xref: /openbmc/linux/drivers/scsi/st.c (revision b6bec26c)
1 /*
2    SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
3    file Documentation/scsi/st.txt for more information.
4 
5    History:
6    Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
7    Contribution and ideas from several people including (in alphabetical
8    order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
9    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
10    Michael Schaefer, J"org Weule, and Eric Youngdale.
11 
12    Copyright 1992 - 2010 Kai Makisara
13    email Kai.Makisara@kolumbus.fi
14 
15    Some small formal changes - aeb, 950809
16 
17    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
18  */
19 
20 static const char *verstr = "20101219";
21 
22 #include <linux/module.h>
23 
24 #include <linux/fs.h>
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
27 #include <linux/mm.h>
28 #include <linux/init.h>
29 #include <linux/string.h>
30 #include <linux/slab.h>
31 #include <linux/errno.h>
32 #include <linux/mtio.h>
33 #include <linux/cdrom.h>
34 #include <linux/ioctl.h>
35 #include <linux/fcntl.h>
36 #include <linux/spinlock.h>
37 #include <linux/blkdev.h>
38 #include <linux/moduleparam.h>
39 #include <linux/cdev.h>
40 #include <linux/idr.h>
41 #include <linux/delay.h>
42 #include <linux/mutex.h>
43 
44 #include <asm/uaccess.h>
45 #include <asm/dma.h>
46 
47 #include <scsi/scsi.h>
48 #include <scsi/scsi_dbg.h>
49 #include <scsi/scsi_device.h>
50 #include <scsi/scsi_driver.h>
51 #include <scsi/scsi_eh.h>
52 #include <scsi/scsi_host.h>
53 #include <scsi/scsi_ioctl.h>
54 #include <scsi/sg.h>
55 
56 
57 /* The driver prints some debugging information on the console if DEBUG
58    is defined and non-zero. */
59 #define DEBUG 0
60 
61 #if DEBUG
62 /* The message level for the debug messages is currently set to KERN_NOTICE
63    so that people can easily see the messages. Later when the debugging messages
64    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
65 #define ST_DEB_MSG  KERN_NOTICE
66 #define DEB(a) a
67 #define DEBC(a) if (debugging) { a ; }
68 #else
69 #define DEB(a)
70 #define DEBC(a)
71 #endif
72 
73 #define ST_KILOBYTE 1024
74 
75 #include "st_options.h"
76 #include "st.h"
77 
78 static int buffer_kbs;
79 static int max_sg_segs;
80 static int try_direct_io = TRY_DIRECT_IO;
81 static int try_rdio = 1;
82 static int try_wdio = 1;
83 
84 static struct class st_sysfs_class;
85 static struct device_attribute st_dev_attrs[];
86 
87 MODULE_AUTHOR("Kai Makisara");
88 MODULE_DESCRIPTION("SCSI tape (st) driver");
89 MODULE_LICENSE("GPL");
90 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
91 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
92 
93 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
94  * of sysfs parameters (which module_param doesn't yet support).
95  * Sysfs parameters defined explicitly later.
96  */
97 module_param_named(buffer_kbs, buffer_kbs, int, 0);
98 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
99 module_param_named(max_sg_segs, max_sg_segs, int, 0);
100 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
101 module_param_named(try_direct_io, try_direct_io, int, 0);
102 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
103 
104 /* Extra parameters for testing */
105 module_param_named(try_rdio, try_rdio, int, 0);
106 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
107 module_param_named(try_wdio, try_wdio, int, 0);
108 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
109 
110 #ifndef MODULE
111 static int write_threshold_kbs;  /* retained for compatibility */
112 static struct st_dev_parm {
113 	char *name;
114 	int *val;
115 } parms[] __initdata = {
116 	{
117 		"buffer_kbs", &buffer_kbs
118 	},
119 	{       /* Retained for compatibility with 2.4 */
120 		"write_threshold_kbs", &write_threshold_kbs
121 	},
122 	{
123 		"max_sg_segs", NULL
124 	},
125 	{
126 		"try_direct_io", &try_direct_io
127 	}
128 };
129 #endif
130 
131 /* Restrict the number of modes so that names for all are assigned */
132 #if ST_NBR_MODES > 16
133 #error "Maximum number of modes is 16"
134 #endif
135 /* Bit reversed order to get same names for same minors with all
136    mode counts */
137 static const char *st_formats[] = {
138 	"",  "r", "k", "s", "l", "t", "o", "u",
139 	"m", "v", "p", "x", "a", "y", "q", "z"};
140 
141 /* The default definitions have been moved to st_options.h */
142 
143 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
144 
145 /* The buffer size should fit into the 24 bits for length in the
146    6-byte SCSI read and write commands. */
147 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
148 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
149 #endif
150 
151 static int debugging = DEBUG;
152 
153 #define MAX_RETRIES 0
154 #define MAX_WRITE_RETRIES 0
155 #define MAX_READY_RETRIES 0
156 #define NO_TAPE  NOT_READY
157 
158 #define ST_TIMEOUT (900 * HZ)
159 #define ST_LONG_TIMEOUT (14000 * HZ)
160 
161 /* Remove mode bits and auto-rewind bit (7) */
162 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
163     (iminor(x) & ~(-1 << ST_MODE_SHIFT)) )
164 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
165 
166 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
167 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
168   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
169 
170 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
171    24 bits) */
172 #define SET_DENS_AND_BLK 0x10001
173 
174 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
175 static int st_max_sg_segs = ST_MAX_SG;
176 
177 static int modes_defined;
178 
179 static int enlarge_buffer(struct st_buffer *, int, int);
180 static void clear_buffer(struct st_buffer *);
181 static void normalize_buffer(struct st_buffer *);
182 static int append_to_buffer(const char __user *, struct st_buffer *, int);
183 static int from_buffer(struct st_buffer *, char __user *, int);
184 static void move_buffer_data(struct st_buffer *, int);
185 
186 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
187 			      unsigned long, size_t, int);
188 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
189 
190 static int st_probe(struct device *);
191 static int st_remove(struct device *);
192 
193 static int do_create_sysfs_files(void);
194 static void do_remove_sysfs_files(void);
195 
196 static struct scsi_driver st_template = {
197 	.owner			= THIS_MODULE,
198 	.gendrv = {
199 		.name		= "st",
200 		.probe		= st_probe,
201 		.remove		= st_remove,
202 	},
203 };
204 
205 static int st_compression(struct scsi_tape *, int);
206 
207 static int find_partition(struct scsi_tape *);
208 static int switch_partition(struct scsi_tape *);
209 
210 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
211 
212 static void scsi_tape_release(struct kref *);
213 
214 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
215 
216 static DEFINE_MUTEX(st_ref_mutex);
217 static DEFINE_SPINLOCK(st_index_lock);
218 static DEFINE_SPINLOCK(st_use_lock);
219 static DEFINE_IDR(st_index_idr);
220 
221 
222 
223 #include "osst_detect.h"
224 #ifndef SIGS_FROM_OSST
225 #define SIGS_FROM_OSST \
226 	{"OnStream", "SC-", "", "osst"}, \
227 	{"OnStream", "DI-", "", "osst"}, \
228 	{"OnStream", "DP-", "", "osst"}, \
229 	{"OnStream", "USB", "", "osst"}, \
230 	{"OnStream", "FW-", "", "osst"}
231 #endif
232 
233 static struct scsi_tape *scsi_tape_get(int dev)
234 {
235 	struct scsi_tape *STp = NULL;
236 
237 	mutex_lock(&st_ref_mutex);
238 	spin_lock(&st_index_lock);
239 
240 	STp = idr_find(&st_index_idr, dev);
241 	if (!STp) goto out;
242 
243 	kref_get(&STp->kref);
244 
245 	if (!STp->device)
246 		goto out_put;
247 
248 	if (scsi_device_get(STp->device))
249 		goto out_put;
250 
251 	goto out;
252 
253 out_put:
254 	kref_put(&STp->kref, scsi_tape_release);
255 	STp = NULL;
256 out:
257 	spin_unlock(&st_index_lock);
258 	mutex_unlock(&st_ref_mutex);
259 	return STp;
260 }
261 
262 static void scsi_tape_put(struct scsi_tape *STp)
263 {
264 	struct scsi_device *sdev = STp->device;
265 
266 	mutex_lock(&st_ref_mutex);
267 	kref_put(&STp->kref, scsi_tape_release);
268 	scsi_device_put(sdev);
269 	mutex_unlock(&st_ref_mutex);
270 }
271 
272 struct st_reject_data {
273 	char *vendor;
274 	char *model;
275 	char *rev;
276 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
277 };
278 
279 static struct st_reject_data reject_list[] = {
280 	/* {"XXX", "Yy-", "", NULL},  example */
281 	SIGS_FROM_OSST,
282 	{NULL, }};
283 
284 /* If the device signature is on the list of incompatible drives, the
285    function returns a pointer to the name of the correct driver (if known) */
286 static char * st_incompatible(struct scsi_device* SDp)
287 {
288 	struct st_reject_data *rp;
289 
290 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
291 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
292 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
293 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
294 			if (rp->driver_hint)
295 				return rp->driver_hint;
296 			else
297 				return "unknown";
298 		}
299 	return NULL;
300 }
301 
302 
303 static inline char *tape_name(struct scsi_tape *tape)
304 {
305 	return tape->disk->disk_name;
306 }
307 
308 
309 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
310 {
311 	const u8 *ucp;
312 	const u8 *sense = SRpnt->sense;
313 
314 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
315 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
316 	s->flags = 0;
317 
318 	if (s->have_sense) {
319 		s->deferred = 0;
320 		s->remainder_valid =
321 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
322 		switch (sense[0] & 0x7f) {
323 		case 0x71:
324 			s->deferred = 1;
325 		case 0x70:
326 			s->fixed_format = 1;
327 			s->flags = sense[2] & 0xe0;
328 			break;
329 		case 0x73:
330 			s->deferred = 1;
331 		case 0x72:
332 			s->fixed_format = 0;
333 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
334 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
335 			break;
336 		}
337 	}
338 }
339 
340 
341 /* Convert the result to success code */
342 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
343 {
344 	int result = SRpnt->result;
345 	u8 scode;
346 	DEB(const char *stp;)
347 	char *name = tape_name(STp);
348 	struct st_cmdstatus *cmdstatp;
349 
350 	if (!result)
351 		return 0;
352 
353 	cmdstatp = &STp->buffer->cmdstat;
354 	st_analyze_sense(SRpnt, cmdstatp);
355 
356 	if (cmdstatp->have_sense)
357 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
358 	else
359 		scode = 0;
360 
361         DEB(
362         if (debugging) {
363                 printk(ST_DEB_MSG "%s: Error: %x, cmd: %x %x %x %x %x %x\n",
364 		       name, result,
365 		       SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
366 		       SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
367 		if (cmdstatp->have_sense)
368 			 __scsi_print_sense(name, SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
369 	} ) /* end DEB */
370 	if (!debugging) { /* Abnormal conditions for tape */
371 		if (!cmdstatp->have_sense)
372 			printk(KERN_WARNING
373 			       "%s: Error %x (driver bt 0x%x, host bt 0x%x).\n",
374 			       name, result, driver_byte(result),
375 			       host_byte(result));
376 		else if (cmdstatp->have_sense &&
377 			 scode != NO_SENSE &&
378 			 scode != RECOVERED_ERROR &&
379 			 /* scode != UNIT_ATTENTION && */
380 			 scode != BLANK_CHECK &&
381 			 scode != VOLUME_OVERFLOW &&
382 			 SRpnt->cmd[0] != MODE_SENSE &&
383 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
384 
385 			__scsi_print_sense(name, SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
386 		}
387 	}
388 
389 	if (cmdstatp->fixed_format &&
390 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
391 		if (STp->cln_sense_value)
392 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
393 					       STp->cln_sense_mask) == STp->cln_sense_value);
394 		else
395 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
396 					       STp->cln_sense_mask) != 0);
397 	}
398 	if (cmdstatp->have_sense &&
399 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
400 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
401 
402 	STp->pos_unknown |= STp->device->was_reset;
403 
404 	if (cmdstatp->have_sense &&
405 	    scode == RECOVERED_ERROR
406 #if ST_RECOVERED_WRITE_FATAL
407 	    && SRpnt->cmd[0] != WRITE_6
408 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
409 #endif
410 	    ) {
411 		STp->recover_count++;
412 		STp->recover_reg++;
413 
414                 DEB(
415 		if (debugging) {
416 			if (SRpnt->cmd[0] == READ_6)
417 				stp = "read";
418 			else if (SRpnt->cmd[0] == WRITE_6)
419 				stp = "write";
420 			else
421 				stp = "ioctl";
422 			printk(ST_DEB_MSG "%s: Recovered %s error (%d).\n", name, stp,
423 			       STp->recover_count);
424 		} ) /* end DEB */
425 
426 		if (cmdstatp->flags == 0)
427 			return 0;
428 	}
429 	return (-EIO);
430 }
431 
432 static struct st_request *st_allocate_request(struct scsi_tape *stp)
433 {
434 	struct st_request *streq;
435 
436 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
437 	if (streq)
438 		streq->stp = stp;
439 	else {
440 		DEBC(printk(KERN_ERR "%s: Can't get SCSI request.\n",
441 			    tape_name(stp)););
442 		if (signal_pending(current))
443 			stp->buffer->syscall_result = -EINTR;
444 		else
445 			stp->buffer->syscall_result = -EBUSY;
446 	}
447 
448 	return streq;
449 }
450 
451 static void st_release_request(struct st_request *streq)
452 {
453 	kfree(streq);
454 }
455 
456 static void st_scsi_execute_end(struct request *req, int uptodate)
457 {
458 	struct st_request *SRpnt = req->end_io_data;
459 	struct scsi_tape *STp = SRpnt->stp;
460 	struct bio *tmp;
461 
462 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors;
463 	STp->buffer->cmdstat.residual = req->resid_len;
464 
465 	tmp = SRpnt->bio;
466 	if (SRpnt->waiting)
467 		complete(SRpnt->waiting);
468 
469 	blk_rq_unmap_user(tmp);
470 	__blk_put_request(req->q, req);
471 }
472 
473 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
474 			   int data_direction, void *buffer, unsigned bufflen,
475 			   int timeout, int retries)
476 {
477 	struct request *req;
478 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
479 	int err = 0;
480 	int write = (data_direction == DMA_TO_DEVICE);
481 
482 	req = blk_get_request(SRpnt->stp->device->request_queue, write,
483 			      GFP_KERNEL);
484 	if (!req)
485 		return DRIVER_ERROR << 24;
486 
487 	req->cmd_type = REQ_TYPE_BLOCK_PC;
488 	req->cmd_flags |= REQ_QUIET;
489 
490 	mdata->null_mapped = 1;
491 
492 	if (bufflen) {
493 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
494 				      GFP_KERNEL);
495 		if (err) {
496 			blk_put_request(req);
497 			return DRIVER_ERROR << 24;
498 		}
499 	}
500 
501 	SRpnt->bio = req->bio;
502 	req->cmd_len = COMMAND_SIZE(cmd[0]);
503 	memset(req->cmd, 0, BLK_MAX_CDB);
504 	memcpy(req->cmd, cmd, req->cmd_len);
505 	req->sense = SRpnt->sense;
506 	req->sense_len = 0;
507 	req->timeout = timeout;
508 	req->retries = retries;
509 	req->end_io_data = SRpnt;
510 
511 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
512 	return 0;
513 }
514 
515 /* Do the scsi command. Waits until command performed if do_wait is true.
