xref: /linux/drivers/scsi/st.c (revision 273b281fa22c293963ee3e6eec418f5dda2dbc83)
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 - 2008 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 = "20081215";
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/errno.h>
31 #include <linux/mtio.h>
32 #include <linux/cdrom.h>
33 #include <linux/ioctl.h>
34 #include <linux/fcntl.h>
35 #include <linux/spinlock.h>
36 #include <linux/blkdev.h>
37 #include <linux/moduleparam.h>
38 #include <linux/cdev.h>
39 #include <linux/delay.h>
40 #include <linux/mutex.h>
41 #include <linux/smp_lock.h>
42 
43 #include <asm/uaccess.h>
44 #include <asm/dma.h>
45 #include <asm/system.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 int st_dev_max;
85 static int st_nr_dev;
86 
87 static struct class *st_sysfs_class;
88 
89 MODULE_AUTHOR("Kai Makisara");
90 MODULE_DESCRIPTION("SCSI tape (st) driver");
91 MODULE_LICENSE("GPL");
92 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
93 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
94 
95 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
96  * of sysfs parameters (which module_param doesn't yet support).
97  * Sysfs parameters defined explicitly later.
98  */
99 module_param_named(buffer_kbs, buffer_kbs, int, 0);
100 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
101 module_param_named(max_sg_segs, max_sg_segs, int, 0);
102 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
103 module_param_named(try_direct_io, try_direct_io, int, 0);
104 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
105 
106 /* Extra parameters for testing */
107 module_param_named(try_rdio, try_rdio, int, 0);
108 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
109 module_param_named(try_wdio, try_wdio, int, 0);
110 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
111 
112 #ifndef MODULE
113 static int write_threshold_kbs;  /* retained for compatibility */
114 static struct st_dev_parm {
115 	char *name;
116 	int *val;
117 } parms[] __initdata = {
118 	{
119 		"buffer_kbs", &buffer_kbs
120 	},
121 	{       /* Retained for compatibility with 2.4 */
122 		"write_threshold_kbs", &write_threshold_kbs
123 	},
124 	{
125 		"max_sg_segs", NULL
126 	},
127 	{
128 		"try_direct_io", &try_direct_io
129 	}
130 };
131 #endif
132 
133 /* Restrict the number of modes so that names for all are assigned */
134 #if ST_NBR_MODES > 16
135 #error "Maximum number of modes is 16"
136 #endif
137 /* Bit reversed order to get same names for same minors with all
138    mode counts */
139 static const char *st_formats[] = {
140 	"",  "r", "k", "s", "l", "t", "o", "u",
141 	"m", "v", "p", "x", "a", "y", "q", "z"};
142 
143 /* The default definitions have been moved to st_options.h */
144 
145 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
146 
147 /* The buffer size should fit into the 24 bits for length in the
148    6-byte SCSI read and write commands. */
149 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
150 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
151 #endif
152 
153 static int debugging = DEBUG;
154 
155 #define MAX_RETRIES 0
156 #define MAX_WRITE_RETRIES 0
157 #define MAX_READY_RETRIES 0
158 #define NO_TAPE  NOT_READY
159 
160 #define ST_TIMEOUT (900 * HZ)
161 #define ST_LONG_TIMEOUT (14000 * HZ)
162 
163 /* Remove mode bits and auto-rewind bit (7) */
164 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
165     (iminor(x) & ~(-1 << ST_MODE_SHIFT)) )
166 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
167 
168 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
169 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
170   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
171 
172 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
173    24 bits) */
174 #define SET_DENS_AND_BLK 0x10001
175 
176 static DEFINE_RWLOCK(st_dev_arr_lock);
177 
178 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
179 static int st_max_sg_segs = ST_MAX_SG;
180 
181 static struct scsi_tape **scsi_tapes = NULL;
182 
183 static int modes_defined;
184 
185 static int enlarge_buffer(struct st_buffer *, int, int);
186 static void clear_buffer(struct st_buffer *);
187 static void normalize_buffer(struct st_buffer *);
188 static int append_to_buffer(const char __user *, struct st_buffer *, int);
189 static int from_buffer(struct st_buffer *, char __user *, int);
190 static void move_buffer_data(struct st_buffer *, int);
191 
192 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
193 			      unsigned long, size_t, int);
194 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
195 
196 static int st_probe(struct device *);
197 static int st_remove(struct device *);
198 
199 static int do_create_sysfs_files(void);
200 static void do_remove_sysfs_files(void);
201 static int do_create_class_files(struct scsi_tape *, int, int);
202 
203 static struct scsi_driver st_template = {
204 	.owner			= THIS_MODULE,
205 	.gendrv = {
206 		.name		= "st",
207 		.probe		= st_probe,
208 		.remove		= st_remove,
209 	},
210 };
211 
212 static int st_compression(struct scsi_tape *, int);
213 
214 static int find_partition(struct scsi_tape *);
215 static int switch_partition(struct scsi_tape *);
216 
217 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
218 
219 static void scsi_tape_release(struct kref *);
220 
221 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
222 
223 static DEFINE_MUTEX(st_ref_mutex);
224 
225 
226 #include "osst_detect.h"
227 #ifndef SIGS_FROM_OSST
228 #define SIGS_FROM_OSST \
229 	{"OnStream", "SC-", "", "osst"}, \
230 	{"OnStream", "DI-", "", "osst"}, \
231 	{"OnStream", "DP-", "", "osst"}, \
232 	{"OnStream", "USB", "", "osst"}, \
233 	{"OnStream", "FW-", "", "osst"}
234 #endif
235 
236 static struct scsi_tape *scsi_tape_get(int dev)
237 {
238 	struct scsi_tape *STp = NULL;
239 
240 	mutex_lock(&st_ref_mutex);
241 	write_lock(&st_dev_arr_lock);
242 
243 	if (dev < st_dev_max && scsi_tapes != NULL)
244 		STp = scsi_tapes[dev];
245 	if (!STp) goto out;
246 
247 	kref_get(&STp->kref);
248 
249 	if (!STp->device)
250 		goto out_put;
251 
252 	if (scsi_device_get(STp->device))
253 		goto out_put;
254 
255 	goto out;
256 
257 out_put:
258 	kref_put(&STp->kref, scsi_tape_release);
259 	STp = NULL;
260 out:
261 	write_unlock(&st_dev_arr_lock);
262 	mutex_unlock(&st_ref_mutex);
263 	return STp;
264 }
265 
266 static void scsi_tape_put(struct scsi_tape *STp)
267 {
268 	struct scsi_device *sdev = STp->device;
269 
270 	mutex_lock(&st_ref_mutex);
271 	kref_put(&STp->kref, scsi_tape_release);
272 	scsi_device_put(sdev);
273 	mutex_unlock(&st_ref_mutex);
274 }
275 
276 struct st_reject_data {
277 	char *vendor;
278 	char *model;
279 	char *rev;
280 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
281 };
282 
283 static struct st_reject_data reject_list[] = {
284 	/* {"XXX", "Yy-", "", NULL},  example */
285 	SIGS_FROM_OSST,
286 	{NULL, }};
287 
288 /* If the device signature is on the list of incompatible drives, the
289    function returns a pointer to the name of the correct driver (if known) */
290 static char * st_incompatible(struct scsi_device* SDp)
291 {
292 	struct st_reject_data *rp;
293 
294 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
295 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
296 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
297 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
298 			if (rp->driver_hint)
299 				return rp->driver_hint;
300 			else
301 				return "unknown";
302 		}
303 	return NULL;
304 }
305 
306 
307 static inline char *tape_name(struct scsi_tape *tape)
308 {
309 	return tape->disk->disk_name;
310 }
311 
312 
313 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
314 {
315 	const u8 *ucp;
316 	const u8 *sense = SRpnt->sense;
317 
318 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
319 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
320 	s->flags = 0;
321 
322 	if (s->have_sense) {
323 		s->deferred = 0;
324 		s->remainder_valid =
325 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
326 		switch (sense[0] & 0x7f) {
327 		case 0x71:
328 			s->deferred = 1;
329 		case 0x70:
330 			s->fixed_format = 1;
331 			s->flags = sense[2] & 0xe0;
332 			break;
333 		case 0x73:
334 			s->deferred = 1;
335 		case 0x72:
336 			s->fixed_format = 0;
337 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
338 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
339 			break;
340 		}
341 	}
342 }
343 
344 
345 /* Convert the result to success code */
346 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
347 {
348 	int result = SRpnt->result;
349 	u8 scode;
350 	DEB(const char *stp;)
351 	char *name = tape_name(STp);
352 	struct st_cmdstatus *cmdstatp;
353 
354 	if (!result)
355 		return 0;
356 
357 	cmdstatp = &STp->buffer->cmdstat;
358 	st_analyze_sense(SRpnt, cmdstatp);
359 
360 	if (cmdstatp->have_sense)
361 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
362 	else
363 		scode = 0;
364 
365         DEB(
366         if (debugging) {
367                 printk(ST_DEB_MSG "%s: Error: %x, cmd: %x %x %x %x %x %x\n",
368 		       name, result,
369 		       SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
370 		       SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
371 		if (cmdstatp->have_sense)
372 			 __scsi_print_sense(name, SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
373 	} ) /* end DEB */
374 	if (!debugging) { /* Abnormal conditions for tape */
375 		if (!cmdstatp->have_sense)
376 			printk(KERN_WARNING
377 			       "%s: Error %x (driver bt 0x%x, host bt 0x%x).\n",
378 			       name, result, driver_byte(result),
379 			       host_byte(result));
380 		else if (cmdstatp->have_sense &&
381 			 scode != NO_SENSE &&
382 			 scode != RECOVERED_ERROR &&
383 			 /* scode != UNIT_ATTENTION && */
384 			 scode != BLANK_CHECK &&
385 			 scode != VOLUME_OVERFLOW &&
386 			 SRpnt->cmd[0] != MODE_SENSE &&
387 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
388 
389 			__scsi_print_sense(name, SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
390 		}
391 	}
392 
393 	if (cmdstatp->fixed_format &&
394 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
395 		if (STp->cln_sense_value)
396 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
397 					       STp->cln_sense_mask) == STp->cln_sense_value);
398 		else
399 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
400 					       STp->cln_sense_mask) != 0);
401 	}
402 	if (cmdstatp->have_sense &&
403 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
404 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
405 
406 	STp->pos_unknown |= STp->device->was_reset;
407 
408 	if (cmdstatp->have_sense &&
409 	    scode == RECOVERED_ERROR
410 #if ST_RECOVERED_WRITE_FATAL
411 	    && SRpnt->cmd[0] != WRITE_6
412 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
413 #endif
414 	    ) {
415 		STp->recover_count++;
416 		STp->recover_reg++;
417 
418                 DEB(
419 		if (debugging) {
420 			if (SRpnt->cmd[0] == READ_6)
421 				stp = "read";
422 			else if (SRpnt->cmd[0] == WRITE_6)
423 				stp = "write";
424 			else
425 				stp = "ioctl";
426 			printk(ST_DEB_MSG "%s: Recovered %s error (%d).\n", name, stp,
427 			       STp->recover_count);
428 		} ) /* end DEB */
429 
430 		if (cmdstatp->flags == 0)
431 			return 0;
432 	}
433 	return (-EIO);
434 }
435 
436 static struct st_request *st_allocate_request(struct scsi_tape *stp)
437 {
438 	struct st_request *streq;
439 
440 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
441 	if (streq)
442 		streq->stp = stp;
443 	else {
444 		DEBC(printk(KERN_ERR "%s: Can't get SCSI request.\n",
445 			    tape_name(stp)););
446 		if (signal_pending(current))
447 			stp->buffer->syscall_result = -EINTR;
448 		else
449 			stp->buffer->syscall_result = -EBUSY;
450 	}
451 
452 	return streq;
453 }
454 
455 static void st_release_request(struct st_request *streq)
456 {
457 	kfree(streq);
458 }
459 
460 static void st_scsi_execute_end(struct request *req, int uptodate)
461 {
462 	struct st_request *SRpnt = req->end_io_data;
463 	struct scsi_tape *STp = SRpnt->stp;
464 
465 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors;
466 	STp->buffer->cmdstat.residual = req->resid_len;
467 
468 	if (SRpnt->waiting)
469 		complete(SRpnt->waiting);
470 
471 	blk_rq_unmap_user(SRpnt->bio);
472 	__blk_put_request(req->q, req);
473 }
474 
475 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
476 			   int data_direction, void *buffer, unsigned bufflen,
477 			   int timeout, int retries)
478 {
479 	struct request *req;
480 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
481 	int err = 0;
482 	int write = (data_direction == DMA_TO_DEVICE);
483 
484 	req = blk_get_request(SRpnt->stp->device->request_queue, write,
485 			      GFP_KERNEL);
486 	if (!req)
487 		return DRIVER_ERROR << 24;
488 
489 	req->cmd_type = REQ_TYPE_BLOCK_PC;
490 	req->cmd_flags |= REQ_QUIET;
491 
492 	mdata->null_mapped = 1;
493 
494 	if (bufflen) {
495 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
496 				      GFP_KERNEL);
497 		if (err) {
498 			blk_put_request(req);
499 			return DRIVER_ERROR << 24;
500 		}
501 	}
502 
503 	SRpnt->bio = req->bio;
504 	req->cmd_len = COMMAND_SIZE(cmd[0]);
505 	memset(req->cmd, 0, BLK_MAX_CDB);
506 	memcpy(req->cmd, cmd, req->cmd_len);
507 	req->sense = SRpnt->sense;
508 	req->sense_len = 0;
509 	req->timeout = timeout;
510 	req->retries = retries;
511 	req->end_io_data = SRpnt;
512 
513 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
514 	return 0;
515 }
516 
517 /* Do the scsi command. Waits until command performed if do_wait is true.
