xref: /openbmc/linux/drivers/scsi/st.c (revision 6fa24b41)
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 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 		.owner		= THIS_MODULE,
210 		.probe		= st_probe,
211 		.remove		= st_remove,
212 		.groups		= st_drv_groups,
213 	},
214 };
215 
216 static int st_compression(struct scsi_tape *, int);
217 
218 static int find_partition(struct scsi_tape *);
219 static int switch_partition(struct scsi_tape *);
220 
221 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
222 
223 static void scsi_tape_release(struct kref *);
224 
225 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
226 
227 static DEFINE_MUTEX(st_ref_mutex);
228 static DEFINE_SPINLOCK(st_index_lock);
229 static DEFINE_SPINLOCK(st_use_lock);
230 static DEFINE_IDR(st_index_idr);
231 
232 
233 
234 #ifndef SIGS_FROM_OSST
235 #define SIGS_FROM_OSST \
236 	{"OnStream", "SC-", "", "osst"}, \
237 	{"OnStream", "DI-", "", "osst"}, \
238 	{"OnStream", "DP-", "", "osst"}, \
239 	{"OnStream", "USB", "", "osst"}, \
240 	{"OnStream", "FW-", "", "osst"}
241 #endif
242 
243 static struct scsi_tape *scsi_tape_get(int dev)
244 {
245 	struct scsi_tape *STp = NULL;
246 
247 	mutex_lock(&st_ref_mutex);
248 	spin_lock(&st_index_lock);
249 
250 	STp = idr_find(&st_index_idr, dev);
251 	if (!STp) goto out;
252 
253 	kref_get(&STp->kref);
254 
255 	if (!STp->device)
256 		goto out_put;
257 
258 	if (scsi_device_get(STp->device))
259 		goto out_put;
260 
261 	goto out;
262 
263 out_put:
264 	kref_put(&STp->kref, scsi_tape_release);
265 	STp = NULL;
266 out:
267 	spin_unlock(&st_index_lock);
268 	mutex_unlock(&st_ref_mutex);
269 	return STp;
270 }
271 
272 static void scsi_tape_put(struct scsi_tape *STp)
273 {
274 	struct scsi_device *sdev = STp->device;
275 
276 	mutex_lock(&st_ref_mutex);
277 	kref_put(&STp->kref, scsi_tape_release);
278 	scsi_device_put(sdev);
279 	mutex_unlock(&st_ref_mutex);
280 }
281 
282 struct st_reject_data {
283 	char *vendor;
284 	char *model;
285 	char *rev;
286 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
287 };
288 
289 static struct st_reject_data reject_list[] = {
290 	/* {"XXX", "Yy-", "", NULL},  example */
291 	SIGS_FROM_OSST,
292 	{NULL, }};
293 
294 /* If the device signature is on the list of incompatible drives, the
295    function returns a pointer to the name of the correct driver (if known) */
296 static char * st_incompatible(struct scsi_device* SDp)
297 {
298 	struct st_reject_data *rp;
299 
300 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
301 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
302 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
303 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
304 			if (rp->driver_hint)
305 				return rp->driver_hint;
306 			else
307 				return "unknown";
308 		}
309 	return NULL;
310 }
311 
312 
313 #define st_printk(prefix, t, fmt, a...) \
314 	sdev_prefix_printk(prefix, (t)->device, (t)->name, fmt, ##a)
315 #ifdef DEBUG
316 #define DEBC_printk(t, fmt, a...) \
317 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
318 #else
319 #define DEBC_printk(t, fmt, a...)
320 #endif
321 
322 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
323 {
324 	const u8 *ucp;
325 	const u8 *sense = SRpnt->sense;
326 
327 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
328 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
329 	s->flags = 0;
330 
331 	if (s->have_sense) {
332 		s->deferred = 0;
333 		s->remainder_valid =
334 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
335 		switch (sense[0] & 0x7f) {
336 		case 0x71:
337 			s->deferred = 1;
338 			fallthrough;
339 		case 0x70:
340 			s->fixed_format = 1;
341 			s->flags = sense[2] & 0xe0;
342 			break;
343 		case 0x73:
344 			s->deferred = 1;
345 			fallthrough;
346 		case 0x72:
347 			s->fixed_format = 0;
348 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
349 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
350 			break;
351 		}
352 	}
353 }
354 
355 
356 /* Convert the result to success code */
357 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
358 {
359 	int result = SRpnt->result;
360 	u8 scode;
361 	DEB(const char *stp;)
362 	char *name = STp->name;
363 	struct st_cmdstatus *cmdstatp;
364 
365 	if (!result)
366 		return 0;
367 
368 	cmdstatp = &STp->buffer->cmdstat;
369 	st_analyze_sense(SRpnt, cmdstatp);
370 
371 	if (cmdstatp->have_sense)
372 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
373 	else
374 		scode = 0;
375 
376 	DEB(
377 	if (debugging) {
378 		st_printk(ST_DEB_MSG, STp,
379 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
380 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
381 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
382 		if (cmdstatp->have_sense)
383 			__scsi_print_sense(STp->device, name,
384 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
385 	} ) /* end DEB */
386 	if (!debugging) { /* Abnormal conditions for tape */
387 		if (!cmdstatp->have_sense)
388 			st_printk(KERN_WARNING, STp,
389 			       "Error %x (driver bt 0, host bt 0x%x).\n",
390 			       result, host_byte(result));
391 		else if (cmdstatp->have_sense &&
392 			 scode != NO_SENSE &&
393 			 scode != RECOVERED_ERROR &&
394 			 /* scode != UNIT_ATTENTION && */
395 			 scode != BLANK_CHECK &&
396 			 scode != VOLUME_OVERFLOW &&
397 			 SRpnt->cmd[0] != MODE_SENSE &&
398 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
399 
400 			__scsi_print_sense(STp->device, name,
401 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
402 		}
403 	}
404 
405 	if (cmdstatp->fixed_format &&
406 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
407 		if (STp->cln_sense_value)
408 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
409 					       STp->cln_sense_mask) == STp->cln_sense_value);
410 		else
411 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
412 					       STp->cln_sense_mask) != 0);
413 	}
414 	if (cmdstatp->have_sense &&
415 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
416 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
417 	if (cmdstatp->have_sense && scode == UNIT_ATTENTION && cmdstatp->sense_hdr.asc == 0x29)
418 		STp->pos_unknown = 1; /* ASC => power on / reset */
419 
420 	STp->pos_unknown |= STp->device->was_reset;
421 
422 	if (cmdstatp->have_sense &&
423 	    scode == RECOVERED_ERROR
424 #if ST_RECOVERED_WRITE_FATAL
425 	    && SRpnt->cmd[0] != WRITE_6
426 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
427 #endif
428 	    ) {
429 		STp->recover_count++;
430 		STp->recover_reg++;
431 
432 		DEB(
433 		if (debugging) {
434 			if (SRpnt->cmd[0] == READ_6)
435 				stp = "read";
436 			else if (SRpnt->cmd[0] == WRITE_6)
437 				stp = "write";
438 			else
439 				stp = "ioctl";
440 			st_printk(ST_DEB_MSG, STp,
441 				  "Recovered %s error (%d).\n",
442 				  stp, STp->recover_count);
443 		} ) /* end DEB */
444 
445 		if (cmdstatp->flags == 0)
446 			return 0;
447 	}
448 	return (-EIO);
449 }
450 
451 static struct st_request *st_allocate_request(struct scsi_tape *stp)
452 {
453 	struct st_request *streq;
454 
455 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
456 	if (streq)
457 		streq->stp = stp;
458 	else {
459 		st_printk(KERN_ERR, stp,
460 			  "Can't get SCSI request.\n");
461 		if (signal_pending(current))
462 			stp->buffer->syscall_result = -EINTR;
463 		else
464 			stp->buffer->syscall_result = -EBUSY;
465 	}
466 
467 	return streq;
468 }
469 
470 static void st_release_request(struct st_request *streq)
471 {
472 	kfree(streq);
473 }
474 
475 static void st_do_stats(struct scsi_tape *STp, struct request *req)
476 {
477 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
478 	ktime_t now;
479 
480 	now = ktime_get();
481 	if (scmd->cmnd[0] == WRITE_6) {
482 		now = ktime_sub(now, STp->stats->write_time);
483 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
484 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
485 		atomic64_inc(&STp->stats->write_cnt);
486 		if (scmd->result) {
487 			atomic64_add(atomic_read(&STp->stats->last_write_size)
488 				- STp->buffer->cmdstat.residual,
489 				&STp->stats->write_byte_cnt);
490 			if (STp->buffer->cmdstat.residual > 0)
491 				atomic64_inc(&STp->stats->resid_cnt);
492 		} else
493 			atomic64_add(atomic_read(&STp->stats->last_write_size),
494 				&STp->stats->write_byte_cnt);
495 	} else if (scmd->cmnd[0] == READ_6) {
496 		now = ktime_sub(now, STp->stats->read_time);
497 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
498 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
499 		atomic64_inc(&STp->stats->read_cnt);
500 		if (scmd->result) {
501 			atomic64_add(atomic_read(&STp->stats->last_read_size)
502 				- STp->buffer->cmdstat.residual,
503 				&STp->stats->read_byte_cnt);
504 			if (STp->buffer->cmdstat.residual > 0)
505 				atomic64_inc(&STp->stats->resid_cnt);
506 		} else
507 			atomic64_add(atomic_read(&STp->stats->last_read_size),
508 				&STp->stats->read_byte_cnt);
509 	} else {
510 		now = ktime_sub(now, STp->stats->other_time);
511 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
512 		atomic64_inc(&STp->stats->other_cnt);
513 	}
514 	atomic64_dec(&STp->stats->in_flight);
515 }
516 
517 static enum rq_end_io_ret st_scsi_execute_end(struct request *req,
518 					      blk_status_t status)
519 {
520 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
521 	struct st_request *SRpnt = req->end_io_data;
522 	struct scsi_tape *STp = SRpnt->stp;
523 	struct bio *tmp;
524 
525 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = scmd->result;
526 	STp->buffer->cmdstat.residual = scmd->resid_len;
527 
528 	st_do_stats(STp, req);
529 
530 	tmp = SRpnt->bio;
531 	if (scmd->sense_len)
532 		memcpy(SRpnt->sense, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
533 	if (SRpnt->waiting)
534 		complete(SRpnt->waiting);
535 
536 	blk_rq_unmap_user(tmp);
537 	blk_mq_free_request(req);
538 	return RQ_END_IO_NONE;
539 }
540 
541 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
542 			   int data_direction, void *buffer, unsigned bufflen,
543 			   int timeout, int retries)
544 {
545 	struct request *req;
546 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
547 	int err = 0;
548 	struct scsi_tape *STp = SRpnt->stp;
549 	struct scsi_cmnd *scmd;
550 
551 	req = scsi_alloc_request(SRpnt->stp->device->request_queue,
552 			data_direction == DMA_TO_DEVICE ?
553 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
554 	if (IS_ERR(req))
555 		return PTR_ERR(req);
556 	scmd = blk_mq_rq_to_pdu(req);
557 	req->rq_flags |= RQF_QUIET;
558 
559 	mdata->null_mapped = 1;
560 
561 	if (bufflen) {
562 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
563 				      GFP_KERNEL);
564 		if (err) {
565 			blk_mq_free_request(req);
566 			return err;
567 		}
568 	}
569 
570 	atomic64_inc(&STp->stats->in_flight);
571 	if (cmd[0] == WRITE_6) {
572 		atomic_set(&STp->stats->last_write_size, bufflen);
573 		STp->stats->write_time = ktime_get();
574 	} else if (cmd[0] == READ_6) {
575 		atomic_set(&STp->stats->last_read_size, bufflen);
576 		STp->stats->read_time = ktime_get();
577 	} else {
578 		STp->stats->other_time = ktime_get();
579 	}
580 
581 	SRpnt->bio = req->bio;
582 	scmd->cmd_len = COMMAND_SIZE(cmd[0]);
583 	memcpy(scmd->cmnd, cmd, scmd->cmd_len);
584 	req->timeout = timeout;
585 	scmd->allowed = retries;
586 	req->end_io = st_scsi_execute_end;
587 	req->end_io_data = SRpnt;
588 
589 	blk_execute_rq_nowait(req, true);
590 	return 0;
591 }
592 
593 /* Do the scsi command. Waits until command performed if do_wait is true.
594    Otherwise write_behind_check() is used to check that the command
595    has finished. */
596 static struct st_request *
597 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
598 	   int bytes, int direction, int timeout, int retries, int do_wait)
599 {
600 	struct completion *waiting;
601 	struct rq_map_data *mdata = &STp->buffer->map_data;
602 	int ret;
603 
604 	/* if async, make sure there's no command outstanding */
605 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
606 		st_printk(KERN_ERR, STp,
607 			  "Async command already active.\n");
608 		if (signal_pending(current))
609 			(STp->buffer)->syscall_result = (-EINTR);
610 		else
611 			(STp->buffer)->syscall_result = (-EBUSY);
612 		return NULL;
613 	}
614 
615 	if (!SRpnt) {
616 		SRpnt = st_allocate_request(STp);
617 		if (!SRpnt)
618 			return NULL;
619 	}
620 
621 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
622 	   which IO is outstanding. It's nulled out when the IO completes. */
623 	if (!do_wait)
624 		(STp->buffer)->last_SRpnt = SRpnt;
625 
626 	waiting = &STp->wait;
627 	init_completion(waiting);
628 	SRpnt->waiting = waiting;
629 
630 	if (STp->buffer->do_dio) {
631 		mdata->page_order = 0;
632 		mdata->nr_entries = STp->buffer->sg_segs;
633 		mdata->pages = STp->buffer->mapped_pages;
634 	} else {
635 		mdata->page_order = STp->buffer->reserved_page_order;
636 		mdata->nr_entries =
637 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
638 		mdata->pages = STp->buffer->reserved_pages;
639 		mdata->offset = 0;
640 	}
641 
642 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
643 	STp->buffer->cmdstat.have_sense = 0;
644 	STp->buffer->syscall_result = 0;
645 
646 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
647 			      retries);
648 	if (ret) {
649 		/* could not allocate the buffer or request was too large */
650 		(STp->buffer)->syscall_result = (-EBUSY);
651 		(STp->buffer)->last_SRpnt = NULL;
652 	} else if (do_wait) {
653 		wait_for_completion(waiting);
654 		SRpnt->waiting = NULL;
655 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
656 	}
657 
658 	return SRpnt;
659 }
660 
661 
662 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
663    write has been correct but EOM early warning reached, -EIO if write ended in
664    error or zero if write successful. Asynchronous writes are used only in
665    variable block mode. */
666 static int write_behind_check(struct scsi_tape * STp)
667 {
668 	int retval = 0;
669 	struct st_buffer *STbuffer;
670 	struct st_partstat *STps;
671 	struct st_cmdstatus *cmdstatp;
672 	struct st_request *SRpnt;
673 
674 	STbuffer = STp->buffer;
675 	if (!STbuffer->writing)
676 		return 0;
677 
678 	DEB(
679 	if (STp->write_pending)
680 		STp->nbr_waits++;
681 	else
682 		STp->nbr_finished++;
683 	) /* end DEB */
684 
685 	wait_for_completion(&(STp->wait));
686 	SRpnt = STbuffer->last_SRpnt;
687 	STbuffer->last_SRpnt = NULL;
688 	SRpnt->waiting = NULL;
689 
690 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
691 	st_release_request(SRpnt);
692 
693 	STbuffer->buffer_bytes -= STbuffer->writing;
694 	STps = &(STp->ps[STp->partition]);
695 	if (STps->drv_block >= 0) {
696 		if (STp->block_size == 0)
697 			STps->drv_block++;
698 		else
699 			STps->drv_block += STbuffer->writing / STp->block_size;
700 	}
701 
702 	cmdstatp = &STbuffer->cmdstat;
703 	if (STbuffer->syscall_result) {
704 		retval = -EIO;
705 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
706 		    (cmdstatp->flags & SENSE_EOM) &&
707 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
708 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
709 			/* EOM at write-behind, has all data been written? */
710 			if (!cmdstatp->remainder_valid ||
711 			    cmdstatp->uremainder64 == 0)
712 				retval = -ENOSPC;
713 		}
714 		if (retval == -EIO)
715 			STps->drv_block = -1;
716 	}
717 	STbuffer->writing = 0;
718 
719 	DEB(if (debugging && retval)
720 		    st_printk(ST_DEB_MSG, STp,
721 				"Async write error %x, return value %d.\n",
722 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
723 
724 	return retval;
725 }
726 
727 
728 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
729    it messes up the block number). */
730 static int cross_eof(struct scsi_tape * STp, int forward)
731 {
732 	struct st_request *SRpnt;
733 	unsigned char cmd[MAX_COMMAND_SIZE];
734 
735 	cmd[0] = SPACE;
736 	cmd[1] = 0x01;		/* Space FileMarks */
737 	if (forward) {
738 		cmd[2] = cmd[3] = 0;
739 		cmd[4] = 1;
740 	} else
741 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
742 	cmd[5] = 0;
743 
744 	DEBC_printk(STp, "Stepping over filemark %s.\n",
745 		    forward ? "forward" : "backward");
746 
747 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
748 			   STp->device->request_queue->rq_timeout,
749 			   MAX_RETRIES, 1);
750 	if (!SRpnt)
751 		return (STp->buffer)->syscall_result;
752 
753 	st_release_request(SRpnt);
754 	SRpnt = NULL;
755 
756 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
757 		st_printk(KERN_ERR, STp,
758 			  "Stepping over filemark %s failed.\n",
759 			  forward ? "forward" : "backward");
760 
761 	return (STp->buffer)->syscall_result;
762 }
763 
764 
765 /* Flush the write buffer (never need to write if variable blocksize). */
766 static int st_flush_write_buffer(struct scsi_tape * STp)
767 {
768 	int transfer, blks;
769 	int result;
770 	unsigned char cmd[MAX_COMMAND_SIZE];
771 	struct st_request *SRpnt;
772 	struct st_partstat *STps;
773 
774 	result = write_behind_check(STp);
775 	if (result)
776 		return result;
777 
778 	result = 0;
779 	if (STp->dirty == 1) {
780 
781 		transfer = STp->buffer->buffer_bytes;
782 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
783 
784 		memset(cmd, 0, MAX_COMMAND_SIZE);
785 		cmd[0] = WRITE_6;
786 		cmd[1] = 1;
787 		blks = transfer / STp->block_size;
788 		cmd[2] = blks >> 16;
789 		cmd[3] = blks >> 8;
790 		cmd[4] = blks;
791 
792 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
793 				   STp->device->request_queue->rq_timeout,
794 				   MAX_WRITE_RETRIES, 1);
795 		if (!SRpnt)
796 			return (STp->buffer)->syscall_result;
797 
798 		STps = &(STp->ps[STp->partition]);
799 		if ((STp->buffer)->syscall_result != 0) {
800 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
801 
802 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
803 			    (cmdstatp->flags & SENSE_EOM) &&
804 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
805 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
806 			    (!cmdstatp->remainder_valid ||
807 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
808 				STp->dirty = 0;
809 				(STp->buffer)->buffer_bytes = 0;
810 				if (STps->drv_block >= 0)
811 					STps->drv_block += blks;
812 				result = (-ENOSPC);
813 			} else {
814 				st_printk(KERN_ERR, STp, "Error on flush.\n");
815 				STps->drv_block = (-1);
816 				result = (-EIO);
817 			}
818 		} else {
819 			if (STps->drv_block >= 0)
820 				STps->drv_block += blks;
821 			STp->dirty = 0;
822 			(STp->buffer)->buffer_bytes = 0;
823 		}
824 		st_release_request(SRpnt);
825 		SRpnt = NULL;
826 	}
827 	return result;
828 }
829 
830 
831 /* Flush the tape buffer. The tape will be positioned correctly unless
832    seek_next is true. */
833 static int flush_buffer(struct scsi_tape *STp, int seek_next)
834 {
835 	int backspace, result;
836 	struct st_partstat *STps;
837 
838 	if (STp->ready != ST_READY)
839 		return 0;
840 
841 	/*
842 	 * If there was a bus reset, block further access
843 	 * to this device.
