Logo Search packages:      
Sourcecode: linux version File versions  Download package

suballoc.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * suballoc.c
 *
 * metadata alloc and free
 * Inspired by ext3 block groups.
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>

#define MLOG_MASK_PREFIX ML_DISK_ALLOC
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.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 "buffer_head_io.h"

static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg);
static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe);
static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
static int ocfs2_block_group_fill(handle_t *handle,
                          struct inode *alloc_inode,
                          struct buffer_head *bg_bh,
                          u64 group_blkno,
                          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);

static int ocfs2_cluster_group_search(struct inode *inode,
                              struct buffer_head *group_bh,
                              u32 bits_wanted, u32 min_bits,
                              u16 *bit_off, u16 *bits_found);
static int ocfs2_block_group_search(struct inode *inode,
                            struct buffer_head *group_bh,
                            u32 bits_wanted, u32 min_bits,
                            u16 *bit_off, u16 *bits_found);
static int ocfs2_claim_suballoc_bits(struct ocfs2_super *osb,
                             struct ocfs2_alloc_context *ac,
                             handle_t *handle,
                             u32 bits_wanted,
                             u32 min_bits,
                             u16 *bit_off,
                             unsigned int *num_bits,
                             u64 *bg_blkno);
static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
                               int nr);
static inline 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);
static inline 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);

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 u64 ocfs2_which_cluster_group(struct inode *inode,
                                  u32 cluster);
static inline void ocfs2_block_to_cluster_group(struct inode *inode,
                                    u64 data_blkno,
                                    u64 *bg_blkno,
                                    u16 *bg_bit_off);

void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
{
      struct inode *inode = ac->ac_inode;

      if (inode) {
            if (ac->ac_which != OCFS2_AC_USE_LOCAL)
                  ocfs2_meta_unlock(inode, 1);

            mutex_unlock(&inode->i_mutex);

            iput(inode);
      }
      if (ac->ac_bh)
            brelse(ac->ac_bh);
      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);
}

/* somewhat more expensive than our other checks, so use sparingly. */
static int ocfs2_check_group_descriptor(struct super_block *sb,
                              struct ocfs2_dinode *di,
                              struct ocfs2_group_desc *gd)
{
      unsigned int max_bits;

      if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(sb, gd);
            return -EIO;
      }

      if (di->i_blkno != gd->bg_parent_dinode) {
            ocfs2_error(sb, "Group descriptor # %llu has bad parent "
                      "pointer (%llu, expected %llu)",
                      (unsigned long long)le64_to_cpu(gd->bg_blkno),
                      (unsigned long long)le64_to_cpu(gd->bg_parent_dinode),
                      (unsigned long long)le64_to_cpu(di->i_blkno));
            return -EIO;
      }

      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) {
            ocfs2_error(sb, "Group descriptor # %llu has bit count of %u",
                      (unsigned long long)le64_to_cpu(gd->bg_blkno),
                      le16_to_cpu(gd->bg_bits));
            return -EIO;
      }

      if (le16_to_cpu(gd->bg_chain) >=
          le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) {
            ocfs2_error(sb, "Group descriptor # %llu has bad chain %u",
                      (unsigned long long)le64_to_cpu(gd->bg_blkno),
                      le16_to_cpu(gd->bg_chain));
            return -EIO;
      }

      if (le16_to_cpu(gd->bg_free_bits_count) > le16_to_cpu(gd->bg_bits)) {
            ocfs2_error(sb, "Group descriptor # %llu has bit count %u but "
                      "claims that %u are free",
                      (unsigned long long)le64_to_cpu(gd->bg_blkno),
                      le16_to_cpu(gd->bg_bits),
                      le16_to_cpu(gd->bg_free_bits_count));
            return -EIO;
      }

      if (le16_to_cpu(gd->bg_bits) > (8 * le16_to_cpu(gd->bg_size))) {
            ocfs2_error(sb, "Group descriptor # %llu has bit count %u but "
                      "max bitmap bits of %u",
                      (unsigned long long)le64_to_cpu(gd->bg_blkno),
                      le16_to_cpu(gd->bg_bits),
                      8 * le16_to_cpu(gd->bg_size));
            return -EIO;
      }

