Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2868 insertions, 0 deletions

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
new file mode 100644
index 000000000..4f48003e4
--- /dev/null
+++ b/fs/ocfs2/suballoc.c
@@ -0,0 +1,2868 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * suballoc.c
+ *
+ * metadata alloc and free
+ * Inspired by ext3 block groups.
+ *
+ * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+
+#include "alloc.h"
+#include "blockcheck.h"
+#include "dlmglue.h"
+#include "inode.h"
+#include "journal.h"
+#include "localalloc.h"
+#include "suballoc.h"
+#include "super.h"
+#include "sysfile.h"
+#include "uptodate.h"
+#include "ocfs2_trace.h"
+
+#include "buffer_head_io.h"
+
+#define NOT_ALLOC_NEW_GROUP		0
+#define ALLOC_NEW_GROUP			0x1
+#define ALLOC_GROUPS_FROM_GLOBAL	0x2
+
+#define OCFS2_MAX_TO_STEAL		1024
+
+struct ocfs2_suballoc_result {
+	u64		sr_bg_blkno;	/* The bg we allocated from.  Set
+					   to 0 when a block group is
+					   contiguous. */
+	u64		sr_bg_stable_blkno; /*
+					     * Doesn't change, always
+					     * set to target block
+					     * group descriptor
+					     * block.
+					     */
+	u64		sr_blkno;	/* The first allocated block */
+	unsigned int	sr_bit_offset;	/* The bit in the bg */
+	unsigned int	sr_bits;	/* How many bits we claimed */
+};
+
+static u64 ocfs2_group_from_res(struct ocfs2_suballoc_result *res)
+{
+	if (res->sr_blkno == 0)
+		return 0;
+
+	if (res->sr_bg_blkno)
+		return res->sr_bg_blkno;
+
+	return ocfs2_which_suballoc_group(res->sr_blkno, res->sr_bit_offset);
+}
+
+static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
+static int ocfs2_block_group_fill(handle_t *handle,
+				  struct inode *alloc_inode,
+				  struct buffer_head *bg_bh,
+				  u64 group_blkno,
+				  unsigned int group_clusters,
+				  u16 my_chain,
+				  struct ocfs2_chain_list *cl);
+static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
+				   struct inode *alloc_inode,
+				   struct buffer_head *bh,
+				   u64 max_block,
+				   u64 *last_alloc_group,
+				   int flags);
+
+static int ocfs2_cluster_group_search(struct inode *inode,
+				      struct buffer_head *group_bh,
+				      u32 bits_wanted, u32 min_bits,
+				      u64 max_block,
+				      struct ocfs2_suballoc_result *res);
+static int ocfs2_block_group_search(struct inode *inode,
+				    struct buffer_head *group_bh,
+				    u32 bits_wanted, u32 min_bits,
+				    u64 max_block,
+				    struct ocfs2_suballoc_result *res);
+static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
+				     handle_t *handle,
+				     u32 bits_wanted,
+				     u32 min_bits,
+				     struct ocfs2_suballoc_result *res);
+static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
+					 int nr);
+static int ocfs2_relink_block_group(handle_t *handle,
+				    struct inode *alloc_inode,
+				    struct buffer_head *fe_bh,
+				    struct buffer_head *bg_bh,
+				    struct buffer_head *prev_bg_bh,
+				    u16 chain);
+static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg,
+						     u32 wanted);
+static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
+						   u64 bg_blkno,
+						   u16 bg_bit_off);
+static inline void ocfs2_block_to_cluster_group(struct inode *inode,
+						u64 data_blkno,
+						u64 *bg_blkno,
+						u16 *bg_bit_off);
+static int ocfs2_reserve_clusters_with_limit(struct ocfs2_super *osb,
+					     u32 bits_wanted, u64 max_block,
+					     int flags,
+					     struct ocfs2_alloc_context **ac);
+
+void ocfs2_free_ac_resource(struct ocfs2_alloc_context *ac)
+{
+	struct inode *inode = ac->ac_inode;
+
+	if (inode) {
+		if (ac->ac_which != OCFS2_AC_USE_LOCAL)
+			ocfs2_inode_unlock(inode, 1);
+
+		inode_unlock(inode);
+
+		iput(inode);
+		ac->ac_inode = NULL;
+	}
+	brelse(ac->ac_bh);
+	ac->ac_bh = NULL;
+	ac->ac_resv = NULL;
+	kfree(ac->ac_find_loc_priv);
+	ac->ac_find_loc_priv = NULL;
+}
+
+void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
+{
+	ocfs2_free_ac_resource(ac);
+	kfree(ac);
+}
+
+static u32 ocfs2_bits_per_group(struct ocfs2_chain_list *cl)
+{
+	return (u32)le16_to_cpu(cl->cl_cpg) * (u32)le16_to_cpu(cl->cl_bpc);
+}
+
+#define do_error(fmt, ...)						\
+do {									\
+	if (resize)							\
+		mlog(ML_ERROR, fmt, ##__VA_ARGS__);			\
+	else								\
+		return ocfs2_error(sb, fmt, ##__VA_ARGS__);		\
+} while (0)
+
+static int ocfs2_validate_gd_self(struct super_block *sb,
+				  struct buffer_head *bh,
+				  int resize)
+{
+	struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+
+	if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
+		do_error("Group descriptor #%llu has bad signature %.*s\n",
+			 (unsigned long long)bh->b_blocknr, 7,
+			 gd->bg_signature);
+	}
+
+	if (le64_to_cpu(gd->bg_blkno) != bh->b_blocknr) {
+		do_error("Group descriptor #%llu has an invalid bg_blkno of %llu\n",
+			 (unsigned long long)bh->b_blocknr,
+			 (unsigned long long)le64_to_cpu(gd->bg_blkno));
+	}
+
+	if (le32_to_cpu(gd->bg_generation) != OCFS2_SB(sb)->fs_generation) {
+		do_error("Group descriptor #%llu has an invalid fs_generation of #%u\n",
+			 (unsigned long long)bh->b_blocknr,
+			 le32_to_cpu(gd->bg_generation));
+	}
+
+	if (le16_to_cpu(gd->bg_free_bits_count) > le16_to_cpu(gd->bg_bits)) {
+		do_error("Group descriptor #%llu has bit count %u but claims that %u are free\n",
+			 (unsigned long long)bh->b_blocknr,
+			 le16_to_cpu(gd->bg_bits),
+			 le16_to_cpu(gd->bg_free_bits_count));
+	}
+
+	if (le16_to_cpu(gd->bg_bits) > (8 * le16_to_cpu(gd->bg_size))) {
+		do_error("Group descriptor #%llu has bit count %u but max bitmap bits of %u\n",
+			 (unsigned long long)bh->b_blocknr,
+			 le16_to_cpu(gd->bg_bits),
+			 8 * le16_to_cpu(gd->bg_size));
+	}
+
+	return 0;
+}
+
+static int ocfs2_validate_gd_parent(struct super_block *sb,
+				    struct ocfs2_dinode *di,
+				    struct buffer_head *bh,
+				    int resize)
+{
+	unsigned int max_bits;
+	struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+
+	if (di->i_blkno != gd->bg_parent_dinode) {
+		do_error("Group descriptor #%llu has bad parent pointer (%llu, expected %llu)\n",
+			 (unsigned long long)bh->b_blocknr,
+			 (unsigned long long)le64_to_cpu(gd->bg_parent_dinode),
+			 (unsigned long long)le64_to_cpu(di->i_blkno));
+	}
+
+	max_bits = le16_to_cpu(di->id2.i_chain.cl_cpg) * le16_to_cpu(di->id2.i_chain.cl_bpc);
+	if (le16_to_cpu(gd->bg_bits) > max_bits) {
+		do_error("Group descriptor #%llu has bit count of %u\n",
+			 (unsigned long long)bh->b_blocknr,
+			 le16_to_cpu(gd->bg_bits));
+	}
+
+	/* In resize, we may meet the case bg_chain == cl_next_free_rec. */
+	if ((le16_to_cpu(gd->bg_chain) >
+	     le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) ||
+	    ((le16_to_cpu(gd->bg_chain) ==
+	     le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) && !resize)) {
+		do_error("Group descriptor #%llu has bad chain %u\n",
+			 (unsigned long long)bh->b_blocknr,
+			 le16_to_cpu(gd->bg_chain));
+	}
+
+	return 0;
+}
+
+#undef do_error
+
+/*
+ * This version only prints errors.  It does not fail the filesystem, and
+ * exists only for resize.
+ */
+int ocfs2_check_group_descriptor(struct super_block *sb,
+				 struct ocfs2_dinode *di,
+				 struct buffer_head *bh)
+{
+	int rc;
+	struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+
+	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, &gd->bg_check);
+	if (rc) {
+		mlog(ML_ERROR,
+		     "Checksum failed for group descriptor %llu\n",
+		     (unsigned long long)bh->b_blocknr);
+	} else
+		rc = ocfs2_validate_gd_self(sb, bh, 1);
+	if (!rc)
+		rc = ocfs2_validate_gd_parent(sb, di, bh, 1);
+
+	return rc;
+}
+
+static int ocfs2_validate_group_descriptor(struct super_block *sb,
+					   struct buffer_head *bh)
+{
+	int rc;
+	struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+
+	trace_ocfs2_validate_group_descriptor(
+					(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, &gd->bg_check);
+	if (rc)
+		return rc;
+
+	/*
+	 * Errors after here are fatal.