844 	 */
845 	if (STp->pos_unknown)
846 		return (-EIO);
847 
848 	STps = &(STp->ps[STp->partition]);
849 	if (STps->rw == ST_WRITING)	/* Writing */
850 		return st_flush_write_buffer(STp);
851 
852 	if (STp->block_size == 0)
853 		return 0;
854 
855 	backspace = ((STp->buffer)->buffer_bytes +
856 		     (STp->buffer)->read_pointer) / STp->block_size -
857 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
858 	    STp->block_size;
859 	(STp->buffer)->buffer_bytes = 0;
860 	(STp->buffer)->read_pointer = 0;
861 	result = 0;
862 	if (!seek_next) {
863 		if (STps->eof == ST_FM_HIT) {
864 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
865 			if (!result)
866 				STps->eof = ST_NOEOF;
867 			else {
868 				if (STps->drv_file >= 0)
869 					STps->drv_file++;
870 				STps->drv_block = 0;
871 			}
872 		}
873 		if (!result && backspace > 0)
874 			result = st_int_ioctl(STp, MTBSR, backspace);
875 	} else if (STps->eof == ST_FM_HIT) {
876 		if (STps->drv_file >= 0)
877 			STps->drv_file++;
878 		STps->drv_block = 0;
879 		STps->eof = ST_NOEOF;
880 	}
881 	return result;
882 
883 }
884 
885 /* Set the mode parameters */
886 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
887 {
888 	int set_it = 0;
889 	unsigned long arg;
890 
891 	if (!STp->density_changed &&
892 	    STm->default_density >= 0 &&
893 	    STm->default_density != STp->density) {
894 		arg = STm->default_density;
895 		set_it = 1;
896 	} else
897 		arg = STp->density;
898 	arg <<= MT_ST_DENSITY_SHIFT;
899 	if (!STp->blksize_changed &&
900 	    STm->default_blksize >= 0 &&
901 	    STm->default_blksize != STp->block_size) {
902 		arg |= STm->default_blksize;
903 		set_it = 1;
904 	} else
905 		arg |= STp->block_size;
906 	if (set_it &&
907 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
908 		st_printk(KERN_WARNING, STp,
909 			  "Can't set default block size to %d bytes "
910 			  "and density %x.\n",
911 			  STm->default_blksize, STm->default_density);
912 		if (modes_defined)
913 			return (-EINVAL);
914 	}
915 	return 0;
916 }
917 
918 
919 /* Lock or unlock the drive door. Don't use when st_request allocated. */
920 static int do_door_lock(struct scsi_tape * STp, int do_lock)
921 {
922 	int retval;
923 
924 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
925 
926 	retval = scsi_set_medium_removal(STp->device,
927 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
928 	if (!retval)
929 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
930 	else
931 		STp->door_locked = ST_LOCK_FAILS;
932 	return retval;
933 }
934 
935 
936 /* Set the internal state after reset */
937 static void reset_state(struct scsi_tape *STp)
938 {
939 	int i;
940 	struct st_partstat *STps;
941 
942 	STp->pos_unknown = 0;
943 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
944 		STps = &(STp->ps[i]);
945 		STps->rw = ST_IDLE;
946 		STps->eof = ST_NOEOF;
947 		STps->at_sm = 0;
948 		STps->last_block_valid = 0;
949 		STps->drv_block = -1;
950 		STps->drv_file = -1;
951 	}
952 	if (STp->can_partitions) {
953 		STp->partition = find_partition(STp);
954 		if (STp->partition < 0)
955 			STp->partition = 0;
956 		STp->new_partition = STp->partition;
957 	}
958 }
959 
960 /* Test if the drive is ready. Returns either one of the codes below or a negative system
961    error code. */
962 #define CHKRES_READY       0
963 #define CHKRES_NEW_SESSION 1
964 #define CHKRES_NOT_READY   2
965 #define CHKRES_NO_TAPE     3
966 
967 #define MAX_ATTENTIONS    10
968 
969 static int test_ready(struct scsi_tape *STp, int do_wait)
970 {
971 	int attentions, waits, max_wait, scode;
972 	int retval = CHKRES_READY, new_session = 0;
973 	unsigned char cmd[MAX_COMMAND_SIZE];
974 	struct st_request *SRpnt = NULL;
975 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
976 
977 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
978 
979 	for (attentions=waits=0; ; ) {
980 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
981 		cmd[0] = TEST_UNIT_READY;
982 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
983 				   STp->long_timeout, MAX_READY_RETRIES, 1);
984 
985 		if (!SRpnt) {
986 			retval = (STp->buffer)->syscall_result;
987 			break;
988 		}
989 
990 		if (cmdstatp->have_sense) {
991 
992 			scode = cmdstatp->sense_hdr.sense_key;
993 
994 			if (scode == UNIT_ATTENTION) { /* New media? */
995 				new_session = 1;
996 				if (attentions < MAX_ATTENTIONS) {
997 					attentions++;
998 					continue;
999 				}
1000 				else {
1001 					retval = (-EIO);
1002 					break;
1003 				}
1004 			}
1005 
1006 			if (scode == NOT_READY) {
1007 				if (waits < max_wait) {
1008 					if (msleep_interruptible(1000)) {
1009 						retval = (-EINTR);
1010 						break;
1011 					}
1012 					waits++;
1013 					continue;
1014 				}
1015 				else {
1016 					if ((STp->device)->scsi_level >= SCSI_2 &&
1017 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1018 						retval = CHKRES_NO_TAPE;
1019 					else
1020 						retval = CHKRES_NOT_READY;
1021 					break;
1022 				}
1023 			}
1024 		}
1025 
1026 		retval = (STp->buffer)->syscall_result;
1027 		if (!retval)
1028 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1029 		break;
1030 	}
1031 
1032 	if (SRpnt != NULL)
1033 		st_release_request(SRpnt);
1034 	return retval;
1035 }
1036 
1037 
1038 /* See if the drive is ready and gather information about the tape. Return values:
1039    < 0   negative error code from errno.h
1040    0     drive ready
1041    1     drive not ready (possibly no tape)
1042 */
1043 static int check_tape(struct scsi_tape *STp, struct file *filp)
1044 {
1045 	int i, retval, new_session = 0, do_wait;
1046 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1047 	unsigned short st_flags = filp->f_flags;
1048 	struct st_request *SRpnt = NULL;
1049 	struct st_modedef *STm;
1050 	struct st_partstat *STps;
1051 	struct inode *inode = file_inode(filp);
1052 	int mode = TAPE_MODE(inode);
1053 
1054 	STp->ready = ST_READY;
1055 
1056 	if (mode != STp->current_mode) {
1057 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1058 			    STp->current_mode, mode);
1059 		new_session = 1;
1060 		STp->current_mode = mode;
1061 	}
1062 	STm = &(STp->modes[STp->current_mode]);
1063 
1064 	saved_cleaning = STp->cleaning_req;
1065 	STp->cleaning_req = 0;
1066 
1067 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1068 	retval = test_ready(STp, do_wait);
1069 
1070 	if (retval < 0)
1071 	    goto err_out;
1072 
1073 	if (retval == CHKRES_NEW_SESSION) {
1074 		STp->pos_unknown = 0;
1075 		STp->partition = STp->new_partition = 0;
1076 		if (STp->can_partitions)
1077 			STp->nbr_partitions = 1; /* This guess will be updated later
1078                                                     if necessary */
1079 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1080 			STps = &(STp->ps[i]);
1081 			STps->rw = ST_IDLE;
1082 			STps->eof = ST_NOEOF;
1083 			STps->at_sm = 0;
1084 			STps->last_block_valid = 0;
1085 			STps->drv_block = 0;
1086 			STps->drv_file = 0;
1087 		}
1088 		new_session = 1;
1089 	}
1090 	else {
1091 		STp->cleaning_req |= saved_cleaning;
1092 
1093 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1094 			if (retval == CHKRES_NO_TAPE)
1095 				STp->ready = ST_NO_TAPE;
1096 			else
1097 				STp->ready = ST_NOT_READY;
1098 
1099 			STp->density = 0;	/* Clear the erroneous "residue" */
1100 			STp->write_prot = 0;
1101 			STp->block_size = 0;
1102 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1103 			STp->partition = STp->new_partition = 0;
1104 			STp->door_locked = ST_UNLOCKED;
1105 			return CHKRES_NOT_READY;
1106 		}
1107 	}
1108 
1109 	if (STp->omit_blklims)
1110 		STp->min_block = STp->max_block = (-1);
1111 	else {
1112 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1113 		cmd[0] = READ_BLOCK_LIMITS;
1114 
1115 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1116 				   STp->device->request_queue->rq_timeout,
1117 				   MAX_READY_RETRIES, 1);
1118 		if (!SRpnt) {
1119 			retval = (STp->buffer)->syscall_result;
1120 			goto err_out;
1121 		}
1122 
1123 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1124 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1125 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1126 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1127 			    (STp->buffer)->b_data[5];
1128 			if ( DEB( debugging || ) !STp->inited)
1129 				st_printk(KERN_INFO, STp,
1130 					  "Block limits %d - %d bytes.\n",
1131 					  STp->min_block, STp->max_block);
1132 		} else {
1133 			STp->min_block = STp->max_block = (-1);
1134 			DEBC_printk(STp, "Can't read block limits.\n");
1135 		}
1136 	}
1137 
1138 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1139 	cmd[0] = MODE_SENSE;
1140 	cmd[4] = 12;
1141 
1142 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1143 			   STp->device->request_queue->rq_timeout,
1144 			   MAX_READY_RETRIES, 1);
1145 	if (!SRpnt) {
1146 		retval = (STp->buffer)->syscall_result;
1147 		goto err_out;
1148 	}
1149 
1150 	if ((STp->buffer)->syscall_result != 0) {
1151 		DEBC_printk(STp, "No Mode Sense.\n");
1152 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1153 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1154 		STp->drv_write_prot = 0;
1155 	} else {
1156 		DEBC_printk(STp,"Mode sense. Length %d, "
1157 			    "medium %x, WBS %x, BLL %d\n",
1158 			    (STp->buffer)->b_data[0],
1159 			    (STp->buffer)->b_data[1],
1160 			    (STp->buffer)->b_data[2],
1161 			    (STp->buffer)->b_data[3]);
1162 
1163 		if ((STp->buffer)->b_data[3] >= 8) {
1164 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1165 			STp->density = (STp->buffer)->b_data[4];
1166 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1167 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1168 			DEBC_printk(STp, "Density %x, tape length: %x, "
1169 				    "drv buffer: %d\n",
1170 				    STp->density,
1171 				    (STp->buffer)->b_data[5] * 65536 +
1172 				    (STp->buffer)->b_data[6] * 256 +
1173 				    (STp->buffer)->b_data[7],
1174 				    STp->drv_buffer);
1175 		}
1176 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1177 		if (!STp->drv_buffer && STp->immediate_filemark) {
1178 			st_printk(KERN_WARNING, STp,
1179 				  "non-buffered tape: disabling "
1180 				  "writing immediate filemarks\n");
1181 			STp->immediate_filemark = 0;
1182 		}
1183 	}
1184 	st_release_request(SRpnt);
1185 	SRpnt = NULL;
1186 	STp->inited = 1;
1187 
1188 	if (STp->block_size > 0)
1189 		(STp->buffer)->buffer_blocks =
1190 			(STp->buffer)->buffer_size / STp->block_size;
1191 	else
1192 		(STp->buffer)->buffer_blocks = 1;
1193 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1194 
1195 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1196 		    STp->block_size, (STp->buffer)->buffer_size,
1197 		    (STp->buffer)->buffer_blocks);
1198 
1199 	if (STp->drv_write_prot) {
1200 		STp->write_prot = 1;
1201 
1202 		DEBC_printk(STp, "Write protected\n");
1203 
1204 		if (do_wait &&
1205 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1206 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1207 			retval = (-EROFS);
1208 			goto err_out;
1209 		}
1210 	}
1211 
1212 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1213 		/* This code is reached when the device is opened for the first time
1214 		   after the driver has been initialized with tape in the drive and the
1215 		   partition support has been enabled. */
1216 		DEBC_printk(STp, "Updating partition number in status.\n");
1217 		if ((STp->partition = find_partition(STp)) < 0) {
1218 			retval = STp->partition;
1219 			goto err_out;
1220 		}
1221 		STp->new_partition = STp->partition;
1222 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1223 	}
1224 
1225 	if (new_session) {	/* Change the drive parameters for the new mode */
1226 		STp->density_changed = STp->blksize_changed = 0;
1227 		STp->compression_changed = 0;
1228 		if (!(STm->defaults_for_writes) &&
1229 		    (retval = set_mode_densblk(STp, STm)) < 0)
1230 		    goto err_out;
1231 
1232 		if (STp->default_drvbuffer != 0xff) {
1233 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1234 				st_printk(KERN_WARNING, STp,
1235 					  "Can't set default drive "
1236 					  "buffering to %d.\n",
1237 					  STp->default_drvbuffer);
1238 		}
1239 	}
1240 
1241 	return CHKRES_READY;
1242 
1243  err_out:
1244 	return retval;
1245 }
1246 
1247 
1248 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1249    module count. */
1250 static int st_open(struct inode *inode, struct file *filp)
1251 {
1252 	int i, retval = (-EIO);
1253 	int resumed = 0;
1254 	struct scsi_tape *STp;
1255 	struct st_partstat *STps;
1256 	int dev = TAPE_NR(inode);
1257 
1258 	/*
1259 	 * We really want to do nonseekable_open(inode, filp); here, but some
1260 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1261 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1262 	 */
1263 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1264 
1265 	if (!(STp = scsi_tape_get(dev))) {
1266 		return -ENXIO;
1267 	}
1268 
1269 	filp->private_data = STp;
1270 
1271 	spin_lock(&st_use_lock);
1272 	if (STp->in_use) {
1273 		spin_unlock(&st_use_lock);
1274 		DEBC_printk(STp, "Device already in use.\n");
1275 		scsi_tape_put(STp);
1276 		return (-EBUSY);
1277 	}
1278 
1279 	STp->in_use = 1;
1280 	spin_unlock(&st_use_lock);
1281 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1282 
1283 	if (scsi_autopm_get_device(STp->device) < 0) {
1284 		retval = -EIO;
1285 		goto err_out;
1286 	}
1287 	resumed = 1;
1288 	if (!scsi_block_when_processing_errors(STp->device)) {
1289 		retval = (-ENXIO);
1290 		goto err_out;
1291 	}
1292 
1293 	/* See that we have at least a one page buffer available */
1294 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE)) {
1295 		st_printk(KERN_WARNING, STp,
1296 			  "Can't allocate one page tape buffer.\n");
1297 		retval = (-EOVERFLOW);
1298 		goto err_out;
1299 	}
1300 
1301 	(STp->buffer)->cleared = 0;
1302 	(STp->buffer)->writing = 0;
1303 	(STp->buffer)->syscall_result = 0;
1304 
1305 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1306 
1307 	STp->dirty = 0;
1308 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1309 		STps = &(STp->ps[i]);
1310 		STps->rw = ST_IDLE;
1311 	}
1312 	STp->try_dio_now = STp->try_dio;
1313 	STp->recover_count = 0;
1314 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1315 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1316 
1317 	retval = check_tape(STp, filp);
1318 	if (retval < 0)
1319 		goto err_out;
1320 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1321 	    retval != CHKRES_READY) {
1322 		if (STp->ready == NO_TAPE)
1323 			retval = (-ENOMEDIUM);
1324 		else
1325 			retval = (-EIO);
1326 		goto err_out;
1327 	}
1328 	return 0;
1329 
1330  err_out:
1331 	normalize_buffer(STp->buffer);
1332 	spin_lock(&st_use_lock);
1333 	STp->in_use = 0;
1334 	spin_unlock(&st_use_lock);
1335 	if (resumed)
1336 		scsi_autopm_put_device(STp->device);
1337 	scsi_tape_put(STp);
1338 	return retval;
1339 
1340 }
1341 
1342 
1343 /* Flush the tape buffer before close */
1344 static int st_flush(struct file *filp, fl_owner_t id)
1345 {
1346 	int result = 0, result2;
1347 	unsigned char cmd[MAX_COMMAND_SIZE];
1348 	struct st_request *SRpnt;
1349 	struct scsi_tape *STp = filp->private_data;
1350 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1351 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1352 
1353 	if (file_count(filp) > 1)
1354 		return 0;
1355 
1356 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1357 		result = st_flush_write_buffer(STp);
1358 		if (result != 0 && result != (-ENOSPC))
1359 			goto out;
1360 	}
1361 
1362 	if (STp->can_partitions &&
1363 	    (result2 = switch_partition(STp)) < 0) {
1364 		DEBC_printk(STp, "switch_partition at close failed.\n");
1365 		if (result == 0)
1366 			result = result2;
1367 		goto out;
1368 	}
1369 
1370 	DEBC( if (STp->nbr_requests)
1371 		st_printk(KERN_DEBUG, STp,
1372 			  "Number of r/w requests %d, dio used in %d, "
1373 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1374 			  STp->nbr_pages));
1375 
1376 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1377 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1378 
1379 #if DEBUG
1380 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1381 			    STp->nbr_waits, STp->nbr_finished);
1382 #endif
1383 		memset(cmd, 0, MAX_COMMAND_SIZE);
1384 		cmd[0] = WRITE_FILEMARKS;
1385 		if (STp->immediate_filemark)
1386 			cmd[1] = 1;
1387 		cmd[4] = 1 + STp->two_fm;
1388 
1389 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1390 				   STp->device->request_queue->rq_timeout,
1391 				   MAX_WRITE_RETRIES, 1);
1392 		if (!SRpnt) {
1393 			result = (STp->buffer)->syscall_result;
1394 			goto out;
1395 		}
1396 
1397 		if (STp->buffer->syscall_result == 0 ||
1398 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1399 		     (cmdstatp->flags & SENSE_EOM) &&
1400 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1401 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1402 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1403 			/* Write successful at EOM */
1404 			st_release_request(SRpnt);
1405 			SRpnt = NULL;
1406 			if (STps->drv_file >= 0)
1407 				STps->drv_file++;
1408 			STps->drv_block = 0;
1409 			if (STp->two_fm)
1410 				cross_eof(STp, 0);
1411 			STps->eof = ST_FM;
1412 		}
1413 		else { /* Write error */
1414 			st_release_request(SRpnt);
1415 			SRpnt = NULL;
1416 			st_printk(KERN_ERR, STp,
1417 				  "Error on write filemark.\n");
1418 			if (result == 0)
1419 				result = (-EIO);
1420 		}
1421 
1422 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1423 	} else if (!STp->rew_at_close) {
1424 		STps = &(STp->ps[STp->partition]);
1425 		if (!STm->sysv || STps->rw != ST_READING) {
1426 			if (STp->can_bsr)
1427 				result = flush_buffer(STp, 0);
1428 			else if (STps->eof == ST_FM_HIT) {
1429 				result = cross_eof(STp, 0);
1430 				if (result) {
1431 					if (STps->drv_file >= 0)
1432 						STps->drv_file++;
1433 					STps->drv_block = 0;
1434 					STps->eof = ST_FM;
1435 				} else
1436 					STps->eof = ST_NOEOF;
1437 			}
1438 		} else if ((STps->eof == ST_NOEOF &&
1439 			    !(result = cross_eof(STp, 1))) ||
1440 			   STps->eof == ST_FM_HIT) {
1441 			if (STps->drv_file >= 0)
1442 				STps->drv_file++;
1443 			STps->drv_block = 0;
1444 			STps->eof = ST_FM;
1445 		}
1446 	}
1447 
1448       out:
1449 	if (STp->rew_at_close) {
1450 		result2 = st_int_ioctl(STp, MTREW, 1);
1451 		if (result == 0)
1452 			result = result2;
1453 	}
1454 	return result;
1455 }
1456 
1457 
1458 /* Close the device and release it. BKL is not needed: this is the only thread
1459    accessing this tape. */
1460 static int st_release(struct inode *inode, struct file *filp)
1461 {
1462 	struct scsi_tape *STp = filp->private_data;
1463 
1464 	if (STp->door_locked == ST_LOCKED_AUTO)
1465 		do_door_lock(STp, 0);
1466 
1467 	normalize_buffer(STp->buffer);
1468 	spin_lock(&st_use_lock);
1469 	STp->in_use = 0;
1470 	spin_unlock(&st_use_lock);
1471 	scsi_autopm_put_device(STp->device);
1472 	scsi_tape_put(STp);
1473 
1474 	return 0;
1475 }
1476 
1477 /* The checks common to both reading and writing */
1478 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1479 {
1480 	ssize_t retval = 0;
1481 
1482 	/*
1483 	 * If we are in the middle of error recovery, don't let anyone
1484 	 * else try and use this device.  Also, if error recovery fails, it
1485 	 * may try and take the device offline, in which case all further
1486 	 * access to the device is prohibited.
