xref: /linux/drivers/scsi/st.c (revision 906fd46a65383cd639e5eec72a047efc33045d86)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3    SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
4    file Documentation/scsi/st.rst for more information.
5 
6    History:
7    Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
8    Contribution and ideas from several people including (in alphabetical
9    order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
10    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
11    Michael Schaefer, J"org Weule, and Eric Youngdale.
12 
13    Copyright 1992 - 2016 Kai Makisara
14    email Kai.Makisara@kolumbus.fi
15 
16    Some small formal changes - aeb, 950809
17 
18    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
19  */
20 
21 static const char *verstr = "20160209";
22 
23 #include <linux/module.h>
24 
25 #include <linux/compat.h>
26 #include <linux/fs.h>
27 #include <linux/kernel.h>
28 #include <linux/sched/signal.h>
29 #include <linux/mm.h>
30 #include <linux/init.h>
31 #include <linux/string.h>
32 #include <linux/slab.h>
33 #include <linux/errno.h>
34 #include <linux/mtio.h>
35 #include <linux/major.h>
36 #include <linux/cdrom.h>
37 #include <linux/ioctl.h>
38 #include <linux/fcntl.h>
39 #include <linux/spinlock.h>
40 #include <linux/blkdev.h>
41 #include <linux/moduleparam.h>
42 #include <linux/cdev.h>
43 #include <linux/idr.h>
44 #include <linux/delay.h>
45 #include <linux/mutex.h>
46 
47 #include <linux/uaccess.h>
48 #include <asm/dma.h>
49 #include <asm/unaligned.h>
50 
51 #include <scsi/scsi.h>
52 #include <scsi/scsi_dbg.h>
53 #include <scsi/scsi_device.h>
54 #include <scsi/scsi_driver.h>
55 #include <scsi/scsi_eh.h>
56 #include <scsi/scsi_host.h>
57 #include <scsi/scsi_ioctl.h>
58 #include <scsi/sg.h>
59 
60 
61 /* The driver prints some debugging information on the console if DEBUG
62    is defined and non-zero. */
63 #define DEBUG 1
64 #define NO_DEBUG 0
65 
66 #define ST_DEB_MSG  KERN_NOTICE
67 #if DEBUG
68 /* The message level for the debug messages is currently set to KERN_NOTICE
69    so that people can easily see the messages. Later when the debugging messages
70    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
71 #define DEB(a) a
72 #define DEBC(a) if (debugging) { a ; }
73 #else
74 #define DEB(a)
75 #define DEBC(a)
76 #endif
77 
78 #define ST_KILOBYTE 1024
79 
80 #include "st_options.h"
81 #include "st.h"
82 
83 static int buffer_kbs;
84 static int max_sg_segs;
85 static int try_direct_io = TRY_DIRECT_IO;
86 static int try_rdio = 1;
87 static int try_wdio = 1;
88 static int debug_flag;
89 
90 static const struct class st_sysfs_class;
91 static const struct attribute_group *st_dev_groups[];
92 static const struct attribute_group *st_drv_groups[];
93 
94 MODULE_AUTHOR("Kai Makisara");
95 MODULE_DESCRIPTION("SCSI tape (st) driver");
96 MODULE_LICENSE("GPL");
97 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
98 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
99 
100 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
101  * of sysfs parameters (which module_param doesn't yet support).
102  * Sysfs parameters defined explicitly later.
103  */
104 module_param_named(buffer_kbs, buffer_kbs, int, 0);
105 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
106 module_param_named(max_sg_segs, max_sg_segs, int, 0);
107 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
108 module_param_named(try_direct_io, try_direct_io, int, 0);
109 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
110 module_param_named(debug_flag, debug_flag, int, 0);
111 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
112 
113 
114 /* Extra parameters for testing */
115 module_param_named(try_rdio, try_rdio, int, 0);
116 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
117 module_param_named(try_wdio, try_wdio, int, 0);
118 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
119 
120 #ifndef MODULE
121 static int write_threshold_kbs;  /* retained for compatibility */
122 static struct st_dev_parm {
123 	char *name;
124 	int *val;
125 } parms[] __initdata = {
126 	{
127 		"buffer_kbs", &buffer_kbs
128 	},
129 	{       /* Retained for compatibility with 2.4 */
130 		"write_threshold_kbs", &write_threshold_kbs
131 	},
132 	{
133 		"max_sg_segs", NULL
134 	},
135 	{
136 		"try_direct_io", &try_direct_io
137 	},
138 	{
139 		"debug_flag", &debug_flag
140 	}
141 };
142 #endif
143 
144 /* Restrict the number of modes so that names for all are assigned */
145 #if ST_NBR_MODES > 16
146 #error "Maximum number of modes is 16"
147 #endif
148 /* Bit reversed order to get same names for same minors with all
149    mode counts */
150 static const char *st_formats[] = {
151 	"",  "r", "k", "s", "l", "t", "o", "u",
152 	"m", "v", "p", "x", "a", "y", "q", "z"};
153 
154 /* The default definitions have been moved to st_options.h */
155 
156 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
157 
158 /* The buffer size should fit into the 24 bits for length in the
159    6-byte SCSI read and write commands. */
160 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
161 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
162 #endif
163 
164 static int debugging = DEBUG;
165 
166 #define MAX_RETRIES 0
167 #define MAX_WRITE_RETRIES 0
168 #define MAX_READY_RETRIES 0
169 #define NO_TAPE  NOT_READY
170 
171 #define ST_TIMEOUT (900 * HZ)
172 #define ST_LONG_TIMEOUT (14000 * HZ)
173 
174 /* Remove mode bits and auto-rewind bit (7) */
175 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
176 	(iminor(x) & ((1 << ST_MODE_SHIFT)-1)))
177 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
178 
179 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
180 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
181   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
182 
183 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
184    24 bits) */
185 #define SET_DENS_AND_BLK 0x10001
186 
187 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
188 static int st_max_sg_segs = ST_MAX_SG;
189 
190 static int modes_defined;
191 
192 static int enlarge_buffer(struct st_buffer *, int);
193 static void clear_buffer(struct st_buffer *);
194 static void normalize_buffer(struct st_buffer *);
195 static int append_to_buffer(const char __user *, struct st_buffer *, int);
196 static int from_buffer(struct st_buffer *, char __user *, int);
197 static void move_buffer_data(struct st_buffer *, int);
198 
199 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
200 			      unsigned long, size_t, int);
201 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
202 
203 static int st_probe(struct device *);
204 static int st_remove(struct device *);
205 
206 static struct scsi_driver st_template = {
207 	.gendrv = {
208 		.name		= "st",
209 		.probe		= st_probe,
210 		.remove		= st_remove,
211 		.groups		= st_drv_groups,
212 	},
213 };
214 
215 static int st_compression(struct scsi_tape *, int);
216 
217 static int find_partition(struct scsi_tape *);
218 static int switch_partition(struct scsi_tape *);
219 
220 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
221 
222 static void scsi_tape_release(struct kref *);
223 
224 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
225 
226 static DEFINE_MUTEX(st_ref_mutex);
227 static DEFINE_SPINLOCK(st_index_lock);
228 static DEFINE_SPINLOCK(st_use_lock);
229 static DEFINE_IDR(st_index_idr);
230 
231 
232 
233 #ifndef SIGS_FROM_OSST
234 #define SIGS_FROM_OSST \
235 	{"OnStream", "SC-", "", "osst"}, \
236 	{"OnStream", "DI-", "", "osst"}, \
237 	{"OnStream", "DP-", "", "osst"}, \
238 	{"OnStream", "USB", "", "osst"}, \
239 	{"OnStream", "FW-", "", "osst"}
240 #endif
241 
242 static struct scsi_tape *scsi_tape_get(int dev)
243 {
244 	struct scsi_tape *STp = NULL;
245 
246 	mutex_lock(&st_ref_mutex);
247 	spin_lock(&st_index_lock);
248 
249 	STp = idr_find(&st_index_idr, dev);
250 	if (!STp) goto out;
251 
252 	kref_get(&STp->kref);
253 
254 	if (!STp->device)
255 		goto out_put;
256 
257 	if (scsi_device_get(STp->device))
258 		goto out_put;
259 
260 	goto out;
261 
262 out_put:
263 	kref_put(&STp->kref, scsi_tape_release);
264 	STp = NULL;
265 out:
266 	spin_unlock(&st_index_lock);
267 	mutex_unlock(&st_ref_mutex);
268 	return STp;
269 }
270 
271 static void scsi_tape_put(struct scsi_tape *STp)
272 {
273 	struct scsi_device *sdev = STp->device;
274 
275 	mutex_lock(&st_ref_mutex);
276 	kref_put(&STp->kref, scsi_tape_release);
277 	scsi_device_put(sdev);
278 	mutex_unlock(&st_ref_mutex);
279 }
280 
281 struct st_reject_data {
282 	char *vendor;
283 	char *model;
284 	char *rev;
285 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
286 };
287 
288 static struct st_reject_data reject_list[] = {
289 	/* {"XXX", "Yy-", "", NULL},  example */
290 	SIGS_FROM_OSST,
291 	{NULL, }};
292 
293 /* If the device signature is on the list of incompatible drives, the
294    function returns a pointer to the name of the correct driver (if known) */
295 static char * st_incompatible(struct scsi_device* SDp)
296 {
297 	struct st_reject_data *rp;
298 
299 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
300 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
301 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
302 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
303 			if (rp->driver_hint)
304 				return rp->driver_hint;
305 			else
306 				return "unknown";
307 		}
308 	return NULL;
309 }
310 
311 
312 #define st_printk(prefix, t, fmt, a...) \
313 	sdev_prefix_printk(prefix, (t)->device, (t)->name, fmt, ##a)
314 #ifdef DEBUG
315 #define DEBC_printk(t, fmt, a...) \
316 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
317 #else
318 #define DEBC_printk(t, fmt, a...)
319 #endif
320 
321 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
322 {
323 	const u8 *ucp;
324 	const u8 *sense = SRpnt->sense;
325 
326 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
327 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
328 	s->flags = 0;
329 
330 	if (s->have_sense) {
331 		s->deferred = 0;
332 		s->remainder_valid =
333 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
334 		switch (sense[0] & 0x7f) {
335 		case 0x71:
336 			s->deferred = 1;
337 			fallthrough;
338 		case 0x70:
339 			s->fixed_format = 1;
340 			s->flags = sense[2] & 0xe0;
341 			break;
342 		case 0x73:
343 			s->deferred = 1;
344 			fallthrough;
345 		case 0x72:
346 			s->fixed_format = 0;
347 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
348 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
349 			break;
350 		}
351 	}
352 }
353 
354 
355 /* Convert the result to success code */
356 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
357 {
358 	int result = SRpnt->result;
359 	u8 scode;
360 	DEB(const char *stp;)
361 	char *name = STp->name;
362 	struct st_cmdstatus *cmdstatp;
363 
364 	if (!result)
365 		return 0;
366 
367 	cmdstatp = &STp->buffer->cmdstat;
368 	st_analyze_sense(SRpnt, cmdstatp);
369 
370 	if (cmdstatp->have_sense)
371 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
372 	else
373 		scode = 0;
374 
375 	DEB(
376 	if (debugging) {
377 		st_printk(ST_DEB_MSG, STp,
378 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
379 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
380 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
381 		if (cmdstatp->have_sense)
382 			__scsi_print_sense(STp->device, name,
383 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
384 	} ) /* end DEB */
385 	if (!debugging) { /* Abnormal conditions for tape */
386 		if (!cmdstatp->have_sense)
387 			st_printk(KERN_WARNING, STp,
388 			       "Error %x (driver bt 0, host bt 0x%x).\n",
389 			       result, host_byte(result));
390 		else if (cmdstatp->have_sense &&
391 			 scode != NO_SENSE &&
392 			 scode != RECOVERED_ERROR &&
393 			 /* scode != UNIT_ATTENTION && */
394 			 scode != BLANK_CHECK &&
395 			 scode != VOLUME_OVERFLOW &&
396 			 SRpnt->cmd[0] != MODE_SENSE &&
397 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
398 
399 			__scsi_print_sense(STp->device, name,
400 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
401 		}
402 	}
403 
404 	if (cmdstatp->fixed_format &&
405 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
406 		if (STp->cln_sense_value)
407 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
408 					       STp->cln_sense_mask) == STp->cln_sense_value);
409 		else
410 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
411 					       STp->cln_sense_mask) != 0);
412 	}
413 	if (cmdstatp->have_sense &&
414 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
415 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
416 	if (cmdstatp->have_sense && scode == UNIT_ATTENTION && cmdstatp->sense_hdr.asc == 0x29)
417 		STp->pos_unknown = 1; /* ASC => power on / reset */
418 
419 	STp->pos_unknown |= STp->device->was_reset;
420 
421 	if (cmdstatp->have_sense &&
422 	    scode == RECOVERED_ERROR
423 #if ST_RECOVERED_WRITE_FATAL
424 	    && SRpnt->cmd[0] != WRITE_6
425 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
426 #endif
427 	    ) {
428 		STp->recover_count++;
429 		STp->recover_reg++;
430 
431 		DEB(
432 		if (debugging) {
433 			if (SRpnt->cmd[0] == READ_6)
434 				stp = "read";
435 			else if (SRpnt->cmd[0] == WRITE_6)
436 				stp = "write";
437 			else
438 				stp = "ioctl";
439 			st_printk(ST_DEB_MSG, STp,
440 				  "Recovered %s error (%d).\n",
441 				  stp, STp->recover_count);
442 		} ) /* end DEB */
443 
444 		if (cmdstatp->flags == 0)
445 			return 0;
446 	}
447 	return (-EIO);
448 }
449 
450 static struct st_request *st_allocate_request(struct scsi_tape *stp)
451 {
452 	struct st_request *streq;
453 
454 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
455 	if (streq)
456 		streq->stp = stp;
457 	else {
458 		st_printk(KERN_ERR, stp,
459 			  "Can't get SCSI request.\n");
460 		if (signal_pending(current))
461 			stp->buffer->syscall_result = -EINTR;
462 		else
463 			stp->buffer->syscall_result = -EBUSY;
464 	}
465 
466 	return streq;
467 }
468 
469 static void st_release_request(struct st_request *streq)
470 {
471 	kfree(streq);
472 }
473 
474 static void st_do_stats(struct scsi_tape *STp, struct request *req)
475 {
476 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
477 	ktime_t now;
478 
479 	now = ktime_get();
480 	if (scmd->cmnd[0] == WRITE_6) {
481 		now = ktime_sub(now, STp->stats->write_time);
482 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
483 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
484 		atomic64_inc(&STp->stats->write_cnt);
485 		if (scmd->result) {
486 			atomic64_add(atomic_read(&STp->stats->last_write_size)
487 				- STp->buffer->cmdstat.residual,
488 				&STp->stats->write_byte_cnt);
489 			if (STp->buffer->cmdstat.residual > 0)
490 				atomic64_inc(&STp->stats->resid_cnt);
491 		} else
492 			atomic64_add(atomic_read(&STp->stats->last_write_size),
493 				&STp->stats->write_byte_cnt);
494 	} else if (scmd->cmnd[0] == READ_6) {
495 		now = ktime_sub(now, STp->stats->read_time);
496 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
497 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
498 		atomic64_inc(&STp->stats->read_cnt);
499 		if (scmd->result) {
500 			atomic64_add(atomic_read(&STp->stats->last_read_size)
501 				- STp->buffer->cmdstat.residual,
502 				&STp->stats->read_byte_cnt);
503 			if (STp->buffer->cmdstat.residual > 0)
504 				atomic64_inc(&STp->stats->resid_cnt);
505 		} else
506 			atomic64_add(atomic_read(&STp->stats->last_read_size),
507 				&STp->stats->read_byte_cnt);
508 	} else {
509 		now = ktime_sub(now, STp->stats->other_time);
510 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
511 		atomic64_inc(&STp->stats->other_cnt);
512 	}
513 	atomic64_dec(&STp->stats->in_flight);
514 }
515 
516 static enum rq_end_io_ret st_scsi_execute_end(struct request *req,
517 					      blk_status_t status)
518 {
519 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
520 	struct st_request *SRpnt = req->end_io_data;
521 	struct scsi_tape *STp = SRpnt->stp;
522 	struct bio *tmp;
523 
524 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = scmd->result;
525 	STp->buffer->cmdstat.residual = scmd->resid_len;
526 
527 	st_do_stats(STp, req);
528 
529 	tmp = SRpnt->bio;
530 	if (scmd->sense_len)
531 		memcpy(SRpnt->sense, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
532 	if (SRpnt->waiting)
533 		complete(SRpnt->waiting);
534 
535 	blk_rq_unmap_user(tmp);
536 	blk_mq_free_request(req);
537 	return RQ_END_IO_NONE;
538 }
539 
540 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
541 			   int data_direction, void *buffer, unsigned bufflen,
542 			   int timeout, int retries)
543 {
544 	struct request *req;
545 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
546 	int err = 0;
547 	struct scsi_tape *STp = SRpnt->stp;
548 	struct scsi_cmnd *scmd;
549 
550 	req = scsi_alloc_request(SRpnt->stp->device->request_queue,
551 			data_direction == DMA_TO_DEVICE ?
552 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
553 	if (IS_ERR(req))
554 		return PTR_ERR(req);
555 	scmd = blk_mq_rq_to_pdu(req);
556 	req->rq_flags |= RQF_QUIET;
557 
558 	mdata->null_mapped = 1;
559 
560 	if (bufflen) {
561 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
562 				      GFP_KERNEL);
563 		if (err) {
564 			blk_mq_free_request(req);
565 			return err;
566 		}
567 	}
568 
569 	atomic64_inc(&STp->stats->in_flight);
570 	if (cmd[0] == WRITE_6) {
571 		atomic_set(&STp->stats->last_write_size, bufflen);
572 		STp->stats->write_time = ktime_get();
573 	} else if (cmd[0] == READ_6) {
574 		atomic_set(&STp->stats->last_read_size, bufflen);
575 		STp->stats->read_time = ktime_get();
576 	} else {
577 		STp->stats->other_time = ktime_get();
578 	}
579 
580 	SRpnt->bio = req->bio;
581 	scmd->cmd_len = COMMAND_SIZE(cmd[0]);
582 	memcpy(scmd->cmnd, cmd, scmd->cmd_len);
583 	req->timeout = timeout;
584 	scmd->allowed = retries;
585 	req->end_io = st_scsi_execute_end;
586 	req->end_io_data = SRpnt;
587 
588 	blk_execute_rq_nowait(req, true);
589 	return 0;
590 }
591 
592 /* Do the scsi command. Waits until command performed if do_wait is true.