516    Otherwise write_behind_check() is used to check that the command
517    has finished. */
518 static struct st_request *
519 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
520 	   int bytes, int direction, int timeout, int retries, int do_wait)
521 {
522 	struct completion *waiting;
523 	struct rq_map_data *mdata = &STp->buffer->map_data;
524 	int ret;
525 
526 	/* if async, make sure there's no command outstanding */
527 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
528 		printk(KERN_ERR "%s: Async command already active.\n",
529 		       tape_name(STp));
530 		if (signal_pending(current))
531 			(STp->buffer)->syscall_result = (-EINTR);
532 		else
533 			(STp->buffer)->syscall_result = (-EBUSY);
534 		return NULL;
535 	}
536 
537 	if (!SRpnt) {
538 		SRpnt = st_allocate_request(STp);
539 		if (!SRpnt)
540 			return NULL;
541 	}
542 
543 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
544 	   which IO is outstanding. It's nulled out when the IO completes. */
545 	if (!do_wait)
546 		(STp->buffer)->last_SRpnt = SRpnt;
547 
548 	waiting = &STp->wait;
549 	init_completion(waiting);
550 	SRpnt->waiting = waiting;
551 
552 	if (STp->buffer->do_dio) {
553 		mdata->page_order = 0;
554 		mdata->nr_entries = STp->buffer->sg_segs;
555 		mdata->pages = STp->buffer->mapped_pages;
556 	} else {
557 		mdata->page_order = STp->buffer->reserved_page_order;
558 		mdata->nr_entries =
559 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
560 		mdata->pages = STp->buffer->reserved_pages;
561 		mdata->offset = 0;
562 	}
563 
564 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
565 	STp->buffer->cmdstat.have_sense = 0;
566 	STp->buffer->syscall_result = 0;
567 
568 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
569 			      retries);
570 	if (ret) {
571 		/* could not allocate the buffer or request was too large */
572 		(STp->buffer)->syscall_result = (-EBUSY);
573 		(STp->buffer)->last_SRpnt = NULL;
574 	} else if (do_wait) {
575 		wait_for_completion(waiting);
576 		SRpnt->waiting = NULL;
577 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
578 	}
579 
580 	return SRpnt;
581 }
582 
583 
584 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
585    write has been correct but EOM early warning reached, -EIO if write ended in
586    error or zero if write successful. Asynchronous writes are used only in
587    variable block mode. */
588 static int write_behind_check(struct scsi_tape * STp)
589 {
590 	int retval = 0;
591 	struct st_buffer *STbuffer;
592 	struct st_partstat *STps;
593 	struct st_cmdstatus *cmdstatp;
594 	struct st_request *SRpnt;
595 
596 	STbuffer = STp->buffer;
597 	if (!STbuffer->writing)
598 		return 0;
599 
600         DEB(
601 	if (STp->write_pending)
602 		STp->nbr_waits++;
603 	else
604 		STp->nbr_finished++;
605         ) /* end DEB */
606 
607 	wait_for_completion(&(STp->wait));
608 	SRpnt = STbuffer->last_SRpnt;
609 	STbuffer->last_SRpnt = NULL;
610 	SRpnt->waiting = NULL;
611 
612 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
613 	st_release_request(SRpnt);
614 
615 	STbuffer->buffer_bytes -= STbuffer->writing;
616 	STps = &(STp->ps[STp->partition]);
617 	if (STps->drv_block >= 0) {
618 		if (STp->block_size == 0)
619 			STps->drv_block++;
620 		else
621 			STps->drv_block += STbuffer->writing / STp->block_size;
622 	}
623 
624 	cmdstatp = &STbuffer->cmdstat;
625 	if (STbuffer->syscall_result) {
626 		retval = -EIO;
627 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
628 		    (cmdstatp->flags & SENSE_EOM) &&
629 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
630 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
631 			/* EOM at write-behind, has all data been written? */
632 			if (!cmdstatp->remainder_valid ||
633 			    cmdstatp->uremainder64 == 0)
634 				retval = -ENOSPC;
635 		}
636 		if (retval == -EIO)
637 			STps->drv_block = -1;
638 	}
639 	STbuffer->writing = 0;
640 
641 	DEB(if (debugging && retval)
642 	    printk(ST_DEB_MSG "%s: Async write error %x, return value %d.\n",
643 		   tape_name(STp), STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
644 
645 	return retval;
646 }
647 
648 
649 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
650    it messes up the block number). */
651 static int cross_eof(struct scsi_tape * STp, int forward)
652 {
653 	struct st_request *SRpnt;
654 	unsigned char cmd[MAX_COMMAND_SIZE];
655 
656 	cmd[0] = SPACE;
657 	cmd[1] = 0x01;		/* Space FileMarks */
658 	if (forward) {
659 		cmd[2] = cmd[3] = 0;
660 		cmd[4] = 1;
661 	} else
662 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
663 	cmd[5] = 0;
664 
665         DEBC(printk(ST_DEB_MSG "%s: Stepping over filemark %s.\n",
666 		   tape_name(STp), forward ? "forward" : "backward"));
667 
668 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
669 			   STp->device->request_queue->rq_timeout,
670 			   MAX_RETRIES, 1);
671 	if (!SRpnt)
672 		return (STp->buffer)->syscall_result;
673 
674 	st_release_request(SRpnt);
675 	SRpnt = NULL;
676 
677 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
678 		printk(KERN_ERR "%s: Stepping over filemark %s failed.\n",
679 		   tape_name(STp), forward ? "forward" : "backward");
680 
681 	return (STp->buffer)->syscall_result;
682 }
683 
684 
685 /* Flush the write buffer (never need to write if variable blocksize). */
686 static int st_flush_write_buffer(struct scsi_tape * STp)
687 {
688 	int transfer, blks;
689 	int result;
690 	unsigned char cmd[MAX_COMMAND_SIZE];
691 	struct st_request *SRpnt;
692 	struct st_partstat *STps;
693 
694 	result = write_behind_check(STp);
695 	if (result)
696 		return result;
697 
698 	result = 0;
699 	if (STp->dirty == 1) {
700 
701 		transfer = STp->buffer->buffer_bytes;
702                 DEBC(printk(ST_DEB_MSG "%s: Flushing %d bytes.\n",
703                                tape_name(STp), transfer));
704 
705 		memset(cmd, 0, MAX_COMMAND_SIZE);
706 		cmd[0] = WRITE_6;
707 		cmd[1] = 1;
708 		blks = transfer / STp->block_size;
709 		cmd[2] = blks >> 16;
710 		cmd[3] = blks >> 8;
711 		cmd[4] = blks;
712 
713 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
714 				   STp->device->request_queue->rq_timeout,
715 				   MAX_WRITE_RETRIES, 1);
716 		if (!SRpnt)
717 			return (STp->buffer)->syscall_result;
718 
719 		STps = &(STp->ps[STp->partition]);
720 		if ((STp->buffer)->syscall_result != 0) {
721 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
722 
723 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
724 			    (cmdstatp->flags & SENSE_EOM) &&
725 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
726 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
727 			    (!cmdstatp->remainder_valid ||
728 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
729 				STp->dirty = 0;
730 				(STp->buffer)->buffer_bytes = 0;
731 				if (STps->drv_block >= 0)
732 					STps->drv_block += blks;
733 				result = (-ENOSPC);
734 			} else {
735 				printk(KERN_ERR "%s: Error on flush.\n",
736                                        tape_name(STp));
737 				STps->drv_block = (-1);
738 				result = (-EIO);
739 			}
740 		} else {
741 			if (STps->drv_block >= 0)
742 				STps->drv_block += blks;
743 			STp->dirty = 0;
744 			(STp->buffer)->buffer_bytes = 0;
745 		}
746 		st_release_request(SRpnt);
747 		SRpnt = NULL;
748 	}
749 	return result;
750 }
751 
752 
753 /* Flush the tape buffer. The tape will be positioned correctly unless
754    seek_next is true. */
755 static int flush_buffer(struct scsi_tape *STp, int seek_next)
756 {
757 	int backspace, result;
758 	struct st_buffer *STbuffer;
759 	struct st_partstat *STps;
760 
761 	STbuffer = STp->buffer;
762 
763 	/*
764 	 * If there was a bus reset, block further access
765 	 * to this device.
766 	 */
767 	if (STp->pos_unknown)
768 		return (-EIO);
769 
770 	if (STp->ready != ST_READY)
771 		return 0;
772 	STps = &(STp->ps[STp->partition]);
773 	if (STps->rw == ST_WRITING)	/* Writing */
774 		return st_flush_write_buffer(STp);
775 
776 	if (STp->block_size == 0)
777 		return 0;
778 
779 	backspace = ((STp->buffer)->buffer_bytes +
780 		     (STp->buffer)->read_pointer) / STp->block_size -
781 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
782 	    STp->block_size;
783 	(STp->buffer)->buffer_bytes = 0;
784 	(STp->buffer)->read_pointer = 0;
785 	result = 0;
786 	if (!seek_next) {
787 		if (STps->eof == ST_FM_HIT) {
788 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
789 			if (!result)
790 				STps->eof = ST_NOEOF;
791 			else {
792 				if (STps->drv_file >= 0)
793 					STps->drv_file++;
794 				STps->drv_block = 0;
795 			}
796 		}
797 		if (!result && backspace > 0)
798 			result = st_int_ioctl(STp, MTBSR, backspace);
799 	} else if (STps->eof == ST_FM_HIT) {
800 		if (STps->drv_file >= 0)
801 			STps->drv_file++;
802 		STps->drv_block = 0;
803 		STps->eof = ST_NOEOF;
804 	}
805 	return result;
806 
807 }
808 
809 /* Set the mode parameters */
810 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
811 {
812 	int set_it = 0;
813 	unsigned long arg;
814 	char *name = tape_name(STp);
815 
816 	if (!STp->density_changed &&
817 	    STm->default_density >= 0 &&
818 	    STm->default_density != STp->density) {
819 		arg = STm->default_density;
820 		set_it = 1;
821 	} else
822 		arg = STp->density;
823 	arg <<= MT_ST_DENSITY_SHIFT;
824 	if (!STp->blksize_changed &&
825 	    STm->default_blksize >= 0 &&
826 	    STm->default_blksize != STp->block_size) {
827 		arg |= STm->default_blksize;
828 		set_it = 1;
829 	} else
830 		arg |= STp->block_size;
831 	if (set_it &&
832 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
833 		printk(KERN_WARNING
834 		       "%s: Can't set default block size to %d bytes and density %x.\n",
835 		       name, STm->default_blksize, STm->default_density);
836 		if (modes_defined)
837 			return (-EINVAL);
838 	}
839 	return 0;
840 }
841 
842 
843 /* Lock or unlock the drive door. Don't use when st_request allocated. */
844 static int do_door_lock(struct scsi_tape * STp, int do_lock)
845 {
846 	int retval, cmd;
847 	DEB(char *name = tape_name(STp);)
848 
849 
850 	cmd = do_lock ? SCSI_IOCTL_DOORLOCK : SCSI_IOCTL_DOORUNLOCK;
851 	DEBC(printk(ST_DEB_MSG "%s: %socking drive door.\n", name,
852 		    do_lock ? "L" : "Unl"));
853 	retval = scsi_ioctl(STp->device, cmd, NULL);
854 	if (!retval) {
855 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
856 	}
857 	else {
858 		STp->door_locked = ST_LOCK_FAILS;
859 	}
860 	return retval;
861 }
862 
863 
864 /* Set the internal state after reset */
865 static void reset_state(struct scsi_tape *STp)
866 {
867 	int i;
868 	struct st_partstat *STps;
869 
870 	STp->pos_unknown = 0;
871 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
872 		STps = &(STp->ps[i]);
873 		STps->rw = ST_IDLE;
874 		STps->eof = ST_NOEOF;
875 		STps->at_sm = 0;
876 		STps->last_block_valid = 0;
877 		STps->drv_block = -1;
878 		STps->drv_file = -1;
879 	}
880 	if (STp->can_partitions) {
881 		STp->partition = find_partition(STp);
882 		if (STp->partition < 0)
883 			STp->partition = 0;
884 		STp->new_partition = STp->partition;
885 	}
886 }
887 
888 /* Test if the drive is ready. Returns either one of the codes below or a negative system
889    error code. */
890 #define CHKRES_READY       0
891 #define CHKRES_NEW_SESSION 1
892 #define CHKRES_NOT_READY   2
893 #define CHKRES_NO_TAPE     3
894 
895 #define MAX_ATTENTIONS    10
896 
897 static int test_ready(struct scsi_tape *STp, int do_wait)
898 {
899 	int attentions, waits, max_wait, scode;
900 	int retval = CHKRES_READY, new_session = 0;
901 	unsigned char cmd[MAX_COMMAND_SIZE];
902 	struct st_request *SRpnt = NULL;
903 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
904 
905 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
906 
907 	for (attentions=waits=0; ; ) {
908 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
909 		cmd[0] = TEST_UNIT_READY;
910 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
911 				   STp->long_timeout, MAX_READY_RETRIES, 1);
912 
913 		if (!SRpnt) {
914 			retval = (STp->buffer)->syscall_result;
915 			break;
916 		}
917 
918 		if (cmdstatp->have_sense) {
919 
920 			scode = cmdstatp->sense_hdr.sense_key;
921 
922 			if (scode == UNIT_ATTENTION) { /* New media? */
923 				new_session = 1;
924 				if (attentions < MAX_ATTENTIONS) {
925 					attentions++;
926 					continue;
927 				}
928 				else {
929 					retval = (-EIO);
930 					break;
931 				}
932 			}
933 
934 			if (scode == NOT_READY) {
935 				if (waits < max_wait) {
936 					if (msleep_interruptible(1000)) {
937 						retval = (-EINTR);
938 						break;
939 					}
940 					waits++;
941 					continue;
942 				}
943 				else {
944 					if ((STp->device)->scsi_level >= SCSI_2 &&
945 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
946 						retval = CHKRES_NO_TAPE;
947 					else
948 						retval = CHKRES_NOT_READY;
949 					break;
950 				}
951 			}
952 		}
953 
954 		retval = (STp->buffer)->syscall_result;
955 		if (!retval)
956 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
957 		break;
958 	}
959 
960 	if (SRpnt != NULL)
961 		st_release_request(SRpnt);
962 	return retval;
963 }
964 
965 
966 /* See if the drive is ready and gather information about the tape. Return values:
967    < 0   negative error code from errno.h
968    0     drive ready
969    1     drive not ready (possibly no tape)
970 */
971 static int check_tape(struct scsi_tape *STp, struct file *filp)
972 {
973 	int i, retval, new_session = 0, do_wait;
974 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
975 	unsigned short st_flags = filp->f_flags;
976 	struct st_request *SRpnt = NULL;
977 	struct st_modedef *STm;
978 	struct st_partstat *STps;
979 	char *name = tape_name(STp);
980 	struct inode *inode = filp->f_path.dentry->d_inode;
981 	int mode = TAPE_MODE(inode);
982 
983 	STp->ready = ST_READY;
984 
985 	if (mode != STp->current_mode) {
986                 DEBC(printk(ST_DEB_MSG "%s: Mode change from %d to %d.\n",
987 			       name, STp->current_mode, mode));
988 		new_session = 1;
989 		STp->current_mode = mode;
990 	}
991 	STm = &(STp->modes[STp->current_mode]);
992 
993 	saved_cleaning = STp->cleaning_req;
994 	STp->cleaning_req = 0;
995 
996 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
997 	retval = test_ready(STp, do_wait);
998 
999 	if (retval < 0)
1000 	    goto err_out;
1001 
1002 	if (retval == CHKRES_NEW_SESSION) {
1003 		STp->pos_unknown = 0;
1004 		STp->partition = STp->new_partition = 0;
1005 		if (STp->can_partitions)
1006 			STp->nbr_partitions = 1; /* This guess will be updated later
1007                                                     if necessary */
1008 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1009 			STps = &(STp->ps[i]);
1010 			STps->rw = ST_IDLE;
1011 			STps->eof = ST_NOEOF;
1012 			STps->at_sm = 0;
1013 			STps->last_block_valid = 0;
1014 			STps->drv_block = 0;
1015 			STps->drv_file = 0;
1016 		}
1017 		new_session = 1;
1018 	}
1019 	else {
1020 		STp->cleaning_req |= saved_cleaning;
1021 
1022 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1023 			if (retval == CHKRES_NO_TAPE)
1024 				STp->ready = ST_NO_TAPE;
1025 			else
1026 				STp->ready = ST_NOT_READY;
1027 
1028 			STp->density = 0;	/* Clear the erroneous "residue" */
1029 			STp->write_prot = 0;
1030 			STp->block_size = 0;
1031 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1032 			STp->partition = STp->new_partition = 0;
1033 			STp->door_locked = ST_UNLOCKED;
1034 			return CHKRES_NOT_READY;
1035 		}
1036 	}
1037 
1038 	if (STp->omit_blklims)
1039 		STp->min_block = STp->max_block = (-1);
1040 	else {
1041 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1042 		cmd[0] = READ_BLOCK_LIMITS;
1043 
1044 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1045 				   STp->device->request_queue->rq_timeout,
1046 				   MAX_READY_RETRIES, 1);
1047 		if (!SRpnt) {
1048 			retval = (STp->buffer)->syscall_result;
1049 			goto err_out;
1050 		}
1051 
1052 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1053 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1054 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1055 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1056 			    (STp->buffer)->b_data[5];
1057 			if ( DEB( debugging || ) !STp->inited)
1058 				printk(KERN_INFO
1059                                        "%s: Block limits %d - %d bytes.\n", name,
1060                                        STp->min_block, STp->max_block);
1061 		} else {
1062 			STp->min_block = STp->max_block = (-1);
1063                         DEBC(printk(ST_DEB_MSG "%s: Can't read block limits.\n",
1064                                        name));
1065 		}
1066 	}
1067 
1068 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1069 	cmd[0] = MODE_SENSE;
1070 	cmd[4] = 12;
1071 
1072 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1073 			   STp->device->request_queue->rq_timeout,
1074 			   MAX_READY_RETRIES, 1);
1075 	if (!SRpnt) {
1076 		retval = (STp->buffer)->syscall_result;
1077 		goto err_out;
1078 	}
1079 
1080 	if ((STp->buffer)->syscall_result != 0) {
1081                 DEBC(printk(ST_DEB_MSG "%s: No Mode Sense.\n", name));
1082 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1083 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1084 		STp->drv_write_prot = 0;
1085 	} else {
1086                 DEBC(printk(ST_DEB_MSG
1087                             "%s: Mode sense. Length %d, medium %x, WBS %x, BLL %d\n",
1088                             name,
1089                             (STp->buffer)->b_data[0], (STp->buffer)->b_data[1],
1090                             (STp->buffer)->b_data[2], (STp->buffer)->b_data[3]));
1091 
1092 		if ((STp->buffer)->b_data[3] >= 8) {
1093 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1094 			STp->density = (STp->buffer)->b_data[4];
1095 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1096 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1097                         DEBC(printk(ST_DEB_MSG
1098                                     "%s: Density %x, tape length: %x, drv buffer: %d\n",
1099                                     name, STp->density, (STp->buffer)->b_data[5] * 65536 +
1100                                     (STp->buffer)->b_data[6] * 256 + (STp->buffer)->b_data[7],
1101                                     STp->drv_buffer));
1102 		}
1103 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1104 		if (!STp->drv_buffer && STp->immediate_filemark) {
1105 			printk(KERN_WARNING
1106 			    "%s: non-buffered tape: disabling writing immediate filemarks\n",
1107 			    name);
1108 			STp->immediate_filemark = 0;
1109 		}
1110 	}
1111 	st_release_request(SRpnt);
1112 	SRpnt = NULL;
1113         STp->inited = 1;
1114 
1115 	if (STp->block_size > 0)
1116 		(STp->buffer)->buffer_blocks =
1117                         (STp->buffer)->buffer_size / STp->block_size;
1118 	else
1119 		(STp->buffer)->buffer_blocks = 1;
1120 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1121 
1122         DEBC(printk(ST_DEB_MSG
1123                        "%s: Block size: %d, buffer size: %d (%d blocks).\n", name,
1124 		       STp->block_size, (STp->buffer)->buffer_size,
1125 		       (STp->buffer)->buffer_blocks));
1126 
1127 	if (STp->drv_write_prot) {
1128 		STp->write_prot = 1;
1129 
1130                 DEBC(printk(ST_DEB_MSG "%s: Write protected\n", name));
1131 
1132 		if (do_wait &&
1133 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1134 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1135 			retval = (-EROFS);
1136 			goto err_out;
1137 		}
1138 	}
1139 
1140 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1141 		/* This code is reached when the device is opened for the first time
1142 		   after the driver has been initialized with tape in the drive and the
1143 		   partition support has been enabled. */
1144                 DEBC(printk(ST_DEB_MSG
1145                             "%s: Updating partition number in status.\n", name));
1146 		if ((STp->partition = find_partition(STp)) < 0) {
1147 			retval = STp->partition;
1148 			goto err_out;
1149 		}
1150 		STp->new_partition = STp->partition;