1487 	 */
1488 	if (!scsi_block_when_processing_errors(STp->device)) {
1489 		retval = (-ENXIO);
1490 		goto out;
1491 	}
1492 
1493 	if (STp->ready != ST_READY) {
1494 		if (STp->ready == ST_NO_TAPE)
1495 			retval = (-ENOMEDIUM);
1496 		else
1497 			retval = (-EIO);
1498 		goto out;
1499 	}
1500 
1501 	if (! STp->modes[STp->current_mode].defined) {
1502 		retval = (-ENXIO);
1503 		goto out;
1504 	}
1505 
1506 
1507 	/*
1508 	 * If there was a bus reset, block further access
1509 	 * to this device.
1510 	 */
1511 	if (STp->pos_unknown) {
1512 		retval = (-EIO);
1513 		goto out;
1514 	}
1515 
1516 	if (count == 0)
1517 		goto out;
1518 
1519 	DEB(
1520 	if (!STp->in_use) {
1521 		st_printk(ST_DEB_MSG, STp,
1522 			  "Incorrect device.\n");
1523 		retval = (-EIO);
1524 		goto out;
1525 	} ) /* end DEB */
1526 
1527 	if (STp->can_partitions &&
1528 	    (retval = switch_partition(STp)) < 0)
1529 		goto out;
1530 
1531 	if (STp->block_size == 0 && STp->max_block > 0 &&
1532 	    (count < STp->min_block || count > STp->max_block)) {
1533 		retval = (-EINVAL);
1534 		goto out;
1535 	}
1536 
1537 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1538 	    !do_door_lock(STp, 1))
1539 		STp->door_locked = ST_LOCKED_AUTO;
1540 
1541  out:
1542 	return retval;
1543 }
1544 
1545 
1546 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1547 			   size_t count, int is_read)
1548 {
1549 	int i, bufsize, retval = 0;
1550 	struct st_buffer *STbp = STp->buffer;
1551 
1552 	if (is_read)
1553 		i = STp->try_dio_now && try_rdio;
1554 	else
1555 		i = STp->try_dio_now && try_wdio;
1556 
1557 	if (i && ((unsigned long)buf & queue_dma_alignment(
1558 					STp->device->request_queue)) == 0) {
1559 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1560 				       count, (is_read ? READ : WRITE));
1561 		if (i > 0) {
1562 			STbp->do_dio = i;
1563 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1564 		}
1565 		else
1566 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1567 		STbp->sg_segs = STbp->do_dio;
1568 		DEB(
1569 		     if (STbp->do_dio) {
1570 			STp->nbr_dio++;
1571 			STp->nbr_pages += STbp->do_dio;
1572 		     }
1573 		)
1574 	} else
1575 		STbp->do_dio = 0;
1576 	DEB( STp->nbr_requests++; )
1577 
1578 	if (!STbp->do_dio) {
1579 		if (STp->block_size)
1580 			bufsize = STp->block_size > st_fixed_buffer_size ?
1581 				STp->block_size : st_fixed_buffer_size;
1582 		else {
1583 			bufsize = count;
1584 			/* Make sure that data from previous user is not leaked even if
1585 			   HBA does not return correct residual */
1586 			if (is_read && STp->sili && !STbp->cleared)
1587 				clear_buffer(STbp);
1588 		}
1589 
1590 		if (bufsize > STbp->buffer_size &&
1591 		    !enlarge_buffer(STbp, bufsize)) {
1592 			st_printk(KERN_WARNING, STp,
1593 				  "Can't allocate %d byte tape buffer.\n",
1594 				  bufsize);
1595 			retval = (-EOVERFLOW);
1596 			goto out;
1597 		}
1598 		if (STp->block_size)
1599 			STbp->buffer_blocks = bufsize / STp->block_size;
1600 	}
1601 
1602  out:
1603 	return retval;
1604 }
1605 
1606 
1607 /* Can be called more than once after each setup_buffer() */
1608 static void release_buffering(struct scsi_tape *STp, int is_read)
1609 {
1610 	struct st_buffer *STbp;
1611 
1612 	STbp = STp->buffer;
1613 	if (STbp->do_dio) {
1614 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1615 		STbp->do_dio = 0;
1616 		STbp->sg_segs = 0;
1617 	}
1618 }
1619 
1620 
1621 /* Write command */
1622 static ssize_t
1623 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1624 {
1625 	ssize_t total;
1626 	ssize_t i, do_count, blks, transfer;
1627 	ssize_t retval;
1628 	int undone, retry_eot = 0, scode;
1629 	int async_write;
1630 	unsigned char cmd[MAX_COMMAND_SIZE];
1631 	const char __user *b_point;
1632 	struct st_request *SRpnt = NULL;
1633 	struct scsi_tape *STp = filp->private_data;
1634 	struct st_modedef *STm;
1635 	struct st_partstat *STps;
1636 	struct st_buffer *STbp;
1637 
1638 	if (mutex_lock_interruptible(&STp->lock))
1639 		return -ERESTARTSYS;
1640 
1641 	retval = rw_checks(STp, filp, count);
1642 	if (retval || count == 0)
1643 		goto out;
1644 
1645 	/* Write must be integral number of blocks */
1646 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1647 		st_printk(KERN_WARNING, STp,
1648 			  "Write not multiple of tape block size.\n");
1649 		retval = (-EINVAL);
1650 		goto out;
1651 	}
1652 
1653 	STm = &(STp->modes[STp->current_mode]);
1654 	STps = &(STp->ps[STp->partition]);
1655 
1656 	if (STp->write_prot) {
1657 		retval = (-EACCES);
1658 		goto out;
1659 	}
1660 
1661 
1662 	if (STps->rw == ST_READING) {
1663 		retval = flush_buffer(STp, 0);
1664 		if (retval)
1665 			goto out;
1666 		STps->rw = ST_WRITING;
1667 	} else if (STps->rw != ST_WRITING &&
1668 		   STps->drv_file == 0 && STps->drv_block == 0) {
1669 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1670 			goto out;
1671 		if (STm->default_compression != ST_DONT_TOUCH &&
1672 		    !(STp->compression_changed)) {
1673 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1674 				st_printk(KERN_WARNING, STp,
1675 					  "Can't set default compression.\n");
1676 				if (modes_defined) {
1677 					retval = (-EINVAL);
1678 					goto out;
1679 				}
1680 			}
1681 		}
1682 	}
1683 
1684 	STbp = STp->buffer;
1685 	i = write_behind_check(STp);
1686 	if (i) {
1687 		if (i == -ENOSPC)
1688 			STps->eof = ST_EOM_OK;
1689 		else
1690 			STps->eof = ST_EOM_ERROR;
1691 	}
1692 
1693 	if (STps->eof == ST_EOM_OK) {
1694 		STps->eof = ST_EOD_1;  /* allow next write */
1695 		retval = (-ENOSPC);
1696 		goto out;
1697 	}
1698 	else if (STps->eof == ST_EOM_ERROR) {
1699 		retval = (-EIO);
1700 		goto out;
1701 	}
1702 
1703 	/* Check the buffer readability in cases where copy_user might catch
1704 	   the problems after some tape movement. */
1705 	if (STp->block_size != 0 &&
1706 	    !STbp->do_dio &&
1707 	    (copy_from_user(&i, buf, 1) != 0 ||
1708 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1709 		retval = (-EFAULT);
1710 		goto out;
1711 	}
1712 
1713 	retval = setup_buffering(STp, buf, count, 0);
1714 	if (retval)
1715 		goto out;
1716 
1717 	total = count;
1718 
1719 	memset(cmd, 0, MAX_COMMAND_SIZE);
1720 	cmd[0] = WRITE_6;
1721 	cmd[1] = (STp->block_size != 0);
1722 
1723 	STps->rw = ST_WRITING;
1724 
1725 	b_point = buf;
1726 	while (count > 0 && !retry_eot) {
1727 
1728 		if (STbp->do_dio) {
1729 			do_count = count;
1730 		}
1731 		else {
1732 			if (STp->block_size == 0)
1733 				do_count = count;
1734 			else {
1735 				do_count = STbp->buffer_blocks * STp->block_size -
1736 					STbp->buffer_bytes;
1737 				if (do_count > count)
1738 					do_count = count;
1739 			}
1740 
1741 			i = append_to_buffer(b_point, STbp, do_count);
1742 			if (i) {
1743 				retval = i;
1744 				goto out;
1745 			}
1746 		}
1747 		count -= do_count;
1748 		b_point += do_count;
1749 
1750 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1751 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1752 
1753 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1754 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1755 		    STbp->buffer_bytes < STbp->buffer_size) {
1756 			STp->dirty = 1;
1757 			/* Don't write a buffer that is not full enough. */
1758 			if (!async_write && count == 0)
1759 				break;
1760 		}
1761 
1762 	retry_write:
1763 		if (STp->block_size == 0)
1764 			blks = transfer = do_count;
1765 		else {
1766 			if (!STbp->do_dio)
1767 				blks = STbp->buffer_bytes;
1768 			else
1769 				blks = do_count;
1770 			blks /= STp->block_size;
1771 			transfer = blks * STp->block_size;
1772 		}
1773 		cmd[2] = blks >> 16;
1774 		cmd[3] = blks >> 8;
1775 		cmd[4] = blks;
1776 
1777 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1778 				   STp->device->request_queue->rq_timeout,
1779 				   MAX_WRITE_RETRIES, !async_write);
1780 		if (!SRpnt) {
1781 			retval = STbp->syscall_result;
1782 			goto out;
1783 		}
1784 		if (async_write && !STbp->syscall_result) {
1785 			STbp->writing = transfer;
1786 			STp->dirty = !(STbp->writing ==
1787 				       STbp->buffer_bytes);
1788 			SRpnt = NULL;  /* Prevent releasing this request! */
1789 			DEB( STp->write_pending = 1; )
1790 			break;
1791 		}
1792 
1793 		if (STbp->syscall_result != 0) {
1794 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1795 
1796 			DEBC_printk(STp, "Error on write:\n");
1797 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1798 				scode = cmdstatp->sense_hdr.sense_key;
1799 				if (cmdstatp->remainder_valid)
1800 					undone = (int)cmdstatp->uremainder64;
1801 				else if (STp->block_size == 0 &&
1802 					 scode == VOLUME_OVERFLOW)
1803 					undone = transfer;
1804 				else
1805 					undone = 0;
1806 				if (STp->block_size != 0)
1807 					undone *= STp->block_size;
1808 				if (undone <= do_count) {
1809 					/* Only data from this write is not written */
1810 					count += undone;
1811 					b_point -= undone;
1812 					do_count -= undone;
1813 					if (STp->block_size)
1814 						blks = (transfer - undone) / STp->block_size;
1815 					STps->eof = ST_EOM_OK;
1816 					/* Continue in fixed block mode if all written
1817 					   in this request but still something left to write
1818 					   (retval left to zero)
1819 					*/
1820 					if (STp->block_size == 0 ||
1821 					    undone > 0 || count == 0)
1822 						retval = (-ENOSPC); /* EOM within current request */
1823 					DEBC_printk(STp, "EOM with %d "
1824 						    "bytes unwritten.\n",
1825 						    (int)count);
1826 				} else {
1827 					/* EOT within data buffered earlier (possible only
1828 					   in fixed block mode without direct i/o) */
1829 					if (!retry_eot && !cmdstatp->deferred &&
1830 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1831 						move_buffer_data(STp->buffer, transfer - undone);
1832 						retry_eot = 1;
1833 						if (STps->drv_block >= 0) {
1834 							STps->drv_block += (transfer - undone) /
1835 								STp->block_size;
1836 						}
1837 						STps->eof = ST_EOM_OK;
1838 						DEBC_printk(STp, "Retry "
1839 							    "write of %d "
1840 							    "bytes at EOM.\n",
1841 							    STp->buffer->buffer_bytes);
1842 						goto retry_write;
1843 					}
1844 					else {
1845 						/* Either error within data buffered by driver or
1846 						   failed retry */
1847 						count -= do_count;
1848 						blks = do_count = 0;
1849 						STps->eof = ST_EOM_ERROR;
1850 						STps->drv_block = (-1); /* Too cautious? */
1851 						retval = (-EIO);	/* EOM for old data */
1852 						DEBC_printk(STp, "EOM with "
1853 							    "lost data.\n");
1854 					}
1855 				}
1856 			} else {
1857 				count += do_count;
1858 				STps->drv_block = (-1);		/* Too cautious? */
1859 				retval = STbp->syscall_result;
1860 			}
1861 
1862 		}
1863 
1864 		if (STps->drv_block >= 0) {
1865 			if (STp->block_size == 0)
1866 				STps->drv_block += (do_count > 0);
1867 			else
1868 				STps->drv_block += blks;
1869 		}
1870 
1871 		STbp->buffer_bytes = 0;
1872 		STp->dirty = 0;
1873 
1874 		if (retval || retry_eot) {
1875 			if (count < total)
1876 				retval = total - count;
1877 			goto out;
1878 		}
1879 	}
1880 
1881 	if (STps->eof == ST_EOD_1)
1882 		STps->eof = ST_EOM_OK;
1883 	else if (STps->eof != ST_EOM_OK)
1884 		STps->eof = ST_NOEOF;
1885 	retval = total - count;
1886 
1887  out:
1888 	if (SRpnt != NULL)
1889 		st_release_request(SRpnt);
1890 	release_buffering(STp, 0);
1891 	mutex_unlock(&STp->lock);
1892 
1893 	return retval;
1894 }
1895 
1896 /* Read data from the tape. Returns zero in the normal case, one if the
1897    eof status has changed, and the negative error code in case of a
1898    fatal error. Otherwise updates the buffer and the eof state.