      return 0;
}

static int ocfs2_block_group_fill(handle_t *handle,
                          struct inode *alloc_inode,
                          struct buffer_head *bg_bh,
                          u64 group_blkno,
                          u16 my_chain,
                          struct ocfs2_chain_list *cl)
{
      int status = 0;
      struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
      struct super_block * sb = alloc_inode->i_sb;

      mlog_entry_void();

      if (((unsigned long long) bg_bh->b_blocknr) != group_blkno) {
            ocfs2_error(alloc_inode->i_sb, "group block (%llu) != "
                      "b_blocknr (%llu)",
                      (unsigned long long)group_blkno,
                      (unsigned long long) bg_bh->b_blocknr);
            status = -EIO;
            goto bail;
      }

      status = ocfs2_journal_access(handle,
                              alloc_inode,
                              bg_bh,
                              OCFS2_JOURNAL_ACCESS_CREATE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      memset(bg, 0, sb->s_blocksize);
      strcpy(bg->bg_signature, OCFS2_GROUP_DESC_SIGNATURE);
      bg->bg_generation = cpu_to_le32(OCFS2_SB(sb)->fs_generation);
      bg->bg_size = cpu_to_le16(ocfs2_group_bitmap_size(sb));
      bg->bg_bits = cpu_to_le16(ocfs2_bits_per_group(cl));
      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);
      /* 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);

      status = ocfs2_journal_dirty(handle, bg_bh);
      if (status < 0)
            mlog_errno(status);

      /* 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:
      mlog_exit(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;
}

/*
 * 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)
{
      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;
      u32 bit_off, num_bits;
      u16 alloc_rec;
      u64 bg_blkno;
      struct buffer_head *bg_bh = NULL;
      struct ocfs2_group_desc *bg;

      BUG_ON(ocfs2_is_cluster_bitmap(alloc_inode));

      mlog_entry_void();

      cl = &fe->id2.i_chain;
      status = ocfs2_reserve_clusters(osb,
                              le16_to_cpu(cl->cl_cpg),
                              &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;
      }

      status = ocfs2_claim_clusters(osb,
                              handle,
                              ac,
                              le16_to_cpu(cl->cl_cpg),
                              &bit_off,
                              &num_bits);
      if (status < 0) {
            if (status != -ENOSPC)
                  mlog_errno(status);
            goto bail;
      }

      alloc_rec = ocfs2_find_smallest_chain(cl);

      /* setup the group */
      bg_blkno = ocfs2_clusters_to_blocks(osb->sb, bit_off);
      mlog(0, "new descriptor, record %u, at block %llu\n",
           alloc_rec, (unsigned long long)bg_blkno);

      bg_bh = sb_getblk(osb->sb, bg_blkno);
      if (!bg_bh) {
            status = -EIO;
            mlog_errno(status);
            goto bail;
      }
      ocfs2_set_new_buffer_uptodate(alloc_inode, bg_bh);

      status = ocfs2_block_group_fill(handle,
                              alloc_inode,
                              bg_bh,
                              bg_blkno,
                              alloc_rec,
                              cl);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      bg = (struct ocfs2_group_desc *) bg_bh->b_data;

      status = ocfs2_journal_access(handle, alloc_inode,
                              bh, OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      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  = cpu_to_le64(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));

      status = ocfs2_journal_dirty(handle, bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      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);

      status = 0;
bail:
      if (handle)
            ocfs2_commit_trans(osb, handle);

      if (ac)
            ocfs2_free_alloc_context(ac);

      if (bg_bh)
            brelse(bg_bh);

      mlog_exit(status);
      return status;
}

static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
                               struct ocfs2_alloc_context *ac,
                               int type,
                               u32 slot)
{
      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;

      mlog_entry_void();

      alloc_inode = ocfs2_get_system_file_inode(osb, type, slot);
      if (!alloc_inode) {
            mlog_errno(-EINVAL);
            return -EINVAL;
      }

      mutex_lock(&alloc_inode->i_mutex);

      status = ocfs2_meta_lock(alloc_inode, &bh, 1);
      if (status < 0) {
            mutex_unlock(&alloc_inode->i_mutex);
            iput(alloc_inode);

            mlog_errno(status);
            return status;
      }

      ac->ac_inode = alloc_inode;