1151 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1152 	}
1153 
1154 	if (new_session) {	/* Change the drive parameters for the new mode */
1155 		STp->density_changed = STp->blksize_changed = 0;
1156 		STp->compression_changed = 0;
1157 		if (!(STm->defaults_for_writes) &&
1158 		    (retval = set_mode_densblk(STp, STm)) < 0)
1159 		    goto err_out;
1160 
1161 		if (STp->default_drvbuffer != 0xff) {
1162 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1163 				printk(KERN_WARNING
1164                                        "%s: Can't set default drive buffering to %d.\n",
1165 				       name, STp->default_drvbuffer);
1166 		}
1167 	}
1168 
1169 	return CHKRES_READY;
1170 
1171  err_out:
1172 	return retval;
1173 }
1174 
1175 
1176 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1177    module count. */
1178 static int st_open(struct inode *inode, struct file *filp)
1179 {
1180 	int i, retval = (-EIO);
1181 	int resumed = 0;
1182 	struct scsi_tape *STp;
1183 	struct st_partstat *STps;
1184 	int dev = TAPE_NR(inode);
1185 	char *name;
1186 
1187 	/*
1188 	 * We really want to do nonseekable_open(inode, filp); here, but some
1189 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1190 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1191 	 */
1192 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1193 
1194 	if (!(STp = scsi_tape_get(dev))) {
1195 		return -ENXIO;
1196 	}
1197 
1198 	filp->private_data = STp;
1199 	name = tape_name(STp);
1200 
1201 	spin_lock(&st_use_lock);
1202 	if (STp->in_use) {
1203 		spin_unlock(&st_use_lock);
1204 		scsi_tape_put(STp);
1205 		DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
1206 		return (-EBUSY);
1207 	}
1208 
1209 	STp->in_use = 1;
1210 	spin_unlock(&st_use_lock);
1211 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1212 
1213 	if (scsi_autopm_get_device(STp->device) < 0) {
1214 		retval = -EIO;
1215 		goto err_out;
1216 	}
1217 	resumed = 1;
1218 	if (!scsi_block_when_processing_errors(STp->device)) {
1219 		retval = (-ENXIO);
1220 		goto err_out;
1221 	}
1222 
1223 	/* See that we have at least a one page buffer available */
1224 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
1225 		printk(KERN_WARNING "%s: Can't allocate one page tape buffer.\n",
1226 		       name);
1227 		retval = (-EOVERFLOW);
1228 		goto err_out;
1229 	}
1230 
1231 	(STp->buffer)->cleared = 0;
1232 	(STp->buffer)->writing = 0;
1233 	(STp->buffer)->syscall_result = 0;
1234 
1235 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1236 
1237 	STp->dirty = 0;
1238 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1239 		STps = &(STp->ps[i]);
1240 		STps->rw = ST_IDLE;
1241 	}
1242 	STp->try_dio_now = STp->try_dio;
1243 	STp->recover_count = 0;
1244 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1245 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1246 
1247 	retval = check_tape(STp, filp);
1248 	if (retval < 0)
1249 		goto err_out;
1250 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1251 	    retval != CHKRES_READY) {
1252 		if (STp->ready == NO_TAPE)
1253 			retval = (-ENOMEDIUM);
1254 		else
1255 			retval = (-EIO);
1256 		goto err_out;
1257 	}
1258 	return 0;
1259 
1260  err_out:
1261 	normalize_buffer(STp->buffer);
1262 	spin_lock(&st_use_lock);
1263 	STp->in_use = 0;
1264 	spin_unlock(&st_use_lock);
1265 	scsi_tape_put(STp);
1266 	if (resumed)
1267 		scsi_autopm_put_device(STp->device);
1268 	return retval;
1269 
1270 }
1271 
1272 
1273 /* Flush the tape buffer before close */
1274 static int st_flush(struct file *filp, fl_owner_t id)
1275 {
1276 	int result = 0, result2;
1277 	unsigned char cmd[MAX_COMMAND_SIZE];
1278 	struct st_request *SRpnt;
1279 	struct scsi_tape *STp = filp->private_data;
1280 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1281 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1282 	char *name = tape_name(STp);
1283 
1284 	if (file_count(filp) > 1)
1285 		return 0;
1286 
1287 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1288 		result = st_flush_write_buffer(STp);
1289 		if (result != 0 && result != (-ENOSPC))
1290 			goto out;
1291 	}
1292 
1293 	if (STp->can_partitions &&
1294 	    (result2 = switch_partition(STp)) < 0) {
1295                 DEBC(printk(ST_DEB_MSG
1296                                "%s: switch_partition at close failed.\n", name));
1297 		if (result == 0)
1298 			result = result2;
1299 		goto out;
1300 	}
1301 
1302 	DEBC( if (STp->nbr_requests)
1303 		printk(KERN_DEBUG "%s: Number of r/w requests %d, dio used in %d, pages %d.\n",
1304 		       name, STp->nbr_requests, STp->nbr_dio, STp->nbr_pages));
1305 
1306 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1307 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1308 
1309                 DEBC(printk(ST_DEB_MSG "%s: Async write waits %d, finished %d.\n",
1310                             name, STp->nbr_waits, STp->nbr_finished);
1311 		)
1312 
1313 		memset(cmd, 0, MAX_COMMAND_SIZE);
1314 		cmd[0] = WRITE_FILEMARKS;
1315 		if (STp->immediate_filemark)
1316 			cmd[1] = 1;
1317 		cmd[4] = 1 + STp->two_fm;
1318 
1319 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1320 				   STp->device->request_queue->rq_timeout,
1321 				   MAX_WRITE_RETRIES, 1);
1322 		if (!SRpnt) {
1323 			result = (STp->buffer)->syscall_result;
1324 			goto out;
1325 		}
1326 
1327 		if (STp->buffer->syscall_result == 0 ||
1328 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1329 		     (cmdstatp->flags & SENSE_EOM) &&
1330 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1331 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1332 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1333 			/* Write successful at EOM */
1334 			st_release_request(SRpnt);
1335 			SRpnt = NULL;
1336 			if (STps->drv_file >= 0)
1337 				STps->drv_file++;
1338 			STps->drv_block = 0;
1339 			if (STp->two_fm)
1340 				cross_eof(STp, 0);
1341 			STps->eof = ST_FM;
1342 		}
1343 		else { /* Write error */
1344 			st_release_request(SRpnt);
1345 			SRpnt = NULL;
1346 			printk(KERN_ERR "%s: Error on write filemark.\n", name);
1347 			if (result == 0)
1348 				result = (-EIO);
1349 		}
1350 
1351                 DEBC(printk(ST_DEB_MSG "%s: Buffer flushed, %d EOF(s) written\n",
1352                             name, cmd[4]));
1353 	} else if (!STp->rew_at_close) {
1354 		STps = &(STp->ps[STp->partition]);
1355 		if (!STm->sysv || STps->rw != ST_READING) {
1356 			if (STp->can_bsr)
1357 				result = flush_buffer(STp, 0);
1358 			else if (STps->eof == ST_FM_HIT) {
1359 				result = cross_eof(STp, 0);
1360 				if (result) {
1361 					if (STps->drv_file >= 0)
1362 						STps->drv_file++;
1363 					STps->drv_block = 0;
1364 					STps->eof = ST_FM;
1365 				} else
1366 					STps->eof = ST_NOEOF;
1367 			}
1368 		} else if ((STps->eof == ST_NOEOF &&
1369 			    !(result = cross_eof(STp, 1))) ||
1370 			   STps->eof == ST_FM_HIT) {
1371 			if (STps->drv_file >= 0)
1372 				STps->drv_file++;
1373 			STps->drv_block = 0;
1374 			STps->eof = ST_FM;
1375 		}
1376 	}
1377 
1378       out:
1379 	if (STp->rew_at_close) {
1380 		result2 = st_int_ioctl(STp, MTREW, 1);
1381 		if (result == 0)
1382 			result = result2;
1383 	}
1384 	return result;
1385 }
1386 
1387 
1388 /* Close the device and release it. BKL is not needed: this is the only thread
1389    accessing this tape. */
1390 static int st_release(struct inode *inode, struct file *filp)
1391 {
1392 	int result = 0;
1393 	struct scsi_tape *STp = filp->private_data;
1394 
1395 	if (STp->door_locked == ST_LOCKED_AUTO)
1396 		do_door_lock(STp, 0);
1397 
1398 	normalize_buffer(STp->buffer);
1399 	spin_lock(&st_use_lock);
1400 	STp->in_use = 0;
1401 	spin_unlock(&st_use_lock);
1402 	scsi_autopm_put_device(STp->device);
1403 	scsi_tape_put(STp);
1404 
1405 	return result;
1406 }
1407 
1408 /* The checks common to both reading and writing */
1409 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1410 {
1411 	ssize_t retval = 0;
1412 
1413 	/*
1414 	 * If we are in the middle of error recovery, don't let anyone
1415 	 * else try and use this device.  Also, if error recovery fails, it
1416 	 * may try and take the device offline, in which case all further
1417 	 * access to the device is prohibited.
1418 	 */
1419 	if (!scsi_block_when_processing_errors(STp->device)) {
1420 		retval = (-ENXIO);
1421 		goto out;
1422 	}
1423 
1424 	if (STp->ready != ST_READY) {
1425 		if (STp->ready == ST_NO_TAPE)
1426 			retval = (-ENOMEDIUM);
1427 		else
1428 			retval = (-EIO);
1429 		goto out;
1430 	}
1431 
1432 	if (! STp->modes[STp->current_mode].defined) {
1433 		retval = (-ENXIO);
1434 		goto out;
1435 	}
1436 
1437 
1438 	/*
1439 	 * If there was a bus reset, block further access
1440 	 * to this device.
1441 	 */
1442 	if (STp->pos_unknown) {
1443 		retval = (-EIO);
1444 		goto out;
1445 	}
1446 
1447 	if (count == 0)
1448 		goto out;
1449 
1450         DEB(
1451 	if (!STp->in_use) {
1452 		printk(ST_DEB_MSG "%s: Incorrect device.\n", tape_name(STp));
1453 		retval = (-EIO);
1454 		goto out;
1455 	} ) /* end DEB */
1456 
1457 	if (STp->can_partitions &&
1458 	    (retval = switch_partition(STp)) < 0)
1459 		goto out;
1460 
1461 	if (STp->block_size == 0 && STp->max_block > 0 &&
1462 	    (count < STp->min_block || count > STp->max_block)) {
1463 		retval = (-EINVAL);
1464 		goto out;
1465 	}
1466 
1467 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1468 	    !do_door_lock(STp, 1))
1469 		STp->door_locked = ST_LOCKED_AUTO;
1470 
1471  out:
1472 	return retval;
1473 }
1474 
1475 
1476 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1477 			   size_t count, int is_read)
1478 {
1479 	int i, bufsize, retval = 0;
1480 	struct st_buffer *STbp = STp->buffer;
1481 
1482 	if (is_read)
1483 		i = STp->try_dio_now && try_rdio;
1484 	else
1485 		i = STp->try_dio_now && try_wdio;
1486 
1487 	if (i && ((unsigned long)buf & queue_dma_alignment(
1488 					STp->device->request_queue)) == 0) {
1489 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1490 				       count, (is_read ? READ : WRITE));
1491 		if (i > 0) {
1492 			STbp->do_dio = i;
1493 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1494 		}
1495 		else
1496 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1497 		STbp->sg_segs = STbp->do_dio;
1498 		DEB(
1499 		     if (STbp->do_dio) {
1500 			STp->nbr_dio++;
1501 			STp->nbr_pages += STbp->do_dio;
1502 		     }
1503 		)
1504 	} else
1505 		STbp->do_dio = 0;
1506 	DEB( STp->nbr_requests++; )
1507 
1508 	if (!STbp->do_dio) {
1509 		if (STp->block_size)
1510 			bufsize = STp->block_size > st_fixed_buffer_size ?
1511 				STp->block_size : st_fixed_buffer_size;
1512 		else {
1513 			bufsize = count;
1514 			/* Make sure that data from previous user is not leaked even if
1515 			   HBA does not return correct residual */
1516 			if (is_read && STp->sili && !STbp->cleared)
1517 				clear_buffer(STbp);
1518 		}
1519 
1520 		if (bufsize > STbp->buffer_size &&
1521 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1522 			printk(KERN_WARNING "%s: Can't allocate %d byte tape buffer.\n",
1523 			       tape_name(STp), bufsize);
1524 			retval = (-EOVERFLOW);
1525 			goto out;
1526 		}
1527 		if (STp->block_size)
1528 			STbp->buffer_blocks = bufsize / STp->block_size;
1529 	}
1530 
1531  out:
1532 	return retval;
1533 }
1534 
1535 
1536 /* Can be called more than once after each setup_buffer() */
1537 static void release_buffering(struct scsi_tape *STp, int is_read)
1538 {
1539 	struct st_buffer *STbp;
1540 
1541 	STbp = STp->buffer;
1542 	if (STbp->do_dio) {
1543 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1544 		STbp->do_dio = 0;
1545 		STbp->sg_segs = 0;
1546 	}
1547 }
1548 
1549 
1550 /* Write command */
1551 static ssize_t
1552 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1553 {
1554 	ssize_t total;
1555 	ssize_t i, do_count, blks, transfer;
1556 	ssize_t retval;
1557 	int undone, retry_eot = 0, scode;
1558 	int async_write;
1559 	unsigned char cmd[MAX_COMMAND_SIZE];
1560 	const char __user *b_point;
1561 	struct st_request *SRpnt = NULL;
1562 	struct scsi_tape *STp = filp->private_data;
1563 	struct st_modedef *STm;
1564 	struct st_partstat *STps;
1565 	struct st_buffer *STbp;
1566 	char *name = tape_name(STp);
1567 
1568 	if (mutex_lock_interruptible(&STp->lock))
1569 		return -ERESTARTSYS;
1570 
1571 	retval = rw_checks(STp, filp, count);
1572 	if (retval || count == 0)
1573 		goto out;
1574 
1575 	/* Write must be integral number of blocks */
1576 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1577 		printk(KERN_WARNING "%s: Write not multiple of tape block size.\n",
1578 		       name);
1579 		retval = (-EINVAL);
1580 		goto out;
1581 	}
1582 
1583 	STm = &(STp->modes[STp->current_mode]);
1584 	STps = &(STp->ps[STp->partition]);
1585 
1586 	if (STp->write_prot) {
1587 		retval = (-EACCES);
1588 		goto out;
1589 	}
1590 
1591 
1592 	if (STps->rw == ST_READING) {
1593 		retval = flush_buffer(STp, 0);
1594 		if (retval)
1595 			goto out;
1596 		STps->rw = ST_WRITING;
1597 	} else if (STps->rw != ST_WRITING &&
1598 		   STps->drv_file == 0 && STps->drv_block == 0) {
1599 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1600 			goto out;
1601 		if (STm->default_compression != ST_DONT_TOUCH &&
1602 		    !(STp->compression_changed)) {
1603 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1604 				printk(KERN_WARNING "%s: Can't set default compression.\n",
1605 				       name);
1606 				if (modes_defined) {
1607 					retval = (-EINVAL);
1608 					goto out;
1609 				}
1610 			}
1611 		}
1612 	}
1613 
1614 	STbp = STp->buffer;
1615 	i = write_behind_check(STp);
1616 	if (i) {
1617 		if (i == -ENOSPC)
1618 			STps->eof = ST_EOM_OK;
1619 		else
1620 			STps->eof = ST_EOM_ERROR;
1621 	}
1622 
1623 	if (STps->eof == ST_EOM_OK) {
1624 		STps->eof = ST_EOD_1;  /* allow next write */
1625 		retval = (-ENOSPC);
1626 		goto out;
1627 	}
1628 	else if (STps->eof == ST_EOM_ERROR) {
1629 		retval = (-EIO);
1630 		goto out;
1631 	}
1632 
1633 	/* Check the buffer readability in cases where copy_user might catch
1634 	   the problems after some tape movement. */
1635 	if (STp->block_size != 0 &&
1636 	    !STbp->do_dio &&
1637 	    (copy_from_user(&i, buf, 1) != 0 ||
1638 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1639 		retval = (-EFAULT);
1640 		goto out;
1641 	}
1642 
1643 	retval = setup_buffering(STp, buf, count, 0);
1644 	if (retval)
1645 		goto out;
1646 
1647 	total = count;
1648 
1649 	memset(cmd, 0, MAX_COMMAND_SIZE);
1650 	cmd[0] = WRITE_6;
1651 	cmd[1] = (STp->block_size != 0);
1652 
1653 	STps->rw = ST_WRITING;
1654 
1655 	b_point = buf;
1656 	while (count > 0 && !retry_eot) {
1657 
1658 		if (STbp->do_dio) {
1659 			do_count = count;
1660 		}
1661 		else {
1662 			if (STp->block_size == 0)
1663 				do_count = count;
1664 			else {
1665 				do_count = STbp->buffer_blocks * STp->block_size -
1666 					STbp->buffer_bytes;
1667 				if (do_count > count)
1668 					do_count = count;
1669 			}
1670 
1671 			i = append_to_buffer(b_point, STbp, do_count);
1672 			if (i) {
1673 				retval = i;
1674 				goto out;
1675 			}
1676 		}
1677 		count -= do_count;
1678 		b_point += do_count;
1679 
1680 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1681 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1682 
1683 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1684 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1685 		    STbp->buffer_bytes < STbp->buffer_size) {
1686 			STp->dirty = 1;
1687 			/* Don't write a buffer that is not full enough. */
1688 			if (!async_write && count == 0)
1689 				break;
1690 		}
1691 
1692 	retry_write:
1693 		if (STp->block_size == 0)
1694 			blks = transfer = do_count;
1695 		else {
1696 			if (!STbp->do_dio)
1697 				blks = STbp->buffer_bytes;
1698 			else
1699 				blks = do_count;
1700 			blks /= STp->block_size;
1701 			transfer = blks * STp->block_size;
1702 		}
1703 		cmd[2] = blks >> 16;
1704 		cmd[3] = blks >> 8;
1705 		cmd[4] = blks;
1706 
1707 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1708 				   STp->device->request_queue->rq_timeout,
1709 				   MAX_WRITE_RETRIES, !async_write);
1710 		if (!SRpnt) {
1711 			retval = STbp->syscall_result;
1712 			goto out;
1713 		}
1714 		if (async_write && !STbp->syscall_result) {
1715 			STbp->writing = transfer;
1716 			STp->dirty = !(STbp->writing ==
1717 				       STbp->buffer_bytes);
1718 			SRpnt = NULL;  /* Prevent releasing this request! */
1719 			DEB( STp->write_pending = 1; )
1720 			break;
1721 		}
1722 
1723 		if (STbp->syscall_result != 0) {
1724 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1725 
1726                         DEBC(printk(ST_DEB_MSG "%s: Error on write:\n", name));
1727 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1728 				scode = cmdstatp->sense_hdr.sense_key;
1729 				if (cmdstatp->remainder_valid)
1730 					undone = (int)cmdstatp->uremainder64;
1731 				else if (STp->block_size == 0 &&
1732 					 scode == VOLUME_OVERFLOW)
1733 					undone = transfer;
1734 				else
1735 					undone = 0;
1736 				if (STp->block_size != 0)
1737 					undone *= STp->block_size;
1738 				if (undone <= do_count) {
1739 					/* Only data from this write is not written */
1740 					count += undone;
1741 					b_point -= undone;
1742 					do_count -= undone;
1743 					if (STp->block_size)
1744 						blks = (transfer - undone) / STp->block_size;
1745 					STps->eof = ST_EOM_OK;
1746 					/* Continue in fixed block mode if all written
1747 					   in this request but still something left to write
1748 					   (retval left to zero)
1749 					*/
1750 					if (STp->block_size == 0 ||
1751 					    undone > 0 || count == 0)
1752 						retval = (-ENOSPC); /* EOM within current request */
1753                                         DEBC(printk(ST_DEB_MSG
1754                                                        "%s: EOM with %d bytes unwritten.\n",
1755 						       name, (int)count));
1756 				} else {
1757 					/* EOT within data buffered earlier (possible only
1758 					   in fixed block mode without direct i/o) */
1759 					if (!retry_eot && !cmdstatp->deferred &&
1760 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1761 						move_buffer_data(STp->buffer, transfer - undone);
1762 						retry_eot = 1;
1763 						if (STps->drv_block >= 0) {
1764 							STps->drv_block += (transfer - undone) /
1765 								STp->block_size;
1766 						}
1767 						STps->eof = ST_EOM_OK;
1768 						DEBC(printk(ST_DEB_MSG
1769 							    "%s: Retry write of %d bytes at EOM.\n",
1770 							    name, STp->buffer->buffer_bytes));
1771 						goto retry_write;
1772 					}
1773 					else {
1774 						/* Either error within data buffered by driver or
1775 						   failed retry */
1776 						count -= do_count;
1777 						blks = do_count = 0;
1778 						STps->eof = ST_EOM_ERROR;
1779 						STps->drv_block = (-1); /* Too cautious? */
1780 						retval = (-EIO);	/* EOM for old data */
1781 						DEBC(printk(ST_DEB_MSG
1782 							    "%s: EOM with lost data.\n",
1783 							    name));
1784 					}
1785 				}
1786 			} else {
1787 				count += do_count;
1788 				STps->drv_block = (-1);		/* Too cautious? */
1789 				retval = STbp->syscall_result;
1790 			}
1791 
1792 		}
1793 
1794 		if (STps->drv_block >= 0) {
1795 			if (STp->block_size == 0)
1796 				STps->drv_block += (do_count > 0);
1797 			else
1798 				STps->drv_block += blks;
1799 		}
1800 
1801 		STbp->buffer_bytes = 0;
1802 		STp->dirty = 0;
1803 
1804 		if (retval || retry_eot) {
1805 			if (count < total)
1806 				retval = total - count;
1807 			goto out;
1808 		}
1809 	}
1810 
1811 	if (STps->eof == ST_EOD_1)
1812 		STps->eof = ST_EOM_OK;
1813 	else if (STps->eof != ST_EOM_OK)
1814 		STps->eof = ST_NOEOF;
1815 	retval = total - count;
1816 
1817  out:
1818 	if (SRpnt != NULL)
1819 		st_release_request(SRpnt);
1820 	release_buffering(STp, 0);
1821 	mutex_unlock(&STp->lock);
1822 
1823 	return retval;
1824 }
1825 
1826 /* Read data from the tape. Returns zero in the normal case, one if the
1827    eof status has changed, and the negative error code in case of a
1828    fatal error. Otherwise updates the buffer and the eof state.
