(2006-08-06) rescue-bootcd

extra/linux-2.6.10/drivers/scsi/sr.c

@@ -0,0 +1,963 @@
+/*
+ *  sr.c Copyright (C) 1992 David Giller
+ *           Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
+ *
+ *  adapted from:
+ *      sd.c Copyright (C) 1992 Drew Eckhardt
+ *      Linux scsi disk driver by
+ *              Drew Eckhardt <drew@colorado.edu>
+ *
+ *	Modified by Eric Youngdale ericy@andante.org to
+ *	add scatter-gather, multiple outstanding request, and other
+ *	enhancements.
+ *
+ *      Modified by Eric Youngdale eric@andante.org to support loadable
+ *      low-level scsi drivers.
+ *
+ *      Modified by Thomas Quinot thomas@melchior.cuivre.fdn.fr to
+ *      provide auto-eject.
+ *
+ *      Modified by Gerd Knorr <kraxel@cs.tu-berlin.de> to support the
+ *      generic cdrom interface
+ *
+ *      Modified by Jens Axboe <axboe@suse.de> - Uniform sr_packet()
+ *      interface, capabilities probe additions, ioctl cleanups, etc.
+ *
+ *	Modified by Richard Gooch <rgooch@atnf.csiro.au> to support devfs
+ *
+ *	Modified by Jens Axboe <axboe@suse.de> - support DVD-RAM
+ *	transparently and lose the GHOST hack
+ *
+ *	Modified by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *	check resource allocation in sr_init and some cleanups
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/bio.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/cdrom.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <asm/uaccess.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>	/* For the door lock/unlock commands */
+#include <scsi/scsi_request.h>
+
+#include "scsi_logging.h"
+#include "sr.h"
+
+
+MODULE_PARM(xa_test, "i");	/* see sr_ioctl.c */
+
+
+#define SR_DISKS	256
+
+#define MAX_RETRIES	3
+#define SR_TIMEOUT	(30 * HZ)
+#define SR_CAPABILITIES \
+	(CDC_CLOSE_TRAY|CDC_OPEN_TRAY|CDC_LOCK|CDC_SELECT_SPEED| \
+	 CDC_SELECT_DISC|CDC_MULTI_SESSION|CDC_MCN|CDC_MEDIA_CHANGED| \
+	 CDC_PLAY_AUDIO|CDC_RESET|CDC_IOCTLS|CDC_DRIVE_STATUS| \
+	 CDC_CD_R|CDC_CD_RW|CDC_DVD|CDC_DVD_R|CDC_DVD_RAM|CDC_GENERIC_PACKET| \
+	 CDC_MRW|CDC_MRW_W|CDC_RAM)
+
+static int sr_probe(struct device *);
+static int sr_remove(struct device *);
+static int sr_init_command(struct scsi_cmnd *);
+
+static struct scsi_driver sr_template = {
+	.owner			= THIS_MODULE,
+	.gendrv = {
+		.name   	= "sr",
+		.probe		= sr_probe,
+		.remove		= sr_remove,
+	},
+	.init_command		= sr_init_command,
+};
+
+static unsigned long sr_index_bits[SR_DISKS / BITS_PER_LONG];
+static spinlock_t sr_index_lock = SPIN_LOCK_UNLOCKED;
+
+/* This semaphore is used to mediate the 0->1 reference get in the
+ * face of object destruction (i.e. we can't allow a get on an
+ * object after last put) */
+static DECLARE_MUTEX(sr_ref_sem);
+
+static int sr_open(struct cdrom_device_info *, int);
+static void sr_release(struct cdrom_device_info *);
+
+static void get_sectorsize(struct scsi_cd *);
+static void get_capabilities(struct scsi_cd *);
+
+static int sr_media_change(struct cdrom_device_info *, int);
+static int sr_packet(struct cdrom_device_info *, struct packet_command *);
+
+static struct cdrom_device_ops sr_dops = {
+	.open			= sr_open,
+	.release	 	= sr_release,
+	.drive_status	 	= sr_drive_status,
+	.media_changed		= sr_media_change,
+	.tray_move		= sr_tray_move,
+	.lock_door		= sr_lock_door,
+	.select_speed		= sr_select_speed,
+	.get_last_session	= sr_get_last_session,
+	.get_mcn		= sr_get_mcn,
+	.reset			= sr_reset,
+	.audio_ioctl		= sr_audio_ioctl,
+	.dev_ioctl		= sr_dev_ioctl,
+	.capability		= SR_CAPABILITIES,
+	.generic_packet		= sr_packet,
+};
+
+static void sr_kref_release(struct kref *kref);
+
+static inline struct scsi_cd *scsi_cd(struct gendisk *disk)
+{
+	return container_of(disk->private_data, struct scsi_cd, driver);
+}
+
+/*
+ * The get and put routines for the struct scsi_cd.  Note this entity
+ * has a scsi_device pointer and owns a reference to this.
