Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 1015 insertions, 0 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
new file mode 100644
index 0000000000..89367c4bf0
--- /dev/null
+++ b/drivers/scsi/scsi.c
@@ -0,0 +1,1015 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  scsi.c Copyright (C) 1992 Drew Eckhardt
+ *         Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
+ *         Copyright (C) 2002, 2003 Christoph Hellwig
+ *
+ *  generic mid-level SCSI driver
+ *      Initial versions: Drew Eckhardt
+ *      Subsequent revisions: Eric Youngdale
+ *
+ *  <drew@colorado.edu>
+ *
+ *  Bug correction thanks go to :
+ *      Rik Faith <faith@cs.unc.edu>
+ *      Tommy Thorn <tthorn>
+ *      Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
+ *
+ *  Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
+ *  add scatter-gather, multiple outstanding request, and other
+ *  enhancements.
+ *
+ *  Native multichannel, wide scsi, /proc/scsi and hot plugging
+ *  support added by Michael Neuffer <mike@i-connect.net>
+ *
+ *  Added request_module("scsi_hostadapter") for kerneld:
+ *  (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
+ *  Bjorn Ekwall  <bj0rn@blox.se>
+ *  (changed to kmod)
+ *
+ *  Major improvements to the timeout, abort, and reset processing,
+ *  as well as performance modifications for large queue depths by
+ *  Leonard N. Zubkoff <lnz@dandelion.com>
+ *
+ *  Converted cli() code to spinlocks, Ingo Molnar
+ *
+ *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
+ *
+ *  out_of_space hacks, D. Gilbert (dpg) 990608
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/unistd.h>
+#include <linux/spinlock.h>
+#include <linux/kmod.h>
+#include <linux/interrupt.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/mutex.h>
+#include <asm/unaligned.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.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_tcq.h>
+
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/scsi.h>
+
+/*
+ * Definitions and constants.
+ */
+
+/*
+ * Note - the initial logging level can be set here to log events at boot time.
+ * After the system is up, you may enable logging via the /proc interface.
+ */
+unsigned int scsi_logging_level;
+#if defined(CONFIG_SCSI_LOGGING)
+EXPORT_SYMBOL(scsi_logging_level);
+#endif
+
+#ifdef CONFIG_SCSI_LOGGING
+void scsi_log_send(struct scsi_cmnd *cmd)
+{
+	unsigned int level;
+
+	/*
+	 * If ML QUEUE log level is greater than or equal to:
+	 *
+	 * 1: nothing (match completion)
+	 *
+	 * 2: log opcode + command of all commands + cmd address
+	 *
+	 * 3: same as 2
+	 *
+	 * 4: same as 3
+	 */
+	if (unlikely(scsi_logging_level)) {
+		level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
+				       SCSI_LOG_MLQUEUE_BITS);
+		if (level > 1) {
+			scmd_printk(KERN_INFO, cmd,
+				    "Send: scmd 0x%p\n", cmd);
+			scsi_print_command(cmd);
+		}
+	}
+}
+
+void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
+{
+	unsigned int level;
+
+	/*
+	 * If ML COMPLETE log level is greater than or equal to:
+	 *
+	 * 1: log disposition, result, opcode + command, and conditionally
+	 * sense data for failures or non SUCCESS dispositions.
+	 *
+	 * 2: same as 1 but for all command completions.
+	 *
+	 * 3: same as 2
+	 *
+	 * 4: same as 3 plus dump extra junk
+	 */
+	if (unlikely(scsi_logging_level)) {
+		level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
+				       SCSI_LOG_MLCOMPLETE_BITS);
+		if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
+		    (level > 1)) {
+			scsi_print_result(cmd, "Done", disposition);
+			scsi_print_command(cmd);
+			if (scsi_status_is_check_condition(cmd->result))
+				scsi_print_sense(cmd);
+			if (level > 3)
+				scmd_printk(KERN_INFO, cmd,
+					    "scsi host busy %d failed %d\n",
+					    scsi_host_busy(cmd->device->host),
+					    cmd->device->host->host_failed);
+		}
+	}
+}
+#endif
+
+/**
+ * scsi_finish_command - cleanup and pass command back to upper layer
+ * @cmd: the command
+ *
+ * Description: Pass command off to upper layer for finishing of I/O
+ *              request, waking processes that are waiting on results,
+ *              etc.
