/*
   *  linux/fs/ext3/balloc.c
   *
   * Copyright (C) 1992, 1993, 1994, 1995
   * Remy Card (card@masi.ibp.fr)
   * Laboratoire MASI - Institut Blaise Pascal
   * Universite Pierre et Marie Curie (Paris VI)
   *
   *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
   *  Big-endian to little-endian byte-swapping/bitmaps by
   *        David S. Miller (davem@caip.rutgers.edu), 1995
   */

  #include <linux/time.h>

  #include <linux/capability.h>

  #include <linux/fs.h>

  #include <linux/slab.h>

  #include <linux/jbd.h>
  #include <linux/ext3_fs.h>
  #include <linux/ext3_jbd.h>
  #include <linux/quotaops.h>
  #include <linux/buffer_head.h>

  #include <linux/blkdev.h>

  #include <trace/events/ext3.h>

  
  /*
   * balloc.c contains the blocks allocation and deallocation routines
   */
  
  /*
   * The free blocks are managed by bitmaps.  A file system contains several
   * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
   * block for inodes, N blocks for the inode table and data blocks.
   *
   * The file system contains group descriptors which are located after the
   * super block.  Each descriptor contains the number of the bitmap block and
   * the free blocks count in the block.  The descriptors are loaded in memory

   * when a file system is mounted (see ext3_fill_super).

   */
  
  
  #define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)

  /*
   * Calculate the block group number and offset, given a block number
   */
  static void ext3_get_group_no_and_offset(struct super_block *sb,
  	ext3_fsblk_t blocknr, unsigned long *blockgrpp, ext3_grpblk_t *offsetp)
  {
  	struct ext3_super_block *es = EXT3_SB(sb)->s_es;
  
  	blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  	if (offsetp)
  		*offsetp = blocknr % EXT3_BLOCKS_PER_GROUP(sb);
  	if (blockgrpp)
  		*blockgrpp = blocknr / EXT3_BLOCKS_PER_GROUP(sb);
  }

  /**
   * ext3_get_group_desc() -- load group descriptor from disk

   * @sb:			super block

   * @block_group:	given block group
   * @bh:			pointer to the buffer head to store the block
   *			group descriptor
   */

  struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  					     unsigned int block_group,
  					     struct buffer_head ** bh)
  {
  	unsigned long group_desc;
  	unsigned long offset;
  	struct ext3_group_desc * desc;
  	struct ext3_sb_info *sbi = EXT3_SB(sb);
  
  	if (block_group >= sbi->s_groups_count) {
  		ext3_error (sb, "ext3_get_group_desc",
  			    "block_group >= groups_count - "
  			    "block_group = %d, groups_count = %lu",
  			    block_group, sbi->s_groups_count);
  
  		return NULL;
  	}
  	smp_rmb();
  
  	group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  	offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  	if (!sbi->s_group_desc[group_desc]) {
  		ext3_error (sb, "ext3_get_group_desc",
  			    "Group descriptor not loaded - "
  			    "block_group = %d, group_desc = %lu, desc = %lu",
  			     block_group, group_desc, offset);
  		return NULL;
  	}
  
  	desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  	if (bh)
  		*bh = sbi->s_group_desc[group_desc];
  	return desc + offset;
  }

  static int ext3_valid_block_bitmap(struct super_block *sb,
  					struct ext3_group_desc *desc,
  					unsigned int block_group,
  					struct buffer_head *bh)
  {
  	ext3_grpblk_t offset;
  	ext3_grpblk_t next_zero_bit;
  	ext3_fsblk_t bitmap_blk;
  	ext3_fsblk_t group_first_block;
  
  	group_first_block = ext3_group_first_block_no(sb, block_group);
  
  	/* check whether block bitmap block number is set */
  	bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
  	offset = bitmap_blk - group_first_block;
  	if (!ext3_test_bit(offset, bh->b_data))
  		/* bad block bitmap */
  		goto err_out;
  
  	/* check whether the inode bitmap block number is set */
  	bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
  	offset = bitmap_blk - group_first_block;
  	if (!ext3_test_bit(offset, bh->b_data))
  		/* bad block bitmap */
  		goto err_out;
  
  	/* check whether the inode table block number is set */
  	bitmap_blk = le32_to_cpu(desc->bg_inode_table);
  	offset = bitmap_blk - group_first_block;
  	next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
  				offset + EXT3_SB(sb)->s_itb_per_group,
  				offset);
  	if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
  		/* good bitmap for inode tables */
  		return 1;
  
  err_out:

  	ext3_error(sb, __func__,

  			"Invalid block bitmap - "
  			"block_group = %d, block = %lu",
  			block_group, bitmap_blk);
  	return 0;
  }

  /**
   * read_block_bitmap()
   * @sb:			super block
   * @block_group:	given block group
   *

   * Read the bitmap for a given block_group,and validate the
   * bits for block/inode/inode tables are set in the bitmaps

   *
   * Return buffer_head on success or NULL in case of failure.
   */
  static struct buffer_head *
  read_block_bitmap(struct super_block *sb, unsigned int block_group)
  {
  	struct ext3_group_desc * desc;
  	struct buffer_head * bh = NULL;

  	ext3_fsblk_t bitmap_blk;

  	desc = ext3_get_group_desc(sb, block_group, NULL);

  	if (!desc)

  		return NULL;

  	trace_ext3_read_block_bitmap(sb, block_group);

  	bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
  	bh = sb_getblk(sb, bitmap_blk);
  	if (unlikely(!bh)) {

  		ext3_error(sb, __func__,

  			    "Cannot read block bitmap - "
  			    "block_group = %d, block_bitmap = %u",
  			    block_group, le32_to_cpu(desc->bg_block_bitmap));

  		return NULL;
  	}
  	if (likely(bh_uptodate_or_lock(bh)))
  		return bh;
  
  	if (bh_submit_read(bh) < 0) {
  		brelse(bh);

  		ext3_error(sb, __func__,

  			    "Cannot read block bitmap - "
  			    "block_group = %d, block_bitmap = %u",
  			    block_group, le32_to_cpu(desc->bg_block_bitmap));
  		return NULL;
  	}

  	ext3_valid_block_bitmap(sb, desc, block_group, bh);
  	/*
  	 * file system mounted not to panic on error, continue with corrupt
  	 * bitmap
  	 */

  	return bh;