518    Otherwise write_behind_check() is used to check that the command
519    has finished. */
520 static struct st_request *
521 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
522 	   int bytes, int direction, int timeout, int retries, int do_wait)
523 {
524 	struct completion *waiting;
525 	struct rq_map_data *mdata = &STp->buffer->map_data;
526 	int ret;
527 
528 	/* if async, make sure there's no command outstanding */
529 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
530 		printk(KERN_ERR "%s: Async command already active.\n",
531 		       tape_name(STp));
532 		if (signal_pending(current))
533 			(STp->buffer)->syscall_result = (-EINTR);
534 		else
535 			(STp->buffer)->syscall_result = (-EBUSY);
536 		return NULL;
537 	}
538 
539 	if (!SRpnt) {
540 		SRpnt = st_allocate_request(STp);
541 		if (!SRpnt)
542 			return NULL;
543 	}
544 
545 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
546 	   which IO is outstanding. It's nulled out when the IO completes. */
547 	if (!do_wait)
548 		(STp->buffer)->last_SRpnt = SRpnt;
549 
550 	waiting = &STp->wait;
551 	init_completion(waiting);
552 	SRpnt->waiting = waiting;
553 
554 	if (STp->buffer->do_dio) {
555 		mdata->nr_entries = STp->buffer->sg_segs;
556 		mdata->pages = STp->buffer->mapped_pages;
557 	} else {
558 		mdata->nr_entries =
559 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
560 		STp->buffer->map_data.pages = STp->buffer->reserved_pages;
561 		STp->buffer->map_data.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 	}
1105 	st_release_request(SRpnt);
1106 	SRpnt = NULL;
1107         STp->inited = 1;
1108 
1109 	if (STp->block_size > 0)
1110 		(STp->buffer)->buffer_blocks =
1111                         (STp->buffer)->buffer_size / STp->block_size;
1112 	else
1113 		(STp->buffer)->buffer_blocks = 1;
1114 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1115 
1116         DEBC(printk(ST_DEB_MSG
1117                        "%s: Block size: %d, buffer size: %d (%d blocks).\n", name,
1118 		       STp->block_size, (STp->buffer)->buffer_size,
1119 		       (STp->buffer)->buffer_blocks));
1120 
1121 	if (STp->drv_write_prot) {
1122 		STp->write_prot = 1;
1123 
1124                 DEBC(printk(ST_DEB_MSG "%s: Write protected\n", name));
1125 
1126 		if (do_wait &&
1127 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1128 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1129 			retval = (-EROFS);
1130 			goto err_out;
1131 		}
1132 	}
1133 
1134 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1135 		/* This code is reached when the device is opened for the first time
1136 		   after the driver has been initialized with tape in the drive and the
1137 		   partition support has been enabled. */
1138                 DEBC(printk(ST_DEB_MSG
1139                             "%s: Updating partition number in status.\n", name));
1140 		if ((STp->partition = find_partition(STp)) < 0) {
1141 			retval = STp->partition;
1142 			goto err_out;
1143 		}
1144 		STp->new_partition = STp->partition;
1145 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1146 	}
1147 
1148 	if (new_session) {	/* Change the drive parameters for the new mode */
1149 		STp->density_changed = STp->blksize_changed = 0;
1150 		STp->compression_changed = 0;
1151 		if (!(STm->defaults_for_writes) &&
1152 		    (retval = set_mode_densblk(STp, STm)) < 0)
1153 		    goto err_out;
1154 
1155 		if (STp->default_drvbuffer != 0xff) {
1156 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1157 				printk(KERN_WARNING
1158                                        "%s: Can't set default drive buffering to %d.\n",
1159 				       name, STp->default_drvbuffer);
1160 		}
1161 	}
1162 
1163 	return CHKRES_READY;
1164 
1165  err_out:
1166 	return retval;
1167 }
1168 
1169 
1170 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1171    module count. */
1172 static int st_open(struct inode *inode, struct file *filp)
1173 {
1174 	int i, retval = (-EIO);
1175 	struct scsi_tape *STp;
1176 	struct st_partstat *STps;
1177 	int dev = TAPE_NR(inode);
1178 	char *name;
1179 
1180 	lock_kernel();
1181 	/*
1182 	 * We really want to do nonseekable_open(inode, filp); here, but some
1183 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1184 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1185 	 */
1186 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1187 
1188 	if (!(STp = scsi_tape_get(dev))) {
1189 		unlock_kernel();
1190 		return -ENXIO;
1191 	}
1192 
1193 	write_lock(&st_dev_arr_lock);
1194 	filp->private_data = STp;
1195 	name = tape_name(STp);
1196 
1197 	if (STp->in_use) {
1198 		write_unlock(&st_dev_arr_lock);
1199 		scsi_tape_put(STp);
1200 		unlock_kernel();
1201 		DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
1202 		return (-EBUSY);
1203 	}
1204 
1205 	STp->in_use = 1;
1206 	write_unlock(&st_dev_arr_lock);
1207 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1208 
1209 	if (!scsi_block_when_processing_errors(STp->device)) {
1210 		retval = (-ENXIO);
1211 		goto err_out;
1212 	}
1213 
1214 	/* See that we have at least a one page buffer available */
1215 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
1216 		printk(KERN_WARNING "%s: Can't allocate one page tape buffer.\n",
1217 		       name);
1218 		retval = (-EOVERFLOW);
1219 		goto err_out;
1220 	}
1221 
1222 	(STp->buffer)->cleared = 0;
1223 	(STp->buffer)->writing = 0;
1224 	(STp->buffer)->syscall_result = 0;
1225 
1226 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1227 
1228 	STp->dirty = 0;
1229 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1230 		STps = &(STp->ps[i]);
1231 		STps->rw = ST_IDLE;
1232 	}
1233 	STp->try_dio_now = STp->try_dio;
1234 	STp->recover_count = 0;
1235 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1236 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1237 
1238 	retval = check_tape(STp, filp);
1239 	if (retval < 0)
1240 		goto err_out;
1241 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1242 	    retval != CHKRES_READY) {
1243 		if (STp->ready == NO_TAPE)
1244 			retval = (-ENOMEDIUM);
1245 		else
1246 			retval = (-EIO);
1247 		goto err_out;
1248 	}
1249 	unlock_kernel();
1250 	return 0;
1251 
1252  err_out:
1253 	normalize_buffer(STp->buffer);
1254 	STp->in_use = 0;
1255 	scsi_tape_put(STp);
1256 	unlock_kernel();
1257 	return retval;
1258 
1259 }
1260 
1261 
1262 /* Flush the tape buffer before close */
1263 static int st_flush(struct file *filp, fl_owner_t id)
1264 {
1265 	int result = 0, result2;
1266 	unsigned char cmd[MAX_COMMAND_SIZE];
1267 	struct st_request *SRpnt;
1268 	struct scsi_tape *STp = filp->private_data;
1269 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1270 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1271 	char *name = tape_name(STp);
1272 
1273 	if (file_count(filp) > 1)
1274 		return 0;
1275 
1276 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1277 		result = st_flush_write_buffer(STp);
1278 		if (result != 0 && result != (-ENOSPC))
1279 			goto out;
1280 	}
1281 
1282 	if (STp->can_partitions &&
1283 	    (result2 = switch_partition(STp)) < 0) {
1284                 DEBC(printk(ST_DEB_MSG
1285                                "%s: switch_partition at close failed.\n", name));
1286 		if (result == 0)
1287 			result = result2;
1288 		goto out;
1289 	}
1290 
1291 	DEBC( if (STp->nbr_requests)
1292 		printk(KERN_DEBUG "%s: Number of r/w requests %d, dio used in %d, pages %d.\n",
1293 		       name, STp->nbr_requests, STp->nbr_dio, STp->nbr_pages));
1294 
1295 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1296 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1297 
1298                 DEBC(printk(ST_DEB_MSG "%s: Async write waits %d, finished %d.\n",
1299                             name, STp->nbr_waits, STp->nbr_finished);
1300 		)
1301 
1302 		memset(cmd, 0, MAX_COMMAND_SIZE);
1303 		cmd[0] = WRITE_FILEMARKS;
1304 		cmd[4] = 1 + STp->two_fm;
1305 
1306 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1307 				   STp->device->request_queue->rq_timeout,
1308 				   MAX_WRITE_RETRIES, 1);
1309 		if (!SRpnt) {
1310 			result = (STp->buffer)->syscall_result;
1311 			goto out;
1312 		}
1313 
1314 		if (STp->buffer->syscall_result == 0 ||
1315 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1316 		     (cmdstatp->flags & SENSE_EOM) &&
1317 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1318 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1319 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1320 			/* Write successful at EOM */
1321 			st_release_request(SRpnt);
1322 			SRpnt = NULL;
1323 			if (STps->drv_file >= 0)
1324 				STps->drv_file++;
1325 			STps->drv_block = 0;
1326 			if (STp->two_fm)
1327 				cross_eof(STp, 0);
1328 			STps->eof = ST_FM;
1329 		}
1330 		else { /* Write error */
1331 			st_release_request(SRpnt);
1332 			SRpnt = NULL;
1333 			printk(KERN_ERR "%s: Error on write filemark.\n", name);
1334 			if (result == 0)
1335 				result = (-EIO);
1336 		}
1337 
1338                 DEBC(printk(ST_DEB_MSG "%s: Buffer flushed, %d EOF(s) written\n",
1339                             name, cmd[4]));
1340 	} else if (!STp->rew_at_close) {
1341 		STps = &(STp->ps[STp->partition]);
1342 		if (!STm->sysv || STps->rw != ST_READING) {
1343 			if (STp->can_bsr)
1344 				result = flush_buffer(STp, 0);
1345 			else if (STps->eof == ST_FM_HIT) {
1346 				result = cross_eof(STp, 0);
1347 				if (result) {
1348 					if (STps->drv_file >= 0)
1349 						STps->drv_file++;
1350 					STps->drv_block = 0;
1351 					STps->eof = ST_FM;
1352 				} else
1353 					STps->eof = ST_NOEOF;
1354 			}
1355 		} else if ((STps->eof == ST_NOEOF &&
1356 			    !(result = cross_eof(STp, 1))) ||
1357 			   STps->eof == ST_FM_HIT) {
1358 			if (STps->drv_file >= 0)
1359 				STps->drv_file++;
1360 			STps->drv_block = 0;
1361 			STps->eof = ST_FM;
1362 		}
1363 	}
1364 
1365       out:
1366 	if (STp->rew_at_close) {
1367 		result2 = st_int_ioctl(STp, MTREW, 1);
1368 		if (result == 0)
1369 			result = result2;
1370 	}
1371 	return result;
1372 }
1373 
1374 
1375 /* Close the device and release it. BKL is not needed: this is the only thread
1376    accessing this tape. */
1377 static int st_release(struct inode *inode, struct file *filp)
1378 {
1379 	int result = 0;
1380 	struct scsi_tape *STp = filp->private_data;
1381 
1382 	if (STp->door_locked == ST_LOCKED_AUTO)
1383 		do_door_lock(STp, 0);
1384 
1385 	normalize_buffer(STp->buffer);
1386 	write_lock(&st_dev_arr_lock);
1387 	STp->in_use = 0;
1388 	write_unlock(&st_dev_arr_lock);
1389 	scsi_tape_put(STp);
1390 
1391 	return result;
1392 }
1393 
1394 /* The checks common to both reading and writing */
1395 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1396 {
1397 	ssize_t retval = 0;
1398 
1399 	/*
1400 	 * If we are in the middle of error recovery, don't let anyone
1401 	 * else try and use this device.  Also, if error recovery fails, it
1402 	 * may try and take the device offline, in which case all further
1403 	 * access to the device is prohibited.
1404 	 */
1405 	if (!scsi_block_when_processing_errors(STp->device)) {
1406 		retval = (-ENXIO);
1407 		goto out;
1408 	}
1409 
1410 	if (STp->ready != ST_READY) {
1411 		if (STp->ready == ST_NO_TAPE)
1412 			retval = (-ENOMEDIUM);
1413 		else
1414 			retval = (-EIO);
1415 		goto out;
1416 	}
1417 
1418 	if (! STp->modes[STp->current_mode].defined) {
1419 		retval = (-ENXIO);
1420 		goto out;
1421 	}
1422 
1423 
1424 	/*
1425 	 * If there was a bus reset, block further access
1426 	 * to this device.
1427 	 */
1428 	if (STp->pos_unknown) {
1429 		retval = (-EIO);
1430 		goto out;
1431 	}
1432 
1433 	if (count == 0)
1434 		goto out;
1435 
1436         DEB(
1437 	if (!STp->in_use) {
1438 		printk(ST_DEB_MSG "%s: Incorrect device.\n", tape_name(STp));
1439 		retval = (-EIO);
1440 		goto out;
1441 	} ) /* end DEB */
1442 
1443 	if (STp->can_partitions &&
1444 	    (retval = switch_partition(STp)) < 0)
1445 		goto out;
1446 
1447 	if (STp->block_size == 0 && STp->max_block > 0 &&
1448 	    (count < STp->min_block || count > STp->max_block)) {
1449 		retval = (-EINVAL);
1450 		goto out;
1451 	}
1452 
1453 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1454 	    !do_door_lock(STp, 1))
1455 		STp->door_locked = ST_LOCKED_AUTO;
1456 
1457  out:
1458 	return retval;
1459 }
1460 
1461 
1462 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1463 			   size_t count, int is_read)
1464 {
1465 	int i, bufsize, retval = 0;
1466 	struct st_buffer *STbp = STp->buffer;
1467 
1468 	if (is_read)
1469 		i = STp->try_dio_now && try_rdio;
1470 	else
1471 		i = STp->try_dio_now && try_wdio;
1472 
1473 	if (i && ((unsigned long)buf & queue_dma_alignment(
1474 					STp->device->request_queue)) == 0) {
1475 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1476 				       count, (is_read ? READ : WRITE));
1477 		if (i > 0) {
1478 			STbp->do_dio = i;
1479 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1480 		}
1481 		else
1482 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1483 		STbp->sg_segs = STbp->do_dio;
1484 		DEB(
1485 		     if (STbp->do_dio) {
1486 			STp->nbr_dio++;
1487 			STp->nbr_pages += STbp->do_dio;
1488 		     }
1489 		)
1490 	} else
1491 		STbp->do_dio = 0;
1492 	DEB( STp->nbr_requests++; )
1493 
1494 	if (!STbp->do_dio) {
1495 		if (STp->block_size)
1496 			bufsize = STp->block_size > st_fixed_buffer_size ?
1497 				STp->block_size : st_fixed_buffer_size;
1498 		else {
1499 			bufsize = count;
1500 			/* Make sure that data from previous user is not leaked even if
1501 			   HBA does not return correct residual */
1502 			if (is_read && STp->sili && !STbp->cleared)
1503 				clear_buffer(STbp);
1504 		}
1505 
1506 		if (bufsize > STbp->buffer_size &&
1507 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1508 			printk(KERN_WARNING "%s: Can't allocate %d byte tape buffer.\n",
1509 			       tape_name(STp), bufsize);
1510 			retval = (-EOVERFLOW);
1511 			goto out;
1512 		}
1513 		if (STp->block_size)
1514 			STbp->buffer_blocks = bufsize / STp->block_size;
1515 	}
1516 
1517  out:
1518 	return retval;
1519 }
1520 
1521 
1522 /* Can be called more than once after each setup_buffer() */
1523 static void release_buffering(struct scsi_tape *STp, int is_read)
1524 {
1525 	struct st_buffer *STbp;
1526 
1527 	STbp = STp->buffer;
1528 	if (STbp->do_dio) {
1529 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1530 		STbp->do_dio = 0;
1531 		STbp->sg_segs = 0;
1532 	}
1533 }
1534 
1535 
1536 /* Write command */
1537 static ssize_t
1538 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1539 {
1540 	ssize_t total;
1541 	ssize_t i, do_count, blks, transfer;
1542 	ssize_t retval;
1543 	int undone, retry_eot = 0, scode;
1544 	int async_write;
1545 	unsigned char cmd[MAX_COMMAND_SIZE];
1546 	const char __user *b_point;
1547 	struct st_request *SRpnt = NULL;
1548 	struct scsi_tape *STp = filp->private_data;
1549 	struct st_modedef *STm;
1550 	struct st_partstat *STps;
1551 	struct st_buffer *STbp;
1552 	char *name = tape_name(STp);
1553 
1554 	if (mutex_lock_interruptible(&STp->lock))
1555 		return -ERESTARTSYS;
1556 
1557 	retval = rw_checks(STp, filp, count);
1558 	if (retval || count == 0)
1559 		goto out;
1560 
1561 	/* Write must be integral number of blocks */
1562 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1563 		printk(KERN_WARNING "%s: Write not multiple of tape block size.\n",
1564 		       name);
1565 		retval = (-EINVAL);
1566 		goto out;
1567 	}
1568 
1569 	STm = &(STp->modes[STp->current_mode]);
1570 	STps = &(STp->ps[STp->partition]);
1571 
1572 	if (STp->write_prot) {
1573 		retval = (-EACCES);
1574 		goto out;
1575 	}
1576 
1577 
1578 	if (STps->rw == ST_READING) {
1579 		retval = flush_buffer(STp, 0);
1580 		if (retval)
1581 			goto out;
1582 		STps->rw = ST_WRITING;
1583 	} else if (STps->rw != ST_WRITING &&
1584 		   STps->drv_file == 0 && STps->drv_block == 0) {
1585 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1586 			goto out;
1587 		if (STm->default_compression != ST_DONT_TOUCH &&
1588 		    !(STp->compression_changed)) {
1589 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1590 				printk(KERN_WARNING "%s: Can't set default compression.\n",
1591 				       name);
1592 				if (modes_defined) {
1593 					retval = (-EINVAL);
1594 					goto out;
1595 				}
1596 			}
1597 		}
1598 	}
1599 
1600 	STbp = STp->buffer;
1601 	i = write_behind_check(STp);
1602 	if (i) {
1603 		if (i == -ENOSPC)
1604 			STps->eof = ST_EOM_OK;
1605 		else
1606 			STps->eof = ST_EOM_ERROR;
1607 	}
1608 
1609 	if (STps->eof == ST_EOM_OK) {
1610 		STps->eof = ST_EOD_1;  /* allow next write */
1611 		retval = (-ENOSPC);
1612 		goto out;
1613 	}
1614 	else if (STps->eof == ST_EOM_ERROR) {
1615 		retval = (-EIO);
1616 		goto out;
1617 	}
1618 
1619 	/* Check the buffer readability in cases where copy_user might catch
1620 	   the problems after some tape movement. */
1621 	if (STp->block_size != 0 &&
1622 	    !STbp->do_dio &&
1623 	    (copy_from_user(&i, buf, 1) != 0 ||
1624 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1625 		retval = (-EFAULT);
1626 		goto out;
1627 	}
1628 
1629 	retval = setup_buffering(STp, buf, count, 0);
1630 	if (retval)
1631 		goto out;
1632 
1633 	total = count;
1634 
1635 	memset(cmd, 0, MAX_COMMAND_SIZE);
1636 	cmd[0] = WRITE_6;
1637 	cmd[1] = (STp->block_size != 0);
1638 
1639 	STps->rw = ST_WRITING;
1640 
1641 	b_point = buf;
1642 	while (count > 0 && !retry_eot) {
1643 
1644 		if (STbp->do_dio) {
1645 			do_count = count;
1646 		}
1647 		else {
1648 			if (STp->block_size == 0)
1649 				do_count = count;
1650 			else {
1651 				do_count = STbp->buffer_blocks * STp->block_size -
1652 					STbp->buffer_bytes;
1653 				if (do_count > count)
1654 					do_count = count;
1655 			}
1656 
1657 			i = append_to_buffer(b_point, STbp, do_count);
1658 			if (i) {
1659 				retval = i;
1660 				goto out;
1661 			}
1662 		}
1663 		count -= do_count;
1664 		b_point += do_count;
1665 
1666 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1667 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1668 
1669 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1670 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1671 		    STbp->buffer_bytes < STbp->buffer_size) {
1672 			STp->dirty = 1;
1673 			/* Don't write a buffer that is not full enough. */
1674 			if (!async_write && count == 0)
1675 				break;
1676 		}
1677 
1678 	retry_write:
1679 		if (STp->block_size == 0)
1680 			blks = transfer = do_count;
1681 		else {
1682 			if (!STbp->do_dio)
1683 				blks = STbp->buffer_bytes;
1684 			else
1685 				blks = do_count;
1686 			blks /= STp->block_size;
1687 			transfer = blks * STp->block_size;
1688 		}
1689 		cmd[2] = blks >> 16;
1690 		cmd[3] = blks >> 8;
1691 		cmd[4] = blks;
1692 
1693 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1694 				   STp->device->request_queue->rq_timeout,
1695 				   MAX_WRITE_RETRIES, !async_write);
1696 		if (!SRpnt) {
1697 			retval = STbp->syscall_result;
1698 			goto out;
1699 		}
1700 		if (async_write && !STbp->syscall_result) {
1701 			STbp->writing = transfer;
1702 			STp->dirty = !(STbp->writing ==
1703 				       STbp->buffer_bytes);
1704 			SRpnt = NULL;  /* Prevent releasing this request! */
1705 			DEB( STp->write_pending = 1; )
1706 			break;
1707 		}
1708 
1709 		if (STbp->syscall_result != 0) {
1710 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1711 
1712                         DEBC(printk(ST_DEB_MSG "%s: Error on write:\n", name));
1713 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1714 				scode = cmdstatp->sense_hdr.sense_key;
1715 				if (cmdstatp->remainder_valid)
1716 					undone = (int)cmdstatp->uremainder64;
1717 				else if (STp->block_size == 0 &&
1718 					 scode == VOLUME_OVERFLOW)
1719 					undone = transfer;
1720 				else
1721 					undone = 0;
1722 				if (STp->block_size != 0)
1723 					undone *= STp->block_size;
1724 				if (undone <= do_count) {
1725 					/* Only data from this write is not written */
1726 					count += undone;
1727 					b_point -= undone;
1728 					do_count -= undone;
1729 					if (STp->block_size)
1730 						blks = (transfer - undone) / STp->block_size;
1731 					STps->eof = ST_EOM_OK;
1732 					/* Continue in fixed block mode if all written
1733 					   in this request but still something left to write
1734 					   (retval left to zero)
1735 					*/
1736 					if (STp->block_size == 0 ||
1737 					    undone > 0 || count == 0)
1738 						retval = (-ENOSPC); /* EOM within current request */
1739                                         DEBC(printk(ST_DEB_MSG
1740                                                        "%s: EOM with %d bytes unwritten.\n",
1741 						       name, (int)count));
1742 				} else {
1743 					/* EOT within data buffered earlier (possible only
1744 					   in fixed block mode without direct i/o) */
1745 					if (!retry_eot && !cmdstatp->deferred &&
1746 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1747 						move_buffer_data(STp->buffer, transfer - undone);
1748 						retry_eot = 1;
1749 						if (STps->drv_block >= 0) {
1750 							STps->drv_block += (transfer - undone) /
1751 								STp->block_size;
1752 						}
1753 						STps->eof = ST_EOM_OK;
1754 						DEBC(printk(ST_DEB_MSG
1755 							    "%s: Retry write of %d bytes at EOM.\n",
1756 							    name, STp->buffer->buffer_bytes));
1757 						goto retry_write;
1758 					}
1759 					else {
1760 						/* Either error within data buffered by driver or
1761 						   failed retry */
1762 						count -= do_count;
1763 						blks = do_count = 0;
1764 						STps->eof = ST_EOM_ERROR;
1765 						STps->drv_block = (-1); /* Too cautious? */
1766 						retval = (-EIO);	/* EOM for old data */
1767 						DEBC(printk(ST_DEB_MSG
1768 							    "%s: EOM with lost data.\n",
1769 							    name));
1770 					}
1771 				}
1772 			} else {
1773 				count += do_count;
1774 				STps->drv_block = (-1);		/* Too cautious? */
1775 				retval = STbp->syscall_result;
1776 			}
1777 
1778 		}
1779 
1780 		if (STps->drv_block >= 0) {
1781 			if (STp->block_size == 0)
1782 				STps->drv_block += (do_count > 0);
1783 			else
1784 				STps->drv_block += blks;
1785 		}
1786 
1787 		STbp->buffer_bytes = 0;
1788 		STp->dirty = 0;
1789 
1790 		if (retval || retry_eot) {
1791 			if (count < total)
1792 				retval = total - count;
1793 			goto out;
1794 		}
1795 	}
1796 
1797 	if (STps->eof == ST_EOD_1)
1798 		STps->eof = ST_EOM_OK;
1799 	else if (STps->eof != ST_EOM_OK)
1800 		STps->eof = ST_NOEOF;
1801 	retval = total - count;
1802 
1803  out:
1804 	if (SRpnt != NULL)
1805 		st_release_request(SRpnt);
1806 	release_buffering(STp, 0);
1807 	mutex_unlock(&STp->lock);
1808 
1809 	return retval;
1810 }
1811 
1812 /* Read data from the tape. Returns zero in the normal case, one if the
1813    eof status has changed, and the negative error code in case of a
1814    fatal error. Otherwise updates the buffer and the eof state.