+ */
+static inline struct scsi_cd *scsi_cd_get(struct gendisk *disk)
+{
+	struct scsi_cd *cd = NULL;
+
+	down(&sr_ref_sem);
+	if (disk->private_data == NULL)
+		goto out;
+	cd = scsi_cd(disk);
+	kref_get(&cd->kref);
+	if (scsi_device_get(cd->device))
+		goto out_put;
+	goto out;
+
+ out_put:
+	kref_put(&cd->kref, sr_kref_release);
+	cd = NULL;
+ out:
+	up(&sr_ref_sem);
+	return cd;
+}
+
+static inline void scsi_cd_put(struct scsi_cd *cd)
+{
+	down(&sr_ref_sem);
+	kref_put(&cd->kref, sr_kref_release);
+	scsi_device_put(cd->device);
+	up(&sr_ref_sem);
+}
+
+/*
+ * This function checks to see if the media has been changed in the
+ * CDROM drive.  It is possible that we have already sensed a change,
+ * or the drive may have sensed one and not yet reported it.  We must
+ * be ready for either case. This function always reports the current
+ * value of the changed bit.  If flag is 0, then the changed bit is reset.
+ * This function could be done as an ioctl, but we would need to have
+ * an inode for that to work, and we do not always have one.
+ */
+
+int sr_media_change(struct cdrom_device_info *cdi, int slot)
+{
+	struct scsi_cd *cd = cdi->handle;
+	int retval;
+
+	if (CDSL_CURRENT != slot) {
+		/* no changer support */
+		return -EINVAL;
+	}
+
+	retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES);
+	if (retval) {
+		/* Unable to test, unit probably not ready.  This usually
+		 * means there is no disc in the drive.  Mark as changed,
+		 * and we will figure it out later once the drive is
+		 * available again.  */
+		cd->device->changed = 1;
+		return 1;	/* This will force a flush, if called from
+				 * check_disk_change */
+	};
+
+	retval = cd->device->changed;
+	cd->device->changed = 0;
+	/* If the disk changed, the capacity will now be different,
+	 * so we force a re-read of this information */
+	if (retval) {
+		/* check multisession offset etc */
+		sr_cd_check(cdi);
+
+		/* 
+		 * If the disk changed, the capacity will now be different,
+		 * so we force a re-read of this information 
+		 * Force 2048 for the sector size so that filesystems won't
+		 * be trying to use something that is too small if the disc
+		 * has changed.
+		 */
+		cd->needs_sector_size = 1;
+		cd->device->sector_size = 2048;
+	}
+	return retval;
+}
+ 
+/*
+ * rw_intr is the interrupt routine for the device driver.
+ *
+ * It will be notified on the end of a SCSI read / write, and will take on
+ * of several actions based on success or failure.
+ */
+static void rw_intr(struct scsi_cmnd * SCpnt)
+{
+	int result = SCpnt->result;
+	int this_count = SCpnt->bufflen;
+	int good_bytes = (result == 0 ? this_count : 0);
+	int block_sectors = 0;
+	long error_sector;
+	struct scsi_cd *cd = scsi_cd(SCpnt->request->rq_disk);
+
+#ifdef DEBUG
+	printk("sr.c done: %x\n", result);
+#endif
+
+	/*
+	 * Handle MEDIUM ERRORs or VOLUME OVERFLOWs that indicate partial
+	 * success.  Since this is a relatively rare error condition, no
+	 * care is taken to avoid unnecessary additional work such as
+	 * memcpy's that could be avoided.