  }
  /*
   * 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 ext3_reserve_window_node *rsv, *prev;
  	int bad;
  
  restart:
  	n = rb_first(root);
  	bad = 0;
  	prev = NULL;
  
  	printk("Block Allocation Reservation Windows Map (%s):
  ", fn);
  	while (n) {

  		rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);

  		if (verbose)
  			printk("reservation window 0x%p "

  			       "start:  %lu, end:  %lu
  ",

  			       rsv, rsv->rsv_start, rsv->rsv_end);
  		if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
  			printk("Bad reservation %p (start >= end)
  ",
  			       rsv);
  			bad = 1;
  		}
  		if (prev && prev->rsv_end >= rsv->rsv_start) {
  			printk("Bad reservation %p (prev->end >= start)
  ",
  			       rsv);
  			bad = 1;
  		}
  		if (bad) {
  			if (!verbose) {
  				printk("Restarting reservation walk in verbose mode
  ");
  				verbose = 1;
  				goto restart;
  			}
  		}
  		n = rb_next(n);
  		prev = rsv;
  	}
  	printk("Window map complete.
  ");

  	BUG_ON(bad);

  }
  #define rsv_window_dump(root, verbose) \

  	__rsv_window_dump((root), (verbose), __func__)

  #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 ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,

  			unsigned int group, struct super_block * sb)
  {

  	ext3_fsblk_t group_first_block, group_last_block;

  	group_first_block = ext3_group_first_block_no(sb, group);

  	group_last_block = group_first_block + (EXT3_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 ext3_reserve_window_node *

  search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)

  {
  	struct rb_node *n = root->rb_node;
  	struct ext3_reserve_window_node *rsv;
  
  	if (!n)
  		return NULL;
  
  	do {
  		rsv = rb_entry(n, struct ext3_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 ext3_reserve_window_node, rsv_node);
  	}
  	return rsv;
  }

  /**
   * ext3_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 hold.
   */

  void ext3_rsv_window_add(struct super_block *sb,
  		    struct ext3_reserve_window_node *rsv)
  {
  	struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
  	struct rb_node *node = &rsv->rsv_node;

  	ext3_fsblk_t start = rsv->rsv_start;

  
  	struct rb_node ** p = &root->rb_node;
  	struct rb_node * parent = NULL;
  	struct ext3_reserve_window_node *this;

  	trace_ext3_rsv_window_add(sb, rsv);

  	while (*p)
  	{
  		parent = *p;
  		this = rb_entry(parent, struct ext3_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);
  }

  /**
   * ext3_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 hold.
   */

  static void rsv_window_remove(struct super_block *sb,
  			      struct ext3_reserve_window_node *rsv)
  {
  	rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
  	rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
  	rsv->rsv_alloc_hit = 0;
  	rb_erase(&rsv->rsv_node, &EXT3_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 EXT3_RESERVE_WINDOW_NOT_ALLOCATED.
   */

  static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
  {
  	/* a valid reservation end block could not be 0 */

  	return rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED;

  }

  
  /**
   * ext3_init_block_alloc_info()
   * @inode:		file inode structure
   *
   * Allocate and initialize the	reservation window structure, and
   * link the window to the ext3 inode structure at last
   *
   * The reservation window structure is only dynamically allocated
   * and linked to ext3 inode the first time the open file
   * needs a new block. So, before every ext3_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 ext3_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 call this function.
   */

  void ext3_init_block_alloc_info(struct inode *inode)
  {
  	struct ext3_inode_info *ei = EXT3_I(inode);

  	struct ext3_block_alloc_info *block_i;

  	struct super_block *sb = inode->i_sb;
  
  	block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
  	if (block_i) {
  		struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
  
  		rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
  		rsv->rsv_end = EXT3_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 = EXT3_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;
  }

  /**
   * ext3_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:
   *	ext3_release_file(): last writer close the file
   *	ext3_clear_inode(): last iput(), when nobody link to this file.
   *	ext3_truncate(): when the block indirect map is about to change.
   *
   */

  void ext3_discard_reservation(struct inode *inode)
  {
  	struct ext3_inode_info *ei = EXT3_I(inode);
  	struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
  	struct ext3_reserve_window_node *rsv;
  	spinlock_t *rsv_lock = &EXT3_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)) {
  			trace_ext3_discard_reservation(inode, rsv);

  			rsv_window_remove(inode->i_sb, rsv);

  		}

  		spin_unlock(rsv_lock);
  	}
  }

  /**
   * ext3_free_blocks_sb() -- Free given blocks and update quota
   * @handle:			handle to this transaction
   * @sb:				super block
   * @block:			start physcial block to free
   * @count:			number of blocks to free
   * @pdquot_freed_blocks:	pointer to quota
   */

  void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,

  			 ext3_fsblk_t block, unsigned long count,
  			 unsigned long *pdquot_freed_blocks)

  {
  	struct buffer_head *bitmap_bh = NULL;
  	struct buffer_head *gd_bh;
  	unsigned long block_group;

  	ext3_grpblk_t bit;

  	unsigned long i;
  	unsigned long overflow;
  	struct ext3_group_desc * desc;
  	struct ext3_super_block * es;
  	struct ext3_sb_info *sbi;
  	int err = 0, ret;

  	ext3_grpblk_t group_freed;

  
  	*pdquot_freed_blocks = 0;
  	sbi = EXT3_SB(sb);
  	es = sbi->s_es;
  	if (block < le32_to_cpu(es->s_first_data_block) ||
  	    block + count < block ||
  	    block + count > le32_to_cpu(es->s_blocks_count)) {
  		ext3_error (sb, "ext3_free_blocks",
  			    "Freeing blocks not in datazone - "

