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Atomic bit operations in mballoc.
[fs/lustre-release.git] / ldiskfs / kernel_patches / patches / ext3-mballoc3-core.patch
index 3bdf71d..0dc6bbc 100644 (file)
@@ -1,74 +1,8 @@
-Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs_sb.h
+Index: linux-2.6.9-full/include/linux/ext3_fs.h
 ===================================================================
---- linux-2.6.9-42.0.10.EL_lustre.1.4.10.orig/include/linux/ext3_fs_sb.h       2007-06-14 13:59:04.000000000 +0200
-+++ linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs_sb.h    2007-06-14 14:16:57.000000000 +0200
-@@ -81,6 +81,61 @@ struct ext3_sb_info {
-       char *s_qf_names[MAXQUOTAS];            /* Names of quota files with journalled quota */
-       int s_jquota_fmt;                       /* Format of quota to use */
- #endif
-+
-+      /* for buddy allocator */
-+      struct ext3_group_info ***s_group_info;
-+      struct inode *s_buddy_cache;
-+      long s_blocks_reserved;
-+      spinlock_t s_reserve_lock;
-+      struct list_head s_active_transaction;
-+      struct list_head s_closed_transaction;
-+      struct list_head s_committed_transaction;
-+      spinlock_t s_md_lock;
-+      tid_t s_last_transaction;
-+      unsigned short *s_mb_offsets, *s_mb_maxs;
-+
-+      /* tunables */
-+      unsigned long s_mb_factor;
-+      unsigned long s_stripe;
-+      unsigned long s_mb_stream_request;
-+      unsigned long s_mb_max_to_scan;
-+      unsigned long s_mb_min_to_scan;
-+      unsigned long s_mb_max_groups_to_scan;
-+      unsigned long s_mb_stats;
-+      unsigned long s_mb_order2_reqs;
-+
-+      /* history to debug policy */
-+      struct ext3_mb_history *s_mb_history;
-+      int s_mb_history_cur;
-+      int s_mb_history_max;
-+      int s_mb_history_num;
-+      struct proc_dir_entry *s_mb_proc;
-+      spinlock_t s_mb_history_lock;
-+      int s_mb_history_filter;
-+
-+      /* stats for buddy allocator */
-+      spinlock_t s_mb_pa_lock;
-+      atomic_t s_bal_reqs;    /* number of reqs with len > 1 */
-+      atomic_t s_bal_success; /* we found long enough chunks */
-+      atomic_t s_bal_allocated;       /* in blocks */
-+      atomic_t s_bal_ex_scanned;      /* total extents scanned */
-+      atomic_t s_bal_goals;   /* goal hits */
-+      atomic_t s_bal_breaks;  /* too long searches */
-+      atomic_t s_bal_2orders; /* 2^order hits */
-+      spinlock_t s_bal_lock;
-+      unsigned long s_mb_buddies_generated;
-+      unsigned long long s_mb_generation_time;
-+      atomic_t s_mb_lost_chunks;
-+      atomic_t s_mb_preallocated;
-+      atomic_t s_mb_discarded;
-+
-+      /* locality groups */
-+      struct ext3_locality_group *s_locality_groups;
-+
- };
-+#define EXT3_GROUP_INFO(sb, group)                                       \
-+      EXT3_SB(sb)->s_group_info[(group) >> EXT3_DESC_PER_BLOCK_BITS(sb)] \
-+                               [(group) & (EXT3_DESC_PER_BLOCK(sb) - 1)]
-+
- #endif        /* _LINUX_EXT3_FS_SB */
-Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs.h
-===================================================================
---- linux-2.6.9-42.0.10.EL_lustre.1.4.10.orig/include/linux/ext3_fs.h  2007-06-14 13:59:04.000000000 +0200
-+++ linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs.h       2007-06-14 14:16:57.000000000 +0200
-@@ -57,6 +57,30 @@ struct statfs;
+--- linux-2.6.9-full.orig/include/linux/ext3_fs.h
++++ linux-2.6.9-full/include/linux/ext3_fs.h
+@@ -53,6 +53,30 @@
  #define ext3_debug(f, a...)   do {} while (0)
  #endif
  
@@ -99,7 +33,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs.h
  /*
   * Special inodes numbers
   */
-@@ -387,6 +411,14 @@ struct ext3_inode {
+@@ -398,6 +422,14 @@ struct ext3_inode {
  #define ext3_find_first_zero_bit      ext2_find_first_zero_bit
  #define ext3_find_next_zero_bit               ext2_find_next_zero_bit
  
