super.c

讲述linux的初始化过程

		udf_debug("Validity check skipped because of novrs option\n");
		return 0;
	}
	/* Check that it is NSR02 compliant */
	/* Process any "CD-ROM Volume Descriptor Set" (ECMA 167 2/8.3.1) */
	else if ((block = udf_vrs(sb, silent)) == -1)
	{
		udf_debug("Failed to read byte 32768. Assuming open disc. Skipping validity check\n");
		return 0;
	}
	else 
		return !block;
}

static int
udf_load_partition(struct super_block *sb, lb_addr *fileset)
{
	struct AnchorVolDescPtr *anchor;
	Uint16 ident;
	struct buffer_head *bh;
	long main_s, main_e, reserve_s, reserve_e;
	int i, j;

	if (!sb)
		return 1;

	for (i=0; i<sizeof(UDF_SB_ANCHOR(sb))/sizeof(int); i++)
	{
		if (UDF_SB_ANCHOR(sb)[i] && (bh = udf_read_tagged(sb,
			UDF_SB_ANCHOR(sb)[i], UDF_SB_ANCHOR(sb)[i] - UDF_SB_SESSION(sb), &ident)))
		{
			anchor = (struct AnchorVolDescPtr *)bh->b_data;

			/* Locate the main sequence */
			main_s = le32_to_cpu( anchor->mainVolDescSeqExt.extLocation );
			main_e = le32_to_cpu( anchor->mainVolDescSeqExt.extLength );
			main_e = main_e >> sb->s_blocksize_bits;
			main_e += main_s;
	
			/* Locate the reserve sequence */
			reserve_s = le32_to_cpu(anchor->reserveVolDescSeqExt.extLocation);
			reserve_e = le32_to_cpu(anchor->reserveVolDescSeqExt.extLength);
			reserve_e = reserve_e >> sb->s_blocksize_bits;
			reserve_e += reserve_s;

			udf_release_data(bh);

			/* Process the main & reserve sequences */
			/* responsible for finding the PartitionDesc(s) */
			if (!(udf_process_sequence(sb, main_s, main_e, fileset) &&
				udf_process_sequence(sb, reserve_s, reserve_e, fileset)))
			{
				break;
			}
		}
	}

	if (i == sizeof(UDF_SB_ANCHOR(sb))/sizeof(int))
	{
		udf_debug("No Anchor block found\n");
		return 1;
	}
	else
		udf_debug("Using anchor in block %d\n", UDF_SB_ANCHOR(sb)[i]);

	for (i=0; i<UDF_SB_NUMPARTS(sb); i++)
	{
		switch UDF_SB_PARTTYPE(sb, i)
		{
			case UDF_VIRTUAL_MAP15:
			case UDF_VIRTUAL_MAP20:
			{
				lb_addr ino;

				if (!UDF_SB_LASTBLOCK(sb))
				{
					udf_debug("Unable to determine Lastblock (For Virtual Partition)\n");
					return 1;
				}

				for (j=0; j<UDF_SB_NUMPARTS(sb); j++)
				{
					if (j != i &&
						UDF_SB_PARTVSN(sb,i) == UDF_SB_PARTVSN(sb,j) &&
						UDF_SB_PARTNUM(sb,i) == UDF_SB_PARTNUM(sb,j))
					{
							ino.partitionReferenceNum = j;
							ino.logicalBlockNum = UDF_SB_LASTBLOCK(sb) -
								UDF_SB_PARTROOT(sb,j);
							break;
					}
				}

				if (j == UDF_SB_NUMPARTS(sb))
					return 1;

				if (!(UDF_SB_VAT(sb) = udf_iget(sb, ino)))
					return 1;

				if (UDF_SB_PARTTYPE(sb,i) == UDF_VIRTUAL_MAP15)
				{
					UDF_SB_TYPEVIRT(sb,i).s_start_offset = udf_ext0_offset(UDF_SB_VAT(sb));
					UDF_SB_TYPEVIRT(sb,i).s_num_entries = (UDF_SB_VAT(sb)->i_size - 36) >> 2;
				}
				else if (UDF_SB_PARTTYPE(sb,i) == UDF_VIRTUAL_MAP20)
				{
					struct buffer_head *bh = NULL;
					Uint32 pos;

