balloc.c

这是Linux系统下的对UDF文件系统新增的功能

/*
 * balloc.c
 *
 * PURPOSE
 *	Block allocation handling routines for the OSTA-UDF(tm) filesystem.
 *
 * CONTACTS
 *	E-mail regarding any portion of the Linux UDF file system should be
 *	directed to the development team mailing list (run by majordomo):
 *		[e-mail]
 *
 * 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) 1999-2003 Ben Fennema
 *  (C) 1999 Stelias Computing Inc
 *
 * HISTORY
 *
 *  02/24/99 blf  Created.
 *
 */

#include "udfdecl.h"

#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <asm/bitops.h>

#include "udf_i.h"
#include "udf_sb.h"

#define udf_clear_bit(nr,addr) ext2_clear_bit(nr,addr)
#define udf_set_bit(nr,addr) ext2_set_bit(nr,addr)
#define udf_test_bit(nr, addr) ext2_test_bit(nr, addr)
#define udf_find_first_one_bit(addr, size) find_first_one_bit(addr, size)
#define udf_find_next_one_bit(addr, size, offset) find_next_one_bit(addr, size, offset)

#define leBPL_to_cpup(x) leNUM_to_cpup(BITS_PER_LONG, x)
#define leNUM_to_cpup(x,y) xleNUM_to_cpup(x,y)
#define xleNUM_to_cpup(x,y) (le ## x ## _to_cpup(y))
#define uintBPL_t uint(BITS_PER_LONG)
#define uint(x) xuint(x)
#define xuint(x) uint ## x ## _t

extern inline int find_next_one_bit (void * addr, int size, int offset)
{
	uintBPL_t * p = ((uintBPL_t *) addr) + (offset / BITS_PER_LONG);
	uintBPL_t result = offset & ~(BITS_PER_LONG-1);
	uintBPL_t tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset &= (BITS_PER_LONG-1);
	if (offset)
	{
		tmp = leBPL_to_cpup(p++);
		tmp &= ~0UL << offset;
		if (size < BITS_PER_LONG)
			goto found_first;
		if (tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}
	while (size & ~(BITS_PER_LONG-1))
	{
		if ((tmp = leBPL_to_cpup(p++)))
			goto found_middle;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = leBPL_to_cpup(p);
found_first:
	tmp &= ~0UL >> (BITS_PER_LONG-size);
found_middle:
	return result + ffz(~tmp);
}

#define find_first_one_bit(addr, size)\
	find_next_one_bit((addr), (size), 0)

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;
	lb_addr loc;

	loc.logicalBlockNum = bitmap->s_extPosition;
	loc.partitionReferenceNum = UDF_SB_PARTITION(sb);

	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)\n", 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_bitmap_free_blocks(struct super_block * sb,
	struct inode * inode,
	struct udf_bitmap *bitmap, lb_addr bloc, uint32_t offset, uint32_t count)
{
	struct buffer_head * bh = NULL;
	unsigned long block;
	unsigned long block_group;
	unsigned long bit;
	unsigned long i;
	int bitmap_nr;
	unsigned long overflow;

	lock_kernel();
	if (bloc.logicalBlockNum < 0 ||
		(bloc.logicalBlockNum + count) > UDF_SB_PARTLEN(sb, bloc.partitionReferenceNum))
	{
		udf_debug("%d < %d || %d + %d > %d\n",
			bloc.logicalBlockNum, 0, bloc.logicalBlockNum, count,
			UDF_SB_PARTLEN(sb, bloc.partitionReferenceNum));
		goto error_return;
	}

	block = bloc.logicalBlockNum + offset + (sizeof(struct spaceBitmapDesc) << 3);

do_more:
	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\n", bit + i);
			udf_debug("byte=%2x\n", ((char *)bh->b_data)[(bit + i) >> 3]);
		}
		else
		{
			if (inode)
				DQUOT_FREE_BLOCK(inode, 1);
			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)])+1);
			}
		}
	}
	mark_buffer_dirty(bh);
	if (overflow)
	{
		block += count;
		count = overflow;
		goto do_more;
	}
error_return:
	sb->s_dirt = 1;
	if (UDF_SB_LVIDBH(sb))
		mark_buffer_dirty(UDF_SB_LVIDBH(sb));
	unlock_kernel();
	return;
}