1829 
1830    Does release user buffer mapping if it is set.
1831 */
1832 static long read_tape(struct scsi_tape *STp, long count,
1833 		      struct st_request ** aSRpnt)
1834 {
1835 	int transfer, blks, bytes;
1836 	unsigned char cmd[MAX_COMMAND_SIZE];
1837 	struct st_request *SRpnt;
1838 	struct st_modedef *STm;
1839 	struct st_partstat *STps;
1840 	struct st_buffer *STbp;
1841 	int retval = 0;
1842 	char *name = tape_name(STp);
1843 
1844 	if (count == 0)
1845 		return 0;
1846 
1847 	STm = &(STp->modes[STp->current_mode]);
1848 	STps = &(STp->ps[STp->partition]);
1849 	if (STps->eof == ST_FM_HIT)
1850 		return 1;
1851 	STbp = STp->buffer;
1852 
1853 	if (STp->block_size == 0)
1854 		blks = bytes = count;
1855 	else {
1856 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1857 			blks = (STp->buffer)->buffer_blocks;
1858 			bytes = blks * STp->block_size;
1859 		} else {
1860 			bytes = count;
1861 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1862 				bytes = (STp->buffer)->buffer_size;
1863 			blks = bytes / STp->block_size;
1864 			bytes = blks * STp->block_size;
1865 		}
1866 	}
1867 
1868 	memset(cmd, 0, MAX_COMMAND_SIZE);
1869 	cmd[0] = READ_6;
1870 	cmd[1] = (STp->block_size != 0);
1871 	if (!cmd[1] && STp->sili)
1872 		cmd[1] |= 2;
1873 	cmd[2] = blks >> 16;
1874 	cmd[3] = blks >> 8;
1875 	cmd[4] = blks;
1876 
1877 	SRpnt = *aSRpnt;
1878 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1879 			   STp->device->request_queue->rq_timeout,
1880 			   MAX_RETRIES, 1);
1881 	release_buffering(STp, 1);
1882 	*aSRpnt = SRpnt;
1883 	if (!SRpnt)
1884 		return STbp->syscall_result;
1885 
1886 	STbp->read_pointer = 0;
1887 	STps->at_sm = 0;
1888 
1889 	/* Something to check */
1890 	if (STbp->syscall_result) {
1891 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1892 
1893 		retval = 1;
1894 		DEBC(printk(ST_DEB_MSG "%s: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1895                             name,
1896                             SRpnt->sense[0], SRpnt->sense[1],
1897                             SRpnt->sense[2], SRpnt->sense[3],
1898                             SRpnt->sense[4], SRpnt->sense[5],
1899                             SRpnt->sense[6], SRpnt->sense[7]));
1900 		if (cmdstatp->have_sense) {
1901 
1902 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1903 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1904 
1905 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1906 				/* Compute the residual count */
1907 				if (cmdstatp->remainder_valid)
1908 					transfer = (int)cmdstatp->uremainder64;
1909 				else
1910 					transfer = 0;
1911 				if (STp->block_size == 0 &&
1912 				    cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR)
1913 					transfer = bytes;
1914 
1915 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1916 					if (STp->block_size == 0) {
1917 						if (transfer <= 0) {
1918 							if (transfer < 0)
1919 								printk(KERN_NOTICE
1920 								       "%s: Failed to read %d byte block with %d byte transfer.\n",
1921 								       name, bytes - transfer, bytes);
1922 							if (STps->drv_block >= 0)
1923 								STps->drv_block += 1;
1924 							STbp->buffer_bytes = 0;
1925 							return (-ENOMEM);
1926 						}
1927 						STbp->buffer_bytes = bytes - transfer;
1928 					} else {
1929 						st_release_request(SRpnt);
1930 						SRpnt = *aSRpnt = NULL;
1931 						if (transfer == blks) {	/* We did not get anything, error */
1932 							printk(KERN_NOTICE "%s: Incorrect block size.\n", name);
1933 							if (STps->drv_block >= 0)
1934 								STps->drv_block += blks - transfer + 1;
1935 							st_int_ioctl(STp, MTBSR, 1);
1936 							return (-EIO);
1937 						}
1938 						/* We have some data, deliver it */
1939 						STbp->buffer_bytes = (blks - transfer) *
1940 						    STp->block_size;
1941                                                 DEBC(printk(ST_DEB_MSG
1942                                                             "%s: ILI but enough data received %ld %d.\n",
1943                                                             name, count, STbp->buffer_bytes));
1944 						if (STps->drv_block >= 0)
1945 							STps->drv_block += 1;
1946 						if (st_int_ioctl(STp, MTBSR, 1))
1947 							return (-EIO);
1948 					}
1949 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
1950 					if (STps->eof != ST_FM_HIT)
1951 						STps->eof = ST_FM_HIT;
1952 					else
1953 						STps->eof = ST_EOD_2;
1954 					if (STp->block_size == 0)
1955 						STbp->buffer_bytes = 0;
1956 					else
1957 						STbp->buffer_bytes =
1958 						    bytes - transfer * STp->block_size;
1959                                         DEBC(printk(ST_DEB_MSG
1960                                                     "%s: EOF detected (%d bytes read).\n",
1961                                                     name, STbp->buffer_bytes));
1962 				} else if (cmdstatp->flags & SENSE_EOM) {
1963 					if (STps->eof == ST_FM)
1964 						STps->eof = ST_EOD_1;
1965 					else
1966 						STps->eof = ST_EOM_OK;
1967 					if (STp->block_size == 0)
1968 						STbp->buffer_bytes = bytes - transfer;
1969 					else
1970 						STbp->buffer_bytes =
1971 						    bytes - transfer * STp->block_size;
1972 
1973                                         DEBC(printk(ST_DEB_MSG "%s: EOM detected (%d bytes read).\n",
1974                                                     name, STbp->buffer_bytes));
1975 				}
1976 			}
1977 			/* end of EOF, EOM, ILI test */
1978 			else {	/* nonzero sense key */
1979                                 DEBC(printk(ST_DEB_MSG
1980                                             "%s: Tape error while reading.\n", name));
1981 				STps->drv_block = (-1);
1982 				if (STps->eof == ST_FM &&
1983 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
1984                                         DEBC(printk(ST_DEB_MSG
1985                                                     "%s: Zero returned for first BLANK CHECK after EOF.\n",
1986                                                     name));
1987 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
1988 				} else	/* Some other extended sense code */
1989 					retval = (-EIO);
1990 			}
1991 
1992 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
1993 				STbp->buffer_bytes = 0;
1994 		}
1995 		/* End of extended sense test */
1996 		else {		/* Non-extended sense */
1997 			retval = STbp->syscall_result;
1998 		}
1999 
2000 	}
2001 	/* End of error handling */
2002 	else {			/* Read successful */
2003 		STbp->buffer_bytes = bytes;
2004 		if (STp->sili) /* In fixed block mode residual is always zero here */
2005 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2006 	}
2007 
2008 	if (STps->drv_block >= 0) {
2009 		if (STp->block_size == 0)
2010 			STps->drv_block++;
2011 		else
2012 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2013 	}
2014 	return retval;
2015 }
2016 
2017 
2018 /* Read command */
2019 static ssize_t
2020 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2021 {
2022 	ssize_t total;
2023 	ssize_t retval = 0;
2024 	ssize_t i, transfer;
2025 	int special, do_dio = 0;
2026 	struct st_request *SRpnt = NULL;
2027 	struct scsi_tape *STp = filp->private_data;
2028 	struct st_modedef *STm;
2029 	struct st_partstat *STps;
2030 	struct st_buffer *STbp = STp->buffer;
2031 	DEB( char *name = tape_name(STp); )
2032 
2033 	if (mutex_lock_interruptible(&STp->lock))
2034 		return -ERESTARTSYS;
2035 
2036 	retval = rw_checks(STp, filp, count);
2037 	if (retval || count == 0)
2038 		goto out;
2039 
2040 	STm = &(STp->modes[STp->current_mode]);
2041 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2042 		if (!STm->do_read_ahead) {
2043 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2044 			goto out;
2045 		}
2046 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2047 	}
2048 
2049 	STps = &(STp->ps[STp->partition]);
2050 	if (STps->rw == ST_WRITING) {
2051 		retval = flush_buffer(STp, 0);
2052 		if (retval)
2053 			goto out;
2054 		STps->rw = ST_READING;
2055 	}
2056         DEB(
2057 	if (debugging && STps->eof != ST_NOEOF)
2058 		printk(ST_DEB_MSG "%s: EOF/EOM flag up (%d). Bytes %d\n", name,
2059 		       STps->eof, STbp->buffer_bytes);
2060         ) /* end DEB */
2061 
2062 	retval = setup_buffering(STp, buf, count, 1);
2063 	if (retval)
2064 		goto out;
2065 	do_dio = STbp->do_dio;
2066 
2067 	if (STbp->buffer_bytes == 0 &&
2068 	    STps->eof >= ST_EOD_1) {
2069 		if (STps->eof < ST_EOD) {
2070 			STps->eof += 1;
2071 			retval = 0;
2072 			goto out;
2073 		}
2074 		retval = (-EIO);	/* EOM or Blank Check */
2075 		goto out;
2076 	}
2077 
2078 	if (do_dio) {
2079 		/* Check the buffer writability before any tape movement. Don't alter
2080 		   buffer data. */
2081 		if (copy_from_user(&i, buf, 1) != 0 ||
2082 		    copy_to_user(buf, &i, 1) != 0 ||
2083 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2084 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2085 			retval = (-EFAULT);
2086 			goto out;
2087 		}
2088 	}
2089 
2090 	STps->rw = ST_READING;
2091 
2092 
2093 	/* Loop until enough data in buffer or a special condition found */
2094 	for (total = 0, special = 0; total < count && !special;) {
2095 
2096 		/* Get new data if the buffer is empty */
2097 		if (STbp->buffer_bytes == 0) {
2098 			special = read_tape(STp, count - total, &SRpnt);
2099 			if (special < 0) {	/* No need to continue read */
2100 				retval = special;
2101 				goto out;
2102 			}
2103 		}
2104 
2105 		/* Move the data from driver buffer to user buffer */
2106 		if (STbp->buffer_bytes > 0) {
2107                         DEB(
2108 			if (debugging && STps->eof != ST_NOEOF)
2109 				printk(ST_DEB_MSG
2110                                        "%s: EOF up (%d). Left %d, needed %d.\n", name,
2111 				       STps->eof, STbp->buffer_bytes,
2112                                        (int)(count - total));
2113                         ) /* end DEB */
2114 			transfer = STbp->buffer_bytes < count - total ?
2115 			    STbp->buffer_bytes : count - total;
2116 			if (!do_dio) {
2117 				i = from_buffer(STbp, buf, transfer);
2118 				if (i) {
2119 					retval = i;
2120 					goto out;
2121 				}
2122 			}
2123 			buf += transfer;
2124 			total += transfer;
2125 		}
2126 
2127 		if (STp->block_size == 0)
2128 			break;	/* Read only one variable length block */
2129 
2130 	}			/* for (total = 0, special = 0;
2131                                    total < count && !special; ) */
2132 
2133 	/* Change the eof state if no data from tape or buffer */
2134 	if (total == 0) {
2135 		if (STps->eof == ST_FM_HIT) {
2136 			STps->eof = ST_FM;
2137 			STps->drv_block = 0;
2138 			if (STps->drv_file >= 0)
2139 				STps->drv_file++;
2140 		} else if (STps->eof == ST_EOD_1) {
2141 			STps->eof = ST_EOD_2;
2142 			STps->drv_block = 0;
2143 			if (STps->drv_file >= 0)
2144 				STps->drv_file++;
2145 		} else if (STps->eof == ST_EOD_2)
2146 			STps->eof = ST_EOD;
2147 	} else if (STps->eof == ST_FM)
2148 		STps->eof = ST_NOEOF;
2149 	retval = total;
2150 
2151  out:
2152 	if (SRpnt != NULL) {
2153 		st_release_request(SRpnt);
2154 		SRpnt = NULL;
2155 	}
2156 	if (do_dio) {
2157 		release_buffering(STp, 1);
2158 		STbp->buffer_bytes = 0;
2159 	}
2160 	mutex_unlock(&STp->lock);
2161 
2162 	return retval;
2163 }
2164 
2165 
2166 
2167 DEB(
2168 /* Set the driver options */
2169 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm, char *name)
2170 {
2171 	if (debugging) {
2172 		printk(KERN_INFO
2173 		       "%s: Mode %d options: buffer writes: %d, async writes: %d, read ahead: %d\n",
2174 		       name, STp->current_mode, STm->do_buffer_writes, STm->do_async_writes,
2175 		       STm->do_read_ahead);
2176 		printk(KERN_INFO
2177 		       "%s:    can bsr: %d, two FMs: %d, fast mteom: %d, auto lock: %d,\n",
2178 		       name, STp->can_bsr, STp->two_fm, STp->fast_mteom, STp->do_auto_lock);
2179 		printk(KERN_INFO
2180 		       "%s:    defs for wr: %d, no block limits: %d, partitions: %d, s2 log: %d\n",
2181 		       name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
2182 		       STp->scsi2_logical);
2183 		printk(KERN_INFO
2184 		       "%s:    sysv: %d nowait: %d sili: %d nowait_filemark: %d\n",
2185 		       name, STm->sysv, STp->immediate, STp->sili,
2186 		       STp->immediate_filemark);
2187 		printk(KERN_INFO "%s:    debugging: %d\n",
2188 		       name, debugging);
2189 	}
2190 }
2191 	)
2192 
2193 
2194 static int st_set_options(struct scsi_tape *STp, long options)
2195 {
2196 	int value;
2197 	long code;
2198 	struct st_modedef *STm;
2199 	char *name = tape_name(STp);
2200 	struct cdev *cd0, *cd1;
2201 
2202 	STm = &(STp->modes[STp->current_mode]);
2203 	if (!STm->defined) {
2204 		cd0 = STm->cdevs[0]; cd1 = STm->cdevs[1];
2205 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2206 		STm->cdevs[0] = cd0; STm->cdevs[1] = cd1;
2207 		modes_defined = 1;
2208                 DEBC(printk(ST_DEB_MSG
2209                             "%s: Initialized mode %d definition from mode 0\n",
2210                             name, STp->current_mode));
2211 	}
2212 
2213 	code = options & MT_ST_OPTIONS;
2214 	if (code == MT_ST_BOOLEANS) {
2215 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2216 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2217 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2218 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2219 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2220 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2221 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2222 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2223 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2224 		if ((STp->device)->scsi_level >= SCSI_2)
2225 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2226 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2227 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2228 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2229 		STm->sysv = (options & MT_ST_SYSV) != 0;
2230 		STp->sili = (options & MT_ST_SILI) != 0;
2231 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2232 		     st_log_options(STp, STm, name); )
2233 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2234 		value = (code == MT_ST_SETBOOLEANS);
2235 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2236 			STm->do_buffer_writes = value;
2237 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2238 			STm->do_async_writes = value;
2239 		if ((options & MT_ST_DEF_WRITES) != 0)
2240 			STm->defaults_for_writes = value;
2241 		if ((options & MT_ST_READ_AHEAD) != 0)
2242 			STm->do_read_ahead = value;
2243 		if ((options & MT_ST_TWO_FM) != 0)
2244 			STp->two_fm = value;
2245 		if ((options & MT_ST_FAST_MTEOM) != 0)
2246 			STp->fast_mteom = value;
2247 		if ((options & MT_ST_AUTO_LOCK) != 0)
2248 			STp->do_auto_lock = value;
2249 		if ((options & MT_ST_CAN_BSR) != 0)
2250 			STp->can_bsr = value;
2251 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2252 			STp->omit_blklims = value;
2253 		if ((STp->device)->scsi_level >= SCSI_2 &&
2254 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2255 			STp->can_partitions = value;
2256 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2257 			STp->scsi2_logical = value;
2258 		if ((options & MT_ST_NOWAIT) != 0)
2259 			STp->immediate = value;
2260 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2261 			STp->immediate_filemark = value;
2262 		if ((options & MT_ST_SYSV) != 0)
2263 			STm->sysv = value;
2264 		if ((options & MT_ST_SILI) != 0)
2265 			STp->sili = value;
2266                 DEB(
2267 		if ((options & MT_ST_DEBUGGING) != 0)
2268 			debugging = value;
2269 			st_log_options(STp, STm, name); )
2270 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2271 		/* Retained for compatibility */
2272 	} else if (code == MT_ST_DEF_BLKSIZE) {
2273 		value = (options & ~MT_ST_OPTIONS);
2274 		if (value == ~MT_ST_OPTIONS) {
2275 			STm->default_blksize = (-1);
2276 			DEBC( printk(KERN_INFO "%s: Default block size disabled.\n", name));
2277 		} else {
2278 			STm->default_blksize = value;
2279 			DEBC( printk(KERN_INFO "%s: Default block size set to %d bytes.\n",
2280 			       name, STm->default_blksize));
2281 			if (STp->ready == ST_READY) {
2282 				STp->blksize_changed = 0;
2283 				set_mode_densblk(STp, STm);
2284 			}
2285 		}
2286 	} else if (code == MT_ST_TIMEOUTS) {
2287 		value = (options & ~MT_ST_OPTIONS);
2288 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2289 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2290 			DEBC( printk(KERN_INFO "%s: Long timeout set to %d seconds.\n", name,
2291 			       (value & ~MT_ST_SET_LONG_TIMEOUT)));
2292 		} else {
2293 			blk_queue_rq_timeout(STp->device->request_queue,
2294 					     value * HZ);
2295 			DEBC( printk(KERN_INFO "%s: Normal timeout set to %d seconds.\n",
2296 				name, value) );
2297 		}
2298 	} else if (code == MT_ST_SET_CLN) {
2299 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2300 		if (value != 0 &&
2301 			(value < EXTENDED_SENSE_START ||
2302 				value >= SCSI_SENSE_BUFFERSIZE))
2303 			return (-EINVAL);
2304 		STp->cln_mode = value;
2305 		STp->cln_sense_mask = (options >> 8) & 0xff;
2306 		STp->cln_sense_value = (options >> 16) & 0xff;
2307 		printk(KERN_INFO
2308 		       "%s: Cleaning request mode %d, mask %02x, value %02x\n",
2309 		       name, value, STp->cln_sense_mask, STp->cln_sense_value);
2310 	} else if (code == MT_ST_DEF_OPTIONS) {
2311 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2312 		value = (options & MT_ST_CLEAR_DEFAULT);
2313 		if (code == MT_ST_DEF_DENSITY) {
2314 			if (value == MT_ST_CLEAR_DEFAULT) {
2315 				STm->default_density = (-1);
2316 				DEBC( printk(KERN_INFO "%s: Density default disabled.\n",
2317                                        name));
2318 			} else {
2319 				STm->default_density = value & 0xff;
2320 				DEBC( printk(KERN_INFO "%s: Density default set to %x\n",
2321 				       name, STm->default_density));
2322 				if (STp->ready == ST_READY) {
2323 					STp->density_changed = 0;
2324 					set_mode_densblk(STp, STm);
2325 				}
2326 			}
2327 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2328 			if (value == MT_ST_CLEAR_DEFAULT) {
2329 				STp->default_drvbuffer = 0xff;
2330 				DEBC( printk(KERN_INFO
2331                                        "%s: Drive buffer default disabled.\n", name));
2332 			} else {
2333 				STp->default_drvbuffer = value & 7;
2334 				DEBC( printk(KERN_INFO
2335                                        "%s: Drive buffer default set to %x\n",
2336 				       name, STp->default_drvbuffer));
2337 				if (STp->ready == ST_READY)
2338 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2339 			}
2340 		} else if (code == MT_ST_DEF_COMPRESSION) {
2341 			if (value == MT_ST_CLEAR_DEFAULT) {
2342 				STm->default_compression = ST_DONT_TOUCH;
2343 				DEBC( printk(KERN_INFO
2344                                        "%s: Compression default disabled.\n", name));
2345 			} else {
2346 				if ((value & 0xff00) != 0) {
2347 					STp->c_algo = (value & 0xff00) >> 8;
2348 					DEBC( printk(KERN_INFO "%s: Compression algorithm set to 0x%x.\n",
2349 					       name, STp->c_algo));
2350 				}
2351 				if ((value & 0xff) != 0xff) {
2352 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2353 					DEBC( printk(KERN_INFO "%s: Compression default set to %x\n",
2354 					       name, (value & 1)));
2355 					if (STp->ready == ST_READY) {
2356 						STp->compression_changed = 0;
2357 						st_compression(STp, (STm->default_compression == ST_YES));
2358 					}
2359 				}
2360 			}
2361 		}
2362 	} else
2363 		return (-EIO);
2364 
2365 	return 0;
2366 }
2367 
2368 #define MODE_HEADER_LENGTH  4
2369 
2370 /* Mode header and page byte offsets */
2371 #define MH_OFF_DATA_LENGTH     0
2372 #define MH_OFF_MEDIUM_TYPE     1
2373 #define MH_OFF_DEV_SPECIFIC    2
2374 #define MH_OFF_BDESCS_LENGTH   3
2375 #define MP_OFF_PAGE_NBR        0
2376 #define MP_OFF_PAGE_LENGTH     1
2377 
2378 /* Mode header and page bit masks */
2379 #define MH_BIT_WP              0x80
2380 #define MP_MSK_PAGE_NBR        0x3f
2381 
2382 /* Don't return block descriptors */
2383 #define MODE_SENSE_OMIT_BDESCS 0x08
2384 
2385 #define MODE_SELECT_PAGE_FORMAT 0x10
2386 
2387 /* Read a mode page into the tape buffer. The block descriptors are included
2388    if incl_block_descs is true. The page control is ored to the page number
2389    parameter, if necessary. */
2390 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2391 {
2392 	unsigned char cmd[MAX_COMMAND_SIZE];
2393 	struct st_request *SRpnt;
2394 
2395 	memset(cmd, 0, MAX_COMMAND_SIZE);
2396 	cmd[0] = MODE_SENSE;
2397 	if (omit_block_descs)
2398 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2399 	cmd[2] = page;
2400 	cmd[4] = 255;
2401 
2402 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2403 			   STp->device->request_queue->rq_timeout, 0, 1);
2404 	if (SRpnt == NULL)
2405 		return (STp->buffer)->syscall_result;
2406 
2407 	st_release_request(SRpnt);
2408 
2409 	return STp->buffer->syscall_result;
2410 }
2411 
2412 
2413 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2414    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2415 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2416 {
2417 	int pgo;
2418 	unsigned char cmd[MAX_COMMAND_SIZE];
2419 	struct st_request *SRpnt;
2420 	int timeout;
2421 
2422 	memset(cmd, 0, MAX_COMMAND_SIZE);
2423 	cmd[0] = MODE_SELECT;
2424 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2425 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2426 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2427 
2428 	/* Clear reserved fields */
2429 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2430 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2431 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2432 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2433 
2434 	timeout = slow ?