@@ -114,7 +48,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs.h
  /*
   * Maximal mount counts between two filesystem checks
   */
-@@ -763,6 +795,20 @@ extern unsigned long ext3_count_dirs (st
+@@ -799,6 +831,20 @@ extern unsigned long ext3_count_dirs (st
  extern void ext3_check_inodes_bitmap (struct super_block *);
  extern unsigned long ext3_count_free (struct buffer_head *, unsigned);
  
@@ -134,12 +68,78 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/include/linux/ext3_fs.h
 +
  
  /* inode.c */
- extern int ext3_block_truncate_page(handle_t *, struct page *,
-Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/super.c
+ int ext3_forget(handle_t *handle, int is_metadata, struct inode *inode,
+Index: linux-2.6.9-full/include/linux/ext3_fs_sb.h
+===================================================================
+--- linux-2.6.9-full.orig/include/linux/ext3_fs_sb.h
++++ linux-2.6.9-full/include/linux/ext3_fs_sb.h
+@@ -88,6 +88,61 @@ struct ext3_sb_info {
+       unsigned long s_ext_blocks;
+       unsigned long s_ext_extents;
+ #endif
++
++      /* for buddy allocator */
++      struct ext3_group_info ***s_group_info;
++      struct inode *s_buddy_cache;
++      long s_blocks_reserved;
++      spinlock_t s_reserve_lock;
++      struct list_head s_active_transaction;
++      struct list_head s_closed_transaction;
++      struct list_head s_committed_transaction;
++      spinlock_t s_md_lock;
++      tid_t s_last_transaction;
++      unsigned short *s_mb_offsets, *s_mb_maxs;
++
++      /* tunables */
++      unsigned long s_mb_factor;
++      unsigned long s_stripe;
++      unsigned long s_mb_stream_request;
++      unsigned long s_mb_max_to_scan;
++      unsigned long s_mb_min_to_scan;
++      unsigned long s_mb_max_groups_to_scan;
++      unsigned long s_mb_stats;
++      unsigned long s_mb_order2_reqs;
++
++      /* history to debug policy */
++      struct ext3_mb_history *s_mb_history;
++      int s_mb_history_cur;
++      int s_mb_history_max;
++      int s_mb_history_num;
++      struct proc_dir_entry *s_mb_proc;
++      spinlock_t s_mb_history_lock;
++      int s_mb_history_filter;
++
++      /* stats for buddy allocator */
++      spinlock_t s_mb_pa_lock;
++      atomic_t s_bal_reqs;    /* number of reqs with len > 1 */
++      atomic_t s_bal_success; /* we found long enough chunks */
++      atomic_t s_bal_allocated;       /* in blocks */
++      atomic_t s_bal_ex_scanned;      /* total extents scanned */
++      atomic_t s_bal_goals;   /* goal hits */
++      atomic_t s_bal_breaks;  /* too long searches */
++      atomic_t s_bal_2orders; /* 2^order hits */
++      spinlock_t s_bal_lock;
++      unsigned long s_mb_buddies_generated;
++      unsigned long long s_mb_generation_time;
++      atomic_t s_mb_lost_chunks;
++      atomic_t s_mb_preallocated;
++      atomic_t s_mb_discarded;
++
++      /* locality groups */
++      struct ext3_locality_group *s_locality_groups;
++
+ };
++#define EXT3_GROUP_INFO(sb, group)                                       \
++      EXT3_SB(sb)->s_group_info[(group) >> EXT3_DESC_PER_BLOCK_BITS(sb)] \
++                               [(group) & (EXT3_DESC_PER_BLOCK(sb) - 1)]
++
+ #endif        /* _LINUX_EXT3_FS_SB */
+Index: linux-2.6.9-full/fs/ext3/super.c
 ===================================================================
---- linux-2.6.9-42.0.10.EL_lustre.1.4.10.orig/fs/ext3/super.c  2007-06-14 13:59:04.000000000 +0200
-+++ linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/super.c       2007-06-14 14:16:57.000000000 +0200
-@@ -394,6 +394,7 @@ void ext3_put_super (struct super_block 
+--- linux-2.6.9-full.orig/fs/ext3/super.c
++++ linux-2.6.9-full/fs/ext3/super.c
+@@ -391,6 +391,7 @@ static void ext3_put_super (struct super
        struct ext3_super_block *es = sbi->s_es;
        int i;
  
@@ -147,16 +147,16 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/super.c
        ext3_ext_release(sb);
