/*
  SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
  file Documentation/scsi/st.txt for more information.

  History:

  OnStream SCSI Tape support (osst) cloned from st.c by
  Willem Riede (osst@riede.org) Feb 2000
  Fixes ... Kurt Garloff <garloff@suse.de> Mar 2000

  Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
  Contribution and ideas from several people including (in alphabetical
  order) Klaus Ehrenfried, Wolfgang Denk, Steve Hirsch, Andreas Koppenh"ofer,
  Michael Leodolter, Eyal Lebedinsky, J"org Weule, and Eric Youngdale.

  Copyright 1992 - 2002 Kai Makisara / 2000 - 2006 Willem Riede
	 email osst@riede.org

  $Header: /cvsroot/osst/Driver/osst.c,v 1.73 2005/01/01 21:13:34 wriede Exp $

  Microscopic alterations - Rik Ling, 2000/12/21
  Last st.c sync: Tue Oct 15 22:01:04 2002 by makisara
  Some small formal changes - aeb, 950809
*/

static const char * cvsid = "$Id: osst.c,v 1.73 2005/01/01 21:13:34 wriede Exp $";
static const char * osst_version = "0.99.4";

/* The "failure to reconnect" firmware bug */
#define OSST_FW_NEED_POLL_MIN 10601 /*(107A)*/
#define OSST_FW_NEED_POLL_MAX 10704 /*(108D)*/
#define OSST_FW_NEED_POLL(x,d) ((x) >= OSST_FW_NEED_POLL_MIN && (x) <= OSST_FW_NEED_POLL_MAX && d->host->this_id != 7)

#include <linux/module.h>

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/mm.h>
#include <linux/slab.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/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <asm/dma.h>

/* The driver prints some debugging information on the console if DEBUG
   is defined and non-zero. */
#define DEBUG 0

/* 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 OSST_DEB_MSG  KERN_NOTICE

#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>

#define ST_KILOBYTE 1024

#include "st.h"
#include "osst.h"
#include "osst_options.h"
#include "osst_detect.h"

static DEFINE_MUTEX(osst_int_mutex);
static int max_dev = 0;
static int write_threshold_kbs = 0;
static int max_sg_segs = 0;

#ifdef MODULE
MODULE_AUTHOR("Willem Riede");
MODULE_DESCRIPTION("OnStream {DI-|FW-|SC-|USB}{30|50} Tape Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(OSST_MAJOR);
MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);

module_param(max_dev, int, 0444);
MODULE_PARM_DESC(max_dev, "Maximum number of OnStream Tape Drives to attach (4)");

module_param(write_threshold_kbs, int, 0644);
MODULE_PARM_DESC(write_threshold_kbs, "Asynchronous write threshold (KB; 32)");

module_param(max_sg_segs, int, 0644);
MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (9)");
#else
static struct osst_dev_parm {
       char   *name;
       int    *val;
} parms[] __initdata = {
       { "max_dev",             &max_dev             },
       { "write_threshold_kbs", &write_threshold_kbs },
       { "max_sg_segs",         &max_sg_segs         }
};
#endif

/* Some default definitions have been moved to osst_options.h */
#define OSST_BUFFER_SIZE (OSST_BUFFER_BLOCKS * ST_KILOBYTE)
#define OSST_WRITE_THRESHOLD (OSST_WRITE_THRESHOLD_BLOCKS * ST_KILOBYTE)

/* The buffer size should fit into the 24 bits for length in the
   6-byte SCSI read and write commands. */
#if OSST_BUFFER_SIZE >= (2 << 24 - 1)
#error "Buffer size should not exceed (2 << 24 - 1) bytes!"
#endif

#if DEBUG
static int debugging = 1;
/* uncomment define below to test error recovery */
// #define OSST_INJECT_ERRORS 1 
#endif

/* Do not retry! The drive firmware already retries when appropriate,
   and when it tries to tell us something, we had better listen... */
#define MAX_RETRIES 0

#define NO_TAPE  NOT_READY

#define OSST_WAIT_POSITION_COMPLETE   (HZ > 200 ? HZ / 200 : 1)
#define OSST_WAIT_WRITE_COMPLETE      (HZ / 12)
#define OSST_WAIT_LONG_WRITE_COMPLETE (HZ / 2)
	
#define OSST_TIMEOUT (200 * HZ)
#define OSST_LONG_TIMEOUT (1800 * HZ)

#define TAPE_NR(x) (iminor(x) & ~(-1 << ST_MODE_SHIFT))
#define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
#define TAPE_REWIND(x) ((iminor(x) & 0x80) == 0)
#define TAPE_IS_RAW(x) (TAPE_MODE(x) & (ST_NBR_MODES >> 1))

/* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
   24 bits) */
#define SET_DENS_AND_BLK 0x10001

static int osst_buffer_size       = OSST_BUFFER_SIZE;
static int osst_write_threshold   = OSST_WRITE_THRESHOLD;
static int osst_max_sg_segs       = OSST_MAX_SG;
static int osst_max_dev           = OSST_MAX_TAPES;
static int osst_nr_dev;

static struct osst_tape **os_scsi_tapes = NULL;
static DEFINE_RWLOCK(os_scsi_tapes_lock);

static int modes_defined = 0;

static struct osst_buffer *new_tape_buffer(int, int, int);
static int enlarge_buffer(struct osst_buffer *, int);
static void normalize_buffer(struct osst_buffer *);
static int append_to_buffer(const char __user *, struct osst_buffer *, int);
static int from_buffer(struct osst_buffer *, char __user *, int);
static int osst_zero_buffer_tail(struct osst_buffer *);
static int osst_copy_to_buffer(struct osst_buffer *, unsigned char *);
static int osst_copy_from_buffer(struct osst_buffer *, unsigned char *);

static int osst_probe(struct device *);
static int osst_remove(struct device *);

static struct scsi_driver osst_template = {
	.gendrv = {
		.name		=  "osst",
		.owner		= THIS_MODULE,
		.probe		= osst_probe,
		.remove		= osst_remove,
	}
};

static int osst_int_ioctl(struct osst_tape *STp, struct osst_request ** aSRpnt,
			    unsigned int cmd_in, unsigned long arg);

static int osst_set_frame_position(struct osst_tape *STp, struct osst_request ** aSRpnt, int frame, int skip);

static int osst_get_frame_position(struct osst_tape *STp, struct osst_request ** aSRpnt);

static int osst_flush_write_buffer(struct osst_tape *STp, struct osst_request ** aSRpnt);

static int osst_write_error_recovery(struct osst_tape * STp, struct osst_request ** aSRpnt, int pending);

static inline char *tape_name(struct osst_tape *tape)
{
	return tape->drive->disk_name;
}

