Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / fs / ocfs2 / suballoc.c
diff --git a/kernel/fs/ocfs2/suballoc.c b/kernel/fs/ocfs2/suballoc.c
new file mode 100644 (file)
index 0000000..4479029
--- /dev/null
@@ -0,0 +1,2919 @@
+/* -*- 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.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+
+#include <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 void ocfs2_debug_bg(struct ocfs2_group_desc *bg);
+static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe);
+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);
+
+               mutex_unlock(&inode->i_mutex);
+
+               iput(inode);
+               ac->ac_inode = NULL;
+       }
+       brelse(ac->ac_bh);
+       ac->ac_bh = NULL;
+       ac->ac_resv = NULL;
+       if (ac->ac_find_loc_priv) {
+               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 "\n", ##__VA_ARGS__);        \
+               else                                                    \
+                       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",
+                        (unsigned long long)bh->b_blocknr, 7,
+                        gd->bg_signature);
+               return -EINVAL;
+       }
+
+       if (le64_to_cpu(gd->bg_blkno) != bh->b_blocknr) {
+               do_error("Group descriptor #%llu has an invalid bg_blkno "
+                        "of %llu",
+                        (unsigned long long)bh->b_blocknr,
+                        (unsigned long long)le64_to_cpu(gd->bg_blkno));
+               return -EINVAL;
+       }
+
+       if (le32_to_cpu(gd->bg_generation) != OCFS2_SB(sb)->fs_generation) {
+               do_error("Group descriptor #%llu has an invalid "
+                        "fs_generation of #%u",
+                        (unsigned long long)bh->b_blocknr,
+                        le32_to_cpu(gd->bg_generation));
+               return -EINVAL;
+       }
+
+       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",
+                        (unsigned long long)bh->b_blocknr,
+                        le16_to_cpu(gd->bg_bits),
+                        le16_to_cpu(gd->bg_free_bits_count));
+               return -EINVAL;
+       }
+
+       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",
+                        (unsigned long long)bh->b_blocknr,
+                        le16_to_cpu(gd->bg_bits),
+                        8 * le16_to_cpu(gd->bg_size));
+               return -EINVAL;
+       }
+
+       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)",
+                        (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));
+               return -EINVAL;
+       }
+
+       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",
+                        (unsigned long long)bh->b_blocknr,
+                        le16_to_cpu(gd->bg_bits));
+               return -EINVAL;
+       }
+
+       /* 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",
+                        (unsigned long long)bh->b_blocknr,
+                        le16_to_cpu(gd->bg_chain));
+               return -EINVAL;
+       }
+
+       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) {
+               ocfs2_error(alloc_inode->i_sb, "group block (%llu) != "
+                           "b_blocknr (%llu)",
+                           (unsigned long long)group_blkno,
+                           (unsigned long long) bg_bh->b_blocknr);
+               status = -EIO;
+               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(OCFS2_SB(sb)->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 (IS_ERR(bg_bh) && (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;
+       }
+
+       mutex_lock(&alloc_inode->i_mutex);
+
+       status = ocfs2_inode_lock(alloc_inode, &bh, 1);
+       if (status < 0) {
+               mutex_unlock(&alloc_inode->i_mutex);
+               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))) {
+               ocfs2_error(alloc_inode->i_sb, "Invalid chain allocator %llu",
+                           (unsigned long long)le64_to_cpu(fe->i_blkno));
+               status = -EIO;
+               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 = slot;
+       else if (type == EXTENT_ALLOC_SYSTEM_INODE)
+               osb->s_meta_steal_slot = 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);
+               goto bail;
+       }
+
+bail:
+       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;
+
+       *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) {
+               status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);
+               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;
+       int ret;
+
+       if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
+               return 0;
+
+       if (!buffer_jbd(bg_bh))
+               return 1;
+
+       jbd_lock_bh_state(bg_bh);
+       bg = (struct ocfs2_group_desc *) bh2jh(bg_bh)->b_committed_data;
+       if (bg)
+               ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
+       else
+               ret = 1;
+       jbd_unlock_bh_state(bg_bh);
+