1899 
1900    Does release user buffer mapping if it is set.
1901 */
1902 static long read_tape(struct scsi_tape *STp, long count,
1903 		      struct st_request ** aSRpnt)
1904 {
1905 	int transfer, blks, bytes;
1906 	unsigned char cmd[MAX_COMMAND_SIZE];
1907 	struct st_request *SRpnt;
1908 	struct st_modedef *STm;
1909 	struct st_partstat *STps;
1910 	struct st_buffer *STbp;
1911 	int retval = 0;
1912 
1913 	if (count == 0)
1914 		return 0;
1915 
1916 	STm = &(STp->modes[STp->current_mode]);
1917 	STps = &(STp->ps[STp->partition]);
1918 	if (STps->eof == ST_FM_HIT)
1919 		return 1;
1920 	STbp = STp->buffer;
1921 
1922 	if (STp->block_size == 0)
1923 		blks = bytes = count;
1924 	else {
1925 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1926 			blks = (STp->buffer)->buffer_blocks;
1927 			bytes = blks * STp->block_size;
1928 		} else {
1929 			bytes = count;
1930 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1931 				bytes = (STp->buffer)->buffer_size;
1932 			blks = bytes / STp->block_size;
1933 			bytes = blks * STp->block_size;
1934 		}
1935 	}
1936 
1937 	memset(cmd, 0, MAX_COMMAND_SIZE);
1938 	cmd[0] = READ_6;
1939 	cmd[1] = (STp->block_size != 0);
1940 	if (!cmd[1] && STp->sili)
1941 		cmd[1] |= 2;
1942 	cmd[2] = blks >> 16;
1943 	cmd[3] = blks >> 8;
1944 	cmd[4] = blks;
1945 
1946 	SRpnt = *aSRpnt;
1947 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1948 			   STp->device->request_queue->rq_timeout,
1949 			   MAX_RETRIES, 1);
1950 	release_buffering(STp, 1);
1951 	*aSRpnt = SRpnt;
1952 	if (!SRpnt)
1953 		return STbp->syscall_result;
1954 
1955 	STbp->read_pointer = 0;
1956 	STps->at_sm = 0;
1957 
1958 	/* Something to check */
1959 	if (STbp->syscall_result) {
1960 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1961 
1962 		retval = 1;
1963 		DEBC_printk(STp,
1964 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1965 			    SRpnt->sense[0], SRpnt->sense[1],
1966 			    SRpnt->sense[2], SRpnt->sense[3],
1967 			    SRpnt->sense[4], SRpnt->sense[5],
1968 			    SRpnt->sense[6], SRpnt->sense[7]);
1969 		if (cmdstatp->have_sense) {
1970 
1971 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1972 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1973 
1974 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1975 				/* Compute the residual count */
1976 				if (cmdstatp->remainder_valid)
1977 					transfer = (int)cmdstatp->uremainder64;
1978 				else
1979 					transfer = 0;
1980 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1981 					if (STp->block_size == 0)
1982 						transfer = bytes;
1983 					/* Some drives set ILI with MEDIUM ERROR */
1984 					cmdstatp->flags &= ~SENSE_ILI;
1985 				}
1986 
1987 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1988 					if (STp->block_size == 0 &&
1989 					    transfer < 0) {
1990 						st_printk(KERN_NOTICE, STp,
1991 							  "Failed to read %d "
1992 							  "byte block with %d "
1993 							  "byte transfer.\n",
1994 							  bytes - transfer,
1995 							  bytes);
1996 						if (STps->drv_block >= 0)
1997 							STps->drv_block += 1;
1998 						STbp->buffer_bytes = 0;
1999 						return (-ENOMEM);
2000 					} else if (STp->block_size == 0) {
2001 						STbp->buffer_bytes = bytes - transfer;
2002 					} else {
2003 						st_release_request(SRpnt);
2004 						SRpnt = *aSRpnt = NULL;
2005 						if (transfer == blks) {	/* We did not get anything, error */
2006 							st_printk(KERN_NOTICE, STp,
2007 								  "Incorrect "
2008 								  "block size.\n");
2009 							if (STps->drv_block >= 0)
2010 								STps->drv_block += blks - transfer + 1;
2011 							st_int_ioctl(STp, MTBSR, 1);
2012 							return (-EIO);
2013 						}
2014 						/* We have some data, deliver it */
2015 						STbp->buffer_bytes = (blks - transfer) *
2016 						    STp->block_size;
2017 						DEBC_printk(STp, "ILI but "
2018 							    "enough data "
2019 							    "received %ld "
2020 							    "%d.\n", count,
2021 							    STbp->buffer_bytes);
2022 						if (STps->drv_block >= 0)
2023 							STps->drv_block += 1;
2024 						if (st_int_ioctl(STp, MTBSR, 1))
2025 							return (-EIO);
2026 					}
2027 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2028 					if (STps->eof != ST_FM_HIT)
2029 						STps->eof = ST_FM_HIT;
2030 					else
2031 						STps->eof = ST_EOD_2;
2032 					if (STp->block_size == 0)
2033 						STbp->buffer_bytes = 0;
2034 					else
2035 						STbp->buffer_bytes =
2036 						    bytes - transfer * STp->block_size;
2037 					DEBC_printk(STp, "EOF detected (%d "
2038 						    "bytes read).\n",
2039 						    STbp->buffer_bytes);
2040 				} else if (cmdstatp->flags & SENSE_EOM) {
2041 					if (STps->eof == ST_FM)
2042 						STps->eof = ST_EOD_1;
2043 					else
2044 						STps->eof = ST_EOM_OK;
2045 					if (STp->block_size == 0)
2046 						STbp->buffer_bytes = bytes - transfer;
2047 					else
2048 						STbp->buffer_bytes =
2049 						    bytes - transfer * STp->block_size;
2050 
2051 					DEBC_printk(STp, "EOM detected (%d "
2052 						    "bytes read).\n",
2053 						    STbp->buffer_bytes);
2054 				}
2055 			}
2056 			/* end of EOF, EOM, ILI test */
2057 			else {	/* nonzero sense key */
2058 				DEBC_printk(STp, "Tape error while reading.\n");
2059 				STps->drv_block = (-1);
2060 				if (STps->eof == ST_FM &&
2061 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2062 					DEBC_printk(STp, "Zero returned for "
2063 						    "first BLANK CHECK "
2064 						    "after EOF.\n");
2065 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2066 				} else	/* Some other extended sense code */
2067 					retval = (-EIO);
2068 			}
2069 
2070 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2071 				STbp->buffer_bytes = 0;
2072 		}
2073 		/* End of extended sense test */
2074 		else {		/* Non-extended sense */
2075 			retval = STbp->syscall_result;
2076 		}
2077 
2078 	}
2079 	/* End of error handling */
2080 	else {			/* Read successful */
2081 		STbp->buffer_bytes = bytes;
2082 		if (STp->sili) /* In fixed block mode residual is always zero here */
2083 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2084 	}
2085 
2086 	if (STps->drv_block >= 0) {
2087 		if (STp->block_size == 0)
2088 			STps->drv_block++;
2089 		else
2090 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2091 	}
2092 	return retval;
2093 }
2094 
2095 
2096 /* Read command */
2097 static ssize_t
2098 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2099 {
2100 	ssize_t total;
2101 	ssize_t retval = 0;
2102 	ssize_t i, transfer;
2103 	int special, do_dio = 0;
2104 	struct st_request *SRpnt = NULL;
2105 	struct scsi_tape *STp = filp->private_data;
2106 	struct st_modedef *STm;
2107 	struct st_partstat *STps;
2108 	struct st_buffer *STbp = STp->buffer;
2109 
2110 	if (mutex_lock_interruptible(&STp->lock))
2111 		return -ERESTARTSYS;
2112 
2113 	retval = rw_checks(STp, filp, count);
2114 	if (retval || count == 0)
2115 		goto out;
2116 
2117 	STm = &(STp->modes[STp->current_mode]);
2118 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2119 		if (!STm->do_read_ahead) {
2120 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2121 			goto out;
2122 		}
2123 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2124 	}
2125 
2126 	STps = &(STp->ps[STp->partition]);
2127 	if (STps->rw == ST_WRITING) {
2128 		retval = flush_buffer(STp, 0);
2129 		if (retval)
2130 			goto out;
2131 		STps->rw = ST_READING;
2132 	}
2133 	DEB(
2134 	if (debugging && STps->eof != ST_NOEOF)
2135 		st_printk(ST_DEB_MSG, STp,
2136 			  "EOF/EOM flag up (%d). Bytes %d\n",
2137 			  STps->eof, STbp->buffer_bytes);
2138 	) /* end DEB */
2139 
2140 	retval = setup_buffering(STp, buf, count, 1);
2141 	if (retval)
2142 		goto out;
2143 	do_dio = STbp->do_dio;
2144 
2145 	if (STbp->buffer_bytes == 0 &&
2146 	    STps->eof >= ST_EOD_1) {
2147 		if (STps->eof < ST_EOD) {
2148 			STps->eof += 1;
2149 			retval = 0;
2150 			goto out;
2151 		}
2152 		retval = (-EIO);	/* EOM or Blank Check */
2153 		goto out;
2154 	}
2155 
2156 	if (do_dio) {
2157 		/* Check the buffer writability before any tape movement. Don't alter
2158 		   buffer data. */
2159 		if (copy_from_user(&i, buf, 1) != 0 ||
2160 		    copy_to_user(buf, &i, 1) != 0 ||
2161 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2162 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2163 			retval = (-EFAULT);
2164 			goto out;
2165 		}
2166 	}
2167 
2168 	STps->rw = ST_READING;
2169 
2170 
2171 	/* Loop until enough data in buffer or a special condition found */
2172 	for (total = 0, special = 0; total < count && !special;) {
2173 
2174 		/* Get new data if the buffer is empty */
2175 		if (STbp->buffer_bytes == 0) {
2176 			special = read_tape(STp, count - total, &SRpnt);
2177 			if (special < 0) {	/* No need to continue read */
2178 				retval = special;
2179 				goto out;
2180 			}
2181 		}
2182 
2183 		/* Move the data from driver buffer to user buffer */
2184 		if (STbp->buffer_bytes > 0) {
2185 			DEB(
2186 			if (debugging && STps->eof != ST_NOEOF)
2187 				st_printk(ST_DEB_MSG, STp,
2188 					  "EOF up (%d). Left %d, needed %d.\n",
2189 					  STps->eof, STbp->buffer_bytes,
2190 					  (int)(count - total));
2191 			) /* end DEB */
2192 			transfer = STbp->buffer_bytes < count - total ?
2193 			    STbp->buffer_bytes : count - total;
2194 			if (!do_dio) {
2195 				i = from_buffer(STbp, buf, transfer);
2196 				if (i) {
2197 					retval = i;
2198 					goto out;
2199 				}
2200 			}
2201 			buf += transfer;
2202 			total += transfer;
2203 		}
2204 
2205 		if (STp->block_size == 0)
2206 			break;	/* Read only one variable length block */
2207 
2208 	}			/* for (total = 0, special = 0;
2209                                    total < count && !special; ) */
2210 
2211 	/* Change the eof state if no data from tape or buffer */
2212 	if (total == 0) {
2213 		if (STps->eof == ST_FM_HIT) {
2214 			STps->eof = ST_FM;
2215 			STps->drv_block = 0;
2216 			if (STps->drv_file >= 0)
2217 				STps->drv_file++;
2218 		} else if (STps->eof == ST_EOD_1) {
2219 			STps->eof = ST_EOD_2;
2220 			STps->drv_block = 0;
2221 			if (STps->drv_file >= 0)
2222 				STps->drv_file++;
2223 		} else if (STps->eof == ST_EOD_2)
2224 			STps->eof = ST_EOD;
2225 	} else if (STps->eof == ST_FM)
2226 		STps->eof = ST_NOEOF;
2227 	retval = total;
2228 
2229  out:
2230 	if (SRpnt != NULL) {
2231 		st_release_request(SRpnt);
2232 		SRpnt = NULL;
2233 	}
2234 	if (do_dio) {
2235 		release_buffering(STp, 1);
2236 		STbp->buffer_bytes = 0;
2237 	}
2238 	mutex_unlock(&STp->lock);
2239 
2240 	return retval;
2241 }
2242 
2243 
2244 
2245 DEB(
2246 /* Set the driver options */
2247 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2248 {
2249 	if (debugging) {
2250 		st_printk(KERN_INFO, STp,
2251 			  "Mode %d options: buffer writes: %d, "
2252 			  "async writes: %d, read ahead: %d\n",
2253 			  STp->current_mode, STm->do_buffer_writes,
2254 			  STm->do_async_writes, STm->do_read_ahead);
2255 		st_printk(KERN_INFO, STp,
2256 			  "    can bsr: %d, two FMs: %d, "
2257 			  "fast mteom: %d, auto lock: %d,\n",
2258 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2259 			  STp->do_auto_lock);
2260 		st_printk(KERN_INFO, STp,
2261 			  "    defs for wr: %d, no block limits: %d, "
2262 			  "partitions: %d, s2 log: %d\n",
2263 			  STm->defaults_for_writes, STp->omit_blklims,
2264 			  STp->can_partitions, STp->scsi2_logical);
2265 		st_printk(KERN_INFO, STp,
2266 			  "    sysv: %d nowait: %d sili: %d "
2267 			  "nowait_filemark: %d\n",
2268 			  STm->sysv, STp->immediate, STp->sili,
2269 			  STp->immediate_filemark);
2270 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2271 	}
2272 }
2273 	)
2274 
2275 
2276 static int st_set_options(struct scsi_tape *STp, long options)
2277 {
2278 	int value;
2279 	long code;
2280 	struct st_modedef *STm;
2281 	struct cdev *cd0, *cd1;
2282 	struct device *d0, *d1;
2283 
2284 	STm = &(STp->modes[STp->current_mode]);
2285 	if (!STm->defined) {
2286 		cd0 = STm->cdevs[0];
2287 		cd1 = STm->cdevs[1];
2288 		d0  = STm->devs[0];
2289 		d1  = STm->devs[1];
2290 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2291 		STm->cdevs[0] = cd0;
2292 		STm->cdevs[1] = cd1;
2293 		STm->devs[0]  = d0;
2294 		STm->devs[1]  = d1;
2295 		modes_defined = 1;
2296 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2297 			    STp->current_mode);
2298 	}
2299 
2300 	code = options & MT_ST_OPTIONS;
2301 	if (code == MT_ST_BOOLEANS) {
2302 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2303 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2304 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2305 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2306 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2307 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2308 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2309 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2310 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2311 		if ((STp->device)->scsi_level >= SCSI_2)
2312 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2313 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2314 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2315 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2316 		STm->sysv = (options & MT_ST_SYSV) != 0;
2317 		STp->sili = (options & MT_ST_SILI) != 0;
2318 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2319 		     st_log_options(STp, STm); )
2320 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2321 		value = (code == MT_ST_SETBOOLEANS);
2322 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2323 			STm->do_buffer_writes = value;
2324 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2325 			STm->do_async_writes = value;
2326 		if ((options & MT_ST_DEF_WRITES) != 0)
2327 			STm->defaults_for_writes = value;
2328 		if ((options & MT_ST_READ_AHEAD) != 0)
2329 			STm->do_read_ahead = value;
2330 		if ((options & MT_ST_TWO_FM) != 0)
2331 			STp->two_fm = value;
2332 		if ((options & MT_ST_FAST_MTEOM) != 0)
2333 			STp->fast_mteom = value;
2334 		if ((options & MT_ST_AUTO_LOCK) != 0)
2335 			STp->do_auto_lock = value;
2336 		if ((options & MT_ST_CAN_BSR) != 0)
2337 			STp->can_bsr = value;
2338 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2339 			STp->omit_blklims = value;
2340 		if ((STp->device)->scsi_level >= SCSI_2 &&
2341 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2342 			STp->can_partitions = value;
2343 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2344 			STp->scsi2_logical = value;
2345 		if ((options & MT_ST_NOWAIT) != 0)
2346 			STp->immediate = value;
2347 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2348 			STp->immediate_filemark = value;
2349 		if ((options & MT_ST_SYSV) != 0)
2350 			STm->sysv = value;
2351 		if ((options & MT_ST_SILI) != 0)
2352 			STp->sili = value;
2353 		DEB(
2354 		if ((options & MT_ST_DEBUGGING) != 0)
2355 			debugging = value;
2356 			st_log_options(STp, STm); )
2357 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2358 		/* Retained for compatibility */
2359 	} else if (code == MT_ST_DEF_BLKSIZE) {
2360 		value = (options & ~MT_ST_OPTIONS);
2361 		if (value == ~MT_ST_OPTIONS) {
2362 			STm->default_blksize = (-1);
2363 			DEBC_printk(STp, "Default block size disabled.\n");
2364 		} else {
2365 			STm->default_blksize = value;
2366 			DEBC_printk(STp,"Default block size set to "
2367 				    "%d bytes.\n", STm->default_blksize);
2368 			if (STp->ready == ST_READY) {
2369 				STp->blksize_changed = 0;
2370 				set_mode_densblk(STp, STm);
2371 			}
2372 		}
2373 	} else if (code == MT_ST_TIMEOUTS) {
2374 		value = (options & ~MT_ST_OPTIONS);
2375 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2376 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2377 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2378 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2379 		} else {
2380 			blk_queue_rq_timeout(STp->device->request_queue,
2381 					     value * HZ);
2382 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2383 				    value);
2384 		}
2385 	} else if (code == MT_ST_SET_CLN) {
2386 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2387 		if (value != 0 &&
2388 			(value < EXTENDED_SENSE_START ||
2389 				value >= SCSI_SENSE_BUFFERSIZE))
2390 			return (-EINVAL);
2391 		STp->cln_mode = value;
2392 		STp->cln_sense_mask = (options >> 8) & 0xff;
2393 		STp->cln_sense_value = (options >> 16) & 0xff;
2394 		st_printk(KERN_INFO, STp,
2395 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2396 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2397 	} else if (code == MT_ST_DEF_OPTIONS) {
2398 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2399 		value = (options & MT_ST_CLEAR_DEFAULT);
2400 		if (code == MT_ST_DEF_DENSITY) {
2401 			if (value == MT_ST_CLEAR_DEFAULT) {
2402 				STm->default_density = (-1);
2403 				DEBC_printk(STp,
2404 					    "Density default disabled.\n");
2405 			} else {
2406 				STm->default_density = value & 0xff;
2407 				DEBC_printk(STp, "Density default set to %x\n",
2408 					    STm->default_density);
2409 				if (STp->ready == ST_READY) {
2410 					STp->density_changed = 0;
2411 					set_mode_densblk(STp, STm);
2412 				}
2413 			}
2414 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2415 			if (value == MT_ST_CLEAR_DEFAULT) {
2416 				STp->default_drvbuffer = 0xff;
2417 				DEBC_printk(STp,
2418 					    "Drive buffer default disabled.\n");
2419 			} else {
2420 				STp->default_drvbuffer = value & 7;
2421 				DEBC_printk(STp,
2422 					    "Drive buffer default set to %x\n",
2423 					    STp->default_drvbuffer);
2424 				if (STp->ready == ST_READY)
2425 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2426 			}
2427 		} else if (code == MT_ST_DEF_COMPRESSION) {
2428 			if (value == MT_ST_CLEAR_DEFAULT) {
2429 				STm->default_compression = ST_DONT_TOUCH;
2430 				DEBC_printk(STp,
2431 					    "Compression default disabled.\n");
2432 			} else {
2433 				if ((value & 0xff00) != 0) {
2434 					STp->c_algo = (value & 0xff00) >> 8;
2435 					DEBC_printk(STp, "Compression "
2436 						    "algorithm set to 0x%x.\n",
2437 						    STp->c_algo);
2438 				}
2439 				if ((value & 0xff) != 0xff) {
2440 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2441 					DEBC_printk(STp, "Compression default "
2442 						    "set to %x\n",
2443 						    (value & 1));
2444 					if (STp->ready == ST_READY) {
2445 						STp->compression_changed = 0;
2446 						st_compression(STp, (STm->default_compression == ST_YES));
2447 					}
2448 				}
2449 			}
2450 		}
2451 	} else
2452 		return (-EIO);
2453 
2454 	return 0;
2455 }
2456 
2457 #define MODE_HEADER_LENGTH  4
2458 
2459 /* Mode header and page byte offsets */
2460 #define MH_OFF_DATA_LENGTH     0
2461 #define MH_OFF_MEDIUM_TYPE     1
2462 #define MH_OFF_DEV_SPECIFIC    2
2463 #define MH_OFF_BDESCS_LENGTH   3
2464 #define MP_OFF_PAGE_NBR        0
2465 #define MP_OFF_PAGE_LENGTH     1
2466 
2467 /* Mode header and page bit masks */
2468 #define MH_BIT_WP              0x80
2469 #define MP_MSK_PAGE_NBR        0x3f
2470 
2471 /* Don't return block descriptors */
2472 #define MODE_SENSE_OMIT_BDESCS 0x08
2473 
2474 #define MODE_SELECT_PAGE_FORMAT 0x10
2475 
2476 /* Read a mode page into the tape buffer. The block descriptors are included
2477    if incl_block_descs is true. The page control is ored to the page number
2478    parameter, if necessary. */
2479 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2480 {
2481 	unsigned char cmd[MAX_COMMAND_SIZE];
2482 	struct st_request *SRpnt;
2483 
2484 	memset(cmd, 0, MAX_COMMAND_SIZE);
2485 	cmd[0] = MODE_SENSE;
2486 	if (omit_block_descs)
2487 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2488 	cmd[2] = page;
2489 	cmd[4] = 255;
2490 
2491 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2492 			   STp->device->request_queue->rq_timeout, 0, 1);
2493 	if (SRpnt == NULL)
2494 		return (STp->buffer)->syscall_result;
2495 
2496 	st_release_request(SRpnt);
2497 
2498 	return STp->buffer->syscall_result;
2499 }
2500 
2501 
2502 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2503    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2504 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2505 {
2506 	int pgo;
2507 	unsigned char cmd[MAX_COMMAND_SIZE];
2508 	struct st_request *SRpnt;
2509 	int timeout;
2510 
2511 	memset(cmd, 0, MAX_COMMAND_SIZE);
2512 	cmd[0] = MODE_SELECT;
2513 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2514 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2515 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2516 
2517 	/* Clear reserved fields */
2518 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2519 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2520 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2521 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2522 
2523 	timeout = slow ?
2524 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2525 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2526 			   timeout, 0, 1);
2527 	if (SRpnt == NULL)
2528 		return (STp->buffer)->syscall_result;
2529 
2530 	st_release_request(SRpnt);
2531 
2532 	return STp->buffer->syscall_result;
2533 }
2534 
2535 
2536 #define COMPRESSION_PAGE        0x0f
2537 #define COMPRESSION_PAGE_LENGTH 16
2538 
2539 #define CP_OFF_DCE_DCC          2
2540 #define CP_OFF_C_ALGO           7
2541 
2542 #define DCE_MASK  0x80
2543 #define DCC_MASK  0x40
2544 #define RED_MASK  0x60
2545 
2546 
2547 /* Control the compression with mode page 15. Algorithm not changed if zero.