/* Routines that handle the interaction with mid-layer SCSI routines */


/* Normalize Sense */
static void osst_analyze_sense(struct osst_request *SRpnt, struct st_cmdstatus *s)
{
	const u8 *ucp;
	const u8 *sense = SRpnt->sense;

	s->have_sense = scsi_normalize_sense(SRpnt->sense,
				SCSI_SENSE_BUFFERSIZE, &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 osst_chk_result(struct osst_tape * STp, struct osst_request * SRpnt)
{
	char *name = tape_name(STp);
	int result = SRpnt->result;
	u8 * sense = SRpnt->sense, scode;
#if DEBUG
	const char *stp;
#endif
	struct st_cmdstatus *cmdstatp;

	if (!result)
		return 0;

	cmdstatp = &STp->buffer->cmdstat;
	osst_analyze_sense(SRpnt, cmdstatp);

	if (cmdstatp->have_sense)
		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
	else
		scode = 0;
#if DEBUG
	if (debugging) {
		printk(OSST_DEB_MSG "%s:D: Error: %x, cmd: %x %x %x %x %x %x\n",
		   name, result,
		   SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
		   SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
		if (scode) printk(OSST_DEB_MSG "%s:D: Sense: %02x, ASC: %02x, ASCQ: %02x\n",
				  name, scode, sense[12], sense[13]);
		if (cmdstatp->have_sense)
			__scsi_print_sense(STp->device, name,
					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
	}
	else
#endif
	if (cmdstatp->have_sense && (
		 scode != NO_SENSE &&
		 scode != RECOVERED_ERROR &&
/*      	 scode != UNIT_ATTENTION && */
		 scode != BLANK_CHECK &&
		 scode != VOLUME_OVERFLOW &&
		 SRpnt->cmd[0] != MODE_SENSE &&
		 SRpnt->cmd[0] != TEST_UNIT_READY)) { /* Abnormal conditions for tape */
		if (cmdstatp->have_sense) {
			printk(KERN_WARNING "%s:W: Command with sense data:\n", name);
			__scsi_print_sense(STp->device, name,
					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
		}
		else {
			static	int	notyetprinted = 1;

			printk(KERN_WARNING
			     "%s:W: Warning %x (driver bt 0x%x, host bt 0x%x).\n",
			     name, result, driver_byte(result),
			     host_byte(result));
			if (notyetprinted) {
				notyetprinted = 0;
				printk(KERN_INFO
					"%s:I: This warning may be caused by your scsi controller,\n", name);
				printk(KERN_INFO
					"%s:I: it has been reported with some Buslogic cards.\n", name);
			}
		}
	}
	STp->pos_unknown |= STp->device->was_reset;

	if (cmdstatp->have_sense && scode == RECOVERED_ERROR) {
		STp->recover_count++;
		STp->recover_erreg++;
#if DEBUG
		if (debugging) {
			if (SRpnt->cmd[0] == READ_6)
				stp = "read";
			else if (SRpnt->cmd[0] == WRITE_6)
				stp = "write";
			else
				stp = "ioctl";
			printk(OSST_DEB_MSG "%s:D: Recovered %s error (%d).\n", name, stp,
					     STp->recover_count);
		}
#endif
		if ((sense[2] & 0xe0) == 0)
			return 0;
	}
	return (-EIO);
}


/* Wakeup from interrupt */
static void osst_end_async(struct request *req, int update)
{
	struct osst_request *SRpnt = req->end_io_data;
	struct osst_tape *STp = SRpnt->stp;
	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;

	STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors;
#if DEBUG
	STp->write_pending = 0;
#endif
	if (SRpnt->waiting)
		complete(SRpnt->waiting);

	if (SRpnt->bio) {
		kfree(mdata->pages);
		blk_rq_unmap_user(SRpnt->bio);
	}

	__blk_put_request(req->q, req);
}

/* osst_request memory management */
static struct osst_request *osst_allocate_request(void)
{
	return kzalloc(sizeof(struct osst_request), GFP_KERNEL);
}

static void osst_release_request(struct osst_request *streq)
{
	kfree(streq);
}

static int osst_execute(struct osst_request *SRpnt, const unsigned char *cmd,
			int cmd_len, int data_direction, void *buffer, unsigned bufflen,
			int use_sg, int timeout, int retries)
{
	struct request *req;
	struct page **pages = NULL;
	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;

	int err = 0;
	int write = (data_direction == DMA_TO_DEVICE);

	req = blk_get_request(SRpnt->stp->device->request_queue, write, GFP_KERNEL);
	if (IS_ERR(req))
		return DRIVER_ERROR << 24;

	blk_rq_set_block_pc(req);
	req->cmd_flags |= REQ_QUIET;

	SRpnt->bio = NULL;

	if (use_sg) {
		struct scatterlist *sg, *sgl = (struct scatterlist *)buffer;
		int i;

		pages = kzalloc(use_sg * sizeof(struct page *), GFP_KERNEL);
		if (!pages)
			goto free_req;

		for_each_sg(sgl, sg, use_sg, i)
			pages[i] = sg_page(sg);

		mdata->null_mapped = 1;

		mdata->page_order = get_order(sgl[0].length);
		mdata->nr_entries =
			DIV_ROUND_UP(bufflen, PAGE_SIZE << mdata->page_order);
		mdata->offset = 0;

		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen, GFP_KERNEL);
		if (err) {
			kfree(pages);
			goto free_req;
		}
		SRpnt->bio = req->bio;
		mdata->pages = pages;

	} else if (bufflen) {
		err = blk_rq_map_kern(req->q, req, buffer, bufflen, GFP_KERNEL);
		if (err)
			goto free_req;
	}

	req->cmd_len = cmd_len;
	memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
	memcpy(req->cmd, cmd, req->cmd_len);
	req->sense = SRpnt->sense;
	req->sense_len = 0;
	req->timeout = timeout;
	req->retries = retries;
	req->end_io_data = SRpnt;

	blk_execute_rq_nowait(req->q, NULL, req, 1, osst_end_async);
	return 0;
free_req:
	blk_put_request(req);
	return DRIVER_ERROR << 24;
}

/* Do the scsi command. Waits until command performed if do_wait is true.
   Otherwise osst_write_behind_check() is used to check that the command
   has finished. */
static	struct osst_request * osst_do_scsi(struct osst_request *SRpnt, struct osst_tape *STp, 
	unsigned char *cmd, int bytes, int direction, int timeout, int retries, int do_wait)
{
	unsigned char *bp;
	unsigned short use_sg;
#ifdef OSST_INJECT_ERRORS
	static   int   inject = 0;
	static   int   repeat = 0;
#endif
	struct completion *waiting;

	/* if async, make sure there's no command outstanding */
	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
		printk(KERN_ERR "%s: Async command already active.\n",
		       tape_name(STp));
		if (signal_pending(current))
			(STp->buffer)->syscall_result = (-EINTR);
		else
			(STp->buffer)->syscall_result = (-EBUSY);
		return NULL;
	}

	if (SRpnt == NULL) {
		SRpnt = osst_allocate_request();
		if (SRpnt == NULL) {
			printk(KERN_ERR "%s: Can't allocate SCSI request.\n",
				     tape_name(STp));
			if (signal_pending(current))
				(STp->buffer)->syscall_result = (-EINTR);
			else
				(STp->buffer)->syscall_result = (-EBUSY);
			return NULL;
		}
		SRpnt->stp = STp;
	}

	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
	   which IO is outstanding. It's nulled out when the IO completes. */
	if (!do_wait)
		(STp->buffer)->last_SRpnt = SRpnt;

	waiting = &STp->wait;
	init_completion(waiting);
	SRpnt->waiting = waiting;

	use_sg = (bytes > STp->buffer->sg[0].length) ? STp->buffer->use_sg : 0;
	if (use_sg) {
		bp = (char *)&(STp->buffer->sg[0]);
		if (STp->buffer->sg_segs < use_sg)
			use_sg = STp->buffer->sg_segs;
	}
	else
		bp = (STp->buffer)->b_data;