1815 
1816    Does release user buffer mapping if it is set.
1817 */
1818 static long read_tape(struct scsi_tape *STp, long count,
1819 		      struct st_request ** aSRpnt)
1820 {
1821 	int transfer, blks, bytes;
1822 	unsigned char cmd[MAX_COMMAND_SIZE];
1823 	struct st_request *SRpnt;
1824 	struct st_modedef *STm;
1825 	struct st_partstat *STps;
1826 	struct st_buffer *STbp;
1827 	int retval = 0;
1828 	char *name = tape_name(STp);
1829 
1830 	if (count == 0)
1831 		return 0;
1832 
1833 	STm = &(STp->modes[STp->current_mode]);
1834 	STps = &(STp->ps[STp->partition]);
1835 	if (STps->eof == ST_FM_HIT)
1836 		return 1;
1837 	STbp = STp->buffer;
1838 
1839 	if (STp->block_size == 0)
1840 		blks = bytes = count;
1841 	else {
1842 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1843 			blks = (STp->buffer)->buffer_blocks;
1844 			bytes = blks * STp->block_size;
1845 		} else {
1846 			bytes = count;
1847 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1848 				bytes = (STp->buffer)->buffer_size;
1849 			blks = bytes / STp->block_size;
1850 			bytes = blks * STp->block_size;
1851 		}
1852 	}
1853 
1854 	memset(cmd, 0, MAX_COMMAND_SIZE);
1855 	cmd[0] = READ_6;
1856 	cmd[1] = (STp->block_size != 0);
1857 	if (!cmd[1] && STp->sili)
1858 		cmd[1] |= 2;
1859 	cmd[2] = blks >> 16;
1860 	cmd[3] = blks >> 8;
1861 	cmd[4] = blks;
1862 
1863 	SRpnt = *aSRpnt;
1864 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1865 			   STp->device->request_queue->rq_timeout,
1866 			   MAX_RETRIES, 1);
1867 	release_buffering(STp, 1);
1868 	*aSRpnt = SRpnt;
1869 	if (!SRpnt)
1870 		return STbp->syscall_result;
1871 
1872 	STbp->read_pointer = 0;
1873 	STps->at_sm = 0;
1874 
1875 	/* Something to check */
1876 	if (STbp->syscall_result) {
1877 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1878 
1879 		retval = 1;
1880 		DEBC(printk(ST_DEB_MSG "%s: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1881                             name,
1882                             SRpnt->sense[0], SRpnt->sense[1],
1883                             SRpnt->sense[2], SRpnt->sense[3],
1884                             SRpnt->sense[4], SRpnt->sense[5],
1885                             SRpnt->sense[6], SRpnt->sense[7]));
1886 		if (cmdstatp->have_sense) {
1887 
1888 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1889 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1890 
1891 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1892 				/* Compute the residual count */
1893 				if (cmdstatp->remainder_valid)
1894 					transfer = (int)cmdstatp->uremainder64;
1895 				else
1896 					transfer = 0;
1897 				if (STp->block_size == 0 &&
1898 				    cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR)
1899 					transfer = bytes;
1900 
1901 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1902 					if (STp->block_size == 0) {
1903 						if (transfer <= 0) {
1904 							if (transfer < 0)
1905 								printk(KERN_NOTICE
1906 								       "%s: Failed to read %d byte block with %d byte transfer.\n",
1907 								       name, bytes - transfer, bytes);
1908 							if (STps->drv_block >= 0)
1909 								STps->drv_block += 1;
1910 							STbp->buffer_bytes = 0;
1911 							return (-ENOMEM);
1912 						}
1913 						STbp->buffer_bytes = bytes - transfer;
1914 					} else {
1915 						st_release_request(SRpnt);
1916 						SRpnt = *aSRpnt = NULL;
1917 						if (transfer == blks) {	/* We did not get anything, error */
1918 							printk(KERN_NOTICE "%s: Incorrect block size.\n", name);
1919 							if (STps->drv_block >= 0)
1920 								STps->drv_block += blks - transfer + 1;
1921 							st_int_ioctl(STp, MTBSR, 1);
1922 							return (-EIO);
1923 						}
1924 						/* We have some data, deliver it */
1925 						STbp->buffer_bytes = (blks - transfer) *
1926 						    STp->block_size;
1927                                                 DEBC(printk(ST_DEB_MSG
1928                                                             "%s: ILI but enough data received %ld %d.\n",
1929                                                             name, count, STbp->buffer_bytes));
1930 						if (STps->drv_block >= 0)
1931 							STps->drv_block += 1;
1932 						if (st_int_ioctl(STp, MTBSR, 1))
1933 							return (-EIO);
1934 					}
1935 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
1936 					if (STps->eof != ST_FM_HIT)
1937 						STps->eof = ST_FM_HIT;
1938 					else
1939 						STps->eof = ST_EOD_2;
1940 					if (STp->block_size == 0)
1941 						STbp->buffer_bytes = 0;
1942 					else
1943 						STbp->buffer_bytes =
1944 						    bytes - transfer * STp->block_size;
1945                                         DEBC(printk(ST_DEB_MSG
1946                                                     "%s: EOF detected (%d bytes read).\n",
1947                                                     name, STbp->buffer_bytes));
1948 				} else if (cmdstatp->flags & SENSE_EOM) {
1949 					if (STps->eof == ST_FM)
1950 						STps->eof = ST_EOD_1;
1951 					else
1952 						STps->eof = ST_EOM_OK;
1953 					if (STp->block_size == 0)
1954 						STbp->buffer_bytes = bytes - transfer;
1955 					else
1956 						STbp->buffer_bytes =
1957 						    bytes - transfer * STp->block_size;
1958 
1959                                         DEBC(printk(ST_DEB_MSG "%s: EOM detected (%d bytes read).\n",
1960                                                     name, STbp->buffer_bytes));
1961 				}
1962 			}
1963 			/* end of EOF, EOM, ILI test */
1964 			else {	/* nonzero sense key */
1965                                 DEBC(printk(ST_DEB_MSG
1966                                             "%s: Tape error while reading.\n", name));
1967 				STps->drv_block = (-1);
1968 				if (STps->eof == ST_FM &&
1969 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
1970                                         DEBC(printk(ST_DEB_MSG
1971                                                     "%s: Zero returned for first BLANK CHECK after EOF.\n",
1972                                                     name));
1973 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
1974 				} else	/* Some other extended sense code */
1975 					retval = (-EIO);
1976 			}
1977 
1978 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
1979 				STbp->buffer_bytes = 0;
1980 		}
1981 		/* End of extended sense test */
1982 		else {		/* Non-extended sense */
1983 			retval = STbp->syscall_result;
1984 		}
1985 
1986 	}
1987 	/* End of error handling */
1988 	else {			/* Read successful */
1989 		STbp->buffer_bytes = bytes;
1990 		if (STp->sili) /* In fixed block mode residual is always zero here */
1991 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
1992 	}
1993 
1994 	if (STps->drv_block >= 0) {
1995 		if (STp->block_size == 0)
1996 			STps->drv_block++;
1997 		else
1998 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
1999 	}
2000 	return retval;
2001 }
2002 
2003 
2004 /* Read command */
2005 static ssize_t
2006 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2007 {
2008 	ssize_t total;
2009 	ssize_t retval = 0;
2010 	ssize_t i, transfer;
2011 	int special, do_dio = 0;
2012 	struct st_request *SRpnt = NULL;
2013 	struct scsi_tape *STp = filp->private_data;
2014 	struct st_modedef *STm;
2015 	struct st_partstat *STps;
2016 	struct st_buffer *STbp = STp->buffer;
2017 	DEB( char *name = tape_name(STp); )
2018 
2019 	if (mutex_lock_interruptible(&STp->lock))
2020 		return -ERESTARTSYS;
2021 
2022 	retval = rw_checks(STp, filp, count);
2023 	if (retval || count == 0)
2024 		goto out;
2025 
2026 	STm = &(STp->modes[STp->current_mode]);
2027 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2028 		if (!STm->do_read_ahead) {
2029 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2030 			goto out;
2031 		}
2032 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2033 	}
2034 
2035 	STps = &(STp->ps[STp->partition]);
2036 	if (STps->rw == ST_WRITING) {
2037 		retval = flush_buffer(STp, 0);
2038 		if (retval)
2039 			goto out;
2040 		STps->rw = ST_READING;
2041 	}
2042         DEB(
2043 	if (debugging && STps->eof != ST_NOEOF)
2044 		printk(ST_DEB_MSG "%s: EOF/EOM flag up (%d). Bytes %d\n", name,
2045 		       STps->eof, STbp->buffer_bytes);
2046         ) /* end DEB */
2047 
2048 	retval = setup_buffering(STp, buf, count, 1);
2049 	if (retval)
2050 		goto out;
2051 	do_dio = STbp->do_dio;
2052 
2053 	if (STbp->buffer_bytes == 0 &&
2054 	    STps->eof >= ST_EOD_1) {
2055 		if (STps->eof < ST_EOD) {
2056 			STps->eof += 1;
2057 			retval = 0;
2058 			goto out;
2059 		}
2060 		retval = (-EIO);	/* EOM or Blank Check */
2061 		goto out;
2062 	}
2063 
2064 	if (do_dio) {
2065 		/* Check the buffer writability before any tape movement. Don't alter
2066 		   buffer data. */
2067 		if (copy_from_user(&i, buf, 1) != 0 ||
2068 		    copy_to_user(buf, &i, 1) != 0 ||
2069 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2070 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2071 			retval = (-EFAULT);
2072 			goto out;
2073 		}
2074 	}
2075 
2076 	STps->rw = ST_READING;
2077 
2078 
2079 	/* Loop until enough data in buffer or a special condition found */
2080 	for (total = 0, special = 0; total < count && !special;) {
2081 
2082 		/* Get new data if the buffer is empty */
2083 		if (STbp->buffer_bytes == 0) {
2084 			special = read_tape(STp, count - total, &SRpnt);
2085 			if (special < 0) {	/* No need to continue read */
2086 				retval = special;
2087 				goto out;
2088 			}
2089 		}
2090 
2091 		/* Move the data from driver buffer to user buffer */
2092 		if (STbp->buffer_bytes > 0) {
2093                         DEB(
2094 			if (debugging && STps->eof != ST_NOEOF)
2095 				printk(ST_DEB_MSG
2096                                        "%s: EOF up (%d). Left %d, needed %d.\n", name,
2097 				       STps->eof, STbp->buffer_bytes,
2098                                        (int)(count - total));
2099                         ) /* end DEB */
2100 			transfer = STbp->buffer_bytes < count - total ?