					pos = udf_block_map(UDF_SB_VAT(sb), 0);
					bh = bread(sb->s_dev, pos, sb->s_blocksize);
					UDF_SB_TYPEVIRT(sb,i).s_start_offset =
						le16_to_cpu(((struct VirtualAllocationTable20 *)bh->b_data + udf_ext0_offset(UDF_SB_VAT(sb)))->lengthHeader) +
							udf_ext0_offset(UDF_SB_VAT(sb));
					UDF_SB_TYPEVIRT(sb,i).s_num_entries = (UDF_SB_VAT(sb)->i_size -
						UDF_SB_TYPEVIRT(sb,i).s_start_offset) >> 2;
					udf_release_data(bh);
				}
				UDF_SB_PARTROOT(sb,i) = udf_get_pblock(sb, 0, i, 0);
				UDF_SB_PARTLEN(sb,i) = UDF_SB_PARTLEN(sb,ino.partitionReferenceNum);
			}
		}
	}
	return 0;
}

static void udf_open_lvid(struct super_block *sb)
{
	if (UDF_SB_LVIDBH(sb))
	{
		int i;
		timestamp cpu_time;

		UDF_SB_LVIDIU(sb)->impIdent.identSuffix[0] = UDF_OS_CLASS_UNIX;
		UDF_SB_LVIDIU(sb)->impIdent.identSuffix[1] = UDF_OS_ID_LINUX;
		if (udf_time_to_stamp(&cpu_time, CURRENT_TIME, CURRENT_UTIME))
			UDF_SB_LVID(sb)->recordingDateAndTime = cpu_to_lets(cpu_time);
		UDF_SB_LVID(sb)->integrityType = INTEGRITY_TYPE_OPEN;

		UDF_SB_LVID(sb)->descTag.descCRC =
			cpu_to_le16(udf_crc((char *)UDF_SB_LVID(sb) + sizeof(tag),
			le16_to_cpu(UDF_SB_LVID(sb)->descTag.descCRCLength), 0));

		UDF_SB_LVID(sb)->descTag.tagChecksum = 0;
		for (i=0; i<16; i++)
			if (i != 4)
				UDF_SB_LVID(sb)->descTag.tagChecksum +=
					((Uint8 *)&(UDF_SB_LVID(sb)->descTag))[i];

		mark_buffer_dirty(UDF_SB_LVIDBH(sb));
		sb->s_dirt = 0;
	}
}

static void udf_close_lvid(struct super_block *sb)
{
	if (UDF_SB_LVIDBH(sb) &&
		UDF_SB_LVID(sb)->integrityType == INTEGRITY_TYPE_OPEN)
	{
		int i;
		timestamp cpu_time;

		UDF_SB_LVIDIU(sb)->impIdent.identSuffix[0] = UDF_OS_CLASS_UNIX;
		UDF_SB_LVIDIU(sb)->impIdent.identSuffix[1] = UDF_OS_ID_LINUX;
		if (udf_time_to_stamp(&cpu_time, CURRENT_TIME, CURRENT_UTIME))
			UDF_SB_LVID(sb)->recordingDateAndTime = cpu_to_lets(cpu_time);
		if (UDF_MAX_WRITE_VERSION > le16_to_cpu(UDF_SB_LVIDIU(sb)->maxUDFWriteRev))
			UDF_SB_LVIDIU(sb)->maxUDFWriteRev = cpu_to_le16(UDF_MAX_WRITE_VERSION);
		if (UDF_SB_UDFREV(sb) > le16_to_cpu(UDF_SB_LVIDIU(sb)->minUDFReadRev))
			UDF_SB_LVIDIU(sb)->minUDFReadRev = cpu_to_le16(UDF_SB_UDFREV(sb));
		if (UDF_SB_UDFREV(sb) > le16_to_cpu(UDF_SB_LVIDIU(sb)->minUDFWriteRev))
			UDF_SB_LVIDIU(sb)->minUDFWriteRev = cpu_to_le16(UDF_SB_UDFREV(sb));
		UDF_SB_LVID(sb)->integrityType = INTEGRITY_TYPE_CLOSE;