	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
	STp->buffer->cmdstat.have_sense = 0;
	STp->buffer->syscall_result = 0;

	if (osst_execute(SRpnt, cmd, COMMAND_SIZE(cmd[0]), direction, bp, bytes,
			 use_sg, timeout, retries))
		/* could not allocate the buffer or request was too large */
		(STp->buffer)->syscall_result = (-EBUSY);
	else if (do_wait) {
		wait_for_completion(waiting);
		SRpnt->waiting = NULL;
		STp->buffer->syscall_result = osst_chk_result(STp, SRpnt);
#ifdef OSST_INJECT_ERRORS
		if (STp->buffer->syscall_result == 0 &&
		    cmd[0] == READ_6 &&
		    cmd[4] && 
		    ( (++ inject % 83) == 29  ||
		      (STp->first_frame_position == 240 
			         /* or STp->read_error_frame to fail again on the block calculated above */ &&
				 ++repeat < 3))) {
			printk(OSST_DEB_MSG "%s:D: Injecting read error\n", tape_name(STp));
			STp->buffer->last_result_fatal = 1;
		}
#endif
	}
	return SRpnt;
}


/* Handle the write-behind checking (downs the semaphore) */
static void osst_write_behind_check(struct osst_tape *STp)
{
	struct osst_buffer * STbuffer;

	STbuffer = STp->buffer;

#if DEBUG
	if (STp->write_pending)
		STp->nbr_waits++;
	else
		STp->nbr_finished++;
#endif
	wait_for_completion(&(STp->wait));
	STp->buffer->last_SRpnt->waiting = NULL;

	STp->buffer->syscall_result = osst_chk_result(STp, STp->buffer->last_SRpnt);

	if (STp->buffer->syscall_result)
		STp->buffer->syscall_result =
			osst_write_error_recovery(STp, &(STp->buffer->last_SRpnt), 1);
	else
		STp->first_frame_position++;

	osst_release_request(STp->buffer->last_SRpnt);

	if (STbuffer->writing < STbuffer->buffer_bytes)
		printk(KERN_WARNING "osst :A: write_behind_check: something left in buffer!\n");

	STbuffer->last_SRpnt = NULL;
	STbuffer->buffer_bytes -= STbuffer->writing;
	STbuffer->writing = 0;

	return;
}



/* Onstream specific Routines */
/*
 * Initialize the OnStream AUX
 */
static void osst_init_aux(struct osst_tape * STp, int frame_type, int frame_seq_number,
					 int logical_blk_num, int blk_sz, int blk_cnt)
{
	os_aux_t       *aux = STp->buffer->aux;
	os_partition_t *par = &aux->partition;
	os_dat_t       *dat = &aux->dat;

	if (STp->raw) return;

	memset(aux, 0, sizeof(*aux));
	aux->format_id = htonl(0);
	memcpy(aux->application_sig, "LIN4", 4);
	aux->hdwr = htonl(0);
	aux->frame_type = frame_type;

	switch (frame_type) {
	  case	OS_FRAME_TYPE_HEADER:
		aux->update_frame_cntr    = htonl(STp->update_frame_cntr);
		par->partition_num        = OS_CONFIG_PARTITION;
		par->par_desc_ver         = OS_PARTITION_VERSION;
		par->wrt_pass_cntr        = htons(0xffff);
		/* 0-4 = reserved, 5-9 = header, 2990-2994 = header, 2995-2999 = reserved */
		par->first_frame_ppos     = htonl(0);
		par->last_frame_ppos      = htonl(0xbb7);
		aux->frame_seq_num        = htonl(0);
		aux->logical_blk_num_high = htonl(0);
		aux->logical_blk_num      = htonl(0);
		aux->next_mark_ppos       = htonl(STp->first_mark_ppos);
		break;
	  case	OS_FRAME_TYPE_DATA:
	  case	OS_FRAME_TYPE_MARKER:
		dat->dat_sz = 8;
		dat->reserved1 = 0;
		dat->entry_cnt = 1;
		dat->reserved3 = 0;
		dat->dat_list[0].blk_sz   = htonl(blk_sz);
		dat->dat_list[0].blk_cnt  = htons(blk_cnt);
		dat->dat_list[0].flags    = frame_type==OS_FRAME_TYPE_MARKER?
							OS_DAT_FLAGS_MARK:OS_DAT_FLAGS_DATA;
		dat->dat_list[0].reserved = 0;
	  case	OS_FRAME_TYPE_EOD:
		aux->update_frame_cntr    = htonl(0);
		par->partition_num        = OS_DATA_PARTITION;
		par->par_desc_ver         = OS_PARTITION_VERSION;
		par->wrt_pass_cntr        = htons(STp->wrt_pass_cntr);
		par->first_frame_ppos     = htonl(STp->first_data_ppos);
		par->last_frame_ppos      = htonl(STp->capacity);
		aux->frame_seq_num        = htonl(frame_seq_number);
		aux->logical_blk_num_high = htonl(0);
		aux->logical_blk_num      = htonl(logical_blk_num);
		break;
	  default: ; /* probably FILL */
	}
	aux->filemark_cnt = htonl(STp->filemark_cnt);
	aux->phys_fm = htonl(0xffffffff);
	aux->last_mark_ppos = htonl(STp->last_mark_ppos);
	aux->last_mark_lbn  = htonl(STp->last_mark_lbn);
}

/*
 * Verify that we have the correct tape frame
 */
static int osst_verify_frame(struct osst_tape * STp, int frame_seq_number, int quiet)
{
	char               * name = tape_name(STp);
	os_aux_t           * aux  = STp->buffer->aux;
	os_partition_t     * par  = &(aux->partition);
	struct st_partstat * STps = &(STp->ps[STp->partition]);
	int		     blk_cnt, blk_sz, i;

	if (STp->raw) {
		if (STp->buffer->syscall_result) {
			for (i=0; i < STp->buffer->sg_segs; i++)
				memset(page_address(sg_page(&STp->buffer->sg[i])),
				       0, STp->buffer->sg[i].length);
			strcpy(STp->buffer->b_data, "READ ERROR ON FRAME");
                } else
			STp->buffer->buffer_bytes = OS_FRAME_SIZE;
		return 1;
	}
	if (STp->buffer->syscall_result) {
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Skipping frame, read error\n", name);
#endif
		return 0;
	}
	if (ntohl(aux->format_id) != 0) {
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Skipping frame, format_id %u\n", name, ntohl(aux->format_id));
#endif
		goto err_out;
	}
	if (memcmp(aux->application_sig, STp->application_sig, 4) != 0 &&
	    (memcmp(aux->application_sig, "LIN3", 4) != 0 || STp->linux_media_version != 4)) {
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Skipping frame, incorrect application signature\n", name);
#endif
		goto err_out;
	}
	if (par->partition_num != OS_DATA_PARTITION) {
		if (!STp->linux_media || STp->linux_media_version != 2) {
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: Skipping frame, partition num %d\n",
					    name, par->partition_num);
#endif
			goto err_out;
		}
	}
	if (par->par_desc_ver != OS_PARTITION_VERSION) {
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Skipping frame, partition version %d\n", name, par->par_desc_ver);
#endif
		goto err_out;
	}
	if (ntohs(par->wrt_pass_cntr) != STp->wrt_pass_cntr) {
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Skipping frame, wrt_pass_cntr %d (expected %d)\n", 
				    name, ntohs(par->wrt_pass_cntr), STp->wrt_pass_cntr);
#endif
		goto err_out;
	}
	if (aux->frame_type != OS_FRAME_TYPE_DATA &&
	    aux->frame_type != OS_FRAME_TYPE_EOD &&
	    aux->frame_type != OS_FRAME_TYPE_MARKER) {
		if (!quiet) {
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: Skipping frame, frame type %x\n", name, aux->frame_type);
#endif
		}
		goto err_out;
	}
	if (aux->frame_type == OS_FRAME_TYPE_EOD &&
	    STp->first_frame_position < STp->eod_frame_ppos) {
		printk(KERN_INFO "%s:I: Skipping premature EOD frame %d\n", name,
				 STp->first_frame_position);
		goto err_out;
	}
        if (frame_seq_number != -1 && ntohl(aux->frame_seq_num) != frame_seq_number) {
		if (!quiet) {
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: Skipping frame, sequence number %u (expected %d)\n", 
					    name, ntohl(aux->frame_seq_num), frame_seq_number);
#endif
		}
		goto err_out;
	}
	if (aux->frame_type == OS_FRAME_TYPE_MARKER) {
		STps->eof = ST_FM_HIT;

