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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * suballoc.c
  *
  * metadata alloc and free
  * Inspired by ext3 block groups.
  *
  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
  */
 
 #include <linux/fs.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
 
 #include <cluster/masklog.h>
 
 #include "ocfs2.h"
 
 #include "alloc.h"
 #include "blockcheck.h"
 #include "dlmglue.h"
 #include "inode.h"
 #include "journal.h"
 #include "localalloc.h"
 #include "suballoc.h"
 #include "super.h"
 #include "sysfile.h"
 #include "uptodate.h"
 #include "ocfs2_trace.h"
 
 #include "buffer_head_io.h"
 
 #define NOT_ALLOC_NEW_GROUP     0
 #define ALLOC_NEW_GROUP         0x1
 #define ALLOC_GROUPS_FROM_GLOBAL    0x2
 
 #define OCFS2_MAX_TO_STEAL      1024
 
 struct ocfs2_suballoc_result {
     u64     sr_bg_blkno;    /* The bg we allocated from.  Set
                        to 0 when a block group is
                        contiguous. */
     u64     sr_bg_stable_blkno; /*
                          * Doesn't change, always
                          * set to target block
                          * group descriptor
                          * block.
                          */
     u64     sr_blkno;   /* The first allocated block */
     unsigned int    sr_bit_offset;  /* The bit in the bg */
     unsigned int    sr_bits;    /* How many bits we claimed */
 };
 
 static u64 ocfs2_group_from_res(struct ocfs2_suballoc_result *res)
 {
     if (res->sr_blkno == 0)
         return 0;
 
     if (res->sr_bg_blkno)
         return res->sr_bg_blkno;
 
     return ocfs2_which_suballoc_group(res->sr_blkno, res->sr_bit_offset);
 }
 
 static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
 static int ocfs2_block_group_fill(handle_t *handle,
                   struct inode *alloc_inode,
                   struct buffer_head *bg_bh,
                   u64 group_blkno,
                   unsigned int group_clusters,
                   u16 my_chain,
                   struct ocfs2_chain_list *cl);
 static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
                    struct inode *alloc_inode,
                    struct buffer_head *bh,
                    u64 max_block,
                    u64 *last_alloc_group,
                    int flags);
 
 static int ocfs2_cluster_group_search(struct inode *inode,
                       struct buffer_head *group_bh,
                       u32 bits_wanted, u32 min_bits,
                       u64 max_block,
                       struct ocfs2_suballoc_result *res);
 static int ocfs2_block_group_search(struct inode *inode,
                     struct buffer_head *group_bh,
                     u32 bits_wanted, u32 min_bits,
                     u64 max_block,
                     struct ocfs2_suballoc_result *res);
 static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
                      handle_t *handle,
                      u32 bits_wanted,
                      u32 min_bits,
                      struct ocfs2_suballoc_result *res);
 static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
                      int nr);
 static int ocfs2_relink_block_group(handle_t *handle,
                     struct inode *alloc_inode,
                     struct buffer_head *fe_bh,
                     struct buffer_head *bg_bh,
                     struct buffer_head *prev_bg_bh,
                     u16 chain);
 static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg,
                              u32 wanted);
 static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
                            u64 bg_blkno,
                            u16 bg_bit_off);
 static inline void ocfs2_block_to_cluster_group(struct inode *inode,
                         u64 data_blkno,
                         u64 *bg_blkno,
                         u16 *bg_bit_off);
 static int ocfs2_reserve_clusters_with_limit(struct ocfs2_super *osb,
                          u32 bits_wanted, u64 max_block,
                          int flags,
                          struct ocfs2_alloc_context **ac);
 
 void ocfs2_free_ac_resource(struct ocfs2_alloc_context *ac)
 {
     struct inode *inode = ac->ac_inode;
 
     if (inode) {
         if (ac->ac_which != OCFS2_AC_USE_LOCAL)
             ocfs2_inode_unlock(inode, 1);
 
         inode_unlock(inode);
 
         iput(inode);
         ac->ac_inode = NULL;
     }
     brelse(ac->ac_bh);
     ac->ac_bh = NULL;
     ac->ac_resv = NULL;
     kfree(ac->ac_find_loc_priv);
     ac->ac_find_loc_priv = NULL;
 }
 
 void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
 {
     ocfs2_free_ac_resource(ac);
     kfree(ac);
 }
 
 static u32 ocfs2_bits_per_group(struct ocfs2_chain_list *cl)
 {
     return (u32)le16_to_cpu(cl->cl_cpg) * (u32)le16_to_cpu(cl->cl_bpc);
 }
 
 #define do_error(fmt, ...)                      \
 do {                                    \
     if (resize)                         \
         mlog(ML_ERROR, fmt, ##__VA_ARGS__);         \
     else                                \
         return ocfs2_error(sb, fmt, ##__VA_ARGS__);     \
 } while (0)
 
 static int ocfs2_validate_gd_self(struct super_block *sb,
                   struct buffer_head *bh,
                   int resize)
 {
     struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
 
     if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
         do_error("Group descriptor #%llu has bad signature %.*s\n",
              (unsigned long long)bh->b_blocknr, 7,
              gd->bg_signature);
     }
 
     if (le64_to_cpu(gd->bg_blkno) != bh->b_blocknr) {
         do_error("Group descriptor #%llu has an invalid bg_blkno of %llu\n",
              (unsigned long long)bh->b_blocknr,
              (unsigned long long)le64_to_cpu(gd->bg_blkno));
     }
 
     if (le32_to_cpu(gd->bg_generation) != OCFS2_SB(sb)->fs_generation) {
         do_error("Group descriptor #%llu has an invalid fs_generation of #%u\n",
              (unsigned long long)bh->b_blocknr,
              le32_to_cpu(gd->bg_generation));
     }
 
     if (le16_to_cpu(gd->bg_free_bits_count) > le16_to_cpu(gd->bg_bits)) {
         do_error("Group descriptor #%llu has bit count %u but claims that %u are free\n",
              (unsigned long long)bh->b_blocknr,
              le16_to_cpu(gd->bg_bits),
              le16_to_cpu(gd->bg_free_bits_count));
     }
 
     if (le16_to_cpu(gd->bg_bits) > (8 * le16_to_cpu(gd->bg_size))) {
         do_error("Group descriptor #%llu has bit count %u but max bitmap bits of %u\n",
              (unsigned long long)bh->b_blocknr,
              le16_to_cpu(gd->bg_bits),
              8 * le16_to_cpu(gd->bg_size));
     }
 
     return 0;
 }
 
 static int ocfs2_validate_gd_parent(struct super_block *sb,
                     struct ocfs2_dinode *di,
                     struct buffer_head *bh,
                     int resize)
 {
     unsigned int max_bits;
     struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
 
     if (di->i_blkno != gd->bg_parent_dinode) {
         do_error("Group descriptor #%llu has bad parent pointer (%llu, expected %llu)\n",
              (unsigned long long)bh->b_blocknr,
              (unsigned long long)le64_to_cpu(gd->bg_parent_dinode),
              (unsigned long long)le64_to_cpu(di->i_blkno));
     }
 
     max_bits = le16_to_cpu(di->id2.i_chain.cl_cpg) * le16_to_cpu(di->id2.i_chain.cl_bpc);
     if (le16_to_cpu(gd->bg_bits) > max_bits) {
         do_error("Group descriptor #%llu has bit count of %u\n",
              (unsigned long long)bh->b_blocknr,
              le16_to_cpu(gd->bg_bits));
     }
 
     /* In resize, we may meet the case bg_chain == cl_next_free_rec. */
     if ((le16_to_cpu(gd->bg_chain) >
          le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) ||
         ((le16_to_cpu(gd->bg_chain) ==
          le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) && !resize)) {
         do_error("Group descriptor #%llu has bad chain %u\n",
              (unsigned long long)bh->b_blocknr,
              le16_to_cpu(gd->bg_chain));
     }
 
     return 0;
 }
 
 #undef do_error
 
 /*
  * This version only prints errors.  It does not fail the filesystem, and
  * exists only for resize.
  */
 int ocfs2_check_group_descriptor(struct super_block *sb,
                  struct ocfs2_dinode *di,
                  struct buffer_head *bh)
 {
     int rc;
     struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
 
     BUG_ON(!buffer_uptodate(bh));
 
     /*
      * If the ecc fails, we return the error but otherwise
      * leave the filesystem running.  We know any error is
      * local to this block.
      */
     rc = ocfs2_validate_meta_ecc(sb, bh->b_data, &gd->bg_check);
     if (rc) {
         mlog(ML_ERROR,
              "Checksum failed for group descriptor %llu\n",
              (unsigned long long)bh->b_blocknr);
     } else
         rc = ocfs2_validate_gd_self(sb, bh, 1);
     if (!rc)
         rc = ocfs2_validate_gd_parent(sb, di, bh, 1);
 
     return rc;
 }
 
 static int ocfs2_validate_group_descriptor(struct super_block *sb,
                        struct buffer_head *bh)
 {
     int rc;
     struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
 
     trace_ocfs2_validate_group_descriptor(
                     (unsigned long long)bh->b_blocknr);
 
     BUG_ON(!buffer_uptodate(bh));
 
     /*
      * If the ecc fails, we return the error but otherwise
      * leave the filesystem running.  We know any error is
      * local to this block.
      */
     rc = ocfs2_validate_meta_ecc(sb, bh->b_data, &gd->bg_check);
     if (rc)
         return rc;
 
     /*
      * Errors after here are fatal.
      */
 
     return ocfs2_validate_gd_self(sb, bh, 0);
 }
 
 int ocfs2_read_group_descriptor(struct inode *inode, struct ocfs2_dinode *di,
                 u64 gd_blkno, struct buffer_head **bh)
 {
     int rc;
     struct buffer_head *tmp = *bh;
 
     rc = ocfs2_read_block(INODE_CACHE(inode), gd_blkno, &tmp,
                   ocfs2_validate_group_descriptor);
     if (rc)
         goto out;
 
     rc = ocfs2_validate_gd_parent(inode->i_sb, di, tmp, 0);
     if (rc) {
         brelse(tmp);
         goto out;
     }
 
     /* If ocfs2_read_block() got us a new bh, pass it up. */
     if (!*bh)
         *bh = tmp;
 
 out:
     return rc;
 }
 
 static void ocfs2_bg_discontig_add_extent(struct ocfs2_super *osb,
                       struct ocfs2_group_desc *bg,
                       struct ocfs2_chain_list *cl,
                       u64 p_blkno, unsigned int clusters)
 {
     struct ocfs2_extent_list *el = &bg->bg_list;
     struct ocfs2_extent_rec *rec;
 
