xref: /linux/drivers/scsi/st.c (revision 4ac6d90867a4de2e12117e755dbd76e08d88697f)
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/cdrom.h>
36 #include <linux/ioctl.h>
37 #include <linux/fcntl.h>
38 #include <linux/spinlock.h>
39 #include <linux/blkdev.h>
40 #include <linux/moduleparam.h>
41 #include <linux/cdev.h>
42 #include <linux/idr.h>
43 #include <linux/delay.h>
44 #include <linux/mutex.h>
45 
46 #include <linux/uaccess.h>
47 #include <asm/dma.h>
48 #include <asm/unaligned.h>
49 
50 #include <scsi/scsi.h>
51 #include <scsi/scsi_dbg.h>
52 #include <scsi/scsi_device.h>
53 #include <scsi/scsi_driver.h>
54 #include <scsi/scsi_eh.h>
55 #include <scsi/scsi_host.h>
56 #include <scsi/scsi_ioctl.h>
57 #include <scsi/sg.h>
58 
59 
60 /* The driver prints some debugging information on the console if DEBUG
61    is defined and non-zero. */
62 #define DEBUG 1
63 #define NO_DEBUG 0
64 
65 #define ST_DEB_MSG  KERN_NOTICE
66 #if DEBUG
67 /* The message level for the debug messages is currently set to KERN_NOTICE
68    so that people can easily see the messages. Later when the debugging messages
69    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
70 #define DEB(a) a
71 #define DEBC(a) if (debugging) { a ; }
72 #else
73 #define DEB(a)
74 #define DEBC(a)
75 #endif
76 
77 #define ST_KILOBYTE 1024
78 
79 #include "st_options.h"
80 #include "st.h"
81 
82 static int buffer_kbs;
83 static int max_sg_segs;
84 static int try_direct_io = TRY_DIRECT_IO;
85 static int try_rdio = 1;
86 static int try_wdio = 1;
87 static int debug_flag;
88 
89 static struct class st_sysfs_class;
90 static const struct attribute_group *st_dev_groups[];
91 static const struct attribute_group *st_drv_groups[];
92 
93 MODULE_AUTHOR("Kai Makisara");
94 MODULE_DESCRIPTION("SCSI tape (st) driver");
95 MODULE_LICENSE("GPL");
96 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
97 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
98 
99 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
100  * of sysfs parameters (which module_param doesn't yet support).
101  * Sysfs parameters defined explicitly later.
102  */
103 module_param_named(buffer_kbs, buffer_kbs, int, 0);
104 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
105 module_param_named(max_sg_segs, max_sg_segs, int, 0);
106 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
107 module_param_named(try_direct_io, try_direct_io, int, 0);
108 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
109 module_param_named(debug_flag, debug_flag, int, 0);
110 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
111 
112 
113 /* Extra parameters for testing */
114 module_param_named(try_rdio, try_rdio, int, 0);
115 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
116 module_param_named(try_wdio, try_wdio, int, 0);
117 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
118 
119 #ifndef MODULE
120 static int write_threshold_kbs;  /* retained for compatibility */
121 static struct st_dev_parm {
122 	char *name;
123 	int *val;
124 } parms[] __initdata = {
125 	{
126 		"buffer_kbs", &buffer_kbs
127 	},
128 	{       /* Retained for compatibility with 2.4 */
129 		"write_threshold_kbs", &write_threshold_kbs
130 	},
131 	{
132 		"max_sg_segs", NULL
133 	},
134 	{
135 		"try_direct_io", &try_direct_io
136 	},
137 	{
138 		"debug_flag", &debug_flag
139 	}
140 };
141 #endif
142 
143 /* Restrict the number of modes so that names for all are assigned */
144 #if ST_NBR_MODES > 16
145 #error "Maximum number of modes is 16"
146 #endif
147 /* Bit reversed order to get same names for same minors with all
148    mode counts */
149 static const char *st_formats[] = {
150 	"",  "r", "k", "s", "l", "t", "o", "u",
151 	"m", "v", "p", "x", "a", "y", "q", "z"};
152 
153 /* The default definitions have been moved to st_options.h */
154 
155 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
156 
157 /* The buffer size should fit into the 24 bits for length in the
158    6-byte SCSI read and write commands. */
159 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
160 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
161 #endif
162 
163 static int debugging = DEBUG;
164 
165 #define MAX_RETRIES 0
166 #define MAX_WRITE_RETRIES 0
167 #define MAX_READY_RETRIES 0
168 #define NO_TAPE  NOT_READY
169 
170 #define ST_TIMEOUT (900 * HZ)
171 #define ST_LONG_TIMEOUT (14000 * HZ)