      fe = (struct ocfs2_dinode *) bh->b_data;
      if (!OCFS2_IS_VALID_DINODE(fe)) {
            OCFS2_RO_ON_INVALID_DINODE(alloc_inode->i_sb, fe);
            status = -EIO;
            goto bail;
      }
      if (!(fe->i_flags & cpu_to_le32(OCFS2_CHAIN_FL))) {
            ocfs2_error(alloc_inode->i_sb, "Invalid chain allocator %llu",
                      (unsigned long long)le64_to_cpu(fe->i_blkno));
            status = -EIO;
            goto bail;
      }

      free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
            le32_to_cpu(fe->id1.bitmap1.i_used);

      if (bits_wanted > free_bits) {
            /* cluster bitmap never grows */
            if (ocfs2_is_cluster_bitmap(alloc_inode)) {
                  mlog(0, "Disk Full: wanted=%u, free_bits=%u\n",
                       bits_wanted, free_bits);
                  status = -ENOSPC;
                  goto bail;
            }

            status = ocfs2_block_group_alloc(osb, alloc_inode, bh);
            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:
      if (bh)
            brelse(bh);

      mlog_exit(status);
      return status;
}

int ocfs2_reserve_new_metadata(struct ocfs2_super *osb,
                         struct ocfs2_dinode *fe,
                         struct ocfs2_alloc_context **ac)
{
      int status;
      u32 slot;

      *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
      if (!(*ac)) {
            status = -ENOMEM;
            mlog_errno(status);
            goto bail;
      }

      (*ac)->ac_bits_wanted = ocfs2_extend_meta_needed(fe);
      (*ac)->ac_which = OCFS2_AC_USE_META;
      slot = osb->slot_num;
      (*ac)->ac_group_search = ocfs2_block_group_search;

      status = ocfs2_reserve_suballoc_bits(osb, (*ac),
                                   EXTENT_ALLOC_SYSTEM_INODE, slot);
      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;
      }

      mlog_exit(status);
      return status;
}

int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
                      struct ocfs2_alloc_context **ac)
{
      int status;

      *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
      if (!(*ac)) {
            status = -ENOMEM;
            mlog_errno(status);
            goto bail;
      }

      (*ac)->ac_bits_wanted = 1;
      (*ac)->ac_which = OCFS2_AC_USE_INODE;

      (*ac)->ac_group_search = ocfs2_block_group_search;

      status = ocfs2_reserve_suballoc_bits(osb, *ac,
                                   INODE_ALLOC_SYSTEM_INODE,
                                   osb->slot_num);
      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;
      }

      mlog_exit(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);
      if (status < 0 && status != -ENOSPC) {
            mlog_errno(status);
            goto bail;
      }

bail:
      return status;
}

/* Callers don't need to care which bitmap (local alloc or main) to
 * use so we figure it out for them, but unfortunately this clutters
 * things a bit. */
int ocfs2_reserve_clusters(struct ocfs2_super *osb,
                     u32 bits_wanted,
                     struct ocfs2_alloc_context **ac)
{
      int status;

      mlog_entry_void();

      *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
      if (!(*ac)) {
            status = -ENOMEM;
            mlog_errno(status);
            goto bail;
      }

      (*ac)->ac_bits_wanted = bits_wanted;

      status = -ENOSPC;
      if (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;
            } else if (status == -ENOSPC) {
                  /* reserve_local_bits will return enospc with
                   * the local alloc inode still locked, so we
                   * can change this safely here. */
                  mlog(0, "Disabling local alloc\n");
                  /* We set to OCFS2_LA_DISABLED so that umount
                   * can clean up what's left of the local
                   * allocation */
                  osb->local_alloc_state = OCFS2_LA_DISABLED;
            }
      }

      if (status == -ENOSPC) {
            status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);
            if (status < 0) {
                  if (status != -ENOSPC)
                        mlog_errno(status);
                  goto bail;
            }
      }

      status = 0;
bail:
      if ((status < 0) && *ac) {
            ocfs2_free_alloc_context(*ac);
            *ac = NULL;
      }

      mlog_exit(status);
      return status;
}

/*
 * 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 seperate 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;

      if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
            return 0;
      if (!buffer_jbd(bg_bh) || !bh2jh(bg_bh)->b_committed_data)
            return 1;

      bg = (struct ocfs2_group_desc *) bh2jh(bg_bh)->b_committed_data;
      return !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
}