2435 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2436 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2437 			   timeout, 0, 1);
2438 	if (SRpnt == NULL)
2439 		return (STp->buffer)->syscall_result;
2440 
2441 	st_release_request(SRpnt);
2442 
2443 	return STp->buffer->syscall_result;
2444 }
2445 
2446 
2447 #define COMPRESSION_PAGE        0x0f
2448 #define COMPRESSION_PAGE_LENGTH 16
2449 
2450 #define CP_OFF_DCE_DCC          2
2451 #define CP_OFF_C_ALGO           7
2452 
2453 #define DCE_MASK  0x80
2454 #define DCC_MASK  0x40
2455 #define RED_MASK  0x60
2456 
2457 
2458 /* Control the compression with mode page 15. Algorithm not changed if zero.
2459 
2460    The block descriptors are read and written because Sony SDT-7000 does not
2461    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2462    Including block descriptors should not cause any harm to other drives. */
2463 
2464 static int st_compression(struct scsi_tape * STp, int state)
2465 {
2466 	int retval;
2467 	int mpoffs;  /* Offset to mode page start */
2468 	unsigned char *b_data = (STp->buffer)->b_data;
2469 	DEB( char *name = tape_name(STp); )
2470 
2471 	if (STp->ready != ST_READY)
2472 		return (-EIO);
2473 
2474 	/* Read the current page contents */
2475 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2476 	if (retval) {
2477                 DEBC(printk(ST_DEB_MSG "%s: Compression mode page not supported.\n",
2478                             name));
2479 		return (-EIO);
2480 	}
2481 
2482 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2483         DEBC(printk(ST_DEB_MSG "%s: Compression state is %d.\n", name,
2484                     (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0)));
2485 
2486 	/* Check if compression can be changed */
2487 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2488                 DEBC(printk(ST_DEB_MSG "%s: Compression not supported.\n", name));
2489 		return (-EIO);
2490 	}
2491 
2492 	/* Do the change */
2493 	if (state) {
2494 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2495 		if (STp->c_algo != 0)
2496 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2497 	}
2498 	else {
2499 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2500 		if (STp->c_algo != 0)
2501 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2502 	}
2503 
2504 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2505 	if (retval) {
2506                 DEBC(printk(ST_DEB_MSG "%s: Compression change failed.\n", name));
2507 		return (-EIO);
2508 	}
2509         DEBC(printk(ST_DEB_MSG "%s: Compression state changed to %d.\n",
2510 		       name, state));
2511 
2512 	STp->compression_changed = 1;
2513 	return 0;
2514 }
2515 
2516 
2517 /* Process the load and unload commands (does unload if the load code is zero) */
2518 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2519 {
2520 	int retval = (-EIO), timeout;
2521 	DEB( char *name = tape_name(STp); )
2522 	unsigned char cmd[MAX_COMMAND_SIZE];
2523 	struct st_partstat *STps;
2524 	struct st_request *SRpnt;
2525 
2526 	if (STp->ready != ST_READY && !load_code) {
2527 		if (STp->ready == ST_NO_TAPE)
2528 			return (-ENOMEDIUM);
2529 		else
2530 			return (-EIO);
2531 	}
2532 
2533 	memset(cmd, 0, MAX_COMMAND_SIZE);
2534 	cmd[0] = START_STOP;
2535 	if (load_code)
2536 		cmd[4] |= 1;
2537 	/*
2538 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2539 	 */
2540 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2541 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2542 		DEBC(printk(ST_DEB_MSG "%s: Enhanced %sload slot %2d.\n",
2543 			    name, (cmd[4]) ? "" : "un",
2544 			    load_code - MT_ST_HPLOADER_OFFSET));
2545 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2546 	}
2547 	if (STp->immediate) {
2548 		cmd[1] = 1;	/* Don't wait for completion */
2549 		timeout = STp->device->request_queue->rq_timeout;
2550 	}
2551 	else
2552 		timeout = STp->long_timeout;
2553 
2554 	DEBC(
2555 		if (!load_code)
2556 		printk(ST_DEB_MSG "%s: Unloading tape.\n", name);
2557 		else
2558 		printk(ST_DEB_MSG "%s: Loading tape.\n", name);
2559 		);
2560 
2561 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2562 			   timeout, MAX_RETRIES, 1);
2563 	if (!SRpnt)
2564 		return (STp->buffer)->syscall_result;
2565 
2566 	retval = (STp->buffer)->syscall_result;
2567 	st_release_request(SRpnt);
2568 
2569 	if (!retval) {	/* SCSI command successful */
2570 
2571 		if (!load_code) {
2572 			STp->rew_at_close = 0;
2573 			STp->ready = ST_NO_TAPE;
2574 		}
2575 		else {
2576 			STp->rew_at_close = STp->autorew_dev;
2577 			retval = check_tape(STp, filp);
2578 			if (retval > 0)
2579 				retval = 0;
2580 		}
2581 	}
2582 	else {
2583 		STps = &(STp->ps[STp->partition]);
2584 		STps->drv_file = STps->drv_block = (-1);
2585 	}
2586 
2587 	return retval;
2588 }
2589 
2590 #if DEBUG
2591 #define ST_DEB_FORWARD  0
2592 #define ST_DEB_BACKWARD 1
2593 static void deb_space_print(char *name, int direction, char *units, unsigned char *cmd)
2594 {
2595 	s32 sc;
2596 
2597 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2598 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2599 	if (direction)
2600 		sc = -sc;
2601 	printk(ST_DEB_MSG "%s: Spacing tape %s over %d %s.\n", name,
2602 	       direction ? "backward" : "forward", sc, units);
2603 }
2604 #endif
2605 
2606 
2607 /* Internal ioctl function */
2608 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2609 {
2610 	int timeout;
2611 	long ltmp;
2612 	int ioctl_result;
2613 	int chg_eof = 1;
2614 	unsigned char cmd[MAX_COMMAND_SIZE];
2615 	struct st_request *SRpnt;
2616 	struct st_partstat *STps;
2617 	int fileno, blkno, at_sm, undone;
2618 	int datalen = 0, direction = DMA_NONE;
2619 	char *name = tape_name(STp);
2620 
2621 	WARN_ON(STp->buffer->do_dio != 0);
2622 	if (STp->ready != ST_READY) {
2623 		if (STp->ready == ST_NO_TAPE)
2624 			return (-ENOMEDIUM);
2625 		else
2626 			return (-EIO);
2627 	}
2628 	timeout = STp->long_timeout;
2629 	STps = &(STp->ps[STp->partition]);
2630 	fileno = STps->drv_file;
2631 	blkno = STps->drv_block;
2632 	at_sm = STps->at_sm;
2633 
2634 	memset(cmd, 0, MAX_COMMAND_SIZE);
2635 	switch (cmd_in) {
2636 	case MTFSFM:
2637 		chg_eof = 0;	/* Changed from the FSF after this */
2638 	case MTFSF:
2639 		cmd[0] = SPACE;
2640 		cmd[1] = 0x01;	/* Space FileMarks */
2641 		cmd[2] = (arg >> 16);
2642 		cmd[3] = (arg >> 8);
2643 		cmd[4] = arg;
2644                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "filemarks", cmd);)
2645 		if (fileno >= 0)
2646 			fileno += arg;
2647 		blkno = 0;
2648 		at_sm &= (arg == 0);
2649 		break;
2650 	case MTBSFM:
2651 		chg_eof = 0;	/* Changed from the FSF after this */
2652 	case MTBSF:
2653 		cmd[0] = SPACE;
2654 		cmd[1] = 0x01;	/* Space FileMarks */
2655 		ltmp = (-arg);
2656 		cmd[2] = (ltmp >> 16);
2657 		cmd[3] = (ltmp >> 8);
2658 		cmd[4] = ltmp;
2659                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "filemarks", cmd);)
2660 		if (fileno >= 0)
2661 			fileno -= arg;
2662 		blkno = (-1);	/* We can't know the block number */
2663 		at_sm &= (arg == 0);
2664 		break;
2665 	case MTFSR:
2666 		cmd[0] = SPACE;
2667 		cmd[1] = 0x00;	/* Space Blocks */
2668 		cmd[2] = (arg >> 16);
2669 		cmd[3] = (arg >> 8);
2670 		cmd[4] = arg;
2671                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "blocks", cmd);)
2672 		if (blkno >= 0)
2673 			blkno += arg;
2674 		at_sm &= (arg == 0);
2675 		break;
2676 	case MTBSR:
2677 		cmd[0] = SPACE;
2678 		cmd[1] = 0x00;	/* Space Blocks */
2679 		ltmp = (-arg);
2680 		cmd[2] = (ltmp >> 16);
2681 		cmd[3] = (ltmp >> 8);
2682 		cmd[4] = ltmp;
2683                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "blocks", cmd);)
2684 		if (blkno >= 0)
2685 			blkno -= arg;
2686 		at_sm &= (arg == 0);
2687 		break;
2688 	case MTFSS:
2689 		cmd[0] = SPACE;
2690 		cmd[1] = 0x04;	/* Space Setmarks */
2691 		cmd[2] = (arg >> 16);
2692 		cmd[3] = (arg >> 8);
2693 		cmd[4] = arg;
2694                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "setmarks", cmd);)
2695 		if (arg != 0) {
2696 			blkno = fileno = (-1);
2697 			at_sm = 1;
2698 		}
2699 		break;
2700 	case MTBSS:
2701 		cmd[0] = SPACE;
2702 		cmd[1] = 0x04;	/* Space Setmarks */
2703 		ltmp = (-arg);
2704 		cmd[2] = (ltmp >> 16);
2705 		cmd[3] = (ltmp >> 8);
2706 		cmd[4] = ltmp;
2707                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "setmarks", cmd);)
2708 		if (arg != 0) {
2709 			blkno = fileno = (-1);
2710 			at_sm = 1;
2711 		}
2712 		break;
2713 	case MTWEOF:
2714 	case MTWEOFI:
2715 	case MTWSM:
2716 		if (STp->write_prot)
2717 			return (-EACCES);
2718 		cmd[0] = WRITE_FILEMARKS;
2719 		if (cmd_in == MTWSM)
2720 			cmd[1] = 2;
2721 		if (cmd_in == MTWEOFI ||
2722 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2723 			cmd[1] |= 1;
2724 		cmd[2] = (arg >> 16);
2725 		cmd[3] = (arg >> 8);
2726 		cmd[4] = arg;
2727 		timeout = STp->device->request_queue->rq_timeout;
2728                 DEBC(
2729 		     if (cmd_in != MTWSM)
2730                                printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name,
2731 				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
2732                      else
2733 				printk(ST_DEB_MSG "%s: Writing %d setmarks.\n", name,
2734 				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
2735 		)
2736 		if (fileno >= 0)
2737 			fileno += arg;
2738 		blkno = 0;
2739 		at_sm = (cmd_in == MTWSM);
2740 		break;
2741 	case MTREW:
2742 		cmd[0] = REZERO_UNIT;
2743 		if (STp->immediate) {
2744 			cmd[1] = 1;	/* Don't wait for completion */
2745 			timeout = STp->device->request_queue->rq_timeout;
2746 		}
2747                 DEBC(printk(ST_DEB_MSG "%s: Rewinding tape.\n", name));
2748 		fileno = blkno = at_sm = 0;
2749 		break;
2750 	case MTNOP:
2751                 DEBC(printk(ST_DEB_MSG "%s: No op on tape.\n", name));
2752 		return 0;	/* Should do something ? */
2753 		break;
2754 	case MTRETEN:
2755 		cmd[0] = START_STOP;
2756 		if (STp->immediate) {
2757 			cmd[1] = 1;	/* Don't wait for completion */
2758 			timeout = STp->device->request_queue->rq_timeout;
2759 		}
2760 		cmd[4] = 3;
2761                 DEBC(printk(ST_DEB_MSG "%s: Retensioning tape.\n", name));
2762 		fileno = blkno = at_sm = 0;
2763 		break;
2764 	case MTEOM:
2765 		if (!STp->fast_mteom) {
2766 			/* space to the end of tape */
2767 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2768 			fileno = STps->drv_file;
2769 			if (STps->eof >= ST_EOD_1)
2770 				return 0;
2771 			/* The next lines would hide the number of spaced FileMarks
2772 			   That's why I inserted the previous lines. I had no luck
2773 			   with detecting EOM with FSF, so we go now to EOM.
