (bhs[i])
+				brelse(bhs[i]);
+			bhs[i] = NULL;
+		}
+	}
+	mlog_exit(status);
+	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 dinode
+ * 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 e_clusters == 0.
+ */
+static int ocfs2_add_branch(struct ocfs2_super *osb,
+			    struct ocfs2_journal_handle *handle,
+			    struct inode *inode,
+			    struct buffer_head *fe_bh,
+			    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_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list  *eb_el;
+	struct ocfs2_extent_list  *el;
+
+	mlog_entry_void();
+
+	BUG_ON(!last_eb_bh);
+
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+
+	if (eb_bh) {
+		eb = (struct ocfs2_extent_block *) eb_bh->b_data;
+		el = &eb->h_list;
+	} else
+		el = &fe->id2.i_list;
+
+	/* we never add a branch to a leaf. */
+	BUG_ON(!el->l_tree_depth);
+
+	new_blocks = le16_to_cpu(el->l_tree_depth);
+
+	/* 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(osb, handle, inode, 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;
+		if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+			OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+			status = -EIO;
+			goto bail;
+		}
+		eb_el = &eb->h_list;
+
+		status = ocfs2_journal_access(handle, inode, 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);
+		eb_el->l_recs[0].e_cpos = fe->i_clusters;
+		eb_el->l_recs[0].e_blkno = cpu_to_le64(next_blkno);
+		eb_el->l_recs[0].e_clusters = cpu_to_le32(0);
+		if (!eb_el->l_tree_depth)
+			new_last_eb_blk = le64_to_cpu(eb->h_blkno);
+
+		status = ocfs2_journal_dirty(handle, bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		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(handle, inode, last_eb_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	status = ocfs2_journal_access(handle, inode, fe_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	if (eb_bh) {
+		status = ocfs2_journal_access(handle, inode, 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 fe, 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 = fe->i_clusters;
+	el->l_recs[i].e_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. */
+	fe->i_last_eb_blk = cpu_to_le64(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);
+
+	status = ocfs2_journal_dirty(handle, last_eb_bh);
+	if (status < 0)
+		mlog_errno(status);
+	status = ocfs2_journal_dirty(handle, fe_bh);
+	if (status < 0)
+		mlog_errno(status);
+	if (eb_bh) {
+		status = ocfs2_journal_dirty(handle, eb_bh);
+		if (status < 0)
+			mlog_errno(status);
+	}
+
+	status = 0;
+bail:
+	if (new_eb_bhs) {
+		for (i = 0; i < new_blocks; i++)
+			if (new_eb_bhs[i])
+				brelse(new_eb_bhs[i]);
+		kfree(new_eb_bhs);
+	}
+
+	mlog_exit(status);
+	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(struct ocfs2_super *osb,
+				  struct ocfs2_journal_handle *handle,
+				  struct inode *inode,
+				  struct buffer_head *fe_bh,
+				  struct ocfs2_alloc_context *meta_ac,
+				  struct buffer_head **ret_new_eb_bh)
+{
+	int status, i;
+	struct buffer_head *new_eb_bh = NULL;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list  *fe_el;
+	struct ocfs2_extent_list  *eb_el;
+
+	mlog_entry_void();
+
+	status = ocfs2_create_new_meta_bhs(osb, handle, inode, 1, meta_ac,
+					   &new_eb_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	eb = (struct ocfs2_extent_block *) new_eb_bh->b_data;
+	if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+		OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+		status = -EIO;
+		goto bail;
+	}
+
+	eb_el = &eb->h_list;
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+	fe_el = &fe->id2.i_list;
+
+	status = ocfs2_journal_access(handle, inode, new_eb_bh,
+				      OCFS2_JOURNAL_ACCESS_CREATE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/* copy the fe data into the new extent block */
+	eb_el->l_tree_depth = fe_el->l_tree_depth;
+	eb_el->l_next_free_rec = fe_el->l_next_free_rec;
+	for(i = 0; i < le16_to_cpu(fe_el->l_next_free_rec); i++) {
+		eb_el->l_recs[i].e_cpos = fe_el->l_recs[i].e_cpos;
+		eb_el->l_recs[i].e_clusters = fe_el->l_recs[i].e_clusters;
+		eb_el->l_recs[i].e_blkno = fe_el->l_recs[i].e_blkno;
+	}
+
+	status = ocfs2_journal_dirty(handle, new_eb_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = ocfs2_journal_access(handle, inode, fe_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/* update fe now */
+	le16_add_cpu(&fe_el->l_tree_depth, 1);
+	fe_el->l_recs[0].e_cpos = 0;
+	fe_el->l_recs[0].e_blkno = eb->h_blkno;
+	fe_el->l_recs[0].e_clusters = fe->i_clusters;
+	for(i = 1; i < le16_to_cpu(fe_el->l_next_free_rec); i++) {
+		fe_el->l_recs[i].e_cpos = 0;
+		fe_el->l_recs[i].e_clusters = 0;
+		fe_el->l_recs[i].e_blkno = 0;
+	}
+	fe_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 (fe_el->l_tree_depth == cpu_to_le16(1))
+		fe->i_last_eb_blk = eb->h_blkno;
+
+	status = ocfs2_journal_dirty(handle, fe_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	*ret_new_eb_bh = new_eb_bh;
+	new_eb_bh = NULL;
+	status = 0;
+bail:
+	if (new_eb_bh)
+		brelse(new_eb_bh);
+
+	mlog_exit(status);
+	return status;
+}
+
+/*
+ * Expects the tree to already have room in the rightmost leaf for the
+ * extent.  Updates all the extent blocks (and the dinode) on the way
+ * down.