  			    "block = "E3FSBLK", count = %lu", block, count);

  		goto error_return;
  	}
  
  	ext3_debug ("freeing block(s) %lu-%lu
  ", block, block + count - 1);
  
  do_more:
  	overflow = 0;
  	block_group = (block - le32_to_cpu(es->s_first_data_block)) /
  		      EXT3_BLOCKS_PER_GROUP(sb);
  	bit = (block - le32_to_cpu(es->s_first_data_block)) %
  		      EXT3_BLOCKS_PER_GROUP(sb);
  	/*
  	 * Check to see if we are freeing blocks across a group
  	 * boundary.
  	 */
  	if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
  		overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
  		count -= overflow;
  	}
  	brelse(bitmap_bh);
  	bitmap_bh = read_block_bitmap(sb, block_group);
  	if (!bitmap_bh)
  		goto error_return;
  	desc = ext3_get_group_desc (sb, block_group, &gd_bh);
  	if (!desc)
  		goto error_return;
  
  	if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
  	    in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
  	    in_range (block, le32_to_cpu(desc->bg_inode_table),
  		      sbi->s_itb_per_group) ||
  	    in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),

  		      sbi->s_itb_per_group)) {

  		ext3_error (sb, "ext3_free_blocks",
  			    "Freeing blocks in system zones - "

  			    "Block = "E3FSBLK", count = %lu",

  			    block, count);

  		goto error_return;
  	}

  
  	/*
  	 * We are about to start releasing blocks in the bitmap,
  	 * so we need undo access.
  	 */
  	/* @@@ check errors */
  	BUFFER_TRACE(bitmap_bh, "getting undo access");
  	err = ext3_journal_get_undo_access(handle, bitmap_bh);
  	if (err)
  		goto error_return;
  
  	/*
  	 * We are about to modify some metadata.  Call the journal APIs
  	 * to unshare ->b_data if a currently-committing transaction is
  	 * using it
  	 */
  	BUFFER_TRACE(gd_bh, "get_write_access");
  	err = ext3_journal_get_write_access(handle, gd_bh);
  	if (err)
  		goto error_return;
  
  	jbd_lock_bh_state(bitmap_bh);
  
  	for (i = 0, group_freed = 0; i < count; i++) {
  		/*
  		 * An HJ special.  This is expensive...
  		 */
  #ifdef CONFIG_JBD_DEBUG
  		jbd_unlock_bh_state(bitmap_bh);
  		{
  			struct buffer_head *debug_bh;
  			debug_bh = sb_find_get_block(sb, block + i);
  			if (debug_bh) {
  				BUFFER_TRACE(debug_bh, "Deleted!");
  				if (!bh2jh(bitmap_bh)->b_committed_data)
  					BUFFER_TRACE(debug_bh,

  						"No committed data in bitmap");

  				BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
  				__brelse(debug_bh);
  			}
  		}
  		jbd_lock_bh_state(bitmap_bh);
  #endif
  		if (need_resched()) {
  			jbd_unlock_bh_state(bitmap_bh);
  			cond_resched();
  			jbd_lock_bh_state(bitmap_bh);
  		}
  		/* @@@ This prevents newly-allocated data from being
  		 * freed and then reallocated within the same

  		 * transaction.
  		 *

  		 * Ideally we would want to allow that to happen, but to
  		 * do so requires making journal_forget() capable of
  		 * revoking the queued write of a data block, which
  		 * implies blocking on the journal lock.  *forget()
  		 * cannot block due to truncate races.
  		 *
  		 * Eventually we can fix this by making journal_forget()
  		 * return a status indicating whether or not it was able
  		 * to revoke the buffer.  On successful revoke, it is
  		 * safe not to set the allocation bit in the committed
  		 * bitmap, because we know that there is no outstanding
  		 * activity on the buffer any more and so it is safe to

  		 * reallocate it.

  		 */
  		BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
  		J_ASSERT_BH(bitmap_bh,
  				bh2jh(bitmap_bh)->b_committed_data != NULL);
  		ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
  				bh2jh(bitmap_bh)->b_committed_data);
  
  		/*
  		 * We clear the bit in the bitmap after setting the committed
  		 * data bit, because this is the reverse order to that which
  		 * the allocator uses.
  		 */
  		BUFFER_TRACE(bitmap_bh, "clear bit");
  		if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
  						bit + i, bitmap_bh->b_data)) {
  			jbd_unlock_bh_state(bitmap_bh);

  			ext3_error(sb, __func__,

  				"bit already cleared for block "E3FSBLK,
  				 block + i);

  			jbd_lock_bh_state(bitmap_bh);
  			BUFFER_TRACE(bitmap_bh, "bit already cleared");
  		} else {
  			group_freed++;
  		}
  	}
  	jbd_unlock_bh_state(bitmap_bh);
  
  	spin_lock(sb_bgl_lock(sbi, block_group));

  	le16_add_cpu(&desc->bg_free_blocks_count, group_freed);

  	spin_unlock(sb_bgl_lock(sbi, block_group));

  	percpu_counter_add(&sbi->s_freeblocks_counter, count);

  
  	/* We dirtied the bitmap block */
  	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
  	err = ext3_journal_dirty_metadata(handle, bitmap_bh);
  
  	/* And the group descriptor block */
  	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
  	ret = ext3_journal_dirty_metadata(handle, gd_bh);
  	if (!err) err = ret;
  	*pdquot_freed_blocks += group_freed;
  
  	if (overflow && !err) {
  		block += count;
  		count = overflow;
  		goto do_more;
  	}

  error_return:
  	brelse(bitmap_bh);
  	ext3_std_error(sb, err);
  	return;
  }

  /**
   * ext3_free_blocks() -- Free given blocks and update quota
   * @handle:		handle for this transaction
   * @inode:		inode
   * @block:		start physical block to free
   * @count:		number of blocks to count
   */

  void ext3_free_blocks(handle_t *handle, struct inode *inode,

  			ext3_fsblk_t block, unsigned long count)

  {

  	struct super_block *sb = inode->i_sb;

  	unsigned long dquot_freed_blocks;

  	trace_ext3_free_blocks(inode, block, count);

  	ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
  	if (dquot_freed_blocks)

  		dquot_free_block(inode, dquot_freed_blocks);

  	return;
  }

  /**
   * ext3_test_allocatable()
   * @nr:			given allocation block group
   * @bh:			bufferhead contains the bitmap of the given block group
   *