     BUG_ON(!ocfs2_supports_discontig_bg(osb));
     if (!el->l_next_free_rec)
         el->l_count = cpu_to_le16(ocfs2_extent_recs_per_gd(osb->sb));
     rec = &el->l_recs[le16_to_cpu(el->l_next_free_rec)];
     rec->e_blkno = cpu_to_le64(p_blkno);
     rec->e_cpos = cpu_to_le32(le16_to_cpu(bg->bg_bits) /
                   le16_to_cpu(cl->cl_bpc));
     rec->e_leaf_clusters = cpu_to_le16(clusters);
     le16_add_cpu(&bg->bg_bits, clusters * le16_to_cpu(cl->cl_bpc));
     le16_add_cpu(&bg->bg_free_bits_count,
              clusters * le16_to_cpu(cl->cl_bpc));
     le16_add_cpu(&el->l_next_free_rec, 1);
 }
 
 static int ocfs2_block_group_fill(handle_t *handle,
                   struct inode *alloc_inode,
                   struct buffer_head *bg_bh,
                   u64 group_blkno,
                   unsigned int group_clusters,
                   u16 my_chain,
                   struct ocfs2_chain_list *cl)
 {
     int status = 0;
     struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
     struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
     struct super_block * sb = alloc_inode->i_sb;
 
     if (((unsigned long long) bg_bh->b_blocknr) != group_blkno) {
         status = ocfs2_error(alloc_inode->i_sb,
                      "group block (%llu) != b_blocknr (%llu)\n",
                      (unsigned long long)group_blkno,
                      (unsigned long long) bg_bh->b_blocknr);
         goto bail;
     }
 
     status = ocfs2_journal_access_gd(handle,
                      INODE_CACHE(alloc_inode),
                      bg_bh,
                      OCFS2_JOURNAL_ACCESS_CREATE);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     memset(bg, 0, sb->s_blocksize);
     strcpy(bg->bg_signature, OCFS2_GROUP_DESC_SIGNATURE);
     bg->bg_generation = cpu_to_le32(osb->fs_generation);
     bg->bg_size = cpu_to_le16(ocfs2_group_bitmap_size(sb, 1,
                         osb->s_feature_incompat));
     bg->bg_chain = cpu_to_le16(my_chain);
     bg->bg_next_group = cl->cl_recs[my_chain].c_blkno;
     bg->bg_parent_dinode = cpu_to_le64(OCFS2_I(alloc_inode)->ip_blkno);
     bg->bg_blkno = cpu_to_le64(group_blkno);
     if (group_clusters == le16_to_cpu(cl->cl_cpg))
         bg->bg_bits = cpu_to_le16(ocfs2_bits_per_group(cl));
     else
         ocfs2_bg_discontig_add_extent(osb, bg, cl, group_blkno,
                           group_clusters);
 
     /* set the 1st bit in the bitmap to account for the descriptor block */
     ocfs2_set_bit(0, (unsigned long *)bg->bg_bitmap);
     bg->bg_free_bits_count = cpu_to_le16(le16_to_cpu(bg->bg_bits) - 1);
 
     ocfs2_journal_dirty(handle, bg_bh);
 
     /* There is no need to zero out or otherwise initialize the
      * other blocks in a group - All valid FS metadata in a block
      * group stores the superblock fs_generation value at
      * allocation time. */
 
 bail:
     if (status)
         mlog_errno(status);
     return status;
 }
 
 static inline u16 ocfs2_find_smallest_chain(struct ocfs2_chain_list *cl)
 {
     u16 curr, best;
 
     best = curr = 0;
     while (curr < le16_to_cpu(cl->cl_count)) {
         if (le32_to_cpu(cl->cl_recs[best].c_total) >
             le32_to_cpu(cl->cl_recs[curr].c_total))
             best = curr;
         curr++;
     }
     return best;
 }
 
 static struct buffer_head *
 ocfs2_block_group_alloc_contig(struct ocfs2_super *osb, handle_t *handle,
                    struct inode *alloc_inode,
                    struct ocfs2_alloc_context *ac,
                    struct ocfs2_chain_list *cl)
 {
     int status;
     u32 bit_off, num_bits;
     u64 bg_blkno;
     struct buffer_head *bg_bh;
     unsigned int alloc_rec = ocfs2_find_smallest_chain(cl);
 
     status = ocfs2_claim_clusters(handle, ac,
                       le16_to_cpu(cl->cl_cpg), &bit_off,
                       &num_bits);
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
 
     /* setup the group */
     bg_blkno = ocfs2_clusters_to_blocks(osb->sb, bit_off);
     trace_ocfs2_block_group_alloc_contig(
          (unsigned long long)bg_blkno, alloc_rec);
 
     bg_bh = sb_getblk(osb->sb, bg_blkno);
     if (!bg_bh) {
         status = -ENOMEM;
         mlog_errno(status);
         goto bail;
     }
     ocfs2_set_new_buffer_uptodate(INODE_CACHE(alloc_inode), bg_bh);
 
     status = ocfs2_block_group_fill(handle, alloc_inode, bg_bh,
                     bg_blkno, num_bits, alloc_rec, cl);
     if (status < 0) {
         brelse(bg_bh);
         mlog_errno(status);
     }
 
 bail:
     return status ? ERR_PTR(status) : bg_bh;
 }
 
 static int ocfs2_block_group_claim_bits(struct ocfs2_super *osb,
                     handle_t *handle,
                     struct ocfs2_alloc_context *ac,
                     unsigned int min_bits,
                     u32 *bit_off, u32 *num_bits)
 {
     int status = 0;
 
     while (min_bits) {
         status = ocfs2_claim_clusters(handle, ac, min_bits,
                           bit_off, num_bits);
         if (status != -ENOSPC)
             break;
 
         min_bits >>= 1;
     }
 
     return status;
 }
 
 static int ocfs2_block_group_grow_discontig(handle_t *handle,
                         struct inode *alloc_inode,
                         struct buffer_head *bg_bh,
                         struct ocfs2_alloc_context *ac,
                         struct ocfs2_chain_list *cl,
                         unsigned int min_bits)
 {
     int status;
     struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
     struct ocfs2_group_desc *bg =
         (struct ocfs2_group_desc *)bg_bh->b_data;
     unsigned int needed = le16_to_cpu(cl->cl_cpg) -
              le16_to_cpu(bg->bg_bits) / le16_to_cpu(cl->cl_bpc);
     u32 p_cpos, clusters;
     u64 p_blkno;
     struct ocfs2_extent_list *el = &bg->bg_list;
 
     status = ocfs2_journal_access_gd(handle,
                      INODE_CACHE(alloc_inode),
                      bg_bh,
                      OCFS2_JOURNAL_ACCESS_CREATE);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     while ((needed > 0) && (le16_to_cpu(el->l_next_free_rec) <
                 le16_to_cpu(el->l_count))) {
         if (min_bits > needed)
             min_bits = needed;
         status = ocfs2_block_group_claim_bits(osb, handle, ac,
                               min_bits, &p_cpos,
                               &clusters);
         if (status < 0) {
             if (status != -ENOSPC)
                 mlog_errno(status);
             goto bail;
         }
         p_blkno = ocfs2_clusters_to_blocks(osb->sb, p_cpos);
         ocfs2_bg_discontig_add_extent(osb, bg, cl, p_blkno,
                           clusters);
 
         min_bits = clusters;
         needed = le16_to_cpu(cl->cl_cpg) -
              le16_to_cpu(bg->bg_bits) / le16_to_cpu(cl->cl_bpc);
     }
 
     if (needed > 0) {
         /*
          * We have used up all the extent rec but can't fill up
          * the cpg. So bail out.
          */
         status = -ENOSPC;
         goto bail;
     }
 
     ocfs2_journal_dirty(handle, bg_bh);
 
 bail:
     return status;
 }
 
 static void ocfs2_bg_alloc_cleanup(handle_t *handle,
                    struct ocfs2_alloc_context *cluster_ac,
                    struct inode *alloc_inode,
                    struct buffer_head *bg_bh)
 {
     int i, ret;
     struct ocfs2_group_desc *bg;
     struct ocfs2_extent_list *el;
     struct ocfs2_extent_rec *rec;
 
     if (!bg_bh)
         return;
 
     bg = (struct ocfs2_group_desc *)bg_bh->b_data;
     el = &bg->bg_list;
     for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
         rec = &el->l_recs[i];
         ret = ocfs2_free_clusters(handle, cluster_ac->ac_inode,
                       cluster_ac->ac_bh,
                       le64_to_cpu(rec->e_blkno),
                       le16_to_cpu(rec->e_leaf_clusters));
         if (ret)
             mlog_errno(ret);
         /* Try all the clusters to free */
     }
 
     ocfs2_remove_from_cache(INODE_CACHE(alloc_inode), bg_bh);
     brelse(bg_bh);
 }
 
 static struct buffer_head *
 ocfs2_block_group_alloc_discontig(handle_t *handle,
                   struct inode *alloc_inode,
                   struct ocfs2_alloc_context *ac,
                   struct ocfs2_chain_list *cl)
 {
     int status;
     u32 bit_off, num_bits;
     u64 bg_blkno;
     unsigned int min_bits = le16_to_cpu(cl->cl_cpg) >> 1;
     struct buffer_head *bg_bh = NULL;
     unsigned int alloc_rec = ocfs2_find_smallest_chain(cl);
     struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
 
     if (!ocfs2_supports_discontig_bg(osb)) {
         status = -ENOSPC;
         goto bail;
     }
 
     status = ocfs2_extend_trans(handle,
                     ocfs2_calc_bg_discontig_credits(osb->sb));
     if (status) {
         mlog_errno(status);
         goto bail;
     }
 
     /*
      * We're going to be grabbing from multiple cluster groups.
      * We don't have enough credits to relink them all, and the
      * cluster groups will be staying in cache for the duration of
      * this operation.
      */
     ac->ac_disable_chain_relink = 1;
 
     /* Claim the first region */
     status = ocfs2_block_group_claim_bits(osb, handle, ac, min_bits,
                           &bit_off, &num_bits);
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
     min_bits = num_bits;
 
     /* setup the group */
     bg_blkno = ocfs2_clusters_to_blocks(osb->sb, bit_off);
     trace_ocfs2_block_group_alloc_discontig(
                 (unsigned long long)bg_blkno, alloc_rec);
 
     bg_bh = sb_getblk(osb->sb, bg_blkno);
     if (!bg_bh) {
         status = -ENOMEM;
         mlog_errno(status);
         goto bail;
     }
     ocfs2_set_new_buffer_uptodate(INODE_CACHE(alloc_inode), bg_bh);
 
     status = ocfs2_block_group_fill(handle, alloc_inode, bg_bh,
                     bg_blkno, num_bits, alloc_rec, cl);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     status = ocfs2_block_group_grow_discontig(handle, alloc_inode,
                           bg_bh, ac, cl, min_bits);
     if (status)
         mlog_errno(status);
 
 bail:
     if (status)
         ocfs2_bg_alloc_cleanup(handle, ac, alloc_inode, bg_bh);
     return status ? ERR_PTR(status) : bg_bh;
 }
 
 /*
  * We expect the block group allocator to already be locked.
  */
 static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
                    struct inode *alloc_inode,
                    struct buffer_head *bh,
                    u64 max_block,
                    u64 *last_alloc_group,
                    int flags)
 {
     int status, credits;
     struct ocfs2_dinode *fe = (struct ocfs2_dinode *) bh->b_data;
     struct ocfs2_chain_list *cl;
     struct ocfs2_alloc_context *ac = NULL;
     handle_t *handle = NULL;
     u16 alloc_rec;
     struct buffer_head *bg_bh = NULL;
     struct ocfs2_group_desc *bg;
 
