Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1934 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
new file mode 100644
index 000000000..6f7c4d41c
--- /dev/null
+++ b/drivers/scsi/scsi_scan.c
@@ -0,0 +1,1934 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * scsi_scan.c
+ *
+ * Copyright (C) 2000 Eric Youngdale,
+ * Copyright (C) 2002 Patrick Mansfield
+ *
+ * The general scanning/probing algorithm is as follows, exceptions are
+ * made to it depending on device specific flags, compilation options, and
+ * global variable (boot or module load time) settings.
+ *
+ * A specific LUN is scanned via an INQUIRY command; if the LUN has a
+ * device attached, a scsi_device is allocated and setup for it.
+ *
+ * For every id of every channel on the given host:
+ *
+ * 	Scan LUN 0; if the target responds to LUN 0 (even if there is no
+ * 	device or storage attached to LUN 0):
+ *
+ * 		If LUN 0 has a device attached, allocate and setup a
+ * 		scsi_device for it.
+ *
+ * 		If target is SCSI-3 or up, issue a REPORT LUN, and scan
+ * 		all of the LUNs returned by the REPORT LUN; else,
+ * 		sequentially scan LUNs up until some maximum is reached,
+ * 		or a LUN is seen that cannot have a device attached to it.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/spinlock.h>
+#include <linux/async.h>
+#include <linux/slab.h>
+#include <asm/unaligned.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_devinfo.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_transport.h>
+#include <scsi/scsi_dh.h>
+#include <scsi/scsi_eh.h>
+
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+
+#define ALLOC_FAILURE_MSG	KERN_ERR "%s: Allocation failure during" \
+	" SCSI scanning, some SCSI devices might not be configured\n"
+
+/*
+ * Default timeout
+ */
+#define SCSI_TIMEOUT (2*HZ)
+#define SCSI_REPORT_LUNS_TIMEOUT (30*HZ)
+
+/*
+ * Prefix values for the SCSI id's (stored in sysfs name field)
+ */
+#define SCSI_UID_SER_NUM 'S'
+#define SCSI_UID_UNKNOWN 'Z'
+
+/*
+ * Return values of some of the scanning functions.
+ *
+ * SCSI_SCAN_NO_RESPONSE: no valid response received from the target, this
+ * includes allocation or general failures preventing IO from being sent.
+ *
+ * SCSI_SCAN_TARGET_PRESENT: target responded, but no device is available
+ * on the given LUN.
+ *
+ * SCSI_SCAN_LUN_PRESENT: target responded, and a device is available on a
+ * given LUN.
+ */
+#define SCSI_SCAN_NO_RESPONSE		0
+#define SCSI_SCAN_TARGET_PRESENT	1
+#define SCSI_SCAN_LUN_PRESENT		2
+
+static const char *scsi_null_device_strs = "nullnullnullnull";
+
+#define MAX_SCSI_LUNS	512
+
+static u64 max_scsi_luns = MAX_SCSI_LUNS;
+
+module_param_named(max_luns, max_scsi_luns, ullong, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(max_luns,
+		 "last scsi LUN (should be between 1 and 2^64-1)");
+
+#ifdef CONFIG_SCSI_SCAN_ASYNC
+#define SCSI_SCAN_TYPE_DEFAULT "async"
+#else
+#define SCSI_SCAN_TYPE_DEFAULT "sync"
+#endif
+
+char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
+
+module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type),
+		    S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(scan, "sync, async, manual, or none. "
+		 "Setting to 'manual' disables automatic scanning, but allows "
+		 "for manual device scan via the 'scan' sysfs attribute.");
+
+static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ + 18;
+
+module_param_named(inq_timeout, scsi_inq_timeout, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(inq_timeout, 
+		 "Timeout (in seconds) waiting for devices to answer INQUIRY."
+		 " Default is 20. Some devices may need more; most need less.");
+
+/* This lock protects only this list */
+static DEFINE_SPINLOCK(async_scan_lock);
+static LIST_HEAD(scanning_hosts);
+
+struct async_scan_data {
+	struct list_head list;
+	struct Scsi_Host *shost;
+	struct completion prev_finished;
+};
+
+/**
+ * scsi_complete_async_scans - Wait for asynchronous scans to complete
+ *
+ * When this function returns, any host which started scanning before
+ * this function was called will have finished its scan.  Hosts which
+ * started scanning after this function was called may or may not have
+ * finished.
+ */
+int scsi_complete_async_scans(void)
+{
+	struct async_scan_data *data;
+
+	do {
+		if (list_empty(&scanning_hosts))
+			return 0;
+		/* If we can't get memory immediately, that's OK.  Just
+		 * sleep a little.  Even if we never get memory, the async
+		 * scans will finish eventually.
+		 */
+		data = kmalloc(sizeof(*data), GFP_KERNEL);
+		if (!data)
+			msleep(1);
+	} while (!data);
+
+	data->shost = NULL;
+	init_completion(&data->prev_finished);
+
+	spin_lock(&async_scan_lock);
+	/* Check that there's still somebody else on the list */
+	if (list_empty(&scanning_hosts))
+		goto done;
+	list_add_tail(&data->list, &scanning_hosts);
+	spin_unlock(&async_scan_lock);
+
+	printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n");
+	wait_for_completion(&data->prev_finished);
+
+	spin_lock(&async_scan_lock);
+	list_del(&data->list);
+	if (!list_empty(&scanning_hosts)) {
+		struct async_scan_data *next = list_entry(scanning_hosts.next,
+				struct async_scan_data, list);
+		complete(&next->prev_finished);
+	}
+ done:
+	spin_unlock(&async_scan_lock);
+
+	kfree(data);
+	return 0;
+}
+
+/**
+ * scsi_unlock_floptical - unlock device via a special MODE SENSE command
+ * @sdev:	scsi device to send command to
+ * @result:	area to store the result of the MODE SENSE
+ *
+ * Description:
+ *     Send a vendor specific MODE SENSE (not a MODE SELECT) command.
+ *     Called for BLIST_KEY devices.
+ **/
+static void scsi_unlock_floptical(struct scsi_device *sdev,
+				  unsigned char *result)
+{
+	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
+
+	sdev_printk(KERN_NOTICE, sdev, "unlocking floptical drive\n");
+	scsi_cmd[0] = MODE_SENSE;
+	scsi_cmd[1] = 0;
+	scsi_cmd[2] = 0x2e;
+	scsi_cmd[3] = 0;
+	scsi_cmd[4] = 0x2a;     /* size */
+	scsi_cmd[5] = 0;
+	scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE, result, 0x2a, NULL,
+			 SCSI_TIMEOUT, 3, NULL);
+}
+
+/**
+ * scsi_alloc_sdev - allocate and setup a scsi_Device
+ * @starget: which target to allocate a &scsi_device for
+ * @lun: which lun
+ * @hostdata: usually NULL and set by ->slave_alloc instead
+ *
+ * Description:
+ *     Allocate, initialize for io, and return a pointer to a scsi_Device.
+ *     Stores the @shost, @channel, @id, and @lun in the scsi_Device, and
+ *     adds scsi_Device to the appropriate list.
+ *
+ * Return value:
+ *     scsi_Device pointer, or NULL on failure.
+ **/
+static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
+					   u64 lun, void *hostdata)
+{
+	struct scsi_device *sdev;
+	int display_failure_msg = 1, ret;
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+
+	sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
+		       GFP_KERNEL);
+	if (!sdev)
+		goto out;
+
+	sdev->vendor = scsi_null_device_strs;
+	sdev->model = scsi_null_device_strs;
+	sdev->rev = scsi_null_device_strs;
+	sdev->host = shost;
+	sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
+	sdev->id = starget->id;
+	sdev->lun = lun;
+	sdev->channel = starget->channel;
+	mutex_init(&sdev->state_mutex);
+	sdev->sdev_state = SDEV_CREATED;
+	INIT_LIST_HEAD(&sdev->siblings);
+	INIT_LIST_HEAD(&sdev->same_target_siblings);
+	INIT_LIST_HEAD(&sdev->starved_entry);
+	INIT_LIST_HEAD(&sdev->event_list);
+	spin_lock_init(&sdev->list_lock);
+	mutex_init(&sdev->inquiry_mutex);
+	INIT_WORK(&sdev->event_work, scsi_evt_thread);
+	INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue);
+
+	sdev->sdev_gendev.parent = get_device(&starget->dev);
+	sdev->sdev_target = starget;
+
+	/* usually NULL and set by ->slave_alloc instead */
+	sdev->hostdata = hostdata;
+
+	/* if the device needs this changing, it may do so in the
+	 * slave_configure function */
+	sdev->max_device_blocked = SCSI_DEFAULT_DEVICE_BLOCKED;
+
+	/*
+	 * Some low level driver could use device->type
+	 */
+	sdev->type = -1;
+
+	/*
+	 * Assume that the device will have handshaking problems,
+	 * and then fix this field later if it turns out it
+	 * doesn't
+	 */
+	sdev->borken = 1;
+
+	sdev->request_queue = scsi_mq_alloc_queue(sdev);
+	if (!sdev->request_queue) {
+		/* release fn is set up in scsi_sysfs_device_initialise, so
+		 * have to free and put manually here */
+		put_device(&starget->dev);
+		kfree(sdev);
+		goto out;
+	}
+	WARN_ON_ONCE(!blk_get_queue(sdev->request_queue));
+	sdev->request_queue->queuedata = sdev;
+
+	scsi_change_queue_depth(sdev, sdev->host->cmd_per_lun ?
