balloc.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

	uspi = sb->u.ufs_sb.s_uspi;
	usb1 = ubh_get_usb_first (USPI_UBH);
	count = newcount - oldcount;
	
	cgno = ufs_dtog(fragment);
	if (sb->fs_cs(cgno).cs_nffree < count)
		return 0;
	if ((ufs_fragnum (fragment) + newcount) > uspi->s_fpb)
		return 0;
	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi)
		return 0;
	ucg = ubh_get_ucg (UCPI_UBH);
	if (!ufs_cg_chkmagic(sb, ucg)) {
		ufs_panic (sb, "ufs_add_fragments",
			"internal error, bad magic number on cg %u", cgno);
		return 0;
	}

	fragno = ufs_dtogd (fragment);
	fragoff = ufs_fragnum (fragno);
	for (i = oldcount; i < newcount; i++)
		if (ubh_isclr (UCPI_UBH, ucpi->c_freeoff, fragno + i))
			return 0;
	/*
	 * Block can be extended
	 */
	ucg->cg_time = cpu_to_fs32(sb, CURRENT_TIME);
	for (i = newcount; i < (uspi->s_fpb - fragoff); i++)
		if (ubh_isclr (UCPI_UBH, ucpi->c_freeoff, fragno + i))
			break;
	fragsize = i - oldcount;
	if (!fs32_to_cpu(sb, ucg->cg_frsum[fragsize]))
		ufs_panic (sb, "ufs_add_fragments",
			"internal error or corrupted bitmap on cg %u", cgno);
	fs32_sub(sb, &ucg->cg_frsum[fragsize], 1);
	if (fragsize != count)
		fs32_add(sb, &ucg->cg_frsum[fragsize - count], 1);
	for (i = oldcount; i < newcount; i++)
		ubh_clrbit (UCPI_UBH, ucpi->c_freeoff, fragno + i);
	if(DQUOT_ALLOC_BLOCK(inode, count)) {
		*err = -EDQUOT;
		return 0;
	}

	fs32_sub(sb, &ucg->cg_cs.cs_nffree, count);
	fs32_sub(sb, &sb->fs_cs(cgno).cs_nffree, count);
	fs32_sub(sb, &usb1->fs_cstotal.cs_nffree, count);
	
	ubh_mark_buffer_dirty (USPI_UBH);
	ubh_mark_buffer_dirty (UCPI_UBH);
	if (sb->s_flags & MS_SYNCHRONOUS) {
		ubh_ll_rw_block (WRITE, 1, (struct ufs_buffer_head **)&ucpi);
		ubh_wait_on_buffer (UCPI_UBH);
	}
	sb->s_dirt = 1;

	UFSD(("EXIT, fragment %u\n", fragment))
	
	return fragment;
}

#define UFS_TEST_FREE_SPACE_CG \
	ucg = (struct ufs_cylinder_group *) sb->u.ufs_sb.s_ucg[cgno]->b_data; \
	if (fs32_to_cpu(sb, ucg->cg_cs.cs_nbfree)) \
		goto cg_found; \
	for (k = count; k < uspi->s_fpb; k++) \
		if (fs32_to_cpu(sb, ucg->cg_frsum[k])) \
			goto cg_found; 

unsigned ufs_alloc_fragments (struct inode * inode, unsigned cgno,
	unsigned goal, unsigned count, int * err)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	unsigned oldcg, i, j, k, result, allocsize;
	
	UFSD(("ENTER, ino %lu, cgno %u, goal %u, count %u\n", inode->i_ino, cgno, goal, count))

	sb = inode->i_sb;
	uspi = sb->u.ufs_sb.s_uspi;
	usb1 = ubh_get_usb_first(USPI_UBH);
	oldcg = cgno;
	
	/*
	 * 1. searching on preferred cylinder group
	 */
	UFS_TEST_FREE_SPACE_CG

	/*
	 * 2. quadratic rehash
	 */
	for (j = 1; j < uspi->s_ncg; j *= 2) {
		cgno += j;
		if (cgno >= uspi->s_ncg) 
			cgno -= uspi->s_ncg;
		UFS_TEST_FREE_SPACE_CG
	}

	/*
	 * 3. brute force search
	 * We start at i = 2 ( 0 is checked at 1.step, 1 at 2.step )
	 */
	cgno = (oldcg + 1) % uspi->s_ncg;
	for (j = 2; j < uspi->s_ncg; j++) {
		cgno++;
		if (cgno >= uspi->s_ncg)
			cgno = 0;
		UFS_TEST_FREE_SPACE_CG
	}
	
