diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
new file mode 100644
index 0000000..265d1ee
--- /dev/null
+++ b/drivers/scsi/st.c
@@ -0,0 +1,4438 @@
+/*
+   SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
+   file Documentation/scsi/st.txt for more information.
+
+   History:
+   Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
+   Contribution and ideas from several people including (in alphabetical
+   order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
+   Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
+   Michael Schaefer, J"org Weule, and Eric Youngdale.
+
+   Copyright 1992 - 2005 Kai Makisara
+   email Kai.Makisara@kolumbus.fi
+
+   Some small formal changes - aeb, 950809
+
+   Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
+ */
+
+static char *verstr = "20050312";
+
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/mtio.h>
+#include <linux/ioctl.h>
+#include <linux/fcntl.h>
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/moduleparam.h>
+#include <linux/devfs_fs_kernel.h>
+#include <linux/cdev.h>
+#include <linux/delay.h>
+
+#include <asm/uaccess.h>
+#include <asm/dma.h>
+#include <asm/system.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsi_request.h>
+
+
+/* The driver prints some debugging information on the console if DEBUG
+   is defined and non-zero. */
+#define DEBUG 0
+
+#if DEBUG
+/* The message level for the debug messages is currently set to KERN_NOTICE
+   so that people can easily see the messages. Later when the debugging messages
+   in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
+#define ST_DEB_MSG  KERN_NOTICE
+#define DEB(a) a
+#define DEBC(a) if (debugging) { a ; }
+#else
+#define DEB(a)
+#define DEBC(a)
+#endif
+
+#define ST_KILOBYTE 1024
+
+#include "st_options.h"
+#include "st.h"
+
+static int buffer_kbs;
+static int max_sg_segs;
+static int try_direct_io = TRY_DIRECT_IO;
+static int try_rdio = 1;
+static int try_wdio = 1;
+
+static int st_dev_max;
+static int st_nr_dev;
+
+static struct class_simple *st_sysfs_class;
+
+MODULE_AUTHOR("Kai Makisara");
+MODULE_DESCRIPTION("SCSI Tape Driver");
+MODULE_LICENSE("GPL");
+
+/* Set 'perm' (4th argument) to 0 to disable module_param's definition
+ * of sysfs parameters (which module_param doesn't yet support).
+ * Sysfs parameters defined explicitly later.
+ */
+module_param_named(buffer_kbs, buffer_kbs, int, 0);
+MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
+module_param_named(max_sg_segs, max_sg_segs, int, 0);
+MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
+module_param_named(try_direct_io, try_direct_io, int, 0);
+MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
+
+/* Extra parameters for testing */
+module_param_named(try_rdio, try_rdio, int, 0);
+MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
+module_param_named(try_wdio, try_wdio, int, 0);
+MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
+
+#ifndef MODULE
+static int write_threshold_kbs;  /* retained for compatibility */
+static struct st_dev_parm {
+	char *name;
+	int *val;
+} parms[] __initdata = {
+	{
+		"buffer_kbs", &buffer_kbs
+	},
+	{       /* Retained for compatibility with 2.4 */
+		"write_threshold_kbs", &write_threshold_kbs
+	},
+	{
+		"max_sg_segs", NULL
+	},
+	{
+		"try_direct_io", &try_direct_io
+	}
+};
+#endif
+
+/* Restrict the number of modes so that names for all are assigned */
+#if ST_NBR_MODES > 16
+#error "Maximum number of modes is 16"
+#endif
+/* Bit reversed order to get same names for same minors with all
+   mode counts */
+static char *st_formats[] = {
+	"",  "r", "k", "s", "l", "t", "o", "u",
+	"m", "v", "p", "x", "a", "y", "q", "z"}; 
+
+/* The default definitions have been moved to st_options.h */
+
+#define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
+
+/* The buffer size should fit into the 24 bits for length in the
+   6-byte SCSI read and write commands. */
+#if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
+#error "Buffer size should not exceed (2 << 24 - 1) bytes!"
+#endif
+
+static int debugging = DEBUG;
+
+#define MAX_RETRIES 0
+#define MAX_WRITE_RETRIES 0
+#define MAX_READY_RETRIES 0
+#define NO_TAPE  NOT_READY
+
+#define ST_TIMEOUT (900 * HZ)
+#define ST_LONG_TIMEOUT (14000 * HZ)
+
+/* Remove mode bits and auto-rewind bit (7) */
+#define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
+    (iminor(x) & ~(-1 << ST_MODE_SHIFT)) )
+#define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
+
+/* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
+#define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
+  (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
+
+/* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
+   24 bits) */
+#define SET_DENS_AND_BLK 0x10001
+
+static DEFINE_RWLOCK(st_dev_arr_lock);
+
+static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
+static int st_max_sg_segs = ST_MAX_SG;
+
+static struct scsi_tape **scsi_tapes = NULL;
+
+static int modes_defined;
+
+static struct st_buffer *new_tape_buffer(int, int, int);
+static int enlarge_buffer(struct st_buffer *, int, int);
+static void normalize_buffer(struct st_buffer *);
+static int append_to_buffer(const char __user *, struct st_buffer *, int);
+static int from_buffer(struct st_buffer *, char __user *, int);
+static void move_buffer_data(struct st_buffer *, int);
+static void buf_to_sg(struct st_buffer *, unsigned int);
+
+static int st_map_user_pages(struct scatterlist *, const unsigned int, 
+			     unsigned long, size_t, int, unsigned long);
+static int sgl_map_user_pages(struct scatterlist *, const unsigned int, 
+			      unsigned long, size_t, int);
+static int sgl_unmap_user_pages(struct scatterlist *, const unsigned int, int);
+
+static int st_probe(struct device *);
+static int st_remove(struct device *);
+static int st_init_command(struct scsi_cmnd *);
+
+static void do_create_driverfs_files(void);
+static void do_remove_driverfs_files(void);
+static void do_create_class_files(struct scsi_tape *, int, int);
+
+static struct scsi_driver st_template = {
+	.owner			= THIS_MODULE,
+	.gendrv = {
+		.name		= "st",
+		.probe		= st_probe,
+		.remove		= st_remove,
+	},
+	.init_command		= st_init_command,
+};
+
+static int st_compression(struct scsi_tape *, int);
+
+static int find_partition(struct scsi_tape *);
+static int switch_partition(struct scsi_tape *);
+
+static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
+
+
+#include "osst_detect.h"
+#ifndef SIGS_FROM_OSST
+#define SIGS_FROM_OSST \
+	{"OnStream", "SC-", "", "osst"}, \
+	{"OnStream", "DI-", "", "osst"}, \
+	{"OnStream", "DP-", "", "osst"}, \
+	{"OnStream", "USB", "", "osst"}, \
+	{"OnStream", "FW-", "", "osst"}
+#endif
+
+struct st_reject_data {
+	char *vendor;
+	char *model;
+	char *rev;
+	char *driver_hint; /* Name of the correct driver, NULL if unknown */
+};
+
+static struct st_reject_data reject_list[] = {
+	/* {"XXX", "Yy-", "", NULL},  example */
+	SIGS_FROM_OSST,
+	{NULL, }};
+
+/* If the device signature is on the list of incompatible drives, the
+   function returns a pointer to the name of the correct driver (if known) */
+static char * st_incompatible(struct scsi_device* SDp)
+{
+	struct st_reject_data *rp;
+
+	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
+		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
+		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
+		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
+			if (rp->driver_hint)
+				return rp->driver_hint;
+			else
+				return "unknown";
+		}
+	return NULL;
+}
+
+
+static inline char *tape_name(struct scsi_tape *tape)
+{
+	return tape->disk->disk_name;
+}
+
+
+static void st_analyze_sense(struct scsi_request *SRpnt, struct st_cmdstatus *s)
+{
+	const u8 *ucp;
+	const u8 *sense = SRpnt->sr_sense_buffer;
+
+	s->have_sense = scsi_request_normalize_sense(SRpnt, &s->sense_hdr);
+	s->flags = 0;
+
+	if (s->have_sense) {
+		s->deferred = 0;
+		s->remainder_valid =
+			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
+		switch (sense[0] & 0x7f) {
+		case 0x71:
+			s->deferred = 1;
+		case 0x70:
+			s->fixed_format = 1;
+			s->flags = sense[2] & 0xe0;
+			break;
+		case 0x73:
+			s->deferred = 1;
+		case 0x72:
+			s->fixed_format = 0;
+			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
+			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
+			break;
+		}
+	}
+}
+
+
+/* Convert the result to success code */
+static int st_chk_result(struct scsi_tape *STp, struct scsi_request * SRpnt)
+{
+	int result = SRpnt->sr_result;
+	u8 scode;
+	DEB(const char *stp;)
+	char *name = tape_name(STp);
+	struct st_cmdstatus *cmdstatp;
+
+	if (!result)
+		return 0;
+
+	cmdstatp = &STp->buffer->cmdstat;
+	st_analyze_sense(STp->buffer->last_SRpnt, cmdstatp);
+
+	if (cmdstatp->have_sense)
+		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
+	else
+		scode = 0;
+
+        DEB(
+        if (debugging) {
+                printk(ST_DEB_MSG "%s: Error: %x, cmd: %x %x %x %x %x %x Len: %d\n",
+		       name, result,
+		       SRpnt->sr_cmnd[0], SRpnt->sr_cmnd[1], SRpnt->sr_cmnd[2],
+		       SRpnt->sr_cmnd[3], SRpnt->sr_cmnd[4], SRpnt->sr_cmnd[5],
+		       SRpnt->sr_bufflen);
+		if (cmdstatp->have_sense)
+			scsi_print_req_sense("st", SRpnt);
+	} ) /* end DEB */
+	if (!debugging) { /* Abnormal conditions for tape */
+		if (!cmdstatp->have_sense)
+			printk(KERN_WARNING
+			       "%s: Error %x (sugg. bt 0x%x, driver bt 0x%x, host bt 0x%x).\n",
+			       name, result, suggestion(result),
+			       driver_byte(result) & DRIVER_MASK, host_byte(result));
+		else if (cmdstatp->have_sense &&
+			 scode != NO_SENSE &&
+			 scode != RECOVERED_ERROR &&
+			 /* scode != UNIT_ATTENTION && */
+			 scode != BLANK_CHECK &&
+			 scode != VOLUME_OVERFLOW &&
+			 SRpnt->sr_cmnd[0] != MODE_SENSE &&
+			 SRpnt->sr_cmnd[0] != TEST_UNIT_READY) {
+				printk(KERN_WARNING "%s: Error with sense data: ", name);
+				scsi_print_req_sense("st", SRpnt);
+		}
+	}
+
+	if (cmdstatp->fixed_format &&
+	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
+		if (STp->cln_sense_value)
+			STp->cleaning_req |= ((SRpnt->sr_sense_buffer[STp->cln_mode] &
+					       STp->cln_sense_mask) == STp->cln_sense_value);
+		else
+			STp->cleaning_req |= ((SRpnt->sr_sense_buffer[STp->cln_mode] &
+					       STp->cln_sense_mask) != 0);
+	}
+	if (cmdstatp->have_sense &&
+	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
+		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
+
+	STp->pos_unknown |= STp->device->was_reset;
+
+	if (cmdstatp->have_sense &&
+	    scode == RECOVERED_ERROR
+#if ST_RECOVERED_WRITE_FATAL
+	    && SRpnt->sr_cmnd[0] != WRITE_6
+	    && SRpnt->sr_cmnd[0] != WRITE_FILEMARKS
+#endif
+	    ) {
+		STp->recover_count++;
+		STp->recover_reg++;
+
+                DEB(
+		if (debugging) {
+			if (SRpnt->sr_cmnd[0] == READ_6)
+				stp = "read";
+			else if (SRpnt->sr_cmnd[0] == WRITE_6)
+				stp = "write";
+			else
+				stp = "ioctl";
+			printk(ST_DEB_MSG "%s: Recovered %s error (%d).\n", name, stp,
+			       STp->recover_count);
+		} ) /* end DEB */
+
+		if (cmdstatp->flags == 0)
+			return 0;
+	}
+	return (-EIO);
+}
+
+
+/* Wakeup from interrupt */
+static void st_sleep_done(struct scsi_cmnd * SCpnt)
+{
+	struct scsi_tape *STp = container_of(SCpnt->request->rq_disk->private_data,
+					     struct scsi_tape, driver);
+
+	(STp->buffer)->cmdstat.midlevel_result = SCpnt->result;
+	SCpnt->request->rq_status = RQ_SCSI_DONE;
+	(STp->buffer)->last_SRpnt = SCpnt->sc_request;
+	DEB( STp->write_pending = 0; )
+
+	complete(SCpnt->request->waiting);
+}
+
+/* Do the scsi command. Waits until command performed if do_wait is true.
+   Otherwise write_behind_check() is used to check that the command
+   has finished. */
+static struct scsi_request *
+st_do_scsi(struct scsi_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
+	   int bytes, int direction, int timeout, int retries, int do_wait)
+{
+	unsigned char *bp;
+
+	if (SRpnt == NULL) {
+		SRpnt = scsi_allocate_request(STp->device, GFP_ATOMIC);
+		if (SRpnt == NULL) {
+			DEBC( printk(KERN_ERR "%s: Can't get SCSI request.\n",
+				     tape_name(STp)); );
+			if (signal_pending(current))
+				(STp->buffer)->syscall_result = (-EINTR);
+			else
+				(STp->buffer)->syscall_result = (-EBUSY);
+			return NULL;
+		}
+	}
+
+	init_completion(&STp->wait);
+	SRpnt->sr_use_sg = STp->buffer->do_dio || (bytes > (STp->buffer)->frp[0].length);
+	if (SRpnt->sr_use_sg) {
+		if (!STp->buffer->do_dio)
+			buf_to_sg(STp->buffer, bytes);
+		SRpnt->sr_use_sg = (STp->buffer)->sg_segs;
+		bp = (char *) &((STp->buffer)->sg[0]);
+	} else
+		bp = (STp->buffer)->b_data;
+	SRpnt->sr_data_direction = direction;
+	SRpnt->sr_cmd_len = 0;
+	SRpnt->sr_request->waiting = &(STp->wait);
+	SRpnt->sr_request->rq_status = RQ_SCSI_BUSY;
+	SRpnt->sr_request->rq_disk = STp->disk;
+	STp->buffer->cmdstat.have_sense = 0;
+
+	scsi_do_req(SRpnt, (void *) cmd, bp, bytes,
+		    st_sleep_done, timeout, retries);
+
+	if (do_wait) {
+		wait_for_completion(SRpnt->sr_request->waiting);
+		SRpnt->sr_request->waiting = NULL;
+		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
+	}
+	return SRpnt;
+}
+
+
+/* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
+   write has been correct but EOM early warning reached, -EIO if write ended in
+   error or zero if write successful. Asynchronous writes are used only in
+   variable block mode. */
+static int write_behind_check(struct scsi_tape * STp)
+{
+	int retval = 0;
+	struct st_buffer *STbuffer;
+	struct st_partstat *STps;
+	struct st_cmdstatus *cmdstatp;
+
+	STbuffer = STp->buffer;
+	if (!STbuffer->writing)
+		return 0;
+
+        DEB(
+	if (STp->write_pending)
+		STp->nbr_waits++;
+	else
+		STp->nbr_finished++;
+        ) /* end DEB */
+
+	wait_for_completion(&(STp->wait));
+	(STp->buffer)->last_SRpnt->sr_request->waiting = NULL;
+
+	(STp->buffer)->syscall_result = st_chk_result(STp, (STp->buffer)->last_SRpnt);
+	scsi_release_request((STp->buffer)->last_SRpnt);
+
+	STbuffer->buffer_bytes -= STbuffer->writing;
+	STps = &(STp->ps[STp->partition]);
+	if (STps->drv_block >= 0) {
+		if (STp->block_size == 0)
+			STps->drv_block++;
+		else
+			STps->drv_block += STbuffer->writing / STp->block_size;
+	}
+
+	cmdstatp = &STbuffer->cmdstat;
+	if (STbuffer->syscall_result) {
+		retval = -EIO;
+		if (cmdstatp->have_sense && !cmdstatp->deferred &&
+		    (cmdstatp->flags & SENSE_EOM) &&
+		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
+		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
+			/* EOM at write-behind, has all data been written? */
+			if (!cmdstatp->remainder_valid ||
+			    cmdstatp->uremainder64 == 0)
+				retval = -ENOSPC;
+		}
+		if (retval == -EIO)
+			STps->drv_block = -1;
+	}
+	STbuffer->writing = 0;
+
+	DEB(if (debugging && retval)
+	    printk(ST_DEB_MSG "%s: Async write error %x, return value %d.\n",
+		   tape_name(STp), STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
+
+	return retval;
+}
+
+
+/* Step over EOF if it has been inadvertently crossed (ioctl not used because
+   it messes up the block number). */
+static int cross_eof(struct scsi_tape * STp, int forward)
+{
+	struct scsi_request *SRpnt;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+
+	cmd[0] = SPACE;
+	cmd[1] = 0x01;		/* Space FileMarks */
+	if (forward) {
+		cmd[2] = cmd[3] = 0;
+		cmd[4] = 1;
+	} else
+		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
+	cmd[5] = 0;
+
+        DEBC(printk(ST_DEB_MSG "%s: Stepping over filemark %s.\n",
+		   tape_name(STp), forward ? "forward" : "backward"));
+
+	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
+			   STp->device->timeout, MAX_RETRIES, 1);
+	if (!SRpnt)
+		return (STp->buffer)->syscall_result;
+
+	scsi_release_request(SRpnt);
+	SRpnt = NULL;
+
+	if ((STp->buffer)->cmdstat.midlevel_result != 0)
+		printk(KERN_ERR "%s: Stepping over filemark %s failed.\n",
+		   tape_name(STp), forward ? "forward" : "backward");
+
+	return (STp->buffer)->syscall_result;
+}
+
+
+/* Flush the write buffer (never need to write if variable blocksize). */
+static int flush_write_buffer(struct scsi_tape * STp)
+{
+	int offset, transfer, blks;
+	int result;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt;
+	struct st_partstat *STps;
+
+	result = write_behind_check(STp);
+	if (result)
+		return result;
+
+	result = 0;
+	if (STp->dirty == 1) {
+
+		offset = (STp->buffer)->buffer_bytes;
+		transfer = ((offset + STp->block_size - 1) /
+			    STp->block_size) * STp->block_size;
+                DEBC(printk(ST_DEB_MSG "%s: Flushing %d bytes.\n",
+                               tape_name(STp), transfer));
+
+		memset((STp->buffer)->b_data + offset, 0, transfer - offset);
+
+		memset(cmd, 0, MAX_COMMAND_SIZE);
+		cmd[0] = WRITE_6;
+		cmd[1] = 1;
+		blks = transfer / STp->block_size;
+		cmd[2] = blks >> 16;
+		cmd[3] = blks >> 8;
+		cmd[4] = blks;
+
+		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
+				   STp->device->timeout, MAX_WRITE_RETRIES, 1);
+		if (!SRpnt)
+			return (STp->buffer)->syscall_result;
+
+		STps = &(STp->ps[STp->partition]);
+		if ((STp->buffer)->syscall_result != 0) {
+			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
+
+			if (cmdstatp->have_sense && !cmdstatp->deferred &&
+			    (cmdstatp->flags & SENSE_EOM) &&
+			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
+			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
+			    (!cmdstatp->remainder_valid ||
+			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
+				STp->dirty = 0;
+				(STp->buffer)->buffer_bytes = 0;
+				if (STps->drv_block >= 0)
+					STps->drv_block += blks;
+				result = (-ENOSPC);
+			} else {
+				printk(KERN_ERR "%s: Error on flush.\n",
+                                       tape_name(STp));
+				STps->drv_block = (-1);
+				result = (-EIO);
+			}
+		} else {
+			if (STps->drv_block >= 0)
+				STps->drv_block += blks;
+			STp->dirty = 0;
+			(STp->buffer)->buffer_bytes = 0;
+		}
+		scsi_release_request(SRpnt);
+		SRpnt = NULL;
+	}
+	return result;
+}
+
+
+/* Flush the tape buffer. The tape will be positioned correctly unless
+   seek_next is true. */
+static int flush_buffer(struct scsi_tape *STp, int seek_next)
+{
+	int backspace, result;
+	struct st_buffer *STbuffer;
+	struct st_partstat *STps;
+
+	STbuffer = STp->buffer;
+
+	/*
+	 * If there was a bus reset, block further access
+	 * to this device.