2101 			    STbp->buffer_bytes : count - total;
2102 			if (!do_dio) {
2103 				i = from_buffer(STbp, buf, transfer);
2104 				if (i) {
2105 					retval = i;
2106 					goto out;
2107 				}
2108 			}
2109 			buf += transfer;
2110 			total += transfer;
2111 		}
2112 
2113 		if (STp->block_size == 0)
2114 			break;	/* Read only one variable length block */
2115 
2116 	}			/* for (total = 0, special = 0;
2117                                    total < count && !special; ) */
2118 
2119 	/* Change the eof state if no data from tape or buffer */
2120 	if (total == 0) {
2121 		if (STps->eof == ST_FM_HIT) {
2122 			STps->eof = ST_FM;
2123 			STps->drv_block = 0;
2124 			if (STps->drv_file >= 0)
2125 				STps->drv_file++;
2126 		} else if (STps->eof == ST_EOD_1) {
2127 			STps->eof = ST_EOD_2;
2128 			STps->drv_block = 0;
2129 			if (STps->drv_file >= 0)
2130 				STps->drv_file++;
2131 		} else if (STps->eof == ST_EOD_2)
2132 			STps->eof = ST_EOD;
2133 	} else if (STps->eof == ST_FM)
2134 		STps->eof = ST_NOEOF;
2135 	retval = total;
2136 
2137  out:
2138 	if (SRpnt != NULL) {
2139 		st_release_request(SRpnt);
2140 		SRpnt = NULL;
2141 	}
2142 	if (do_dio) {
2143 		release_buffering(STp, 1);
2144 		STbp->buffer_bytes = 0;
2145 	}
2146 	mutex_unlock(&STp->lock);
2147 
2148 	return retval;
2149 }
2150 
2151 
2152 
2153 DEB(
2154 /* Set the driver options */
2155 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm, char *name)
2156 {
2157 	if (debugging) {
2158 		printk(KERN_INFO
2159 		       "%s: Mode %d options: buffer writes: %d, async writes: %d, read ahead: %d\n",
2160 		       name, STp->current_mode, STm->do_buffer_writes, STm->do_async_writes,
2161 		       STm->do_read_ahead);
2162 		printk(KERN_INFO
2163 		       "%s:    can bsr: %d, two FMs: %d, fast mteom: %d, auto lock: %d,\n",
2164 		       name, STp->can_bsr, STp->two_fm, STp->fast_mteom, STp->do_auto_lock);
2165 		printk(KERN_INFO
2166 		       "%s:    defs for wr: %d, no block limits: %d, partitions: %d, s2 log: %d\n",
2167 		       name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
2168 		       STp->scsi2_logical);
2169 		printk(KERN_INFO
2170 		       "%s:    sysv: %d nowait: %d sili: %d\n", name, STm->sysv, STp->immediate,
2171 			STp->sili);
2172 		printk(KERN_INFO "%s:    debugging: %d\n",
2173 		       name, debugging);
2174 	}
2175 }
2176 	)
2177 
2178 
2179 static int st_set_options(struct scsi_tape *STp, long options)
2180 {
2181 	int value;
2182 	long code;
2183 	struct st_modedef *STm;
2184 	char *name = tape_name(STp);
2185 	struct cdev *cd0, *cd1;
2186 
2187 	STm = &(STp->modes[STp->current_mode]);
2188 	if (!STm->defined) {
2189 		cd0 = STm->cdevs[0]; cd1 = STm->cdevs[1];
2190 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2191 		STm->cdevs[0] = cd0; STm->cdevs[1] = cd1;
2192 		modes_defined = 1;
2193                 DEBC(printk(ST_DEB_MSG
2194                             "%s: Initialized mode %d definition from mode 0\n",
2195                             name, STp->current_mode));
2196 	}
2197 
2198 	code = options & MT_ST_OPTIONS;
2199 	if (code == MT_ST_BOOLEANS) {
2200 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2201 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2202 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2203 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2204 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2205 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2206 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2207 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2208 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2209 		if ((STp->device)->scsi_level >= SCSI_2)
2210 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2211 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2212 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2213 		STm->sysv = (options & MT_ST_SYSV) != 0;
2214 		STp->sili = (options & MT_ST_SILI) != 0;
2215 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2216 		     st_log_options(STp, STm, name); )
2217 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2218 		value = (code == MT_ST_SETBOOLEANS);
2219 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2220 			STm->do_buffer_writes = value;
2221 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2222 			STm->do_async_writes = value;
2223 		if ((options & MT_ST_DEF_WRITES) != 0)
2224 			STm->defaults_for_writes = value;
2225 		if ((options & MT_ST_READ_AHEAD) != 0)
2226 			STm->do_read_ahead = value;
2227 		if ((options & MT_ST_TWO_FM) != 0)
2228 			STp->two_fm = value;
2229 		if ((options & MT_ST_FAST_MTEOM) != 0)
2230 			STp->fast_mteom = value;
2231 		if ((options & MT_ST_AUTO_LOCK) != 0)
2232 			STp->do_auto_lock = value;
2233 		if ((options & MT_ST_CAN_BSR) != 0)
2234 			STp->can_bsr = value;
2235 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2236 			STp->omit_blklims = value;
2237 		if ((STp->device)->scsi_level >= SCSI_2 &&
2238 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2239 			STp->can_partitions = value;
2240 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2241 			STp->scsi2_logical = value;
2242 		if ((options & MT_ST_NOWAIT) != 0)
2243 			STp->immediate = value;
2244 		if ((options & MT_ST_SYSV) != 0)
2245 			STm->sysv = value;
2246 		if ((options & MT_ST_SILI) != 0)
2247 			STp->sili = value;
2248                 DEB(
2249 		if ((options & MT_ST_DEBUGGING) != 0)
2250 			debugging = value;
2251 			st_log_options(STp, STm, name); )
2252 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2253 		/* Retained for compatibility */
2254 	} else if (code == MT_ST_DEF_BLKSIZE) {
2255 		value = (options & ~MT_ST_OPTIONS);
2256 		if (value == ~MT_ST_OPTIONS) {
2257 			STm->default_blksize = (-1);
2258 			DEBC( printk(KERN_INFO "%s: Default block size disabled.\n", name));
2259 		} else {
2260 			STm->default_blksize = value;
2261 			DEBC( printk(KERN_INFO "%s: Default block size set to %d bytes.\n",
2262 			       name, STm->default_blksize));
2263 			if (STp->ready == ST_READY) {
2264 				STp->blksize_changed = 0;
2265 				set_mode_densblk(STp, STm);
2266 			}
2267 		}
2268 	} else if (code == MT_ST_TIMEOUTS) {
2269 		value = (options & ~MT_ST_OPTIONS);
2270 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2271 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2272 			DEBC( printk(KERN_INFO "%s: Long timeout set to %d seconds.\n", name,
2273 			       (value & ~MT_ST_SET_LONG_TIMEOUT)));
2274 		} else {
2275 			blk_queue_rq_timeout(STp->device->request_queue,
2276 					     value * HZ);
2277 			DEBC( printk(KERN_INFO "%s: Normal timeout set to %d seconds.\n",
2278 				name, value) );
2279 		}
2280 	} else if (code == MT_ST_SET_CLN) {
2281 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2282 		if (value != 0 &&
2283 			(value < EXTENDED_SENSE_START ||
2284 				value >= SCSI_SENSE_BUFFERSIZE))
2285 			return (-EINVAL);
2286 		STp->cln_mode = value;
2287 		STp->cln_sense_mask = (options >> 8) & 0xff;
2288 		STp->cln_sense_value = (options >> 16) & 0xff;
2289 		printk(KERN_INFO
2290 		       "%s: Cleaning request mode %d, mask %02x, value %02x\n",
2291 		       name, value, STp->cln_sense_mask, STp->cln_sense_value);
2292 	} else if (code == MT_ST_DEF_OPTIONS) {
2293 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2294 		value = (options & MT_ST_CLEAR_DEFAULT);
2295 		if (code == MT_ST_DEF_DENSITY) {
2296 			if (value == MT_ST_CLEAR_DEFAULT) {
2297 				STm->default_density = (-1);
2298 				DEBC( printk(KERN_INFO "%s: Density default disabled.\n",
2299                                        name));
2300 			} else {
2301 				STm->default_density = value & 0xff;
2302 				DEBC( printk(KERN_INFO "%s: Density default set to %x\n",
2303 				       name, STm->default_density));
2304 				if (STp->ready == ST_READY) {
2305 					STp->density_changed = 0;
2306 					set_mode_densblk(STp, STm);
2307 				}
2308 			}
2309 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2310 			if (value == MT_ST_CLEAR_DEFAULT) {
2311 				STp->default_drvbuffer = 0xff;
2312 				DEBC( printk(KERN_INFO
2313                                        "%s: Drive buffer default disabled.\n", name));
2314 			} else {
2315 				STp->default_drvbuffer = value & 7;
2316 				DEBC( printk(KERN_INFO
2317                                        "%s: Drive buffer default set to %x\n",
2318 				       name, STp->default_drvbuffer));
2319 				if (STp->ready == ST_READY)
2320 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2321 			}
2322 		} else if (code == MT_ST_DEF_COMPRESSION) {
2323 			if (value == MT_ST_CLEAR_DEFAULT) {
2324 				STm->default_compression = ST_DONT_TOUCH;
2325 				DEBC( printk(KERN_INFO
2326                                        "%s: Compression default disabled.\n", name));
2327 			} else {
2328 				if ((value & 0xff00) != 0) {
2329 					STp->c_algo = (value & 0xff00) >> 8;
2330 					DEBC( printk(KERN_INFO "%s: Compression algorithm set to 0x%x.\n",
2331 					       name, STp->c_algo));
2332 				}
2333 				if ((value & 0xff) != 0xff) {
2334 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2335 					DEBC( printk(KERN_INFO "%s: Compression default set to %x\n",
2336 					       name, (value & 1)));
2337 					if (STp->ready == ST_READY) {
2338 						STp->compression_changed = 0;
2339 						st_compression(STp, (STm->default_compression == ST_YES));
2340 					}
2341 				}
2342 			}
2343 		}
2344 	} else
2345 		return (-EIO);
2346 
2347 	return 0;
2348 }
2349 
2350 #define MODE_HEADER_LENGTH  4
2351 
2352 /* Mode header and page byte offsets */
2353 #define MH_OFF_DATA_LENGTH     0
2354 #define MH_OFF_MEDIUM_TYPE     1
2355 #define MH_OFF_DEV_SPECIFIC    2
2356 #define MH_OFF_BDESCS_LENGTH   3
2357 #define MP_OFF_PAGE_NBR        0
2358 #define MP_OFF_PAGE_LENGTH     1
2359 
2360 /* Mode header and page bit masks */
2361 #define MH_BIT_WP              0x80
2362 #define MP_MSK_PAGE_NBR        0x3f
2363 
2364 /* Don't return block descriptors */
2365 #define MODE_SENSE_OMIT_BDESCS 0x08
2366 
2367 #define MODE_SELECT_PAGE_FORMAT 0x10
2368 
2369 /* Read a mode page into the tape buffer. The block descriptors are included
2370    if incl_block_descs is true. The page control is ored to the page number
2371    parameter, if necessary. */
2372 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2373 {
2374 	unsigned char cmd[MAX_COMMAND_SIZE];
2375 	struct st_request *SRpnt;
2376 
2377 	memset(cmd, 0, MAX_COMMAND_SIZE);
2378 	cmd[0] = MODE_SENSE;
2379 	if (omit_block_descs)
2380 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2381 	cmd[2] = page;
2382 	cmd[4] = 255;
2383 
2384 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2385 			   STp->device->request_queue->rq_timeout, 0, 1);
2386 	if (SRpnt == NULL)
2387 		return (STp->buffer)->syscall_result;
2388 
2389 	st_release_request(SRpnt);
2390 
2391 	return STp->buffer->syscall_result;
2392 }
2393 
2394 
2395 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2396    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2397 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2398 {
2399 	int pgo;
2400 	unsigned char cmd[MAX_COMMAND_SIZE];
2401 	struct st_request *SRpnt;
2402 	int timeout;
2403 
2404 	memset(cmd, 0, MAX_COMMAND_SIZE);
2405 	cmd[0] = MODE_SELECT;
2406 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2407 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2408 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2409 
2410 	/* Clear reserved fields */
2411 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2412 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2413 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2414 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2415 
2416 	timeout = slow ?
2417 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2418 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2419 			   timeout, 0, 1);
2420 	if (SRpnt == NULL)
2421 		return (STp->buffer)->syscall_result;
2422 
2423 	st_release_request(SRpnt);
2424 
2425 	return STp->buffer->syscall_result;
2426 }
2427 
2428 
2429 #define COMPRESSION_PAGE        0x0f
2430 #define COMPRESSION_PAGE_LENGTH 16
2431 
2432 #define CP_OFF_DCE_DCC          2
2433 #define CP_OFF_C_ALGO           7
2434 
2435 #define DCE_MASK  0x80
2436 #define DCC_MASK  0x40
2437 #define RED_MASK  0x60
2438 
2439 
2440 /* Control the compression with mode page 15. Algorithm not changed if zero.
2441 
2442    The block descriptors are read and written because Sony SDT-7000 does not
2443    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2444    Including block descriptors should not cause any harm to other drives. */
2445 
2446 static int st_compression(struct scsi_tape * STp, int state)
2447 {
2448 	int retval;
2449 	int mpoffs;  /* Offset to mode page start */
2450 	unsigned char *b_data = (STp->buffer)->b_data;
2451 	DEB( char *name = tape_name(STp); )
2452 
2453 	if (STp->ready != ST_READY)
2454 		return (-EIO);
2455 
2456 	/* Read the current page contents */
2457 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2458 	if (retval) {
2459                 DEBC(printk(ST_DEB_MSG "%s: Compression mode page not supported.\n",
2460                             name));
2461 		return (-EIO);
2462 	}
2463 
2464 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2465         DEBC(printk(ST_DEB_MSG "%s: Compression state is %d.\n", name,
2466                     (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0)));
2467 
2468 	/* Check if compression can be changed */
2469 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2470                 DEBC(printk(ST_DEB_MSG "%s: Compression not supported.\n", name));
2471 		return (-EIO);
2472 	}
2473 
2474 	/* Do the change */
2475 	if (state) {
2476 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2477 		if (STp->c_algo != 0)
2478 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2479 	}
2480 	else {
2481 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2482 		if (STp->c_algo != 0)
2483 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2484 	}
2485 
2486 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2487 	if (retval) {
2488                 DEBC(printk(ST_DEB_MSG "%s: Compression change failed.\n", name));
2489 		return (-EIO);
2490 	}
2491         DEBC(printk(ST_DEB_MSG "%s: Compression state changed to %d.\n",
2492 		       name, state));
2493 
2494 	STp->compression_changed = 1;
2495 	return 0;
2496 }
2497 
2498 
2499 /* Process the load and unload commands (does unload if the load code is zero) */
2500 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2501 {
2502 	int retval = (-EIO), timeout;
2503 	DEB( char *name = tape_name(STp); )
2504 	unsigned char cmd[MAX_COMMAND_SIZE];
2505 	struct st_partstat *STps;
2506 	struct st_request *SRpnt;
2507 
2508 	if (STp->ready != ST_READY && !load_code) {
2509 		if (STp->ready == ST_NO_TAPE)
2510 			return (-ENOMEDIUM);
2511 		else
2512 			return (-EIO);
2513 	}
2514 
2515 	memset(cmd, 0, MAX_COMMAND_SIZE);
2516 	cmd[0] = START_STOP;
2517 	if (load_code)
2518 		cmd[4] |= 1;
2519 	/*
2520 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2521 	 */
2522 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2523 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2524 		DEBC(printk(ST_DEB_MSG "%s: Enhanced %sload slot %2d.\n",
2525 			    name, (cmd[4]) ? "" : "un",
2526 			    load_code - MT_ST_HPLOADER_OFFSET));
2527 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2528 	}
2529 	if (STp->immediate) {
2530 		cmd[1] = 1;	/* Don't wait for completion */
2531 		timeout = STp->device->request_queue->rq_timeout;
2532 	}
2533 	else
2534 		timeout = STp->long_timeout;
2535 
2536 	DEBC(
2537 		if (!load_code)
2538 		printk(ST_DEB_MSG "%s: Unloading tape.\n", name);
2539 		else
2540 		printk(ST_DEB_MSG "%s: Loading tape.\n", name);
2541 		);
2542 
2543 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2544 			   timeout, MAX_RETRIES, 1);
2545 	if (!SRpnt)
2546 		return (STp->buffer)->syscall_result;
2547 
2548 	retval = (STp->buffer)->syscall_result;
2549 	st_release_request(SRpnt);
2550 
2551 	if (!retval) {	/* SCSI command successful */
2552 
2553 		if (!load_code) {
2554 			STp->rew_at_close = 0;
2555 			STp->ready = ST_NO_TAPE;
2556 		}
2557 		else {
2558 			STp->rew_at_close = STp->autorew_dev;
2559 			retval = check_tape(STp, filp);
2560 			if (retval > 0)
2561 				retval = 0;
2562 		}
2563 	}
2564 	else {
2565 		STps = &(STp->ps[STp->partition]);
2566 		STps->drv_file = STps->drv_block = (-1);
2567 	}
2568 
2569 	return retval;
2570 }
2571 
2572 #if DEBUG
2573 #define ST_DEB_FORWARD  0
2574 #define ST_DEB_BACKWARD 1
2575 static void deb_space_print(char *name, int direction, char *units, unsigned char *cmd)
2576 {
2577 	s32 sc;
2578 
2579 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2580 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2581 	if (direction)
2582 		sc = -sc;
2583 	printk(ST_DEB_MSG "%s: Spacing tape %s over %d %s.\n", name,
2584 	       direction ? "backward" : "forward", sc, units);
2585 }
2586 #endif
2587 
2588 
2589 /* Internal ioctl function */
2590 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2591 {
2592 	int timeout;
2593 	long ltmp;
2594 	int ioctl_result;
2595 	int chg_eof = 1;
2596 	unsigned char cmd[MAX_COMMAND_SIZE];
2597 	struct st_request *SRpnt;
2598 	struct st_partstat *STps;
2599 	int fileno, blkno, at_sm, undone;
2600 	int datalen = 0, direction = DMA_NONE;
2601 	char *name = tape_name(STp);
2602 
2603 	WARN_ON(STp->buffer->do_dio != 0);
2604 	if (STp->ready != ST_READY) {
2605 		if (STp->ready == ST_NO_TAPE)
2606 			return (-ENOMEDIUM);
2607 		else
2608 			return (-EIO);
2609 	}
2610 	timeout = STp->long_timeout;
2611 	STps = &(STp->ps[STp->partition]);
2612 	fileno = STps->drv_file;
2613 	blkno = STps->drv_block;
2614 	at_sm = STps->at_sm;
2615 
2616 	memset(cmd, 0, MAX_COMMAND_SIZE);
2617 	switch (cmd_in) {
2618 	case MTFSFM:
2619 		chg_eof = 0;	/* Changed from the FSF after this */
2620 	case MTFSF:
2621 		cmd[0] = SPACE;
2622 		cmd[1] = 0x01;	/* Space FileMarks */
2623 		cmd[2] = (arg >> 16);
2624 		cmd[3] = (arg >> 8);
2625 		cmd[4] = arg;
2626                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "filemarks", cmd);)
2627 		if (fileno >= 0)
2628 			fileno += arg;
2629 		blkno = 0;
2630 		at_sm &= (arg == 0);
2631 		break;
2632 	case MTBSFM:
2633 		chg_eof = 0;	/* Changed from the FSF after this */
2634 	case MTBSF:
2635 		cmd[0] = SPACE;
2636 		cmd[1] = 0x01;	/* Space FileMarks */
2637 		ltmp = (-arg);
2638 		cmd[2] = (ltmp >> 16);
2639 		cmd[3] = (ltmp >> 8);
2640 		cmd[4] = ltmp;
2641                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "filemarks", cmd);)
2642 		if (fileno >= 0)
2643 			fileno -= arg;
2644 		blkno = (-1);	/* We can't know the block number */
2645 		at_sm &= (arg == 0);
2646 		break;
2647 	case MTFSR:
2648 		cmd[0] = SPACE;
2649 		cmd[1] = 0x00;	/* Space Blocks */
2650 		cmd[2] = (arg >> 16);
2651 		cmd[3] = (arg >> 8);
2652 		cmd[4] = arg;
2653                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "blocks", cmd);)
2654 		if (blkno >= 0)
2655 			blkno += arg;
2656 		at_sm &= (arg == 0);
2657 		break;
2658 	case MTBSR:
2659 		cmd[0] = SPACE;
2660 		cmd[1] = 0x00;	/* Space Blocks */
2661 		ltmp = (-arg);
2662 		cmd[2] = (ltmp >> 16);
2663 		cmd[3] = (ltmp >> 8);
2664 		cmd[4] = ltmp;
2665                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "blocks", cmd);)
2666 		if (blkno >= 0)
2667 			blkno -= arg;
2668 		at_sm &= (arg == 0);
2669 		break;
2670 	case MTFSS:
2671 		cmd[0] = SPACE;
2672 		cmd[1] = 0x04;	/* Space Setmarks */
2673 		cmd[2] = (arg >> 16);
2674 		cmd[3] = (arg >> 8);
2675 		cmd[4] = arg;
2676                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "setmarks", cmd);)
2677 		if (arg != 0) {
2678 			blkno = fileno = (-1);
2679 			at_sm = 1;
2680 		}
2681 		break;
2682 	case MTBSS:
2683 		cmd[0] = SPACE;
2684 		cmd[1] = 0x04;	/* Space Setmarks */
2685 		ltmp = (-arg);
2686 		cmd[2] = (ltmp >> 16);
2687 		cmd[3] = (ltmp >> 8);
2688 		cmd[4] = ltmp;
2689                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "setmarks", cmd);)
2690 		if (arg != 0) {
2691 			blkno = fileno = (-1);
2692 			at_sm = 1;
2693 		}
2694 		break;
2695 	case MTWEOF:
2696 	case MTWSM:
2697 		if (STp->write_prot)
2698 			return (-EACCES);
2699 		cmd[0] = WRITE_FILEMARKS;
2700 		if (cmd_in == MTWSM)
2701 			cmd[1] = 2;
2702 		cmd[2] = (arg >> 16);
2703 		cmd[3] = (arg >> 8);
2704 		cmd[4] = arg;
2705 		timeout = STp->device->request_queue->rq_timeout;
2706                 DEBC(
2707                      if (cmd_in == MTWEOF)
2708                                printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name,
2709 				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
2710                      else
2711 				printk(ST_DEB_MSG "%s: Writing %d setmarks.\n", name,
2712 				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
2713 		)
2714 		if (fileno >= 0)
2715 			fileno += arg;
2716 		blkno = 0;
2717 		at_sm = (cmd_in == MTWSM);
2718 		break;
2719 	case MTREW:
2720 		cmd[0] = REZERO_UNIT;
2721 		if (STp->immediate) {
2722 			cmd[1] = 1;	/* Don't wait for completion */
2723 			timeout = STp->device->request_queue->rq_timeout;
2724 		}
2725                 DEBC(printk(ST_DEB_MSG "%s: Rewinding tape.\n", name));
2726 		fileno = blkno = at_sm = 0;
2727 		break;
2728 	case MTNOP:
2729                 DEBC(printk(ST_DEB_MSG "%s: No op on tape.\n", name));
2730 		return 0;	/* Should do something ? */
2731 		break;
2732 	case MTRETEN:
2733 		cmd[0] = START_STOP;
2734 		if (STp->immediate) {
2735 			cmd[1] = 1;	/* Don't wait for completion */
2736 			timeout = STp->device->request_queue->rq_timeout;
2737 		}
2738 		cmd[4] = 3;
2739                 DEBC(printk(ST_DEB_MSG "%s: Retensioning tape.\n", name));
2740 		fileno = blkno = at_sm = 0;
2741 		break;
2742 	case MTEOM:
2743 		if (!STp->fast_mteom) {
2744 			/* space to the end of tape */
2745 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2746 			fileno = STps->drv_file;
2747 			if (STps->eof >= ST_EOD_1)
2748 				return 0;
2749 			/* The next lines would hide the number of spaced FileMarks
2750 			   That's why I inserted the previous lines. I had no luck
2751 			   with detecting EOM with FSF, so we go now to EOM.