+					sdev->host->cmd_per_lun : 1);
+
+	scsi_sysfs_device_initialize(sdev);
+
+	if (shost->hostt->slave_alloc) {
+		ret = shost->hostt->slave_alloc(sdev);
+		if (ret) {
+			/*
+			 * if LLDD reports slave not present, don't clutter
+			 * console with alloc failure messages
+			 */
+			if (ret == -ENXIO)
+				display_failure_msg = 0;
+			goto out_device_destroy;
+		}
+	}
+
+	return sdev;
+
+out_device_destroy:
+	__scsi_remove_device(sdev);
+out:
+	if (display_failure_msg)
+		printk(ALLOC_FAILURE_MSG, __func__);
+	return NULL;
+}
+
+static void scsi_target_destroy(struct scsi_target *starget)
+{
+	struct device *dev = &starget->dev;
+	struct Scsi_Host *shost = dev_to_shost(dev->parent);
+	unsigned long flags;
+
+	BUG_ON(starget->state == STARGET_DEL);
+	starget->state = STARGET_DEL;
+	transport_destroy_device(dev);
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (shost->hostt->target_destroy)
+		shost->hostt->target_destroy(starget);
+	list_del_init(&starget->siblings);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	put_device(dev);
+}
+
+static void scsi_target_dev_release(struct device *dev)
+{
+	struct device *parent = dev->parent;
+	struct scsi_target *starget = to_scsi_target(dev);
+
+	kfree(starget);
+	put_device(parent);
+}
+
+static struct device_type scsi_target_type = {
+	.name =		"scsi_target",
+	.release =	scsi_target_dev_release,
+};
+
+int scsi_is_target_device(const struct device *dev)
+{
+	return dev->type == &scsi_target_type;
+}
+EXPORT_SYMBOL(scsi_is_target_device);
+
+static struct scsi_target *__scsi_find_target(struct device *parent,
+					      int channel, uint id)
+{
+	struct scsi_target *starget, *found_starget = NULL;
+	struct Scsi_Host *shost = dev_to_shost(parent);
+	/*
+	 * Search for an existing target for this sdev.
+	 */
+	list_for_each_entry(starget, &shost->__targets, siblings) {
+		if (starget->id == id &&
+		    starget->channel == channel) {
+			found_starget = starget;
+			break;
+		}
+	}
+	if (found_starget)
+		get_device(&found_starget->dev);
+
+	return found_starget;
+}
+
+/**
+ * scsi_target_reap_ref_release - remove target from visibility
+ * @kref: the reap_ref in the target being released
+ *
+ * Called on last put of reap_ref, which is the indication that no device
+ * under this target is visible anymore, so render the target invisible in
+ * sysfs.  Note: we have to be in user context here because the target reaps
+ * should be done in places where the scsi device visibility is being removed.
+ */
+static void scsi_target_reap_ref_release(struct kref *kref)
+{
+	struct scsi_target *starget
+		= container_of(kref, struct scsi_target, reap_ref);
+
+	/*
+	 * if we get here and the target is still in a CREATED state that
+	 * means it was allocated but never made visible (because a scan
+	 * turned up no LUNs), so don't call device_del() on it.
+	 */
+	if ((starget->state != STARGET_CREATED) &&
+	    (starget->state != STARGET_CREATED_REMOVE)) {
+		transport_remove_device(&starget->dev);
+		device_del(&starget->dev);
+	}
+	scsi_target_destroy(starget);
+}
+
+static void scsi_target_reap_ref_put(struct scsi_target *starget)
+{
+	kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
+}
+
+/**
+ * scsi_alloc_target - allocate a new or find an existing target
+ * @parent:	parent of the target (need not be a scsi host)
+ * @channel:	target channel number (zero if no channels)
+ * @id:		target id number
+ *
+ * Return an existing target if one exists, provided it hasn't already
+ * gone into STARGET_DEL state, otherwise allocate a new target.
+ *
+ * The target is returned with an incremented reference, so the caller
+ * is responsible for both reaping and doing a last put
+ */
+static struct scsi_target *scsi_alloc_target(struct device *parent,
+					     int channel, uint id)
+{
+	struct Scsi_Host *shost = dev_to_shost(parent);
+	struct device *dev = NULL;
+	unsigned long flags;
+	const int size = sizeof(struct scsi_target)
+		+ shost->transportt->target_size;
+	struct scsi_target *starget;
+	struct scsi_target *found_target;
+	int error, ref_got;
+
+	starget = kzalloc(size, GFP_KERNEL);
+	if (!starget) {
+		printk(KERN_ERR "%s: allocation failure\n", __func__);
+		return NULL;
+	}
+	dev = &starget->dev;
+	device_initialize(dev);
+	kref_init(&starget->reap_ref);
+	dev->parent = get_device(parent);
+	dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
+	dev->bus = &scsi_bus_type;
+	dev->type = &scsi_target_type;
+	starget->id = id;
+	starget->channel = channel;
+	starget->can_queue = 0;
+	INIT_LIST_HEAD(&starget->siblings);
+	INIT_LIST_HEAD(&starget->devices);
+	starget->state = STARGET_CREATED;
+	starget->scsi_level = SCSI_2;
+	starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
+ retry:
+	spin_lock_irqsave(shost->host_lock, flags);
+
+	found_target = __scsi_find_target(parent, channel, id);
+	if (found_target)
+		goto found;
+
+	list_add_tail(&starget->siblings, &shost->__targets);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	/* allocate and add */
+	transport_setup_device(dev);
+	if (shost->hostt->target_alloc) {
+		error = shost->hostt->target_alloc(starget);
+
+		if(error) {
+			if (error != -ENXIO)
+				dev_err(dev, "target allocation failed, error %d\n", error);
+			/* don't want scsi_target_reap to do the final
+			 * put because it will be under the host lock */
+			scsi_target_destroy(starget);
+			return NULL;
+		}
+	}
+	get_device(dev);
+
+	return starget;
+
+ found:
+	/*
+	 * release routine already fired if kref is zero, so if we can still
+	 * take the reference, the target must be alive.  If we can't, it must
+	 * be dying and we need to wait for a new target
+	 */
+	ref_got = kref_get_unless_zero(&found_target->reap_ref);
+
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	if (ref_got) {
+		put_device(dev);
+		return found_target;
+	}
+	/*
+	 * Unfortunately, we found a dying target; need to wait until it's
+	 * dead before we can get a new one.  There is an anomaly here.  We
+	 * *should* call scsi_target_reap() to balance the kref_get() of the
+	 * reap_ref above.  However, since the target being released, it's
+	 * already invisible and the reap_ref is irrelevant.  If we call
+	 * scsi_target_reap() we might spuriously do another device_del() on
+	 * an already invisible target.
+	 */
+	put_device(&found_target->dev);
+	/*
+	 * length of time is irrelevant here, we just want to yield the CPU
+	 * for a tick to avoid busy waiting for the target to die.
+	 */
+	msleep(1);
+	goto retry;
+}
+
+/**
+ * scsi_target_reap - check to see if target is in use and destroy if not
+ * @starget: target to be checked
+ *
+ * This is used after removing a LUN or doing a last put of the target
+ * it checks atomically that nothing is using the target and removes
+ * it if so.