+	 */
+	if (STp->pos_unknown)
+		return (-EIO);
+
+	if (STp->ready != ST_READY)
+		return 0;
+	STps = &(STp->ps[STp->partition]);
+	if (STps->rw == ST_WRITING)	/* Writing */
+		return flush_write_buffer(STp);
+
+	if (STp->block_size == 0)
+		return 0;
+
+	backspace = ((STp->buffer)->buffer_bytes +
+		     (STp->buffer)->read_pointer) / STp->block_size -
+	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
+	    STp->block_size;
+	(STp->buffer)->buffer_bytes = 0;
+	(STp->buffer)->read_pointer = 0;
+	result = 0;
+	if (!seek_next) {
+		if (STps->eof == ST_FM_HIT) {
+			result = cross_eof(STp, 0);	/* Back over the EOF hit */
+			if (!result)
+				STps->eof = ST_NOEOF;
+			else {
+				if (STps->drv_file >= 0)
+					STps->drv_file++;
+				STps->drv_block = 0;
+			}
+		}
+		if (!result && backspace > 0)
+			result = st_int_ioctl(STp, MTBSR, backspace);
+	} else if (STps->eof == ST_FM_HIT) {
+		if (STps->drv_file >= 0)
+			STps->drv_file++;
+		STps->drv_block = 0;
+		STps->eof = ST_NOEOF;
+	}
+	return result;
+
+}
+
+/* Set the mode parameters */
+static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
+{
+	int set_it = 0;
+	unsigned long arg;
+	char *name = tape_name(STp);
+
+	if (!STp->density_changed &&
+	    STm->default_density >= 0 &&
+	    STm->default_density != STp->density) {
+		arg = STm->default_density;
+		set_it = 1;
+	} else
+		arg = STp->density;
+	arg <<= MT_ST_DENSITY_SHIFT;
+	if (!STp->blksize_changed &&
+	    STm->default_blksize >= 0 &&
+	    STm->default_blksize != STp->block_size) {
+		arg |= STm->default_blksize;
+		set_it = 1;
+	} else
+		arg |= STp->block_size;
+	if (set_it &&
+	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
+		printk(KERN_WARNING
+		       "%s: Can't set default block size to %d bytes and density %x.\n",
+		       name, STm->default_blksize, STm->default_density);
+		if (modes_defined)
+			return (-EINVAL);
+	}
+	return 0;
+}
+
+
+/* Lock or unlock the drive door. Don't use when scsi_request allocated. */
+static int do_door_lock(struct scsi_tape * STp, int do_lock)
+{
+	int retval, cmd;
+	DEB(char *name = tape_name(STp);)
+
+
+	cmd = do_lock ? SCSI_IOCTL_DOORLOCK : SCSI_IOCTL_DOORUNLOCK;
+	DEBC(printk(ST_DEB_MSG "%s: %socking drive door.\n", name,
+		    do_lock ? "L" : "Unl"));
+	retval = scsi_ioctl(STp->device, cmd, NULL);
+	if (!retval) {
+		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
+	}
+	else {
+		STp->door_locked = ST_LOCK_FAILS;
+	}
+	return retval;
+}
+
+
+/* Set the internal state after reset */
+static void reset_state(struct scsi_tape *STp)
+{
+	int i;
+	struct st_partstat *STps;
+
+	STp->pos_unknown = 0;
+	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
+		STps = &(STp->ps[i]);
+		STps->rw = ST_IDLE;
+		STps->eof = ST_NOEOF;
+		STps->at_sm = 0;
+		STps->last_block_valid = 0;
+		STps->drv_block = -1;
+		STps->drv_file = -1;
+	}
+	if (STp->can_partitions) {
+		STp->partition = find_partition(STp);
+		if (STp->partition < 0)
+			STp->partition = 0;
+		STp->new_partition = STp->partition;
+	}
+}
+
+/* Test if the drive is ready. Returns either one of the codes below or a negative system
+   error code. */
+#define CHKRES_READY       0
+#define CHKRES_NEW_SESSION 1
+#define CHKRES_NOT_READY   2
+#define CHKRES_NO_TAPE     3
+
+#define MAX_ATTENTIONS    10
+
+static int test_ready(struct scsi_tape *STp, int do_wait)
+{
+	int attentions, waits, max_wait, scode;
+	int retval = CHKRES_READY, new_session = 0;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt = NULL;
+	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
+
+	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
+
+	for (attentions=waits=0; ; ) {
+		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
+		cmd[0] = TEST_UNIT_READY;
+		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
+				   STp->long_timeout, MAX_READY_RETRIES, 1);
+
+		if (!SRpnt) {
+			retval = (STp->buffer)->syscall_result;
+			break;
+		}
+
+		if (cmdstatp->have_sense) {
+
+			scode = cmdstatp->sense_hdr.sense_key;
+
+			if (scode == UNIT_ATTENTION) { /* New media? */
+				new_session = 1;
+				if (attentions < MAX_ATTENTIONS) {
+					attentions++;
+					continue;
+				}
+				else {
+					retval = (-EIO);
+					break;
+				}
+			}
+
+			if (scode == NOT_READY) {
+				if (waits < max_wait) {
+					if (msleep_interruptible(1000)) {
+						retval = (-EINTR);
+						break;
+					}
+					waits++;
+					continue;
+				}
+				else {
+					if ((STp->device)->scsi_level >= SCSI_2 &&
+					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
+						retval = CHKRES_NO_TAPE;
+					else
+						retval = CHKRES_NOT_READY;
+					break;
+				}
+			}
+		}
+
+		retval = (STp->buffer)->syscall_result;
+		if (!retval)
+			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
+		break;
+	}
+
+	if (SRpnt != NULL)
+		scsi_release_request(SRpnt);
+	return retval;
+}
+
+
+/* See if the drive is ready and gather information about the tape. Return values:
+   < 0   negative error code from errno.h
+   0     drive ready
+   1     drive not ready (possibly no tape)
+*/
+static int check_tape(struct scsi_tape *STp, struct file *filp)
+{
+	int i, retval, new_session = 0, do_wait;
+	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
+	unsigned short st_flags = filp->f_flags;
+	struct scsi_request *SRpnt = NULL;
+	struct st_modedef *STm;
+	struct st_partstat *STps;
+	char *name = tape_name(STp);
+	struct inode *inode = filp->f_dentry->d_inode;
+	int mode = TAPE_MODE(inode);
+
+	STp->ready = ST_READY;
+
+	if (mode != STp->current_mode) {
+                DEBC(printk(ST_DEB_MSG "%s: Mode change from %d to %d.\n",
+			       name, STp->current_mode, mode));
+		new_session = 1;
+		STp->current_mode = mode;
+	}
+	STm = &(STp->modes[STp->current_mode]);
+
+	saved_cleaning = STp->cleaning_req;
+	STp->cleaning_req = 0;
+
+	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
+	retval = test_ready(STp, do_wait);
+
+	if (retval < 0)
+	    goto err_out;
+
+	if (retval == CHKRES_NEW_SESSION) {
+		STp->pos_unknown = 0;
+		STp->partition = STp->new_partition = 0;
+		if (STp->can_partitions)
+			STp->nbr_partitions = 1; /* This guess will be updated later
+                                                    if necessary */
+		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
+			STps = &(STp->ps[i]);
+			STps->rw = ST_IDLE;
+			STps->eof = ST_NOEOF;
+			STps->at_sm = 0;
+			STps->last_block_valid = 0;
+			STps->drv_block = 0;
+			STps->drv_file = 0;
+		}
+		new_session = 1;
+	}
+	else {
+		STp->cleaning_req |= saved_cleaning;
+
+		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
+			if (retval == CHKRES_NO_TAPE)
+				STp->ready = ST_NO_TAPE;
+			else
+				STp->ready = ST_NOT_READY;
+
+			STp->density = 0;	/* Clear the erroneous "residue" */
+			STp->write_prot = 0;
+			STp->block_size = 0;
+			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
+			STp->partition = STp->new_partition = 0;
+			STp->door_locked = ST_UNLOCKED;
+			return CHKRES_NOT_READY;
+		}
+	}
+
+	if (STp->omit_blklims)
+		STp->min_block = STp->max_block = (-1);
+	else {
+		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
+		cmd[0] = READ_BLOCK_LIMITS;
+
+		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
+				   STp->device->timeout, MAX_READY_RETRIES, 1);
+		if (!SRpnt) {
+			retval = (STp->buffer)->syscall_result;
+			goto err_out;
+		}
+
+		if (!SRpnt->sr_result && !STp->buffer->cmdstat.have_sense) {
+			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
+			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
+			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
+			    (STp->buffer)->b_data[5];
+			if ( DEB( debugging || ) !STp->inited)
+				printk(KERN_WARNING
+                                       "%s: Block limits %d - %d bytes.\n", name,
+                                       STp->min_block, STp->max_block);
+		} else {
+			STp->min_block = STp->max_block = (-1);
+                        DEBC(printk(ST_DEB_MSG "%s: Can't read block limits.\n",
+                                       name));
+		}
+	}
+
+	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
+	cmd[0] = MODE_SENSE;
+	cmd[4] = 12;
+
+	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
+			STp->device->timeout, MAX_READY_RETRIES, 1);
+	if (!SRpnt) {
+		retval = (STp->buffer)->syscall_result;
+		goto err_out;
+	}
+
+	if ((STp->buffer)->syscall_result != 0) {
+                DEBC(printk(ST_DEB_MSG "%s: No Mode Sense.\n", name));
+		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
+		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
+		STp->drv_write_prot = 0;
+	} else {
+                DEBC(printk(ST_DEB_MSG
+                            "%s: Mode sense. Length %d, medium %x, WBS %x, BLL %d\n",
+                            name,
+                            (STp->buffer)->b_data[0], (STp->buffer)->b_data[1],
+                            (STp->buffer)->b_data[2], (STp->buffer)->b_data[3]));
+
+		if ((STp->buffer)->b_data[3] >= 8) {
+			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
+			STp->density = (STp->buffer)->b_data[4];
+			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
+			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
+                        DEBC(printk(ST_DEB_MSG
+                                    "%s: Density %x, tape length: %x, drv buffer: %d\n",
+                                    name, STp->density, (STp->buffer)->b_data[5] * 65536 +
+                                    (STp->buffer)->b_data[6] * 256 + (STp->buffer)->b_data[7],
+                                    STp->drv_buffer));
+		}
+		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
+	}
+	scsi_release_request(SRpnt);
+	SRpnt = NULL;
+        STp->inited = 1;
+
+	if (STp->block_size > 0)
+		(STp->buffer)->buffer_blocks =
+                        (STp->buffer)->buffer_size / STp->block_size;
+	else
+		(STp->buffer)->buffer_blocks = 1;
+	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
+
+        DEBC(printk(ST_DEB_MSG
+                       "%s: Block size: %d, buffer size: %d (%d blocks).\n", name,
+		       STp->block_size, (STp->buffer)->buffer_size,
+		       (STp->buffer)->buffer_blocks));
+
+	if (STp->drv_write_prot) {
+		STp->write_prot = 1;
+
+                DEBC(printk(ST_DEB_MSG "%s: Write protected\n", name));
+
+		if (do_wait &&
+		    ((st_flags & O_ACCMODE) == O_WRONLY ||
+		     (st_flags & O_ACCMODE) == O_RDWR)) {
+			retval = (-EROFS);
+			goto err_out;
+		}
+	}
+
+	if (STp->can_partitions && STp->nbr_partitions < 1) {
+		/* This code is reached when the device is opened for the first time
+		   after the driver has been initialized with tape in the drive and the
+		   partition support has been enabled. */
+                DEBC(printk(ST_DEB_MSG
+                            "%s: Updating partition number in status.\n", name));
+		if ((STp->partition = find_partition(STp)) < 0) {
+			retval = STp->partition;
+			goto err_out;
+		}
+		STp->new_partition = STp->partition;
+		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
+	}
+
+	if (new_session) {	/* Change the drive parameters for the new mode */
+		STp->density_changed = STp->blksize_changed = 0;
+		STp->compression_changed = 0;
+		if (!(STm->defaults_for_writes) &&
+		    (retval = set_mode_densblk(STp, STm)) < 0)
+		    goto err_out;
+
+		if (STp->default_drvbuffer != 0xff) {
+			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
+				printk(KERN_WARNING
+                                       "%s: Can't set default drive buffering to %d.\n",
+				       name, STp->default_drvbuffer);
+		}
+	}
+
+	return CHKRES_READY;
+
+ err_out:
+	return retval;
+}
+
+
+/* Open the device. Needs to be called with BKL only because of incrementing the SCSI host
+   module count. */
+static int st_open(struct inode *inode, struct file *filp)
+{
+	int i, retval = (-EIO);
+	struct scsi_tape *STp;
+	struct st_partstat *STps;
+	int dev = TAPE_NR(inode);
+	char *name;
+
+	/*
+	 * We really want to do nonseekable_open(inode, filp); here, but some
+	 * versions of tar incorrectly call lseek on tapes and bail out if that
+	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
+	 */
+	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
+
+	write_lock(&st_dev_arr_lock);
+	if (dev >= st_dev_max || scsi_tapes == NULL ||
+	    ((STp = scsi_tapes[dev]) == NULL)) {
+		write_unlock(&st_dev_arr_lock);
+		return (-ENXIO);
+	}
+	filp->private_data = STp;
+	name = tape_name(STp);
+
+	if (STp->in_use) {
+		write_unlock(&st_dev_arr_lock);
+		DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
+		return (-EBUSY);
+	}
+
+	if(scsi_device_get(STp->device)) {
+		write_unlock(&st_dev_arr_lock);
+		return (-ENXIO);
+	}
+	STp->in_use = 1;
+	write_unlock(&st_dev_arr_lock);
+	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
+
+	if (!scsi_block_when_processing_errors(STp->device)) {
+		retval = (-ENXIO);
+		goto err_out;
+	}
+
+	/* See that we have at least a one page buffer available */
+	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
+		printk(KERN_WARNING "%s: Can't allocate one page tape buffer.\n",
+		       name);
+		retval = (-EOVERFLOW);
+		goto err_out;
+	}
+
+	(STp->buffer)->writing = 0;
+	(STp->buffer)->syscall_result = 0;
+
+	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
+
+	STp->dirty = 0;
+	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
+		STps = &(STp->ps[i]);
+		STps->rw = ST_IDLE;
+	}
+	STp->recover_count = 0;
+	DEB( STp->nbr_waits = STp->nbr_finished = 0;
+	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = STp->nbr_combinable = 0; )
+
+	retval = check_tape(STp, filp);
+	if (retval < 0)
+		goto err_out;
+	if ((filp->f_flags & O_NONBLOCK) == 0 &&
+	    retval != CHKRES_READY) {
+		retval = (-EIO);
+		goto err_out;
+	}
+	return 0;
+
+ err_out:
+	normalize_buffer(STp->buffer);
+	STp->in_use = 0;
+	scsi_device_put(STp->device);
+	return retval;
+
+}
+
+
+/* Flush the tape buffer before close */
+static int st_flush(struct file *filp)
+{
+	int result = 0, result2;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt;
+	struct scsi_tape *STp = filp->private_data;
+	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
+	struct st_partstat *STps = &(STp->ps[STp->partition]);
+	char *name = tape_name(STp);
+
+	if (file_count(filp) > 1)
+		return 0;
+
+	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
+		result = flush_write_buffer(STp);
+		if (result != 0 && result != (-ENOSPC))
+			goto out;
+	}
+
+	if (STp->can_partitions &&
+	    (result2 = switch_partition(STp)) < 0) {
+                DEBC(printk(ST_DEB_MSG
+                               "%s: switch_partition at close failed.\n", name));
+		if (result == 0)
+			result = result2;
+		goto out;
+	}
+
+	DEBC( if (STp->nbr_requests)
+		printk(KERN_WARNING "%s: Number of r/w requests %d, dio used in %d, pages %d (%d).\n",
+		       name, STp->nbr_requests, STp->nbr_dio, STp->nbr_pages, STp->nbr_combinable));
+
+	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
+		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
+
+                DEBC(printk(ST_DEB_MSG "%s: Async write waits %d, finished %d.\n",
+                            name, STp->nbr_waits, STp->nbr_finished);
+		)
+
+		memset(cmd, 0, MAX_COMMAND_SIZE);
+		cmd[0] = WRITE_FILEMARKS;
+		cmd[4] = 1 + STp->two_fm;
+
+		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
+				   STp->device->timeout, MAX_WRITE_RETRIES, 1);
+		if (!SRpnt) {
+			result = (STp->buffer)->syscall_result;
+			goto out;
+		}
+
+		if (STp->buffer->syscall_result == 0 ||
+		    (cmdstatp->have_sense && !cmdstatp->deferred &&
+		     (cmdstatp->flags & SENSE_EOM) &&
+		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
+		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
+		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
+			/* Write successful at EOM */
+			scsi_release_request(SRpnt);
+			SRpnt = NULL;
+			if (STps->drv_file >= 0)
+				STps->drv_file++;
+			STps->drv_block = 0;
+			if (STp->two_fm)
+				cross_eof(STp, 0);
+			STps->eof = ST_FM;
+		}
+		else { /* Write error */
+			scsi_release_request(SRpnt);
+			SRpnt = NULL;
+			printk(KERN_ERR "%s: Error on write filemark.\n", name);
+			if (result == 0)
+				result = (-EIO);
+		}
+
+                DEBC(printk(ST_DEB_MSG "%s: Buffer flushed, %d EOF(s) written\n",
+                            name, cmd[4]));
+	} else if (!STp->rew_at_close) {
+		STps = &(STp->ps[STp->partition]);
+		if (!STm->sysv || STps->rw != ST_READING) {
+			if (STp->can_bsr)
+				result = flush_buffer(STp, 0);
+			else if (STps->eof == ST_FM_HIT) {
+				result = cross_eof(STp, 0);
+				if (result) {
+					if (STps->drv_file >= 0)
+						STps->drv_file++;
+					STps->drv_block = 0;
+					STps->eof = ST_FM;
+				} else
+					STps->eof = ST_NOEOF;
+			}
+		} else if ((STps->eof == ST_NOEOF &&
+			    !(result = cross_eof(STp, 1))) ||
+			   STps->eof == ST_FM_HIT) {
+			if (STps->drv_file >= 0)
+				STps->drv_file++;
+			STps->drv_block = 0;
+			STps->eof = ST_FM;
+		}
+	}
+
+      out:
+	if (STp->rew_at_close) {
+		result2 = st_int_ioctl(STp, MTREW, 1);
+		if (result == 0)
+			result = result2;
+	}
+	return result;
+}
+
+
+/* Close the device and release it. BKL is not needed: this is the only thread
+   accessing this tape. */
+static int st_release(struct inode *inode, struct file *filp)
+{
+	int result = 0;
+	struct scsi_tape *STp = filp->private_data;
+
+	if (STp->door_locked == ST_LOCKED_AUTO)
+		do_door_lock(STp, 0);
+
+	normalize_buffer(STp->buffer);
+	write_lock(&st_dev_arr_lock);
+	STp->in_use = 0;
+	write_unlock(&st_dev_arr_lock);
+	scsi_device_put(STp->device);
+
+	return result;
+}
+
+/* The checks common to both reading and writing */
+static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
+{
+	ssize_t retval = 0;
+
+	/*
+	 * If we are in the middle of error recovery, don't let anyone
+	 * else try and use this device.  Also, if error recovery fails, it
+	 * may try and take the device offline, in which case all further
+	 * access to the device is prohibited.
