/*
   * balloc.c
   *
   * PURPOSE
   *	Block allocation handling routines for the OSTA-UDF(tm) filesystem.
   *

   * COPYRIGHT
   *	This file is distributed under the terms of the GNU General Public
   *	License (GPL). Copies of the GPL can be obtained from:
   *		ftp://prep.ai.mit.edu/pub/gnu/GPL
   *	Each contributing author retains all rights to their own work.
   *
   *  (C) 1999-2001 Ben Fennema
   *  (C) 1999 Stelias Computing Inc
   *
   * HISTORY
   *
   *  02/24/99 blf  Created.
   *
   */
  
  #include "udfdecl.h"

  #include <linux/buffer_head.h>
  #include <linux/bitops.h>
  
  #include "udf_i.h"
  #include "udf_sb.h"

  #define udf_clear_bit	__test_and_clear_bit_le
  #define udf_set_bit	__test_and_set_bit_le
  #define udf_test_bit	test_bit_le
  #define udf_find_next_one_bit	find_next_bit_le

  static int read_block_bitmap(struct super_block *sb,
  			     struct udf_bitmap *bitmap, unsigned int block,
  			     unsigned long bitmap_nr)

  {
  	struct buffer_head *bh = NULL;
  	int retval = 0;

  	struct kernel_lb_addr loc;

  
  	loc.logicalBlockNum = bitmap->s_extPosition;

  	loc.partitionReferenceNum = UDF_SB(sb)->s_partition;

  	bh = udf_tread(sb, udf_get_lb_pblock(sb, &loc, block));

  	if (!bh)

  		retval = -EIO;

  	bitmap->s_block_bitmap[bitmap_nr] = bh;
  	return retval;
  }

  static int __load_block_bitmap(struct super_block *sb,
  			       struct udf_bitmap *bitmap,
  			       unsigned int block_group)

  {
  	int retval = 0;
  	int nr_groups = bitmap->s_nr_groups;

  	if (block_group >= nr_groups) {

  		udf_debug("block_group (%d) > nr_groups (%d)
  ",
  			  block_group, nr_groups);

  	}

  	if (bitmap->s_block_bitmap[block_group]) {

  		return block_group;

  	} else {
  		retval = read_block_bitmap(sb, bitmap, block_group,
  					   block_group);

  		if (retval < 0)
  			return retval;
  		return block_group;
  	}
  }

  static inline int load_block_bitmap(struct super_block *sb,
  				    struct udf_bitmap *bitmap,
  				    unsigned int block_group)

  {
  	int slot;
  
  	slot = __load_block_bitmap(sb, bitmap, block_group);
  
  	if (slot < 0)
  		return slot;
  
  	if (!bitmap->s_block_bitmap[slot])
  		return -EIO;
  
  	return slot;
  }

  static void udf_add_free_space(struct super_block *sb, u16 partition, u32 cnt)

  {

  	struct udf_sb_info *sbi = UDF_SB(sb);

  	struct logicalVolIntegrityDesc *lvid;

  	if (!sbi->s_lvid_bh)
  		return;

  
  	lvid = (struct logicalVolIntegrityDesc *)sbi->s_lvid_bh->b_data;

  	le32_add_cpu(&lvid->freeSpaceTable[partition], cnt);

  	udf_updated_lvid(sb);

  }

  static void udf_bitmap_free_blocks(struct super_block *sb,
  				   struct inode *inode,
  				   struct udf_bitmap *bitmap,

  				   struct kernel_lb_addr *bloc,
  				   uint32_t offset,

  				   uint32_t count)

  {
  	struct udf_sb_info *sbi = UDF_SB(sb);

  	struct buffer_head *bh = NULL;

  	struct udf_part_map *partmap;

  	unsigned long block;
  	unsigned long block_group;
  	unsigned long bit;
  	unsigned long i;
  	int bitmap_nr;
  	unsigned long overflow;

  	mutex_lock(&sbi->s_alloc_mutex);

  	partmap = &sbi->s_partmaps[bloc->partitionReferenceNum];

  	if (bloc->logicalBlockNum + count < count ||
  	    (bloc->logicalBlockNum + count) > partmap->s_partition_len) {

  		udf_debug("%d < %d || %d + %d > %d
  ",

  			  bloc->logicalBlockNum, 0,
  			  bloc->logicalBlockNum, count,
  			  partmap->s_partition_len);

  		goto error_return;
  	}

  	block = bloc->logicalBlockNum + offset +

  		(sizeof(struct spaceBitmapDesc) << 3);

  	do {
  		overflow = 0;
  		block_group = block >> (sb->s_blocksize_bits + 3);
  		bit = block % (sb->s_blocksize << 3);
  