   * 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.
   */

  static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)

  {
  	int ret;
  	struct journal_head *jh = bh2jh(bh);
  
  	if (ext3_test_bit(nr, bh->b_data))
  		return 0;
  
  	jbd_lock_bh_state(bh);
  	if (!jh->b_committed_data)
  		ret = 1;
  	else
  		ret = !ext3_test_bit(nr, jh->b_committed_data);
  	jbd_unlock_bh_state(bh);
  	return ret;
  }

  /**
   * 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 alternately through the actual
   * bitmap on disk and the last-committed copy in journal, until we find a
   * bit free in both bitmaps.
   */

  static ext3_grpblk_t
  bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
  					ext3_grpblk_t maxblocks)

  {

  	ext3_grpblk_t next;

  	struct journal_head *jh = bh2jh(bh);

  	while (start < maxblocks) {
  		next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
  		if (next >= maxblocks)
  			return -1;
  		if (ext3_test_allocatable(next, bh))
  			return next;
  		jbd_lock_bh_state(bh);
  		if (jh->b_committed_data)
  			start = ext3_find_next_zero_bit(jh->b_committed_data,

  							maxblocks, next);

  		jbd_unlock_bh_state(bh);
  	}
  	return -1;
  }

  /**
   * 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 honor both the bitmap and

   * its last-committed copy (if that exists), and 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 ext3_grpblk_t
  find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
  			ext3_grpblk_t maxblocks)

  {

  	ext3_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.
  		 *
  		 * end_goal is more or less random, but it has to be
  		 * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
  		 * next 64-bit boundary is simple..
  		 */

  		ext3_grpblk_t end_goal = (start + 63) & ~63;

  		if (end_goal > maxblocks)
  			end_goal = maxblocks;
  		here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
  		if (here < end_goal && ext3_test_allocatable(here, bh))
  			return here;
  		ext3_debug("Bit not found near goal
  ");
  	}
  
  	here = start;
  	if (here < 0)
  		here = 0;

  	p = bh->b_data + (here >> 3);

  	r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));

  	next = (r - bh->b_data) << 3;

  
  	if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
  		return next;
  
  	/*
  	 * The bitmap search --- search forward alternately through the actual
  	 * bitmap and the last-committed copy until we find a bit free in
  	 * both
  	 */
  	here = bitmap_search_next_usable_block(here, bh, maxblocks);
  	return here;
  }

  /**
   * claim_block()

   * @lock:		the spin lock for this block group

   * @block:		the free block (group relative) to allocate

   * @bh:			the buffer_head contains the block group bitmap

   *

   * We think we can allocate this block in this bitmap.  Try to set the bit.
   * If that succeeds then check that nobody has allocated and then freed the
   * block since we saw that is was not marked in b_committed_data.  If it _was_
   * allocated and freed then clear the bit in the bitmap again and return
   * zero (failure).
   */
  static inline int

  claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)

  {
  	struct journal_head *jh = bh2jh(bh);
  	int ret;
  
  	if (ext3_set_bit_atomic(lock, block, bh->b_data))
  		return 0;
  	jbd_lock_bh_state(bh);
  	if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
  		ext3_clear_bit_atomic(lock, block, bh->b_data);
  		ret = 0;
  	} else {
  		ret = 1;
  	}
  	jbd_unlock_bh_state(bh);
  	return ret;
  }

  /**
   * ext3_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.  In that case we must release write access to the old one via
   * ext3_journal_release_buffer(), else we'll run out of credits.
   */

  static ext3_grpblk_t

  ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,

  			struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,

  			unsigned long *count, struct ext3_reserve_window *my_rsv)

  {

  	ext3_fsblk_t group_first_block;
  	ext3_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 = ext3_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 > EXT3_BLOCKS_PER_GROUP(sb))
  			/* reservation window crosses group boundary */
  			end = EXT3_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 = EXT3_BLOCKS_PER_GROUP(sb);
  	}
  
  	BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
  
  repeat:

  	if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
  		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 &&
  					ext3_test_allocatable(grp_goal - 1,

  								bitmap_bh);

  					i++, grp_goal--)

  				;
  		}
  	}

  	start = grp_goal;

  	if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group),
  		grp_goal, bitmap_bh)) {

  		/*
  		 * 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
  		&& ext3_test_allocatable(grp_goal, bitmap_bh)

  		&& claim_block(sb_bgl_lock(EXT3_SB(sb), group),
  				grp_goal, bitmap_bh)) {

  		num++;

  		grp_goal++;

  	}
  	*count = num;

  	return grp_goal - num;

  fail_access:

  	*count = num;

  	return -1;
  }
  
  /**

   *	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.
   *

   *	@my_rsv: the reservation window

   *

   *	@sb: the super block
   *
   *	@start_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 ext3_reserve_window_node *search_head,

  				struct ext3_reserve_window_node *my_rsv,

  				struct super_block * sb,
  				ext3_fsblk_t start_block,
  				ext3_fsblk_t last_block)

  {
  	struct rb_node *next;
  	struct ext3_reserve_window_node *rsv, *prev;

  	ext3_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)...
  		 */
  		if (cur > last_block)

  			return -1;		/* fail */

  
  		prev = rsv;
  		next = rb_next(&rsv->rsv_node);

  		rsv = rb_entry(next,struct ext3_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 available 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)
  		ext3_rsv_window_add(sb, my_rsv);
  
  	return 0;

  }
  
  /**

   *	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
   *

   *	@my_rsv: the reservation window

   *

   *	@grp_goal: The goal (group-relative).  It is where the search for a

   *		free reservable space should start from.