+	 */
+	if (driver_byte(result) != 0 &&		/* An error occurred */
+	    (SCpnt->sense_buffer[0] & 0x7f) == 0x70) { /* Sense current */
+		switch (SCpnt->sense_buffer[2]) {
+		case MEDIUM_ERROR:
+		case VOLUME_OVERFLOW:
+		case ILLEGAL_REQUEST:
+			if (!(SCpnt->sense_buffer[0] & 0x90))
+				break;
+			if (!blk_fs_request(SCpnt->request))
+				break;
+			error_sector = (SCpnt->sense_buffer[3] << 24) |
+				(SCpnt->sense_buffer[4] << 16) |
+				(SCpnt->sense_buffer[5] << 8) |
+				SCpnt->sense_buffer[6];
+			if (SCpnt->request->bio != NULL)
+				block_sectors =
+					bio_sectors(SCpnt->request->bio);
+			if (block_sectors < 4)
+				block_sectors = 4;
+			if (cd->device->sector_size == 2048)
+				error_sector <<= 2;
+			error_sector &= ~(block_sectors - 1);
+			good_bytes = (error_sector - SCpnt->request->sector) << 9;
+			if (good_bytes < 0 || good_bytes >= this_count)
+				good_bytes = 0;
+			/*
+			 * The SCSI specification allows for the value
+			 * returned by READ CAPACITY to be up to 75 2K
+			 * sectors past the last readable block.
+			 * Therefore, if we hit a medium error within the
+			 * last 75 2K sectors, we decrease the saved size
+			 * value.
+			 */
+			if (error_sector < get_capacity(cd->disk) &&
+			    cd->capacity - error_sector < 4 * 75)
+				set_capacity(cd->disk, error_sector);
+			break;
+
+		case RECOVERED_ERROR:
+
+			/*
+			 * An error occured, but it recovered.  Inform the
+			 * user, but make sure that it's not treated as a
+			 * hard error.
+			 */
+			scsi_print_sense("sr", SCpnt);
+			SCpnt->result = 0;
+			SCpnt->sense_buffer[0] = 0x0;
+			good_bytes = this_count;
+			break;
+
+		default:
+			break;
+		}
+	}
+
+	/*
+	 * This calls the generic completion function, now that we know
+	 * how many actual sectors finished, and how many sectors we need
+	 * to say have failed.
+	 */
+	scsi_io_completion(SCpnt, good_bytes, block_sectors << 9);
+}
+
+static int sr_init_command(struct scsi_cmnd * SCpnt)
+{
+	int block=0, this_count, s_size, timeout = SR_TIMEOUT;
+	struct scsi_cd *cd = scsi_cd(SCpnt->request->rq_disk);
+
+	SCSI_LOG_HLQUEUE(1, printk("Doing sr request, dev = %s, block = %d\n",
+				cd->disk->disk_name, block));
+
+	if (!cd->device || !scsi_device_online(cd->device)) {
+		SCSI_LOG_HLQUEUE(2, printk("Finishing %ld sectors\n",
+					SCpnt->request->nr_sectors));
+		SCSI_LOG_HLQUEUE(2, printk("Retry with 0x%p\n", SCpnt));
+		return 0;
+	}
+
+	if (cd->device->changed) {
+		/*
+		 * quietly refuse to do anything to a changed disc until the
+		 * changed bit has been reset
+		 */
+		return 0;
+	}
+
+	/*
+	 * these are already setup, just copy cdb basically
+	 */
+	if (SCpnt->request->flags & REQ_BLOCK_PC) {
+		struct request *rq = SCpnt->request;
+
+		if (sizeof(rq->cmd) > sizeof(SCpnt->cmnd))
+			return 0;
+
+		memcpy(SCpnt->cmnd, rq->cmd, sizeof(SCpnt->cmnd));
+		if (!rq->data_len)
+			SCpnt->sc_data_direction = DMA_NONE;
+		else if (rq_data_dir(rq) == WRITE)
+			SCpnt->sc_data_direction = DMA_TO_DEVICE;
+		else
+			SCpnt->sc_data_direction = DMA_FROM_DEVICE;
+
+		this_count = rq->data_len;
+		if (rq->timeout)
+			timeout = rq->timeout;