		UDF_SB_LVID(sb)->descTag.descCRC =
			cpu_to_le16(udf_crc((char *)UDF_SB_LVID(sb) + sizeof(tag),
			le16_to_cpu(UDF_SB_LVID(sb)->descTag.descCRCLength), 0));

		UDF_SB_LVID(sb)->descTag.tagChecksum = 0;
		for (i=0; i<16; i++)
			if (i != 4)
				UDF_SB_LVID(sb)->descTag.tagChecksum +=
					((Uint8 *)&(UDF_SB_LVID(sb)->descTag))[i];

		mark_buffer_dirty(UDF_SB_LVIDBH(sb));
	}
}

/*
 * udf_read_super
 *
 * PURPOSE
 *	Complete the specified super block.
 *
 * PRE-CONDITIONS
 *	sb			Pointer to superblock to complete - never NULL.
 *	sb->s_dev		Device to read suberblock from.
 *	options			Pointer to mount options.
 *	silent			Silent flag.
 *
 * HISTORY
 *	July 1, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 */
static struct super_block *
udf_read_super(struct super_block *sb, void *options, int silent)
{
	struct inode *inode=NULL;
	struct udf_options uopt;
	lb_addr rootdir, fileset;
	int i;

	uopt.flags = (1 << UDF_FLAG_USE_AD_IN_ICB);
	uopt.uid = -1;
	uopt.gid = -1;
	uopt.umask = 0;

	memset(UDF_SB(sb), 0x00, sizeof(struct udf_sb_info));

#if CONFIG_UDF_RW != 1
	sb->s_flags |= MS_RDONLY;
#endif

	if (!udf_parse_options((char *)options, &uopt))
		goto error_out;

	fileset.logicalBlockNum = 0xFFFFFFFF;
	fileset.partitionReferenceNum = 0xFFFF;

	UDF_SB(sb)->s_flags = uopt.flags;
	UDF_SB(sb)->s_uid = uopt.uid;
	UDF_SB(sb)->s_gid = uopt.gid;
	UDF_SB(sb)->s_umask = uopt.umask;

	/* Set the block size for all transfers */
	if (!udf_set_blocksize(sb, uopt.blocksize))
		goto error_out;

	if ( uopt.session == 0xFFFFFFFF )
		UDF_SB_SESSION(sb) = udf_get_last_session(sb);
	else
		UDF_SB_SESSION(sb) = uopt.session;

	udf_debug("Multi-session=%d\n", UDF_SB_SESSION(sb));

	if ( uopt.lastblock == 0xFFFFFFFF )
		UDF_SB_LASTBLOCK(sb) = udf_get_last_block(sb);
	else
		UDF_SB_LASTBLOCK(sb) = uopt.lastblock;

	UDF_SB_LASTBLOCK(sb) = udf_find_anchor(sb, uopt.anchor, UDF_SB_LASTBLOCK(sb));

	udf_debug("Lastblock=%d\n", UDF_SB_LASTBLOCK(sb));

	if (udf_check_valid(sb, uopt.novrs, silent)) /* read volume recognition sequences */
	{
		printk("UDF-fs: No VRS found\n");
 		goto error_out;
	}

	/* Fill in the rest of the superblock */
	sb->s_op = &udf_sb_ops;
	sb->dq_op = NULL;
	sb->s_dirt = 0;
	sb->s_magic = UDF_SUPER_MAGIC;

	for (i=0; i<UDF_MAX_BLOCK_LOADED; i++)
	{
		UDF_SB_BLOCK_BITMAP_NUMBER(sb,i) = 0;
		UDF_SB_BLOCK_BITMAP(sb,i) = NULL;
	}
	UDF_SB_LOADED_BLOCK_BITMAPS(sb) = 0;

	if (udf_load_partition(sb, &fileset))
	{
		printk("UDF-fs: No partition found (1)\n");
		goto error_out;
	}

	if ( UDF_SB_LVIDBH(sb) )
	{
		Uint16 minUDFReadRev = le16_to_cpu(UDF_SB_LVIDIU(sb)->minUDFReadRev);
		Uint16 minUDFWriteRev = le16_to_cpu(UDF_SB_LVIDIU(sb)->minUDFWriteRev);
		/* Uint16 maxUDFWriteRev = le16_to_cpu(UDF_SB_LVIDIU(sb)->maxUDFWriteRev); */

