xref: /linux/drivers/scsi/st.c (revision 5a116dd2797677cad48fee2f42267e3cb69f5502)
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 && value >= SCSI_SENSE_BUFFERSIZE)
2284 			return (-EINVAL);
2285 		STp->cln_mode = value;
2286 		STp->cln_sense_mask = (options >> 8) & 0xff;
2287 		STp->cln_sense_value = (options >> 16) & 0xff;
2288 		printk(KERN_INFO
2289 		       "%s: Cleaning request mode %d, mask %02x, value %02x\n",
2290 		       name, value, STp->cln_sense_mask, STp->cln_sense_value);
2291 	} else if (code == MT_ST_DEF_OPTIONS) {
2292 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2293 		value = (options & MT_ST_CLEAR_DEFAULT);
2294 		if (code == MT_ST_DEF_DENSITY) {
2295 			if (value == MT_ST_CLEAR_DEFAULT) {
2296 				STm->default_density = (-1);
2297 				DEBC( printk(KERN_INFO "%s: Density default disabled.\n",
2298                                        name));
2299 			} else {
2300 				STm->default_density = value & 0xff;
2301 				DEBC( printk(KERN_INFO "%s: Density default set to %x\n",
2302 				       name, STm->default_density));
2303 				if (STp->ready == ST_READY) {
2304 					STp->density_changed = 0;
2305 					set_mode_densblk(STp, STm);
2306 				}
2307 			}
2308 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2309 			if (value == MT_ST_CLEAR_DEFAULT) {
2310 				STp->default_drvbuffer = 0xff;
2311 				DEBC( printk(KERN_INFO
2312                                        "%s: Drive buffer default disabled.\n", name));
2313 			} else {
2314 				STp->default_drvbuffer = value & 7;
2315 				DEBC( printk(KERN_INFO
2316                                        "%s: Drive buffer default set to %x\n",
2317 				       name, STp->default_drvbuffer));
2318 				if (STp->ready == ST_READY)
2319 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2320 			}
2321 		} else if (code == MT_ST_DEF_COMPRESSION) {
2322 			if (value == MT_ST_CLEAR_DEFAULT) {
2323 				STm->default_compression = ST_DONT_TOUCH;
2324 				DEBC( printk(KERN_INFO
2325                                        "%s: Compression default disabled.\n", name));
2326 			} else {
2327 				if ((value & 0xff00) != 0) {
2328 					STp->c_algo = (value & 0xff00) >> 8;
2329 					DEBC( printk(KERN_INFO "%s: Compression algorithm set to 0x%x.\n",
2330 					       name, STp->c_algo));
2331 				}
2332 				if ((value & 0xff) != 0xff) {
2333 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2334 					DEBC( printk(KERN_INFO "%s: Compression default set to %x\n",
2335 					       name, (value & 1)));
2336 					if (STp->ready == ST_READY) {
2337 						STp->compression_changed = 0;
2338 						st_compression(STp, (STm->default_compression == ST_YES));
2339 					}
2340 				}
2341 			}
2342 		}
2343 	} else
2344 		return (-EIO);
2345 
2346 	return 0;
2347 }
2348 
2349 #define MODE_HEADER_LENGTH  4
2350 
2351 /* Mode header and page byte offsets */
2352 #define MH_OFF_DATA_LENGTH     0
2353 #define MH_OFF_MEDIUM_TYPE     1
2354 #define MH_OFF_DEV_SPECIFIC    2
2355 #define MH_OFF_BDESCS_LENGTH   3
2356 #define MP_OFF_PAGE_NBR        0
2357 #define MP_OFF_PAGE_LENGTH     1
2358 
2359 /* Mode header and page bit masks */
2360 #define MH_BIT_WP              0x80
2361 #define MP_MSK_PAGE_NBR        0x3f
2362 
2363 /* Don't return block descriptors */
2364 #define MODE_SENSE_OMIT_BDESCS 0x08
2365 
2366 #define MODE_SELECT_PAGE_FORMAT 0x10
2367 
2368 /* Read a mode page into the tape buffer. The block descriptors are included
2369    if incl_block_descs is true. The page control is ored to the page number
2370    parameter, if necessary. */
2371 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2372 {
2373 	unsigned char cmd[MAX_COMMAND_SIZE];
2374 	struct st_request *SRpnt;
2375 
2376 	memset(cmd, 0, MAX_COMMAND_SIZE);
2377 	cmd[0] = MODE_SENSE;
2378 	if (omit_block_descs)
2379 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2380 	cmd[2] = page;
2381 	cmd[4] = 255;
2382 
2383 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2384 			   STp->device->request_queue->rq_timeout, 0, 1);
2385 	if (SRpnt == NULL)
2386 		return (STp->buffer)->syscall_result;
2387 
2388 	st_release_request(SRpnt);
2389 
2390 	return STp->buffer->syscall_result;
2391 }
2392 
2393 
2394 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2395    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2396 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2397 {
2398 	int pgo;
2399 	unsigned char cmd[MAX_COMMAND_SIZE];
2400 	struct st_request *SRpnt;
2401 	int timeout;
2402 
2403 	memset(cmd, 0, MAX_COMMAND_SIZE);
2404 	cmd[0] = MODE_SELECT;
2405 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2406 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2407 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2408 
2409 	/* Clear reserved fields */
2410 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2411 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2412 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2413 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2414 
2415 	timeout = slow ?
2416 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2417 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2418 			   timeout, 0, 1);
2419 	if (SRpnt == NULL)
2420 		return (STp->buffer)->syscall_result;
2421 
2422 	st_release_request(SRpnt);
2423 
2424 	return STp->buffer->syscall_result;
2425 }
2426 
2427 
2428 #define COMPRESSION_PAGE        0x0f
2429 #define COMPRESSION_PAGE_LENGTH 16
2430 
2431 #define CP_OFF_DCE_DCC          2
2432 #define CP_OFF_C_ALGO           7
2433 
2434 #define DCE_MASK  0x80
2435 #define DCC_MASK  0x40
2436 #define RED_MASK  0x60
2437 
2438 
2439 /* Control the compression with mode page 15. Algorithm not changed if zero.
2440 
2441    The block descriptors are read and written because Sony SDT-7000 does not
2442    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2443    Including block descriptors should not cause any harm to other drives. */
2444 
2445 static int st_compression(struct scsi_tape * STp, int state)
2446 {
2447 	int retval;
2448 	int mpoffs;  /* Offset to mode page start */
2449 	unsigned char *b_data = (STp->buffer)->b_data;
2450 	DEB( char *name = tape_name(STp); )
2451 
2452 	if (STp->ready != ST_READY)
2453 		return (-EIO);
2454 
2455 	/* Read the current page contents */
2456 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2457 	if (retval) {
2458                 DEBC(printk(ST_DEB_MSG "%s: Compression mode page not supported.\n",
2459                             name));
2460 		return (-EIO);
2461 	}
2462 
2463 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2464         DEBC(printk(ST_DEB_MSG "%s: Compression state is %d.\n", name,
2465                     (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0)));
2466 
2467 	/* Check if compression can be changed */
2468 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2469                 DEBC(printk(ST_DEB_MSG "%s: Compression not supported.\n", name));
2470 		return (-EIO);
2471 	}
2472 
2473 	/* Do the change */
2474 	if (state) {
2475 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2476 		if (STp->c_algo != 0)
2477 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2478 	}
2479 	else {
2480 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2481 		if (STp->c_algo != 0)
2482 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2483 	}
2484 
2485 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2486 	if (retval) {
2487                 DEBC(printk(ST_DEB_MSG "%s: Compression change failed.\n", name));
2488 		return (-EIO);
2489 	}
2490         DEBC(printk(ST_DEB_MSG "%s: Compression state changed to %d.\n",
2491 		       name, state));
2492 
2493 	STp->compression_changed = 1;
2494 	return 0;
2495 }
2496 
2497 
2498 /* Process the load and unload commands (does unload if the load code is zero) */