   *		if we have a grp_goal(grp_goal >0 ), then start from there,
   *		no grp_goal(grp_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 ext3_reserve_window_node *my_rsv,

  		ext3_grpblk_t grp_goal, struct super_block *sb,

  		unsigned int group, struct buffer_head *bitmap_bh)
  {
  	struct ext3_reserve_window_node *search_head;

  	ext3_fsblk_t group_first_block, group_end_block, start_block;
  	ext3_grpblk_t first_free_block;

  	struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
  	unsigned long size;

  	int ret;
  	spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;

  	group_first_block = ext3_group_first_block_no(sb, group);

  	group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);

  	if (grp_goal < 0)

  		start_block = group_first_block;
  	else

  		start_block = grp_goal + group_first_block;

  	trace_ext3_alloc_new_reservation(sb, start_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 > EXT3_MAX_RESERVE_BLOCKS)
  				size = EXT3_MAX_RESERVE_BLOCKS;
  			my_rsv->rsv_goal_size= size;
  		}
  	}

  
  	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.
  	 *
  	 * searching the first free bit on the block bitmap and copy of
  	 * last committed bitmap alternatively, until we found a allocatable
  	 * block. Search start 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) {
  		trace_ext3_reserved(sb, start_block, my_rsv);

  		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 ext3_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 ext3_new_blocks() tries to allocate blocks,
   */

  static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
  			struct super_block *sb, int size)
  {
  	struct ext3_reserve_window_node *next_rsv;
  	struct rb_node *next;
  	spinlock_t *rsv_lock = &EXT3_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 ext3_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);
  }

  /**
   * ext3_try_to_allocate_with_rsv()
   * @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

   * @my_rsv:		reservation window

   * @count:		target number of blocks to allocate

   * @errp:		pointer to store the error code
   *

   * 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 ext3_grpblk_t

  ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
  			unsigned int group, struct buffer_head *bitmap_bh,

  			ext3_grpblk_t grp_goal,
  			struct ext3_reserve_window_node * my_rsv,

  			unsigned long *count, int *errp)

  {

  	ext3_fsblk_t group_first_block, group_last_block;

  	ext3_grpblk_t ret = 0;

  	int fatal;

  	unsigned long num = *count;

  
  	*errp = 0;
  
  	/*
  	 * Make sure we use undo access for the bitmap, because it is critical
  	 * that we do the frozen_data COW on bitmap buffers in all cases even
  	 * if the buffer is in BJ_Forget state in the committing transaction.
  	 */
  	BUFFER_TRACE(bitmap_bh, "get undo access for new block");
  	fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
  	if (fatal) {
  		*errp = fatal;
  		return -1;
  	}
  
  	/*
  	 * 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 ) {

  		ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,

  						grp_goal, count, NULL);

  		goto out;
  	}

  	/*

  	 * grp_goal is a group relative block number (if there is a goal)

  	 * 0 <= grp_goal < EXT3_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 = ext3_group_first_block_no(sb, group);

  	group_last_block = group_first_block + (EXT3_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(&EXT3_SB(sb)->s_rsv_window_root, 1);

  			BUG();

  		}

  		ret = ext3_try_to_allocate(sb, handle, 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;

  	}
  out:
  	if (ret >= 0) {
  		BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
  					"bitmap block");
  		fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
  		if (fatal) {
  			*errp = fatal;
  			return -1;
  		}
  		return ret;
  	}
  
  	BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
  	ext3_journal_release_buffer(handle, bitmap_bh);
  	return ret;
  }

  /**
   * ext3_has_free_blocks()
   * @sbi:		in-core super block structure.
   *
   * Check if filesystem has at least 1 free block available for allocation.
   */

  static int ext3_has_free_blocks(struct ext3_sb_info *sbi, int use_reservation)

  {

  	ext3_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) &&

  		!use_reservation && sbi->s_resuid != current_fsuid() &&

  		(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
  		return 0;
  	}
  	return 1;
  }

  /**
   * ext3_should_retry_alloc()
   * @sb:			super block
   * @retries		number of attemps has been made
   *

   * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
   * it is profitable to retry the operation, this function will wait

   * for the current or committing transaction to complete, and then

   * return TRUE.

   *
   * if the total number of retries exceed three times, return FALSE.

   */
  int ext3_should_retry_alloc(struct super_block *sb, int *retries)
  {

  	if (!ext3_has_free_blocks(EXT3_SB(sb), 0) || (*retries)++ > 3)

  		return 0;
  
  	jbd_debug(1, "%s: retrying operation after ENOSPC
  ", sb->s_id);
  
  	return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
  }

  /**
   * ext3_new_blocks() -- core block(s) allocation function
   * @handle:		handle to this transaction
   * @inode:		file inode
   * @goal:		given target block(filesystem wide)
   * @count:		target number of blocks to allocate
   * @errp:		error code
   *
   * ext3_new_blocks uses a goal block to assist allocation.  It tries to
   * allocate block(s) from the block group contains the goal block first. If that
   * fails, it will try to allocate block(s) from other block groups without
   * any specific goal block.
   *

   */

  ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
  			ext3_fsblk_t goal, unsigned long *count, int *errp)

  {
  	struct buffer_head *bitmap_bh = NULL;
  	struct buffer_head *gdp_bh;
  	int group_no;
  	int goal_group;

  	ext3_grpblk_t grp_target_blk;	/* blockgroup relative goal block */
  	ext3_grpblk_t grp_alloc_blk;	/* blockgroup-relative allocated block*/
  	ext3_fsblk_t ret_block;		/* filesyetem-wide allocated block */

  	int bgi;			/* blockgroup iteration index */

  	int fatal = 0, err;
  	int performed_allocation = 0;

  	ext3_grpblk_t free_blocks;	/* number of free blocks in a group */

  	struct super_block *sb;
  	struct ext3_group_desc *gdp;
  	struct ext3_super_block *es;
  	struct ext3_sb_info *sbi;
  	struct ext3_reserve_window_node *my_rsv = NULL;
  	struct ext3_block_alloc_info *block_i;
  	unsigned short windowsz = 0;
  #ifdef EXT3FS_DEBUG
  	static int goal_hits, goal_attempts;
  #endif
  	unsigned long ngroups;

  	unsigned long num = *count;

  
  	*errp = -ENOSPC;
  	sb = inode->i_sb;