		if (minUDFReadRev > UDF_MAX_READ_VERSION)
		{
			printk("UDF-fs: minUDFReadRev=%x (max is %x)\n",
				UDF_SB_LVIDIU(sb)->minUDFReadRev, UDF_MAX_READ_VERSION);
			goto error_out;
		}
		else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION)
		{
			sb->s_flags |= MS_RDONLY;
		}

		if (minUDFReadRev >= UDF_VERS_USE_EXTENDED_FE)
			UDF_SET_FLAG(sb, UDF_FLAG_USE_EXTENDED_FE);
		if (minUDFReadRev >= UDF_VERS_USE_STREAMS)
			UDF_SET_FLAG(sb, UDF_FLAG_USE_STREAMS);
	}

	if ( !UDF_SB_NUMPARTS(sb) )
	{
		printk("UDF-fs: No partition found (2)\n");
		goto error_out;
	}

	if ( udf_find_fileset(sb, &fileset, &rootdir) )
	{
		printk("UDF-fs: No fileset found\n");
		goto error_out;
	}

	if (!silent)
	{
		timestamp ts;
		udf_time_to_stamp(&ts, UDF_SB_RECORDTIME(sb), 0);
		udf_info("UDF %s (%s) Mounting volume '%s', timestamp %04u/%02u/%02u %02u:%02u (%x)\n",
			UDFFS_VERSION, UDFFS_DATE,
			UDF_SB_VOLIDENT(sb), ts.year, ts.month, ts.day, ts.hour, ts.minute,
			ts.typeAndTimezone);
	}
	if (!(sb->s_flags & MS_RDONLY))
		udf_open_lvid(sb);

	/* Assign the root inode */
	/* assign inodes by physical block number */
	/* perhaps it's not extensible enough, but for now ... */
	inode = udf_iget(sb, rootdir); 
	if (!inode)
	{
		printk("UDF-fs: Error in udf_iget, block=%d, partition=%d\n",
			rootdir.logicalBlockNum, rootdir.partitionReferenceNum);
		goto error_out;
	}

	/* Allocate a dentry for the root inode */
	sb->s_root = d_alloc_root(inode);
	if (!sb->s_root)
	{
		printk("UDF-fs: Couldn't allocate root dentry\n");
		iput(inode);
		goto error_out;
	}

	return sb;

error_out:
	if (UDF_SB_VAT(sb))
		iput(UDF_SB_VAT(sb));
	if (!(sb->s_flags & MS_RDONLY))
		udf_close_lvid(sb);
	udf_release_data(UDF_SB_LVIDBH(sb));
	UDF_SB_FREE(sb);
	return NULL;
}

void udf_error(struct super_block *sb, const char *function,
	const char *fmt, ...)
{
	va_list args;

	if (!(sb->s_flags & MS_RDONLY))
	{
		/* mark sb error */
		sb->s_dirt = 1;
	}
	va_start(args, fmt);
	vsprintf(error_buf, fmt, args);
	va_end(args);
	printk (KERN_CRIT "UDF-fs error (device %s): %s: %s\n",
		bdevname(sb->s_dev), function, error_buf);
}

void udf_warning(struct super_block *sb, const char *function,
	const char *fmt, ...)
{
	va_list args;

	va_start (args, fmt);
	vsprintf(error_buf, fmt, args);
	va_end(args);
	printk(KERN_WARNING "UDF-fs warning (device %s): %s: %s\n",
		bdevname(sb->s_dev), function, error_buf);
}

/*
 * udf_put_super
 *
 * PURPOSE
 *	Prepare for destruction of the superblock.
 *
 * DESCRIPTION
 *	Called before the filesystem is unmounted.
 *
 * HISTORY
 *	July 1, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 */
static void
udf_put_super(struct super_block *sb)
{
	int i;

	if (UDF_SB_VAT(sb))
		iput(UDF_SB_VAT(sb));
	if (!(sb->s_flags & MS_RDONLY))
		udf_close_lvid(sb);
	udf_release_data(UDF_SB_LVIDBH(sb));
	for (i=0; i<UDF_MAX_BLOCK_LOADED; i++)
		udf_release_data(UDF_SB_BLOCK_BITMAP(sb, i));
	UDF_SB_FREE(sb);
}