2774 			   Joerg Weule */
2775 		} else
2776 			fileno = (-1);
2777 		cmd[0] = SPACE;
2778 		cmd[1] = 3;
2779                 DEBC(printk(ST_DEB_MSG "%s: Spacing to end of recorded medium.\n",
2780                             name));
2781 		blkno = -1;
2782 		at_sm = 0;
2783 		break;
2784 	case MTERASE:
2785 		if (STp->write_prot)
2786 			return (-EACCES);
2787 		cmd[0] = ERASE;
2788 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2789 		if (STp->immediate) {
2790 			cmd[1] |= 2;	/* Don't wait for completion */
2791 			timeout = STp->device->request_queue->rq_timeout;
2792 		}
2793 		else
2794 			timeout = STp->long_timeout * 8;
2795 
2796                 DEBC(printk(ST_DEB_MSG "%s: Erasing tape.\n", name));
2797 		fileno = blkno = at_sm = 0;
2798 		break;
2799 	case MTSETBLK:		/* Set block length */
2800 	case MTSETDENSITY:	/* Set tape density */
2801 	case MTSETDRVBUFFER:	/* Set drive buffering */
2802 	case SET_DENS_AND_BLK:	/* Set density and block size */
2803 		chg_eof = 0;
2804 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2805 			return (-EIO);	/* Not allowed if data in buffer */
2806 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2807 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2808 		    STp->max_block > 0 &&
2809 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2810 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2811 			printk(KERN_WARNING "%s: Illegal block size.\n", name);
2812 			return (-EINVAL);
2813 		}
2814 		cmd[0] = MODE_SELECT;
2815 		if ((STp->use_pf & USE_PF))
2816 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2817 		cmd[4] = datalen = 12;
2818 		direction = DMA_TO_DEVICE;
2819 
2820 		memset((STp->buffer)->b_data, 0, 12);
2821 		if (cmd_in == MTSETDRVBUFFER)
2822 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2823 		else
2824 			(STp->buffer)->b_data[2] =
2825 			    STp->drv_buffer << 4;
2826 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2827 		if (cmd_in == MTSETDENSITY) {
2828 			(STp->buffer)->b_data[4] = arg;
2829 			STp->density_changed = 1;	/* At least we tried ;-) */
2830 		} else if (cmd_in == SET_DENS_AND_BLK)
2831 			(STp->buffer)->b_data[4] = arg >> 24;
2832 		else
2833 			(STp->buffer)->b_data[4] = STp->density;
2834 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2835 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2836 			if (cmd_in == MTSETBLK)
2837 				STp->blksize_changed = 1; /* At least we tried ;-) */
2838 		} else
2839 			ltmp = STp->block_size;
2840 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2841 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2842 		(STp->buffer)->b_data[11] = ltmp;
2843 		timeout = STp->device->request_queue->rq_timeout;
2844                 DEBC(
2845 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2846 				printk(ST_DEB_MSG
2847                                        "%s: Setting block size to %d bytes.\n", name,
2848 				       (STp->buffer)->b_data[9] * 65536 +
2849 				       (STp->buffer)->b_data[10] * 256 +
2850 				       (STp->buffer)->b_data[11]);
2851 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2852 				printk(ST_DEB_MSG
2853                                        "%s: Setting density code to %x.\n", name,
2854 				       (STp->buffer)->b_data[4]);
2855 			if (cmd_in == MTSETDRVBUFFER)
2856 				printk(ST_DEB_MSG
2857                                        "%s: Setting drive buffer code to %d.\n", name,
2858 				    ((STp->buffer)->b_data[2] >> 4) & 7);
2859 		)
2860 		break;
2861 	default:
2862 		return (-ENOSYS);
2863 	}
2864 
2865 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2866 			   timeout, MAX_RETRIES, 1);
2867 	if (!SRpnt)
2868 		return (STp->buffer)->syscall_result;
2869 
2870 	ioctl_result = (STp->buffer)->syscall_result;
2871 
2872 	if (!ioctl_result) {	/* SCSI command successful */
2873 		st_release_request(SRpnt);
2874 		SRpnt = NULL;
2875 		STps->drv_block = blkno;
2876 		STps->drv_file = fileno;
2877 		STps->at_sm = at_sm;
2878 
2879 		if (cmd_in == MTBSFM)
2880 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2881 		else if (cmd_in == MTFSFM)
2882 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2883 
2884 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2885 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2886 			if (STp->block_size != 0) {
2887 				(STp->buffer)->buffer_blocks =
2888 				    (STp->buffer)->buffer_size / STp->block_size;
2889 			}
2890 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2891 			if (cmd_in == SET_DENS_AND_BLK)
2892 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2893 		} else if (cmd_in == MTSETDRVBUFFER)
2894 			STp->drv_buffer = (arg & 7);
2895 		else if (cmd_in == MTSETDENSITY)
2896 			STp->density = arg;
2897 
2898 		if (cmd_in == MTEOM)
2899 			STps->eof = ST_EOD;
2900 		else if (cmd_in == MTFSF)
2901 			STps->eof = ST_FM;
2902 		else if (chg_eof)
2903 			STps->eof = ST_NOEOF;
2904 
2905 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
2906 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
2907 	} else { /* SCSI command was not completely successful. Don't return
2908                     from this block without releasing the SCSI command block! */
2909 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
2910 
2911 		if (cmdstatp->flags & SENSE_EOM) {
2912 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
2913 			    cmd_in != MTBSR && cmd_in != MTBSS)
2914 				STps->eof = ST_EOM_OK;
2915 			STps->drv_block = 0;
2916 		}
2917 
2918 		if (cmdstatp->remainder_valid)
2919 			undone = (int)cmdstatp->uremainder64;
2920 		else
2921 			undone = 0;
2922 
2923 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
2924 		    cmdstatp->have_sense &&
2925 		    (cmdstatp->flags & SENSE_EOM)) {
2926 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
2927 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
2928 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
2929 				STps->eof = ST_NOEOF;
2930 			} else {  /* Writing EOF(s) failed */
2931 				if (fileno >= 0)
2932 					fileno -= undone;
2933 				if (undone < arg)
2934 					STps->eof = ST_NOEOF;
2935 			}
2936 			STps->drv_file = fileno;
2937 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
2938 			if (fileno >= 0)
2939 				STps->drv_file = fileno - undone;
2940 			else
2941 				STps->drv_file = fileno;
2942 			STps->drv_block = -1;
2943 			STps->eof = ST_NOEOF;
2944 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
2945 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
2946 				undone = (-undone);
2947 			if (STps->drv_file >= 0)
2948 				STps->drv_file = fileno + undone;
2949 			STps->drv_block = 0;
2950 			STps->eof = ST_NOEOF;
2951 		} else if (cmd_in == MTFSR) {
2952 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
2953 				if (STps->drv_file >= 0)
2954 					STps->drv_file++;
2955 				STps->drv_block = 0;
2956 				STps->eof = ST_FM;
2957 			} else {
2958 				if (blkno >= undone)
2959 					STps->drv_block = blkno - undone;
2960 				else
2961 					STps->drv_block = (-1);
2962 				STps->eof = ST_NOEOF;
2963 			}
2964 		} else if (cmd_in == MTBSR) {
2965 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
2966 				STps->drv_file--;
2967 				STps->drv_block = (-1);
2968 			} else {
2969 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
2970 					undone = (-undone);
2971 				if (STps->drv_block >= 0)
2972 					STps->drv_block = blkno + undone;
2973 			}
2974 			STps->eof = ST_NOEOF;
2975 		} else if (cmd_in == MTEOM) {
2976 			STps->drv_file = (-1);
2977 			STps->drv_block = (-1);
2978 			STps->eof = ST_EOD;
2979 		} else if (cmd_in == MTSETBLK ||
2980 			   cmd_in == MTSETDENSITY ||
2981 			   cmd_in == MTSETDRVBUFFER ||
2982 			   cmd_in == SET_DENS_AND_BLK) {
2983 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
2984 			    !(STp->use_pf & PF_TESTED)) {
2985 				/* Try the other possible state of Page Format if not
2986 				   already tried */
2987 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
2988 				st_release_request(SRpnt);
2989 				SRpnt = NULL;
2990 				return st_int_ioctl(STp, cmd_in, arg);
2991 			}
2992 		} else if (chg_eof)
2993 			STps->eof = ST_NOEOF;
2994 
2995 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
2996 			STps->eof = ST_EOD;
2997 
2998 		st_release_request(SRpnt);
2999 		SRpnt = NULL;
3000 	}
3001 
3002 	return ioctl_result;
3003 }
3004 
3005 
3006 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3007    structure. */
3008 
3009 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3010 			int logical)
3011 {
3012 	int result;
3013 	unsigned char scmd[MAX_COMMAND_SIZE];
3014 	struct st_request *SRpnt;
3015 	DEB( char *name = tape_name(STp); )
3016 
3017 	if (STp->ready != ST_READY)
3018 		return (-EIO);
3019 
3020 	memset(scmd, 0, MAX_COMMAND_SIZE);
3021 	if ((STp->device)->scsi_level < SCSI_2) {
3022 		scmd[0] = QFA_REQUEST_BLOCK;
3023 		scmd[4] = 3;
3024 	} else {
3025 		scmd[0] = READ_POSITION;
3026 		if (!logical && !STp->scsi2_logical)
3027 			scmd[1] = 1;
3028 	}
3029 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3030 			   STp->device->request_queue->rq_timeout,
3031 			   MAX_READY_RETRIES, 1);
3032 	if (!SRpnt)
3033 		return (STp->buffer)->syscall_result;
3034 
3035 	if ((STp->buffer)->syscall_result != 0 ||
3036 	    (STp->device->scsi_level >= SCSI_2 &&
3037 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3038 		*block = *partition = 0;
3039                 DEBC(printk(ST_DEB_MSG "%s: Can't read tape position.\n", name));
3040 		result = (-EIO);
3041 	} else {
3042 		result = 0;
3043 		if ((STp->device)->scsi_level < SCSI_2) {
3044 			*block = ((STp->buffer)->b_data[0] << 16)
3045 			    + ((STp->buffer)->b_data[1] << 8)
3046 			    + (STp->buffer)->b_data[2];
3047 			*partition = 0;
3048 		} else {
3049 			*block = ((STp->buffer)->b_data[4] << 24)
3050 			    + ((STp->buffer)->b_data[5] << 16)
3051 			    + ((STp->buffer)->b_data[6] << 8)
3052 			    + (STp->buffer)->b_data[7];
3053 			*partition = (STp->buffer)->b_data[1];
3054 			if (((STp->buffer)->b_data[0] & 0x80) &&
3055 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3056 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3057 		}
3058                 DEBC(printk(ST_DEB_MSG "%s: Got tape pos. blk %d part %d.\n", name,
3059                             *block, *partition));
3060 	}
3061 	st_release_request(SRpnt);
3062 	SRpnt = NULL;
3063 
3064 	return result;
3065 }
3066 
3067 
3068 /* Set the tape block and partition. Negative partition means that only the
3069    block should be set in vendor specific way. */
3070 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3071 			int logical)
3072 {
3073 	struct st_partstat *STps;
3074 	int result, p;
3075 	unsigned int blk;
3076 	int timeout;
3077 	unsigned char scmd[MAX_COMMAND_SIZE];
3078 	struct st_request *SRpnt;
3079 	DEB( char *name = tape_name(STp); )
3080 
3081 	if (STp->ready != ST_READY)
3082 		return (-EIO);
3083 	timeout = STp->long_timeout;
3084 	STps = &(STp->ps[STp->partition]);
3085 
3086         DEBC(printk(ST_DEB_MSG "%s: Setting block to %d and partition to %d.\n",
3087                     name, block, partition));
3088 	DEB(if (partition < 0)
3089 		return (-EIO); )
3090 
3091 	/* Update the location at the partition we are leaving */
3092 	if ((!STp->can_partitions && partition != 0) ||
3093 	    partition >= ST_NBR_PARTITIONS)
3094 		return (-EINVAL);
3095 	if (partition != STp->partition) {
3096 		if (get_location(STp, &blk, &p, 1))
3097 			STps->last_block_valid = 0;
3098 		else {
3099 			STps->last_block_valid = 1;
3100 			STps->last_block_visited = blk;
3101                         DEBC(printk(ST_DEB_MSG
3102                                     "%s: Visited block %d for partition %d saved.\n",
3103                                     name, blk, STp->partition));
3104 		}
3105 	}
3106 
3107 	memset(scmd, 0, MAX_COMMAND_SIZE);
3108 	if ((STp->device)->scsi_level < SCSI_2) {
3109 		scmd[0] = QFA_SEEK_BLOCK;
3110 		scmd[2] = (block >> 16);
3111 		scmd[3] = (block >> 8);
3112 		scmd[4] = block;
3113 		scmd[5] = 0;
3114 	} else {
3115 		scmd[0] = SEEK_10;
3116 		scmd[3] = (block >> 24);
3117 		scmd[4] = (block >> 16);
3118 		scmd[5] = (block >> 8);
3119 		scmd[6] = block;
3120 		if (!logical && !STp->scsi2_logical)
3121 			scmd[1] = 4;
3122 		if (STp->partition != partition) {
3123 			scmd[1] |= 2;
3124 			scmd[8] = partition;
3125                         DEBC(printk(ST_DEB_MSG
3126                                     "%s: Trying to change partition from %d to %d\n",
3127                                     name, STp->partition, partition));
3128 		}
3129 	}
3130 	if (STp->immediate) {
3131 		scmd[1] |= 1;		/* Don't wait for completion */
3132 		timeout = STp->device->request_queue->rq_timeout;
3133 	}
3134 
3135 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3136 			   timeout, MAX_READY_RETRIES, 1);
3137 	if (!SRpnt)
3138 		return (STp->buffer)->syscall_result;
3139 
3140 	STps->drv_block = STps->drv_file = (-1);
3141 	STps->eof = ST_NOEOF;
3142 	if ((STp->buffer)->syscall_result != 0) {
3143 		result = (-EIO);
3144 		if (STp->can_partitions &&
3145 		    (STp->device)->scsi_level >= SCSI_2 &&
3146 		    (p = find_partition(STp)) >= 0)
3147 			STp->partition = p;
3148 	} else {
3149 		if (STp->can_partitions) {
3150 			STp->partition = partition;
3151 			STps = &(STp->ps[partition]);
3152 			if (!STps->last_block_valid ||
3153 			    STps->last_block_visited != block) {
3154 				STps->at_sm = 0;
3155 				STps->rw = ST_IDLE;
3156 			}
3157 		} else
3158 			STps->at_sm = 0;
3159 		if (block == 0)
3160 			STps->drv_block = STps->drv_file = 0;
3161 		result = 0;
3162 	}
3163 
3164 	st_release_request(SRpnt);
3165 	SRpnt = NULL;
3166 
3167 	return result;
3168 }
3169 
3170 
3171 /* Find the current partition number for the drive status. Called from open and
3172    returns either partition number of negative error code. */
3173 static int find_partition(struct scsi_tape *STp)
3174 {
3175 	int i, partition;
3176 	unsigned int block;
3177 
3178 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3179 		return i;
3180 	if (partition >= ST_NBR_PARTITIONS)
3181 		return (-EIO);
3182 	return partition;
3183 }
3184 
3185 
3186 /* Change the partition if necessary */
3187 static int switch_partition(struct scsi_tape *STp)
3188 {
3189 	struct st_partstat *STps;
3190 
3191 	if (STp->partition == STp->new_partition)
3192 		return 0;
3193 	STps = &(STp->ps[STp->new_partition]);
3194 	if (!STps->last_block_valid)
3195 		STps->last_block_visited = 0;
3196 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3197 }
3198 
3199 /* Functions for reading and writing the medium partition mode page. */
3200 
3201 #define PART_PAGE   0x11
3202 #define PART_PAGE_FIXED_LENGTH 8
3203 
3204 #define PP_OFF_MAX_ADD_PARTS   2
3205 #define PP_OFF_NBR_ADD_PARTS   3
3206 #define PP_OFF_FLAGS           4
3207 #define PP_OFF_PART_UNITS      6
3208 #define PP_OFF_RESERVED        7
3209 
3210 #define PP_BIT_IDP             0x20
3211 #define PP_MSK_PSUM_MB         0x10
3212 
3213 /* Get the number of partitions on the tape. As a side effect reads the
3214    mode page into the tape buffer. */
3215 static int nbr_partitions(struct scsi_tape *STp)
3216 {
3217 	int result;
3218 	DEB( char *name = tape_name(STp); )
3219 
3220 	if (STp->ready != ST_READY)
3221 		return (-EIO);
3222 
3223 	result = read_mode_page(STp, PART_PAGE, 1);
3224 
3225 	if (result) {
3226                 DEBC(printk(ST_DEB_MSG "%s: Can't read medium partition page.\n",
3227                             name));
3228 		result = (-EIO);
3229 	} else {
3230 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3231 					      PP_OFF_NBR_ADD_PARTS] + 1;
3232                 DEBC(printk(ST_DEB_MSG "%s: Number of partitions %d.\n", name, result));
3233 	}
3234 
3235 	return result;
3236 }
3237 
3238 
3239 /* Partition the tape into two partitions if size > 0 or one partition if
3240    size == 0.
3241 
3242    The block descriptors are read and written because Sony SDT-7000 does not
3243    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3244 
3245    My HP C1533A drive returns only one partition size field. This is used to
3246    set the size of partition 1. There is no size field for the default partition.
3247    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3248    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3249    The following algorithm is used to accommodate both drives: if the number of
3250    partition size fields is greater than the maximum number of additional partitions
3251    in the mode page, the second field is used. Otherwise the first field is used.
3252 
3253    For Seagate DDS drives the page length must be 8 when no partitions is defined
3254    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3255    is acceptable also to some other old drives and enforced if the first partition
3256    size field is used for the first additional partition size.
3257  */
3258 static int partition_tape(struct scsi_tape *STp, int size)
3259 {
3260 	char *name = tape_name(STp);
3261 	int result;
3262 	int pgo, psd_cnt, psdo;
3263 	unsigned char *bp;
3264 
3265 	result = read_mode_page(STp, PART_PAGE, 0);
3266 	if (result) {
3267 		DEBC(printk(ST_DEB_MSG "%s: Can't read partition mode page.\n", name));
3268 		return result;
3269 	}
3270 	/* The mode page is in the buffer. Let's modify it and write it. */
3271 	bp = (STp->buffer)->b_data;
3272 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3273 	DEBC(printk(ST_DEB_MSG "%s: Partition page length is %d bytes.\n",
3274 		    name, bp[pgo + MP_OFF_PAGE_LENGTH] + 2));
3275 
3276 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3277 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3278 	if (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS]) {
3279 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest of the tape */
3280 		psdo += 2;
3281 	}
3282 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3283 
3284 	DEBC(printk("%s: psd_cnt %d, max.parts %d, nbr_parts %d\n", name,
3285 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3286 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]));
3287 
3288 	if (size <= 0) {
3289 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3290 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3291 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3292                 DEBC(printk(ST_DEB_MSG "%s: Formatting tape with one partition.\n",
3293                             name));
3294 	} else {
3295 		bp[psdo] = (size >> 8) & 0xff;
3296 		bp[psdo + 1] = size & 0xff;
3297 		bp[pgo + 3] = 1;
3298 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3299 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3300                 DEBC(printk(ST_DEB_MSG
3301                             "%s: Formatting tape with two partitions (1 = %d MB).\n",
3302                             name, size));
3303 	}
3304 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3305 	bp[pgo + PP_OFF_RESERVED] = 0;
3306 	bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | PP_MSK_PSUM_MB;
3307 
3308 	result = write_mode_page(STp, PART_PAGE, 1);
3309 	if (result) {
3310 		printk(KERN_INFO "%s: Partitioning of tape failed.\n", name);
3311 		result = (-EIO);
3312 	}
3313 
3314 	return result;
3315 }
3316 
3317 
3318 
3319 /* The ioctl command */
3320 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3321 {
3322 	int i, cmd_nr, cmd_type, bt;
3323 	int retval = 0;
3324 	unsigned int blk;
3325 	struct scsi_tape *STp = file->private_data;
3326 	struct st_modedef *STm;
3327 	struct st_partstat *STps;
3328 	char *name = tape_name(STp);
3329 	void __user *p = (void __user *)arg;
3330 
3331 	if (mutex_lock_interruptible(&STp->lock))
3332 		return -ERESTARTSYS;
3333 
3334         DEB(
3335 	if (debugging && !STp->in_use) {
3336 		printk(ST_DEB_MSG "%s: Incorrect device.\n", name);
3337 		retval = (-EIO);
3338 		goto out;
3339 	} ) /* end DEB */
3340 
3341 	STm = &(STp->modes[STp->current_mode]);
3342 	STps = &(STp->ps[STp->partition]);
3343 
3344 	/*
3345 	 * If we are in the middle of error recovery, don't let anyone
3346 	 * else try and use this device.  Also, if error recovery fails, it
3347 	 * may try and take the device offline, in which case all further
3348 	 * access to the device is prohibited.