+ */
+static int ocfs2_do_insert_extent(struct ocfs2_super *osb,
+				  struct ocfs2_journal_handle *handle,
+				  struct inode *inode,
+				  struct buffer_head *fe_bh,
+				  u64 start_blk,
+				  u32 new_clusters)
+{
+	int status, i, num_bhs = 0;
+	u64 next_blkno;
+	u16 next_free;
+	struct buffer_head **eb_bhs = NULL;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list  *el;
+
+	mlog_entry_void();
+
+	status = ocfs2_journal_access(handle, inode, fe_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+	el = &fe->id2.i_list;
+	if (el->l_tree_depth) {
+		/* This is another operation where we want to be
+		 * careful about our tree updates. An error here means
+		 * none of the previous changes we made should roll
+		 * forward. As a result, we have to record the buffers
+		 * for this part of the tree in an array and reserve a
+		 * journal write to them before making any changes. */
+		num_bhs = le16_to_cpu(fe->id2.i_list.l_tree_depth);
+		eb_bhs = kcalloc(num_bhs, sizeof(struct buffer_head *),
+				 GFP_KERNEL);
+		if (!eb_bhs) {
+			status = -ENOMEM;
+			mlog_errno(status);
+			goto bail;
+		}
+
+		i = 0;
+		while(el->l_tree_depth) {
+			next_free = le16_to_cpu(el->l_next_free_rec);
+			if (next_free == 0) {
+				ocfs2_error(inode->i_sb,
+					    "Dinode %"MLFu64" has a bad "
+					    "extent list",
+					    OCFS2_I(inode)->ip_blkno);
+				status = -EIO;
+				goto bail;
+			}
+			next_blkno = le64_to_cpu(el->l_recs[next_free - 1].e_blkno);
+
+			BUG_ON(i >= num_bhs);
+			status = ocfs2_read_block(osb, next_blkno, &eb_bhs[i],
+						  OCFS2_BH_CACHED, inode);
+			if (status < 0) {
+				mlog_errno(status);
+				goto bail;
+			}
+			eb = (struct ocfs2_extent_block *) eb_bhs[i]->b_data;
+			if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+				OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb,
+								 eb);
+				status = -EIO;
+				goto bail;
+			}
+
+			status = ocfs2_journal_access(handle, inode, eb_bhs[i],
+						      OCFS2_JOURNAL_ACCESS_WRITE);
+			if (status < 0) {
+				mlog_errno(status);
+				goto bail;
+			}
+
+			el = &eb->h_list;
+			i++;
+			/* When we leave this loop, eb_bhs[num_bhs - 1] will
+			 * hold the bottom-most leaf extent block. */
+		}
+		BUG_ON(el->l_tree_depth);
+
+		el = &fe->id2.i_list;
+		/* If we have tree depth, then the fe update is
+		 * trivial, and we want to switch el out for the
+		 * bottom-most leaf in order to update it with the
+		 * actual extent data below. */
+		next_free = le16_to_cpu(el->l_next_free_rec);
+		if (next_free == 0) {
+			ocfs2_error(inode->i_sb,
+				    "Dinode %"MLFu64" has a bad "
+				    "extent list",
+				    OCFS2_I(inode)->ip_blkno);
+			status = -EIO;
+			goto bail;
+		}
+		le32_add_cpu(&el->l_recs[next_free - 1].e_clusters,
+			     new_clusters);
+		/* (num_bhs - 1) to avoid the leaf */
+		for(i = 0; i < (num_bhs - 1); i++) {
+			eb = (struct ocfs2_extent_block *) eb_bhs[i]->b_data;
+			el = &eb->h_list;
+
+			/* finally, make our actual change to the
+			 * intermediate extent blocks. */
+			next_free = le16_to_cpu(el->l_next_free_rec);
+			le32_add_cpu(&el->l_recs[next_free - 1].e_clusters,
+				     new_clusters);
+
+			status = ocfs2_journal_dirty(handle, eb_bhs[i]);
+			if (status < 0)
+				mlog_errno(status);
+		}
+		BUG_ON(i != (num_bhs - 1));
+		/* note that the leaf block wasn't touched in
+		 * the loop above */
+		eb = (struct ocfs2_extent_block *) eb_bhs[num_bhs - 1]->b_data;
+		el = &eb->h_list;
+		BUG_ON(el->l_tree_depth);
+	}
+
+	/* yay, we can finally add the actual extent now! */
+	i = le16_to_cpu(el->l_next_free_rec) - 1;
+	if (le16_to_cpu(el->l_next_free_rec) &&
+	    ocfs2_extent_contig(inode, &el->l_recs[i], start_blk)) {
+		le32_add_cpu(&el->l_recs[i].e_clusters, new_clusters);
+	} else if (le16_to_cpu(el->l_next_free_rec) &&
+		   (le32_to_cpu(el->l_recs[i].e_clusters) == 0)) {
+		/* having an empty extent at eof is legal. */
+		if (el->l_recs[i].e_cpos != fe->i_clusters) {
+			ocfs2_error(inode->i_sb,
+				    "Dinode %"MLFu64" trailing extent is bad: "
+				    "cpos (%u) != number of clusters (%u)",
+				    le32_to_cpu(el->l_recs[i].e_cpos),
+				    le32_to_cpu(fe->i_clusters));
+			status = -EIO;
+			goto bail;
+		}
+		el->l_recs[i].e_blkno = cpu_to_le64(start_blk);
+		el->l_recs[i].e_clusters = cpu_to_le32(new_clusters);
+	} else {
+		/* No contiguous record, or no empty record at eof, so
+		 * we add a new one. */
+
+		BUG_ON(le16_to_cpu(el->l_next_free_rec) >=
+		       le16_to_cpu(el->l_count));
+		i = le16_to_cpu(el->l_next_free_rec);
+
+		el->l_recs[i].e_blkno = cpu_to_le64(start_blk);
+		el->l_recs[i].e_clusters = cpu_to_le32(new_clusters);
+		el->l_recs[i].e_cpos = fe->i_clusters;
+		le16_add_cpu(&el->l_next_free_rec, 1);
+	}
+
+	/*
+	 * extent_map errors are not fatal, so they are ignored outside
+	 * of flushing the thing.