2752 			   Joerg Weule */
2753 		} else
2754 			fileno = (-1);
2755 		cmd[0] = SPACE;
2756 		cmd[1] = 3;
2757                 DEBC(printk(ST_DEB_MSG "%s: Spacing to end of recorded medium.\n",
2758                             name));
2759 		blkno = -1;
2760 		at_sm = 0;
2761 		break;
2762 	case MTERASE:
2763 		if (STp->write_prot)
2764 			return (-EACCES);
2765 		cmd[0] = ERASE;
2766 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2767 		if (STp->immediate) {
2768 			cmd[1] |= 2;	/* Don't wait for completion */
2769 			timeout = STp->device->request_queue->rq_timeout;
2770 		}
2771 		else
2772 			timeout = STp->long_timeout * 8;
2773 
2774                 DEBC(printk(ST_DEB_MSG "%s: Erasing tape.\n", name));
2775 		fileno = blkno = at_sm = 0;
2776 		break;
2777 	case MTSETBLK:		/* Set block length */
2778 	case MTSETDENSITY:	/* Set tape density */
2779 	case MTSETDRVBUFFER:	/* Set drive buffering */
2780 	case SET_DENS_AND_BLK:	/* Set density and block size */
2781 		chg_eof = 0;
2782 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2783 			return (-EIO);	/* Not allowed if data in buffer */
2784 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2785 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2786 		    STp->max_block > 0 &&
2787 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2788 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2789 			printk(KERN_WARNING "%s: Illegal block size.\n", name);
2790 			return (-EINVAL);
2791 		}
2792 		cmd[0] = MODE_SELECT;
2793 		if ((STp->use_pf & USE_PF))
2794 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2795 		cmd[4] = datalen = 12;
2796 		direction = DMA_TO_DEVICE;
2797 
2798 		memset((STp->buffer)->b_data, 0, 12);
2799 		if (cmd_in == MTSETDRVBUFFER)
2800 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2801 		else
2802 			(STp->buffer)->b_data[2] =
2803 			    STp->drv_buffer << 4;
2804 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2805 		if (cmd_in == MTSETDENSITY) {
2806 			(STp->buffer)->b_data[4] = arg;
2807 			STp->density_changed = 1;	/* At least we tried ;-) */
2808 		} else if (cmd_in == SET_DENS_AND_BLK)
2809 			(STp->buffer)->b_data[4] = arg >> 24;
2810 		else
2811 			(STp->buffer)->b_data[4] = STp->density;
2812 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2813 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2814 			if (cmd_in == MTSETBLK)
2815 				STp->blksize_changed = 1; /* At least we tried ;-) */
2816 		} else
2817 			ltmp = STp->block_size;
2818 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2819 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2820 		(STp->buffer)->b_data[11] = ltmp;
2821 		timeout = STp->device->request_queue->rq_timeout;
2822                 DEBC(
2823 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2824 				printk(ST_DEB_MSG
2825                                        "%s: Setting block size to %d bytes.\n", name,
2826 				       (STp->buffer)->b_data[9] * 65536 +
2827 				       (STp->buffer)->b_data[10] * 256 +
2828 				       (STp->buffer)->b_data[11]);
2829 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2830 				printk(ST_DEB_MSG
2831                                        "%s: Setting density code to %x.\n", name,
2832 				       (STp->buffer)->b_data[4]);
2833 			if (cmd_in == MTSETDRVBUFFER)
2834 				printk(ST_DEB_MSG
2835                                        "%s: Setting drive buffer code to %d.\n", name,
2836 				    ((STp->buffer)->b_data[2] >> 4) & 7);
2837 		)
2838 		break;
2839 	default:
2840 		return (-ENOSYS);
2841 	}
2842 
2843 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2844 			   timeout, MAX_RETRIES, 1);
2845 	if (!SRpnt)
2846 		return (STp->buffer)->syscall_result;
2847 
2848 	ioctl_result = (STp->buffer)->syscall_result;
2849 
2850 	if (!ioctl_result) {	/* SCSI command successful */
2851 		st_release_request(SRpnt);
2852 		SRpnt = NULL;
2853 		STps->drv_block = blkno;
2854 		STps->drv_file = fileno;
2855 		STps->at_sm = at_sm;
2856 
2857 		if (cmd_in == MTBSFM)
2858 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2859 		else if (cmd_in == MTFSFM)
2860 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2861 
2862 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2863 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2864 			if (STp->block_size != 0) {
2865 				(STp->buffer)->buffer_blocks =
2866 				    (STp->buffer)->buffer_size / STp->block_size;
2867 			}
2868 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2869 			if (cmd_in == SET_DENS_AND_BLK)
2870 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2871 		} else if (cmd_in == MTSETDRVBUFFER)
2872 			STp->drv_buffer = (arg & 7);
2873 		else if (cmd_in == MTSETDENSITY)
2874 			STp->density = arg;
2875 
2876 		if (cmd_in == MTEOM)
2877 			STps->eof = ST_EOD;
2878 		else if (cmd_in == MTFSF)
2879 			STps->eof = ST_FM;
2880 		else if (chg_eof)
2881 			STps->eof = ST_NOEOF;
2882 
2883 		if (cmd_in == MTWEOF)
2884 			STps->rw = ST_IDLE;
2885 	} else { /* SCSI command was not completely successful. Don't return
2886                     from this block without releasing the SCSI command block! */
2887 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
2888 
2889 		if (cmdstatp->flags & SENSE_EOM) {
2890 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
2891 			    cmd_in != MTBSR && cmd_in != MTBSS)
2892 				STps->eof = ST_EOM_OK;
2893 			STps->drv_block = 0;
2894 		}
2895 
2896 		if (cmdstatp->remainder_valid)
2897 			undone = (int)cmdstatp->uremainder64;
2898 		else
2899 			undone = 0;
2900 
2901 		if (cmd_in == MTWEOF &&
2902 		    cmdstatp->have_sense &&
2903 		    (cmdstatp->flags & SENSE_EOM)) {
2904 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
2905 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
2906 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
2907 				STps->eof = ST_NOEOF;
2908 			} else {  /* Writing EOF(s) failed */
2909 				if (fileno >= 0)
2910 					fileno -= undone;
2911 				if (undone < arg)
2912 					STps->eof = ST_NOEOF;
2913 			}
2914 			STps->drv_file = fileno;
2915 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
2916 			if (fileno >= 0)
2917 				STps->drv_file = fileno - undone;
2918 			else
2919 				STps->drv_file = fileno;
2920 			STps->drv_block = -1;
2921 			STps->eof = ST_NOEOF;
2922 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
2923 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
2924 				undone = (-undone);
2925 			if (STps->drv_file >= 0)
2926 				STps->drv_file = fileno + undone;
2927 			STps->drv_block = 0;
2928 			STps->eof = ST_NOEOF;
2929 		} else if (cmd_in == MTFSR) {
2930 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
2931 				if (STps->drv_file >= 0)
2932 					STps->drv_file++;
2933 				STps->drv_block = 0;
2934 				STps->eof = ST_FM;
2935 			} else {
2936 				if (blkno >= undone)
2937 					STps->drv_block = blkno - undone;
2938 				else
2939 					STps->drv_block = (-1);
2940 				STps->eof = ST_NOEOF;
2941 			}
2942 		} else if (cmd_in == MTBSR) {
2943 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
2944 				STps->drv_file--;
2945 				STps->drv_block = (-1);
2946 			} else {
2947 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
2948 					undone = (-undone);
2949 				if (STps->drv_block >= 0)
2950 					STps->drv_block = blkno + undone;
2951 			}
2952 			STps->eof = ST_NOEOF;
2953 		} else if (cmd_in == MTEOM) {
2954 			STps->drv_file = (-1);
2955 			STps->drv_block = (-1);
2956 			STps->eof = ST_EOD;
2957 		} else if (cmd_in == MTSETBLK ||
2958 			   cmd_in == MTSETDENSITY ||
2959 			   cmd_in == MTSETDRVBUFFER ||
2960 			   cmd_in == SET_DENS_AND_BLK) {
2961 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
2962 			    !(STp->use_pf & PF_TESTED)) {
2963 				/* Try the other possible state of Page Format if not
2964 				   already tried */
2965 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
2966 				st_release_request(SRpnt);
2967 				SRpnt = NULL;
2968 				return st_int_ioctl(STp, cmd_in, arg);
2969 			}
2970 		} else if (chg_eof)
2971 			STps->eof = ST_NOEOF;
2972 
2973 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
2974 			STps->eof = ST_EOD;
2975 
2976 		st_release_request(SRpnt);
2977 		SRpnt = NULL;
2978 	}
2979 
2980 	return ioctl_result;
2981 }
2982 
2983 
2984 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
2985    structure. */
2986 
2987 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
2988 			int logical)
2989 {
2990 	int result;
2991 	unsigned char scmd[MAX_COMMAND_SIZE];
2992 	struct st_request *SRpnt;
2993 	DEB( char *name = tape_name(STp); )
2994 
2995 	if (STp->ready != ST_READY)
2996 		return (-EIO);
2997 
2998 	memset(scmd, 0, MAX_COMMAND_SIZE);
2999 	if ((STp->device)->scsi_level < SCSI_2) {
3000 		scmd[0] = QFA_REQUEST_BLOCK;
3001 		scmd[4] = 3;
3002 	} else {
3003 		scmd[0] = READ_POSITION;
3004 		if (!logical && !STp->scsi2_logical)
3005 			scmd[1] = 1;
3006 	}
3007 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3008 			   STp->device->request_queue->rq_timeout,
3009 			   MAX_READY_RETRIES, 1);
3010 	if (!SRpnt)
3011 		return (STp->buffer)->syscall_result;
3012 
3013 	if ((STp->buffer)->syscall_result != 0 ||
3014 	    (STp->device->scsi_level >= SCSI_2 &&
3015 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3016 		*block = *partition = 0;
3017                 DEBC(printk(ST_DEB_MSG "%s: Can't read tape position.\n", name));
3018 		result = (-EIO);
3019 	} else {
3020 		result = 0;
3021 		if ((STp->device)->scsi_level < SCSI_2) {
3022 			*block = ((STp->buffer)->b_data[0] << 16)
3023 			    + ((STp->buffer)->b_data[1] << 8)
3024 			    + (STp->buffer)->b_data[2];
3025 			*partition = 0;
3026 		} else {
3027 			*block = ((STp->buffer)->b_data[4] << 24)
3028 			    + ((STp->buffer)->b_data[5] << 16)
3029 			    + ((STp->buffer)->b_data[6] << 8)
3030 			    + (STp->buffer)->b_data[7];
3031 			*partition = (STp->buffer)->b_data[1];
3032 			if (((STp->buffer)->b_data[0] & 0x80) &&
3033 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3034 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3035 		}
3036                 DEBC(printk(ST_DEB_MSG "%s: Got tape pos. blk %d part %d.\n", name,
3037                             *block, *partition));
3038 	}
3039 	st_release_request(SRpnt);
3040 	SRpnt = NULL;
3041 
3042 	return result;
3043 }
3044 
3045 
3046 /* Set the tape block and partition. Negative partition means that only the
3047    block should be set in vendor specific way. */
3048 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3049 			int logical)
3050 {
3051 	struct st_partstat *STps;
3052 	int result, p;
3053 	unsigned int blk;
3054 	int timeout;
3055 	unsigned char scmd[MAX_COMMAND_SIZE];
3056 	struct st_request *SRpnt;
3057 	DEB( char *name = tape_name(STp); )
3058 
3059 	if (STp->ready != ST_READY)
3060 		return (-EIO);
3061 	timeout = STp->long_timeout;
3062 	STps = &(STp->ps[STp->partition]);
3063 
3064         DEBC(printk(ST_DEB_MSG "%s: Setting block to %d and partition to %d.\n",
3065                     name, block, partition));
3066 	DEB(if (partition < 0)
3067 		return (-EIO); )
3068 
3069 	/* Update the location at the partition we are leaving */
3070 	if ((!STp->can_partitions && partition != 0) ||
3071 	    partition >= ST_NBR_PARTITIONS)
3072 		return (-EINVAL);
3073 	if (partition != STp->partition) {
3074 		if (get_location(STp, &blk, &p, 1))
3075 			STps->last_block_valid = 0;
3076 		else {
3077 			STps->last_block_valid = 1;
3078 			STps->last_block_visited = blk;
3079                         DEBC(printk(ST_DEB_MSG
3080                                     "%s: Visited block %d for partition %d saved.\n",
3081                                     name, blk, STp->partition));
3082 		}
3083 	}
3084 
3085 	memset(scmd, 0, MAX_COMMAND_SIZE);
3086 	if ((STp->device)->scsi_level < SCSI_2) {
3087 		scmd[0] = QFA_SEEK_BLOCK;
3088 		scmd[2] = (block >> 16);
3089 		scmd[3] = (block >> 8);
3090 		scmd[4] = block;
3091 		scmd[5] = 0;
3092 	} else {
3093 		scmd[0] = SEEK_10;
3094 		scmd[3] = (block >> 24);
3095 		scmd[4] = (block >> 16);
3096 		scmd[5] = (block >> 8);
3097 		scmd[6] = block;
3098 		if (!logical && !STp->scsi2_logical)
3099 			scmd[1] = 4;
3100 		if (STp->partition != partition) {
3101 			scmd[1] |= 2;
3102 			scmd[8] = partition;
3103                         DEBC(printk(ST_DEB_MSG
3104                                     "%s: Trying to change partition from %d to %d\n",
3105                                     name, STp->partition, partition));
3106 		}
3107 	}
3108 	if (STp->immediate) {
3109 		scmd[1] |= 1;		/* Don't wait for completion */
3110 		timeout = STp->device->request_queue->rq_timeout;
3111 	}
3112 
3113 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3114 			   timeout, MAX_READY_RETRIES, 1);
3115 	if (!SRpnt)
3116 		return (STp->buffer)->syscall_result;
3117 
3118 	STps->drv_block = STps->drv_file = (-1);
3119 	STps->eof = ST_NOEOF;
3120 	if ((STp->buffer)->syscall_result != 0) {
3121 		result = (-EIO);
3122 		if (STp->can_partitions &&
3123 		    (STp->device)->scsi_level >= SCSI_2 &&
3124 		    (p = find_partition(STp)) >= 0)
3125 			STp->partition = p;
3126 	} else {
3127 		if (STp->can_partitions) {
3128 			STp->partition = partition;
3129 			STps = &(STp->ps[partition]);
3130 			if (!STps->last_block_valid ||
3131 			    STps->last_block_visited != block) {
3132 				STps->at_sm = 0;
3133 				STps->rw = ST_IDLE;
3134 			}
3135 		} else
3136 			STps->at_sm = 0;
3137 		if (block == 0)
3138 			STps->drv_block = STps->drv_file = 0;
3139 		result = 0;
3140 	}
3141 
3142 	st_release_request(SRpnt);
3143 	SRpnt = NULL;
3144 
3145 	return result;
3146 }
3147 
3148 
3149 /* Find the current partition number for the drive status. Called from open and
3150    returns either partition number of negative error code. */
3151 static int find_partition(struct scsi_tape *STp)
3152 {
3153 	int i, partition;
3154 	unsigned int block;
3155 
3156 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3157 		return i;
3158 	if (partition >= ST_NBR_PARTITIONS)
3159 		return (-EIO);
3160 	return partition;
3161 }
3162 
3163 
3164 /* Change the partition if necessary */
3165 static int switch_partition(struct scsi_tape *STp)
3166 {
3167 	struct st_partstat *STps;
3168 
3169 	if (STp->partition == STp->new_partition)
3170 		return 0;
3171 	STps = &(STp->ps[STp->new_partition]);
3172 	if (!STps->last_block_valid)
3173 		STps->last_block_visited = 0;
3174 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3175 }
3176 
3177 /* Functions for reading and writing the medium partition mode page. */
3178 
3179 #define PART_PAGE   0x11
3180 #define PART_PAGE_FIXED_LENGTH 8
3181 
3182 #define PP_OFF_MAX_ADD_PARTS   2
3183 #define PP_OFF_NBR_ADD_PARTS   3
3184 #define PP_OFF_FLAGS           4
3185 #define PP_OFF_PART_UNITS      6
3186 #define PP_OFF_RESERVED        7
3187 
3188 #define PP_BIT_IDP             0x20
3189 #define PP_MSK_PSUM_MB         0x10
3190 
3191 /* Get the number of partitions on the tape. As a side effect reads the
3192    mode page into the tape buffer. */
3193 static int nbr_partitions(struct scsi_tape *STp)
3194 {
3195 	int result;
3196 	DEB( char *name = tape_name(STp); )
3197 
3198 	if (STp->ready != ST_READY)
3199 		return (-EIO);
3200 
3201 	result = read_mode_page(STp, PART_PAGE, 1);
3202 
3203 	if (result) {
3204                 DEBC(printk(ST_DEB_MSG "%s: Can't read medium partition page.\n",
3205                             name));
3206 		result = (-EIO);
3207 	} else {
3208 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3209 					      PP_OFF_NBR_ADD_PARTS] + 1;
3210                 DEBC(printk(ST_DEB_MSG "%s: Number of partitions %d.\n", name, result));
3211 	}
3212 
3213 	return result;
3214 }
3215 
3216 
3217 /* Partition the tape into two partitions if size > 0 or one partition if
3218    size == 0.