172 
173 /* Remove mode bits and auto-rewind bit (7) */
174 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
175 	(iminor(x) & ((1 << ST_MODE_SHIFT)-1)))
176 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
177 
178 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
179 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
180   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
181 
182 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
183    24 bits) */
184 #define SET_DENS_AND_BLK 0x10001
185 
186 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
187 static int st_max_sg_segs = ST_MAX_SG;
188 
189 static int modes_defined;
190 
191 static int enlarge_buffer(struct st_buffer *, int);
192 static void clear_buffer(struct st_buffer *);
193 static void normalize_buffer(struct st_buffer *);
194 static int append_to_buffer(const char __user *, struct st_buffer *, int);
195 static int from_buffer(struct st_buffer *, char __user *, int);
196 static void move_buffer_data(struct st_buffer *, int);
197 
198 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
199 			      unsigned long, size_t, int);
200 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
201 
202 static int st_probe(struct device *);
203 static int st_remove(struct device *);
204 
205 static struct scsi_driver st_template = {
206 	.gendrv = {
207 		.name		= "st",
208 		.owner		= THIS_MODULE,
209 		.probe		= st_probe,
210 		.remove		= st_remove,
211 		.groups		= st_drv_groups,
212 	},
213 };
214 
215 static int st_compression(struct scsi_tape *, int);
216 
217 static int find_partition(struct scsi_tape *);
218 static int switch_partition(struct scsi_tape *);
219 
220 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
221 
222 static void scsi_tape_release(struct kref *);
223 
224 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
225 
226 static DEFINE_MUTEX(st_ref_mutex);
227 static DEFINE_SPINLOCK(st_index_lock);
228 static DEFINE_SPINLOCK(st_use_lock);
229 static DEFINE_IDR(st_index_idr);
230 
231 
232 
233 #ifndef SIGS_FROM_OSST
234 #define SIGS_FROM_OSST \
235 	{"OnStream", "SC-", "", "osst"}, \
236 	{"OnStream", "DI-", "", "osst"}, \
237 	{"OnStream", "DP-", "", "osst"}, \
238 	{"OnStream", "USB", "", "osst"}, \
239 	{"OnStream", "FW-", "", "osst"}
240 #endif
241 
242 static struct scsi_tape *scsi_tape_get(int dev)
243 {
244 	struct scsi_tape *STp = NULL;
245 
246 	mutex_lock(&st_ref_mutex);
247 	spin_lock(&st_index_lock);
248 
249 	STp = idr_find(&st_index_idr, dev);
250 	if (!STp) goto out;
251 
252 	kref_get(&STp->kref);
253 
254 	if (!STp->device)
255 		goto out_put;
256 
257 	if (scsi_device_get(STp->device))
258 		goto out_put;
259 
260 	goto out;
261 
262 out_put:
263 	kref_put(&STp->kref, scsi_tape_release);
264 	STp = NULL;
265 out:
266 	spin_unlock(&st_index_lock);
267 	mutex_unlock(&st_ref_mutex);
268 	return STp;
269 }
270 
271 static void scsi_tape_put(struct scsi_tape *STp)
272 {
273 	struct scsi_device *sdev = STp->device;
274 
275 	mutex_lock(&st_ref_mutex);
276 	kref_put(&STp->kref, scsi_tape_release);
277 	scsi_device_put(sdev);
278 	mutex_unlock(&st_ref_mutex);
279 }
280 
281 struct st_reject_data {
282 	char *vendor;
283 	char *model;
284 	char *rev;
285 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
286 };
287 
288 static struct st_reject_data reject_list[] = {
289 	/* {"XXX", "Yy-", "", NULL},  example */
290 	SIGS_FROM_OSST,
291 	{NULL, }};
292 
293 /* If the device signature is on the list of incompatible drives, the
294    function returns a pointer to the name of the correct driver (if known) */
295 static char * st_incompatible(struct scsi_device* SDp)
296 {
297 	struct st_reject_data *rp;
298 
299 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
300 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
301 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
302 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
303 			if (rp->driver_hint)
304 				return rp->driver_hint;
305 			else
306 				return "unknown";
307 		}
308 	return NULL;
309 }
310 
311 
312 #define st_printk(prefix, t, fmt, a...) \
313 	sdev_prefix_printk(prefix, (t)->device, (t)->name, fmt, ##a)
314 #ifdef DEBUG
315 #define DEBC_printk(t, fmt, a...) \
316 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
317 #else
318 #define DEBC_printk(t, fmt, a...)