+	 */
+	status = ocfs2_extent_map_append(inode, &el->l_recs[i],
+					 new_clusters);
+	if (status) {
+		mlog_errno(status);
+		ocfs2_extent_map_drop(inode, le32_to_cpu(fe->i_clusters));
+	}
+
+	status = ocfs2_journal_dirty(handle, fe_bh);
+	if (status < 0)
+		mlog_errno(status);
+	if (fe->id2.i_list.l_tree_depth) {
+		status = ocfs2_journal_dirty(handle, eb_bhs[num_bhs - 1]);
+		if (status < 0)
+			mlog_errno(status);
+	}
+
+	status = 0;
+bail:
+	if (eb_bhs) {
+		for (i = 0; i < num_bhs; i++)
+			if (eb_bhs[i])
+				brelse(eb_bhs[i]);
+		kfree(eb_bhs);
+	}
+
+	mlog_exit(status);
+	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 dinode has room. We
+ *    pass NULL back in *lowest_eb_bh, but still return '0'
+ *
+ * 3) the search fails to find anything AND the dinode is full, in
+ *    which case we return > 0
+ *
+ * return status < 0 indicates an error.
+ */
+static int ocfs2_find_branch_target(struct ocfs2_super *osb,
+				    struct inode *inode,
+				    struct buffer_head *fe_bh,
+				    struct buffer_head **target_bh)
+{
+	int status = 0, i;
+	u64 blkno;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list  *el;
+	struct buffer_head *bh = NULL;
+	struct buffer_head *lowest_bh = NULL;
+
+	mlog_entry_void();
+
+	*target_bh = NULL;
+
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+	el = &fe->id2.i_list;
+
+	while(le16_to_cpu(el->l_tree_depth) > 1) {
+		if (le16_to_cpu(el->l_next_free_rec) == 0) {
+			ocfs2_error(inode->i_sb, "Dinode %"MLFu64" has empty "
+				    "extent list (next_free_rec == 0)",
+				    OCFS2_I(inode)->ip_blkno);
+			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(inode->i_sb, "Dinode %"MLFu64" has extent "
+				    "list where extent # %d has no physical "
+				    "block start",
+				    OCFS2_I(inode)->ip_blkno, i);
+			status = -EIO;
+			goto bail;
+		}
+
+		if (bh) {
+			brelse(bh);
+			bh = NULL;
+		}
+
+		status = ocfs2_read_block(osb, blkno, &bh, OCFS2_BH_CACHED,
+					  inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		eb = (struct ocfs2_extent_block *) bh->b_data;
+		if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+			OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+			status = -EIO;
+			goto bail;
+		}
+		el = &eb->h_list;
+
+		if (le16_to_cpu(el->l_next_free_rec) <
+		    le16_to_cpu(el->l_count)) {
+			if (lowest_bh)
+				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' */
+	if (!lowest_bh
+	    && (fe->id2.i_list.l_next_free_rec == fe->id2.i_list.l_count))
+		status = 1;
+
+	*target_bh = lowest_bh;
+bail:
+	if (bh)
+		brelse(bh);
+
+	mlog_exit(status);
+	return status;
+}
+
+/* the caller needs to update fe->i_clusters */
+int ocfs2_insert_extent(struct ocfs2_super *osb,
+			struct ocfs2_journal_handle *handle,
+			struct inode *inode,
+			struct buffer_head *fe_bh,
+			u64 start_blk,
+			u32 new_clusters,
+			struct ocfs2_alloc_context *meta_ac)
+{
+	int status, i, shift;
+	struct buffer_head *last_eb_bh = NULL;
+	struct buffer_head *bh = NULL;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list  *el;
+
+	mlog_entry_void();
+
+	mlog(0, "add %u clusters starting at block %"MLFu64" to "
+		"inode %"MLFu64"\n",
+	     new_clusters, start_blk, OCFS2_I(inode)->ip_blkno);
+
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+	el = &fe->id2.i_list;
+
+	if (el->l_tree_depth) {
+		/* jump to end of tree */
+		status = ocfs2_read_block(osb, le64_to_cpu(fe->i_last_eb_blk),
+					  &last_eb_bh, OCFS2_BH_CACHED, inode);
+		if (status < 0) {
+			mlog_exit(status);
+			goto bail;
+		}
+		eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
+		el = &eb->h_list;
+	}
+
+	/* Can we allocate without adding/shifting tree bits? */
+	i = le16_to_cpu(el->l_next_free_rec) - 1;
+	if (le16_to_cpu(el->l_next_free_rec) == 0
+	    || (le16_to_cpu(el->l_next_free_rec) < le16_to_cpu(el->l_count))
+	    || le32_to_cpu(el->l_recs[i].e_clusters) == 0
+	    || ocfs2_extent_contig(inode, &el->l_recs[i], start_blk))
+		goto out_add;
+
+	mlog(0, "ocfs2_allocate_extent: couldn't do a simple add, traversing "
+	     "tree now.\n");
+
+	shift = ocfs2_find_branch_target(osb, inode, fe_bh, &bh);
+	if (shift < 0) {
+		status = shift;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/* 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) {
+		/* if we hit a leaf, we'd better be empty :) */
+		BUG_ON(le16_to_cpu(el->l_next_free_rec) !=
+		       le16_to_cpu(el->l_count));
+		BUG_ON(bh);
+		mlog(0, "ocfs2_allocate_extent: need to shift tree depth "
+		     "(current = %u)\n",
+		     le16_to_cpu(fe->id2.i_list.l_tree_depth));
+
+		/* ocfs2_shift_tree_depth will return us a buffer with
+		 * the new extent block (so we can pass that to
+		 * ocfs2_add_branch). */
+		status = ocfs2_shift_tree_depth(osb, handle, inode, fe_bh,
+						meta_ac, &bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		/* Special case: we have room now if we shifted from
+		 * tree_depth 0 */