593    Otherwise write_behind_check() is used to check that the command
594    has finished. */
595 static struct st_request *
596 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
597 	   int bytes, int direction, int timeout, int retries, int do_wait)
598 {
599 	struct completion *waiting;
600 	struct rq_map_data *mdata = &STp->buffer->map_data;
601 	int ret;
602 
603 	/* if async, make sure there's no command outstanding */
604 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
605 		st_printk(KERN_ERR, STp,
606 			  "Async command already active.\n");
607 		if (signal_pending(current))
608 			(STp->buffer)->syscall_result = (-EINTR);
609 		else
610 			(STp->buffer)->syscall_result = (-EBUSY);
611 		return NULL;
612 	}
613 
614 	if (!SRpnt) {
615 		SRpnt = st_allocate_request(STp);
616 		if (!SRpnt)
617 			return NULL;
618 	}
619 
620 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
621 	   which IO is outstanding. It's nulled out when the IO completes. */
622 	if (!do_wait)
623 		(STp->buffer)->last_SRpnt = SRpnt;
624 
625 	waiting = &STp->wait;
626 	init_completion(waiting);
627 	SRpnt->waiting = waiting;
628 
629 	if (STp->buffer->do_dio) {
630 		mdata->page_order = 0;
631 		mdata->nr_entries = STp->buffer->sg_segs;
632 		mdata->pages = STp->buffer->mapped_pages;
633 	} else {
634 		mdata->page_order = STp->buffer->reserved_page_order;
635 		mdata->nr_entries =
636 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
637 		mdata->pages = STp->buffer->reserved_pages;
638 		mdata->offset = 0;
639 	}
640 
641 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
642 	STp->buffer->cmdstat.have_sense = 0;
643 	STp->buffer->syscall_result = 0;
644 
645 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
646 			      retries);
647 	if (ret) {
648 		/* could not allocate the buffer or request was too large */
649 		(STp->buffer)->syscall_result = (-EBUSY);
650 		(STp->buffer)->last_SRpnt = NULL;
651 	} else if (do_wait) {
652 		wait_for_completion(waiting);
653 		SRpnt->waiting = NULL;
654 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
655 	}
656 
657 	return SRpnt;
658 }
659 
660 
661 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
662    write has been correct but EOM early warning reached, -EIO if write ended in
663    error or zero if write successful. Asynchronous writes are used only in
664    variable block mode. */
665 static int write_behind_check(struct scsi_tape * STp)
666 {
667 	int retval = 0;
668 	struct st_buffer *STbuffer;
669 	struct st_partstat *STps;
670 	struct st_cmdstatus *cmdstatp;
671 	struct st_request *SRpnt;
672 
673 	STbuffer = STp->buffer;
674 	if (!STbuffer->writing)
675 		return 0;
676 
677 	DEB(
678 	if (STp->write_pending)
679 		STp->nbr_waits++;
680 	else
681 		STp->nbr_finished++;
682 	) /* end DEB */
683 
684 	wait_for_completion(&(STp->wait));
685 	SRpnt = STbuffer->last_SRpnt;
686 	STbuffer->last_SRpnt = NULL;
687 	SRpnt->waiting = NULL;
688 
689 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
690 	st_release_request(SRpnt);
691 
692 	STbuffer->buffer_bytes -= STbuffer->writing;
693 	STps = &(STp->ps[STp->partition]);
694 	if (STps->drv_block >= 0) {
695 		if (STp->block_size == 0)
696 			STps->drv_block++;
697 		else
698 			STps->drv_block += STbuffer->writing / STp->block_size;
699 	}
700 
701 	cmdstatp = &STbuffer->cmdstat;
702 	if (STbuffer->syscall_result) {
703 		retval = -EIO;
704 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
705 		    (cmdstatp->flags & SENSE_EOM) &&
706 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
707 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
708 			/* EOM at write-behind, has all data been written? */
709 			if (!cmdstatp->remainder_valid ||
710 			    cmdstatp->uremainder64 == 0)
711 				retval = -ENOSPC;
712 		}
713 		if (retval == -EIO)
714 			STps->drv_block = -1;
715 	}
716 	STbuffer->writing = 0;
717 
718 	DEB(if (debugging && retval)
719 		    st_printk(ST_DEB_MSG, STp,
720 				"Async write error %x, return value %d.\n",
721 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
722 
723 	return retval;
724 }
725 
726 
727 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
728    it messes up the block number). */
729 static int cross_eof(struct scsi_tape * STp, int forward)
730 {
731 	struct st_request *SRpnt;
732 	unsigned char cmd[MAX_COMMAND_SIZE];
733 
734 	cmd[0] = SPACE;
735 	cmd[1] = 0x01;		/* Space FileMarks */
736 	if (forward) {
737 		cmd[2] = cmd[3] = 0;
738 		cmd[4] = 1;
739 	} else
740 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
741 	cmd[5] = 0;
742 
743 	DEBC_printk(STp, "Stepping over filemark %s.\n",
744 		    forward ? "forward" : "backward");
745 
746 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
747 			   STp->device->request_queue->rq_timeout,
748 			   MAX_RETRIES, 1);
749 	if (!SRpnt)
750 		return (STp->buffer)->syscall_result;
751 
752 	st_release_request(SRpnt);
753 	SRpnt = NULL;
754 
755 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
756 		st_printk(KERN_ERR, STp,
757 			  "Stepping over filemark %s failed.\n",
758 			  forward ? "forward" : "backward");
759 
760 	return (STp->buffer)->syscall_result;
761 }
762 
763 
764 /* Flush the write buffer (never need to write if variable blocksize). */
765 static int st_flush_write_buffer(struct scsi_tape * STp)
766 {
767 	int transfer, blks;
768 	int result;
769 	unsigned char cmd[MAX_COMMAND_SIZE];
770 	struct st_request *SRpnt;
771 	struct st_partstat *STps;
772 
773 	result = write_behind_check(STp);
774 	if (result)
775 		return result;
776 
777 	result = 0;
778 	if (STp->dirty == 1) {
779 
780 		transfer = STp->buffer->buffer_bytes;
781 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
782 
783 		memset(cmd, 0, MAX_COMMAND_SIZE);
784 		cmd[0] = WRITE_6;
785 		cmd[1] = 1;
786 		blks = transfer / STp->block_size;
787 		cmd[2] = blks >> 16;
788 		cmd[3] = blks >> 8;
789 		cmd[4] = blks;
790 
791 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
792 				   STp->device->request_queue->rq_timeout,
793 				   MAX_WRITE_RETRIES, 1);
794 		if (!SRpnt)
795 			return (STp->buffer)->syscall_result;
796 
797 		STps = &(STp->ps[STp->partition]);
798 		if ((STp->buffer)->syscall_result != 0) {
799 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
800 
801 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
802 			    (cmdstatp->flags & SENSE_EOM) &&
803 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
804 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
805 			    (!cmdstatp->remainder_valid ||
806 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
807 				STp->dirty = 0;
808 				(STp->buffer)->buffer_bytes = 0;
809 				if (STps->drv_block >= 0)
810 					STps->drv_block += blks;
811 				result = (-ENOSPC);
812 			} else {
813 				st_printk(KERN_ERR, STp, "Error on flush.\n");
814 				STps->drv_block = (-1);
815 				result = (-EIO);
816 			}
817 		} else {
818 			if (STps->drv_block >= 0)
819 				STps->drv_block += blks;
820 			STp->dirty = 0;
821 			(STp->buffer)->buffer_bytes = 0;
822 		}
823 		st_release_request(SRpnt);
824 		SRpnt = NULL;
825 	}
826 	return result;
827 }
828 
829 
830 /* Flush the tape buffer. The tape will be positioned correctly unless
831    seek_next is true. */
832 static int flush_buffer(struct scsi_tape *STp, int seek_next)
833 {
834 	int backspace, result;
835 	struct st_partstat *STps;
836 
837 	/*
838 	 * If there was a bus reset, block further access
839 	 * to this device.
840 	 */
841 	if (STp->pos_unknown)
842 		return (-EIO);
843 
844 	if (STp->ready != ST_READY)
845 		return 0;
846 	STps = &(STp->ps[STp->partition]);
847 	if (STps->rw == ST_WRITING)	/* Writing */
848 		return st_flush_write_buffer(STp);
849 
850 	if (STp->block_size == 0)
851 		return 0;
852 
853 	backspace = ((STp->buffer)->buffer_bytes +
854 		     (STp->buffer)->read_pointer) / STp->block_size -
855 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
856 	    STp->block_size;
857 	(STp->buffer)->buffer_bytes = 0;
858 	(STp->buffer)->read_pointer = 0;
859 	result = 0;
860 	if (!seek_next) {
861 		if (STps->eof == ST_FM_HIT) {
862 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
863 			if (!result)
864 				STps->eof = ST_NOEOF;
865 			else {
866 				if (STps->drv_file >= 0)
867 					STps->drv_file++;
868 				STps->drv_block = 0;
869 			}
870 		}
871 		if (!result && backspace > 0)
872 			result = st_int_ioctl(STp, MTBSR, backspace);
873 	} else if (STps->eof == ST_FM_HIT) {
874 		if (STps->drv_file >= 0)
875 			STps->drv_file++;
876 		STps->drv_block = 0;
877 		STps->eof = ST_NOEOF;
878 	}
879 	return result;
880 
881 }
882 
883 /* Set the mode parameters */
884 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
885 {
886 	int set_it = 0;
887 	unsigned long arg;
888 
889 	if (!STp->density_changed &&
890 	    STm->default_density >= 0 &&
891 	    STm->default_density != STp->density) {
892 		arg = STm->default_density;
893 		set_it = 1;
894 	} else
895 		arg = STp->density;
896 	arg <<= MT_ST_DENSITY_SHIFT;
897 	if (!STp->blksize_changed &&
898 	    STm->default_blksize >= 0 &&
899 	    STm->default_blksize != STp->block_size) {
900 		arg |= STm->default_blksize;
901 		set_it = 1;
902 	} else
903 		arg |= STp->block_size;
904 	if (set_it &&
905 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
906 		st_printk(KERN_WARNING, STp,
907 			  "Can't set default block size to %d bytes "
908 			  "and density %x.\n",
909 			  STm->default_blksize, STm->default_density);
910 		if (modes_defined)
911 			return (-EINVAL);
912 	}
913 	return 0;
914 }
915 
916 
917 /* Lock or unlock the drive door. Don't use when st_request allocated. */
918 static int do_door_lock(struct scsi_tape * STp, int do_lock)
919 {
920 	int retval;
921 
922 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
923 
924 	retval = scsi_set_medium_removal(STp->device,
925 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
926 	if (!retval)
927 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
928 	else
929 		STp->door_locked = ST_LOCK_FAILS;
930 	return retval;
931 }
932 
933 
934 /* Set the internal state after reset */
935 static void reset_state(struct scsi_tape *STp)
936 {
937 	int i;
938 	struct st_partstat *STps;
939 
940 	STp->pos_unknown = 0;
941 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
942 		STps = &(STp->ps[i]);
943 		STps->rw = ST_IDLE;
944 		STps->eof = ST_NOEOF;
945 		STps->at_sm = 0;
946 		STps->last_block_valid = 0;
947 		STps->drv_block = -1;
948 		STps->drv_file = -1;
949 	}
950 	if (STp->can_partitions) {
951 		STp->partition = find_partition(STp);
952 		if (STp->partition < 0)
953 			STp->partition = 0;
954 		STp->new_partition = STp->partition;
955 	}
956 }
957 
958 /* Test if the drive is ready. Returns either one of the codes below or a negative system
959    error code. */
960 #define CHKRES_READY       0
961 #define CHKRES_NEW_SESSION 1
962 #define CHKRES_NOT_READY   2
963 #define CHKRES_NO_TAPE     3
964 
965 #define MAX_ATTENTIONS    10
966 
967 static int test_ready(struct scsi_tape *STp, int do_wait)
968 {
969 	int attentions, waits, max_wait, scode;
970 	int retval = CHKRES_READY, new_session = 0;
971 	unsigned char cmd[MAX_COMMAND_SIZE];
972 	struct st_request *SRpnt = NULL;
973 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
974 
975 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
976 
977 	for (attentions=waits=0; ; ) {
978 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
979 		cmd[0] = TEST_UNIT_READY;
980 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
981 				   STp->long_timeout, MAX_READY_RETRIES, 1);
982 
983 		if (!SRpnt) {
984 			retval = (STp->buffer)->syscall_result;
985 			break;
986 		}
987 
988 		if (cmdstatp->have_sense) {
989 
990 			scode = cmdstatp->sense_hdr.sense_key;
991 
992 			if (scode == UNIT_ATTENTION) { /* New media? */
993 				new_session = 1;
994 				if (attentions < MAX_ATTENTIONS) {
995 					attentions++;
996 					continue;
997 				}
998 				else {
999 					retval = (-EIO);
1000 					break;
1001 				}
1002 			}
1003 
1004 			if (scode == NOT_READY) {
1005 				if (waits < max_wait) {
1006 					if (msleep_interruptible(1000)) {
1007 						retval = (-EINTR);
1008 						break;
1009 					}
1010 					waits++;
1011 					continue;
1012 				}
1013 				else {
1014 					if ((STp->device)->scsi_level >= SCSI_2 &&
1015 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1016 						retval = CHKRES_NO_TAPE;
1017 					else
1018 						retval = CHKRES_NOT_READY;
1019 					break;
1020 				}
1021 			}
1022 		}
1023 
1024 		retval = (STp->buffer)->syscall_result;
1025 		if (!retval)
1026 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1027 		break;
1028 	}
1029 
1030 	if (SRpnt != NULL)
1031 		st_release_request(SRpnt);
1032 	return retval;
1033 }
1034 
1035 
1036 /* See if the drive is ready and gather information about the tape. Return values:
1037    < 0   negative error code from errno.h
1038    0     drive ready
1039    1     drive not ready (possibly no tape)
1040 */
1041 static int check_tape(struct scsi_tape *STp, struct file *filp)
1042 {
1043 	int i, retval, new_session = 0, do_wait;
1044 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1045 	unsigned short st_flags = filp->f_flags;
1046 	struct st_request *SRpnt = NULL;
1047 	struct st_modedef *STm;
1048 	struct st_partstat *STps;
1049 	struct inode *inode = file_inode(filp);
1050 	int mode = TAPE_MODE(inode);
1051 
1052 	STp->ready = ST_READY;
1053 
1054 	if (mode != STp->current_mode) {
1055 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1056 			    STp->current_mode, mode);
1057 		new_session = 1;
1058 		STp->current_mode = mode;
1059 	}
1060 	STm = &(STp->modes[STp->current_mode]);
1061 
1062 	saved_cleaning = STp->cleaning_req;
1063 	STp->cleaning_req = 0;
1064 
1065 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1066 	retval = test_ready(STp, do_wait);
1067 
1068 	if (retval < 0)
1069 	    goto err_out;
1070 
1071 	if (retval == CHKRES_NEW_SESSION) {
1072 		STp->pos_unknown = 0;
1073 		STp->partition = STp->new_partition = 0;
1074 		if (STp->can_partitions)
1075 			STp->nbr_partitions = 1; /* This guess will be updated later
1076                                                     if necessary */
1077 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1078 			STps = &(STp->ps[i]);
1079 			STps->rw = ST_IDLE;
1080 			STps->eof = ST_NOEOF;
1081 			STps->at_sm = 0;
1082 			STps->last_block_valid = 0;
1083 			STps->drv_block = 0;
1084 			STps->drv_file = 0;
1085 		}
1086 		new_session = 1;
1087 	}
1088 	else {
1089 		STp->cleaning_req |= saved_cleaning;
1090 
1091 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1092 			if (retval == CHKRES_NO_TAPE)
1093 				STp->ready = ST_NO_TAPE;
1094 			else
1095 				STp->ready = ST_NOT_READY;
1096 
1097 			STp->density = 0;	/* Clear the erroneous "residue" */
1098 			STp->write_prot = 0;
1099 			STp->block_size = 0;
1100 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1101 			STp->partition = STp->new_partition = 0;
1102 			STp->door_locked = ST_UNLOCKED;
1103 			return CHKRES_NOT_READY;
1104 		}
1105 	}
1106 
1107 	if (STp->omit_blklims)
1108 		STp->min_block = STp->max_block = (-1);
1109 	else {
1110 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1111 		cmd[0] = READ_BLOCK_LIMITS;
1112 
1113 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1114 				   STp->device->request_queue->rq_timeout,
1115 				   MAX_READY_RETRIES, 1);
1116 		if (!SRpnt) {
1117 			retval = (STp->buffer)->syscall_result;
1118 			goto err_out;
1119 		}
1120 
1121 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1122 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1123 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1124 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1125 			    (STp->buffer)->b_data[5];
1126 			if ( DEB( debugging || ) !STp->inited)
1127 				st_printk(KERN_INFO, STp,
1128 					  "Block limits %d - %d bytes.\n",
1129 					  STp->min_block, STp->max_block);
1130 		} else {
1131 			STp->min_block = STp->max_block = (-1);
1132 			DEBC_printk(STp, "Can't read block limits.\n");
1133 		}
1134 	}
1135 
1136 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1137 	cmd[0] = MODE_SENSE;
1138 	cmd[4] = 12;
1139 
1140 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1141 			   STp->device->request_queue->rq_timeout,
1142 			   MAX_READY_RETRIES, 1);
1143 	if (!SRpnt) {
1144 		retval = (STp->buffer)->syscall_result;
1145 		goto err_out;
1146 	}
1147 
1148 	if ((STp->buffer)->syscall_result != 0) {
1149 		DEBC_printk(STp, "No Mode Sense.\n");
1150 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1151 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1152 		STp->drv_write_prot = 0;
1153 	} else {
1154 		DEBC_printk(STp,"Mode sense. Length %d, "
1155 			    "medium %x, WBS %x, BLL %d\n",
1156 			    (STp->buffer)->b_data[0],
1157 			    (STp->buffer)->b_data[1],
1158 			    (STp->buffer)->b_data[2],
1159 			    (STp->buffer)->b_data[3]);
1160 
1161 		if ((STp->buffer)->b_data[3] >= 8) {
1162 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1163 			STp->density = (STp->buffer)->b_data[4];
1164 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1165 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1166 			DEBC_printk(STp, "Density %x, tape length: %x, "
1167 				    "drv buffer: %d\n",
1168 				    STp->density,
1169 				    (STp->buffer)->b_data[5] * 65536 +
1170 				    (STp->buffer)->b_data[6] * 256 +
1171 				    (STp->buffer)->b_data[7],
1172 				    STp->drv_buffer);
1173 		}
1174 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1175 		if (!STp->drv_buffer && STp->immediate_filemark) {
1176 			st_printk(KERN_WARNING, STp,
1177 				  "non-buffered tape: disabling "
1178 				  "writing immediate filemarks\n");
1179 			STp->immediate_filemark = 0;
1180 		}
1181 	}
1182 	st_release_request(SRpnt);
1183 	SRpnt = NULL;
1184 	STp->inited = 1;
1185 
1186 	if (STp->block_size > 0)
1187 		(STp->buffer)->buffer_blocks =
1188 			(STp->buffer)->buffer_size / STp->block_size;
1189 	else
1190 		(STp->buffer)->buffer_blocks = 1;
1191 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1192 
1193 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1194 		    STp->block_size, (STp->buffer)->buffer_size,
1195 		    (STp->buffer)->buffer_blocks);
1196 
1197 	if (STp->drv_write_prot) {
1198 		STp->write_prot = 1;
1199 
1200 		DEBC_printk(STp, "Write protected\n");
1201 
1202 		if (do_wait &&
1203 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1204 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1205 			retval = (-EROFS);
1206 			goto err_out;
1207 		}
1208 	}
1209 
1210 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1211 		/* This code is reached when the device is opened for the first time
1212 		   after the driver has been initialized with tape in the drive and the
1213 		   partition support has been enabled. */
1214 		DEBC_printk(STp, "Updating partition number in status.\n");
1215 		if ((STp->partition = find_partition(STp)) < 0) {
1216 			retval = STp->partition;
1217 			goto err_out;
1218 		}
1219 		STp->new_partition = STp->partition;
1220 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1221 	}
1222 
1223 	if (new_session) {	/* Change the drive parameters for the new mode */
1224 		STp->density_changed = STp->blksize_changed = 0;
1225 		STp->compression_changed = 0;