2548 
2549    The block descriptors are read and written because Sony SDT-7000 does not
2550    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2551    Including block descriptors should not cause any harm to other drives. */
2552 
2553 static int st_compression(struct scsi_tape * STp, int state)
2554 {
2555 	int retval;
2556 	int mpoffs;  /* Offset to mode page start */
2557 	unsigned char *b_data = (STp->buffer)->b_data;
2558 
2559 	if (STp->ready != ST_READY)
2560 		return (-EIO);
2561 
2562 	/* Read the current page contents */
2563 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2564 	if (retval) {
2565 		DEBC_printk(STp, "Compression mode page not supported.\n");
2566 		return (-EIO);
2567 	}
2568 
2569 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2570 	DEBC_printk(STp, "Compression state is %d.\n",
2571 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2572 
2573 	/* Check if compression can be changed */
2574 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2575 		DEBC_printk(STp, "Compression not supported.\n");
2576 		return (-EIO);
2577 	}
2578 
2579 	/* Do the change */
2580 	if (state) {
2581 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2582 		if (STp->c_algo != 0)
2583 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2584 	}
2585 	else {
2586 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2587 		if (STp->c_algo != 0)
2588 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2589 	}
2590 
2591 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2592 	if (retval) {
2593 		DEBC_printk(STp, "Compression change failed.\n");
2594 		return (-EIO);
2595 	}
2596 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2597 
2598 	STp->compression_changed = 1;
2599 	return 0;
2600 }
2601 
2602 
2603 /* Process the load and unload commands (does unload if the load code is zero) */
2604 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2605 {
2606 	int retval = (-EIO), timeout;
2607 	unsigned char cmd[MAX_COMMAND_SIZE];
2608 	struct st_partstat *STps;
2609 	struct st_request *SRpnt;
2610 
2611 	if (STp->ready != ST_READY && !load_code) {
2612 		if (STp->ready == ST_NO_TAPE)
2613 			return (-ENOMEDIUM);
2614 		else
2615 			return (-EIO);
2616 	}
2617 
2618 	memset(cmd, 0, MAX_COMMAND_SIZE);
2619 	cmd[0] = START_STOP;
2620 	if (load_code)
2621 		cmd[4] |= 1;
2622 	/*
2623 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2624 	 */
2625 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2626 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2627 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2628 			    (cmd[4]) ? "" : "un",
2629 			    load_code - MT_ST_HPLOADER_OFFSET);
2630 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2631 	}
2632 	if (STp->immediate) {
2633 		cmd[1] = 1;	/* Don't wait for completion */
2634 		timeout = STp->device->request_queue->rq_timeout;
2635 	}
2636 	else
2637 		timeout = STp->long_timeout;
2638 
2639 	DEBC(
2640 		if (!load_code)
2641 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2642 		else
2643 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2644 		);
2645 
2646 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2647 			   timeout, MAX_RETRIES, 1);
2648 	if (!SRpnt)
2649 		return (STp->buffer)->syscall_result;
2650 
2651 	retval = (STp->buffer)->syscall_result;
2652 	st_release_request(SRpnt);
2653 
2654 	if (!retval) {	/* SCSI command successful */
2655 
2656 		if (!load_code) {
2657 			STp->rew_at_close = 0;
2658 			STp->ready = ST_NO_TAPE;
2659 		}
2660 		else {
2661 			STp->rew_at_close = STp->autorew_dev;
2662 			retval = check_tape(STp, filp);
2663 			if (retval > 0)
2664 				retval = 0;
2665 		}
2666 	}
2667 	else {
2668 		STps = &(STp->ps[STp->partition]);
2669 		STps->drv_file = STps->drv_block = (-1);
2670 	}
2671 
2672 	return retval;
2673 }
2674 
2675 #if DEBUG
2676 #define ST_DEB_FORWARD  0
2677 #define ST_DEB_BACKWARD 1
2678 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2679 {
2680 	s32 sc;
2681 
2682 	if (!debugging)
2683 		return;
2684 
2685 	sc = sign_extend32(get_unaligned_be24(&cmd[2]), 23);
2686 	if (direction)
2687 		sc = -sc;
2688 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2689 		  direction ? "backward" : "forward", sc, units);
2690 }
2691 #else
2692 #define ST_DEB_FORWARD  0
2693 #define ST_DEB_BACKWARD 1
2694 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2695 #endif
2696 
2697 
2698 /* Internal ioctl function */
2699 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2700 {
2701 	int timeout;
2702 	long ltmp;
2703 	int ioctl_result;
2704 	int chg_eof = 1;
2705 	unsigned char cmd[MAX_COMMAND_SIZE];
2706 	struct st_request *SRpnt;
2707 	struct st_partstat *STps;
2708 	int fileno, blkno, at_sm, undone;
2709 	int datalen = 0, direction = DMA_NONE;
2710 
2711 	WARN_ON(STp->buffer->do_dio != 0);
2712 	if (STp->ready != ST_READY) {
2713 		if (STp->ready == ST_NO_TAPE)
2714 			return (-ENOMEDIUM);
2715 		else
2716 			return (-EIO);
2717 	}
2718 	timeout = STp->long_timeout;
2719 	STps = &(STp->ps[STp->partition]);
2720 	fileno = STps->drv_file;
2721 	blkno = STps->drv_block;
2722 	at_sm = STps->at_sm;
2723 
2724 	memset(cmd, 0, MAX_COMMAND_SIZE);
2725 	switch (cmd_in) {
2726 	case MTFSFM:
2727 		chg_eof = 0;	/* Changed from the FSF after this */
2728 		fallthrough;
2729 	case MTFSF:
2730 		cmd[0] = SPACE;
2731 		cmd[1] = 0x01;	/* Space FileMarks */
2732 		cmd[2] = (arg >> 16);
2733 		cmd[3] = (arg >> 8);
2734 		cmd[4] = arg;
2735 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2736 		if (fileno >= 0)
2737 			fileno += arg;
2738 		blkno = 0;
2739 		at_sm &= (arg == 0);
2740 		break;
2741 	case MTBSFM:
2742 		chg_eof = 0;	/* Changed from the FSF after this */
2743 		fallthrough;
2744 	case MTBSF:
2745 		cmd[0] = SPACE;
2746 		cmd[1] = 0x01;	/* Space FileMarks */
2747 		ltmp = (-arg);
2748 		cmd[2] = (ltmp >> 16);
2749 		cmd[3] = (ltmp >> 8);
2750 		cmd[4] = ltmp;
2751 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2752 		if (fileno >= 0)
2753 			fileno -= arg;
2754 		blkno = (-1);	/* We can't know the block number */
2755 		at_sm &= (arg == 0);
2756 		break;
2757 	case MTFSR:
2758 		cmd[0] = SPACE;
2759 		cmd[1] = 0x00;	/* Space Blocks */
2760 		cmd[2] = (arg >> 16);
2761 		cmd[3] = (arg >> 8);
2762 		cmd[4] = arg;
2763 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2764 		if (blkno >= 0)
2765 			blkno += arg;
2766 		at_sm &= (arg == 0);
2767 		break;
2768 	case MTBSR:
2769 		cmd[0] = SPACE;
2770 		cmd[1] = 0x00;	/* Space Blocks */
2771 		ltmp = (-arg);
2772 		cmd[2] = (ltmp >> 16);
2773 		cmd[3] = (ltmp >> 8);
2774 		cmd[4] = ltmp;
2775 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2776 		if (blkno >= 0)
2777 			blkno -= arg;
2778 		at_sm &= (arg == 0);
2779 		break;
2780 	case MTFSS:
2781 		cmd[0] = SPACE;
2782 		cmd[1] = 0x04;	/* Space Setmarks */
2783 		cmd[2] = (arg >> 16);
2784 		cmd[3] = (arg >> 8);
2785 		cmd[4] = arg;
2786 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2787 		if (arg != 0) {
2788 			blkno = fileno = (-1);
2789 			at_sm = 1;
2790 		}
2791 		break;
2792 	case MTBSS:
2793 		cmd[0] = SPACE;
2794 		cmd[1] = 0x04;	/* Space Setmarks */
2795 		ltmp = (-arg);
2796 		cmd[2] = (ltmp >> 16);
2797 		cmd[3] = (ltmp >> 8);
2798 		cmd[4] = ltmp;
2799 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2800 		if (arg != 0) {
2801 			blkno = fileno = (-1);
2802 			at_sm = 1;
2803 		}
2804 		break;
2805 	case MTWEOF:
2806 	case MTWEOFI:
2807 	case MTWSM:
2808 		if (STp->write_prot)
2809 			return (-EACCES);
2810 		cmd[0] = WRITE_FILEMARKS;
2811 		if (cmd_in == MTWSM)
2812 			cmd[1] = 2;
2813 		if (cmd_in == MTWEOFI ||
2814 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2815 			cmd[1] |= 1;
2816 		cmd[2] = (arg >> 16);
2817 		cmd[3] = (arg >> 8);
2818 		cmd[4] = arg;
2819 		timeout = STp->device->request_queue->rq_timeout;
2820 		DEBC(
2821 			if (cmd_in != MTWSM)
2822 				st_printk(ST_DEB_MSG, STp,
2823 					  "Writing %d filemarks.\n",
2824 					  cmd[2] * 65536 +
2825 					  cmd[3] * 256 +
2826 					  cmd[4]);
2827 			else
2828 				st_printk(ST_DEB_MSG, STp,
2829 					  "Writing %d setmarks.\n",
2830 					  cmd[2] * 65536 +
2831 					  cmd[3] * 256 +
2832 					  cmd[4]);
2833 		)
2834 		if (fileno >= 0)
2835 			fileno += arg;
2836 		blkno = 0;
2837 		at_sm = (cmd_in == MTWSM);
2838 		break;
2839 	case MTREW:
2840 		cmd[0] = REZERO_UNIT;
2841 		if (STp->immediate) {
2842 			cmd[1] = 1;	/* Don't wait for completion */
2843 			timeout = STp->device->request_queue->rq_timeout;
2844 		}
2845 		DEBC_printk(STp, "Rewinding tape.\n");
2846 		fileno = blkno = at_sm = 0;
2847 		break;
2848 	case MTNOP:
2849 		DEBC_printk(STp, "No op on tape.\n");
2850 		return 0;	/* Should do something ? */
2851 	case MTRETEN:
2852 		cmd[0] = START_STOP;
2853 		if (STp->immediate) {
2854 			cmd[1] = 1;	/* Don't wait for completion */
2855 			timeout = STp->device->request_queue->rq_timeout;
2856 		}
2857 		cmd[4] = 3;
2858 		DEBC_printk(STp, "Retensioning tape.\n");
2859 		fileno = blkno = at_sm = 0;
2860 		break;
2861 	case MTEOM:
2862 		if (!STp->fast_mteom) {
2863 			/* space to the end of tape */
2864 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2865 			fileno = STps->drv_file;
2866 			if (STps->eof >= ST_EOD_1)
2867 				return 0;
2868 			/* The next lines would hide the number of spaced FileMarks
2869 			   That's why I inserted the previous lines. I had no luck
2870 			   with detecting EOM with FSF, so we go now to EOM.
2871 			   Joerg Weule */
2872 		} else
2873 			fileno = (-1);
2874 		cmd[0] = SPACE;
2875 		cmd[1] = 3;
2876 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2877 		blkno = -1;
2878 		at_sm = 0;
2879 		break;
2880 	case MTERASE:
2881 		if (STp->write_prot)
2882 			return (-EACCES);
2883 		cmd[0] = ERASE;
2884 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2885 		if (STp->immediate) {
2886 			cmd[1] |= 2;	/* Don't wait for completion */
2887 			timeout = STp->device->request_queue->rq_timeout;
2888 		}
2889 		else
2890 			timeout = STp->long_timeout * 8;
2891 
2892 		DEBC_printk(STp, "Erasing tape.\n");
2893 		fileno = blkno = at_sm = 0;
2894 		break;
2895 	case MTSETBLK:		/* Set block length */
2896 	case MTSETDENSITY:	/* Set tape density */
2897 	case MTSETDRVBUFFER:	/* Set drive buffering */
2898 	case SET_DENS_AND_BLK:	/* Set density and block size */
2899 		chg_eof = 0;
2900 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2901 			return (-EIO);	/* Not allowed if data in buffer */
2902 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2903 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2904 		    STp->max_block > 0 &&
2905 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2906 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2907 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2908 			return (-EINVAL);
2909 		}
2910 		cmd[0] = MODE_SELECT;
2911 		if ((STp->use_pf & USE_PF))
2912 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2913 		cmd[4] = datalen = 12;
2914 		direction = DMA_TO_DEVICE;
2915 
2916 		memset((STp->buffer)->b_data, 0, 12);
2917 		if (cmd_in == MTSETDRVBUFFER)
2918 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2919 		else
2920 			(STp->buffer)->b_data[2] =
2921 			    STp->drv_buffer << 4;
2922 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2923 		if (cmd_in == MTSETDENSITY) {
2924 			(STp->buffer)->b_data[4] = arg;
2925 			STp->density_changed = 1;	/* At least we tried ;-) */
2926 		} else if (cmd_in == SET_DENS_AND_BLK)
2927 			(STp->buffer)->b_data[4] = arg >> 24;
2928 		else
2929 			(STp->buffer)->b_data[4] = STp->density;
2930 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2931 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2932 			if (cmd_in == MTSETBLK)
2933 				STp->blksize_changed = 1; /* At least we tried ;-) */
2934 		} else
2935 			ltmp = STp->block_size;
2936 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2937 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2938 		(STp->buffer)->b_data[11] = ltmp;
2939 		timeout = STp->device->request_queue->rq_timeout;
2940 		DEBC(
2941 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2942 				st_printk(ST_DEB_MSG, STp,
2943 					  "Setting block size to %d bytes.\n",
2944 					  (STp->buffer)->b_data[9] * 65536 +
2945 					  (STp->buffer)->b_data[10] * 256 +
2946 					  (STp->buffer)->b_data[11]);
2947 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2948 				st_printk(ST_DEB_MSG, STp,
2949 					  "Setting density code to %x.\n",
2950 					  (STp->buffer)->b_data[4]);
2951 			if (cmd_in == MTSETDRVBUFFER)
2952 				st_printk(ST_DEB_MSG, STp,
2953 					  "Setting drive buffer code to %d.\n",
2954 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2955 		)
2956 		break;
2957 	default:
2958 		return (-ENOSYS);
2959 	}
2960 
2961 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2962 			   timeout, MAX_RETRIES, 1);
2963 	if (!SRpnt)
2964 		return (STp->buffer)->syscall_result;
2965 
2966 	ioctl_result = (STp->buffer)->syscall_result;
2967 
2968 	if (!ioctl_result) {	/* SCSI command successful */
2969 		st_release_request(SRpnt);
2970 		SRpnt = NULL;
2971 		STps->drv_block = blkno;
2972 		STps->drv_file = fileno;
2973 		STps->at_sm = at_sm;
2974 
2975 		if (cmd_in == MTBSFM)
2976 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2977 		else if (cmd_in == MTFSFM)
2978 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2979 
2980 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2981 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2982 			if (STp->block_size != 0) {
2983 				(STp->buffer)->buffer_blocks =
2984 				    (STp->buffer)->buffer_size / STp->block_size;
2985 			}
2986 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2987 			if (cmd_in == SET_DENS_AND_BLK)
2988 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2989 		} else if (cmd_in == MTSETDRVBUFFER)
2990 			STp->drv_buffer = (arg & 7);
2991 		else if (cmd_in == MTSETDENSITY)
2992 			STp->density = arg;
2993 
2994 		if (cmd_in == MTEOM)
2995 			STps->eof = ST_EOD;
2996 		else if (cmd_in == MTFSF)
2997 			STps->eof = ST_FM;
2998 		else if (chg_eof)
2999 			STps->eof = ST_NOEOF;
3000 
3001 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
3002 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
3003 	} else { /* SCSI command was not completely successful. Don't return
3004                     from this block without releasing the SCSI command block! */
3005 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
3006 
3007 		if (cmdstatp->flags & SENSE_EOM) {
3008 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3009 			    cmd_in != MTBSR && cmd_in != MTBSS)
3010 				STps->eof = ST_EOM_OK;
3011 			STps->drv_block = 0;
3012 		}
3013 
3014 		if (cmdstatp->remainder_valid)
3015 			undone = (int)cmdstatp->uremainder64;
3016 		else
3017 			undone = 0;
3018 
3019 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3020 		    cmdstatp->have_sense &&
3021 		    (cmdstatp->flags & SENSE_EOM)) {
3022 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3023 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3024 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3025 				STps->eof = ST_NOEOF;
3026 			} else {  /* Writing EOF(s) failed */
3027 				if (fileno >= 0)
3028 					fileno -= undone;
3029 				if (undone < arg)
3030 					STps->eof = ST_NOEOF;
3031 			}
3032 			STps->drv_file = fileno;
3033 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3034 			if (fileno >= 0)
3035 				STps->drv_file = fileno - undone;
3036 			else
3037 				STps->drv_file = fileno;
3038 			STps->drv_block = -1;
3039 			STps->eof = ST_NOEOF;
3040 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3041 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3042 				undone = (-undone);
3043 			if (STps->drv_file >= 0)
3044 				STps->drv_file = fileno + undone;
3045 			STps->drv_block = 0;
3046 			STps->eof = ST_NOEOF;
3047 		} else if (cmd_in == MTFSR) {
3048 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3049 				if (STps->drv_file >= 0)
3050 					STps->drv_file++;
3051 				STps->drv_block = 0;
3052 				STps->eof = ST_FM;
3053 			} else {
3054 				if (blkno >= undone)
3055 					STps->drv_block = blkno - undone;
3056 				else
3057 					STps->drv_block = (-1);
3058 				STps->eof = ST_NOEOF;
3059 			}
3060 		} else if (cmd_in == MTBSR) {
3061 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3062 				STps->drv_file--;
3063 				STps->drv_block = (-1);
3064 			} else {
3065 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3066 					undone = (-undone);
3067 				if (STps->drv_block >= 0)
3068 					STps->drv_block = blkno + undone;
3069 			}
3070 			STps->eof = ST_NOEOF;
3071 		} else if (cmd_in == MTEOM) {
3072 			STps->drv_file = (-1);
3073 			STps->drv_block = (-1);
3074 			STps->eof = ST_EOD;
3075 		} else if (cmd_in == MTSETBLK ||
3076 			   cmd_in == MTSETDENSITY ||
3077 			   cmd_in == MTSETDRVBUFFER ||
3078 			   cmd_in == SET_DENS_AND_BLK) {
3079 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3080 			    !(STp->use_pf & PF_TESTED)) {
3081 				/* Try the other possible state of Page Format if not
3082 				   already tried */
3083 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3084 				st_release_request(SRpnt);
3085 				SRpnt = NULL;