+	 */
+	if (!scsi_block_when_processing_errors(STp->device)) {
+		retval = (-ENXIO);
+		goto out;
+	}
+
+	if (STp->ready != ST_READY) {
+		if (STp->ready == ST_NO_TAPE)
+			retval = (-ENOMEDIUM);
+		else
+			retval = (-EIO);
+		goto out;
+	}
+
+	if (! STp->modes[STp->current_mode].defined) {
+		retval = (-ENXIO);
+		goto out;
+	}
+
+
+	/*
+	 * If there was a bus reset, block further access
+	 * to this device.
+	 */
+	if (STp->pos_unknown) {
+		retval = (-EIO);
+		goto out;
+	}
+
+	if (count == 0)
+		goto out;
+
+        DEB(
+	if (!STp->in_use) {
+		printk(ST_DEB_MSG "%s: Incorrect device.\n", tape_name(STp));
+		retval = (-EIO);
+		goto out;
+	} ) /* end DEB */
+
+	if (STp->can_partitions &&
+	    (retval = switch_partition(STp)) < 0)
+		goto out;
+
+	if (STp->block_size == 0 && STp->max_block > 0 &&
+	    (count < STp->min_block || count > STp->max_block)) {
+		retval = (-EINVAL);
+		goto out;
+	}
+
+	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
+	    !do_door_lock(STp, 1))
+		STp->door_locked = ST_LOCKED_AUTO;
+
+ out:
+	return retval;
+}
+
+
+static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
+			   size_t count, int is_read)
+{
+	int i, bufsize, retval = 0;
+	struct st_buffer *STbp = STp->buffer;
+
+	if (is_read)
+		i = STp->try_dio && try_rdio;
+	else
+		i = STp->try_dio && try_wdio;
+	if (i && ((unsigned long)buf & queue_dma_alignment(
+					STp->device->request_queue)) == 0) {
+		i = st_map_user_pages(&(STbp->sg[0]), STbp->use_sg,
+				      (unsigned long)buf, count, (is_read ? READ : WRITE),
+				      STp->max_pfn);
+		if (i > 0) {
+			STbp->do_dio = i;
+			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
+		}
+		else
+			STbp->do_dio = 0;  /* fall back to buffering with any error */
+		STbp->sg_segs = STbp->do_dio;
+		STbp->frp_sg_current = 0;
+		DEB(
+		     if (STbp->do_dio) {
+			STp->nbr_dio++;
+			STp->nbr_pages += STbp->do_dio;
+			for (i=1; i < STbp->do_dio; i++)
+				if (page_to_pfn(STbp->sg[i].page) == page_to_pfn(STbp->sg[i-1].page) + 1)
+					STp->nbr_combinable++;
+		     }
+		)
+	} else
+		STbp->do_dio = 0;
+	DEB( STp->nbr_requests++; )
+
+	if (!STbp->do_dio) {
+		if (STp->block_size)
+			bufsize = STp->block_size > st_fixed_buffer_size ?
+				STp->block_size : st_fixed_buffer_size;
+		else
+			bufsize = count;
+		if (bufsize > STbp->buffer_size &&
+		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
+			printk(KERN_WARNING "%s: Can't allocate %d byte tape buffer.\n",
+			       tape_name(STp), bufsize);
+			retval = (-EOVERFLOW);
+			goto out;
+		}
+		if (STp->block_size)
+			STbp->buffer_blocks = bufsize / STp->block_size;
+	}
+
+ out:
+	return retval;
+}
+
+
+/* Can be called more than once after each setup_buffer() */
+static void release_buffering(struct scsi_tape *STp)
+{
+	struct st_buffer *STbp;
+
+	STbp = STp->buffer;
+	if (STbp->do_dio) {
+		sgl_unmap_user_pages(&(STbp->sg[0]), STbp->do_dio, 0);
+		STbp->do_dio = 0;
+	}
+}
+
+
+/* Write command */
+static ssize_t
+st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
+{
+	ssize_t total;
+	ssize_t i, do_count, blks, transfer;
+	ssize_t retval;
+	int undone, retry_eot = 0, scode;
+	int async_write;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	const char __user *b_point;
+	struct scsi_request *SRpnt = NULL;
+	struct scsi_tape *STp = filp->private_data;
+	struct st_modedef *STm;
+	struct st_partstat *STps;
+	struct st_buffer *STbp;
+	char *name = tape_name(STp);
+
+	if (down_interruptible(&STp->lock))
+		return -ERESTARTSYS;
+
+	retval = rw_checks(STp, filp, count);
+	if (retval || count == 0)
+		goto out;
+
+	/* Write must be integral number of blocks */
+	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
+		printk(KERN_WARNING "%s: Write not multiple of tape block size.\n",
+		       name);
+		retval = (-EINVAL);
+		goto out;
+	}
+
+	STm = &(STp->modes[STp->current_mode]);
+	STps = &(STp->ps[STp->partition]);
+
+	if (STp->write_prot) {
+		retval = (-EACCES);
+		goto out;
+	}
+
+
+	if (STps->rw == ST_READING) {
+		retval = flush_buffer(STp, 0);
+		if (retval)
+			goto out;
+		STps->rw = ST_WRITING;
+	} else if (STps->rw != ST_WRITING &&
+		   STps->drv_file == 0 && STps->drv_block == 0) {
+		if ((retval = set_mode_densblk(STp, STm)) < 0)
+			goto out;
+		if (STm->default_compression != ST_DONT_TOUCH &&
+		    !(STp->compression_changed)) {
+			if (st_compression(STp, (STm->default_compression == ST_YES))) {
+				printk(KERN_WARNING "%s: Can't set default compression.\n",
+				       name);
+				if (modes_defined) {
+					retval = (-EINVAL);
+					goto out;
+				}
+			}
+		}
+	}
+
+	STbp = STp->buffer;
+	i = write_behind_check(STp);
+	if (i) {
+		if (i == -ENOSPC)
+			STps->eof = ST_EOM_OK;
+		else
+			STps->eof = ST_EOM_ERROR;
+	}
+
+	if (STps->eof == ST_EOM_OK) {
+		STps->eof = ST_EOD_1;  /* allow next write */
+		retval = (-ENOSPC);
+		goto out;
+	}
+	else if (STps->eof == ST_EOM_ERROR) {
+		retval = (-EIO);
+		goto out;
+	}
+
+	/* Check the buffer readability in cases where copy_user might catch
+	   the problems after some tape movement. */
+	if (STp->block_size != 0 &&
+	    !STbp->do_dio &&
+	    (copy_from_user(&i, buf, 1) != 0 ||
+	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
+		retval = (-EFAULT);
+		goto out;
+	}
+
+	retval = setup_buffering(STp, buf, count, 0);
+	if (retval)
+		goto out;
+
+	total = count;
+
+	memset(cmd, 0, MAX_COMMAND_SIZE);
+	cmd[0] = WRITE_6;
+	cmd[1] = (STp->block_size != 0);
+
+	STps->rw = ST_WRITING;
+
+	b_point = buf;
+	while (count > 0 && !retry_eot) {
+
+		if (STbp->do_dio) {
+			do_count = count;
+		}
+		else {
+			if (STp->block_size == 0)
+				do_count = count;
+			else {
+				do_count = STbp->buffer_blocks * STp->block_size -
+					STbp->buffer_bytes;
+				if (do_count > count)
+					do_count = count;
+			}
+
+			i = append_to_buffer(b_point, STbp, do_count);
+			if (i) {
+				retval = i;
+				goto out;
+			}
+		}
+		count -= do_count;
+		b_point += do_count;
+
+		async_write = STp->block_size == 0 && !STbp->do_dio &&
+			STm->do_async_writes && STps->eof < ST_EOM_OK;
+
+		if (STp->block_size != 0 && STm->do_buffer_writes &&
+		    !(STp->try_dio && try_wdio) && STps->eof < ST_EOM_OK &&
+		    STbp->buffer_bytes < STbp->buffer_size) {
+			STp->dirty = 1;
+			/* Don't write a buffer that is not full enough. */
+			if (!async_write && count == 0)
+				break;
+		}
+
+	retry_write:
+		if (STp->block_size == 0)
+			blks = transfer = do_count;
+		else {
+			if (!STbp->do_dio)
+				blks = STbp->buffer_bytes;
+			else
+				blks = do_count;
+			blks /= STp->block_size;
+			transfer = blks * STp->block_size;
+		}
+		cmd[2] = blks >> 16;
+		cmd[3] = blks >> 8;
+		cmd[4] = blks;
+
+		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
+				   STp->device->timeout, MAX_WRITE_RETRIES, !async_write);
+		if (!SRpnt) {
+			retval = STbp->syscall_result;
+			goto out;
+		}
+		if (async_write) {
+			STbp->writing = transfer;
+			STp->dirty = !(STbp->writing ==
+				       STbp->buffer_bytes);
+			SRpnt = NULL;  /* Prevent releasing this request! */
+			DEB( STp->write_pending = 1; )
+			break;
+		}
+
+		if (STbp->syscall_result != 0) {
+			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
+
+                        DEBC(printk(ST_DEB_MSG "%s: Error on write:\n", name));
+			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
+				scode = cmdstatp->sense_hdr.sense_key;
+				if (cmdstatp->remainder_valid)
+					undone = (int)cmdstatp->uremainder64;
+				else if (STp->block_size == 0 &&
+					 scode == VOLUME_OVERFLOW)
+					undone = transfer;
+				else
+					undone = 0;
+				if (STp->block_size != 0)
+					undone *= STp->block_size;
+				if (undone <= do_count) {
+					/* Only data from this write is not written */
+					count += undone;
+					do_count -= undone;
+					if (STp->block_size)
+						blks = (transfer - undone) / STp->block_size;
+					STps->eof = ST_EOM_OK;
+					/* Continue in fixed block mode if all written
+					   in this request but still something left to write
+					   (retval left to zero)
+					*/
+					if (STp->block_size == 0 ||
+					    undone > 0 || count == 0)
+						retval = (-ENOSPC); /* EOM within current request */
+                                        DEBC(printk(ST_DEB_MSG
+                                                       "%s: EOM with %d bytes unwritten.\n",
+						       name, (int)count));
+				} else {
+					/* EOT within data buffered earlier (possible only
+					   in fixed block mode without direct i/o) */
+					if (!retry_eot && !cmdstatp->deferred &&
+					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
+						move_buffer_data(STp->buffer, transfer - undone);
+						retry_eot = 1;
+						if (STps->drv_block >= 0) {
+							STps->drv_block += (transfer - undone) /
+								STp->block_size;
+						}
+						STps->eof = ST_EOM_OK;
+						DEBC(printk(ST_DEB_MSG
+							    "%s: Retry write of %d bytes at EOM.\n",
+							    name, STp->buffer->buffer_bytes));
+						goto retry_write;
+					}
+					else {
+						/* Either error within data buffered by driver or
+						   failed retry */
+						count -= do_count;
+						blks = do_count = 0;
+						STps->eof = ST_EOM_ERROR;
+						STps->drv_block = (-1); /* Too cautious? */
+						retval = (-EIO);	/* EOM for old data */
+						DEBC(printk(ST_DEB_MSG
+							    "%s: EOM with lost data.\n",
+							    name));
+					}
+				}
+			} else {
+				count += do_count;
+				STps->drv_block = (-1);		/* Too cautious? */
+				retval = (-EIO);
+			}
+
+		}
+
+		if (STps->drv_block >= 0) {
+			if (STp->block_size == 0)
+				STps->drv_block += (do_count > 0);
+			else
+				STps->drv_block += blks;
+		}
+
+		STbp->buffer_bytes = 0;
+		STp->dirty = 0;
+
+		if (retval || retry_eot) {
+			if (count < total)
+				retval = total - count;
+			goto out;
+		}
+	}
+
+	if (STps->eof == ST_EOD_1)
+		STps->eof = ST_EOM_OK;
+	else if (STps->eof != ST_EOM_OK)
+		STps->eof = ST_NOEOF;
+	retval = total - count;
+
+ out:
+	if (SRpnt != NULL)
+		scsi_release_request(SRpnt);
+	release_buffering(STp);
+	up(&STp->lock);
+
+	return retval;
+}
+
+/* Read data from the tape. Returns zero in the normal case, one if the
+   eof status has changed, and the negative error code in case of a
+   fatal error. Otherwise updates the buffer and the eof state.
+
+   Does release user buffer mapping if it is set.
