splice: implement default splice_read method
[linux-2.6.git] / 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         if (ioctl_by_bdev(bdev, CDROM_LAST_WRITTEN, (unsigned long) &lblock))
60                 lblock = bdev->bd_inode->i_size >> sb->s_blocksize_bits;
61
62         if (lblock)
63                 return lblock - 1;
64         else
65                 return 0;
66 }