		i = ntohl(aux->filemark_cnt);
		if (STp->header_cache != NULL && i < OS_FM_TAB_MAX && (i > STp->filemark_cnt ||
		    STp->first_frame_position - 1 != ntohl(STp->header_cache->dat_fm_tab.fm_tab_ent[i]))) {
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: %s filemark %d at frame pos %d\n", name,
				  STp->header_cache->dat_fm_tab.fm_tab_ent[i] == 0?"Learned":"Corrected",
				  i, STp->first_frame_position - 1);
#endif
			STp->header_cache->dat_fm_tab.fm_tab_ent[i] = htonl(STp->first_frame_position - 1);
			if (i >= STp->filemark_cnt)
				 STp->filemark_cnt = i+1;
		}
	}
	if (aux->frame_type == OS_FRAME_TYPE_EOD) {
		STps->eof = ST_EOD_1;
		STp->frame_in_buffer = 1;
	}
	if (aux->frame_type == OS_FRAME_TYPE_DATA) {
                blk_cnt = ntohs(aux->dat.dat_list[0].blk_cnt);
		blk_sz  = ntohl(aux->dat.dat_list[0].blk_sz);
		STp->buffer->buffer_bytes = blk_cnt * blk_sz;
		STp->buffer->read_pointer = 0;
		STp->frame_in_buffer = 1;

		/* See what block size was used to write file */
		if (STp->block_size != blk_sz && blk_sz > 0) {
			printk(KERN_INFO
	    	"%s:I: File was written with block size %d%c, currently %d%c, adjusted to match.\n",
       				name, blk_sz<1024?blk_sz:blk_sz/1024,blk_sz<1024?'b':'k',
				STp->block_size<1024?STp->block_size:STp->block_size/1024,
				STp->block_size<1024?'b':'k');
			STp->block_size            = blk_sz;
			STp->buffer->buffer_blocks = OS_DATA_SIZE / blk_sz;
		}
		STps->eof = ST_NOEOF;
	}
        STp->frame_seq_number = ntohl(aux->frame_seq_num);
	STp->logical_blk_num  = ntohl(aux->logical_blk_num);
	return 1;

err_out:
	if (STp->read_error_frame == 0)
		STp->read_error_frame = STp->first_frame_position - 1;
	return 0;
}

/*
 * Wait for the unit to become Ready
 */
static int osst_wait_ready(struct osst_tape * STp, struct osst_request ** aSRpnt,
				 unsigned timeout, int initial_delay)
{
	unsigned char		cmd[MAX_COMMAND_SIZE];
	struct osst_request   * SRpnt;
	unsigned long		startwait = jiffies;
#if DEBUG
	int			dbg  = debugging;
	char    	      * name = tape_name(STp);

	printk(OSST_DEB_MSG "%s:D: Reached onstream wait ready\n", name);
#endif

	if (initial_delay > 0)
		msleep(jiffies_to_msecs(initial_delay));

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = TEST_UNIT_READY;

	SRpnt = osst_do_scsi(*aSRpnt, STp, cmd, 0, DMA_NONE, STp->timeout, MAX_RETRIES, 1);
	*aSRpnt = SRpnt;
	if (!SRpnt) return (-EBUSY);

	while ( STp->buffer->syscall_result && time_before(jiffies, startwait + timeout*HZ) &&
	       (( SRpnt->sense[2]  == 2 && SRpnt->sense[12] == 4    &&
		 (SRpnt->sense[13] == 1 || SRpnt->sense[13] == 8)    ) ||
		( SRpnt->sense[2]  == 6 && SRpnt->sense[12] == 0x28 &&
		  SRpnt->sense[13] == 0                                        )  )) {
#if DEBUG
	    if (debugging) {
		printk(OSST_DEB_MSG "%s:D: Sleeping in onstream wait ready\n", name);
		printk(OSST_DEB_MSG "%s:D: Turning off debugging for a while\n", name);
		debugging = 0;
	    }
#endif
	    msleep(100);

	    memset(cmd, 0, MAX_COMMAND_SIZE);
	    cmd[0] = TEST_UNIT_READY;

	    SRpnt = osst_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE, STp->timeout, MAX_RETRIES, 1);
	}
	*aSRpnt = SRpnt;
#if DEBUG
	debugging = dbg;
#endif
	if ( STp->buffer->syscall_result &&
	     osst_write_error_recovery(STp, aSRpnt, 0) ) {
#if DEBUG
	    printk(OSST_DEB_MSG "%s:D: Abnormal exit from onstream wait ready\n", name);
	    printk(OSST_DEB_MSG "%s:D: Result = %d, Sense: 0=%02x, 2=%02x, 12=%02x, 13=%02x\n", name,
			STp->buffer->syscall_result, SRpnt->sense[0], SRpnt->sense[2],
			SRpnt->sense[12], SRpnt->sense[13]);
#endif
	    return (-EIO);
	}
#if DEBUG
	printk(OSST_DEB_MSG "%s:D: Normal exit from onstream wait ready\n", name);
#endif
	return 0;
}

/*
 * Wait for a tape to be inserted in the unit
 */
static int osst_wait_for_medium(struct osst_tape * STp, struct osst_request ** aSRpnt, unsigned timeout)
{
	unsigned char		cmd[MAX_COMMAND_SIZE];
	struct osst_request   * SRpnt;
	unsigned long		startwait = jiffies;
#if DEBUG
	int			dbg = debugging;
	char    	      * name = tape_name(STp);

	printk(OSST_DEB_MSG "%s:D: Reached onstream wait for medium\n", name);
#endif

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = TEST_UNIT_READY;

	SRpnt = osst_do_scsi(*aSRpnt, STp, cmd, 0, DMA_NONE, STp->timeout, MAX_RETRIES, 1);
	*aSRpnt = SRpnt;
	if (!SRpnt) return (-EBUSY);

	while ( STp->buffer->syscall_result && time_before(jiffies, startwait + timeout*HZ) &&
		SRpnt->sense[2] == 2 && SRpnt->sense[12] == 0x3a && SRpnt->sense[13] == 0  ) {
#if DEBUG
	    if (debugging) {
		printk(OSST_DEB_MSG "%s:D: Sleeping in onstream wait medium\n", name);
		printk(OSST_DEB_MSG "%s:D: Turning off debugging for a while\n", name);
		debugging = 0;
	    }
#endif
	    msleep(100);

	    memset(cmd, 0, MAX_COMMAND_SIZE);
	    cmd[0] = TEST_UNIT_READY;