3086 				return st_int_ioctl(STp, cmd_in, arg);
3087 			}
3088 		} else if (chg_eof)
3089 			STps->eof = ST_NOEOF;
3090 
3091 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3092 			STps->eof = ST_EOD;
3093 
3094 		st_release_request(SRpnt);
3095 		SRpnt = NULL;
3096 	}
3097 
3098 	return ioctl_result;
3099 }
3100 
3101 
3102 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3103    structure. */
3104 
3105 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3106 			int logical)
3107 {
3108 	int result;
3109 	unsigned char scmd[MAX_COMMAND_SIZE];
3110 	struct st_request *SRpnt;
3111 
3112 	if (STp->ready != ST_READY)
3113 		return (-EIO);
3114 
3115 	memset(scmd, 0, MAX_COMMAND_SIZE);
3116 	if ((STp->device)->scsi_level < SCSI_2) {
3117 		scmd[0] = QFA_REQUEST_BLOCK;
3118 		scmd[4] = 3;
3119 	} else {
3120 		scmd[0] = READ_POSITION;
3121 		if (!logical && !STp->scsi2_logical)
3122 			scmd[1] = 1;
3123 	}
3124 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3125 			   STp->device->request_queue->rq_timeout,
3126 			   MAX_READY_RETRIES, 1);
3127 	if (!SRpnt)
3128 		return (STp->buffer)->syscall_result;
3129 
3130 	if ((STp->buffer)->syscall_result != 0 ||
3131 	    (STp->device->scsi_level >= SCSI_2 &&
3132 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3133 		*block = *partition = 0;
3134 		DEBC_printk(STp, " Can't read tape position.\n");
3135 		result = (-EIO);
3136 	} else {
3137 		result = 0;
3138 		if ((STp->device)->scsi_level < SCSI_2) {
3139 			*block = ((STp->buffer)->b_data[0] << 16)
3140 			    + ((STp->buffer)->b_data[1] << 8)
3141 			    + (STp->buffer)->b_data[2];
3142 			*partition = 0;
3143 		} else {
3144 			*block = ((STp->buffer)->b_data[4] << 24)
3145 			    + ((STp->buffer)->b_data[5] << 16)
3146 			    + ((STp->buffer)->b_data[6] << 8)
3147 			    + (STp->buffer)->b_data[7];
3148 			*partition = (STp->buffer)->b_data[1];
3149 			if (((STp->buffer)->b_data[0] & 0x80) &&
3150 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3151 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3152 		}
3153 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3154 			    *block, *partition);
3155 	}
3156 	st_release_request(SRpnt);
3157 	SRpnt = NULL;
3158 
3159 	return result;
3160 }
3161 
3162 
3163 /* Set the tape block and partition. Negative partition means that only the
3164    block should be set in vendor specific way. */
3165 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3166 			int logical)
3167 {
3168 	struct st_partstat *STps;
3169 	int result, p;
3170 	unsigned int blk;
3171 	int timeout;
3172 	unsigned char scmd[MAX_COMMAND_SIZE];
3173 	struct st_request *SRpnt;
3174 
3175 	if (STp->ready != ST_READY)
3176 		return (-EIO);
3177 	timeout = STp->long_timeout;
3178 	STps = &(STp->ps[STp->partition]);
3179 
3180 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3181 		    block, partition);
3182 	DEB(if (partition < 0)
3183 		return (-EIO); )
3184 
3185 	/* Update the location at the partition we are leaving */
3186 	if ((!STp->can_partitions && partition != 0) ||
3187 	    partition >= ST_NBR_PARTITIONS)
3188 		return (-EINVAL);
3189 	if (partition != STp->partition) {
3190 		if (get_location(STp, &blk, &p, 1))
3191 			STps->last_block_valid = 0;
3192 		else {
3193 			STps->last_block_valid = 1;
3194 			STps->last_block_visited = blk;
3195 			DEBC_printk(STp, "Visited block %d for "
3196 				    "partition %d saved.\n",
3197 				    blk, STp->partition);
3198 		}
3199 	}
3200 
3201 	memset(scmd, 0, MAX_COMMAND_SIZE);
3202 	if ((STp->device)->scsi_level < SCSI_2) {
3203 		scmd[0] = QFA_SEEK_BLOCK;
3204 		scmd[2] = (block >> 16);
3205 		scmd[3] = (block >> 8);
3206 		scmd[4] = block;
3207 		scmd[5] = 0;
3208 	} else {
3209 		scmd[0] = SEEK_10;
3210 		scmd[3] = (block >> 24);
3211 		scmd[4] = (block >> 16);
3212 		scmd[5] = (block >> 8);
3213 		scmd[6] = block;
3214 		if (!logical && !STp->scsi2_logical)
3215 			scmd[1] = 4;
3216 		if (STp->partition != partition) {
3217 			scmd[1] |= 2;
3218 			scmd[8] = partition;
3219 			DEBC_printk(STp, "Trying to change partition "
3220 				    "from %d to %d\n", STp->partition,
3221 				    partition);
3222 		}
3223 	}
3224 	if (STp->immediate) {
3225 		scmd[1] |= 1;		/* Don't wait for completion */
3226 		timeout = STp->device->request_queue->rq_timeout;
3227 	}
3228 
3229 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3230 			   timeout, MAX_READY_RETRIES, 1);
3231 	if (!SRpnt)
3232 		return (STp->buffer)->syscall_result;
3233 
3234 	STps->drv_block = STps->drv_file = (-1);
3235 	STps->eof = ST_NOEOF;
3236 	if ((STp->buffer)->syscall_result != 0) {
3237 		result = (-EIO);
3238 		if (STp->can_partitions &&
3239 		    (STp->device)->scsi_level >= SCSI_2 &&
3240 		    (p = find_partition(STp)) >= 0)
3241 			STp->partition = p;
3242 	} else {
3243 		if (STp->can_partitions) {
3244 			STp->partition = partition;
3245 			STps = &(STp->ps[partition]);
3246 			if (!STps->last_block_valid ||
3247 			    STps->last_block_visited != block) {
3248 				STps->at_sm = 0;
3249 				STps->rw = ST_IDLE;
3250 			}
3251 		} else
3252 			STps->at_sm = 0;
3253 		if (block == 0)
3254 			STps->drv_block = STps->drv_file = 0;
3255 		result = 0;
3256 	}
3257 
3258 	st_release_request(SRpnt);
3259 	SRpnt = NULL;
3260 
3261 	return result;
3262 }
3263 
3264 
3265 /* Find the current partition number for the drive status. Called from open and
3266    returns either partition number of negative error code. */
3267 static int find_partition(struct scsi_tape *STp)
3268 {
3269 	int i, partition;
3270 	unsigned int block;
3271 
3272 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3273 		return i;
3274 	if (partition >= ST_NBR_PARTITIONS)
3275 		return (-EIO);
3276 	return partition;
3277 }
3278 
3279 
3280 /* Change the partition if necessary */
3281 static int switch_partition(struct scsi_tape *STp)
3282 {
3283 	struct st_partstat *STps;
3284 
3285 	if (STp->partition == STp->new_partition)
3286 		return 0;
3287 	STps = &(STp->ps[STp->new_partition]);
3288 	if (!STps->last_block_valid)
3289 		STps->last_block_visited = 0;
3290 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3291 }
3292 
3293 /* Functions for reading and writing the medium partition mode page. */
3294 
3295 #define PART_PAGE   0x11
3296 #define PART_PAGE_FIXED_LENGTH 8
3297 
3298 #define PP_OFF_MAX_ADD_PARTS   2
3299 #define PP_OFF_NBR_ADD_PARTS   3
3300 #define PP_OFF_FLAGS           4
3301 #define PP_OFF_PART_UNITS      6
3302 #define PP_OFF_RESERVED        7
3303 
3304 #define PP_BIT_IDP             0x20
3305 #define PP_BIT_FDP             0x80
3306 #define PP_MSK_PSUM_MB         0x10
3307 #define PP_MSK_PSUM_UNITS      0x18
3308 #define PP_MSK_POFM            0x04
3309 
3310 /* Get the number of partitions on the tape. As a side effect reads the
3311    mode page into the tape buffer. */
3312 static int nbr_partitions(struct scsi_tape *STp)
3313 {
3314 	int result;
3315 
3316 	if (STp->ready != ST_READY)
3317 		return (-EIO);
3318 
3319 	result = read_mode_page(STp, PART_PAGE, 1);
3320 
3321 	if (result) {
3322 		DEBC_printk(STp, "Can't read medium partition page.\n");
3323 		result = (-EIO);
3324 	} else {
3325 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3326 					      PP_OFF_NBR_ADD_PARTS] + 1;
3327 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3328 	}
3329 
3330 	return result;
3331 }
3332 
3333 
3334 static int format_medium(struct scsi_tape *STp, int format)
3335 {
3336 	int result = 0;
3337 	int timeout = STp->long_timeout;
3338 	unsigned char scmd[MAX_COMMAND_SIZE];
3339 	struct st_request *SRpnt;
3340 
3341 	memset(scmd, 0, MAX_COMMAND_SIZE);
3342 	scmd[0] = FORMAT_UNIT;
3343 	scmd[2] = format;
3344 	if (STp->immediate) {
3345 		scmd[1] |= 1;		/* Don't wait for completion */
3346 		timeout = STp->device->request_queue->rq_timeout;
3347 	}
3348 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3349 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3350 			   timeout, MAX_RETRIES, 1);
3351 	if (!SRpnt)
3352 		result = STp->buffer->syscall_result;
3353 	return result;
3354 }
3355 
3356 
3357 /* Partition the tape into two partitions if size > 0 or one partition if
3358    size == 0.
3359 
3360    The block descriptors are read and written because Sony SDT-7000 does not
3361    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3362 
3363    My HP C1533A drive returns only one partition size field. This is used to
3364    set the size of partition 1. There is no size field for the default partition.
3365    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3366    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3367    The following algorithm is used to accommodate both drives: if the number of
3368    partition size fields is greater than the maximum number of additional partitions
3369    in the mode page, the second field is used. Otherwise the first field is used.
3370 
3371    For Seagate DDS drives the page length must be 8 when no partitions is defined
3372    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3373    is acceptable also to some other old drives and enforced if the first partition
3374    size field is used for the first additional partition size.
3375 
3376    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3377  */
3378 static int partition_tape(struct scsi_tape *STp, int size)
3379 {
3380 	int result;
3381 	int target_partition;
3382 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3383 	int pgo, psd_cnt, psdo;
3384 	int psum = PP_MSK_PSUM_MB, units = 0;
3385 	unsigned char *bp;
3386 
3387 	result = read_mode_page(STp, PART_PAGE, 0);
3388 	if (result) {
3389 		DEBC_printk(STp, "Can't read partition mode page.\n");
3390 		return result;
3391 	}
3392 	target_partition = 1;
3393 	if (size < 0) {
3394 		target_partition = 0;
3395 		size = -size;
3396 	}
3397 
3398 	/* The mode page is in the buffer. Let's modify it and write it. */
3399 	bp = (STp->buffer)->b_data;
3400 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3401 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3402 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3403 
3404 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3405 
3406 	if (scsi3) {
3407 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3408 		if (needs_format && size == 0) {
3409 			/* No need to write the mode page when clearing
3410 			 *  partitioning
3411 			 */
3412 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3413 			result = format_medium(STp, 0);
3414 			goto out;
3415 		}
3416 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3417 			psd_cnt = 2;
3418 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3419 			/* Use units scaling for large partitions if the device
3420 			 * suggests it and no precision lost. Required for IBM
3421 			 * TS1140/50 drives that don't support MB units.
3422 			 */
3423 			if (size >= 1000 && (size % 1000) == 0) {
3424 				size /= 1000;
3425 				psum = PP_MSK_PSUM_UNITS;
3426 				units = 9; /* GB */
3427 			}
3428 		}
3429 		/* Try it anyway if too large to specify in MB */
3430 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3431 			size /= 1000;
3432 			psum = PP_MSK_PSUM_UNITS;
3433 			units = 9;  /* GB */
3434 		}
3435 	}
3436 
3437 	if (size >= 65535 ||  /* Does not fit into two bytes */
3438 	    (target_partition == 0 && psd_cnt < 2)) {
3439 		result = -EINVAL;
3440 		goto out;
3441 	}
3442 
3443 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3444 	/* The second condition is for HP DDS which use only one partition size
3445 	 * descriptor
3446 	 */
3447 	if (target_partition > 0 &&
3448 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3449 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3450 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3451 		psdo += 2;
3452 	}
3453 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3454 
3455 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3456 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3457 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3458 
3459 	if (size == 0) {
3460 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3461 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3462 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3463 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3464 	} else {
3465 		bp[psdo] = (size >> 8) & 0xff;
3466 		bp[psdo + 1] = size & 0xff;
3467 		if (target_partition == 0)
3468 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3469 		bp[pgo + 3] = 1;
3470 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3471 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3472 		DEBC_printk(STp,
3473 			    "Formatting tape with two partitions (%i = %d MB).\n",
3474 			    target_partition, units > 0 ? size * 1000 : size);
3475 	}
3476 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3477 	bp[pgo + PP_OFF_RESERVED] = 0;
3478 	if (size != 1 || units != 0) {
3479 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3480 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3481 		bp[pgo + PP_OFF_PART_UNITS] = units;
3482 	} else
3483 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3484 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3485 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3486 
3487 	result = write_mode_page(STp, PART_PAGE, 1);
3488 
3489 	if (!result && needs_format)
3490 		result = format_medium(STp, 1);
3491 
3492 	if (result) {
3493 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3494 		result = (-EIO);
3495 	}
3496 
3497 out:
3498 	return result;
3499 }
3500 
3501 
3502 
3503 /* The ioctl command */
3504 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3505 {
3506 	void __user *p = (void __user *)arg;
3507 	int i, cmd_nr, cmd_type, bt;
3508 	int retval = 0;
3509 	unsigned int blk;
3510 	struct scsi_tape *STp = file->private_data;
3511 	struct st_modedef *STm;
3512 	struct st_partstat *STps;
3513 
3514 	if (mutex_lock_interruptible(&STp->lock))
3515 		return -ERESTARTSYS;
3516 
3517 	DEB(
3518 	if (debugging && !STp->in_use) {
3519 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3520 		retval = (-EIO);
3521 		goto out;
3522 	} ) /* end DEB */
3523 
3524 	STm = &(STp->modes[STp->current_mode]);
3525 	STps = &(STp->ps[STp->partition]);
3526 
3527 	/*
3528 	 * If we are in the middle of error recovery, don't let anyone
3529 	 * else try and use this device.  Also, if error recovery fails, it
3530 	 * may try and take the device offline, in which case all further
3531 	 * access to the device is prohibited.
3532 	 */
3533 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3534 			file->f_flags & O_NDELAY);
3535 	if (retval)
3536 		goto out;
3537 
3538 	cmd_type = _IOC_TYPE(cmd_in);
3539 	cmd_nr = _IOC_NR(cmd_in);
3540 
3541 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3542 		struct mtop mtc;
3543 
3544 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3545 			retval = (-EINVAL);
3546 			goto out;
3547 		}
3548 
3549 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3550 		if (i) {
3551 			retval = (-EFAULT);
3552 			goto out;
3553 		}
3554 
3555 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3556 			st_printk(KERN_WARNING, STp,
3557 				  "MTSETDRVBUFFER only allowed for root.\n");
3558 			retval = (-EPERM);
3559 			goto out;
3560 		}
3561 		if (!STm->defined &&
3562 		    (mtc.mt_op != MTSETDRVBUFFER &&
3563 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3564 			retval = (-ENXIO);
3565 			goto out;
3566 		}
3567 
3568 		if (!STp->pos_unknown) {
3569 
3570 			if (STps->eof == ST_FM_HIT) {
3571 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3572                                     mtc.mt_op == MTEOM) {
3573 					mtc.mt_count -= 1;
3574 					if (STps->drv_file >= 0)
3575 						STps->drv_file += 1;
3576 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3577 					mtc.mt_count += 1;
3578 					if (STps->drv_file >= 0)
3579 						STps->drv_file += 1;
3580 				}
3581 			}
3582 
3583 			if (mtc.mt_op == MTSEEK) {
3584 				/* Old position must be restored if partition will be
3585                                    changed */
3586 				i = !STp->can_partitions ||
3587 				    (STp->new_partition != STp->partition);
3588 			} else {
3589 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3590 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3591 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3592 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3593 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3594 				    mtc.mt_op == MTCOMPRESSION;
3595 			}
3596 			i = flush_buffer(STp, i);
3597 			if (i < 0) {
3598 				retval = i;
3599 				goto out;
3600 			}
3601 			if (STps->rw == ST_WRITING &&
3602 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3603 			     mtc.mt_op == MTSEEK ||
3604 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3605 				i = st_int_ioctl(STp, MTWEOF, 1);
3606 				if (i < 0) {
3607 					retval = i;
3608 					goto out;
3609 				}
3610 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3611 					mtc.mt_count++;
3612 				STps->rw = ST_IDLE;
3613 			     }
3614 
3615 		} else {
3616 			/*
3617 			 * If there was a bus reset, block further access
3618 			 * to this device.  If the user wants to rewind the tape,
3619 			 * then reset the flag and allow access again.