+	 */
+
+	return ocfs2_validate_gd_self(sb, bh, 0);
+}
+
+int ocfs2_read_group_descriptor(struct inode *inode, struct ocfs2_dinode *di,
+				u64 gd_blkno, struct buffer_head **bh)
+{
+	int rc;
+	struct buffer_head *tmp = *bh;
+
+	rc = ocfs2_read_block(INODE_CACHE(inode), gd_blkno, &tmp,
+			      ocfs2_validate_group_descriptor);
+	if (rc)
+		goto out;
+
+	rc = ocfs2_validate_gd_parent(inode->i_sb, di, tmp, 0);
+	if (rc) {
+		brelse(tmp);
+		goto out;
+	}
+
+	/* If ocfs2_read_block() got us a new bh, pass it up. */
+	if (!*bh)
+		*bh = tmp;
+
+out:
+	return rc;
+}
+
+static void ocfs2_bg_discontig_add_extent(struct ocfs2_super *osb,
+					  struct ocfs2_group_desc *bg,
+					  struct ocfs2_chain_list *cl,
+					  u64 p_blkno, unsigned int clusters)
+{
+	struct ocfs2_extent_list *el = &bg->bg_list;
+	struct ocfs2_extent_rec *rec;
+
+	BUG_ON(!ocfs2_supports_discontig_bg(osb));
+	if (!el->l_next_free_rec)
+		el->l_count = cpu_to_le16(ocfs2_extent_recs_per_gd(osb->sb));
+	rec = &el->l_recs[le16_to_cpu(el->l_next_free_rec)];
+	rec->e_blkno = cpu_to_le64(p_blkno);
+	rec->e_cpos = cpu_to_le32(le16_to_cpu(bg->bg_bits) /
+				  le16_to_cpu(cl->cl_bpc));
+	rec->e_leaf_clusters = cpu_to_le16(clusters);
+	le16_add_cpu(&bg->bg_bits, clusters * le16_to_cpu(cl->cl_bpc));
+	le16_add_cpu(&bg->bg_free_bits_count,
+		     clusters * le16_to_cpu(cl->cl_bpc));
+	le16_add_cpu(&el->l_next_free_rec, 1);
+}
+
+static int ocfs2_block_group_fill(handle_t *handle,
+				  struct inode *alloc_inode,
+				  struct buffer_head *bg_bh,
+				  u64 group_blkno,
+				  unsigned int group_clusters,
+				  u16 my_chain,
+				  struct ocfs2_chain_list *cl)
+{
+	int status = 0;
+	struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
+	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
+	struct super_block * sb = alloc_inode->i_sb;
+
+	if (((unsigned long long) bg_bh->b_blocknr) != group_blkno) {
+		status = ocfs2_error(alloc_inode->i_sb,
+				     "group block (%llu) != b_blocknr (%llu)\n",
+				     (unsigned long long)group_blkno,
+				     (unsigned long long) bg_bh->b_blocknr);
+		goto bail;
+	}
+
+	status = ocfs2_journal_access_gd(handle,
+					 INODE_CACHE(alloc_inode),
+					 bg_bh,
+					 OCFS2_JOURNAL_ACCESS_CREATE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	memset(bg, 0, sb->s_blocksize);
+	strcpy(bg->bg_signature, OCFS2_GROUP_DESC_SIGNATURE);
+	bg->bg_generation = cpu_to_le32(osb->fs_generation);
+	bg->bg_size = cpu_to_le16(ocfs2_group_bitmap_size(sb, 1,
+						osb->s_feature_incompat));
+	bg->bg_chain = cpu_to_le16(my_chain);
+	bg->bg_next_group = cl->cl_recs[my_chain].c_blkno;
+	bg->bg_parent_dinode = cpu_to_le64(OCFS2_I(alloc_inode)->ip_blkno);
+	bg->bg_blkno = cpu_to_le64(group_blkno);
+	if (group_clusters == le16_to_cpu(cl->cl_cpg))
+		bg->bg_bits = cpu_to_le16(ocfs2_bits_per_group(cl));
+	else
+		ocfs2_bg_discontig_add_extent(osb, bg, cl, group_blkno,
+					      group_clusters);
+
+	/* set the 1st bit in the bitmap to account for the descriptor block */
+	ocfs2_set_bit(0, (unsigned long *)bg->bg_bitmap);
+	bg->bg_free_bits_count = cpu_to_le16(le16_to_cpu(bg->bg_bits) - 1);
+
+	ocfs2_journal_dirty(handle, bg_bh);
+
+	/* There is no need to zero out or otherwise initialize the
+	 * other blocks in a group - All valid FS metadata in a block
+	 * group stores the superblock fs_generation value at
+	 * allocation time. */
+
+bail:
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+static inline u16 ocfs2_find_smallest_chain(struct ocfs2_chain_list *cl)
+{
+	u16 curr, best;
+
+	best = curr = 0;
+	while (curr < le16_to_cpu(cl->cl_count)) {
+		if (le32_to_cpu(cl->cl_recs[best].c_total) >
+		    le32_to_cpu(cl->cl_recs[curr].c_total))
+			best = curr;
+		curr++;
+	}
+	return best;
+}
+
+static struct buffer_head *
+ocfs2_block_group_alloc_contig(struct ocfs2_super *osb, handle_t *handle,
+			       struct inode *alloc_inode,
+			       struct ocfs2_alloc_context *ac,
+			       struct ocfs2_chain_list *cl)
+{
+	int status;
+	u32 bit_off, num_bits;
+	u64 bg_blkno;
+	struct buffer_head *bg_bh;
+	unsigned int alloc_rec = ocfs2_find_smallest_chain(cl);
+
+	status = ocfs2_claim_clusters(handle, ac,
+				      le16_to_cpu(cl->cl_cpg), &bit_off,
+				      &num_bits);
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	/* setup the group */
+	bg_blkno = ocfs2_clusters_to_blocks(osb->sb, bit_off);
+	trace_ocfs2_block_group_alloc_contig(
+	     (unsigned long long)bg_blkno, alloc_rec);
+
+	bg_bh = sb_getblk(osb->sb, bg_blkno);
+	if (!bg_bh) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+	ocfs2_set_new_buffer_uptodate(INODE_CACHE(alloc_inode), bg_bh);
+
+	status = ocfs2_block_group_fill(handle, alloc_inode, bg_bh,
+					bg_blkno, num_bits, alloc_rec, cl);
+	if (status < 0) {
+		brelse(bg_bh);
+		mlog_errno(status);
+	}
+
+bail:
+	return status ? ERR_PTR(status) : bg_bh;
+}
+
+static int ocfs2_block_group_claim_bits(struct ocfs2_super *osb,
+					handle_t *handle,
+					struct ocfs2_alloc_context *ac,
+					unsigned int min_bits,
+					u32 *bit_off, u32 *num_bits)
+{
+	int status = 0;
+
+	while (min_bits) {
+		status = ocfs2_claim_clusters(handle, ac, min_bits,
+					      bit_off, num_bits);
+		if (status != -ENOSPC)
+			break;
+
+		min_bits >>= 1;
+	}
+
+	return status;
+}
+
+static int ocfs2_block_group_grow_discontig(handle_t *handle,
+					    struct inode *alloc_inode,
+					    struct buffer_head *bg_bh,
+					    struct ocfs2_alloc_context *ac,
+					    struct ocfs2_chain_list *cl,
+					    unsigned int min_bits)
+{
+	int status;
+	struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
+	struct ocfs2_group_desc *bg =
+		(struct ocfs2_group_desc *)bg_bh->b_data;
+	unsigned int needed = le16_to_cpu(cl->cl_cpg) -
+			 le16_to_cpu(bg->bg_bits) / le16_to_cpu(cl->cl_bpc);
+	u32 p_cpos, clusters;
+	u64 p_blkno;
+	struct ocfs2_extent_list *el = &bg->bg_list;
+
+	status = ocfs2_journal_access_gd(handle,
+					 INODE_CACHE(alloc_inode),
+					 bg_bh,
+					 OCFS2_JOURNAL_ACCESS_CREATE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	while ((needed > 0) && (le16_to_cpu(el->l_next_free_rec) <
+				le16_to_cpu(el->l_count))) {
+		if (min_bits > needed)
+			min_bits = needed;
+		status = ocfs2_block_group_claim_bits(osb, handle, ac,
+						      min_bits, &p_cpos,
+						      &clusters);
+		if (status < 0) {
+			if (status != -ENOSPC)
+				mlog_errno(status);
+			goto bail;
+		}
+		p_blkno = ocfs2_clusters_to_blocks(osb->sb, p_cpos);
+		ocfs2_bg_discontig_add_extent(osb, bg, cl, p_blkno,
+					      clusters);
+
+		min_bits = clusters;
+		needed = le16_to_cpu(cl->cl_cpg) -
+			 le16_to_cpu(bg->bg_bits) / le16_to_cpu(cl->cl_bpc);
+	}
+
+	if (needed > 0) {
+		/*
+		 * We have used up all the extent rec but can't fill up
+		 * the cpg. So bail out.
+		 */
+		status = -ENOSPC;
+		goto bail;
+	}
+
+	ocfs2_journal_dirty(handle, bg_bh);
+
+bail:
+	return status;
+}
+
+static void ocfs2_bg_alloc_cleanup(handle_t *handle,
+				   struct ocfs2_alloc_context *cluster_ac,
+				   struct inode *alloc_inode,
+				   struct buffer_head *bg_bh)
+{
+	int i, ret;
+	struct ocfs2_group_desc *bg;
+	struct ocfs2_extent_list *el;
+	struct ocfs2_extent_rec *rec;
+
+	if (!bg_bh)
+		return;
+
+	bg = (struct ocfs2_group_desc *)bg_bh->b_data;
+	el = &bg->bg_list;
+	for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
+		rec = &el->l_recs[i];
+		ret = ocfs2_free_clusters(handle, cluster_ac->ac_inode,
+					  cluster_ac->ac_bh,
+					  le64_to_cpu(rec->e_blkno),
+					  le16_to_cpu(rec->e_leaf_clusters));
+		if (ret)
+			mlog_errno(ret);
+		/* Try all the clusters to free */
+	}
+
+	ocfs2_remove_from_cache(INODE_CACHE(alloc_inode), bg_bh);
+	brelse(bg_bh);
+}
+
+static struct buffer_head *
+ocfs2_block_group_alloc_discontig(handle_t *handle,
+				  struct inode *alloc_inode,
+				  struct ocfs2_alloc_context *ac,
+				  struct ocfs2_chain_list *cl)
+{
+	int status;
+	u32 bit_off, num_bits;
+	u64 bg_blkno;
+	unsigned int min_bits = le16_to_cpu(cl->cl_cpg) >> 1;
+	struct buffer_head *bg_bh = NULL;
+	unsigned int alloc_rec = ocfs2_find_smallest_chain(cl);
+	struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
+
+	if (!ocfs2_supports_discontig_bg(osb)) {
+		status = -ENOSPC;
+		goto bail;
+	}
+
+	status = ocfs2_extend_trans(handle,
+				    ocfs2_calc_bg_discontig_credits(osb->sb));
+	if (status) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/*
+	 * We're going to be grabbing from multiple cluster groups.
+	 * We don't have enough credits to relink them all, and the
+	 * cluster groups will be staying in cache for the duration of
+	 * this operation.
+	 */
+	ac->ac_disable_chain_relink = 1;
+
+	/* Claim the first region */
+	status = ocfs2_block_group_claim_bits(osb, handle, ac, min_bits,
+					      &bit_off, &num_bits);
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+	min_bits = num_bits;
+
+	/* setup the group */
+	bg_blkno = ocfs2_clusters_to_blocks(osb->sb, bit_off);
+	trace_ocfs2_block_group_alloc_discontig(
+				(unsigned long long)bg_blkno, alloc_rec);
+
+	bg_bh = sb_getblk(osb->sb, bg_blkno);
+	if (!bg_bh) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+	ocfs2_set_new_buffer_uptodate(INODE_CACHE(alloc_inode), bg_bh);
+
+	status = ocfs2_block_group_fill(handle, alloc_inode, bg_bh,
+					bg_blkno, num_bits, alloc_rec, cl);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = ocfs2_block_group_grow_discontig(handle, alloc_inode,
+						  bg_bh, ac, cl, min_bits);
+	if (status)
+		mlog_errno(status);
+
+bail:
+	if (status)
+		ocfs2_bg_alloc_cleanup(handle, ac, alloc_inode, bg_bh);
+	return status ? ERR_PTR(status) : bg_bh;
+}
+
+/*
+ * We expect the block group allocator to already be locked.