+
+		SCpnt->transfersize = rq->data_len;
+		goto queue;
+	}
+
+	if (!(SCpnt->request->flags & REQ_CMD)) {
+		blk_dump_rq_flags(SCpnt->request, "sr unsup command");
+		return 0;
+	}
+
+	/*
+	 * we do lazy blocksize switching (when reading XA sectors,
+	 * see CDROMREADMODE2 ioctl) 
+	 */
+	s_size = cd->device->sector_size;
+	if (s_size > 2048) {
+		if (!in_interrupt())
+			sr_set_blocklength(cd, 2048);
+		else
+			printk("sr: can't switch blocksize: in interrupt\n");
+	}
+
+	if (s_size != 512 && s_size != 1024 && s_size != 2048) {
+		printk("sr: bad sector size %d\n", s_size);
+		return 0;
+	}
+
+	if (rq_data_dir(SCpnt->request) == WRITE) {
+		if (!cd->device->writeable)
+			return 0;
+		SCpnt->cmnd[0] = WRITE_10;
+		SCpnt->sc_data_direction = DMA_TO_DEVICE;
+ 	 	cd->cdi.media_written = 1;
+	} else if (rq_data_dir(SCpnt->request) == READ) {
+		SCpnt->cmnd[0] = READ_10;
+		SCpnt->sc_data_direction = DMA_FROM_DEVICE;
+	} else {
+		blk_dump_rq_flags(SCpnt->request, "Unknown sr command");
+		return 0;
+	}
+
+	{
+		struct scatterlist *sg = SCpnt->request_buffer;
+		int i, size = 0;
+		for (i = 0; i < SCpnt->use_sg; i++)
+			size += sg[i].length;
+
+		if (size != SCpnt->request_bufflen && SCpnt->use_sg) {
+			printk(KERN_ERR "sr: mismatch count %d, bytes %d\n",
+					size, SCpnt->request_bufflen);
+			if (SCpnt->request_bufflen > size)
+				SCpnt->request_bufflen = SCpnt->bufflen = size;
+		}
+	}
+
+	/*
+	 * request doesn't start on hw block boundary, add scatter pads
+	 */
+	if (((unsigned int)SCpnt->request->sector % (s_size >> 9)) ||
+	    (SCpnt->request_bufflen % s_size)) {
+		printk("sr: unaligned transfer\n");
+		return 0;
+	}
+
+	this_count = (SCpnt->request_bufflen >> 9) / (s_size >> 9);
+
+
+	SCSI_LOG_HLQUEUE(2, printk("%s : %s %d/%ld 512 byte blocks.\n",
+				cd->cdi.name,
+				(rq_data_dir(SCpnt->request) == WRITE) ?
+					"writing" : "reading",
+				this_count, SCpnt->request->nr_sectors));
+
+	SCpnt->cmnd[1] = 0;
+	block = (unsigned int)SCpnt->request->sector / (s_size >> 9);
+
+	if (this_count > 0xffff) {
+		this_count = 0xffff;
+		SCpnt->request_bufflen = SCpnt->bufflen =
+				this_count * s_size;
+	}
+
+	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
+	SCpnt->cmnd[3] = (unsigned char) (block >> 16) & 0xff;
+	SCpnt->cmnd[4] = (unsigned char) (block >> 8) & 0xff;
+	SCpnt->cmnd[5] = (unsigned char) block & 0xff;
+	SCpnt->cmnd[6] = SCpnt->cmnd[9] = 0;
+	SCpnt->cmnd[7] = (unsigned char) (this_count >> 8) & 0xff;
+	SCpnt->cmnd[8] = (unsigned char) this_count & 0xff;
+
+	/*
+	 * We shouldn't disconnect in the middle of a sector, so with a dumb
+	 * host adapter, it's safe to assume that we can at least transfer
+	 * this many bytes between each connect / disconnect.
+	 */
+	SCpnt->transfersize = cd->device->sector_size;
+	SCpnt->underflow = this_count << 9;
+
+queue:
+	SCpnt->allowed = MAX_RETRIES;
+	SCpnt->timeout_per_command = timeout;
+
+	/*
+	 * This is the completion routine we use.  This is matched in terms
+	 * of capability to this function.
+	 */
+	SCpnt->done = rw_intr;
+
+	/*
+	 * This indicates that the command is ready from our end to be
+	 * queued.