1226 		if (!(STm->defaults_for_writes) &&
1227 		    (retval = set_mode_densblk(STp, STm)) < 0)
1228 		    goto err_out;
1229 
1230 		if (STp->default_drvbuffer != 0xff) {
1231 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1232 				st_printk(KERN_WARNING, STp,
1233 					  "Can't set default drive "
1234 					  "buffering to %d.\n",
1235 					  STp->default_drvbuffer);
1236 		}
1237 	}
1238 
1239 	return CHKRES_READY;
1240 
1241  err_out:
1242 	return retval;
1243 }
1244 
1245 
1246 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1247    module count. */
1248 static int st_open(struct inode *inode, struct file *filp)
1249 {
1250 	int i, retval = (-EIO);
1251 	int resumed = 0;
1252 	struct scsi_tape *STp;
1253 	struct st_partstat *STps;
1254 	int dev = TAPE_NR(inode);
1255 
1256 	/*
1257 	 * We really want to do nonseekable_open(inode, filp); here, but some
1258 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1259 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1260 	 */
1261 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1262 
1263 	if (!(STp = scsi_tape_get(dev))) {
1264 		return -ENXIO;
1265 	}
1266 
1267 	filp->private_data = STp;
1268 
1269 	spin_lock(&st_use_lock);
1270 	if (STp->in_use) {
1271 		spin_unlock(&st_use_lock);
1272 		DEBC_printk(STp, "Device already in use.\n");
1273 		scsi_tape_put(STp);
1274 		return (-EBUSY);
1275 	}
1276 
1277 	STp->in_use = 1;
1278 	spin_unlock(&st_use_lock);
1279 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1280 
1281 	if (scsi_autopm_get_device(STp->device) < 0) {
1282 		retval = -EIO;
1283 		goto err_out;
1284 	}
1285 	resumed = 1;
1286 	if (!scsi_block_when_processing_errors(STp->device)) {
1287 		retval = (-ENXIO);
1288 		goto err_out;
1289 	}
1290 
1291 	/* See that we have at least a one page buffer available */
1292 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE)) {
1293 		st_printk(KERN_WARNING, STp,
1294 			  "Can't allocate one page tape buffer.\n");
1295 		retval = (-EOVERFLOW);
1296 		goto err_out;
1297 	}
1298 
1299 	(STp->buffer)->cleared = 0;
1300 	(STp->buffer)->writing = 0;
1301 	(STp->buffer)->syscall_result = 0;
1302 
1303 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1304 
1305 	STp->dirty = 0;
1306 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1307 		STps = &(STp->ps[i]);
1308 		STps->rw = ST_IDLE;
1309 	}
1310 	STp->try_dio_now = STp->try_dio;
1311 	STp->recover_count = 0;
1312 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1313 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1314 
1315 	retval = check_tape(STp, filp);
1316 	if (retval < 0)
1317 		goto err_out;
1318 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1319 	    retval != CHKRES_READY) {
1320 		if (STp->ready == NO_TAPE)
1321 			retval = (-ENOMEDIUM);
1322 		else
1323 			retval = (-EIO);
1324 		goto err_out;
1325 	}
1326 	return 0;
1327 
1328  err_out:
1329 	normalize_buffer(STp->buffer);
1330 	spin_lock(&st_use_lock);
1331 	STp->in_use = 0;
1332 	spin_unlock(&st_use_lock);
1333 	if (resumed)
1334 		scsi_autopm_put_device(STp->device);
1335 	scsi_tape_put(STp);
1336 	return retval;
1337 
1338 }
1339 
1340 
1341 /* Flush the tape buffer before close */
1342 static int st_flush(struct file *filp, fl_owner_t id)
1343 {
1344 	int result = 0, result2;
1345 	unsigned char cmd[MAX_COMMAND_SIZE];
1346 	struct st_request *SRpnt;
1347 	struct scsi_tape *STp = filp->private_data;
1348 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1349 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1350 
1351 	if (file_count(filp) > 1)
1352 		return 0;
1353 
1354 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1355 		result = st_flush_write_buffer(STp);
1356 		if (result != 0 && result != (-ENOSPC))
1357 			goto out;
1358 	}
1359 
1360 	if (STp->can_partitions &&
1361 	    (result2 = switch_partition(STp)) < 0) {
1362 		DEBC_printk(STp, "switch_partition at close failed.\n");
1363 		if (result == 0)
1364 			result = result2;
1365 		goto out;
1366 	}
1367 
1368 	DEBC( if (STp->nbr_requests)
1369 		st_printk(KERN_DEBUG, STp,
1370 			  "Number of r/w requests %d, dio used in %d, "
1371 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1372 			  STp->nbr_pages));
1373 
1374 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1375 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1376 
1377 #if DEBUG
1378 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1379 			    STp->nbr_waits, STp->nbr_finished);
1380 #endif
1381 		memset(cmd, 0, MAX_COMMAND_SIZE);
1382 		cmd[0] = WRITE_FILEMARKS;
1383 		if (STp->immediate_filemark)
1384 			cmd[1] = 1;
1385 		cmd[4] = 1 + STp->two_fm;
1386 
1387 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1388 				   STp->device->request_queue->rq_timeout,
1389 				   MAX_WRITE_RETRIES, 1);
1390 		if (!SRpnt) {
1391 			result = (STp->buffer)->syscall_result;
1392 			goto out;
1393 		}
1394 
1395 		if (STp->buffer->syscall_result == 0 ||
1396 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1397 		     (cmdstatp->flags & SENSE_EOM) &&
1398 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1399 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1400 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1401 			/* Write successful at EOM */
1402 			st_release_request(SRpnt);
1403 			SRpnt = NULL;
1404 			if (STps->drv_file >= 0)
1405 				STps->drv_file++;
1406 			STps->drv_block = 0;
1407 			if (STp->two_fm)
1408 				cross_eof(STp, 0);
1409 			STps->eof = ST_FM;
1410 		}
1411 		else { /* Write error */
1412 			st_release_request(SRpnt);
1413 			SRpnt = NULL;
1414 			st_printk(KERN_ERR, STp,
1415 				  "Error on write filemark.\n");
1416 			if (result == 0)
1417 				result = (-EIO);
1418 		}
1419 
1420 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1421 	} else if (!STp->rew_at_close) {
1422 		STps = &(STp->ps[STp->partition]);
1423 		if (!STm->sysv || STps->rw != ST_READING) {
1424 			if (STp->can_bsr)
1425 				result = flush_buffer(STp, 0);
1426 			else if (STps->eof == ST_FM_HIT) {
1427 				result = cross_eof(STp, 0);
1428 				if (result) {
1429 					if (STps->drv_file >= 0)
1430 						STps->drv_file++;
1431 					STps->drv_block = 0;
1432 					STps->eof = ST_FM;
1433 				} else
1434 					STps->eof = ST_NOEOF;
1435 			}
1436 		} else if ((STps->eof == ST_NOEOF &&
1437 			    !(result = cross_eof(STp, 1))) ||
1438 			   STps->eof == ST_FM_HIT) {
1439 			if (STps->drv_file >= 0)
1440 				STps->drv_file++;
1441 			STps->drv_block = 0;
1442 			STps->eof = ST_FM;
1443 		}
1444 	}
1445 
1446       out:
1447 	if (STp->rew_at_close) {
1448 		result2 = st_int_ioctl(STp, MTREW, 1);
1449 		if (result == 0)
1450 			result = result2;
1451 	}
1452 	return result;
1453 }
1454 
1455 
1456 /* Close the device and release it. BKL is not needed: this is the only thread
1457    accessing this tape. */
1458 static int st_release(struct inode *inode, struct file *filp)
1459 {
1460 	struct scsi_tape *STp = filp->private_data;
1461 
1462 	if (STp->door_locked == ST_LOCKED_AUTO)
1463 		do_door_lock(STp, 0);
1464 
1465 	normalize_buffer(STp->buffer);
1466 	spin_lock(&st_use_lock);
1467 	STp->in_use = 0;
1468 	spin_unlock(&st_use_lock);
1469 	scsi_autopm_put_device(STp->device);
1470 	scsi_tape_put(STp);
1471 
1472 	return 0;
1473 }
1474 
1475 /* The checks common to both reading and writing */
1476 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1477 {
1478 	ssize_t retval = 0;
1479 
1480 	/*
1481 	 * If we are in the middle of error recovery, don't let anyone
1482 	 * else try and use this device.  Also, if error recovery fails, it
1483 	 * may try and take the device offline, in which case all further
1484 	 * access to the device is prohibited.
1485 	 */
1486 	if (!scsi_block_when_processing_errors(STp->device)) {
1487 		retval = (-ENXIO);
1488 		goto out;
1489 	}
1490 
1491 	if (STp->ready != ST_READY) {
1492 		if (STp->ready == ST_NO_TAPE)
1493 			retval = (-ENOMEDIUM);
1494 		else
1495 			retval = (-EIO);
1496 		goto out;
1497 	}
1498 
1499 	if (! STp->modes[STp->current_mode].defined) {
1500 		retval = (-ENXIO);
1501 		goto out;
1502 	}
1503 
1504 
1505 	/*
1506 	 * If there was a bus reset, block further access
1507 	 * to this device.
1508 	 */
1509 	if (STp->pos_unknown) {
1510 		retval = (-EIO);
1511 		goto out;
1512 	}
1513 
1514 	if (count == 0)
1515 		goto out;
1516 
1517 	DEB(
1518 	if (!STp->in_use) {
1519 		st_printk(ST_DEB_MSG, STp,
1520 			  "Incorrect device.\n");
1521 		retval = (-EIO);
1522 		goto out;
1523 	} ) /* end DEB */
1524 
1525 	if (STp->can_partitions &&
1526 	    (retval = switch_partition(STp)) < 0)
1527 		goto out;
1528 
1529 	if (STp->block_size == 0 && STp->max_block > 0 &&
1530 	    (count < STp->min_block || count > STp->max_block)) {
1531 		retval = (-EINVAL);
1532 		goto out;
1533 	}
1534 
1535 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1536 	    !do_door_lock(STp, 1))
1537 		STp->door_locked = ST_LOCKED_AUTO;
1538 
1539  out:
1540 	return retval;
1541 }
1542 
1543 
1544 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1545 			   size_t count, int is_read)
1546 {
1547 	int i, bufsize, retval = 0;
1548 	struct st_buffer *STbp = STp->buffer;
1549 
1550 	if (is_read)
1551 		i = STp->try_dio_now && try_rdio;
1552 	else
1553 		i = STp->try_dio_now && try_wdio;
1554 
1555 	if (i && ((unsigned long)buf & queue_dma_alignment(
1556 					STp->device->request_queue)) == 0) {
1557 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1558 				       count, (is_read ? READ : WRITE));
1559 		if (i > 0) {
1560 			STbp->do_dio = i;
1561 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1562 		}
1563 		else
1564 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1565 		STbp->sg_segs = STbp->do_dio;
1566 		DEB(
1567 		     if (STbp->do_dio) {
1568 			STp->nbr_dio++;
1569 			STp->nbr_pages += STbp->do_dio;
1570 		     }
1571 		)
1572 	} else
1573 		STbp->do_dio = 0;
1574 	DEB( STp->nbr_requests++; )
1575 
1576 	if (!STbp->do_dio) {
1577 		if (STp->block_size)
1578 			bufsize = STp->block_size > st_fixed_buffer_size ?
1579 				STp->block_size : st_fixed_buffer_size;
1580 		else {
1581 			bufsize = count;
1582 			/* Make sure that data from previous user is not leaked even if
1583 			   HBA does not return correct residual */
1584 			if (is_read && STp->sili && !STbp->cleared)
1585 				clear_buffer(STbp);
1586 		}
1587 
1588 		if (bufsize > STbp->buffer_size &&
1589 		    !enlarge_buffer(STbp, bufsize)) {
1590 			st_printk(KERN_WARNING, STp,
1591 				  "Can't allocate %d byte tape buffer.\n",
1592 				  bufsize);
1593 			retval = (-EOVERFLOW);
1594 			goto out;
1595 		}
1596 		if (STp->block_size)
1597 			STbp->buffer_blocks = bufsize / STp->block_size;
1598 	}
1599 
1600  out:
1601 	return retval;
1602 }
1603 
1604 
1605 /* Can be called more than once after each setup_buffer() */
1606 static void release_buffering(struct scsi_tape *STp, int is_read)
1607 {
1608 	struct st_buffer *STbp;
1609 
1610 	STbp = STp->buffer;
1611 	if (STbp->do_dio) {
1612 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1613 		STbp->do_dio = 0;
1614 		STbp->sg_segs = 0;
1615 	}
1616 }
1617 
1618 
1619 /* Write command */
1620 static ssize_t
1621 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1622 {
1623 	ssize_t total;
1624 	ssize_t i, do_count, blks, transfer;
1625 	ssize_t retval;
1626 	int undone, retry_eot = 0, scode;
1627 	int async_write;
1628 	unsigned char cmd[MAX_COMMAND_SIZE];
1629 	const char __user *b_point;
1630 	struct st_request *SRpnt = NULL;
1631 	struct scsi_tape *STp = filp->private_data;
1632 	struct st_modedef *STm;
1633 	struct st_partstat *STps;
1634 	struct st_buffer *STbp;
1635 
1636 	if (mutex_lock_interruptible(&STp->lock))
1637 		return -ERESTARTSYS;
1638 
1639 	retval = rw_checks(STp, filp, count);
1640 	if (retval || count == 0)
1641 		goto out;
1642 
1643 	/* Write must be integral number of blocks */
1644 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1645 		st_printk(KERN_WARNING, STp,
1646 			  "Write not multiple of tape block size.\n");
1647 		retval = (-EINVAL);
1648 		goto out;
1649 	}
1650 
1651 	STm = &(STp->modes[STp->current_mode]);
1652 	STps = &(STp->ps[STp->partition]);
1653 
1654 	if (STp->write_prot) {
1655 		retval = (-EACCES);
1656 		goto out;
1657 	}
1658 
1659 
1660 	if (STps->rw == ST_READING) {
1661 		retval = flush_buffer(STp, 0);
1662 		if (retval)
1663 			goto out;
1664 		STps->rw = ST_WRITING;
1665 	} else if (STps->rw != ST_WRITING &&
1666 		   STps->drv_file == 0 && STps->drv_block == 0) {
1667 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1668 			goto out;
1669 		if (STm->default_compression != ST_DONT_TOUCH &&
1670 		    !(STp->compression_changed)) {
1671 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1672 				st_printk(KERN_WARNING, STp,
1673 					  "Can't set default compression.\n");
1674 				if (modes_defined) {
1675 					retval = (-EINVAL);
1676 					goto out;
1677 				}
1678 			}
1679 		}
1680 	}
1681 
1682 	STbp = STp->buffer;
1683 	i = write_behind_check(STp);
1684 	if (i) {
1685 		if (i == -ENOSPC)
1686 			STps->eof = ST_EOM_OK;
1687 		else
1688 			STps->eof = ST_EOM_ERROR;
1689 	}
1690 
1691 	if (STps->eof == ST_EOM_OK) {
1692 		STps->eof = ST_EOD_1;  /* allow next write */
1693 		retval = (-ENOSPC);
1694 		goto out;
1695 	}
1696 	else if (STps->eof == ST_EOM_ERROR) {
1697 		retval = (-EIO);
1698 		goto out;
1699 	}
1700 
1701 	/* Check the buffer readability in cases where copy_user might catch
1702 	   the problems after some tape movement. */
1703 	if (STp->block_size != 0 &&
1704 	    !STbp->do_dio &&
1705 	    (copy_from_user(&i, buf, 1) != 0 ||
1706 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1707 		retval = (-EFAULT);
1708 		goto out;
1709 	}
1710 
1711 	retval = setup_buffering(STp, buf, count, 0);
1712 	if (retval)
1713 		goto out;
1714 
1715 	total = count;
1716 
1717 	memset(cmd, 0, MAX_COMMAND_SIZE);
1718 	cmd[0] = WRITE_6;
1719 	cmd[1] = (STp->block_size != 0);
1720 
1721 	STps->rw = ST_WRITING;
1722 
1723 	b_point = buf;
1724 	while (count > 0 && !retry_eot) {
1725 
1726 		if (STbp->do_dio) {
1727 			do_count = count;
1728 		}
1729 		else {
1730 			if (STp->block_size == 0)
1731 				do_count = count;
1732 			else {
1733 				do_count = STbp->buffer_blocks * STp->block_size -
1734 					STbp->buffer_bytes;
1735 				if (do_count > count)
1736 					do_count = count;
1737 			}
1738 
1739 			i = append_to_buffer(b_point, STbp, do_count);
1740 			if (i) {
1741 				retval = i;
1742 				goto out;
1743 			}
1744 		}
1745 		count -= do_count;
1746 		b_point += do_count;
1747 
1748 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1749 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1750 
1751 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1752 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1753 		    STbp->buffer_bytes < STbp->buffer_size) {
1754 			STp->dirty = 1;
1755 			/* Don't write a buffer that is not full enough. */
1756 			if (!async_write && count == 0)
1757 				break;
1758 		}
1759 
1760 	retry_write:
1761 		if (STp->block_size == 0)
1762 			blks = transfer = do_count;
1763 		else {
1764 			if (!STbp->do_dio)
1765 				blks = STbp->buffer_bytes;
1766 			else
1767 				blks = do_count;
1768 			blks /= STp->block_size;
1769 			transfer = blks * STp->block_size;
1770 		}
1771 		cmd[2] = blks >> 16;
1772 		cmd[3] = blks >> 8;
1773 		cmd[4] = blks;
1774 
1775 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1776 				   STp->device->request_queue->rq_timeout,
1777 				   MAX_WRITE_RETRIES, !async_write);
1778 		if (!SRpnt) {
1779 			retval = STbp->syscall_result;
1780 			goto out;
1781 		}
1782 		if (async_write && !STbp->syscall_result) {
1783 			STbp->writing = transfer;
1784 			STp->dirty = !(STbp->writing ==
1785 				       STbp->buffer_bytes);
1786 			SRpnt = NULL;  /* Prevent releasing this request! */
1787 			DEB( STp->write_pending = 1; )
1788 			break;
1789 		}
1790 
1791 		if (STbp->syscall_result != 0) {
1792 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1793 
1794 			DEBC_printk(STp, "Error on write:\n");
1795 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1796 				scode = cmdstatp->sense_hdr.sense_key;
1797 				if (cmdstatp->remainder_valid)
1798 					undone = (int)cmdstatp->uremainder64;
1799 				else if (STp->block_size == 0 &&
1800 					 scode == VOLUME_OVERFLOW)
1801 					undone = transfer;
1802 				else
1803 					undone = 0;
1804 				if (STp->block_size != 0)
1805 					undone *= STp->block_size;
1806 				if (undone <= do_count) {
1807 					/* Only data from this write is not written */
1808 					count += undone;
1809 					b_point -= undone;
1810 					do_count -= undone;
1811 					if (STp->block_size)
1812 						blks = (transfer - undone) / STp->block_size;
1813 					STps->eof = ST_EOM_OK;
1814 					/* Continue in fixed block mode if all written
1815 					   in this request but still something left to write
1816 					   (retval left to zero)
1817 					*/
1818 					if (STp->block_size == 0 ||
1819 					    undone > 0 || count == 0)
1820 						retval = (-ENOSPC); /* EOM within current request */
1821 					DEBC_printk(STp, "EOM with %d "
1822 						    "bytes unwritten.\n",
1823 						    (int)count);
1824 				} else {
1825 					/* EOT within data buffered earlier (possible only
1826 					   in fixed block mode without direct i/o) */
1827 					if (!retry_eot && !cmdstatp->deferred &&
1828 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1829 						move_buffer_data(STp->buffer, transfer - undone);
1830 						retry_eot = 1;
1831 						if (STps->drv_block >= 0) {
1832 							STps->drv_block += (transfer - undone) /
1833 								STp->block_size;
1834 						}
1835 						STps->eof = ST_EOM_OK;
1836 						DEBC_printk(STp, "Retry "
1837 							    "write of %d "
1838 							    "bytes at EOM.\n",
1839 							    STp->buffer->buffer_bytes);
1840 						goto retry_write;
1841 					}
1842 					else {
1843 						/* Either error within data buffered by driver or
1844 						   failed retry */
1845 						count -= do_count;
1846 						blks = do_count = 0;
1847 						STps->eof = ST_EOM_ERROR;
1848 						STps->drv_block = (-1); /* Too cautious? */
1849 						retval = (-EIO);	/* EOM for old data */
1850 						DEBC_printk(STp, "EOM with "
1851 							    "lost data.\n");
1852 					}
1853 				}
1854 			} else {
1855 				count += do_count;
1856 				STps->drv_block = (-1);		/* Too cautious? */
1857 				retval = STbp->syscall_result;
1858 			}
1859 
1860 		}
1861 
1862 		if (STps->drv_block >= 0) {
1863 			if (STp->block_size == 0)
1864 				STps->drv_block += (do_count > 0);
1865 			else
1866 				STps->drv_block += blks;
1867 		}
1868 
1869 		STbp->buffer_bytes = 0;
1870 		STp->dirty = 0;
1871 
1872 		if (retval || retry_eot) {
1873 			if (count < total)
1874 				retval = total - count;
1875 			goto out;
1876 		}
1877 	}
1878 
1879 	if (STps->eof == ST_EOD_1)
1880 		STps->eof = ST_EOM_OK;
1881 	else if (STps->eof != ST_EOM_OK)
1882 		STps->eof = ST_NOEOF;
1883 	retval = total - count;
1884 
1885  out:
1886 	if (SRpnt != NULL)
1887 		st_release_request(SRpnt);
1888 	release_buffering(STp, 0);
1889 	mutex_unlock(&STp->lock);
1890 
1891 	return retval;
1892 }
1893 
1894 /* Read data from the tape. Returns zero in the normal case, one if the
1895    eof status has changed, and the negative error code in case of a
1896    fatal error. Otherwise updates the buffer and the eof state.