+*/
+static long read_tape(struct scsi_tape *STp, long count,
+		      struct scsi_request ** aSRpnt)
+{
+	int transfer, blks, bytes;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt;
+	struct st_modedef *STm;
+	struct st_partstat *STps;
+	struct st_buffer *STbp;
+	int retval = 0;
+	char *name = tape_name(STp);
+
+	if (count == 0)
+		return 0;
+
+	STm = &(STp->modes[STp->current_mode]);
+	STps = &(STp->ps[STp->partition]);
+	if (STps->eof == ST_FM_HIT)
+		return 1;
+	STbp = STp->buffer;
+
+	if (STp->block_size == 0)
+		blks = bytes = count;
+	else {
+		if (!(STp->try_dio && try_rdio) && STm->do_read_ahead) {
+			blks = (STp->buffer)->buffer_blocks;
+			bytes = blks * STp->block_size;
+		} else {
+			bytes = count;
+			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
+				bytes = (STp->buffer)->buffer_size;
+			blks = bytes / STp->block_size;
+			bytes = blks * STp->block_size;
+		}
+	}
+
+	memset(cmd, 0, MAX_COMMAND_SIZE);
+	cmd[0] = READ_6;
+	cmd[1] = (STp->block_size != 0);
+	cmd[2] = blks >> 16;
+	cmd[3] = blks >> 8;
+	cmd[4] = blks;
+
+	SRpnt = *aSRpnt;
+	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
+			   STp->device->timeout, MAX_RETRIES, 1);
+	release_buffering(STp);
+	*aSRpnt = SRpnt;
+	if (!SRpnt)
+		return STbp->syscall_result;
+
+	STbp->read_pointer = 0;
+	STps->at_sm = 0;
+
+	/* Something to check */
+	if (STbp->syscall_result) {
+		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
+
+		retval = 1;
+		DEBC(printk(ST_DEB_MSG "%s: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
+                            name,
+                            SRpnt->sr_sense_buffer[0], SRpnt->sr_sense_buffer[1],
+                            SRpnt->sr_sense_buffer[2], SRpnt->sr_sense_buffer[3],
+                            SRpnt->sr_sense_buffer[4], SRpnt->sr_sense_buffer[5],
+                            SRpnt->sr_sense_buffer[6], SRpnt->sr_sense_buffer[7]));
+		if (cmdstatp->have_sense) {
+
+			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
+				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
+
+			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
+				/* Compute the residual count */
+				if (cmdstatp->remainder_valid)
+					transfer = (int)cmdstatp->uremainder64;
+				else
+					transfer = 0;
+				if (STp->block_size == 0 &&
+				    cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR)
+					transfer = bytes;
+
+				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
+					if (STp->block_size == 0) {
+						if (transfer <= 0) {
+							if (transfer < 0)
+								printk(KERN_NOTICE
+								       "%s: Failed to read %d byte block with %d byte transfer.\n",
+								       name, bytes - transfer, bytes);
+							if (STps->drv_block >= 0)
+								STps->drv_block += 1;
+							STbp->buffer_bytes = 0;
+							return (-ENOMEM);
+						}
+						STbp->buffer_bytes = bytes - transfer;
+					} else {
+						scsi_release_request(SRpnt);
+						SRpnt = *aSRpnt = NULL;
+						if (transfer == blks) {	/* We did not get anything, error */
+							printk(KERN_NOTICE "%s: Incorrect block size.\n", name);
+							if (STps->drv_block >= 0)
+								STps->drv_block += blks - transfer + 1;
+							st_int_ioctl(STp, MTBSR, 1);
+							return (-EIO);
+						}
+						/* We have some data, deliver it */
+						STbp->buffer_bytes = (blks - transfer) *
+						    STp->block_size;
+                                                DEBC(printk(ST_DEB_MSG
+                                                            "%s: ILI but enough data received %ld %d.\n",
+                                                            name, count, STbp->buffer_bytes));
+						if (STps->drv_block >= 0)
+							STps->drv_block += 1;
+						if (st_int_ioctl(STp, MTBSR, 1))
+							return (-EIO);
+					}
+				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
+					if (STps->eof != ST_FM_HIT)
+						STps->eof = ST_FM_HIT;
+					else
+						STps->eof = ST_EOD_2;
+					if (STp->block_size == 0)
+						STbp->buffer_bytes = 0;
+					else
+						STbp->buffer_bytes =
+						    bytes - transfer * STp->block_size;
+                                        DEBC(printk(ST_DEB_MSG
+                                                    "%s: EOF detected (%d bytes read).\n",
+                                                    name, STbp->buffer_bytes));
+				} else if (cmdstatp->flags & SENSE_EOM) {
+					if (STps->eof == ST_FM)
+						STps->eof = ST_EOD_1;
+					else
+						STps->eof = ST_EOM_OK;
+					if (STp->block_size == 0)
+						STbp->buffer_bytes = bytes - transfer;
+					else
+						STbp->buffer_bytes =
+						    bytes - transfer * STp->block_size;
+
+                                        DEBC(printk(ST_DEB_MSG "%s: EOM detected (%d bytes read).\n",
+                                                    name, STbp->buffer_bytes));
+				}
+			}
+			/* end of EOF, EOM, ILI test */ 
+			else {	/* nonzero sense key */
+                                DEBC(printk(ST_DEB_MSG
+                                            "%s: Tape error while reading.\n", name));
+				STps->drv_block = (-1);
+				if (STps->eof == ST_FM &&
+				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
+                                        DEBC(printk(ST_DEB_MSG
+                                                    "%s: Zero returned for first BLANK CHECK after EOF.\n",
+                                                    name));
+					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
+				} else	/* Some other extended sense code */
+					retval = (-EIO);
+			}
+
+			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
+				STbp->buffer_bytes = 0;
+		}
+		/* End of extended sense test */ 
+		else {		/* Non-extended sense */
+			retval = STbp->syscall_result;
+		}
+
+	}
+	/* End of error handling */ 
+	else			/* Read successful */
+		STbp->buffer_bytes = bytes;
+
+	if (STps->drv_block >= 0) {
+		if (STp->block_size == 0)
+			STps->drv_block++;
+		else
+			STps->drv_block += STbp->buffer_bytes / STp->block_size;
+	}
+	return retval;
+}
+
+
+/* Read command */
+static ssize_t
+st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
+{
+	ssize_t total;
+	ssize_t retval = 0;
+	ssize_t i, transfer;
+	int special, do_dio = 0;
+	struct scsi_request *SRpnt = NULL;
+	struct scsi_tape *STp = filp->private_data;
+	struct st_modedef *STm;
+	struct st_partstat *STps;
+	struct st_buffer *STbp = STp->buffer;
+	DEB( char *name = tape_name(STp); )
+
+	if (down_interruptible(&STp->lock))
+		return -ERESTARTSYS;
+
+	retval = rw_checks(STp, filp, count);
+	if (retval || count == 0)
+		goto out;
+
+	STm = &(STp->modes[STp->current_mode]);
+	if (!(STm->do_read_ahead) && STp->block_size != 0 &&
+	    (count % STp->block_size) != 0) {
+		retval = (-EINVAL);	/* Read must be integral number of blocks */
+		goto out;
+	}
+
+	STps = &(STp->ps[STp->partition]);
+	if (STps->rw == ST_WRITING) {
+		retval = flush_buffer(STp, 0);
+		if (retval)
+			goto out;
+		STps->rw = ST_READING;
+	}
+        DEB(
+	if (debugging && STps->eof != ST_NOEOF)
+		printk(ST_DEB_MSG "%s: EOF/EOM flag up (%d). Bytes %d\n", name,
+		       STps->eof, STbp->buffer_bytes);
+        ) /* end DEB */
+
+	retval = setup_buffering(STp, buf, count, 1);
+	if (retval)
+		goto out;
+	do_dio = STbp->do_dio;
+
+	if (STbp->buffer_bytes == 0 &&
+	    STps->eof >= ST_EOD_1) {
+		if (STps->eof < ST_EOD) {
+			STps->eof += 1;
+			retval = 0;
+			goto out;
+		}
+		retval = (-EIO);	/* EOM or Blank Check */
+		goto out;
+	}
+
+	if (do_dio) {
+		/* Check the buffer writability before any tape movement. Don't alter
+		   buffer data. */
+		if (copy_from_user(&i, buf, 1) != 0 ||
+		    copy_to_user(buf, &i, 1) != 0 ||
+		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
+		    copy_to_user(buf + count - 1, &i, 1) != 0) {
+			retval = (-EFAULT);
+			goto out;
+		}
+	}
+
+	STps->rw = ST_READING;
+
+
+	/* Loop until enough data in buffer or a special condition found */
+	for (total = 0, special = 0; total < count && !special;) {
+
+		/* Get new data if the buffer is empty */
+		if (STbp->buffer_bytes == 0) {
+			special = read_tape(STp, count - total, &SRpnt);
+			if (special < 0) {	/* No need to continue read */
+				retval = special;
+				goto out;
+			}
+		}
+
+		/* Move the data from driver buffer to user buffer */
+		if (STbp->buffer_bytes > 0) {
+                        DEB(
+			if (debugging && STps->eof != ST_NOEOF)
+				printk(ST_DEB_MSG
+                                       "%s: EOF up (%d). Left %d, needed %d.\n", name,
+				       STps->eof, STbp->buffer_bytes,
+                                       (int)(count - total));
+                        ) /* end DEB */
+			transfer = STbp->buffer_bytes < count - total ?
+			    STbp->buffer_bytes : count - total;
+			if (!do_dio) {
+				i = from_buffer(STbp, buf, transfer);
+				if (i) {
+					retval = i;
+					goto out;
+				}
+			}
+			buf += transfer;
+			total += transfer;
+		}
+
+		if (STp->block_size == 0)
+			break;	/* Read only one variable length block */
+
+	}			/* for (total = 0, special = 0;
+                                   total < count && !special; ) */
+
+	/* Change the eof state if no data from tape or buffer */
+	if (total == 0) {
+		if (STps->eof == ST_FM_HIT) {
+			STps->eof = ST_FM;
+			STps->drv_block = 0;
+			if (STps->drv_file >= 0)
+				STps->drv_file++;
+		} else if (STps->eof == ST_EOD_1) {
+			STps->eof = ST_EOD_2;
+			STps->drv_block = 0;
+			if (STps->drv_file >= 0)
+				STps->drv_file++;
+		} else if (STps->eof == ST_EOD_2)
+			STps->eof = ST_EOD;
+	} else if (STps->eof == ST_FM)
+		STps->eof = ST_NOEOF;
+	retval = total;
+
+ out:
+	if (SRpnt != NULL) {
+		scsi_release_request(SRpnt);
+		SRpnt = NULL;
+	}
+	if (do_dio) {
+		release_buffering(STp);
+		STbp->buffer_bytes = 0;
+	}
+	up(&STp->lock);
+
+	return retval;
+}
+
+
+
+DEB(
+/* Set the driver options */
+static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm, char *name)
+{
+	if (debugging) {
+		printk(KERN_INFO
+		       "%s: Mode %d options: buffer writes: %d, async writes: %d, read ahead: %d\n",
+		       name, STp->current_mode, STm->do_buffer_writes, STm->do_async_writes,
+		       STm->do_read_ahead);
+		printk(KERN_INFO
+		       "%s:    can bsr: %d, two FMs: %d, fast mteom: %d, auto lock: %d,\n",
+		       name, STp->can_bsr, STp->two_fm, STp->fast_mteom, STp->do_auto_lock);
+		printk(KERN_INFO
+		       "%s:    defs for wr: %d, no block limits: %d, partitions: %d, s2 log: %d\n",
+		       name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
+		       STp->scsi2_logical);
+		printk(KERN_INFO
+		       "%s:    sysv: %d nowait: %d\n", name, STm->sysv, STp->immediate);
+		printk(KERN_INFO "%s:    debugging: %d\n",
+		       name, debugging);
+	}
+}
+	)
+
+
+static int st_set_options(struct scsi_tape *STp, long options)
+{
+	int value;
+	long code;
+	struct st_modedef *STm;
+	char *name = tape_name(STp);
+	struct cdev *cd0, *cd1;
+
+	STm = &(STp->modes[STp->current_mode]);
+	if (!STm->defined) {
+		cd0 = STm->cdevs[0]; cd1 = STm->cdevs[1];
+		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
+		STm->cdevs[0] = cd0; STm->cdevs[1] = cd1;
+		modes_defined = 1;
+                DEBC(printk(ST_DEB_MSG
+                            "%s: Initialized mode %d definition from mode 0\n",
+                            name, STp->current_mode));
+	}
+
+	code = options & MT_ST_OPTIONS;
+	if (code == MT_ST_BOOLEANS) {
+		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
+		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
+		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
+		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
+		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
+		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
+		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
+		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
+		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
+		if ((STp->device)->scsi_level >= SCSI_2)
+			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
+		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
+		STp->immediate = (options & MT_ST_NOWAIT) != 0;
+		STm->sysv = (options & MT_ST_SYSV) != 0;
+		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
+		     st_log_options(STp, STm, name); )
+	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
+		value = (code == MT_ST_SETBOOLEANS);
+		if ((options & MT_ST_BUFFER_WRITES) != 0)
+			STm->do_buffer_writes = value;
+		if ((options & MT_ST_ASYNC_WRITES) != 0)
+			STm->do_async_writes = value;
+		if ((options & MT_ST_DEF_WRITES) != 0)
+			STm->defaults_for_writes = value;
+		if ((options & MT_ST_READ_AHEAD) != 0)
+			STm->do_read_ahead = value;
+		if ((options & MT_ST_TWO_FM) != 0)
+			STp->two_fm = value;
+		if ((options & MT_ST_FAST_MTEOM) != 0)
+			STp->fast_mteom = value;
+		if ((options & MT_ST_AUTO_LOCK) != 0)
+			STp->do_auto_lock = value;
+		if ((options & MT_ST_CAN_BSR) != 0)
+			STp->can_bsr = value;
+		if ((options & MT_ST_NO_BLKLIMS) != 0)
+			STp->omit_blklims = value;
+		if ((STp->device)->scsi_level >= SCSI_2 &&
+		    (options & MT_ST_CAN_PARTITIONS) != 0)
+			STp->can_partitions = value;
+		if ((options & MT_ST_SCSI2LOGICAL) != 0)
+			STp->scsi2_logical = value;
+		if ((options & MT_ST_NOWAIT) != 0)
+			STp->immediate = value;
+		if ((options & MT_ST_SYSV) != 0)
+			STm->sysv = value;
+                DEB(
+		if ((options & MT_ST_DEBUGGING) != 0)
+			debugging = value;
+			st_log_options(STp, STm, name); )
+	} else if (code == MT_ST_WRITE_THRESHOLD) {
+		/* Retained for compatibility */
+	} else if (code == MT_ST_DEF_BLKSIZE) {
+		value = (options & ~MT_ST_OPTIONS);
+		if (value == ~MT_ST_OPTIONS) {
+			STm->default_blksize = (-1);
+			DEBC( printk(KERN_INFO "%s: Default block size disabled.\n", name));
+		} else {
+			STm->default_blksize = value;
+			DEBC( printk(KERN_INFO "%s: Default block size set to %d bytes.\n",
+			       name, STm->default_blksize));
+			if (STp->ready == ST_READY) {
+				STp->blksize_changed = 0;
+				set_mode_densblk(STp, STm);
+			}
+		}
+	} else if (code == MT_ST_TIMEOUTS) {
+		value = (options & ~MT_ST_OPTIONS);
+		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
+			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
+			DEBC( printk(KERN_INFO "%s: Long timeout set to %d seconds.\n", name,
+			       (value & ~MT_ST_SET_LONG_TIMEOUT)));
+		} else {
+			STp->device->timeout = value * HZ;
+			DEBC( printk(KERN_INFO "%s: Normal timeout set to %d seconds.\n",
+				name, value) );
+		}
+	} else if (code == MT_ST_SET_CLN) {
+		value = (options & ~MT_ST_OPTIONS) & 0xff;
+		if (value != 0 &&
+		    value < EXTENDED_SENSE_START && value >= SCSI_SENSE_BUFFERSIZE)
+			return (-EINVAL);
+		STp->cln_mode = value;
+		STp->cln_sense_mask = (options >> 8) & 0xff;
+		STp->cln_sense_value = (options >> 16) & 0xff;
+		printk(KERN_INFO
+		       "%s: Cleaning request mode %d, mask %02x, value %02x\n",
+		       name, value, STp->cln_sense_mask, STp->cln_sense_value);
+	} else if (code == MT_ST_DEF_OPTIONS) {
+		code = (options & ~MT_ST_CLEAR_DEFAULT);
+		value = (options & MT_ST_CLEAR_DEFAULT);
+		if (code == MT_ST_DEF_DENSITY) {
+			if (value == MT_ST_CLEAR_DEFAULT) {
+				STm->default_density = (-1);
+				DEBC( printk(KERN_INFO "%s: Density default disabled.\n",
+                                       name));
+			} else {
+				STm->default_density = value & 0xff;
+				DEBC( printk(KERN_INFO "%s: Density default set to %x\n",
+				       name, STm->default_density));
+				if (STp->ready == ST_READY) {
+					STp->density_changed = 0;
+					set_mode_densblk(STp, STm);
+				}
+			}
+		} else if (code == MT_ST_DEF_DRVBUFFER) {
+			if (value == MT_ST_CLEAR_DEFAULT) {
+				STp->default_drvbuffer = 0xff;
+				DEBC( printk(KERN_INFO
+                                       "%s: Drive buffer default disabled.\n", name));
+			} else {
+				STp->default_drvbuffer = value & 7;
+				DEBC( printk(KERN_INFO
+                                       "%s: Drive buffer default set to %x\n",
+				       name, STp->default_drvbuffer));
+				if (STp->ready == ST_READY)
+					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
+			}
+		} else if (code == MT_ST_DEF_COMPRESSION) {
+			if (value == MT_ST_CLEAR_DEFAULT) {
+				STm->default_compression = ST_DONT_TOUCH;
+				DEBC( printk(KERN_INFO
+                                       "%s: Compression default disabled.\n", name));
+			} else {
+				if ((value & 0xff00) != 0) {
+					STp->c_algo = (value & 0xff00) >> 8;
+					DEBC( printk(KERN_INFO "%s: Compression algorithm set to 0x%x.\n",
+					       name, STp->c_algo));
+				}
+				if ((value & 0xff) != 0xff) {
+					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
+					DEBC( printk(KERN_INFO "%s: Compression default set to %x\n",
+					       name, (value & 1)));
+					if (STp->ready == ST_READY) {
+						STp->compression_changed = 0;
+						st_compression(STp, (STm->default_compression == ST_YES));
+					}
+				}
+			}
+		}
+	} else
+		return (-EIO);
+
+	return 0;
+}
+
+#define MODE_HEADER_LENGTH  4
+
+/* Mode header and page byte offsets */
+#define MH_OFF_DATA_LENGTH     0
+#define MH_OFF_MEDIUM_TYPE     1
+#define MH_OFF_DEV_SPECIFIC    2
+#define MH_OFF_BDESCS_LENGTH   3
+#define MP_OFF_PAGE_NBR        0
+#define MP_OFF_PAGE_LENGTH     1
+
+/* Mode header and page bit masks */
+#define MH_BIT_WP              0x80
+#define MP_MSK_PAGE_NBR        0x3f
+
+/* Don't return block descriptors */
+#define MODE_SENSE_OMIT_BDESCS 0x08
+
+#define MODE_SELECT_PAGE_FORMAT 0x10
+
+/* Read a mode page into the tape buffer. The block descriptors are included
+   if incl_block_descs is true. The page control is ored to the page number
+   parameter, if necessary. */
+static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
+{
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt = NULL;
+
+	memset(cmd, 0, MAX_COMMAND_SIZE);
+	cmd[0] = MODE_SENSE;
+	if (omit_block_descs)
+		cmd[1] = MODE_SENSE_OMIT_BDESCS;
+	cmd[2] = page;
+	cmd[4] = 255;
+
+	SRpnt = st_do_scsi(SRpnt, STp, cmd, cmd[4], DMA_FROM_DEVICE,
+			   STp->device->timeout, 0, 1);
+	if (SRpnt == NULL)
+		return (STp->buffer)->syscall_result;
+
+	scsi_release_request(SRpnt);
+
+	return (STp->buffer)->syscall_result;
+}
+
+
+/* Send the mode page in the tape buffer to the drive. Assumes that the mode data
+   in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
+static int write_mode_page(struct scsi_tape *STp, int page, int slow)
+{
+	int pgo;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt = NULL;
+
+	memset(cmd, 0, MAX_COMMAND_SIZE);
+	cmd[0] = MODE_SELECT;
+	cmd[1] = MODE_SELECT_PAGE_FORMAT;
+	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
+	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
+
+	/* Clear reserved fields */
+	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
+	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
+	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
+	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
+
+	SRpnt = st_do_scsi(SRpnt, STp, cmd, cmd[4], DMA_TO_DEVICE,
+			   (slow ? STp->long_timeout : STp->device->timeout), 0, 1);
+	if (SRpnt == NULL)
+		return (STp->buffer)->syscall_result;
+
+	scsi_release_request(SRpnt);
+
+	return (STp->buffer)->syscall_result;
+}
+
+
+#define COMPRESSION_PAGE        0x0f
+#define COMPRESSION_PAGE_LENGTH 16
+
+#define CP_OFF_DCE_DCC          2
+#define CP_OFF_C_ALGO           7
+
+#define DCE_MASK  0x80
+#define DCC_MASK  0x40
+#define RED_MASK  0x60
+
+
+/* Control the compression with mode page 15. Algorithm not changed if zero.