  		/*
  		* Check to see if we are freeing blocks across a group boundary.
  		*/
  		if (bit + count > (sb->s_blocksize << 3)) {
  			overflow = bit + count - (sb->s_blocksize << 3);
  			count -= overflow;

  		}

  		bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
  		if (bitmap_nr < 0)
  			goto error_return;
  
  		bh = bitmap->s_block_bitmap[bitmap_nr];
  		for (i = 0; i < count; i++) {
  			if (udf_set_bit(bit + i, bh->b_data)) {
  				udf_debug("bit %ld already set
  ", bit + i);
  				udf_debug("byte=%2x
  ",

  					  ((char *)bh->b_data)[(bit + i) >> 3]);

  			}
  		}

  		udf_add_free_space(sb, sbi->s_partition, count);

  		mark_buffer_dirty(bh);
  		if (overflow) {
  			block += count;
  			count = overflow;
  		}
  	} while (overflow);

  error_return:

  	mutex_unlock(&sbi->s_alloc_mutex);

  }

  static int udf_bitmap_prealloc_blocks(struct super_block *sb,
  				      struct inode *inode,
  				      struct udf_bitmap *bitmap,
  				      uint16_t partition, uint32_t first_block,
  				      uint32_t block_count)

  {
  	struct udf_sb_info *sbi = UDF_SB(sb);
  	int alloc_count = 0;
  	int bit, block, block_group, group_start;
  	int nr_groups, bitmap_nr;
  	struct buffer_head *bh;

  	__u32 part_len;

  	mutex_lock(&sbi->s_alloc_mutex);

  	part_len = sbi->s_partmaps[partition].s_partition_len;

  	if (first_block >= part_len)

  		goto out;

  	if (first_block + block_count > part_len)
  		block_count = part_len - first_block;

  	do {
  		nr_groups = udf_compute_nr_groups(sb, partition);
  		block = first_block + (sizeof(struct spaceBitmapDesc) << 3);
  		block_group = block >> (sb->s_blocksize_bits + 3);
  		group_start = block_group ? 0 : sizeof(struct spaceBitmapDesc);

  		bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
  		if (bitmap_nr < 0)
  			goto out;
  		bh = bitmap->s_block_bitmap[bitmap_nr];

  		bit = block % (sb->s_blocksize << 3);

  		while (bit < (sb->s_blocksize << 3) && block_count > 0) {

  			if (!udf_clear_bit(bit, bh->b_data))

  				goto out;

  			block_count--;
  			alloc_count++;
  			bit++;
  			block++;

  		}

  		mark_buffer_dirty(bh);
  	} while (block_count > 0);

  out:

  	udf_add_free_space(sb, partition, -alloc_count);

  	mutex_unlock(&sbi->s_alloc_mutex);

  	return alloc_count;
  }

  static int udf_bitmap_new_block(struct super_block *sb,
  				struct inode *inode,
  				struct udf_bitmap *bitmap, uint16_t partition,
  				uint32_t goal, int *err)

  {
  	struct udf_sb_info *sbi = UDF_SB(sb);

  	int newbit, bit = 0, block, block_group, group_start;

  	int end_goal, nr_groups, bitmap_nr, i;
  	struct buffer_head *bh = NULL;
  	char *ptr;
  	int newblock = 0;
  