2499 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2500 {
2501 	int retval = (-EIO), timeout;
2502 	DEB( char *name = tape_name(STp); )
2503 	unsigned char cmd[MAX_COMMAND_SIZE];
2504 	struct st_partstat *STps;
2505 	struct st_request *SRpnt;
2506 
2507 	if (STp->ready != ST_READY && !load_code) {
2508 		if (STp->ready == ST_NO_TAPE)
2509 			return (-ENOMEDIUM);
2510 		else
2511 			return (-EIO);
2512 	}
2513 
2514 	memset(cmd, 0, MAX_COMMAND_SIZE);
2515 	cmd[0] = START_STOP;
2516 	if (load_code)
2517 		cmd[4] |= 1;
2518 	/*
2519 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2520 	 */
2521 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2522 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2523 		DEBC(printk(ST_DEB_MSG "%s: Enhanced %sload slot %2d.\n",
2524 			    name, (cmd[4]) ? "" : "un",
2525 			    load_code - MT_ST_HPLOADER_OFFSET));
2526 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2527 	}
2528 	if (STp->immediate) {
2529 		cmd[1] = 1;	/* Don't wait for completion */
2530 		timeout = STp->device->request_queue->rq_timeout;
2531 	}
2532 	else
2533 		timeout = STp->long_timeout;
2534 
2535 	DEBC(
2536 		if (!load_code)
2537 		printk(ST_DEB_MSG "%s: Unloading tape.\n", name);
2538 		else
2539 		printk(ST_DEB_MSG "%s: Loading tape.\n", name);
2540 		);
2541 
2542 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2543 			   timeout, MAX_RETRIES, 1);
2544 	if (!SRpnt)
2545 		return (STp->buffer)->syscall_result;
2546 
2547 	retval = (STp->buffer)->syscall_result;
2548 	st_release_request(SRpnt);
2549 
2550 	if (!retval) {	/* SCSI command successful */
2551 
2552 		if (!load_code) {
2553 			STp->rew_at_close = 0;
2554 			STp->ready = ST_NO_TAPE;
2555 		}
2556 		else {
2557 			STp->rew_at_close = STp->autorew_dev;
2558 			retval = check_tape(STp, filp);
2559 			if (retval > 0)
2560 				retval = 0;
2561 		}
2562 	}
2563 	else {
2564 		STps = &(STp->ps[STp->partition]);
2565 		STps->drv_file = STps->drv_block = (-1);
2566 	}
2567 
2568 	return retval;
2569 }
2570 
2571 #if DEBUG
2572 #define ST_DEB_FORWARD  0
2573 #define ST_DEB_BACKWARD 1
2574 static void deb_space_print(char *name, int direction, char *units, unsigned char *cmd)
2575 {
2576 	s32 sc;
2577 
2578 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2579 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2580 	if (direction)
2581 		sc = -sc;
2582 	printk(ST_DEB_MSG "%s: Spacing tape %s over %d %s.\n", name,
2583 	       direction ? "backward" : "forward", sc, units);
2584 }
2585 #endif
2586 
2587 
2588 /* Internal ioctl function */
2589 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2590 {
2591 	int timeout;
2592 	long ltmp;
2593 	int ioctl_result;
2594 	int chg_eof = 1;
2595 	unsigned char cmd[MAX_COMMAND_SIZE];
2596 	struct st_request *SRpnt;
2597 	struct st_partstat *STps;
2598 	int fileno, blkno, at_sm, undone;
2599 	int datalen = 0, direction = DMA_NONE;
2600 	char *name = tape_name(STp);
2601 
2602 	WARN_ON(STp->buffer->do_dio != 0);
2603 	if (STp->ready != ST_READY) {
2604 		if (STp->ready == ST_NO_TAPE)
2605 			return (-ENOMEDIUM);
2606 		else
2607 			return (-EIO);
2608 	}
2609 	timeout = STp->long_timeout;
2610 	STps = &(STp->ps[STp->partition]);
2611 	fileno = STps->drv_file;
2612 	blkno = STps->drv_block;
2613 	at_sm = STps->at_sm;
2614 
2615 	memset(cmd, 0, MAX_COMMAND_SIZE);
2616 	switch (cmd_in) {
2617 	case MTFSFM:
2618 		chg_eof = 0;	/* Changed from the FSF after this */
2619 	case MTFSF:
2620 		cmd[0] = SPACE;
2621 		cmd[1] = 0x01;	/* Space FileMarks */
2622 		cmd[2] = (arg >> 16);
2623 		cmd[3] = (arg >> 8);
2624 		cmd[4] = arg;
2625                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "filemarks", cmd);)
2626 		if (fileno >= 0)
2627 			fileno += arg;
2628 		blkno = 0;
2629 		at_sm &= (arg == 0);
2630 		break;
2631 	case MTBSFM:
2632 		chg_eof = 0;	/* Changed from the FSF after this */
2633 	case MTBSF:
2634 		cmd[0] = SPACE;
2635 		cmd[1] = 0x01;	/* Space FileMarks */
2636 		ltmp = (-arg);
2637 		cmd[2] = (ltmp >> 16);
2638 		cmd[3] = (ltmp >> 8);
2639 		cmd[4] = ltmp;
2640                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "filemarks", cmd);)
2641 		if (fileno >= 0)
2642 			fileno -= arg;
2643 		blkno = (-1);	/* We can't know the block number */
2644 		at_sm &= (arg == 0);
2645 		break;
2646 	case MTFSR:
2647 		cmd[0] = SPACE;
2648 		cmd[1] = 0x00;	/* Space Blocks */
2649 		cmd[2] = (arg >> 16);
2650 		cmd[3] = (arg >> 8);
2651 		cmd[4] = arg;
2652                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "blocks", cmd);)
2653 		if (blkno >= 0)
2654 			blkno += arg;
2655 		at_sm &= (arg == 0);
2656 		break;
2657 	case MTBSR:
2658 		cmd[0] = SPACE;
2659 		cmd[1] = 0x00;	/* Space Blocks */
2660 		ltmp = (-arg);
2661 		cmd[2] = (ltmp >> 16);
2662 		cmd[3] = (ltmp >> 8);
2663 		cmd[4] = ltmp;
2664                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "blocks", cmd);)
2665 		if (blkno >= 0)
2666 			blkno -= arg;
2667 		at_sm &= (arg == 0);
2668 		break;
2669 	case MTFSS:
2670 		cmd[0] = SPACE;
2671 		cmd[1] = 0x04;	/* Space Setmarks */
2672 		cmd[2] = (arg >> 16);
2673 		cmd[3] = (arg >> 8);
2674 		cmd[4] = arg;
2675                 DEBC(deb_space_print(name, ST_DEB_FORWARD, "setmarks", cmd);)
2676 		if (arg != 0) {
2677 			blkno = fileno = (-1);
2678 			at_sm = 1;
2679 		}
2680 		break;
2681 	case MTBSS:
2682 		cmd[0] = SPACE;
2683 		cmd[1] = 0x04;	/* Space Setmarks */
2684 		ltmp = (-arg);
2685 		cmd[2] = (ltmp >> 16);
2686 		cmd[3] = (ltmp >> 8);
2687 		cmd[4] = ltmp;
2688                 DEBC(deb_space_print(name, ST_DEB_BACKWARD, "setmarks", cmd);)
2689 		if (arg != 0) {
2690 			blkno = fileno = (-1);
2691 			at_sm = 1;
2692 		}
2693 		break;
2694 	case MTWEOF:
2695 	case MTWSM:
2696 		if (STp->write_prot)
2697 			return (-EACCES);
2698 		cmd[0] = WRITE_FILEMARKS;
2699 		if (cmd_in == MTWSM)
2700 			cmd[1] = 2;
2701 		cmd[2] = (arg >> 16);
2702 		cmd[3] = (arg >> 8);
2703 		cmd[4] = arg;
2704 		timeout = STp->device->request_queue->rq_timeout;
2705                 DEBC(
2706                      if (cmd_in == MTWEOF)
2707                                printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name,
2708 				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
2709                      else
2710 				printk(ST_DEB_MSG "%s: Writing %d setmarks.\n", name,
2711 				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
2712 		)
2713 		if (fileno >= 0)
2714 			fileno += arg;
2715 		blkno = 0;
2716 		at_sm = (cmd_in == MTWSM);
2717 		break;
2718 	case MTREW:
2719 		cmd[0] = REZERO_UNIT;
2720 		if (STp->immediate) {
2721 			cmd[1] = 1;	/* Don't wait for completion */
2722 			timeout = STp->device->request_queue->rq_timeout;
2723 		}
2724                 DEBC(printk(ST_DEB_MSG "%s: Rewinding tape.\n", name));
2725 		fileno = blkno = at_sm = 0;
2726 		break;
2727 	case MTNOP:
2728                 DEBC(printk(ST_DEB_MSG "%s: No op on tape.\n", name));
2729 		return 0;	/* Should do something ? */
2730 		break;
2731 	case MTRETEN:
2732 		cmd[0] = START_STOP;
2733 		if (STp->immediate) {
2734 			cmd[1] = 1;	/* Don't wait for completion */
2735 			timeout = STp->device->request_queue->rq_timeout;
2736 		}
2737 		cmd[4] = 3;
2738                 DEBC(printk(ST_DEB_MSG "%s: Retensioning tape.\n", name));
2739 		fileno = blkno = at_sm = 0;
2740 		break;
2741 	case MTEOM:
2742 		if (!STp->fast_mteom) {
2743 			/* space to the end of tape */
2744 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2745 			fileno = STps->drv_file;
2746 			if (STps->eof >= ST_EOD_1)
2747 				return 0;
2748 			/* The next lines would hide the number of spaced FileMarks
2749 			   That's why I inserted the previous lines. I had no luck
2750 			   with detecting EOM with FSF, so we go now to EOM.