+
+   The block descriptors are read and written because Sony SDT-7000 does not
+   work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
+   Including block descriptors should not cause any harm to other drives. */
+
+static int st_compression(struct scsi_tape * STp, int state)
+{
+	int retval;
+	int mpoffs;  /* Offset to mode page start */
+	unsigned char *b_data = (STp->buffer)->b_data;
+	DEB( char *name = tape_name(STp); )
+
+	if (STp->ready != ST_READY)
+		return (-EIO);
+
+	/* Read the current page contents */
+	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
+	if (retval) {
+                DEBC(printk(ST_DEB_MSG "%s: Compression mode page not supported.\n",
+                            name));
+		return (-EIO);
+	}
+
+	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
+        DEBC(printk(ST_DEB_MSG "%s: Compression state is %d.\n", name,
+                    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0)));
+
+	/* Check if compression can be changed */
+	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
+                DEBC(printk(ST_DEB_MSG "%s: Compression not supported.\n", name));
+		return (-EIO);
+	}
+
+	/* Do the change */
+	if (state) {
+		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
+		if (STp->c_algo != 0)
+			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
+	}
+	else {
+		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
+		if (STp->c_algo != 0)
+			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
+	}
+
+	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
+	if (retval) {
+                DEBC(printk(ST_DEB_MSG "%s: Compression change failed.\n", name));
+		return (-EIO);
+	}
+        DEBC(printk(ST_DEB_MSG "%s: Compression state changed to %d.\n",
+		       name, state));
+
+	STp->compression_changed = 1;
+	return 0;
+}
+
+
+/* Process the load and unload commands (does unload if the load code is zero) */
+static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
+{
+	int retval = (-EIO), timeout;
+	DEB( char *name = tape_name(STp); )
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct st_partstat *STps;
+	struct scsi_request *SRpnt;
+
+	if (STp->ready != ST_READY && !load_code) {
+		if (STp->ready == ST_NO_TAPE)
+			return (-ENOMEDIUM);
+		else
+			return (-EIO);
+	}
+
+	memset(cmd, 0, MAX_COMMAND_SIZE);
+	cmd[0] = START_STOP;
+	if (load_code)
+		cmd[4] |= 1;
+	/*
+	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
+	 */
+	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
+	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
+		DEBC(printk(ST_DEB_MSG "%s: Enhanced %sload slot %2d.\n",
+			    name, (cmd[4]) ? "" : "un",
+			    load_code - MT_ST_HPLOADER_OFFSET));
+		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
+	}
+	if (STp->immediate) {
+		cmd[1] = 1;	/* Don't wait for completion */
+		timeout = STp->device->timeout;
+	}
+	else
+		timeout = STp->long_timeout;
+
+	DEBC(
+		if (!load_code)
+		printk(ST_DEB_MSG "%s: Unloading tape.\n", name);
+		else
+		printk(ST_DEB_MSG "%s: Loading tape.\n", name);
+		);
+
+	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
+			   timeout, MAX_RETRIES, 1);
+	if (!SRpnt)
+		return (STp->buffer)->syscall_result;
+
+	retval = (STp->buffer)->syscall_result;
+	scsi_release_request(SRpnt);
+
+	if (!retval) {	/* SCSI command successful */
+
+		if (!load_code) {
+			STp->rew_at_close = 0;
+			STp->ready = ST_NO_TAPE;
+		}
+		else {
+			STp->rew_at_close = STp->autorew_dev;
+			retval = check_tape(STp, filp);
+			if (retval > 0)
+				retval = 0;
+		}
+	}
+	else {
+		STps = &(STp->ps[STp->partition]);
+		STps->drv_file = STps->drv_block = (-1);
+	}
+
+	return retval;
+}
+
+#if DEBUG
+#define ST_DEB_FORWARD  0
+#define ST_DEB_BACKWARD 1
+static void deb_space_print(char *name, int direction, char *units, unsigned char *cmd)
+{
+	s32 sc;
+
+	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
+	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
+	if (direction)
+		sc = -sc;
+	printk(ST_DEB_MSG "%s: Spacing tape %s over %d %s.\n", name,
+	       direction ? "backward" : "forward", sc, units);
+}
+#endif
+
+
+/* Internal ioctl function */
+static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
+{
+	int timeout;
+	long ltmp;
+	int ioctl_result;
+	int chg_eof = 1;
+	unsigned char cmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt;
+	struct st_partstat *STps;
+	int fileno, blkno, at_sm, undone;
+	int datalen = 0, direction = DMA_NONE;
+	char *name = tape_name(STp);
+
+	WARN_ON(STp->buffer->do_dio != 0);
+	if (STp->ready != ST_READY) {
+		if (STp->ready == ST_NO_TAPE)
+			return (-ENOMEDIUM);
+		else
+			return (-EIO);
+	}
+	timeout = STp->long_timeout;
+	STps = &(STp->ps[STp->partition]);
+	fileno = STps->drv_file;
+	blkno = STps->drv_block;
+	at_sm = STps->at_sm;
+
+	memset(cmd, 0, MAX_COMMAND_SIZE);
+	switch (cmd_in) {
+	case MTFSFM:
+		chg_eof = 0;	/* Changed from the FSF after this */
+	case MTFSF:
+		cmd[0] = SPACE;
+		cmd[1] = 0x01;	/* Space FileMarks */
+		cmd[2] = (arg >> 16);
+		cmd[3] = (arg >> 8);
+		cmd[4] = arg;
+                DEBC(deb_space_print(name, ST_DEB_FORWARD, "filemarks", cmd);)
+		if (fileno >= 0)
+			fileno += arg;
+		blkno = 0;
+		at_sm &= (arg == 0);
+		break;
+	case MTBSFM:
+		chg_eof = 0;	/* Changed from the FSF after this */
+	case MTBSF:
+		cmd[0] = SPACE;
+		cmd[1] = 0x01;	/* Space FileMarks */
+		ltmp = (-arg);
+		cmd[2] = (ltmp >> 16);
+		cmd[3] = (ltmp >> 8);
+		cmd[4] = ltmp;
+                DEBC(deb_space_print(name, ST_DEB_BACKWARD, "filemarks", cmd);)
+		if (fileno >= 0)
+			fileno -= arg;
+		blkno = (-1);	/* We can't know the block number */
+		at_sm &= (arg == 0);
+		break;
+	case MTFSR:
+		cmd[0] = SPACE;
+		cmd[1] = 0x00;	/* Space Blocks */
+		cmd[2] = (arg >> 16);
+		cmd[3] = (arg >> 8);
+		cmd[4] = arg;
+                DEBC(deb_space_print(name, ST_DEB_FORWARD, "blocks", cmd);)
+		if (blkno >= 0)
+			blkno += arg;
+		at_sm &= (arg == 0);
+		break;
+	case MTBSR:
+		cmd[0] = SPACE;
+		cmd[1] = 0x00;	/* Space Blocks */
+		ltmp = (-arg);
+		cmd[2] = (ltmp >> 16);
+		cmd[3] = (ltmp >> 8);
+		cmd[4] = ltmp;
+                DEBC(deb_space_print(name, ST_DEB_BACKWARD, "blocks", cmd);)
+		if (blkno >= 0)
+			blkno -= arg;
+		at_sm &= (arg == 0);
+		break;
+	case MTFSS:
+		cmd[0] = SPACE;
+		cmd[1] = 0x04;	/* Space Setmarks */
+		cmd[2] = (arg >> 16);
+		cmd[3] = (arg >> 8);
+		cmd[4] = arg;
+                DEBC(deb_space_print(name, ST_DEB_FORWARD, "setmarks", cmd);)
+		if (arg != 0) {
+			blkno = fileno = (-1);
+			at_sm = 1;
+		}
+		break;
+	case MTBSS:
+		cmd[0] = SPACE;
+		cmd[1] = 0x04;	/* Space Setmarks */
+		ltmp = (-arg);
+		cmd[2] = (ltmp >> 16);
+		cmd[3] = (ltmp >> 8);
+		cmd[4] = ltmp;
+                DEBC(deb_space_print(name, ST_DEB_BACKWARD, "setmarks", cmd);)
+		if (arg != 0) {
+			blkno = fileno = (-1);
+			at_sm = 1;
+		}
+		break;
+	case MTWEOF:
+	case MTWSM:
+		if (STp->write_prot)
+			return (-EACCES);
+		cmd[0] = WRITE_FILEMARKS;
+		if (cmd_in == MTWSM)
+			cmd[1] = 2;
+		cmd[2] = (arg >> 16);
+		cmd[3] = (arg >> 8);
+		cmd[4] = arg;
+		timeout = STp->device->timeout;
+                DEBC(
+                     if (cmd_in == MTWEOF)
+                               printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name,
+				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
+                     else
+				printk(ST_DEB_MSG "%s: Writing %d setmarks.\n", name,
+				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
+		)
+		if (fileno >= 0)
+			fileno += arg;
+		blkno = 0;
+		at_sm = (cmd_in == MTWSM);
+		break;
+	case MTREW:
+		cmd[0] = REZERO_UNIT;
+		if (STp->immediate) {
+			cmd[1] = 1;	/* Don't wait for completion */
+			timeout = STp->device->timeout;
+		}
+                DEBC(printk(ST_DEB_MSG "%s: Rewinding tape.\n", name));
+		fileno = blkno = at_sm = 0;
+		break;
+	case MTNOP:
+                DEBC(printk(ST_DEB_MSG "%s: No op on tape.\n", name));
+		return 0;	/* Should do something ? */
+		break;
+	case MTRETEN:
+		cmd[0] = START_STOP;
+		if (STp->immediate) {
+			cmd[1] = 1;	/* Don't wait for completion */
+			timeout = STp->device->timeout;
+		}
+		cmd[4] = 3;
+                DEBC(printk(ST_DEB_MSG "%s: Retensioning tape.\n", name));
+		fileno = blkno = at_sm = 0;
+		break;
+	case MTEOM:
+		if (!STp->fast_mteom) {
+			/* space to the end of tape */
+			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
+			fileno = STps->drv_file;
+			if (STps->eof >= ST_EOD_1)
+				return 0;
+			/* The next lines would hide the number of spaced FileMarks
+			   That's why I inserted the previous lines. I had no luck
+			   with detecting EOM with FSF, so we go now to EOM.
+			   Joerg Weule */
+		} else
+			fileno = (-1);
+		cmd[0] = SPACE;
+		cmd[1] = 3;
+                DEBC(printk(ST_DEB_MSG "%s: Spacing to end of recorded medium.\n",
+                            name));
+		blkno = -1;
+		at_sm = 0;
+		break;
+	case MTERASE:
+		if (STp->write_prot)
+			return (-EACCES);
+		cmd[0] = ERASE;
+		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
+		if (STp->immediate) {
+			cmd[1] |= 2;	/* Don't wait for completion */
+			timeout = STp->device->timeout;
+		}
+		else
+			timeout = STp->long_timeout * 8;
+
+                DEBC(printk(ST_DEB_MSG "%s: Erasing tape.\n", name));
+		fileno = blkno = at_sm = 0;
+		break;
+	case MTSETBLK:		/* Set block length */
+	case MTSETDENSITY:	/* Set tape density */
+	case MTSETDRVBUFFER:	/* Set drive buffering */
+	case SET_DENS_AND_BLK:	/* Set density and block size */
+		chg_eof = 0;
+		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
+			return (-EIO);	/* Not allowed if data in buffer */
+		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
+		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
+		    STp->max_block > 0 &&
+		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
+		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
+			printk(KERN_WARNING "%s: Illegal block size.\n", name);
+			return (-EINVAL);
+		}
+		cmd[0] = MODE_SELECT;
+		if ((STp->use_pf & USE_PF))
+			cmd[1] = MODE_SELECT_PAGE_FORMAT;
+		cmd[4] = datalen = 12;
+		direction = DMA_TO_DEVICE;
+
+		memset((STp->buffer)->b_data, 0, 12);
+		if (cmd_in == MTSETDRVBUFFER)
+			(STp->buffer)->b_data[2] = (arg & 7) << 4;
+		else
+			(STp->buffer)->b_data[2] =
+			    STp->drv_buffer << 4;
+		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
+		if (cmd_in == MTSETDENSITY) {
+			(STp->buffer)->b_data[4] = arg;
+			STp->density_changed = 1;	/* At least we tried ;-) */
+		} else if (cmd_in == SET_DENS_AND_BLK)
+			(STp->buffer)->b_data[4] = arg >> 24;
+		else
+			(STp->buffer)->b_data[4] = STp->density;
+		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
+			ltmp = arg & MT_ST_BLKSIZE_MASK;
+			if (cmd_in == MTSETBLK)
+				STp->blksize_changed = 1; /* At least we tried ;-) */
+		} else
+			ltmp = STp->block_size;
+		(STp->buffer)->b_data[9] = (ltmp >> 16);
+		(STp->buffer)->b_data[10] = (ltmp >> 8);
+		(STp->buffer)->b_data[11] = ltmp;
+		timeout = STp->device->timeout;
+                DEBC(
+			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
+				printk(ST_DEB_MSG
+                                       "%s: Setting block size to %d bytes.\n", name,
+				       (STp->buffer)->b_data[9] * 65536 +
+				       (STp->buffer)->b_data[10] * 256 +
+				       (STp->buffer)->b_data[11]);
+			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
+				printk(ST_DEB_MSG
+                                       "%s: Setting density code to %x.\n", name,
+				       (STp->buffer)->b_data[4]);
+			if (cmd_in == MTSETDRVBUFFER)
+				printk(ST_DEB_MSG
+                                       "%s: Setting drive buffer code to %d.\n", name,
+				    ((STp->buffer)->b_data[2] >> 4) & 7);
+		)
+		break;
+	default:
+		return (-ENOSYS);
+	}
+
+	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
+			   timeout, MAX_RETRIES, 1);
+	if (!SRpnt)
+		return (STp->buffer)->syscall_result;
+
+	ioctl_result = (STp->buffer)->syscall_result;
+
+	if (!ioctl_result) {	/* SCSI command successful */
+		scsi_release_request(SRpnt);
+		SRpnt = NULL;
+		STps->drv_block = blkno;
+		STps->drv_file = fileno;
+		STps->at_sm = at_sm;
+
+		if (cmd_in == MTBSFM)
+			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
+		else if (cmd_in == MTFSFM)
+			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
+
+		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
+			int old_block_size = STp->block_size;
+			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
+			if (STp->block_size != 0) {
+				if (old_block_size == 0)
+					normalize_buffer(STp->buffer);
+				(STp->buffer)->buffer_blocks =
+				    (STp->buffer)->buffer_size / STp->block_size;
+			}
+			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
+			if (cmd_in == SET_DENS_AND_BLK)
+				STp->density = arg >> MT_ST_DENSITY_SHIFT;
+		} else if (cmd_in == MTSETDRVBUFFER)
+			STp->drv_buffer = (arg & 7);
+		else if (cmd_in == MTSETDENSITY)
+			STp->density = arg;
+
+		if (cmd_in == MTEOM)
+			STps->eof = ST_EOD;
+		else if (cmd_in == MTFSF)
+			STps->eof = ST_FM;
+		else if (chg_eof)
+			STps->eof = ST_NOEOF;
+
+		if (cmd_in == MTWEOF)
+			STps->rw = ST_IDLE;
+	} else { /* SCSI command was not completely successful. Don't return
+                    from this block without releasing the SCSI command block! */
+		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
+
+		if (cmdstatp->flags & SENSE_EOM) {
+			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
+			    cmd_in != MTBSR && cmd_in != MTBSS)
+				STps->eof = ST_EOM_OK;
+			STps->drv_block = 0;
+		}
+
+		if (cmdstatp->remainder_valid)
+			undone = (int)cmdstatp->uremainder64;
+		else
+			undone = 0;
+
+		if (cmd_in == MTWEOF &&
+		    cmdstatp->have_sense &&
+		    (cmdstatp->flags & SENSE_EOM) &&
+		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
+		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
+		    undone == 0) {
+			ioctl_result = 0;	/* EOF written succesfully at EOM */
+			if (fileno >= 0)
+				fileno++;
+			STps->drv_file = fileno;
+			STps->eof = ST_NOEOF;
+		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
+			if (fileno >= 0)
+				STps->drv_file = fileno - undone;
+			else
+				STps->drv_file = fileno;
+			STps->drv_block = -1;
+			STps->eof = ST_NOEOF;
+		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
+			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
+				undone = (-undone);
+			if (STps->drv_file >= 0)
+				STps->drv_file = fileno + undone;
+			STps->drv_block = 0;
+			STps->eof = ST_NOEOF;
+		} else if (cmd_in == MTFSR) {
+			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
