2.6.24

 fs

 ext2

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index baf71dd..377ad17 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -94,70 +94,17 @@ error_out:
    return bh;
 }
 
-/*
- * Set sb->s_dirt here because the superblock was "logically" altered.  We
- * need to recalculate its free blocks count and flush it out.
- */
-static int reserve_blocks(struct super_block *sb, int count)
-{
-   struct ext2_sb_info *sbi = EXT2_SB(sb);
-   struct ext2_super_block *es = sbi->s_es;
-   unsigned free_blocks;
-   unsigned root_blocks;
-
-   free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
-   root_blocks = le32_to_cpu(es->s_r_blocks_count);
-
-   if (free_blocks < count)
-      count = free_blocks;
-
-   if (free_blocks < root_blocks + count && !capable(CAP_SYS_RESOURCE) &&
-       sbi->s_resuid != current->fsuid &&
-       (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
-      /*
-       * We are too close to reserve and we are not privileged.
-       * Can we allocate anything at all?
-       */
-      if (free_blocks > root_blocks)
-         count = free_blocks - root_blocks;
-      else
-         return 0;
-   }
-
-   percpu_counter_mod(&sbi->s_freeblocks_counter, -count);
-   sb->s_dirt = 1;
-   return count;
-}
-
 static void release_blocks(struct super_block *sb, int count)
 {
    if (count) {
       struct ext2_sb_info *sbi = EXT2_SB(sb);
 
-      percpu_counter_mod(&sbi->s_freeblocks_counter, count);
+      percpu_counter_add(&sbi->s_freeblocks_counter, count);
       sb->s_dirt = 1;
    }
 }
 
-static int group_reserve_blocks(struct ext2_sb_info *sbi, int group_no,
-   struct ext2_group_desc *desc, struct buffer_head *bh, int count)
-{
-   unsigned free_blocks;
-
-   if (!desc->bg_free_blocks_count)
-      return 0;
-
-   spin_lock(sb_bgl_lock(sbi, group_no));
-   free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
-   if (free_blocks < count)
-      count = free_blocks;
-   desc->bg_free_blocks_count = cpu_to_le16(free_blocks - count);
-   spin_unlock(sb_bgl_lock(sbi, group_no));
-   mark_buffer_dirty(bh);
-   return count;
-}
-
-static void group_release_blocks(struct super_block *sb, int group_no,
+static void group_adjust_blocks(struct super_block *sb, int group_no,
    struct ext2_group_desc *desc, struct buffer_head *bh, int count)
 {
    if (count) {
@@ -173,7 +120,306 @@ static void group_release_blocks(struct super_block *sb, int group_no,
    }
 }
 