+ */
+void scsi_target_reap(struct scsi_target *starget)
+{
+	/*
+	 * serious problem if this triggers: STARGET_DEL is only set in the if
+	 * the reap_ref drops to zero, so we're trying to do another final put
+	 * on an already released kref
+	 */
+	BUG_ON(starget->state == STARGET_DEL);
+	scsi_target_reap_ref_put(starget);
+}
+
+/**
+ * scsi_sanitize_inquiry_string - remove non-graphical chars from an
+ *                                INQUIRY result string
+ * @s: INQUIRY result string to sanitize
+ * @len: length of the string
+ *
+ * Description:
+ *	The SCSI spec says that INQUIRY vendor, product, and revision
+ *	strings must consist entirely of graphic ASCII characters,
+ *	padded on the right with spaces.  Since not all devices obey
+ *	this rule, we will replace non-graphic or non-ASCII characters
+ *	with spaces.  Exception: a NUL character is interpreted as a
+ *	string terminator, so all the following characters are set to
+ *	spaces.
+ **/
+void scsi_sanitize_inquiry_string(unsigned char *s, int len)
+{
+	int terminated = 0;
+
+	for (; len > 0; (--len, ++s)) {
+		if (*s == 0)
+			terminated = 1;
+		if (terminated || *s < 0x20 || *s > 0x7e)
+			*s = ' ';
+	}
+}
+EXPORT_SYMBOL(scsi_sanitize_inquiry_string);
+
+/**
+ * scsi_probe_lun - probe a single LUN using a SCSI INQUIRY
+ * @sdev:	scsi_device to probe
+ * @inq_result:	area to store the INQUIRY result
+ * @result_len: len of inq_result
+ * @bflags:	store any bflags found here
+ *
+ * Description:
+ *     Probe the lun associated with @req using a standard SCSI INQUIRY;
+ *
+ *     If the INQUIRY is successful, zero is returned and the
+ *     INQUIRY data is in @inq_result; the scsi_level and INQUIRY length
+ *     are copied to the scsi_device any flags value is stored in *@bflags.
+ **/
+static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
+			  int result_len, blist_flags_t *bflags)
+{
+	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
+	int first_inquiry_len, try_inquiry_len, next_inquiry_len;
+	int response_len = 0;
+	int pass, count, result;
+	struct scsi_sense_hdr sshdr;
+
+	*bflags = 0;
+
+	/* Perform up to 3 passes.  The first pass uses a conservative
+	 * transfer length of 36 unless sdev->inquiry_len specifies a
+	 * different value. */
+	first_inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
+	try_inquiry_len = first_inquiry_len;
+	pass = 1;
+
+ next_pass:
+	SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
+				"scsi scan: INQUIRY pass %d length %d\n",
+				pass, try_inquiry_len));
+
+	/* Each pass gets up to three chances to ignore Unit Attention */
+	for (count = 0; count < 3; ++count) {
+		int resid;
+
+		memset(scsi_cmd, 0, 6);
+		scsi_cmd[0] = INQUIRY;
+		scsi_cmd[4] = (unsigned char) try_inquiry_len;
+
+		memset(inq_result, 0, try_inquiry_len);
+
+		result = scsi_execute_req(sdev,  scsi_cmd, DMA_FROM_DEVICE,
+					  inq_result, try_inquiry_len, &sshdr,
+					  HZ / 2 + HZ * scsi_inq_timeout, 3,
+					  &resid);
+
+		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
+				"scsi scan: INQUIRY %s with code 0x%x\n",
+				result ? "failed" : "successful", result));
+
+		if (result) {
+			/*
+			 * not-ready to ready transition [asc/ascq=0x28/0x0]
+			 * or power-on, reset [asc/ascq=0x29/0x0], continue.
+			 * INQUIRY should not yield UNIT_ATTENTION
+			 * but many buggy devices do so anyway. 
+			 */
+			if (driver_byte(result) == DRIVER_SENSE &&
+			    scsi_sense_valid(&sshdr)) {
+				if ((sshdr.sense_key == UNIT_ATTENTION) &&
+				    ((sshdr.asc == 0x28) ||
+				     (sshdr.asc == 0x29)) &&
+				    (sshdr.ascq == 0))
+					continue;
+			}
+		} else {
+			/*
+			 * if nothing was transferred, we try
+			 * again. It's a workaround for some USB
+			 * devices.
+			 */
+			if (resid == try_inquiry_len)
+				continue;
+		}
+		break;
+	}
+
+	if (result == 0) {
+		scsi_sanitize_inquiry_string(&inq_result[8], 8);
+		scsi_sanitize_inquiry_string(&inq_result[16], 16);
+		scsi_sanitize_inquiry_string(&inq_result[32], 4);
+
+		response_len = inq_result[4] + 5;
+		if (response_len > 255)
+			response_len = first_inquiry_len;	/* sanity */
+
+		/*
+		 * Get any flags for this device.
+		 *
+		 * XXX add a bflags to scsi_device, and replace the
+		 * corresponding bit fields in scsi_device, so bflags
+		 * need not be passed as an argument.
+		 */
+		*bflags = scsi_get_device_flags(sdev, &inq_result[8],
+				&inq_result[16]);
+
+		/* When the first pass succeeds we gain information about
+		 * what larger transfer lengths might work. */
+		if (pass == 1) {
+			if (BLIST_INQUIRY_36 & *bflags)
+				next_inquiry_len = 36;
+			else if (sdev->inquiry_len)
+				next_inquiry_len = sdev->inquiry_len;
+			else
+				next_inquiry_len = response_len;
+
+			/* If more data is available perform the second pass */
+			if (next_inquiry_len > try_inquiry_len) {
+				try_inquiry_len = next_inquiry_len;
+				pass = 2;
+				goto next_pass;
+			}
+		}
+
+	} else if (pass == 2) {
+		sdev_printk(KERN_INFO, sdev,
+			    "scsi scan: %d byte inquiry failed.  "
+			    "Consider BLIST_INQUIRY_36 for this device\n",
+			    try_inquiry_len);
+
+		/* If this pass failed, the third pass goes back and transfers
+		 * the same amount as we successfully got in the first pass. */
+		try_inquiry_len = first_inquiry_len;
+		pass = 3;
+		goto next_pass;
+	}
+
+	/* If the last transfer attempt got an error, assume the
+	 * peripheral doesn't exist or is dead. */
+	if (result)
+		return -EIO;
+
+	/* Don't report any more data than the device says is valid */
+	sdev->inquiry_len = min(try_inquiry_len, response_len);
+
+	/*
+	 * XXX Abort if the response length is less than 36? If less than
+	 * 32, the lookup of the device flags (above) could be invalid,
+	 * and it would be possible to take an incorrect action - we do
+	 * not want to hang because of a short INQUIRY. On the flip side,
+	 * if the device is spun down or becoming ready (and so it gives a
+	 * short INQUIRY), an abort here prevents any further use of the
+	 * device, including spin up.
+	 *
+	 * On the whole, the best approach seems to be to assume the first
+	 * 36 bytes are valid no matter what the device says.  That's
+	 * better than copying < 36 bytes to the inquiry-result buffer
+	 * and displaying garbage for the Vendor, Product, or Revision
+	 * strings.
+	 */
+	if (sdev->inquiry_len < 36) {
+		if (!sdev->host->short_inquiry) {
+			shost_printk(KERN_INFO, sdev->host,
+				    "scsi scan: INQUIRY result too short (%d),"
+				    " using 36\n", sdev->inquiry_len);
+			sdev->host->short_inquiry = 1;
+		}
+		sdev->inquiry_len = 36;
+	}
+
+	/*
+	 * Related to the above issue:
+	 *
+	 * XXX Devices (disk or all?) should be sent a TEST UNIT READY,
+	 * and if not ready, sent a START_STOP to start (maybe spin up) and
+	 * then send the INQUIRY again, since the INQUIRY can change after
+	 * a device is initialized.
+	 *
+	 * Ideally, start a device if explicitly asked to do so.  This
+	 * assumes that a device is spun up on power on, spun down on
+	 * request, and then spun up on request.
+	 */
+
+	/*
+	 * The scanning code needs to know the scsi_level, even if no
+	 * device is attached at LUN 0 (SCSI_SCAN_TARGET_PRESENT) so
+	 * non-zero LUNs can be scanned.
+	 */
+	sdev->scsi_level = inq_result[2] & 0x07;
+	if (sdev->scsi_level >= 2 ||
+	    (sdev->scsi_level == 1 && (inq_result[3] & 0x0f) == 1))
+		sdev->scsi_level++;
+	sdev->sdev_target->scsi_level = sdev->scsi_level;
+
+	/*
+	 * If SCSI-2 or lower, and if the transport requires it,
+	 * store the LUN value in CDB[1].