3219 
3220    The block descriptors are read and written because Sony SDT-7000 does not
3221    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3222 
3223    My HP C1533A drive returns only one partition size field. This is used to
3224    set the size of partition 1. There is no size field for the default partition.
3225    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3226    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3227    The following algorithm is used to accommodate both drives: if the number of
3228    partition size fields is greater than the maximum number of additional partitions
3229    in the mode page, the second field is used. Otherwise the first field is used.
3230 
3231    For Seagate DDS drives the page length must be 8 when no partitions is defined
3232    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3233    is acceptable also to some other old drives and enforced if the first partition
3234    size field is used for the first additional partition size.
3235  */
3236 static int partition_tape(struct scsi_tape *STp, int size)
3237 {
3238 	char *name = tape_name(STp);
3239 	int result;
3240 	int pgo, psd_cnt, psdo;
3241 	unsigned char *bp;
3242 
3243 	result = read_mode_page(STp, PART_PAGE, 0);
3244 	if (result) {
3245 		DEBC(printk(ST_DEB_MSG "%s: Can't read partition mode page.\n", name));
3246 		return result;
3247 	}
3248 	/* The mode page is in the buffer. Let's modify it and write it. */
3249 	bp = (STp->buffer)->b_data;
3250 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3251 	DEBC(printk(ST_DEB_MSG "%s: Partition page length is %d bytes.\n",
3252 		    name, bp[pgo + MP_OFF_PAGE_LENGTH] + 2));
3253 
3254 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3255 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3256 	if (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS]) {
3257 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest of the tape */
3258 		psdo += 2;
3259 	}
3260 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3261 
3262 	DEBC(printk("%s: psd_cnt %d, max.parts %d, nbr_parts %d\n", name,
3263 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3264 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]));
3265 
3266 	if (size <= 0) {
3267 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3268 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3269 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3270                 DEBC(printk(ST_DEB_MSG "%s: Formatting tape with one partition.\n",
3271                             name));
3272 	} else {
3273 		bp[psdo] = (size >> 8) & 0xff;
3274 		bp[psdo + 1] = size & 0xff;
3275 		bp[pgo + 3] = 1;
3276 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3277 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3278                 DEBC(printk(ST_DEB_MSG
3279                             "%s: Formatting tape with two partitions (1 = %d MB).\n",
3280                             name, size));
3281 	}
3282 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3283 	bp[pgo + PP_OFF_RESERVED] = 0;
3284 	bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | PP_MSK_PSUM_MB;
3285 
3286 	result = write_mode_page(STp, PART_PAGE, 1);
3287 	if (result) {
3288 		printk(KERN_INFO "%s: Partitioning of tape failed.\n", name);
3289 		result = (-EIO);
3290 	}
3291 
3292 	return result;
3293 }
3294 
3295 
3296 
3297 /* The ioctl command */
3298 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3299 {
3300 	int i, cmd_nr, cmd_type, bt;
3301 	int retval = 0;
3302 	unsigned int blk;
3303 	struct scsi_tape *STp = file->private_data;
3304 	struct st_modedef *STm;
3305 	struct st_partstat *STps;
3306 	char *name = tape_name(STp);
3307 	void __user *p = (void __user *)arg;
3308 
3309 	if (mutex_lock_interruptible(&STp->lock))
3310 		return -ERESTARTSYS;
3311 
3312         DEB(
3313 	if (debugging && !STp->in_use) {
3314 		printk(ST_DEB_MSG "%s: Incorrect device.\n", name);
3315 		retval = (-EIO);
3316 		goto out;
3317 	} ) /* end DEB */
3318 
3319 	STm = &(STp->modes[STp->current_mode]);
3320 	STps = &(STp->ps[STp->partition]);
3321 
3322 	/*
3323 	 * If we are in the middle of error recovery, don't let anyone
3324 	 * else try and use this device.  Also, if error recovery fails, it
3325 	 * may try and take the device offline, in which case all further
3326 	 * access to the device is prohibited.
3327 	 */
3328 	retval = scsi_nonblockable_ioctl(STp->device, cmd_in, p,
3329 					file->f_flags & O_NDELAY);
3330 	if (!scsi_block_when_processing_errors(STp->device) || retval != -ENODEV)
3331 		goto out;
3332 	retval = 0;
3333 
3334 	cmd_type = _IOC_TYPE(cmd_in);
3335 	cmd_nr = _IOC_NR(cmd_in);
3336 
3337 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3338 		struct mtop mtc;
3339 
3340 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3341 			retval = (-EINVAL);
3342 			goto out;
3343 		}
3344 
3345 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3346 		if (i) {
3347 			retval = (-EFAULT);
3348 			goto out;
3349 		}
3350 
3351 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3352 			printk(KERN_WARNING
3353                                "%s: MTSETDRVBUFFER only allowed for root.\n", name);
3354 			retval = (-EPERM);
3355 			goto out;
3356 		}
3357 		if (!STm->defined &&
3358 		    (mtc.mt_op != MTSETDRVBUFFER &&
3359 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3360 			retval = (-ENXIO);
3361 			goto out;
3362 		}
3363 
3364 		if (!STp->pos_unknown) {
3365 
3366 			if (STps->eof == ST_FM_HIT) {
3367 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3368                                     mtc.mt_op == MTEOM) {
3369 					mtc.mt_count -= 1;
3370 					if (STps->drv_file >= 0)
3371 						STps->drv_file += 1;
3372 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3373 					mtc.mt_count += 1;
3374 					if (STps->drv_file >= 0)
3375 						STps->drv_file += 1;
3376 				}
3377 			}
3378 
3379 			if (mtc.mt_op == MTSEEK) {
3380 				/* Old position must be restored if partition will be
3381                                    changed */
3382 				i = !STp->can_partitions ||
3383 				    (STp->new_partition != STp->partition);
3384 			} else {
3385 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3386 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3387 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3388 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3389 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3390 				    mtc.mt_op == MTCOMPRESSION;
3391 			}
3392 			i = flush_buffer(STp, i);
3393 			if (i < 0) {
3394 				retval = i;
3395 				goto out;
3396 			}
3397 			if (STps->rw == ST_WRITING &&
3398 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3399 			     mtc.mt_op == MTSEEK ||
3400 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3401 				i = st_int_ioctl(STp, MTWEOF, 1);
3402 				if (i < 0) {
3403 					retval = i;
3404 					goto out;
3405 				}
3406 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3407 					mtc.mt_count++;
3408 				STps->rw = ST_IDLE;
3409 			     }
3410 
3411 		} else {
3412 			/*
3413 			 * If there was a bus reset, block further access
3414 			 * to this device.  If the user wants to rewind the tape,
3415 			 * then reset the flag and allow access again.
3416 			 */
3417 			if (mtc.mt_op != MTREW &&
3418 			    mtc.mt_op != MTOFFL &&
3419 			    mtc.mt_op != MTRETEN &&
3420 			    mtc.mt_op != MTERASE &&
3421 			    mtc.mt_op != MTSEEK &&
3422 			    mtc.mt_op != MTEOM) {
3423 				retval = (-EIO);
3424 				goto out;
3425 			}
3426 			reset_state(STp);
3427 			/* remove this when the midlevel properly clears was_reset */
3428 			STp->device->was_reset = 0;
3429 		}
3430 
3431 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3432 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3433 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3434 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3435 
3436 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3437 			do_door_lock(STp, 0);	/* Ignore result! */
3438 
3439 		if (mtc.mt_op == MTSETDRVBUFFER &&
3440 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3441 			retval = st_set_options(STp, mtc.mt_count);
3442 			goto out;
3443 		}
3444 
3445 		if (mtc.mt_op == MTSETPART) {
3446 			if (!STp->can_partitions ||
3447 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3448 				retval = (-EINVAL);
3449 				goto out;
3450 			}
3451 			if (mtc.mt_count >= STp->nbr_partitions &&
3452 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3453 				retval = (-EIO);
3454 				goto out;
3455 			}
3456 			if (mtc.mt_count >= STp->nbr_partitions) {
3457 				retval = (-EINVAL);
3458 				goto out;
3459 			}
3460 			STp->new_partition = mtc.mt_count;
3461 			retval = 0;
3462 			goto out;
3463 		}
3464 
3465 		if (mtc.mt_op == MTMKPART) {
3466 			if (!STp->can_partitions) {
3467 				retval = (-EINVAL);
3468 				goto out;
3469 			}
3470 			if ((i = st_int_ioctl(STp, MTREW, 0)) < 0 ||
3471 			    (i = partition_tape(STp, mtc.mt_count)) < 0) {
3472 				retval = i;
3473 				goto out;
3474 			}
3475 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3476 				STp->ps[i].rw = ST_IDLE;
3477 				STp->ps[i].at_sm = 0;
3478 				STp->ps[i].last_block_valid = 0;
3479 			}
3480 			STp->partition = STp->new_partition = 0;
3481 			STp->nbr_partitions = 1;	/* Bad guess ?-) */
3482 			STps->drv_block = STps->drv_file = 0;
3483 			retval = 0;
3484 			goto out;
3485 		}
3486 
3487 		if (mtc.mt_op == MTSEEK) {
3488 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3489 			if (!STp->can_partitions)
3490 				STp->ps[0].rw = ST_IDLE;
3491 			retval = i;
3492 			goto out;
3493 		}
3494 
3495 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3496 			retval = do_load_unload(STp, file, 0);
3497 			goto out;
3498 		}
3499 
3500 		if (mtc.mt_op == MTLOAD) {
3501 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3502 			goto out;
3503 		}
3504 
3505 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3506 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3507 			goto out;
3508 		}
3509 
3510 		if (STp->can_partitions && STp->ready == ST_READY &&
3511 		    (i = switch_partition(STp)) < 0) {
3512 			retval = i;
3513 			goto out;
3514 		}
3515 
3516 		if (mtc.mt_op == MTCOMPRESSION)
3517 			retval = st_compression(STp, (mtc.mt_count & 1));
3518 		else
3519 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3520 		goto out;
3521 	}
3522 	if (!STm->defined) {
3523 		retval = (-ENXIO);
3524 		goto out;
3525 	}
3526 
3527 	if ((i = flush_buffer(STp, 0)) < 0) {
3528 		retval = i;
3529 		goto out;
3530 	}
3531 	if (STp->can_partitions &&
3532 	    (i = switch_partition(STp)) < 0) {
3533 		retval = i;
3534 		goto out;
3535 	}
3536 
3537 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3538 		struct mtget mt_status;
3539 
3540 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3541 			 retval = (-EINVAL);
3542 			 goto out;
3543 		}
3544 
3545 		mt_status.mt_type = STp->tape_type;
3546 		mt_status.mt_dsreg =
3547 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3548 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3549 		mt_status.mt_blkno = STps->drv_block;
3550 		mt_status.mt_fileno = STps->drv_file;
3551 		if (STp->block_size != 0) {
3552 			if (STps->rw == ST_WRITING)
3553 				mt_status.mt_blkno +=
3554 				    (STp->buffer)->buffer_bytes / STp->block_size;
3555 			else if (STps->rw == ST_READING)
3556 				mt_status.mt_blkno -=
3557                                         ((STp->buffer)->buffer_bytes +
3558                                          STp->block_size - 1) / STp->block_size;
3559 		}
3560 
3561 		mt_status.mt_gstat = 0;
3562 		if (STp->drv_write_prot)
3563 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3564 		if (mt_status.mt_blkno == 0) {
3565 			if (mt_status.mt_fileno == 0)
3566 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3567 			else
3568 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3569 		}
3570 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3571 		mt_status.mt_resid = STp->partition;
3572 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3573 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3574 		else if (STps->eof >= ST_EOM_OK)
3575 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3576 		if (STp->density == 1)
3577 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3578 		else if (STp->density == 2)
3579 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3580 		else if (STp->density == 3)
3581 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3582 		if (STp->ready == ST_READY)
3583 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3584 		if (STp->ready == ST_NO_TAPE)
3585 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3586 		if (STps->at_sm)
3587 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3588 		if (STm->do_async_writes ||
3589                     (STm->do_buffer_writes && STp->block_size != 0) ||
3590 		    STp->drv_buffer != 0)
3591 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3592 		if (STp->cleaning_req)
3593 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3594 
3595 		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
3596 		if (i) {
3597 			retval = (-EFAULT);
3598 			goto out;
3599 		}
3600 
3601 		STp->recover_reg = 0;		/* Clear after read */
3602 		retval = 0;
3603 		goto out;
3604 	}			/* End of MTIOCGET */
3605 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3606 		struct mtpos mt_pos;
3607 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3608 			 retval = (-EINVAL);
3609 			 goto out;
3610 		}
3611 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3612 			retval = i;
3613 			goto out;
3614 		}
3615 		mt_pos.mt_blkno = blk;
3616 		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
3617 		if (i)
3618 			retval = (-EFAULT);
3619 		goto out;
3620 	}
3621 	mutex_unlock(&STp->lock);
3622 	switch (cmd_in) {
3623 		case SCSI_IOCTL_GET_IDLUN:
3624 		case SCSI_IOCTL_GET_BUS_NUMBER:
3625 			break;
3626 		default:
3627 			if ((cmd_in == SG_IO ||
3628 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3629 			     cmd_in == CDROM_SEND_PACKET) &&
3630 			    !capable(CAP_SYS_RAWIO))
3631 				i = -EPERM;
3632 			else
3633 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3634 						   file->f_mode, cmd_in, p);
3635 			if (i != -ENOTTY)
3636 				return i;
3637 			break;
3638 	}
3639 	retval = scsi_ioctl(STp->device, cmd_in, p);
3640 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3641 		STp->rew_at_close = 0;
3642 		STp->ready = ST_NO_TAPE;
3643 	}
3644 	return retval;
3645 
3646  out:
3647 	mutex_unlock(&STp->lock);
3648 	return retval;
3649 }
3650 
3651 #ifdef CONFIG_COMPAT
3652 static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3653 {
3654 	struct scsi_tape *STp = file->private_data;
3655 	struct scsi_device *sdev = STp->device;
3656 	int ret = -ENOIOCTLCMD;
3657 	if (sdev->host->hostt->compat_ioctl) {
3658 
3659 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
3660 
3661 	}
3662 	return ret;
3663 }
3664 #endif
3665 
3666 
3667 
3668 /* Try to allocate a new tape buffer. Calling function must not hold
3669    dev_arr_lock. */
3670 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3671 {
3672 	struct st_buffer *tb;
3673 
3674 	tb = kzalloc(sizeof(struct st_buffer), GFP_ATOMIC);
3675 	if (!tb) {
3676 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3677 		return NULL;
3678 	}
3679 	tb->frp_segs = 0;
3680 	tb->use_sg = max_sg;
3681 	tb->dma = need_dma;
3682 	tb->buffer_size = 0;
3683 
3684 	tb->reserved_pages = kzalloc(max_sg * sizeof(struct page *),
3685 				     GFP_ATOMIC);
3686 	if (!tb->reserved_pages) {
3687 		kfree(tb);
3688 		return NULL;
3689 	}
3690 
3691 	return tb;
3692 }
3693 
3694 
3695 /* Try to allocate enough space in the tape buffer */
3696 #define ST_MAX_ORDER 6
3697 
3698 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3699 {
3700 	int segs, nbr, max_segs, b_size, order, got;
3701 	gfp_t priority;
3702 
3703 	if (new_size <= STbuffer->buffer_size)