2751 			   Joerg Weule */
2752 		} else
2753 			fileno = (-1);
2754 		cmd[0] = SPACE;
2755 		cmd[1] = 3;
2756                 DEBC(printk(ST_DEB_MSG "%s: Spacing to end of recorded medium.\n",
2757                             name));
2758 		blkno = -1;
2759 		at_sm = 0;
2760 		break;
2761 	case MTERASE:
2762 		if (STp->write_prot)
2763 			return (-EACCES);
2764 		cmd[0] = ERASE;
2765 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2766 		if (STp->immediate) {
2767 			cmd[1] |= 2;	/* Don't wait for completion */
2768 			timeout = STp->device->request_queue->rq_timeout;
2769 		}
2770 		else
2771 			timeout = STp->long_timeout * 8;
2772 
2773                 DEBC(printk(ST_DEB_MSG "%s: Erasing tape.\n", name));
2774 		fileno = blkno = at_sm = 0;
2775 		break;
2776 	case MTSETBLK:		/* Set block length */
2777 	case MTSETDENSITY:	/* Set tape density */
2778 	case MTSETDRVBUFFER:	/* Set drive buffering */
2779 	case SET_DENS_AND_BLK:	/* Set density and block size */
2780 		chg_eof = 0;
2781 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2782 			return (-EIO);	/* Not allowed if data in buffer */
2783 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2784 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2785 		    STp->max_block > 0 &&
2786 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2787 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2788 			printk(KERN_WARNING "%s: Illegal block size.\n", name);
2789 			return (-EINVAL);
2790 		}
2791 		cmd[0] = MODE_SELECT;
2792 		if ((STp->use_pf & USE_PF))
2793 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2794 		cmd[4] = datalen = 12;
2795 		direction = DMA_TO_DEVICE;
2796 
2797 		memset((STp->buffer)->b_data, 0, 12);
2798 		if (cmd_in == MTSETDRVBUFFER)
2799 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2800 		else
2801 			(STp->buffer)->b_data[2] =
2802 			    STp->drv_buffer << 4;
2803 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2804 		if (cmd_in == MTSETDENSITY) {
2805 			(STp->buffer)->b_data[4] = arg;
2806 			STp->density_changed = 1;	/* At least we tried ;-) */
2807 		} else if (cmd_in == SET_DENS_AND_BLK)
2808 			(STp->buffer)->b_data[4] = arg >> 24;
2809 		else
2810 			(STp->buffer)->b_data[4] = STp->density;
2811 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2812 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2813 			if (cmd_in == MTSETBLK)
2814 				STp->blksize_changed = 1; /* At least we tried ;-) */
2815 		} else
2816 			ltmp = STp->block_size;
2817 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2818 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2819 		(STp->buffer)->b_data[11] = ltmp;
2820 		timeout = STp->device->request_queue->rq_timeout;
2821                 DEBC(
2822 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2823 				printk(ST_DEB_MSG
2824                                        "%s: Setting block size to %d bytes.\n", name,
2825 				       (STp->buffer)->b_data[9] * 65536 +
2826 				       (STp->buffer)->b_data[10] * 256 +
2827 				       (STp->buffer)->b_data[11]);
2828 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2829 				printk(ST_DEB_MSG
2830                                        "%s: Setting density code to %x.\n", name,
2831 				       (STp->buffer)->b_data[4]);
2832 			if (cmd_in == MTSETDRVBUFFER)
2833 				printk(ST_DEB_MSG
2834                                        "%s: Setting drive buffer code to %d.\n", name,
2835 				    ((STp->buffer)->b_data[2] >> 4) & 7);
2836 		)
2837 		break;
2838 	default:
2839 		return (-ENOSYS);
2840 	}
2841 
2842 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2843 			   timeout, MAX_RETRIES, 1);
2844 	if (!SRpnt)
2845 		return (STp->buffer)->syscall_result;
2846 
2847 	ioctl_result = (STp->buffer)->syscall_result;
2848 
2849 	if (!ioctl_result) {	/* SCSI command successful */
2850 		st_release_request(SRpnt);
2851 		SRpnt = NULL;
2852 		STps->drv_block = blkno;
2853 		STps->drv_file = fileno;
2854 		STps->at_sm = at_sm;
2855 
2856 		if (cmd_in == MTBSFM)
2857 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2858 		else if (cmd_in == MTFSFM)
2859 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2860 
2861 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2862 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2863 			if (STp->block_size != 0) {
2864 				(STp->buffer)->buffer_blocks =
2865 				    (STp->buffer)->buffer_size / STp->block_size;
2866 			}
2867 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2868 			if (cmd_in == SET_DENS_AND_BLK)
2869 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2870 		} else if (cmd_in == MTSETDRVBUFFER)
2871 			STp->drv_buffer = (arg & 7);
2872 		else if (cmd_in == MTSETDENSITY)
2873 			STp->density = arg;
2874 
2875 		if (cmd_in == MTEOM)
2876 			STps->eof = ST_EOD;
2877 		else if (cmd_in == MTFSF)
2878 			STps->eof = ST_FM;
2879 		else if (chg_eof)
2880 			STps->eof = ST_NOEOF;
2881 
2882 		if (cmd_in == MTWEOF)
2883 			STps->rw = ST_IDLE;
2884 	} else { /* SCSI command was not completely successful. Don't return
2885                     from this block without releasing the SCSI command block! */
2886 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
2887 
2888 		if (cmdstatp->flags & SENSE_EOM) {
2889 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
2890 			    cmd_in != MTBSR && cmd_in != MTBSS)
2891 				STps->eof = ST_EOM_OK;
2892 			STps->drv_block = 0;
2893 		}
2894 
2895 		if (cmdstatp->remainder_valid)
2896 			undone = (int)cmdstatp->uremainder64;
2897 		else
2898 			undone = 0;
2899 
2900 		if (cmd_in == MTWEOF &&
2901 		    cmdstatp->have_sense &&
2902 		    (cmdstatp->flags & SENSE_EOM)) {
2903 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
2904 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
2905 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
2906 				STps->eof = ST_NOEOF;
2907 			} else {  /* Writing EOF(s) failed */
2908 				if (fileno >= 0)
2909 					fileno -= undone;
2910 				if (undone < arg)
2911 					STps->eof = ST_NOEOF;
2912 			}
2913 			STps->drv_file = fileno;
2914 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
2915 			if (fileno >= 0)
2916 				STps->drv_file = fileno - undone;
2917 			else
2918 				STps->drv_file = fileno;
2919 			STps->drv_block = -1;
2920 			STps->eof = ST_NOEOF;
2921 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
2922 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
2923 				undone = (-undone);
2924 			if (STps->drv_file >= 0)
2925 				STps->drv_file = fileno + undone;
2926 			STps->drv_block = 0;
2927 			STps->eof = ST_NOEOF;
2928 		} else if (cmd_in == MTFSR) {
2929 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
2930 				if (STps->drv_file >= 0)
2931 					STps->drv_file++;
2932 				STps->drv_block = 0;
2933 				STps->eof = ST_FM;
2934 			} else {
2935 				if (blkno >= undone)
2936 					STps->drv_block = blkno - undone;
2937 				else
2938 					STps->drv_block = (-1);
2939 				STps->eof = ST_NOEOF;
2940 			}
2941 		} else if (cmd_in == MTBSR) {
2942 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
2943 				STps->drv_file--;
2944 				STps->drv_block = (-1);
2945 			} else {
2946 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
2947 					undone = (-undone);
2948 				if (STps->drv_block >= 0)
2949 					STps->drv_block = blkno + undone;
2950 			}
2951 			STps->eof = ST_NOEOF;
2952 		} else if (cmd_in == MTEOM) {
2953 			STps->drv_file = (-1);
2954 			STps->drv_block = (-1);
2955 			STps->eof = ST_EOD;
2956 		} else if (cmd_in == MTSETBLK ||
2957 			   cmd_in == MTSETDENSITY ||
2958 			   cmd_in == MTSETDRVBUFFER ||
2959 			   cmd_in == SET_DENS_AND_BLK) {
2960 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
2961 			    !(STp->use_pf & PF_TESTED)) {
2962 				/* Try the other possible state of Page Format if not
2963 				   already tried */
2964 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
2965 				st_release_request(SRpnt);
2966 				SRpnt = NULL;
2967 				return st_int_ioctl(STp, cmd_in, arg);
2968 			}
2969 		} else if (chg_eof)
2970 			STps->eof = ST_NOEOF;
2971 
2972 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
2973 			STps->eof = ST_EOD;
2974 
2975 		st_release_request(SRpnt);
2976 		SRpnt = NULL;
2977 	}
2978 
2979 	return ioctl_result;
2980 }
2981 
2982 
2983 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
2984    structure. */
2985 
2986 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
2987 			int logical)
2988 {
2989 	int result;
2990 	unsigned char scmd[MAX_COMMAND_SIZE];
2991 	struct st_request *SRpnt;
2992 	DEB( char *name = tape_name(STp); )
2993 
2994 	if (STp->ready != ST_READY)
2995 		return (-EIO);
2996 
2997 	memset(scmd, 0, MAX_COMMAND_SIZE);
2998 	if ((STp->device)->scsi_level < SCSI_2) {
2999 		scmd[0] = QFA_REQUEST_BLOCK;
3000 		scmd[4] = 3;
3001 	} else {
3002 		scmd[0] = READ_POSITION;
3003 		if (!logical && !STp->scsi2_logical)
3004 			scmd[1] = 1;
3005 	}
3006 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3007 			   STp->device->request_queue->rq_timeout,
3008 			   MAX_READY_RETRIES, 1);
3009 	if (!SRpnt)
3010 		return (STp->buffer)->syscall_result;
3011 
3012 	if ((STp->buffer)->syscall_result != 0 ||
3013 	    (STp->device->scsi_level >= SCSI_2 &&
3014 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3015 		*block = *partition = 0;
3016                 DEBC(printk(ST_DEB_MSG "%s: Can't read tape position.\n", name));
3017 		result = (-EIO);
3018 	} else {
3019 		result = 0;
3020 		if ((STp->device)->scsi_level < SCSI_2) {
3021 			*block = ((STp->buffer)->b_data[0] << 16)
3022 			    + ((STp->buffer)->b_data[1] << 8)
3023 			    + (STp->buffer)->b_data[2];
3024 			*partition = 0;
3025 		} else {
3026 			*block = ((STp->buffer)->b_data[4] << 24)
3027 			    + ((STp->buffer)->b_data[5] << 16)
3028 			    + ((STp->buffer)->b_data[6] << 8)
3029 			    + (STp->buffer)->b_data[7];
3030 			*partition = (STp->buffer)->b_data[1];
3031 			if (((STp->buffer)->b_data[0] & 0x80) &&
3032 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3033 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3034 		}
3035                 DEBC(printk(ST_DEB_MSG "%s: Got tape pos. blk %d part %d.\n", name,
3036                             *block, *partition));
3037 	}
3038 	st_release_request(SRpnt);
3039 	SRpnt = NULL;
3040 
3041 	return result;
3042 }
3043 
3044 
3045 /* Set the tape block and partition. Negative partition means that only the
3046    block should be set in vendor specific way. */
3047 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3048 			int logical)
3049 {
3050 	struct st_partstat *STps;
3051 	int result, p;
3052 	unsigned int blk;
3053 	int timeout;
3054 	unsigned char scmd[MAX_COMMAND_SIZE];
3055 	struct st_request *SRpnt;
3056 	DEB( char *name = tape_name(STp); )
3057 
3058 	if (STp->ready != ST_READY)
3059 		return (-EIO);
3060 	timeout = STp->long_timeout;
3061 	STps = &(STp->ps[STp->partition]);
3062 
3063         DEBC(printk(ST_DEB_MSG "%s: Setting block to %d and partition to %d.\n",
3064                     name, block, partition));
3065 	DEB(if (partition < 0)
3066 		return (-EIO); )
3067 
3068 	/* Update the location at the partition we are leaving */
3069 	if ((!STp->can_partitions && partition != 0) ||
3070 	    partition >= ST_NBR_PARTITIONS)
3071 		return (-EINVAL);
3072 	if (partition != STp->partition) {
3073 		if (get_location(STp, &blk, &p, 1))
3074 			STps->last_block_valid = 0;
3075 		else {
3076 			STps->last_block_valid = 1;
3077 			STps->last_block_visited = blk;
3078                         DEBC(printk(ST_DEB_MSG