  
  	/*
  	 * Check quota for allocation of this block.
  	 */

  	err = dquot_alloc_block(inode, num);
  	if (err) {
  		*errp = err;

  		return 0;
  	}

  	trace_ext3_request_blocks(inode, goal, num);

  	sbi = EXT3_SB(sb);

  	es = sbi->s_es;

  	ext3_debug("goal=%lu.
  ", 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 EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
  	 * reservation on that particular file)
  	 */
  	block_i = EXT3_I(inode)->i_block_alloc_info;
  	if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
  		my_rsv = &block_i->rsv_window_node;

  	if (!ext3_has_free_blocks(sbi, IS_NOQUOTA(inode))) {

  		*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)) /
  			EXT3_BLOCKS_PER_GROUP(sb);

  	goal_group = group_no;
  retry_alloc:

  	gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
  	if (!gdp)
  		goto io_error;

  	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)

  		&& (free_blocks > 0)

  		&& (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)) %

  				EXT3_BLOCKS_PER_GROUP(sb));
  		bitmap_bh = read_block_bitmap(sb, group_no);
  		if (!bitmap_bh)
  			goto io_error;

  		grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
  					group_no, bitmap_bh, grp_target_blk,
  					my_rsv,	&num, &fatal);

  		if (fatal)
  			goto out;

  		if (grp_alloc_blk >= 0)

  			goto allocated;
  	}
  
  	ngroups = EXT3_SB(sb)->s_groups_count;
  	smp_rmb();
  
  	/*

  	 * Now search the rest of the groups.  We assume that

  	 * group_no and gdp correctly point to the last group visited.

  	 */
  	for (bgi = 0; bgi < ngroups; bgi++) {
  		group_no++;
  		if (group_no >= ngroups)
  			group_no = 0;
  		gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);

  		if (!gdp)
  			goto io_error;

  		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
  		/*

  		 * skip this group (and avoid loading bitmap) if there
  		 * are no free blocks
  		 */
  		if (!free_blocks)
  			continue;
  		/*

  		 * skip this group if the number of
  		 * free blocks is less than half of the reservation
  		 * window size.
  		 */

  		if (my_rsv && (free_blocks <= (windowsz/2)))

  			continue;
  
  		brelse(bitmap_bh);
  		bitmap_bh = read_block_bitmap(sb, group_no);
  		if (!bitmap_bh)
  			goto io_error;

  		/*
  		 * try to allocate block(s) from this group, without a goal(-1).
  		 */
  		grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
  					group_no, bitmap_bh, -1, my_rsv,
  					&num, &fatal);

  		if (fatal)
  			goto out;

  		if (grp_alloc_blk >= 0)

  			goto allocated;
  	}
  	/*

  	 * We may end up a bogus earlier ENOSPC error due to

  	 * filesystem is "full" of reservations, but

  	 * there maybe indeed free blocks available 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:
  
  	ext3_debug("using block group %d(%d)
  ",
  			group_no, gdp->bg_free_blocks_count);
  
  	BUFFER_TRACE(gdp_bh, "get_write_access");
  	fatal = ext3_journal_get_write_access(handle, gdp_bh);
  	if (fatal)
  		goto out;

  	ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);

  	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),

  		      EXT3_SB(sb)->s_itb_per_group) ||

  	    in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),

  		      EXT3_SB(sb)->s_itb_per_group)) {

  		ext3_error(sb, "ext3_new_block",
  			    "Allocating block in system zone - "

  			    "blocks from "E3FSBLK", length %lu",
  			     ret_block, num);

  		/*
  		 * claim_block() marked the blocks we allocated as in use. So we
  		 * may want to selectively mark some of the blocks as free.
  		 */
  		goto retry_alloc;

  	}

  
  	performed_allocation = 1;
  
  #ifdef CONFIG_JBD_DEBUG
  	{
  		struct buffer_head *debug_bh;
  
  		/* Record bitmap buffer state in the newly allocated block */

  		debug_bh = sb_find_get_block(sb, ret_block);

  		if (debug_bh) {
  			BUFFER_TRACE(debug_bh, "state when allocated");
  			BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
  			brelse(debug_bh);
  		}
  	}
  	jbd_lock_bh_state(bitmap_bh);
  	spin_lock(sb_bgl_lock(sbi, group_no));
  	if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {

  		int i;
  
  		for (i = 0; i < num; i++) {

  			if (ext3_test_bit(grp_alloc_blk+i,

  					bh2jh(bitmap_bh)->b_committed_data)) {
  				printk("%s: block was unexpectedly set in "

  					"b_committed_data
  ", __func__);

  			}

  		}
  	}

  	ext3_debug("found bit %d
  ", grp_alloc_blk);

  	spin_unlock(sb_bgl_lock(sbi, group_no));
  	jbd_unlock_bh_state(bitmap_bh);
  #endif

  	if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {

  		ext3_error(sb, "ext3_new_block",

  			    "block("E3FSBLK") >= blocks count(%d) - "

  			    "block_group = %d, es == %p ", ret_block,
  			le32_to_cpu(es->s_blocks_count), group_no, es);
  		goto out;
  	}
  
  	/*
  	 * It is up to the caller to add the new buffer to a journal
  	 * list of some description.  We don't know in advance whether
  	 * the caller wants to use it as metadata or data.
  	 */

  	ext3_debug("allocating block %lu. Goal hits %d of %d.
  ",

  			ret_block, goal_hits, goal_attempts);
  
  	spin_lock(sb_bgl_lock(sbi, group_no));

  	le16_add_cpu(&gdp->bg_free_blocks_count, -num);

  	spin_unlock(sb_bgl_lock(sbi, group_no));

  	percpu_counter_sub(&sbi->s_freeblocks_counter, num);

  
  	BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
  	err = ext3_journal_dirty_metadata(handle, gdp_bh);
  	if (!fatal)
  		fatal = err;

  	if (fatal)
  		goto out;
  
  	*errp = 0;
  	brelse(bitmap_bh);

  	dquot_free_block(inode, *count-num);

  	*count = num;

  
  	trace_ext3_allocate_blocks(inode, goal, num,
  				   (unsigned long long)ret_block);

  	return ret_block;
  
  io_error:
  	*errp = -EIO;
  out:
  	if (fatal) {
  		*errp = fatal;
  		ext3_std_error(sb, fatal);
  	}
  	/*
  	 * Undo the block allocation
  	 */
  	if (!performed_allocation)

  		dquot_free_block(inode, *count);

  	brelse(bitmap_bh);
  	return 0;
  }

  ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
  			ext3_fsblk_t goal, int *errp)