-/* Free given blocks, update quota and i_blocks field */
+/*
+ * The reservation window structure operations
+ * --------------------------------------------
+ * Operations include:
+ * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
+ *
+ * We use a red-black tree to represent per-filesystem reservation
+ * windows.
+ *
+ */
+
+/**
+ * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
+ * @rb_root:      root of per-filesystem reservation rb tree
+ * @verbose:      verbose mode
+ * @fn:         function which wishes to dump the reservation map
+ *
+ * If verbose is turned on, it will print the whole block reservation
+ * windows(start, end). Otherwise, it will only print out the "bad" windows,
+ * those windows that overlap with their immediate neighbors.
+ */
+#if 1
+static void __rsv_window_dump(struct rb_root *root, int verbose,
+               const char *fn)
+{
+   struct rb_node *n;
+   struct ext2_reserve_window_node *rsv, *prev;
+   int bad;
+
+restart:
+   n = rb_first(root);
+   bad = 0;
+   prev = NULL;
+
+   printk("Block Allocation Reservation Windows Map (%s):\n", fn);
+   while (n) {
+      rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
+      if (verbose)
+         printk("reservation window 0x%p "
+            "start: %lu, end: %lu\n",
+            rsv, rsv->rsv_start, rsv->rsv_end);
+      if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
+         printk("Bad reservation %p (start >= end)\n",
+                rsv);
+         bad = 1;
+      }
+      if (prev && prev->rsv_end >= rsv->rsv_start) {
+         printk("Bad reservation %p (prev->end >= start)\n",
+                rsv);
+         bad = 1;
+      }
+      if (bad) {
+         if (!verbose) {
+            printk("Restarting reservation walk in verbose mode\n");
+            verbose = 1;
+            goto restart;
+         }
+      }
+      n = rb_next(n);
+      prev = rsv;
+   }
+   printk("Window map complete.\n");
+   if (bad)
+      BUG();
+}
+#define rsv_window_dump(root, verbose) \
+   __rsv_window_dump((root), (verbose), __FUNCTION__)
+#else
+#define rsv_window_dump(root, verbose) do {} while (0)
+#endif
+
+/**
+ * goal_in_my_reservation()
+ * @rsv:      inode's reservation window
+ * @grp_goal:      given goal block relative to the allocation block group
+ * @group:      the current allocation block group
+ * @sb:         filesystem super block
+ *
+ * Test if the given goal block (group relative) is within the file's
+ * own block reservation window range.
+ *
+ * If the reservation window is outside the goal allocation group, return 0;
+ * grp_goal (given goal block) could be -1, which means no specific
+ * goal block. In this case, always return 1.
+ * If the goal block is within the reservation window, return 1;
+ * otherwise, return 0;
+ */
+static int
+goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
+         unsigned int group, struct super_block * sb)
+{
+   ext2_fsblk_t group_first_block, group_last_block;
+
+   group_first_block = ext2_group_first_block_no(sb, group);
+   group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
+
+   if ((rsv->_rsv_start > group_last_block) ||
+       (rsv->_rsv_end < group_first_block))
+      return 0;
+   if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
+      || (grp_goal + group_first_block > rsv->_rsv_end)))
+      return 0;
+   return 1;
+}
+
+/**
+ * search_reserve_window()
+ * @rb_root:      root of reservation tree
+ * @goal:      target allocation block
+ *
+ * Find the reserved window which includes the goal, or the previous one
+ * if the goal is not in any window.
+ * Returns NULL if there are no windows or if all windows start after the goal.
+ */
+static struct ext2_reserve_window_node *
+search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
+{
+   struct rb_node *n = root->rb_node;
+   struct ext2_reserve_window_node *rsv;
+
+   if (!n)
+      return NULL;
+
+   do {
+      rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
+
+      if (goal < rsv->rsv_start)
+         n = n->rb_left;
+      else if (goal > rsv->rsv_end)
+         n = n->rb_right;
+      else
+         return rsv;
+   } while (n);
+   /*
+    * We've fallen off the end of the tree: the goal wasn't inside
+    * any particular node.  OK, the previous node must be to one
+    * side of the interval containing the goal.  If it's the RHS,
+    * we need to back up one.
+    */
+   if (rsv->rsv_start > goal) {
+      n = rb_prev(&rsv->rsv_node);
+      rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
+   }
+   return rsv;
+}
+
+/*
+ * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
+ * @sb:         super block
+ * @rsv:      reservation window to add
+ *
+ * Must be called with rsv_lock held.
+ */
+void ext2_rsv_window_add(struct super_block *sb,
+          struct ext2_reserve_window_node *rsv)
+{
+   struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
+   struct rb_node *node = &rsv->rsv_node;
+   ext2_fsblk_t start = rsv->rsv_start;
+
+   struct rb_node ** p = &root->rb_node;
+   struct rb_node * parent = NULL;
+   struct ext2_reserve_window_node *this;
+
+   while (*p)
+   {
+      parent = *p;
+      this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
+
+      if (start < this->rsv_start)
+         p = &(*p)->rb_left;
+      else if (start > this->rsv_end)
+         p = &(*p)->rb_right;
+      else {
+         rsv_window_dump(root, 1);
+         BUG();
+      }
+   }
+
+   rb_link_node(node, parent, p);
+   rb_insert_color(node, root);
+}
+
+/**
+ * rsv_window_remove() -- unlink a window from the reservation rb tree
+ * @sb:         super block
+ * @rsv:      reservation window to remove
+ *
+ * Mark the block reservation window as not allocated, and unlink it
+ * from the filesystem reservation window rb tree. Must be called with
+ * rsv_lock held.
+ */
+static void rsv_window_remove(struct super_block *sb,
+               struct ext2_reserve_window_node *rsv)
+{
+   rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
+   rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
+   rsv->rsv_alloc_hit = 0;
+   rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
+}
+
+/*
+ * rsv_is_empty() -- Check if the reservation window is allocated.
+ * @rsv:      given reservation window to check
+ *
+ * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
+ */
+static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
+{
+   /* a valid reservation end block could not be 0 */
+   return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
+}
+
+/**
+ * ext2_init_block_alloc_info()
+ * @inode:      file inode structure
+ *
+ * Allocate and initialize the  reservation window structure, and
+ * link the window to the ext2 inode structure at last
+ *
+ * The reservation window structure is only dynamically allocated
+ * and linked to ext2 inode the first time the open file
+ * needs a new block. So, before every ext2_new_block(s) call, for
+ * regular files, we should check whether the reservation window
+ * structure exists or not. In the latter case, this function is called.
+ * Fail to do so will result in block reservation being turned off for that
+ * open file.
+ *
+ * This function is called from ext2_get_blocks_handle(), also called
+ * when setting the reservation window size through ioctl before the file
+ * is open for write (needs block allocation).
+ *
+ * Needs truncate_mutex protection prior to calling this function.
+ */
+void ext2_init_block_alloc_info(struct inode *inode)
+{
+   struct ext2_inode_info *ei = EXT2_I(inode);
+   struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
+   struct super_block *sb = inode->i_sb;
+
+   block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
+   if (block_i) {
+      struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
+
+      rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
+      rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
+
+       /*
+       * if filesystem is mounted with NORESERVATION, the goal
+       * reservation window size is set to zero to indicate
+       * block reservation is off
+       */
+      if (!test_opt(sb, RESERVATION))
+         rsv->rsv_goal_size = 0;
+      else
+         rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
+      rsv->rsv_alloc_hit = 0;
+      block_i->last_alloc_logical_block = 0;
+      block_i->last_alloc_physical_block = 0;
+   }
+   ei->i_block_alloc_info = block_i;
+}
+
+/**
+ * ext2_discard_reservation()
+ * @inode:      inode
+ *
+ * Discard(free) block reservation window on last file close, or truncate
+ * or at last iput().
+ *
+ * It is being called in three cases:
+ *    ext2_release_file(): last writer closes the file
+ *    ext2_clear_inode(): last iput(), when nobody links to this file.
+ *    ext2_truncate(): when the block indirect map is about to change.
+ */
+void ext2_discard_reservation(struct inode *inode)
+{
+   struct ext2_inode_info *ei = EXT2_I(inode);
+   struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
+   struct ext2_reserve_window_node *rsv;
+   spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
+
+   if (!block_i)
+      return;
+
+   rsv = &block_i->rsv_window_node;
+   if (!rsv_is_empty(&rsv->rsv_window)) {
+      spin_lock(rsv_lock);
+      if (!rsv_is_empty(&rsv->rsv_window))
+         rsv_window_remove(inode->i_sb, rsv);
+      spin_unlock(rsv_lock);
+   }
+}
+
+/**
+ * ext2_free_blocks_sb() -- Free given blocks and update quota and i_blocks
+ * @inode:      inode
+ * @block:      start physcial block to free
+ * @count:      number of blocks to free
+ */
 void ext2_free_blocks (struct inode * inode, unsigned long block,
              unsigned long count)
 {
@@ -248,7 +494,7 @@ do_more:
    if (sb->s_flags & MS_SYNCHRONOUS)
       sync_dirty_buffer(bitmap_bh);
 