3079                                     "%s: Visited block %d for partition %d saved.\n",
3080                                     name, blk, STp->partition));
3081 		}
3082 	}
3083 
3084 	memset(scmd, 0, MAX_COMMAND_SIZE);
3085 	if ((STp->device)->scsi_level < SCSI_2) {
3086 		scmd[0] = QFA_SEEK_BLOCK;
3087 		scmd[2] = (block >> 16);
3088 		scmd[3] = (block >> 8);
3089 		scmd[4] = block;
3090 		scmd[5] = 0;
3091 	} else {
3092 		scmd[0] = SEEK_10;
3093 		scmd[3] = (block >> 24);
3094 		scmd[4] = (block >> 16);
3095 		scmd[5] = (block >> 8);
3096 		scmd[6] = block;
3097 		if (!logical && !STp->scsi2_logical)
3098 			scmd[1] = 4;
3099 		if (STp->partition != partition) {
3100 			scmd[1] |= 2;
3101 			scmd[8] = partition;
3102                         DEBC(printk(ST_DEB_MSG
3103                                     "%s: Trying to change partition from %d to %d\n",
3104                                     name, STp->partition, partition));
3105 		}
3106 	}
3107 	if (STp->immediate) {
3108 		scmd[1] |= 1;		/* Don't wait for completion */
3109 		timeout = STp->device->request_queue->rq_timeout;
3110 	}
3111 
3112 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3113 			   timeout, MAX_READY_RETRIES, 1);
3114 	if (!SRpnt)
3115 		return (STp->buffer)->syscall_result;
3116 
3117 	STps->drv_block = STps->drv_file = (-1);
3118 	STps->eof = ST_NOEOF;
3119 	if ((STp->buffer)->syscall_result != 0) {
3120 		result = (-EIO);
3121 		if (STp->can_partitions &&
3122 		    (STp->device)->scsi_level >= SCSI_2 &&
3123 		    (p = find_partition(STp)) >= 0)
3124 			STp->partition = p;
3125 	} else {
3126 		if (STp->can_partitions) {
3127 			STp->partition = partition;
3128 			STps = &(STp->ps[partition]);
3129 			if (!STps->last_block_valid ||
3130 			    STps->last_block_visited != block) {
3131 				STps->at_sm = 0;
3132 				STps->rw = ST_IDLE;
3133 			}
3134 		} else
3135 			STps->at_sm = 0;
3136 		if (block == 0)
3137 			STps->drv_block = STps->drv_file = 0;
3138 		result = 0;
3139 	}
3140 
3141 	st_release_request(SRpnt);
3142 	SRpnt = NULL;
3143 
3144 	return result;
3145 }
3146 
3147 
3148 /* Find the current partition number for the drive status. Called from open and
3149    returns either partition number of negative error code. */
3150 static int find_partition(struct scsi_tape *STp)
3151 {
3152 	int i, partition;
3153 	unsigned int block;
3154 
3155 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3156 		return i;
3157 	if (partition >= ST_NBR_PARTITIONS)
3158 		return (-EIO);
3159 	return partition;
3160 }
3161 
3162 
3163 /* Change the partition if necessary */
3164 static int switch_partition(struct scsi_tape *STp)
3165 {
3166 	struct st_partstat *STps;
3167 
3168 	if (STp->partition == STp->new_partition)
3169 		return 0;
3170 	STps = &(STp->ps[STp->new_partition]);
3171 	if (!STps->last_block_valid)
3172 		STps->last_block_visited = 0;
3173 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3174 }
3175 
3176 /* Functions for reading and writing the medium partition mode page. */
3177 
3178 #define PART_PAGE   0x11
3179 #define PART_PAGE_FIXED_LENGTH 8
3180 
3181 #define PP_OFF_MAX_ADD_PARTS   2
3182 #define PP_OFF_NBR_ADD_PARTS   3
3183 #define PP_OFF_FLAGS           4
3184 #define PP_OFF_PART_UNITS      6
3185 #define PP_OFF_RESERVED        7
3186 
3187 #define PP_BIT_IDP             0x20
3188 #define PP_MSK_PSUM_MB         0x10
3189 
3190 /* Get the number of partitions on the tape. As a side effect reads the
3191    mode page into the tape buffer. */
3192 static int nbr_partitions(struct scsi_tape *STp)
3193 {
3194 	int result;
3195 	DEB( char *name = tape_name(STp); )
3196 
3197 	if (STp->ready != ST_READY)
3198 		return (-EIO);
3199 
3200 	result = read_mode_page(STp, PART_PAGE, 1);
3201 
3202 	if (result) {
3203                 DEBC(printk(ST_DEB_MSG "%s: Can't read medium partition page.\n",
3204                             name));
3205 		result = (-EIO);
3206 	} else {
3207 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3208 					      PP_OFF_NBR_ADD_PARTS] + 1;
3209                 DEBC(printk(ST_DEB_MSG "%s: Number of partitions %d.\n", name, result));
3210 	}
3211 
3212 	return result;
3213 }
3214 
3215 
3216 /* Partition the tape into two partitions if size > 0 or one partition if
3217    size == 0.
3218 
3219    The block descriptors are read and written because Sony SDT-7000 does not
3220    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3221 
3222    My HP C1533A drive returns only one partition size field. This is used to
3223    set the size of partition 1. There is no size field for the default partition.
3224    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3225    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3226    The following algorithm is used to accommodate both drives: if the number of
3227    partition size fields is greater than the maximum number of additional partitions
3228    in the mode page, the second field is used. Otherwise the first field is used.
3229 
3230    For Seagate DDS drives the page length must be 8 when no partitions is defined
3231    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3232    is acceptable also to some other old drives and enforced if the first partition
3233    size field is used for the first additional partition size.
3234  */
3235 static int partition_tape(struct scsi_tape *STp, int size)
3236 {
3237 	char *name = tape_name(STp);
3238 	int result;
3239 	int pgo, psd_cnt, psdo;
3240 	unsigned char *bp;
3241 
3242 	result = read_mode_page(STp, PART_PAGE, 0);
3243 	if (result) {
3244 		DEBC(printk(ST_DEB_MSG "%s: Can't read partition mode page.\n", name));
3245 		return result;
3246 	}
3247 	/* The mode page is in the buffer. Let's modify it and write it. */
3248 	bp = (STp->buffer)->b_data;
3249 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3250 	DEBC(printk(ST_DEB_MSG "%s: Partition page length is %d bytes.\n",
3251 		    name, bp[pgo + MP_OFF_PAGE_LENGTH] + 2));
3252 
3253 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3254 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3255 	if (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS]) {
3256 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest of the tape */
3257 		psdo += 2;
3258 	}
3259 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3260 
3261 	DEBC(printk("%s: psd_cnt %d, max.parts %d, nbr_parts %d\n", name,
3262 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3263 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]));
3264 
3265 	if (size <= 0) {
3266 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3267 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3268 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3269                 DEBC(printk(ST_DEB_MSG "%s: Formatting tape with one partition.\n",
3270                             name));
3271 	} else {
3272 		bp[psdo] = (size >> 8) & 0xff;
3273 		bp[psdo + 1] = size & 0xff;
3274 		bp[pgo + 3] = 1;
3275 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3276 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3277                 DEBC(printk(ST_DEB_MSG
3278                             "%s: Formatting tape with two partitions (1 = %d MB).\n",
3279                             name, size));
3280 	}
3281 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3282 	bp[pgo + PP_OFF_RESERVED] = 0;
3283 	bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | PP_MSK_PSUM_MB;
3284 
3285 	result = write_mode_page(STp, PART_PAGE, 1);
3286 	if (result) {
3287 		printk(KERN_INFO "%s: Partitioning of tape failed.\n", name);
3288 		result = (-EIO);
3289 	}
3290 
3291 	return result;
3292 }
3293 
3294 
3295 
3296 /* The ioctl command */
3297 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3298 {
3299 	int i, cmd_nr, cmd_type, bt;
3300 	int retval = 0;
3301 	unsigned int blk;
3302 	struct scsi_tape *STp = file->private_data;
3303 	struct st_modedef *STm;
3304 	struct st_partstat *STps;
3305 	char *name = tape_name(STp);
3306 	void __user *p = (void __user *)arg;
3307 
3308 	if (mutex_lock_interruptible(&STp->lock))
3309 		return -ERESTARTSYS;
3310 
3311         DEB(
3312 	if (debugging && !STp->in_use) {
3313 		printk(ST_DEB_MSG "%s: Incorrect device.\n", name);
3314 		retval = (-EIO);
3315 		goto out;
3316 	} ) /* end DEB */
3317 
3318 	STm = &(STp->modes[STp->current_mode]);
3319 	STps = &(STp->ps[STp->partition]);
3320 
3321 	/*
3322 	 * If we are in the middle of error recovery, don't let anyone
3323 	 * else try and use this device.  Also, if error recovery fails, it
3324 	 * may try and take the device offline, in which case all further
3325 	 * access to the device is prohibited.
3326 	 */
3327 	retval = scsi_nonblockable_ioctl(STp->device, cmd_in, p,
3328 					file->f_flags & O_NDELAY);
3329 	if (!scsi_block_when_processing_errors(STp->device) || retval != -ENODEV)
3330 		goto out;
3331 	retval = 0;
3332 
3333 	cmd_type = _IOC_TYPE(cmd_in);
3334 	cmd_nr = _IOC_NR(cmd_in);
3335 
3336 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3337 		struct mtop mtc;
3338 
3339 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3340 			retval = (-EINVAL);
3341 			goto out;
3342 		}
3343 
3344 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3345 		if (i) {
3346 			retval = (-EFAULT);
3347 			goto out;
3348 		}
3349 
3350 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3351 			printk(KERN_WARNING
3352                                "%s: MTSETDRVBUFFER only allowed for root.\n", name);
3353 			retval = (-EPERM);
3354 			goto out;
3355 		}
3356 		if (!STm->defined &&
3357 		    (mtc.mt_op != MTSETDRVBUFFER &&
3358 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3359 			retval = (-ENXIO);
3360 			goto out;
3361 		}
3362 
3363 		if (!STp->pos_unknown) {
3364 
3365 			if (STps->eof == ST_FM_HIT) {
3366 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3367                                     mtc.mt_op == MTEOM) {
3368 					mtc.mt_count -= 1;
3369 					if (STps->drv_file >= 0)
3370 						STps->drv_file += 1;
3371 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3372 					mtc.mt_count += 1;
3373 					if (STps->drv_file >= 0)
3374 						STps->drv_file += 1;
3375 				}
3376 			}
3377 
3378 			if (mtc.mt_op == MTSEEK) {
3379 				/* Old position must be restored if partition will be
3380                                    changed */
3381 				i = !STp->can_partitions ||
3382 				    (STp->new_partition != STp->partition);
3383 			} else {
3384 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3385 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3386 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3387 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3388 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3389 				    mtc.mt_op == MTCOMPRESSION;
3390 			}
3391 			i = flush_buffer(STp, i);
3392 			if (i < 0) {
3393 				retval = i;
3394 				goto out;
3395 			}
3396 			if (STps->rw == ST_WRITING &&
3397 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3398 			     mtc.mt_op == MTSEEK ||
3399 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3400 				i = st_int_ioctl(STp, MTWEOF, 1);
3401 				if (i < 0) {
3402 					retval = i;
3403 					goto out;
3404 				}
3405 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3406 					mtc.mt_count++;
3407 				STps->rw = ST_IDLE;
3408 			     }
3409 
3410 		} else {
3411 			/*
3412 			 * If there was a bus reset, block further access
3413 			 * to this device.  If the user wants to rewind the tape,
3414 			 * then reset the flag and allow access again.