+ */
+static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
+				   struct inode *alloc_inode,
+				   struct buffer_head *bh,
+				   u64 max_block,
+				   u64 *last_alloc_group,
+				   int flags)
+{
+	int status, credits;
+	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) bh->b_data;
+	struct ocfs2_chain_list *cl;
+	struct ocfs2_alloc_context *ac = NULL;
+	handle_t *handle = NULL;
+	u16 alloc_rec;
+	struct buffer_head *bg_bh = NULL;
+	struct ocfs2_group_desc *bg;
+
+	BUG_ON(ocfs2_is_cluster_bitmap(alloc_inode));
+
+	cl = &fe->id2.i_chain;
+	status = ocfs2_reserve_clusters_with_limit(osb,
+						   le16_to_cpu(cl->cl_cpg),
+						   max_block, flags, &ac);
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	credits = ocfs2_calc_group_alloc_credits(osb->sb,
+						 le16_to_cpu(cl->cl_cpg));
+	handle = ocfs2_start_trans(osb, credits);
+	if (IS_ERR(handle)) {
+		status = PTR_ERR(handle);
+		handle = NULL;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	if (last_alloc_group && *last_alloc_group != 0) {
+		trace_ocfs2_block_group_alloc(
+				(unsigned long long)*last_alloc_group);
+		ac->ac_last_group = *last_alloc_group;
+	}
+
+	bg_bh = ocfs2_block_group_alloc_contig(osb, handle, alloc_inode,
+					       ac, cl);
+	if (PTR_ERR(bg_bh) == -ENOSPC)
+		bg_bh = ocfs2_block_group_alloc_discontig(handle,
+							  alloc_inode,
+							  ac, cl);
+	if (IS_ERR(bg_bh)) {
+		status = PTR_ERR(bg_bh);
+		bg_bh = NULL;
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+	bg = (struct ocfs2_group_desc *) bg_bh->b_data;
+
+	status = ocfs2_journal_access_di(handle, INODE_CACHE(alloc_inode),
+					 bh, OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	alloc_rec = le16_to_cpu(bg->bg_chain);
+	le32_add_cpu(&cl->cl_recs[alloc_rec].c_free,
+		     le16_to_cpu(bg->bg_free_bits_count));
+	le32_add_cpu(&cl->cl_recs[alloc_rec].c_total,
+		     le16_to_cpu(bg->bg_bits));
+	cl->cl_recs[alloc_rec].c_blkno = bg->bg_blkno;
+	if (le16_to_cpu(cl->cl_next_free_rec) < le16_to_cpu(cl->cl_count))
+		le16_add_cpu(&cl->cl_next_free_rec, 1);
+
+	le32_add_cpu(&fe->id1.bitmap1.i_used, le16_to_cpu(bg->bg_bits) -
+					le16_to_cpu(bg->bg_free_bits_count));
+	le32_add_cpu(&fe->id1.bitmap1.i_total, le16_to_cpu(bg->bg_bits));
+	le32_add_cpu(&fe->i_clusters, le16_to_cpu(cl->cl_cpg));
+
+	ocfs2_journal_dirty(handle, bh);
+
+	spin_lock(&OCFS2_I(alloc_inode)->ip_lock);
+	OCFS2_I(alloc_inode)->ip_clusters = le32_to_cpu(fe->i_clusters);
+	fe->i_size = cpu_to_le64(ocfs2_clusters_to_bytes(alloc_inode->i_sb,
+					     le32_to_cpu(fe->i_clusters)));
+	spin_unlock(&OCFS2_I(alloc_inode)->ip_lock);
+	i_size_write(alloc_inode, le64_to_cpu(fe->i_size));
+	alloc_inode->i_blocks = ocfs2_inode_sector_count(alloc_inode);
+	ocfs2_update_inode_fsync_trans(handle, alloc_inode, 0);
+
+	status = 0;
+
+	/* save the new last alloc group so that the caller can cache it. */
+	if (last_alloc_group)
+		*last_alloc_group = ac->ac_last_group;
+
+bail:
+	if (handle)
+		ocfs2_commit_trans(osb, handle);
+
+	if (ac)
+		ocfs2_free_alloc_context(ac);
+
+	brelse(bg_bh);
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
+				       struct ocfs2_alloc_context *ac,
+				       int type,
+				       u32 slot,
+				       u64 *last_alloc_group,
+				       int flags)
+{
+	int status;
+	u32 bits_wanted = ac->ac_bits_wanted;
+	struct inode *alloc_inode;
+	struct buffer_head *bh = NULL;
+	struct ocfs2_dinode *fe;
+	u32 free_bits;
+
+	alloc_inode = ocfs2_get_system_file_inode(osb, type, slot);
+	if (!alloc_inode) {
+		mlog_errno(-EINVAL);
+		return -EINVAL;
+	}
+
+	inode_lock(alloc_inode);
+
+	status = ocfs2_inode_lock(alloc_inode, &bh, 1);
+	if (status < 0) {
+		inode_unlock(alloc_inode);
+		iput(alloc_inode);
+
+		mlog_errno(status);
+		return status;
+	}
+
+	ac->ac_inode = alloc_inode;
+	ac->ac_alloc_slot = slot;
+
+	fe = (struct ocfs2_dinode *) bh->b_data;
+
+	/* The bh was validated by the inode read inside
+	 * ocfs2_inode_lock().  Any corruption is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
+
+	if (!(fe->i_flags & cpu_to_le32(OCFS2_CHAIN_FL))) {
+		status = ocfs2_error(alloc_inode->i_sb,
+				     "Invalid chain allocator %llu\n",
+				     (unsigned long long)le64_to_cpu(fe->i_blkno));
+		goto bail;
+	}
+
+	free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
+		le32_to_cpu(fe->id1.bitmap1.i_used);
+
+	if (bits_wanted > free_bits) {
+		/* cluster bitmap never grows */
+		if (ocfs2_is_cluster_bitmap(alloc_inode)) {
+			trace_ocfs2_reserve_suballoc_bits_nospc(bits_wanted,
+								free_bits);
+			status = -ENOSPC;
+			goto bail;
+		}
+
+		if (!(flags & ALLOC_NEW_GROUP)) {
+			trace_ocfs2_reserve_suballoc_bits_no_new_group(
+						slot, bits_wanted, free_bits);
+			status = -ENOSPC;
+			goto bail;
+		}
+
+		status = ocfs2_block_group_alloc(osb, alloc_inode, bh,
+						 ac->ac_max_block,
+						 last_alloc_group, flags);
+		if (status < 0) {
+			if (status != -ENOSPC)
+				mlog_errno(status);
+			goto bail;
+		}
+		atomic_inc(&osb->alloc_stats.bg_extends);
+
+		/* You should never ask for this much metadata */
+		BUG_ON(bits_wanted >
+		       (le32_to_cpu(fe->id1.bitmap1.i_total)
+			- le32_to_cpu(fe->id1.bitmap1.i_used)));
+	}
+
+	get_bh(bh);
+	ac->ac_bh = bh;
+bail:
+	brelse(bh);
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+static void ocfs2_init_inode_steal_slot(struct ocfs2_super *osb)
+{
+	spin_lock(&osb->osb_lock);
+	osb->s_inode_steal_slot = OCFS2_INVALID_SLOT;
+	spin_unlock(&osb->osb_lock);
+	atomic_set(&osb->s_num_inodes_stolen, 0);
+}
+
+static void ocfs2_init_meta_steal_slot(struct ocfs2_super *osb)
+{
+	spin_lock(&osb->osb_lock);
+	osb->s_meta_steal_slot = OCFS2_INVALID_SLOT;
+	spin_unlock(&osb->osb_lock);
+	atomic_set(&osb->s_num_meta_stolen, 0);
+}
+
+void ocfs2_init_steal_slots(struct ocfs2_super *osb)
+{
+	ocfs2_init_inode_steal_slot(osb);
+	ocfs2_init_meta_steal_slot(osb);
+}
+
+static void __ocfs2_set_steal_slot(struct ocfs2_super *osb, int slot, int type)
+{
+	spin_lock(&osb->osb_lock);
+	if (type == INODE_ALLOC_SYSTEM_INODE)
+		osb->s_inode_steal_slot = (u16)slot;
+	else if (type == EXTENT_ALLOC_SYSTEM_INODE)
+		osb->s_meta_steal_slot = (u16)slot;
+	spin_unlock(&osb->osb_lock);
+}
+
+static int __ocfs2_get_steal_slot(struct ocfs2_super *osb, int type)
+{
+	int slot = OCFS2_INVALID_SLOT;
+
+	spin_lock(&osb->osb_lock);
+	if (type == INODE_ALLOC_SYSTEM_INODE)
+		slot = osb->s_inode_steal_slot;
+	else if (type == EXTENT_ALLOC_SYSTEM_INODE)
+		slot = osb->s_meta_steal_slot;
+	spin_unlock(&osb->osb_lock);
+
+	return slot;
+}
+
+static int ocfs2_get_inode_steal_slot(struct ocfs2_super *osb)
+{
+	return __ocfs2_get_steal_slot(osb, INODE_ALLOC_SYSTEM_INODE);
+}
+
+static int ocfs2_get_meta_steal_slot(struct ocfs2_super *osb)
+{
+	return __ocfs2_get_steal_slot(osb, EXTENT_ALLOC_SYSTEM_INODE);
+}
+
+static int ocfs2_steal_resource(struct ocfs2_super *osb,
+				struct ocfs2_alloc_context *ac,
+				int type)
+{
+	int i, status = -ENOSPC;
+	int slot = __ocfs2_get_steal_slot(osb, type);
+
+	/* Start to steal resource from the first slot after ours. */
+	if (slot == OCFS2_INVALID_SLOT)
+		slot = osb->slot_num + 1;
+
+	for (i = 0; i < osb->max_slots; i++, slot++) {
+		if (slot == osb->max_slots)
+			slot = 0;
+
+		if (slot == osb->slot_num)
+			continue;
+
+		status = ocfs2_reserve_suballoc_bits(osb, ac,
+						     type,
+						     (u32)slot, NULL,
+						     NOT_ALLOC_NEW_GROUP);
+		if (status >= 0) {
+			__ocfs2_set_steal_slot(osb, slot, type);
+			break;
+		}
+
+		ocfs2_free_ac_resource(ac);
+	}
+
+	return status;
+}
+
+static int ocfs2_steal_inode(struct ocfs2_super *osb,
+			     struct ocfs2_alloc_context *ac)
+{
+	return ocfs2_steal_resource(osb, ac, INODE_ALLOC_SYSTEM_INODE);
+}
+
+static int ocfs2_steal_meta(struct ocfs2_super *osb,
+			    struct ocfs2_alloc_context *ac)
+{
+	return ocfs2_steal_resource(osb, ac, EXTENT_ALLOC_SYSTEM_INODE);
+}
+
+int ocfs2_reserve_new_metadata_blocks(struct ocfs2_super *osb,
+				      int blocks,
+				      struct ocfs2_alloc_context **ac)
+{
+	int status;
+	int slot = ocfs2_get_meta_steal_slot(osb);
+
+	*ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
+	if (!(*ac)) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	(*ac)->ac_bits_wanted = blocks;
+	(*ac)->ac_which = OCFS2_AC_USE_META;
+	(*ac)->ac_group_search = ocfs2_block_group_search;
+
+	if (slot != OCFS2_INVALID_SLOT &&
+		atomic_read(&osb->s_num_meta_stolen) < OCFS2_MAX_TO_STEAL)
+		goto extent_steal;
+
+	atomic_set(&osb->s_num_meta_stolen, 0);
+	status = ocfs2_reserve_suballoc_bits(osb, (*ac),
+					     EXTENT_ALLOC_SYSTEM_INODE,
+					     (u32)osb->slot_num, NULL,
+					     ALLOC_GROUPS_FROM_GLOBAL|ALLOC_NEW_GROUP);
+
+
+	if (status >= 0) {
+		status = 0;
+		if (slot != OCFS2_INVALID_SLOT)
+			ocfs2_init_meta_steal_slot(osb);
+		goto bail;
+	} else if (status < 0 && status != -ENOSPC) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	ocfs2_free_ac_resource(*ac);
+
+extent_steal:
+	status = ocfs2_steal_meta(osb, *ac);
+	atomic_inc(&osb->s_num_meta_stolen);
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	status = 0;
+bail:
+	if ((status < 0) && *ac) {
+		ocfs2_free_alloc_context(*ac);
+		*ac = NULL;
+	}
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+int ocfs2_reserve_new_metadata(struct ocfs2_super *osb,
+			       struct ocfs2_extent_list *root_el,
+			       struct ocfs2_alloc_context **ac)
+{
+	return ocfs2_reserve_new_metadata_blocks(osb,
+					ocfs2_extend_meta_needed(root_el),
+					ac);
+}
+
+int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
+			    struct ocfs2_alloc_context **ac)
+{
+	int status;
+	int slot = ocfs2_get_inode_steal_slot(osb);
+	u64 alloc_group;
+
+	*ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
+	if (!(*ac)) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	(*ac)->ac_bits_wanted = 1;
+	(*ac)->ac_which = OCFS2_AC_USE_INODE;
+
+	(*ac)->ac_group_search = ocfs2_block_group_search;
+
+	/*
+	 * stat(2) can't handle i_ino > 32bits, so we tell the
+	 * lower levels not to allocate us a block group past that
+	 * limit.  The 'inode64' mount option avoids this behavior.
+	 */
+	if (!(osb->s_mount_opt & OCFS2_MOUNT_INODE64))
+		(*ac)->ac_max_block = (u32)~0U;
+
+	/*
+	 * slot is set when we successfully steal inode from other nodes.
+	 * It is reset in 3 places:
+	 * 1. when we flush the truncate log
+	 * 2. when we complete local alloc recovery.
+	 * 3. when we successfully allocate from our own slot.
+	 * After it is set, we will go on stealing inodes until we find the
+	 * need to check our slots to see whether there is some space for us.