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,
                                   u16 *bit_off,
                                   u16 *bits_found)
{
      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;

      if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(osb->sb, bg);
            return -EIO;
      }

      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;
            }
      }

      /* XXX: I think the first clause is equivalent to the second
       *    - jlbec */
      if (found == bits_wanted) {
            *bit_off = start - found;
            *bits_found = found;
      } else if (best_size) {
            *bit_off = best_offset;
            *bits_found = best_size;
      } else {
            status = -ENOSPC;
            /* No error log here -- see the comment above
             * ocfs2_test_bg_bit_allocatable */
      }

      return status;
}

static inline 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;

      mlog_entry_void();

      if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
            status = -EIO;
            goto bail;
      }
      BUG_ON(le16_to_cpu(bg->bg_free_bits_count) < num_bits);

      mlog(0, "block_group_set_bits: off = %u, num = %u\n", bit_off,
           num_bits);

      if (ocfs2_is_cluster_bitmap(alloc_inode))
            journal_type = OCFS2_JOURNAL_ACCESS_UNDO;

      status = ocfs2_journal_access(handle,
                              alloc_inode,
                              group_bh,
                              journal_type);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      le16_add_cpu(&bg->bg_free_bits_count, -num_bits);

      while(num_bits--)
            ocfs2_set_bit(bit_off++, bitmap);

      status = ocfs2_journal_dirty(handle,
                             group_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

bail:
      mlog_exit(status);
      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 fe_ptr, 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;

      if (!OCFS2_IS_VALID_DINODE(fe)) {
            OCFS2_RO_ON_INVALID_DINODE(alloc_inode->i_sb, fe);
            status = -EIO;
            goto out;
      }
      if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
            status = -EIO;
            goto out;
      }
      if (!OCFS2_IS_VALID_GROUP_DESC(prev_bg)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, prev_bg);
            status = -EIO;
            goto out;
      }

      mlog(0, "Suballoc %llu, chain %u, move group %llu to top, prev = %llu\n",
           (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));

      fe_ptr = le64_to_cpu(fe->id2.i_chain.cl_recs[chain].c_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(handle, alloc_inode, prev_bg_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto out_rollback;
      }

      prev_bg->bg_next_group = bg->bg_next_group;

      status = ocfs2_journal_dirty(handle, prev_bg_bh);
      if (status < 0) {
            mlog_errno(status);
            goto out_rollback;
      }

      status = ocfs2_journal_access(handle, alloc_inode, bg_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto out_rollback;
      }

      bg->bg_next_group = fe->id2.i_chain.cl_recs[chain].c_blkno;

      status = ocfs2_journal_dirty(handle, bg_bh);
      if (status < 0) {
            mlog_errno(status);
            goto out_rollback;
      }

      status = ocfs2_journal_access(handle, alloc_inode, fe_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto out_rollback;
      }

      fe->id2.i_chain.cl_recs[chain].c_blkno = bg->bg_blkno;

      status = ocfs2_journal_dirty(handle, fe_bh);
      if (status < 0) {
            mlog_errno(status);
            goto out_rollback;
      }

      status = 0;
out_rollback:
      if (status < 0) {
            fe->id2.i_chain.cl_recs[chain].c_blkno = cpu_to_le64(fe_ptr);
            bg->bg_next_group = cpu_to_le64(bg_ptr);
            prev_bg->bg_next_group = cpu_to_le64(prev_bg_ptr);
      }
out:
      mlog_exit(status);
      return status;
}

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,
                              u16 *bit_off, u16 *bits_found)
{
      int search = -ENOSPC;
      int ret;
      struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *) group_bh->b_data;
      u16 tmp_off, tmp_found;
      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 extention 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;
                  mlog(0, "Desc %llu, bg_bits %u, clusters %u, use %u\n",
                       (unsigned long long)le64_to_cpu(gd->bg_blkno),
                       le16_to_cpu(gd->bg_bits),
                       OCFS2_I(inode)->ip_clusters, max_bits);
            }

            ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
                                          group_bh, bits_wanted,
                                          max_bits,
                                          &tmp_off, &tmp_found);
            if (ret)
                  return ret;