3415 			 */
3416 			if (mtc.mt_op != MTREW &&
3417 			    mtc.mt_op != MTOFFL &&
3418 			    mtc.mt_op != MTRETEN &&
3419 			    mtc.mt_op != MTERASE &&
3420 			    mtc.mt_op != MTSEEK &&
3421 			    mtc.mt_op != MTEOM) {
3422 				retval = (-EIO);
3423 				goto out;
3424 			}
3425 			reset_state(STp);
3426 			/* remove this when the midlevel properly clears was_reset */
3427 			STp->device->was_reset = 0;
3428 		}
3429 
3430 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3431 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3432 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3433 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3434 
3435 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3436 			do_door_lock(STp, 0);	/* Ignore result! */
3437 
3438 		if (mtc.mt_op == MTSETDRVBUFFER &&
3439 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3440 			retval = st_set_options(STp, mtc.mt_count);
3441 			goto out;
3442 		}
3443 
3444 		if (mtc.mt_op == MTSETPART) {
3445 			if (!STp->can_partitions ||
3446 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3447 				retval = (-EINVAL);
3448 				goto out;
3449 			}
3450 			if (mtc.mt_count >= STp->nbr_partitions &&
3451 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3452 				retval = (-EIO);
3453 				goto out;
3454 			}
3455 			if (mtc.mt_count >= STp->nbr_partitions) {
3456 				retval = (-EINVAL);
3457 				goto out;
3458 			}
3459 			STp->new_partition = mtc.mt_count;
3460 			retval = 0;
3461 			goto out;
3462 		}
3463 
3464 		if (mtc.mt_op == MTMKPART) {
3465 			if (!STp->can_partitions) {
3466 				retval = (-EINVAL);
3467 				goto out;
3468 			}
3469 			if ((i = st_int_ioctl(STp, MTREW, 0)) < 0 ||
3470 			    (i = partition_tape(STp, mtc.mt_count)) < 0) {
3471 				retval = i;
3472 				goto out;
3473 			}
3474 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3475 				STp->ps[i].rw = ST_IDLE;
3476 				STp->ps[i].at_sm = 0;
3477 				STp->ps[i].last_block_valid = 0;
3478 			}
3479 			STp->partition = STp->new_partition = 0;
3480 			STp->nbr_partitions = 1;	/* Bad guess ?-) */
3481 			STps->drv_block = STps->drv_file = 0;
3482 			retval = 0;
3483 			goto out;
3484 		}
3485 
3486 		if (mtc.mt_op == MTSEEK) {
3487 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3488 			if (!STp->can_partitions)
3489 				STp->ps[0].rw = ST_IDLE;
3490 			retval = i;
3491 			goto out;
3492 		}
3493 
3494 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3495 			retval = do_load_unload(STp, file, 0);
3496 			goto out;
3497 		}
3498 
3499 		if (mtc.mt_op == MTLOAD) {
3500 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3501 			goto out;
3502 		}
3503 
3504 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3505 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3506 			goto out;
3507 		}
3508 
3509 		if (STp->can_partitions && STp->ready == ST_READY &&
3510 		    (i = switch_partition(STp)) < 0) {
3511 			retval = i;
3512 			goto out;
3513 		}
3514 
3515 		if (mtc.mt_op == MTCOMPRESSION)
3516 			retval = st_compression(STp, (mtc.mt_count & 1));
3517 		else
3518 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3519 		goto out;
3520 	}
3521 	if (!STm->defined) {
3522 		retval = (-ENXIO);
3523 		goto out;
3524 	}
3525 
3526 	if ((i = flush_buffer(STp, 0)) < 0) {
3527 		retval = i;
3528 		goto out;
3529 	}
3530 	if (STp->can_partitions &&
3531 	    (i = switch_partition(STp)) < 0) {
3532 		retval = i;
3533 		goto out;
3534 	}
3535 
3536 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3537 		struct mtget mt_status;
3538 
3539 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3540 			 retval = (-EINVAL);
3541 			 goto out;
3542 		}
3543 
3544 		mt_status.mt_type = STp->tape_type;
3545 		mt_status.mt_dsreg =
3546 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3547 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3548 		mt_status.mt_blkno = STps->drv_block;
3549 		mt_status.mt_fileno = STps->drv_file;
3550 		if (STp->block_size != 0) {
3551 			if (STps->rw == ST_WRITING)
3552 				mt_status.mt_blkno +=
3553 				    (STp->buffer)->buffer_bytes / STp->block_size;
3554 			else if (STps->rw == ST_READING)
3555 				mt_status.mt_blkno -=
3556                                         ((STp->buffer)->buffer_bytes +
3557                                          STp->block_size - 1) / STp->block_size;
3558 		}
3559 
3560 		mt_status.mt_gstat = 0;
3561 		if (STp->drv_write_prot)
3562 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3563 		if (mt_status.mt_blkno == 0) {
3564 			if (mt_status.mt_fileno == 0)
3565 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3566 			else
3567 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3568 		}
3569 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3570 		mt_status.mt_resid = STp->partition;
3571 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3572 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3573 		else if (STps->eof >= ST_EOM_OK)
3574 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3575 		if (STp->density == 1)
3576 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3577 		else if (STp->density == 2)
3578 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3579 		else if (STp->density == 3)
3580 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3581 		if (STp->ready == ST_READY)
3582 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3583 		if (STp->ready == ST_NO_TAPE)
3584 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3585 		if (STps->at_sm)
3586 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3587 		if (STm->do_async_writes ||
3588                     (STm->do_buffer_writes && STp->block_size != 0) ||
3589 		    STp->drv_buffer != 0)
3590 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3591 		if (STp->cleaning_req)
3592 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3593 
3594 		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
3595 		if (i) {
3596 			retval = (-EFAULT);
3597 			goto out;
3598 		}
3599 
3600 		STp->recover_reg = 0;		/* Clear after read */
3601 		retval = 0;
3602 		goto out;
3603 	}			/* End of MTIOCGET */
3604 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3605 		struct mtpos mt_pos;
3606 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3607 			 retval = (-EINVAL);
3608 			 goto out;
3609 		}
3610 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3611 			retval = i;
3612 			goto out;
3613 		}
3614 		mt_pos.mt_blkno = blk;
3615 		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
3616 		if (i)
3617 			retval = (-EFAULT);
3618 		goto out;
3619 	}
3620 	mutex_unlock(&STp->lock);
3621 	switch (cmd_in) {
3622 		case SCSI_IOCTL_GET_IDLUN:
3623 		case SCSI_IOCTL_GET_BUS_NUMBER:
3624 			break;
3625 		default:
3626 			if ((cmd_in == SG_IO ||
3627 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3628 			     cmd_in == CDROM_SEND_PACKET) &&
3629 			    !capable(CAP_SYS_RAWIO))
3630 				i = -EPERM;
3631 			else
3632 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3633 						   file->f_mode, cmd_in, p);
3634 			if (i != -ENOTTY)
3635 				return i;
3636 			break;
3637 	}
3638 	retval = scsi_ioctl(STp->device, cmd_in, p);
3639 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3640 		STp->rew_at_close = 0;
3641 		STp->ready = ST_NO_TAPE;
3642 	}
3643 	return retval;
3644 
3645  out:
3646 	mutex_unlock(&STp->lock);
3647 	return retval;
3648 }
3649 
3650 #ifdef CONFIG_COMPAT
3651 static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3652 {
3653 	struct scsi_tape *STp = file->private_data;
3654 	struct scsi_device *sdev = STp->device;
3655 	int ret = -ENOIOCTLCMD;
3656 	if (sdev->host->hostt->compat_ioctl) {
3657 
3658 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
3659 
3660 	}
3661 	return ret;
3662 }
3663 #endif
3664 
3665 
3666 
3667 /* Try to allocate a new tape buffer. Calling function must not hold
3668    dev_arr_lock. */
3669 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3670 {
3671 	struct st_buffer *tb;
3672 
3673 	tb = kzalloc(sizeof(struct st_buffer), GFP_ATOMIC);
3674 	if (!tb) {
3675 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3676 		return NULL;
3677 	}
3678 	tb->frp_segs = 0;
3679 	tb->use_sg = max_sg;
3680 	tb->dma = need_dma;
3681 	tb->buffer_size = 0;
3682 