     BUG_ON(ocfs2_is_cluster_bitmap(alloc_inode));
 
     cl = &fe->id2.i_chain;
     status = ocfs2_reserve_clusters_with_limit(osb,
                            le16_to_cpu(cl->cl_cpg),
                            max_block, flags, &ac);
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
 
     credits = ocfs2_calc_group_alloc_credits(osb->sb,
                          le16_to_cpu(cl->cl_cpg));
     handle = ocfs2_start_trans(osb, credits);
     if (IS_ERR(handle)) {
         status = PTR_ERR(handle);
         handle = NULL;
         mlog_errno(status);
         goto bail;
     }
 
     if (last_alloc_group && *last_alloc_group != 0) {
         trace_ocfs2_block_group_alloc(
                 (unsigned long long)*last_alloc_group);
         ac->ac_last_group = *last_alloc_group;
     }
 
     bg_bh = ocfs2_block_group_alloc_contig(osb, handle, alloc_inode,
                            ac, cl);
     if (PTR_ERR(bg_bh) == -ENOSPC)
         bg_bh = ocfs2_block_group_alloc_discontig(handle,
                               alloc_inode,
                               ac, cl);
     if (IS_ERR(bg_bh)) {
         status = PTR_ERR(bg_bh);
         bg_bh = NULL;
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
     bg = (struct ocfs2_group_desc *) bg_bh->b_data;
 
     status = ocfs2_journal_access_di(handle, INODE_CACHE(alloc_inode),
                      bh, OCFS2_JOURNAL_ACCESS_WRITE);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     alloc_rec = le16_to_cpu(bg->bg_chain);
     le32_add_cpu(&cl->cl_recs[alloc_rec].c_free,
              le16_to_cpu(bg->bg_free_bits_count));
     le32_add_cpu(&cl->cl_recs[alloc_rec].c_total,
              le16_to_cpu(bg->bg_bits));
     cl->cl_recs[alloc_rec].c_blkno = bg->bg_blkno;
     if (le16_to_cpu(cl->cl_next_free_rec) < le16_to_cpu(cl->cl_count))
         le16_add_cpu(&cl->cl_next_free_rec, 1);
 
     le32_add_cpu(&fe->id1.bitmap1.i_used, le16_to_cpu(bg->bg_bits) -
                     le16_to_cpu(bg->bg_free_bits_count));
     le32_add_cpu(&fe->id1.bitmap1.i_total, le16_to_cpu(bg->bg_bits));
     le32_add_cpu(&fe->i_clusters, le16_to_cpu(cl->cl_cpg));
 
     ocfs2_journal_dirty(handle, bh);
 
     spin_lock(&OCFS2_I(alloc_inode)->ip_lock);
     OCFS2_I(alloc_inode)->ip_clusters = le32_to_cpu(fe->i_clusters);
     fe->i_size = cpu_to_le64(ocfs2_clusters_to_bytes(alloc_inode->i_sb,
                          le32_to_cpu(fe->i_clusters)));
     spin_unlock(&OCFS2_I(alloc_inode)->ip_lock);
     i_size_write(alloc_inode, le64_to_cpu(fe->i_size));
     alloc_inode->i_blocks = ocfs2_inode_sector_count(alloc_inode);
     ocfs2_update_inode_fsync_trans(handle, alloc_inode, 0);
 
     status = 0;
 
     /* save the new last alloc group so that the caller can cache it. */
     if (last_alloc_group)
         *last_alloc_group = ac->ac_last_group;
 
 bail:
     if (handle)
         ocfs2_commit_trans(osb, handle);
 
     if (ac)
         ocfs2_free_alloc_context(ac);
 
     brelse(bg_bh);
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
                        struct ocfs2_alloc_context *ac,
                        int type,
                        u32 slot,
                        u64 *last_alloc_group,
                        int flags)
 {
     int status;
     u32 bits_wanted = ac->ac_bits_wanted;
     struct inode *alloc_inode;
     struct buffer_head *bh = NULL;
     struct ocfs2_dinode *fe;
     u32 free_bits;
 
     alloc_inode = ocfs2_get_system_file_inode(osb, type, slot);
     if (!alloc_inode) {
         mlog_errno(-EINVAL);
         return -EINVAL;
     }
 
     inode_lock(alloc_inode);
 
     status = ocfs2_inode_lock(alloc_inode, &bh, 1);
     if (status < 0) {
         inode_unlock(alloc_inode);
         iput(alloc_inode);
 
         mlog_errno(status);
         return status;
     }
 
     ac->ac_inode = alloc_inode;
     ac->ac_alloc_slot = slot;
 
     fe = (struct ocfs2_dinode *) bh->b_data;
 
     /* The bh was validated by the inode read inside
      * ocfs2_inode_lock().  Any corruption is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
 
     if (!(fe->i_flags & cpu_to_le32(OCFS2_CHAIN_FL))) {
         status = ocfs2_error(alloc_inode->i_sb,
                      "Invalid chain allocator %llu\n",
                      (unsigned long long)le64_to_cpu(fe->i_blkno));
         goto bail;
     }
 
     free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
         le32_to_cpu(fe->id1.bitmap1.i_used);
 
     if (bits_wanted > free_bits) {
         /* cluster bitmap never grows */
         if (ocfs2_is_cluster_bitmap(alloc_inode)) {
             trace_ocfs2_reserve_suballoc_bits_nospc(bits_wanted,
                                 free_bits);
             status = -ENOSPC;
             goto bail;
         }
 
         if (!(flags & ALLOC_NEW_GROUP)) {
             trace_ocfs2_reserve_suballoc_bits_no_new_group(
                         slot, bits_wanted, free_bits);
             status = -ENOSPC;
             goto bail;
         }
 
         status = ocfs2_block_group_alloc(osb, alloc_inode, bh,
                          ac->ac_max_block,
                          last_alloc_group, flags);
         if (status < 0) {
             if (status != -ENOSPC)
                 mlog_errno(status);
             goto bail;
         }
         atomic_inc(&osb->alloc_stats.bg_extends);
 
         /* You should never ask for this much metadata */
         BUG_ON(bits_wanted >
                (le32_to_cpu(fe->id1.bitmap1.i_total)
             - le32_to_cpu(fe->id1.bitmap1.i_used)));
     }
 
     get_bh(bh);
     ac->ac_bh = bh;
 bail:
     brelse(bh);
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 static void ocfs2_init_inode_steal_slot(struct ocfs2_super *osb)
 {
     spin_lock(&osb->osb_lock);
     osb->s_inode_steal_slot = OCFS2_INVALID_SLOT;
     spin_unlock(&osb->osb_lock);
     atomic_set(&osb->s_num_inodes_stolen, 0);
 }
 
 static void ocfs2_init_meta_steal_slot(struct ocfs2_super *osb)
 {
     spin_lock(&osb->osb_lock);
     osb->s_meta_steal_slot = OCFS2_INVALID_SLOT;
     spin_unlock(&osb->osb_lock);
     atomic_set(&osb->s_num_meta_stolen, 0);
 }
 
 void ocfs2_init_steal_slots(struct ocfs2_super *osb)
 {
     ocfs2_init_inode_steal_slot(osb);
     ocfs2_init_meta_steal_slot(osb);
 }
 
 static void __ocfs2_set_steal_slot(struct ocfs2_super *osb, int slot, int type)
 {
     spin_lock(&osb->osb_lock);
     if (type == INODE_ALLOC_SYSTEM_INODE)
         osb->s_inode_steal_slot = (u16)slot;
     else if (type == EXTENT_ALLOC_SYSTEM_INODE)
         osb->s_meta_steal_slot = (u16)slot;
     spin_unlock(&osb->osb_lock);
 }
 
 static int __ocfs2_get_steal_slot(struct ocfs2_super *osb, int type)
 {
     int slot = OCFS2_INVALID_SLOT;
 
     spin_lock(&osb->osb_lock);
     if (type == INODE_ALLOC_SYSTEM_INODE)
         slot = osb->s_inode_steal_slot;
     else if (type == EXTENT_ALLOC_SYSTEM_INODE)
         slot = osb->s_meta_steal_slot;
     spin_unlock(&osb->osb_lock);
 
     return slot;
 }
 
 static int ocfs2_get_inode_steal_slot(struct ocfs2_super *osb)
 {
     return __ocfs2_get_steal_slot(osb, INODE_ALLOC_SYSTEM_INODE);
 }
 
 static int ocfs2_get_meta_steal_slot(struct ocfs2_super *osb)
 {
     return __ocfs2_get_steal_slot(osb, EXTENT_ALLOC_SYSTEM_INODE);
 }
 
 static int ocfs2_steal_resource(struct ocfs2_super *osb,
                 struct ocfs2_alloc_context *ac,
                 int type)
 {
     int i, status = -ENOSPC;
     int slot = __ocfs2_get_steal_slot(osb, type);
 
     /* Start to steal resource from the first slot after ours. */
     if (slot == OCFS2_INVALID_SLOT)
         slot = osb->slot_num + 1;
 
     for (i = 0; i < osb->max_slots; i++, slot++) {
         if (slot == osb->max_slots)
             slot = 0;
 
         if (slot == osb->slot_num)
             continue;
 
         status = ocfs2_reserve_suballoc_bits(osb, ac,
                              type,
                              (u32)slot, NULL,
                              NOT_ALLOC_NEW_GROUP);
         if (status >= 0) {
             __ocfs2_set_steal_slot(osb, slot, type);
             break;
         }
 
         ocfs2_free_ac_resource(ac);
     }
 
     return status;
 }
 
 static int ocfs2_steal_inode(struct ocfs2_super *osb,
                  struct ocfs2_alloc_context *ac)
 {
     return ocfs2_steal_resource(osb, ac, INODE_ALLOC_SYSTEM_INODE);
 }
 
 static int ocfs2_steal_meta(struct ocfs2_super *osb,
                 struct ocfs2_alloc_context *ac)
 {
     return ocfs2_steal_resource(osb, ac, EXTENT_ALLOC_SYSTEM_INODE);
 }
 
 int ocfs2_reserve_new_metadata_blocks(struct ocfs2_super *osb,
                       int blocks,
                       struct ocfs2_alloc_context **ac)
 {
     int status;
     int slot = ocfs2_get_meta_steal_slot(osb);
 
     *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
     if (!(*ac)) {
         status = -ENOMEM;
         mlog_errno(status);
         goto bail;
     }
 
     (*ac)->ac_bits_wanted = blocks;
     (*ac)->ac_which = OCFS2_AC_USE_META;
     (*ac)->ac_group_search = ocfs2_block_group_search;
 
     if (slot != OCFS2_INVALID_SLOT &&
         atomic_read(&osb->s_num_meta_stolen) < OCFS2_MAX_TO_STEAL)
         goto extent_steal;
 
     atomic_set(&osb->s_num_meta_stolen, 0);
     status = ocfs2_reserve_suballoc_bits(osb, (*ac),
                          EXTENT_ALLOC_SYSTEM_INODE,
                          (u32)osb->slot_num, NULL,
                          ALLOC_GROUPS_FROM_GLOBAL|ALLOC_NEW_GROUP);
 
 
     if (status >= 0) {
         status = 0;
         if (slot != OCFS2_INVALID_SLOT)
             ocfs2_init_meta_steal_slot(osb);
         goto bail;
     } else if (status < 0 && status != -ENOSPC) {
         mlog_errno(status);
         goto bail;
     }
 
     ocfs2_free_ac_resource(*ac);
 
 extent_steal:
     status = ocfs2_steal_meta(osb, *ac);
     atomic_inc(&osb->s_num_meta_stolen);
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
 
     status = 0;
 bail:
     if ((status < 0) && *ac) {
         ocfs2_free_alloc_context(*ac);
         *ac = NULL;
     }
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 int ocfs2_reserve_new_metadata(struct ocfs2_super *osb,
                    struct ocfs2_extent_list *root_el,
                    struct ocfs2_alloc_context **ac)
 {
     return ocfs2_reserve_new_metadata_blocks(osb,
                     ocfs2_extend_meta_needed(root_el),
                     ac);
 }
 
 int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
                 struct ocfs2_alloc_context **ac)
 {
     int status;
     int slot = ocfs2_get_inode_steal_slot(osb);
     u64 alloc_group;
 
     *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
     if (!(*ac)) {
         status = -ENOMEM;
         mlog_errno(status);
         goto bail;
     }
 
     (*ac)->ac_bits_wanted = 1;
     (*ac)->ac_which = OCFS2_AC_USE_INODE;
 
     (*ac)->ac_group_search = ocfs2_block_group_search;
 
     /*
      * stat(2) can't handle i_ino > 32bits, so we tell the
      * lower levels not to allocate us a block group past that
      * limit.  The 'inode64' mount option avoids this behavior.
      */
     if (!(osb->s_mount_opt & OCFS2_MOUNT_INODE64))
         (*ac)->ac_max_block = (u32)~0U;
 