	UFSD(("EXIT (FAILED)\n"))
	return 0;

cg_found:
	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi)
		return 0;
	ucg = ubh_get_ucg (UCPI_UBH);
	if (!ufs_cg_chkmagic(sb, ucg)) 
		ufs_panic (sb, "ufs_alloc_fragments",
			"internal error, bad magic number on cg %u", cgno);
	ucg->cg_time = cpu_to_fs32(sb, CURRENT_TIME);

	if (count == uspi->s_fpb) {
		result = ufs_alloccg_block (inode, ucpi, goal, err);
		if (result == (unsigned)-1)
			return 0;
		goto succed;
	}

	for (allocsize = count; allocsize < uspi->s_fpb; allocsize++)
		if (fs32_to_cpu(sb, ucg->cg_frsum[allocsize]) != 0)
			break;
	
	if (allocsize == uspi->s_fpb) {
		result = ufs_alloccg_block (inode, ucpi, goal, err);
		if (result == (unsigned)-1)
			return 0;
		goal = ufs_dtogd (result);
		for (i = count; i < uspi->s_fpb; i++)
			ubh_setbit (UCPI_UBH, ucpi->c_freeoff, goal + i);
		i = uspi->s_fpb - count;
		DQUOT_FREE_BLOCK(inode, i);

		fs32_add(sb, &ucg->cg_cs.cs_nffree, i);
		fs32_add(sb, &usb1->fs_cstotal.cs_nffree, i);
		fs32_add(sb, &sb->fs_cs(cgno).cs_nffree, i);
		fs32_add(sb, &ucg->cg_frsum[i], 1);
		goto succed;
	}

	result = ufs_bitmap_search (sb, ucpi, goal, allocsize);
	if (result == (unsigned)-1)
		return 0;
	if(DQUOT_ALLOC_BLOCK(inode, count)) {
		*err = -EDQUOT;
		return 0;
	}
	for (i = 0; i < count; i++)
		ubh_clrbit (UCPI_UBH, ucpi->c_freeoff, result + i);
	
	fs32_sub(sb, &ucg->cg_cs.cs_nffree, count);
	fs32_sub(sb, &usb1->fs_cstotal.cs_nffree, count);
	fs32_sub(sb, &sb->fs_cs(cgno).cs_nffree, count);
	fs32_sub(sb, &ucg->cg_frsum[allocsize], 1);

	if (count != allocsize)
		fs32_add(sb, &ucg->cg_frsum[allocsize - count], 1);

succed:
	ubh_mark_buffer_dirty (USPI_UBH);
	ubh_mark_buffer_dirty (UCPI_UBH);
	if (sb->s_flags & MS_SYNCHRONOUS) {
		ubh_ll_rw_block (WRITE, 1, (struct ufs_buffer_head **)&ucpi);
		ubh_wait_on_buffer (UCPI_UBH);
	}
	sb->s_dirt = 1;

	result += cgno * uspi->s_fpg;
	UFSD(("EXIT3, result %u\n", result))
	return result;
}

unsigned ufs_alloccg_block (struct inode * inode,
	struct ufs_cg_private_info * ucpi, unsigned goal, int * err)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cylinder_group * ucg;
	unsigned result, cylno, blkno;

	UFSD(("ENTER, goal %u\n", goal))

	sb = inode->i_sb;
	uspi = sb->u.ufs_sb.s_uspi;
	usb1 = ubh_get_usb_first(USPI_UBH);
	ucg = ubh_get_ucg(UCPI_UBH);

	if (goal == 0) {
		goal = ucpi->c_rotor;
		goto norot;
	}
	goal = ufs_blknum (goal);
	goal = ufs_dtogd (goal);
	
	/*
	 * If the requested block is available, use it.
	 */
	if (ubh_isblockset(UCPI_UBH, ucpi->c_freeoff, ufs_fragstoblks(goal))) {
		result = goal;
		goto gotit;
	}
	
norot:	
	result = ufs_bitmap_search (sb, ucpi, goal, uspi->s_fpb);
	if (result == (unsigned)-1)
		return (unsigned)-1;
	ucpi->c_rotor = result;
gotit:
	blkno = ufs_fragstoblks(result);
	ubh_clrblock (UCPI_UBH, ucpi->c_freeoff, blkno);
	if ((sb->u.ufs_sb.s_flags & UFS_CG_MASK) == UFS_CG_44BSD)
		ufs_clusteracct (sb, ucpi, blkno, -1);
	if(DQUOT_ALLOC_BLOCK(inode, uspi->s_fpb)) {
		*err = -EDQUOT;
		return (unsigned)-1;
	}

	fs32_sub(sb, &ucg->cg_cs.cs_nbfree, 1);
	fs32_sub(sb, &usb1->fs_cstotal.cs_nbfree, 1);
	fs32_sub(sb, &sb->fs_cs(ucpi->c_cgx).cs_nbfree, 1);
	cylno = ufs_cbtocylno(result);
	fs16_sub(sb, &ubh_cg_blks(ucpi, cylno, ufs_cbtorpos(result)), 1);
	fs32_sub(sb, &ubh_cg_blktot(ucpi, cylno), 1);
	