+ */
+void scsi_finish_command(struct scsi_cmnd *cmd)
+{
+	struct scsi_device *sdev = cmd->device;
+	struct scsi_target *starget = scsi_target(sdev);
+	struct Scsi_Host *shost = sdev->host;
+	struct scsi_driver *drv;
+	unsigned int good_bytes;
+
+	scsi_device_unbusy(sdev, cmd);
+
+	/*
+	 * Clear the flags that say that the device/target/host is no longer
+	 * capable of accepting new commands.
+	 */
+	if (atomic_read(&shost->host_blocked))
+		atomic_set(&shost->host_blocked, 0);
+	if (atomic_read(&starget->target_blocked))
+		atomic_set(&starget->target_blocked, 0);
+	if (atomic_read(&sdev->device_blocked))
+		atomic_set(&sdev->device_blocked, 0);
+
+	SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
+				"Notifying upper driver of completion "
+				"(result %x)\n", cmd->result));
+
+	good_bytes = scsi_bufflen(cmd);
+	if (!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd))) {
+		int old_good_bytes = good_bytes;
+		drv = scsi_cmd_to_driver(cmd);
+		if (drv->done)
+			good_bytes = drv->done(cmd);
+		/*
+		 * USB may not give sense identifying bad sector and
+		 * simply return a residue instead, so subtract off the
+		 * residue if drv->done() error processing indicates no
+		 * change to the completion length.
+		 */
+		if (good_bytes == old_good_bytes)
+			good_bytes -= scsi_get_resid(cmd);
+	}
+	scsi_io_completion(cmd, good_bytes);
+}
+
+
+/*
+ * 4096 is big enough for saturating fast SCSI LUNs.
+ */
+int scsi_device_max_queue_depth(struct scsi_device *sdev)
+{
+	return min_t(int, sdev->host->can_queue, 4096);
+}
+
+/**
+ * scsi_change_queue_depth - change a device's queue depth
+ * @sdev: SCSI Device in question
+ * @depth: number of commands allowed to be queued to the driver
+ *
+ * Sets the device queue depth and returns the new value.
+ */
+int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
+{
+	depth = min_t(int, depth, scsi_device_max_queue_depth(sdev));
+
+	if (depth > 0) {
+		sdev->queue_depth = depth;
+		wmb();
+	}
+
+	if (sdev->request_queue)
+		blk_set_queue_depth(sdev->request_queue, depth);
+
+	sbitmap_resize(&sdev->budget_map, sdev->queue_depth);
+
+	return sdev->queue_depth;
+}
+EXPORT_SYMBOL(scsi_change_queue_depth);
+
+/**
+ * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
+ * @sdev: SCSI Device in question
+ * @depth: Current number of outstanding SCSI commands on this device,
+ *         not counting the one returned as QUEUE_FULL.
+ *
+ * Description:	This function will track successive QUEUE_FULL events on a
+ * 		specific SCSI device to determine if and when there is a
+ * 		need to adjust the queue depth on the device.
+ *
+ * Returns:	0 - No change needed, >0 - Adjust queue depth to this new depth,
+ * 		-1 - Drop back to untagged operation using host->cmd_per_lun
+ * 			as the untagged command depth
+ *
+ * Lock Status:	None held on entry
+ *
+ * Notes:	Low level drivers may call this at any time and we will do
+ * 		"The Right Thing."  We are interrupt context safe.
+ */
+int scsi_track_queue_full(struct scsi_device *sdev, int depth)
+{
+
+	/*
+	 * Don't let QUEUE_FULLs on the same
+	 * jiffies count, they could all be from
+	 * same event.