+	 */
+	sdev->lun_in_cdb = 0;
+	if (sdev->scsi_level <= SCSI_2 &&
+	    sdev->scsi_level != SCSI_UNKNOWN &&
+	    !sdev->host->no_scsi2_lun_in_cdb)
+		sdev->lun_in_cdb = 1;
+
+	return 0;
+}
+
+/**
+ * scsi_add_lun - allocate and fully initialze a scsi_device
+ * @sdev:	holds information to be stored in the new scsi_device
+ * @inq_result:	holds the result of a previous INQUIRY to the LUN
+ * @bflags:	black/white list flag
+ * @async:	1 if this device is being scanned asynchronously
+ *
+ * Description:
+ *     Initialize the scsi_device @sdev.  Optionally set fields based
+ *     on values in *@bflags.
+ *
+ * Return:
+ *     SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
+ *     SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
+ **/
+static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
+		blist_flags_t *bflags, int async)
+{
+	int ret;
+
+	/*
+	 * XXX do not save the inquiry, since it can change underneath us,
+	 * save just vendor/model/rev.
+	 *
+	 * Rather than save it and have an ioctl that retrieves the saved
+	 * value, have an ioctl that executes the same INQUIRY code used
+	 * in scsi_probe_lun, let user level programs doing INQUIRY
+	 * scanning run at their own risk, or supply a user level program
+	 * that can correctly scan.
+	 */
+
+	/*
+	 * Copy at least 36 bytes of INQUIRY data, so that we don't
+	 * dereference unallocated memory when accessing the Vendor,
+	 * Product, and Revision strings.  Badly behaved devices may set
+	 * the INQUIRY Additional Length byte to a small value, indicating
+	 * these strings are invalid, but often they contain plausible data
+	 * nonetheless.  It doesn't matter if the device sent < 36 bytes
+	 * total, since scsi_probe_lun() initializes inq_result with 0s.
+	 */
+	sdev->inquiry = kmemdup(inq_result,
+				max_t(size_t, sdev->inquiry_len, 36),
+				GFP_KERNEL);
+	if (sdev->inquiry == NULL)
+		return SCSI_SCAN_NO_RESPONSE;
+
+	sdev->vendor = (char *) (sdev->inquiry + 8);
+	sdev->model = (char *) (sdev->inquiry + 16);
+	sdev->rev = (char *) (sdev->inquiry + 32);
+
+	if (strncmp(sdev->vendor, "ATA     ", 8) == 0) {
+		/*
+		 * sata emulation layer device.  This is a hack to work around
+		 * the SATL power management specifications which state that
+		 * when the SATL detects the device has gone into standby
+		 * mode, it shall respond with NOT READY.
+		 */
+		sdev->allow_restart = 1;
+	}
+
+	if (*bflags & BLIST_ISROM) {
+		sdev->type = TYPE_ROM;
+		sdev->removable = 1;
+	} else {
+		sdev->type = (inq_result[0] & 0x1f);
+		sdev->removable = (inq_result[1] & 0x80) >> 7;
+
+		/*
+		 * some devices may respond with wrong type for
+		 * well-known logical units. Force well-known type
+		 * to enumerate them correctly.
+		 */
+		if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
+			sdev_printk(KERN_WARNING, sdev,
+				"%s: correcting incorrect peripheral device type 0x%x for W-LUN 0x%16xhN\n",
+				__func__, sdev->type, (unsigned int)sdev->lun);
+			sdev->type = TYPE_WLUN;
+		}
+
+	}
+
+	if (sdev->type == TYPE_RBC || sdev->type == TYPE_ROM) {
+		/* RBC and MMC devices can return SCSI-3 compliance and yet
+		 * still not support REPORT LUNS, so make them act as
+		 * BLIST_NOREPORTLUN unless BLIST_REPORTLUN2 is
+		 * specifically set */
+		if ((*bflags & BLIST_REPORTLUN2) == 0)
+			*bflags |= BLIST_NOREPORTLUN;
+	}
+
+	/*
+	 * For a peripheral qualifier (PQ) value of 1 (001b), the SCSI
+	 * spec says: The device server is capable of supporting the
+	 * specified peripheral device type on this logical unit. However,
+	 * the physical device is not currently connected to this logical
+	 * unit.
+	 *
+	 * The above is vague, as it implies that we could treat 001 and
+	 * 011 the same. Stay compatible with previous code, and create a
+	 * scsi_device for a PQ of 1
+	 *
+	 * Don't set the device offline here; rather let the upper
+	 * level drivers eval the PQ to decide whether they should
+	 * attach. So remove ((inq_result[0] >> 5) & 7) == 1 check.
+	 */ 
+
+	sdev->inq_periph_qual = (inq_result[0] >> 5) & 7;
+	sdev->lockable = sdev->removable;
+	sdev->soft_reset = (inq_result[7] & 1) && ((inq_result[3] & 7) == 2);
+
+	if (sdev->scsi_level >= SCSI_3 ||
+			(sdev->inquiry_len > 56 && inq_result[56] & 0x04))
+		sdev->ppr = 1;
+	if (inq_result[7] & 0x60)
+		sdev->wdtr = 1;
+	if (inq_result[7] & 0x10)
+		sdev->sdtr = 1;
+
+	sdev_printk(KERN_NOTICE, sdev, "%s %.8s %.16s %.4s PQ: %d "
+			"ANSI: %d%s\n", scsi_device_type(sdev->type),
+			sdev->vendor, sdev->model, sdev->rev,
+			sdev->inq_periph_qual, inq_result[2] & 0x07,
+			(inq_result[3] & 0x0f) == 1 ? " CCS" : "");
+
+	if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
+	    !(*bflags & BLIST_NOTQ)) {
+		sdev->tagged_supported = 1;
+		sdev->simple_tags = 1;
+	}
+
+	/*
+	 * Some devices (Texel CD ROM drives) have handshaking problems
+	 * when used with the Seagate controllers. borken is initialized
+	 * to 1, and then set it to 0 here.
+	 */
+	if ((*bflags & BLIST_BORKEN) == 0)
+		sdev->borken = 0;
+
+	if (*bflags & BLIST_NO_ULD_ATTACH)
+		sdev->no_uld_attach = 1;
+
+	/*
+	 * Apparently some really broken devices (contrary to the SCSI
+	 * standards) need to be selected without asserting ATN
+	 */
+	if (*bflags & BLIST_SELECT_NO_ATN)
+		sdev->select_no_atn = 1;
+
+	/*
+	 * Maximum 512 sector transfer length
+	 * broken RA4x00 Compaq Disk Array
+	 */
+	if (*bflags & BLIST_MAX_512)
+		blk_queue_max_hw_sectors(sdev->request_queue, 512);
+	/*
+	 * Max 1024 sector transfer length for targets that report incorrect
+	 * max/optimal lengths and relied on the old block layer safe default
+	 */
+	else if (*bflags & BLIST_MAX_1024)
+		blk_queue_max_hw_sectors(sdev->request_queue, 1024);
+
+	/*
+	 * Some devices may not want to have a start command automatically
+	 * issued when a device is added.