	UFSD(("EXIT, result %u\n", result))

	return result;
}

unsigned ufs_bitmap_search (struct super_block * sb,
	struct ufs_cg_private_info * ucpi, unsigned goal, unsigned count)
{
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cylinder_group * ucg;
	unsigned start, length, location, result;
	unsigned possition, fragsize, blockmap, mask;
	
	UFSD(("ENTER, cg %u, goal %u, count %u\n", ucpi->c_cgx, goal, count))

	uspi = sb->u.ufs_sb.s_uspi;
	usb1 = ubh_get_usb_first (USPI_UBH);
	ucg = ubh_get_ucg(UCPI_UBH);

	if (goal)
		start = ufs_dtogd(goal) >> 3;
	else
		start = ucpi->c_frotor >> 3;
		
	length = ((uspi->s_fpg + 7) >> 3) - start;
	location = ubh_scanc(UCPI_UBH, ucpi->c_freeoff + start, length,
		(uspi->s_fpb == 8) ? ufs_fragtable_8fpb : ufs_fragtable_other,
		1 << (count - 1 + (uspi->s_fpb & 7))); 
	if (location == 0) {
		length = start + 1;
		location = ubh_scanc(UCPI_UBH, ucpi->c_freeoff, length, 
			(uspi->s_fpb == 8) ? ufs_fragtable_8fpb : ufs_fragtable_other,
			1 << (count - 1 + (uspi->s_fpb & 7)));
		if (location == 0) {
			ufs_error (sb, "ufs_bitmap_search",
			"bitmap corrupted on cg %u, start %u, length %u, count %u, freeoff %u\n",
			ucpi->c_cgx, start, length, count, ucpi->c_freeoff);
			return (unsigned)-1;
		}
		start = 0;
	}
	result = (start + length - location) << 3;
	ucpi->c_frotor = result;

	/*
	 * found the byte in the map
	 */
	blockmap = ubh_blkmap(UCPI_UBH, ucpi->c_freeoff, result);
	fragsize = 0;
	for (possition = 0, mask = 1; possition < 8; possition++, mask <<= 1) {
		if (blockmap & mask) {
			if (!(possition & uspi->s_fpbmask))
				fragsize = 1;
			else 
				fragsize++;
		}
		else {
			if (fragsize == count) {
				result += possition - count;
				UFSD(("EXIT, result %u\n", result))
				return result;
			}
			fragsize = 0;
		}
	}
	if (fragsize == count) {
		result += possition - count;
		UFSD(("EXIT, result %u\n", result))
		return result;
	}
	ufs_error (sb, "ufs_bitmap_search", "block not in map on cg %u\n", ucpi->c_cgx);
	UFSD(("EXIT (FAILED)\n"))
	return (unsigned)-1;
}

void ufs_clusteracct(struct super_block * sb, 
	struct ufs_cg_private_info * ucpi, unsigned blkno, int cnt)
{
	struct ufs_sb_private_info * uspi;
	int i, start, end, forw, back;
	
	uspi = sb->u.ufs_sb.s_uspi;
	if (uspi->s_contigsumsize <= 0)
		return;

	if (cnt > 0)
		ubh_setbit(UCPI_UBH, ucpi->c_clusteroff, blkno);
	else
		ubh_clrbit(UCPI_UBH, ucpi->c_clusteroff, blkno);

	/*
	 * Find the size of the cluster going forward.
	 */
	start = blkno + 1;
	end = start + uspi->s_contigsumsize;
	if ( end >= ucpi->c_nclusterblks)
		end = ucpi->c_nclusterblks;
	i = ubh_find_next_zero_bit (UCPI_UBH, ucpi->c_clusteroff, end, start);
	if (i > end)
		i = end;
	forw = i - start;
	
	/*
	 * Find the size of the cluster going backward.
	 */
	start = blkno - 1;
	end = start - uspi->s_contigsumsize;
	if (end < 0 ) 
		end = -1;
	i = ubh_find_last_zero_bit (UCPI_UBH, ucpi->c_clusteroff, start, end);
	if ( i < end) 
		i = end;
	back = start - i;
	