3704 		return 1;
3705 
3706 	if (STbuffer->buffer_size <= PAGE_SIZE)
3707 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3708 
3709 	max_segs = STbuffer->use_sg;
3710 	nbr = max_segs - STbuffer->frp_segs;
3711 	if (nbr <= 0)
3712 		return 0;
3713 
3714 	priority = GFP_KERNEL | __GFP_NOWARN;
3715 	if (need_dma)
3716 		priority |= GFP_DMA;
3717 
3718 	if (STbuffer->cleared)
3719 		priority |= __GFP_ZERO;
3720 
3721 	if (STbuffer->frp_segs) {
3722 		order = STbuffer->map_data.page_order;
3723 		b_size = PAGE_SIZE << order;
3724 	} else {
3725 		for (b_size = PAGE_SIZE, order = 0;
3726 		     order < ST_MAX_ORDER && b_size < new_size;
3727 		     order++, b_size *= 2)
3728 			;  /* empty */
3729 	}
3730 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3731 		if (order == ST_MAX_ORDER)
3732 			return 0;
3733 		normalize_buffer(STbuffer);
3734 		return enlarge_buffer(STbuffer, new_size, need_dma);
3735 	}
3736 
3737 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3738 	     segs < max_segs && got < new_size;) {
3739 		struct page *page;
3740 
3741 		page = alloc_pages(priority, order);
3742 		if (!page) {
3743 			DEB(STbuffer->buffer_size = got);
3744 			normalize_buffer(STbuffer);
3745 			return 0;
3746 		}
3747 
3748 		STbuffer->frp_segs += 1;
3749 		got += b_size;
3750 		STbuffer->buffer_size = got;
3751 		STbuffer->reserved_pages[segs] = page;
3752 		segs++;
3753 	}
3754 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3755 	STbuffer->map_data.page_order = order;
3756 
3757 	return 1;
3758 }
3759 
3760 
3761 /* Make sure that no data from previous user is in the internal buffer */
3762 static void clear_buffer(struct st_buffer * st_bp)
3763 {
3764 	int i;
3765 
3766 	for (i=0; i < st_bp->frp_segs; i++)
3767 		memset(page_address(st_bp->reserved_pages[i]), 0,
3768 		       PAGE_SIZE << st_bp->map_data.page_order);
3769 	st_bp->cleared = 1;
3770 }
3771 
3772 
3773 /* Release the extra buffer */
3774 static void normalize_buffer(struct st_buffer * STbuffer)
3775 {
3776 	int i, order = STbuffer->map_data.page_order;
3777 
3778 	for (i = 0; i < STbuffer->frp_segs; i++) {
3779 		__free_pages(STbuffer->reserved_pages[i], order);
3780 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3781 	}
3782 	STbuffer->frp_segs = 0;
3783 	STbuffer->sg_segs = 0;
3784 	STbuffer->map_data.page_order = 0;
3785 	STbuffer->map_data.offset = 0;
3786 }
3787 
3788 
3789 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3790    negative error code. */
3791 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3792 {
3793 	int i, cnt, res, offset;
3794 	int length = PAGE_SIZE << st_bp->map_data.page_order;
3795 
3796 	for (i = 0, offset = st_bp->buffer_bytes;
3797 	     i < st_bp->frp_segs && offset >= length; i++)
3798 		offset -= length;
3799 	if (i == st_bp->frp_segs) {	/* Should never happen */
3800 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
3801 		return (-EIO);
3802 	}
3803 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3804 		struct page *page = st_bp->reserved_pages[i];
3805 		cnt = length - offset < do_count ? length - offset : do_count;
3806 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
3807 		if (res)
3808 			return (-EFAULT);
3809 		do_count -= cnt;
3810 		st_bp->buffer_bytes += cnt;
3811 		ubp += cnt;
3812 		offset = 0;
3813 	}
3814 	if (do_count) /* Should never happen */
3815 		return (-EIO);
3816 
3817 	return 0;
3818 }
3819 
3820 
3821 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
3822    negative error code. */
3823 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
3824 {
3825 	int i, cnt, res, offset;
3826 	int length = PAGE_SIZE << st_bp->map_data.page_order;
3827 
3828 	for (i = 0, offset = st_bp->read_pointer;
3829 	     i < st_bp->frp_segs && offset >= length; i++)
3830 		offset -= length;
3831 	if (i == st_bp->frp_segs) {	/* Should never happen */
3832 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
3833 		return (-EIO);
3834 	}
3835 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3836 		struct page *page = st_bp->reserved_pages[i];
3837 		cnt = length - offset < do_count ? length - offset : do_count;
3838 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
3839 		if (res)
3840 			return (-EFAULT);
3841 		do_count -= cnt;
3842 		st_bp->buffer_bytes -= cnt;
3843 		st_bp->read_pointer += cnt;
3844 		ubp += cnt;
3845 		offset = 0;
3846 	}
3847 	if (do_count) /* Should never happen */
3848 		return (-EIO);
3849 
3850 	return 0;
3851 }
3852 
3853 
3854 /* Move data towards start of buffer */
3855 static void move_buffer_data(struct st_buffer * st_bp, int offset)
3856 {
3857 	int src_seg, dst_seg, src_offset = 0, dst_offset;
3858 	int count, total;
3859 	int length = PAGE_SIZE << st_bp->map_data.page_order;
3860 
3861 	if (offset == 0)
3862 		return;
3863 
3864 	total=st_bp->buffer_bytes - offset;
3865 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
3866 		src_offset = offset;
3867 		if (src_offset < length)
3868 			break;
3869 		offset -= length;
3870 	}
3871 
3872 	st_bp->buffer_bytes = st_bp->read_pointer = total;
3873 	for (dst_seg=dst_offset=0; total > 0; ) {
3874 		struct page *dpage = st_bp->reserved_pages[dst_seg];
3875 		struct page *spage = st_bp->reserved_pages[src_seg];
3876 
3877 		count = min(length - dst_offset, length - src_offset);
3878 		memmove(page_address(dpage) + dst_offset,
3879 			page_address(spage) + src_offset, count);
3880 		src_offset += count;
3881 		if (src_offset >= length) {
3882 			src_seg++;
3883 			src_offset = 0;
3884 		}
3885 		dst_offset += count;
3886 		if (dst_offset >= length) {
3887 			dst_seg++;
3888 			dst_offset = 0;
3889 		}
3890 		total -= count;
3891 	}
3892 }
3893 
3894 /* Validate the options from command line or module parameters */
3895 static void validate_options(void)
3896 {
3897 	if (buffer_kbs > 0)
3898 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
3899 	if (max_sg_segs >= ST_FIRST_SG)
3900 		st_max_sg_segs = max_sg_segs;
3901 }
3902 
3903 #ifndef MODULE
3904 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
3905  */
3906 static int __init st_setup(char *str)
3907 {
3908 	int i, len, ints[5];
3909 	char *stp;
3910 
3911 	stp = get_options(str, ARRAY_SIZE(ints), ints);
3912 
3913 	if (ints[0] > 0) {
3914 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
3915 			if (parms[i].val)
3916 				*parms[i].val = ints[i + 1];
3917 	} else {
3918 		while (stp != NULL) {
3919 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
3920 				len = strlen(parms[i].name);
3921 				if (!strncmp(stp, parms[i].name, len) &&
3922 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
3923 					if (parms[i].val)
3924 						*parms[i].val =
3925 							simple_strtoul(stp + len + 1, NULL, 0);
3926 					else
3927 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
3928 						       parms[i].name);
3929 					break;
3930 				}
3931 			}
3932 			if (i >= ARRAY_SIZE(parms))
3933 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
3934 					stp);
3935 			stp = strchr(stp, ',');
3936 			if (stp)
3937 				stp++;
3938 		}
3939 	}
3940 
3941 	validate_options();
3942 
3943 	return 1;
3944 }
3945 
3946 __setup("st=", st_setup);
3947 
3948 #endif
3949 
3950 static const struct file_operations st_fops =
3951 {
3952 	.owner =	THIS_MODULE,
3953 	.read =		st_read,
3954 	.write =	st_write,
3955 	.unlocked_ioctl = st_ioctl,
3956 #ifdef CONFIG_COMPAT
3957 	.compat_ioctl = st_compat_ioctl,
3958 #endif
3959 	.open =		st_open,
3960 	.flush =	st_flush,
3961 	.release =	st_release,
3962 };
3963 
3964 static int st_probe(struct device *dev)
3965 {
3966 	struct scsi_device *SDp = to_scsi_device(dev);
3967 	struct gendisk *disk = NULL;
3968 	struct cdev *cdev = NULL;
3969 	struct scsi_tape *tpnt = NULL;
3970 	struct st_modedef *STm;
3971 	struct st_partstat *STps;
3972 	struct st_buffer *buffer;
3973 	int i, j, mode, dev_num, error;
3974 	char *stp;
3975 
3976 	if (SDp->type != TYPE_TAPE)
3977 		return -ENODEV;
3978 	if ((stp = st_incompatible(SDp))) {
3979 		sdev_printk(KERN_INFO, SDp, "Found incompatible tape\n");
3980 		printk(KERN_INFO "st: The suggested driver is %s.\n", stp);
3981 		return -ENODEV;
3982 	}
3983 
3984 	i = min(queue_max_hw_segments(SDp->request_queue),
3985 		queue_max_phys_segments(SDp->request_queue));
3986 	if (st_max_sg_segs < i)
3987 		i = st_max_sg_segs;
3988 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
3989 	if (buffer == NULL) {
3990 		printk(KERN_ERR
3991 		       "st: Can't allocate new tape buffer. Device not attached.\n");
3992 		goto out;
3993 	}
3994 
3995 	disk = alloc_disk(1);
3996 	if (!disk) {
3997 		printk(KERN_ERR "st: out of memory. Device not attached.\n");
3998 		goto out_buffer_free;
3999 	}
4000 
4001 	write_lock(&st_dev_arr_lock);
4002 	if (st_nr_dev >= st_dev_max) {
4003 		struct scsi_tape **tmp_da;
4004 		int tmp_dev_max;
4005 
4006 		tmp_dev_max = max(st_nr_dev * 2, 8);
4007 		if (tmp_dev_max > ST_MAX_TAPES)
4008 			tmp_dev_max = ST_MAX_TAPES;
4009 		if (tmp_dev_max <= st_nr_dev) {
4010 			write_unlock(&st_dev_arr_lock);
4011 			printk(KERN_ERR "st: Too many tape devices (max. %d).\n",
4012 			       ST_MAX_TAPES);
4013 			goto out_put_disk;
4014 		}
4015 
4016 		tmp_da = kzalloc(tmp_dev_max * sizeof(struct scsi_tape *), GFP_ATOMIC);
4017 		if (tmp_da == NULL) {
4018 			write_unlock(&st_dev_arr_lock);
4019 			printk(KERN_ERR "st: Can't extend device array.\n");
4020 			goto out_put_disk;
4021 		}
4022 
4023 		if (scsi_tapes != NULL) {
4024 			memcpy(tmp_da, scsi_tapes,
4025 			       st_dev_max * sizeof(struct scsi_tape *));
4026 			kfree(scsi_tapes);
4027 		}
4028 		scsi_tapes = tmp_da;
4029 
4030 		st_dev_max = tmp_dev_max;
4031 	}
4032 
4033 	for (i = 0; i < st_dev_max; i++)
4034 		if (scsi_tapes[i] == NULL)
4035 			break;
4036 	if (i >= st_dev_max)
4037 		panic("scsi_devices corrupt (st)");
4038 
4039 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
4040 	if (tpnt == NULL) {
4041 		write_unlock(&st_dev_arr_lock);
4042 		printk(KERN_ERR "st: Can't allocate device descriptor.\n");
4043 		goto out_put_disk;
4044 	}
4045 	kref_init(&tpnt->kref);
4046 	tpnt->disk = disk;
4047 	sprintf(disk->disk_name, "st%d", i);
4048 	disk->private_data = &tpnt->driver;
4049 	disk->queue = SDp->request_queue;
4050 	tpnt->driver = &st_template;
4051 	scsi_tapes[i] = tpnt;
4052 	dev_num = i;
4053 
4054 	tpnt->device = SDp;
4055 	if (SDp->scsi_level <= 2)
4056 		tpnt->tape_type = MT_ISSCSI1;
4057 	else
4058 		tpnt->tape_type = MT_ISSCSI2;
4059 
4060 	tpnt->buffer = buffer;
4061 	tpnt->buffer->last_SRpnt = NULL;
4062 
4063 	tpnt->inited = 0;
4064 	tpnt->dirty = 0;
4065 	tpnt->in_use = 0;
4066 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4067 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4068 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4069 	tpnt->density = 0;
4070 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4071 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4072 	tpnt->can_partitions = 0;
4073 	tpnt->two_fm = ST_TWO_FM;
4074 	tpnt->fast_mteom = ST_FAST_MTEOM;
4075 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4076 	tpnt->sili = ST_SILI;
4077 	tpnt->immediate = ST_NOWAIT;
4078 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4079 	tpnt->partition = 0;
4080 	tpnt->new_partition = 0;
4081 	tpnt->nbr_partitions = 0;
4082 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4083 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4084 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4085 
4086 	for (i = 0; i < ST_NBR_MODES; i++) {
4087 		STm = &(tpnt->modes[i]);
4088 		STm->defined = 0;
4089 		STm->sysv = ST_SYSV;
4090 		STm->defaults_for_writes = 0;
4091 		STm->do_async_writes = ST_ASYNC_WRITES;
4092 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4093 		STm->do_read_ahead = ST_READ_AHEAD;
4094 		STm->default_compression = ST_DONT_TOUCH;
4095 		STm->default_blksize = (-1);	/* No forced size */
4096 		STm->default_density = (-1);	/* No forced density */
4097 	}
4098 
4099 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4100 		STps = &(tpnt->ps[i]);
4101 		STps->rw = ST_IDLE;
4102 		STps->eof = ST_NOEOF;
4103 		STps->at_sm = 0;
4104 		STps->last_block_valid = 0;
4105 		STps->drv_block = (-1);
4106 		STps->drv_file = (-1);
4107 	}
4108 
4109 	tpnt->current_mode = 0;
4110 	tpnt->modes[0].defined = 1;
4111 
4112 	tpnt->density_changed = tpnt->compression_changed =
4113 	    tpnt->blksize_changed = 0;
4114 	mutex_init(&tpnt->lock);
4115 
4116 	st_nr_dev++;
4117 	write_unlock(&st_dev_arr_lock);
4118 
4119 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4120 		STm = &(tpnt->modes[mode]);
4121 		for (j=0; j < 2; j++) {
4122 			cdev = cdev_alloc();
4123 			if (!cdev) {
4124 				printk(KERN_ERR
4125 				       "st%d: out of memory. Device not attached.\n",
4126 				       dev_num);
4127 				goto out_free_tape;
4128 			}
4129 			cdev->owner = THIS_MODULE;
4130 			cdev->ops = &st_fops;
4131 
4132 			error = cdev_add(cdev,
4133 					 MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, j)),
4134 					 1);
4135 			if (error) {
4136 				printk(KERN_ERR "st%d: Can't add %s-rewind mode %d\n",
4137 				       dev_num, j ? "non" : "auto", mode);
4138 				printk(KERN_ERR "st%d: Device not attached.\n", dev_num);
4139 				goto out_free_tape;
4140 			}
4141 			STm->cdevs[j] = cdev;
4142 
4143 		}
4144 		error = do_create_class_files(tpnt, dev_num, mode);
4145 		if (error)
4146 			goto out_free_tape;
4147 	}
4148 
4149 	sdev_printk(KERN_NOTICE, SDp,
4150 		    "Attached scsi tape %s\n", tape_name(tpnt));
4151 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4152 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4153 		    queue_dma_alignment(SDp->request_queue) + 1);
4154 
4155 	return 0;
4156 
4157 out_free_tape:
4158 	for (mode=0; mode < ST_NBR_MODES; mode++) {
4159 		STm = &(tpnt->modes[mode]);
4160 		sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
4161 				  "tape");
4162 		for (j=0; j < 2; j++) {
4163 			if (STm->cdevs[j]) {
4164 				if (cdev == STm->cdevs[j])
4165 					cdev = NULL;
4166 					device_destroy(st_sysfs_class,
4167 						       MKDEV(SCSI_TAPE_MAJOR,
4168 							     TAPE_MINOR(i, mode, j)));
4169 				cdev_del(STm->cdevs[j]);
4170 			}
4171 		}
4172 	}
4173 	if (cdev)
4174 		cdev_del(cdev);
4175 	write_lock(&st_dev_arr_lock);
4176 	scsi_tapes[dev_num] = NULL;
4177 	st_nr_dev--;
4178 	write_unlock(&st_dev_arr_lock);
4179 out_put_disk:
4180 	put_disk(disk);
4181 	kfree(tpnt);
4182 out_buffer_free:
4183 	kfree(buffer);
4184 out:
4185 	return -ENODEV;
4186 };
4187 
4188 
4189 static int st_remove(struct device *dev)
4190 {
4191 	struct scsi_device *SDp = to_scsi_device(dev);
4192 	struct scsi_tape *tpnt;
4193 	int i, j, mode;
4194 
4195 	write_lock(&st_dev_arr_lock);
4196 	for (i = 0; i < st_dev_max; i++) {
4197 		tpnt = scsi_tapes[i];
4198 		if (tpnt != NULL && tpnt->device == SDp) {
4199 			scsi_tapes[i] = NULL;
4200 			st_nr_dev--;
4201 			write_unlock(&st_dev_arr_lock);
4202 			sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
4203 					  "tape");
4204 			for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4205 				for (j=0; j < 2; j++) {
4206 					device_destroy(st_sysfs_class,
4207 						       MKDEV(SCSI_TAPE_MAJOR,
4208 							     TAPE_MINOR(i, mode, j)));
4209 					cdev_del(tpnt->modes[mode].cdevs[j]);
4210 					tpnt->modes[mode].cdevs[j] = NULL;
4211 				}
4212 			}
4213 
4214 			mutex_lock(&st_ref_mutex);
4215 			kref_put(&tpnt->kref, scsi_tape_release);
4216 			mutex_unlock(&st_ref_mutex);
4217 			return 0;
4218 		}
4219 	}
4220 
4221 	write_unlock(&st_dev_arr_lock);
4222 	return 0;
4223 }
4224 
4225 /**
4226  *      scsi_tape_release - Called to free the Scsi_Tape structure
4227  *      @kref: pointer to embedded kref
4228  *
4229  *      st_ref_mutex must be held entering this routine.  Because it is
4230  *      called on last put, you should always use the scsi_tape_get()
4231  *      scsi_tape_put() helpers which manipulate the semaphore directly
4232  *      and never do a direct kref_put().