        ext3_xattr_put_super(sb);
        journal_destroy(sbi->s_journal);
-@@ -463,6 +464,8 @@ static struct inode *ext3_alloc_inode(st
+@@ -458,6 +459,8 @@ static struct inode *ext3_alloc_inode(st
        ei->vfs_inode.i_version = 1;
-       
        memset(&ei->i_cached_extent, 0, sizeof(ei->i_cached_extent));
 +      INIT_LIST_HEAD(&ei->i_prealloc_list);
 +      spin_lock_init(&ei->i_prealloc_lock);
        return &ei->vfs_inode;
  }
  
-@@ -2576,7 +2579,13 @@ static struct file_system_type ext3_fs_t
+@@ -2763,7 +2766,13 @@ static struct file_system_type ext3_fs_t
  
  static int __init init_ext3_fs(void)
  {
@@ -171,19 +171,19 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/super.c
        if (err)
                return err;
        err = init_inodecache();
-@@ -2598,6 +2607,7 @@ static void __exit exit_ext3_fs(void)
+@@ -2785,6 +2794,7 @@ static void __exit exit_ext3_fs(void)
        unregister_filesystem(&ext3_fs_type);
        destroy_inodecache();
        exit_ext3_xattr();
 +      exit_ext3_proc();
  }
  
- int ext3_prep_san_write(struct inode *inode, long *blocks,
-Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
+ int ext3_map_inode_page(struct inode *inode, struct page *page,
+Index: linux-2.6.9-full/fs/ext3/mballoc.c
 ===================================================================
---- /dev/null  1970-01-01 00:00:00.000000000 +0000
-+++ linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c     2007-06-14 14:19:27.000000000 +0200
-@@ -0,0 +1,4369 @@
+--- /dev/null
++++ linux-2.6.9-full/fs/ext3/mballoc.c
+@@ -0,0 +1,4395 @@
 +/*
 + * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
 + * Written by Alex Tomas <alex@clusterfs.com>
@@ -742,10 +742,10 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      ext2_set_bit(bit, addr);
 +}
 +
-+static inline void mb_set_bit_atomic(int bit, void *addr)
++static inline void mb_set_bit_atomic(spinlock_t *lock, int bit, void *addr)
 +{
 +      mb_correct_addr_and_bit(bit,addr);
-+      ext2_set_bit_atomic(NULL, bit, addr);
++      ext2_set_bit_atomic(lock, bit, addr);
 +}
 +
 +static inline void mb_clear_bit(int bit, void *addr)
@@ -754,10 +754,10 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      ext2_clear_bit(bit, addr);
 +}
 +
-+static inline void mb_clear_bit_atomic(int bit, void *addr)
++static inline void mb_clear_bit_atomic(spinlock_t *lock, int bit, void *addr)
 +{
 +      mb_correct_addr_and_bit(bit,addr);
-+      ext2_clear_bit_atomic(NULL, bit, addr);
++      ext2_clear_bit_atomic(lock, bit, addr);
 +}
 +
 +static inline int mb_find_next_zero_bit(void *addr, int max, int start)
@@ -1328,7 +1328,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      return 0;
 +}
 +
-+static inline void mb_clear_bits(void *bm, int cur, int len)
++static inline void mb_clear_bits(spinlock_t *lock, void *bm, int cur, int len)
 +{
 +      __u32 *addr;
 +
@@ -1341,12 +1341,12 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      cur += 32;
 +                      continue;
 +              }
-+              mb_clear_bit_atomic(cur, bm);
++              mb_clear_bit_atomic(lock, cur, bm);
 +              cur++;
 +      }
 +}
 +
-+static inline void mb_set_bits(void *bm, int cur, int len)
++static inline void mb_set_bits(spinlock_t *lock, void *bm, int cur, int len)
 +{
 +      __u32 *addr;
 +
@@ -1359,7 +1359,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      cur += 32;
 +                      continue;
 +              }
-+              mb_set_bit_atomic(cur, bm);
++              mb_set_bit_atomic(lock, cur, bm);
 +              cur++;
 +      }
 +}
@@ -1566,7 +1566,8 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +              e3b->bd_info->bb_counters[ord]++;
 +      }
 +
-+      mb_set_bits(EXT3_MB_BITMAP(e3b), ex->fe_start, len0);
++      mb_set_bits(sb_bgl_lock(EXT3_SB(e3b->bd_sb), ex->fe_group),
++                  EXT3_MB_BITMAP(e3b), ex->fe_start, len0);