+	 */
+	if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
+		return 0;
+
+	sdev->last_queue_full_time = jiffies;
+	if (sdev->last_queue_full_depth != depth) {
+		sdev->last_queue_full_count = 1;
+		sdev->last_queue_full_depth = depth;
+	} else {
+		sdev->last_queue_full_count++;
+	}
+
+	if (sdev->last_queue_full_count <= 10)
+		return 0;
+
+	return scsi_change_queue_depth(sdev, depth);
+}
+EXPORT_SYMBOL(scsi_track_queue_full);
+
+/**
+ * scsi_vpd_inquiry - Request a device provide us with a VPD page
+ * @sdev: The device to ask
+ * @buffer: Where to put the result
+ * @page: Which Vital Product Data to return
+ * @len: The length of the buffer
+ *
+ * This is an internal helper function.  You probably want to use
+ * scsi_get_vpd_page instead.
+ *
+ * Returns size of the vpd page on success or a negative error number.
+ */
+static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
+							u8 page, unsigned len)
+{
+	int result;
+	unsigned char cmd[16];
+
+	if (len < 4)
+		return -EINVAL;
+
+	cmd[0] = INQUIRY;
+	cmd[1] = 1;		/* EVPD */
+	cmd[2] = page;
+	cmd[3] = len >> 8;
+	cmd[4] = len & 0xff;
+	cmd[5] = 0;		/* Control byte */
+
+	/*
+	 * I'm not convinced we need to try quite this hard to get VPD, but
+	 * all the existing users tried this hard.
+	 */
+	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer, len,
+				  30 * HZ, 3, NULL);
+	if (result)
+		return -EIO;
+
+	/*
+	 * Sanity check that we got the page back that we asked for and that
+	 * the page size is not 0.
+	 */
+	if (buffer[1] != page)
+		return -EIO;
+
+	result = get_unaligned_be16(&buffer[2]);
+	if (!result)
+		return -EIO;
+
+	return result + 4;
+}
+
+static int scsi_get_vpd_size(struct scsi_device *sdev, u8 page)
+{
+	unsigned char vpd_header[SCSI_VPD_HEADER_SIZE] __aligned(4);
+	int result;
+
+	if (sdev->no_vpd_size)
+		return SCSI_DEFAULT_VPD_LEN;
+
+	/*
+	 * Fetch the VPD page header to find out how big the page
+	 * is. This is done to prevent problems on legacy devices
+	 * which can not handle allocation lengths as large as
+	 * potentially requested by the caller.
+	 */
+	result = scsi_vpd_inquiry(sdev, vpd_header, page, sizeof(vpd_header));
+	if (result < 0)
+		return 0;
+
+	if (result < SCSI_VPD_HEADER_SIZE) {
+		dev_warn_once(&sdev->sdev_gendev,
+			      "%s: short VPD page 0x%02x length: %d bytes\n",
+			      __func__, page, result);
+		return 0;
+	}
+
+	return result;
+}
+
+/**
+ * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
+ * @sdev: The device to ask
+ * @page: Which Vital Product Data to return
+ * @buf: where to store the VPD
+ * @buf_len: number of bytes in the VPD buffer area
+ *
+ * SCSI devices may optionally supply Vital Product Data.  Each 'page'
+ * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
+ * If the device supports this VPD page, this routine fills @buf
+ * with the data from that page and return 0. If the VPD page is not
+ * supported or its content cannot be retrieved, -EINVAL is returned.
+ */
+int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
+		      int buf_len)
+{
+	int result, vpd_len;
+
+	if (!scsi_device_supports_vpd(sdev))
+		return -EINVAL;
+
+	vpd_len = scsi_get_vpd_size(sdev, page);
+	if (vpd_len <= 0)
+		return -EINVAL;
+
+	vpd_len = min(vpd_len, buf_len);
+
+	/*
+	 * Fetch the actual page. Since the appropriate size was reported
+	 * by the device it is now safe to ask for something bigger.
+	 */
+	memset(buf, 0, buf_len);
+	result = scsi_vpd_inquiry(sdev, buf, page, vpd_len);
+	if (result < 0)
+		return -EINVAL;
+	else if (result > vpd_len)
+		dev_warn_once(&sdev->sdev_gendev,
+			      "%s: VPD page 0x%02x result %d > %d bytes\n",
+			      __func__, page, result, vpd_len);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
+
+/**
+ * scsi_get_vpd_buf - Get Vital Product Data from a SCSI device
+ * @sdev: The device to ask
+ * @page: Which Vital Product Data to return
+ *
+ * Returns %NULL upon failure.