3349 	 */
3350 	retval = scsi_nonblockable_ioctl(STp->device, cmd_in, p,
3351 					file->f_flags & O_NDELAY);
3352 	if (!scsi_block_when_processing_errors(STp->device) || retval != -ENODEV)
3353 		goto out;
3354 	retval = 0;
3355 
3356 	cmd_type = _IOC_TYPE(cmd_in);
3357 	cmd_nr = _IOC_NR(cmd_in);
3358 
3359 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3360 		struct mtop mtc;
3361 
3362 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3363 			retval = (-EINVAL);
3364 			goto out;
3365 		}
3366 
3367 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3368 		if (i) {
3369 			retval = (-EFAULT);
3370 			goto out;
3371 		}
3372 
3373 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3374 			printk(KERN_WARNING
3375                                "%s: MTSETDRVBUFFER only allowed for root.\n", name);
3376 			retval = (-EPERM);
3377 			goto out;
3378 		}
3379 		if (!STm->defined &&
3380 		    (mtc.mt_op != MTSETDRVBUFFER &&
3381 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3382 			retval = (-ENXIO);
3383 			goto out;
3384 		}
3385 
3386 		if (!STp->pos_unknown) {
3387 
3388 			if (STps->eof == ST_FM_HIT) {
3389 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3390                                     mtc.mt_op == MTEOM) {
3391 					mtc.mt_count -= 1;
3392 					if (STps->drv_file >= 0)
3393 						STps->drv_file += 1;
3394 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3395 					mtc.mt_count += 1;
3396 					if (STps->drv_file >= 0)
3397 						STps->drv_file += 1;
3398 				}
3399 			}
3400 
3401 			if (mtc.mt_op == MTSEEK) {
3402 				/* Old position must be restored if partition will be
3403                                    changed */
3404 				i = !STp->can_partitions ||
3405 				    (STp->new_partition != STp->partition);
3406 			} else {
3407 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3408 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3409 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3410 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3411 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3412 				    mtc.mt_op == MTCOMPRESSION;
3413 			}
3414 			i = flush_buffer(STp, i);
3415 			if (i < 0) {
3416 				retval = i;
3417 				goto out;
3418 			}
3419 			if (STps->rw == ST_WRITING &&
3420 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3421 			     mtc.mt_op == MTSEEK ||
3422 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3423 				i = st_int_ioctl(STp, MTWEOF, 1);
3424 				if (i < 0) {
3425 					retval = i;
3426 					goto out;
3427 				}
3428 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3429 					mtc.mt_count++;
3430 				STps->rw = ST_IDLE;
3431 			     }
3432 
3433 		} else {
3434 			/*
3435 			 * If there was a bus reset, block further access
3436 			 * to this device.  If the user wants to rewind the tape,
3437 			 * then reset the flag and allow access again.
3438 			 */
3439 			if (mtc.mt_op != MTREW &&
3440 			    mtc.mt_op != MTOFFL &&
3441 			    mtc.mt_op != MTRETEN &&
3442 			    mtc.mt_op != MTERASE &&
3443 			    mtc.mt_op != MTSEEK &&
3444 			    mtc.mt_op != MTEOM) {
3445 				retval = (-EIO);
3446 				goto out;
3447 			}
3448 			reset_state(STp);
3449 			/* remove this when the midlevel properly clears was_reset */
3450 			STp->device->was_reset = 0;
3451 		}
3452 
3453 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3454 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3455 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3456 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3457 
3458 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3459 			do_door_lock(STp, 0);	/* Ignore result! */
3460 
3461 		if (mtc.mt_op == MTSETDRVBUFFER &&
3462 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3463 			retval = st_set_options(STp, mtc.mt_count);
3464 			goto out;
3465 		}
3466 
3467 		if (mtc.mt_op == MTSETPART) {
3468 			if (!STp->can_partitions ||
3469 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3470 				retval = (-EINVAL);
3471 				goto out;
3472 			}
3473 			if (mtc.mt_count >= STp->nbr_partitions &&
3474 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3475 				retval = (-EIO);
3476 				goto out;
3477 			}
3478 			if (mtc.mt_count >= STp->nbr_partitions) {
3479 				retval = (-EINVAL);
3480 				goto out;
3481 			}
3482 			STp->new_partition = mtc.mt_count;
3483 			retval = 0;
3484 			goto out;
3485 		}
3486 
3487 		if (mtc.mt_op == MTMKPART) {
3488 			if (!STp->can_partitions) {
3489 				retval = (-EINVAL);
3490 				goto out;
3491 			}
3492 			if ((i = st_int_ioctl(STp, MTREW, 0)) < 0 ||
3493 			    (i = partition_tape(STp, mtc.mt_count)) < 0) {
3494 				retval = i;
3495 				goto out;
3496 			}
3497 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3498 				STp->ps[i].rw = ST_IDLE;
3499 				STp->ps[i].at_sm = 0;
3500 				STp->ps[i].last_block_valid = 0;
3501 			}
3502 			STp->partition = STp->new_partition = 0;
3503 			STp->nbr_partitions = 1;	/* Bad guess ?-) */
3504 			STps->drv_block = STps->drv_file = 0;
3505 			retval = 0;
3506 			goto out;
3507 		}
3508 
3509 		if (mtc.mt_op == MTSEEK) {
3510 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3511 			if (!STp->can_partitions)
3512 				STp->ps[0].rw = ST_IDLE;
3513 			retval = i;
3514 			goto out;
3515 		}
3516 
3517 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3518 			retval = do_load_unload(STp, file, 0);
3519 			goto out;
3520 		}
3521 
3522 		if (mtc.mt_op == MTLOAD) {
3523 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3524 			goto out;
3525 		}
3526 
3527 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3528 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3529 			goto out;
3530 		}
3531 
3532 		if (STp->can_partitions && STp->ready == ST_READY &&
3533 		    (i = switch_partition(STp)) < 0) {
3534 			retval = i;
3535 			goto out;
3536 		}
3537 
3538 		if (mtc.mt_op == MTCOMPRESSION)
3539 			retval = st_compression(STp, (mtc.mt_count & 1));
3540 		else
3541 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3542 		goto out;
3543 	}
3544 	if (!STm->defined) {
3545 		retval = (-ENXIO);
3546 		goto out;
3547 	}
3548 
3549 	if ((i = flush_buffer(STp, 0)) < 0) {
3550 		retval = i;
3551 		goto out;
3552 	}
3553 	if (STp->can_partitions &&
3554 	    (i = switch_partition(STp)) < 0) {
3555 		retval = i;
3556 		goto out;
3557 	}
3558 
3559 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3560 		struct mtget mt_status;
3561 
3562 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3563 			 retval = (-EINVAL);
3564 			 goto out;
3565 		}
3566 
3567 		mt_status.mt_type = STp->tape_type;
3568 		mt_status.mt_dsreg =
3569 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3570 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3571 		mt_status.mt_blkno = STps->drv_block;
3572 		mt_status.mt_fileno = STps->drv_file;
3573 		if (STp->block_size != 0) {
3574 			if (STps->rw == ST_WRITING)
3575 				mt_status.mt_blkno +=
3576 				    (STp->buffer)->buffer_bytes / STp->block_size;
3577 			else if (STps->rw == ST_READING)
3578 				mt_status.mt_blkno -=
3579                                         ((STp->buffer)->buffer_bytes +
3580                                          STp->block_size - 1) / STp->block_size;
3581 		}
3582 
3583 		mt_status.mt_gstat = 0;
3584 		if (STp->drv_write_prot)
3585 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3586 		if (mt_status.mt_blkno == 0) {
3587 			if (mt_status.mt_fileno == 0)
3588 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3589 			else
3590 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3591 		}
3592 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3593 		mt_status.mt_resid = STp->partition;
3594 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3595 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3596 		else if (STps->eof >= ST_EOM_OK)
3597 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3598 		if (STp->density == 1)
3599 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3600 		else if (STp->density == 2)
3601 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3602 		else if (STp->density == 3)
3603 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3604 		if (STp->ready == ST_READY)
3605 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3606 		if (STp->ready == ST_NO_TAPE)
3607 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3608 		if (STps->at_sm)
3609 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3610 		if (STm->do_async_writes ||
3611                     (STm->do_buffer_writes && STp->block_size != 0) ||
3612 		    STp->drv_buffer != 0)
3613 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3614 		if (STp->cleaning_req)
3615 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3616 
3617 		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
3618 		if (i) {
3619 			retval = (-EFAULT);
3620 			goto out;
3621 		}
3622 
3623 		STp->recover_reg = 0;		/* Clear after read */
3624 		retval = 0;
3625 		goto out;
3626 	}			/* End of MTIOCGET */
3627 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3628 		struct mtpos mt_pos;
3629 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3630 			 retval = (-EINVAL);
3631 			 goto out;
3632 		}
3633 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3634 			retval = i;
3635 			goto out;
3636 		}
3637 		mt_pos.mt_blkno = blk;
3638 		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
3639 		if (i)
3640 			retval = (-EFAULT);
3641 		goto out;
3642 	}
3643 	mutex_unlock(&STp->lock);
3644 	switch (cmd_in) {
3645 		case SCSI_IOCTL_GET_IDLUN:
3646 		case SCSI_IOCTL_GET_BUS_NUMBER:
3647 			break;
3648 		default:
3649 			if ((cmd_in == SG_IO ||
3650 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3651 			     cmd_in == CDROM_SEND_PACKET) &&
3652 			    !capable(CAP_SYS_RAWIO))
3653 				i = -EPERM;
3654 			else
3655 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3656 						   file->f_mode, cmd_in, p);
3657 			if (i != -ENOTTY)
3658 				return i;
3659 			break;
3660 	}
3661 	retval = scsi_ioctl(STp->device, cmd_in, p);
3662 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3663 		STp->rew_at_close = 0;
3664 		STp->ready = ST_NO_TAPE;
3665 	}
3666 	return retval;
3667 
3668  out:
3669 	mutex_unlock(&STp->lock);
3670 	return retval;
3671 }
3672 
3673 #ifdef CONFIG_COMPAT
3674 static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3675 {
3676 	struct scsi_tape *STp = file->private_data;
3677 	struct scsi_device *sdev = STp->device;
3678 	int ret = -ENOIOCTLCMD;
3679 	if (sdev->host->hostt->compat_ioctl) {
3680 
3681 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
3682 
3683 	}
3684 	return ret;
3685 }
3686 #endif
3687 
3688 
3689 
3690 /* Try to allocate a new tape buffer. Calling function must not hold
3691    dev_arr_lock. */
3692 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3693 {
3694 	struct st_buffer *tb;
3695 
3696 	tb = kzalloc(sizeof(struct st_buffer), GFP_ATOMIC);
3697 	if (!tb) {
3698 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3699 		return NULL;
3700 	}
3701 	tb->frp_segs = 0;
3702 	tb->use_sg = max_sg;
3703 	tb->dma = need_dma;
3704 	tb->buffer_size = 0;
3705 
3706 	tb->reserved_pages = kzalloc(max_sg * sizeof(struct page *),
3707 				     GFP_ATOMIC);
3708 	if (!tb->reserved_pages) {
3709 		kfree(tb);
3710 		return NULL;
3711 	}
3712 
3713 	return tb;
3714 }
3715 
3716 
3717 /* Try to allocate enough space in the tape buffer */
3718 #define ST_MAX_ORDER 6
3719 
3720 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3721 {
3722 	int segs, nbr, max_segs, b_size, order, got;
3723 	gfp_t priority;
3724 
3725 	if (new_size <= STbuffer->buffer_size)
3726 		return 1;
3727 
3728 	if (STbuffer->buffer_size <= PAGE_SIZE)
3729 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3730 
3731 	max_segs = STbuffer->use_sg;
3732 	nbr = max_segs - STbuffer->frp_segs;
3733 	if (nbr <= 0)
3734 		return 0;
3735 
3736 	priority = GFP_KERNEL | __GFP_NOWARN;
3737 	if (need_dma)
3738 		priority |= GFP_DMA;
3739 
3740 	if (STbuffer->cleared)
3741 		priority |= __GFP_ZERO;
3742 
3743 	if (STbuffer->frp_segs) {
3744 		order = STbuffer->reserved_page_order;
3745 		b_size = PAGE_SIZE << order;
3746 	} else {
3747 		for (b_size = PAGE_SIZE, order = 0;
3748 		     order < ST_MAX_ORDER &&
3749 			     max_segs * (PAGE_SIZE << order) < new_size;
3750 		     order++, b_size *= 2)
3751 			;  /* empty */
3752 		STbuffer->reserved_page_order = order;
3753 	}
3754 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3755 		if (order == ST_MAX_ORDER)
3756 			return 0;
3757 		normalize_buffer(STbuffer);
3758 		return enlarge_buffer(STbuffer, new_size, need_dma);
3759 	}
3760 
3761 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3762 	     segs < max_segs && got < new_size;) {
3763 		struct page *page;
3764 
3765 		page = alloc_pages(priority, order);
3766 		if (!page) {
3767 			DEB(STbuffer->buffer_size = got);
3768 			normalize_buffer(STbuffer);
3769 			return 0;
3770 		}
3771 
3772 		STbuffer->frp_segs += 1;
3773 		got += b_size;
3774 		STbuffer->buffer_size = got;
3775 		STbuffer->reserved_pages[segs] = page;
3776 		segs++;
3777 	}
3778 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3779 
3780 	return 1;
3781 }
3782 
3783 
3784 /* Make sure that no data from previous user is in the internal buffer */
3785 static void clear_buffer(struct st_buffer * st_bp)
3786 {
3787 	int i;
3788 
3789 	for (i=0; i < st_bp->frp_segs; i++)
3790 		memset(page_address(st_bp->reserved_pages[i]), 0,
3791 		       PAGE_SIZE << st_bp->reserved_page_order);
3792 	st_bp->cleared = 1;
3793 }
3794 
3795 
3796 /* Release the extra buffer */
3797 static void normalize_buffer(struct st_buffer * STbuffer)
3798 {
3799 	int i, order = STbuffer->reserved_page_order;
3800 
3801 	for (i = 0; i < STbuffer->frp_segs; i++) {
3802 		__free_pages(STbuffer->reserved_pages[i], order);
3803 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3804 	}
3805 	STbuffer->frp_segs = 0;
3806 	STbuffer->sg_segs = 0;
3807 	STbuffer->reserved_page_order = 0;
3808 	STbuffer->map_data.offset = 0;
3809 }
3810 
3811 
3812 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3813    negative error code. */
3814 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3815 {
3816 	int i, cnt, res, offset;
3817 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3818 
3819 	for (i = 0, offset = st_bp->buffer_bytes;
3820 	     i < st_bp->frp_segs && offset >= length; i++)
3821 		offset -= length;
3822 	if (i == st_bp->frp_segs) {	/* Should never happen */
3823 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
3824 		return (-EIO);
3825 	}
3826 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3827 		struct page *page = st_bp->reserved_pages[i];
3828 		cnt = length - offset < do_count ? length - offset : do_count;
3829 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
3830 		if (res)
3831 			return (-EFAULT);
3832 		do_count -= cnt;
3833 		st_bp->buffer_bytes += cnt;
3834 		ubp += cnt;
3835 		offset = 0;
3836 	}
3837 	if (do_count) /* Should never happen */
3838 		return (-EIO);
3839 
3840 	return 0;
3841 }
3842 
3843 
3844 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
3845    negative error code. */
3846 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
3847 {
3848 	int i, cnt, res, offset;
3849 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3850 
3851 	for (i = 0, offset = st_bp->read_pointer;
3852 	     i < st_bp->frp_segs && offset >= length; i++)
3853 		offset -= length;
3854 	if (i == st_bp->frp_segs) {	/* Should never happen */
3855 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
3856 		return (-EIO);
3857 	}
3858 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3859 		struct page *page = st_bp->reserved_pages[i];
3860 		cnt = length - offset < do_count ? length - offset : do_count;
3861 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
3862 		if (res)
3863 			return (-EFAULT);
3864 		do_count -= cnt;
3865 		st_bp->buffer_bytes -= cnt;
3866 		st_bp->read_pointer += cnt;
3867 		ubp += cnt;
3868 		offset = 0;
3869 	}
3870 	if (do_count) /* Should never happen */
3871 		return (-EIO);
3872 
3873 	return 0;
3874 }
3875 
3876 
3877 /* Move data towards start of buffer */
3878 static void move_buffer_data(struct st_buffer * st_bp, int offset)
3879 {
3880 	int src_seg, dst_seg, src_offset = 0, dst_offset;
3881 	int count, total;
3882 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3883 
3884 	if (offset == 0)
3885 		return;
3886 
3887 	total=st_bp->buffer_bytes - offset;
3888 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
3889 		src_offset = offset;
3890 		if (src_offset < length)
3891 			break;
3892 		offset -= length;
3893 	}
3894 
3895 	st_bp->buffer_bytes = st_bp->read_pointer = total;
3896 	for (dst_seg=dst_offset=0; total > 0; ) {
3897 		struct page *dpage = st_bp->reserved_pages[dst_seg];
3898 		struct page *spage = st_bp->reserved_pages[src_seg];
3899 
3900 		count = min(length - dst_offset, length - src_offset);
3901 		memmove(page_address(dpage) + dst_offset,
3902 			page_address(spage) + src_offset, count);
3903 		src_offset += count;
3904 		if (src_offset >= length) {
3905 			src_seg++;
3906 			src_offset = 0;
3907 		}
3908 		dst_offset += count;
3909 		if (dst_offset >= length) {
3910 			dst_seg++;
3911 			dst_offset = 0;
3912 		}
3913 		total -= count;
3914 	}
3915 }
3916 
3917 /* Validate the options from command line or module parameters */
3918 static void validate_options(void)
3919 {
3920 	if (buffer_kbs > 0)
3921 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
3922 	if (max_sg_segs >= ST_FIRST_SG)
3923 		st_max_sg_segs = max_sg_segs;
3924 }
3925 
3926 #ifndef MODULE
3927 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
3928  */
3929 static int __init st_setup(char *str)
3930 {
3931 	int i, len, ints[5];
3932 	char *stp;
3933 
3934 	stp = get_options(str, ARRAY_SIZE(ints), ints);
3935 
3936 	if (ints[0] > 0) {
3937 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
3938 			if (parms[i].val)
3939 				*parms[i].val = ints[i + 1];
3940 	} else {
3941 		while (stp != NULL) {
3942 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
3943 				len = strlen(parms[i].name);
3944 				if (!strncmp(stp, parms[i].name, len) &&
3945 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
3946 					if (parms[i].val)
3947 						*parms[i].val =
3948 							simple_strtoul(stp + len + 1, NULL, 0);
3949 					else
3950 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