-   group_release_blocks(sb, block_group, desc, bh2, group_freed);
+   group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
    freed += group_freed;
 
    if (overflow) {
@@ -262,16 +508,46 @@ error_return:
    DQUOT_FREE_BLOCK(inode, freed);
 }
 
-static int grab_block(spinlock_t *lock, char *map, unsigned size, int goal)
+/**
+ * bitmap_search_next_usable_block()
+ * @start:      the starting block (group relative) of the search
+ * @bh:         bufferhead contains the block group bitmap
+ * @maxblocks:      the ending block (group relative) of the reservation
+ *
+ * The bitmap search --- search forward through the actual bitmap on disk until
+ * we find a bit free.
+ */
+static ext2_grpblk_t
+bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
+               ext2_grpblk_t maxblocks)
 {
-   int k;
-   char *p, *r;
+   ext2_grpblk_t next;
 
-   if (!ext2_test_bit(goal, map))
-      goto got_it;
+   next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
+   if (next >= maxblocks)
+      return -1;
+   return next;
+}
 
-repeat:
-   if (goal) {
+/**
+ * find_next_usable_block()
+ * @start:      the starting block (group relative) to find next
+ *          allocatable block in bitmap.
+ * @bh:         bufferhead contains the block group bitmap
+ * @maxblocks:      the ending block (group relative) for the search
+ *
+ * Find an allocatable block in a bitmap.  We perform the "most
+ * appropriate allocation" algorithm of looking for a free block near
+ * the initial goal; then for a free byte somewhere in the bitmap;
+ * then for any free bit in the bitmap.
+ */
+static ext2_grpblk_t
+find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
+{
+   ext2_grpblk_t here, next;
+   char *p, *r;
+
+   if (start > 0) {
       /*
        * The goal was occupied; search forward for a free 
        * block within the next XX blocks.
@@ -280,249 +556,812 @@ repeat:
        * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
        * next 64-bit boundary is simple..
        */
-      k = (goal + 63) & ~63;
-      goal = ext2_find_next_zero_bit(map, k, goal);
-      if (goal < k)
-         goto got_it;
+      ext2_grpblk_t end_goal = (start + 63) & ~63;
+      if (end_goal > maxblocks)
+         end_goal = maxblocks;
+      here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
+      if (here < end_goal)
+         return here;
+      ext2_debug("Bit not found near goal\n");
+   }
+
+   here = start;
+   if (here < 0)
+      here = 0;
+
+   p = ((char *)bh->b_data) + (here >> 3);
+   r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
+   next = (r - ((char *)bh->b_data)) << 3;
+
+   if (next < maxblocks && next >= here)
+      return next;
+
+   here = bitmap_search_next_usable_block(here, bh, maxblocks);
+   return here;
+}
+
+/*
+ * ext2_try_to_allocate()
+ * @sb:         superblock
+ * @handle:      handle to this transaction
+ * @group:      given allocation block group
+ * @bitmap_bh:      bufferhead holds the block bitmap
+ * @grp_goal:      given target block within the group
+ * @count:      target number of blocks to allocate
+ * @my_rsv:      reservation window
+ *
+ * Attempt to allocate blocks within a give range. Set the range of allocation
+ * first, then find the first free bit(s) from the bitmap (within the range),
+ * and at last, allocate the blocks by claiming the found free bit as allocated.
+ *
+ * To set the range of this allocation:
+ *    if there is a reservation window, only try to allocate block(s)
+ *    from the file's own reservation window;
+ *    Otherwise, the allocation range starts from the give goal block,
+ *    ends at the block group's last block.
+ *
+ * If we failed to allocate the desired block then we may end up crossing to a
+ * new bitmap.
+ */
+static int
+ext2_try_to_allocate(struct super_block *sb, int group,
+         struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
+         unsigned long *count,
+         struct ext2_reserve_window *my_rsv)
+{
+   ext2_fsblk_t group_first_block;
+          ext2_grpblk_t start, end;
+   unsigned long num = 0;
+
+   /* we do allocation within the reservation window if we have a window */
+   if (my_rsv) {
+      group_first_block = ext2_group_first_block_no(sb, group);
+      if (my_rsv->_rsv_start >= group_first_block)
+         start = my_rsv->_rsv_start - group_first_block;
+      else
+         /* reservation window cross group boundary */
+         start = 0;
+      end = my_rsv->_rsv_end - group_first_block + 1;
+      if (end > EXT2_BLOCKS_PER_GROUP(sb))
+         /* reservation window crosses group boundary */
+         end = EXT2_BLOCKS_PER_GROUP(sb);
+      if ((start <= grp_goal) && (grp_goal < end))
+         start = grp_goal;
+      else
+         grp_goal = -1;
+   } else {
+      if (grp_goal > 0)
+         start = grp_goal;
+      else
+         start = 0;
+      end = EXT2_BLOCKS_PER_GROUP(sb);
+   }
+
+   BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
+
+repeat:
+   if (grp_goal < 0) {
+      grp_goal = find_next_usable_block(start, bitmap_bh, end);
+      if (grp_goal < 0)
+         goto fail_access;
+      if (!my_rsv) {
+         int i;
+
+         for (i = 0; i < 7 && grp_goal > start &&
+               !ext2_test_bit(grp_goal - 1,
+                          bitmap_bh->b_data);
+                    i++, grp_goal--)
+            ;
+      }
+   }
+   start = grp_goal;
+
+   if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
+                            bitmap_bh->b_data)) {
       /*
-       * Search in the remainder of the current group.
+       * The block was allocated by another thread, or it was
+       * allocated and then freed by another thread
        */
+      start++;
+      grp_goal++;
+      if (start >= end)
+         goto fail_access;
+      goto repeat;
    }
+   num++;
+   grp_goal++;
+   while (num < *count && grp_goal < end
+      && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
+               grp_goal, bitmap_bh->b_data)) {
+      num++;
+      grp_goal++;
+   }
+   *count = num;
+   return grp_goal - num;
+fail_access:
+   *count = num;
+   return -1;
+}
 