+ */
+static struct scsi_vpd *scsi_get_vpd_buf(struct scsi_device *sdev, u8 page)
+{
+	struct scsi_vpd *vpd_buf;
+	int vpd_len, result;
+
+	vpd_len = scsi_get_vpd_size(sdev, page);
+	if (vpd_len <= 0)
+		return NULL;
+
+retry_pg:
+	/*
+	 * Fetch the actual page. Since the appropriate size was reported
+	 * by the device it is now safe to ask for something bigger.
+	 */
+	vpd_buf = kmalloc(sizeof(*vpd_buf) + vpd_len, GFP_KERNEL);
+	if (!vpd_buf)
+		return NULL;
+
+	result = scsi_vpd_inquiry(sdev, vpd_buf->data, page, vpd_len);
+	if (result < 0) {
+		kfree(vpd_buf);
+		return NULL;
+	}
+	if (result > vpd_len) {
+		dev_warn_once(&sdev->sdev_gendev,
+			      "%s: VPD page 0x%02x result %d > %d bytes\n",
+			      __func__, page, result, vpd_len);
+		vpd_len = result;
+		kfree(vpd_buf);
+		goto retry_pg;
+	}
+
+	vpd_buf->len = result;
+
+	return vpd_buf;
+}
+
+static void scsi_update_vpd_page(struct scsi_device *sdev, u8 page,
+				 struct scsi_vpd __rcu **sdev_vpd_buf)
+{
+	struct scsi_vpd *vpd_buf;
+
+	vpd_buf = scsi_get_vpd_buf(sdev, page);
+	if (!vpd_buf)
+		return;
+
+	mutex_lock(&sdev->inquiry_mutex);
+	vpd_buf = rcu_replace_pointer(*sdev_vpd_buf, vpd_buf,
+				      lockdep_is_held(&sdev->inquiry_mutex));
+	mutex_unlock(&sdev->inquiry_mutex);
+
+	if (vpd_buf)
+		kfree_rcu(vpd_buf, rcu);
+}
+
+/**
+ * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
+ * @sdev: The device to ask
+ *
+ * Attach the 'Device Identification' VPD page (0x83) and the
+ * 'Unit Serial Number' VPD page (0x80) to a SCSI device
+ * structure. This information can be used to identify the device
+ * uniquely.
+ */
+void scsi_attach_vpd(struct scsi_device *sdev)
+{
+	int i;
+	struct scsi_vpd *vpd_buf;
+
+	if (!scsi_device_supports_vpd(sdev))
+		return;
+
+	/* Ask for all the pages supported by this device */
+	vpd_buf = scsi_get_vpd_buf(sdev, 0);
+	if (!vpd_buf)
+		return;
+
+	for (i = 4; i < vpd_buf->len; i++) {
+		if (vpd_buf->data[i] == 0x0)
+			scsi_update_vpd_page(sdev, 0x0, &sdev->vpd_pg0);
+		if (vpd_buf->data[i] == 0x80)
+			scsi_update_vpd_page(sdev, 0x80, &sdev->vpd_pg80);
+		if (vpd_buf->data[i] == 0x83)
+			scsi_update_vpd_page(sdev, 0x83, &sdev->vpd_pg83);
+		if (vpd_buf->data[i] == 0x89)
+			scsi_update_vpd_page(sdev, 0x89, &sdev->vpd_pg89);
+		if (vpd_buf->data[i] == 0xb0)
+			scsi_update_vpd_page(sdev, 0xb0, &sdev->vpd_pgb0);
+		if (vpd_buf->data[i] == 0xb1)
+			scsi_update_vpd_page(sdev, 0xb1, &sdev->vpd_pgb1);
+		if (vpd_buf->data[i] == 0xb2)
+			scsi_update_vpd_page(sdev, 0xb2, &sdev->vpd_pgb2);
+	}
+	kfree(vpd_buf);
+}
+
+/**
+ * scsi_report_opcode - Find out if a given command is supported
+ * @sdev:	scsi device to query
+ * @buffer:	scratch buffer (must be at least 20 bytes long)
+ * @len:	length of buffer
+ * @opcode:	opcode for the command to look up
+ * @sa:		service action for the command to look up
+ *
+ * Uses the REPORT SUPPORTED OPERATION CODES to check support for the
+ * command identified with @opcode and @sa. If the command does not
+ * have a service action, @sa must be 0. Returns -EINVAL if RSOC fails,
+ * 0 if the command is not supported and 1 if the device claims to
+ * support the command.