  	*err = -ENOSPC;

  	mutex_lock(&sbi->s_alloc_mutex);

  repeat:

  	if (goal >= sbi->s_partmaps[partition].s_partition_len)

  		goal = 0;
  
  	nr_groups = bitmap->s_nr_groups;
  	block = goal + (sizeof(struct spaceBitmapDesc) << 3);
  	block_group = block >> (sb->s_blocksize_bits + 3);
  	group_start = block_group ? 0 : sizeof(struct spaceBitmapDesc);
  
  	bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
  	if (bitmap_nr < 0)
  		goto error_return;
  	bh = bitmap->s_block_bitmap[bitmap_nr];

  	ptr = memscan((char *)bh->b_data + group_start, 0xFF,
  		      sb->s_blocksize - group_start);

  	if ((ptr - ((char *)bh->b_data)) < sb->s_blocksize) {

  		bit = block % (sb->s_blocksize << 3);

  		if (udf_test_bit(bit, bh->b_data))

  			goto got_block;

  		end_goal = (bit + 63) & ~63;
  		bit = udf_find_next_one_bit(bh->b_data, end_goal, bit);
  		if (bit < end_goal)
  			goto got_block;

  		ptr = memscan((char *)bh->b_data + (bit >> 3), 0xFF,
  			      sb->s_blocksize - ((bit + 7) >> 3));

  		newbit = (ptr - ((char *)bh->b_data)) << 3;

  		if (newbit < sb->s_blocksize << 3) {

  			bit = newbit;
  			goto search_back;
  		}

  		newbit = udf_find_next_one_bit(bh->b_data,
  					       sb->s_blocksize << 3, bit);

  		if (newbit < sb->s_blocksize << 3) {

  			bit = newbit;
  			goto got_block;
  		}
  	}

  	for (i = 0; i < (nr_groups * 2); i++) {
  		block_group++;

  		if (block_group >= nr_groups)
  			block_group = 0;
  		group_start = block_group ? 0 : sizeof(struct spaceBitmapDesc);
  
  		bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
  		if (bitmap_nr < 0)
  			goto error_return;
  		bh = bitmap->s_block_bitmap[bitmap_nr];

  		if (i < nr_groups) {

  			ptr = memscan((char *)bh->b_data + group_start, 0xFF,
  				      sb->s_blocksize - group_start);

  			if ((ptr - ((char *)bh->b_data)) < sb->s_blocksize) {

  				bit = (ptr - ((char *)bh->b_data)) << 3;
  				break;
  			}

  		} else {

  			bit = udf_find_next_one_bit(bh->b_data,

  						    sb->s_blocksize << 3,
  						    group_start << 3);

  			if (bit < sb->s_blocksize << 3)
  				break;
  		}
  	}

  	if (i >= (nr_groups * 2)) {

  		mutex_unlock(&sbi->s_alloc_mutex);

  		return newblock;
  	}
  	if (bit < sb->s_blocksize << 3)
  		goto search_back;
  	else

  		bit = udf_find_next_one_bit(bh->b_data, sb->s_blocksize << 3,
  					    group_start << 3);

  	if (bit >= sb->s_blocksize << 3) {

  		mutex_unlock(&sbi->s_alloc_mutex);

  		return 0;
  	}

  search_back:

  	i = 0;
  	while (i < 7 && bit > (group_start << 3) &&
  	       udf_test_bit(bit - 1, bh->b_data)) {
  		++i;
  		--bit;
  	}

  got_block:

  	newblock = bit + (block_group << (sb->s_blocksize_bits + 3)) -

  		(sizeof(struct spaceBitmapDesc) << 3);

  	if (!udf_clear_bit(bit, bh->b_data)) {

  		udf_debug("bit already cleared for block %d
  ", bit);
  		goto repeat;
  	}
  
  	mark_buffer_dirty(bh);

  	udf_add_free_space(sb, partition, -1);

  	mutex_unlock(&sbi->s_alloc_mutex);

  	*err = 0;
  	return newblock;

  error_return:

  	*err = -EIO;

  	mutex_unlock(&sbi->s_alloc_mutex);

  	return 0;
  }

  static void udf_table_free_blocks(struct super_block *sb,
  				  struct inode *inode,
  				  struct inode *table,

  				  struct kernel_lb_addr *bloc,
  				  uint32_t offset,

  				  uint32_t count)