+	 */
+	if (*bflags & BLIST_NOSTARTONADD)
+		sdev->no_start_on_add = 1;
+
+	if (*bflags & BLIST_SINGLELUN)
+		scsi_target(sdev)->single_lun = 1;
+
+	sdev->use_10_for_rw = 1;
+
+	/* some devices don't like REPORT SUPPORTED OPERATION CODES
+	 * and will simply timeout causing sd_mod init to take a very
+	 * very long time */
+	if (*bflags & BLIST_NO_RSOC)
+		sdev->no_report_opcodes = 1;
+
+	/* set the device running here so that slave configure
+	 * may do I/O */
+	mutex_lock(&sdev->state_mutex);
+	ret = scsi_device_set_state(sdev, SDEV_RUNNING);
+	if (ret)
+		ret = scsi_device_set_state(sdev, SDEV_BLOCK);
+	mutex_unlock(&sdev->state_mutex);
+
+	if (ret) {
+		sdev_printk(KERN_ERR, sdev,
+			    "in wrong state %s to complete scan\n",
+			    scsi_device_state_name(sdev->sdev_state));
+		return SCSI_SCAN_NO_RESPONSE;
+	}
+
+	if (*bflags & BLIST_NOT_LOCKABLE)
+		sdev->lockable = 0;
+
+	if (*bflags & BLIST_RETRY_HWERROR)
+		sdev->retry_hwerror = 1;
+
+	if (*bflags & BLIST_NO_DIF)
+		sdev->no_dif = 1;
+
+	if (*bflags & BLIST_UNMAP_LIMIT_WS)
+		sdev->unmap_limit_for_ws = 1;
+
+	sdev->eh_timeout = SCSI_DEFAULT_EH_TIMEOUT;
+
+	if (*bflags & BLIST_TRY_VPD_PAGES)
+		sdev->try_vpd_pages = 1;
+	else if (*bflags & BLIST_SKIP_VPD_PAGES)
+		sdev->skip_vpd_pages = 1;
+
+	transport_configure_device(&sdev->sdev_gendev);
+
+	if (sdev->host->hostt->slave_configure) {
+		ret = sdev->host->hostt->slave_configure(sdev);
+		if (ret) {
+			/*
+			 * if LLDD reports slave not present, don't clutter
+			 * console with alloc failure messages
+			 */
+			if (ret != -ENXIO) {
+				sdev_printk(KERN_ERR, sdev,
+					"failed to configure device\n");
+			}
+			return SCSI_SCAN_NO_RESPONSE;
+		}
+	}
+
+	if (sdev->scsi_level >= SCSI_3)
+		scsi_attach_vpd(sdev);
+
+	sdev->max_queue_depth = sdev->queue_depth;
+	sdev->sdev_bflags = *bflags;
+
+	/*
+	 * Ok, the device is now all set up, we can
+	 * register it and tell the rest of the kernel
+	 * about it.
+	 */
+	if (!async && scsi_sysfs_add_sdev(sdev) != 0)
+		return SCSI_SCAN_NO_RESPONSE;
+
+	return SCSI_SCAN_LUN_PRESENT;
+}
+
+#ifdef CONFIG_SCSI_LOGGING
+/** 
+ * scsi_inq_str - print INQUIRY data from min to max index, strip trailing whitespace
+ * @buf:   Output buffer with at least end-first+1 bytes of space
+ * @inq:   Inquiry buffer (input)
+ * @first: Offset of string into inq
+ * @end:   Index after last character in inq
+ */
+static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
+				   unsigned first, unsigned end)
+{
+	unsigned term = 0, idx;
+
+	for (idx = 0; idx + first < end && idx + first < inq[4] + 5; idx++) {
+		if (inq[idx+first] > ' ') {
+			buf[idx] = inq[idx+first];
+			term = idx+1;
+		} else {
+			buf[idx] = ' ';
+		}
+	}
+	buf[term] = 0;
+	return buf;
+}
+#endif
+
+/**
+ * scsi_probe_and_add_lun - probe a LUN, if a LUN is found add it
+ * @starget:	pointer to target device structure
+ * @lun:	LUN of target device
+ * @bflagsp:	store bflags here if not NULL
+ * @sdevp:	probe the LUN corresponding to this scsi_device
+ * @rescan:     if not equal to SCSI_SCAN_INITIAL skip some code only
+ *              needed on first scan
+ * @hostdata:	passed to scsi_alloc_sdev()
+ *
+ * Description:
+ *     Call scsi_probe_lun, if a LUN with an attached device is found,
+ *     allocate and set it up by calling scsi_add_lun.
+ *
+ * Return:
+ *
+ *   - SCSI_SCAN_NO_RESPONSE: could not allocate or setup a scsi_device
+ *   - SCSI_SCAN_TARGET_PRESENT: target responded, but no device is
+ *         attached at the LUN
+ *   - SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized
+ **/
+static int scsi_probe_and_add_lun(struct scsi_target *starget,
+				  u64 lun, blist_flags_t *bflagsp,
+				  struct scsi_device **sdevp,
+				  enum scsi_scan_mode rescan,
+				  void *hostdata)
+{
+	struct scsi_device *sdev;
+	unsigned char *result;
+	blist_flags_t bflags;
+	int res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+
+	/*
+	 * The rescan flag is used as an optimization, the first scan of a
+	 * host adapter calls into here with rescan == 0.
+	 */
+	sdev = scsi_device_lookup_by_target(starget, lun);
+	if (sdev) {
+		if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
+			SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
+				"scsi scan: device exists on %s\n",
+				dev_name(&sdev->sdev_gendev)));
+			if (sdevp)
+				*sdevp = sdev;
+			else
+				scsi_device_put(sdev);
+
+			if (bflagsp)
+				*bflagsp = scsi_get_device_flags(sdev,
+								 sdev->vendor,
+								 sdev->model);
+			return SCSI_SCAN_LUN_PRESENT;
+		}
+		scsi_device_put(sdev);
+	} else
+		sdev = scsi_alloc_sdev(starget, lun, hostdata);
+	if (!sdev)
+		goto out;
+
+	result = kmalloc(result_len, GFP_KERNEL |
+			((shost->unchecked_isa_dma) ? __GFP_DMA : 0));
+	if (!result)
+		goto out_free_sdev;
+
+	if (scsi_probe_lun(sdev, result, result_len, &bflags))
+		goto out_free_result;
+
+	if (bflagsp)
+		*bflagsp = bflags;
+	/*
+	 * result contains valid SCSI INQUIRY data.
+	 */
+	if ((result[0] >> 5) == 3) {
+		/*
+		 * For a Peripheral qualifier 3 (011b), the SCSI
+		 * spec says: The device server is not capable of
+		 * supporting a physical device on this logical
+		 * unit.
+		 *
+		 * For disks, this implies that there is no
+		 * logical disk configured at sdev->lun, but there
+		 * is a target id responding.
+		 */
+		SCSI_LOG_SCAN_BUS(2, sdev_printk(KERN_INFO, sdev, "scsi scan:"
+				   " peripheral qualifier of 3, device not"
+				   " added\n"))
+		if (lun == 0) {
+			SCSI_LOG_SCAN_BUS(1, {
+				unsigned char vend[9];
+				unsigned char mod[17];
+
+				sdev_printk(KERN_INFO, sdev,
+					"scsi scan: consider passing scsi_mod."
+					"dev_flags=%s:%s:0x240 or 0x1000240\n",
+					scsi_inq_str(vend, result, 8, 16),
+					scsi_inq_str(mod, result, 16, 32));
+			});
+
+		}
+
+		res = SCSI_SCAN_TARGET_PRESENT;
+		goto out_free_result;
+	}
+
+	/*
+	 * Some targets may set slight variations of PQ and PDT to signal
+	 * that no LUN is present, so don't add sdev in these cases.
+	 * Two specific examples are:
+	 * 1) NetApp targets: return PQ=1, PDT=0x1f
+	 * 2) USB UFI: returns PDT=0x1f, with the PQ bits being "reserved"
+	 *    in the UFI 1.0 spec (we cannot rely on reserved bits).
+	 *
+	 * References:
+	 * 1) SCSI SPC-3, pp. 145-146
+	 * PQ=1: "A peripheral device having the specified peripheral
+	 * device type is not connected to this logical unit. However, the
+	 * device server is capable of supporting the specified peripheral
+	 * device type on this logical unit."
+	 * PDT=0x1f: "Unknown or no device type"
+	 * 2) USB UFI 1.0, p. 20
+	 * PDT=00h Direct-access device (floppy)
+	 * PDT=1Fh none (no FDD connected to the requested logical unit)
+	 */
+	if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
+	    (result[0] & 0x1f) == 0x1f &&
+	    !scsi_is_wlun(lun)) {
+		SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
+					"scsi scan: peripheral device type"
+					" of 31, no device added\n"));
+		res = SCSI_SCAN_TARGET_PRESENT;
+		goto out_free_result;
+	}
+
+	res = scsi_add_lun(sdev, result, &bflags, shost->async_scan);
+	if (res == SCSI_SCAN_LUN_PRESENT) {
+		if (bflags & BLIST_KEY) {
+			sdev->lockable = 0;
+			scsi_unlock_floptical(sdev, result);
+		}
+	}
+
+ out_free_result:
+	kfree(result);
+ out_free_sdev:
+	if (res == SCSI_SCAN_LUN_PRESENT) {
+		if (sdevp) {
+			if (scsi_device_get(sdev) == 0) {
+				*sdevp = sdev;
+			} else {
+				__scsi_remove_device(sdev);
+				res = SCSI_SCAN_NO_RESPONSE;
+			}
+		}
+	} else
+		__scsi_remove_device(sdev);
+ out:
+	return res;
+}
+
+/**
+ * scsi_sequential_lun_scan - sequentially scan a SCSI target
+ * @starget:	pointer to target structure to scan
+ * @bflags:	black/white list flag for LUN 0
+ * @scsi_level: Which version of the standard does this device adhere to
+ * @rescan:     passed to scsi_probe_add_lun()
+ *
+ * Description:
+ *     Generally, scan from LUN 1 (LUN 0 is assumed to already have been
+ *     scanned) to some maximum lun until a LUN is found with no device
+ *     attached. Use the bflags to figure out any oddities.