     /*
      * slot is set when we successfully steal inode from other nodes.
      * It is reset in 3 places:
      * 1. when we flush the truncate log
      * 2. when we complete local alloc recovery.
      * 3. when we successfully allocate from our own slot.
      * After it is set, we will go on stealing inodes until we find the
      * need to check our slots to see whether there is some space for us.
      */
     if (slot != OCFS2_INVALID_SLOT &&
         atomic_read(&osb->s_num_inodes_stolen) < OCFS2_MAX_TO_STEAL)
         goto inode_steal;
 
     atomic_set(&osb->s_num_inodes_stolen, 0);
     alloc_group = osb->osb_inode_alloc_group;
     status = ocfs2_reserve_suballoc_bits(osb, *ac,
                          INODE_ALLOC_SYSTEM_INODE,
                          (u32)osb->slot_num,
                          &alloc_group,
                          ALLOC_NEW_GROUP |
                          ALLOC_GROUPS_FROM_GLOBAL);
     if (status >= 0) {
         status = 0;
 
         spin_lock(&osb->osb_lock);
         osb->osb_inode_alloc_group = alloc_group;
         spin_unlock(&osb->osb_lock);
         trace_ocfs2_reserve_new_inode_new_group(
             (unsigned long long)alloc_group);
 
         /*
          * Some inodes must be freed by us, so try to allocate
          * from our own next time.
          */
         if (slot != OCFS2_INVALID_SLOT)
             ocfs2_init_inode_steal_slot(osb);
         goto bail;
     } else if (status < 0 && status != -ENOSPC) {
         mlog_errno(status);
         goto bail;
     }
 
     ocfs2_free_ac_resource(*ac);
 
 inode_steal:
     status = ocfs2_steal_inode(osb, *ac);
     atomic_inc(&osb->s_num_inodes_stolen);
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
 
     status = 0;
 bail:
     if ((status < 0) && *ac) {
         ocfs2_free_alloc_context(*ac);
         *ac = NULL;
     }
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 /* local alloc code has to do the same thing, so rather than do this
  * twice.. */
 int ocfs2_reserve_cluster_bitmap_bits(struct ocfs2_super *osb,
                       struct ocfs2_alloc_context *ac)
 {
     int status;
 
     ac->ac_which = OCFS2_AC_USE_MAIN;
     ac->ac_group_search = ocfs2_cluster_group_search;
 
     status = ocfs2_reserve_suballoc_bits(osb, ac,
                          GLOBAL_BITMAP_SYSTEM_INODE,
                          OCFS2_INVALID_SLOT, NULL,
                          ALLOC_NEW_GROUP);
     if (status < 0 && status != -ENOSPC)
         mlog_errno(status);
 
     return status;
 }
 
 /* Callers don't need to care which bitmap (local alloc or main) to
  * use so we figure it out for them, but unfortunately this clutters
  * things a bit. */
 static int ocfs2_reserve_clusters_with_limit(struct ocfs2_super *osb,
                          u32 bits_wanted, u64 max_block,
                          int flags,
                          struct ocfs2_alloc_context **ac)
 {
     int status, ret = 0;
     int retried = 0;
 
     *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
     if (!(*ac)) {
         status = -ENOMEM;
         mlog_errno(status);
         goto bail;
     }
 
     (*ac)->ac_bits_wanted = bits_wanted;
     (*ac)->ac_max_block = max_block;
 
     status = -ENOSPC;
     if (!(flags & ALLOC_GROUPS_FROM_GLOBAL) &&
         ocfs2_alloc_should_use_local(osb, bits_wanted)) {
         status = ocfs2_reserve_local_alloc_bits(osb,
                             bits_wanted,
                             *ac);
         if ((status < 0) && (status != -ENOSPC)) {
             mlog_errno(status);
             goto bail;
         }
     }
 
     if (status == -ENOSPC) {
 retry:
         status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);
         /* Retry if there is sufficient space cached in truncate log */
         if (status == -ENOSPC && !retried) {
             retried = 1;
             ocfs2_inode_unlock((*ac)->ac_inode, 1);
             inode_unlock((*ac)->ac_inode);
 
             ret = ocfs2_try_to_free_truncate_log(osb, bits_wanted);
             if (ret == 1) {
                 iput((*ac)->ac_inode);
                 (*ac)->ac_inode = NULL;
                 goto retry;
             }
 
             if (ret < 0)
                 mlog_errno(ret);
 
             inode_lock((*ac)->ac_inode);
             ret = ocfs2_inode_lock((*ac)->ac_inode, NULL, 1);
             if (ret < 0) {
                 mlog_errno(ret);
                 inode_unlock((*ac)->ac_inode);
                 iput((*ac)->ac_inode);
                 (*ac)->ac_inode = NULL;
                 goto bail;
             }
         }
         if (status < 0) {
             if (status != -ENOSPC)
                 mlog_errno(status);
             goto bail;
         }
     }
 
     status = 0;
 bail:
     if ((status < 0) && *ac) {
         ocfs2_free_alloc_context(*ac);
         *ac = NULL;
     }
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 int ocfs2_reserve_clusters(struct ocfs2_super *osb,
                u32 bits_wanted,
                struct ocfs2_alloc_context **ac)
 {
     return ocfs2_reserve_clusters_with_limit(osb, bits_wanted, 0,
                          ALLOC_NEW_GROUP, ac);
 }
 
 /*
  * More or less lifted from ext3. I'll leave their description below:
  *
  * "For ext3 allocations, we must not reuse any blocks which are
  * allocated in the bitmap buffer's "last committed data" copy.  This
  * prevents deletes from freeing up the page for reuse until we have
  * committed the delete transaction.
  *
  * If we didn't do this, then deleting something and reallocating it as
  * data would allow the old block to be overwritten before the
  * transaction committed (because we force data to disk before commit).
  * This would lead to corruption if we crashed between overwriting the
  * data and committing the delete.
  *
  * @@@ We may want to make this allocation behaviour conditional on
  * data-writes at some point, and disable it for metadata allocations or
  * sync-data inodes."
  *
  * Note: OCFS2 already does this differently for metadata vs data
  * allocations, as those bitmaps are separate and undo access is never
  * called on a metadata group descriptor.
  */
 static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
                      int nr)
 {
     struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
     struct journal_head *jh;
     int ret;
 
     if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
         return 0;
 
     jh = jbd2_journal_grab_journal_head(bg_bh);
     if (!jh)
         return 1;
 
     spin_lock(&jh->b_state_lock);
     bg = (struct ocfs2_group_desc *) jh->b_committed_data;
     if (bg)
         ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
     else
         ret = 1;
     spin_unlock(&jh->b_state_lock);
     jbd2_journal_put_journal_head(jh);
 
     return ret;
 }
 
 static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
                          struct buffer_head *bg_bh,
                          unsigned int bits_wanted,
                          unsigned int total_bits,
                          struct ocfs2_suballoc_result *res)
 {
     void *bitmap;
     u16 best_offset, best_size;
     int offset, start, found, status = 0;
     struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
 
     /* Callers got this descriptor from
      * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
 
     found = start = best_offset = best_size = 0;
     bitmap = bg->bg_bitmap;
 
     while((offset = ocfs2_find_next_zero_bit(bitmap, total_bits, start)) != -1) {
         if (offset == total_bits)
             break;
 
         if (!ocfs2_test_bg_bit_allocatable(bg_bh, offset)) {
             /* We found a zero, but we can't use it as it
              * hasn't been put to disk yet! */
             found = 0;
             start = offset + 1;
         } else if (offset == start) {
             /* we found a zero */
             found++;
             /* move start to the next bit to test */
             start++;
         } else {
             /* got a zero after some ones */
             found = 1;
             start = offset + 1;
         }
         if (found > best_size) {
             best_size = found;
             best_offset = start - found;
         }
         /* we got everything we needed */
         if (found == bits_wanted) {
             /* mlog(0, "Found it all!\n"); */
             break;
         }
     }
 
     if (best_size) {
         res->sr_bit_offset = best_offset;
         res->sr_bits = best_size;
     } else {
         status = -ENOSPC;
         /* No error log here -- see the comment above
          * ocfs2_test_bg_bit_allocatable */
     }
 
     return status;
 }
 
 int ocfs2_block_group_set_bits(handle_t *handle,
                          struct inode *alloc_inode,
                          struct ocfs2_group_desc *bg,
                          struct buffer_head *group_bh,
                          unsigned int bit_off,
                          unsigned int num_bits)
 {
     int status;
     void *bitmap = bg->bg_bitmap;
     int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
 
     /* All callers get the descriptor via
      * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
     BUG_ON(le16_to_cpu(bg->bg_free_bits_count) < num_bits);
 
     trace_ocfs2_block_group_set_bits(bit_off, num_bits);
 
     if (ocfs2_is_cluster_bitmap(alloc_inode))
         journal_type = OCFS2_JOURNAL_ACCESS_UNDO;
 
     status = ocfs2_journal_access_gd(handle,
                      INODE_CACHE(alloc_inode),
                      group_bh,
                      journal_type);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     le16_add_cpu(&bg->bg_free_bits_count, -num_bits);
     if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
         return ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit count %u but claims %u are freed. num_bits %d\n",
                    (unsigned long long)le64_to_cpu(bg->bg_blkno),
                    le16_to_cpu(bg->bg_bits),
                    le16_to_cpu(bg->bg_free_bits_count),
                    num_bits);
     }
     while(num_bits--)
         ocfs2_set_bit(bit_off++, bitmap);
 
     ocfs2_journal_dirty(handle, group_bh);
 
 bail:
     return status;
 }
 
 /* find the one with the most empty bits */
 static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl)
 {
     u16 curr, best;
 
     BUG_ON(!cl->cl_next_free_rec);
 
     best = curr = 0;
     while (curr < le16_to_cpu(cl->cl_next_free_rec)) {
         if (le32_to_cpu(cl->cl_recs[curr].c_free) >
             le32_to_cpu(cl->cl_recs[best].c_free))
             best = curr;
         curr++;
     }
 
     BUG_ON(best >= le16_to_cpu(cl->cl_next_free_rec));
     return best;
 }
 
 static int ocfs2_relink_block_group(handle_t *handle,
                     struct inode *alloc_inode,
                     struct buffer_head *fe_bh,
                     struct buffer_head *bg_bh,
                     struct buffer_head *prev_bg_bh,
                     u16 chain)
 {
     int status;
     /* there is a really tiny chance the journal calls could fail,
      * but we wouldn't want inconsistent blocks in *any* case. */
     u64 bg_ptr, prev_bg_ptr;
     struct ocfs2_dinode *fe = (struct ocfs2_dinode *) fe_bh->b_data;
     struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
     struct ocfs2_group_desc *prev_bg = (struct ocfs2_group_desc *) prev_bg_bh->b_data;
 
     /* The caller got these descriptors from
      * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
     BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(prev_bg));
 
     trace_ocfs2_relink_block_group(
         (unsigned long long)le64_to_cpu(fe->i_blkno), chain,
         (unsigned long long)le64_to_cpu(bg->bg_blkno),
         (unsigned long long)le64_to_cpu(prev_bg->bg_blkno));
 
     bg_ptr = le64_to_cpu(bg->bg_next_group);
     prev_bg_ptr = le64_to_cpu(prev_bg->bg_next_group);
 
     status = ocfs2_journal_access_gd(handle, INODE_CACHE(alloc_inode),
                      prev_bg_bh,
                      OCFS2_JOURNAL_ACCESS_WRITE);
     if (status < 0)
         goto out;
 
     prev_bg->bg_next_group = bg->bg_next_group;
     ocfs2_journal_dirty(handle, prev_bg_bh);
 
     status = ocfs2_journal_access_gd(handle, INODE_CACHE(alloc_inode),
                      bg_bh, OCFS2_JOURNAL_ACCESS_WRITE);
     if (status < 0)
         goto out_rollback_prev_bg;
 
     bg->bg_next_group = fe->id2.i_chain.cl_recs[chain].c_blkno;
     ocfs2_journal_dirty(handle, bg_bh);
 
     status = ocfs2_journal_access_di(handle, INODE_CACHE(alloc_inode),
                      fe_bh, OCFS2_JOURNAL_ACCESS_WRITE);
     if (status < 0)
         goto out_rollback_bg;
 
     fe->id2.i_chain.cl_recs[chain].c_blkno = bg->bg_blkno;
     ocfs2_journal_dirty(handle, fe_bh);
 
 out:
     if (status < 0)
         mlog_errno(status);
     return status;
 
 out_rollback_bg:
     bg->bg_next_group = cpu_to_le64(bg_ptr);
 out_rollback_prev_bg:
     prev_bg->bg_next_group = cpu_to_le64(prev_bg_ptr);
     goto out;
 }
 
 static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg,
                              u32 wanted)
 {
     return le16_to_cpu(bg->bg_free_bits_count) > wanted;
 }
 