1897 
1898    Does release user buffer mapping if it is set.
1899 */
1900 static long read_tape(struct scsi_tape *STp, long count,
1901 		      struct st_request ** aSRpnt)
1902 {
1903 	int transfer, blks, bytes;
1904 	unsigned char cmd[MAX_COMMAND_SIZE];
1905 	struct st_request *SRpnt;
1906 	struct st_modedef *STm;
1907 	struct st_partstat *STps;
1908 	struct st_buffer *STbp;
1909 	int retval = 0;
1910 
1911 	if (count == 0)
1912 		return 0;
1913 
1914 	STm = &(STp->modes[STp->current_mode]);
1915 	STps = &(STp->ps[STp->partition]);
1916 	if (STps->eof == ST_FM_HIT)
1917 		return 1;
1918 	STbp = STp->buffer;
1919 
1920 	if (STp->block_size == 0)
1921 		blks = bytes = count;
1922 	else {
1923 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1924 			blks = (STp->buffer)->buffer_blocks;
1925 			bytes = blks * STp->block_size;
1926 		} else {
1927 			bytes = count;
1928 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1929 				bytes = (STp->buffer)->buffer_size;
1930 			blks = bytes / STp->block_size;
1931 			bytes = blks * STp->block_size;
1932 		}
1933 	}
1934 
1935 	memset(cmd, 0, MAX_COMMAND_SIZE);
1936 	cmd[0] = READ_6;
1937 	cmd[1] = (STp->block_size != 0);
1938 	if (!cmd[1] && STp->sili)
1939 		cmd[1] |= 2;
1940 	cmd[2] = blks >> 16;
1941 	cmd[3] = blks >> 8;
1942 	cmd[4] = blks;
1943 
1944 	SRpnt = *aSRpnt;
1945 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1946 			   STp->device->request_queue->rq_timeout,
1947 			   MAX_RETRIES, 1);
1948 	release_buffering(STp, 1);
1949 	*aSRpnt = SRpnt;
1950 	if (!SRpnt)
1951 		return STbp->syscall_result;
1952 
1953 	STbp->read_pointer = 0;
1954 	STps->at_sm = 0;
1955 
1956 	/* Something to check */
1957 	if (STbp->syscall_result) {
1958 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1959 
1960 		retval = 1;
1961 		DEBC_printk(STp,
1962 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1963 			    SRpnt->sense[0], SRpnt->sense[1],
1964 			    SRpnt->sense[2], SRpnt->sense[3],
1965 			    SRpnt->sense[4], SRpnt->sense[5],
1966 			    SRpnt->sense[6], SRpnt->sense[7]);
1967 		if (cmdstatp->have_sense) {
1968 
1969 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1970 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1971 
1972 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1973 				/* Compute the residual count */
1974 				if (cmdstatp->remainder_valid)
1975 					transfer = (int)cmdstatp->uremainder64;
1976 				else
1977 					transfer = 0;
1978 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1979 					if (STp->block_size == 0)
1980 						transfer = bytes;
1981 					/* Some drives set ILI with MEDIUM ERROR */
1982 					cmdstatp->flags &= ~SENSE_ILI;
1983 				}
1984 
1985 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1986 					if (STp->block_size == 0 &&
1987 					    transfer < 0) {
1988 						st_printk(KERN_NOTICE, STp,
1989 							  "Failed to read %d "
1990 							  "byte block with %d "
1991 							  "byte transfer.\n",
1992 							  bytes - transfer,
1993 							  bytes);
1994 						if (STps->drv_block >= 0)
1995 							STps->drv_block += 1;
1996 						STbp->buffer_bytes = 0;
1997 						return (-ENOMEM);
1998 					} else if (STp->block_size == 0) {
1999 						STbp->buffer_bytes = bytes - transfer;
2000 					} else {
2001 						st_release_request(SRpnt);
2002 						SRpnt = *aSRpnt = NULL;
2003 						if (transfer == blks) {	/* We did not get anything, error */
2004 							st_printk(KERN_NOTICE, STp,
2005 								  "Incorrect "
2006 								  "block size.\n");
2007 							if (STps->drv_block >= 0)
2008 								STps->drv_block += blks - transfer + 1;
2009 							st_int_ioctl(STp, MTBSR, 1);
2010 							return (-EIO);
2011 						}
2012 						/* We have some data, deliver it */
2013 						STbp->buffer_bytes = (blks - transfer) *
2014 						    STp->block_size;
2015 						DEBC_printk(STp, "ILI but "
2016 							    "enough data "
2017 							    "received %ld "
2018 							    "%d.\n", count,
2019 							    STbp->buffer_bytes);
2020 						if (STps->drv_block >= 0)
2021 							STps->drv_block += 1;
2022 						if (st_int_ioctl(STp, MTBSR, 1))
2023 							return (-EIO);
2024 					}
2025 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2026 					if (STps->eof != ST_FM_HIT)
2027 						STps->eof = ST_FM_HIT;
2028 					else
2029 						STps->eof = ST_EOD_2;
2030 					if (STp->block_size == 0)
2031 						STbp->buffer_bytes = 0;
2032 					else
2033 						STbp->buffer_bytes =
2034 						    bytes - transfer * STp->block_size;
2035 					DEBC_printk(STp, "EOF detected (%d "
2036 						    "bytes read).\n",
2037 						    STbp->buffer_bytes);
2038 				} else if (cmdstatp->flags & SENSE_EOM) {
2039 					if (STps->eof == ST_FM)
2040 						STps->eof = ST_EOD_1;
2041 					else
2042 						STps->eof = ST_EOM_OK;
2043 					if (STp->block_size == 0)
2044 						STbp->buffer_bytes = bytes - transfer;
2045 					else
2046 						STbp->buffer_bytes =
2047 						    bytes - transfer * STp->block_size;
2048 
2049 					DEBC_printk(STp, "EOM detected (%d "
2050 						    "bytes read).\n",
2051 						    STbp->buffer_bytes);
2052 				}
2053 			}
2054 			/* end of EOF, EOM, ILI test */
2055 			else {	/* nonzero sense key */
2056 				DEBC_printk(STp, "Tape error while reading.\n");
2057 				STps->drv_block = (-1);
2058 				if (STps->eof == ST_FM &&
2059 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2060 					DEBC_printk(STp, "Zero returned for "
2061 						    "first BLANK CHECK "
2062 						    "after EOF.\n");
2063 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2064 				} else	/* Some other extended sense code */
2065 					retval = (-EIO);
2066 			}
2067 
2068 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2069 				STbp->buffer_bytes = 0;
2070 		}
2071 		/* End of extended sense test */
2072 		else {		/* Non-extended sense */
2073 			retval = STbp->syscall_result;
2074 		}
2075 
2076 	}
2077 	/* End of error handling */
2078 	else {			/* Read successful */
2079 		STbp->buffer_bytes = bytes;
2080 		if (STp->sili) /* In fixed block mode residual is always zero here */
2081 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2082 	}
2083 
2084 	if (STps->drv_block >= 0) {
2085 		if (STp->block_size == 0)
2086 			STps->drv_block++;
2087 		else
2088 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2089 	}
2090 	return retval;
2091 }
2092 
2093 
2094 /* Read command */
2095 static ssize_t
2096 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2097 {
2098 	ssize_t total;
2099 	ssize_t retval = 0;
2100 	ssize_t i, transfer;
2101 	int special, do_dio = 0;
2102 	struct st_request *SRpnt = NULL;
2103 	struct scsi_tape *STp = filp->private_data;
2104 	struct st_modedef *STm;
2105 	struct st_partstat *STps;
2106 	struct st_buffer *STbp = STp->buffer;
2107 
2108 	if (mutex_lock_interruptible(&STp->lock))
2109 		return -ERESTARTSYS;
2110 
2111 	retval = rw_checks(STp, filp, count);
2112 	if (retval || count == 0)
2113 		goto out;
2114 
2115 	STm = &(STp->modes[STp->current_mode]);
2116 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2117 		if (!STm->do_read_ahead) {
2118 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2119 			goto out;
2120 		}
2121 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2122 	}
2123 
2124 	STps = &(STp->ps[STp->partition]);
2125 	if (STps->rw == ST_WRITING) {
2126 		retval = flush_buffer(STp, 0);
2127 		if (retval)
2128 			goto out;
2129 		STps->rw = ST_READING;
2130 	}
2131 	DEB(
2132 	if (debugging && STps->eof != ST_NOEOF)
2133 		st_printk(ST_DEB_MSG, STp,
2134 			  "EOF/EOM flag up (%d). Bytes %d\n",
2135 			  STps->eof, STbp->buffer_bytes);
2136 	) /* end DEB */
2137 
2138 	retval = setup_buffering(STp, buf, count, 1);
2139 	if (retval)
2140 		goto out;
2141 	do_dio = STbp->do_dio;
2142 
2143 	if (STbp->buffer_bytes == 0 &&
2144 	    STps->eof >= ST_EOD_1) {
2145 		if (STps->eof < ST_EOD) {
2146 			STps->eof += 1;
2147 			retval = 0;
2148 			goto out;
2149 		}
2150 		retval = (-EIO);	/* EOM or Blank Check */
2151 		goto out;
2152 	}
2153 
2154 	if (do_dio) {
2155 		/* Check the buffer writability before any tape movement. Don't alter
2156 		   buffer data. */
2157 		if (copy_from_user(&i, buf, 1) != 0 ||
2158 		    copy_to_user(buf, &i, 1) != 0 ||
2159 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2160 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2161 			retval = (-EFAULT);
2162 			goto out;
2163 		}
2164 	}
2165 
2166 	STps->rw = ST_READING;
2167 
2168 
2169 	/* Loop until enough data in buffer or a special condition found */
2170 	for (total = 0, special = 0; total < count && !special;) {
2171 
2172 		/* Get new data if the buffer is empty */
2173 		if (STbp->buffer_bytes == 0) {
2174 			special = read_tape(STp, count - total, &SRpnt);
2175 			if (special < 0) {	/* No need to continue read */
2176 				retval = special;
2177 				goto out;
2178 			}
2179 		}
2180 
2181 		/* Move the data from driver buffer to user buffer */
2182 		if (STbp->buffer_bytes > 0) {
2183 			DEB(
2184 			if (debugging && STps->eof != ST_NOEOF)
2185 				st_printk(ST_DEB_MSG, STp,
2186 					  "EOF up (%d). Left %d, needed %d.\n",
2187 					  STps->eof, STbp->buffer_bytes,
2188 					  (int)(count - total));
2189 			) /* end DEB */
2190 			transfer = STbp->buffer_bytes < count - total ?
2191 			    STbp->buffer_bytes : count - total;
2192 			if (!do_dio) {
2193 				i = from_buffer(STbp, buf, transfer);
2194 				if (i) {
2195 					retval = i;
2196 					goto out;
2197 				}
2198 			}
2199 			buf += transfer;
2200 			total += transfer;
2201 		}
2202 
2203 		if (STp->block_size == 0)
2204 			break;	/* Read only one variable length block */
2205 
2206 	}			/* for (total = 0, special = 0;
2207                                    total < count && !special; ) */
2208 
2209 	/* Change the eof state if no data from tape or buffer */
2210 	if (total == 0) {
2211 		if (STps->eof == ST_FM_HIT) {
2212 			STps->eof = ST_FM;
2213 			STps->drv_block = 0;
2214 			if (STps->drv_file >= 0)
2215 				STps->drv_file++;
2216 		} else if (STps->eof == ST_EOD_1) {
2217 			STps->eof = ST_EOD_2;
2218 			STps->drv_block = 0;
2219 			if (STps->drv_file >= 0)
2220 				STps->drv_file++;
2221 		} else if (STps->eof == ST_EOD_2)
2222 			STps->eof = ST_EOD;
2223 	} else if (STps->eof == ST_FM)
2224 		STps->eof = ST_NOEOF;
2225 	retval = total;
2226 
2227  out:
2228 	if (SRpnt != NULL) {
2229 		st_release_request(SRpnt);
2230 		SRpnt = NULL;
2231 	}
2232 	if (do_dio) {
2233 		release_buffering(STp, 1);
2234 		STbp->buffer_bytes = 0;
2235 	}
2236 	mutex_unlock(&STp->lock);
2237 
2238 	return retval;
2239 }
2240 
2241 
2242 
2243 DEB(
2244 /* Set the driver options */
2245 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2246 {
2247 	if (debugging) {
2248 		st_printk(KERN_INFO, STp,
2249 			  "Mode %d options: buffer writes: %d, "
2250 			  "async writes: %d, read ahead: %d\n",
2251 			  STp->current_mode, STm->do_buffer_writes,
2252 			  STm->do_async_writes, STm->do_read_ahead);
2253 		st_printk(KERN_INFO, STp,
2254 			  "    can bsr: %d, two FMs: %d, "
2255 			  "fast mteom: %d, auto lock: %d,\n",
2256 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2257 			  STp->do_auto_lock);
2258 		st_printk(KERN_INFO, STp,
2259 			  "    defs for wr: %d, no block limits: %d, "
2260 			  "partitions: %d, s2 log: %d\n",
2261 			  STm->defaults_for_writes, STp->omit_blklims,
2262 			  STp->can_partitions, STp->scsi2_logical);
2263 		st_printk(KERN_INFO, STp,
2264 			  "    sysv: %d nowait: %d sili: %d "
2265 			  "nowait_filemark: %d\n",
2266 			  STm->sysv, STp->immediate, STp->sili,
2267 			  STp->immediate_filemark);
2268 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2269 	}
2270 }
2271 	)
2272 
2273 
2274 static int st_set_options(struct scsi_tape *STp, long options)
2275 {
2276 	int value;
2277 	long code;
2278 	struct st_modedef *STm;
2279 	struct cdev *cd0, *cd1;
2280 	struct device *d0, *d1;
2281 
2282 	STm = &(STp->modes[STp->current_mode]);
2283 	if (!STm->defined) {
2284 		cd0 = STm->cdevs[0];
2285 		cd1 = STm->cdevs[1];
2286 		d0  = STm->devs[0];
2287 		d1  = STm->devs[1];
2288 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2289 		STm->cdevs[0] = cd0;
2290 		STm->cdevs[1] = cd1;
2291 		STm->devs[0]  = d0;
2292 		STm->devs[1]  = d1;
2293 		modes_defined = 1;
2294 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2295 			    STp->current_mode);
2296 	}
2297 
2298 	code = options & MT_ST_OPTIONS;
2299 	if (code == MT_ST_BOOLEANS) {
2300 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2301 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2302 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2303 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2304 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2305 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2306 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2307 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2308 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2309 		if ((STp->device)->scsi_level >= SCSI_2)
2310 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2311 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2312 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2313 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2314 		STm->sysv = (options & MT_ST_SYSV) != 0;
2315 		STp->sili = (options & MT_ST_SILI) != 0;
2316 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2317 		     st_log_options(STp, STm); )
2318 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2319 		value = (code == MT_ST_SETBOOLEANS);
2320 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2321 			STm->do_buffer_writes = value;
2322 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2323 			STm->do_async_writes = value;
2324 		if ((options & MT_ST_DEF_WRITES) != 0)
2325 			STm->defaults_for_writes = value;
2326 		if ((options & MT_ST_READ_AHEAD) != 0)
2327 			STm->do_read_ahead = value;
2328 		if ((options & MT_ST_TWO_FM) != 0)
2329 			STp->two_fm = value;
2330 		if ((options & MT_ST_FAST_MTEOM) != 0)
2331 			STp->fast_mteom = value;
2332 		if ((options & MT_ST_AUTO_LOCK) != 0)
2333 			STp->do_auto_lock = value;
2334 		if ((options & MT_ST_CAN_BSR) != 0)
2335 			STp->can_bsr = value;
2336 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2337 			STp->omit_blklims = value;
2338 		if ((STp->device)->scsi_level >= SCSI_2 &&
2339 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2340 			STp->can_partitions = value;
2341 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2342 			STp->scsi2_logical = value;
2343 		if ((options & MT_ST_NOWAIT) != 0)
2344 			STp->immediate = value;
2345 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2346 			STp->immediate_filemark = value;
2347 		if ((options & MT_ST_SYSV) != 0)
2348 			STm->sysv = value;
2349 		if ((options & MT_ST_SILI) != 0)
2350 			STp->sili = value;
2351 		DEB(
2352 		if ((options & MT_ST_DEBUGGING) != 0)
2353 			debugging = value;
2354 			st_log_options(STp, STm); )
2355 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2356 		/* Retained for compatibility */
2357 	} else if (code == MT_ST_DEF_BLKSIZE) {
2358 		value = (options & ~MT_ST_OPTIONS);
2359 		if (value == ~MT_ST_OPTIONS) {
2360 			STm->default_blksize = (-1);
2361 			DEBC_printk(STp, "Default block size disabled.\n");
2362 		} else {
2363 			STm->default_blksize = value;
2364 			DEBC_printk(STp,"Default block size set to "
2365 				    "%d bytes.\n", STm->default_blksize);
2366 			if (STp->ready == ST_READY) {
2367 				STp->blksize_changed = 0;
2368 				set_mode_densblk(STp, STm);
2369 			}
2370 		}
2371 	} else if (code == MT_ST_TIMEOUTS) {
2372 		value = (options & ~MT_ST_OPTIONS);
2373 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2374 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2375 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2376 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2377 		} else {
2378 			blk_queue_rq_timeout(STp->device->request_queue,
2379 					     value * HZ);
2380 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2381 				    value);
2382 		}
2383 	} else if (code == MT_ST_SET_CLN) {
2384 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2385 		if (value != 0 &&
2386 			(value < EXTENDED_SENSE_START ||
2387 				value >= SCSI_SENSE_BUFFERSIZE))
2388 			return (-EINVAL);
2389 		STp->cln_mode = value;
2390 		STp->cln_sense_mask = (options >> 8) & 0xff;
2391 		STp->cln_sense_value = (options >> 16) & 0xff;
2392 		st_printk(KERN_INFO, STp,
2393 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2394 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2395 	} else if (code == MT_ST_DEF_OPTIONS) {
2396 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2397 		value = (options & MT_ST_CLEAR_DEFAULT);
2398 		if (code == MT_ST_DEF_DENSITY) {
2399 			if (value == MT_ST_CLEAR_DEFAULT) {
2400 				STm->default_density = (-1);
2401 				DEBC_printk(STp,
2402 					    "Density default disabled.\n");
2403 			} else {
2404 				STm->default_density = value & 0xff;
2405 				DEBC_printk(STp, "Density default set to %x\n",
2406 					    STm->default_density);
2407 				if (STp->ready == ST_READY) {
2408 					STp->density_changed = 0;
2409 					set_mode_densblk(STp, STm);
2410 				}
2411 			}
2412 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2413 			if (value == MT_ST_CLEAR_DEFAULT) {
2414 				STp->default_drvbuffer = 0xff;
2415 				DEBC_printk(STp,
2416 					    "Drive buffer default disabled.\n");
2417 			} else {
2418 				STp->default_drvbuffer = value & 7;
2419 				DEBC_printk(STp,
2420 					    "Drive buffer default set to %x\n",
2421 					    STp->default_drvbuffer);
2422 				if (STp->ready == ST_READY)
2423 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2424 			}
2425 		} else if (code == MT_ST_DEF_COMPRESSION) {
2426 			if (value == MT_ST_CLEAR_DEFAULT) {
2427 				STm->default_compression = ST_DONT_TOUCH;
2428 				DEBC_printk(STp,
2429 					    "Compression default disabled.\n");
2430 			} else {
2431 				if ((value & 0xff00) != 0) {
2432 					STp->c_algo = (value & 0xff00) >> 8;
2433 					DEBC_printk(STp, "Compression "
2434 						    "algorithm set to 0x%x.\n",
2435 						    STp->c_algo);
2436 				}
2437 				if ((value & 0xff) != 0xff) {
2438 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2439 					DEBC_printk(STp, "Compression default "
2440 						    "set to %x\n",
2441 						    (value & 1));
2442 					if (STp->ready == ST_READY) {
2443 						STp->compression_changed = 0;
2444 						st_compression(STp, (STm->default_compression == ST_YES));
2445 					}
2446 				}
2447 			}
2448 		}
2449 	} else
2450 		return (-EIO);
2451 
2452 	return 0;
2453 }
2454 
2455 #define MODE_HEADER_LENGTH  4
2456 
2457 /* Mode header and page byte offsets */
2458 #define MH_OFF_DATA_LENGTH     0
2459 #define MH_OFF_MEDIUM_TYPE     1
2460 #define MH_OFF_DEV_SPECIFIC    2
2461 #define MH_OFF_BDESCS_LENGTH   3
2462 #define MP_OFF_PAGE_NBR        0
2463 #define MP_OFF_PAGE_LENGTH     1
2464 
2465 /* Mode header and page bit masks */
2466 #define MH_BIT_WP              0x80
2467 #define MP_MSK_PAGE_NBR        0x3f
2468 
2469 /* Don't return block descriptors */
2470 #define MODE_SENSE_OMIT_BDESCS 0x08
2471 
2472 #define MODE_SELECT_PAGE_FORMAT 0x10
2473 
2474 /* Read a mode page into the tape buffer. The block descriptors are included
2475    if incl_block_descs is true. The page control is ored to the page number
2476    parameter, if necessary. */
2477 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2478 {
2479 	unsigned char cmd[MAX_COMMAND_SIZE];
2480 	struct st_request *SRpnt;
2481 
2482 	memset(cmd, 0, MAX_COMMAND_SIZE);
2483 	cmd[0] = MODE_SENSE;
2484 	if (omit_block_descs)
2485 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2486 	cmd[2] = page;
2487 	cmd[4] = 255;
2488 
2489 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2490 			   STp->device->request_queue->rq_timeout, 0, 1);
2491 	if (SRpnt == NULL)
2492 		return (STp->buffer)->syscall_result;
2493 
2494 	st_release_request(SRpnt);
2495 
2496 	return STp->buffer->syscall_result;
2497 }
2498 
2499 
2500 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2501    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2502 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2503 {
2504 	int pgo;
2505 	unsigned char cmd[MAX_COMMAND_SIZE];
2506 	struct st_request *SRpnt;
2507 	int timeout;
2508 
2509 	memset(cmd, 0, MAX_COMMAND_SIZE);
2510 	cmd[0] = MODE_SELECT;
2511 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2512 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2513 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2514 
2515 	/* Clear reserved fields */
2516 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2517 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2518 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2519 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2520 
2521 	timeout = slow ?