  {
  	unsigned long count = 1;
  
  	return ext3_new_blocks(handle, inode, goal, &count, errp);
  }

  /**
   * ext3_count_free_blocks() -- count filesystem free blocks
   * @sb:		superblock
   *
   * Adds up the number of free blocks from each block group.
   */

  ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)

  {

  	ext3_fsblk_t desc_count;

  	struct ext3_group_desc *gdp;
  	int i;

  	unsigned long ngroups = EXT3_SB(sb)->s_groups_count;

  #ifdef EXT3FS_DEBUG
  	struct ext3_super_block *es;

  	ext3_fsblk_t bitmap_count;
  	unsigned long x;

  	struct buffer_head *bitmap_bh = NULL;

  	es = EXT3_SB(sb)->s_es;
  	desc_count = 0;
  	bitmap_count = 0;
  	gdp = NULL;

  	smp_rmb();

  	for (i = 0; i < ngroups; i++) {

  		gdp = ext3_get_group_desc(sb, i, NULL);
  		if (!gdp)
  			continue;
  		desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
  		brelse(bitmap_bh);
  		bitmap_bh = read_block_bitmap(sb, i);
  		if (bitmap_bh == NULL)
  			continue;
  
  		x = ext3_count_free(bitmap_bh, sb->s_blocksize);
  		printk("group %d: stored = %d, counted = %lu
  ",
  			i, le16_to_cpu(gdp->bg_free_blocks_count), x);
  		bitmap_count += x;
  	}
  	brelse(bitmap_bh);

  	printk("ext3_count_free_blocks: stored = "E3FSBLK
  		", computed = "E3FSBLK", "E3FSBLK"
  ",
  	       le32_to_cpu(es->s_free_blocks_count),
  		desc_count, bitmap_count);

  	return bitmap_count;
  #else
  	desc_count = 0;

  	smp_rmb();
  	for (i = 0; i < ngroups; i++) {
  		gdp = ext3_get_group_desc(sb, i, NULL);
  		if (!gdp)
  			continue;
  		desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
  	}
  
  	return desc_count;
  #endif
  }

  static inline int test_root(int a, int b)
  {
  	int num = b;
  
  	while (a > num)
  		num *= b;
  	return num == a;
  }
  
  static int ext3_group_sparse(int group)
  {
  	if (group <= 1)
  		return 1;
  	if (!(group & 1))
  		return 0;
  	return (test_root(group, 7) || test_root(group, 5) ||
  		test_root(group, 3));
  }
  
  /**
   *	ext3_bg_has_super - number of blocks used by the superblock in group
   *	@sb: superblock for filesystem
   *	@group: group number to check
   *
   *	Return the number of blocks used by the superblock (primary or backup)
   *	in this group.  Currently this will be only 0 or 1.
   */
  int ext3_bg_has_super(struct super_block *sb, int group)
  {

  	if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
  				EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
  			!ext3_group_sparse(group))

  		return 0;
  	return 1;
  }

  static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
  {
  	unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
  	unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
  	unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
  
  	if (group == first || group == first + 1 || group == last)
  		return 1;
  	return 0;
  }
  
  static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
  {

  	return ext3_bg_has_super(sb, group) ? EXT3_SB(sb)->s_gdb_count : 0;

  }

  /**
   *	ext3_bg_num_gdb - number of blocks used by the group table in group
   *	@sb: superblock for filesystem
   *	@group: group number to check
   *
   *	Return the number of blocks used by the group descriptor table
   *	(primary or backup) in this group.  In the future there may be a
   *	different number of descriptor blocks in each group.
   */
  unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
  {

  	unsigned long first_meta_bg =
  			le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
  	unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
  
  	if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
  			metagroup < first_meta_bg)
  		return ext3_bg_num_gdb_nometa(sb,group);

  	return ext3_bg_num_gdb_meta(sb,group);
  
  }

  
  /**
   * ext3_trim_all_free -- function to trim all free space in alloc. group
   * @sb:			super block for file system
   * @group:		allocation group to trim
   * @start:		first group block to examine
   * @max:		last group block to examine
   * @gdp:		allocation group description structure
   * @minblocks:		minimum extent block count
   *
   * ext3_trim_all_free walks through group's block bitmap searching for free
   * blocks. When the free block is found, it tries to allocate this block and
   * consequent free block to get the biggest free extent possible, until it
   * reaches any used block. Then issue a TRIM command on this extent and free
   * the extent in the block bitmap. This is done until whole group is scanned.
   */

  static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb,
  					unsigned int group,
  					ext3_grpblk_t start, ext3_grpblk_t max,
  					ext3_grpblk_t minblocks)

  {
  	handle_t *handle;
  	ext3_grpblk_t next, free_blocks, bit, freed, count = 0;
  	ext3_fsblk_t discard_block;
  	struct ext3_sb_info *sbi;
  	struct buffer_head *gdp_bh, *bitmap_bh = NULL;
  	struct ext3_group_desc *gdp;
  	int err = 0, ret = 0;
  
  	/*
  	 * We will update one block bitmap, and one group descriptor
  	 */
  	handle = ext3_journal_start_sb(sb, 2);
  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	bitmap_bh = read_block_bitmap(sb, group);
  	if (!bitmap_bh) {
  		err = -EIO;
  		goto err_out;
  	}
  
  	BUFFER_TRACE(bitmap_bh, "getting undo access");
  	err = ext3_journal_get_undo_access(handle, bitmap_bh);
  	if (err)
  		goto err_out;
  
  	gdp = ext3_get_group_desc(sb, group, &gdp_bh);
  	if (!gdp) {
  		err = -EIO;
  		goto err_out;
  	}
  
  	BUFFER_TRACE(gdp_bh, "get_write_access");
  	err = ext3_journal_get_write_access(handle, gdp_bh);
  	if (err)
  		goto err_out;
  
  	free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
  	sbi = EXT3_SB(sb);
  