-   p = map + (goal >> 3);
-   r = memscan(p, 0, (size - goal + 7) >> 3);
-   k = (r - map) << 3;
-   if (k < size) {
-      /* 
-       * We have succeeded in finding a free byte in the block
-       * bitmap.  Now search backwards to find the start of this
-       * group of free blocks - won't take more than 7 iterations.
+/**
+ *    find_next_reservable_window():
+ *      find a reservable space within the given range.
+ *      It does not allocate the reservation window for now:
+ *      alloc_new_reservation() will do the work later.
+ *
+ *    @search_head: the head of the searching list;
+ *      This is not necessarily the list head of the whole filesystem
+ *
+ *      We have both head and start_block to assist the search
+ *      for the reservable space. The list starts from head,
+ *      but we will shift to the place where start_block is,
+ *      then start from there, when looking for a reservable space.
+ *
+ *    @size: the target new reservation window size
+ *
+ *    @group_first_block: the first block we consider to start
+ *         the real search from
+ *
+ *    @last_block:
+ *      the maximum block number that our goal reservable space
+ *      could start from. This is normally the last block in this
+ *      group. The search will end when we found the start of next
+ *      possible reservable space is out of this boundary.
+ *      This could handle the cross boundary reservation window
+ *      request.
+ *
+ *    basically we search from the given range, rather than the whole
+ *    reservation double linked list, (start_block, last_block)
+ *    to find a free region that is of my size and has not
+ *    been reserved.
+ *
+ */
+static int find_next_reservable_window(
+            struct ext2_reserve_window_node *search_head,
+            struct ext2_reserve_window_node *my_rsv,
+            struct super_block * sb,
+            ext2_fsblk_t start_block,
+            ext2_fsblk_t last_block)
+{
+   struct rb_node *next;
+   struct ext2_reserve_window_node *rsv, *prev;
+   ext2_fsblk_t cur;
+   int size = my_rsv->rsv_goal_size;
+
+   /* TODO: make the start of the reservation window byte-aligned */
+   /* cur = *start_block & ~7;*/
+   cur = start_block;
+   rsv = search_head;
+   if (!rsv)
+      return -1;
+
+   while (1) {
+      if (cur <= rsv->rsv_end)
+         cur = rsv->rsv_end + 1;
+
+      /* TODO?
+       * in the case we could not find a reservable space
+       * that is what is expected, during the re-search, we could
+       * remember what's the largest reservable space we could have
+       * and return that one.
+       *
+       * For now it will fail if we could not find the reservable
+       * space with expected-size (or more)...
        */
-      for (goal = k; goal && !ext2_test_bit (goal - 1, map); goal--)
-         ;
-      goto got_it;
+      if (cur > last_block)
+         return -1;      /* fail */
+
+      prev = rsv;
+      next = rb_next(&rsv->rsv_node);
+      rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
+
+      /*
+       * Reached the last reservation, we can just append to the
+       * previous one.
+       */
+      if (!next)
+         break;
+
+      if (cur + size <= rsv->rsv_start) {
+         /*
+          * Found a reserveable space big enough.  We could
+          * have a reservation across the group boundary here
+           */
+         break;
+      }
    }
+   /*
+    * we come here either :
+    * when we reach the end of the whole list,
+    * and there is empty reservable space after last entry in the list.
+    * append it to the end of the list.
+    *
+    * or we found one reservable space in the middle of the list,
+    * return the reservation window that we could append to.
+    * succeed.
+    */
+
+   if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
+      rsv_window_remove(sb, my_rsv);
+
+   /*
+    * Let's book the whole avaliable window for now.  We will check the
+    * disk bitmap later and then, if there are free blocks then we adjust
+    * the window size if it's larger than requested.
+    * Otherwise, we will remove this node from the tree next time
+    * call find_next_reservable_window.
+    */
+   my_rsv->rsv_start = cur;
+   my_rsv->rsv_end = cur + size - 1;
+   my_rsv->rsv_alloc_hit = 0;
+
+   if (prev != my_rsv)
+      ext2_rsv_window_add(sb, my_rsv);
+
+   return 0;
+}
 