3620 			 */
3621 			if (mtc.mt_op != MTREW &&
3622 			    mtc.mt_op != MTOFFL &&
3623 			    mtc.mt_op != MTRETEN &&
3624 			    mtc.mt_op != MTERASE &&
3625 			    mtc.mt_op != MTSEEK &&
3626 			    mtc.mt_op != MTEOM) {
3627 				retval = (-EIO);
3628 				goto out;
3629 			}
3630 			reset_state(STp);
3631 			/* remove this when the midlevel properly clears was_reset */
3632 			STp->device->was_reset = 0;
3633 		}
3634 
3635 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3636 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3637 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3638 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3639 
3640 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3641 			do_door_lock(STp, 0);	/* Ignore result! */
3642 
3643 		if (mtc.mt_op == MTSETDRVBUFFER &&
3644 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3645 			retval = st_set_options(STp, mtc.mt_count);
3646 			goto out;
3647 		}
3648 
3649 		if (mtc.mt_op == MTSETPART) {
3650 			if (!STp->can_partitions ||
3651 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3652 				retval = (-EINVAL);
3653 				goto out;
3654 			}
3655 			if (mtc.mt_count >= STp->nbr_partitions &&
3656 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3657 				retval = (-EIO);
3658 				goto out;
3659 			}
3660 			if (mtc.mt_count >= STp->nbr_partitions) {
3661 				retval = (-EINVAL);
3662 				goto out;
3663 			}
3664 			STp->new_partition = mtc.mt_count;
3665 			retval = 0;
3666 			goto out;
3667 		}
3668 
3669 		if (mtc.mt_op == MTMKPART) {
3670 			if (!STp->can_partitions) {
3671 				retval = (-EINVAL);
3672 				goto out;
3673 			}
3674 			i = do_load_unload(STp, file, 1);
3675 			if (i < 0) {
3676 				retval = i;
3677 				goto out;
3678 			}
3679 			i = partition_tape(STp, mtc.mt_count);
3680 			if (i < 0) {
3681 				retval = i;
3682 				goto out;
3683 			}
3684 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3685 				STp->ps[i].rw = ST_IDLE;
3686 				STp->ps[i].at_sm = 0;
3687 				STp->ps[i].last_block_valid = 0;
3688 			}
3689 			STp->partition = STp->new_partition = 0;
3690 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3691 			STps->drv_block = STps->drv_file = 0;
3692 			retval = 0;
3693 			goto out;
3694 		}
3695 
3696 		if (mtc.mt_op == MTSEEK) {
3697 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3698 			if (!STp->can_partitions)
3699 				STp->ps[0].rw = ST_IDLE;
3700 			retval = i;
3701 			goto out;
3702 		}
3703 
3704 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3705 			retval = do_load_unload(STp, file, 0);
3706 			goto out;
3707 		}
3708 
3709 		if (mtc.mt_op == MTLOAD) {
3710 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3711 			goto out;
3712 		}
3713 
3714 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3715 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3716 			goto out;
3717 		}
3718 
3719 		if (STp->can_partitions && STp->ready == ST_READY &&
3720 		    (i = switch_partition(STp)) < 0) {
3721 			retval = i;
3722 			goto out;
3723 		}
3724 
3725 		if (mtc.mt_op == MTCOMPRESSION)
3726 			retval = st_compression(STp, (mtc.mt_count & 1));
3727 		else
3728 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3729 		goto out;
3730 	}
3731 	if (!STm->defined) {
3732 		retval = (-ENXIO);
3733 		goto out;
3734 	}
3735 
3736 	if ((i = flush_buffer(STp, 0)) < 0) {
3737 		retval = i;
3738 		goto out;
3739 	}
3740 	if (STp->can_partitions &&
3741 	    (i = switch_partition(STp)) < 0) {
3742 		retval = i;
3743 		goto out;
3744 	}
3745 
3746 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3747 		struct mtget mt_status;
3748 
3749 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3750 			 retval = (-EINVAL);
3751 			 goto out;
3752 		}
3753 
3754 		mt_status.mt_type = STp->tape_type;
3755 		mt_status.mt_dsreg =
3756 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3757 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3758 		mt_status.mt_blkno = STps->drv_block;
3759 		mt_status.mt_fileno = STps->drv_file;
3760 		if (STp->block_size != 0) {
3761 			if (STps->rw == ST_WRITING)
3762 				mt_status.mt_blkno +=
3763 				    (STp->buffer)->buffer_bytes / STp->block_size;
3764 			else if (STps->rw == ST_READING)
3765 				mt_status.mt_blkno -=
3766                                         ((STp->buffer)->buffer_bytes +
3767                                          STp->block_size - 1) / STp->block_size;
3768 		}
3769 
3770 		mt_status.mt_gstat = 0;
3771 		if (STp->drv_write_prot)
3772 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3773 		if (mt_status.mt_blkno == 0) {
3774 			if (mt_status.mt_fileno == 0)
3775 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3776 			else
3777 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3778 		}
3779 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3780 		mt_status.mt_resid = STp->partition;
3781 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3782 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3783 		else if (STps->eof >= ST_EOM_OK)
3784 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3785 		if (STp->density == 1)
3786 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3787 		else if (STp->density == 2)
3788 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3789 		else if (STp->density == 3)
3790 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3791 		if (STp->ready == ST_READY)
3792 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3793 		if (STp->ready == ST_NO_TAPE)
3794 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3795 		if (STps->at_sm)
3796 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3797 		if (STm->do_async_writes ||
3798                     (STm->do_buffer_writes && STp->block_size != 0) ||
3799 		    STp->drv_buffer != 0)
3800 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3801 		if (STp->cleaning_req)
3802 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3803 
3804 		retval = put_user_mtget(p, &mt_status);
3805 		if (retval)
3806 			goto out;
3807 
3808 		STp->recover_reg = 0;		/* Clear after read */
3809 		goto out;
3810 	}			/* End of MTIOCGET */
3811 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3812 		struct mtpos mt_pos;
3813 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3814 			 retval = (-EINVAL);
3815 			 goto out;
3816 		}
3817 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3818 			retval = i;
3819 			goto out;
3820 		}
3821 		mt_pos.mt_blkno = blk;
3822 		retval = put_user_mtpos(p, &mt_pos);
3823 		goto out;
3824 	}
3825 	mutex_unlock(&STp->lock);
3826 
3827 	switch (cmd_in) {
3828 	case SG_IO:
3829 	case SCSI_IOCTL_SEND_COMMAND:
3830 	case CDROM_SEND_PACKET:
3831 		if (!capable(CAP_SYS_RAWIO))
3832 			return -EPERM;
3833 		break;
3834 	default:
3835 		break;
3836 	}
3837 
3838 	retval = scsi_ioctl(STp->device, file->f_mode & FMODE_WRITE, cmd_in, p);
3839 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) {
3840 		/* unload */
3841 		STp->rew_at_close = 0;
3842 		STp->ready = ST_NO_TAPE;
3843 	}
3844 	return retval;
3845 
3846  out:
3847 	mutex_unlock(&STp->lock);
3848 	return retval;
3849 }
3850 
3851 #ifdef CONFIG_COMPAT
3852 static long st_compat_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3853 {
3854 	/* argument conversion is handled using put_user_mtpos/put_user_mtget */
3855 	switch (cmd_in) {
3856 	case MTIOCPOS32:
3857 		cmd_in = MTIOCPOS;
3858 		break;
3859 	case MTIOCGET32:
3860 		cmd_in = MTIOCGET;
3861 		break;
3862 	}
3863 
3864 	return st_ioctl(file, cmd_in, arg);
3865 }
3866 #endif
3867 
3868 
3869 
3870 /* Try to allocate a new tape buffer. Calling function must not hold
3871    dev_arr_lock. */
3872 static struct st_buffer *new_tape_buffer(int max_sg)
3873 {
3874 	struct st_buffer *tb;
3875 
3876 	tb = kzalloc(sizeof(struct st_buffer), GFP_KERNEL);
3877 	if (!tb) {
3878 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3879 		return NULL;
3880 	}
3881 	tb->frp_segs = 0;
3882 	tb->use_sg = max_sg;
3883 	tb->buffer_size = 0;
3884 
3885 	tb->reserved_pages = kcalloc(max_sg, sizeof(struct page *),
3886 				     GFP_KERNEL);
3887 	if (!tb->reserved_pages) {
3888 		kfree(tb);
3889 		return NULL;
3890 	}
3891 
3892 	return tb;
3893 }
3894 
3895 
3896 /* Try to allocate enough space in the tape buffer */
3897 #define ST_MAX_ORDER 6
3898 
3899 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size)
3900 {
3901 	int segs, max_segs, b_size, order, got;
3902 	gfp_t priority;
3903 
3904 	if (new_size <= STbuffer->buffer_size)
3905 		return 1;
3906 
3907 	if (STbuffer->buffer_size <= PAGE_SIZE)
3908 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3909 
3910 	max_segs = STbuffer->use_sg;
3911 
3912 	priority = GFP_KERNEL | __GFP_NOWARN;
3913 
3914 	if (STbuffer->cleared)
3915 		priority |= __GFP_ZERO;
3916 
3917 	if (STbuffer->frp_segs) {
3918 		order = STbuffer->reserved_page_order;
3919 		b_size = PAGE_SIZE << order;
3920 	} else {
3921 		for (b_size = PAGE_SIZE, order = 0;
3922 		     order < ST_MAX_ORDER &&
3923 			     max_segs * (PAGE_SIZE << order) < new_size;
3924 		     order++, b_size *= 2)
3925 			;  /* empty */
3926 		STbuffer->reserved_page_order = order;
3927 	}
3928 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3929 		if (order == ST_MAX_ORDER)
3930 			return 0;
3931 		normalize_buffer(STbuffer);
3932 		return enlarge_buffer(STbuffer, new_size);
3933 	}
3934 
3935 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3936 	     segs < max_segs && got < new_size;) {
3937 		struct page *page;
3938 
3939 		page = alloc_pages(priority, order);
3940 		if (!page) {
3941 			DEB(STbuffer->buffer_size = got);
3942 			normalize_buffer(STbuffer);
3943 			return 0;
3944 		}
3945 
3946 		STbuffer->frp_segs += 1;
3947 		got += b_size;
3948 		STbuffer->buffer_size = got;
3949 		STbuffer->reserved_pages[segs] = page;
3950 		segs++;
3951 	}
3952 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3953 
3954 	return 1;
3955 }
3956 
3957 
3958 /* Make sure that no data from previous user is in the internal buffer */
3959 static void clear_buffer(struct st_buffer * st_bp)
3960 {
3961 	int i;
3962 
3963 	for (i=0; i < st_bp->frp_segs; i++)
3964 		memset(page_address(st_bp->reserved_pages[i]), 0,
3965 		       PAGE_SIZE << st_bp->reserved_page_order);
3966 	st_bp->cleared = 1;
3967 }
3968 
3969 
3970 /* Release the extra buffer */
3971 static void normalize_buffer(struct st_buffer * STbuffer)
3972 {
3973 	int i, order = STbuffer->reserved_page_order;
3974 
3975 	for (i = 0; i < STbuffer->frp_segs; i++) {
3976 		__free_pages(STbuffer->reserved_pages[i], order);
3977 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3978 	}
3979 	STbuffer->frp_segs = 0;
3980 	STbuffer->sg_segs = 0;
3981 	STbuffer->reserved_page_order = 0;
3982 	STbuffer->map_data.offset = 0;
3983 }
3984 
3985 
3986 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3987    negative error code. */
3988 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3989 {
3990 	int i, cnt, res, offset;
3991 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3992 
3993 	for (i = 0, offset = st_bp->buffer_bytes;
3994 	     i < st_bp->frp_segs && offset >= length; i++)
3995 		offset -= length;
3996 	if (i == st_bp->frp_segs) {	/* Should never happen */
3997 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
3998 		return (-EIO);
3999 	}
4000 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4001 		struct page *page = st_bp->reserved_pages[i];
4002 		cnt = length - offset < do_count ? length - offset : do_count;
4003 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4004 		if (res)
4005 			return (-EFAULT);
4006 		do_count -= cnt;
4007 		st_bp->buffer_bytes += cnt;
4008 		ubp += cnt;
4009 		offset = 0;
4010 	}
4011 	if (do_count) /* Should never happen */
4012 		return (-EIO);
4013 
4014 	return 0;
4015 }
4016 
4017 
4018 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4019    negative error code. */
4020 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4021 {
4022 	int i, cnt, res, offset;
4023 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4024 
4025 	for (i = 0, offset = st_bp->read_pointer;
4026 	     i < st_bp->frp_segs && offset >= length; i++)
4027 		offset -= length;
4028 	if (i == st_bp->frp_segs) {	/* Should never happen */
4029 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4030 		return (-EIO);
4031 	}
4032 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4033 		struct page *page = st_bp->reserved_pages[i];
4034 		cnt = length - offset < do_count ? length - offset : do_count;
4035 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4036 		if (res)
4037 			return (-EFAULT);
4038 		do_count -= cnt;
4039 		st_bp->buffer_bytes -= cnt;
4040 		st_bp->read_pointer += cnt;
4041 		ubp += cnt;
4042 		offset = 0;
4043 	}
4044 	if (do_count) /* Should never happen */
4045 		return (-EIO);
4046 
4047 	return 0;
4048 }
4049 
4050 
4051 /* Move data towards start of buffer */
4052 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4053 {
4054 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4055 	int count, total;
4056 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4057 
4058 	if (offset == 0)
4059 		return;
4060 
4061 	total=st_bp->buffer_bytes - offset;
4062 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4063 		src_offset = offset;
4064 		if (src_offset < length)
4065 			break;
4066 		offset -= length;
4067 	}
4068 
4069 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4070 	for (dst_seg=dst_offset=0; total > 0; ) {
4071 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4072 		struct page *spage = st_bp->reserved_pages[src_seg];
4073 
4074 		count = min(length - dst_offset, length - src_offset);
4075 		memmove(page_address(dpage) + dst_offset,
4076 			page_address(spage) + src_offset, count);
4077 		src_offset += count;
4078 		if (src_offset >= length) {
4079 			src_seg++;
4080 			src_offset = 0;
4081 		}
4082 		dst_offset += count;
4083 		if (dst_offset >= length) {
4084 			dst_seg++;
4085 			dst_offset = 0;
4086 		}
4087 		total -= count;
4088 	}
4089 }
4090 
4091 /* Validate the options from command line or module parameters */
4092 static void validate_options(void)
4093 {
4094 	if (buffer_kbs > 0)
4095 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4096 	if (max_sg_segs >= ST_FIRST_SG)
4097 		st_max_sg_segs = max_sg_segs;
4098 }
4099 
4100 #ifndef MODULE
4101 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4102  */
4103 static int __init st_setup(char *str)
4104 {
4105 	int i, len, ints[5];
4106 	char *stp;
4107 
4108 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4109 
4110 	if (ints[0] > 0) {
4111 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4112 			if (parms[i].val)
4113 				*parms[i].val = ints[i + 1];
4114 	} else {
4115 		while (stp != NULL) {
4116 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4117 				len = strlen(parms[i].name);
4118 				if (!strncmp(stp, parms[i].name, len) &&
4119 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4120 					if (parms[i].val)
4121 						*parms[i].val =
4122 							simple_strtoul(stp + len + 1, NULL, 0);
4123 					else
4124 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4125 						       parms[i].name);
4126 					break;
4127 				}
4128 			}
4129 			if (i >= ARRAY_SIZE(parms))
4130 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4131 					stp);
4132 			stp = strchr(stp, ',');
4133 			if (stp)
4134 				stp++;
4135 		}
4136 	}
4137 
4138 	validate_options();
4139 
4140 	return 1;
4141 }
4142 
4143 __setup("st=", st_setup);
4144 
4145 #endif
4146 
4147 static const struct file_operations st_fops =
4148 {
4149 	.owner =	THIS_MODULE,
4150 	.read =		st_read,
4151 	.write =	st_write,
4152 	.unlocked_ioctl = st_ioctl,
4153 #ifdef CONFIG_COMPAT
4154 	.compat_ioctl = st_compat_ioctl,
4155 #endif
4156 	.open =		st_open,
4157 	.flush =	st_flush,
4158 	.release =	st_release,
4159 	.llseek =	noop_llseek,
4160 };
4161 
4162 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4163 {
4164 	int i, error;
4165 	dev_t cdev_devno;
4166 	struct cdev *cdev;
4167 	struct device *dev;
4168 	struct st_modedef *STm = &(tape->modes[mode]);
4169 	char name[10];
4170 	int dev_num = tape->index;
4171 
4172 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4173 
4174 	cdev = cdev_alloc();
4175 	if (!cdev) {
4176 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4177 		error = -ENOMEM;
4178 		goto out;
4179 	}
4180 	cdev->owner = THIS_MODULE;
4181 	cdev->ops = &st_fops;
4182 	STm->cdevs[rew] = cdev;
4183 
4184 	error = cdev_add(cdev, cdev_devno, 1);
4185 	if (error) {
4186 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4187 		       rew ? "non" : "auto", mode);
4188 		pr_err("st%d: Device not attached.\n", dev_num);
4189 		goto out_free;
4190 	}
4191 
4192 	i = mode << (4 - ST_NBR_MODE_BITS);
4193 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4194 		 tape->name, st_formats[i]);
4195 
4196 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4197 			    cdev_devno, &tape->modes[mode], "%s", name);
4198 	if (IS_ERR(dev)) {
4199 		pr_err("st%d: device_create failed\n", dev_num);
4200 		error = PTR_ERR(dev);
4201 		goto out_free;
4202 	}
4203 
4204 	STm->devs[rew] = dev;
4205 
4206 	return 0;
4207 out_free:
4208 	cdev_del(STm->cdevs[rew]);
4209 out:
4210 	STm->cdevs[rew] = NULL;
4211 	STm->devs[rew] = NULL;
4212 	return error;
4213 }
4214 
4215 static int create_cdevs(struct scsi_tape *tape)
4216 {
4217 	int mode, error;
4218 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4219 		error = create_one_cdev(tape, mode, 0);
4220 		if (error)
4221 			return error;
4222 		error = create_one_cdev(tape, mode, 1);
4223 		if (error)
4224 			return error;
4225 	}
4226 
4227 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4228 				 &tape->modes[0].devs[0]->kobj, "tape");
4229 }
4230 
4231 static void remove_cdevs(struct scsi_tape *tape)
4232 {
4233 	int mode, rew;
4234 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4235 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4236 		struct st_modedef *STm = &(tape->modes[mode]);
4237 		for (rew = 0; rew < 2; rew++) {
4238 			if (STm->cdevs[rew])
4239 				cdev_del(STm->cdevs[rew]);
4240 			if (STm->devs[rew])
4241 				device_unregister(STm->devs[rew]);
4242 		}
4243 	}
4244 }
4245 
4246 static int st_probe(struct device *dev)
4247 {
4248 	struct scsi_device *SDp = to_scsi_device(dev);
4249 	struct scsi_tape *tpnt = NULL;
4250 	struct st_modedef *STm;
4251 	struct st_partstat *STps;
4252 	struct st_buffer *buffer;
4253 	int i, error;
4254 
4255 	if (SDp->type != TYPE_TAPE)
4256 		return -ENODEV;
4257 	if (st_incompatible(SDp)) {
4258 		sdev_printk(KERN_INFO, SDp,
4259 			    "OnStream tapes are no longer supported;\n");
4260 		sdev_printk(KERN_INFO, SDp,
4261 			    "please mail to linux-scsi@vger.kernel.org.\n");
4262 		return -ENODEV;
4263 	}
4264 
4265 	scsi_autopm_get_device(SDp);
4266 	i = queue_max_segments(SDp->request_queue);
4267 	if (st_max_sg_segs < i)
4268 		i = st_max_sg_segs;
4269 	buffer = new_tape_buffer(i);
4270 	if (buffer == NULL) {
4271 		sdev_printk(KERN_ERR, SDp,
4272 			    "st: Can't allocate new tape buffer. "
4273 			    "Device not attached.\n");
4274 		goto out;
4275 	}
4276 
4277 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
4278 	if (tpnt == NULL) {
4279 		sdev_printk(KERN_ERR, SDp,
4280 			    "st: Can't allocate device descriptor.\n");
4281 		goto out_buffer_free;
4282 	}
4283 	kref_init(&tpnt->kref);
4284 
4285 	tpnt->device = SDp;
4286 	if (SDp->scsi_level <= 2)
4287 		tpnt->tape_type = MT_ISSCSI1;
4288 	else
4289 		tpnt->tape_type = MT_ISSCSI2;
4290 
4291 	tpnt->buffer = buffer;
4292 	tpnt->buffer->last_SRpnt = NULL;
4293 
4294 	tpnt->inited = 0;
4295 	tpnt->dirty = 0;
4296 	tpnt->in_use = 0;
4297 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4298 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4299 	tpnt->density = 0;
4300 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4301 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4302 	tpnt->can_partitions = 0;
4303 	tpnt->two_fm = ST_TWO_FM;
4304 	tpnt->fast_mteom = ST_FAST_MTEOM;
4305 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4306 	tpnt->sili = ST_SILI;
4307 	tpnt->immediate = ST_NOWAIT;
4308 	tpnt->immediate_filemark = 0;
4309 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4310 	tpnt->partition = 0;
4311 	tpnt->new_partition = 0;
4312 	tpnt->nbr_partitions = 0;
4313 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4314 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4315 	tpnt->try_dio = try_direct_io;
4316 
4317 	for (i = 0; i < ST_NBR_MODES; i++) {
4318 		STm = &(tpnt->modes[i]);
4319 		STm->defined = 0;
4320 		STm->sysv = ST_SYSV;
4321 		STm->defaults_for_writes = 0;
4322 		STm->do_async_writes = ST_ASYNC_WRITES;
4323 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4324 		STm->do_read_ahead = ST_READ_AHEAD;
4325 		STm->default_compression = ST_DONT_TOUCH;
4326 		STm->default_blksize = (-1);	/* No forced size */
4327 		STm->default_density = (-1);	/* No forced density */
4328 		STm->tape = tpnt;
4329 	}
4330 
4331 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4332 		STps = &(tpnt->ps[i]);
4333 		STps->rw = ST_IDLE;
4334 		STps->eof = ST_NOEOF;
4335 		STps->at_sm = 0;
4336 		STps->last_block_valid = 0;
4337 		STps->drv_block = (-1);
4338 		STps->drv_file = (-1);
4339 	}
4340 
4341 	tpnt->current_mode = 0;
4342 	tpnt->modes[0].defined = 1;
4343 
4344 	tpnt->density_changed = tpnt->compression_changed =
4345 	    tpnt->blksize_changed = 0;
4346 	mutex_init(&tpnt->lock);
4347 
4348 	idr_preload(GFP_KERNEL);
4349 	spin_lock(&st_index_lock);
4350 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4351 	spin_unlock(&st_index_lock);
4352 	idr_preload_end();
4353 	if (error < 0) {
4354 		pr_warn("st: idr allocation failed: %d\n", error);
4355 		goto out_free_tape;
4356 	}
4357 	tpnt->index = error;
4358 	sprintf(tpnt->name, "st%d", tpnt->index);
4359 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4360 	if (tpnt->stats == NULL) {
4361 		sdev_printk(KERN_ERR, SDp,
4362 			    "st: Can't allocate statistics.\n");
4363 		goto out_idr_remove;
4364 	}
4365 
4366 	dev_set_drvdata(dev, tpnt);
4367 
4368 
4369 	error = create_cdevs(tpnt);
4370 	if (error)
4371 		goto out_remove_devs;
4372 	scsi_autopm_put_device(SDp);
4373 
4374 	sdev_printk(KERN_NOTICE, SDp,
4375 		    "Attached scsi tape %s\n", tpnt->name);
4376 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4377 		    tpnt->name, tpnt->try_dio ? "yes" : "no",
4378 		    queue_dma_alignment(SDp->request_queue) + 1);
4379 
4380 	return 0;
4381 
4382 out_remove_devs:
4383 	remove_cdevs(tpnt);
4384 	kfree(tpnt->stats);
4385 out_idr_remove:
4386 	spin_lock(&st_index_lock);
4387 	idr_remove(&st_index_idr, tpnt->index);
4388 	spin_unlock(&st_index_lock);
4389 out_free_tape:
4390 	kfree(tpnt);
4391 out_buffer_free:
4392 	kfree(buffer);
4393 out:
4394 	scsi_autopm_put_device(SDp);
4395 	return -ENODEV;
4396 };
4397 
4398 
4399 static int st_remove(struct device *dev)
4400 {
4401 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4402 	int index = tpnt->index;
4403 
4404 	scsi_autopm_get_device(to_scsi_device(dev));
4405 	remove_cdevs(tpnt);
4406 
4407 	mutex_lock(&st_ref_mutex);
4408 	kref_put(&tpnt->kref, scsi_tape_release);
4409 	mutex_unlock(&st_ref_mutex);
4410 	spin_lock(&st_index_lock);
4411 	idr_remove(&st_index_idr, index);
4412 	spin_unlock(&st_index_lock);
4413 	return 0;
4414 }
4415 
4416 /**
4417  *      scsi_tape_release - Called to free the Scsi_Tape structure
4418  *      @kref: pointer to embedded kref
4419  *
4420  *      st_ref_mutex must be held entering this routine.  Because it is
4421  *      called on last put, you should always use the scsi_tape_get()
4422  *      scsi_tape_put() helpers which manipulate the semaphore directly
4423  *      and never do a direct kref_put().