+       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)) {
+               ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit"
+                           " count %u but claims %u are freed. num_bits %d",
+                           (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);
+               return -EROFS;
+       }
+       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(OCFS2_SB(inode->i_sb),
+                                                       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)) {
+               ocfs2_error(ac->ac_inode->i_sb,
+                           "Chain allocator dinode %llu has %u used "
+                           "bits but only %u total.",
+                           (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));
+               status = -EIO;
+               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) {
+               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;
+
+       /* 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;
+       }
+
+       if (undo_fn) {
+               jbd_lock_bh_state(group_bh);
+               undo_bg = (struct ocfs2_group_desc *)
+                                       bh2jh(group_bh)->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)) {
+               ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit"
+                           " count %u but claims %u are freed. num_bits %d",
+                           (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);
+               return -EROFS;
+       }
+
+       if (undo_fn)
+               jbd_unlock_bh_state(group_bh);
+
+       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);
+
+       if (status)
+               mlog_errno(status);
+       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;
+       struct ocfs2_dinode *fe;
+
+       /* 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)));
+
+       fe = (struct ocfs2_dinode *) bitmap_bh->b_data;
+
+       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:
+       if (status)
+               mlog_errno(status);
+       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);
+}
+
+static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg)
+{
+       printk("Block Group:\n");
+       printk("bg_signature:       %s\n", bg->bg_signature);
+       printk("bg_size:            %u\n", bg->bg_size);
+       printk("bg_bits:            %u\n", bg->bg_bits);
+       printk("bg_free_bits_count: %u\n", bg->bg_free_bits_count);
+       printk("bg_chain:           %u\n", bg->bg_chain);
+       printk("bg_generation:      %u\n", le32_to_cpu(bg->bg_generation));
+       printk("bg_next_group:      %llu\n",
+              (unsigned long long)bg->bg_next_group);
+       printk("bg_parent_dinode:   %llu\n",
+              (unsigned long long)bg->bg_parent_dinode);
+       printk("bg_blkno:           %llu\n",
+              (unsigned long long)bg->bg_blkno);
+}
+
+static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe)
+{
+       int i;
+
+       printk("Suballoc Inode %llu:\n", (unsigned long long)fe->i_blkno);
+       printk("i_signature:                  %s\n", fe->i_signature);
+       printk("i_size:                       %llu\n",
+              (unsigned long long)fe->i_size);
+       printk("i_clusters:                   %u\n", fe->i_clusters);
+       printk("i_generation:                 %u\n",
+              le32_to_cpu(fe->i_generation));
+       printk("id1.bitmap1.i_used:           %u\n",
+              le32_to_cpu(fe->id1.bitmap1.i_used));
+       printk("id1.bitmap1.i_total:          %u\n",
+              le32_to_cpu(fe->id1.bitmap1.i_total));
+       printk("id2.i_chain.cl_cpg:           %u\n", fe->id2.i_chain.cl_cpg);
+       printk("id2.i_chain.cl_bpc:           %u\n", fe->id2.i_chain.cl_bpc);
+       printk("id2.i_chain.cl_count:         %u\n", fe->id2.i_chain.cl_count);
+       printk("id2.i_chain.cl_next_free_rec: %u\n",
+              fe->id2.i_chain.cl_next_free_rec);
+       for(i = 0; i < fe->id2.i_chain.cl_next_free_rec; i++) {
+               printk("fe->id2.i_chain.cl_recs[%d].c_free:  %u\n", i,
+                      fe->id2.i_chain.cl_recs[i].c_free);
+               printk("fe->id2.i_chain.cl_recs[%d].c_total: %u\n", i,
+                      fe->id2.i_chain.cl_recs[i].c_total);
+               printk("fe->id2.i_chain.cl_recs[%d].c_blkno: %llu\n", i,
+                      (unsigned long long)fe->id2.i_chain.cl_recs[i].c_blkno);
+       }
+}
+
+/*
+ * 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(osb, 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;
+       }
+
+       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;
+       }
+
+       mutex_lock(&inode_alloc_inode->i_mutex);
+       status = ocfs2_inode_lock(inode_alloc_inode, &alloc_bh, 0);
+       if (status < 0) {
+               mutex_unlock(&inode_alloc_inode->i_mutex);
+               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);
+       mutex_unlock(&inode_alloc_inode->i_mutex);
+
+       iput(inode_alloc_inode);
+       brelse(alloc_bh);
+bail:
+       if (status)
+               mlog_errno(status);
+       return status;
+}