319 #endif
320 
321 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
322 {
323 	const u8 *ucp;
324 	const u8 *sense = SRpnt->sense;
325 
326 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
327 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
328 	s->flags = 0;
329 
330 	if (s->have_sense) {
331 		s->deferred = 0;
332 		s->remainder_valid =
333 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
334 		switch (sense[0] & 0x7f) {
335 		case 0x71:
336 			s->deferred = 1;
337 			fallthrough;
338 		case 0x70:
339 			s->fixed_format = 1;
340 			s->flags = sense[2] & 0xe0;
341 			break;
342 		case 0x73:
343 			s->deferred = 1;
344 			fallthrough;
345 		case 0x72:
346 			s->fixed_format = 0;
347 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
348 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
349 			break;
350 		}
351 	}
352 }
353 
354 
355 /* Convert the result to success code */
356 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
357 {
358 	int result = SRpnt->result;
359 	u8 scode;
360 	DEB(const char *stp;)
361 	char *name = STp->name;
362 	struct st_cmdstatus *cmdstatp;
363 
364 	if (!result)
365 		return 0;
366 
367 	cmdstatp = &STp->buffer->cmdstat;
368 	st_analyze_sense(SRpnt, cmdstatp);
369 
370 	if (cmdstatp->have_sense)
371 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
372 	else
373 		scode = 0;
374 
375 	DEB(
376 	if (debugging) {
377 		st_printk(ST_DEB_MSG, STp,
378 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
379 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
380 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
381 		if (cmdstatp->have_sense)
382 			__scsi_print_sense(STp->device, name,
383 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
384 	} ) /* end DEB */
385 	if (!debugging) { /* Abnormal conditions for tape */
386 		if (!cmdstatp->have_sense)
387 			st_printk(KERN_WARNING, STp,
388 			       "Error %x (driver bt 0, host bt 0x%x).\n",
389 			       result, host_byte(result));
390 		else if (cmdstatp->have_sense &&
391 			 scode != NO_SENSE &&
392 			 scode != RECOVERED_ERROR &&
393 			 /* scode != UNIT_ATTENTION && */
394 			 scode != BLANK_CHECK &&
395 			 scode != VOLUME_OVERFLOW &&
396 			 SRpnt->cmd[0] != MODE_SENSE &&
397 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
398 
399 			__scsi_print_sense(STp->device, name,
400 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
401 		}
402 	}
403 
404 	if (cmdstatp->fixed_format &&
405 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
406 		if (STp->cln_sense_value)
407 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
408 					       STp->cln_sense_mask) == STp->cln_sense_value);
409 		else
410 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
411 					       STp->cln_sense_mask) != 0);
412 	}
413 	if (cmdstatp->have_sense &&
414 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
415 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
416 
417 	STp->pos_unknown |= STp->device->was_reset;
418 
419 	if (cmdstatp->have_sense &&
420 	    scode == RECOVERED_ERROR
421 #if ST_RECOVERED_WRITE_FATAL
422 	    && SRpnt->cmd[0] != WRITE_6
423 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
424 #endif
425 	    ) {
426 		STp->recover_count++;
427 		STp->recover_reg++;
428 
429 		DEB(
430 		if (debugging) {
431 			if (SRpnt->cmd[0] == READ_6)
432 				stp = "read";
433 			else if (SRpnt->cmd[0] == WRITE_6)
434 				stp = "write";
435 			else
436 				stp = "ioctl";
437 			st_printk(ST_DEB_MSG, STp,