3683 	tb->reserved_pages = kzalloc(max_sg * sizeof(struct page *),
3684 				     GFP_ATOMIC);
3685 	if (!tb->reserved_pages) {
3686 		kfree(tb);
3687 		return NULL;
3688 	}
3689 
3690 	return tb;
3691 }
3692 
3693 
3694 /* Try to allocate enough space in the tape buffer */
3695 #define ST_MAX_ORDER 6
3696 
3697 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3698 {
3699 	int segs, nbr, max_segs, b_size, order, got;
3700 	gfp_t priority;
3701 
3702 	if (new_size <= STbuffer->buffer_size)
3703 		return 1;
3704 
3705 	if (STbuffer->buffer_size <= PAGE_SIZE)
3706 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3707 
3708 	max_segs = STbuffer->use_sg;
3709 	nbr = max_segs - STbuffer->frp_segs;
3710 	if (nbr <= 0)
3711 		return 0;
3712 
3713 	priority = GFP_KERNEL | __GFP_NOWARN;
3714 	if (need_dma)
3715 		priority |= GFP_DMA;
3716 
3717 	if (STbuffer->cleared)
3718 		priority |= __GFP_ZERO;
3719 
3720 	if (STbuffer->frp_segs) {
3721 		order = STbuffer->map_data.page_order;
3722 		b_size = PAGE_SIZE << order;
3723 	} else {
3724 		for (b_size = PAGE_SIZE, order = 0;
3725 		     order < ST_MAX_ORDER && b_size < new_size;
3726 		     order++, b_size *= 2)
3727 			;  /* empty */
3728 	}
3729 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3730 		if (order == ST_MAX_ORDER)
3731 			return 0;
3732 		normalize_buffer(STbuffer);
3733 		return enlarge_buffer(STbuffer, new_size, need_dma);
3734 	}
3735 
3736 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3737 	     segs < max_segs && got < new_size;) {
3738 		struct page *page;
3739 
3740 		page = alloc_pages(priority, order);
3741 		if (!page) {
3742 			DEB(STbuffer->buffer_size = got);
3743 			normalize_buffer(STbuffer);
3744 			return 0;
3745 		}
3746 
3747 		STbuffer->frp_segs += 1;
3748 		got += b_size;
3749 		STbuffer->buffer_size = got;
3750 		STbuffer->reserved_pages[segs] = page;
3751 		segs++;
3752 	}
3753 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3754 	STbuffer->map_data.page_order = order;
3755 
3756 	return 1;
3757 }
3758 
3759 
3760 /* Make sure that no data from previous user is in the internal buffer */
3761 static void clear_buffer(struct st_buffer * st_bp)
3762 {
3763 	int i;
3764 
3765 	for (i=0; i < st_bp->frp_segs; i++)
3766 		memset(page_address(st_bp->reserved_pages[i]), 0,
3767 		       PAGE_SIZE << st_bp->map_data.page_order);
3768 	st_bp->cleared = 1;
3769 }
3770 
3771 
3772 /* Release the extra buffer */
3773 static void normalize_buffer(struct st_buffer * STbuffer)
3774 {
3775 	int i, order = STbuffer->map_data.page_order;
3776 
3777 	for (i = 0; i < STbuffer->frp_segs; i++) {
3778 		__free_pages(STbuffer->reserved_pages[i], order);
3779 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3780 	}
3781 	STbuffer->frp_segs = 0;
3782 	STbuffer->sg_segs = 0;
3783 	STbuffer->map_data.page_order = 0;
3784 	STbuffer->map_data.offset = 0;
3785 }
3786 
3787 
3788 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3789    negative error code. */
3790 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3791 {
3792 	int i, cnt, res, offset;
3793 	int length = PAGE_SIZE << st_bp->map_data.page_order;
3794 
3795 	for (i = 0, offset = st_bp->buffer_bytes;
3796 	     i < st_bp->frp_segs && offset >= length; i++)
3797 		offset -= length;
3798 	if (i == st_bp->frp_segs) {	/* Should never happen */
3799 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
3800 		return (-EIO);
3801 	}
3802 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3803 		struct page *page = st_bp->reserved_pages[i];
3804 		cnt = length - offset < do_count ? length - offset : do_count;
3805 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
3806 		if (res)
3807 			return (-EFAULT);
3808 		do_count -= cnt;
3809 		st_bp->buffer_bytes += cnt;
3810 		ubp += cnt;
3811 		offset = 0;
3812 	}
3813 	if (do_count) /* Should never happen */
3814 		return (-EIO);
3815 
3816 	return 0;
3817 }
3818 
3819 
3820 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
3821    negative error code. */
3822 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
3823 {
3824 	int i, cnt, res, offset;
3825 	int length = PAGE_SIZE << st_bp->map_data.page_order;
3826 
3827 	for (i = 0, offset = st_bp->read_pointer;
3828 	     i < st_bp->frp_segs && offset >= length; i++)
3829 		offset -= length;
3830 	if (i == st_bp->frp_segs) {	/* Should never happen */
3831 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
3832 		return (-EIO);
3833 	}
3834 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3835 		struct page *page = st_bp->reserved_pages[i];
3836 		cnt = length - offset < do_count ? length - offset : do_count;
3837 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
3838 		if (res)
3839 			return (-EFAULT);
3840 		do_count -= cnt;
3841 		st_bp->buffer_bytes -= cnt;
3842 		st_bp->read_pointer += cnt;
3843 		ubp += cnt;
3844 		offset = 0;
3845 	}
3846 	if (do_count) /* Should never happen */
3847 		return (-EIO);
3848 
3849 	return 0;
3850 }
3851 
3852 
3853 /* Move data towards start of buffer */
3854 static void move_buffer_data(struct st_buffer * st_bp, int offset)
3855 {
3856 	int src_seg, dst_seg, src_offset = 0, dst_offset;
3857 	int count, total;
3858 	int length = PAGE_SIZE << st_bp->map_data.page_order;
3859 
3860 	if (offset == 0)
3861 		return;
3862 
3863 	total=st_bp->buffer_bytes - offset;
3864 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
3865 		src_offset = offset;
3866 		if (src_offset < length)
3867 			break;
3868 		offset -= length;
3869 	}
3870 
3871 	st_bp->buffer_bytes = st_bp->read_pointer = total;
3872 	for (dst_seg=dst_offset=0; total > 0; ) {
3873 		struct page *dpage = st_bp->reserved_pages[dst_seg];
3874 		struct page *spage = st_bp->reserved_pages[src_seg];
3875 
3876 		count = min(length - dst_offset, length - src_offset);
3877 		memmove(page_address(dpage) + dst_offset,
3878 			page_address(spage) + src_offset, count);
3879 		src_offset += count;
3880 		if (src_offset >= length) {
3881 			src_seg++;
3882 			src_offset = 0;
3883 		}
3884 		dst_offset += count;
3885 		if (dst_offset >= length) {
3886 			dst_seg++;
3887 			dst_offset = 0;
3888 		}
3889 		total -= count;
3890 	}
3891 }
3892 
3893 /* Validate the options from command line or module parameters */
3894 static void validate_options(void)
3895 {
3896 	if (buffer_kbs > 0)
3897 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
3898 	if (max_sg_segs >= ST_FIRST_SG)
3899 		st_max_sg_segs = max_sg_segs;
3900 }
3901 
3902 #ifndef MODULE
3903 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
3904  */
3905 static int __init st_setup(char *str)
3906 {
3907 	int i, len, ints[5];
3908 	char *stp;
3909 
3910 	stp = get_options(str, ARRAY_SIZE(ints), ints);
3911 
3912 	if (ints[0] > 0) {
3913 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
3914 			if (parms[i].val)
3915 				*parms[i].val = ints[i + 1];
3916 	} else {
3917 		while (stp != NULL) {
3918 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
3919 				len = strlen(parms[i].name);
3920 				if (!strncmp(stp, parms[i].name, len) &&
3921 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
3922 					if (parms[i].val)
3923 						*parms[i].val =
3924 							simple_strtoul(stp + len + 1, NULL, 0);
3925 					else
3926 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
3927 						       parms[i].name);
3928 					break;
3929 				}
3930 			}
3931 			if (i >= ARRAY_SIZE(parms))
3932 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
3933 					stp);
3934 			stp = strchr(stp, ',');
3935 			if (stp)
3936 				stp++;
3937 		}
3938 	}
3939 
3940 	validate_options();
3941 
3942 	return 1;
3943 }
3944 
3945 __setup("st=", st_setup);
3946 
3947 #endif
3948 
3949 static const struct file_operations st_fops =
3950 {
3951 	.owner =	THIS_MODULE,
3952 	.read =		st_read,
3953 	.write =	st_write,
3954 	.unlocked_ioctl = st_ioctl,
3955 #ifdef CONFIG_COMPAT
3956 	.compat_ioctl = st_compat_ioctl,
3957 #endif
3958 	.open =		st_open,
3959 	.flush =	st_flush,
3960 	.release =	st_release,
3961 };
3962 
3963 static int st_probe(struct device *dev)
3964 {
3965 	struct scsi_device *SDp = to_scsi_device(dev);
3966 	struct gendisk *disk = NULL;
3967 	struct cdev *cdev = NULL;
3968 	struct scsi_tape *tpnt = NULL;
3969 	struct st_modedef *STm;