  {
  	struct udf_sb_info *sbi = UDF_SB(sb);

  	struct udf_part_map *partmap;

  	uint32_t start, end;

  	uint32_t elen;

  	struct kernel_lb_addr eloc;

  	struct extent_position oepos, epos;

  	int8_t etype;
  	int i;

  	struct udf_inode_info *iinfo;

  	mutex_lock(&sbi->s_alloc_mutex);

  	partmap = &sbi->s_partmaps[bloc->partitionReferenceNum];

  	if (bloc->logicalBlockNum + count < count ||
  	    (bloc->logicalBlockNum + count) > partmap->s_partition_len) {

  		udf_debug("%d < %d || %d + %d > %d
  ",

  			  bloc->logicalBlockNum, 0,
  			  bloc->logicalBlockNum, count,

  			  partmap->s_partition_len);

  		goto error_return;
  	}

  	iinfo = UDF_I(table);

  	udf_add_free_space(sb, sbi->s_partition, count);

  	start = bloc->logicalBlockNum + offset;
  	end = bloc->logicalBlockNum + offset + count - 1;

  	epos.offset = oepos.offset = sizeof(struct unallocSpaceEntry);

  	elen = 0;

  	epos.block = oepos.block = iinfo->i_location;

  	epos.bh = oepos.bh = NULL;

  	while (count &&
  	       (etype = udf_next_aext(table, &epos, &eloc, &elen, 1)) != -1) {

  		if (((eloc.logicalBlockNum +
  			(elen >> sb->s_blocksize_bits)) == start)) {
  			if ((0x3FFFFFFF - elen) <
  					(count << sb->s_blocksize_bits)) {
  				uint32_t tmp = ((0x3FFFFFFF - elen) >>
  							sb->s_blocksize_bits);
  				count -= tmp;
  				start += tmp;
  				elen = (etype << 30) |
  					(0x40000000 - sb->s_blocksize);

  			} else {

  				elen = (etype << 30) |
  					(elen +
  					(count << sb->s_blocksize_bits));

  				start += count;
  				count = 0;
  			}

  			udf_write_aext(table, &oepos, &eloc, elen, 1);

  		} else if (eloc.logicalBlockNum == (end + 1)) {

  			if ((0x3FFFFFFF - elen) <
  					(count << sb->s_blocksize_bits)) {
  				uint32_t tmp = ((0x3FFFFFFF - elen) >>
  						sb->s_blocksize_bits);
  				count -= tmp;
  				end -= tmp;
  				eloc.logicalBlockNum -= tmp;
  				elen = (etype << 30) |
  					(0x40000000 - sb->s_blocksize);

  			} else {

  				eloc.logicalBlockNum = start;

  				elen = (etype << 30) |
  					(elen +
  					(count << sb->s_blocksize_bits));

  				end -= count;
  				count = 0;
  			}

  			udf_write_aext(table, &oepos, &eloc, elen, 1);

  		}

  		if (epos.bh != oepos.bh) {

  			i = -1;

  			oepos.block = epos.block;

  			brelse(oepos.bh);
  			get_bh(epos.bh);

  			oepos.bh = epos.bh;
  			oepos.offset = 0;

  		} else {

  			oepos.offset = epos.offset;

  		}

  	}

  	if (count) {

  		/*

  		 * NOTE: we CANNOT use udf_add_aext here, as it can try to
  		 * allocate a new block, and since we hold the super block
  		 * lock already very bad things would happen :)

  		 *
  		 * We copy the behavior of udf_add_aext, but instead of
  		 * trying to allocate a new block close to the existing one,
  		 * we just steal a block from the extent we are trying to add.
  		 *
  		 * It would be nice if the blocks were close together, but it
  		 * isn't required.

  		 */

  
  		int adsize;

  		struct short_ad *sad = NULL;
  		struct long_ad *lad = NULL;

  		struct allocExtDesc *aed;
  
  		eloc.logicalBlockNum = start;

  		elen = EXT_RECORDED_ALLOCATED |
  			(count << sb->s_blocksize_bits);

  		if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)

  			adsize = sizeof(struct short_ad);

  		else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)

  			adsize = sizeof(struct long_ad);

  		else {

  			brelse(oepos.bh);
  			brelse(epos.bh);

  			goto error_return;
  		}

  		if (epos.offset + (2 * adsize) > sb->s_blocksize) {

  			unsigned char *sptr, *dptr;

  			int loffset;

  			brelse(oepos.bh);

  			oepos = epos;