438 				  "Recovered %s error (%d).\n",
439 				  stp, STp->recover_count);
440 		} ) /* end DEB */
441 
442 		if (cmdstatp->flags == 0)
443 			return 0;
444 	}
445 	return (-EIO);
446 }
447 
448 static struct st_request *st_allocate_request(struct scsi_tape *stp)
449 {
450 	struct st_request *streq;
451 
452 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
453 	if (streq)
454 		streq->stp = stp;
455 	else {
456 		st_printk(KERN_ERR, stp,
457 			  "Can't get SCSI request.\n");
458 		if (signal_pending(current))
459 			stp->buffer->syscall_result = -EINTR;
460 		else
461 			stp->buffer->syscall_result = -EBUSY;
462 	}
463 
464 	return streq;
465 }
466 
467 static void st_release_request(struct st_request *streq)
468 {
469 	kfree(streq);
470 }
471 
472 static void st_do_stats(struct scsi_tape *STp, struct request *req)
473 {
474 	ktime_t now;
475 
476 	now = ktime_get();
477 	if (scsi_req(req)->cmd[0] == WRITE_6) {
478 		now = ktime_sub(now, STp->stats->write_time);
479 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
480 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
481 		atomic64_inc(&STp->stats->write_cnt);
482 		if (scsi_req(req)->result) {
483 			atomic64_add(atomic_read(&STp->stats->last_write_size)
484 				- STp->buffer->cmdstat.residual,
485 				&STp->stats->write_byte_cnt);
486 			if (STp->buffer->cmdstat.residual > 0)
487 				atomic64_inc(&STp->stats->resid_cnt);
488 		} else
489 			atomic64_add(atomic_read(&STp->stats->last_write_size),
490 				&STp->stats->write_byte_cnt);
491 	} else if (scsi_req(req)->cmd[0] == READ_6) {
492 		now = ktime_sub(now, STp->stats->read_time);
493 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
494 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
495 		atomic64_inc(&STp->stats->read_cnt);
496 		if (scsi_req(req)->result) {
497 			atomic64_add(atomic_read(&STp->stats->last_read_size)
498 				- STp->buffer->cmdstat.residual,
499 				&STp->stats->read_byte_cnt);
500 			if (STp->buffer->cmdstat.residual > 0)
501 				atomic64_inc(&STp->stats->resid_cnt);
502 		} else
503 			atomic64_add(atomic_read(&STp->stats->last_read_size),
504 				&STp->stats->read_byte_cnt);
505 	} else {
506 		now = ktime_sub(now, STp->stats->other_time);
507 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
508 		atomic64_inc(&STp->stats->other_cnt);
509 	}
510 	atomic64_dec(&STp->stats->in_flight);
511 }
512 
513 static void st_scsi_execute_end(struct request *req, blk_status_t status)
514 {
515 	struct st_request *SRpnt = req->end_io_data;
516 	struct scsi_request *rq = scsi_req(req);
517 	struct scsi_tape *STp = SRpnt->stp;
518 	struct bio *tmp;
519 
520 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = rq->result;
521 	STp->buffer->cmdstat.residual = rq->resid_len;
522 
523 	st_do_stats(STp, req);
524 
525 	tmp = SRpnt->bio;
526 	if (rq->sense_len)
527 		memcpy(SRpnt->sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
528 	if (SRpnt->waiting)
529 		complete(SRpnt->waiting);
530 
531 	blk_rq_unmap_user(tmp);
532 	blk_put_request(req);
533 }
534 
535 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
536 			   int data_direction, void *buffer, unsigned bufflen,
537 			   int timeout, int retries)
538 {
539 	struct request *req;
540 	struct scsi_request *rq;
541 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
542 	int err = 0;
543 	struct scsi_tape *STp = SRpnt->stp;
544 
545 	req = blk_get_request(SRpnt->stp->device->request_queue,
546 			data_direction == DMA_TO_DEVICE ?