+		if (fe->id2.i_list.l_tree_depth == cpu_to_le16(1))
+			goto out_add;
+	}
+
+	/* call ocfs2_add_branch to add the final part of the tree with
+	 * the new data. */
+	mlog(0, "ocfs2_allocate_extent: add branch. bh = %p\n", bh);
+	status = ocfs2_add_branch(osb, handle, inode, fe_bh, bh, last_eb_bh,
+				  meta_ac);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+out_add:
+	/* Finally, we can add clusters. */
+	status = ocfs2_do_insert_extent(osb, handle, inode, fe_bh,
+					start_blk, new_clusters);
+	if (status < 0)
+		mlog_errno(status);
+
+bail:
+	if (bh)
+		brelse(bh);
+
+	if (last_eb_bh)
+		brelse(last_eb_bh);
+
+	mlog_exit(status);
+	return status;
+}
+
+static inline 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;
+}
+
+static int ocfs2_truncate_log_append(struct ocfs2_super *osb,
+				     struct ocfs2_journal_handle *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;
+
+	mlog_entry("start_blk = %"MLFu64", num_clusters = %u\n", start_blk,
+		   num_clusters);
+
+	BUG_ON(!down_trylock(&tl_inode->i_sem));
+
+	start_cluster = ocfs2_blocks_to_clusters(osb->sb, start_blk);
+
+	di = (struct ocfs2_dinode *) tl_bh->b_data;
+	tl = &di->id2.i_dealloc;
+	if (!OCFS2_IS_VALID_DINODE(di)) {
+		OCFS2_RO_ON_INVALID_DINODE(osb->sb, di);
+		status = -EIO;
+		goto bail;
+	}
+
+	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 #%"MLFu64" invalid ("
+			"wanted %u, actual %u\n", 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(handle, tl_inode, tl_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	mlog(0, "Log truncate of %u clusters starting at cluster %u to "
+	     "%"MLFu64" (index = %d)\n", num_clusters, start_cluster,
+	     OCFS2_I(tl_inode)->ip_blkno, index);
+
+	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);
+		mlog(0, "Coalesce with index %u (start = %u, clusters = %u)\n",
+		     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);
+
+	status = ocfs2_journal_dirty(handle, tl_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+bail:
+	mlog_exit(status);
+	return status;
+}
+
+static int ocfs2_replay_truncate_records(struct ocfs2_super *osb,
+					 struct ocfs2_journal_handle *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;
+
+	mlog_entry_void();
+
+	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(handle, tl_inode, tl_bh,
+					      OCFS2_JOURNAL_ACCESS_WRITE);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		tl->tl_used = cpu_to_le16(i);
+
+		status = ocfs2_journal_dirty(handle, tl_bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		/* 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) {
+			mlog(0, "free record %d, start = %u, clusters = %u\n",
+			     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--;
+	}
+
+bail:
+	mlog_exit(status);
+	return status;
+}
+
+/* Expects you to already be holding tl_inode->i_sem */
+static int __ocfs2_flush_truncate_log(struct ocfs2_super *osb)
+{
+	int status;
+	unsigned int num_to_flush;
+	struct ocfs2_journal_handle *handle = NULL;
+	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;
+
+	mlog_entry_void();
+
+	BUG_ON(!down_trylock(&tl_inode->i_sem));
+
+	di = (struct ocfs2_dinode *) tl_bh->b_data;
+	tl = &di->id2.i_dealloc;
+	if (!OCFS2_IS_VALID_DINODE(di)) {
+		OCFS2_RO_ON_INVALID_DINODE(osb->sb, di);
+		status = -EIO;
+		goto bail;
+	}
+
+	num_to_flush = le16_to_cpu(tl->tl_used);
+	mlog(0, "Flush %u records from truncate log #%"MLFu64"\n",
+	     num_to_flush, OCFS2_I(tl_inode)->ip_blkno);
+	if (!num_to_flush) {
+		status = 0;
+		goto bail;
+	}
+
+	handle = ocfs2_alloc_handle(osb);
+	if (!handle) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	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 bail;
+	}
+
+	ocfs2_handle_add_inode(handle, data_alloc_inode);
+	status = ocfs2_meta_lock(data_alloc_inode, handle, &data_alloc_bh, 1);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	handle = ocfs2_start_trans(osb, handle, OCFS2_TRUNCATE_LOG_UPDATE);
+	if (IS_ERR(handle)) {
+		status = PTR_ERR(handle);
+		handle = NULL;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = ocfs2_replay_truncate_records(osb, handle, data_alloc_inode,
+					       data_alloc_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+bail:
+	if (handle)
+		ocfs2_commit_trans(handle);
+
+	if (data_alloc_inode)
+		iput(data_alloc_inode);
+
+	if (data_alloc_bh)
+		brelse(data_alloc_bh);
+
+	mlog_exit(status);
+	return status;
+}
+
+int ocfs2_flush_truncate_log(struct ocfs2_super *osb)
+{
+	int status;
+	struct inode *tl_inode = osb->osb_tl_inode;
+
+	down(&tl_inode->i_sem);
+	status = __ocfs2_flush_truncate_log(osb);
+	up(&tl_inode->i_sem);
+
+	return status;
+}
+
+static void ocfs2_truncate_log_worker(void *data)
+{
+	int status;
+	struct ocfs2_super *osb = data;
+
+	mlog_entry_void();
+
+	status = ocfs2_flush_truncate_log(osb);
+	if (status < 0)
+		mlog_errno(status);
+
+	mlog_exit(status);
+}
+
+#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) {