3970 	struct st_partstat *STps;
3971 	struct st_buffer *buffer;
3972 	int i, j, mode, dev_num, error;
3973 	char *stp;
3974 
3975 	if (SDp->type != TYPE_TAPE)
3976 		return -ENODEV;
3977 	if ((stp = st_incompatible(SDp))) {
3978 		sdev_printk(KERN_INFO, SDp, "Found incompatible tape\n");
3979 		printk(KERN_INFO "st: The suggested driver is %s.\n", stp);
3980 		return -ENODEV;
3981 	}
3982 
3983 	i = min(queue_max_hw_segments(SDp->request_queue),
3984 		queue_max_phys_segments(SDp->request_queue));
3985 	if (st_max_sg_segs < i)
3986 		i = st_max_sg_segs;
3987 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
3988 	if (buffer == NULL) {
3989 		printk(KERN_ERR
3990 		       "st: Can't allocate new tape buffer. Device not attached.\n");
3991 		goto out;
3992 	}
3993 
3994 	disk = alloc_disk(1);
3995 	if (!disk) {
3996 		printk(KERN_ERR "st: out of memory. Device not attached.\n");
3997 		goto out_buffer_free;
3998 	}
3999 
4000 	write_lock(&st_dev_arr_lock);
4001 	if (st_nr_dev >= st_dev_max) {
4002 		struct scsi_tape **tmp_da;
4003 		int tmp_dev_max;
4004 
4005 		tmp_dev_max = max(st_nr_dev * 2, 8);
4006 		if (tmp_dev_max > ST_MAX_TAPES)
4007 			tmp_dev_max = ST_MAX_TAPES;
4008 		if (tmp_dev_max <= st_nr_dev) {
4009 			write_unlock(&st_dev_arr_lock);
4010 			printk(KERN_ERR "st: Too many tape devices (max. %d).\n",
4011 			       ST_MAX_TAPES);
4012 			goto out_put_disk;
4013 		}
4014 
4015 		tmp_da = kzalloc(tmp_dev_max * sizeof(struct scsi_tape *), GFP_ATOMIC);
4016 		if (tmp_da == NULL) {
4017 			write_unlock(&st_dev_arr_lock);
4018 			printk(KERN_ERR "st: Can't extend device array.\n");
4019 			goto out_put_disk;
4020 		}
4021 
4022 		if (scsi_tapes != NULL) {
4023 			memcpy(tmp_da, scsi_tapes,
4024 			       st_dev_max * sizeof(struct scsi_tape *));
4025 			kfree(scsi_tapes);
4026 		}
4027 		scsi_tapes = tmp_da;
4028 
4029 		st_dev_max = tmp_dev_max;
4030 	}
4031 
4032 	for (i = 0; i < st_dev_max; i++)
4033 		if (scsi_tapes[i] == NULL)
4034 			break;
4035 	if (i >= st_dev_max)
4036 		panic("scsi_devices corrupt (st)");
4037 
4038 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
4039 	if (tpnt == NULL) {
4040 		write_unlock(&st_dev_arr_lock);
4041 		printk(KERN_ERR "st: Can't allocate device descriptor.\n");
4042 		goto out_put_disk;
4043 	}
4044 	kref_init(&tpnt->kref);
4045 	tpnt->disk = disk;
4046 	sprintf(disk->disk_name, "st%d", i);
4047 	disk->private_data = &tpnt->driver;
4048 	disk->queue = SDp->request_queue;
4049 	tpnt->driver = &st_template;
4050 	scsi_tapes[i] = tpnt;
4051 	dev_num = i;
4052 
4053 	tpnt->device = SDp;
4054 	if (SDp->scsi_level <= 2)
4055 		tpnt->tape_type = MT_ISSCSI1;
4056 	else
4057 		tpnt->tape_type = MT_ISSCSI2;
4058 
4059 	tpnt->buffer = buffer;
4060 	tpnt->buffer->last_SRpnt = NULL;
4061 
4062 	tpnt->inited = 0;
4063 	tpnt->dirty = 0;
4064 	tpnt->in_use = 0;
4065 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4066 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4067 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4068 	tpnt->density = 0;
4069 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4070 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4071 	tpnt->can_partitions = 0;
4072 	tpnt->two_fm = ST_TWO_FM;
4073 	tpnt->fast_mteom = ST_FAST_MTEOM;
4074 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4075 	tpnt->sili = ST_SILI;
4076 	tpnt->immediate = ST_NOWAIT;
4077 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4078 	tpnt->partition = 0;
4079 	tpnt->new_partition = 0;
4080 	tpnt->nbr_partitions = 0;
4081 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4082 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4083 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4084 
4085 	for (i = 0; i < ST_NBR_MODES; i++) {
4086 		STm = &(tpnt->modes[i]);
4087 		STm->defined = 0;
4088 		STm->sysv = ST_SYSV;
4089 		STm->defaults_for_writes = 0;
4090 		STm->do_async_writes = ST_ASYNC_WRITES;
4091 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4092 		STm->do_read_ahead = ST_READ_AHEAD;
4093 		STm->default_compression = ST_DONT_TOUCH;
4094 		STm->default_blksize = (-1);	/* No forced size */
4095 		STm->default_density = (-1);	/* No forced density */
4096 	}
4097 
4098 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4099 		STps = &(tpnt->ps[i]);
4100 		STps->rw = ST_IDLE;
4101 		STps->eof = ST_NOEOF;
4102 		STps->at_sm = 0;
4103 		STps->last_block_valid = 0;
4104 		STps->drv_block = (-1);
4105 		STps->drv_file = (-1);
4106 	}
4107 
4108 	tpnt->current_mode = 0;
4109 	tpnt->modes[0].defined = 1;
4110 
4111 	tpnt->density_changed = tpnt->compression_changed =
4112 	    tpnt->blksize_changed = 0;
4113 	mutex_init(&tpnt->lock);
4114 
4115 	st_nr_dev++;
4116 	write_unlock(&st_dev_arr_lock);
4117 
4118 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4119 		STm = &(tpnt->modes[mode]);
4120 		for (j=0; j < 2; j++) {
4121 			cdev = cdev_alloc();
4122 			if (!cdev) {
4123 				printk(KERN_ERR
4124 				       "st%d: out of memory. Device not attached.\n",
4125 				       dev_num);
4126 				goto out_free_tape;
4127 			}
4128 			cdev->owner = THIS_MODULE;
4129 			cdev->ops = &st_fops;
4130 
4131 			error = cdev_add(cdev,
4132 					 MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, j)),
4133 					 1);
4134 			if (error) {
4135 				printk(KERN_ERR "st%d: Can't add %s-rewind mode %d\n",
4136 				       dev_num, j ? "non" : "auto", mode);
4137 				printk(KERN_ERR "st%d: Device not attached.\n", dev_num);
4138 				goto out_free_tape;
4139 			}
4140 			STm->cdevs[j] = cdev;
4141 
4142 		}
4143 		error = do_create_class_files(tpnt, dev_num, mode);
4144 		if (error)
4145 			goto out_free_tape;
4146 	}
4147 
4148 	sdev_printk(KERN_NOTICE, SDp,
4149 		    "Attached scsi tape %s\n", tape_name(tpnt));
4150 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4151 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4152 		    queue_dma_alignment(SDp->request_queue) + 1);
4153 
4154 	return 0;
4155 
4156 out_free_tape:
4157 	for (mode=0; mode < ST_NBR_MODES; mode++) {
4158 		STm = &(tpnt->modes[mode]);
4159 		sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
4160 				  "tape");
4161 		for (j=0; j < 2; j++) {
4162 			if (STm->cdevs[j]) {
4163 				if (cdev == STm->cdevs[j])
4164 					cdev = NULL;
4165 					device_destroy(st_sysfs_class,
4166 						       MKDEV(SCSI_TAPE_MAJOR,
4167 							     TAPE_MINOR(i, mode, j)));
4168 				cdev_del(STm->cdevs[j]);
4169 			}
4170 		}
4171 	}
4172 	if (cdev)
4173 		cdev_del(cdev);
4174 	write_lock(&st_dev_arr_lock);
4175 	scsi_tapes[dev_num] = NULL;
4176 	st_nr_dev--;
4177 	write_unlock(&st_dev_arr_lock);
4178 out_put_disk:
4179 	put_disk(disk);
4180 	kfree(tpnt);
4181 out_buffer_free:
4182 	kfree(buffer);
4183 out:
4184 	return -ENODEV;
4185 };
4186 
4187 
4188 static int st_remove(struct device *dev)
4189 {
4190 	struct scsi_device *SDp = to_scsi_device(dev);
4191 	struct scsi_tape *tpnt;
4192 	int i, j, mode;
4193 
4194 	write_lock(&st_dev_arr_lock);
4195 	for (i = 0; i < st_dev_max; i++) {
4196 		tpnt = scsi_tapes[i];
4197 		if (tpnt != NULL && tpnt->device == SDp) {
4198 			scsi_tapes[i] = NULL;
4199 			st_nr_dev--;
4200 			write_unlock(&st_dev_arr_lock);
4201 			sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
4202 					  "tape");
4203 			for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4204 				for (j=0; j < 2; j++) {
4205 					device_destroy(st_sysfs_class,
4206 						       MKDEV(SCSI_TAPE_MAJOR,
4207 							     TAPE_MINOR(i, mode, j)));
4208 					cdev_del(tpnt->modes[mode].cdevs[j]);
4209 					tpnt->modes[mode].cdevs[j] = NULL;
4210 				}
4211 			}
4212 
4213 			mutex_lock(&st_ref_mutex);
4214 			kref_put(&tpnt->kref, scsi_tape_release);
4215 			mutex_unlock(&st_ref_mutex);
4216 			return 0;
4217 		}
4218 	}
4219 
4220 	write_unlock(&st_dev_arr_lock);
4221 	return 0;
4222 }
4223 
4224 /**
4225  *      scsi_tape_release - Called to free the Scsi_Tape structure
4226  *      @kref: pointer to embedded kref
4227  *
4228  *      st_ref_mutex must be held entering this routine.  Because it is
4229  *      called on last put, you should always use the scsi_tape_get()
4230  *      scsi_tape_put() helpers which manipulate the semaphore directly
4231  *      and never do a direct kref_put().