 /* return 0 on success, -ENOSPC to keep searching and any other < 0
  * value on error. */
 static int ocfs2_cluster_group_search(struct inode *inode,
                       struct buffer_head *group_bh,
                       u32 bits_wanted, u32 min_bits,
                       u64 max_block,
                       struct ocfs2_suballoc_result *res)
 {
     int search = -ENOSPC;
     int ret;
     u64 blkoff;
     struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *) group_bh->b_data;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     unsigned int max_bits, gd_cluster_off;
 
     BUG_ON(!ocfs2_is_cluster_bitmap(inode));
 
     if (gd->bg_free_bits_count) {
         max_bits = le16_to_cpu(gd->bg_bits);
 
         /* Tail groups in cluster bitmaps which aren't cpg
          * aligned are prone to partial extension by a failed
          * fs resize. If the file system resize never got to
          * update the dinode cluster count, then we don't want
          * to trust any clusters past it, regardless of what
          * the group descriptor says. */
         gd_cluster_off = ocfs2_blocks_to_clusters(inode->i_sb,
                               le64_to_cpu(gd->bg_blkno));
         if ((gd_cluster_off + max_bits) >
             OCFS2_I(inode)->ip_clusters) {
             max_bits = OCFS2_I(inode)->ip_clusters - gd_cluster_off;
             trace_ocfs2_cluster_group_search_wrong_max_bits(
                 (unsigned long long)le64_to_cpu(gd->bg_blkno),
                 le16_to_cpu(gd->bg_bits),
                 OCFS2_I(inode)->ip_clusters, max_bits);
         }
 
         ret = ocfs2_block_group_find_clear_bits(osb,
                             group_bh, bits_wanted,
                             max_bits, res);
         if (ret)
             return ret;
 
         if (max_block) {
             blkoff = ocfs2_clusters_to_blocks(inode->i_sb,
                               gd_cluster_off +
                               res->sr_bit_offset +
                               res->sr_bits);
             trace_ocfs2_cluster_group_search_max_block(
                 (unsigned long long)blkoff,
                 (unsigned long long)max_block);
             if (blkoff > max_block)
                 return -ENOSPC;
         }
 
         /* ocfs2_block_group_find_clear_bits() might
          * return success, but we still want to return
          * -ENOSPC unless it found the minimum number
          * of bits. */
         if (min_bits <= res->sr_bits)
             search = 0; /* success */
         else if (res->sr_bits) {
             /*
              * Don't show bits which we'll be returning
              * for allocation to the local alloc bitmap.
              */
             ocfs2_local_alloc_seen_free_bits(osb, res->sr_bits);
         }
     }
 
     return search;
 }
 
 static int ocfs2_block_group_search(struct inode *inode,
                     struct buffer_head *group_bh,
                     u32 bits_wanted, u32 min_bits,
                     u64 max_block,
                     struct ocfs2_suballoc_result *res)
 {
     int ret = -ENOSPC;
     u64 blkoff;
     struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) group_bh->b_data;
 
     BUG_ON(min_bits != 1);
     BUG_ON(ocfs2_is_cluster_bitmap(inode));
 
     if (bg->bg_free_bits_count) {
         ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
                             group_bh, bits_wanted,
                             le16_to_cpu(bg->bg_bits),
                             res);
         if (!ret && max_block) {
             blkoff = le64_to_cpu(bg->bg_blkno) +
                 res->sr_bit_offset + res->sr_bits;
             trace_ocfs2_block_group_search_max_block(
                 (unsigned long long)blkoff,
                 (unsigned long long)max_block);
             if (blkoff > max_block)
                 ret = -ENOSPC;
         }
     }
 
     return ret;
 }
 
 int ocfs2_alloc_dinode_update_counts(struct inode *inode,
                        handle_t *handle,
                        struct buffer_head *di_bh,
                        u32 num_bits,
                        u16 chain)
 {
     int ret;
     u32 tmp_used;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *) di_bh->b_data;
     struct ocfs2_chain_list *cl = (struct ocfs2_chain_list *) &di->id2.i_chain;
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
     tmp_used = le32_to_cpu(di->id1.bitmap1.i_used);
     di->id1.bitmap1.i_used = cpu_to_le32(num_bits + tmp_used);
     le32_add_cpu(&cl->cl_recs[chain].c_free, -num_bits);
     ocfs2_journal_dirty(handle, di_bh);
 
 out:
     return ret;
 }
 
 void ocfs2_rollback_alloc_dinode_counts(struct inode *inode,
                        struct buffer_head *di_bh,
                        u32 num_bits,
                        u16 chain)
 {
     u32 tmp_used;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *) di_bh->b_data;
     struct ocfs2_chain_list *cl;
 
     cl = (struct ocfs2_chain_list *)&di->id2.i_chain;
     tmp_used = le32_to_cpu(di->id1.bitmap1.i_used);
     di->id1.bitmap1.i_used = cpu_to_le32(tmp_used - num_bits);
     le32_add_cpu(&cl->cl_recs[chain].c_free, num_bits);
 }
 
 static int ocfs2_bg_discontig_fix_by_rec(struct ocfs2_suballoc_result *res,
                      struct ocfs2_extent_rec *rec,
                      struct ocfs2_chain_list *cl)
 {
     unsigned int bpc = le16_to_cpu(cl->cl_bpc);
     unsigned int bitoff = le32_to_cpu(rec->e_cpos) * bpc;
     unsigned int bitcount = le16_to_cpu(rec->e_leaf_clusters) * bpc;
 
     if (res->sr_bit_offset < bitoff)
         return 0;
     if (res->sr_bit_offset >= (bitoff + bitcount))
         return 0;
     res->sr_blkno = le64_to_cpu(rec->e_blkno) +
         (res->sr_bit_offset - bitoff);
     if ((res->sr_bit_offset + res->sr_bits) > (bitoff + bitcount))
         res->sr_bits = (bitoff + bitcount) - res->sr_bit_offset;
     return 1;
 }
 
 static void ocfs2_bg_discontig_fix_result(struct ocfs2_alloc_context *ac,
                       struct ocfs2_group_desc *bg,
                       struct ocfs2_suballoc_result *res)
 {
     int i;
     u64 bg_blkno = res->sr_bg_blkno;  /* Save off */
     struct ocfs2_extent_rec *rec;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)ac->ac_bh->b_data;
     struct ocfs2_chain_list *cl = &di->id2.i_chain;
 
     if (ocfs2_is_cluster_bitmap(ac->ac_inode)) {
         res->sr_blkno = 0;
         return;
     }
 
     res->sr_blkno = res->sr_bg_blkno + res->sr_bit_offset;
     res->sr_bg_blkno = 0;  /* Clear it for contig block groups */
     if (!ocfs2_supports_discontig_bg(OCFS2_SB(ac->ac_inode->i_sb)) ||
         !bg->bg_list.l_next_free_rec)
         return;
 
     for (i = 0; i < le16_to_cpu(bg->bg_list.l_next_free_rec); i++) {
         rec = &bg->bg_list.l_recs[i];
         if (ocfs2_bg_discontig_fix_by_rec(res, rec, cl)) {
             res->sr_bg_blkno = bg_blkno;  /* Restore */
             break;
         }
     }
 }
 
 static int ocfs2_search_one_group(struct ocfs2_alloc_context *ac,
                   handle_t *handle,
                   u32 bits_wanted,
                   u32 min_bits,
                   struct ocfs2_suballoc_result *res,
                   u16 *bits_left)
 {
     int ret;
     struct buffer_head *group_bh = NULL;
     struct ocfs2_group_desc *gd;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)ac->ac_bh->b_data;
     struct inode *alloc_inode = ac->ac_inode;
 
     ret = ocfs2_read_group_descriptor(alloc_inode, di,
                       res->sr_bg_blkno, &group_bh);
     if (ret < 0) {
         mlog_errno(ret);
         return ret;
     }
 
     gd = (struct ocfs2_group_desc *) group_bh->b_data;
     ret = ac->ac_group_search(alloc_inode, group_bh, bits_wanted, min_bits,
                   ac->ac_max_block, res);
     if (ret < 0) {
         if (ret != -ENOSPC)
             mlog_errno(ret);
         goto out;
     }
 
     if (!ret)
         ocfs2_bg_discontig_fix_result(ac, gd, res);
 
     /*
      * sr_bg_blkno might have been changed by
      * ocfs2_bg_discontig_fix_result
      */
     res->sr_bg_stable_blkno = group_bh->b_blocknr;
 
     if (ac->ac_find_loc_only)
         goto out_loc_only;
 
     ret = ocfs2_alloc_dinode_update_counts(alloc_inode, handle, ac->ac_bh,
                            res->sr_bits,
                            le16_to_cpu(gd->bg_chain));
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_block_group_set_bits(handle, alloc_inode, gd, group_bh,
                      res->sr_bit_offset, res->sr_bits);
     if (ret < 0) {
         ocfs2_rollback_alloc_dinode_counts(alloc_inode, ac->ac_bh,
                            res->sr_bits,
                            le16_to_cpu(gd->bg_chain));
         mlog_errno(ret);
     }
 
 out_loc_only:
     *bits_left = le16_to_cpu(gd->bg_free_bits_count);
 
 out:
     brelse(group_bh);
 
     return ret;
 }
 
 static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
                   handle_t *handle,
                   u32 bits_wanted,
                   u32 min_bits,
                   struct ocfs2_suballoc_result *res,
                   u16 *bits_left)
 {
     int status;
     u16 chain;
     u64 next_group;
     struct inode *alloc_inode = ac->ac_inode;
     struct buffer_head *group_bh = NULL;
     struct buffer_head *prev_group_bh = NULL;
     struct ocfs2_dinode *fe = (struct ocfs2_dinode *) ac->ac_bh->b_data;
     struct ocfs2_chain_list *cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;
     struct ocfs2_group_desc *bg;
 
     chain = ac->ac_chain;
     trace_ocfs2_search_chain_begin(
         (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno,
         bits_wanted, chain);
 
     status = ocfs2_read_group_descriptor(alloc_inode, fe,
                          le64_to_cpu(cl->cl_recs[chain].c_blkno),
                          &group_bh);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
     bg = (struct ocfs2_group_desc *) group_bh->b_data;
 
     status = -ENOSPC;
     /* for now, the chain search is a bit simplistic. We just use
      * the 1st group with any empty bits. */
     while ((status = ac->ac_group_search(alloc_inode, group_bh,
                          bits_wanted, min_bits,
                          ac->ac_max_block,
                          res)) == -ENOSPC) {
         if (!bg->bg_next_group)
             break;
 
         brelse(prev_group_bh);
         prev_group_bh = NULL;
 
         next_group = le64_to_cpu(bg->bg_next_group);
         prev_group_bh = group_bh;
         group_bh = NULL;
         status = ocfs2_read_group_descriptor(alloc_inode, fe,
                              next_group, &group_bh);
         if (status < 0) {
             mlog_errno(status);
             goto bail;
         }
         bg = (struct ocfs2_group_desc *) group_bh->b_data;
     }
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
 
     trace_ocfs2_search_chain_succ(
         (unsigned long long)le64_to_cpu(bg->bg_blkno), res->sr_bits);
 
     res->sr_bg_blkno = le64_to_cpu(bg->bg_blkno);
 