+	 */
+	if (slot != OCFS2_INVALID_SLOT &&
+	    atomic_read(&osb->s_num_inodes_stolen) < OCFS2_MAX_TO_STEAL)
+		goto inode_steal;
+
+	atomic_set(&osb->s_num_inodes_stolen, 0);
+	alloc_group = osb->osb_inode_alloc_group;
+	status = ocfs2_reserve_suballoc_bits(osb, *ac,
+					     INODE_ALLOC_SYSTEM_INODE,
+					     (u32)osb->slot_num,
+					     &alloc_group,
+					     ALLOC_NEW_GROUP |
+					     ALLOC_GROUPS_FROM_GLOBAL);
+	if (status >= 0) {
+		status = 0;
+
+		spin_lock(&osb->osb_lock);
+		osb->osb_inode_alloc_group = alloc_group;
+		spin_unlock(&osb->osb_lock);
+		trace_ocfs2_reserve_new_inode_new_group(
+			(unsigned long long)alloc_group);
+
+		/*
+		 * Some inodes must be freed by us, so try to allocate
+		 * from our own next time.
+		 */
+		if (slot != OCFS2_INVALID_SLOT)
+			ocfs2_init_inode_steal_slot(osb);
+		goto bail;
+	} else if (status < 0 && status != -ENOSPC) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	ocfs2_free_ac_resource(*ac);
+
+inode_steal:
+	status = ocfs2_steal_inode(osb, *ac);
+	atomic_inc(&osb->s_num_inodes_stolen);
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	status = 0;
+bail:
+	if ((status < 0) && *ac) {
+		ocfs2_free_alloc_context(*ac);
+		*ac = NULL;
+	}
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+/* local alloc code has to do the same thing, so rather than do this
+ * twice.. */
+int ocfs2_reserve_cluster_bitmap_bits(struct ocfs2_super *osb,
+				      struct ocfs2_alloc_context *ac)
+{
+	int status;
+
+	ac->ac_which = OCFS2_AC_USE_MAIN;
+	ac->ac_group_search = ocfs2_cluster_group_search;
+
+	status = ocfs2_reserve_suballoc_bits(osb, ac,
+					     GLOBAL_BITMAP_SYSTEM_INODE,
+					     OCFS2_INVALID_SLOT, NULL,
+					     ALLOC_NEW_GROUP);
+	if (status < 0 && status != -ENOSPC)
+		mlog_errno(status);
+
+	return status;
+}
+
+/* Callers don't need to care which bitmap (local alloc or main) to
+ * use so we figure it out for them, but unfortunately this clutters
+ * things a bit. */
+static int ocfs2_reserve_clusters_with_limit(struct ocfs2_super *osb,
+					     u32 bits_wanted, u64 max_block,
+					     int flags,
+					     struct ocfs2_alloc_context **ac)
+{
+	int status, ret = 0;
+	int retried = 0;
+
+	*ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
+	if (!(*ac)) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	(*ac)->ac_bits_wanted = bits_wanted;
+	(*ac)->ac_max_block = max_block;
+
+	status = -ENOSPC;
+	if (!(flags & ALLOC_GROUPS_FROM_GLOBAL) &&
+	    ocfs2_alloc_should_use_local(osb, bits_wanted)) {
+		status = ocfs2_reserve_local_alloc_bits(osb,
+							bits_wanted,
+							*ac);
+		if ((status < 0) && (status != -ENOSPC)) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	if (status == -ENOSPC) {
+retry:
+		status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);
+		/* Retry if there is sufficient space cached in truncate log */
+		if (status == -ENOSPC && !retried) {
+			retried = 1;
+			ocfs2_inode_unlock((*ac)->ac_inode, 1);
+			inode_unlock((*ac)->ac_inode);
+
+			ret = ocfs2_try_to_free_truncate_log(osb, bits_wanted);
+			if (ret == 1) {
+				iput((*ac)->ac_inode);
+				(*ac)->ac_inode = NULL;
+				goto retry;
+			}
+
+			if (ret < 0)
+				mlog_errno(ret);
+
+			inode_lock((*ac)->ac_inode);
+			ret = ocfs2_inode_lock((*ac)->ac_inode, NULL, 1);
+			if (ret < 0) {
+				mlog_errno(ret);
+				inode_unlock((*ac)->ac_inode);
+				iput((*ac)->ac_inode);
+				(*ac)->ac_inode = NULL;
+				goto bail;
+			}
+		}
+		if (status < 0) {
+			if (status != -ENOSPC)
+				mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	status = 0;
+bail:
+	if ((status < 0) && *ac) {
+		ocfs2_free_alloc_context(*ac);
+		*ac = NULL;
+	}
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+int ocfs2_reserve_clusters(struct ocfs2_super *osb,
+			   u32 bits_wanted,
+			   struct ocfs2_alloc_context **ac)
+{
+	return ocfs2_reserve_clusters_with_limit(osb, bits_wanted, 0,
+						 ALLOC_NEW_GROUP, ac);
+}
+
+/*
+ * More or less lifted from ext3. I'll leave their description below:
+ *
+ * "For ext3 allocations, we must not reuse any blocks which are
+ * allocated in the bitmap buffer's "last committed data" copy.  This
+ * prevents deletes from freeing up the page for reuse until we have
+ * committed the delete transaction.
+ *
+ * If we didn't do this, then deleting something and reallocating it as
+ * data would allow the old block to be overwritten before the
+ * transaction committed (because we force data to disk before commit).
+ * This would lead to corruption if we crashed between overwriting the
+ * data and committing the delete.
+ *
+ * @@@ We may want to make this allocation behaviour conditional on
+ * data-writes at some point, and disable it for metadata allocations or
+ * sync-data inodes."
+ *
+ * Note: OCFS2 already does this differently for metadata vs data
+ * allocations, as those bitmaps are separate and undo access is never
+ * called on a metadata group descriptor.
+ */
+static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
+					 int nr)
+{
+	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
+	struct journal_head *jh;
+	int ret;
+
+	if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
+		return 0;
+
+	jh = jbd2_journal_grab_journal_head(bg_bh);
+	if (!jh)
+		return 1;
+
+	spin_lock(&jh->b_state_lock);
+	bg = (struct ocfs2_group_desc *) jh->b_committed_data;
+	if (bg)
+		ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
+	else
+		ret = 1;
+	spin_unlock(&jh->b_state_lock);
+	jbd2_journal_put_journal_head(jh);
+
+	return ret;
+}
+
+static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
+					     struct buffer_head *bg_bh,
+					     unsigned int bits_wanted,
+					     unsigned int total_bits,
+					     struct ocfs2_suballoc_result *res)
+{
+	void *bitmap;
+	u16 best_offset, best_size;
+	int offset, start, found, status = 0;
+	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
+
+	/* Callers got this descriptor from
+	 * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
+
+	found = start = best_offset = best_size = 0;
+	bitmap = bg->bg_bitmap;
+
+	while((offset = ocfs2_find_next_zero_bit(bitmap, total_bits, start)) != -1) {
+		if (offset == total_bits)
+			break;
+
+		if (!ocfs2_test_bg_bit_allocatable(bg_bh, offset)) {
+			/* We found a zero, but we can't use it as it
+			 * hasn't been put to disk yet! */
+			found = 0;
+			start = offset + 1;
+		} else if (offset == start) {
+			/* we found a zero */
+			found++;
+			/* move start to the next bit to test */
+			start++;
+		} else {
+			/* got a zero after some ones */
+			found = 1;
+			start = offset + 1;
+		}
+		if (found > best_size) {
+			best_size = found;
+			best_offset = start - found;
+		}
+		/* we got everything we needed */
+		if (found == bits_wanted) {
+			/* mlog(0, "Found it all!\n"); */
+			break;
+		}
+	}
+
+	if (best_size) {
+		res->sr_bit_offset = best_offset;
+		res->sr_bits = best_size;
+	} else {
+		status = -ENOSPC;
+		/* No error log here -- see the comment above
+		 * ocfs2_test_bg_bit_allocatable */
+	}
+
+	return status;
+}
+
+int ocfs2_block_group_set_bits(handle_t *handle,
+					     struct inode *alloc_inode,
+					     struct ocfs2_group_desc *bg,
+					     struct buffer_head *group_bh,
+					     unsigned int bit_off,
+					     unsigned int num_bits)
+{
+	int status;
+	void *bitmap = bg->bg_bitmap;
+	int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
+
+	/* All callers get the descriptor via
+	 * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
+	BUG_ON(le16_to_cpu(bg->bg_free_bits_count) < num_bits);
+
+	trace_ocfs2_block_group_set_bits(bit_off, num_bits);
+
+	if (ocfs2_is_cluster_bitmap(alloc_inode))
+		journal_type = OCFS2_JOURNAL_ACCESS_UNDO;
+
+	status = ocfs2_journal_access_gd(handle,
+					 INODE_CACHE(alloc_inode),
+					 group_bh,
+					 journal_type);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	le16_add_cpu(&bg->bg_free_bits_count, -num_bits);
+	if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
+		return ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit count %u but claims %u are freed. num_bits %d\n",
+				   (unsigned long long)le64_to_cpu(bg->bg_blkno),
+				   le16_to_cpu(bg->bg_bits),
+				   le16_to_cpu(bg->bg_free_bits_count),
+				   num_bits);
+	}
+	while(num_bits--)
+		ocfs2_set_bit(bit_off++, bitmap);
+
+	ocfs2_journal_dirty(handle, group_bh);
+
+bail:
+	return status;
+}
+
+/* find the one with the most empty bits */
+static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl)
+{
+	u16 curr, best;
+
+	BUG_ON(!cl->cl_next_free_rec);
+
+	best = curr = 0;
+	while (curr < le16_to_cpu(cl->cl_next_free_rec)) {
+		if (le32_to_cpu(cl->cl_recs[curr].c_free) >
+		    le32_to_cpu(cl->cl_recs[best].c_free))
+			best = curr;
+		curr++;
+	}
+
+	BUG_ON(best >= le16_to_cpu(cl->cl_next_free_rec));
+	return best;
+}
+
+static int ocfs2_relink_block_group(handle_t *handle,
+				    struct inode *alloc_inode,
+				    struct buffer_head *fe_bh,
+				    struct buffer_head *bg_bh,
+				    struct buffer_head *prev_bg_bh,
+				    u16 chain)
+{
+	int status;
+	/* there is a really tiny chance the journal calls could fail,
+	 * but we wouldn't want inconsistent blocks in *any* case. */
+	u64 bg_ptr, prev_bg_ptr;
+	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) fe_bh->b_data;
+	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
+	struct ocfs2_group_desc *prev_bg = (struct ocfs2_group_desc *) prev_bg_bh->b_data;
+
+	/* The caller got these descriptors from
+	 * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
+	BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(prev_bg));
+
+	trace_ocfs2_relink_block_group(
+		(unsigned long long)le64_to_cpu(fe->i_blkno), chain,
+		(unsigned long long)le64_to_cpu(bg->bg_blkno),
+		(unsigned long long)le64_to_cpu(prev_bg->bg_blkno));
+
+	bg_ptr = le64_to_cpu(bg->bg_next_group);
+	prev_bg_ptr = le64_to_cpu(prev_bg->bg_next_group);
+
+	status = ocfs2_journal_access_gd(handle, INODE_CACHE(alloc_inode),
+					 prev_bg_bh,
+					 OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0)
+		goto out;
+
+	prev_bg->bg_next_group = bg->bg_next_group;
+	ocfs2_journal_dirty(handle, prev_bg_bh);
+
+	status = ocfs2_journal_access_gd(handle, INODE_CACHE(alloc_inode),
+					 bg_bh, OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0)
+		goto out_rollback_prev_bg;
+
+	bg->bg_next_group = fe->id2.i_chain.cl_recs[chain].c_blkno;
+	ocfs2_journal_dirty(handle, bg_bh);
+
+	status = ocfs2_journal_access_di(handle, INODE_CACHE(alloc_inode),
+					 fe_bh, OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0)
+		goto out_rollback_bg;
+
+	fe->id2.i_chain.cl_recs[chain].c_blkno = bg->bg_blkno;
+	ocfs2_journal_dirty(handle, fe_bh);
+
+out:
+	if (status < 0)
+		mlog_errno(status);
+	return status;
+
+out_rollback_bg:
+	bg->bg_next_group = cpu_to_le64(bg_ptr);
+out_rollback_prev_bg:
+	prev_bg->bg_next_group = cpu_to_le64(prev_bg_ptr);
+	goto out;
+}
+
+static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg,
+						     u32 wanted)
+{
+	return le16_to_cpu(bg->bg_free_bits_count) > wanted;
+}
+
+/* return 0 on success, -ENOSPC to keep searching and any other < 0
+ * value on error. */
+static int ocfs2_cluster_group_search(struct inode *inode,
+				      struct buffer_head *group_bh,
+				      u32 bits_wanted, u32 min_bits,
+				      u64 max_block,
+				      struct ocfs2_suballoc_result *res)
+{
+	int search = -ENOSPC;
+	int ret;
+	u64 blkoff;
+	struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *) group_bh->b_data;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	unsigned int max_bits, gd_cluster_off;
+
+	BUG_ON(!ocfs2_is_cluster_bitmap(inode));
+
+	if (gd->bg_free_bits_count) {
+		max_bits = le16_to_cpu(gd->bg_bits);
+
+		/* Tail groups in cluster bitmaps which aren't cpg
+		 * aligned are prone to partial extension by a failed
+		 * fs resize. If the file system resize never got to
+		 * update the dinode cluster count, then we don't want
+		 * to trust any clusters past it, regardless of what
+		 * the group descriptor says. */
+		gd_cluster_off = ocfs2_blocks_to_clusters(inode->i_sb,
+							  le64_to_cpu(gd->bg_blkno));
+		if ((gd_cluster_off + max_bits) >
+		    OCFS2_I(inode)->ip_clusters) {
+			max_bits = OCFS2_I(inode)->ip_clusters - gd_cluster_off;
+			trace_ocfs2_cluster_group_search_wrong_max_bits(
+				(unsigned long long)le64_to_cpu(gd->bg_blkno),
+				le16_to_cpu(gd->bg_bits),
+				OCFS2_I(inode)->ip_clusters, max_bits);
+		}
+
+		ret = ocfs2_block_group_find_clear_bits(osb,
+							group_bh, bits_wanted,
+							max_bits, res);
+		if (ret)
+			return ret;
+
+		if (max_block) {
+			blkoff = ocfs2_clusters_to_blocks(inode->i_sb,
+							  gd_cluster_off +
+							  res->sr_bit_offset +
+							  res->sr_bits);
+			trace_ocfs2_cluster_group_search_max_block(
+				(unsigned long long)blkoff,
+				(unsigned long long)max_block);
+			if (blkoff > max_block)
+				return -ENOSPC;
+		}
+
+		/* ocfs2_block_group_find_clear_bits() might
+		 * return success, but we still want to return
+		 * -ENOSPC unless it found the minimum number
+		 * of bits. */
+		if (min_bits <= res->sr_bits)
+			search = 0; /* success */
+		else if (res->sr_bits) {
+			/*
+			 * Don't show bits which we'll be returning
+			 * for allocation to the local alloc bitmap.