4232  **/
4233 static void scsi_tape_release(struct kref *kref)
4234 {
4235 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4236 	struct gendisk *disk = tpnt->disk;
4237 
4238 	tpnt->device = NULL;
4239 
4240 	if (tpnt->buffer) {
4241 		normalize_buffer(tpnt->buffer);
4242 		kfree(tpnt->buffer->reserved_pages);
4243 		kfree(tpnt->buffer);
4244 	}
4245 
4246 	disk->private_data = NULL;
4247 	put_disk(disk);
4248 	kfree(tpnt);
4249 	return;
4250 }
4251 
4252 static int __init init_st(void)
4253 {
4254 	int err;
4255 
4256 	validate_options();
4257 
4258 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4259 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4260 
4261 	st_sysfs_class = class_create(THIS_MODULE, "scsi_tape");
4262 	if (IS_ERR(st_sysfs_class)) {
4263 		printk(KERN_ERR "Unable create sysfs class for SCSI tapes\n");
4264 		return PTR_ERR(st_sysfs_class);
4265 	}
4266 
4267 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4268 				     ST_MAX_TAPE_ENTRIES, "st");
4269 	if (err) {
4270 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4271 		       SCSI_TAPE_MAJOR);
4272 		goto err_class;
4273 	}
4274 
4275 	err = scsi_register_driver(&st_template.gendrv);
4276 	if (err)
4277 		goto err_chrdev;
4278 
4279 	err = do_create_sysfs_files();
4280 	if (err)
4281 		goto err_scsidrv;
4282 
4283 	return 0;
4284 
4285 err_scsidrv:
4286 	scsi_unregister_driver(&st_template.gendrv);
4287 err_chrdev:
4288 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4289 				 ST_MAX_TAPE_ENTRIES);
4290 err_class:
4291 	class_destroy(st_sysfs_class);
4292 	return err;
4293 }
4294 
4295 static void __exit exit_st(void)
4296 {
4297 	do_remove_sysfs_files();
4298 	scsi_unregister_driver(&st_template.gendrv);
4299 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4300 				 ST_MAX_TAPE_ENTRIES);
4301 	class_destroy(st_sysfs_class);
4302 	kfree(scsi_tapes);
4303 	printk(KERN_INFO "st: Unloaded.\n");
4304 }
4305 
4306 module_init(init_st);
4307 module_exit(exit_st);
4308 
4309 
4310 /* The sysfs driver interface. Read-only at the moment */
4311 static ssize_t st_try_direct_io_show(struct device_driver *ddp, char *buf)
4312 {
4313 	return snprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4314 }
4315 static DRIVER_ATTR(try_direct_io, S_IRUGO, st_try_direct_io_show, NULL);
4316 
4317 static ssize_t st_fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4318 {
4319 	return snprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4320 }
4321 static DRIVER_ATTR(fixed_buffer_size, S_IRUGO, st_fixed_buffer_size_show, NULL);
4322 
4323 static ssize_t st_max_sg_segs_show(struct device_driver *ddp, char *buf)
4324 {
4325 	return snprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4326 }
4327 static DRIVER_ATTR(max_sg_segs, S_IRUGO, st_max_sg_segs_show, NULL);
4328 
4329 static ssize_t st_version_show(struct device_driver *ddd, char *buf)
4330 {
4331 	return snprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4332 }
4333 static DRIVER_ATTR(version, S_IRUGO, st_version_show, NULL);
4334 
4335 static int do_create_sysfs_files(void)
4336 {
4337 	struct device_driver *sysfs = &st_template.gendrv;
4338 	int err;
4339 
4340 	err = driver_create_file(sysfs, &driver_attr_try_direct_io);
4341 	if (err)
4342 		return err;
4343 	err = driver_create_file(sysfs, &driver_attr_fixed_buffer_size);
4344 	if (err)
4345 		goto err_try_direct_io;
4346 	err = driver_create_file(sysfs, &driver_attr_max_sg_segs);
4347 	if (err)
4348 		goto err_attr_fixed_buf;
4349 	err = driver_create_file(sysfs, &driver_attr_version);
4350 	if (err)
4351 		goto err_attr_max_sg;
4352 
4353 	return 0;
4354 
4355 err_attr_max_sg:
4356 	driver_remove_file(sysfs, &driver_attr_max_sg_segs);
4357 err_attr_fixed_buf:
4358 	driver_remove_file(sysfs, &driver_attr_fixed_buffer_size);
4359 err_try_direct_io:
4360 	driver_remove_file(sysfs, &driver_attr_try_direct_io);
4361 	return err;
4362 }
4363 
4364 static void do_remove_sysfs_files(void)
4365 {
4366 	struct device_driver *sysfs = &st_template.gendrv;
4367 
4368 	driver_remove_file(sysfs, &driver_attr_version);
4369 	driver_remove_file(sysfs, &driver_attr_max_sg_segs);
4370 	driver_remove_file(sysfs, &driver_attr_fixed_buffer_size);
4371 	driver_remove_file(sysfs, &driver_attr_try_direct_io);
4372 }
4373 
4374 
4375 /* The sysfs simple class interface */
4376 static ssize_t
4377 st_defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4378 {
4379 	struct st_modedef *STm = dev_get_drvdata(dev);
4380 	ssize_t l = 0;
4381 
4382 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4383 	return l;
4384 }
4385 
4386 DEVICE_ATTR(defined, S_IRUGO, st_defined_show, NULL);
4387 
4388 static ssize_t
4389 st_defblk_show(struct device *dev, struct device_attribute *attr, char *buf)
4390 {
4391 	struct st_modedef *STm = dev_get_drvdata(dev);
4392 	ssize_t l = 0;
4393 
4394 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4395 	return l;
4396 }
4397 
4398 DEVICE_ATTR(default_blksize, S_IRUGO, st_defblk_show, NULL);
4399 
4400 static ssize_t
4401 st_defdensity_show(struct device *dev, struct device_attribute *attr, char *buf)
4402 {
4403 	struct st_modedef *STm = dev_get_drvdata(dev);
4404 	ssize_t l = 0;
4405 	char *fmt;
4406 
4407 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4408 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4409 	return l;
4410 }
4411 
4412 DEVICE_ATTR(default_density, S_IRUGO, st_defdensity_show, NULL);
4413 
4414 static ssize_t
4415 st_defcompression_show(struct device *dev, struct device_attribute *attr,
4416 		       char *buf)
4417 {
4418 	struct st_modedef *STm = dev_get_drvdata(dev);
4419 	ssize_t l = 0;
4420 
4421 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4422 	return l;
4423 }
4424 
4425 DEVICE_ATTR(default_compression, S_IRUGO, st_defcompression_show, NULL);
4426 
4427 static ssize_t
4428 st_options_show(struct device *dev, struct device_attribute *attr, char *buf)
4429 {
4430 	struct st_modedef *STm = dev_get_drvdata(dev);
4431 	struct scsi_tape *STp;
4432 	int i, j, options;
4433 	ssize_t l = 0;
4434 
4435 	for (i=0; i < st_dev_max; i++) {
4436 		for (j=0; j < ST_NBR_MODES; j++)
4437 			if (&scsi_tapes[i]->modes[j] == STm)
4438 				break;
4439 		if (j < ST_NBR_MODES)
4440 			break;
4441 	}
4442 	if (i == st_dev_max)
4443 		return 0;  /* should never happen */
4444 
4445 	STp = scsi_tapes[i];
4446 
4447 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4448 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4449 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4450 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4451 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4452 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4453 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4454 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4455 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4456 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4457 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4458 	options |= STm->sysv ? MT_ST_SYSV : 0;
4459 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4460 	options |= STp->sili ? MT_ST_SILI : 0;
4461 
4462 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4463 	return l;
4464 }
4465 
4466 DEVICE_ATTR(options, S_IRUGO, st_options_show, NULL);
4467 
4468 static int do_create_class_files(struct scsi_tape *STp, int dev_num, int mode)
4469 {
4470 	int i, rew, error;
4471 	char name[10];
4472 	struct device *st_class_member;
4473 
4474 	for (rew=0; rew < 2; rew++) {
4475 		/* Make sure that the minor numbers corresponding to the four
4476 		   first modes always get the same names */
4477 		i = mode << (4 - ST_NBR_MODE_BITS);
4478 		snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4479 			 STp->disk->disk_name, st_formats[i]);
4480 		st_class_member =
4481 			device_create(st_sysfs_class, &STp->device->sdev_gendev,
4482 				      MKDEV(SCSI_TAPE_MAJOR,
4483 					    TAPE_MINOR(dev_num, mode, rew)),
4484 				      &STp->modes[mode], "%s", name);
4485 		if (IS_ERR(st_class_member)) {
4486 			printk(KERN_WARNING "st%d: device_create failed\n",
4487 			       dev_num);
4488 			error = PTR_ERR(st_class_member);
4489 			goto out;
4490 		}
4491 
4492 		error = device_create_file(st_class_member,
4493 					   &dev_attr_defined);
4494 		if (error) goto out;
4495 		error = device_create_file(st_class_member,
4496 					   &dev_attr_default_blksize);
4497 		if (error) goto out;
4498 		error = device_create_file(st_class_member,
4499 					   &dev_attr_default_density);
4500 		if (error) goto out;
4501 		error = device_create_file(st_class_member,
4502 					   &dev_attr_default_compression);
4503 		if (error) goto out;
4504 		error = device_create_file(st_class_member,
4505 					   &dev_attr_options);
4506 		if (error) goto out;
4507 
4508 		if (mode == 0 && rew == 0) {
4509 			error = sysfs_create_link(&STp->device->sdev_gendev.kobj,
4510 						  &st_class_member->kobj,
4511 						  "tape");
4512 			if (error) {
4513 				printk(KERN_ERR
4514 				       "st%d: Can't create sysfs link from SCSI device.\n",
4515 				       dev_num);
4516 				goto out;
4517 			}
4518 		}
4519 	}
4520 
4521 	return 0;
4522 
4523 out:
4524 	return error;
4525 }
4526 
4527 /* The following functions may be useful for a larger audience. */
4528 static int sgl_map_user_pages(struct st_buffer *STbp,
4529 			      const unsigned int max_pages, unsigned long uaddr,
4530 			      size_t count, int rw)
4531 {
4532 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4533 	unsigned long start = uaddr >> PAGE_SHIFT;
4534 	const int nr_pages = end - start;
4535 	int res, i, j;
4536 	struct page **pages;
4537 	struct rq_map_data *mdata = &STbp->map_data;
4538 
4539 	/* User attempted Overflow! */
4540 	if ((uaddr + count) < uaddr)
4541 		return -EINVAL;
4542 
4543 	/* Too big */
4544         if (nr_pages > max_pages)
4545 		return -ENOMEM;
4546 
4547 	/* Hmm? */
4548 	if (count == 0)
4549 		return 0;
4550 
4551 	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
4552 		return -ENOMEM;
4553 
4554         /* Try to fault in all of the necessary pages */
4555 	down_read(&current->mm->mmap_sem);
4556         /* rw==READ means read from drive, write into memory area */
4557 	res = get_user_pages(
4558 		current,
4559 		current->mm,
4560 		uaddr,
4561 		nr_pages,
4562 		rw == READ,
4563 		0, /* don't force */
4564 		pages,
4565 		NULL);
4566 	up_read(&current->mm->mmap_sem);
4567 
4568 	/* Errors and no page mapped should return here */
4569 	if (res < nr_pages)
4570 		goto out_unmap;
4571 
4572         for (i=0; i < nr_pages; i++) {
4573                 /* FIXME: flush superflous for rw==READ,
4574                  * probably wrong function for rw==WRITE
4575                  */
4576 		flush_dcache_page(pages[i]);
4577         }
4578 
4579 	mdata->offset = uaddr & ~PAGE_MASK;
4580 	mdata->page_order = 0;
4581 	STbp->mapped_pages = pages;
4582 
4583 	return nr_pages;
4584  out_unmap:
4585 	if (res > 0) {
4586 		for (j=0; j < res; j++)
4587 			page_cache_release(pages[j]);
4588 		res = 0;
4589 	}
4590 	kfree(pages);
4591 	return res;
4592 }
4593 
4594 
4595 /* And unmap them... */
4596 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4597 				const unsigned int nr_pages, int dirtied)
4598 {
4599 	int i;
4600 
4601 	for (i=0; i < nr_pages; i++) {
4602 		struct page *page = STbp->mapped_pages[i];
4603 
4604 		if (dirtied)
4605 			SetPageDirty(page);
4606 		/* FIXME: cache flush missing for rw==READ
4607 		 * FIXME: call the correct reference counting function
4608 		 */
4609 		page_cache_release(page);
4610 	}
4611 	kfree(STbp->mapped_pages);
4612 	STbp->mapped_pages = NULL;
4613 
4614 	return 0;
4615 }
4616