+ */
+int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
+		       unsigned int len, unsigned char opcode,
+		       unsigned short sa)
+{
+	unsigned char cmd[16];
+	struct scsi_sense_hdr sshdr;
+	int result, request_len;
+	const struct scsi_exec_args exec_args = {
+		.sshdr = &sshdr,
+	};
+
+	if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
+		return -EINVAL;
+
+	/* RSOC header + size of command we are asking about */
+	request_len = 4 + COMMAND_SIZE(opcode);
+	if (request_len > len) {
+		dev_warn_once(&sdev->sdev_gendev,
+			      "%s: len %u bytes, opcode 0x%02x needs %u\n",
+			      __func__, len, opcode, request_len);
+		return -EINVAL;
+	}
+
+	memset(cmd, 0, 16);
+	cmd[0] = MAINTENANCE_IN;
+	cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
+	if (!sa) {
+		cmd[2] = 1;	/* One command format */
+		cmd[3] = opcode;
+	} else {
+		cmd[2] = 3;	/* One command format with service action */
+		cmd[3] = opcode;
+		put_unaligned_be16(sa, &cmd[4]);
+	}
+	put_unaligned_be32(request_len, &cmd[6]);
+	memset(buffer, 0, len);
+
+	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer,
+				  request_len, 30 * HZ, 3, &exec_args);
+	if (result < 0)
+		return result;
+	if (result && scsi_sense_valid(&sshdr) &&
+	    sshdr.sense_key == ILLEGAL_REQUEST &&
+	    (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
+		return -EINVAL;
+
+	if ((buffer[1] & 3) == 3) /* Command supported */
+		return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(scsi_report_opcode);
+
+#define SCSI_CDL_CHECK_BUF_LEN	64
+
+static bool scsi_cdl_check_cmd(struct scsi_device *sdev, u8 opcode, u16 sa,
+			       unsigned char *buf)
+{
+	int ret;
+	u8 cdlp;
+
+	/* Check operation code */
+	ret = scsi_report_opcode(sdev, buf, SCSI_CDL_CHECK_BUF_LEN, opcode, sa);
+	if (ret <= 0)
+		return false;
+
+	if ((buf[1] & 0x03) != 0x03)
+		return false;
+
+	/*
+	 * See SPC-6, One_command parameter data format for
+	 * REPORT SUPPORTED OPERATION CODES. We have the following cases
+	 * depending on rwcdlp (buf[0] & 0x01) value:
+	 *  - rwcdlp == 0: then cdlp indicates support for the A mode page when
+	 *		   it is equal to 1 and for the B mode page when it is
+	 *		   equal to 2.
+	 *  - rwcdlp == 1: then cdlp indicates support for the T2A mode page
+	 *		   when it is equal to 1 and for the T2B mode page when
+	 *		   it is equal to 2.
+	 * Overall, to detect support for command duration limits, we only need
+	 * to check that cdlp is 1 or 2.
+	 */
+	cdlp = (buf[1] & 0x18) >> 3;
+
+	return cdlp == 0x01 || cdlp == 0x02;
+}
+
+/**
+ * scsi_cdl_check - Check if a SCSI device supports Command Duration Limits
+ * @sdev: The device to check
+ */
+void scsi_cdl_check(struct scsi_device *sdev)
+{
+	bool cdl_supported;
+	unsigned char *buf;
+
+	/*
+	 * Support for CDL was defined in SPC-5. Ignore devices reporting an
+	 * lower SPC version. This also avoids problems with old drives choking
+	 * on MAINTENANCE_IN / MI_REPORT_SUPPORTED_OPERATION_CODES with a
+	 * service action specified, as done in scsi_cdl_check_cmd().