+			 */
+			ocfs2_local_alloc_seen_free_bits(osb, res->sr_bits);
+		}
+	}
+
+	return search;
+}
+
+static int ocfs2_block_group_search(struct inode *inode,
+				    struct buffer_head *group_bh,
+				    u32 bits_wanted, u32 min_bits,
+				    u64 max_block,
+				    struct ocfs2_suballoc_result *res)
+{
+	int ret = -ENOSPC;
+	u64 blkoff;
+	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) group_bh->b_data;
+
+	BUG_ON(min_bits != 1);
+	BUG_ON(ocfs2_is_cluster_bitmap(inode));
+
+	if (bg->bg_free_bits_count) {
+		ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
+							group_bh, bits_wanted,
+							le16_to_cpu(bg->bg_bits),
+							res);
+		if (!ret && max_block) {
+			blkoff = le64_to_cpu(bg->bg_blkno) +
+				res->sr_bit_offset + res->sr_bits;
+			trace_ocfs2_block_group_search_max_block(
+				(unsigned long long)blkoff,
+				(unsigned long long)max_block);
+			if (blkoff > max_block)
+				ret = -ENOSPC;
+		}
+	}
+
+	return ret;
+}
+
+int ocfs2_alloc_dinode_update_counts(struct inode *inode,
+				       handle_t *handle,
+				       struct buffer_head *di_bh,
+				       u32 num_bits,
+				       u16 chain)
+{
+	int ret;
+	u32 tmp_used;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *) di_bh->b_data;
+	struct ocfs2_chain_list *cl = (struct ocfs2_chain_list *) &di->id2.i_chain;
+
+	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (ret < 0) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	tmp_used = le32_to_cpu(di->id1.bitmap1.i_used);
+	di->id1.bitmap1.i_used = cpu_to_le32(num_bits + tmp_used);
+	le32_add_cpu(&cl->cl_recs[chain].c_free, -num_bits);
+	ocfs2_journal_dirty(handle, di_bh);
+
+out:
+	return ret;
+}
+
+void ocfs2_rollback_alloc_dinode_counts(struct inode *inode,
+				       struct buffer_head *di_bh,
+				       u32 num_bits,
+				       u16 chain)
+{
+	u32 tmp_used;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *) di_bh->b_data;
+	struct ocfs2_chain_list *cl;
+
+	cl = (struct ocfs2_chain_list *)&di->id2.i_chain;
+	tmp_used = le32_to_cpu(di->id1.bitmap1.i_used);
+	di->id1.bitmap1.i_used = cpu_to_le32(tmp_used - num_bits);
+	le32_add_cpu(&cl->cl_recs[chain].c_free, num_bits);
+}
+
+static int ocfs2_bg_discontig_fix_by_rec(struct ocfs2_suballoc_result *res,
+					 struct ocfs2_extent_rec *rec,
+					 struct ocfs2_chain_list *cl)
+{
+	unsigned int bpc = le16_to_cpu(cl->cl_bpc);
+	unsigned int bitoff = le32_to_cpu(rec->e_cpos) * bpc;
+	unsigned int bitcount = le16_to_cpu(rec->e_leaf_clusters) * bpc;
+
+	if (res->sr_bit_offset < bitoff)
+		return 0;
+	if (res->sr_bit_offset >= (bitoff + bitcount))
+		return 0;
+	res->sr_blkno = le64_to_cpu(rec->e_blkno) +
+		(res->sr_bit_offset - bitoff);
+	if ((res->sr_bit_offset + res->sr_bits) > (bitoff + bitcount))
+		res->sr_bits = (bitoff + bitcount) - res->sr_bit_offset;
+	return 1;
+}
+
+static void ocfs2_bg_discontig_fix_result(struct ocfs2_alloc_context *ac,
+					  struct ocfs2_group_desc *bg,
+					  struct ocfs2_suballoc_result *res)
+{
+	int i;
+	u64 bg_blkno = res->sr_bg_blkno;  /* Save off */
+	struct ocfs2_extent_rec *rec;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)ac->ac_bh->b_data;
+	struct ocfs2_chain_list *cl = &di->id2.i_chain;
+
+	if (ocfs2_is_cluster_bitmap(ac->ac_inode)) {
+		res->sr_blkno = 0;
+		return;
+	}
+
+	res->sr_blkno = res->sr_bg_blkno + res->sr_bit_offset;
+	res->sr_bg_blkno = 0;  /* Clear it for contig block groups */
+	if (!ocfs2_supports_discontig_bg(OCFS2_SB(ac->ac_inode->i_sb)) ||
+	    !bg->bg_list.l_next_free_rec)
+		return;
+
+	for (i = 0; i < le16_to_cpu(bg->bg_list.l_next_free_rec); i++) {
+		rec = &bg->bg_list.l_recs[i];
+		if (ocfs2_bg_discontig_fix_by_rec(res, rec, cl)) {
+			res->sr_bg_blkno = bg_blkno;  /* Restore */
+			break;
+		}
+	}
+}
+
+static int ocfs2_search_one_group(struct ocfs2_alloc_context *ac,
+				  handle_t *handle,
+				  u32 bits_wanted,
+				  u32 min_bits,
+				  struct ocfs2_suballoc_result *res,
+				  u16 *bits_left)
+{
+	int ret;
+	struct buffer_head *group_bh = NULL;
+	struct ocfs2_group_desc *gd;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)ac->ac_bh->b_data;
+	struct inode *alloc_inode = ac->ac_inode;
+
+	ret = ocfs2_read_group_descriptor(alloc_inode, di,
+					  res->sr_bg_blkno, &group_bh);
+	if (ret < 0) {
+		mlog_errno(ret);
+		return ret;
+	}
+
+	gd = (struct ocfs2_group_desc *) group_bh->b_data;
+	ret = ac->ac_group_search(alloc_inode, group_bh, bits_wanted, min_bits,
+				  ac->ac_max_block, res);
+	if (ret < 0) {
+		if (ret != -ENOSPC)
+			mlog_errno(ret);
+		goto out;
+	}
+
+	if (!ret)
+		ocfs2_bg_discontig_fix_result(ac, gd, res);
+
+	/*
+	 * sr_bg_blkno might have been changed by
+	 * ocfs2_bg_discontig_fix_result
+	 */
+	res->sr_bg_stable_blkno = group_bh->b_blocknr;
+
+	if (ac->ac_find_loc_only)
+		goto out_loc_only;
+
+	ret = ocfs2_alloc_dinode_update_counts(alloc_inode, handle, ac->ac_bh,
+					       res->sr_bits,
+					       le16_to_cpu(gd->bg_chain));
+	if (ret < 0) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ret = ocfs2_block_group_set_bits(handle, alloc_inode, gd, group_bh,
+					 res->sr_bit_offset, res->sr_bits);
+	if (ret < 0) {
+		ocfs2_rollback_alloc_dinode_counts(alloc_inode, ac->ac_bh,
+					       res->sr_bits,
+					       le16_to_cpu(gd->bg_chain));
+		mlog_errno(ret);
+	}
+
+out_loc_only:
+	*bits_left = le16_to_cpu(gd->bg_free_bits_count);
+
+out:
+	brelse(group_bh);
+
+	return ret;
+}
+
+static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
+			      handle_t *handle,
+			      u32 bits_wanted,
+			      u32 min_bits,
+			      struct ocfs2_suballoc_result *res,
+			      u16 *bits_left)
+{
+	int status;
+	u16 chain;
+	u64 next_group;
+	struct inode *alloc_inode = ac->ac_inode;
+	struct buffer_head *group_bh = NULL;
+	struct buffer_head *prev_group_bh = NULL;
+	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) ac->ac_bh->b_data;
+	struct ocfs2_chain_list *cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;
+	struct ocfs2_group_desc *bg;
+
+	chain = ac->ac_chain;
+	trace_ocfs2_search_chain_begin(
+		(unsigned long long)OCFS2_I(alloc_inode)->ip_blkno,
+		bits_wanted, chain);
+
+	status = ocfs2_read_group_descriptor(alloc_inode, fe,
+					     le64_to_cpu(cl->cl_recs[chain].c_blkno),
+					     &group_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	bg = (struct ocfs2_group_desc *) group_bh->b_data;
+
+	status = -ENOSPC;
+	/* for now, the chain search is a bit simplistic. We just use
+	 * the 1st group with any empty bits. */
+	while ((status = ac->ac_group_search(alloc_inode, group_bh,
+					     bits_wanted, min_bits,
+					     ac->ac_max_block,
+					     res)) == -ENOSPC) {
+		if (!bg->bg_next_group)
+			break;
+
+		brelse(prev_group_bh);
+		prev_group_bh = NULL;
+
+		next_group = le64_to_cpu(bg->bg_next_group);
+		prev_group_bh = group_bh;
+		group_bh = NULL;
+		status = ocfs2_read_group_descriptor(alloc_inode, fe,
+						     next_group, &group_bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+		bg = (struct ocfs2_group_desc *) group_bh->b_data;
+	}
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	trace_ocfs2_search_chain_succ(
+		(unsigned long long)le64_to_cpu(bg->bg_blkno), res->sr_bits);
+
+	res->sr_bg_blkno = le64_to_cpu(bg->bg_blkno);
+
+	BUG_ON(res->sr_bits == 0);
+	if (!status)
+		ocfs2_bg_discontig_fix_result(ac, bg, res);
+
+	/*
+	 * sr_bg_blkno might have been changed by
+	 * ocfs2_bg_discontig_fix_result
+	 */
+	res->sr_bg_stable_blkno = group_bh->b_blocknr;
+
+	/*
+	 * Keep track of previous block descriptor read. When
+	 * we find a target, if we have read more than X
+	 * number of descriptors, and the target is reasonably
+	 * empty, relink him to top of his chain.