  
  			/* Steal a block from the extent being free'd */

  			epos.block.logicalBlockNum = eloc.logicalBlockNum;

  			eloc.logicalBlockNum++;

  			elen -= sb->s_blocksize;

  			epos.bh = udf_tread(sb,

  					udf_get_lb_pblock(sb, &epos.block, 0));

  			if (!epos.bh) {

  				brelse(oepos.bh);

  				goto error_return;
  			}

  			aed = (struct allocExtDesc *)(epos.bh->b_data);

  			aed->previousAllocExtLocation =
  				cpu_to_le32(oepos.block.logicalBlockNum);

  			if (epos.offset + adsize > sb->s_blocksize) {

  				loffset = epos.offset;

  				aed->lengthAllocDescs = cpu_to_le32(adsize);

  				sptr = iinfo->i_ext.i_data + epos.offset

  								- adsize;

  				dptr = epos.bh->b_data +
  					sizeof(struct allocExtDesc);

  				memcpy(dptr, sptr, adsize);

  				epos.offset = sizeof(struct allocExtDesc) +
  						adsize;

  			} else {

  				loffset = epos.offset + adsize;

  				aed->lengthAllocDescs = cpu_to_le32(0);

  				if (oepos.bh) {

  					sptr = oepos.bh->b_data + epos.offset;

  					aed = (struct allocExtDesc *)
  						oepos.bh->b_data;

  					le32_add_cpu(&aed->lengthAllocDescs,
  							adsize);

  				} else {

  					sptr = iinfo->i_ext.i_data +

  								epos.offset;

  					iinfo->i_lenAlloc += adsize;

  					mark_inode_dirty(table);
  				}

  				epos.offset = sizeof(struct allocExtDesc);

  			}

  			if (sbi->s_udfrev >= 0x0200)

  				udf_new_tag(epos.bh->b_data, TAG_IDENT_AED,
  					    3, 1, epos.block.logicalBlockNum,

  					    sizeof(struct tag));

  			else

  				udf_new_tag(epos.bh->b_data, TAG_IDENT_AED,
  					    2, 1, epos.block.logicalBlockNum,

  					    sizeof(struct tag));

  			switch (iinfo->i_alloc_type) {

  			case ICBTAG_FLAG_AD_SHORT:

  				sad = (struct short_ad *)sptr;

  				sad->extLength = cpu_to_le32(
  					EXT_NEXT_EXTENT_ALLOCDECS |
  					sb->s_blocksize);
  				sad->extPosition =
  					cpu_to_le32(epos.block.logicalBlockNum);
  				break;
  			case ICBTAG_FLAG_AD_LONG:

  				lad = (struct long_ad *)sptr;

  				lad->extLength = cpu_to_le32(
  					EXT_NEXT_EXTENT_ALLOCDECS |
  					sb->s_blocksize);
  				lad->extLocation =
  					cpu_to_lelb(epos.block);
  				break;

  			}

  			if (oepos.bh) {

  				udf_update_tag(oepos.bh->b_data, loffset);
  				mark_buffer_dirty(oepos.bh);

  			} else {

  				mark_inode_dirty(table);

  			}

  		}

  		/* It's possible that stealing the block emptied the extent */
  		if (elen) {

  			udf_write_aext(table, &epos, &eloc, elen, 1);

  			if (!epos.bh) {

  				iinfo->i_lenAlloc += adsize;

  				mark_inode_dirty(table);

  			} else {

  				aed = (struct allocExtDesc *)epos.bh->b_data;

  				le32_add_cpu(&aed->lengthAllocDescs, adsize);

  				udf_update_tag(epos.bh->b_data, epos.offset);
  				mark_buffer_dirty(epos.bh);

  			}
  		}
  	}

  	brelse(epos.bh);
  	brelse(oepos.bh);

  error_return:

  	mutex_unlock(&sbi->s_alloc_mutex);

  	return;
  }

  static int udf_table_prealloc_blocks(struct super_block *sb,
  				     struct inode *inode,
  				     struct inode *table, uint16_t partition,
  				     uint32_t first_block, uint32_t block_count)