+ *
+ *     Modifies sdevscan->lun.
+ **/
+static void scsi_sequential_lun_scan(struct scsi_target *starget,
+				     blist_flags_t bflags, int scsi_level,
+				     enum scsi_scan_mode rescan)
+{
+	uint max_dev_lun;
+	u64 sparse_lun, lun;
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+
+	SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
+		"scsi scan: Sequential scan\n"));
+
+	max_dev_lun = min(max_scsi_luns, shost->max_lun);
+	/*
+	 * If this device is known to support sparse multiple units,
+	 * override the other settings, and scan all of them. Normally,
+	 * SCSI-3 devices should be scanned via the REPORT LUNS.
+	 */
+	if (bflags & BLIST_SPARSELUN) {
+		max_dev_lun = shost->max_lun;
+		sparse_lun = 1;
+	} else
+		sparse_lun = 0;
+
+	/*
+	 * If less than SCSI_1_CCS, and no special lun scanning, stop
+	 * scanning; this matches 2.4 behaviour, but could just be a bug
+	 * (to continue scanning a SCSI_1_CCS device).
+	 *
+	 * This test is broken.  We might not have any device on lun0 for
+	 * a sparselun device, and if that's the case then how would we
+	 * know the real scsi_level, eh?  It might make sense to just not
+	 * scan any SCSI_1 device for non-0 luns, but that check would best
+	 * go into scsi_alloc_sdev() and just have it return null when asked
+	 * to alloc an sdev for lun > 0 on an already found SCSI_1 device.
+	 *
+	if ((sdevscan->scsi_level < SCSI_1_CCS) &&
+	    ((bflags & (BLIST_FORCELUN | BLIST_SPARSELUN | BLIST_MAX5LUN))
+	     == 0))
+		return;
+	 */
+	/*
+	 * If this device is known to support multiple units, override
+	 * the other settings, and scan all of them.
+	 */
+	if (bflags & BLIST_FORCELUN)
+		max_dev_lun = shost->max_lun;
+	/*
+	 * REGAL CDC-4X: avoid hang after LUN 4
+	 */
+	if (bflags & BLIST_MAX5LUN)
+		max_dev_lun = min(5U, max_dev_lun);
+	/*
+	 * Do not scan SCSI-2 or lower device past LUN 7, unless
+	 * BLIST_LARGELUN.
+	 */
+	if (scsi_level < SCSI_3 && !(bflags & BLIST_LARGELUN))
+		max_dev_lun = min(8U, max_dev_lun);
+	else
+		max_dev_lun = min(256U, max_dev_lun);
+
+	/*
+	 * We have already scanned LUN 0, so start at LUN 1. Keep scanning
+	 * until we reach the max, or no LUN is found and we are not
+	 * sparse_lun.
+	 */
+	for (lun = 1; lun < max_dev_lun; ++lun)
+		if ((scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan,
+					    NULL) != SCSI_SCAN_LUN_PRESENT) &&
+		    !sparse_lun)
+			return;
+}
+
+/**
+ * scsi_report_lun_scan - Scan using SCSI REPORT LUN results
+ * @starget: which target
+ * @bflags: Zero or a mix of BLIST_NOLUN, BLIST_REPORTLUN2, or BLIST_NOREPORTLUN
+ * @rescan: nonzero if we can skip code only needed on first scan
+ *
+ * Description:
+ *   Fast scanning for modern (SCSI-3) devices by sending a REPORT LUN command.
+ *   Scan the resulting list of LUNs by calling scsi_probe_and_add_lun.
+ *
+ *   If BLINK_REPORTLUN2 is set, scan a target that supports more than 8
+ *   LUNs even if it's older than SCSI-3.
+ *   If BLIST_NOREPORTLUN is set, return 1 always.
+ *   If BLIST_NOLUN is set, return 0 always.
+ *   If starget->no_report_luns is set, return 1 always.
+ *
+ * Return:
+ *     0: scan completed (or no memory, so further scanning is futile)
+ *     1: could not scan with REPORT LUN
+ **/
+static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflags,
+				enum scsi_scan_mode rescan)
+{
+	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
+	unsigned int length;
+	u64 lun;
+	unsigned int num_luns;
+	unsigned int retries;
+	int result;
+	struct scsi_lun *lunp, *lun_data;
+	struct scsi_sense_hdr sshdr;
+	struct scsi_device *sdev;
+	struct Scsi_Host *shost = dev_to_shost(&starget->dev);
+	int ret = 0;
+
+	/*
+	 * Only support SCSI-3 and up devices if BLIST_NOREPORTLUN is not set.
+	 * Also allow SCSI-2 if BLIST_REPORTLUN2 is set and host adapter does
+	 * support more than 8 LUNs.
+	 * Don't attempt if the target doesn't support REPORT LUNS.
+	 */
+	if (bflags & BLIST_NOREPORTLUN)
+		return 1;
+	if (starget->scsi_level < SCSI_2 &&
+	    starget->scsi_level != SCSI_UNKNOWN)
+		return 1;
+	if (starget->scsi_level < SCSI_3 &&
+	    (!(bflags & BLIST_REPORTLUN2) || shost->max_lun <= 8))
+		return 1;
+	if (bflags & BLIST_NOLUN)
+		return 0;
+	if (starget->no_report_luns)
+		return 1;
+
+	if (!(sdev = scsi_device_lookup_by_target(starget, 0))) {
+		sdev = scsi_alloc_sdev(starget, 0, NULL);
+		if (!sdev)
+			return 0;
+		if (scsi_device_get(sdev)) {
+			__scsi_remove_device(sdev);
+			return 0;
+		}
+	}
+
+	/*
+	 * Allocate enough to hold the header (the same size as one scsi_lun)
+	 * plus the number of luns we are requesting.  511 was the default
+	 * value of the now removed max_report_luns parameter.
+	 */
+	length = (511 + 1) * sizeof(struct scsi_lun);
+retry:
+	lun_data = kmalloc(length, GFP_KERNEL |
+			   (sdev->host->unchecked_isa_dma ? __GFP_DMA : 0));
+	if (!lun_data) {
+		printk(ALLOC_FAILURE_MSG, __func__);
+		goto out;
+	}
+
+	scsi_cmd[0] = REPORT_LUNS;
+
+	/*
+	 * bytes 1 - 5: reserved, set to zero.
+	 */
+	memset(&scsi_cmd[1], 0, 5);
+
+	/*
+	 * bytes 6 - 9: length of the command.
+	 */
+	put_unaligned_be32(length, &scsi_cmd[6]);
+
+	scsi_cmd[10] = 0;	/* reserved */
+	scsi_cmd[11] = 0;	/* control */
+
+	/*
+	 * We can get a UNIT ATTENTION, for example a power on/reset, so
+	 * retry a few times (like sd.c does for TEST UNIT READY).
+	 * Experience shows some combinations of adapter/devices get at
+	 * least two power on/resets.
+	 *
+	 * Illegal requests (for devices that do not support REPORT LUNS)
+	 * should come through as a check condition, and will not generate
+	 * a retry.
+	 */
+	for (retries = 0; retries < 3; retries++) {
+		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
+				"scsi scan: Sending REPORT LUNS to (try %d)\n",
+				retries));
+
+		result = scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE,
+					  lun_data, length, &sshdr,
+					  SCSI_REPORT_LUNS_TIMEOUT, 3, NULL);
+
+		SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
+				"scsi scan: REPORT LUNS"
+				" %s (try %d) result 0x%x\n",
+				result ?  "failed" : "successful",
+				retries, result));
+		if (result == 0)
+			break;
+		else if (scsi_sense_valid(&sshdr)) {
+			if (sshdr.sense_key != UNIT_ATTENTION)
+				break;
+		}
+	}
+
+	if (result) {
+		/*
+		 * The device probably does not support a REPORT LUN command
+		 */
+		ret = 1;
+		goto out_err;
+	}
+
+	/*
+	 * Get the length from the first four bytes of lun_data.