+				if (STps->drv_file >= 0)
+					STps->drv_file++;
+				STps->drv_block = 0;
+				STps->eof = ST_FM;
+			} else {
+				if (blkno >= undone)
+					STps->drv_block = blkno - undone;
+				else
+					STps->drv_block = (-1);
+				STps->eof = ST_NOEOF;
+			}
+		} else if (cmd_in == MTBSR) {
+			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
+				STps->drv_file--;
+				STps->drv_block = (-1);
+			} else {
+				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
+					undone = (-undone);
+				if (STps->drv_block >= 0)
+					STps->drv_block = blkno + undone;
+			}
+			STps->eof = ST_NOEOF;
+		} else if (cmd_in == MTEOM) {
+			STps->drv_file = (-1);
+			STps->drv_block = (-1);
+			STps->eof = ST_EOD;
+		} else if (cmd_in == MTSETBLK ||
+			   cmd_in == MTSETDENSITY ||
+			   cmd_in == MTSETDRVBUFFER ||
+			   cmd_in == SET_DENS_AND_BLK) {
+			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
+			    !(STp->use_pf & PF_TESTED)) {
+				/* Try the other possible state of Page Format if not
+				   already tried */
+				STp->use_pf = !STp->use_pf | PF_TESTED;
+				scsi_release_request(SRpnt);
+				SRpnt = NULL;
+				return st_int_ioctl(STp, cmd_in, arg);
+			}
+		} else if (chg_eof)
+			STps->eof = ST_NOEOF;
+
+		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
+			STps->eof = ST_EOD;
+
+		scsi_release_request(SRpnt);
+		SRpnt = NULL;
+	}
+
+	return ioctl_result;
+}
+
+
+/* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
+   structure. */
+
+static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
+			int logical)
+{
+	int result;
+	unsigned char scmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt;
+	DEB( char *name = tape_name(STp); )
+
+	if (STp->ready != ST_READY)
+		return (-EIO);
+
+	memset(scmd, 0, MAX_COMMAND_SIZE);
+	if ((STp->device)->scsi_level < SCSI_2) {
+		scmd[0] = QFA_REQUEST_BLOCK;
+		scmd[4] = 3;
+	} else {
+		scmd[0] = READ_POSITION;
+		if (!logical && !STp->scsi2_logical)
+			scmd[1] = 1;
+	}
+	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
+			STp->device->timeout, MAX_READY_RETRIES, 1);
+	if (!SRpnt)
+		return (STp->buffer)->syscall_result;
+
+	if ((STp->buffer)->syscall_result != 0 ||
+	    (STp->device->scsi_level >= SCSI_2 &&
+	     ((STp->buffer)->b_data[0] & 4) != 0)) {
+		*block = *partition = 0;
+                DEBC(printk(ST_DEB_MSG "%s: Can't read tape position.\n", name));
+		result = (-EIO);
+	} else {
+		result = 0;
+		if ((STp->device)->scsi_level < SCSI_2) {
+			*block = ((STp->buffer)->b_data[0] << 16)
+			    + ((STp->buffer)->b_data[1] << 8)
+			    + (STp->buffer)->b_data[2];
+			*partition = 0;
+		} else {
+			*block = ((STp->buffer)->b_data[4] << 24)
+			    + ((STp->buffer)->b_data[5] << 16)
+			    + ((STp->buffer)->b_data[6] << 8)
+			    + (STp->buffer)->b_data[7];
+			*partition = (STp->buffer)->b_data[1];
+			if (((STp->buffer)->b_data[0] & 0x80) &&
+			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
+				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
+		}
+                DEBC(printk(ST_DEB_MSG "%s: Got tape pos. blk %d part %d.\n", name,
+                            *block, *partition));
+	}
+	scsi_release_request(SRpnt);
+	SRpnt = NULL;
+
+	return result;
+}
+
+
+/* Set the tape block and partition. Negative partition means that only the
+   block should be set in vendor specific way. */
+static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
+			int logical)
+{
+	struct st_partstat *STps;
+	int result, p;
+	unsigned int blk;
+	int timeout;
+	unsigned char scmd[MAX_COMMAND_SIZE];
+	struct scsi_request *SRpnt;
+	DEB( char *name = tape_name(STp); )
+
+	if (STp->ready != ST_READY)
+		return (-EIO);
+	timeout = STp->long_timeout;
+	STps = &(STp->ps[STp->partition]);
+
+        DEBC(printk(ST_DEB_MSG "%s: Setting block to %d and partition to %d.\n",
+                    name, block, partition));
+	DEB(if (partition < 0)
+		return (-EIO); )
+
+	/* Update the location at the partition we are leaving */
+	if ((!STp->can_partitions && partition != 0) ||
+	    partition >= ST_NBR_PARTITIONS)
+		return (-EINVAL);
+	if (partition != STp->partition) {
+		if (get_location(STp, &blk, &p, 1))
+			STps->last_block_valid = 0;
+		else {
+			STps->last_block_valid = 1;
+			STps->last_block_visited = blk;
+                        DEBC(printk(ST_DEB_MSG
+                                    "%s: Visited block %d for partition %d saved.\n",
+                                    name, blk, STp->partition));
+		}
+	}
+
+	memset(scmd, 0, MAX_COMMAND_SIZE);
+	if ((STp->device)->scsi_level < SCSI_2) {
+		scmd[0] = QFA_SEEK_BLOCK;
+		scmd[2] = (block >> 16);
+		scmd[3] = (block >> 8);
+		scmd[4] = block;
+		scmd[5] = 0;
+	} else {
+		scmd[0] = SEEK_10;
+		scmd[3] = (block >> 24);
+		scmd[4] = (block >> 16);
+		scmd[5] = (block >> 8);
+		scmd[6] = block;
+		if (!logical && !STp->scsi2_logical)
+			scmd[1] = 4;
+		if (STp->partition != partition) {
+			scmd[1] |= 2;
+			scmd[8] = partition;
+                        DEBC(printk(ST_DEB_MSG
+                                    "%s: Trying to change partition from %d to %d\n",
+                                    name, STp->partition, partition));
+		}
+	}
+	if (STp->immediate) {
+		scmd[1] |= 1;		/* Don't wait for completion */
+		timeout = STp->device->timeout;
+	}
+
+	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
+			   timeout, MAX_READY_RETRIES, 1);
+	if (!SRpnt)
+		return (STp->buffer)->syscall_result;
+
+	STps->drv_block = STps->drv_file = (-1);
+	STps->eof = ST_NOEOF;
+	if ((STp->buffer)->syscall_result != 0) {
+		result = (-EIO);
+		if (STp->can_partitions &&
+		    (STp->device)->scsi_level >= SCSI_2 &&
+		    (p = find_partition(STp)) >= 0)
+			STp->partition = p;
+	} else {
+		if (STp->can_partitions) {
+			STp->partition = partition;
+			STps = &(STp->ps[partition]);
+			if (!STps->last_block_valid ||
+			    STps->last_block_visited != block) {
+				STps->at_sm = 0;
+				STps->rw = ST_IDLE;
+			}
+		} else
+			STps->at_sm = 0;
+		if (block == 0)
+			STps->drv_block = STps->drv_file = 0;
+		result = 0;
+	}
+
+	scsi_release_request(SRpnt);
+	SRpnt = NULL;
+
+	return result;
+}
+
+
+/* Find the current partition number for the drive status. Called from open and
+   returns either partition number of negative error code. */
+static int find_partition(struct scsi_tape *STp)
+{
+	int i, partition;
+	unsigned int block;
+
+	if ((i = get_location(STp, &block, &partition, 1)) < 0)
+		return i;
+	if (partition >= ST_NBR_PARTITIONS)
+		return (-EIO);
+	return partition;
+}
+
+
+/* Change the partition if necessary */
+static int switch_partition(struct scsi_tape *STp)
+{
+	struct st_partstat *STps;
+
+	if (STp->partition == STp->new_partition)
+		return 0;
+	STps = &(STp->ps[STp->new_partition]);
+	if (!STps->last_block_valid)
+		STps->last_block_visited = 0;
+	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
+}
+
+/* Functions for reading and writing the medium partition mode page. */
+
+#define PART_PAGE   0x11
+#define PART_PAGE_FIXED_LENGTH 8
+
+#define PP_OFF_MAX_ADD_PARTS   2
+#define PP_OFF_NBR_ADD_PARTS   3
+#define PP_OFF_FLAGS           4
+#define PP_OFF_PART_UNITS      6
+#define PP_OFF_RESERVED        7
+
+#define PP_BIT_IDP             0x20
+#define PP_MSK_PSUM_MB         0x10
+
+/* Get the number of partitions on the tape. As a side effect reads the
+   mode page into the tape buffer. */
+static int nbr_partitions(struct scsi_tape *STp)
+{
+	int result;
+	DEB( char *name = tape_name(STp); )
+
+	if (STp->ready != ST_READY)
+		return (-EIO);
+
+	result = read_mode_page(STp, PART_PAGE, 1);
+
+	if (result) {
+                DEBC(printk(ST_DEB_MSG "%s: Can't read medium partition page.\n",
+                            name));
+		result = (-EIO);
+	} else {
+		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
+					      PP_OFF_NBR_ADD_PARTS] + 1;
+                DEBC(printk(ST_DEB_MSG "%s: Number of partitions %d.\n", name, result));
+	}
+
+	return result;
+}
+
+
+/* Partition the tape into two partitions if size > 0 or one partition if
+   size == 0.
+
+   The block descriptors are read and written because Sony SDT-7000 does not
+   work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
+
+   My HP C1533A drive returns only one partition size field. This is used to
+   set the size of partition 1. There is no size field for the default partition.
+   Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
+   used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
+   The following algorithm is used to accommodate both drives: if the number of
+   partition size fields is greater than the maximum number of additional partitions
+   in the mode page, the second field is used. Otherwise the first field is used.
+
+   For Seagate DDS drives the page length must be 8 when no partitions is defined
+   and 10 when 1 partition is defined (information from Eric Lee Green). This is
+   is acceptable also to some other old drives and enforced if the first partition
+   size field is used for the first additional partition size.
+ */
+static int partition_tape(struct scsi_tape *STp, int size)
+{
+	char *name = tape_name(STp);
+	int result;
+	int pgo, psd_cnt, psdo;
+	unsigned char *bp;
+
+	result = read_mode_page(STp, PART_PAGE, 0);
+	if (result) {
+		DEBC(printk(ST_DEB_MSG "%s: Can't read partition mode page.\n", name));
+		return result;
+	}
+	/* The mode page is in the buffer. Let's modify it and write it. */
+	bp = (STp->buffer)->b_data;
+	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
+	DEBC(printk(ST_DEB_MSG "%s: Partition page length is %d bytes.\n",
+		    name, bp[pgo + MP_OFF_PAGE_LENGTH] + 2));
+
+	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
+	psdo = pgo + PART_PAGE_FIXED_LENGTH;
+	if (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS]) {
+		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest of the tape */
+		psdo += 2;
+	}
+	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
+
+	DEBC(printk("%s: psd_cnt %d, max.parts %d, nbr_parts %d\n", name,
+		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
+		    bp[pgo + PP_OFF_NBR_ADD_PARTS]));
+
+	if (size <= 0) {
+		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
+		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
+		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
+                DEBC(printk(ST_DEB_MSG "%s: Formatting tape with one partition.\n",
+                            name));
+	} else {
+		bp[psdo] = (size >> 8) & 0xff;
+		bp[psdo + 1] = size & 0xff;
+		bp[pgo + 3] = 1;
+		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
+		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
+                DEBC(printk(ST_DEB_MSG
+                            "%s: Formatting tape with two partitions (1 = %d MB).\n",
+                            name, size));
+	}
+	bp[pgo + PP_OFF_PART_UNITS] = 0;
+	bp[pgo + PP_OFF_RESERVED] = 0;
+	bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | PP_MSK_PSUM_MB;
+
+	result = write_mode_page(STp, PART_PAGE, 1);
+	if (result) {
+		printk(KERN_INFO "%s: Partitioning of tape failed.\n", name);
+		result = (-EIO);
+	}
+
+	return result;
+}
+
+
+
+/* The ioctl command */
+static int st_ioctl(struct inode *inode, struct file *file,
+		    unsigned int cmd_in, unsigned long arg)
+{
+	int i, cmd_nr, cmd_type, bt;
+	int retval = 0;
+	unsigned int blk;
+	struct scsi_tape *STp = file->private_data;
+	struct st_modedef *STm;
+	struct st_partstat *STps;
+	char *name = tape_name(STp);
+	void __user *p = (void __user *)arg;
+
+	if (down_interruptible(&STp->lock))
+		return -ERESTARTSYS;
+
+        DEB(
+	if (debugging && !STp->in_use) {
+		printk(ST_DEB_MSG "%s: Incorrect device.\n", name);
+		retval = (-EIO);
+		goto out;
+	} ) /* end DEB */
+
+	STm = &(STp->modes[STp->current_mode]);
+	STps = &(STp->ps[STp->partition]);
+
+	/*
+	 * If we are in the middle of error recovery, don't let anyone
+	 * else try and use this device.  Also, if error recovery fails, it
+	 * may try and take the device offline, in which case all further
+	 * access to the device is prohibited.
+	 */
+	retval = scsi_nonblockable_ioctl(STp->device, cmd_in, p, file);
+	if (!scsi_block_when_processing_errors(STp->device) || retval != -ENODEV)
+		goto out;
+	retval = 0;
+
+	cmd_type = _IOC_TYPE(cmd_in);
+	cmd_nr = _IOC_NR(cmd_in);
+
+	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
+		struct mtop mtc;
+
+		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
+			retval = (-EINVAL);
+			goto out;
+		}
+
+		i = copy_from_user(&mtc, p, sizeof(struct mtop));
+		if (i) {
+			retval = (-EFAULT);
+			goto out;
+		}
+
+		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
+			printk(KERN_WARNING
+                               "%s: MTSETDRVBUFFER only allowed for root.\n", name);
+			retval = (-EPERM);
+			goto out;
+		}
+		if (!STm->defined &&
+		    (mtc.mt_op != MTSETDRVBUFFER &&
+		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
+			retval = (-ENXIO);
+			goto out;
+		}
+
+		if (!STp->pos_unknown) {
+
+			if (STps->eof == ST_FM_HIT) {
+				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
+                                    mtc.mt_op == MTEOM) {
+					mtc.mt_count -= 1;
+					if (STps->drv_file >= 0)
+						STps->drv_file += 1;
+				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
+					mtc.mt_count += 1;
+					if (STps->drv_file >= 0)
+						STps->drv_file += 1;
+				}
+			}
+
+			if (mtc.mt_op == MTSEEK) {
+				/* Old position must be restored if partition will be
+                                   changed */
+				i = !STp->can_partitions ||
+				    (STp->new_partition != STp->partition);
+			} else {
+				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
+				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
+				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
+				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
+				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
+				    mtc.mt_op == MTCOMPRESSION;
+			}
+			i = flush_buffer(STp, i);
+			if (i < 0) {
+				retval = i;
+				goto out;
+			}
+			if (STps->rw == ST_WRITING &&
+			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
+			     mtc.mt_op == MTSEEK ||
+			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
+				i = st_int_ioctl(STp, MTWEOF, 1);
+				if (i < 0) {
+					retval = i;
+					goto out;
+				}
+				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
+					mtc.mt_count++;
+				STps->rw = ST_IDLE;
+			     }
+
+		} else {
+			/*
+			 * If there was a bus reset, block further access
+			 * to this device.  If the user wants to rewind the tape,
+			 * then reset the flag and allow access again.