/*
 * udf_stat_fs
 *
 * PURPOSE
 *	Return info about the filesystem.
 *
 * DESCRIPTION
 *	Called by sys_statfs()
 *
 * HISTORY
 *	July 1, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 */
static int
udf_statfs(struct super_block *sb, struct statfs *buf)
{
	buf->f_type = UDF_SUPER_MAGIC;
	buf->f_bsize = sb->s_blocksize;
	buf->f_blocks = UDF_SB_PARTLEN(sb, UDF_SB_PARTITION(sb));
	buf->f_bfree = udf_count_free(sb);
	buf->f_bavail = buf->f_bfree;
	buf->f_files = (UDF_SB_LVIDBH(sb) ?
		(le32_to_cpu(UDF_SB_LVIDIU(sb)->numFiles) +
		le32_to_cpu(UDF_SB_LVIDIU(sb)->numDirs)) : 0) + buf->f_bfree;
	buf->f_ffree = buf->f_bfree;
	/* __kernel_fsid_t f_fsid */
	buf->f_namelen = UDF_NAME_LEN;

	return 0;
}

static unsigned char udf_bitmap_lookup[16] = {
	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4
};
	
static unsigned int
udf_count_free(struct super_block *sb)
{
	struct buffer_head *bh = NULL;
	unsigned int accum = 0;
	lb_addr loc;
	Uint32 bitmap;

	if (UDF_SB_PARTFLAGS(sb,UDF_SB_PARTITION(sb)) & UDF_PART_FLAG_UNALLOC_BITMAP)
		bitmap = UDF_SB_PARTMAPS(sb)[UDF_SB_PARTITION(sb)].s_uspace.bitmap;
	else if (UDF_SB_PARTFLAGS(sb,UDF_SB_PARTITION(sb)) & UDF_PART_FLAG_FREED_BITMAP)
		bitmap = UDF_SB_PARTMAPS(sb)[UDF_SB_PARTITION(sb)].s_fspace.bitmap;
	else
		bitmap = 0xFFFFFFFF;

	if (bitmap != 0xFFFFFFFF)
	{
		struct SpaceBitmapDesc *bm;
		int block = 0, newblock, index;
		Uint16 ident;
		Uint32 bytes;
		Uint8 value;
		Uint8 * ptr;

		loc.logicalBlockNum = bitmap;
		loc.partitionReferenceNum = UDF_SB_PARTITION(sb);
		bh = udf_read_ptagged(sb, loc, 0, &ident);

		if (!bh)
		{
			printk(KERN_ERR "udf: udf_count_free failed\n");
			return 0;
		}
		else if (ident != TID_SPACE_BITMAP_DESC)
		{
			udf_release_data(bh);
			printk(KERN_ERR "udf: udf_count_free failed\n");
			return 0;
		}

		bm = (struct SpaceBitmapDesc *)bh->b_data;
		bytes = bm->numOfBytes;
		index = sizeof(struct SpaceBitmapDesc); /* offset in first block only */
		ptr = (Uint8 *)bh->b_data;

		while ( bytes > 0 )
		{
			while ((bytes > 0) && (index < sb->s_blocksize))
			{
				value = ptr[index];
				accum += udf_bitmap_lookup[ value & 0x0f ];
				accum += udf_bitmap_lookup[ value >> 4 ];
				index++;
				bytes--;
			}
			if ( bytes )
			{
				udf_release_data(bh);
				newblock = udf_get_lb_pblock(sb, loc, ++block);
				bh = udf_tread(sb, newblock, sb->s_blocksize);
				if (!bh)
				{
					udf_debug("read failed\n");
					return accum;
				}
				index = 0;
				ptr = (Uint8 *)bh->b_data;
			}
		}
		udf_release_data(bh);
	}
	else
	{
		if (UDF_SB_LVIDBH(sb))
		{
			if (le32_to_cpu(UDF_SB_LVID(sb)->numOfPartitions) > UDF_SB_PARTITION(sb))
				accum = le32_to_cpu(UDF_SB_LVID(sb)->freeSpaceTable[UDF_SB_PARTITION(sb)]);

			if (accum == 0xFFFFFFFF)
				accum = 0;
		}
	}

	return accum;
}