-   k = ext2_find_next_zero_bit ((u32 *)map, size, goal);
-   if (k < size) {
-      goal = k;
-      goto got_it;
+/**
+ *    alloc_new_reservation()--allocate a new reservation window
+ *
+ *      To make a new reservation, we search part of the filesystem
+ *      reservation list (the list that inside the group). We try to
+ *      allocate a new reservation window near the allocation goal,
+ *      or the beginning of the group, if there is no goal.
+ *
+ *      We first find a reservable space after the goal, then from
+ *      there, we check the bitmap for the first free block after
+ *      it. If there is no free block until the end of group, then the
+ *      whole group is full, we failed. Otherwise, check if the free
+ *      block is inside the expected reservable space, if so, we
+ *      succeed.
+ *      If the first free block is outside the reservable space, then
+ *      start from the first free block, we search for next available
+ *      space, and go on.
+ *
+ *   on succeed, a new reservation will be found and inserted into the list
+ *   It contains at least one free block, and it does not overlap with other
+ *   reservation windows.
+ *
+ *   failed: we failed to find a reservation window in this group
+ *
+ *   @rsv: the reservation
+ *
+ *   @grp_goal: The goal (group-relative).  It is where the search for a
+ *      free reservable space should start from.
+ *      if we have a goal(goal >0 ), then start from there,
+ *      no goal(goal = -1), we start from the first block
+ *      of the group.
+ *
+ *   @sb: the super block
+ *   @group: the group we are trying to allocate in
+ *   @bitmap_bh: the block group block bitmap
+ *
+ */
+static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
+      ext2_grpblk_t grp_goal, struct super_block *sb,
+      unsigned int group, struct buffer_head *bitmap_bh)
+{
+   struct ext2_reserve_window_node *search_head;
+   ext2_fsblk_t group_first_block, group_end_block, start_block;
+   ext2_grpblk_t first_free_block;
+   struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
+   unsigned long size;
+   int ret;
+   spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
+
+   group_first_block = ext2_group_first_block_no(sb, group);
+   group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
+
+   if (grp_goal < 0)
+      start_block = group_first_block;
+   else
+      start_block = grp_goal + group_first_block;
+
+   size = my_rsv->rsv_goal_size;
+
+   if (!rsv_is_empty(&my_rsv->rsv_window)) {
+      /*
+       * if the old reservation is cross group boundary
+       * and if the goal is inside the old reservation window,
+       * we will come here when we just failed to allocate from
+       * the first part of the window. We still have another part
+       * that belongs to the next group. In this case, there is no
+       * point to discard our window and try to allocate a new one
+       * in this group(which will fail). we should
+       * keep the reservation window, just simply move on.
+       *
+       * Maybe we could shift the start block of the reservation
+       * window to the first block of next group.
+       */
+
+      if ((my_rsv->rsv_start <= group_end_block) &&
+            (my_rsv->rsv_end > group_end_block) &&
+            (start_block >= my_rsv->rsv_start))
+         return -1;
+
+      if ((my_rsv->rsv_alloc_hit >
+           (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
+         /*
+          * if the previously allocation hit ratio is
+          * greater than 1/2, then we double the size of
+          * the reservation window the next time,
+          * otherwise we keep the same size window
+          */
+         size = size * 2;
+         if (size > EXT2_MAX_RESERVE_BLOCKS)
+            size = EXT2_MAX_RESERVE_BLOCKS;
+         my_rsv->rsv_goal_size= size;
+      }
    }
-   return -1;
-got_it:
-   if (ext2_set_bit_atomic(lock, goal, (void *) map)) 
-      goto repeat;   
-   return goal;
+
+   spin_lock(rsv_lock);
+   /*
+    * shift the search start to the window near the goal block
+    */
+   search_head = search_reserve_window(fs_rsv_root, start_block);
+
+   /*
+    * find_next_reservable_window() simply finds a reservable window
+    * inside the given range(start_block, group_end_block).
+    *
+    * To make sure the reservation window has a free bit inside it, we
+    * need to check the bitmap after we found a reservable window.
+    */
+retry:
+   ret = find_next_reservable_window(search_head, my_rsv, sb,
+                  start_block, group_end_block);
+
+   if (ret == -1) {
+      if (!rsv_is_empty(&my_rsv->rsv_window))
+         rsv_window_remove(sb, my_rsv);
+      spin_unlock(rsv_lock);
+      return -1;
+   }
+
+   /*
+    * On success, find_next_reservable_window() returns the
+    * reservation window where there is a reservable space after it.
+    * Before we reserve this reservable space, we need
+    * to make sure there is at least a free block inside this region.
+    *
+    * Search the first free bit on the block bitmap.  Search starts from
+    * the start block of the reservable space we just found.
+    */
+   spin_unlock(rsv_lock);
+   first_free_block = bitmap_search_next_usable_block(
+         my_rsv->rsv_start - group_first_block,
+         bitmap_bh, group_end_block - group_first_block + 1);
+
+   if (first_free_block < 0) {
+      /*
+       * no free block left on the bitmap, no point
+       * to reserve the space. return failed.
+       */
+      spin_lock(rsv_lock);
+      if (!rsv_is_empty(&my_rsv->rsv_window))
+         rsv_window_remove(sb, my_rsv);
+      spin_unlock(rsv_lock);
+      return -1;      /* failed */
+   }
+
+   start_block = first_free_block + group_first_block;
+   /*
+    * check if the first free block is within the
+    * free space we just reserved
+    */
+   if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
+      return 0;      /* success */
+   /*
+    * if the first free bit we found is out of the reservable space
+    * continue search for next reservable space,
+    * start from where the free block is,
+    * we also shift the list head to where we stopped last time
+    */
+   search_head = my_rsv;
+   spin_lock(rsv_lock);
+   goto retry;
+}
+
+/**
+ * try_to_extend_reservation()
+ * @my_rsv:      given reservation window
+ * @sb:         super block
+ * @size:      the delta to extend
+ *
+ * Attempt to expand the reservation window large enough to have
+ * required number of free blocks
+ *
+ * Since ext2_try_to_allocate() will always allocate blocks within
+ * the reservation window range, if the window size is too small,
+ * multiple blocks allocation has to stop at the end of the reservation
+ * window. To make this more efficient, given the total number of
+ * blocks needed and the current size of the window, we try to
+ * expand the reservation window size if necessary on a best-effort
+ * basis before ext2_new_blocks() tries to allocate blocks.
+ */
+static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
+         struct super_block *sb, int size)
+{
+   struct ext2_reserve_window_node *next_rsv;
+   struct rb_node *next;
+   spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
+
+   if (!spin_trylock(rsv_lock))
+      return;
+
+   next = rb_next(&my_rsv->rsv_node);
+
+   if (!next)
+      my_rsv->rsv_end += size;
+   else {
+      next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
+
+      if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
+         my_rsv->rsv_end += size;
+      else
+         my_rsv->rsv_end = next_rsv->rsv_start - 1;
+   }
+   spin_unlock(rsv_lock);
+}
+
+/**
+ * ext2_try_to_allocate_with_rsv()
+ * @sb:         superblock
+ * @group:      given allocation block group
+ * @bitmap_bh:      bufferhead holds the block bitmap
+ * @grp_goal:      given target block within the group
+ * @count:      target number of blocks to allocate
+ * @my_rsv:      reservation window
+ *
+ * This is the main function used to allocate a new block and its reservation
+ * window.
+ *
+ * Each time when a new block allocation is need, first try to allocate from
+ * its own reservation.  If it does not have a reservation window, instead of
+ * looking for a free bit on bitmap first, then look up the reservation list to
+ * see if it is inside somebody else's reservation window, we try to allocate a
+ * reservation window for it starting from the goal first. Then do the block
+ * allocation within the reservation window.
+ *
+ * This will avoid keeping on searching the reservation list again and
+ * again when somebody is looking for a free block (without
+ * reservation), and there are lots of free blocks, but they are all
+ * being reserved.
+ *
+ * We use a red-black tree for the per-filesystem reservation list.
+ */
+static ext2_grpblk_t
+ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
+         struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
+         struct ext2_reserve_window_node * my_rsv,
+         unsigned long *count)
+{
+   ext2_fsblk_t group_first_block, group_last_block;
+   ext2_grpblk_t ret = 0;
+   unsigned long num = *count;
+
+   /*
+    * we don't deal with reservation when
+    * filesystem is mounted without reservation
+    * or the file is not a regular file
+    * or last attempt to allocate a block with reservation turned on failed
+    */
+   if (my_rsv == NULL) {
+      return ext2_try_to_allocate(sb, group, bitmap_bh,
+                  grp_goal, count, NULL);
+   }
+   /*
+    * grp_goal is a group relative block number (if there is a goal)
+    * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
+    * first block is a filesystem wide block number
+    * first block is the block number of the first block in this group
+    */
+   group_first_block = ext2_group_first_block_no(sb, group);
+   group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
+
+   /*
+    * Basically we will allocate a new block from inode's reservation
+    * window.
+    *
+    * We need to allocate a new reservation window, if:
+    * a) inode does not have a reservation window; or
+    * b) last attempt to allocate a block from existing reservation
+    *    failed; or
+    * c) we come here with a goal and with a reservation window
+    *
+    * We do not need to allocate a new reservation window if we come here
+    * at the beginning with a goal and the goal is inside the window, or
+    * we don't have a goal but already have a reservation window.
+    * then we could go to allocate from the reservation window directly.
+    */
+   while (1) {
+      if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
+         !goal_in_my_reservation(&my_rsv->rsv_window,
+                  grp_goal, group, sb)) {
+         if (my_rsv->rsv_goal_size < *count)
+            my_rsv->rsv_goal_size = *count;
+         ret = alloc_new_reservation(my_rsv, grp_goal, sb,
+                     group, bitmap_bh);
+         if (ret < 0)
+            break;         /* failed */
+
+         if (!goal_in_my_reservation(&my_rsv->rsv_window,
+                     grp_goal, group, sb))
+            grp_goal = -1;
+      } else if (grp_goal >= 0) {
+         int curr = my_rsv->rsv_end -
+               (grp_goal + group_first_block) + 1;
+
+         if (curr < *count)
+            try_to_extend_reservation(my_rsv, sb,
+                     *count - curr);
+      }
+
+      if ((my_rsv->rsv_start > group_last_block) ||
+            (my_rsv->rsv_end < group_first_block)) {
+         rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
+         BUG();
+      }
+      ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
+                  &num, &my_rsv->rsv_window);
+      if (ret >= 0) {
+         my_rsv->rsv_alloc_hit += num;
+         *count = num;
+         break;            /* succeed */
+      }
+      num = *count;
+   }
+   return ret;
+}
+
+/**
+ * ext2_has_free_blocks()
+ * @sbi:      in-core super block structure.
+ *
+ * Check if filesystem has at least 1 free block available for allocation.
+ */
+static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
+{
+   ext2_fsblk_t free_blocks, root_blocks;
+
+   free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
+   root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
+   if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
+      sbi->s_resuid != current->fsuid &&
+      (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
+      return 0;
+   }
+   return 1;
 }
 
