balloc.c

linux 内核源代码

	if (UDF_SB_LVIDBH(sb)) {
		UDF_SB_LVID(sb)->freeSpaceTable[UDF_SB_PARTITION(sb)] =
			cpu_to_le32(le32_to_cpu(UDF_SB_LVID(sb)->freeSpaceTable[UDF_SB_PARTITION(sb)]) + count);
		mark_buffer_dirty(UDF_SB_LVIDBH(sb));
	}

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

	epos.offset = oepos.offset = sizeof(struct unallocSpaceEntry);
	elen = 0;
	epos.block = oepos.block = UDF_I_LOCATION(table);
	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)) {
				count -= ((0x3FFFFFFF - elen) >> sb->s_blocksize_bits);
				start += ((0x3FFFFFFF - elen) >> sb->s_blocksize_bits);
				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)) {
				count -= ((0x3FFFFFFF - elen) >> sb->s_blocksize_bits);
				end -= ((0x3FFFFFFF - elen) >> sb->s_blocksize_bits);
				eloc.logicalBlockNum -= ((0x3FFFFFFF - elen) >> sb->s_blocksize_bits);
				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;
		short_ad *sad = NULL;
		long_ad *lad = NULL;
		struct allocExtDesc *aed;

		eloc.logicalBlockNum = start;
		elen = EXT_RECORDED_ALLOCATED |
			(count << sb->s_blocksize_bits);

		if (UDF_I_ALLOCTYPE(table) == ICBTAG_FLAG_AD_SHORT) {
			adsize = sizeof(short_ad);
		} else if (UDF_I_ALLOCTYPE(table) == ICBTAG_FLAG_AD_LONG) {
			adsize = sizeof(long_ad);
		} else {
			brelse(oepos.bh);
			brelse(epos.bh);
			goto error_return;
		}

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

			if (!(epos.bh = udf_tread(sb, udf_get_lb_pblock(sb, epos.block, 0)))) {
				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 = UDF_I_DATA(table) + 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;
					aed->lengthAllocDescs =
						cpu_to_le32(le32_to_cpu(aed->lengthAllocDescs) + adsize);
				} else {
					sptr = UDF_I_DATA(table) + epos.offset;
					UDF_I_LENALLOC(table) += adsize;
					mark_inode_dirty(table);
				}
				epos.offset = sizeof(struct allocExtDesc);
			}
			if (UDF_SB_UDFREV(sb) >= 0x0200)
				udf_new_tag(epos.bh->b_data, TAG_IDENT_AED, 3, 1,
					    epos.block.logicalBlockNum, sizeof(tag));
			else
				udf_new_tag(epos.bh->b_data, TAG_IDENT_AED, 2, 1,
					    epos.block.logicalBlockNum, sizeof(tag));

			switch (UDF_I_ALLOCTYPE(table)) {
				case ICBTAG_FLAG_AD_SHORT:
					sad = (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 = (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);
			}
		}

		if (elen) { /* It's possible that stealing the block emptied the extent */
			udf_write_aext(table, &epos, eloc, elen, 1);

			if (!epos.bh) {
				UDF_I_LENALLOC(table) += adsize;
				mark_inode_dirty(table);
			} else {
				aed = (struct allocExtDesc *)epos.bh->b_data;
				aed->lengthAllocDescs =
					cpu_to_le32(le32_to_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:
	sb->s_dirt = 1;
	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;
	kernel_lb_addr eloc;
	struct extent_position epos;
	int8_t etype = -1;

	if (first_block < 0 || first_block >= UDF_SB_PARTLEN(sb, partition))
		return 0;

	if (UDF_I_ALLOCTYPE(table) == ICBTAG_FLAG_AD_SHORT)
		adsize = sizeof(short_ad);
	else if (UDF_I_ALLOCTYPE(table) == ICBTAG_FLAG_AD_LONG)
		adsize = sizeof(long_ad);
	else
		return 0;

	mutex_lock(&sbi->s_alloc_mutex);
	epos.offset = sizeof(struct unallocSpaceEntry);
	epos.block = UDF_I_LOCATION(table);
	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\n",
			  eloc.logicalBlockNum, elen, first_block);
		; /* empty loop body */
	}

	if (first_block == eloc.logicalBlockNum) {
		epos.offset -= adsize;

		alloc_count = (elen >> sb->s_blocksize_bits);
		if (inode && DQUOT_PREALLOC_BLOCK(inode, alloc_count > block_count ? block_count : alloc_count)) {
			alloc_count = 0;
		} else 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_SB_LVIDBH(sb)) {
		UDF_SB_LVID(sb)->freeSpaceTable[partition] =
			cpu_to_le32(le32_to_cpu(UDF_SB_LVID(sb)->freeSpaceTable[partition]) - alloc_count);
		mark_buffer_dirty(UDF_SB_LVIDBH(sb));
		sb->s_dirt = 1;
	}
	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;
	kernel_lb_addr eloc, uninitialized_var(goal_eloc);
	struct extent_position epos, goal_epos;
	int8_t etype;

