fs/udf/lowlevel.c

Source file repositories/reference/linux-study-clean/fs/udf/lowlevel.c

File Facts

System
Linux kernel
Corpus path
fs/udf/lowlevel.c
Extension
.c
Size
1352 bytes
Lines
63
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * lowlevel.c
 *
 * PURPOSE
 *  Low Level Device Routines for the UDF filesystem
 *
 * COPYRIGHT
 *  (C) 1999-2001 Ben Fennema
 *
 * HISTORY
 *
 *  03/26/99 blf  Created.
 */

#include "udfdecl.h"

#include <linux/blkdev.h>
#include <linux/cdrom.h>
#include <linux/uaccess.h>

#include "udf_sb.h"

unsigned int udf_get_last_session(struct super_block *sb)
{
	struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
	struct cdrom_multisession ms_info;

	if (!cdi) {
		udf_debug("CDROMMULTISESSION not supported.\n");
		return 0;
	}

	ms_info.addr_format = CDROM_LBA;
	if (cdrom_multisession(cdi, &ms_info) == 0) {
		udf_debug("XA disk: %s, vol_desc_start=%d\n",
			  ms_info.xa_flag ? "yes" : "no", ms_info.addr.lba);
		if (ms_info.xa_flag) /* necessary for a valid ms_info.addr */
			return ms_info.addr.lba;
	}
	return 0;
}

udf_pblk_t udf_get_last_block(struct super_block *sb)
{
	struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
	unsigned long lblock = 0;

	/*
	 * The cdrom layer call failed or returned obviously bogus value?
	 * Try using the device size...
	 */
	if (!cdi || cdrom_get_last_written(cdi, &lblock) || lblock == 0) {
		if (sb_bdev_nr_blocks(sb) > ~(udf_pblk_t)0)
			return 0;
		lblock = sb_bdev_nr_blocks(sb);
	}

	if (lblock)
		return lblock - 1;
	return 0;
}

Annotation

Implementation Notes