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)
{
	int alloc_count = 0;
	int bit, block, block_group, group_start;
	int nr_groups, bitmap_nr;
	struct buffer_head *bh;

	lock_kernel();

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

	if (first_block + block_count > UDF_SB_PARTLEN(sb, partition))
		block_count = UDF_SB_PARTLEN(sb, partition) - first_block;

repeat:
	nr_groups = (UDF_SB_PARTLEN(sb, partition) +
		(sizeof(struct spaceBitmapDesc) << 3) + (sb->s_blocksize * 8) - 1) / (sb->s_blocksize * 8);
	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_test_bit(bit, bh->b_data))
			goto out;
		else if (DQUOT_PREALLOC_BLOCK(inode, 1))
			goto out;
		else if (!udf_clear_bit(bit, bh->b_data))
		{
			udf_debug("bit already cleared for block %d\n", bit);
			DQUOT_FREE_BLOCK(inode, 1);
			goto out;
		}
		block_count --;
		alloc_count ++;
		bit ++;
		block ++;
	}
	mark_buffer_dirty(bh);
	if (block_count > 0)
		goto repeat;
out:
	if (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;
	unlock_kernel();
	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)
{
	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;
	lock_kernel();

repeat:
	if (goal < 0 || goal >= UDF_SB_PARTLEN(sb, partition))
		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((char *)bh->b_data, sb->s_blocksize << 3, group_start << 3);
			if (bit < sb->s_blocksize << 3)
				break;
		}
	}
	if (i >= (nr_groups*2))
	{
		unlock_kernel();
		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)
	{
		unlock_kernel();
		return 0;
	}

search_back:
	for (i=0; i<7 && bit > (group_start << 3) && udf_test_bit(bit - 1, bh->b_data); i++, bit--);

got_block:

	/*
	 * Check quota for allocation of this block.
	 */
	if (inode && DQUOT_ALLOC_BLOCK(inode, 1))
	{
		unlock_kernel();
		*err = -EDQUOT;
		return 0;
	}

	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\n", bit);
		goto repeat;
	}

	mark_buffer_dirty(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;
	unlock_kernel();
	*err = 0;
	return newblock;

error_return:
	*err = -EIO;
	unlock_kernel();
	return 0;
}

static void udf_table_free_blocks(struct super_block * sb,
	struct inode * inode,
	struct inode * table, lb_addr bloc, uint32_t offset, uint32_t count)
{
	uint32_t start, end;
	uint32_t nextoffset, oextoffset, elen;
	lb_addr nbloc, obloc, eloc;
	struct buffer_head *obh, *nbh;
	int8_t etype;
	int i;

	lock_kernel();
	if (bloc.logicalBlockNum < 0 ||
		(bloc.logicalBlockNum + count) > UDF_SB_PARTLEN(sb, bloc.partitionReferenceNum))
	{
		udf_debug("%d < %d || %d + %d > %d\n",
			bloc.logicalBlockNum, 0, bloc.logicalBlockNum, count,
			UDF_SB_PARTLEN(sb, bloc.partitionReferenceNum));
		goto error_return;
	}

	/* We do this up front - There are some error conditions that could occure,
	   but.. oh well */
	if (inode)
		DQUOT_FREE_BLOCK(inode, count);
	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;

	oextoffset = nextoffset = sizeof(struct unallocSpaceEntry);
	elen = 0;
	obloc = nbloc = UDF_I_LOCATION(table);

	obh = nbh = NULL;

	while (count && (etype =
		udf_next_aext(table, &nbloc, &nextoffset, &eloc, &elen, &nbh, 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