            /* 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 <= tmp_found) {
                  *bit_off = tmp_off;
                  *bits_found = tmp_found;
                  search = 0; /* success */
            }
      }

      return search;
}

static int ocfs2_block_group_search(struct inode *inode,
                            struct buffer_head *group_bh,
                            u32 bits_wanted, u32 min_bits,
                            u16 *bit_off, u16 *bits_found)
{
      int ret = -ENOSPC;
      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),
                                          bit_off, bits_found);

      return ret;
}

static 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(handle, 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);

      ret = ocfs2_journal_dirty(handle, di_bh);
      if (ret < 0)
            mlog_errno(ret);

out:
      return ret;
}

static int ocfs2_search_one_group(struct ocfs2_alloc_context *ac,
                          handle_t *handle,
                          u32 bits_wanted,
                          u32 min_bits,
                          u16 *bit_off,
                          unsigned int *num_bits,
                          u64 gd_blkno,
                          u16 *bits_left)
{
      int ret;
      u16 found;
      struct buffer_head *group_bh = NULL;
      struct ocfs2_group_desc *gd;
      struct inode *alloc_inode = ac->ac_inode;

      ret = ocfs2_read_block(OCFS2_SB(alloc_inode->i_sb), gd_blkno,
                         &group_bh, OCFS2_BH_CACHED, alloc_inode);
      if (ret < 0) {
            mlog_errno(ret);
            return ret;
      }

      gd = (struct ocfs2_group_desc *) group_bh->b_data;
      if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, gd);
            ret = -EIO;
            goto out;
      }

      ret = ac->ac_group_search(alloc_inode, group_bh, bits_wanted, min_bits,
                          bit_off, &found);
      if (ret < 0) {
            if (ret != -ENOSPC)
                  mlog_errno(ret);
            goto out;
      }

      *num_bits = found;

      ret = ocfs2_alloc_dinode_update_counts(alloc_inode, handle, ac->ac_bh,
                                     *num_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,
                               *bit_off, *num_bits);
      if (ret < 0)
            mlog_errno(ret);

      *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,
                        u16 *bit_off,
                        unsigned int *num_bits,
                        u64 *bg_blkno,
                        u16 *bits_left)
{
      int status;
      u16 chain, tmp_bits;
      u32 tmp_used;
      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;
      mlog(0, "trying to alloc %u bits from chain %u, inode %llu\n",
           bits_wanted, chain,
           (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno);

      status = ocfs2_read_block(OCFS2_SB(alloc_inode->i_sb),
                          le64_to_cpu(cl->cl_recs[chain].c_blkno),
                          &group_bh, OCFS2_BH_CACHED, alloc_inode);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }
      bg = (struct ocfs2_group_desc *) group_bh->b_data;
      status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, bg);
      if (status) {
            mlog_errno(status);
            goto bail;
      }

      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, bit_off,
                                   &tmp_bits)) == -ENOSPC) {
            if (!bg->bg_next_group)
                  break;

            if (prev_group_bh) {
                  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_block(OCFS2_SB(alloc_inode->i_sb),
                                next_group, &group_bh,
                                OCFS2_BH_CACHED, alloc_inode);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
            bg = (struct ocfs2_group_desc *) group_bh->b_data;
            status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, bg);
            if (status) {
                  mlog_errno(status);
                  goto bail;
            }
      }
      if (status < 0) {
            if (status != -ENOSPC)
                  mlog_errno(status);
            goto bail;
      }

      mlog(0, "alloc succeeds: we give %u bits from block group %llu\n",
           tmp_bits, (unsigned long long)le64_to_cpu(bg->bg_blkno));

      *num_bits = tmp_bits;

      BUG_ON(*num_bits == 0);

      /*
       * 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_allow_chain_relink &&
          (prev_group_bh) &&
          (ocfs2_block_group_reasonably_empty(bg, *num_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;
            }
      }

      /* Ok, claim our bits now: set the info on dinode, chainlist
       * and then the group */
      status = ocfs2_journal_access(handle,
                              alloc_inode,
                              ac->ac_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      tmp_used = le32_to_cpu(fe->id1.bitmap1.i_used);
      fe->id1.bitmap1.i_used = cpu_to_le32(*num_bits + tmp_used);
      le32_add_cpu(&cl->cl_recs[chain].c_free, -(*num_bits));

      status = ocfs2_journal_dirty(handle,
                             ac->ac_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_block_group_set_bits(handle,
                                  alloc_inode,
                                  bg,
                                  group_bh,
                                  *bit_off,
                                  *num_bits);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      mlog(0, "Allocated %u bits from suballocator %llu\n", *num_bits,
           (unsigned long long)le64_to_cpu(fe->i_blkno));