 +      mb_check_buddy(e3b);
 +
 +      return ret;
@@ -2388,7 +2389,8 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      spin_lock_init(&sbi->s_mb_history_lock);
 +      i = sbi->s_mb_history_max * sizeof(struct ext3_mb_history);
 +      sbi->s_mb_history = kmalloc(i, GFP_KERNEL);
-+      memset(sbi->s_mb_history, 0, i);
++       if (likely(sbi->s_mb_history != NULL))
++               memset(sbi->s_mb_history, 0, i);
 +      /* if we can't allocate history, then we simple won't use it */
 +}
 +
@@ -2398,7 +2400,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      struct ext3_sb_info *sbi = EXT3_SB(ac->ac_sb);
 +      struct ext3_mb_history h;
 +
-+      if (likely(sbi->s_mb_history == NULL))
++      if (unlikely(sbi->s_mb_history == NULL))
 +              return;
 +
 +      if (!(ac->ac_op & sbi->s_mb_history_filter))
@@ -3091,7 +3093,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      struct ext3_sb_info *sbi;
 +      struct super_block *sb;
 +      sector_t block;
-+      int len, err;
++      int err;
 +
 +      BUG_ON(ac->ac_status != AC_STATUS_FOUND);
 +      BUG_ON(ac->ac_b_ex.fe_len <= 0);
@@ -3103,20 +3105,6 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      ext3_debug("using block group %d(%d)\n", ac->ac_b_group.group,
 +                      gdp->bg_free_blocks_count);
 +
-+      /* time to check quota, we can't do this before because
-+       * having quota spent on preallocated-unused-yet blocks
-+       * would be wrong */
-+      len = ac->ac_b_ex.fe_len;
-+      while (len && DQUOT_ALLOC_BLOCK(ac->ac_inode, len)) len--;
-+      if (ac->ac_b_ex.fe_len != len) {
-+              /* some blocks can't be allocated due to quota
-+               * we have to return them back */
-+              BUG();
-+      }
-+      err = -EDQUOT;
-+      if (len == 0)
-+              goto out_err;
-+
 +      err = -EIO;
 +      bitmap_bh = read_block_bitmap(sb, ac->ac_b_ex.fe_group);
 +      if (!bitmap_bh)
@@ -3155,7 +3143,8 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +              }
 +      }
 +#endif
-+      mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len);
++      mb_set_bits(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group), bitmap_bh->b_data,
++                  ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len);
 +
 +      spin_lock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
 +      gdp->bg_free_blocks_count =
@@ -3287,6 +3276,15 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +              unsigned long pa_end;
 +
 +              pa = list_entry(cur, struct ext3_prealloc_space, pa_inode_list);
++
++              if (pa->pa_deleted)
++                      continue;
++              spin_lock(&pa->pa_lock);
++              if (pa->pa_deleted) {
++                      spin_unlock(&pa->pa_lock);
++                      continue;
++              }
++
 +              pa_end = pa->pa_lstart + pa->pa_len;
 +
 +              /* PA must not overlap original request */
@@ -3294,10 +3292,14 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      ac->ac_o_ex.fe_logical < pa->pa_lstart));
 +
 +              /* skip PA normalized request doesn't overlap with */
-+              if (pa->pa_lstart >= end)
++              if (pa->pa_lstart >= end) {
++                      spin_unlock(&pa->pa_lock);
 +                      continue;
-+              if (pa_end <= start)
++              }
++              if (pa_end <= start) {
++                      spin_unlock(&pa->pa_lock);
 +                      continue;
++              }
 +              BUG_ON(pa->pa_lstart <= start && pa_end >= end);
 +
 +              if (pa_end <= ac->ac_o_ex.fe_logical) {
@@ -3309,6 +3311,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      BUG_ON(pa->pa_lstart > end);
 +                      end = pa->pa_lstart;
 +              }
++              spin_unlock(&pa->pa_lock);
