/*
   *  linux/fs/hfsplus/wrapper.c
   *
   * Copyright (C) 2001
   * Brad Boyer (flar@allandria.com)
   * (C) 2003 Ardis Technologies <roman@ardistech.com>
   *
   * Handling of HFS wrappers around HFS+ volumes
   */
  
  #include <linux/fs.h>
  #include <linux/blkdev.h>
  #include <linux/cdrom.h>
  #include <linux/genhd.h>
  #include <asm/unaligned.h>
  
  #include "hfsplus_fs.h"
  #include "hfsplus_raw.h"
  
  struct hfsplus_wd {
  	u32 ablk_size;
  	u16 ablk_start;
  	u16 embed_start;
  	u16 embed_count;
  };
  
  /*
   * hfsplus_submit_bio - Perfrom block I/O
   * @sb: super block of volume for I/O
   * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
   * @buf: buffer for I/O
   * @data: output pointer for location of requested data
   * @rw: direction of I/O
   *
   * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
   * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
   * @data will return a pointer to the start of the requested sector,
   * which may not be the same location as @buf.
   *
   * If @sector is not aligned to the bdev logical block size it will
   * be rounded down. For writes this means that @buf should contain data
   * that starts at the rounded-down address. As long as the data was
   * read using hfsplus_submit_bio() and the same buffer is used things
   * will work correctly.
   */
  int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
  		void *buf, void **data, int rw)
  {
  	struct bio *bio;
  	int ret = 0;
  	u64 io_size;
  	loff_t start;
  	int offset;
  
  	/*
  	 * Align sector to hardware sector size and find offset. We
  	 * assume that io_size is a power of two, which _should_
  	 * be true.
  	 */
  	io_size = hfsplus_min_io_size(sb);
  	start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
  	offset = start & (io_size - 1);
  	sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
  
  	bio = bio_alloc(GFP_NOIO, 1);
  	bio->bi_iter.bi_sector = sector;
  	bio->bi_bdev = sb->s_bdev;
  
  	if (!(rw & WRITE) && data)
  		*data = (u8 *)buf + offset;
  
  	while (io_size > 0) {
  		unsigned int page_offset = offset_in_page(buf);
  		unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
  					 io_size);
  
  		ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
  		if (ret != len) {
  			ret = -EIO;
  			goto out;
  		}
  		io_size -= len;
  		buf = (u8 *)buf + len;
  	}
  
  	ret = submit_bio_wait(rw, bio);
  out:
  	bio_put(bio);
  	return ret < 0 ? ret : 0;
  }
  
  static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
  {
  	u32 extent;
  	u16 attrib;
  	__be16 sig;
  
  	sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
  	if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
  	    sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
  		return 0;
  
  	attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
  	if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
  	   !(attrib & HFSP_WRAP_ATTRIB_SPARED))
  		return 0;
  
  	wd->ablk_size =
  		be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
  	if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
  		return 0;
  	if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
  		return 0;
  	wd->ablk_start =
  		be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
  
  	extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
  	wd->embed_start = (extent >> 16) & 0xFFFF;
  	wd->embed_count = extent & 0xFFFF;
  
  	return 1;
  }
  
  static int hfsplus_get_last_session(struct super_block *sb,
  				    sector_t *start, sector_t *size)
  {
  	struct cdrom_multisession ms_info;
  	struct cdrom_tocentry te;
  	int res;
  
  	/* default values */
  	*start = 0;
  	*size = sb->s_bdev->bd_inode->i_size >> 9;
  
  	if (HFSPLUS_SB(sb)->session >= 0) {
  		te.cdte_track = HFSPLUS_SB(sb)->session;
  		te.cdte_format = CDROM_LBA;
  		res = ioctl_by_bdev(sb->s_bdev,
  			CDROMREADTOCENTRY, (unsigned long)&te);
  		if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
  			*start = (sector_t)te.cdte_addr.lba << 2;
  			return 0;
  		}
  		pr_err("invalid session number or type of track
  ");
  		return -EINVAL;
  	}
  	ms_info.addr_format = CDROM_LBA;
  	res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION,
  		(unsigned long)&ms_info);
  	if (!res && ms_info.xa_flag)
  		*start = (sector_t)ms_info.addr.lba << 2;
  	return 0;
  }
  
  /* Find the volume header and fill in some minimum bits in superblock */
  /* Takes in super block, returns true if good data read */
  int hfsplus_read_wrapper(struct super_block *sb)
  {
  	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
  	struct hfsplus_wd wd;
  	sector_t part_start, part_size;
  	u32 blocksize;
  	int error = 0;
  
  	error = -EINVAL;
  	blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
  	if (!blocksize)
  		goto out;
  
  	if (hfsplus_get_last_session(sb, &part_start, &part_size))
  		goto out;
  
  	error = -ENOMEM;
  	sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
  	if (!sbi->s_vhdr_buf)
  		goto out;
  	sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
  	if (!sbi->s_backup_vhdr_buf)
  		goto out_free_vhdr;
  
  reread:
  	error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
  				   sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
  				   READ);
  	if (error)
  		goto out_free_backup_vhdr;
  
  	error = -EINVAL;
  	switch (sbi->s_vhdr->signature) {
  	case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
  		set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
  		/*FALLTHRU*/
  	case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
  		break;
  	case cpu_to_be16(HFSP_WRAP_MAGIC):
  		if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
  			goto out_free_backup_vhdr;
  		wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
  		part_start += (sector_t)wd.ablk_start +
  			       (sector_t)wd.embed_start * wd.ablk_size;
  		part_size = (sector_t)wd.embed_count * wd.ablk_size;
  		goto reread;
  	default:
  		/*
  		 * Check for a partition block.
  		 *
  		 * (should do this only for cdrom/loop though)
  		 */
  		if (hfs_part_find(sb, &part_start, &part_size))
  			goto out_free_backup_vhdr;
  		goto reread;
  	}
  
  	error = hfsplus_submit_bio(sb, part_start + part_size - 2,
  				   sbi->s_backup_vhdr_buf,
  				   (void **)&sbi->s_backup_vhdr, READ);
  	if (error)
  		goto out_free_backup_vhdr;
  
  	error = -EINVAL;
  	if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
  		pr_warn("invalid secondary volume header
  ");
  		goto out_free_backup_vhdr;
  	}
  
  	blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
  
  	/*
  	 * Block size must be at least as large as a sector and a multiple of 2.
  	 */
  	if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
  		goto out_free_backup_vhdr;
  	sbi->alloc_blksz = blocksize;
  	sbi->alloc_blksz_shift = 0;
  	while ((blocksize >>= 1) != 0)
  		sbi->alloc_blksz_shift++;
  	blocksize = min(sbi->alloc_blksz, (u32)PAGE_SIZE);
  
  	/*
  	 * Align block size to block offset.
  	 */
  	while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
  		blocksize >>= 1;
  
  	if (sb_set_blocksize(sb, blocksize) != blocksize) {
  		pr_err("unable to set blocksize to %u!
  ", blocksize);
  		goto out_free_backup_vhdr;
  	}
  
  	sbi->blockoffset =
  		part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
  	sbi->part_start = part_start;
  	sbi->sect_count = part_size;
  	sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
  	return 0;
  
  out_free_backup_vhdr:
  	kfree(sbi->s_backup_vhdr_buf);
  out_free_vhdr:
  	kfree(sbi->s_vhdr_buf);
  out:
  	return error;
  }