      *bg_blkno = le64_to_cpu(bg->bg_blkno);
      *bits_left = le16_to_cpu(bg->bg_free_bits_count);
bail:
      if (group_bh)
            brelse(group_bh);
      if (prev_group_bh)
            brelse(prev_group_bh);

      mlog_exit(status);
      return status;
}

/* will give out up to bits_wanted contiguous bits. */
static int ocfs2_claim_suballoc_bits(struct ocfs2_super *osb,
                             struct ocfs2_alloc_context *ac,
                             handle_t *handle,
                             u32 bits_wanted,
                             u32 min_bits,
                             u16 *bit_off,
                             unsigned int *num_bits,
                             u64 *bg_blkno)
{
      int status;
      u16 victim, i;
      u16 bits_left = 0;
      u64 hint_blkno = ac->ac_last_group;
      struct ocfs2_chain_list *cl;
      struct ocfs2_dinode *fe;

      mlog_entry_void();

      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;
      if (!OCFS2_IS_VALID_DINODE(fe)) {
            OCFS2_RO_ON_INVALID_DINODE(osb->sb, fe);
            status = -EIO;
            goto bail;
      }
      if (le32_to_cpu(fe->id1.bitmap1.i_used) >=
          le32_to_cpu(fe->id1.bitmap1.i_total)) {
            ocfs2_error(osb->sb, "Chain allocator dinode %llu has %u used "
                      "bits but only %u total.",
                      (unsigned long long)le64_to_cpu(fe->i_blkno),
                      le32_to_cpu(fe->id1.bitmap1.i_used),
                      le32_to_cpu(fe->id1.bitmap1.i_total));
            status = -EIO;
            goto bail;
      }

      if (hint_blkno) {
            /* Attempt to short-circuit the usual search mechanism
             * by jumping straight to the most recently used
             * allocation group. This helps us mantain some
             * contiguousness across allocations. */
            status = ocfs2_search_one_group(ac, handle, bits_wanted,
                                    min_bits, bit_off, num_bits,
                                    hint_blkno, &bits_left);
            if (!status) {
                  /* Be careful to update *bg_blkno here as the
                   * caller is expecting it to be filled in, and
                   * ocfs2_search_one_group() won't do that for
                   * us. */
                  *bg_blkno = hint_blkno;
                  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;
      ac->ac_allow_chain_relink = 1;

      status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits, bit_off,
                            num_bits, bg_blkno, &bits_left);
      if (!status)
            goto set_hint;
      if (status < 0 && status != -ENOSPC) {
            mlog_errno(status);
            goto bail;
      }

      mlog(0, "Search of victim chain %u came up with nothing, "
           "trying all chains now.\n", 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_allow_chain_relink = 0;
      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,
                                  bit_off, num_bits, bg_blkno,
                                  &bits_left);
            if (!status)
                  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 = *bg_blkno;
      }

bail:
      mlog_exit(status);
      return status;
}

int ocfs2_claim_metadata(struct ocfs2_super *osb,
                   handle_t *handle,
                   struct ocfs2_alloc_context *ac,
                   u32 bits_wanted,
                   u16 *suballoc_bit_start,
                   unsigned int *num_bits,
                   u64 *blkno_start)
{
      int status;
      u64 bg_blkno;

      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(osb,
                                 ac,
                                 handle,
                                 bits_wanted,
                                 1,
                                 suballoc_bit_start,
                                 num_bits,
                                 &bg_blkno);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }
      atomic_inc(&osb->alloc_stats.bg_allocs);

      *blkno_start = bg_blkno + (u64) *suballoc_bit_start;
      ac->ac_bits_given += (*num_bits);
      status = 0;
bail:
      mlog_exit(status);
      return status;
}

int ocfs2_claim_new_inode(struct ocfs2_super *osb,
                    handle_t *handle,
                    struct ocfs2_alloc_context *ac,
                    u16 *suballoc_bit,
                    u64 *fe_blkno)
{
      int status;
      unsigned int num_bits;
      u64 bg_blkno;

      mlog_entry_void();