	    SRpnt = osst_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE, STp->timeout, MAX_RETRIES, 1);
	}
	*aSRpnt = SRpnt;
#if DEBUG
	debugging = dbg;
#endif
	if ( STp->buffer->syscall_result     && SRpnt->sense[2]  != 2 &&
	     SRpnt->sense[12] != 4 && SRpnt->sense[13] == 1) {
#if DEBUG
	    printk(OSST_DEB_MSG "%s:D: Abnormal exit from onstream wait medium\n", name);
	    printk(OSST_DEB_MSG "%s:D: Result = %d, Sense: 0=%02x, 2=%02x, 12=%02x, 13=%02x\n", name,
			STp->buffer->syscall_result, SRpnt->sense[0], SRpnt->sense[2],
			SRpnt->sense[12], SRpnt->sense[13]);
#endif
	    return 0;
	}
#if DEBUG
	printk(OSST_DEB_MSG "%s:D: Normal exit from onstream wait medium\n", name);
#endif
	return 1;
}

static int osst_position_tape_and_confirm(struct osst_tape * STp, struct osst_request ** aSRpnt, int frame)
{
	int	retval;

	osst_wait_ready(STp, aSRpnt, 15 * 60, 0);			/* TODO - can this catch a write error? */
	retval = osst_set_frame_position(STp, aSRpnt, frame, 0);
	if (retval) return (retval);
	osst_wait_ready(STp, aSRpnt, 15 * 60, OSST_WAIT_POSITION_COMPLETE);
	return (osst_get_frame_position(STp, aSRpnt));
}

/*
 * Wait for write(s) to complete
 */
static int osst_flush_drive_buffer(struct osst_tape * STp, struct osst_request ** aSRpnt)
{
	unsigned char		cmd[MAX_COMMAND_SIZE];
	struct osst_request   * SRpnt;
	int			result = 0;
	int			delay  = OSST_WAIT_WRITE_COMPLETE;
#if DEBUG
	char		      * name = tape_name(STp);

	printk(OSST_DEB_MSG "%s:D: Reached onstream flush drive buffer (write filemark)\n", name);
#endif

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = WRITE_FILEMARKS;
	cmd[1] = 1;

	SRpnt = osst_do_scsi(*aSRpnt, STp, cmd, 0, DMA_NONE, STp->timeout, MAX_RETRIES, 1);
	*aSRpnt = SRpnt;
	if (!SRpnt) return (-EBUSY);
	if (STp->buffer->syscall_result) {
		if ((SRpnt->sense[2] & 0x0f) == 2 && SRpnt->sense[12] == 4) {
			if (SRpnt->sense[13] == 8) {
				delay = OSST_WAIT_LONG_WRITE_COMPLETE;
			}
		} else
			result = osst_write_error_recovery(STp, aSRpnt, 0);
	}
	result |= osst_wait_ready(STp, aSRpnt, 5 * 60, delay);
	STp->ps[STp->partition].rw = OS_WRITING_COMPLETE;

	return (result);
}

#define OSST_POLL_PER_SEC 10
static int osst_wait_frame(struct osst_tape * STp, struct osst_request ** aSRpnt, int curr, int minlast, int to)
{
	unsigned long	startwait = jiffies;
	char	      * name      = tape_name(STp);
#if DEBUG
	char	   notyetprinted  = 1;
#endif
	if (minlast >= 0 && STp->ps[STp->partition].rw != ST_READING)
		printk(KERN_ERR "%s:A: Waiting for frame without having initialized read!\n", name);

	while (time_before (jiffies, startwait + to*HZ))
	{ 
		int result;
		result = osst_get_frame_position(STp, aSRpnt);
		if (result == -EIO)
			if ((result = osst_write_error_recovery(STp, aSRpnt, 0)) == 0)
				return 0;	/* successful recovery leaves drive ready for frame */
		if (result < 0) break;
		if (STp->first_frame_position == curr &&
		    ((minlast < 0 &&
		      (signed)STp->last_frame_position > (signed)curr + minlast) ||
		     (minlast >= 0 && STp->cur_frames > minlast)
		    ) && result >= 0)
		{
#if DEBUG			
			if (debugging || time_after_eq(jiffies, startwait + 2*HZ/OSST_POLL_PER_SEC))
				printk (OSST_DEB_MSG
					"%s:D: Succ wait f fr %i (>%i): %i-%i %i (%i): %3li.%li s\n",
					name, curr, curr+minlast, STp->first_frame_position,
					STp->last_frame_position, STp->cur_frames,
					result, (jiffies-startwait)/HZ, 
					(((jiffies-startwait)%HZ)*10)/HZ);
#endif
			return 0;
		}
#if DEBUG
		if (time_after_eq(jiffies, startwait + 2*HZ/OSST_POLL_PER_SEC) && notyetprinted)
		{
			printk (OSST_DEB_MSG "%s:D: Wait for frame %i (>%i): %i-%i %i (%i)\n",
				name, curr, curr+minlast, STp->first_frame_position,
				STp->last_frame_position, STp->cur_frames, result);
			notyetprinted--;
		}
#endif
		msleep(1000 / OSST_POLL_PER_SEC);
	}
#if DEBUG
	printk (OSST_DEB_MSG "%s:D: Fail wait f fr %i (>%i): %i-%i %i: %3li.%li s\n",
		name, curr, curr+minlast, STp->first_frame_position,
		STp->last_frame_position, STp->cur_frames,
		(jiffies-startwait)/HZ, (((jiffies-startwait)%HZ)*10)/HZ);
#endif	
	return -EBUSY;
}

static int osst_recover_wait_frame(struct osst_tape * STp, struct osst_request ** aSRpnt, int writing)
{
	struct osst_request   * SRpnt;
	unsigned char		cmd[MAX_COMMAND_SIZE];
	unsigned long   	startwait = jiffies;
	int			retval    = 1;
        char		      * name      = tape_name(STp);
                                                                                                                                
	if (writing) {
		char	mybuf[24];
		char  * olddata = STp->buffer->b_data;
		int	oldsize = STp->buffer->buffer_size;

		/* write zero fm then read pos - if shows write error, try to recover - if no progress, wait */

		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = WRITE_FILEMARKS;
		cmd[1] = 1;
		SRpnt = osst_do_scsi(*aSRpnt, STp, cmd, 0, DMA_NONE, STp->timeout,
								MAX_RETRIES, 1);

		while (retval && time_before (jiffies, startwait + 5*60*HZ)) {

			if (STp->buffer->syscall_result && (SRpnt->sense[2] & 0x0f) != 2) {

				/* some failure - not just not-ready */
				retval = osst_write_error_recovery(STp, aSRpnt, 0);
				break;
			}
			schedule_timeout_interruptible(HZ / OSST_POLL_PER_SEC);

			STp->buffer->b_data = mybuf; STp->buffer->buffer_size = 24;
			memset(cmd, 0, MAX_COMMAND_SIZE);
			cmd[0] = READ_POSITION;

			SRpnt = osst_do_scsi(SRpnt, STp, cmd, 20, DMA_FROM_DEVICE, STp->timeout,
										MAX_RETRIES, 1);

			retval = ( STp->buffer->syscall_result || (STp->buffer)->b_data[15] > 25 );
			STp->buffer->b_data = olddata; STp->buffer->buffer_size = oldsize;
		}
		if (retval)
			printk(KERN_ERR "%s:E: Device did not succeed to write buffered data\n", name);
	} else
		/* TODO - figure out which error conditions can be handled */
		if (STp->buffer->syscall_result)
			printk(KERN_WARNING
				"%s:W: Recover_wait_frame(read) cannot handle %02x:%02x:%02x\n", name,
					(*aSRpnt)->sense[ 2] & 0x0f,
					(*aSRpnt)->sense[12],
					(*aSRpnt)->sense[13]);

	return retval;
}

/*
 * Read the next OnStream tape frame at the current location
 */
static int osst_read_frame(struct osst_tape * STp, struct osst_request ** aSRpnt, int timeout)
{
	unsigned char		cmd[MAX_COMMAND_SIZE];
	struct osst_request   * SRpnt;
	int			retval = 0;
#if DEBUG
	os_aux_t	      * aux    = STp->buffer->aux;
	char		      * name   = tape_name(STp);
#endif

	if (STp->poll)
		if (osst_wait_frame (STp, aSRpnt, STp->first_frame_position, 0, timeout))
			retval = osst_recover_wait_frame(STp, aSRpnt, 0);

