fs/udf/lowlevel.c

   1 /*
   2  * lowlevel.c
   3  *
   4  * PURPOSE
   5  *  Low Level Device Routines for the UDF filesystem
   6  *
   7  * COPYRIGHT
   8  *      This file is distributed under the terms of the GNU General Public
   9  *      License (GPL). Copies of the GPL can be obtained from:
  10  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
  11  *      Each contributing author retains all rights to their own work.
  12  *
  13  *  (C) 1999-2001 Ben Fennema
  14  *
  15  * HISTORY
  16  *
  17  *  03/26/99 blf  Created.
  18  */
  19
  20 #include "udfdecl.h"
  21
  22 #include <linux/blkdev.h>
  23 #include <linux/cdrom.h>
  24 #include <asm/uaccess.h>
  25
  26 #include "udf_sb.h"
  27
  28 unsigned int udf_get_last_session(struct super_block *sb)
  29 {
  30         struct cdrom_multisession ms_info;
  31         unsigned int vol_desc_start;
  32         struct block_device *bdev = sb->s_bdev;
  33         int i;
  34
  35         vol_desc_start = 0;
  36         ms_info.addr_format = CDROM_LBA;
  37         i = ioctl_by_bdev(bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
  38
  39 #define WE_OBEY_THE_WRITTEN_STANDARDS 1
  40
  41         if (i == 0) {
  42                 udf_debug("XA disk: %s, vol_desc_start=%d\n",
  43                           (ms_info.xa_flag ? "yes" : "no"), ms_info.addr.lba);
  44 #if WE_OBEY_THE_WRITTEN_STANDARDS
  45                 if (ms_info.xa_flag) /* necessary for a valid ms_info.addr */
  46 #endif
  47                         vol_desc_start = ms_info.addr.lba;
  48         } else {
  49                 udf_debug("CDROMMULTISESSION not supported: rc=%d\n", i);
  50         }
  51         return vol_desc_start;
  52 }
  53
  54 unsigned long udf_get_last_block(struct super_block *sb)
  55 {
  56         struct block_device *bdev = sb->s_bdev;
  57         unsigned long lblock = 0;
  58
  59         /*
  60          * ioctl failed or returned obviously bogus value?
  61          * Try using the device size...
  62          */
  63         if (ioctl_by_bdev(bdev, CDROM_LAST_WRITTEN, (unsigned long) &lblock) ||
  64             lblock == 0)
  65                 lblock = bdev->bd_inode->i_size >> sb->s_blocksize_bits;
  66
  67         if (lblock)
  68                 return lblock - 1;
  69         else
  70                 return 0;
  71 }