sd.c

linux 内核源代码

	if (len < 3)
		goto bad_sense;
	if (len > 20)
		len = 20;

	/* Take headers and block descriptors into account */
	len += data.header_length + data.block_descriptor_length;
	if (len > SD_BUF_SIZE)
		goto bad_sense;

	/* Get the data */
	res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len, &data, &sshdr);

	if (scsi_status_is_good(res)) {
		int offset = data.header_length + data.block_descriptor_length;

		if (offset >= SD_BUF_SIZE - 2) {
			sd_printk(KERN_ERR, sdkp, "Malformed MODE SENSE response\n");
			goto defaults;
		}

		if ((buffer[offset] & 0x3f) != modepage) {
			sd_printk(KERN_ERR, sdkp, "Got wrong page\n");
			goto defaults;
		}

		if (modepage == 8) {
			sdkp->WCE = ((buffer[offset + 2] & 0x04) != 0);
			sdkp->RCD = ((buffer[offset + 2] & 0x01) != 0);
		} else {
			sdkp->WCE = ((buffer[offset + 2] & 0x01) == 0);
			sdkp->RCD = 0;
		}

		sdkp->DPOFUA = (data.device_specific & 0x10) != 0;
		if (sdkp->DPOFUA && !sdkp->device->use_10_for_rw) {
			sd_printk(KERN_NOTICE, sdkp,
				  "Uses READ/WRITE(6), disabling FUA\n");
			sdkp->DPOFUA = 0;
		}

		sd_printk(KERN_NOTICE, sdkp,
		       "Write cache: %s, read cache: %s, %s\n",
		       sdkp->WCE ? "enabled" : "disabled",
		       sdkp->RCD ? "disabled" : "enabled",
		       sdkp->DPOFUA ? "supports DPO and FUA"
		       : "doesn't support DPO or FUA");

		return;
	}

bad_sense:
	if (scsi_sense_valid(&sshdr) &&
	    sshdr.sense_key == ILLEGAL_REQUEST &&
	    sshdr.asc == 0x24 && sshdr.ascq == 0x0)
		/* Invalid field in CDB */
		sd_printk(KERN_NOTICE, sdkp, "Cache data unavailable\n");
	else
		sd_printk(KERN_ERR, sdkp, "Asking for cache data failed\n");

defaults:
	sd_printk(KERN_ERR, sdkp, "Assuming drive cache: write through\n");
	sdkp->WCE = 0;
	sdkp->RCD = 0;
	sdkp->DPOFUA = 0;
}

/**
 *	sd_revalidate_disk - called the first time a new disk is seen,
 *	performs disk spin up, read_capacity, etc.
 *	@disk: struct gendisk we care about
 **/
static int sd_revalidate_disk(struct gendisk *disk)
{
	struct scsi_disk *sdkp = scsi_disk(disk);
	struct scsi_device *sdp = sdkp->device;
	unsigned char *buffer;
	unsigned ordered;

	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
				      "sd_revalidate_disk\n"));

	/*
	 * If the device is offline, don't try and read capacity or any
	 * of the other niceties.
	 */
	if (!scsi_device_online(sdp))
		goto out;

	buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
	if (!buffer) {
		sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory "
			  "allocation failure.\n");
		goto out;
	}

	/* defaults, until the device tells us otherwise */
	sdp->sector_size = 512;
	sdkp->capacity = 0;
	sdkp->media_present = 1;
	sdkp->write_prot = 0;
	sdkp->WCE = 0;
	sdkp->RCD = 0;

	sd_spinup_disk(sdkp);

	/*
	 * Without media there is no reason to ask; moreover, some devices
	 * react badly if we do.
	 */
	if (sdkp->media_present) {
		sd_read_capacity(sdkp, buffer);
		sd_read_write_protect_flag(sdkp, buffer);
		sd_read_cache_type(sdkp, buffer);
	}

	/*
	 * We now have all cache related info, determine how we deal
	 * with ordered requests.  Note that as the current SCSI
	 * dispatch function can alter request order, we cannot use
	 * QUEUE_ORDERED_TAG_* even when ordered tag is supported.
	 */
	if (sdkp->WCE)
		ordered = sdkp->DPOFUA
			? QUEUE_ORDERED_DRAIN_FUA : QUEUE_ORDERED_DRAIN_FLUSH;
	else
		ordered = QUEUE_ORDERED_DRAIN;

	blk_queue_ordered(sdkp->disk->queue, ordered, sd_prepare_flush);

	set_capacity(disk, sdkp->capacity);
	kfree(buffer);