+	 *
+	 * We've read 0 extra blocks and only send one more to
+	 * the transaction, yet the next guy to search has a
+	 * much easier time.
+	 *
+	 * Do this *after* figuring out how many bits we're taking out
+	 * of our target group.
+	 */
+	if (!ac->ac_disable_chain_relink &&
+	    (prev_group_bh) &&
+	    (ocfs2_block_group_reasonably_empty(bg, res->sr_bits))) {
+		status = ocfs2_relink_block_group(handle, alloc_inode,
+						  ac->ac_bh, group_bh,
+						  prev_group_bh, chain);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	if (ac->ac_find_loc_only)
+		goto out_loc_only;
+
+	status = ocfs2_alloc_dinode_update_counts(alloc_inode, handle,
+						  ac->ac_bh, res->sr_bits,
+						  chain);
+	if (status) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = ocfs2_block_group_set_bits(handle,
+					    alloc_inode,
+					    bg,
+					    group_bh,
+					    res->sr_bit_offset,
+					    res->sr_bits);
+	if (status < 0) {
+		ocfs2_rollback_alloc_dinode_counts(alloc_inode,
+					ac->ac_bh, res->sr_bits, chain);
+		mlog_errno(status);
+		goto bail;
+	}
+
+	trace_ocfs2_search_chain_end(
+			(unsigned long long)le64_to_cpu(fe->i_blkno),
+			res->sr_bits);
+
+out_loc_only:
+	*bits_left = le16_to_cpu(bg->bg_free_bits_count);
+bail:
+	brelse(group_bh);
+	brelse(prev_group_bh);
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+/* will give out up to bits_wanted contiguous bits. */
+static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
+				     handle_t *handle,
+				     u32 bits_wanted,
+				     u32 min_bits,
+				     struct ocfs2_suballoc_result *res)
+{
+	int status;
+	u16 victim, i;
+	u16 bits_left = 0;
+	u64 hint = ac->ac_last_group;
+	struct ocfs2_chain_list *cl;
+	struct ocfs2_dinode *fe;
+
+	BUG_ON(ac->ac_bits_given >= ac->ac_bits_wanted);
+	BUG_ON(bits_wanted > (ac->ac_bits_wanted - ac->ac_bits_given));
+	BUG_ON(!ac->ac_bh);
+
+	fe = (struct ocfs2_dinode *) ac->ac_bh->b_data;
+
+	/* The bh was validated by the inode read during
+	 * ocfs2_reserve_suballoc_bits().  Any corruption is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
+
+	if (le32_to_cpu(fe->id1.bitmap1.i_used) >=
+	    le32_to_cpu(fe->id1.bitmap1.i_total)) {
+		status = ocfs2_error(ac->ac_inode->i_sb,
+				     "Chain allocator dinode %llu has %u used bits but only %u total\n",
+				     (unsigned long long)le64_to_cpu(fe->i_blkno),
+				     le32_to_cpu(fe->id1.bitmap1.i_used),
+				     le32_to_cpu(fe->id1.bitmap1.i_total));
+		goto bail;
+	}
+
+	res->sr_bg_blkno = hint;
+	if (res->sr_bg_blkno) {
+		/* Attempt to short-circuit the usual search mechanism
+		 * by jumping straight to the most recently used
+		 * allocation group. This helps us maintain some
+		 * contiguousness across allocations. */
+		status = ocfs2_search_one_group(ac, handle, bits_wanted,
+						min_bits, res, &bits_left);
+		if (!status)
+			goto set_hint;
+		if (status < 0 && status != -ENOSPC) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;
+
+	victim = ocfs2_find_victim_chain(cl);
+	ac->ac_chain = victim;
+
+	status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
+				    res, &bits_left);
+	if (!status) {
+		if (ocfs2_is_cluster_bitmap(ac->ac_inode))
+			hint = res->sr_bg_blkno;
+		else
+			hint = ocfs2_group_from_res(res);
+		goto set_hint;
+	}
+	if (status < 0 && status != -ENOSPC) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	trace_ocfs2_claim_suballoc_bits(victim);
+
+	/* If we didn't pick a good victim, then just default to
+	 * searching each chain in order. Don't allow chain relinking
+	 * because we only calculate enough journal credits for one
+	 * relink per alloc. */
+	ac->ac_disable_chain_relink = 1;
+	for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i ++) {
+		if (i == victim)
+			continue;
+		if (!cl->cl_recs[i].c_free)
+			continue;
+
+		ac->ac_chain = i;
+		status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
+					    res, &bits_left);
+		if (!status) {
+			hint = ocfs2_group_from_res(res);
+			break;
+		}
+		if (status < 0 && status != -ENOSPC) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+set_hint:
+	if (status != -ENOSPC) {
+		/* If the next search of this group is not likely to
+		 * yield a suitable extent, then we reset the last
+		 * group hint so as to not waste a disk read */
+		if (bits_left < min_bits)
+			ac->ac_last_group = 0;
+		else
+			ac->ac_last_group = hint;
+	}
+
+bail:
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+int ocfs2_claim_metadata(handle_t *handle,
+			 struct ocfs2_alloc_context *ac,
+			 u32 bits_wanted,
+			 u64 *suballoc_loc,
+			 u16 *suballoc_bit_start,
+			 unsigned int *num_bits,
+			 u64 *blkno_start)
+{
+	int status;
+	struct ocfs2_suballoc_result res = { .sr_blkno = 0, };
+
+	BUG_ON(!ac);
+	BUG_ON(ac->ac_bits_wanted < (ac->ac_bits_given + bits_wanted));
+	BUG_ON(ac->ac_which != OCFS2_AC_USE_META);
+
+	status = ocfs2_claim_suballoc_bits(ac,
+					   handle,
+					   bits_wanted,
+					   1,
+					   &res);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	atomic_inc(&OCFS2_SB(ac->ac_inode->i_sb)->alloc_stats.bg_allocs);
+
+	*suballoc_loc = res.sr_bg_blkno;
+	*suballoc_bit_start = res.sr_bit_offset;
+	*blkno_start = res.sr_blkno;
+	ac->ac_bits_given += res.sr_bits;
+	*num_bits = res.sr_bits;
+	status = 0;
+bail:
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+static void ocfs2_init_inode_ac_group(struct inode *dir,
+				      struct buffer_head *parent_di_bh,
+				      struct ocfs2_alloc_context *ac)
+{
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)parent_di_bh->b_data;
+	/*
+	 * Try to allocate inodes from some specific group.
+	 *
+	 * If the parent dir has recorded the last group used in allocation,
+	 * cool, use it. Otherwise if we try to allocate new inode from the
+	 * same slot the parent dir belongs to, use the same chunk.
+	 *
+	 * We are very careful here to avoid the mistake of setting
+	 * ac_last_group to a group descriptor from a different (unlocked) slot.
+	 */
+	if (OCFS2_I(dir)->ip_last_used_group &&
+	    OCFS2_I(dir)->ip_last_used_slot == ac->ac_alloc_slot)
+		ac->ac_last_group = OCFS2_I(dir)->ip_last_used_group;
+	else if (le16_to_cpu(di->i_suballoc_slot) == ac->ac_alloc_slot) {
+		if (di->i_suballoc_loc)
+			ac->ac_last_group = le64_to_cpu(di->i_suballoc_loc);
+		else
+			ac->ac_last_group = ocfs2_which_suballoc_group(
+					le64_to_cpu(di->i_blkno),
+					le16_to_cpu(di->i_suballoc_bit));
+	}
+}
+
+static inline void ocfs2_save_inode_ac_group(struct inode *dir,
+					     struct ocfs2_alloc_context *ac)
+{
+	OCFS2_I(dir)->ip_last_used_group = ac->ac_last_group;
+	OCFS2_I(dir)->ip_last_used_slot = ac->ac_alloc_slot;
+}
+
+int ocfs2_find_new_inode_loc(struct inode *dir,
+			     struct buffer_head *parent_fe_bh,
+			     struct ocfs2_alloc_context *ac,
+			     u64 *fe_blkno)
+{
+	int ret;
+	handle_t *handle = NULL;
+	struct ocfs2_suballoc_result *res;
+
+	BUG_ON(!ac);
+	BUG_ON(ac->ac_bits_given != 0);
+	BUG_ON(ac->ac_bits_wanted != 1);
+	BUG_ON(ac->ac_which != OCFS2_AC_USE_INODE);
+
+	res = kzalloc(sizeof(*res), GFP_NOFS);
+	if (res == NULL) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ocfs2_init_inode_ac_group(dir, parent_fe_bh, ac);
+
+	/*
+	 * The handle started here is for chain relink. Alternatively,
+	 * we could just disable relink for these calls.
+	 */
+	handle = ocfs2_start_trans(OCFS2_SB(dir->i_sb), OCFS2_SUBALLOC_ALLOC);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		handle = NULL;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	/*
+	 * This will instruct ocfs2_claim_suballoc_bits and
+	 * ocfs2_search_one_group to search but save actual allocation
+	 * for later.