+	 */
+	return 1;
+}
+
+static int sr_block_open(struct inode *inode, struct file *file)
+{
+	struct gendisk *disk = inode->i_bdev->bd_disk;
+	struct scsi_cd *cd = scsi_cd(inode->i_bdev->bd_disk);
+	int ret = 0;
+
+	if(!(cd = scsi_cd_get(disk)))
+		return -ENXIO;
+
+	if((ret = cdrom_open(&cd->cdi, inode, file)) != 0)
+		scsi_cd_put(cd);
+
+	return ret;
+}
+
+static int sr_block_release(struct inode *inode, struct file *file)
+{
+	int ret;
+	struct scsi_cd *cd = scsi_cd(inode->i_bdev->bd_disk);
+	ret = cdrom_release(&cd->cdi, file);
+	if(ret)
+		return ret;
+	
+	scsi_cd_put(cd);
+
+	return 0;
+}
+
+static int sr_block_ioctl(struct inode *inode, struct file *file, unsigned cmd,
+			  unsigned long arg)
+{
+	struct scsi_cd *cd = scsi_cd(inode->i_bdev->bd_disk);
+	struct scsi_device *sdev = cd->device;
+
+        /*
+         * Send SCSI addressing ioctls directly to mid level, send other
+         * ioctls to cdrom/block level.
+         */
+        switch (cmd) {
+                case SCSI_IOCTL_GET_IDLUN:
+                case SCSI_IOCTL_GET_BUS_NUMBER:
+                        return scsi_ioctl(sdev, cmd, (void __user *)arg);
+	}
+	return cdrom_ioctl(file, &cd->cdi, inode, cmd, arg);
+}
+
+static int sr_block_media_changed(struct gendisk *disk)
+{
+	struct scsi_cd *cd = scsi_cd(disk);
+	return cdrom_media_changed(&cd->cdi);
+}
+
+struct block_device_operations sr_bdops =
+{
+	.owner		= THIS_MODULE,
+	.open		= sr_block_open,
+	.release	= sr_block_release,
+	.ioctl		= sr_block_ioctl,
+	.media_changed	= sr_block_media_changed,
+};
+
+static int sr_open(struct cdrom_device_info *cdi, int purpose)
+{
+	struct scsi_cd *cd = cdi->handle;
+	struct scsi_device *sdev = cd->device;
+	int retval;
+
+	/*
+	 * If the device is in error recovery, wait until it is done.
+	 * If the device is offline, then disallow any access to it.
+	 */
+	retval = -ENXIO;
+	if (!scsi_block_when_processing_errors(sdev))
+		goto error_out;
+
+	/*
+	 * If this device did not have media in the drive at boot time, then
+	 * we would have been unable to get the sector size.  Check to see if
+	 * this is the case, and try again.
+	 */
+	if (cd->needs_sector_size)
+		get_sectorsize(cd);
+	return 0;
+
+error_out:
+	scsi_cd_put(cd);
+	return retval;	
+}
+
+static void sr_release(struct cdrom_device_info *cdi)
+{
+	struct scsi_cd *cd = cdi->handle;
+
+	if (cd->device->sector_size > 2048)
+		sr_set_blocklength(cd, 2048);
+
+}
+
+static int sr_probe(struct device *dev)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct gendisk *disk;
+	struct scsi_cd *cd;
+	int minor, error;
+
+	error = -ENODEV;
+	if (sdev->type != TYPE_ROM && sdev->type != TYPE_WORM)
+		goto fail;
+
+	error = -ENOMEM;
+	cd = kmalloc(sizeof(*cd), GFP_KERNEL);
+	if (!cd)
+		goto fail;
+	memset(cd, 0, sizeof(*cd));
+
+	kref_init(&cd->kref);
+
+	disk = alloc_disk(1);
+	if (!disk)
+		goto fail_free;
+
+	spin_lock(&sr_index_lock);
+	minor = find_first_zero_bit(sr_index_bits, SR_DISKS);
+	if (minor == SR_DISKS) {
+		spin_unlock(&sr_index_lock);
+		error = -EBUSY;
+		goto fail_put;
+	}
+	__set_bit(minor, sr_index_bits);
+	spin_unlock(&sr_index_lock);
+
+	disk->major = SCSI_CDROM_MAJOR;
+	disk->first_minor = minor;
+	sprintf(disk->disk_name, "sr%d", minor);
+	disk->fops = &sr_bdops;
+	disk->flags = GENHD_FL_CD;