 out:
	return 0;
}

/**
 *	sd_probe - called during driver initialization and whenever a
 *	new scsi device is attached to the system. It is called once
 *	for each scsi device (not just disks) present.
 *	@dev: pointer to device object
 *
 *	Returns 0 if successful (or not interested in this scsi device 
 *	(e.g. scanner)); 1 when there is an error.
 *
 *	Note: this function is invoked from the scsi mid-level.
 *	This function sets up the mapping between a given 
 *	<host,channel,id,lun> (found in sdp) and new device name 
 *	(e.g. /dev/sda). More precisely it is the block device major 
 *	and minor number that is chosen here.
 *
 *	Assume sd_attach is not re-entrant (for time being)
 *	Also think about sd_attach() and sd_remove() running coincidentally.
 **/
static int sd_probe(struct device *dev)
{
	struct scsi_device *sdp = to_scsi_device(dev);
	struct scsi_disk *sdkp;
	struct gendisk *gd;
	u32 index;
	int error;

	error = -ENODEV;
	if (sdp->type != TYPE_DISK && sdp->type != TYPE_MOD && sdp->type != TYPE_RBC)
		goto out;

	SCSI_LOG_HLQUEUE(3, sdev_printk(KERN_INFO, sdp,
					"sd_attach\n"));

	error = -ENOMEM;
	sdkp = kzalloc(sizeof(*sdkp), GFP_KERNEL);
	if (!sdkp)
		goto out;

	gd = alloc_disk(16);
	if (!gd)
		goto out_free;

	if (!idr_pre_get(&sd_index_idr, GFP_KERNEL))
		goto out_put;

	spin_lock(&sd_index_lock);
	error = idr_get_new(&sd_index_idr, NULL, &index);
	spin_unlock(&sd_index_lock);

	if (index >= SD_MAX_DISKS)
		error = -EBUSY;
	if (error)
		goto out_put;

	sdkp->device = sdp;
	sdkp->driver = &sd_template;
	sdkp->disk = gd;
	sdkp->index = index;
	sdkp->openers = 0;

	if (!sdp->timeout) {
		if (sdp->type != TYPE_MOD)
			sdp->timeout = SD_TIMEOUT;
		else
			sdp->timeout = SD_MOD_TIMEOUT;
	}

	class_device_initialize(&sdkp->cdev);
	sdkp->cdev.dev = &sdp->sdev_gendev;
	sdkp->cdev.class = &sd_disk_class;
	strncpy(sdkp->cdev.class_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);

	if (class_device_add(&sdkp->cdev))
		goto out_put;

	get_device(&sdp->sdev_gendev);

	gd->major = sd_major((index & 0xf0) >> 4);
	gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
	gd->minors = 16;
	gd->fops = &sd_fops;

	if (index < 26) {
		sprintf(gd->disk_name, "sd%c", 'a' + index % 26);
	} else if (index < (26 + 1) * 26) {
		sprintf(gd->disk_name, "sd%c%c",
			'a' + index / 26 - 1,'a' + index % 26);
	} else {
		const unsigned int m1 = (index / 26 - 1) / 26 - 1;
		const unsigned int m2 = (index / 26 - 1) % 26;
		const unsigned int m3 =  index % 26;
		sprintf(gd->disk_name, "sd%c%c%c",
			'a' + m1, 'a' + m2, 'a' + m3);
	}

	gd->private_data = &sdkp->driver;
	gd->queue = sdkp->device->request_queue;

	sd_revalidate_disk(gd);

	blk_queue_prep_rq(sdp->request_queue, sd_prep_fn);

	gd->driverfs_dev = &sdp->sdev_gendev;
	gd->flags = GENHD_FL_DRIVERFS;
	if (sdp->removable)
		gd->flags |= GENHD_FL_REMOVABLE;

	dev_set_drvdata(dev, sdkp);
	add_disk(gd);

	sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
		  sdp->removable ? "removable " : "");

	return 0;

 out_put:
	put_disk(gd);
 out_free:
	kfree(sdkp);
 out:
	return error;
}

/**
 *	sd_remove - called whenever a scsi disk (previously recognized by
 *	sd_probe) is detached from the system. It is called (potentially
 *	multiple times) during sd module unload.
 *	@sdp: pointer to mid level scsi device object
 *
 *	Note: this function is invoked from the scsi mid-level.
 *	This function potentially frees up a device name (e.g. /dev/sdc)
 *	that could be re-used by a subsequent sd_probe().
 *	This function is not called when the built-in sd driver is "exit-ed".
 **/
static int sd_remove(struct device *dev)
{
	struct scsi_disk *sdkp = dev_get_drvdata(dev);

	class_device_del(&sdkp->cdev);
	del_gendisk(sdkp->disk);
	sd_shutdown(dev);

	mutex_lock(&sd_ref_mutex);
	dev_set_drvdata(dev, NULL);
	class_device_put(&sdkp->cdev);
	mutex_unlock(&sd_ref_mutex);