547 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
548 	if (IS_ERR(req))
549 		return PTR_ERR(req);
550 	rq = scsi_req(req);
551 	req->rq_flags |= RQF_QUIET;
552 
553 	mdata->null_mapped = 1;
554 
555 	if (bufflen) {
556 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
557 				      GFP_KERNEL);
558 		if (err) {
559 			blk_put_request(req);
560 			return err;
561 		}
562 	}
563 
564 	atomic64_inc(&STp->stats->in_flight);
565 	if (cmd[0] == WRITE_6) {
566 		atomic_set(&STp->stats->last_write_size, bufflen);
567 		STp->stats->write_time = ktime_get();
568 	} else if (cmd[0] == READ_6) {
569 		atomic_set(&STp->stats->last_read_size, bufflen);
570 		STp->stats->read_time = ktime_get();
571 	} else {
572 		STp->stats->other_time = ktime_get();
573 	}
574 
575 	SRpnt->bio = req->bio;
576 	rq->cmd_len = COMMAND_SIZE(cmd[0]);
577 	memset(rq->cmd, 0, BLK_MAX_CDB);
578 	memcpy(rq->cmd, cmd, rq->cmd_len);
579 	req->timeout = timeout;
580 	rq->retries = retries;
581 	req->end_io_data = SRpnt;
582 
583 	blk_execute_rq_nowait(NULL, req, 1, st_scsi_execute_end);
584 	return 0;
585 }
586 
587 /* Do the scsi command. Waits until command performed if do_wait is true.
588    Otherwise write_behind_check() is used to check that the command
589    has finished. */
590 static struct st_request *
591 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
592 	   int bytes, int direction, int timeout, int retries, int do_wait)
593 {
594 	struct completion *waiting;
595 	struct rq_map_data *mdata = &STp->buffer->map_data;
596 	int ret;
597 
598 	/* if async, make sure there's no command outstanding */
599 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
600 		st_printk(KERN_ERR, STp,
601 			  "Async command already active.\n");
602 		if (signal_pending(current))
603 			(STp->buffer)->syscall_result = (-EINTR);
604 		else
605 			(STp->buffer)->syscall_result = (-EBUSY);
606 		return NULL;
607 	}
608 
609 	if (!SRpnt) {
610 		SRpnt = st_allocate_request(STp);
611 		if (!SRpnt)
612 			return NULL;
613 	}
614 
615 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
616 	   which IO is outstanding. It's nulled out when the IO completes. */
617 	if (!do_wait)
618 		(STp->buffer)->last_SRpnt = SRpnt;
619 
620 	waiting = &STp->wait;
621 	init_completion(waiting);
622 	SRpnt->waiting = waiting;
623 
624 	if (STp->buffer->do_dio) {
625 		mdata->page_order = 0;
626 		mdata->nr_entries = STp->buffer->sg_segs;
627 		mdata->pages = STp->buffer->mapped_pages;
628 	} else {
629 		mdata->page_order = STp->buffer->reserved_page_order;
630 		mdata->nr_entries =
631 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
632 		mdata->pages = STp->buffer->reserved_pages;
633 		mdata->offset = 0;
634 	}
635 
636 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
637 	STp->buffer->cmdstat.have_sense = 0;
638 	STp->buffer->syscall_result = 0;
639 
640 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
641 			      retries);
642 	if (ret) {
643 		/* could not allocate the buffer or request was too large */
644 		(STp->buffer)->syscall_result = (-EBUSY);
645 		(STp->buffer)->last_SRpnt = NULL;
646 	} else if (do_wait) {
647 		wait_for_completion(waiting);
648 		SRpnt->waiting = NULL;
649 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
650 	}
651 
652 	return SRpnt;
653 }
654 
655 
656 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
657    write has been correct but EOM early warning reached, -EIO if write ended in
658    error or zero if write successful. Asynchronous writes are used only in
659    variable block mode. */
660 static int write_behind_check(struct scsi_tape * STp)
661 {
662 	int retval = 0;
663 	struct st_buffer *STbuffer;
664 	struct st_partstat *STps;
665 	struct st_cmdstatus *cmdstatp;
666 	struct st_request *SRpnt;