 +      }
 +      rcu_read_unlock();
 +      size = end - start;
@@ -3319,8 +3322,12 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +              struct ext3_prealloc_space *pa;
 +              unsigned long pa_end;
 +              pa = list_entry(cur, struct ext3_prealloc_space, pa_inode_list);
-+              pa_end = pa->pa_lstart + pa->pa_len;
-+              BUG_ON(!(start >= pa_end || end <= pa->pa_lstart));
++              spin_lock(&pa->pa_lock);
++              if (pa->pa_deleted == 0) {
++                      pa_end = pa->pa_lstart + pa->pa_len;
++                      BUG_ON(!(start >= pa_end || end <= pa->pa_lstart));
++              }
++              spin_unlock(&pa->pa_lock);
 +      }
 +      rcu_read_unlock();
 +
@@ -3511,7 +3518,7 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +              len = pa->pa_len;
 +              spin_unlock(&pa->pa_lock);
 +              BUG_ON(groupnr != group);
-+              mb_set_bits(bitmap, start, len);
++              mb_set_bits(sb_bgl_lock(EXT3_SB(sb), group), bitmap, start,len);
 +              preallocated += len;
 +              count++;
 +      }
@@ -3896,8 +3903,10 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      }
 +
 +      /* if we still need more blocks and some PAs were used, try again */
-+      if (free < needed && busy)
++      if (free < needed && busy) {
++              ext3_unlock_group(sb, group);
 +              goto repeat;
++      }
 +
 +      /* found anything to free? */
 +      if (list_empty(&list)) {
@@ -4233,8 +4242,8 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +      struct ext3_allocation_context ac;
 +      struct ext3_sb_info *sbi;
 +      struct super_block *sb;
-+      unsigned long block;
-+      int err, freed;
++      unsigned long block = 0;
++      int freed, inquota;
 +
 +      sb = ar->inode->i_sb;
 +      sbi = EXT3_SB(sb);
@@ -4245,14 +4254,26 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      printk(KERN_ERR "EXT3-fs: multiblock request with "
 +                                      "mballoc disabled!\n");
 +              ar->len = 1;
-+              err = ext3_new_block_old(handle, ar->inode, ar->goal, errp);
-+              return err;
++              block = ext3_new_block_old(handle, ar->inode, ar->goal, errp);
++              return block;
 +      }
 +
++      while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
++              ar->flags |= EXT3_MB_HINT_NOPREALLOC;
++              ar->len--;
++      }
++      if (ar->len == 0) {
++              *errp = -EDQUOT;
++              return 0;
++      }
++      inquota = ar->len;
++
 +      ext3_mb_poll_new_transaction(sb, handle);
 +
-+      if ((err = ext3_mb_initialize_context(&ac, ar)))
-+              return err;
++      if ((*errp = ext3_mb_initialize_context(&ac, ar))) {
++              ar->len = 0;
++              goto out;
++      }
 +
 +      ac.ac_op = EXT3_MB_HISTORY_PREALLOC;
 +      if (!ext3_mb_use_preallocated(&ac)) {
@@ -4283,12 +4304,16 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      goto repeat;
 +              *errp = -ENOSPC;
 +              ac.ac_b_ex.fe_len = 0;
-+              block = 0;
++              ar->len = 0;
 +              ext3_mb_show_ac(&ac);
 +      }
 +
 +      ext3_mb_release_context(&ac);
 +
++out:
++      if (ar->len < inquota)
++              DQUOT_FREE_BLOCK(ar->inode, inquota - ar->len);
++
 +      return block;
 +}
 +EXPORT_SYMBOL(ext3_mb_new_blocks);
@@ -4504,7 +4529,8 @@ Index: linux-2.6.9-42.0.10.EL_lustre.1.4.10/fs/ext3/mballoc.c
 +                      BUG_ON(!mb_test_bit(bit + i, bitmap_bh->b_data));
 +      }
 +#endif
-+      mb_clear_bits(bitmap_bh->b_data, bit, count);
++      mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data, bit,
++                      count);
 +
 +      /* We dirtied the bitmap block */
 +      BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");