     BUG_ON(res->sr_bits == 0);
     if (!status)
         ocfs2_bg_discontig_fix_result(ac, bg, res);
 
     /*
      * sr_bg_blkno might have been changed by
      * ocfs2_bg_discontig_fix_result
      */
     res->sr_bg_stable_blkno = group_bh->b_blocknr;
 
     /*
      * Keep track of previous block descriptor read. When
      * we find a target, if we have read more than X
      * number of descriptors, and the target is reasonably
      * empty, relink him to top of his chain.
      *
      * We've read 0 extra blocks and only send one more to
      * the transaction, yet the next guy to search has a
      * much easier time.
      *
      * Do this *after* figuring out how many bits we're taking out
      * of our target group.
      */
     if (!ac->ac_disable_chain_relink &&
         (prev_group_bh) &&
         (ocfs2_block_group_reasonably_empty(bg, res->sr_bits))) {
         status = ocfs2_relink_block_group(handle, alloc_inode,
                           ac->ac_bh, group_bh,
                           prev_group_bh, chain);
         if (status < 0) {
             mlog_errno(status);
             goto bail;
         }
     }
 
     if (ac->ac_find_loc_only)
         goto out_loc_only;
 
     status = ocfs2_alloc_dinode_update_counts(alloc_inode, handle,
                           ac->ac_bh, res->sr_bits,
                           chain);
     if (status) {
         mlog_errno(status);
         goto bail;
     }
 
     status = ocfs2_block_group_set_bits(handle,
                         alloc_inode,
                         bg,
                         group_bh,
                         res->sr_bit_offset,
                         res->sr_bits);
     if (status < 0) {
         ocfs2_rollback_alloc_dinode_counts(alloc_inode,
                     ac->ac_bh, res->sr_bits, chain);
         mlog_errno(status);
         goto bail;
     }
 
     trace_ocfs2_search_chain_end(
             (unsigned long long)le64_to_cpu(fe->i_blkno),
             res->sr_bits);
 
 out_loc_only:
     *bits_left = le16_to_cpu(bg->bg_free_bits_count);
 bail:
     brelse(group_bh);
     brelse(prev_group_bh);
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 /* will give out up to bits_wanted contiguous bits. */
 static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
                      handle_t *handle,
                      u32 bits_wanted,
                      u32 min_bits,
                      struct ocfs2_suballoc_result *res)
 {
     int status;
     u16 victim, i;
     u16 bits_left = 0;
     u64 hint = ac->ac_last_group;
     struct ocfs2_chain_list *cl;
     struct ocfs2_dinode *fe;
 
     BUG_ON(ac->ac_bits_given >= ac->ac_bits_wanted);
     BUG_ON(bits_wanted > (ac->ac_bits_wanted - ac->ac_bits_given));
     BUG_ON(!ac->ac_bh);
 
     fe = (struct ocfs2_dinode *) ac->ac_bh->b_data;
 
     /* The bh was validated by the inode read during
      * ocfs2_reserve_suballoc_bits().  Any corruption is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
 
     if (le32_to_cpu(fe->id1.bitmap1.i_used) >=
         le32_to_cpu(fe->id1.bitmap1.i_total)) {
         status = ocfs2_error(ac->ac_inode->i_sb,
                      "Chain allocator dinode %llu has %u used bits but only %u total\n",
                      (unsigned long long)le64_to_cpu(fe->i_blkno),
                      le32_to_cpu(fe->id1.bitmap1.i_used),
                      le32_to_cpu(fe->id1.bitmap1.i_total));
         goto bail;
     }
 
     res->sr_bg_blkno = hint;
     if (res->sr_bg_blkno) {
         /* Attempt to short-circuit the usual search mechanism
          * by jumping straight to the most recently used
          * allocation group. This helps us maintain some
          * contiguousness across allocations. */
         status = ocfs2_search_one_group(ac, handle, bits_wanted,
                         min_bits, res, &bits_left);
         if (!status)
             goto set_hint;
         if (status < 0 && status != -ENOSPC) {
             mlog_errno(status);
             goto bail;
         }
     }
 
     cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;
 
     victim = ocfs2_find_victim_chain(cl);
     ac->ac_chain = victim;
 
     status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
                     res, &bits_left);
     if (!status) {
         if (ocfs2_is_cluster_bitmap(ac->ac_inode))
             hint = res->sr_bg_blkno;
         else
             hint = ocfs2_group_from_res(res);
         goto set_hint;
     }
     if (status < 0 && status != -ENOSPC) {
         mlog_errno(status);
         goto bail;
     }
 
     trace_ocfs2_claim_suballoc_bits(victim);
 
     /* If we didn't pick a good victim, then just default to
      * searching each chain in order. Don't allow chain relinking
      * because we only calculate enough journal credits for one
      * relink per alloc. */
     ac->ac_disable_chain_relink = 1;
     for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i ++) {
         if (i == victim)
             continue;
         if (!cl->cl_recs[i].c_free)
             continue;
 
         ac->ac_chain = i;
         status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
                         res, &bits_left);
         if (!status) {
             hint = ocfs2_group_from_res(res);
             break;
         }
         if (status < 0 && status != -ENOSPC) {
             mlog_errno(status);
             goto bail;
         }
     }
 
 set_hint:
     if (status != -ENOSPC) {
         /* If the next search of this group is not likely to
          * yield a suitable extent, then we reset the last
          * group hint so as to not waste a disk read */
         if (bits_left < min_bits)
             ac->ac_last_group = 0;
         else
             ac->ac_last_group = hint;
     }
 
 bail:
     if (status)
         mlog_errno(status);
     return status;
 }
 
 int ocfs2_claim_metadata(handle_t *handle,
              struct ocfs2_alloc_context *ac,
              u32 bits_wanted,
              u64 *suballoc_loc,
              u16 *suballoc_bit_start,
              unsigned int *num_bits,
              u64 *blkno_start)
 {
     int status;
     struct ocfs2_suballoc_result res = { .sr_blkno = 0, };
 
     BUG_ON(!ac);
     BUG_ON(ac->ac_bits_wanted < (ac->ac_bits_given + bits_wanted));
     BUG_ON(ac->ac_which != OCFS2_AC_USE_META);
 
     status = ocfs2_claim_suballoc_bits(ac,
                        handle,
                        bits_wanted,
                        1,
                        &res);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
     atomic_inc(&OCFS2_SB(ac->ac_inode->i_sb)->alloc_stats.bg_allocs);
 
     *suballoc_loc = res.sr_bg_blkno;
     *suballoc_bit_start = res.sr_bit_offset;
     *blkno_start = res.sr_blkno;
     ac->ac_bits_given += res.sr_bits;
     *num_bits = res.sr_bits;
     status = 0;
 bail:
     if (status)
         mlog_errno(status);
     return status;
 }
 
 static void ocfs2_init_inode_ac_group(struct inode *dir,
                       struct buffer_head *parent_di_bh,
                       struct ocfs2_alloc_context *ac)
 {
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)parent_di_bh->b_data;
     /*
      * Try to allocate inodes from some specific group.
      *
      * If the parent dir has recorded the last group used in allocation,
      * cool, use it. Otherwise if we try to allocate new inode from the
      * same slot the parent dir belongs to, use the same chunk.
      *
      * We are very careful here to avoid the mistake of setting
      * ac_last_group to a group descriptor from a different (unlocked) slot.
      */
     if (OCFS2_I(dir)->ip_last_used_group &&
         OCFS2_I(dir)->ip_last_used_slot == ac->ac_alloc_slot)
         ac->ac_last_group = OCFS2_I(dir)->ip_last_used_group;
     else if (le16_to_cpu(di->i_suballoc_slot) == ac->ac_alloc_slot) {
         if (di->i_suballoc_loc)
             ac->ac_last_group = le64_to_cpu(di->i_suballoc_loc);
         else
             ac->ac_last_group = ocfs2_which_suballoc_group(
                     le64_to_cpu(di->i_blkno),
                     le16_to_cpu(di->i_suballoc_bit));
     }
 }
 
 static inline void ocfs2_save_inode_ac_group(struct inode *dir,
                          struct ocfs2_alloc_context *ac)
 {
     OCFS2_I(dir)->ip_last_used_group = ac->ac_last_group;
     OCFS2_I(dir)->ip_last_used_slot = ac->ac_alloc_slot;
 }
 
 int ocfs2_find_new_inode_loc(struct inode *dir,
                  struct buffer_head *parent_fe_bh,
                  struct ocfs2_alloc_context *ac,
                  u64 *fe_blkno)
 {
     int ret;
     handle_t *handle = NULL;
     struct ocfs2_suballoc_result *res;
 
     BUG_ON(!ac);
     BUG_ON(ac->ac_bits_given != 0);
     BUG_ON(ac->ac_bits_wanted != 1);
     BUG_ON(ac->ac_which != OCFS2_AC_USE_INODE);
 
     res = kzalloc(sizeof(*res), GFP_NOFS);
     if (res == NULL) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     ocfs2_init_inode_ac_group(dir, parent_fe_bh, ac);
 
     /*
      * The handle started here is for chain relink. Alternatively,
      * we could just disable relink for these calls.
      */
     handle = ocfs2_start_trans(OCFS2_SB(dir->i_sb), OCFS2_SUBALLOC_ALLOC);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         handle = NULL;
         mlog_errno(ret);
         goto out;
     }
 
     /*
      * This will instruct ocfs2_claim_suballoc_bits and
      * ocfs2_search_one_group to search but save actual allocation
      * for later.
      */
     ac->ac_find_loc_only = 1;
 
     ret = ocfs2_claim_suballoc_bits(ac, handle, 1, 1, res);
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
     ac->ac_find_loc_priv = res;
     *fe_blkno = res->sr_blkno;
     ocfs2_update_inode_fsync_trans(handle, dir, 0);
 out:
     if (handle)
         ocfs2_commit_trans(OCFS2_SB(dir->i_sb), handle);
 
     if (ret)
         kfree(res);
 
     return ret;
 }
 
 int ocfs2_claim_new_inode_at_loc(handle_t *handle,
                  struct inode *dir,
                  struct ocfs2_alloc_context *ac,
                  u64 *suballoc_loc,
                  u16 *suballoc_bit,
                  u64 di_blkno)
 {
     int ret;
     u16 chain;
     struct ocfs2_suballoc_result *res = ac->ac_find_loc_priv;
     struct buffer_head *bg_bh = NULL;
     struct ocfs2_group_desc *bg;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *) ac->ac_bh->b_data;
 
     /*
      * Since di_blkno is being passed back in, we check for any
      * inconsistencies which may have happened between
      * calls. These are code bugs as di_blkno is not expected to
      * change once returned from ocfs2_find_new_inode_loc()
      */
     BUG_ON(res->sr_blkno != di_blkno);
 
     ret = ocfs2_read_group_descriptor(ac->ac_inode, di,
                       res->sr_bg_stable_blkno, &bg_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     bg = (struct ocfs2_group_desc *) bg_bh->b_data;
     chain = le16_to_cpu(bg->bg_chain);
 
     ret = ocfs2_alloc_dinode_update_counts(ac->ac_inode, handle,
                            ac->ac_bh, res->sr_bits,
                            chain);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_block_group_set_bits(handle,
                      ac->ac_inode,
                      bg,
                      bg_bh,
                      res->sr_bit_offset,
                      res->sr_bits);
     if (ret < 0) {
         ocfs2_rollback_alloc_dinode_counts(ac->ac_inode,
                            ac->ac_bh, res->sr_bits, chain);
         mlog_errno(ret);
         goto out;
     }
 
     trace_ocfs2_claim_new_inode_at_loc((unsigned long long)di_blkno,
                        res->sr_bits);
 
     atomic_inc(&OCFS2_SB(ac->ac_inode->i_sb)->alloc_stats.bg_allocs);
 