  {
  	struct udf_sb_info *sbi = UDF_SB(sb);
  	int alloc_count = 0;

  	uint32_t elen, adsize;

  	struct kernel_lb_addr eloc;

  	struct extent_position epos;

  	int8_t etype = -1;

  	struct udf_inode_info *iinfo;

  	if (first_block >= sbi->s_partmaps[partition].s_partition_len)

  		return 0;

  	iinfo = UDF_I(table);
  	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)

  		adsize = sizeof(struct short_ad);

  	else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)

  		adsize = sizeof(struct long_ad);

  	else
  		return 0;

  	mutex_lock(&sbi->s_alloc_mutex);

  	epos.offset = sizeof(struct unallocSpaceEntry);

  	epos.block = iinfo->i_location;

  	epos.bh = NULL;

  	eloc.logicalBlockNum = 0xFFFFFFFF;

  	while (first_block != eloc.logicalBlockNum &&
  	       (etype = udf_next_aext(table, &epos, &eloc, &elen, 1)) != -1) {

  		udf_debug("eloc=%d, elen=%d, first_block=%d
  ",

  			  eloc.logicalBlockNum, elen, first_block);

  		; /* empty loop body */

  	}

  	if (first_block == eloc.logicalBlockNum) {

  		epos.offset -= adsize;

  
  		alloc_count = (elen >> sb->s_blocksize_bits);

  		if (alloc_count > block_count) {

  			alloc_count = block_count;
  			eloc.logicalBlockNum += alloc_count;
  			elen -= (alloc_count << sb->s_blocksize_bits);

  			udf_write_aext(table, &epos, &eloc,

  					(etype << 30) | elen, 1);
  		} else
  			udf_delete_aext(table, epos, eloc,
  					(etype << 30) | elen);

  	} else {

  		alloc_count = 0;

  	}

  	brelse(epos.bh);

  	if (alloc_count)
  		udf_add_free_space(sb, partition, -alloc_count);

  	mutex_unlock(&sbi->s_alloc_mutex);

  	return alloc_count;
  }

  static int udf_table_new_block(struct super_block *sb,
  			       struct inode *inode,
  			       struct inode *table, uint16_t partition,
  			       uint32_t goal, int *err)

  {
  	struct udf_sb_info *sbi = UDF_SB(sb);
  	uint32_t spread = 0xFFFFFFFF, nspread = 0xFFFFFFFF;
  	uint32_t newblock = 0, adsize;

  	uint32_t elen, goal_elen = 0;

  	struct kernel_lb_addr eloc, uninitialized_var(goal_eloc);

  	struct extent_position epos, goal_epos;

  	int8_t etype;

  	struct udf_inode_info *iinfo = UDF_I(table);

  
  	*err = -ENOSPC;

  	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)

  		adsize = sizeof(struct short_ad);

  	else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)

  		adsize = sizeof(struct long_ad);

  	else
  		return newblock;

  	mutex_lock(&sbi->s_alloc_mutex);

  	if (goal >= sbi->s_partmaps[partition].s_partition_len)

  		goal = 0;

  	/* We search for the closest matching block to goal. If we find
  	   a exact hit, we stop. Otherwise we keep going till we run out
  	   of extents. We store the buffer_head, bloc, and extoffset
  	   of the current closest match and use that when we are done.

  	 */

  	epos.offset = sizeof(struct unallocSpaceEntry);

  	epos.block = iinfo->i_location;

  	epos.bh = goal_epos.bh = NULL;

  	while (spread &&
  	       (etype = udf_next_aext(table, &epos, &eloc, &elen, 1)) != -1) {

  		if (goal >= eloc.logicalBlockNum) {

  			if (goal < eloc.logicalBlockNum +
  					(elen >> sb->s_blocksize_bits))

  				nspread = 0;
  			else
  				nspread = goal - eloc.logicalBlockNum -

  					(elen >> sb->s_blocksize_bits);
  		} else {

  			nspread = eloc.logicalBlockNum - goal;

  		}

  		if (nspread < spread) {

  			spread = nspread;

  			if (goal_epos.bh != epos.bh) {

  				brelse(goal_epos.bh);

  				goal_epos.bh = epos.bh;

  				get_bh(goal_epos.bh);