+	 */
+	if (sdev->scsi_level < SCSI_SPC_5) {
+		sdev->cdl_supported = 0;
+		return;
+	}
+
+	buf = kmalloc(SCSI_CDL_CHECK_BUF_LEN, GFP_KERNEL);
+	if (!buf) {
+		sdev->cdl_supported = 0;
+		return;
+	}
+
+	/* Check support for READ_16, WRITE_16, READ_32 and WRITE_32 commands */
+	cdl_supported =
+		scsi_cdl_check_cmd(sdev, READ_16, 0, buf) ||
+		scsi_cdl_check_cmd(sdev, WRITE_16, 0, buf) ||
+		scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, READ_32, buf) ||
+		scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, WRITE_32, buf);
+	if (cdl_supported) {
+		/*
+		 * We have CDL support: force the use of READ16/WRITE16.
+		 * READ32 and WRITE32 will be used for devices that support
+		 * the T10_PI_TYPE2_PROTECTION protection type.
+		 */
+		sdev->use_16_for_rw = 1;
+		sdev->use_10_for_rw = 0;
+
+		sdev->cdl_supported = 1;
+	} else {
+		sdev->cdl_supported = 0;
+	}
+
+	kfree(buf);
+}
+
+/**
+ * scsi_cdl_enable - Enable or disable a SCSI device supports for Command
+ *                   Duration Limits
+ * @sdev: The target device
+ * @enable: the target state
+ */
+int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
+{
+	struct scsi_mode_data data;
+	struct scsi_sense_hdr sshdr;
+	struct scsi_vpd *vpd;
+	bool is_ata = false;
+	char buf[64];
+	int ret;
+
+	if (!sdev->cdl_supported)
+		return -EOPNOTSUPP;
+
+	rcu_read_lock();
+	vpd = rcu_dereference(sdev->vpd_pg89);
+	if (vpd)
+		is_ata = true;
+	rcu_read_unlock();
+
+	/*
+	 * For ATA devices, CDL needs to be enabled with a SET FEATURES command.
+	 */
+	if (is_ata) {
+		char *buf_data;
+		int len;
+
+		ret = scsi_mode_sense(sdev, 0x08, 0x0a, 0xf2, buf, sizeof(buf),
+				      5 * HZ, 3, &data, NULL);
+		if (ret)
+			return -EINVAL;
+
+		/* Enable CDL using the ATA feature page */
+		len = min_t(size_t, sizeof(buf),
+			    data.length - data.header_length -
+			    data.block_descriptor_length);
+		buf_data = buf + data.header_length +
+			data.block_descriptor_length;
+		if (enable)
+			buf_data[4] = 0x02;
+		else
+			buf_data[4] = 0;
+
+		ret = scsi_mode_select(sdev, 1, 0, buf_data, len, 5 * HZ, 3,
+				       &data, &sshdr);
+		if (ret) {
+			if (scsi_sense_valid(&sshdr))
+				scsi_print_sense_hdr(sdev,
+					dev_name(&sdev->sdev_gendev), &sshdr);
+			return ret;
+		}
+	}
+
+	sdev->cdl_enable = enable;
+
+	return 0;
+}
+
+/**
+ * scsi_device_get  -  get an additional reference to a scsi_device
+ * @sdev:	device to get a reference to
+ *
+ * Description: Gets a reference to the scsi_device and increments the use count
+ * of the underlying LLDD module.  You must hold host_lock of the
+ * parent Scsi_Host or already have a reference when calling this.
+ *
+ * This will fail if a device is deleted or cancelled, or when the LLD module
+ * is in the process of being unloaded.