3951 						       parms[i].name);
3952 					break;
3953 				}
3954 			}
3955 			if (i >= ARRAY_SIZE(parms))
3956 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
3957 					stp);
3958 			stp = strchr(stp, ',');
3959 			if (stp)
3960 				stp++;
3961 		}
3962 	}
3963 
3964 	validate_options();
3965 
3966 	return 1;
3967 }
3968 
3969 __setup("st=", st_setup);
3970 
3971 #endif
3972 
3973 static const struct file_operations st_fops =
3974 {
3975 	.owner =	THIS_MODULE,
3976 	.read =		st_read,
3977 	.write =	st_write,
3978 	.unlocked_ioctl = st_ioctl,
3979 #ifdef CONFIG_COMPAT
3980 	.compat_ioctl = st_compat_ioctl,
3981 #endif
3982 	.open =		st_open,
3983 	.flush =	st_flush,
3984 	.release =	st_release,
3985 	.llseek =	noop_llseek,
3986 };
3987 
3988 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
3989 {
3990 	int i, error;
3991 	dev_t cdev_devno;
3992 	struct cdev *cdev;
3993 	struct device *dev;
3994 	struct st_modedef *STm = &(tape->modes[mode]);
3995 	char name[10];
3996 	int dev_num = tape->index;
3997 
3998 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
3999 
4000 	cdev = cdev_alloc();
4001 	if (!cdev) {
4002 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4003 		error = -ENOMEM;
4004 		goto out;
4005 	}
4006 	cdev->owner = THIS_MODULE;
4007 	cdev->ops = &st_fops;
4008 
4009 	error = cdev_add(cdev, cdev_devno, 1);
4010 	if (error) {
4011 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4012 		       rew ? "non" : "auto", mode);
4013 		pr_err("st%d: Device not attached.\n", dev_num);
4014 		goto out_free;
4015 	}
4016 	STm->cdevs[rew] = cdev;
4017 
4018 	i = mode << (4 - ST_NBR_MODE_BITS);
4019 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4020 		 tape->disk->disk_name, st_formats[i]);
4021 
4022 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4023 			    cdev_devno, &tape->modes[mode], "%s", name);
4024 	if (IS_ERR(dev)) {
4025 		pr_err("st%d: device_create failed\n", dev_num);
4026 		error = PTR_ERR(dev);
4027 		goto out_free;
4028 	}
4029 
4030 	STm->devs[rew] = dev;
4031 
4032 	return 0;
4033 out_free:
4034 	cdev_del(STm->cdevs[rew]);
4035 	STm->cdevs[rew] = NULL;
4036 out:
4037 	return error;
4038 }
4039 
4040 static int create_cdevs(struct scsi_tape *tape)
4041 {
4042 	int mode, error;
4043 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4044 		error = create_one_cdev(tape, mode, 0);
4045 		if (error)
4046 			return error;
4047 		error = create_one_cdev(tape, mode, 1);
4048 		if (error)
4049 			return error;
4050 	}
4051 
4052 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4053 				 &tape->modes[0].devs[0]->kobj, "tape");
4054 }
4055 
4056 static void remove_cdevs(struct scsi_tape *tape)
4057 {
4058 	int mode, rew;
4059 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4060 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4061 		struct st_modedef *STm = &(tape->modes[mode]);
4062 		for (rew = 0; rew < 2; rew++) {
4063 			if (STm->cdevs[rew])
4064 				cdev_del(STm->cdevs[rew]);
4065 			if (STm->devs[rew])
4066 				device_unregister(STm->devs[rew]);
4067 		}
4068 	}
4069 }
4070 
4071 static int st_probe(struct device *dev)
4072 {
4073 	struct scsi_device *SDp = to_scsi_device(dev);
4074 	struct gendisk *disk = NULL;
4075 	struct scsi_tape *tpnt = NULL;
4076 	struct st_modedef *STm;
4077 	struct st_partstat *STps;
4078 	struct st_buffer *buffer;
4079 	int i, dev_num, error;
4080 	char *stp;
4081 
4082 	if (SDp->type != TYPE_TAPE)
4083 		return -ENODEV;
4084 	if ((stp = st_incompatible(SDp))) {
4085 		sdev_printk(KERN_INFO, SDp, "Found incompatible tape\n");
4086 		printk(KERN_INFO "st: The suggested driver is %s.\n", stp);
4087 		return -ENODEV;
4088 	}
4089 
4090 	i = queue_max_segments(SDp->request_queue);
4091 	if (st_max_sg_segs < i)
4092 		i = st_max_sg_segs;
4093 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
4094 	if (buffer == NULL) {
4095 		printk(KERN_ERR
4096 		       "st: Can't allocate new tape buffer. Device not attached.\n");
4097 		goto out;
4098 	}
4099 
4100 	disk = alloc_disk(1);
4101 	if (!disk) {
4102 		printk(KERN_ERR "st: out of memory. Device not attached.\n");
4103 		goto out_buffer_free;
4104 	}
4105 
4106 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
4107 	if (tpnt == NULL) {
4108 		printk(KERN_ERR "st: Can't allocate device descriptor.\n");
4109 		goto out_put_disk;
4110 	}
4111 	kref_init(&tpnt->kref);
4112 	tpnt->disk = disk;
4113 	disk->private_data = &tpnt->driver;
4114 	disk->queue = SDp->request_queue;
4115 	tpnt->driver = &st_template;
4116 
4117 	tpnt->device = SDp;
4118 	if (SDp->scsi_level <= 2)
4119 		tpnt->tape_type = MT_ISSCSI1;
4120 	else
4121 		tpnt->tape_type = MT_ISSCSI2;
4122 
4123 	tpnt->buffer = buffer;
4124 	tpnt->buffer->last_SRpnt = NULL;
4125 
4126 	tpnt->inited = 0;
4127 	tpnt->dirty = 0;
4128 	tpnt->in_use = 0;
4129 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4130 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4131 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4132 	tpnt->density = 0;
4133 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4134 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4135 	tpnt->can_partitions = 0;
4136 	tpnt->two_fm = ST_TWO_FM;
4137 	tpnt->fast_mteom = ST_FAST_MTEOM;
4138 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4139 	tpnt->sili = ST_SILI;
4140 	tpnt->immediate = ST_NOWAIT;
4141 	tpnt->immediate_filemark = 0;
4142 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4143 	tpnt->partition = 0;
4144 	tpnt->new_partition = 0;
4145 	tpnt->nbr_partitions = 0;
4146 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4147 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4148 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4149 
4150 	for (i = 0; i < ST_NBR_MODES; i++) {
4151 		STm = &(tpnt->modes[i]);
4152 		STm->defined = 0;
4153 		STm->sysv = ST_SYSV;
4154 		STm->defaults_for_writes = 0;
4155 		STm->do_async_writes = ST_ASYNC_WRITES;
4156 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4157 		STm->do_read_ahead = ST_READ_AHEAD;
4158 		STm->default_compression = ST_DONT_TOUCH;
4159 		STm->default_blksize = (-1);	/* No forced size */
4160 		STm->default_density = (-1);	/* No forced density */
4161 		STm->tape = tpnt;
4162 	}
4163 
4164 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4165 		STps = &(tpnt->ps[i]);
4166 		STps->rw = ST_IDLE;
4167 		STps->eof = ST_NOEOF;
4168 		STps->at_sm = 0;
4169 		STps->last_block_valid = 0;
4170 		STps->drv_block = (-1);
4171 		STps->drv_file = (-1);
4172 	}
4173 
4174 	tpnt->current_mode = 0;
4175 	tpnt->modes[0].defined = 1;
4176 
4177 	tpnt->density_changed = tpnt->compression_changed =
4178 	    tpnt->blksize_changed = 0;
4179 	mutex_init(&tpnt->lock);
4180 
4181 	if (!idr_pre_get(&st_index_idr, GFP_KERNEL)) {
4182 		pr_warn("st: idr expansion failed\n");
4183 		error = -ENOMEM;
4184 		goto out_put_disk;
4185 	}
4186 
4187 	spin_lock(&st_index_lock);
4188 	error = idr_get_new(&st_index_idr, tpnt, &dev_num);
4189 	spin_unlock(&st_index_lock);
4190 	if (error) {
4191 		pr_warn("st: idr allocation failed: %d\n", error);
4192 		goto out_put_disk;
4193 	}
4194 
4195 	if (dev_num > ST_MAX_TAPES) {
4196 		pr_err("st: Too many tape devices (max. %d).\n", ST_MAX_TAPES);
4197 		goto out_put_index;
4198 	}
4199 
4200 	tpnt->index = dev_num;
4201 	sprintf(disk->disk_name, "st%d", dev_num);
4202 
4203 	dev_set_drvdata(dev, tpnt);
4204 
4205 
4206 	error = create_cdevs(tpnt);
4207 	if (error)
4208 		goto out_remove_devs;
4209 	scsi_autopm_put_device(SDp);
4210 
4211 	sdev_printk(KERN_NOTICE, SDp,
4212 		    "Attached scsi tape %s\n", tape_name(tpnt));
4213 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4214 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4215 		    queue_dma_alignment(SDp->request_queue) + 1);
4216 
4217 	return 0;
4218 
4219 out_remove_devs:
4220 	remove_cdevs(tpnt);
4221 out_put_index:
4222 	spin_lock(&st_index_lock);
4223 	idr_remove(&st_index_idr, dev_num);
4224 	spin_unlock(&st_index_lock);
4225 out_put_disk:
4226 	put_disk(disk);
4227 	kfree(tpnt);
4228 out_buffer_free:
4229 	kfree(buffer);
4230 out:
4231 	return -ENODEV;
4232 };
4233 
4234 
4235 static int st_remove(struct device *dev)
4236 {
4237 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4238 	int index = tpnt->index;
4239 
4240 	scsi_autopm_get_device(to_scsi_device(dev));
4241 	remove_cdevs(tpnt);
4242 
4243 	mutex_lock(&st_ref_mutex);
4244 	kref_put(&tpnt->kref, scsi_tape_release);
4245 	mutex_unlock(&st_ref_mutex);
4246 	spin_lock(&st_index_lock);
4247 	idr_remove(&st_index_idr, index);
4248 	spin_unlock(&st_index_lock);
4249 	return 0;
4250 }
4251 
4252 /**
4253  *      scsi_tape_release - Called to free the Scsi_Tape structure
4254  *      @kref: pointer to embedded kref
4255  *
4256  *      st_ref_mutex must be held entering this routine.  Because it is
4257  *      called on last put, you should always use the scsi_tape_get()
4258  *      scsi_tape_put() helpers which manipulate the semaphore directly
4259  *      and never do a direct kref_put().
4260  **/
4261 static void scsi_tape_release(struct kref *kref)
4262 {
4263 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4264 	struct gendisk *disk = tpnt->disk;
4265 
4266 	tpnt->device = NULL;
4267 
4268 	if (tpnt->buffer) {
4269 		normalize_buffer(tpnt->buffer);
4270 		kfree(tpnt->buffer->reserved_pages);
4271 		kfree(tpnt->buffer);
4272 	}
4273 
4274 	disk->private_data = NULL;
4275 	put_disk(disk);
4276 	kfree(tpnt);
4277 	return;
4278 }
4279 
4280 static struct class st_sysfs_class = {
4281 	.name = "scsi_tape",
4282 	.dev_attrs = st_dev_attrs,
4283 };
4284 
4285 static int __init init_st(void)
4286 {
4287 	int err;
4288 
4289 	validate_options();
4290 
4291 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4292 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4293 
4294 	err = class_register(&st_sysfs_class);
4295 	if (err) {
4296 		pr_err("Unable register sysfs class for SCSI tapes\n");
4297 		return err;
4298 	}
4299 
4300 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4301 				     ST_MAX_TAPE_ENTRIES, "st");
4302 	if (err) {
4303 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4304 		       SCSI_TAPE_MAJOR);
4305 		goto err_class;
4306 	}
4307 
4308 	err = scsi_register_driver(&st_template.gendrv);
4309 	if (err)
4310 		goto err_chrdev;
4311 
4312 	err = do_create_sysfs_files();
4313 	if (err)
4314 		goto err_scsidrv;
4315 
4316 	return 0;
4317 
4318 err_scsidrv:
4319 	scsi_unregister_driver(&st_template.gendrv);
4320 err_chrdev:
4321 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4322 				 ST_MAX_TAPE_ENTRIES);
4323 err_class:
4324 	class_unregister(&st_sysfs_class);
4325 	return err;
4326 }
4327 
4328 static void __exit exit_st(void)
4329 {
4330 	do_remove_sysfs_files();
4331 	scsi_unregister_driver(&st_template.gendrv);
4332 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4333 				 ST_MAX_TAPE_ENTRIES);
4334 	class_unregister(&st_sysfs_class);
4335 	printk(KERN_INFO "st: Unloaded.\n");
4336 }
4337 
4338 module_init(init_st);
4339 module_exit(exit_st);
4340 
4341 
4342 /* The sysfs driver interface. Read-only at the moment */
4343 static ssize_t st_try_direct_io_show(struct device_driver *ddp, char *buf)
4344 {
4345 	return snprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4346 }
4347 static DRIVER_ATTR(try_direct_io, S_IRUGO, st_try_direct_io_show, NULL);
4348 
4349 static ssize_t st_fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4350 {
4351 	return snprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4352 }
4353 static DRIVER_ATTR(fixed_buffer_size, S_IRUGO, st_fixed_buffer_size_show, NULL);
4354 
4355 static ssize_t st_max_sg_segs_show(struct device_driver *ddp, char *buf)
4356 {
4357 	return snprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4358 }
4359 static DRIVER_ATTR(max_sg_segs, S_IRUGO, st_max_sg_segs_show, NULL);
4360 
4361 static ssize_t st_version_show(struct device_driver *ddd, char *buf)
4362 {
4363 	return snprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4364 }
4365 static DRIVER_ATTR(version, S_IRUGO, st_version_show, NULL);
4366 
4367 static int do_create_sysfs_files(void)
4368 {
4369 	struct device_driver *sysfs = &st_template.gendrv;
4370 	int err;
4371 
4372 	err = driver_create_file(sysfs, &driver_attr_try_direct_io);
4373 	if (err)
4374 		return err;
4375 	err = driver_create_file(sysfs, &driver_attr_fixed_buffer_size);
4376 	if (err)
4377 		goto err_try_direct_io;
4378 	err = driver_create_file(sysfs, &driver_attr_max_sg_segs);
4379 	if (err)
4380 		goto err_attr_fixed_buf;
4381 	err = driver_create_file(sysfs, &driver_attr_version);
4382 	if (err)
4383 		goto err_attr_max_sg;
4384 
4385 	return 0;
4386 
4387 err_attr_max_sg:
4388 	driver_remove_file(sysfs, &driver_attr_max_sg_segs);
4389 err_attr_fixed_buf:
4390 	driver_remove_file(sysfs, &driver_attr_fixed_buffer_size);
4391 err_try_direct_io:
4392 	driver_remove_file(sysfs, &driver_attr_try_direct_io);
4393 	return err;
4394 }
4395 
4396 static void do_remove_sysfs_files(void)
4397 {
4398 	struct device_driver *sysfs = &st_template.gendrv;
4399 
4400 	driver_remove_file(sysfs, &driver_attr_version);
4401 	driver_remove_file(sysfs, &driver_attr_max_sg_segs);
4402 	driver_remove_file(sysfs, &driver_attr_fixed_buffer_size);
4403 	driver_remove_file(sysfs, &driver_attr_try_direct_io);
4404 }
4405 
4406 /* The sysfs simple class interface */
4407 static ssize_t
4408 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4409 {
4410 	struct st_modedef *STm = dev_get_drvdata(dev);
4411 	ssize_t l = 0;
4412 
4413 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4414 	return l;
4415 }
4416 
4417 static ssize_t
4418 default_blksize_show(struct device *dev, struct device_attribute *attr,
4419 		     char *buf)
4420 {
4421 	struct st_modedef *STm = dev_get_drvdata(dev);
4422 	ssize_t l = 0;
4423 
4424 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4425 	return l;
4426 }
4427 
4428 
4429 static ssize_t
4430 default_density_show(struct device *dev, struct device_attribute *attr,
4431 		     char *buf)
4432 {
4433 	struct st_modedef *STm = dev_get_drvdata(dev);
4434 	ssize_t l = 0;
4435 	char *fmt;
4436 
4437 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4438 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4439 	return l;
4440 }
4441 
4442 static ssize_t
4443 default_compression_show(struct device *dev, struct device_attribute *attr,
4444 			 char *buf)
4445 {
4446 	struct st_modedef *STm = dev_get_drvdata(dev);
4447 	ssize_t l = 0;
4448 
4449 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4450 	return l;
4451 }
4452 
4453 static ssize_t
4454 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4455 {
4456 	struct st_modedef *STm = dev_get_drvdata(dev);
4457 	struct scsi_tape *STp = STm->tape;
4458 	int options;
4459 	ssize_t l = 0;
4460 
4461 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4462 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4463 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4464 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4465 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4466 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4467 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4468 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4469 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4470 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4471 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4472 	options |= STm->sysv ? MT_ST_SYSV : 0;
4473 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4474 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4475 	options |= STp->sili ? MT_ST_SILI : 0;
4476 
4477 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4478 	return l;
4479 }
4480 
4481 static struct device_attribute st_dev_attrs[] = {
4482 	__ATTR_RO(defined),
4483 	__ATTR_RO(default_blksize),
4484 	__ATTR_RO(default_density),
4485 	__ATTR_RO(default_compression),
4486 	__ATTR_RO(options),
4487 	__ATTR_NULL,
4488 };
4489 
4490 /* The following functions may be useful for a larger audience. */
4491 static int sgl_map_user_pages(struct st_buffer *STbp,
4492 			      const unsigned int max_pages, unsigned long uaddr,
4493 			      size_t count, int rw)
4494 {
4495 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4496 	unsigned long start = uaddr >> PAGE_SHIFT;
4497 	const int nr_pages = end - start;
4498 	int res, i, j;
4499 	struct page **pages;
4500 	struct rq_map_data *mdata = &STbp->map_data;
4501 
4502 	/* User attempted Overflow! */
4503 	if ((uaddr + count) < uaddr)
4504 		return -EINVAL;
4505 
4506 	/* Too big */
4507         if (nr_pages > max_pages)
4508 		return -ENOMEM;
4509 
4510 	/* Hmm? */
4511 	if (count == 0)
4512 		return 0;
4513 
4514 	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
4515 		return -ENOMEM;
4516 
4517         /* Try to fault in all of the necessary pages */
4518 	down_read(&current->mm->mmap_sem);
4519         /* rw==READ means read from drive, write into memory area */
4520 	res = get_user_pages(
4521 		current,
4522 		current->mm,
4523 		uaddr,
4524 		nr_pages,
4525 		rw == READ,
4526 		0, /* don't force */
4527 		pages,
4528 		NULL);
4529 	up_read(&current->mm->mmap_sem);
4530 
4531 	/* Errors and no page mapped should return here */
4532 	if (res < nr_pages)
4533 		goto out_unmap;
4534 
4535         for (i=0; i < nr_pages; i++) {
4536                 /* FIXME: flush superflous for rw==READ,
4537                  * probably wrong function for rw==WRITE
4538                  */
4539 		flush_dcache_page(pages[i]);
4540         }
4541 
4542 	mdata->offset = uaddr & ~PAGE_MASK;
4543 	STbp->mapped_pages = pages;
4544 
4545 	return nr_pages;
4546  out_unmap:
4547 	if (res > 0) {
4548 		for (j=0; j < res; j++)
4549 			page_cache_release(pages[j]);
4550 		res = 0;
4551 	}
4552 	kfree(pages);
4553 	return res;
4554 }
4555 
4556 
4557 /* And unmap them... */
4558 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4559 				const unsigned int nr_pages, int dirtied)
4560 {
4561 	int i;
4562 
4563 	for (i=0; i < nr_pages; i++) {
4564 		struct page *page = STbp->mapped_pages[i];
4565 
4566 		if (dirtied)
4567 			SetPageDirty(page);
4568 		/* FIXME: cache flush missing for rw==READ
4569 		 * FIXME: call the correct reference counting function
4570 		 */
4571 		page_cache_release(page);
4572 	}
4573 	kfree(STbp->mapped_pages);
4574 	STbp->mapped_pages = NULL;
4575 
4576 	return 0;
4577 }
4578