	return 0;
}

/**
 *	scsi_disk_release - Called to free the scsi_disk structure
 *	@cdev: pointer to embedded class device
 *
 *	sd_ref_mutex must be held entering this routine.  Because it is
 *	called on last put, you should always use the scsi_disk_get()
 *	scsi_disk_put() helpers which manipulate the semaphore directly
 *	and never do a direct class_device_put().
 **/
static void scsi_disk_release(struct class_device *cdev)
{
	struct scsi_disk *sdkp = to_scsi_disk(cdev);
	struct gendisk *disk = sdkp->disk;
	
	spin_lock(&sd_index_lock);
	idr_remove(&sd_index_idr, sdkp->index);
	spin_unlock(&sd_index_lock);

	disk->private_data = NULL;
	put_disk(disk);
	put_device(&sdkp->device->sdev_gendev);

	kfree(sdkp);
}

static int sd_start_stop_device(struct scsi_disk *sdkp, int start)
{
	unsigned char cmd[6] = { START_STOP };	/* START_VALID */
	struct scsi_sense_hdr sshdr;
	struct scsi_device *sdp = sdkp->device;
	int res;

	if (start)
		cmd[4] |= 1;	/* START */

	if (!scsi_device_online(sdp))
		return -ENODEV;

	res = scsi_execute_req(sdp, cmd, DMA_NONE, NULL, 0, &sshdr,
			       SD_TIMEOUT, SD_MAX_RETRIES);
	if (res) {
		sd_printk(KERN_WARNING, sdkp, "START_STOP FAILED\n");
		sd_print_result(sdkp, res);
		if (driver_byte(res) & DRIVER_SENSE)
			sd_print_sense_hdr(sdkp, &sshdr);
	}

	return res;
}

/*
 * Send a SYNCHRONIZE CACHE instruction down to the device through
 * the normal SCSI command structure.  Wait for the command to
 * complete.
 */
static void sd_shutdown(struct device *dev)
{
	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);

	if (!sdkp)
		return;         /* this can happen */

	if (sdkp->WCE) {
		sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");
		sd_sync_cache(sdkp);
	}

	if (system_state != SYSTEM_RESTART && sdkp->device->manage_start_stop) {
		sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
		sd_start_stop_device(sdkp, 0);
	}

	scsi_disk_put(sdkp);
}

static int sd_suspend(struct device *dev, pm_message_t mesg)
{
	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
	int ret = 0;

	if (!sdkp)
		return 0;	/* this can happen */

	if (sdkp->WCE) {
		sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");
		ret = sd_sync_cache(sdkp);
		if (ret)
			goto done;
	}

	if (mesg.event == PM_EVENT_SUSPEND &&
	    sdkp->device->manage_start_stop) {
		sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
		ret = sd_start_stop_device(sdkp, 0);
	}

done:
	scsi_disk_put(sdkp);
	return ret;
}

static int sd_resume(struct device *dev)
{
	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
	int ret = 0;

	if (!sdkp->device->manage_start_stop)
		goto done;

	sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
	ret = sd_start_stop_device(sdkp, 1);

done:
	scsi_disk_put(sdkp);
	return ret;
}

/**
 *	init_sd - entry point for this driver (both when built in or when
 *	a module).
 *
 *	Note: this function registers this driver with the scsi mid-level.
 **/
static int __init init_sd(void)
{
	int majors = 0, i, err;

	SCSI_LOG_HLQUEUE(3, printk("init_sd: sd driver entry point\n"));

	for (i = 0; i < SD_MAJORS; i++)
		if (register_blkdev(sd_major(i), "sd") == 0)
			majors++;

	if (!majors)
		return -ENODEV;

	err = class_register(&sd_disk_class);
	if (err)
		goto err_out;

	err = scsi_register_driver(&sd_template.gendrv);
	if (err)
		goto err_out_class;

	return 0;

err_out_class:
	class_unregister(&sd_disk_class);
err_out:
	for (i = 0; i < SD_MAJORS; i++)
		unregister_blkdev(sd_major(i), "sd");
	return err;
}

/**
 *	exit_sd - exit point for this driver (when it is a module).
 *
 *	Note: this function unregisters this driver from the scsi mid-level.
 **/
static void __exit exit_sd(void)
{
	int i;

	SCSI_LOG_HLQUEUE(3, printk("exit_sd: exiting sd driver\n"));

	scsi_unregister_driver(&sd_template.gendrv);
	class_unregister(&sd_disk_class);

	for (i = 0; i < SD_MAJORS; i++)
		unregister_blkdev(sd_major(i), "sd");
}

module_init(init_sd);
module_exit(exit_sd);

static void sd_print_sense_hdr(struct scsi_disk *sdkp,
			       struct scsi_sense_hdr *sshdr)
{
	sd_printk(KERN_INFO, sdkp, "");
	scsi_show_sense_hdr(sshdr);
	sd_printk(KERN_INFO, sdkp, "");
	scsi_show_extd_sense(sshdr->asc, sshdr->ascq);
}

static void sd_print_result(struct scsi_disk *sdkp, int result)
{
	sd_printk(KERN_INFO, sdkp, "");
	scsi_show_result(result);
}