      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);

      status = ocfs2_claim_suballoc_bits(osb,
                                 ac,
                                 handle,
                                 1,
                                 1,
                                 suballoc_bit,
                                 &num_bits,
                                 &bg_blkno);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }
      atomic_inc(&osb->alloc_stats.bg_allocs);

      BUG_ON(num_bits != 1);

      *fe_blkno = bg_blkno + (u64) (*suballoc_bit);
      ac->ac_bits_given++;
      status = 0;
bail:
      mlog_exit(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. */
static inline 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(struct ocfs2_super *osb,
                     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;
      u64 bg_blkno = 0;
      u16 bg_bit_off;

      mlog_entry_void();

      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) {
            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 exceeds "
                               "group bitmap size!");
                  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(osb,
                                       ac,
                                       handle,
                                       bits_wanted,
                                       min_clusters,
                                       &bg_bit_off,
                                       num_clusters,
                                       &bg_blkno);
            if (!status) {
                  *cluster_start =
                        ocfs2_desc_bitmap_to_cluster_off(ac->ac_inode,
                                                 bg_blkno,
                                                 bg_bit_off);
                  atomic_inc(&osb->alloc_stats.bitmap_data);
            }
      }
      if (status < 0) {
            if (status != -ENOSPC)
                  mlog_errno(status);
            goto bail;
      }

      ac->ac_bits_given += *num_clusters;

bail:
      mlog_exit(status);
      return status;
}

int ocfs2_claim_clusters(struct ocfs2_super *osb,
                   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(osb, handle, ac, min_clusters,
                              bits_wanted, cluster_start, num_clusters);
}

static inline 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)
{
      int status;
      unsigned int tmp;
      int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
      struct ocfs2_group_desc *undo_bg = NULL;

      mlog_entry_void();

      if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
            OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
            status = -EIO;
            goto bail;
      }

      mlog(0, "off = %u, num = %u\n", bit_off, num_bits);

      if (ocfs2_is_cluster_bitmap(alloc_inode))
            journal_type = OCFS2_JOURNAL_ACCESS_UNDO;

      status = ocfs2_journal_access(handle, alloc_inode, group_bh,
                              journal_type);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      if (ocfs2_is_cluster_bitmap(alloc_inode))
            undo_bg = (struct ocfs2_group_desc *) bh2jh(group_bh)->b_committed_data;

      tmp = num_bits;
      while(tmp--) {
            ocfs2_clear_bit((bit_off + tmp),
                        (unsigned long *) bg->bg_bitmap);
            if (ocfs2_is_cluster_bitmap(alloc_inode))
                  ocfs2_set_bit(bit_off + tmp,
                              (unsigned long *) undo_bg->bg_bitmap);
      }
      le16_add_cpu(&bg->bg_free_bits_count, num_bits);

      status = ocfs2_journal_dirty(handle, group_bh);
      if (status < 0)
            mlog_errno(status);
bail:
      return status;
}

/*
 * expects the suballoc inode to already be locked.
 */
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)
{
      int status = 0;
      u32 tmp_used;
      struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
      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;

      mlog_entry_void();

      if (!OCFS2_IS_VALID_DINODE(fe)) {
            OCFS2_RO_ON_INVALID_DINODE(alloc_inode->i_sb, fe);
            status = -EIO;
            goto bail;
      }
      BUG_ON((count + start_bit) > ocfs2_bits_per_group(cl));

      mlog(0, "%llu: freeing %u bits from group %llu, starting at %u\n",
           (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno, count,
           (unsigned long long)bg_blkno, start_bit);

      status = ocfs2_read_block(osb, bg_blkno, &group_bh, OCFS2_BH_CACHED,
                          alloc_inode);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      group = (struct ocfs2_group_desc *) group_bh->b_data;
      status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, group);
      if (status) {
            mlog_errno(status);
            goto bail;
      }
      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);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_journal_access(handle, alloc_inode, alloc_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            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);

      status = ocfs2_journal_dirty(handle, alloc_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

bail:
      if (group_bh)
            brelse(group_bh);

      mlog_exit(status);
      return status;
}

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);

      return ocfs2_free_suballoc_bits(handle, inode_alloc_inode,
                              inode_alloc_bh, bit, bg_blkno, 1);
}

int ocfs2_free_clusters(handle_t *handle,
                   struct inode *bitmap_inode,
                   struct buffer_head *bitmap_bh,
                   u64 start_blk,
                   unsigned int num_clusters)
{
      int status;
      u16 bg_start_bit;
      u64 bg_blkno;
      struct ocfs2_dinode *fe;