+ */
+int scsi_device_get(struct scsi_device *sdev)
+{
+	if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
+		goto fail;
+	if (!try_module_get(sdev->host->hostt->module))
+		goto fail;
+	if (!get_device(&sdev->sdev_gendev))
+		goto fail_put_module;
+	return 0;
+
+fail_put_module:
+	module_put(sdev->host->hostt->module);
+fail:
+	return -ENXIO;
+}
+EXPORT_SYMBOL(scsi_device_get);
+
+/**
+ * scsi_device_put  -  release a reference to a scsi_device
+ * @sdev:	device to release a reference on.
+ *
+ * Description: Release a reference to the scsi_device and decrements the use
+ * count of the underlying LLDD module.  The device is freed once the last
+ * user vanishes.
+ */
+void scsi_device_put(struct scsi_device *sdev)
+{
+	struct module *mod = sdev->host->hostt->module;
+
+	put_device(&sdev->sdev_gendev);
+	module_put(mod);
+}
+EXPORT_SYMBOL(scsi_device_put);
+
+/* helper for shost_for_each_device, see that for documentation */
+struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
+					   struct scsi_device *prev)
+{
+	struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
+	struct scsi_device *next = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	while (list->next != &shost->__devices) {
+		next = list_entry(list->next, struct scsi_device, siblings);
+		/* skip devices that we can't get a reference to */
+		if (!scsi_device_get(next))
+			break;
+		next = NULL;
+		list = list->next;
+	}
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	if (prev)
+		scsi_device_put(prev);
+	return next;
+}
+EXPORT_SYMBOL(__scsi_iterate_devices);
+
+/**
+ * starget_for_each_device  -  helper to walk all devices of a target
+ * @starget:	target whose devices we want to iterate over.
+ * @data:	Opaque passed to each function call.
+ * @fn:		Function to call on each device
+ *
+ * This traverses over each device of @starget.  The devices have
+ * a reference that must be released by scsi_host_put when breaking
+ * out of the loop.
+ */
+void starget_for_each_device(struct scsi_target *starget, void *data,
+		     void (*fn)(struct scsi_device *, void *))
+{
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	struct scsi_device *sdev;
+
+	shost_for_each_device(sdev, shost) {
+		if ((sdev->channel == starget->channel) &&
+		    (sdev->id == starget->id))
+			fn(sdev, data);
+	}
+}
+EXPORT_SYMBOL(starget_for_each_device);
+
+/**
+ * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
+ * @starget:	target whose devices we want to iterate over.
+ * @data:	parameter for callback @fn()
+ * @fn:		callback function that is invoked for each device
+ *
+ * This traverses over each device of @starget.  It does _not_
+ * take a reference on the scsi_device, so the whole loop must be
+ * protected by shost->host_lock.
+ *
+ * Note:  The only reason why drivers would want to use this is because
+ * they need to access the device list in irq context.  Otherwise you
+ * really want to use starget_for_each_device instead.
+ **/
+void __starget_for_each_device(struct scsi_target *starget, void *data,
+			       void (*fn)(struct scsi_device *, void *))
+{
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	struct scsi_device *sdev;
+
+	__shost_for_each_device(sdev, shost) {
+		if ((sdev->channel == starget->channel) &&
+		    (sdev->id == starget->id))
+			fn(sdev, data);
+	}
+}
+EXPORT_SYMBOL(__starget_for_each_device);
+
+/**
+ * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
+ * @starget:	SCSI target pointer
+ * @lun:	SCSI Logical Unit Number
+ *
+ * Description: Looks up the scsi_device with the specified @lun for a given
+ * @starget.  The returned scsi_device does not have an additional
+ * reference.  You must hold the host's host_lock over this call and
+ * any access to the returned scsi_device. A scsi_device in state
+ * SDEV_DEL is skipped.
+ *
+ * Note:  The only reason why drivers should use this is because
+ * they need to access the device list in irq context.  Otherwise you
+ * really want to use scsi_device_lookup_by_target instead.