	/*
	 * Account for old cluster and the possibly new forward and
	 * back clusters.
	 */
	i = back + forw + 1;
	if (i > uspi->s_contigsumsize)
		i = uspi->s_contigsumsize;
	fs32_add(sb, (u32*)ubh_get_addr(UCPI_UBH, ucpi->c_clustersumoff + (i << 2)), cnt);
	if (back > 0)
		fs32_sub(sb, (u32*)ubh_get_addr(UCPI_UBH, ucpi->c_clustersumoff + (back << 2)), cnt);
	if (forw > 0)
		fs32_sub(sb, (u32*)ubh_get_addr(UCPI_UBH, ucpi->c_clustersumoff + (forw << 2)), cnt);
}


static unsigned char ufs_fragtable_8fpb[] = {
	0x00, 0x01, 0x01, 0x02, 0x01, 0x01, 0x02, 0x04, 0x01, 0x01, 0x01, 0x03, 0x02, 0x03, 0x04, 0x08,
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x02, 0x03, 0x03, 0x02, 0x04, 0x05, 0x08, 0x10,
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x01, 0x01, 0x01, 0x03, 0x03, 0x03, 0x05, 0x09,
	0x02, 0x03, 0x03, 0x02, 0x03, 0x03, 0x02, 0x06, 0x04, 0x05, 0x05, 0x06, 0x08, 0x09, 0x10, 0x20,
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x01, 0x01, 0x01, 0x03, 0x03, 0x03, 0x05, 0x09,	
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x03, 0x03, 0x03, 0x03, 0x05, 0x05, 0x09, 0x11,
	0x02, 0x03, 0x03, 0x02, 0x03, 0x03, 0x02, 0x06, 0x03, 0x03, 0x03, 0x03, 0x02, 0x03, 0x06, 0x0A,
	0x04, 0x05, 0x05, 0x06, 0x05, 0x05, 0x06, 0x04, 0x08, 0x09, 0x09, 0x0A, 0x10, 0x11, 0x20, 0x40,
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x01, 0x01, 0x01, 0x03, 0x03, 0x03, 0x05, 0x09,
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x03, 0x03, 0x03, 0x03, 0x05, 0x05, 0x09, 0x11,
	0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x03, 0x05, 0x01, 0x01, 0x01, 0x03, 0x03, 0x03, 0x05, 0x09,
	0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x07, 0x05, 0x05, 0x05, 0x07, 0x09, 0x09, 0x11, 0x21,
	0x02, 0x03, 0x03, 0x02, 0x03, 0x03, 0x02, 0x06, 0x03, 0x03, 0x03, 0x03, 0x02, 0x03, 0x06, 0x0A,
	0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x07, 0x02, 0x03, 0x03, 0x02, 0x06, 0x07, 0x0A, 0x12,
	0x04, 0x05, 0x05, 0x06, 0x05, 0x05, 0x06, 0x04, 0x05, 0x05, 0x05, 0x07, 0x06, 0x07, 0x04, 0x0C,
	0x08, 0x09, 0x09, 0x0A, 0x09, 0x09, 0x0A, 0x0C, 0x10, 0x11, 0x11, 0x12, 0x20, 0x21, 0x40, 0x80,
};

static unsigned char ufs_fragtable_other[] = {
	0x00, 0x16, 0x16, 0x2A, 0x16, 0x16, 0x26, 0x4E, 0x16, 0x16, 0x16, 0x3E, 0x2A, 0x3E, 0x4E, 0x8A,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x2A, 0x3E, 0x3E, 0x2A, 0x3E, 0x3E, 0x2E, 0x6E, 0x3E, 0x3E, 0x3E, 0x3E, 0x2A, 0x3E, 0x6E, 0xAA,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x26, 0x36, 0x36, 0x2E, 0x36, 0x36, 0x26, 0x6E, 0x36, 0x36, 0x36, 0x3E, 0x2E, 0x3E, 0x6E, 0xAE,
	0x4E, 0x5E, 0x5E, 0x6E, 0x5E, 0x5E, 0x6E, 0x4E, 0x5E, 0x5E, 0x5E, 0x7E, 0x6E, 0x7E, 0x4E, 0xCE,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x16, 0x16, 0x16, 0x3E, 0x16, 0x16, 0x36, 0x5E, 0x16, 0x16, 0x16, 0x3E, 0x3E, 0x3E, 0x5E, 0x9E,
	0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x7E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x7E, 0xBE,
	0x2A, 0x3E, 0x3E, 0x2A, 0x3E, 0x3E, 0x2E, 0x6E, 0x3E, 0x3E, 0x3E, 0x3E, 0x2A, 0x3E, 0x6E, 0xAA,
	0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x7E,	0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x7E, 0xBE,
	0x4E, 0x5E, 0x5E, 0x6E, 0x5E, 0x5E, 0x6E, 0x4E, 0x5E, 0x5E, 0x5E, 0x7E, 0x6E, 0x7E, 0x4E, 0xCE,
	0x8A, 0x9E, 0x9E, 0xAA, 0x9E, 0x9E, 0xAE, 0xCE, 0x9E, 0x9E, 0x9E, 0xBE, 0xAA, 0xBE, 0xCE, 0x8A,
};