2522 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2523 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2524 			   timeout, 0, 1);
2525 	if (SRpnt == NULL)
2526 		return (STp->buffer)->syscall_result;
2527 
2528 	st_release_request(SRpnt);
2529 
2530 	return STp->buffer->syscall_result;
2531 }
2532 
2533 
2534 #define COMPRESSION_PAGE        0x0f
2535 #define COMPRESSION_PAGE_LENGTH 16
2536 
2537 #define CP_OFF_DCE_DCC          2
2538 #define CP_OFF_C_ALGO           7
2539 
2540 #define DCE_MASK  0x80
2541 #define DCC_MASK  0x40
2542 #define RED_MASK  0x60
2543 
2544 
2545 /* Control the compression with mode page 15. Algorithm not changed if zero.
2546 
2547    The block descriptors are read and written because Sony SDT-7000 does not
2548    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2549    Including block descriptors should not cause any harm to other drives. */
2550 
2551 static int st_compression(struct scsi_tape * STp, int state)
2552 {
2553 	int retval;
2554 	int mpoffs;  /* Offset to mode page start */
2555 	unsigned char *b_data = (STp->buffer)->b_data;
2556 
2557 	if (STp->ready != ST_READY)
2558 		return (-EIO);
2559 
2560 	/* Read the current page contents */
2561 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2562 	if (retval) {
2563 		DEBC_printk(STp, "Compression mode page not supported.\n");
2564 		return (-EIO);
2565 	}
2566 
2567 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2568 	DEBC_printk(STp, "Compression state is %d.\n",
2569 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2570 
2571 	/* Check if compression can be changed */
2572 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2573 		DEBC_printk(STp, "Compression not supported.\n");
2574 		return (-EIO);
2575 	}
2576 
2577 	/* Do the change */
2578 	if (state) {
2579 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2580 		if (STp->c_algo != 0)
2581 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2582 	}
2583 	else {
2584 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2585 		if (STp->c_algo != 0)
2586 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2587 	}
2588 
2589 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2590 	if (retval) {
2591 		DEBC_printk(STp, "Compression change failed.\n");
2592 		return (-EIO);
2593 	}
2594 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2595 
2596 	STp->compression_changed = 1;
2597 	return 0;
2598 }
2599 
2600 
2601 /* Process the load and unload commands (does unload if the load code is zero) */
2602 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2603 {
2604 	int retval = (-EIO), timeout;
2605 	unsigned char cmd[MAX_COMMAND_SIZE];
2606 	struct st_partstat *STps;
2607 	struct st_request *SRpnt;
2608 
2609 	if (STp->ready != ST_READY && !load_code) {
2610 		if (STp->ready == ST_NO_TAPE)
2611 			return (-ENOMEDIUM);
2612 		else
2613 			return (-EIO);
2614 	}
2615 
2616 	memset(cmd, 0, MAX_COMMAND_SIZE);
2617 	cmd[0] = START_STOP;
2618 	if (load_code)
2619 		cmd[4] |= 1;
2620 	/*
2621 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2622 	 */
2623 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2624 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2625 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2626 			    (cmd[4]) ? "" : "un",
2627 			    load_code - MT_ST_HPLOADER_OFFSET);
2628 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2629 	}
2630 	if (STp->immediate) {
2631 		cmd[1] = 1;	/* Don't wait for completion */
2632 		timeout = STp->device->request_queue->rq_timeout;
2633 	}
2634 	else
2635 		timeout = STp->long_timeout;
2636 
2637 	DEBC(
2638 		if (!load_code)
2639 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2640 		else
2641 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2642 		);
2643 
2644 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2645 			   timeout, MAX_RETRIES, 1);
2646 	if (!SRpnt)
2647 		return (STp->buffer)->syscall_result;
2648 
2649 	retval = (STp->buffer)->syscall_result;
2650 	st_release_request(SRpnt);
2651 
2652 	if (!retval) {	/* SCSI command successful */
2653 
2654 		if (!load_code) {
2655 			STp->rew_at_close = 0;
2656 			STp->ready = ST_NO_TAPE;
2657 		}
2658 		else {
2659 			STp->rew_at_close = STp->autorew_dev;
2660 			retval = check_tape(STp, filp);
2661 			if (retval > 0)
2662 				retval = 0;
2663 		}
2664 	}
2665 	else {
2666 		STps = &(STp->ps[STp->partition]);
2667 		STps->drv_file = STps->drv_block = (-1);
2668 	}
2669 
2670 	return retval;
2671 }
2672 
2673 #if DEBUG
2674 #define ST_DEB_FORWARD  0
2675 #define ST_DEB_BACKWARD 1
2676 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2677 {
2678 	s32 sc;
2679 
2680 	if (!debugging)
2681 		return;
2682 
2683 	sc = sign_extend32(get_unaligned_be24(&cmd[2]), 23);
2684 	if (direction)
2685 		sc = -sc;
2686 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2687 		  direction ? "backward" : "forward", sc, units);
2688 }
2689 #else
2690 #define ST_DEB_FORWARD  0
2691 #define ST_DEB_BACKWARD 1
2692 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2693 #endif
2694 
2695 
2696 /* Internal ioctl function */
2697 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2698 {
2699 	int timeout;
2700 	long ltmp;
2701 	int ioctl_result;
2702 	int chg_eof = 1;
2703 	unsigned char cmd[MAX_COMMAND_SIZE];
2704 	struct st_request *SRpnt;
2705 	struct st_partstat *STps;
2706 	int fileno, blkno, at_sm, undone;
2707 	int datalen = 0, direction = DMA_NONE;
2708 
2709 	WARN_ON(STp->buffer->do_dio != 0);
2710 	if (STp->ready != ST_READY) {
2711 		if (STp->ready == ST_NO_TAPE)
2712 			return (-ENOMEDIUM);
2713 		else
2714 			return (-EIO);
2715 	}
2716 	timeout = STp->long_timeout;
2717 	STps = &(STp->ps[STp->partition]);
2718 	fileno = STps->drv_file;
2719 	blkno = STps->drv_block;
2720 	at_sm = STps->at_sm;
2721 
2722 	memset(cmd, 0, MAX_COMMAND_SIZE);
2723 	switch (cmd_in) {
2724 	case MTFSFM:
2725 		chg_eof = 0;	/* Changed from the FSF after this */
2726 		fallthrough;
2727 	case MTFSF:
2728 		cmd[0] = SPACE;
2729 		cmd[1] = 0x01;	/* Space FileMarks */
2730 		cmd[2] = (arg >> 16);
2731 		cmd[3] = (arg >> 8);
2732 		cmd[4] = arg;
2733 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2734 		if (fileno >= 0)
2735 			fileno += arg;
2736 		blkno = 0;
2737 		at_sm &= (arg == 0);
2738 		break;
2739 	case MTBSFM:
2740 		chg_eof = 0;	/* Changed from the FSF after this */
2741 		fallthrough;
2742 	case MTBSF:
2743 		cmd[0] = SPACE;
2744 		cmd[1] = 0x01;	/* Space FileMarks */
2745 		ltmp = (-arg);
2746 		cmd[2] = (ltmp >> 16);
2747 		cmd[3] = (ltmp >> 8);
2748 		cmd[4] = ltmp;
2749 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2750 		if (fileno >= 0)
2751 			fileno -= arg;
2752 		blkno = (-1);	/* We can't know the block number */
2753 		at_sm &= (arg == 0);
2754 		break;
2755 	case MTFSR:
2756 		cmd[0] = SPACE;
2757 		cmd[1] = 0x00;	/* Space Blocks */
2758 		cmd[2] = (arg >> 16);
2759 		cmd[3] = (arg >> 8);
2760 		cmd[4] = arg;
2761 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2762 		if (blkno >= 0)
2763 			blkno += arg;
2764 		at_sm &= (arg == 0);
2765 		break;
2766 	case MTBSR:
2767 		cmd[0] = SPACE;
2768 		cmd[1] = 0x00;	/* Space Blocks */
2769 		ltmp = (-arg);
2770 		cmd[2] = (ltmp >> 16);
2771 		cmd[3] = (ltmp >> 8);
2772 		cmd[4] = ltmp;
2773 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2774 		if (blkno >= 0)
2775 			blkno -= arg;
2776 		at_sm &= (arg == 0);
2777 		break;
2778 	case MTFSS:
2779 		cmd[0] = SPACE;
2780 		cmd[1] = 0x04;	/* Space Setmarks */
2781 		cmd[2] = (arg >> 16);
2782 		cmd[3] = (arg >> 8);
2783 		cmd[4] = arg;
2784 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2785 		if (arg != 0) {
2786 			blkno = fileno = (-1);
2787 			at_sm = 1;
2788 		}
2789 		break;
2790 	case MTBSS:
2791 		cmd[0] = SPACE;
2792 		cmd[1] = 0x04;	/* Space Setmarks */
2793 		ltmp = (-arg);
2794 		cmd[2] = (ltmp >> 16);
2795 		cmd[3] = (ltmp >> 8);
2796 		cmd[4] = ltmp;
2797 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2798 		if (arg != 0) {
2799 			blkno = fileno = (-1);
2800 			at_sm = 1;
2801 		}
2802 		break;
2803 	case MTWEOF:
2804 	case MTWEOFI:
2805 	case MTWSM:
2806 		if (STp->write_prot)
2807 			return (-EACCES);
2808 		cmd[0] = WRITE_FILEMARKS;
2809 		if (cmd_in == MTWSM)
2810 			cmd[1] = 2;
2811 		if (cmd_in == MTWEOFI ||
2812 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2813 			cmd[1] |= 1;
2814 		cmd[2] = (arg >> 16);
2815 		cmd[3] = (arg >> 8);
2816 		cmd[4] = arg;
2817 		timeout = STp->device->request_queue->rq_timeout;
2818 		DEBC(
2819 			if (cmd_in != MTWSM)
2820 				st_printk(ST_DEB_MSG, STp,
2821 					  "Writing %d filemarks.\n",
2822 					  cmd[2] * 65536 +
2823 					  cmd[3] * 256 +
2824 					  cmd[4]);
2825 			else
2826 				st_printk(ST_DEB_MSG, STp,
2827 					  "Writing %d setmarks.\n",
2828 					  cmd[2] * 65536 +
2829 					  cmd[3] * 256 +
2830 					  cmd[4]);
2831 		)
2832 		if (fileno >= 0)
2833 			fileno += arg;
2834 		blkno = 0;
2835 		at_sm = (cmd_in == MTWSM);
2836 		break;
2837 	case MTREW:
2838 		cmd[0] = REZERO_UNIT;
2839 		if (STp->immediate) {
2840 			cmd[1] = 1;	/* Don't wait for completion */
2841 			timeout = STp->device->request_queue->rq_timeout;
2842 		}
2843 		DEBC_printk(STp, "Rewinding tape.\n");
2844 		fileno = blkno = at_sm = 0;
2845 		break;
2846 	case MTNOP:
2847 		DEBC_printk(STp, "No op on tape.\n");
2848 		return 0;	/* Should do something ? */
2849 	case MTRETEN:
2850 		cmd[0] = START_STOP;
2851 		if (STp->immediate) {
2852 			cmd[1] = 1;	/* Don't wait for completion */
2853 			timeout = STp->device->request_queue->rq_timeout;
2854 		}
2855 		cmd[4] = 3;
2856 		DEBC_printk(STp, "Retensioning tape.\n");
2857 		fileno = blkno = at_sm = 0;
2858 		break;
2859 	case MTEOM:
2860 		if (!STp->fast_mteom) {
2861 			/* space to the end of tape */
2862 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2863 			fileno = STps->drv_file;
2864 			if (STps->eof >= ST_EOD_1)
2865 				return 0;
2866 			/* The next lines would hide the number of spaced FileMarks
2867 			   That's why I inserted the previous lines. I had no luck
2868 			   with detecting EOM with FSF, so we go now to EOM.