	*err = -ENOSPC;

	if (UDF_I_ALLOCTYPE(table) == ICBTAG_FLAG_AD_SHORT)
		adsize = sizeof(short_ad);
	else if (UDF_I_ALLOCTYPE(table) == ICBTAG_FLAG_AD_LONG)
		adsize = sizeof(long_ad);
	else
		return newblock;

	mutex_lock(&sbi->s_alloc_mutex);
	if (goal < 0 || goal >= UDF_SB_PARTLEN(sb, partition))
		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 = UDF_I_LOCATION(table);
	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 (inode && DQUOT_ALLOC_BLOCK(inode, 1)) {
		brelse(goal_epos.bh);
		mutex_unlock(&sbi->s_alloc_mutex);
		*err = -EDQUOT;
		return 0;
	}

	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);

	if (UDF_SB_LVIDBH(sb)) {
		UDF_SB_LVID(sb)->freeSpaceTable[partition] =
			cpu_to_le32(le32_to_cpu(UDF_SB_LVID(sb)->freeSpaceTable[partition]) - 1);
		mark_buffer_dirty(UDF_SB_LVIDBH(sb));
	}

	sb->s_dirt = 1;
	mutex_unlock(&sbi->s_alloc_mutex);
	*err = 0;
	return newblock;
}

inline void udf_free_blocks(struct super_block *sb,
			    struct inode *inode,
			    kernel_lb_addr bloc, uint32_t offset,
			    uint32_t count)
{
	uint16_t partition = bloc.partitionReferenceNum;

	if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_UNALLOC_BITMAP) {
		return udf_bitmap_free_blocks(sb, inode,
					      UDF_SB_PARTMAPS(sb)[partition].s_uspace.s_bitmap,
					      bloc, offset, count);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_UNALLOC_TABLE) {
		return udf_table_free_blocks(sb, inode,
					     UDF_SB_PARTMAPS(sb)[partition].s_uspace.s_table,
					     bloc, offset, count);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_FREED_BITMAP) {
		return udf_bitmap_free_blocks(sb, inode,
					      UDF_SB_PARTMAPS(sb)[partition].s_fspace.s_bitmap,
					      bloc, offset, count);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_FREED_TABLE) {
		return udf_table_free_blocks(sb, inode,
					     UDF_SB_PARTMAPS(sb)[partition].s_fspace.s_table,
					     bloc, offset, count);
	} else {
		return;
	}
}

inline int udf_prealloc_blocks(struct super_block *sb,
			       struct inode *inode,
			       uint16_t partition, uint32_t first_block,
			       uint32_t block_count)
{
	if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_UNALLOC_BITMAP) {
		return udf_bitmap_prealloc_blocks(sb, inode,
						  UDF_SB_PARTMAPS(sb)[partition].s_uspace.s_bitmap,
						  partition, first_block, block_count);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_UNALLOC_TABLE) {
		return udf_table_prealloc_blocks(sb, inode,
						 UDF_SB_PARTMAPS(sb)[partition].s_uspace.s_table,
						 partition, first_block, block_count);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_FREED_BITMAP) {
		return udf_bitmap_prealloc_blocks(sb, inode,
						  UDF_SB_PARTMAPS(sb)[partition].s_fspace.s_bitmap,
						  partition, first_block, block_count);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_FREED_TABLE) {
		return udf_table_prealloc_blocks(sb, inode,
						 UDF_SB_PARTMAPS(sb)[partition].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)
{
	int ret;

	if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_UNALLOC_BITMAP) {
		ret = udf_bitmap_new_block(sb, inode,
					   UDF_SB_PARTMAPS(sb)[partition].s_uspace.s_bitmap,
					   partition, goal, err);
		return ret;
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_UNALLOC_TABLE) {
		return udf_table_new_block(sb, inode,
					   UDF_SB_PARTMAPS(sb)[partition].s_uspace.s_table,
					   partition, goal, err);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_FREED_BITMAP) {
		return udf_bitmap_new_block(sb, inode,
					    UDF_SB_PARTMAPS(sb)[partition].s_fspace.s_bitmap,
					    partition, goal, err);
	} else if (UDF_SB_PARTFLAGS(sb, partition) & UDF_PART_FLAG_FREED_TABLE) {
		return udf_table_new_block(sb, inode,
					   UDF_SB_PARTMAPS(sb)[partition].s_fspace.s_table,
					   partition, goal, err);
	} else {
		*err = -EIO;
		return 0;
	}
}