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = READ_6;
	cmd[1] = 1;
	cmd[4] = 1;

#if DEBUG
	if (debugging)
		printk(OSST_DEB_MSG "%s:D: Reading frame from OnStream tape\n", name);
#endif
	SRpnt = osst_do_scsi(*aSRpnt, STp, cmd, OS_FRAME_SIZE, DMA_FROM_DEVICE,
				      STp->timeout, MAX_RETRIES, 1);
	*aSRpnt = SRpnt;
	if (!SRpnt)
		return (-EBUSY);

	if ((STp->buffer)->syscall_result) {
	    retval = 1;
	    if (STp->read_error_frame == 0) {
		STp->read_error_frame = STp->first_frame_position;
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Recording read error at %d\n", name, STp->read_error_frame);
#endif
	    }
#if DEBUG
	    if (debugging)
		printk(OSST_DEB_MSG "%s:D: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
		   name,
		   SRpnt->sense[0], SRpnt->sense[1],
		   SRpnt->sense[2], SRpnt->sense[3],
		   SRpnt->sense[4], SRpnt->sense[5],
		   SRpnt->sense[6], SRpnt->sense[7]);
#endif
	}
	else
	    STp->first_frame_position++;
#if DEBUG
	if (debugging) {
	   char sig[8]; int i;
	   for (i=0;i<4;i++)
		   sig[i] = aux->application_sig[i]<32?'^':aux->application_sig[i];
	   sig[4] = '\0';
	   printk(OSST_DEB_MSG 
		"%s:D: AUX: %s UpdFrCt#%d Wpass#%d %s FrSeq#%d LogBlk#%d Qty=%d Sz=%d\n", name, sig,
			ntohl(aux->update_frame_cntr), ntohs(aux->partition.wrt_pass_cntr),
			aux->frame_type==1?"EOD":aux->frame_type==2?"MARK":
			aux->frame_type==8?"HEADR":aux->frame_type==0x80?"DATA":"FILL", 
			ntohl(aux->frame_seq_num), ntohl(aux->logical_blk_num),
			ntohs(aux->dat.dat_list[0].blk_cnt), ntohl(aux->dat.dat_list[0].blk_sz) );
	   if (aux->frame_type==2)
		printk(OSST_DEB_MSG "%s:D: mark_cnt=%d, last_mark_ppos=%d, last_mark_lbn=%d\n", name,
			ntohl(aux->filemark_cnt), ntohl(aux->last_mark_ppos), ntohl(aux->last_mark_lbn));
	   printk(OSST_DEB_MSG "%s:D: Exit read frame from OnStream tape with code %d\n", name, retval);
	}
#endif
	return (retval);
}

static int osst_initiate_read(struct osst_tape * STp, struct osst_request ** aSRpnt)
{
	struct st_partstat    * STps   = &(STp->ps[STp->partition]);
	struct osst_request   * SRpnt  ;
	unsigned char		cmd[MAX_COMMAND_SIZE];
	int			retval = 0;
	char		      * name   = tape_name(STp);

	if (STps->rw != ST_READING) {         /* Initialize read operation */
		if (STps->rw == ST_WRITING || STp->dirty) {
			STp->write_type = OS_WRITE_DATA;
                        osst_flush_write_buffer(STp, aSRpnt);
			osst_flush_drive_buffer(STp, aSRpnt);
		}
		STps->rw = ST_READING;
		STp->frame_in_buffer = 0;

		/*
		 *      Issue a read 0 command to get the OnStream drive
                 *      read frames into its buffer.
		 */
		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = READ_6;
		cmd[1] = 1;

#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Start Read Ahead on OnStream tape\n", name);
#endif
		SRpnt   = osst_do_scsi(*aSRpnt, STp, cmd, 0, DMA_NONE, STp->timeout, MAX_RETRIES, 1);
		*aSRpnt = SRpnt;
		if ((retval = STp->buffer->syscall_result))
			printk(KERN_WARNING "%s:W: Error starting read ahead\n", name);
	}

	return retval;
}

static int osst_get_logical_frame(struct osst_tape * STp, struct osst_request ** aSRpnt,
						int frame_seq_number, int quiet)
{
	struct st_partstat * STps  = &(STp->ps[STp->partition]);
	char		   * name  = tape_name(STp);
	int		     cnt   = 0,
			     bad   = 0,
			     past  = 0,
			     x,
			     position;

	/*
	 * If we want just any frame (-1) and there is a frame in the buffer, return it
	 */
	if (frame_seq_number == -1 && STp->frame_in_buffer) {
#if DEBUG
		printk(OSST_DEB_MSG "%s:D: Frame %d still in buffer\n", name, STp->frame_seq_number);
#endif
		return (STps->eof);
	}
	/*
         * Search and wait for the next logical tape frame
	 */
	while (1) {
		if (cnt++ > 400) {
                        printk(KERN_ERR "%s:E: Couldn't find logical frame %d, aborting\n",
					    name, frame_seq_number);
			if (STp->read_error_frame) {
				osst_set_frame_position(STp, aSRpnt, STp->read_error_frame, 0);
#if DEBUG
                        	printk(OSST_DEB_MSG "%s:D: Repositioning tape to bad frame %d\n",
						    name, STp->read_error_frame);
#endif
				STp->read_error_frame = 0;
				STp->abort_count++;
			}
			return (-EIO);
		}
#if DEBUG
		if (debugging)
			printk(OSST_DEB_MSG "%s:D: Looking for frame %d, attempt %d\n",
					  name, frame_seq_number, cnt);
#endif
		if ( osst_initiate_read(STp, aSRpnt)
                || ( (!STp->frame_in_buffer) && osst_read_frame(STp, aSRpnt, 30) ) ) {
			if (STp->raw)
				return (-EIO);
			position = osst_get_frame_position(STp, aSRpnt);
			if (position >= 0xbae && position < 0xbb8)
				position = 0xbb8;
			else if (position > STp->eod_frame_ppos || ++bad == 10) {
				position = STp->read_error_frame - 1;
				bad = 0;
			}
			else {
				position += 29;
				cnt      += 19;
			}
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: Bad frame detected, positioning tape to block %d\n",
					 name, position);
#endif
			osst_set_frame_position(STp, aSRpnt, position, 0);
			continue;
		}
		if (osst_verify_frame(STp, frame_seq_number, quiet))
			break;
		if (osst_verify_frame(STp, -1, quiet)) {
			x = ntohl(STp->buffer->aux->frame_seq_num);
			if (STp->fast_open) {
				printk(KERN_WARNING
				       "%s:W: Found logical frame %d instead of %d after fast open\n",
				       name, x, frame_seq_number);
				STp->header_ok = 0;
				STp->read_error_frame = 0;
				return (-EIO);
			}
			if (x > frame_seq_number) {
				if (++past > 3) {
					/* positioning backwards did not bring us to the desired frame */
					position = STp->read_error_frame - 1;
				}
				else {
			        	position = osst_get_frame_position(STp, aSRpnt)
					         + frame_seq_number - x - 1;

					if (STp->first_frame_position >= 3000 && position < 3000)
						position -= 10;
				}
#if DEBUG
                                printk(OSST_DEB_MSG
				       "%s:D: Found logical frame %d while looking for %d: back up %d\n",
						name, x, frame_seq_number,
					       	STp->first_frame_position - position);
#endif
                        	osst_set_frame_position(STp, aSRpnt, position, 0);
				cnt += 10;
			}
			else
				past = 0;
		}
		if (osst_get_frame_position(STp, aSRpnt) == 0xbaf) {
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: Skipping config partition\n", name);
#endif
			osst_set_frame_position(STp, aSRpnt, 0xbb8, 0);
			cnt--;
		}
		STp->frame_in_buffer = 0;
	}
	if (cnt > 1) {
		STp->recover_count++;
		STp->recover_erreg++;
		printk(KERN_WARNING "%s:I: Don't worry, Read error at position %d recovered\n", 
					name, STp->read_error_frame);
 	}
	STp->read_count++;