4424  **/
4425 static void scsi_tape_release(struct kref *kref)
4426 {
4427 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4428 
4429 	tpnt->device = NULL;
4430 
4431 	if (tpnt->buffer) {
4432 		normalize_buffer(tpnt->buffer);
4433 		kfree(tpnt->buffer->reserved_pages);
4434 		kfree(tpnt->buffer);
4435 	}
4436 
4437 	kfree(tpnt->stats);
4438 	kfree(tpnt);
4439 	return;
4440 }
4441 
4442 static struct class st_sysfs_class = {
4443 	.name = "scsi_tape",
4444 	.dev_groups = st_dev_groups,
4445 };
4446 
4447 static int __init init_st(void)
4448 {
4449 	int err;
4450 
4451 	validate_options();
4452 
4453 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4454 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4455 
4456 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4457 	if (debugging) {
4458 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4459 			debugging);
4460 	}
4461 
4462 	err = class_register(&st_sysfs_class);
4463 	if (err) {
4464 		pr_err("Unable register sysfs class for SCSI tapes\n");
4465 		return err;
4466 	}
4467 
4468 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4469 				     ST_MAX_TAPE_ENTRIES, "st");
4470 	if (err) {
4471 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4472 		       SCSI_TAPE_MAJOR);
4473 		goto err_class;
4474 	}
4475 
4476 	err = scsi_register_driver(&st_template.gendrv);
4477 	if (err)
4478 		goto err_chrdev;
4479 
4480 	return 0;
4481 
4482 err_chrdev:
4483 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4484 				 ST_MAX_TAPE_ENTRIES);
4485 err_class:
4486 	class_unregister(&st_sysfs_class);
4487 	return err;
4488 }
4489 
4490 static void __exit exit_st(void)
4491 {
4492 	scsi_unregister_driver(&st_template.gendrv);
4493 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4494 				 ST_MAX_TAPE_ENTRIES);
4495 	class_unregister(&st_sysfs_class);
4496 	idr_destroy(&st_index_idr);
4497 	printk(KERN_INFO "st: Unloaded.\n");
4498 }
4499 
4500 module_init(init_st);
4501 module_exit(exit_st);
4502 
4503 
4504 /* The sysfs driver interface. Read-only at the moment */
4505 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4506 {
4507 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4508 }
4509 static DRIVER_ATTR_RO(try_direct_io);
4510 
4511 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4512 {
4513 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4514 }
4515 static DRIVER_ATTR_RO(fixed_buffer_size);
4516 
4517 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4518 {
4519 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4520 }
4521 static DRIVER_ATTR_RO(max_sg_segs);
4522 
4523 static ssize_t version_show(struct device_driver *ddd, char *buf)
4524 {
4525 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4526 }
4527 static DRIVER_ATTR_RO(version);
4528 
4529 #if DEBUG
4530 static ssize_t debug_flag_store(struct device_driver *ddp,
4531 	const char *buf, size_t count)
4532 {
4533 /* We only care what the first byte of the data is the rest is unused.
4534  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4535  * other values have -EINVAL returned if they are passed in.
4536  */
4537 	if (count > 0) {
4538 		if (buf[0] == '0') {
4539 			debugging = NO_DEBUG;
4540 			return count;
4541 		} else if (buf[0] == '1') {
4542 			debugging = 1;
4543 			return count;
4544 		}
4545 	}
4546 	return -EINVAL;
4547 }
4548 
4549 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4550 {
4551 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4552 }
4553 static DRIVER_ATTR_RW(debug_flag);
4554 #endif
4555 
4556 static struct attribute *st_drv_attrs[] = {
4557 	&driver_attr_try_direct_io.attr,
4558 	&driver_attr_fixed_buffer_size.attr,
4559 	&driver_attr_max_sg_segs.attr,
4560 	&driver_attr_version.attr,
4561 #if DEBUG
4562 	&driver_attr_debug_flag.attr,
4563 #endif
4564 	NULL,
4565 };
4566 ATTRIBUTE_GROUPS(st_drv);
4567 
4568 /* The sysfs simple class interface */
4569 static ssize_t
4570 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4571 {
4572 	struct st_modedef *STm = dev_get_drvdata(dev);
4573 	ssize_t l = 0;
4574 
4575 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4576 	return l;
4577 }
4578 static DEVICE_ATTR_RO(defined);
4579 
4580 static ssize_t
4581 default_blksize_show(struct device *dev, struct device_attribute *attr,
4582 		     char *buf)
4583 {
4584 	struct st_modedef *STm = dev_get_drvdata(dev);
4585 	ssize_t l = 0;
4586 
4587 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4588 	return l;
4589 }
4590 static DEVICE_ATTR_RO(default_blksize);
4591 
4592 static ssize_t
4593 default_density_show(struct device *dev, struct device_attribute *attr,
4594 		     char *buf)
4595 {
4596 	struct st_modedef *STm = dev_get_drvdata(dev);
4597 	ssize_t l = 0;
4598 	char *fmt;
4599 
4600 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4601 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4602 	return l;
4603 }
4604 static DEVICE_ATTR_RO(default_density);
4605 
4606 static ssize_t
4607 default_compression_show(struct device *dev, struct device_attribute *attr,
4608 			 char *buf)
4609 {
4610 	struct st_modedef *STm = dev_get_drvdata(dev);
4611 	ssize_t l = 0;
4612 
4613 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4614 	return l;
4615 }
4616 static DEVICE_ATTR_RO(default_compression);
4617 
4618 static ssize_t
4619 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4620 {
4621 	struct st_modedef *STm = dev_get_drvdata(dev);
4622 	struct scsi_tape *STp = STm->tape;
4623 	int options;
4624 	ssize_t l = 0;
4625 
4626 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4627 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4628 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4629 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4630 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4631 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4632 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4633 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4634 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4635 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4636 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4637 	options |= STm->sysv ? MT_ST_SYSV : 0;
4638 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4639 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4640 	options |= STp->sili ? MT_ST_SILI : 0;
4641 
4642 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4643 	return l;
4644 }
4645 static DEVICE_ATTR_RO(options);
4646 
4647 /* Support for tape stats */
4648 
4649 /**
4650  * read_cnt_show - return read count - count of reads made from tape drive
4651  * @dev: struct device
4652  * @attr: attribute structure
4653  * @buf: buffer to return formatted data in
4654  */
4655 static ssize_t read_cnt_show(struct device *dev,
4656 	struct device_attribute *attr, char *buf)
4657 {
4658 	struct st_modedef *STm = dev_get_drvdata(dev);
4659 
4660 	return sprintf(buf, "%lld",
4661 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4662 }
4663 static DEVICE_ATTR_RO(read_cnt);
4664 
4665 /**
4666  * read_byte_cnt_show - return read byte count - tape drives
4667  * may use blocks less than 512 bytes this gives the raw byte count of
4668  * of data read from the tape drive.
4669  * @dev: struct device
4670  * @attr: attribute structure
4671  * @buf: buffer to return formatted data in
4672  */
4673 static ssize_t read_byte_cnt_show(struct device *dev,
4674 	struct device_attribute *attr, char *buf)
4675 {
4676 	struct st_modedef *STm = dev_get_drvdata(dev);
4677 
4678 	return sprintf(buf, "%lld",
4679 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4680 }
4681 static DEVICE_ATTR_RO(read_byte_cnt);
4682 
4683 /**
4684  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4685  * @dev: struct device
4686  * @attr: attribute structure
4687  * @buf: buffer to return formatted data in
4688  */
4689 static ssize_t read_ns_show(struct device *dev,
4690 	struct device_attribute *attr, char *buf)
4691 {
4692 	struct st_modedef *STm = dev_get_drvdata(dev);
4693 
4694 	return sprintf(buf, "%lld",
4695 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4696 }
4697 static DEVICE_ATTR_RO(read_ns);
4698 
4699 /**
4700  * write_cnt_show - write count - number of user calls
4701  * to write(2) that have written data to tape.
4702  * @dev: struct device
4703  * @attr: attribute structure
4704  * @buf: buffer to return formatted data in
4705  */
4706 static ssize_t write_cnt_show(struct device *dev,
4707 	struct device_attribute *attr, char *buf)
4708 {
4709 	struct st_modedef *STm = dev_get_drvdata(dev);
4710 
4711 	return sprintf(buf, "%lld",
4712 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4713 }
4714 static DEVICE_ATTR_RO(write_cnt);
4715 
4716 /**
4717  * write_byte_cnt_show - write byte count - raw count of
4718  * bytes written to tape.
4719  * @dev: struct device
4720  * @attr: attribute structure
4721  * @buf: buffer to return formatted data in
4722  */
4723 static ssize_t write_byte_cnt_show(struct device *dev,
4724 	struct device_attribute *attr, char *buf)
4725 {
4726 	struct st_modedef *STm = dev_get_drvdata(dev);
4727 
4728 	return sprintf(buf, "%lld",
4729 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4730 }
4731 static DEVICE_ATTR_RO(write_byte_cnt);
4732 
4733 /**
4734  * write_ns_show - write ns - number of nanoseconds waiting on write
4735  * requests to complete.
4736  * @dev: struct device
4737  * @attr: attribute structure
4738  * @buf: buffer to return formatted data in
4739  */
4740 static ssize_t write_ns_show(struct device *dev,
4741 	struct device_attribute *attr, char *buf)
4742 {
4743 	struct st_modedef *STm = dev_get_drvdata(dev);
4744 
4745 	return sprintf(buf, "%lld",
4746 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4747 }
4748 static DEVICE_ATTR_RO(write_ns);
4749 
4750 /**
4751  * in_flight_show - number of I/Os currently in flight -
4752  * in most cases this will be either 0 or 1. It may be higher if someone
4753  * has also issued other SCSI commands such as via an ioctl.
4754  * @dev: struct device
4755  * @attr: attribute structure
4756  * @buf: buffer to return formatted data in
4757  */
4758 static ssize_t in_flight_show(struct device *dev,
4759 	struct device_attribute *attr, char *buf)
4760 {
4761 	struct st_modedef *STm = dev_get_drvdata(dev);
4762 
4763 	return sprintf(buf, "%lld",
4764 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4765 }
4766 static DEVICE_ATTR_RO(in_flight);
4767 
4768 /**
4769  * io_ns_show - io wait ns - this is the number of ns spent
4770  * waiting on all I/O to complete. This includes tape movement commands
4771  * such as rewinding, seeking to end of file or tape, it also includes
4772  * read and write. To determine the time spent on tape movement
4773  * subtract the read and write ns from this value.
4774  * @dev: struct device
4775  * @attr: attribute structure
4776  * @buf: buffer to return formatted data in
4777  */
4778 static ssize_t io_ns_show(struct device *dev,
4779 	struct device_attribute *attr, char *buf)
4780 {
4781 	struct st_modedef *STm = dev_get_drvdata(dev);
4782 
4783 	return sprintf(buf, "%lld",
4784 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4785 }
4786 static DEVICE_ATTR_RO(io_ns);
4787 
4788 /**
4789  * other_cnt_show - other io count - this is the number of
4790  * I/O requests other than read and write requests.
4791  * Typically these are tape movement requests but will include driver
4792  * tape movement. This includes only requests issued by the st driver.
4793  * @dev: struct device
4794  * @attr: attribute structure
4795  * @buf: buffer to return formatted data in
4796  */
4797 static ssize_t other_cnt_show(struct device *dev,
4798 	struct device_attribute *attr, char *buf)
4799 {
4800 	struct st_modedef *STm = dev_get_drvdata(dev);
4801 
4802 	return sprintf(buf, "%lld",
4803 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4804 }
4805 static DEVICE_ATTR_RO(other_cnt);
4806 
4807 /**
4808  * resid_cnt_show - A count of the number of times we get a residual
4809  * count - this should indicate someone issuing reads larger than the
4810  * block size on tape.
4811  * @dev: struct device
4812  * @attr: attribute structure
4813  * @buf: buffer to return formatted data in
4814  */
4815 static ssize_t resid_cnt_show(struct device *dev,
4816 	struct device_attribute *attr, char *buf)
4817 {
4818 	struct st_modedef *STm = dev_get_drvdata(dev);
4819 
4820 	return sprintf(buf, "%lld",
4821 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4822 }
4823 static DEVICE_ATTR_RO(resid_cnt);
4824 
4825 static struct attribute *st_dev_attrs[] = {
4826 	&dev_attr_defined.attr,
4827 	&dev_attr_default_blksize.attr,
4828 	&dev_attr_default_density.attr,
4829 	&dev_attr_default_compression.attr,
4830 	&dev_attr_options.attr,
4831 	NULL,
4832 };
4833 
4834 static struct attribute *st_stats_attrs[] = {
4835 	&dev_attr_read_cnt.attr,
4836 	&dev_attr_read_byte_cnt.attr,
4837 	&dev_attr_read_ns.attr,
4838 	&dev_attr_write_cnt.attr,
4839 	&dev_attr_write_byte_cnt.attr,
4840 	&dev_attr_write_ns.attr,
4841 	&dev_attr_in_flight.attr,
4842 	&dev_attr_io_ns.attr,
4843 	&dev_attr_other_cnt.attr,
4844 	&dev_attr_resid_cnt.attr,
4845 	NULL,
4846 };
4847 
4848 static struct attribute_group stats_group = {
4849 	.name = "stats",
4850 	.attrs = st_stats_attrs,
4851 };
4852 
4853 static struct attribute_group st_group = {
4854 	.attrs = st_dev_attrs,
4855 };
4856 
4857 static const struct attribute_group *st_dev_groups[] = {
4858 	&st_group,
4859 	&stats_group,
4860 	NULL,
4861 };
4862 
4863 /* The following functions may be useful for a larger audience. */
4864 static int sgl_map_user_pages(struct st_buffer *STbp,
4865 			      const unsigned int max_pages, unsigned long uaddr,
4866 			      size_t count, int rw)
4867 {
4868 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4869 	unsigned long start = uaddr >> PAGE_SHIFT;
4870 	const int nr_pages = end - start;
4871 	int res, i;
4872 	struct page **pages;
4873 	struct rq_map_data *mdata = &STbp->map_data;
4874 
4875 	/* User attempted Overflow! */
4876 	if ((uaddr + count) < uaddr)
4877 		return -EINVAL;
4878 
4879 	/* Too big */
4880         if (nr_pages > max_pages)
4881 		return -ENOMEM;
4882 
4883 	/* Hmm? */
4884 	if (count == 0)
4885 		return 0;
4886 
4887 	pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
4888 	if (pages == NULL)
4889 		return -ENOMEM;
4890 
4891         /* Try to fault in all of the necessary pages */
4892         /* rw==READ means read from drive, write into memory area */
4893 	res = pin_user_pages_fast(uaddr, nr_pages, rw == READ ? FOLL_WRITE : 0,
4894 				  pages);
4895 
4896 	/* Errors and no page mapped should return here */
4897 	if (res < nr_pages)
4898 		goto out_unmap;
4899 
4900         for (i=0; i < nr_pages; i++) {
4901                 /* FIXME: flush superflous for rw==READ,
4902                  * probably wrong function for rw==WRITE
4903                  */
4904 		flush_dcache_page(pages[i]);
4905         }
4906 
4907 	mdata->offset = uaddr & ~PAGE_MASK;
4908 	STbp->mapped_pages = pages;
4909 
4910 	return nr_pages;
4911  out_unmap:
4912 	if (res > 0) {
4913 		unpin_user_pages(pages, res);
4914 		res = 0;
4915 	}
4916 	kfree(pages);
4917 	return res;
4918 }
4919 
4920 
4921 /* And unmap them... */
4922 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4923 				const unsigned int nr_pages, int dirtied)
4924 {
4925 	/* FIXME: cache flush missing for rw==READ */
4926 	unpin_user_pages_dirty_lock(STbp->mapped_pages, nr_pages, dirtied);
4927 
4928 	kfree(STbp->mapped_pages);
4929 	STbp->mapped_pages = NULL;
4930 
4931 	return 0;
4932 }
4933