+ **/
+struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
+						   u64 lun)
+{
+	struct scsi_device *sdev;
+
+	list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
+		if (sdev->sdev_state == SDEV_DEL)
+			continue;
+		if (sdev->lun ==lun)
+			return sdev;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(__scsi_device_lookup_by_target);
+
+/**
+ * scsi_device_lookup_by_target - find a device given the target
+ * @starget:	SCSI target pointer
+ * @lun:	SCSI Logical Unit Number
+ *
+ * Description: Looks up the scsi_device with the specified @lun for a given
+ * @starget.  The returned scsi_device has an additional reference that
+ * needs to be released with scsi_device_put once you're done with it.
+ **/
+struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
+						 u64 lun)
+{
+	struct scsi_device *sdev;
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	sdev = __scsi_device_lookup_by_target(starget, lun);
+	if (sdev && scsi_device_get(sdev))
+		sdev = NULL;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	return sdev;
+}
+EXPORT_SYMBOL(scsi_device_lookup_by_target);
+
+/**
+ * __scsi_device_lookup - find a device given the host (UNLOCKED)
+ * @shost:	SCSI host pointer
+ * @channel:	SCSI channel (zero if only one channel)
+ * @id:		SCSI target number (physical unit number)
+ * @lun:	SCSI Logical Unit Number
+ *
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a given host. The returned scsi_device does not have an additional
+ * reference.  You must hold the host's host_lock over this call and any access
+ * to the returned scsi_device.
+ *
+ * Note:  The only reason why drivers would want to use this is because
+ * they need to access the device list in irq context.  Otherwise you
+ * really want to use scsi_device_lookup instead.
+ **/
+struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
+		uint channel, uint id, u64 lun)
+{
+	struct scsi_device *sdev;
+
+	list_for_each_entry(sdev, &shost->__devices, siblings) {
+		if (sdev->sdev_state == SDEV_DEL)
+			continue;
+		if (sdev->channel == channel && sdev->id == id &&
+				sdev->lun ==lun)
+			return sdev;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(__scsi_device_lookup);
+
+/**
+ * scsi_device_lookup - find a device given the host
+ * @shost:	SCSI host pointer
+ * @channel:	SCSI channel (zero if only one channel)
+ * @id:		SCSI target number (physical unit number)
+ * @lun:	SCSI Logical Unit Number
+ *
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a given host.  The returned scsi_device has an additional reference that
+ * needs to be released with scsi_device_put once you're done with it.
+ **/
+struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
+		uint channel, uint id, u64 lun)
+{
+	struct scsi_device *sdev;
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	sdev = __scsi_device_lookup(shost, channel, id, lun);
+	if (sdev && scsi_device_get(sdev))
+		sdev = NULL;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	return sdev;
+}
+EXPORT_SYMBOL(scsi_device_lookup);
+
+MODULE_DESCRIPTION("SCSI core");
+MODULE_LICENSE("GPL");
+
+module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
+
+static int __init init_scsi(void)
+{
+	int error;
+
+	error = scsi_init_procfs();
+	if (error)
+		goto cleanup_queue;
+	error = scsi_init_devinfo();
+	if (error)
+		goto cleanup_procfs;
+	error = scsi_init_hosts();
+	if (error)
+		goto cleanup_devlist;
+	error = scsi_init_sysctl();
+	if (error)
+		goto cleanup_hosts;
+	error = scsi_sysfs_register();
+	if (error)
+		goto cleanup_sysctl;
+
+	scsi_netlink_init();
+
+	printk(KERN_NOTICE "SCSI subsystem initialized\n");
+	return 0;
+
+cleanup_sysctl:
+	scsi_exit_sysctl();
+cleanup_hosts:
+	scsi_exit_hosts();
+cleanup_devlist:
+	scsi_exit_devinfo();
+cleanup_procfs:
+	scsi_exit_procfs();
+cleanup_queue:
+	scsi_exit_queue();
+	printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
+	       -error);
+	return error;
+}
+
+static void __exit exit_scsi(void)
+{
+	scsi_netlink_exit();
+	scsi_sysfs_unregister();
+	scsi_exit_sysctl();
+	scsi_exit_hosts();
+	scsi_exit_devinfo();
+	scsi_exit_procfs();
+	scsi_exit_queue();
+}
+
+subsys_initcall(init_scsi);
+module_exit(exit_scsi);