#if DEBUG
	if (debugging || STps->eof)
		printk(OSST_DEB_MSG
			"%s:D: Exit get logical frame (%d=>%d) from OnStream tape with code %d\n",
			name, frame_seq_number, STp->frame_seq_number, STps->eof);
#endif
	STp->fast_open = 0;
	STp->read_error_frame = 0;
	return (STps->eof);
}

static int osst_seek_logical_blk(struct osst_tape * STp, struct osst_request ** aSRpnt, int logical_blk_num)
{
        struct st_partstat * STps = &(STp->ps[STp->partition]);
	char		   * name = tape_name(STp);
	int	retries    = 0;
	int	frame_seq_estimate, ppos_estimate, move;
	
	if (logical_blk_num < 0) logical_blk_num = 0;
#if DEBUG
	printk(OSST_DEB_MSG "%s:D: Seeking logical block %d (now at %d, size %d%c)\n",
				name, logical_blk_num, STp->logical_blk_num, 
				STp->block_size<1024?STp->block_size:STp->block_size/1024,
				STp->block_size<1024?'b':'k');
#endif
	/* Do we know where we are? */
	if (STps->drv_block >= 0) {
		move                = logical_blk_num - STp->logical_blk_num;
		if (move < 0) move -= (OS_DATA_SIZE / STp->block_size) - 1;
		move               /= (OS_DATA_SIZE / STp->block_size);
		frame_seq_estimate  = STp->frame_seq_number + move;
	} else
		frame_seq_estimate  = logical_blk_num * STp->block_size / OS_DATA_SIZE;

	if (frame_seq_estimate < 2980) ppos_estimate = frame_seq_estimate + 10;
	else			       ppos_estimate = frame_seq_estimate + 20;
	while (++retries < 10) {
	   if (ppos_estimate > STp->eod_frame_ppos-2) {
	       frame_seq_estimate += STp->eod_frame_ppos - 2 - ppos_estimate;
	       ppos_estimate       = STp->eod_frame_ppos - 2;
	   }
	   if (frame_seq_estimate < 0) {
	       frame_seq_estimate = 0;
	       ppos_estimate      = 10;
	   }
	   osst_set_frame_position(STp, aSRpnt, ppos_estimate, 0);
	   if (osst_get_logical_frame(STp, aSRpnt, frame_seq_estimate, 1) >= 0) {
	      /* we've located the estimated frame, now does it have our block? */
	      if (logical_blk_num <  STp->logical_blk_num ||
	          logical_blk_num >= STp->logical_blk_num + ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt)) {
		 if (STps->eof == ST_FM_HIT)
		    move = logical_blk_num < STp->logical_blk_num? -2 : 1;
		 else {
		    move                = logical_blk_num - STp->logical_blk_num;
		    if (move < 0) move -= (OS_DATA_SIZE / STp->block_size) - 1;
		    move               /= (OS_DATA_SIZE / STp->block_size);
		 }
		 if (!move) move = logical_blk_num > STp->logical_blk_num ? 1 : -1;
#if DEBUG
		 printk(OSST_DEB_MSG
			"%s:D: Seek retry %d at ppos %d fsq %d (est %d) lbn %d (need %d) move %d\n",
				name, retries, ppos_estimate, STp->frame_seq_number, frame_seq_estimate, 
				STp->logical_blk_num, logical_blk_num, move);
#endif
		 frame_seq_estimate += move;
		 ppos_estimate      += move;
		 continue;
	      } else {
		 STp->buffer->read_pointer  = (logical_blk_num - STp->logical_blk_num) * STp->block_size;
		 STp->buffer->buffer_bytes -= STp->buffer->read_pointer;
		 STp->logical_blk_num       =  logical_blk_num;
#if DEBUG
		 printk(OSST_DEB_MSG 
			"%s:D: Seek success at ppos %d fsq %d in_buf %d, bytes %d, ptr %d*%d\n",
				name, ppos_estimate, STp->frame_seq_number, STp->frame_in_buffer, 
				STp->buffer->buffer_bytes, STp->buffer->read_pointer / STp->block_size, 
				STp->block_size);
#endif
		 STps->drv_file = ntohl(STp->buffer->aux->filemark_cnt);
		 if (STps->eof == ST_FM_HIT) {
		     STps->drv_file++;
		     STps->drv_block = 0;
		 } else {
		     STps->drv_block = ntohl(STp->buffer->aux->last_mark_lbn)?
					  STp->logical_blk_num -
					     (STps->drv_file ? ntohl(STp->buffer->aux->last_mark_lbn) + 1 : 0):
					-1;
		 }
		 STps->eof = (STp->first_frame_position >= STp->eod_frame_ppos)?ST_EOD:ST_NOEOF;
		 return 0;
	      }
	   }
	   if (osst_get_logical_frame(STp, aSRpnt, -1, 1) < 0)
	      goto error;
	   /* we are not yet at the estimated frame, adjust our estimate of its physical position */
#if DEBUG
	   printk(OSST_DEB_MSG "%s:D: Seek retry %d at ppos %d fsq %d (est %d) lbn %d (need %d)\n", 
			   name, retries, ppos_estimate, STp->frame_seq_number, frame_seq_estimate, 
			   STp->logical_blk_num, logical_blk_num);
#endif
	   if (frame_seq_estimate != STp->frame_seq_number)
	      ppos_estimate += frame_seq_estimate - STp->frame_seq_number;
	   else
	      break;
	}
error:
	printk(KERN_ERR "%s:E: Couldn't seek to logical block %d (at %d), %d retries\n", 
			    name, logical_blk_num, STp->logical_blk_num, retries);
	return (-EIO);
}

/* The values below are based on the OnStream frame payload size of 32K == 2**15,
 * that is, OSST_FRAME_SHIFT + OSST_SECTOR_SHIFT must be 15. With a minimum block
 * size of 512 bytes, we need to be able to resolve 32K/512 == 64 == 2**6 positions
 * inside each frame. Finally, OSST_SECTOR_MASK == 2**OSST_FRAME_SHIFT - 1.
 */
#define OSST_FRAME_SHIFT  6
#define OSST_SECTOR_SHIFT 9
#define OSST_SECTOR_MASK  0x03F

static int osst_get_sector(struct osst_tape * STp, struct osst_request ** aSRpnt)
{
	int	sector;
#if DEBUG
	char  * name = tape_name(STp);
	
	printk(OSST_DEB_MSG 
		"%s:D: Positioned at ppos %d, frame %d, lbn %d, file %d, blk %d, %cptr %d, eof %d\n",
		name, STp->first_frame_position, STp->frame_seq_number, STp->logical_blk_num,
		STp->ps[STp->partition].drv_file, STp->ps[STp->partition].drv_block, 
		STp->ps[STp->partition].rw == ST_WRITING?'w':'r',
		STp->ps[STp->partition].rw == ST_WRITING?STp->buffer->buffer_bytes:
		STp->buffer->read_pointer, STp->ps[STp->partition].eof);
#endif
	/* do we know where we are inside a file? */
	if (STp->ps[STp->partition].drv_block >= 0) {
		sector = (STp->frame_in_buffer ? STp->first_frame_position-1 :
				STp->first_frame_position) << OSST_FRAME_SHIFT;
		if (STp->ps[STp->partition].rw == ST_WRITING)
		       	sector |= (STp->buffer->buffer_bytes >> OSST_SECTOR_SHIFT) & OSST_SECTOR_MASK;
		else
	       		sector |= (STp->buffer->read_pointer >> OSST_SECTOR_SHIFT) & OSST_SECTOR_MASK;
	} else {
		sector = osst_get_frame_position(STp, aSRpnt);
		if (sector > 0)
			sector <<= OSST_FRAME_SHIFT;
	}
	return sector;
}