      /* You can't ever have a contiguous set of clusters
       * bigger than a block group bitmap so we never have to worry
       * about looping on them. */

      mlog_entry_void();

      /* This is expensive. We can safely remove once this stuff has
       * gotten tested really well. */
      BUG_ON(start_blk != ocfs2_clusters_to_blocks(bitmap_inode->i_sb, ocfs2_blocks_to_clusters(bitmap_inode->i_sb, start_blk)));

      fe = (struct ocfs2_dinode *) bitmap_bh->b_data;

      ocfs2_block_to_cluster_group(bitmap_inode, start_blk, &bg_blkno,
                             &bg_start_bit);

      mlog(0, "want to free %u clusters starting at block %llu\n",
           num_clusters, (unsigned long long)start_blk);
      mlog(0, "bg_blkno = %llu, bg_start_bit = %u\n",
           (unsigned long long)bg_blkno, bg_start_bit);

      status = ocfs2_free_suballoc_bits(handle, bitmap_inode, bitmap_bh,
                                bg_start_bit, bg_blkno,
                                num_clusters);
      if (status < 0)
            mlog_errno(status);

      mlog_exit(status);
      return status;
}

static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg)
{
      printk("Block Group:\n");
      printk("bg_signature:       %s\n", bg->bg_signature);
      printk("bg_size:            %u\n", bg->bg_size);
      printk("bg_bits:            %u\n", bg->bg_bits);
      printk("bg_free_bits_count: %u\n", bg->bg_free_bits_count);
      printk("bg_chain:           %u\n", bg->bg_chain);
      printk("bg_generation:      %u\n", le32_to_cpu(bg->bg_generation));
      printk("bg_next_group:      %llu\n",
             (unsigned long long)bg->bg_next_group);
      printk("bg_parent_dinode:   %llu\n",
             (unsigned long long)bg->bg_parent_dinode);
      printk("bg_blkno:           %llu\n",
             (unsigned long long)bg->bg_blkno);
}

static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe)
{
      int i;

      printk("Suballoc Inode %llu:\n", (unsigned long long)fe->i_blkno);
      printk("i_signature:                  %s\n", fe->i_signature);
      printk("i_size:                       %llu\n",
             (unsigned long long)fe->i_size);
      printk("i_clusters:                   %u\n", fe->i_clusters);
      printk("i_generation:                 %u\n",
             le32_to_cpu(fe->i_generation));
      printk("id1.bitmap1.i_used:           %u\n",
             le32_to_cpu(fe->id1.bitmap1.i_used));
      printk("id1.bitmap1.i_total:          %u\n",
             le32_to_cpu(fe->id1.bitmap1.i_total));
      printk("id2.i_chain.cl_cpg:           %u\n", fe->id2.i_chain.cl_cpg);
      printk("id2.i_chain.cl_bpc:           %u\n", fe->id2.i_chain.cl_bpc);
      printk("id2.i_chain.cl_count:         %u\n", fe->id2.i_chain.cl_count);
      printk("id2.i_chain.cl_next_free_rec: %u\n",
             fe->id2.i_chain.cl_next_free_rec);
      for(i = 0; i < fe->id2.i_chain.cl_next_free_rec; i++) {
            printk("fe->id2.i_chain.cl_recs[%d].c_free:  %u\n", i,
                   fe->id2.i_chain.cl_recs[i].c_free);
            printk("fe->id2.i_chain.cl_recs[%d].c_total: %u\n", i,
                   fe->id2.i_chain.cl_recs[i].c_total);
            printk("fe->id2.i_chain.cl_recs[%d].c_blkno: %llu\n", i,
                   (unsigned long long)fe->id2.i_chain.cl_recs[i].c_blkno);
      }
}

Generated by  Doxygen 1.6.0   Back to index