2869 			   Joerg Weule */
2870 		} else
2871 			fileno = (-1);
2872 		cmd[0] = SPACE;
2873 		cmd[1] = 3;
2874 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2875 		blkno = -1;
2876 		at_sm = 0;
2877 		break;
2878 	case MTERASE:
2879 		if (STp->write_prot)
2880 			return (-EACCES);
2881 		cmd[0] = ERASE;
2882 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2883 		if (STp->immediate) {
2884 			cmd[1] |= 2;	/* Don't wait for completion */
2885 			timeout = STp->device->request_queue->rq_timeout;
2886 		}
2887 		else
2888 			timeout = STp->long_timeout * 8;
2889 
2890 		DEBC_printk(STp, "Erasing tape.\n");
2891 		fileno = blkno = at_sm = 0;
2892 		break;
2893 	case MTSETBLK:		/* Set block length */
2894 	case MTSETDENSITY:	/* Set tape density */
2895 	case MTSETDRVBUFFER:	/* Set drive buffering */
2896 	case SET_DENS_AND_BLK:	/* Set density and block size */
2897 		chg_eof = 0;
2898 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2899 			return (-EIO);	/* Not allowed if data in buffer */
2900 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2901 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2902 		    STp->max_block > 0 &&
2903 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2904 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2905 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2906 			return (-EINVAL);
2907 		}
2908 		cmd[0] = MODE_SELECT;
2909 		if ((STp->use_pf & USE_PF))
2910 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2911 		cmd[4] = datalen = 12;
2912 		direction = DMA_TO_DEVICE;
2913 
2914 		memset((STp->buffer)->b_data, 0, 12);
2915 		if (cmd_in == MTSETDRVBUFFER)
2916 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2917 		else
2918 			(STp->buffer)->b_data[2] =
2919 			    STp->drv_buffer << 4;
2920 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2921 		if (cmd_in == MTSETDENSITY) {
2922 			(STp->buffer)->b_data[4] = arg;
2923 			STp->density_changed = 1;	/* At least we tried ;-) */
2924 		} else if (cmd_in == SET_DENS_AND_BLK)
2925 			(STp->buffer)->b_data[4] = arg >> 24;
2926 		else
2927 			(STp->buffer)->b_data[4] = STp->density;
2928 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2929 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2930 			if (cmd_in == MTSETBLK)
2931 				STp->blksize_changed = 1; /* At least we tried ;-) */
2932 		} else
2933 			ltmp = STp->block_size;
2934 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2935 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2936 		(STp->buffer)->b_data[11] = ltmp;
2937 		timeout = STp->device->request_queue->rq_timeout;
2938 		DEBC(
2939 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2940 				st_printk(ST_DEB_MSG, STp,
2941 					  "Setting block size to %d bytes.\n",
2942 					  (STp->buffer)->b_data[9] * 65536 +
2943 					  (STp->buffer)->b_data[10] * 256 +
2944 					  (STp->buffer)->b_data[11]);
2945 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2946 				st_printk(ST_DEB_MSG, STp,
2947 					  "Setting density code to %x.\n",
2948 					  (STp->buffer)->b_data[4]);
2949 			if (cmd_in == MTSETDRVBUFFER)
2950 				st_printk(ST_DEB_MSG, STp,
2951 					  "Setting drive buffer code to %d.\n",
2952 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2953 		)
2954 		break;
2955 	default:
2956 		return (-ENOSYS);
2957 	}
2958 
2959 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2960 			   timeout, MAX_RETRIES, 1);
2961 	if (!SRpnt)
2962 		return (STp->buffer)->syscall_result;
2963 
2964 	ioctl_result = (STp->buffer)->syscall_result;
2965 
2966 	if (!ioctl_result) {	/* SCSI command successful */
2967 		st_release_request(SRpnt);
2968 		SRpnt = NULL;
2969 		STps->drv_block = blkno;
2970 		STps->drv_file = fileno;
2971 		STps->at_sm = at_sm;
2972 
2973 		if (cmd_in == MTBSFM)
2974 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2975 		else if (cmd_in == MTFSFM)
2976 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2977 
2978 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2979 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2980 			if (STp->block_size != 0) {
2981 				(STp->buffer)->buffer_blocks =
2982 				    (STp->buffer)->buffer_size / STp->block_size;
2983 			}
2984 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2985 			if (cmd_in == SET_DENS_AND_BLK)
2986 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2987 		} else if (cmd_in == MTSETDRVBUFFER)
2988 			STp->drv_buffer = (arg & 7);
2989 		else if (cmd_in == MTSETDENSITY)
2990 			STp->density = arg;
2991 
2992 		if (cmd_in == MTEOM)
2993 			STps->eof = ST_EOD;
2994 		else if (cmd_in == MTFSF)
2995 			STps->eof = ST_FM;
2996 		else if (chg_eof)
2997 			STps->eof = ST_NOEOF;
2998 
2999 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
3000 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
3001 	} else { /* SCSI command was not completely successful. Don't return
3002                     from this block without releasing the SCSI command block! */
3003 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
3004 
3005 		if (cmdstatp->flags & SENSE_EOM) {
3006 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3007 			    cmd_in != MTBSR && cmd_in != MTBSS)
3008 				STps->eof = ST_EOM_OK;
3009 			STps->drv_block = 0;
3010 		}
3011 
3012 		if (cmdstatp->remainder_valid)
3013 			undone = (int)cmdstatp->uremainder64;
3014 		else
3015 			undone = 0;
3016 
3017 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3018 		    cmdstatp->have_sense &&
3019 		    (cmdstatp->flags & SENSE_EOM)) {
3020 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3021 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3022 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3023 				STps->eof = ST_NOEOF;
3024 			} else {  /* Writing EOF(s) failed */
3025 				if (fileno >= 0)
3026 					fileno -= undone;
3027 				if (undone < arg)
3028 					STps->eof = ST_NOEOF;
3029 			}
3030 			STps->drv_file = fileno;
3031 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3032 			if (fileno >= 0)
3033 				STps->drv_file = fileno - undone;
3034 			else
3035 				STps->drv_file = fileno;
3036 			STps->drv_block = -1;
3037 			STps->eof = ST_NOEOF;
3038 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3039 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3040 				undone = (-undone);
3041 			if (STps->drv_file >= 0)
3042 				STps->drv_file = fileno + undone;
3043 			STps->drv_block = 0;
3044 			STps->eof = ST_NOEOF;
3045 		} else if (cmd_in == MTFSR) {
3046 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3047 				if (STps->drv_file >= 0)
3048 					STps->drv_file++;
3049 				STps->drv_block = 0;
3050 				STps->eof = ST_FM;
3051 			} else {
3052 				if (blkno >= undone)
3053 					STps->drv_block = blkno - undone;
3054 				else
3055 					STps->drv_block = (-1);
3056 				STps->eof = ST_NOEOF;
3057 			}
3058 		} else if (cmd_in == MTBSR) {
3059 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3060 				STps->drv_file--;
3061 				STps->drv_block = (-1);
3062 			} else {
3063 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3064 					undone = (-undone);
3065 				if (STps->drv_block >= 0)
3066 					STps->drv_block = blkno + undone;
3067 			}
3068 			STps->eof = ST_NOEOF;
3069 		} else if (cmd_in == MTEOM) {
3070 			STps->drv_file = (-1);
3071 			STps->drv_block = (-1);
3072 			STps->eof = ST_EOD;
3073 		} else if (cmd_in == MTSETBLK ||
3074 			   cmd_in == MTSETDENSITY ||
3075 			   cmd_in == MTSETDRVBUFFER ||
3076 			   cmd_in == SET_DENS_AND_BLK) {
3077 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3078 			    !(STp->use_pf & PF_TESTED)) {
3079 				/* Try the other possible state of Page Format if not
3080 				   already tried */
3081 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3082 				st_release_request(SRpnt);
3083 				SRpnt = NULL;
3084 				return st_int_ioctl(STp, cmd_in, arg);
3085 			}
3086 		} else if (chg_eof)
3087 			STps->eof = ST_NOEOF;
3088 
3089 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3090 			STps->eof = ST_EOD;
3091 
3092 		st_release_request(SRpnt);
3093 		SRpnt = NULL;
3094 	}
3095 
3096 	return ioctl_result;
3097 }
3098 
3099 
3100 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3101    structure. */
3102 
3103 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3104 			int logical)
3105 {
3106 	int result;
3107 	unsigned char scmd[MAX_COMMAND_SIZE];
3108 	struct st_request *SRpnt;
3109 
3110 	if (STp->ready != ST_READY)
3111 		return (-EIO);
3112 
3113 	memset(scmd, 0, MAX_COMMAND_SIZE);
3114 	if ((STp->device)->scsi_level < SCSI_2) {
3115 		scmd[0] = QFA_REQUEST_BLOCK;
3116 		scmd[4] = 3;
3117 	} else {
3118 		scmd[0] = READ_POSITION;
3119 		if (!logical && !STp->scsi2_logical)
3120 			scmd[1] = 1;
3121 	}
3122 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3123 			   STp->device->request_queue->rq_timeout,
3124 			   MAX_READY_RETRIES, 1);
3125 	if (!SRpnt)
3126 		return (STp->buffer)->syscall_result;
3127 
3128 	if ((STp->buffer)->syscall_result != 0 ||
3129 	    (STp->device->scsi_level >= SCSI_2 &&
3130 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3131 		*block = *partition = 0;
3132 		DEBC_printk(STp, " Can't read tape position.\n");
3133 		result = (-EIO);
3134 	} else {
3135 		result = 0;
3136 		if ((STp->device)->scsi_level < SCSI_2) {
3137 			*block = ((STp->buffer)->b_data[0] << 16)
3138 			    + ((STp->buffer)->b_data[1] << 8)
3139 			    + (STp->buffer)->b_data[2];
3140 			*partition = 0;
3141 		} else {
3142 			*block = ((STp->buffer)->b_data[4] << 24)
3143 			    + ((STp->buffer)->b_data[5] << 16)
3144 			    + ((STp->buffer)->b_data[6] << 8)
3145 			    + (STp->buffer)->b_data[7];
3146 			*partition = (STp->buffer)->b_data[1];
3147 			if (((STp->buffer)->b_data[0] & 0x80) &&
3148 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3149 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3150 		}
3151 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3152 			    *block, *partition);
3153 	}
3154 	st_release_request(SRpnt);
3155 	SRpnt = NULL;
3156 
3157 	return result;
3158 }
3159 
3160 
3161 /* Set the tape block and partition. Negative partition means that only the
3162    block should be set in vendor specific way. */
3163 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3164 			int logical)
3165 {
3166 	struct st_partstat *STps;
3167 	int result, p;
3168 	unsigned int blk;
3169 	int timeout;
3170 	unsigned char scmd[MAX_COMMAND_SIZE];
3171 	struct st_request *SRpnt;
3172 
3173 	if (STp->ready != ST_READY)
3174 		return (-EIO);
3175 	timeout = STp->long_timeout;
3176 	STps = &(STp->ps[STp->partition]);
3177 
3178 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3179 		    block, partition);
3180 	DEB(if (partition < 0)
3181 		return (-EIO); )
3182 
3183 	/* Update the location at the partition we are leaving */
3184 	if ((!STp->can_partitions && partition != 0) ||
3185 	    partition >= ST_NBR_PARTITIONS)
3186 		return (-EINVAL);
3187 	if (partition != STp->partition) {
3188 		if (get_location(STp, &blk, &p, 1))
3189 			STps->last_block_valid = 0;
3190 		else {
3191 			STps->last_block_valid = 1;
3192 			STps->last_block_visited = blk;
3193 			DEBC_printk(STp, "Visited block %d for "
3194 				    "partition %d saved.\n",
3195 				    blk, STp->partition);
3196 		}
3197 	}
3198 
3199 	memset(scmd, 0, MAX_COMMAND_SIZE);
3200 	if ((STp->device)->scsi_level < SCSI_2) {
3201 		scmd[0] = QFA_SEEK_BLOCK;
3202 		scmd[2] = (block >> 16);
3203 		scmd[3] = (block >> 8);
3204 		scmd[4] = block;
3205 		scmd[5] = 0;
3206 	} else {
3207 		scmd[0] = SEEK_10;
3208 		scmd[3] = (block >> 24);
3209 		scmd[4] = (block >> 16);
3210 		scmd[5] = (block >> 8);
3211 		scmd[6] = block;
3212 		if (!logical && !STp->scsi2_logical)
3213 			scmd[1] = 4;
3214 		if (STp->partition != partition) {
3215 			scmd[1] |= 2;
3216 			scmd[8] = partition;
3217 			DEBC_printk(STp, "Trying to change partition "
3218 				    "from %d to %d\n", STp->partition,
3219 				    partition);
3220 		}
3221 	}
3222 	if (STp->immediate) {
3223 		scmd[1] |= 1;		/* Don't wait for completion */
3224 		timeout = STp->device->request_queue->rq_timeout;
3225 	}
3226 
3227 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3228 			   timeout, MAX_READY_RETRIES, 1);
3229 	if (!SRpnt)
3230 		return (STp->buffer)->syscall_result;
3231 
3232 	STps->drv_block = STps->drv_file = (-1);
3233 	STps->eof = ST_NOEOF;
3234 	if ((STp->buffer)->syscall_result != 0) {
3235 		result = (-EIO);
3236 		if (STp->can_partitions &&
3237 		    (STp->device)->scsi_level >= SCSI_2 &&
3238 		    (p = find_partition(STp)) >= 0)
3239 			STp->partition = p;
3240 	} else {
3241 		if (STp->can_partitions) {
3242 			STp->partition = partition;
3243 			STps = &(STp->ps[partition]);
3244 			if (!STps->last_block_valid ||
3245 			    STps->last_block_visited != block) {
3246 				STps->at_sm = 0;
3247 				STps->rw = ST_IDLE;
3248 			}
3249 		} else
3250 			STps->at_sm = 0;
3251 		if (block == 0)
3252 			STps->drv_block = STps->drv_file = 0;
3253 		result = 0;
3254 	}
3255 
3256 	st_release_request(SRpnt);
3257 	SRpnt = NULL;
3258 
3259 	return result;
3260 }
3261 
3262 
3263 /* Find the current partition number for the drive status. Called from open and
3264    returns either partition number of negative error code. */
3265 static int find_partition(struct scsi_tape *STp)
3266 {
3267 	int i, partition;
3268 	unsigned int block;
3269 
3270 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3271 		return i;
3272 	if (partition >= ST_NBR_PARTITIONS)
3273 		return (-EIO);
3274 	return partition;
3275 }
3276 
3277 
3278 /* Change the partition if necessary */
3279 static int switch_partition(struct scsi_tape *STp)
3280 {
3281 	struct st_partstat *STps;
3282 
3283 	if (STp->partition == STp->new_partition)
3284 		return 0;
3285 	STps = &(STp->ps[STp->new_partition]);
3286 	if (!STps->last_block_valid)
3287 		STps->last_block_visited = 0;
3288 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3289 }
3290 
3291 /* Functions for reading and writing the medium partition mode page. */
3292 
3293 #define PART_PAGE   0x11
3294 #define PART_PAGE_FIXED_LENGTH 8
3295 
3296 #define PP_OFF_MAX_ADD_PARTS   2
3297 #define PP_OFF_NBR_ADD_PARTS   3
3298 #define PP_OFF_FLAGS           4
3299 #define PP_OFF_PART_UNITS      6
3300 #define PP_OFF_RESERVED        7
3301 
3302 #define PP_BIT_IDP             0x20
3303 #define PP_BIT_FDP             0x80
3304 #define PP_MSK_PSUM_MB         0x10
3305 #define PP_MSK_PSUM_UNITS      0x18
3306 #define PP_MSK_POFM            0x04
3307 
3308 /* Get the number of partitions on the tape. As a side effect reads the
3309    mode page into the tape buffer. */
3310 static int nbr_partitions(struct scsi_tape *STp)
3311 {
3312 	int result;
3313 
3314 	if (STp->ready != ST_READY)
3315 		return (-EIO);
3316 
3317 	result = read_mode_page(STp, PART_PAGE, 1);
3318 
3319 	if (result) {
3320 		DEBC_printk(STp, "Can't read medium partition page.\n");
3321 		result = (-EIO);
3322 	} else {
3323 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3324 					      PP_OFF_NBR_ADD_PARTS] + 1;
3325 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3326 	}
3327 
3328 	return result;
3329 }
3330 
3331 
3332 static int format_medium(struct scsi_tape *STp, int format)
3333 {
3334 	int result = 0;
3335 	int timeout = STp->long_timeout;
3336 	unsigned char scmd[MAX_COMMAND_SIZE];
3337 	struct st_request *SRpnt;
3338 
3339 	memset(scmd, 0, MAX_COMMAND_SIZE);
3340 	scmd[0] = FORMAT_UNIT;
3341 	scmd[2] = format;
3342 	if (STp->immediate) {
3343 		scmd[1] |= 1;		/* Don't wait for completion */
3344 		timeout = STp->device->request_queue->rq_timeout;
3345 	}
3346 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3347 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3348 			   timeout, MAX_RETRIES, 1);
3349 	if (!SRpnt)
3350 		result = STp->buffer->syscall_result;
3351 	return result;
3352 }
3353 
3354 
3355 /* Partition the tape into two partitions if size > 0 or one partition if
3356    size == 0.
3357 
3358    The block descriptors are read and written because Sony SDT-7000 does not
3359    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3360 
3361    My HP C1533A drive returns only one partition size field. This is used to
3362    set the size of partition 1. There is no size field for the default partition.
3363    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3364    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3365    The following algorithm is used to accommodate both drives: if the number of
3366    partition size fields is greater than the maximum number of additional partitions
3367    in the mode page, the second field is used. Otherwise the first field is used.
3368 
3369    For Seagate DDS drives the page length must be 8 when no partitions is defined
3370    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3371    is acceptable also to some other old drives and enforced if the first partition
3372    size field is used for the first additional partition size.
3373 
3374    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3375  */
3376 static int partition_tape(struct scsi_tape *STp, int size)
3377 {
3378 	int result;
3379 	int target_partition;
3380 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3381 	int pgo, psd_cnt, psdo;
3382 	int psum = PP_MSK_PSUM_MB, units = 0;
3383 	unsigned char *bp;
3384 
3385 	result = read_mode_page(STp, PART_PAGE, 0);
3386 	if (result) {
3387 		DEBC_printk(STp, "Can't read partition mode page.\n");
3388 		return result;
3389 	}
3390 	target_partition = 1;
3391 	if (size < 0) {
3392 		target_partition = 0;
3393 		size = -size;
3394 	}
3395 
3396 	/* The mode page is in the buffer. Let's modify it and write it. */
3397 	bp = (STp->buffer)->b_data;
3398 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3399 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3400 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3401 
3402 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3403 
3404 	if (scsi3) {
3405 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3406 		if (needs_format && size == 0) {
3407 			/* No need to write the mode page when clearing
3408 			 *  partitioning
3409 			 */
3410 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3411 			result = format_medium(STp, 0);
3412 			goto out;
3413 		}
3414 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3415 			psd_cnt = 2;
3416 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3417 			/* Use units scaling for large partitions if the device
3418 			 * suggests it and no precision lost. Required for IBM
3419 			 * TS1140/50 drives that don't support MB units.
3420 			 */
3421 			if (size >= 1000 && (size % 1000) == 0) {
3422 				size /= 1000;
3423 				psum = PP_MSK_PSUM_UNITS;
3424 				units = 9; /* GB */
3425 			}
3426 		}
3427 		/* Try it anyway if too large to specify in MB */
3428 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3429 			size /= 1000;
3430 			psum = PP_MSK_PSUM_UNITS;
3431 			units = 9;  /* GB */
3432 		}
3433 	}
3434 
3435 	if (size >= 65535 ||  /* Does not fit into two bytes */
3436 	    (target_partition == 0 && psd_cnt < 2)) {
3437 		result = -EINVAL;
3438 		goto out;
3439 	}
3440 
3441 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3442 	/* The second condition is for HP DDS which use only one partition size
3443 	 * descriptor
3444 	 */
3445 	if (target_partition > 0 &&
3446 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3447 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3448 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3449 		psdo += 2;
3450 	}
3451 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3452 
3453 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3454 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3455 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3456 
3457 	if (size == 0) {
3458 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3459 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3460 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3461 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3462 	} else {
3463 		bp[psdo] = (size >> 8) & 0xff;
3464 		bp[psdo + 1] = size & 0xff;
3465 		if (target_partition == 0)
3466 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3467 		bp[pgo + 3] = 1;
3468 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3469 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3470 		DEBC_printk(STp,
3471 			    "Formatting tape with two partitions (%i = %d MB).\n",
3472 			    target_partition, units > 0 ? size * 1000 : size);
3473 	}
3474 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3475 	bp[pgo + PP_OFF_RESERVED] = 0;
3476 	if (size != 1 || units != 0) {
3477 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3478 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3479 		bp[pgo + PP_OFF_PART_UNITS] = units;
3480 	} else
3481 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3482 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3483 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3484 
3485 	result = write_mode_page(STp, PART_PAGE, 1);
3486 
3487 	if (!result && needs_format)
3488 		result = format_medium(STp, 1);
3489 
3490 	if (result) {
3491 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3492 		result = (-EIO);
3493 	}
3494 
3495 out:
3496 	return result;
3497 }
3498 
3499 
3500 
3501 /* The ioctl command */
3502 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3503 {
3504 	void __user *p = (void __user *)arg;
3505 	int i, cmd_nr, cmd_type, bt;
3506 	int retval = 0;
3507 	unsigned int blk;
3508 	struct scsi_tape *STp = file->private_data;
3509 	struct st_modedef *STm;
3510 	struct st_partstat *STps;
3511 
3512 	if (mutex_lock_interruptible(&STp->lock))
3513 		return -ERESTARTSYS;
3514 
3515 	DEB(
3516 	if (debugging && !STp->in_use) {
3517 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3518 		retval = (-EIO);
3519 		goto out;
3520 	} ) /* end DEB */
3521 
3522 	STm = &(STp->modes[STp->current_mode]);
3523 	STps = &(STp->ps[STp->partition]);
3524 
3525 	/*
3526 	 * If we are in the middle of error recovery, don't let anyone
3527 	 * else try and use this device.  Also, if error recovery fails, it
3528 	 * may try and take the device offline, in which case all further
3529 	 * access to the device is prohibited.
3530 	 */
3531 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3532 			file->f_flags & O_NDELAY);
3533 	if (retval)
3534 		goto out;
3535 
3536 	cmd_type = _IOC_TYPE(cmd_in);
3537 	cmd_nr = _IOC_NR(cmd_in);
3538 
3539 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3540 		struct mtop mtc;
3541 
3542 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3543 			retval = (-EINVAL);
3544 			goto out;
3545 		}
3546 
3547 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3548 		if (i) {
3549 			retval = (-EFAULT);
3550 			goto out;
3551 		}
3552 
3553 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3554 			st_printk(KERN_WARNING, STp,
3555 				  "MTSETDRVBUFFER only allowed for root.\n");
3556 			retval = (-EPERM);
3557 			goto out;
3558 		}
3559 		if (!STm->defined &&
3560 		    (mtc.mt_op != MTSETDRVBUFFER &&
3561 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3562 			retval = (-ENXIO);
3563 			goto out;
3564 		}
3565 
3566 		if (!STp->pos_unknown) {
3567 
3568 			if (STps->eof == ST_FM_HIT) {
3569 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3570                                     mtc.mt_op == MTEOM) {
3571 					mtc.mt_count -= 1;
3572 					if (STps->drv_file >= 0)
3573 						STps->drv_file += 1;
3574 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3575 					mtc.mt_count += 1;
3576 					if (STps->drv_file >= 0)
3577 						STps->drv_file += 1;
3578 				}
3579 			}
3580 
3581 			if (mtc.mt_op == MTSEEK) {
3582 				/* Old position must be restored if partition will be
3583                                    changed */
3584 				i = !STp->can_partitions ||
3585 				    (STp->new_partition != STp->partition);
3586 			} else {
3587 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3588 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3589 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3590 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3591 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3592 				    mtc.mt_op == MTCOMPRESSION;
3593 			}
3594 			i = flush_buffer(STp, i);
3595 			if (i < 0) {
3596 				retval = i;
3597 				goto out;
3598 			}
3599 			if (STps->rw == ST_WRITING &&
3600 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3601 			     mtc.mt_op == MTSEEK ||
3602 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3603 				i = st_int_ioctl(STp, MTWEOF, 1);
3604 				if (i < 0) {
3605 					retval = i;
3606 					goto out;
3607 				}
3608 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3609 					mtc.mt_count++;
3610 				STps->rw = ST_IDLE;
3611 			     }
3612 
3613 		} else {
3614 			/*
3615 			 * If there was a bus reset, block further access
3616 			 * to this device.  If the user wants to rewind the tape,
3617 			 * then reset the flag and allow access again.