     BUG_ON(res->sr_bits != 1);
 
     *suballoc_loc = res->sr_bg_blkno;
     *suballoc_bit = res->sr_bit_offset;
     ac->ac_bits_given++;
     ocfs2_save_inode_ac_group(dir, ac);
 
 out:
     brelse(bg_bh);
 
     return ret;
 }
 
 int ocfs2_claim_new_inode(handle_t *handle,
               struct inode *dir,
               struct buffer_head *parent_fe_bh,
               struct ocfs2_alloc_context *ac,
               u64 *suballoc_loc,
               u16 *suballoc_bit,
               u64 *fe_blkno)
 {
     int status;
     struct ocfs2_suballoc_result res;
 
     BUG_ON(!ac);
     BUG_ON(ac->ac_bits_given != 0);
     BUG_ON(ac->ac_bits_wanted != 1);
     BUG_ON(ac->ac_which != OCFS2_AC_USE_INODE);
 
     ocfs2_init_inode_ac_group(dir, parent_fe_bh, ac);
 
     status = ocfs2_claim_suballoc_bits(ac,
                        handle,
                        1,
                        1,
                        &res);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
     atomic_inc(&OCFS2_SB(ac->ac_inode->i_sb)->alloc_stats.bg_allocs);
 
     BUG_ON(res.sr_bits != 1);
 
     *suballoc_loc = res.sr_bg_blkno;
     *suballoc_bit = res.sr_bit_offset;
     *fe_blkno = res.sr_blkno;
     ac->ac_bits_given++;
     ocfs2_save_inode_ac_group(dir, ac);
     status = 0;
 bail:
     if (status)
         mlog_errno(status);
     return status;
 }
 
 /* translate a group desc. blkno and it's bitmap offset into
  * disk cluster offset. */
 static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
                            u64 bg_blkno,
                            u16 bg_bit_off)
 {
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     u32 cluster = 0;
 
     BUG_ON(!ocfs2_is_cluster_bitmap(inode));
 
     if (bg_blkno != osb->first_cluster_group_blkno)
         cluster = ocfs2_blocks_to_clusters(inode->i_sb, bg_blkno);
     cluster += (u32) bg_bit_off;
     return cluster;
 }
 
 /* given a cluster offset, calculate which block group it belongs to
  * and return that block offset. */
 u64 ocfs2_which_cluster_group(struct inode *inode, u32 cluster)
 {
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     u32 group_no;
 
     BUG_ON(!ocfs2_is_cluster_bitmap(inode));
 
     group_no = cluster / osb->bitmap_cpg;
     if (!group_no)
         return osb->first_cluster_group_blkno;
     return ocfs2_clusters_to_blocks(inode->i_sb,
                     group_no * osb->bitmap_cpg);
 }
 
 /* given the block number of a cluster start, calculate which cluster
  * group and descriptor bitmap offset that corresponds to. */
 static inline void ocfs2_block_to_cluster_group(struct inode *inode,
                         u64 data_blkno,
                         u64 *bg_blkno,
                         u16 *bg_bit_off)
 {
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     u32 data_cluster = ocfs2_blocks_to_clusters(osb->sb, data_blkno);
 
     BUG_ON(!ocfs2_is_cluster_bitmap(inode));
 
     *bg_blkno = ocfs2_which_cluster_group(inode,
                           data_cluster);
 
     if (*bg_blkno == osb->first_cluster_group_blkno)
         *bg_bit_off = (u16) data_cluster;
     else
         *bg_bit_off = (u16) ocfs2_blocks_to_clusters(osb->sb,
                                  data_blkno - *bg_blkno);
 }
 
 /*
  * min_bits - minimum contiguous chunk from this total allocation we
  * can handle. set to what we asked for originally for a full
  * contig. allocation, set to '1' to indicate we can deal with extents
  * of any size.
  */
 int __ocfs2_claim_clusters(handle_t *handle,
                struct ocfs2_alloc_context *ac,
                u32 min_clusters,
                u32 max_clusters,
                u32 *cluster_start,
                u32 *num_clusters)
 {
     int status;
     unsigned int bits_wanted = max_clusters;
     struct ocfs2_suballoc_result res = { .sr_blkno = 0, };
     struct ocfs2_super *osb = OCFS2_SB(ac->ac_inode->i_sb);
 
     BUG_ON(ac->ac_bits_given >= ac->ac_bits_wanted);
 
     BUG_ON(ac->ac_which != OCFS2_AC_USE_LOCAL
            && ac->ac_which != OCFS2_AC_USE_MAIN);
 
     if (ac->ac_which == OCFS2_AC_USE_LOCAL) {
         WARN_ON(min_clusters > 1);
 
         status = ocfs2_claim_local_alloc_bits(osb,
                               handle,
                               ac,
                               bits_wanted,
                               cluster_start,
                               num_clusters);
         if (!status)
             atomic_inc(&osb->alloc_stats.local_data);
     } else {
         if (min_clusters > (osb->bitmap_cpg - 1)) {
             /* The only paths asking for contiguousness
              * should know about this already. */
             mlog(ML_ERROR, "minimum allocation requested %u exceeds "
                  "group bitmap size %u!\n", min_clusters,
                  osb->bitmap_cpg);
             status = -ENOSPC;
             goto bail;
         }
         /* clamp the current request down to a realistic size. */
         if (bits_wanted > (osb->bitmap_cpg - 1))
             bits_wanted = osb->bitmap_cpg - 1;
 
         status = ocfs2_claim_suballoc_bits(ac,
                            handle,
                            bits_wanted,
                            min_clusters,
                            &res);
         if (!status) {
             BUG_ON(res.sr_blkno); /* cluster alloc can't set */
             *cluster_start =
                 ocfs2_desc_bitmap_to_cluster_off(ac->ac_inode,
                                  res.sr_bg_blkno,
                                  res.sr_bit_offset);
             atomic_inc(&osb->alloc_stats.bitmap_data);
             *num_clusters = res.sr_bits;
         }
     }
     if (status < 0) {
         if (status != -ENOSPC)
             mlog_errno(status);
         goto bail;
     }
 
     ac->ac_bits_given += *num_clusters;
 
 bail:
     if (status)
         mlog_errno(status);
     return status;
 }
 
 int ocfs2_claim_clusters(handle_t *handle,
              struct ocfs2_alloc_context *ac,
              u32 min_clusters,
              u32 *cluster_start,
              u32 *num_clusters)
 {
     unsigned int bits_wanted = ac->ac_bits_wanted - ac->ac_bits_given;
 
     return __ocfs2_claim_clusters(handle, ac, min_clusters,
                       bits_wanted, cluster_start, num_clusters);
 }
 
 static int ocfs2_block_group_clear_bits(handle_t *handle,
                     struct inode *alloc_inode,
                     struct ocfs2_group_desc *bg,
                     struct buffer_head *group_bh,
                     unsigned int bit_off,
                     unsigned int num_bits,
                     void (*undo_fn)(unsigned int bit,
                             unsigned long *bmap))
 {
     int status;
     unsigned int tmp;
     struct ocfs2_group_desc *undo_bg = NULL;
     struct journal_head *jh;
 
     /* The caller got this descriptor from
      * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
 
     trace_ocfs2_block_group_clear_bits(bit_off, num_bits);
 
     BUG_ON(undo_fn && !ocfs2_is_cluster_bitmap(alloc_inode));
     status = ocfs2_journal_access_gd(handle, INODE_CACHE(alloc_inode),
                      group_bh,
                      undo_fn ?
                      OCFS2_JOURNAL_ACCESS_UNDO :
                      OCFS2_JOURNAL_ACCESS_WRITE);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     jh = bh2jh(group_bh);
     if (undo_fn) {
         spin_lock(&jh->b_state_lock);
         undo_bg = (struct ocfs2_group_desc *) jh->b_committed_data;
         BUG_ON(!undo_bg);
     }
 
     tmp = num_bits;
     while(tmp--) {
         ocfs2_clear_bit((bit_off + tmp),
                 (unsigned long *) bg->bg_bitmap);
         if (undo_fn)
             undo_fn(bit_off + tmp,
                 (unsigned long *) undo_bg->bg_bitmap);
     }
     le16_add_cpu(&bg->bg_free_bits_count, num_bits);
     if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
         if (undo_fn)
             spin_unlock(&jh->b_state_lock);
         return ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit count %u but claims %u are freed. num_bits %d\n",
                    (unsigned long long)le64_to_cpu(bg->bg_blkno),
                    le16_to_cpu(bg->bg_bits),
                    le16_to_cpu(bg->bg_free_bits_count),
                    num_bits);
     }
 
     if (undo_fn)
         spin_unlock(&jh->b_state_lock);
 
     ocfs2_journal_dirty(handle, group_bh);
 bail:
     return status;
 }
 
 /*
  * expects the suballoc inode to already be locked.
  */
 static int _ocfs2_free_suballoc_bits(handle_t *handle,
                      struct inode *alloc_inode,
                      struct buffer_head *alloc_bh,
                      unsigned int start_bit,
                      u64 bg_blkno,
                      unsigned int count,
                      void (*undo_fn)(unsigned int bit,
                              unsigned long *bitmap))
 {
     int status = 0;
     u32 tmp_used;
     struct ocfs2_dinode *fe = (struct ocfs2_dinode *) alloc_bh->b_data;
     struct ocfs2_chain_list *cl = &fe->id2.i_chain;
     struct buffer_head *group_bh = NULL;
     struct ocfs2_group_desc *group;
 
     /* The alloc_bh comes from ocfs2_free_dinode() or
      * ocfs2_free_clusters().  The callers have all locked the
      * allocator and gotten alloc_bh from the lock call.  This
      * validates the dinode buffer.  Any corruption that has happened
      * is a code bug. */
     BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
     BUG_ON((count + start_bit) > ocfs2_bits_per_group(cl));
 
     trace_ocfs2_free_suballoc_bits(
         (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno,
         (unsigned long long)bg_blkno,
         start_bit, count);
 
     status = ocfs2_read_group_descriptor(alloc_inode, fe, bg_blkno,
                          &group_bh);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
     group = (struct ocfs2_group_desc *) group_bh->b_data;
 
     BUG_ON((count + start_bit) > le16_to_cpu(group->bg_bits));
 
     status = ocfs2_block_group_clear_bits(handle, alloc_inode,
                           group, group_bh,
                           start_bit, count, undo_fn);
     if (status < 0) {
         mlog_errno(status);
         goto bail;
     }
 
     status = ocfs2_journal_access_di(handle, INODE_CACHE(alloc_inode),
                      alloc_bh, OCFS2_JOURNAL_ACCESS_WRITE);
     if (status < 0) {
         mlog_errno(status);
         ocfs2_block_group_set_bits(handle, alloc_inode, group, group_bh,
                 start_bit, count);
         goto bail;
     }
 
     le32_add_cpu(&cl->cl_recs[le16_to_cpu(group->bg_chain)].c_free,
              count);
     tmp_used = le32_to_cpu(fe->id1.bitmap1.i_used);
     fe->id1.bitmap1.i_used = cpu_to_le32(tmp_used - count);
     ocfs2_journal_dirty(handle, alloc_bh);
 
 bail:
     brelse(group_bh);
     return status;
 }
 
 int ocfs2_free_suballoc_bits(handle_t *handle,
                  struct inode *alloc_inode,
                  struct buffer_head *alloc_bh,
                  unsigned int start_bit,
                  u64 bg_blkno,
                  unsigned int count)
 {
     return _ocfs2_free_suballoc_bits(handle, alloc_inode, alloc_bh,
                      start_bit, bg_blkno, count, NULL);
 }
 
 int ocfs2_free_dinode(handle_t *handle,
               struct inode *inode_alloc_inode,
               struct buffer_head *inode_alloc_bh,
               struct ocfs2_dinode *di)
 {
     u64 blk = le64_to_cpu(di->i_blkno);
     u16 bit = le16_to_cpu(di->i_suballoc_bit);
     u64 bg_blkno = ocfs2_which_suballoc_group(blk, bit);
 
     if (di->i_suballoc_loc)
         bg_blkno = le64_to_cpu(di->i_suballoc_loc);
     return ocfs2_free_suballoc_bits(handle, inode_alloc_inode,
                     inode_alloc_bh, bit, bg_blkno, 1);
 }
 
 static int _ocfs2_free_clusters(handle_t *handle,
                 struct inode *bitmap_inode,
                 struct buffer_head *bitmap_bh,
                 u64 start_blk,
                 unsigned int num_clusters,
                 void (*undo_fn)(unsigned int bit,
                         unsigned long *bitmap))
 {
     int status;
     u16 bg_start_bit;
     u64 bg_blkno;
 