+		/* 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_block(osb, OCFS2_I(inode)->ip_blkno, &bh,
+				  OCFS2_BH_CACHED, inode);
+	if (status < 0) {
+		iput(inode);
+		mlog_errno(status);
+		goto bail;
+	}
+
+	*tl_inode = inode;
+	*tl_bh    = bh;
+bail:
+	mlog_exit(status);
+	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;
+
+	mlog(0, "recover truncate log from slot %d\n", 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 = &di->id2.i_dealloc;
+	if (!OCFS2_IS_VALID_DINODE(di)) {
+		OCFS2_RO_ON_INVALID_DINODE(tl_inode->i_sb, di);
+		status = -EIO;
+		goto bail;
+	}
+
+	if (le16_to_cpu(tl->tl_used)) {
+		mlog(0, "We'll have %u logs to recover\n",
+		     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;
+
+		status = ocfs2_write_block(osb, tl_bh, tl_inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+bail:
+	if (tl_inode)
+		iput(tl_inode);
+	if (tl_bh)
+		brelse(tl_bh);
+
+	if (status < 0 && (*tl_copy)) {
+		kfree(*tl_copy);
+		*tl_copy = NULL;
+	}
+
+	mlog_exit(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;
+	struct ocfs2_journal_handle *handle;
+	struct inode *tl_inode = osb->osb_tl_inode;
+	struct ocfs2_truncate_log *tl;
+
+	mlog_entry_void();
+
+	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);
+	mlog(0, "cleanup %u records from %"MLFu64"\n", num_recs,
+	     tl_copy->i_blkno);
+
+	down(&tl_inode->i_sem);
+	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, NULL,
+					   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(handle);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail_up;
+		}
+	}
+
+bail_up:
+	up(&tl_inode->i_sem);
+
+	mlog_exit(status);
+	return status;
+}
+
+void ocfs2_truncate_log_shutdown(struct ocfs2_super *osb)
+{
+	int status;
+	struct inode *tl_inode = osb->osb_tl_inode;
+
+	mlog_entry_void();
+
+	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);
+	}
+
+	mlog_exit_void();
+}
+
+int ocfs2_truncate_log_init(struct ocfs2_super *osb)
+{
+	int status;
+	struct inode *tl_inode = NULL;
+	struct buffer_head *tl_bh = NULL;
+
+	mlog_entry_void();
+
+	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_WORK(&osb->osb_truncate_log_wq, ocfs2_truncate_log_worker, osb);
+	osb->osb_tl_bh    = tl_bh;
+	osb->osb_tl_inode = tl_inode;
+
+	mlog_exit(status);
+	return status;
+}
+
+/* This function will figure out whether the currently last extent
+ * block will be deleted, and if it will, what the new last extent
+ * block will be so we can update his h_next_leaf_blk field, as well
+ * as the dinodes i_last_eb_blk */
+static int ocfs2_find_new_last_ext_blk(struct ocfs2_super *osb,
+				       struct inode *inode,
+				       struct ocfs2_dinode *fe,
+				       u32 new_i_clusters,
+				       struct buffer_head *old_last_eb,
+				       struct buffer_head **new_last_eb)
+{
+	int i, status = 0;
+	u64 block = 0;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list *el;
+	struct buffer_head *bh = NULL;
+
+	*new_last_eb = NULL;
+
+	if (!OCFS2_IS_VALID_DINODE(fe)) {
+		OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, fe);
+		status = -EIO;
+		goto bail;
+	}
+
+	/* we have no tree, so of course, no last_eb. */
+	if (!fe->id2.i_list.l_tree_depth)
+		goto bail;
+
+	/* trunc to zero special case - this makes tree_depth = 0
+	 * regardless of what it is.  */
+	if (!new_i_clusters)
+		goto bail;
+
+	eb = (struct ocfs2_extent_block *) old_last_eb->b_data;
+	el = &(eb->h_list);
+	BUG_ON(!el->l_next_free_rec);
+
+	/* Make sure that this guy will actually be empty after we
+	 * clear away the data. */
+	if (le32_to_cpu(el->l_recs[0].e_cpos) < new_i_clusters)
+		goto bail;
+
+	/* Ok, at this point, we know that last_eb will definitely
+	 * change, so lets traverse the tree and find the second to
+	 * last extent block. */
+	el = &(fe->id2.i_list);
+	/* go down the tree, */
+	do {
+		for(i = (le16_to_cpu(el->l_next_free_rec) - 1); i >= 0; i--) {
+			if (le32_to_cpu(el->l_recs[i].e_cpos) <
+			    new_i_clusters) {
+				block = le64_to_cpu(el->l_recs[i].e_blkno);
+				break;
+			}
+		}
+		BUG_ON(i < 0);
+
+		if (bh) {
+			brelse(bh);
+			bh = NULL;
+		}
+
+		status = ocfs2_read_block(osb, block, &bh, OCFS2_BH_CACHED,
+					 inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		eb = (struct ocfs2_extent_block *) bh->b_data;
+		el = &eb->h_list;
+		if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+			OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+			status = -EIO;
+			goto bail;
+		}
+	} while (el->l_tree_depth);
+
+	*new_last_eb = bh;
+	get_bh(*new_last_eb);
+	mlog(0, "returning block %"MLFu64"\n", le64_to_cpu(eb->h_blkno));
+bail:
+	if (bh)
+		brelse(bh);
+
+	return status;
+}
+
+static int ocfs2_do_truncate(struct ocfs2_super *osb,
+			     unsigned int clusters_to_del,
+			     struct inode *inode,
+			     struct buffer_head *fe_bh,
+			     struct buffer_head *old_last_eb_bh,
+			     struct ocfs2_journal_handle *handle,
+			     struct ocfs2_truncate_context *tc)
+{