+	 */
+	ac->ac_find_loc_only = 1;
+
+	ret = ocfs2_claim_suballoc_bits(ac, handle, 1, 1, res);
+	if (ret < 0) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ac->ac_find_loc_priv = res;
+	*fe_blkno = res->sr_blkno;
+	ocfs2_update_inode_fsync_trans(handle, dir, 0);
+out:
+	if (handle)
+		ocfs2_commit_trans(OCFS2_SB(dir->i_sb), handle);
+
+	if (ret)
+		kfree(res);
+
+	return ret;
+}
+
+int ocfs2_claim_new_inode_at_loc(handle_t *handle,
+				 struct inode *dir,
+				 struct ocfs2_alloc_context *ac,
+				 u64 *suballoc_loc,
+				 u16 *suballoc_bit,
+				 u64 di_blkno)
+{
+	int ret;
+	u16 chain;
+	struct ocfs2_suballoc_result *res = ac->ac_find_loc_priv;
+	struct buffer_head *bg_bh = NULL;
+	struct ocfs2_group_desc *bg;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *) ac->ac_bh->b_data;
+
+	/*
+	 * Since di_blkno is being passed back in, we check for any
+	 * inconsistencies which may have happened between
+	 * calls. These are code bugs as di_blkno is not expected to
+	 * change once returned from ocfs2_find_new_inode_loc()
+	 */
+	BUG_ON(res->sr_blkno != di_blkno);
+
+	ret = ocfs2_read_group_descriptor(ac->ac_inode, di,
+					  res->sr_bg_stable_blkno, &bg_bh);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	bg = (struct ocfs2_group_desc *) bg_bh->b_data;
+	chain = le16_to_cpu(bg->bg_chain);
+
+	ret = ocfs2_alloc_dinode_update_counts(ac->ac_inode, handle,
+					       ac->ac_bh, res->sr_bits,
+					       chain);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ret = ocfs2_block_group_set_bits(handle,
+					 ac->ac_inode,
+					 bg,
+					 bg_bh,
+					 res->sr_bit_offset,
+					 res->sr_bits);
+	if (ret < 0) {
+		ocfs2_rollback_alloc_dinode_counts(ac->ac_inode,
+					       ac->ac_bh, res->sr_bits, chain);
+		mlog_errno(ret);
+		goto out;
+	}
+
+	trace_ocfs2_claim_new_inode_at_loc((unsigned long long)di_blkno,
+					   res->sr_bits);
+
+	atomic_inc(&OCFS2_SB(ac->ac_inode->i_sb)->alloc_stats.bg_allocs);
+
+	BUG_ON(res->sr_bits != 1);
+
+	*suballoc_loc = res->sr_bg_blkno;
+	*suballoc_bit = res->sr_bit_offset;
+	ac->ac_bits_given++;
+	ocfs2_save_inode_ac_group(dir, ac);
+
+out:
+	brelse(bg_bh);
+
+	return ret;
+}
+
+int ocfs2_claim_new_inode(handle_t *handle,
+			  struct inode *dir,
+			  struct buffer_head *parent_fe_bh,
+			  struct ocfs2_alloc_context *ac,
+			  u64 *suballoc_loc,
+			  u16 *suballoc_bit,
+			  u64 *fe_blkno)
+{
+	int status;
+	struct ocfs2_suballoc_result res;
+
+	BUG_ON(!ac);
+	BUG_ON(ac->ac_bits_given != 0);
+	BUG_ON(ac->ac_bits_wanted != 1);
+	BUG_ON(ac->ac_which != OCFS2_AC_USE_INODE);
+
+	ocfs2_init_inode_ac_group(dir, parent_fe_bh, ac);
+
+	status = ocfs2_claim_suballoc_bits(ac,
+					   handle,
+					   1,
+					   1,
+					   &res);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	atomic_inc(&OCFS2_SB(ac->ac_inode->i_sb)->alloc_stats.bg_allocs);
+
+	BUG_ON(res.sr_bits != 1);
+
+	*suballoc_loc = res.sr_bg_blkno;
+	*suballoc_bit = res.sr_bit_offset;
+	*fe_blkno = res.sr_blkno;
+	ac->ac_bits_given++;
+	ocfs2_save_inode_ac_group(dir, ac);
+	status = 0;
+bail:
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+/* translate a group desc. blkno and it's bitmap offset into
+ * disk cluster offset. */
+static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
+						   u64 bg_blkno,
+						   u16 bg_bit_off)
+{
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	u32 cluster = 0;
+
+	BUG_ON(!ocfs2_is_cluster_bitmap(inode));
+
+	if (bg_blkno != osb->first_cluster_group_blkno)
+		cluster = ocfs2_blocks_to_clusters(inode->i_sb, bg_blkno);
+	cluster += (u32) bg_bit_off;
+	return cluster;
+}
+
+/* given a cluster offset, calculate which block group it belongs to
+ * and return that block offset. */
+u64 ocfs2_which_cluster_group(struct inode *inode, u32 cluster)
+{
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	u32 group_no;
+
+	BUG_ON(!ocfs2_is_cluster_bitmap(inode));
+
+	group_no = cluster / osb->bitmap_cpg;
+	if (!group_no)
+		return osb->first_cluster_group_blkno;
+	return ocfs2_clusters_to_blocks(inode->i_sb,
+					group_no * osb->bitmap_cpg);
+}
+
+/* given the block number of a cluster start, calculate which cluster
+ * group and descriptor bitmap offset that corresponds to. */
+static inline void ocfs2_block_to_cluster_group(struct inode *inode,
+						u64 data_blkno,
+						u64 *bg_blkno,
+						u16 *bg_bit_off)
+{
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	u32 data_cluster = ocfs2_blocks_to_clusters(osb->sb, data_blkno);
+
+	BUG_ON(!ocfs2_is_cluster_bitmap(inode));
+
+	*bg_blkno = ocfs2_which_cluster_group(inode,
+					      data_cluster);
+
+	if (*bg_blkno == osb->first_cluster_group_blkno)
+		*bg_bit_off = (u16) data_cluster;
+	else
+		*bg_bit_off = (u16) ocfs2_blocks_to_clusters(osb->sb,
+							     data_blkno - *bg_blkno);
+}
+
+/*
+ * min_bits - minimum contiguous chunk from this total allocation we
+ * can handle. set to what we asked for originally for a full
+ * contig. allocation, set to '1' to indicate we can deal with extents
+ * of any size.
+ */
+int __ocfs2_claim_clusters(handle_t *handle,
+			   struct ocfs2_alloc_context *ac,
+			   u32 min_clusters,
+			   u32 max_clusters,
+			   u32 *cluster_start,
+			   u32 *num_clusters)
+{
+	int status;
+	unsigned int bits_wanted = max_clusters;
+	struct ocfs2_suballoc_result res = { .sr_blkno = 0, };
+	struct ocfs2_super *osb = OCFS2_SB(ac->ac_inode->i_sb);
+
+	BUG_ON(ac->ac_bits_given >= ac->ac_bits_wanted);
+
+	BUG_ON(ac->ac_which != OCFS2_AC_USE_LOCAL
+	       && ac->ac_which != OCFS2_AC_USE_MAIN);
+
+	if (ac->ac_which == OCFS2_AC_USE_LOCAL) {
+		WARN_ON(min_clusters > 1);
+
+		status = ocfs2_claim_local_alloc_bits(osb,
+						      handle,
+						      ac,
+						      bits_wanted,
+						      cluster_start,
+						      num_clusters);
+		if (!status)
+			atomic_inc(&osb->alloc_stats.local_data);
+	} else {
+		if (min_clusters > (osb->bitmap_cpg - 1)) {
+			/* The only paths asking for contiguousness
+			 * should know about this already. */
+			mlog(ML_ERROR, "minimum allocation requested %u exceeds "
+			     "group bitmap size %u!\n", min_clusters,
+			     osb->bitmap_cpg);
+			status = -ENOSPC;
+			goto bail;
+		}
+		/* clamp the current request down to a realistic size. */
+		if (bits_wanted > (osb->bitmap_cpg - 1))
+			bits_wanted = osb->bitmap_cpg - 1;
+
+		status = ocfs2_claim_suballoc_bits(ac,
+						   handle,
+						   bits_wanted,
+						   min_clusters,
+						   &res);
+		if (!status) {
+			BUG_ON(res.sr_blkno); /* cluster alloc can't set */
+			*cluster_start =
+				ocfs2_desc_bitmap_to_cluster_off(ac->ac_inode,
+								 res.sr_bg_blkno,
+								 res.sr_bit_offset);
+			atomic_inc(&osb->alloc_stats.bitmap_data);
+			*num_clusters = res.sr_bits;
+		}
+	}
+	if (status < 0) {
+		if (status != -ENOSPC)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	ac->ac_bits_given += *num_clusters;
+
+bail:
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+int ocfs2_claim_clusters(handle_t *handle,
+			 struct ocfs2_alloc_context *ac,
+			 u32 min_clusters,
+			 u32 *cluster_start,
+			 u32 *num_clusters)
+{
+	unsigned int bits_wanted = ac->ac_bits_wanted - ac->ac_bits_given;
+
+	return __ocfs2_claim_clusters(handle, ac, min_clusters,
+				      bits_wanted, cluster_start, num_clusters);
+}
+
+static int ocfs2_block_group_clear_bits(handle_t *handle,
+					struct inode *alloc_inode,
+					struct ocfs2_group_desc *bg,
+					struct buffer_head *group_bh,
+					unsigned int bit_off,
+					unsigned int num_bits,
+					void (*undo_fn)(unsigned int bit,
+							unsigned long *bmap))
+{
+	int status;
+	unsigned int tmp;
+	struct ocfs2_group_desc *undo_bg = NULL;
+	struct journal_head *jh;
+
+	/* The caller got this descriptor from
+	 * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
+
+	trace_ocfs2_block_group_clear_bits(bit_off, num_bits);
+
+	BUG_ON(undo_fn && !ocfs2_is_cluster_bitmap(alloc_inode));
+	status = ocfs2_journal_access_gd(handle, INODE_CACHE(alloc_inode),
+					 group_bh,
+					 undo_fn ?
+					 OCFS2_JOURNAL_ACCESS_UNDO :
+					 OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	jh = bh2jh(group_bh);
+	if (undo_fn) {
+		spin_lock(&jh->b_state_lock);
+		undo_bg = (struct ocfs2_group_desc *) jh->b_committed_data;
+		BUG_ON(!undo_bg);
+	}
+
+	tmp = num_bits;
+	while(tmp--) {
+		ocfs2_clear_bit((bit_off + tmp),
+				(unsigned long *) bg->bg_bitmap);
+		if (undo_fn)
+			undo_fn(bit_off + tmp,
+				(unsigned long *) undo_bg->bg_bitmap);
+	}
+	le16_add_cpu(&bg->bg_free_bits_count, num_bits);
+	if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
+		if (undo_fn)
+			spin_unlock(&jh->b_state_lock);
+		return ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit count %u but claims %u are freed. num_bits %d\n",
+				   (unsigned long long)le64_to_cpu(bg->bg_blkno),
+				   le16_to_cpu(bg->bg_bits),
+				   le16_to_cpu(bg->bg_free_bits_count),
+				   num_bits);
+	}
+
+	if (undo_fn)
+		spin_unlock(&jh->b_state_lock);
+
+	ocfs2_journal_dirty(handle, group_bh);
+bail:
+	return status;
+}
+
+/*
+ * expects the suballoc inode to already be locked.
+ */
+static int _ocfs2_free_suballoc_bits(handle_t *handle,
+				     struct inode *alloc_inode,
+				     struct buffer_head *alloc_bh,
+				     unsigned int start_bit,
+				     u64 bg_blkno,
+				     unsigned int count,
+				     void (*undo_fn)(unsigned int bit,
+						     unsigned long *bitmap))
+{
+	int status = 0;
+	u32 tmp_used;
+	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) alloc_bh->b_data;
+	struct ocfs2_chain_list *cl = &fe->id2.i_chain;
+	struct buffer_head *group_bh = NULL;
+	struct ocfs2_group_desc *group;
+
+	/* The alloc_bh comes from ocfs2_free_dinode() or
+	 * ocfs2_free_clusters().  The callers have all locked the
+	 * allocator and gotten alloc_bh from the lock call.  This
+	 * validates the dinode buffer.  Any corruption that has happened
+	 * is a code bug. */
+	BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
+	BUG_ON((count + start_bit) > ocfs2_bits_per_group(cl));
+
+	trace_ocfs2_free_suballoc_bits(
+		(unsigned long long)OCFS2_I(alloc_inode)->ip_blkno,
+		(unsigned long long)bg_blkno,
+		start_bit, count);
+
+	status = ocfs2_read_group_descriptor(alloc_inode, fe, bg_blkno,
+					     &group_bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	group = (struct ocfs2_group_desc *) group_bh->b_data;
+
+	BUG_ON((count + start_bit) > le16_to_cpu(group->bg_bits));
+
+	status = ocfs2_block_group_clear_bits(handle, alloc_inode,
+					      group, group_bh,
+					      start_bit, count, undo_fn);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = ocfs2_journal_access_di(handle, INODE_CACHE(alloc_inode),
+					 alloc_bh, OCFS2_JOURNAL_ACCESS_WRITE);
+	if (status < 0) {
+		mlog_errno(status);
+		ocfs2_block_group_set_bits(handle, alloc_inode, group, group_bh,
+				start_bit, count);
+		goto bail;
+	}
+
+	le32_add_cpu(&cl->cl_recs[le16_to_cpu(group->bg_chain)].c_free,
+		     count);
+	tmp_used = le32_to_cpu(fe->id1.bitmap1.i_used);
+	fe->id1.bitmap1.i_used = cpu_to_le32(tmp_used - count);
+	ocfs2_journal_dirty(handle, alloc_bh);
+
+bail:
+	brelse(group_bh);
+	return status;
+}
+
+int ocfs2_free_suballoc_bits(handle_t *handle,
+			     struct inode *alloc_inode,
+			     struct buffer_head *alloc_bh,
+			     unsigned int start_bit,
+			     u64 bg_blkno,
+			     unsigned int count)
+{
+	return _ocfs2_free_suballoc_bits(handle, alloc_inode, alloc_bh,
+					 start_bit, bg_blkno, count, NULL);
+}
+
+int ocfs2_free_dinode(handle_t *handle,
+		      struct inode *inode_alloc_inode,
+		      struct buffer_head *inode_alloc_bh,
+		      struct ocfs2_dinode *di)
+{
+	u64 blk = le64_to_cpu(di->i_blkno);
+	u16 bit = le16_to_cpu(di->i_suballoc_bit);
+	u64 bg_blkno = ocfs2_which_suballoc_group(blk, bit);
+
+	if (di->i_suballoc_loc)
+		bg_blkno = le64_to_cpu(di->i_suballoc_loc);
+	return ocfs2_free_suballoc_bits(handle, inode_alloc_inode,
+					inode_alloc_bh, bit, bg_blkno, 1);
+}
+
+static int _ocfs2_free_clusters(handle_t *handle,
+				struct inode *bitmap_inode,
+				struct buffer_head *bitmap_bh,
+				u64 start_blk,
+				unsigned int num_clusters,
+				void (*undo_fn)(unsigned int bit,
+						unsigned long *bitmap))
+{
+	int status;
+	u16 bg_start_bit;
+	u64 bg_blkno;
+
+	/* You can't ever have a contiguous set of clusters
+	 * bigger than a block group bitmap so we never have to worry
+	 * about looping on them.