+	 */
+	if (get_unaligned_be32(lun_data->scsi_lun) +
+	    sizeof(struct scsi_lun) > length) {
+		length = get_unaligned_be32(lun_data->scsi_lun) +
+			 sizeof(struct scsi_lun);
+		kfree(lun_data);
+		goto retry;
+	}
+	length = get_unaligned_be32(lun_data->scsi_lun);
+
+	num_luns = (length / sizeof(struct scsi_lun));
+
+	SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
+		"scsi scan: REPORT LUN scan\n"));
+
+	/*
+	 * Scan the luns in lun_data. The entry at offset 0 is really
+	 * the header, so start at 1 and go up to and including num_luns.
+	 */
+	for (lunp = &lun_data[1]; lunp <= &lun_data[num_luns]; lunp++) {
+		lun = scsilun_to_int(lunp);
+
+		if (lun > sdev->host->max_lun) {
+			sdev_printk(KERN_WARNING, sdev,
+				    "lun%llu has a LUN larger than"
+				    " allowed by the host adapter\n", lun);
+		} else {
+			int res;
+
+			res = scsi_probe_and_add_lun(starget,
+				lun, NULL, NULL, rescan, NULL);
+			if (res == SCSI_SCAN_NO_RESPONSE) {
+				/*
+				 * Got some results, but now none, abort.
+				 */
+				sdev_printk(KERN_ERR, sdev,
+					"Unexpected response"
+					" from lun %llu while scanning, scan"
+					" aborted\n", (unsigned long long)lun);
+				break;
+			}
+		}
+	}
+
+ out_err:
+	kfree(lun_data);
+ out:
+	if (scsi_device_created(sdev))
+		/*
+		 * the sdev we used didn't appear in the report luns scan
+		 */
+		__scsi_remove_device(sdev);
+	scsi_device_put(sdev);
+	return ret;
+}
+
+struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
+				      uint id, u64 lun, void *hostdata)
+{
+	struct scsi_device *sdev = ERR_PTR(-ENODEV);
+	struct device *parent = &shost->shost_gendev;
+	struct scsi_target *starget;
+
+	if (strncmp(scsi_scan_type, "none", 4) == 0)
+		return ERR_PTR(-ENODEV);
+
+	starget = scsi_alloc_target(parent, channel, id);
+	if (!starget)
+		return ERR_PTR(-ENOMEM);
+	scsi_autopm_get_target(starget);
+
+	mutex_lock(&shost->scan_mutex);
+	if (!shost->async_scan)
+		scsi_complete_async_scans();
+
+	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
+		scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
+		scsi_autopm_put_host(shost);
+	}
+	mutex_unlock(&shost->scan_mutex);
+	scsi_autopm_put_target(starget);
+	/*
+	 * paired with scsi_alloc_target().  Target will be destroyed unless
+	 * scsi_probe_and_add_lun made an underlying device visible
+	 */
+	scsi_target_reap(starget);
+	put_device(&starget->dev);
+
+	return sdev;
+}
+EXPORT_SYMBOL(__scsi_add_device);
+
+int scsi_add_device(struct Scsi_Host *host, uint channel,
+		    uint target, u64 lun)
+{
+	struct scsi_device *sdev = 
+		__scsi_add_device(host, channel, target, lun, NULL);
+	if (IS_ERR(sdev))
+		return PTR_ERR(sdev);
+
+	scsi_device_put(sdev);
+	return 0;
+}
+EXPORT_SYMBOL(scsi_add_device);
+
+void scsi_rescan_device(struct device *dev)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+
+	device_lock(dev);
+
+	scsi_attach_vpd(sdev);
+
+	if (sdev->handler && sdev->handler->rescan)
+		sdev->handler->rescan(sdev);
+
+	if (dev->driver && try_module_get(dev->driver->owner)) {
+		struct scsi_driver *drv = to_scsi_driver(dev->driver);
+
+		if (drv->rescan)
+			drv->rescan(dev);
+		module_put(dev->driver->owner);
+	}
+	device_unlock(dev);
+}
+EXPORT_SYMBOL(scsi_rescan_device);
+
+static void __scsi_scan_target(struct device *parent, unsigned int channel,
+		unsigned int id, u64 lun, enum scsi_scan_mode rescan)
+{
+	struct Scsi_Host *shost = dev_to_shost(parent);
+	blist_flags_t bflags = 0;
+	int res;
+	struct scsi_target *starget;
+
+	if (shost->this_id == id)
+		/*
+		 * Don't scan the host adapter
+		 */
+		return;
+
+	starget = scsi_alloc_target(parent, channel, id);
+	if (!starget)
+		return;
+	scsi_autopm_get_target(starget);
+
+	if (lun != SCAN_WILD_CARD) {
+		/*
+		 * Scan for a specific host/chan/id/lun.
+		 */
+		scsi_probe_and_add_lun(starget, lun, NULL, NULL, rescan, NULL);
+		goto out_reap;
+	}
+
+	/*
+	 * Scan LUN 0, if there is some response, scan further. Ideally, we
+	 * would not configure LUN 0 until all LUNs are scanned.
+	 */
+	res = scsi_probe_and_add_lun(starget, 0, &bflags, NULL, rescan, NULL);
+	if (res == SCSI_SCAN_LUN_PRESENT || res == SCSI_SCAN_TARGET_PRESENT) {
+		if (scsi_report_lun_scan(starget, bflags, rescan) != 0)
+			/*
+			 * The REPORT LUN did not scan the target,
+			 * do a sequential scan.
+			 */
+			scsi_sequential_lun_scan(starget, bflags,
+						 starget->scsi_level, rescan);
+	}
+
+ out_reap:
+	scsi_autopm_put_target(starget);
+	/*
+	 * paired with scsi_alloc_target(): determine if the target has
+	 * any children at all and if not, nuke it
+	 */
+	scsi_target_reap(starget);
+
+	put_device(&starget->dev);
+}
+
+/**
+ * scsi_scan_target - scan a target id, possibly including all LUNs on the target.
+ * @parent:	host to scan
+ * @channel:	channel to scan
+ * @id:		target id to scan
+ * @lun:	Specific LUN to scan or SCAN_WILD_CARD
+ * @rescan:	passed to LUN scanning routines; SCSI_SCAN_INITIAL for
+ *              no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
+ *              and SCSI_SCAN_MANUAL to force scanning even if
+ *              'scan=manual' is set.
+ *
+ * Description:
+ *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
+ *     and possibly all LUNs on the target id.
+ *
+ *     First try a REPORT LUN scan, if that does not scan the target, do a
+ *     sequential scan of LUNs on the target id.
+ **/
+void scsi_scan_target(struct device *parent, unsigned int channel,
+		      unsigned int id, u64 lun, enum scsi_scan_mode rescan)
+{
+	struct Scsi_Host *shost = dev_to_shost(parent);
+
+	if (strncmp(scsi_scan_type, "none", 4) == 0)
+		return;
+
+	if (rescan != SCSI_SCAN_MANUAL &&
+	    strncmp(scsi_scan_type, "manual", 6) == 0)
+		return;
+
+	mutex_lock(&shost->scan_mutex);
+	if (!shost->async_scan)
+		scsi_complete_async_scans();
+
+	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
+		__scsi_scan_target(parent, channel, id, lun, rescan);
+		scsi_autopm_put_host(shost);
+	}
+	mutex_unlock(&shost->scan_mutex);
+}
+EXPORT_SYMBOL(scsi_scan_target);
+
+static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
+			      unsigned int id, u64 lun,
+			      enum scsi_scan_mode rescan)
+{
+	uint order_id;
+
+	if (id == SCAN_WILD_CARD)
+		for (id = 0; id < shost->max_id; ++id) {
+			/*
+			 * XXX adapter drivers when possible (FCP, iSCSI)
+			 * could modify max_id to match the current max,
+			 * not the absolute max.
+			 *
+			 * XXX add a shost id iterator, so for example,
+			 * the FC ID can be the same as a target id
+			 * without a huge overhead of sparse id's.
+			 */
+			if (shost->reverse_ordering)
+				/*
+				 * Scan from high to low id.