  	 /* Walk through the whole group */
  	while (start < max) {
  		start = bitmap_search_next_usable_block(start, bitmap_bh, max);
  		if (start < 0)
  			break;
  		next = start;
  
  		/*
  		 * Allocate contiguous free extents by setting bits in the
  		 * block bitmap
  		 */
  		while (next < max
  			&& claim_block(sb_bgl_lock(sbi, group),
  					next, bitmap_bh)) {
  			next++;
  		}
  
  		 /* We did not claim any blocks */
  		if (next == start)
  			continue;
  
  		discard_block = (ext3_fsblk_t)start +
  				ext3_group_first_block_no(sb, group);
  
  		/* Update counters */
  		spin_lock(sb_bgl_lock(sbi, group));
  		le16_add_cpu(&gdp->bg_free_blocks_count, start - next);
  		spin_unlock(sb_bgl_lock(sbi, group));
  		percpu_counter_sub(&sbi->s_freeblocks_counter, next - start);

  		free_blocks -= next - start;

  		/* Do not issue a TRIM on extents smaller than minblocks */
  		if ((next - start) < minblocks)
  			goto free_extent;

  		trace_ext3_discard_blocks(sb, discard_block, next - start);

  		 /* Send the TRIM command down to the device */
  		err = sb_issue_discard(sb, discard_block, next - start,
  				       GFP_NOFS, 0);
  		count += (next - start);
  free_extent:
  		freed = 0;
  
  		/*
  		 * Clear bits in the bitmap
  		 */
  		for (bit = start; bit < next; bit++) {
  			BUFFER_TRACE(bitmap_bh, "clear bit");
  			if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, group),
  						bit, bitmap_bh->b_data)) {
  				ext3_error(sb, __func__,
  					"bit already cleared for block "E3FSBLK,
  					 (unsigned long)bit);
  				BUFFER_TRACE(bitmap_bh, "bit already cleared");
  			} else {
  				freed++;
  			}
  		}
  
  		/* Update couters */
  		spin_lock(sb_bgl_lock(sbi, group));
  		le16_add_cpu(&gdp->bg_free_blocks_count, freed);
  		spin_unlock(sb_bgl_lock(sbi, group));
  		percpu_counter_add(&sbi->s_freeblocks_counter, freed);
  
  		start = next;
  		if (err < 0) {
  			if (err != -EOPNOTSUPP)
  				ext3_warning(sb, __func__, "Discard command "
  					     "returned error %d
  ", err);
  			break;
  		}
  
  		if (fatal_signal_pending(current)) {
  			err = -ERESTARTSYS;
  			break;
  		}
  
  		cond_resched();
  
  		/* No more suitable extents */

  		if (free_blocks < minblocks)

  			break;
  	}
  
  	/* We dirtied the bitmap block */
  	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
  	ret = ext3_journal_dirty_metadata(handle, bitmap_bh);
  	if (!err)
  		err = ret;
  
  	/* And the group descriptor block */
  	BUFFER_TRACE(gdp_bh, "dirtied group descriptor block");
  	ret = ext3_journal_dirty_metadata(handle, gdp_bh);
  	if (!err)
  		err = ret;
  
  	ext3_debug("trimmed %d blocks in the group %d
  ",
  		count, group);
  
  err_out:
  	if (err)
  		count = err;
  	ext3_journal_stop(handle);
  	brelse(bitmap_bh);
  
  	return count;
  }
  
  /**
   * ext3_trim_fs() -- trim ioctl handle function
   * @sb:			superblock for filesystem
   * @start:		First Byte to trim
   * @len:		number of Bytes to trim from start
   * @minlen:		minimum extent length in Bytes
   *
   * ext3_trim_fs goes through all allocation groups containing Bytes from
   * start to start+len. For each such a group ext3_trim_all_free function
   * is invoked to trim all free space.
   */
  int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
  {
  	ext3_grpblk_t last_block, first_block, free_blocks;
  	unsigned long first_group, last_group;
  	unsigned long group, ngroups;
  	struct ext3_group_desc *gdp;
  	struct ext3_super_block *es = EXT3_SB(sb)->s_es;
  	uint64_t start, len, minlen, trimmed;
  	ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count);
  	int ret = 0;

  	start = (range->start >> sb->s_blocksize_bits) +
  		le32_to_cpu(es->s_first_data_block);

  	len = range->len >> sb->s_blocksize_bits;
  	minlen = range->minlen >> sb->s_blocksize_bits;
  	trimmed = 0;
  
  	if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb)))
  		return -EINVAL;
  	if (start >= max_blks)

  		return -EINVAL;

  	if (start + len > max_blks)
  		len = max_blks - start;
  
  	ngroups = EXT3_SB(sb)->s_groups_count;
  	smp_rmb();
  
  	/* Determine first and last group to examine based on start and len */
  	ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start,
  				     &first_group, &first_block);
  	ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) (start + len),
  				     &last_group, &last_block);
  	last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group;
  	last_block = EXT3_BLOCKS_PER_GROUP(sb);
  
  	if (first_group > last_group)
  		return -EINVAL;
  
  	for (group = first_group; group <= last_group; group++) {
  		gdp = ext3_get_group_desc(sb, group, NULL);
  		if (!gdp)
  			break;
  
  		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
  		if (free_blocks < minlen)
  			continue;

  		/*
  		 * For all the groups except the last one, last block will
  		 * always be EXT3_BLOCKS_PER_GROUP(sb), so we only need to
  		 * change it for the last group in which case first_block +
  		 * len < EXT3_BLOCKS_PER_GROUP(sb).
  		 */
  		if (first_block + len < EXT3_BLOCKS_PER_GROUP(sb))

  			last_block = first_block + len;

  		len -= last_block - first_block;

  
  		ret = ext3_trim_all_free(sb, group, first_block,
  					last_block, minlen);
  		if (ret < 0)
  			break;
  
  		trimmed += ret;
  		first_block = 0;
  	}
  
  	if (ret >= 0)
  		ret = 0;

  	range->len = trimmed * sb->s_blocksize;
  
  	return ret;
  }