+
+	cd->device = sdev;
+	cd->disk = disk;
+	cd->driver = &sr_template;
+	cd->disk = disk;
+	cd->capacity = 0x1fffff;
+	cd->needs_sector_size = 1;
+	cd->device->changed = 1;	/* force recheck CD type */
+	cd->use = 1;
+	cd->readcd_known = 0;
+	cd->readcd_cdda = 0;
+
+	cd->cdi.ops = &sr_dops;
+	cd->cdi.handle = cd;
+	cd->cdi.mask = 0;
+	cd->cdi.capacity = 1;
+	sprintf(cd->cdi.name, "sr%d", minor);
+
+	sdev->sector_size = 2048;	/* A guess, just in case */
+
+	/* FIXME: need to handle a get_capabilities failure properly ?? */
+	get_capabilities(cd);
+	sr_vendor_init(cd);
+
+	snprintf(disk->devfs_name, sizeof(disk->devfs_name),
+			"%s/cd", sdev->devfs_name);
+	disk->driverfs_dev = &sdev->sdev_gendev;
+	set_capacity(disk, cd->capacity);
+	disk->private_data = &cd->driver;
+	disk->queue = sdev->request_queue;
+	cd->cdi.disk = disk;
+
+	if (register_cdrom(&cd->cdi))
+		goto fail_put;
+
+	dev_set_drvdata(dev, cd);
+	disk->flags |= GENHD_FL_REMOVABLE;
+	add_disk(disk);
+
+	printk(KERN_DEBUG
+	    "Attached scsi CD-ROM %s at scsi%d, channel %d, id %d, lun %d\n",
+	    cd->cdi.name, sdev->host->host_no, sdev->channel,
+	    sdev->id, sdev->lun);
+	return 0;
+
+fail_put:
+	put_disk(disk);
+fail_free:
+	kfree(cd);
+fail:
+	return error;
+}
+
+
+static void get_sectorsize(struct scsi_cd *cd)
+{
+	unsigned char cmd[10];
+	unsigned char *buffer;
+	int the_result, retries = 3;
+	int sector_size;
+	struct scsi_request *SRpnt = NULL;
+	request_queue_t *queue;
+
+	buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);
+	if (!buffer)
+		goto Enomem;
+	SRpnt = scsi_allocate_request(cd->device, GFP_KERNEL);
+	if (!SRpnt)
+		goto Enomem;
+
+	do {
+		cmd[0] = READ_CAPACITY;
+		memset((void *) &cmd[1], 0, 9);
+		/* Mark as really busy */
+		SRpnt->sr_request->rq_status = RQ_SCSI_BUSY;
+		SRpnt->sr_cmd_len = 0;
+
+		memset(buffer, 0, 8);
+
+		/* Do the command and wait.. */
+		SRpnt->sr_data_direction = DMA_FROM_DEVICE;
+		scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
+			      8, SR_TIMEOUT, MAX_RETRIES);
+
+		the_result = SRpnt->sr_result;
+		retries--;
+
+	} while (the_result && retries);
+
+
+	scsi_release_request(SRpnt);
+	SRpnt = NULL;
+
+	if (the_result) {
+		cd->capacity = 0x1fffff;
+		sector_size = 2048;	/* A guess, just in case */
+		cd->needs_sector_size = 1;
+	} else {
+#if 0
+		if (cdrom_get_last_written(&cd->cdi,
+					   &cd->capacity))
+#endif
+			cd->capacity = 1 + ((buffer[0] << 24) |
+						    (buffer[1] << 16) |
+						    (buffer[2] << 8) |
+						    buffer[3]);
+		sector_size = (buffer[4] << 24) |
+		    (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
+		switch (sector_size) {
+			/*
+			 * HP 4020i CD-Recorder reports 2340 byte sectors
+			 * Philips CD-Writers report 2352 byte sectors
+			 *
+			 * Use 2k sectors for them..
+			 */
+		case 0:
+		case 2340:
+		case 2352:
+			sector_size = 2048;
+			/* fall through */
+		case 2048:
+			cd->capacity *= 4;
+			/* fall through */
+		case 512:
+			break;
+		default:
+			printk("%s: unsupported sector size %d.\n",
+			       cd->cdi.name, sector_size);
+			cd->capacity = 0;
+			cd->needs_sector_size = 1;
+		}
+
+		cd->device->sector_size = sector_size;
+
+		/*
+		 * Add this so that we have the ability to correctly gauge
+		 * what the device is capable of.