  			}

  			goal_epos.block = epos.block;
  			goal_epos.offset = epos.offset - adsize;

  			goal_eloc = eloc;
  			goal_elen = (etype << 30) | elen;
  		}
  	}

  	brelse(epos.bh);

  	if (spread == 0xFFFFFFFF) {

  		brelse(goal_epos.bh);

  		mutex_unlock(&sbi->s_alloc_mutex);

  		return 0;
  	}
  
  	/* Only allocate blocks from the beginning of the extent.
  	   That way, we only delete (empty) extents, never have to insert an
  	   extent because of splitting */
  	/* This works, but very poorly.... */
  
  	newblock = goal_eloc.logicalBlockNum;

  	goal_eloc.logicalBlockNum++;

  	goal_elen -= sb->s_blocksize;

  
  	if (goal_elen)

  		udf_write_aext(table, &goal_epos, &goal_eloc, goal_elen, 1);

  	else

  		udf_delete_aext(table, goal_epos, goal_eloc, goal_elen);

  	brelse(goal_epos.bh);

  	udf_add_free_space(sb, partition, -1);

  	mutex_unlock(&sbi->s_alloc_mutex);

  	*err = 0;
  	return newblock;
  }

  void udf_free_blocks(struct super_block *sb, struct inode *inode,
  		     struct kernel_lb_addr *bloc, uint32_t offset,
  		     uint32_t count)

  {

  	uint16_t partition = bloc->partitionReferenceNum;

  	struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];

  	if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP) {

  		udf_bitmap_free_blocks(sb, inode, map->s_uspace.s_bitmap,
  				       bloc, offset, count);

  	} else if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_TABLE) {

  		udf_table_free_blocks(sb, inode, map->s_uspace.s_table,
  				      bloc, offset, count);

  	} else if (map->s_partition_flags & UDF_PART_FLAG_FREED_BITMAP) {

  		udf_bitmap_free_blocks(sb, inode, map->s_fspace.s_bitmap,
  				       bloc, offset, count);

  	} else if (map->s_partition_flags & UDF_PART_FLAG_FREED_TABLE) {

  		udf_table_free_blocks(sb, inode, map->s_fspace.s_table,
  				      bloc, offset, count);

  	}

  }

  inline int udf_prealloc_blocks(struct super_block *sb,
  			       struct inode *inode,
  			       uint16_t partition, uint32_t first_block,
  			       uint32_t block_count)

  {

  	struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];

  	if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP)

  		return udf_bitmap_prealloc_blocks(sb, inode,

  						  map->s_uspace.s_bitmap,

  						  partition, first_block,
  						  block_count);
  	else if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_TABLE)

  		return udf_table_prealloc_blocks(sb, inode,

  						 map->s_uspace.s_table,

  						 partition, first_block,
  						 block_count);
  	else if (map->s_partition_flags & UDF_PART_FLAG_FREED_BITMAP)

  		return udf_bitmap_prealloc_blocks(sb, inode,

  						  map->s_fspace.s_bitmap,

  						  partition, first_block,
  						  block_count);
  	else if (map->s_partition_flags & UDF_PART_FLAG_FREED_TABLE)

  		return udf_table_prealloc_blocks(sb, inode,

  						 map->s_fspace.s_table,

  						 partition, first_block,
  						 block_count);
  	else

  		return 0;
  }

  inline int udf_new_block(struct super_block *sb,
  			 struct inode *inode,
  			 uint16_t partition, uint32_t goal, int *err)

  {

  	struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];

  	if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP)
  		return udf_bitmap_new_block(sb, inode,

  					   map->s_uspace.s_bitmap,

  					   partition, goal, err);

  	else if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_TABLE)

  		return udf_table_new_block(sb, inode,

  					   map->s_uspace.s_table,

  					   partition, goal, err);

  	else if (map->s_partition_flags & UDF_PART_FLAG_FREED_BITMAP)

  		return udf_bitmap_new_block(sb, inode,

  					    map->s_fspace.s_bitmap,

  					    partition, goal, err);

  	else if (map->s_partition_flags & UDF_PART_FLAG_FREED_TABLE)

  		return udf_table_new_block(sb, inode,

  					   map->s_fspace.s_table,

  					   partition, goal, err);

  	else {

  		*err = -EIO;
  		return 0;
  	}
  }