3618 			 */
3619 			if (mtc.mt_op != MTREW &&
3620 			    mtc.mt_op != MTOFFL &&
3621 			    mtc.mt_op != MTRETEN &&
3622 			    mtc.mt_op != MTERASE &&
3623 			    mtc.mt_op != MTSEEK &&
3624 			    mtc.mt_op != MTEOM) {
3625 				retval = (-EIO);
3626 				goto out;
3627 			}
3628 			reset_state(STp);
3629 			/* remove this when the midlevel properly clears was_reset */
3630 			STp->device->was_reset = 0;
3631 		}
3632 
3633 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3634 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3635 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3636 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3637 
3638 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3639 			do_door_lock(STp, 0);	/* Ignore result! */
3640 
3641 		if (mtc.mt_op == MTSETDRVBUFFER &&
3642 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3643 			retval = st_set_options(STp, mtc.mt_count);
3644 			goto out;
3645 		}
3646 
3647 		if (mtc.mt_op == MTSETPART) {
3648 			if (!STp->can_partitions ||
3649 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3650 				retval = (-EINVAL);
3651 				goto out;
3652 			}
3653 			if (mtc.mt_count >= STp->nbr_partitions &&
3654 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3655 				retval = (-EIO);
3656 				goto out;
3657 			}
3658 			if (mtc.mt_count >= STp->nbr_partitions) {
3659 				retval = (-EINVAL);
3660 				goto out;
3661 			}
3662 			STp->new_partition = mtc.mt_count;
3663 			retval = 0;
3664 			goto out;
3665 		}
3666 
3667 		if (mtc.mt_op == MTMKPART) {
3668 			if (!STp->can_partitions) {
3669 				retval = (-EINVAL);
3670 				goto out;
3671 			}
3672 			i = do_load_unload(STp, file, 1);
3673 			if (i < 0) {
3674 				retval = i;
3675 				goto out;
3676 			}
3677 			i = partition_tape(STp, mtc.mt_count);
3678 			if (i < 0) {
3679 				retval = i;
3680 				goto out;
3681 			}
3682 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3683 				STp->ps[i].rw = ST_IDLE;
3684 				STp->ps[i].at_sm = 0;
3685 				STp->ps[i].last_block_valid = 0;
3686 			}
3687 			STp->partition = STp->new_partition = 0;
3688 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3689 			STps->drv_block = STps->drv_file = 0;
3690 			retval = 0;
3691 			goto out;
3692 		}
3693 
3694 		if (mtc.mt_op == MTSEEK) {
3695 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3696 			if (!STp->can_partitions)
3697 				STp->ps[0].rw = ST_IDLE;
3698 			retval = i;
3699 			goto out;
3700 		}
3701 
3702 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3703 			retval = do_load_unload(STp, file, 0);
3704 			goto out;
3705 		}
3706 
3707 		if (mtc.mt_op == MTLOAD) {
3708 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3709 			goto out;
3710 		}
3711 
3712 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3713 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3714 			goto out;
3715 		}
3716 
3717 		if (STp->can_partitions && STp->ready == ST_READY &&
3718 		    (i = switch_partition(STp)) < 0) {
3719 			retval = i;
3720 			goto out;
3721 		}
3722 
3723 		if (mtc.mt_op == MTCOMPRESSION)
3724 			retval = st_compression(STp, (mtc.mt_count & 1));
3725 		else
3726 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3727 		goto out;
3728 	}
3729 	if (!STm->defined) {
3730 		retval = (-ENXIO);
3731 		goto out;
3732 	}
3733 
3734 	if ((i = flush_buffer(STp, 0)) < 0) {
3735 		retval = i;
3736 		goto out;
3737 	}
3738 	if (STp->can_partitions &&
3739 	    (i = switch_partition(STp)) < 0) {
3740 		retval = i;
3741 		goto out;
3742 	}
3743 
3744 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3745 		struct mtget mt_status;
3746 
3747 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3748 			 retval = (-EINVAL);
3749 			 goto out;
3750 		}
3751 
3752 		mt_status.mt_type = STp->tape_type;
3753 		mt_status.mt_dsreg =
3754 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3755 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3756 		mt_status.mt_blkno = STps->drv_block;
3757 		mt_status.mt_fileno = STps->drv_file;
3758 		if (STp->block_size != 0) {
3759 			if (STps->rw == ST_WRITING)
3760 				mt_status.mt_blkno +=
3761 				    (STp->buffer)->buffer_bytes / STp->block_size;
3762 			else if (STps->rw == ST_READING)
3763 				mt_status.mt_blkno -=
3764                                         ((STp->buffer)->buffer_bytes +
3765                                          STp->block_size - 1) / STp->block_size;
3766 		}
3767 
3768 		mt_status.mt_gstat = 0;
3769 		if (STp->drv_write_prot)
3770 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3771 		if (mt_status.mt_blkno == 0) {
3772 			if (mt_status.mt_fileno == 0)
3773 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3774 			else
3775 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3776 		}
3777 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3778 		mt_status.mt_resid = STp->partition;
3779 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3780 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3781 		else if (STps->eof >= ST_EOM_OK)
3782 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3783 		if (STp->density == 1)
3784 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3785 		else if (STp->density == 2)
3786 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3787 		else if (STp->density == 3)
3788 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3789 		if (STp->ready == ST_READY)
3790 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3791 		if (STp->ready == ST_NO_TAPE)
3792 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3793 		if (STps->at_sm)
3794 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3795 		if (STm->do_async_writes ||
3796                     (STm->do_buffer_writes && STp->block_size != 0) ||
3797 		    STp->drv_buffer != 0)
3798 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3799 		if (STp->cleaning_req)
3800 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3801 
3802 		retval = put_user_mtget(p, &mt_status);
3803 		if (retval)
3804 			goto out;
3805 
3806 		STp->recover_reg = 0;		/* Clear after read */
3807 		goto out;
3808 	}			/* End of MTIOCGET */
3809 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3810 		struct mtpos mt_pos;
3811 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3812 			 retval = (-EINVAL);
3813 			 goto out;
3814 		}
3815 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3816 			retval = i;
3817 			goto out;
3818 		}
3819 		mt_pos.mt_blkno = blk;
3820 		retval = put_user_mtpos(p, &mt_pos);
3821 		goto out;
3822 	}
3823 	mutex_unlock(&STp->lock);
3824 
3825 	switch (cmd_in) {
3826 	case SG_IO:
3827 	case SCSI_IOCTL_SEND_COMMAND:
3828 	case CDROM_SEND_PACKET:
3829 		if (!capable(CAP_SYS_RAWIO))
3830 			return -EPERM;
3831 		break;
3832 	default:
3833 		break;
3834 	}
3835 
3836 	retval = scsi_ioctl(STp->device, file->f_mode & FMODE_WRITE, cmd_in, p);
3837 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) {
3838 		/* unload */
3839 		STp->rew_at_close = 0;
3840 		STp->ready = ST_NO_TAPE;
3841 	}
3842 	return retval;
3843 
3844  out:
3845 	mutex_unlock(&STp->lock);
3846 	return retval;
3847 }
3848 
3849 #ifdef CONFIG_COMPAT
3850 static long st_compat_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3851 {
3852 	/* argument conversion is handled using put_user_mtpos/put_user_mtget */
3853 	switch (cmd_in) {
3854 	case MTIOCPOS32:
3855 		cmd_in = MTIOCPOS;
3856 		break;
3857 	case MTIOCGET32:
3858 		cmd_in = MTIOCGET;
3859 		break;
3860 	}
3861 
3862 	return st_ioctl(file, cmd_in, arg);
3863 }
3864 #endif
3865 
3866 
3867 
3868 /* Try to allocate a new tape buffer. Calling function must not hold
3869    dev_arr_lock. */
3870 static struct st_buffer *new_tape_buffer(int max_sg)
3871 {
3872 	struct st_buffer *tb;
3873 
3874 	tb = kzalloc(sizeof(struct st_buffer), GFP_KERNEL);
3875 	if (!tb) {
3876 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3877 		return NULL;
3878 	}
3879 	tb->frp_segs = 0;
3880 	tb->use_sg = max_sg;
3881 	tb->buffer_size = 0;
3882 
3883 	tb->reserved_pages = kcalloc(max_sg, sizeof(struct page *),
3884 				     GFP_KERNEL);
3885 	if (!tb->reserved_pages) {
3886 		kfree(tb);
3887 		return NULL;
3888 	}
3889 
3890 	return tb;
3891 }
3892 
3893 
3894 /* Try to allocate enough space in the tape buffer */
3895 #define ST_MAX_ORDER 6
3896 
3897 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size)
3898 {
3899 	int segs, max_segs, b_size, order, got;
3900 	gfp_t priority;
3901 
3902 	if (new_size <= STbuffer->buffer_size)
3903 		return 1;
3904 
3905 	if (STbuffer->buffer_size <= PAGE_SIZE)
3906 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3907 
3908 	max_segs = STbuffer->use_sg;
3909 
3910 	priority = GFP_KERNEL | __GFP_NOWARN;
3911 
3912 	if (STbuffer->cleared)
3913 		priority |= __GFP_ZERO;
3914 
3915 	if (STbuffer->frp_segs) {
3916 		order = STbuffer->reserved_page_order;
3917 		b_size = PAGE_SIZE << order;
3918 	} else {
3919 		for (b_size = PAGE_SIZE, order = 0;
3920 		     order < ST_MAX_ORDER &&
3921 			     max_segs * (PAGE_SIZE << order) < new_size;
3922 		     order++, b_size *= 2)
3923 			;  /* empty */
3924 		STbuffer->reserved_page_order = order;
3925 	}
3926 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3927 		if (order == ST_MAX_ORDER)
3928 			return 0;
3929 		normalize_buffer(STbuffer);
3930 		return enlarge_buffer(STbuffer, new_size);
3931 	}
3932 
3933 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3934 	     segs < max_segs && got < new_size;) {
3935 		struct page *page;
3936 
3937 		page = alloc_pages(priority, order);
3938 		if (!page) {
3939 			DEB(STbuffer->buffer_size = got);
3940 			normalize_buffer(STbuffer);
3941 			return 0;
3942 		}
3943 
3944 		STbuffer->frp_segs += 1;
3945 		got += b_size;
3946 		STbuffer->buffer_size = got;
3947 		STbuffer->reserved_pages[segs] = page;
3948 		segs++;
3949 	}
3950 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3951 
3952 	return 1;
3953 }
3954 
3955 
3956 /* Make sure that no data from previous user is in the internal buffer */
3957 static void clear_buffer(struct st_buffer * st_bp)
3958 {
3959 	int i;
3960 
3961 	for (i=0; i < st_bp->frp_segs; i++)
3962 		memset(page_address(st_bp->reserved_pages[i]), 0,
3963 		       PAGE_SIZE << st_bp->reserved_page_order);
3964 	st_bp->cleared = 1;
3965 }
3966 
3967 
3968 /* Release the extra buffer */
3969 static void normalize_buffer(struct st_buffer * STbuffer)
3970 {
3971 	int i, order = STbuffer->reserved_page_order;
3972 
3973 	for (i = 0; i < STbuffer->frp_segs; i++) {
3974 		__free_pages(STbuffer->reserved_pages[i], order);
3975 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3976 	}
3977 	STbuffer->frp_segs = 0;
3978 	STbuffer->sg_segs = 0;
3979 	STbuffer->reserved_page_order = 0;
3980 	STbuffer->map_data.offset = 0;
3981 }
3982 
3983 
3984 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3985    negative error code. */
3986 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3987 {
3988 	int i, cnt, res, offset;
3989 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3990 
3991 	for (i = 0, offset = st_bp->buffer_bytes;
3992 	     i < st_bp->frp_segs && offset >= length; i++)
3993 		offset -= length;
3994 	if (i == st_bp->frp_segs) {	/* Should never happen */
3995 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
3996 		return (-EIO);
3997 	}
3998 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3999 		struct page *page = st_bp->reserved_pages[i];
4000 		cnt = length - offset < do_count ? length - offset : do_count;
4001 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4002 		if (res)
4003 			return (-EFAULT);
4004 		do_count -= cnt;
4005 		st_bp->buffer_bytes += cnt;
4006 		ubp += cnt;
4007 		offset = 0;
4008 	}
4009 	if (do_count) /* Should never happen */
4010 		return (-EIO);
4011 
4012 	return 0;
4013 }
4014 
4015 
4016 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4017    negative error code. */
4018 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4019 {
4020 	int i, cnt, res, offset;
4021 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4022 
4023 	for (i = 0, offset = st_bp->read_pointer;
4024 	     i < st_bp->frp_segs && offset >= length; i++)
4025 		offset -= length;
4026 	if (i == st_bp->frp_segs) {	/* Should never happen */
4027 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4028 		return (-EIO);
4029 	}
4030 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4031 		struct page *page = st_bp->reserved_pages[i];
4032 		cnt = length - offset < do_count ? length - offset : do_count;
4033 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4034 		if (res)
4035 			return (-EFAULT);
4036 		do_count -= cnt;
4037 		st_bp->buffer_bytes -= cnt;
4038 		st_bp->read_pointer += cnt;
4039 		ubp += cnt;
4040 		offset = 0;
4041 	}
4042 	if (do_count) /* Should never happen */
4043 		return (-EIO);
4044 
4045 	return 0;
4046 }
4047 
4048 
4049 /* Move data towards start of buffer */
4050 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4051 {
4052 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4053 	int count, total;
4054 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4055 
4056 	if (offset == 0)
4057 		return;
4058 
4059 	total=st_bp->buffer_bytes - offset;
4060 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4061 		src_offset = offset;
4062 		if (src_offset < length)
4063 			break;
4064 		offset -= length;
4065 	}
4066 
4067 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4068 	for (dst_seg=dst_offset=0; total > 0; ) {
4069 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4070 		struct page *spage = st_bp->reserved_pages[src_seg];
4071 
4072 		count = min(length - dst_offset, length - src_offset);
4073 		memmove(page_address(dpage) + dst_offset,
4074 			page_address(spage) + src_offset, count);
4075 		src_offset += count;
4076 		if (src_offset >= length) {
4077 			src_seg++;
4078 			src_offset = 0;
4079 		}
4080 		dst_offset += count;
4081 		if (dst_offset >= length) {
4082 			dst_seg++;
4083 			dst_offset = 0;
4084 		}
4085 		total -= count;
4086 	}
4087 }
4088 
4089 /* Validate the options from command line or module parameters */
4090 static void validate_options(void)
4091 {
4092 	if (buffer_kbs > 0)
4093 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4094 	if (max_sg_segs >= ST_FIRST_SG)
4095 		st_max_sg_segs = max_sg_segs;
4096 }
4097 
4098 #ifndef MODULE
4099 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4100  */
4101 static int __init st_setup(char *str)
4102 {
4103 	int i, len, ints[5];
4104 	char *stp;
4105 
4106 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4107 
4108 	if (ints[0] > 0) {
4109 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4110 			if (parms[i].val)
4111 				*parms[i].val = ints[i + 1];
4112 	} else {
4113 		while (stp != NULL) {
4114 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4115 				len = strlen(parms[i].name);
4116 				if (!strncmp(stp, parms[i].name, len) &&
4117 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4118 					if (parms[i].val)
4119 						*parms[i].val =
4120 							simple_strtoul(stp + len + 1, NULL, 0);
4121 					else
4122 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4123 						       parms[i].name);
4124 					break;
4125 				}
4126 			}
4127 			if (i >= ARRAY_SIZE(parms))
4128 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4129 					stp);
4130 			stp = strchr(stp, ',');
4131 			if (stp)
4132 				stp++;
4133 		}
4134 	}
4135 
4136 	validate_options();
4137 
4138 	return 1;
4139 }
4140 
4141 __setup("st=", st_setup);
4142 
4143 #endif
4144 
4145 static const struct file_operations st_fops =
4146 {
4147 	.owner =	THIS_MODULE,
4148 	.read =		st_read,
4149 	.write =	st_write,
4150 	.unlocked_ioctl = st_ioctl,
4151 #ifdef CONFIG_COMPAT
4152 	.compat_ioctl = st_compat_ioctl,
4153 #endif
4154 	.open =		st_open,
4155 	.flush =	st_flush,
4156 	.release =	st_release,
4157 	.llseek =	noop_llseek,
4158 };
4159 
4160 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4161 {
4162 	int i, error;
4163 	dev_t cdev_devno;
4164 	struct cdev *cdev;
4165 	struct device *dev;
4166 	struct st_modedef *STm = &(tape->modes[mode]);
4167 	char name[10];
4168 	int dev_num = tape->index;
4169 
4170 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4171 
4172 	cdev = cdev_alloc();
4173 	if (!cdev) {
4174 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4175 		error = -ENOMEM;
4176 		goto out;
4177 	}
4178 	cdev->owner = THIS_MODULE;
4179 	cdev->ops = &st_fops;
4180 	STm->cdevs[rew] = cdev;
4181 
4182 	error = cdev_add(cdev, cdev_devno, 1);
4183 	if (error) {
4184 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4185 		       rew ? "non" : "auto", mode);
4186 		pr_err("st%d: Device not attached.\n", dev_num);
4187 		goto out_free;
4188 	}
4189 
4190 	i = mode << (4 - ST_NBR_MODE_BITS);
4191 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4192 		 tape->name, st_formats[i]);
4193 
4194 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4195 			    cdev_devno, &tape->modes[mode], "%s", name);
4196 	if (IS_ERR(dev)) {
4197 		pr_err("st%d: device_create failed\n", dev_num);
4198 		error = PTR_ERR(dev);
4199 		goto out_free;
4200 	}
4201 
4202 	STm->devs[rew] = dev;
4203 
4204 	return 0;
4205 out_free:
4206 	cdev_del(STm->cdevs[rew]);
4207 out:
4208 	STm->cdevs[rew] = NULL;
4209 	STm->devs[rew] = NULL;
4210 	return error;
4211 }
4212 
4213 static int create_cdevs(struct scsi_tape *tape)
4214 {
4215 	int mode, error;
4216 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4217 		error = create_one_cdev(tape, mode, 0);
4218 		if (error)
4219 			return error;
4220 		error = create_one_cdev(tape, mode, 1);
4221 		if (error)
4222 			return error;
4223 	}
4224 
4225 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4226 				 &tape->modes[0].devs[0]->kobj, "tape");
4227 }
4228 
4229 static void remove_cdevs(struct scsi_tape *tape)
4230 {
4231 	int mode, rew;
4232 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4233 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4234 		struct st_modedef *STm = &(tape->modes[mode]);
4235 		for (rew = 0; rew < 2; rew++) {
4236 			if (STm->cdevs[rew])
4237 				cdev_del(STm->cdevs[rew]);
4238 			if (STm->devs[rew])
4239 				device_unregister(STm->devs[rew]);
4240 		}
4241 	}
4242 }
4243 
4244 static int st_probe(struct device *dev)
4245 {
4246 	struct scsi_device *SDp = to_scsi_device(dev);
4247 	struct scsi_tape *tpnt = NULL;
4248 	struct st_modedef *STm;
4249 	struct st_partstat *STps;
4250 	struct st_buffer *buffer;
4251 	int i, error;
4252 
4253 	if (SDp->type != TYPE_TAPE)
4254 		return -ENODEV;
4255 	if (st_incompatible(SDp)) {
4256 		sdev_printk(KERN_INFO, SDp,
4257 			    "OnStream tapes are no longer supported;\n");
4258 		sdev_printk(KERN_INFO, SDp,
4259 			    "please mail to linux-scsi@vger.kernel.org.\n");
4260 		return -ENODEV;
4261 	}
4262 
4263 	scsi_autopm_get_device(SDp);
4264 	i = queue_max_segments(SDp->request_queue);
4265 	if (st_max_sg_segs < i)
4266 		i = st_max_sg_segs;
4267 	buffer = new_tape_buffer(i);
4268 	if (buffer == NULL) {
4269 		sdev_printk(KERN_ERR, SDp,
4270 			    "st: Can't allocate new tape buffer. "
4271 			    "Device not attached.\n");
4272 		goto out;
4273 	}
4274 
4275 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
4276 	if (tpnt == NULL) {
4277 		sdev_printk(KERN_ERR, SDp,
4278 			    "st: Can't allocate device descriptor.\n");
4279 		goto out_buffer_free;
4280 	}
4281 	kref_init(&tpnt->kref);
4282 
4283 	tpnt->device = SDp;
4284 	if (SDp->scsi_level <= 2)
4285 		tpnt->tape_type = MT_ISSCSI1;
4286 	else
4287 		tpnt->tape_type = MT_ISSCSI2;
4288 
4289 	tpnt->buffer = buffer;
4290 	tpnt->buffer->last_SRpnt = NULL;
4291 
4292 	tpnt->inited = 0;
4293 	tpnt->dirty = 0;
4294 	tpnt->in_use = 0;
4295 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4296 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4297 	tpnt->density = 0;
4298 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4299 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4300 	tpnt->can_partitions = 0;
4301 	tpnt->two_fm = ST_TWO_FM;
4302 	tpnt->fast_mteom = ST_FAST_MTEOM;
4303 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4304 	tpnt->sili = ST_SILI;
4305 	tpnt->immediate = ST_NOWAIT;
4306 	tpnt->immediate_filemark = 0;
4307 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4308 	tpnt->partition = 0;
4309 	tpnt->new_partition = 0;
4310 	tpnt->nbr_partitions = 0;
4311 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4312 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4313 	tpnt->try_dio = try_direct_io;
4314 
4315 	for (i = 0; i < ST_NBR_MODES; i++) {
4316 		STm = &(tpnt->modes[i]);
4317 		STm->defined = 0;
4318 		STm->sysv = ST_SYSV;
4319 		STm->defaults_for_writes = 0;
4320 		STm->do_async_writes = ST_ASYNC_WRITES;
4321 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4322 		STm->do_read_ahead = ST_READ_AHEAD;
4323 		STm->default_compression = ST_DONT_TOUCH;
4324 		STm->default_blksize = (-1);	/* No forced size */
4325 		STm->default_density = (-1);	/* No forced density */
4326 		STm->tape = tpnt;
4327 	}
4328 
4329 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4330 		STps = &(tpnt->ps[i]);
4331 		STps->rw = ST_IDLE;
4332 		STps->eof = ST_NOEOF;
4333 		STps->at_sm = 0;
4334 		STps->last_block_valid = 0;
4335 		STps->drv_block = (-1);
4336 		STps->drv_file = (-1);
4337 	}
4338 
4339 	tpnt->current_mode = 0;
4340 	tpnt->modes[0].defined = 1;
4341 
4342 	tpnt->density_changed = tpnt->compression_changed =
4343 	    tpnt->blksize_changed = 0;
4344 	mutex_init(&tpnt->lock);
4345 
4346 	idr_preload(GFP_KERNEL);
4347 	spin_lock(&st_index_lock);
4348 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4349 	spin_unlock(&st_index_lock);
4350 	idr_preload_end();
4351 	if (error < 0) {
4352 		pr_warn("st: idr allocation failed: %d\n", error);
4353 		goto out_free_tape;
4354 	}
4355 	tpnt->index = error;
4356 	sprintf(tpnt->name, "st%d", tpnt->index);
4357 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4358 	if (tpnt->stats == NULL) {
4359 		sdev_printk(KERN_ERR, SDp,
4360 			    "st: Can't allocate statistics.\n");
4361 		goto out_idr_remove;
4362 	}
4363 
4364 	dev_set_drvdata(dev, tpnt);
4365 
4366 
4367 	error = create_cdevs(tpnt);
4368 	if (error)
4369 		goto out_remove_devs;
4370 	scsi_autopm_put_device(SDp);
4371 
4372 	sdev_printk(KERN_NOTICE, SDp,
4373 		    "Attached scsi tape %s\n", tpnt->name);
4374 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4375 		    tpnt->name, tpnt->try_dio ? "yes" : "no",
4376 		    queue_dma_alignment(SDp->request_queue) + 1);
4377 
4378 	return 0;
4379 
4380 out_remove_devs:
4381 	remove_cdevs(tpnt);
4382 	kfree(tpnt->stats);
4383 out_idr_remove:
4384 	spin_lock(&st_index_lock);
4385 	idr_remove(&st_index_idr, tpnt->index);
4386 	spin_unlock(&st_index_lock);
4387 out_free_tape:
4388 	kfree(tpnt);
4389 out_buffer_free:
4390 	kfree(buffer);
4391 out:
4392 	scsi_autopm_put_device(SDp);
4393 	return -ENODEV;
4394 };
4395 
4396 
4397 static int st_remove(struct device *dev)
4398 {
4399 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4400 	int index = tpnt->index;
4401 
4402 	scsi_autopm_get_device(to_scsi_device(dev));
4403 	remove_cdevs(tpnt);
4404 
4405 	mutex_lock(&st_ref_mutex);
4406 	kref_put(&tpnt->kref, scsi_tape_release);
4407 	mutex_unlock(&st_ref_mutex);
4408 	spin_lock(&st_index_lock);
4409 	idr_remove(&st_index_idr, index);
4410 	spin_unlock(&st_index_lock);
4411 	return 0;
4412 }
4413 
4414 /**
4415  *      scsi_tape_release - Called to free the Scsi_Tape structure
4416  *      @kref: pointer to embedded kref
4417  *
4418  *      st_ref_mutex must be held entering this routine.  Because it is
4419  *      called on last put, you should always use the scsi_tape_get()
4420  *      scsi_tape_put() helpers which manipulate the semaphore directly
4421  *      and never do a direct kref_put().