+		 */
+		cd->needs_sector_size = 0;
+		set_capacity(cd->disk, cd->capacity);
+	}
+
+	queue = cd->device->request_queue;
+	blk_queue_hardsect_size(queue, sector_size);
+out:
+	kfree(buffer);
+	return;
+
+Enomem:
+	cd->capacity = 0x1fffff;
+	sector_size = 2048;	/* A guess, just in case */
+	cd->needs_sector_size = 1;
+	if (SRpnt)
+		scsi_release_request(SRpnt);
+	goto out;
+}
+
+static void get_capabilities(struct scsi_cd *cd)
+{
+	unsigned char *buffer;
+	struct scsi_mode_data data;
+	struct scsi_request *SRpnt;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	unsigned int the_result;
+	int retries, rc, n;
+
+	static char *loadmech[] =
+	{
+		"caddy",
+		"tray",
+		"pop-up",
+		"",
+		"changer",
+		"cartridge changer",
+		"",
+		""
+	};
+
+	/* allocate a request for the TEST_UNIT_READY */
+	SRpnt = scsi_allocate_request(cd->device, GFP_KERNEL);
+	if (!SRpnt) {
+		printk(KERN_WARNING "(get_capabilities:) Request allocation "
+		       "failure.\n");
+		return;
+	}
+
+	/* allocate transfer buffer */
+	buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);
+	if (!buffer) {
+		printk(KERN_ERR "sr: out of memory.\n");
+		scsi_release_request(SRpnt);
+		return;
+	}
+
+	/* issue TEST_UNIT_READY until the initial startup UNIT_ATTENTION
+	 * conditions are gone, or a timeout happens
+	 */
+	retries = 0;
+	do {
+		memset((void *)cmd, 0, MAX_COMMAND_SIZE);
+		cmd[0] = TEST_UNIT_READY;
+
+		SRpnt->sr_cmd_len = 0;
+		SRpnt->sr_sense_buffer[0] = 0;
+		SRpnt->sr_sense_buffer[2] = 0;
+		SRpnt->sr_data_direction = DMA_NONE;
+
+		scsi_wait_req (SRpnt, (void *) cmd, buffer,
+			       0, SR_TIMEOUT, MAX_RETRIES);
+
+		the_result = SRpnt->sr_result;
+		retries++;
+	} while (retries < 5 && 
+		 (!scsi_status_is_good(the_result) ||
+		  ((driver_byte(the_result) & DRIVER_SENSE) &&
+		   SRpnt->sr_sense_buffer[2] == UNIT_ATTENTION)));
+
+	/* ask for mode page 0x2a */
+	rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, 128,
+			     SR_TIMEOUT, 3, &data);
+
+	if (!scsi_status_is_good(rc)) {
+		/* failed, drive doesn't have capabilities mode page */
+		cd->cdi.speed = 1;
+		cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |
+					 CDC_DVD | CDC_DVD_RAM |
+					 CDC_SELECT_DISC | CDC_SELECT_SPEED);
+		scsi_release_request(SRpnt);
+		kfree(buffer);
+		printk("%s: scsi-1 drive\n", cd->cdi.name);
+		return;
+	}
+
+	n = data.header_length + data.block_descriptor_length;
+	cd->cdi.speed = ((buffer[n + 8] << 8) + buffer[n + 9]) / 176;
+	cd->readcd_known = 1;
+	cd->readcd_cdda = buffer[n + 5] & 0x01;
+	/* print some capability bits */
+	printk("%s: scsi3-mmc drive: %dx/%dx %s%s%s%s%s%s\n", cd->cdi.name,
+	       ((buffer[n + 14] << 8) + buffer[n + 15]) / 176,
+	       cd->cdi.speed,
+	       buffer[n + 3] & 0x01 ? "writer " : "", /* CD Writer */
+	       buffer[n + 3] & 0x20 ? "dvd-ram " : "",
+	       buffer[n + 2] & 0x02 ? "cd/rw " : "", /* can read rewriteable */
+	       buffer[n + 4] & 0x20 ? "xa/form2 " : "",	/* can read xa/from2 */
+	       buffer[n + 5] & 0x01 ? "cdda " : "", /* can read audio data */