+	int status, i, depth;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_block *last_eb = NULL;
+	struct ocfs2_extent_list *el;
+	struct buffer_head *eb_bh = NULL;
+	struct buffer_head *last_eb_bh = NULL;
+	u64 next_eb = 0;
+	u64 delete_blk = 0;
+
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+
+	status = ocfs2_find_new_last_ext_blk(osb,
+					     inode,
+					     fe,
+					     le32_to_cpu(fe->i_clusters) -
+					     		clusters_to_del,
+					     old_last_eb_bh,
+					     &last_eb_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	if (last_eb_bh)
+		last_eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
+
+	status = ocfs2_journal_access(handle, inode, fe_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	el = &(fe->id2.i_list);
+
+	spin_lock(&OCFS2_I(inode)->ip_lock);
+	OCFS2_I(inode)->ip_clusters = le32_to_cpu(fe->i_clusters) -
+				      clusters_to_del;
+	spin_unlock(&OCFS2_I(inode)->ip_lock);
+	le32_add_cpu(&fe->i_clusters, -clusters_to_del);
+	fe->i_mtime = cpu_to_le64(CURRENT_TIME.tv_sec);
+	fe->i_mtime_nsec = cpu_to_le32(CURRENT_TIME.tv_nsec);
+
+	i = le16_to_cpu(el->l_next_free_rec) - 1;
+
+	BUG_ON(le32_to_cpu(el->l_recs[i].e_clusters) < clusters_to_del);
+	le32_add_cpu(&el->l_recs[i].e_clusters, -clusters_to_del);
+	/* tree depth zero, we can just delete the clusters, otherwise
+	 * we need to record the offset of the next level extent block
+	 * as we may overwrite it. */
+	if (!el->l_tree_depth)
+		delete_blk = le64_to_cpu(el->l_recs[i].e_blkno)
+			+ ocfs2_clusters_to_blocks(osb->sb,
+					le32_to_cpu(el->l_recs[i].e_clusters));
+	else
+		next_eb = le64_to_cpu(el->l_recs[i].e_blkno);
+
+	if (!el->l_recs[i].e_clusters) {
+		/* if we deleted the whole extent record, then clear
+		 * out the other fields and update the extent
+		 * list. For depth > 0 trees, we've already recorded
+		 * the extent block in 'next_eb' */
+		el->l_recs[i].e_cpos = 0;
+		el->l_recs[i].e_blkno = 0;
+		BUG_ON(!el->l_next_free_rec);
+		le16_add_cpu(&el->l_next_free_rec, -1);
+	}
+
+	depth = le16_to_cpu(el->l_tree_depth);
+	if (!fe->i_clusters) {
+		/* trunc to zero is a special case. */
+		el->l_tree_depth = 0;
+		fe->i_last_eb_blk = 0;
+	} else if (last_eb)
+		fe->i_last_eb_blk = last_eb->h_blkno;
+
+	status = ocfs2_journal_dirty(handle, fe_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	if (last_eb) {
+		/* If there will be a new last extent block, then by
+		 * definition, there cannot be any leaves to the right of
+		 * him. */
+		status = ocfs2_journal_access(handle, inode, last_eb_bh,
+					      OCFS2_JOURNAL_ACCESS_WRITE);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		last_eb->h_next_leaf_blk = 0;
+		status = ocfs2_journal_dirty(handle, last_eb_bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	/* if our tree depth > 0, update all the tree blocks below us. */
+	while (depth) {
+		mlog(0, "traveling tree (depth = %d, next_eb = %"MLFu64")\n",
+		     depth,  next_eb);
+		status = ocfs2_read_block(osb, next_eb, &eb_bh,
+					  OCFS2_BH_CACHED, inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		eb = (struct ocfs2_extent_block *)eb_bh->b_data;
+		if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+			OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+			status = -EIO;
+			goto bail;
+		}
+		el = &(eb->h_list);
+
+		status = ocfs2_journal_access(handle, inode, eb_bh,
+					      OCFS2_JOURNAL_ACCESS_WRITE);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		BUG_ON(le16_to_cpu(el->l_next_free_rec) == 0);
+		BUG_ON(depth != (le16_to_cpu(el->l_tree_depth) + 1));
+
+		i = le16_to_cpu(el->l_next_free_rec) - 1;
+
+		mlog(0, "extent block %"MLFu64", before: record %d: "
+		     "(%u, %u, %"MLFu64"), next = %u\n",
+		     le64_to_cpu(eb->h_blkno), i,
+		     le32_to_cpu(el->l_recs[i].e_cpos),
+		     le32_to_cpu(el->l_recs[i].e_clusters),
+		     le64_to_cpu(el->l_recs[i].e_blkno),
+		     le16_to_cpu(el->l_next_free_rec));
+
+		BUG_ON(le32_to_cpu(el->l_recs[i].e_clusters) < clusters_to_del);
+		le32_add_cpu(&el->l_recs[i].e_clusters, -clusters_to_del);
+
+		next_eb = le64_to_cpu(el->l_recs[i].e_blkno);
+		/* bottom-most block requires us to delete data.*/
+		if (!el->l_tree_depth)
+			delete_blk = le64_to_cpu(el->l_recs[i].e_blkno)
+				+ ocfs2_clusters_to_blocks(osb->sb,
+					le32_to_cpu(el->l_recs[i].e_clusters));
+		if (!el->l_recs[i].e_clusters) {
+			el->l_recs[i].e_cpos = 0;
+			el->l_recs[i].e_blkno = 0;
+			BUG_ON(!el->l_next_free_rec);
+			le16_add_cpu(&el->l_next_free_rec, -1);
+		}
+		mlog(0, "extent block %"MLFu64", after: record %d: "
+		     "(%u, %u, %"MLFu64"), next = %u\n",
+		     le64_to_cpu(eb->h_blkno), i,
+		     le32_to_cpu(el->l_recs[i].e_cpos),
+		     le32_to_cpu(el->l_recs[i].e_clusters),
+		     le64_to_cpu(el->l_recs[i].e_blkno),
+		     le16_to_cpu(el->l_next_free_rec));
+
+		status = ocfs2_journal_dirty(handle, eb_bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		if (!el->l_next_free_rec) {