 /*
- * ext2_new_block uses a goal block to assist allocation.  If the goal is
+ * ext2_new_blocks() -- core block(s) allocation function
+ * @inode:      file inode
+ * @goal:      given target block(filesystem wide)
+ * @count:      target number of blocks to allocate
+ * @errp:      error code
+ *
+ * ext2_new_blocks uses a goal block to assist allocation.  If the goal is
  * free, or there is a free block within 32 blocks of the goal, that block
  * is allocated.  Otherwise a forward search is made for a free block; within 
  * each block group the search first looks for an entire free byte in the block
  * bitmap, and then for any free bit if that fails.
  * This function also updates quota and i_blocks field.
  */
-int ext2_new_block(struct inode *inode, unsigned long goal,
-         u32 *prealloc_count, u32 *prealloc_block, int *err)
+ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
+          unsigned long *count, int *errp)
 {
    struct buffer_head *bitmap_bh = NULL;
-   struct buffer_head *gdp_bh;   /* bh2 */
-   struct ext2_group_desc *desc;
-   int group_no;         /* i */
-   int ret_block;         /* j */
-   int group_idx;         /* k */
-   int target_block;      /* tmp */
-   int block = 0;
-   struct super_block *sb = inode->i_sb;
-   struct ext2_sb_info *sbi = EXT2_SB(sb);
-   struct ext2_super_block *es = sbi->s_es;
-   unsigned group_size = EXT2_BLOCKS_PER_GROUP(sb);
-   unsigned prealloc_goal = es->s_prealloc_blocks;
-   unsigned group_alloc = 0, es_alloc, dq_alloc;
-   int nr_scanned_groups;
-
-   if (!prealloc_goal--)
-      prealloc_goal = EXT2_DEFAULT_PREALLOC_BLOCKS - 1;
-   if (!prealloc_count || *prealloc_count)
-      prealloc_goal = 0;
-
-   if (DQUOT_ALLOC_BLOCK(inode, 1)) {
-      *err = -EDQUOT;
-      goto out;
+   struct buffer_head *gdp_bh;
+   int group_no;
+   int goal_group;
+   ext2_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
+   ext2_grpblk_t grp_alloc_blk;   /* blockgroup-relative allocated block*/
+   ext2_fsblk_t ret_block;      /* filesyetem-wide allocated block */
+   int bgi;         /* blockgroup iteration index */
+   int performed_allocation = 0;
+   ext2_grpblk_t free_blocks;   /* number of free blocks in a group */
+   struct super_block *sb;
+   struct ext2_group_desc *gdp;
+   struct ext2_super_block *es;
+   struct ext2_sb_info *sbi;
+   struct ext2_reserve_window_node *my_rsv = NULL;
+   struct ext2_block_alloc_info *block_i;
+   unsigned short windowsz = 0;
+   unsigned long ngroups;
+   unsigned long num = *count;
+
+   *errp = -ENOSPC;
+   sb = inode->i_sb;
+   if (!sb) {
+      printk("ext2_new_blocks: nonexistent device");
+      return 0;
    }
 