+				 */
+				order_id = shost->max_id - id - 1;
+			else
+				order_id = id;
+			__scsi_scan_target(&shost->shost_gendev, channel,
+					order_id, lun, rescan);
+		}
+	else
+		__scsi_scan_target(&shost->shost_gendev, channel,
+				id, lun, rescan);
+}
+
+int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
+			    unsigned int id, u64 lun,
+			    enum scsi_scan_mode rescan)
+{
+	SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
+		"%s: <%u:%u:%llu>\n",
+		__func__, channel, id, lun));
+
+	if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) ||
+	    ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) ||
+	    ((lun != SCAN_WILD_CARD) && (lun >= shost->max_lun)))
+		return -EINVAL;
+
+	mutex_lock(&shost->scan_mutex);
+	if (!shost->async_scan)
+		scsi_complete_async_scans();
+
+	if (scsi_host_scan_allowed(shost) && scsi_autopm_get_host(shost) == 0) {
+		if (channel == SCAN_WILD_CARD)
+			for (channel = 0; channel <= shost->max_channel;
+			     channel++)
+				scsi_scan_channel(shost, channel, id, lun,
+						  rescan);
+		else
+			scsi_scan_channel(shost, channel, id, lun, rescan);
+		scsi_autopm_put_host(shost);
+	}
+	mutex_unlock(&shost->scan_mutex);
+
+	return 0;
+}
+
+static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
+{
+	struct scsi_device *sdev;
+	shost_for_each_device(sdev, shost) {
+		/* target removed before the device could be added */
+		if (sdev->sdev_state == SDEV_DEL)
+			continue;
+		/* If device is already visible, skip adding it to sysfs */
+		if (sdev->is_visible)
+			continue;
+		if (!scsi_host_scan_allowed(shost) ||
+		    scsi_sysfs_add_sdev(sdev) != 0)
+			__scsi_remove_device(sdev);
+	}
+}
+
+/**
+ * scsi_prep_async_scan - prepare for an async scan
+ * @shost: the host which will be scanned
+ * Returns: a cookie to be passed to scsi_finish_async_scan()
+ *
+ * Tells the midlayer this host is going to do an asynchronous scan.
+ * It reserves the host's position in the scanning list and ensures
+ * that other asynchronous scans started after this one won't affect the
+ * ordering of the discovered devices.
+ */
+static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
+{
+	struct async_scan_data *data = NULL;
+	unsigned long flags;
+
+	if (strncmp(scsi_scan_type, "sync", 4) == 0)
+		return NULL;
+
+	mutex_lock(&shost->scan_mutex);
+	if (shost->async_scan) {
+		shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__);
+		goto err;
+	}
+
+	data = kmalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		goto err;
+	data->shost = scsi_host_get(shost);
+	if (!data->shost)
+		goto err;
+	init_completion(&data->prev_finished);
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	shost->async_scan = 1;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	mutex_unlock(&shost->scan_mutex);
+
+	spin_lock(&async_scan_lock);
+	if (list_empty(&scanning_hosts))
+		complete(&data->prev_finished);
+	list_add_tail(&data->list, &scanning_hosts);
+	spin_unlock(&async_scan_lock);
+
+	return data;
+
+ err:
+	mutex_unlock(&shost->scan_mutex);
+	kfree(data);
+	return NULL;
+}
+
+/**
+ * scsi_finish_async_scan - asynchronous scan has finished
+ * @data: cookie returned from earlier call to scsi_prep_async_scan()
+ *
+ * All the devices currently attached to this host have been found.
+ * This function announces all the devices it has found to the rest
+ * of the system.
+ */
+static void scsi_finish_async_scan(struct async_scan_data *data)
+{
+	struct Scsi_Host *shost;
+	unsigned long flags;
+
+	if (!data)
+		return;
+
+	shost = data->shost;
+
+	mutex_lock(&shost->scan_mutex);
+
+	if (!shost->async_scan) {
+		shost_printk(KERN_INFO, shost, "%s called twice\n", __func__);
+		dump_stack();
+		mutex_unlock(&shost->scan_mutex);
+		return;
+	}
+
+	wait_for_completion(&data->prev_finished);
+
+	scsi_sysfs_add_devices(shost);
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	shost->async_scan = 0;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	mutex_unlock(&shost->scan_mutex);
+
+	spin_lock(&async_scan_lock);
+	list_del(&data->list);
+	if (!list_empty(&scanning_hosts)) {
+		struct async_scan_data *next = list_entry(scanning_hosts.next,
+				struct async_scan_data, list);
+		complete(&next->prev_finished);
+	}
+	spin_unlock(&async_scan_lock);
+
+	scsi_autopm_put_host(shost);
+	scsi_host_put(shost);
+	kfree(data);
+}
+
+static void do_scsi_scan_host(struct Scsi_Host *shost)
+{
+	if (shost->hostt->scan_finished) {
+		unsigned long start = jiffies;
+		if (shost->hostt->scan_start)
+			shost->hostt->scan_start(shost);
+
+		while (!shost->hostt->scan_finished(shost, jiffies - start))
+			msleep(10);
+	} else {
+		scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
+				SCAN_WILD_CARD, 0);
+	}
+}
+
+static void do_scan_async(void *_data, async_cookie_t c)
+{
+	struct async_scan_data *data = _data;
+	struct Scsi_Host *shost = data->shost;
+
+	do_scsi_scan_host(shost);
+	scsi_finish_async_scan(data);
+}
+
+/**
+ * scsi_scan_host - scan the given adapter
+ * @shost:	adapter to scan
+ **/
+void scsi_scan_host(struct Scsi_Host *shost)
+{
+	struct async_scan_data *data;
+
+	if (strncmp(scsi_scan_type, "none", 4) == 0 ||
+	    strncmp(scsi_scan_type, "manual", 6) == 0)
+		return;
+	if (scsi_autopm_get_host(shost) < 0)
+		return;
+
+	data = scsi_prep_async_scan(shost);
+	if (!data) {
+		do_scsi_scan_host(shost);
+		scsi_autopm_put_host(shost);
+		return;
+	}
+
+	/* register with the async subsystem so wait_for_device_probe()
+	 * will flush this work
+	 */
+	async_schedule(do_scan_async, data);
+
+	/* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */
+}
+EXPORT_SYMBOL(scsi_scan_host);
+
+void scsi_forget_host(struct Scsi_Host *shost)
+{
+	struct scsi_device *sdev;
+	unsigned long flags;
+
+ restart:
+	spin_lock_irqsave(shost->host_lock, flags);
+	list_for_each_entry(sdev, &shost->__devices, siblings) {
+		if (sdev->sdev_state == SDEV_DEL)
+			continue;
+		spin_unlock_irqrestore(shost->host_lock, flags);
+		__scsi_remove_device(sdev);
+		goto restart;
+	}
+	spin_unlock_irqrestore(shost->host_lock, flags);
+}
+
+/**
+ * scsi_get_host_dev - Create a scsi_device that points to the host adapter itself
+ * @shost: Host that needs a scsi_device
+ *
+ * Lock status: None assumed.
+ *
+ * Returns:     The scsi_device or NULL
+ *
+ * Notes:
+ *	Attach a single scsi_device to the Scsi_Host - this should
+ *	be made to look like a "pseudo-device" that points to the
+ *	HA itself.
+ *
+ *	Note - this device is not accessible from any high-level
+ *	drivers (including generics), which is probably not
+ *	optimal.  We can add hooks later to attach.
+ */
+struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
+{
+	struct scsi_device *sdev = NULL;
+	struct scsi_target *starget;
+
+	mutex_lock(&shost->scan_mutex);
+	if (!scsi_host_scan_allowed(shost))
+		goto out;
+	starget = scsi_alloc_target(&shost->shost_gendev, 0, shost->this_id);
+	if (!starget)
+		goto out;
+
+	sdev = scsi_alloc_sdev(starget, 0, NULL);
+	if (sdev)
+		sdev->borken = 0;
+	else
+		scsi_target_reap(starget);
+	put_device(&starget->dev);
+ out:
+	mutex_unlock(&shost->scan_mutex);
+	return sdev;
+}
+EXPORT_SYMBOL(scsi_get_host_dev);
+
+/**
+ * scsi_free_host_dev - Free a scsi_device that points to the host adapter itself
+ * @sdev: Host device to be freed
+ *
+ * Lock status: None assumed.
+ *
+ * Returns:     Nothing
+ */
+void scsi_free_host_dev(struct scsi_device *sdev)
+{
+	BUG_ON(sdev->id != sdev->host->this_id);
+
+	__scsi_remove_device(sdev);
+}
+EXPORT_SYMBOL(scsi_free_host_dev);
+