+			mlog(0, "deleting this extent block.\n");
+
+			ocfs2_remove_from_cache(inode, eb_bh);
+
+			BUG_ON(eb->h_suballoc_slot);
+			BUG_ON(el->l_recs[0].e_clusters);
+			BUG_ON(el->l_recs[0].e_cpos);
+			BUG_ON(el->l_recs[0].e_blkno);
+			status = ocfs2_free_extent_block(handle,
+							 tc->tc_ext_alloc_inode,
+							 tc->tc_ext_alloc_bh,
+							 eb);
+			if (status < 0) {
+				mlog_errno(status);
+				goto bail;
+			}
+		}
+		brelse(eb_bh);
+		eb_bh = NULL;
+		depth--;
+	}
+
+	BUG_ON(!delete_blk);
+	status = ocfs2_truncate_log_append(osb, handle, delete_blk,
+					   clusters_to_del);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	status = 0;
+bail:
+	if (!status)
+		ocfs2_extent_map_trunc(inode, le32_to_cpu(fe->i_clusters));
+	else
+		ocfs2_extent_map_drop(inode, 0);
+	mlog_exit(status);
+	return status;
+}
+
+/*
+ * 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 *fe_bh,
+			  struct ocfs2_truncate_context *tc)
+{
+	int status, i, credits, tl_sem = 0;
+	u32 clusters_to_del, target_i_clusters;
+	u64 last_eb = 0;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list *el;
+	struct buffer_head *last_eb_bh;
+	struct ocfs2_journal_handle *handle = NULL;
+	struct inode *tl_inode = osb->osb_tl_inode;
+
+	mlog_entry_void();
+
+	down_write(&OCFS2_I(inode)->ip_alloc_sem);
+
+	target_i_clusters = ocfs2_clusters_for_bytes(osb->sb,
+						     i_size_read(inode));
+
+	last_eb_bh = tc->tc_last_eb_bh;
+	tc->tc_last_eb_bh = NULL;
+
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+
+	if (fe->id2.i_list.l_tree_depth) {
+		eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
+		el = &eb->h_list;
+	} else
+		el = &fe->id2.i_list;
+	last_eb = le64_to_cpu(fe->i_last_eb_blk);
+start:
+	mlog(0, "ocfs2_commit_truncate: fe->i_clusters = %u, "
+	     "last_eb = %"MLFu64", fe->i_last_eb_blk = %"MLFu64", "
+	     "fe->id2.i_list.l_tree_depth = %u last_eb_bh = %p\n",
+	     le32_to_cpu(fe->i_clusters), last_eb,
+	     le64_to_cpu(fe->i_last_eb_blk),
+	     le16_to_cpu(fe->id2.i_list.l_tree_depth), last_eb_bh);
+
+	if (last_eb != le64_to_cpu(fe->i_last_eb_blk)) {
+		mlog(0, "last_eb changed!\n");
+		BUG_ON(!fe->id2.i_list.l_tree_depth);
+		last_eb = le64_to_cpu(fe->i_last_eb_blk);
+		/* i_last_eb_blk may have changed, read it if
+		 * necessary. We don't have to worry about the
+		 * truncate to zero case here (where there becomes no
+		 * last_eb) because we never loop back after our work
+		 * is done. */
+		if (last_eb_bh) {
+			brelse(last_eb_bh);
+			last_eb_bh = NULL;
+		}
+
+		status = ocfs2_read_block(osb, last_eb,
+					  &last_eb_bh, OCFS2_BH_CACHED,
+					  inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
+		if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+			OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+			status = -EIO;
+			goto bail;
+		}
+		el = &(eb->h_list);
+	}
+
+	/* by now, el will point to the extent list on the bottom most
+	 * portion of this tree. */
+	i = le16_to_cpu(el->l_next_free_rec) - 1;
+	if (le32_to_cpu(el->l_recs[i].e_cpos) >= target_i_clusters)
+		clusters_to_del = le32_to_cpu(el->l_recs[i].e_clusters);
+	else
+		clusters_to_del = (le32_to_cpu(el->l_recs[i].e_clusters) +
+				   le32_to_cpu(el->l_recs[i].e_cpos)) -
+				  target_i_clusters;
+
+	mlog(0, "clusters_to_del = %u in this pass\n", clusters_to_del);
+
+	down(&tl_inode->i_sem);
+	tl_sem = 1;
+	/* ocfs2_truncate_log_needs_flush guarantees us at least one
+	 * record is free for use. If there isn't any, we flush to get
+	 * an empty truncate log.  */
+	if (ocfs2_truncate_log_needs_flush(osb)) {
+		status = __ocfs2_flush_truncate_log(osb);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	credits = ocfs2_calc_tree_trunc_credits(osb->sb, clusters_to_del,
+						fe, el);
+	handle = ocfs2_start_trans(osb, NULL, credits);
+	if (IS_ERR(handle)) {
+		status = PTR_ERR(handle);
+		handle = NULL;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+	status = ocfs2_mark_inode_dirty(handle, inode, fe_bh);
+	if (status < 0)
+		mlog_errno(status);
+
+	status = ocfs2_do_truncate(osb, clusters_to_del, inode, fe_bh,
+				   last_eb_bh, handle, tc);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	up(&tl_inode->i_sem);
+	tl_sem = 0;
+
+	ocfs2_commit_trans(handle);
+	handle = NULL;
+
+	BUG_ON(le32_to_cpu(fe->i_clusters) < target_i_clusters);
+	if (le32_to_cpu(fe->i_clusters) > target_i_clusters)
+		goto start;
+bail:
+	up_write(&OCFS2_I(inode)->ip_alloc_sem);
+
+	ocfs2_schedule_truncate_log_flush(osb, 1);
+
+	if (tl_sem)
+		up(&tl_inode->i_sem);
+
+	if (handle)
+		ocfs2_commit_trans(handle);
+
+	if (last_eb_bh)
+		brelse(last_eb_bh);
+
+	/* This will drop the ext_alloc cluster lock for us */
+	ocfs2_free_truncate_context(tc);
+
+	mlog_exit(status);
+	return status;
+}
+
+
+/*
+ * Expects the inode to already be locked. This will figure out which
+ * inodes need to be locked and will put them on the returned truncate
+ * context.