static int osst_seek_sector(struct osst_tape * STp, struct osst_request ** aSRpnt, int sector)
{
        struct st_partstat * STps   = &(STp->ps[STp->partition]);
	int		     frame  = sector >> OSST_FRAME_SHIFT,
			     offset = (sector & OSST_SECTOR_MASK) << OSST_SECTOR_SHIFT, 
			     r;
#if DEBUG
	char          * name = tape_name(STp);

	printk(OSST_DEB_MSG "%s:D: Seeking sector %d in frame %d at offset %d\n",
				name, sector, frame, offset);
#endif
	if (frame < 0 || frame >= STp->capacity) return (-ENXIO);

	if (frame <= STp->first_data_ppos) {
		STp->frame_seq_number = STp->logical_blk_num = STps->drv_file = STps->drv_block = 0;
		return (osst_set_frame_position(STp, aSRpnt, frame, 0));
	}
	r = osst_set_frame_position(STp, aSRpnt, offset?frame:frame-1, 0);
	if (r < 0) return r;

	r = osst_get_logical_frame(STp, aSRpnt, -1, 1);
	if (r < 0) return r;

	if (osst_get_frame_position(STp, aSRpnt) != (offset?frame+1:frame)) return (-EIO);

	if (offset) {
		STp->logical_blk_num      += offset / STp->block_size;
		STp->buffer->read_pointer  = offset;
		STp->buffer->buffer_bytes -= offset;
	} else {
		STp->frame_seq_number++;
		STp->frame_in_buffer       = 0;
		STp->logical_blk_num      += ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt);
		STp->buffer->buffer_bytes  = STp->buffer->read_pointer = 0;
	}
	STps->drv_file = ntohl(STp->buffer->aux->filemark_cnt);
	if (STps->eof == ST_FM_HIT) {
		STps->drv_file++;
		STps->drv_block = 0;
	} else {
		STps->drv_block = ntohl(STp->buffer->aux->last_mark_lbn)?
				    STp->logical_blk_num -
					(STps->drv_file ? ntohl(STp->buffer->aux->last_mark_lbn) + 1 : 0):
				  -1;
	}
	STps->eof       = (STp->first_frame_position >= STp->eod_frame_ppos)?ST_EOD:ST_NOEOF;
#if DEBUG
	printk(OSST_DEB_MSG 
		"%s:D: Now positioned at ppos %d, frame %d, lbn %d, file %d, blk %d, rptr %d, eof %d\n",
		name, STp->first_frame_position, STp->frame_seq_number, STp->logical_blk_num,
		STps->drv_file, STps->drv_block, STp->buffer->read_pointer, STps->eof);
#endif
	return 0;
}

/*
 * Read back the drive's internal buffer contents, as a part
 * of the write error recovery mechanism for old OnStream
 * firmware revisions.
 * Precondition for this function to work: all frames in the
 * drive's buffer must be of one type (DATA, MARK or EOD)!
 */
static int osst_read_back_buffer_and_rewrite(struct osst_tape * STp, struct osst_request ** aSRpnt,
						unsigned int frame, unsigned int skip, int pending)
{
	struct osst_request   * SRpnt = * aSRpnt;
	unsigned char	      * buffer, * p;
	unsigned char		cmd[MAX_COMMAND_SIZE];
	int			flag, new_frame, i;
	int			nframes          = STp->cur_frames;
	int			blks_per_frame   = ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt);
	int			frame_seq_number = ntohl(STp->buffer->aux->frame_seq_num)
						- (nframes + pending - 1);
	int			logical_blk_num  = ntohl(STp->buffer->aux->logical_blk_num) 
						- (nframes + pending - 1) * blks_per_frame;
	char		      * name             = tape_name(STp);
	unsigned long		startwait        = jiffies;
#if DEBUG
	int			dbg              = debugging;
#endif

	if ((buffer = vmalloc((nframes + 1) * OS_DATA_SIZE)) == NULL)
		return (-EIO);

	printk(KERN_INFO "%s:I: Reading back %d frames from drive buffer%s\n",
			 name, nframes, pending?" and one that was pending":"");

	osst_copy_from_buffer(STp->buffer, (p = &buffer[nframes * OS_DATA_SIZE]));
#if DEBUG
	if (pending && debugging)
		printk(OSST_DEB_MSG "%s:D: Pending frame %d (lblk %d), data %02x %02x %02x %02x\n",
				name, frame_seq_number + nframes,
			       	logical_blk_num + nframes * blks_per_frame,
			       	p[0], p[1], p[2], p[3]);
#endif
	for (i = 0, p = buffer; i < nframes; i++, p += OS_DATA_SIZE) {

		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = 0x3C;		/* Buffer Read           */
		cmd[1] = 6;		/* Retrieve Faulty Block */
		cmd[7] = 32768 >> 8;
		cmd[8] = 32768 & 0xff;

		SRpnt = osst_do_scsi(SRpnt, STp, cmd, OS_FRAME_SIZE, DMA_FROM_DEVICE,
					    STp->timeout, MAX_RETRIES, 1);
	
		if ((STp->buffer)->syscall_result || !SRpnt) {
			printk(KERN_ERR "%s:E: Failed to read frame back from OnStream buffer\n", name);
			vfree(buffer);
			*aSRpnt = SRpnt;
			return (-EIO);
		}
		osst_copy_from_buffer(STp->buffer, p);
#if DEBUG
		if (debugging)
			printk(OSST_DEB_MSG "%s:D: Read back logical frame %d, data %02x %02x %02x %02x\n",
					  name, frame_seq_number + i, p[0], p[1], p[2], p[3]);
#endif
	}
	*aSRpnt = SRpnt;
	osst_get_frame_position(STp, aSRpnt);

#if DEBUG
	printk(OSST_DEB_MSG "%s:D: Frames left in buffer: %d\n", name, STp->cur_frames);
#endif
	/* Write synchronously so we can be sure we're OK again and don't have to recover recursively */
	/* In the header we don't actually re-write the frames that fail, just the ones after them */

	for (flag=1, new_frame=frame, p=buffer, i=0; i < nframes + pending; ) {

		if (flag) {
			if (STp->write_type == OS_WRITE_HEADER) {
				i += skip;
				p += skip * OS_DATA_SIZE;
			}
			else if (new_frame < 2990 && new_frame+skip+nframes+pending >= 2990)
				new_frame = 3000-i;
			else
				new_frame += skip;
#if DEBUG
			printk(OSST_DEB_MSG "%s:D: Position to frame %d, write fseq %d\n",
						name, new_frame+i, frame_seq_number+i);
#endif
			osst_set_frame_position(STp, aSRpnt, new_frame + i, 0);
			osst_wait_ready(STp, aSRpnt, 60, OSST_WAIT_POSITION_COMPLETE);
			osst_get_frame_position(STp, aSRpnt);
			SRpnt = * aSRpnt;

			if (new_frame > frame + 1000) {
				printk(KERN_ERR "%s:E: Failed to find writable tape media\n", nam…