     /* You can't ever have a contiguous set of clusters
      * bigger than a block group bitmap so we never have to worry
      * about looping on them.
      * This is expensive. We can safely remove once this stuff has
      * gotten tested really well. */
     BUG_ON(start_blk != ocfs2_clusters_to_blocks(bitmap_inode->i_sb,
                 ocfs2_blocks_to_clusters(bitmap_inode->i_sb,
                              start_blk)));
 
 
     ocfs2_block_to_cluster_group(bitmap_inode, start_blk, &bg_blkno,
                      &bg_start_bit);
 
     trace_ocfs2_free_clusters((unsigned long long)bg_blkno,
             (unsigned long long)start_blk,
             bg_start_bit, num_clusters);
 
     status = _ocfs2_free_suballoc_bits(handle, bitmap_inode, bitmap_bh,
                        bg_start_bit, bg_blkno,
                        num_clusters, undo_fn);
     if (status < 0) {
         mlog_errno(status);
         goto out;
     }
 
     ocfs2_local_alloc_seen_free_bits(OCFS2_SB(bitmap_inode->i_sb),
                      num_clusters);
 
 out:
     return status;
 }
 
 int ocfs2_free_clusters(handle_t *handle,
             struct inode *bitmap_inode,
             struct buffer_head *bitmap_bh,
             u64 start_blk,
             unsigned int num_clusters)
 {
     return _ocfs2_free_clusters(handle, bitmap_inode, bitmap_bh,
                     start_blk, num_clusters,
                     _ocfs2_set_bit);
 }
 
 /*
  * Give never-used clusters back to the global bitmap.  We don't need
  * to protect these bits in the undo buffer.
  */
 int ocfs2_release_clusters(handle_t *handle,
                struct inode *bitmap_inode,
                struct buffer_head *bitmap_bh,
                u64 start_blk,
                unsigned int num_clusters)
 {
     return _ocfs2_free_clusters(handle, bitmap_inode, bitmap_bh,
                     start_blk, num_clusters,
                     _ocfs2_clear_bit);
 }
 
 /*
  * For a given allocation, determine which allocators will need to be
  * accessed, and lock them, reserving the appropriate number of bits.
  *
  * Sparse file systems call this from ocfs2_write_begin_nolock()
  * and ocfs2_allocate_unwritten_extents().
  *
  * File systems which don't support holes call this from
  * ocfs2_extend_allocation().
  */
 int ocfs2_lock_allocators(struct inode *inode,
               struct ocfs2_extent_tree *et,
               u32 clusters_to_add, u32 extents_to_split,
               struct ocfs2_alloc_context **data_ac,
               struct ocfs2_alloc_context **meta_ac)
 {
     int ret = 0, num_free_extents;
     unsigned int max_recs_needed = clusters_to_add + 2 * extents_to_split;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
     *meta_ac = NULL;
     if (data_ac)
         *data_ac = NULL;
 
     BUG_ON(clusters_to_add != 0 && data_ac == NULL);
 
     num_free_extents = ocfs2_num_free_extents(et);
     if (num_free_extents < 0) {
         ret = num_free_extents;
         mlog_errno(ret);
         goto out;
     }
 
     /*
      * Sparse allocation file systems need to be more conservative
      * with reserving room for expansion - the actual allocation
      * happens while we've got a journal handle open so re-taking
      * a cluster lock (because we ran out of room for another
      * extent) will violate ordering rules.
      *
      * Most of the time we'll only be seeing this 1 cluster at a time
      * anyway.
      *
      * Always lock for any unwritten extents - we might want to
      * add blocks during a split.
      */
     if (!num_free_extents ||
         (ocfs2_sparse_alloc(osb) && num_free_extents < max_recs_needed)) {
         ret = ocfs2_reserve_new_metadata(osb, et->et_root_el, meta_ac);
         if (ret < 0) {
             if (ret != -ENOSPC)
                 mlog_errno(ret);
             goto out;
         }
     }
 
     if (clusters_to_add == 0)
         goto out;
 
     ret = ocfs2_reserve_clusters(osb, clusters_to_add, data_ac);
     if (ret < 0) {
         if (ret != -ENOSPC)
             mlog_errno(ret);
         goto out;
     }
 
 out:
     if (ret) {
         if (*meta_ac) {
             ocfs2_free_alloc_context(*meta_ac);
             *meta_ac = NULL;
         }
 
         /*
          * We cannot have an error and a non null *data_ac.
          */
     }
 
     return ret;
 }
 
 /*
  * Read the inode specified by blkno to get suballoc_slot and
  * suballoc_bit.
  */
 static int ocfs2_get_suballoc_slot_bit(struct ocfs2_super *osb, u64 blkno,
                        u16 *suballoc_slot, u64 *group_blkno,
                        u16 *suballoc_bit)
 {
     int status;
     struct buffer_head *inode_bh = NULL;
     struct ocfs2_dinode *inode_fe;
 
     trace_ocfs2_get_suballoc_slot_bit((unsigned long long)blkno);
 
     /* dirty read disk */
     status = ocfs2_read_blocks_sync(osb, blkno, 1, &inode_bh);
     if (status < 0) {
         mlog(ML_ERROR, "read block %llu failed %d\n",
              (unsigned long long)blkno, status);
         goto bail;
     }
 
     inode_fe = (struct ocfs2_dinode *) inode_bh->b_data;
     if (!OCFS2_IS_VALID_DINODE(inode_fe)) {
         mlog(ML_ERROR, "invalid inode %llu requested\n",
              (unsigned long long)blkno);
         status = -EINVAL;
         goto bail;
     }
 
     if (le16_to_cpu(inode_fe->i_suballoc_slot) != (u16)OCFS2_INVALID_SLOT &&
         (u32)le16_to_cpu(inode_fe->i_suballoc_slot) > osb->max_slots - 1) {
         mlog(ML_ERROR, "inode %llu has invalid suballoc slot %u\n",
              (unsigned long long)blkno,
              (u32)le16_to_cpu(inode_fe->i_suballoc_slot));
         status = -EINVAL;
         goto bail;
     }
 
     if (suballoc_slot)
         *suballoc_slot = le16_to_cpu(inode_fe->i_suballoc_slot);
     if (suballoc_bit)
         *suballoc_bit = le16_to_cpu(inode_fe->i_suballoc_bit);
     if (group_blkno)
         *group_blkno = le64_to_cpu(inode_fe->i_suballoc_loc);
 
 bail:
     brelse(inode_bh);
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 /*
  * test whether bit is SET in allocator bitmap or not.  on success, 0
  * is returned and *res is 1 for SET; 0 otherwise.  when fails, errno
  * is returned and *res is meaningless.  Call this after you have
  * cluster locked against suballoc, or you may get a result based on
  * non-up2date contents
  */
 static int ocfs2_test_suballoc_bit(struct ocfs2_super *osb,
                    struct inode *suballoc,
                    struct buffer_head *alloc_bh,
                    u64 group_blkno, u64 blkno,
                    u16 bit, int *res)
 {
     struct ocfs2_dinode *alloc_di;
     struct ocfs2_group_desc *group;
     struct buffer_head *group_bh = NULL;
     u64 bg_blkno;
     int status;
 
     trace_ocfs2_test_suballoc_bit((unsigned long long)blkno,
                       (unsigned int)bit);
 
     alloc_di = (struct ocfs2_dinode *)alloc_bh->b_data;
     if ((bit + 1) > ocfs2_bits_per_group(&alloc_di->id2.i_chain)) {
         mlog(ML_ERROR, "suballoc bit %u out of range of %u\n",
              (unsigned int)bit,
              ocfs2_bits_per_group(&alloc_di->id2.i_chain));
         status = -EINVAL;
         goto bail;
     }
 
     bg_blkno = group_blkno ? group_blkno :
            ocfs2_which_suballoc_group(blkno, bit);
     status = ocfs2_read_group_descriptor(suballoc, alloc_di, bg_blkno,
                          &group_bh);
     if (status < 0) {
         mlog(ML_ERROR, "read group %llu failed %d\n",
              (unsigned long long)bg_blkno, status);
         goto bail;
     }
 
     group = (struct ocfs2_group_desc *) group_bh->b_data;
     *res = ocfs2_test_bit(bit, (unsigned long *)group->bg_bitmap);
 
 bail:
     brelse(group_bh);
 
     if (status)
         mlog_errno(status);
     return status;
 }
 
 /*
  * Test if the bit representing this inode (blkno) is set in the
  * suballocator.
  *
  * On success, 0 is returned and *res is 1 for SET; 0 otherwise.
  *
  * In the event of failure, a negative value is returned and *res is
  * meaningless.
  *
  * Callers must make sure to hold nfs_sync_lock to prevent
  * ocfs2_delete_inode() on another node from accessing the same
  * suballocator concurrently.
  */
 int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res)
 {
     int status;
     u64 group_blkno = 0;
     u16 suballoc_bit = 0, suballoc_slot = 0;
     struct inode *inode_alloc_inode;
     struct buffer_head *alloc_bh = NULL;
 
     trace_ocfs2_test_inode_bit((unsigned long long)blkno);
 
     status = ocfs2_get_suballoc_slot_bit(osb, blkno, &suballoc_slot,
                          &group_blkno, &suballoc_bit);
     if (status < 0) {
         mlog(ML_ERROR, "get alloc slot and bit failed %d\n", status);
         goto bail;
     }
 
     if (suballoc_slot == (u16)OCFS2_INVALID_SLOT)
         inode_alloc_inode = ocfs2_get_system_file_inode(osb,
             GLOBAL_INODE_ALLOC_SYSTEM_INODE, suballoc_slot);
     else
         inode_alloc_inode = ocfs2_get_system_file_inode(osb,
             INODE_ALLOC_SYSTEM_INODE, suballoc_slot);
     if (!inode_alloc_inode) {
         /* the error code could be inaccurate, but we are not able to
          * get the correct one. */
         status = -EINVAL;
         mlog(ML_ERROR, "unable to get alloc inode in slot %u\n",
              (u32)suballoc_slot);
         goto bail;
     }
 
     inode_lock(inode_alloc_inode);
     status = ocfs2_inode_lock(inode_alloc_inode, &alloc_bh, 0);
     if (status < 0) {
         inode_unlock(inode_alloc_inode);
         iput(inode_alloc_inode);
         mlog(ML_ERROR, "lock on alloc inode on slot %u failed %d\n",
              (u32)suballoc_slot, status);
         goto bail;
     }
 
     status = ocfs2_test_suballoc_bit(osb, inode_alloc_inode, alloc_bh,
                      group_blkno, blkno, suballoc_bit, res);
     if (status < 0)
         mlog(ML_ERROR, "test suballoc bit failed %d\n", status);
 
     ocfs2_inode_unlock(inode_alloc_inode, 0);
     inode_unlock(inode_alloc_inode);
 
     iput(inode_alloc_inode);
     brelse(alloc_bh);
 bail:
     if (status)
         mlog_errno(status);
     return status;
 }