+	 * This is expensive. We can safely remove once this stuff has
+	 * gotten tested really well. */
+	BUG_ON(start_blk != ocfs2_clusters_to_blocks(bitmap_inode->i_sb,
+				ocfs2_blocks_to_clusters(bitmap_inode->i_sb,
+							 start_blk)));
+
+
+	ocfs2_block_to_cluster_group(bitmap_inode, start_blk, &bg_blkno,
+				     &bg_start_bit);
+
+	trace_ocfs2_free_clusters((unsigned long long)bg_blkno,
+			(unsigned long long)start_blk,
+			bg_start_bit, num_clusters);
+
+	status = _ocfs2_free_suballoc_bits(handle, bitmap_inode, bitmap_bh,
+					   bg_start_bit, bg_blkno,
+					   num_clusters, undo_fn);
+	if (status < 0) {
+		mlog_errno(status);
+		goto out;
+	}
+
+	ocfs2_local_alloc_seen_free_bits(OCFS2_SB(bitmap_inode->i_sb),
+					 num_clusters);
+
+out:
+	return status;
+}
+
+int ocfs2_free_clusters(handle_t *handle,
+			struct inode *bitmap_inode,
+			struct buffer_head *bitmap_bh,
+			u64 start_blk,
+			unsigned int num_clusters)
+{
+	return _ocfs2_free_clusters(handle, bitmap_inode, bitmap_bh,
+				    start_blk, num_clusters,
+				    _ocfs2_set_bit);
+}
+
+/*
+ * Give never-used clusters back to the global bitmap.  We don't need
+ * to protect these bits in the undo buffer.
+ */
+int ocfs2_release_clusters(handle_t *handle,
+			   struct inode *bitmap_inode,
+			   struct buffer_head *bitmap_bh,
+			   u64 start_blk,
+			   unsigned int num_clusters)
+{
+	return _ocfs2_free_clusters(handle, bitmap_inode, bitmap_bh,
+				    start_blk, num_clusters,
+				    _ocfs2_clear_bit);
+}
+
+/*
+ * For a given allocation, determine which allocators will need to be
+ * accessed, and lock them, reserving the appropriate number of bits.
+ *
+ * Sparse file systems call this from ocfs2_write_begin_nolock()
+ * and ocfs2_allocate_unwritten_extents().
+ *
+ * File systems which don't support holes call this from
+ * ocfs2_extend_allocation().
+ */
+int ocfs2_lock_allocators(struct inode *inode,
+			  struct ocfs2_extent_tree *et,
+			  u32 clusters_to_add, u32 extents_to_split,
+			  struct ocfs2_alloc_context **data_ac,
+			  struct ocfs2_alloc_context **meta_ac)
+{
+	int ret = 0, num_free_extents;
+	unsigned int max_recs_needed = clusters_to_add + 2 * extents_to_split;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	*meta_ac = NULL;
+	if (data_ac)
+		*data_ac = NULL;
+
+	BUG_ON(clusters_to_add != 0 && data_ac == NULL);
+
+	num_free_extents = ocfs2_num_free_extents(et);
+	if (num_free_extents < 0) {
+		ret = num_free_extents;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	/*
+	 * Sparse allocation file systems need to be more conservative
+	 * with reserving room for expansion - the actual allocation
+	 * happens while we've got a journal handle open so re-taking
+	 * a cluster lock (because we ran out of room for another
+	 * extent) will violate ordering rules.
+	 *
+	 * Most of the time we'll only be seeing this 1 cluster at a time
+	 * anyway.
+	 *
+	 * Always lock for any unwritten extents - we might want to
+	 * add blocks during a split.
+	 */
+	if (!num_free_extents ||
+	    (ocfs2_sparse_alloc(osb) && num_free_extents < max_recs_needed)) {
+		ret = ocfs2_reserve_new_metadata(osb, et->et_root_el, meta_ac);
+		if (ret < 0) {
+			if (ret != -ENOSPC)
+				mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	if (clusters_to_add == 0)
+		goto out;
+
+	ret = ocfs2_reserve_clusters(osb, clusters_to_add, data_ac);
+	if (ret < 0) {
+		if (ret != -ENOSPC)
+			mlog_errno(ret);
+		goto out;
+	}
+
+out:
+	if (ret) {
+		if (*meta_ac) {
+			ocfs2_free_alloc_context(*meta_ac);
+			*meta_ac = NULL;
+		}
+
+		/*
+		 * We cannot have an error and a non null *data_ac.
+		 */
+	}
+
+	return ret;
+}
+
+/*
+ * Read the inode specified by blkno to get suballoc_slot and
+ * suballoc_bit.
+ */
+static int ocfs2_get_suballoc_slot_bit(struct ocfs2_super *osb, u64 blkno,
+				       u16 *suballoc_slot, u64 *group_blkno,
+				       u16 *suballoc_bit)
+{
+	int status;
+	struct buffer_head *inode_bh = NULL;
+	struct ocfs2_dinode *inode_fe;
+
+	trace_ocfs2_get_suballoc_slot_bit((unsigned long long)blkno);
+
+	/* dirty read disk */
+	status = ocfs2_read_blocks_sync(osb, blkno, 1, &inode_bh);
+	if (status < 0) {
+		mlog(ML_ERROR, "read block %llu failed %d\n",
+		     (unsigned long long)blkno, status);
+		goto bail;
+	}
+
+	inode_fe = (struct ocfs2_dinode *) inode_bh->b_data;
+	if (!OCFS2_IS_VALID_DINODE(inode_fe)) {
+		mlog(ML_ERROR, "invalid inode %llu requested\n",
+		     (unsigned long long)blkno);
+		status = -EINVAL;
+		goto bail;
+	}
+
+	if (le16_to_cpu(inode_fe->i_suballoc_slot) != (u16)OCFS2_INVALID_SLOT &&
+	    (u32)le16_to_cpu(inode_fe->i_suballoc_slot) > osb->max_slots - 1) {
+		mlog(ML_ERROR, "inode %llu has invalid suballoc slot %u\n",
+		     (unsigned long long)blkno,
+		     (u32)le16_to_cpu(inode_fe->i_suballoc_slot));
+		status = -EINVAL;
+		goto bail;
+	}
+
+	if (suballoc_slot)
+		*suballoc_slot = le16_to_cpu(inode_fe->i_suballoc_slot);
+	if (suballoc_bit)
+		*suballoc_bit = le16_to_cpu(inode_fe->i_suballoc_bit);
+	if (group_blkno)
+		*group_blkno = le64_to_cpu(inode_fe->i_suballoc_loc);
+
+bail:
+	brelse(inode_bh);
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+/*
+ * test whether bit is SET in allocator bitmap or not.  on success, 0
+ * is returned and *res is 1 for SET; 0 otherwise.  when fails, errno
+ * is returned and *res is meaningless.  Call this after you have
+ * cluster locked against suballoc, or you may get a result based on
+ * non-up2date contents
+ */
+static int ocfs2_test_suballoc_bit(struct ocfs2_super *osb,
+				   struct inode *suballoc,
+				   struct buffer_head *alloc_bh,
+				   u64 group_blkno, u64 blkno,
+				   u16 bit, int *res)
+{
+	struct ocfs2_dinode *alloc_di;
+	struct ocfs2_group_desc *group;
+	struct buffer_head *group_bh = NULL;
+	u64 bg_blkno;
+	int status;
+
+	trace_ocfs2_test_suballoc_bit((unsigned long long)blkno,
+				      (unsigned int)bit);
+
+	alloc_di = (struct ocfs2_dinode *)alloc_bh->b_data;
+	if ((bit + 1) > ocfs2_bits_per_group(&alloc_di->id2.i_chain)) {
+		mlog(ML_ERROR, "suballoc bit %u out of range of %u\n",
+		     (unsigned int)bit,
+		     ocfs2_bits_per_group(&alloc_di->id2.i_chain));
+		status = -EINVAL;
+		goto bail;
+	}
+
+	bg_blkno = group_blkno ? group_blkno :
+		   ocfs2_which_suballoc_group(blkno, bit);
+	status = ocfs2_read_group_descriptor(suballoc, alloc_di, bg_blkno,
+					     &group_bh);
+	if (status < 0) {
+		mlog(ML_ERROR, "read group %llu failed %d\n",
+		     (unsigned long long)bg_blkno, status);
+		goto bail;
+	}
+
+	group = (struct ocfs2_group_desc *) group_bh->b_data;
+	*res = ocfs2_test_bit(bit, (unsigned long *)group->bg_bitmap);
+
+bail:
+	brelse(group_bh);
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+/*
+ * Test if the bit representing this inode (blkno) is set in the
+ * suballocator.
+ *
+ * On success, 0 is returned and *res is 1 for SET; 0 otherwise.
+ *
+ * In the event of failure, a negative value is returned and *res is
+ * meaningless.
+ *
+ * Callers must make sure to hold nfs_sync_lock to prevent
+ * ocfs2_delete_inode() on another node from accessing the same
+ * suballocator concurrently.
+ */
+int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res)
+{
+	int status;
+	u64 group_blkno = 0;
+	u16 suballoc_bit = 0, suballoc_slot = 0;
+	struct inode *inode_alloc_inode;
+	struct buffer_head *alloc_bh = NULL;
+
+	trace_ocfs2_test_inode_bit((unsigned long long)blkno);
+
+	status = ocfs2_get_suballoc_slot_bit(osb, blkno, &suballoc_slot,
+					     &group_blkno, &suballoc_bit);
+	if (status < 0) {
+		mlog(ML_ERROR, "get alloc slot and bit failed %d\n", status);
+		goto bail;
+	}
+
+	if (suballoc_slot == (u16)OCFS2_INVALID_SLOT)
+		inode_alloc_inode = ocfs2_get_system_file_inode(osb,
+			GLOBAL_INODE_ALLOC_SYSTEM_INODE, suballoc_slot);
+	else
+		inode_alloc_inode = ocfs2_get_system_file_inode(osb,
+			INODE_ALLOC_SYSTEM_INODE, suballoc_slot);
+	if (!inode_alloc_inode) {
+		/* the error code could be inaccurate, but we are not able to
+		 * get the correct one. */
+		status = -EINVAL;
+		mlog(ML_ERROR, "unable to get alloc inode in slot %u\n",
+		     (u32)suballoc_slot);
+		goto bail;
+	}
+
+	inode_lock(inode_alloc_inode);
+	status = ocfs2_inode_lock(inode_alloc_inode, &alloc_bh, 0);
+	if (status < 0) {
+		inode_unlock(inode_alloc_inode);
+		iput(inode_alloc_inode);
+		mlog(ML_ERROR, "lock on alloc inode on slot %u failed %d\n",
+		     (u32)suballoc_slot, status);
+		goto bail;
+	}
+
+	status = ocfs2_test_suballoc_bit(osb, inode_alloc_inode, alloc_bh,
+					 group_blkno, blkno, suballoc_bit, res);
+	if (status < 0)
+		mlog(ML_ERROR, "test suballoc bit failed %d\n", status);
+
+	ocfs2_inode_unlock(inode_alloc_inode, 0);
+	inode_unlock(inode_alloc_inode);
+
+	iput(inode_alloc_inode);
+	brelse(alloc_bh);
+bail:
+	if (status)
+		mlog_errno(status);
+	return status;
+}