+			 */
+			if (mtc.mt_op != MTREW &&
+			    mtc.mt_op != MTOFFL &&
+			    mtc.mt_op != MTRETEN &&
+			    mtc.mt_op != MTERASE &&
+			    mtc.mt_op != MTSEEK &&
+			    mtc.mt_op != MTEOM) {
+				retval = (-EIO);
+				goto out;
+			}
+			reset_state(STp);
+			/* remove this when the midlevel properly clears was_reset */
+			STp->device->was_reset = 0;
+		}
+
+		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
+		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
+		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
+			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
+
+		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
+			do_door_lock(STp, 0);	/* Ignore result! */
+
+		if (mtc.mt_op == MTSETDRVBUFFER &&
+		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
+			retval = st_set_options(STp, mtc.mt_count);
+			goto out;
+		}
+
+		if (mtc.mt_op == MTSETPART) {
+			if (!STp->can_partitions ||
+			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
+				retval = (-EINVAL);
+				goto out;
+			}
+			if (mtc.mt_count >= STp->nbr_partitions &&
+			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
+				retval = (-EIO);
+				goto out;
+			}
+			if (mtc.mt_count >= STp->nbr_partitions) {
+				retval = (-EINVAL);
+				goto out;
+			}
+			STp->new_partition = mtc.mt_count;
+			retval = 0;
+			goto out;
+		}
+
+		if (mtc.mt_op == MTMKPART) {
+			if (!STp->can_partitions) {
+				retval = (-EINVAL);
+				goto out;
+			}
+			if ((i = st_int_ioctl(STp, MTREW, 0)) < 0 ||
+			    (i = partition_tape(STp, mtc.mt_count)) < 0) {
+				retval = i;
+				goto out;
+			}
+			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
+				STp->ps[i].rw = ST_IDLE;
+				STp->ps[i].at_sm = 0;
+				STp->ps[i].last_block_valid = 0;
+			}
+			STp->partition = STp->new_partition = 0;
+			STp->nbr_partitions = 1;	/* Bad guess ?-) */
+			STps->drv_block = STps->drv_file = 0;
+			retval = 0;
+			goto out;
+		}
+
+		if (mtc.mt_op == MTSEEK) {
+			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
+			if (!STp->can_partitions)
+				STp->ps[0].rw = ST_IDLE;
+			retval = i;
+			goto out;
+		}
+
+		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
+			retval = do_load_unload(STp, file, 0);
+			goto out;
+		}
+
+		if (mtc.mt_op == MTLOAD) {
+			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
+			goto out;
+		}
+
+		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
+			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
+			goto out;
+		}
+
+		if (STp->can_partitions && STp->ready == ST_READY &&
+		    (i = switch_partition(STp)) < 0) {
+			retval = i;
+			goto out;
+		}
+
+		if (mtc.mt_op == MTCOMPRESSION)
+			retval = st_compression(STp, (mtc.mt_count & 1));
+		else
+			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
+		goto out;
+	}
+	if (!STm->defined) {
+		retval = (-ENXIO);
+		goto out;
+	}
+
+	if ((i = flush_buffer(STp, 0)) < 0) {
+		retval = i;
+		goto out;
+	}
+	if (STp->can_partitions &&
+	    (i = switch_partition(STp)) < 0) {
+		retval = i;
+		goto out;
+	}
+
+	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
+		struct mtget mt_status;
+
+		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
+			 retval = (-EINVAL);
+			 goto out;
+		}
+
+		mt_status.mt_type = STp->tape_type;
+		mt_status.mt_dsreg =
+		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
+		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
+		mt_status.mt_blkno = STps->drv_block;
+		mt_status.mt_fileno = STps->drv_file;
+		if (STp->block_size != 0) {
+			if (STps->rw == ST_WRITING)
+				mt_status.mt_blkno +=
+				    (STp->buffer)->buffer_bytes / STp->block_size;
+			else if (STps->rw == ST_READING)
+				mt_status.mt_blkno -=
+                                        ((STp->buffer)->buffer_bytes +
+                                         STp->block_size - 1) / STp->block_size;
+		}
+
+		mt_status.mt_gstat = 0;
+		if (STp->drv_write_prot)
+			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
+		if (mt_status.mt_blkno == 0) {
+			if (mt_status.mt_fileno == 0)
+				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
+			else
+				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
+		}
+		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
+		mt_status.mt_resid = STp->partition;
+		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
+			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
+		else if (STps->eof >= ST_EOM_OK)
+			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
+		if (STp->density == 1)
+			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
+		else if (STp->density == 2)
+			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
+		else if (STp->density == 3)
+			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
+		if (STp->ready == ST_READY)
+			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
+		if (STp->ready == ST_NO_TAPE)
+			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
+		if (STps->at_sm)
+			mt_status.mt_gstat |= GMT_SM(0xffffffff);
+		if (STm->do_async_writes ||
+                    (STm->do_buffer_writes && STp->block_size != 0) ||
+		    STp->drv_buffer != 0)
+			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
+		if (STp->cleaning_req)
+			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
+
+		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
+		if (i) {
+			retval = (-EFAULT);
+			goto out;
+		}
+
+		STp->recover_reg = 0;		/* Clear after read */
+		retval = 0;
+		goto out;
+	}			/* End of MTIOCGET */
+	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
+		struct mtpos mt_pos;
+		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
+			 retval = (-EINVAL);
+			 goto out;
+		}
+		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
+			retval = i;
+			goto out;
+		}
+		mt_pos.mt_blkno = blk;
+		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
+		if (i)
+			retval = (-EFAULT);
+		goto out;
+	}
+	up(&STp->lock);
+	switch (cmd_in) {
+		case SCSI_IOCTL_GET_IDLUN:
+		case SCSI_IOCTL_GET_BUS_NUMBER:
+			break;
+		default:
+			if (!capable(CAP_SYS_ADMIN))
+				i = -EPERM;
+			else
+				i = scsi_cmd_ioctl(file, STp->disk, cmd_in, p);
+			if (i != -ENOTTY)
+				return i;
+			break;
+	}
+	if (!capable(CAP_SYS_ADMIN) &&
+	    (cmd_in == SCSI_IOCTL_START_UNIT || cmd_in == SCSI_IOCTL_STOP_UNIT))
+		return -EPERM;
+	return scsi_ioctl(STp->device, cmd_in, p);
+
+ out:
+	up(&STp->lock);
+	return retval;
+}
+
+#ifdef CONFIG_COMPAT
+static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct scsi_tape *STp = file->private_data;
+	struct scsi_device *sdev = STp->device;
+	int ret = -ENOIOCTLCMD;
+	if (sdev->host->hostt->compat_ioctl) { 
+
+		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
+
+	}
+	return ret;
+}
+#endif
+
+
+
+/* Try to allocate a new tape buffer. Calling function must not hold
+   dev_arr_lock. */
+static struct st_buffer *
+ new_tape_buffer(int from_initialization, int need_dma, int max_sg)
+{
+	int i, priority, got = 0, segs = 0;
+	struct st_buffer *tb;
+
+	if (from_initialization)
+		priority = GFP_ATOMIC;
+	else
+		priority = GFP_KERNEL;
+
+	i = sizeof(struct st_buffer) + (max_sg - 1) * sizeof(struct scatterlist) +
+		max_sg * sizeof(struct st_buf_fragment);
+	tb = kmalloc(i, priority);
+	if (!tb) {
+		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
+		return NULL;
+	}
+	memset(tb, 0, i);
+	tb->frp_segs = tb->orig_frp_segs = segs;
+	tb->use_sg = max_sg;
+	if (segs > 0)
+		tb->b_data = page_address(tb->sg[0].page);
+	tb->frp = (struct st_buf_fragment *)(&(tb->sg[0]) + max_sg);
+
+	tb->in_use = 1;
+	tb->dma = need_dma;
+	tb->buffer_size = got;
+
+	return tb;
+}
+
+
+/* Try to allocate enough space in the tape buffer */
+static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
+{
+	int segs, nbr, max_segs, b_size, priority, order, got;
+
+	if (new_size <= STbuffer->buffer_size)
+		return 1;
+
+	if (STbuffer->buffer_size <= PAGE_SIZE)
+		normalize_buffer(STbuffer);  /* Avoid extra segment */
+
+	max_segs = STbuffer->use_sg;
+	nbr = max_segs - STbuffer->frp_segs;
+	if (nbr <= 0)
+		return 0;
+
+	priority = GFP_KERNEL | __GFP_NOWARN;
+	if (need_dma)
+		priority |= GFP_DMA;
+	for (b_size = PAGE_SIZE, order=0;
+	     b_size < new_size - STbuffer->buffer_size;
+	     order++, b_size *= 2)
+		;  /* empty */
+
+	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
+	     segs < max_segs && got < new_size;) {
+		STbuffer->frp[segs].page = alloc_pages(priority, order);
+		if (STbuffer->frp[segs].page == NULL) {
+			if (new_size - got <= (max_segs - segs) * b_size / 2) {
+				b_size /= 2; /* Large enough for the rest of the buffers */
+				order--;
+				continue;
+			}
+			DEB(STbuffer->buffer_size = got);
+			normalize_buffer(STbuffer);
+			return 0;
+		}
+		STbuffer->frp[segs].length = b_size;
+		STbuffer->frp_segs += 1;
+		got += b_size;
+		STbuffer->buffer_size = got;
+		segs++;
+	}
+	STbuffer->b_data = page_address(STbuffer->frp[0].page);
+
+	return 1;
+}
+
+
+/* Release the extra buffer */
+static void normalize_buffer(struct st_buffer * STbuffer)
+{
+	int i, order;
+
+	for (i = STbuffer->orig_frp_segs; i < STbuffer->frp_segs; i++) {
+		order = get_order(STbuffer->frp[i].length);
+		__free_pages(STbuffer->frp[i].page, order);
+		STbuffer->buffer_size -= STbuffer->frp[i].length;
+	}
+	STbuffer->frp_segs = STbuffer->orig_frp_segs;
+	STbuffer->frp_sg_current = 0;
+}
+
+
+/* Move data from the user buffer to the tape buffer. Returns zero (success) or
+   negative error code. */
+static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
+{
+	int i, cnt, res, offset;
+
+	for (i = 0, offset = st_bp->buffer_bytes;
+	     i < st_bp->frp_segs && offset >= st_bp->frp[i].length; i++)
+		offset -= st_bp->frp[i].length;
+	if (i == st_bp->frp_segs) {	/* Should never happen */
+		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
+		return (-EIO);
+	}
+	for (; i < st_bp->frp_segs && do_count > 0; i++) {
+		cnt = st_bp->frp[i].length - offset < do_count ?
+		    st_bp->frp[i].length - offset : do_count;
+		res = copy_from_user(page_address(st_bp->frp[i].page) + offset, ubp, cnt);
+		if (res)
+			return (-EFAULT);
+		do_count -= cnt;
+		st_bp->buffer_bytes += cnt;
+		ubp += cnt;
+		offset = 0;
+	}
+	if (do_count) /* Should never happen */
+		return (-EIO);
+
+	return 0;
+}
+
+
+/* Move data from the tape buffer to the user buffer. Returns zero (success) or
+   negative error code. */
+static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
+{
+	int i, cnt, res, offset;
+
+	for (i = 0, offset = st_bp->read_pointer;
+	     i < st_bp->frp_segs && offset >= st_bp->frp[i].length; i++)
+		offset -= st_bp->frp[i].length;
+	if (i == st_bp->frp_segs) {	/* Should never happen */
+		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
+		return (-EIO);
+	}
+	for (; i < st_bp->frp_segs && do_count > 0; i++) {
+		cnt = st_bp->frp[i].length - offset < do_count ?
+		    st_bp->frp[i].length - offset : do_count;
+		res = copy_to_user(ubp, page_address(st_bp->frp[i].page) + offset, cnt);
+		if (res)
+			return (-EFAULT);
+		do_count -= cnt;
+		st_bp->buffer_bytes -= cnt;
+		st_bp->read_pointer += cnt;
+		ubp += cnt;
+		offset = 0;
+	}
+	if (do_count) /* Should never happen */
+		return (-EIO);
+
+	return 0;
+}
+
+
+/* Move data towards start of buffer */
+static void move_buffer_data(struct st_buffer * st_bp, int offset)
+{
+	int src_seg, dst_seg, src_offset = 0, dst_offset;
+	int count, total;
+
+	if (offset == 0)
+		return;
+
+	total=st_bp->buffer_bytes - offset;
+	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
+		src_offset = offset;
+		if (src_offset < st_bp->frp[src_seg].length)
+			break;
+		offset -= st_bp->frp[src_seg].length;
+	}
+
+	st_bp->buffer_bytes = st_bp->read_pointer = total;
+	for (dst_seg=dst_offset=0; total > 0; ) {
+		count = min(st_bp->frp[dst_seg].length - dst_offset,
+			    st_bp->frp[src_seg].length - src_offset);
+		memmove(page_address(st_bp->frp[dst_seg].page) + dst_offset,
+			page_address(st_bp->frp[src_seg].page) + src_offset, count);
+		src_offset += count;
+		if (src_offset >= st_bp->frp[src_seg].length) {
+			src_seg++;
+			src_offset = 0;
+		}
+		dst_offset += count;
+		if (dst_offset >= st_bp->frp[dst_seg].length) {
+			dst_seg++;
+			dst_offset = 0;
+		}
+		total -= count;
+	}
+}
+
+
+/* Fill the s/g list up to the length required for this transfer */
+static void buf_to_sg(struct st_buffer *STbp, unsigned int length)
+{
+	int i;
+	unsigned int count;
+	struct scatterlist *sg;
+	struct st_buf_fragment *frp;
+
+	if (length == STbp->frp_sg_current)
+		return;   /* work already done */
+
+	sg = &(STbp->sg[0]);
+	frp = STbp->frp;
+	for (i=count=0; count < length; i++) {
+		sg[i].page = frp[i].page;
+		if (length - count > frp[i].length)
+			sg[i].length = frp[i].length;
+		else
+			sg[i].length = length - count;
+		count += sg[i].length;
+		sg[i].offset = 0;
+	}
+	STbp->sg_segs = i;
+	STbp->frp_sg_current = length;
+}
+
+
+/* Validate the options from command line or module parameters */
+static void validate_options(void)
+{
+	if (buffer_kbs > 0)
+		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
+	if (max_sg_segs >= ST_FIRST_SG)
+		st_max_sg_segs = max_sg_segs;
+}
+
+#ifndef MODULE
+/* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
+ */
+static int __init st_setup(char *str)
+{
+	int i, len, ints[5];
+	char *stp;
+
+	stp = get_options(str, ARRAY_SIZE(ints), ints);
+
+	if (ints[0] > 0) {
+		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
+			if (parms[i].val)
+				*parms[i].val = ints[i + 1];
+	} else {
+		while (stp != NULL) {
+			for (i = 0; i < ARRAY_SIZE(parms); i++) {
+				len = strlen(parms[i].name);
+				if (!strncmp(stp, parms[i].name, len) &&
+				    (*(stp + len) == ':' || *(stp + len) == '=')) {
+					if (parms[i].val)
+						*parms[i].val =
+							simple_strtoul(stp + len + 1, NULL, 0);
+					else
+						printk(KERN_WARNING "st: Obsolete parameter %s\n",
+						       parms[i].name);
+					break;
+				}
+			}
+			if (i >= sizeof(parms) / sizeof(struct st_dev_parm))
+				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
+					stp);
+			stp = strchr(stp, ',');
+			if (stp)
+				stp++;
+		}
+	}
+
+	validate_options();
+
+	return 1;
+}
+
+__setup("st=", st_setup);
+
+#endif
+
+static struct file_operations st_fops =
+{
+	.owner =	THIS_MODULE,
+	.read =		st_read,
+	.write =	st_write,
+	.ioctl =	st_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = st_compat_ioctl,
+#endif
+	.open =		st_open,
+	.flush =	st_flush,
+	.release =	st_release,
+};
+
+static int st_probe(struct device *dev)
+{
+	struct scsi_device *SDp = to_scsi_device(dev);
+	struct gendisk *disk = NULL;
+	struct cdev *cdev = NULL;
+	struct scsi_tape *tpnt = NULL;
+	struct st_modedef *STm;
+	struct st_partstat *STps;
+	struct st_buffer *buffer;
+	int i, j, mode, dev_num, error;
+	char *stp;
+	u64 bounce_limit;
+
+	if (SDp->type != TYPE_TAPE)
+		return -ENODEV;
+	if ((stp = st_incompatible(SDp))) {
+		printk(KERN_INFO
+		       "st: Found incompatible tape at scsi%d, channel %d, id %d, lun %d\n",
+		       SDp->host->host_no, SDp->channel, SDp->id, SDp->lun);
+		printk(KERN_INFO "st: The suggested driver is %s.\n", stp);
+		return -ENODEV;
+	}
+
+	i = SDp->host->sg_tablesize;
+	if (st_max_sg_segs < i)
+		i = st_max_sg_segs;
+	buffer = new_tape_buffer(1, (SDp->host)->unchecked_isa_dma, i);
+	if (buffer == NULL) {
+		printk(KERN_ERR
+		       "st: Can't allocate new tape buffer. Device not attached.\n");
+		goto out;
+	}
+
+	disk = alloc_disk(1);
+	if (!disk) {
+		printk(KERN_ERR "st: out of memory. Device not attached.\n");
+		goto out_buffer_free;
+	}
+
+	write_lock(&st_dev_arr_lock);
+	if (st_nr_dev >= st_dev_max) {
+		struct scsi_tape **tmp_da;
+		int tmp_dev_max;
+
+		tmp_dev_max = max(st_nr_dev * 2, 8);
+		if (tmp_dev_max > ST_MAX_TAPES)
+			tmp_dev_max = ST_MAX_TAPES;
+		if (tmp_dev_max <= st_nr_dev) {
+			write_unlock(&st_dev_arr_lock);
+			printk(KERN_ERR "st: Too many tape devices (max. %d).\n",
+			       ST_MAX_TAPES);
+			goto out_put_disk;
+		}
+
+		tmp_da = kmalloc(tmp_dev_max * sizeof(struct scsi_tape *), GFP_ATOMIC);
+		if (tmp_da == NULL) {
+			write_unlock(&st_dev_arr_lock);
+			printk(KERN_ERR "st: Can't extend device array.\n");
+			goto out_put_disk;