-   while (prealloc_goal && DQUOT_PREALLOC_BLOCK(inode, prealloc_goal))
-      prealloc_goal--;
+   /*
+    * Check quota for allocation of this block.
+    */
+   if (DQUOT_ALLOC_BLOCK(inode, num)) {
+      *errp = -EDQUOT;
+      return 0;
+   }
 
-   dq_alloc = prealloc_goal + 1;
-   es_alloc = reserve_blocks(sb, dq_alloc);
-   if (!es_alloc) {
-      *err = -ENOSPC;
-      goto out_dquot;
+   sbi = EXT2_SB(sb);
+   es = EXT2_SB(sb)->s_es;
+   ext2_debug("goal=%lu.\n", goal);
+   /*
+    * Allocate a block from reservation only when
+    * filesystem is mounted with reservation(default,-o reservation), and
+    * it's a regular file, and
+    * the desired window size is greater than 0 (One could use ioctl
+    * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
+    * reservation on that particular file)
+    */
+   block_i = EXT2_I(inode)->i_block_alloc_info;
+   if (block_i) {
+      windowsz = block_i->rsv_window_node.rsv_goal_size;
+      if (windowsz > 0)
+         my_rsv = &block_i->rsv_window_node;
    }
 
-   ext2_debug ("goal=%lu.\n", goal);
+   if (!ext2_has_free_blocks(sbi)) {
+      *errp = -ENOSPC;
+      goto out;
+   }
 
+   /*
+    * First, test whether the goal block is free.
+    */
    if (goal < le32_to_cpu(es->s_first_data_block) ||
        goal >= le32_to_cpu(es->s_blocks_count))
       goal = le32_to_cpu(es->s_first_data_block);
-   group_no = (goal - le32_to_cpu(es->s_first_data_block)) / group_size;
-   desc = ext2_get_group_desc (sb, group_no, &gdp_bh);
-   if (!desc) {
-      /*
-       * gdp_bh may still be uninitialised.  But group_release_blocks
-       * will not touch it because group_alloc is zero.
-       */
+   group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
+         EXT2_BLOCKS_PER_GROUP(sb);
+   goal_group = group_no;
+retry_alloc:
+   gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
+   if (!gdp)
       goto io_error;
-   }
 
-   group_alloc = group_reserve_blocks(sbi, group_no, desc,
-               gdp_bh, es_alloc);
-   if (group_alloc) {
-      ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
-               group_size);
-      brelse(bitmap_bh);
+   free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
+   /*
+    * if there is not enough free blocks to make a new resevation
+    * turn off reservation for this allocation
+    */
+   if (my_rsv && (free_blocks < windowsz)
+      && (rsv_is_empty(&my_rsv->rsv_window)))
+      my_rsv = NULL;
+
+   if (free_blocks > 0) {
+      grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
+            EXT2_BLOCKS_PER_GROUP(sb));
       bitmap_bh = read_block_bitmap(sb, group_no);
       if (!bitmap_bh)
          goto io_error;
-      
-      ext2_debug("goal is at %d:%d.\n", group_no, ret_block);
-
-      ret_block = grab_block(sb_bgl_lock(sbi, group_no),
-            bitmap_bh->b_data, group_size, ret_block);
-      if (ret_block >= 0)
-         goto got_block;
-      group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc);
-      group_alloc = 0;
+      grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
+               bitmap_bh, grp_target_blk,
+               my_rsv, &num);
+      if (grp_alloc_blk >= 0)
+         goto allocated;
    }
 
-   ext2_debug ("Bit not found in block group %d.\n", group_no);
+   ngroups = EXT2_SB(sb)->s_groups_count;
+   smp_rmb();
 
    /*
     * Now search the rest of the groups.  We assume that 
-    * i and desc correctly point to the last group visited.
+    * i and gdp correctly point to the last group visited.
     */
-   nr_scanned_groups = 0;
-retry:
-   for (group_idx = 0; !group_alloc &&
-         group_idx < sbi->s_groups_count; group_idx++) {
+   for (bgi = 0; bgi < ngroups; bgi++) {
       group_no++;
-      if (group_no >= sbi->s_groups_count)
+      if (group_no >= ngroups)
          group_no = 0;
-      desc = ext2_get_group_desc(sb, group_no, &gdp_bh);
-      if (!desc)
+      gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
+      if (!gdp)
          goto io_error;
-      group_alloc = group_reserve_blocks(sbi, group_no, desc,
-                  gdp_bh, es_alloc);
-   }
-   if (!group_alloc) {
-      *err = -ENOSPC;
-      goto out_release;
-   }
-   brelse(bitmap_bh);
-   bitmap_bh = read_block_bitmap(sb, group_no);
-   if (!bitmap_bh)
-      goto io_error;
 