4233  **/
4234 static void scsi_tape_release(struct kref *kref)
4235 {
4236 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4237 	struct gendisk *disk = tpnt->disk;
4238 
4239 	tpnt->device = NULL;
4240 
4241 	if (tpnt->buffer) {
4242 		normalize_buffer(tpnt->buffer);
4243 		kfree(tpnt->buffer->reserved_pages);
4244 		kfree(tpnt->buffer);
4245 	}
4246 
4247 	disk->private_data = NULL;
4248 	put_disk(disk);
4249 	kfree(tpnt);
4250 	return;
4251 }
4252 
4253 static int __init init_st(void)
4254 {
4255 	int err;
4256 
4257 	validate_options();
4258 
4259 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4260 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4261 
4262 	st_sysfs_class = class_create(THIS_MODULE, "scsi_tape");
4263 	if (IS_ERR(st_sysfs_class)) {
4264 		printk(KERN_ERR "Unable create sysfs class for SCSI tapes\n");
4265 		return PTR_ERR(st_sysfs_class);
4266 	}
4267 
4268 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4269 				     ST_MAX_TAPE_ENTRIES, "st");
4270 	if (err) {
4271 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4272 		       SCSI_TAPE_MAJOR);
4273 		goto err_class;
4274 	}
4275 
4276 	err = scsi_register_driver(&st_template.gendrv);
4277 	if (err)
4278 		goto err_chrdev;
4279 
4280 	err = do_create_sysfs_files();
4281 	if (err)
4282 		goto err_scsidrv;
4283 
4284 	return 0;
4285 
4286 err_scsidrv:
4287 	scsi_unregister_driver(&st_template.gendrv);
4288 err_chrdev:
4289 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4290 				 ST_MAX_TAPE_ENTRIES);
4291 err_class:
4292 	class_destroy(st_sysfs_class);
4293 	return err;
4294 }
4295 
4296 static void __exit exit_st(void)
4297 {
4298 	do_remove_sysfs_files();
4299 	scsi_unregister_driver(&st_template.gendrv);
4300 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4301 				 ST_MAX_TAPE_ENTRIES);
4302 	class_destroy(st_sysfs_class);
4303 	kfree(scsi_tapes);
4304 	printk(KERN_INFO "st: Unloaded.\n");
4305 }
4306 
4307 module_init(init_st);
4308 module_exit(exit_st);
4309 
4310 
4311 /* The sysfs driver interface. Read-only at the moment */
4312 static ssize_t st_try_direct_io_show(struct device_driver *ddp, char *buf)
4313 {
4314 	return snprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4315 }
4316 static DRIVER_ATTR(try_direct_io, S_IRUGO, st_try_direct_io_show, NULL);
4317 
4318 static ssize_t st_fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4319 {
4320 	return snprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4321 }
4322 static DRIVER_ATTR(fixed_buffer_size, S_IRUGO, st_fixed_buffer_size_show, NULL);
4323 
4324 static ssize_t st_max_sg_segs_show(struct device_driver *ddp, char *buf)
4325 {
4326 	return snprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4327 }
4328 static DRIVER_ATTR(max_sg_segs, S_IRUGO, st_max_sg_segs_show, NULL);
4329 
4330 static ssize_t st_version_show(struct device_driver *ddd, char *buf)
4331 {
4332 	return snprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4333 }
4334 static DRIVER_ATTR(version, S_IRUGO, st_version_show, NULL);
4335 
4336 static int do_create_sysfs_files(void)
4337 {
4338 	struct device_driver *sysfs = &st_template.gendrv;
4339 	int err;
4340 
4341 	err = driver_create_file(sysfs, &driver_attr_try_direct_io);
4342 	if (err)
4343 		return err;
4344 	err = driver_create_file(sysfs, &driver_attr_fixed_buffer_size);
4345 	if (err)
4346 		goto err_try_direct_io;
4347 	err = driver_create_file(sysfs, &driver_attr_max_sg_segs);
4348 	if (err)
4349 		goto err_attr_fixed_buf;
4350 	err = driver_create_file(sysfs, &driver_attr_version);
4351 	if (err)
4352 		goto err_attr_max_sg;
4353 
4354 	return 0;
4355 
4356 err_attr_max_sg:
4357 	driver_remove_file(sysfs, &driver_attr_max_sg_segs);
4358 err_attr_fixed_buf:
4359 	driver_remove_file(sysfs, &driver_attr_fixed_buffer_size);
4360 err_try_direct_io:
4361 	driver_remove_file(sysfs, &driver_attr_try_direct_io);
4362 	return err;
4363 }
4364 
4365 static void do_remove_sysfs_files(void)
4366 {
4367 	struct device_driver *sysfs = &st_template.gendrv;
4368 
4369 	driver_remove_file(sysfs, &driver_attr_version);
4370 	driver_remove_file(sysfs, &driver_attr_max_sg_segs);
4371 	driver_remove_file(sysfs, &driver_attr_fixed_buffer_size);
4372 	driver_remove_file(sysfs, &driver_attr_try_direct_io);
4373 }
4374 
4375 
4376 /* The sysfs simple class interface */
4377 static ssize_t
4378 st_defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4379 {
4380 	struct st_modedef *STm = dev_get_drvdata(dev);
4381 	ssize_t l = 0;
4382 
4383 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4384 	return l;
4385 }
4386 
4387 DEVICE_ATTR(defined, S_IRUGO, st_defined_show, NULL);
4388 
4389 static ssize_t
4390 st_defblk_show(struct device *dev, struct device_attribute *attr, char *buf)
4391 {
4392 	struct st_modedef *STm = dev_get_drvdata(dev);
4393 	ssize_t l = 0;
4394 
4395 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4396 	return l;
4397 }
4398 
4399 DEVICE_ATTR(default_blksize, S_IRUGO, st_defblk_show, NULL);
4400 
4401 static ssize_t
4402 st_defdensity_show(struct device *dev, struct device_attribute *attr, char *buf)
4403 {
4404 	struct st_modedef *STm = dev_get_drvdata(dev);
4405 	ssize_t l = 0;
4406 	char *fmt;
4407 
4408 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4409 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4410 	return l;
4411 }
4412 
4413 DEVICE_ATTR(default_density, S_IRUGO, st_defdensity_show, NULL);
4414 
4415 static ssize_t
4416 st_defcompression_show(struct device *dev, struct device_attribute *attr,
4417 		       char *buf)
4418 {
4419 	struct st_modedef *STm = dev_get_drvdata(dev);
4420 	ssize_t l = 0;
4421 
4422 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4423 	return l;
4424 }
4425 
4426 DEVICE_ATTR(default_compression, S_IRUGO, st_defcompression_show, NULL);
4427 
4428 static ssize_t
4429 st_options_show(struct device *dev, struct device_attribute *attr, char *buf)
4430 {
4431 	struct st_modedef *STm = dev_get_drvdata(dev);
4432 	struct scsi_tape *STp;
4433 	int i, j, options;
4434 	ssize_t l = 0;
4435 
4436 	for (i=0; i < st_dev_max; i++) {
4437 		for (j=0; j < ST_NBR_MODES; j++)
4438 			if (&scsi_tapes[i]->modes[j] == STm)
4439 				break;
4440 		if (j < ST_NBR_MODES)
4441 			break;
4442 	}
4443 	if (i == st_dev_max)
4444 		return 0;  /* should never happen */
4445 
4446 	STp = scsi_tapes[i];
4447 
4448 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4449 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4450 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4451 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4452 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4453 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4454 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4455 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4456 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4457 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4458 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4459 	options |= STm->sysv ? MT_ST_SYSV : 0;
4460 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4461 	options |= STp->sili ? MT_ST_SILI : 0;
4462 
4463 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4464 	return l;
4465 }
4466 
4467 DEVICE_ATTR(options, S_IRUGO, st_options_show, NULL);
4468 
4469 static int do_create_class_files(struct scsi_tape *STp, int dev_num, int mode)
4470 {
4471 	int i, rew, error;
4472 	char name[10];
4473 	struct device *st_class_member;
4474 
4475 	for (rew=0; rew < 2; rew++) {
4476 		/* Make sure that the minor numbers corresponding to the four
4477 		   first modes always get the same names */
4478 		i = mode << (4 - ST_NBR_MODE_BITS);
4479 		snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4480 			 STp->disk->disk_name, st_formats[i]);
4481 		st_class_member =
4482 			device_create(st_sysfs_class, &STp->device->sdev_gendev,
4483 				      MKDEV(SCSI_TAPE_MAJOR,
4484 					    TAPE_MINOR(dev_num, mode, rew)),
4485 				      &STp->modes[mode], "%s", name);
4486 		if (IS_ERR(st_class_member)) {
4487 			printk(KERN_WARNING "st%d: device_create failed\n",
4488 			       dev_num);
4489 			error = PTR_ERR(st_class_member);
4490 			goto out;
4491 		}
4492 
4493 		error = device_create_file(st_class_member,
4494 					   &dev_attr_defined);
4495 		if (error) goto out;
4496 		error = device_create_file(st_class_member,
4497 					   &dev_attr_default_blksize);
4498 		if (error) goto out;
4499 		error = device_create_file(st_class_member,
4500 					   &dev_attr_default_density);
4501 		if (error) goto out;
4502 		error = device_create_file(st_class_member,
4503 					   &dev_attr_default_compression);
4504 		if (error) goto out;
4505 		error = device_create_file(st_class_member,
4506 					   &dev_attr_options);
4507 		if (error) goto out;
4508 
4509 		if (mode == 0 && rew == 0) {
4510 			error = sysfs_create_link(&STp->device->sdev_gendev.kobj,
4511 						  &st_class_member->kobj,
4512 						  "tape");
4513 			if (error) {
4514 				printk(KERN_ERR
4515 				       "st%d: Can't create sysfs link from SCSI device.\n",
4516 				       dev_num);
4517 				goto out;
4518 			}
4519 		}
4520 	}
4521 
4522 	return 0;
4523 
4524 out:
4525 	return error;
4526 }
4527 
4528 /* The following functions may be useful for a larger audience. */
4529 static int sgl_map_user_pages(struct st_buffer *STbp,
4530 			      const unsigned int max_pages, unsigned long uaddr,
4531 			      size_t count, int rw)
4532 {
4533 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4534 	unsigned long start = uaddr >> PAGE_SHIFT;
4535 	const int nr_pages = end - start;
4536 	int res, i, j;
4537 	struct page **pages;
4538 	struct rq_map_data *mdata = &STbp->map_data;
4539 
4540 	/* User attempted Overflow! */
4541 	if ((uaddr + count) < uaddr)
4542 		return -EINVAL;
4543 
4544 	/* Too big */
4545         if (nr_pages > max_pages)
4546 		return -ENOMEM;
4547 
4548 	/* Hmm? */
4549 	if (count == 0)
4550 		return 0;
4551 
4552 	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
4553 		return -ENOMEM;
4554 
4555         /* Try to fault in all of the necessary pages */
4556 	down_read(&current->mm->mmap_sem);
4557         /* rw==READ means read from drive, write into memory area */
4558 	res = get_user_pages(
4559 		current,
4560 		current->mm,
4561 		uaddr,
4562 		nr_pages,
4563 		rw == READ,
4564 		0, /* don't force */
4565 		pages,
4566 		NULL);
4567 	up_read(&current->mm->mmap_sem);
4568 
4569 	/* Errors and no page mapped should return here */
4570 	if (res < nr_pages)
4571 		goto out_unmap;
4572 
4573         for (i=0; i < nr_pages; i++) {
4574                 /* FIXME: flush superflous for rw==READ,
4575                  * probably wrong function for rw==WRITE
4576                  */
4577 		flush_dcache_page(pages[i]);
4578         }
4579 
4580 	mdata->offset = uaddr & ~PAGE_MASK;
4581 	mdata->page_order = 0;
4582 	STbp->mapped_pages = pages;
4583 
4584 	return nr_pages;
4585  out_unmap:
4586 	if (res > 0) {
4587 		for (j=0; j < res; j++)
4588 			page_cache_release(pages[j]);
4589 		res = 0;
4590 	}
4591 	kfree(pages);
4592 	return res;
4593 }
4594 
4595 
4596 /* And unmap them... */
4597 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4598 				const unsigned int nr_pages, int dirtied)
4599 {
4600 	int i;
4601 
4602 	for (i=0; i < nr_pages; i++) {
4603 		struct page *page = STbp->mapped_pages[i];
4604 
4605 		if (dirtied)
4606 			SetPageDirty(page);
4607 		/* FIXME: cache flush missing for rw==READ
4608 		 * FIXME: call the correct reference counting function
4609 		 */
4610 		page_cache_release(page);
4611 	}
4612 	kfree(STbp->mapped_pages);
4613 	STbp->mapped_pages = NULL;
4614 
4615 	return 0;
4616 }
4617