+	       loadmech[buffer[n + 6] >> 5]);
+	if ((buffer[n + 6] >> 5) == 0)
+		/* caddy drives can't close tray... */
+		cd->cdi.mask |= CDC_CLOSE_TRAY;
+	if ((buffer[n + 2] & 0x8) == 0)
+		/* not a DVD drive */
+		cd->cdi.mask |= CDC_DVD;
+	if ((buffer[n + 3] & 0x20) == 0) 
+		/* can't write DVD-RAM media */
+		cd->cdi.mask |= CDC_DVD_RAM;
+	if ((buffer[n + 3] & 0x10) == 0)
+		/* can't write DVD-R media */
+		cd->cdi.mask |= CDC_DVD_R;
+	if ((buffer[n + 3] & 0x2) == 0)
+		/* can't write CD-RW media */
+		cd->cdi.mask |= CDC_CD_RW;
+	if ((buffer[n + 3] & 0x1) == 0)
+		/* can't write CD-R media */
+		cd->cdi.mask |= CDC_CD_R;
+	if ((buffer[n + 6] & 0x8) == 0)
+		/* can't eject */
+		cd->cdi.mask |= CDC_OPEN_TRAY;
+
+	if ((buffer[n + 6] >> 5) == mechtype_individual_changer ||
+	    (buffer[n + 6] >> 5) == mechtype_cartridge_changer)
+		cd->cdi.capacity =
+		    cdrom_number_of_slots(&cd->cdi);
+	if (cd->cdi.capacity <= 1)
+		/* not a changer */
+		cd->cdi.mask |= CDC_SELECT_DISC;
+	/*else    I don't think it can close its tray
+		cd->cdi.mask |= CDC_CLOSE_TRAY; */
+
+	/*
+	 * if DVD-RAM, MRW-W or CD-RW, we are randomly writable
+	 */
+	if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) !=
+			(CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) {
+		cd->device->writeable = 1;
+	}
+
+	scsi_release_request(SRpnt);
+	kfree(buffer);
+}
+
+/*
+ * sr_packet() is the entry point for the generic commands generated
+ * by the Uniform CD-ROM layer. 
+ */
+static int sr_packet(struct cdrom_device_info *cdi,
+		struct packet_command *cgc)
+{
+	if (cgc->timeout <= 0)
+		cgc->timeout = IOCTL_TIMEOUT;
+
+	sr_do_ioctl(cdi->handle, cgc);
+
+	return cgc->stat;
+}
+
+/**
+ *	sr_kref_release - Called to free the scsi_cd structure
+ *	@kref: pointer to embedded kref
+ *
+ *	sr_ref_sem must be held entering this routine.  Because it is
+ *	called on last put, you should always use the scsi_cd_get()
+ *	scsi_cd_put() helpers which manipulate the semaphore directly
+ *	and never do a direct kref_put().
+ **/
+static void sr_kref_release(struct kref *kref)
+{
+	struct scsi_cd *cd = container_of(kref, struct scsi_cd, kref);
+	struct gendisk *disk = cd->disk;
+
+	spin_lock(&sr_index_lock);
+	clear_bit(disk->first_minor, sr_index_bits);
+	spin_unlock(&sr_index_lock);
+
+	unregister_cdrom(&cd->cdi);
+
+	disk->private_data = NULL;
+
+	put_disk(disk);
+
+	kfree(cd);
+}
+
+static int sr_remove(struct device *dev)
+{
+	struct scsi_cd *cd = dev_get_drvdata(dev);
+
+	del_gendisk(cd->disk);
+
+	down(&sr_ref_sem);
+	kref_put(&cd->kref, sr_kref_release);
+	up(&sr_ref_sem);
+
+	return 0;
+}
+
+static int __init init_sr(void)
+{
+	int rc;
+
+	rc = register_blkdev(SCSI_CDROM_MAJOR, "sr");
+	if (rc)
+		return rc;
+	return scsi_register_driver(&sr_template.gendrv);
+}
+
+static void __exit exit_sr(void)
+{
+	scsi_unregister_driver(&sr_template.gendrv);
+	unregister_blkdev(SCSI_CDROM_MAJOR, "sr");
+}
+
+module_init(init_sr);
+module_exit(exit_sr);
+MODULE_LICENSE("GPL");