-   ret_block = grab_block(sb_bgl_lock(sbi, group_no), bitmap_bh->b_data,
-            group_size, 0);
-   if (ret_block < 0) {
+      free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
       /*
-       * If a free block counter is corrupted we can loop inifintely.
-       * Detect that here.
+       * skip this group if the number of
+       * free blocks is less than half of the reservation
+       * window size.
        */
-      nr_scanned_groups++;
-      if (nr_scanned_groups > 2 * sbi->s_groups_count) {
-         ext2_error(sb, "ext2_new_block",
-            "corrupted free blocks counters");
+      if (free_blocks <= (windowsz/2))
+         continue;
+
+      brelse(bitmap_bh);
+      bitmap_bh = read_block_bitmap(sb, group_no);
+      if (!bitmap_bh)
          goto io_error;
-      }
       /*
-       * Someone else grabbed the last free block in this blockgroup
-       * before us.  Retry the scan.
+       * try to allocate block(s) from this group, without a goal(-1).
        */
-      group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc);
-      group_alloc = 0;
-      goto retry;
+      grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
+               bitmap_bh, -1, my_rsv, &num);
+      if (grp_alloc_blk >= 0)
+         goto allocated;
    }
+   /*
+    * We may end up a bogus ealier ENOSPC error due to
+    * filesystem is "full" of reservations, but
+    * there maybe indeed free blocks avaliable on disk
+    * In this case, we just forget about the reservations
+    * just do block allocation as without reservations.
+    */
+   if (my_rsv) {
+      my_rsv = NULL;
+      windowsz = 0;
+      group_no = goal_group;
+      goto retry_alloc;
+   }
+   /* No space left on the device */
+   *errp = -ENOSPC;
+   goto out;
+
+allocated:
 
-got_block:
    ext2_debug("using block group %d(%d)\n",
-      group_no, desc->bg_free_blocks_count);
+         group_no, gdp->bg_free_blocks_count);
 
-   target_block = ret_block + group_no * group_size +
-         le32_to_cpu(es->s_first_data_block);
+   ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
 
-   if (target_block == le32_to_cpu(desc->bg_block_bitmap) ||
-       target_block == le32_to_cpu(desc->bg_inode_bitmap) ||
-       in_range(target_block, le32_to_cpu(desc->bg_inode_table),
-            sbi->s_itb_per_group))
-      ext2_error (sb, "ext2_new_block",
+   if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
+       in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
+       in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
+            EXT2_SB(sb)->s_itb_per_group) ||
+       in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
+            EXT2_SB(sb)->s_itb_per_group))
+      ext2_error(sb, "ext2_new_blocks",
              "Allocating block in system zone - "
-             "block = %u", target_block);
+             "blocks from "E2FSBLK", length %lu",
+             ret_block, num);
 
-   if (target_block >= le32_to_cpu(es->s_blocks_count)) {
-      ext2_error (sb, "ext2_new_block",
-             "block(%d) >= blocks count(%d) - "
+   performed_allocation = 1;
+
+   if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
+      ext2_error(sb, "ext2_new_blocks",
+             "block("E2FSBLK") >= blocks count(%d) - "
              "block_group = %d, es == %p ", ret_block,
          le32_to_cpu(es->s_blocks_count), group_no, es);
-      goto io_error;
+      goto out;
    }
-   block = target_block;
-
-   /* OK, we _had_ allocated something */
-   ext2_debug("found bit %d\n", ret_block);
-
-   dq_alloc--;
-   es_alloc--;
-   group_alloc--;
 
-   /*
-    * Do block preallocation now if required.
-    */
-   write_lock(&EXT2_I(inode)->i_meta_lock);
-   if (group_alloc && !*prealloc_count) {
-      unsigned n;
-
-      for (n = 0; n < group_alloc && ++ret_block < group_size; n++) {
-         if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group_no),
-                  ret_block,
-                  (void*) bitmap_bh->b_data))
-             break;
-      }
-      *prealloc_block = block + 1;
-      *prealloc_count = n;
-      es_alloc -= n;
-      dq_alloc -= n;
-      group_alloc -= n;
-   }
-   write_unlock(&EXT2_I(inode)->i_meta_lock);
+   group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
+   percpu_counter_sub(&sbi->s_freeblocks_counter, num);
 
    mark_buffer_dirty(bitmap_bh);
    if (sb->s_flags & MS_SYNCHRONOUS)
       sync_dirty_buffer(bitmap_bh);
 
-   ext2_debug ("allocating block %d. ", block);
+   *errp = 0;
+   brelse(bitmap_bh);
+   DQUOT_FREE_BLOCK(inode, *count-num);
+   *count = num;
+   return ret_block;
 
-   *err = 0;
-out_release:
-   group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc);
-   release_blocks(sb, es_alloc);
-out_dquot:
-   DQUOT_FREE_BLOCK(inode, dq_alloc);
+io_error:
+   *errp = -EIO;
 out:
+   /*
+    * Undo the block allocation
+    */
+   if (!performed_allocation)
+      DQUOT_FREE_BLOCK(inode, *count);
    brelse(bitmap_bh);
-   return block;
+   return 0;
+}
 
-io_error:
-   *err = -EIO;
-   goto out_release;
+ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
+{
+   unsigned long count = 1;
+
+   return ext2_new_blocks(inode, goal, &count, errp);
 }
 
 #ifdef EXT2FS_DEBUG
 
-static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
+static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
 
 unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
 {
@@ -583,14 +1422,6 @@ unsigned long ext2_count_free_blocks (struct super_block * sb)
 #endif
 }
 
-static inline int
-block_in_use(unsigned long block, struct super_block *sb, unsigned char *map)
-{
-   return ext2_test_bit ((block -
-      le32_to_cpu(EXT2_SB(sb)->s_es->s_first_data_block)) %
-          EXT2_BLOCKS_PER_GROUP(sb), map);
-}
-
 static inline int test_root(int a, int b)
 {
    int num = b;