+ */
+int ocfs2_prepare_truncate(struct ocfs2_super *osb,
+			   struct inode *inode,
+			   struct buffer_head *fe_bh,
+			   struct ocfs2_truncate_context **tc)
+{
+	int status, metadata_delete;
+	unsigned int new_i_clusters;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_extent_block *eb;
+	struct ocfs2_extent_list *el;
+	struct buffer_head *last_eb_bh = NULL;
+	struct inode *ext_alloc_inode = NULL;
+	struct buffer_head *ext_alloc_bh = NULL;
+
+	mlog_entry_void();
+
+	*tc = NULL;
+
+	new_i_clusters = ocfs2_clusters_for_bytes(osb->sb,
+						  i_size_read(inode));
+	fe = (struct ocfs2_dinode *) fe_bh->b_data;
+
+	mlog(0, "fe->i_clusters = %u, new_i_clusters = %u, fe->i_size ="
+	     "%"MLFu64"\n", fe->i_clusters, new_i_clusters, fe->i_size);
+
+	if (le32_to_cpu(fe->i_clusters) <= new_i_clusters) {
+		ocfs2_error(inode->i_sb, "Dinode %"MLFu64" has cluster count "
+			    "%u and size %"MLFu64" whereas struct inode has "
+			    "cluster count %u and size %llu which caused an "
+			    "invalid truncate to %u clusters.",
+			    le64_to_cpu(fe->i_blkno),
+			    le32_to_cpu(fe->i_clusters),
+			    le64_to_cpu(fe->i_size),
+			    OCFS2_I(inode)->ip_clusters, i_size_read(inode),
+			    new_i_clusters);
+		mlog_meta_lvb(ML_ERROR, &OCFS2_I(inode)->ip_meta_lockres);
+		status = -EIO;
+		goto bail;
+	}
+
+	*tc = kcalloc(1, sizeof(struct ocfs2_truncate_context), GFP_KERNEL);
+	if (!(*tc)) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	metadata_delete = 0;
+	if (fe->id2.i_list.l_tree_depth) {
+		/* If we have a tree, then the truncate may result in
+		 * metadata deletes. Figure this out from the
+		 * rightmost leaf block.*/
+		status = ocfs2_read_block(osb, le64_to_cpu(fe->i_last_eb_blk),
+					  &last_eb_bh, OCFS2_BH_CACHED, inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
+		if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+			OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+
+			brelse(last_eb_bh);
+			status = -EIO;
+			goto bail;
+		}
+		el = &(eb->h_list);
+		if (le32_to_cpu(el->l_recs[0].e_cpos) >= new_i_clusters)
+			metadata_delete = 1;
+	}
+
+	(*tc)->tc_last_eb_bh = last_eb_bh;
+
+	if (metadata_delete) {
+		mlog(0, "Will have to delete metadata for this trunc. "
+		     "locking allocator.\n");
+		ext_alloc_inode = ocfs2_get_system_file_inode(osb, EXTENT_ALLOC_SYSTEM_INODE, 0);
+		if (!ext_alloc_inode) {
+			status = -ENOMEM;
+			mlog_errno(status);
+			goto bail;
+		}
+
+		down(&ext_alloc_inode->i_sem);
+		(*tc)->tc_ext_alloc_inode = ext_alloc_inode;
+
+		status = ocfs2_meta_lock(ext_alloc_inode,
+					 NULL,
+					 &ext_alloc_bh,
+					 1);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		(*tc)->tc_ext_alloc_bh = ext_alloc_bh;
+		(*tc)->tc_ext_alloc_locked = 1;
+	}
+
+	status = 0;
+bail:
+	if (status < 0) {
+		if (*tc)
+			ocfs2_free_truncate_context(*tc);
+		*tc = NULL;
+	}
+	mlog_exit_void();
+	return status;
+}
+
+static void ocfs2_free_truncate_context(struct ocfs2_truncate_context *tc)
+{
+	if (tc->tc_ext_alloc_inode) {
+		if (tc->tc_ext_alloc_locked)
+			ocfs2_meta_unlock(tc->tc_ext_alloc_inode, 1);
+
+		up(&tc->tc_ext_alloc_inode->i_sem);
+		iput(tc->tc_ext_alloc_inode);
+	}
+
+	if (tc->tc_ext_alloc_bh)
+		brelse(tc->tc_ext_alloc_bh);
+
+	if (tc->tc_last_eb_bh)
+		brelse(tc->tc_last_eb_bh);
+
+	kfree(tc);
+}