+		}
+
+		memset(tmp_da, 0, tmp_dev_max * sizeof(struct scsi_tape *));
+		if (scsi_tapes != NULL) {
+			memcpy(tmp_da, scsi_tapes,
+			       st_dev_max * sizeof(struct scsi_tape *));
+			kfree(scsi_tapes);
+		}
+		scsi_tapes = tmp_da;
+
+		st_dev_max = tmp_dev_max;
+	}
+
+	for (i = 0; i < st_dev_max; i++)
+		if (scsi_tapes[i] == NULL)
+			break;
+	if (i >= st_dev_max)
+		panic("scsi_devices corrupt (st)");
+
+	tpnt = kmalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
+	if (tpnt == NULL) {
+		write_unlock(&st_dev_arr_lock);
+		printk(KERN_ERR "st: Can't allocate device descriptor.\n");
+		goto out_put_disk;
+	}
+	memset(tpnt, 0, sizeof(struct scsi_tape));
+	tpnt->disk = disk;
+	sprintf(disk->disk_name, "st%d", i);
+	disk->private_data = &tpnt->driver;
+	disk->queue = SDp->request_queue;
+	tpnt->driver = &st_template;
+	scsi_tapes[i] = tpnt;
+	dev_num = i;
+
+	tpnt->device = SDp;
+	if (SDp->scsi_level <= 2)
+		tpnt->tape_type = MT_ISSCSI1;
+	else
+		tpnt->tape_type = MT_ISSCSI2;
+
+	tpnt->buffer = buffer;
+
+	tpnt->inited = 0;
+	tpnt->dirty = 0;
+	tpnt->in_use = 0;
+	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
+	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
+	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
+	tpnt->density = 0;
+	tpnt->do_auto_lock = ST_AUTO_LOCK;
+	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
+	tpnt->can_partitions = 0;
+	tpnt->two_fm = ST_TWO_FM;
+	tpnt->fast_mteom = ST_FAST_MTEOM;
+	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
+	tpnt->immediate = ST_NOWAIT;
+	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
+	tpnt->partition = 0;
+	tpnt->new_partition = 0;
+	tpnt->nbr_partitions = 0;
+	tpnt->device->timeout = ST_TIMEOUT;
+	tpnt->long_timeout = ST_LONG_TIMEOUT;
+	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
+
+	bounce_limit = scsi_calculate_bounce_limit(SDp->host) >> PAGE_SHIFT;
+	if (bounce_limit > ULONG_MAX)
+		bounce_limit = ULONG_MAX;
+	tpnt->max_pfn = bounce_limit;
+
+	for (i = 0; i < ST_NBR_MODES; i++) {
+		STm = &(tpnt->modes[i]);
+		STm->defined = 0;
+		STm->sysv = ST_SYSV;
+		STm->defaults_for_writes = 0;
+		STm->do_async_writes = ST_ASYNC_WRITES;
+		STm->do_buffer_writes = ST_BUFFER_WRITES;
+		STm->do_read_ahead = ST_READ_AHEAD;
+		STm->default_compression = ST_DONT_TOUCH;
+		STm->default_blksize = (-1);	/* No forced size */
+		STm->default_density = (-1);	/* No forced density */
+	}
+
+	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
+		STps = &(tpnt->ps[i]);
+		STps->rw = ST_IDLE;
+		STps->eof = ST_NOEOF;
+		STps->at_sm = 0;
+		STps->last_block_valid = 0;
+		STps->drv_block = (-1);
+		STps->drv_file = (-1);
+	}
+
+	tpnt->current_mode = 0;
+	tpnt->modes[0].defined = 1;
+
+	tpnt->density_changed = tpnt->compression_changed =
+	    tpnt->blksize_changed = 0;
+	init_MUTEX(&tpnt->lock);
+
+	st_nr_dev++;
+	write_unlock(&st_dev_arr_lock);
+
+	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
+		STm = &(tpnt->modes[mode]);
+		for (j=0; j < 2; j++) {
+			cdev = cdev_alloc();
+			if (!cdev) {
+				printk(KERN_ERR
+				       "st%d: out of memory. Device not attached.\n",
+				       dev_num);
+				goto out_free_tape;
+			}
+			cdev->owner = THIS_MODULE;
+			cdev->ops = &st_fops;
+
+			error = cdev_add(cdev,
+					 MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, j)),
+					 1);
+			if (error) {
+				printk(KERN_ERR "st%d: Can't add %s-rewind mode %d\n",
+				       dev_num, j ? "non" : "auto", mode);
+				printk(KERN_ERR "st%d: Device not attached.\n", dev_num);
+				goto out_free_tape;
+			}
+			STm->cdevs[j] = cdev;
+
+		}
+		do_create_class_files(tpnt, dev_num, mode);
+	}
+
+	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
+		/* Make sure that the minor numbers corresponding to the four
+		   first modes always get the same names */
+		i = mode << (4 - ST_NBR_MODE_BITS);
+		/*  Rewind entry  */
+		devfs_mk_cdev(MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, 0)),
+			      S_IFCHR | S_IRUGO | S_IWUGO,
+			      "%s/mt%s", SDp->devfs_name, st_formats[i]);
+		/*  No-rewind entry  */
+		devfs_mk_cdev(MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, 1)),
+			      S_IFCHR | S_IRUGO | S_IWUGO,
+			      "%s/mt%sn", SDp->devfs_name, st_formats[i]);
+	}
+	disk->number = devfs_register_tape(SDp->devfs_name);
+
+	printk(KERN_WARNING
+	"Attached scsi tape %s at scsi%d, channel %d, id %d, lun %d\n",
+	       tape_name(tpnt), SDp->host->host_no, SDp->channel, SDp->id, SDp->lun);
+	printk(KERN_WARNING "%s: try direct i/o: %s (alignment %d B), max page reachable by HBA %lu\n",
+	       tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
+	       queue_dma_alignment(SDp->request_queue) + 1, tpnt->max_pfn);
+
+	return 0;
+
+out_free_tape:
+	for (mode=0; mode < ST_NBR_MODES; mode++) {
+		STm = &(tpnt->modes[mode]);
+		sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
+				  "tape");
+		for (j=0; j < 2; j++) {
+			if (STm->cdevs[j]) {
+				if (cdev == STm->cdevs[j])
+					cdev = NULL;
+				class_simple_device_remove(MKDEV(SCSI_TAPE_MAJOR,
+								 TAPE_MINOR(i, mode, j)));
+				cdev_del(STm->cdevs[j]);
+			}
+		}
+	}
+	if (cdev)
+		cdev_del(cdev);
+	write_lock(&st_dev_arr_lock);
+	scsi_tapes[dev_num] = NULL;
+	st_nr_dev--;
+	write_unlock(&st_dev_arr_lock);
+out_put_disk:
+	put_disk(disk);
+	if (tpnt)
+		kfree(tpnt);
+out_buffer_free:
+	kfree(buffer);
+out:
+	return -ENODEV;
+};
+
+
+static int st_remove(struct device *dev)
+{
+	struct scsi_device *SDp = to_scsi_device(dev);
+	struct scsi_tape *tpnt;
+	int i, j, mode;
+
+	write_lock(&st_dev_arr_lock);
+	for (i = 0; i < st_dev_max; i++) {
+		tpnt = scsi_tapes[i];
+		if (tpnt != NULL && tpnt->device == SDp) {
+			scsi_tapes[i] = NULL;
+			st_nr_dev--;
+			write_unlock(&st_dev_arr_lock);
+			devfs_unregister_tape(tpnt->disk->number);
+			sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
+					  "tape");
+			for (mode = 0; mode < ST_NBR_MODES; ++mode) {
+				j = mode << (4 - ST_NBR_MODE_BITS);
+				devfs_remove("%s/mt%s", SDp->devfs_name, st_formats[j]);
+				devfs_remove("%s/mt%sn", SDp->devfs_name, st_formats[j]);
+				for (j=0; j < 2; j++) {
+					class_simple_device_remove(MKDEV(SCSI_TAPE_MAJOR,
+									 TAPE_MINOR(i, mode, j)));
+					cdev_del(tpnt->modes[mode].cdevs[j]);
+					tpnt->modes[mode].cdevs[j] = NULL;
+				}
+			}
+			tpnt->device = NULL;
+
+			if (tpnt->buffer) {
+				tpnt->buffer->orig_frp_segs = 0;
+				normalize_buffer(tpnt->buffer);
+				kfree(tpnt->buffer);
+			}
+			put_disk(tpnt->disk);
+			kfree(tpnt);
+			return 0;
+		}
+	}
+
+	write_unlock(&st_dev_arr_lock);
+	return 0;
+}
+
+static void st_intr(struct scsi_cmnd *SCpnt)
+{
+	scsi_io_completion(SCpnt, (SCpnt->result ? 0: SCpnt->bufflen), 1);
+}
+
+/*
+ * st_init_command: only called via the scsi_cmd_ioctl (block SG_IO)
+ * interface for REQ_BLOCK_PC commands.
+ */
+static int st_init_command(struct scsi_cmnd *SCpnt)
+{
+	struct request *rq;
+
+	if (!(SCpnt->request->flags & REQ_BLOCK_PC))
+		return 0;
+
+	rq = SCpnt->request;
+	if (sizeof(rq->cmd) > sizeof(SCpnt->cmnd))
+		return 0;
+
+	memcpy(SCpnt->cmnd, rq->cmd, sizeof(SCpnt->cmnd));
+
+	if (rq_data_dir(rq) == WRITE)
+		SCpnt->sc_data_direction = DMA_TO_DEVICE;
+	else if (rq->data_len)
+		SCpnt->sc_data_direction = DMA_FROM_DEVICE;
+	else
+		SCpnt->sc_data_direction = DMA_NONE;
+
+	SCpnt->timeout_per_command = rq->timeout;
+	SCpnt->transfersize = rq->data_len;
+	SCpnt->done = st_intr;
+	return 1;
+}
+
+static int __init init_st(void)
+{
+	validate_options();
+
+	printk(KERN_INFO
+		"st: Version %s, fixed bufsize %d, s/g segs %d\n",
+		verstr, st_fixed_buffer_size, st_max_sg_segs);
+
+	st_sysfs_class = class_simple_create(THIS_MODULE, "scsi_tape");
+	if (IS_ERR(st_sysfs_class)) {
+		st_sysfs_class = NULL;
+		printk(KERN_ERR "Unable create sysfs class for SCSI tapes\n");
+		return 1;
+	}
+
+	if (!register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
+				    ST_MAX_TAPE_ENTRIES, "st")) {
+		if (scsi_register_driver(&st_template.gendrv) == 0) {
+			do_create_driverfs_files();
+			return 0;
+		}
+		if (st_sysfs_class)
+			class_simple_destroy(st_sysfs_class);		
+		unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
+
+					 ST_MAX_TAPE_ENTRIES);
+	}
+
+	printk(KERN_ERR "Unable to get major %d for SCSI tapes\n", SCSI_TAPE_MAJOR);
+	return 1;
+}
+
+static void __exit exit_st(void)
+{
+	if (st_sysfs_class)
+		class_simple_destroy(st_sysfs_class);
+	st_sysfs_class = NULL;
+	do_remove_driverfs_files();
+	scsi_unregister_driver(&st_template.gendrv);
+	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
+				 ST_MAX_TAPE_ENTRIES);
+	kfree(scsi_tapes);
+	printk(KERN_INFO "st: Unloaded.\n");
+}
+
+module_init(init_st);
+module_exit(exit_st);
+
+
+/* The sysfs driver interface. Read-only at the moment */
+static ssize_t st_try_direct_io_show(struct device_driver *ddp, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
+}
+static DRIVER_ATTR(try_direct_io, S_IRUGO, st_try_direct_io_show, NULL);
+
+static ssize_t st_fixed_buffer_size_show(struct device_driver *ddp, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
+}
+static DRIVER_ATTR(fixed_buffer_size, S_IRUGO, st_fixed_buffer_size_show, NULL);
+
+static ssize_t st_max_sg_segs_show(struct device_driver *ddp, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
+}
+static DRIVER_ATTR(max_sg_segs, S_IRUGO, st_max_sg_segs_show, NULL);
+
+static ssize_t st_version_show(struct device_driver *ddd, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
+}
+static DRIVER_ATTR(version, S_IRUGO, st_version_show, NULL);
+
+static void do_create_driverfs_files(void)
+{
+	struct device_driver *driverfs = &st_template.gendrv;
+
+	driver_create_file(driverfs, &driver_attr_try_direct_io);
+	driver_create_file(driverfs, &driver_attr_fixed_buffer_size);
+	driver_create_file(driverfs, &driver_attr_max_sg_segs);
+	driver_create_file(driverfs, &driver_attr_version);
+}
+
+static void do_remove_driverfs_files(void)
+{
+	struct device_driver *driverfs = &st_template.gendrv;
+
+	driver_remove_file(driverfs, &driver_attr_version);
+	driver_remove_file(driverfs, &driver_attr_max_sg_segs);
+	driver_remove_file(driverfs, &driver_attr_fixed_buffer_size);
+	driver_remove_file(driverfs, &driver_attr_try_direct_io);
+}
+
+
+/* The sysfs simple class interface */
+static ssize_t st_defined_show(struct class_device *class_dev, char *buf)
+{
+	struct st_modedef *STm = (struct st_modedef *)class_get_devdata(class_dev);
+	ssize_t l = 0;
+
+	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
+	return l;
+}
+
+CLASS_DEVICE_ATTR(defined, S_IRUGO, st_defined_show, NULL);
+
+static ssize_t st_defblk_show(struct class_device *class_dev, char *buf)
+{
+	struct st_modedef *STm = (struct st_modedef *)class_get_devdata(class_dev);
+	ssize_t l = 0;
+
+	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
+	return l;
+}
+
+CLASS_DEVICE_ATTR(default_blksize, S_IRUGO, st_defblk_show, NULL);
+
+static ssize_t st_defdensity_show(struct class_device *class_dev, char *buf)
+{
+	struct st_modedef *STm = (struct st_modedef *)class_get_devdata(class_dev);
+	ssize_t l = 0;
+	char *fmt;
+
+	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
+	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
+	return l;
+}
+
+CLASS_DEVICE_ATTR(default_density, S_IRUGO, st_defdensity_show, NULL);
+
+static ssize_t st_defcompression_show(struct class_device *class_dev, char *buf)
+{
+	struct st_modedef *STm = (struct st_modedef *)class_get_devdata(class_dev);
+	ssize_t l = 0;
+
+	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
+	return l;
+}
+
+CLASS_DEVICE_ATTR(default_compression, S_IRUGO, st_defcompression_show, NULL);
+
+static void do_create_class_files(struct scsi_tape *STp, int dev_num, int mode)
+{
+	int i, rew, error;
+	char name[10];
+	struct class_device *st_class_member;
+
+	if (!st_sysfs_class)
+		return;
+
+	for (rew=0; rew < 2; rew++) {
+		/* Make sure that the minor numbers corresponding to the four
+		   first modes always get the same names */
+		i = mode << (4 - ST_NBR_MODE_BITS);
+		snprintf(name, 10, "%s%s%s", rew ? "n" : "",
+			 STp->disk->disk_name, st_formats[i]);
+		st_class_member =
+			class_simple_device_add(st_sysfs_class,
+						MKDEV(SCSI_TAPE_MAJOR,
+						      TAPE_MINOR(dev_num, mode, rew)),
+						&STp->device->sdev_gendev, "%s", name);
+		if (IS_ERR(st_class_member)) {
+			printk(KERN_WARNING "st%d: class_simple_device_add failed\n",
+			       dev_num);
+			goto out;
+		}
+		class_set_devdata(st_class_member, &STp->modes[mode]);
+
+		class_device_create_file(st_class_member,
+					 &class_device_attr_defined);
+		class_device_create_file(st_class_member,
+					 &class_device_attr_default_blksize);
+		class_device_create_file(st_class_member,
+					 &class_device_attr_default_density);
+		class_device_create_file(st_class_member,
+					 &class_device_attr_default_compression);
+		if (mode == 0 && rew == 0) {
+			error = sysfs_create_link(&STp->device->sdev_gendev.kobj,
+						  &st_class_member->kobj,
+						  "tape");
+			if (error) {
+				printk(KERN_ERR
+				       "st%d: Can't create sysfs link from SCSI device.\n",
+				       dev_num);
+			}
+		}
+	}
+ out:
+	return;
+}
+
+
+/* Pin down user pages and put them into a scatter gather list. Returns <= 0 if
+   - mapping of all pages not successful
+   - any page is above max_pfn
+   (i.e., either completely successful or fails)
+*/
+static int st_map_user_pages(struct scatterlist *sgl, const unsigned int max_pages, 
+			     unsigned long uaddr, size_t count, int rw,
+			     unsigned long max_pfn)
+{
+	int i, nr_pages;
+
+	nr_pages = sgl_map_user_pages(sgl, max_pages, uaddr, count, rw);
+	if (nr_pages <= 0)
+		return nr_pages;
+
+	for (i=0; i < nr_pages; i++) {
+		if (page_to_pfn(sgl[i].page) > max_pfn)
+			goto out_unmap;
+	}
+	return nr_pages;
+
+ out_unmap:
+	sgl_unmap_user_pages(sgl, nr_pages, 0);
+	return 0;
+}
+
+
+/* The following functions may be useful for a larger audience. */
+static int sgl_map_user_pages(struct scatterlist *sgl, const unsigned int max_pages, 
+			      unsigned long uaddr, size_t count, int rw)
+{
+	int res, i, j;
+	unsigned int nr_pages;
+	struct page **pages;
+
+	nr_pages = ((uaddr & ~PAGE_MASK) + count + ~PAGE_MASK) >> PAGE_SHIFT;
+
+	/* User attempted Overflow! */
+	if ((uaddr + count) < uaddr)
+		return -EINVAL;
+
+	/* Too big */
+        if (nr_pages > max_pages)
+		return -ENOMEM;
+
+	/* Hmm? */
+	if (count == 0)
+		return 0;
+
+	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
+		return -ENOMEM;
+
+        /* Try to fault in all of the necessary pages */
+	down_read(&current->mm->mmap_sem);
+        /* rw==READ means read from drive, write into memory area */
+	res = get_user_pages(
+		current,
+		current->mm,
+		uaddr,
+		nr_pages,
+		rw == READ,
+		0, /* don't force */
+		pages,
+		NULL);
+	up_read(&current->mm->mmap_sem);
+
+	/* Errors and no page mapped should return here */
+	if (res < nr_pages)
+		goto out_unmap;
+
+        for (i=0; i < nr_pages; i++) {
+                /* FIXME: flush superflous for rw==READ,
+                 * probably wrong function for rw==WRITE
+                 */
+		flush_dcache_page(pages[i]);
+        }
+
+	/* Populate the scatter/gather list */
+	sgl[0].page = pages[0]; 
+	sgl[0].offset = uaddr & ~PAGE_MASK;
+	if (nr_pages > 1) {
+		sgl[0].length = PAGE_SIZE - sgl[0].offset;
+		count -= sgl[0].length;
+		for (i=1; i < nr_pages ; i++) {
+			sgl[i].offset = 0;
+			sgl[i].page = pages[i]; 
+			sgl[i].length = count < PAGE_SIZE ? count : PAGE_SIZE;
+			count -= PAGE_SIZE;
+		}
+	}
+	else {
+		sgl[0].length = count;
+	}
+
+	kfree(pages);
+	return nr_pages;
+
+ out_unmap:
+	if (res > 0) {
+		for (j=0; j < res; j++)
+			page_cache_release(pages[j]);
+	}
+	kfree(pages);
+	return res;
+}
+
+
+/* And unmap them... */
+static int sgl_unmap_user_pages(struct scatterlist *sgl, const unsigned int nr_pages,
+				int dirtied)
+{
+	int i;
+
+	for (i=0; i < nr_pages; i++) {
+		if (dirtied && !PageReserved(sgl[i].page))
+			SetPageDirty(sgl[i].page);
+		/* FIXME: cache flush missing for rw==READ
+		 * FIXME: call the correct reference counting function
+		 */
+		page_cache_release(sgl[i].page);
+	}
+
+	return 0;
+}