4422  **/
4423 static void scsi_tape_release(struct kref *kref)
4424 {
4425 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4426 
4427 	tpnt->device = NULL;
4428 
4429 	if (tpnt->buffer) {
4430 		normalize_buffer(tpnt->buffer);
4431 		kfree(tpnt->buffer->reserved_pages);
4432 		kfree(tpnt->buffer);
4433 	}
4434 
4435 	kfree(tpnt->stats);
4436 	kfree(tpnt);
4437 	return;
4438 }
4439 
4440 static const struct class st_sysfs_class = {
4441 	.name = "scsi_tape",
4442 	.dev_groups = st_dev_groups,
4443 };
4444 
4445 static int __init init_st(void)
4446 {
4447 	int err;
4448 
4449 	validate_options();
4450 
4451 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4452 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4453 
4454 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4455 	if (debugging) {
4456 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4457 			debugging);
4458 	}
4459 
4460 	err = class_register(&st_sysfs_class);
4461 	if (err) {
4462 		pr_err("Unable register sysfs class for SCSI tapes\n");
4463 		return err;
4464 	}
4465 
4466 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4467 				     ST_MAX_TAPE_ENTRIES, "st");
4468 	if (err) {
4469 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4470 		       SCSI_TAPE_MAJOR);
4471 		goto err_class;
4472 	}
4473 
4474 	err = scsi_register_driver(&st_template.gendrv);
4475 	if (err)
4476 		goto err_chrdev;
4477 
4478 	return 0;
4479 
4480 err_chrdev:
4481 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4482 				 ST_MAX_TAPE_ENTRIES);
4483 err_class:
4484 	class_unregister(&st_sysfs_class);
4485 	return err;
4486 }
4487 
4488 static void __exit exit_st(void)
4489 {
4490 	scsi_unregister_driver(&st_template.gendrv);
4491 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4492 				 ST_MAX_TAPE_ENTRIES);
4493 	class_unregister(&st_sysfs_class);
4494 	idr_destroy(&st_index_idr);
4495 	printk(KERN_INFO "st: Unloaded.\n");
4496 }
4497 
4498 module_init(init_st);
4499 module_exit(exit_st);
4500 
4501 
4502 /* The sysfs driver interface. Read-only at the moment */
4503 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4504 {
4505 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4506 }
4507 static DRIVER_ATTR_RO(try_direct_io);
4508 
4509 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4510 {
4511 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4512 }
4513 static DRIVER_ATTR_RO(fixed_buffer_size);
4514 
4515 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4516 {
4517 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4518 }
4519 static DRIVER_ATTR_RO(max_sg_segs);
4520 
4521 static ssize_t version_show(struct device_driver *ddd, char *buf)
4522 {
4523 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4524 }
4525 static DRIVER_ATTR_RO(version);
4526 
4527 #if DEBUG
4528 static ssize_t debug_flag_store(struct device_driver *ddp,
4529 	const char *buf, size_t count)
4530 {
4531 /* We only care what the first byte of the data is the rest is unused.
4532  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4533  * other values have -EINVAL returned if they are passed in.
4534  */
4535 	if (count > 0) {
4536 		if (buf[0] == '0') {
4537 			debugging = NO_DEBUG;
4538 			return count;
4539 		} else if (buf[0] == '1') {
4540 			debugging = 1;
4541 			return count;
4542 		}
4543 	}
4544 	return -EINVAL;
4545 }
4546 
4547 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4548 {
4549 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4550 }
4551 static DRIVER_ATTR_RW(debug_flag);
4552 #endif
4553 
4554 static struct attribute *st_drv_attrs[] = {
4555 	&driver_attr_try_direct_io.attr,
4556 	&driver_attr_fixed_buffer_size.attr,
4557 	&driver_attr_max_sg_segs.attr,
4558 	&driver_attr_version.attr,
4559 #if DEBUG
4560 	&driver_attr_debug_flag.attr,
4561 #endif
4562 	NULL,
4563 };
4564 ATTRIBUTE_GROUPS(st_drv);
4565 
4566 /* The sysfs simple class interface */
4567 static ssize_t
4568 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4569 {
4570 	struct st_modedef *STm = dev_get_drvdata(dev);
4571 	ssize_t l = 0;
4572 
4573 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4574 	return l;
4575 }
4576 static DEVICE_ATTR_RO(defined);
4577 
4578 static ssize_t
4579 default_blksize_show(struct device *dev, struct device_attribute *attr,
4580 		     char *buf)
4581 {
4582 	struct st_modedef *STm = dev_get_drvdata(dev);
4583 	ssize_t l = 0;
4584 
4585 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4586 	return l;
4587 }
4588 static DEVICE_ATTR_RO(default_blksize);
4589 
4590 static ssize_t
4591 default_density_show(struct device *dev, struct device_attribute *attr,
4592 		     char *buf)
4593 {
4594 	struct st_modedef *STm = dev_get_drvdata(dev);
4595 	ssize_t l = 0;
4596 	char *fmt;
4597 
4598 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4599 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4600 	return l;
4601 }
4602 static DEVICE_ATTR_RO(default_density);
4603 
4604 static ssize_t
4605 default_compression_show(struct device *dev, struct device_attribute *attr,
4606 			 char *buf)
4607 {
4608 	struct st_modedef *STm = dev_get_drvdata(dev);
4609 	ssize_t l = 0;
4610 
4611 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4612 	return l;
4613 }
4614 static DEVICE_ATTR_RO(default_compression);
4615 
4616 static ssize_t
4617 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4618 {
4619 	struct st_modedef *STm = dev_get_drvdata(dev);
4620 	struct scsi_tape *STp = STm->tape;
4621 	int options;
4622 	ssize_t l = 0;
4623 
4624 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4625 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4626 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4627 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4628 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4629 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4630 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4631 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4632 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4633 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4634 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4635 	options |= STm->sysv ? MT_ST_SYSV : 0;
4636 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4637 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4638 	options |= STp->sili ? MT_ST_SILI : 0;
4639 
4640 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4641 	return l;
4642 }
4643 static DEVICE_ATTR_RO(options);
4644 
4645 /* Support for tape stats */
4646 
4647 /**
4648  * read_cnt_show - return read count - count of reads made from tape drive
4649  * @dev: struct device
4650  * @attr: attribute structure
4651  * @buf: buffer to return formatted data in
4652  */
4653 static ssize_t read_cnt_show(struct device *dev,
4654 	struct device_attribute *attr, char *buf)
4655 {
4656 	struct st_modedef *STm = dev_get_drvdata(dev);
4657 
4658 	return sprintf(buf, "%lld",
4659 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4660 }
4661 static DEVICE_ATTR_RO(read_cnt);
4662 
4663 /**
4664  * read_byte_cnt_show - return read byte count - tape drives
4665  * may use blocks less than 512 bytes this gives the raw byte count of
4666  * of data read from the tape drive.
4667  * @dev: struct device
4668  * @attr: attribute structure
4669  * @buf: buffer to return formatted data in
4670  */
4671 static ssize_t read_byte_cnt_show(struct device *dev,
4672 	struct device_attribute *attr, char *buf)
4673 {
4674 	struct st_modedef *STm = dev_get_drvdata(dev);
4675 
4676 	return sprintf(buf, "%lld",
4677 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4678 }
4679 static DEVICE_ATTR_RO(read_byte_cnt);
4680 
4681 /**
4682  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4683  * @dev: struct device
4684  * @attr: attribute structure
4685  * @buf: buffer to return formatted data in
4686  */
4687 static ssize_t read_ns_show(struct device *dev,
4688 	struct device_attribute *attr, char *buf)
4689 {
4690 	struct st_modedef *STm = dev_get_drvdata(dev);
4691 
4692 	return sprintf(buf, "%lld",
4693 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4694 }
4695 static DEVICE_ATTR_RO(read_ns);
4696 
4697 /**
4698  * write_cnt_show - write count - number of user calls
4699  * to write(2) that have written data to tape.
4700  * @dev: struct device
4701  * @attr: attribute structure
4702  * @buf: buffer to return formatted data in
4703  */
4704 static ssize_t write_cnt_show(struct device *dev,
4705 	struct device_attribute *attr, char *buf)
4706 {
4707 	struct st_modedef *STm = dev_get_drvdata(dev);
4708 
4709 	return sprintf(buf, "%lld",
4710 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4711 }
4712 static DEVICE_ATTR_RO(write_cnt);
4713 
4714 /**
4715  * write_byte_cnt_show - write byte count - raw count of
4716  * bytes written to tape.
4717  * @dev: struct device
4718  * @attr: attribute structure
4719  * @buf: buffer to return formatted data in
4720  */
4721 static ssize_t write_byte_cnt_show(struct device *dev,
4722 	struct device_attribute *attr, char *buf)
4723 {
4724 	struct st_modedef *STm = dev_get_drvdata(dev);
4725 
4726 	return sprintf(buf, "%lld",
4727 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4728 }
4729 static DEVICE_ATTR_RO(write_byte_cnt);
4730 
4731 /**
4732  * write_ns_show - write ns - number of nanoseconds waiting on write
4733  * requests to complete.
4734  * @dev: struct device
4735  * @attr: attribute structure
4736  * @buf: buffer to return formatted data in
4737  */
4738 static ssize_t write_ns_show(struct device *dev,
4739 	struct device_attribute *attr, char *buf)
4740 {
4741 	struct st_modedef *STm = dev_get_drvdata(dev);
4742 
4743 	return sprintf(buf, "%lld",
4744 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4745 }
4746 static DEVICE_ATTR_RO(write_ns);
4747 
4748 /**
4749  * in_flight_show - number of I/Os currently in flight -
4750  * in most cases this will be either 0 or 1. It may be higher if someone
4751  * has also issued other SCSI commands such as via an ioctl.
4752  * @dev: struct device
4753  * @attr: attribute structure
4754  * @buf: buffer to return formatted data in
4755  */
4756 static ssize_t in_flight_show(struct device *dev,
4757 	struct device_attribute *attr, char *buf)
4758 {
4759 	struct st_modedef *STm = dev_get_drvdata(dev);
4760 
4761 	return sprintf(buf, "%lld",
4762 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4763 }
4764 static DEVICE_ATTR_RO(in_flight);
4765 
4766 /**
4767  * io_ns_show - io wait ns - this is the number of ns spent
4768  * waiting on all I/O to complete. This includes tape movement commands
4769  * such as rewinding, seeking to end of file or tape, it also includes
4770  * read and write. To determine the time spent on tape movement
4771  * subtract the read and write ns from this value.
4772  * @dev: struct device
4773  * @attr: attribute structure
4774  * @buf: buffer to return formatted data in
4775  */
4776 static ssize_t io_ns_show(struct device *dev,
4777 	struct device_attribute *attr, char *buf)
4778 {
4779 	struct st_modedef *STm = dev_get_drvdata(dev);
4780 
4781 	return sprintf(buf, "%lld",
4782 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4783 }
4784 static DEVICE_ATTR_RO(io_ns);
4785 
4786 /**
4787  * other_cnt_show - other io count - this is the number of
4788  * I/O requests other than read and write requests.
4789  * Typically these are tape movement requests but will include driver
4790  * tape movement. This includes only requests issued by the st driver.
4791  * @dev: struct device
4792  * @attr: attribute structure
4793  * @buf: buffer to return formatted data in
4794  */
4795 static ssize_t other_cnt_show(struct device *dev,
4796 	struct device_attribute *attr, char *buf)
4797 {
4798 	struct st_modedef *STm = dev_get_drvdata(dev);
4799 
4800 	return sprintf(buf, "%lld",
4801 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4802 }
4803 static DEVICE_ATTR_RO(other_cnt);
4804 
4805 /**
4806  * resid_cnt_show - A count of the number of times we get a residual
4807  * count - this should indicate someone issuing reads larger than the
4808  * block size on tape.
4809  * @dev: struct device
4810  * @attr: attribute structure
4811  * @buf: buffer to return formatted data in
4812  */
4813 static ssize_t resid_cnt_show(struct device *dev,
4814 	struct device_attribute *attr, char *buf)
4815 {
4816 	struct st_modedef *STm = dev_get_drvdata(dev);
4817 
4818 	return sprintf(buf, "%lld",
4819 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4820 }
4821 static DEVICE_ATTR_RO(resid_cnt);
4822 
4823 static struct attribute *st_dev_attrs[] = {
4824 	&dev_attr_defined.attr,
4825 	&dev_attr_default_blksize.attr,
4826 	&dev_attr_default_density.attr,
4827 	&dev_attr_default_compression.attr,
4828 	&dev_attr_options.attr,
4829 	NULL,
4830 };
4831 
4832 static struct attribute *st_stats_attrs[] = {
4833 	&dev_attr_read_cnt.attr,
4834 	&dev_attr_read_byte_cnt.attr,
4835 	&dev_attr_read_ns.attr,
4836 	&dev_attr_write_cnt.attr,
4837 	&dev_attr_write_byte_cnt.attr,
4838 	&dev_attr_write_ns.attr,
4839 	&dev_attr_in_flight.attr,
4840 	&dev_attr_io_ns.attr,
4841 	&dev_attr_other_cnt.attr,
4842 	&dev_attr_resid_cnt.attr,
4843 	NULL,
4844 };
4845 
4846 static struct attribute_group stats_group = {
4847 	.name = "stats",
4848 	.attrs = st_stats_attrs,
4849 };
4850 
4851 static struct attribute_group st_group = {
4852 	.attrs = st_dev_attrs,
4853 };
4854 
4855 static const struct attribute_group *st_dev_groups[] = {
4856 	&st_group,
4857 	&stats_group,
4858 	NULL,
4859 };
4860 
4861 /* The following functions may be useful for a larger audience. */
4862 static int sgl_map_user_pages(struct st_buffer *STbp,
4863 			      const unsigned int max_pages, unsigned long uaddr,
4864 			      size_t count, int rw)
4865 {
4866 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4867 	unsigned long start = uaddr >> PAGE_SHIFT;
4868 	const int nr_pages = end - start;
4869 	int res, i;
4870 	struct page **pages;
4871 	struct rq_map_data *mdata = &STbp->map_data;
4872 
4873 	/* User attempted Overflow! */
4874 	if ((uaddr + count) < uaddr)
4875 		return -EINVAL;
4876 
4877 	/* Too big */
4878         if (nr_pages > max_pages)
4879 		return -ENOMEM;
4880 
4881 	/* Hmm? */
4882 	if (count == 0)
4883 		return 0;
4884 
4885 	pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
4886 	if (pages == NULL)
4887 		return -ENOMEM;
4888 
4889         /* Try to fault in all of the necessary pages */
4890         /* rw==READ means read from drive, write into memory area */
4891 	res = pin_user_pages_fast(uaddr, nr_pages, rw == READ ? FOLL_WRITE : 0,
4892 				  pages);
4893 
4894 	/* Errors and no page mapped should return here */
4895 	if (res < nr_pages)
4896 		goto out_unmap;
4897 
4898         for (i=0; i < nr_pages; i++) {
4899                 /* FIXME: flush superflous for rw==READ,
4900                  * probably wrong function for rw==WRITE
4901                  */
4902 		flush_dcache_page(pages[i]);
4903         }
4904 
4905 	mdata->offset = uaddr & ~PAGE_MASK;
4906 	STbp->mapped_pages = pages;
4907 
4908 	return nr_pages;
4909  out_unmap:
4910 	if (res > 0) {
4911 		unpin_user_pages(pages, res);
4912 		res = 0;
4913 	}
4914 	kfree(pages);
4915 	return res;
4916 }
4917 
4918 
4919 /* And unmap them... */
4920 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4921 				const unsigned int nr_pages, int dirtied)
4922 {
4923 	/* FIXME: cache flush missing for rw==READ */
4924 	unpin_user_pages_dirty_lock(STbp->mapped_pages, nr_pages, dirtied);
4925 
4926 	kfree(STbp->mapped_pages);
4927 	STbp->mapped_pages = NULL;
4928 
4929 	return 0;
4930 }
4931