667 
668 	STbuffer = STp->buffer;
669 	if (!STbuffer->writing)
670 		return 0;
671 
672 	DEB(
673 	if (STp->write_pending)
674 		STp->nbr_waits++;
675 	else
676 		STp->nbr_finished++;
677 	) /* end DEB */
678 
679 	wait_for_completion(&(STp->wait));
680 	SRpnt = STbuffer->last_SRpnt;
681 	STbuffer->last_SRpnt = NULL;
682 	SRpnt->waiting = NULL;
683 
684 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
685 	st_release_request(SRpnt);
686 
687 	STbuffer->buffer_bytes -= STbuffer->writing;
688 	STps = &(STp->ps[STp->partition]);
689 	if (STps->drv_block >= 0) {
690 		if (STp->block_size == 0)
691 			STps->drv_block++;
692 		else
693 			STps->drv_block += STbuffer->writing / STp->block_size;
694 	}
695 
696 	cmdstatp = &STbuffer->cmdstat;
697 	if (STbuffer->syscall_result) {
698 		retval = -EIO;
699 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
700 		    (cmdstatp->flags & SENSE_EOM) &&
701 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
702 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
703 			/* EOM at write-behind, has all data been written? */
704 			if (!cmdstatp->remainder_valid ||
705 			    cmdstatp->uremainder64 == 0)
706 				retval = -ENOSPC;
707 		}
708 		if (retval == -EIO)
709 			STps->drv_block = -1;
710 	}
711 	STbuffer->writing = 0;
712 
713 	DEB(if (debugging && retval)
714 		    st_printk(ST_DEB_MSG, STp,
715 				"Async write error %x, return value %d.\n",
716 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
717 
718 	return retval;
719 }
720 
721 
722 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
723    it messes up the block number). */
724 static int cross_eof(struct scsi_tape * STp, int forward)
725 {
726 	struct st_request *SRpnt;
727 	unsigned char cmd[MAX_COMMAND_SIZE];
728 
729 	cmd[0] = SPACE;
730 	cmd[1] = 0x01;		/* Space FileMarks */
731 	if (forward) {
732 		cmd[2] = cmd[3] = 0;
733 		cmd[4] = 1;
734 	} else
735 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
736 	cmd[5] = 0;
737 
738 	DEBC_printk(STp, "Stepping over filemark %s.\n",
739 		    forward ? "forward" : "backward");
740 
741 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
742 			   STp->device->request_queue->rq_timeout,
743 			   MAX_RETRIES, 1);
744 	if (!SRpnt)
745 		return (STp->buffer)->syscall_result;
746 
747 	st_release_request(SRpnt);
748 	SRpnt = NULL;
749 
750 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
751 		st_printk(KERN_ERR, STp,
752 			  "Stepping over filemark %s failed.\n",
753 			  forward ? "forward" : "backward");
754 
755 	return (STp->buffer)->syscall_result;
756 }
757 
758 
759 /* Flush the write buffer (never need to write if variable blocksize). */
760 static int st_flush_write_buffer(struct scsi_tape * STp)
761 {
762 	int transfer, blks;
763 	int result;
764 	unsigned char cmd[MAX_COMMAND_SIZE];
765 	struct st_request *SRpnt;
766 	struct st_partstat *STps;
767 
768 	result = write_behind_check(STp);
769 	if (result)
770 		return result;
771 
772 	result = 0;
773 	if (STp->dirty == 1) {
774 
775 		transfer = STp->buffer->buffer_bytes;
776 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
777 
778 		memset(cmd, 0, MAX_COMMAND_SIZE);
779 		cmd[0] = WRITE_6;
780 		cmd[1] = 1;
781 		blks = transfer / STp->block_size;
782 		cmd[2] = blks >> 16;
783 		cmd[3] = blks >> 8;
784 		cmd[4] = blks;
785 
786 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
787 				   STp->device->request_queue->rq_timeout,
788 				   MAX_WRITE_RETRIES, 1);
789 		if (!SRpnt)
790 			return (STp->buffer)->syscall_result;
791 
792 		STps = &(STp->ps[STp->partition]);
793 		if ((STp->buffer)->syscall_result != 0) {
794 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
795 
796 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
797 			    (cmdstatp->flags & SENSE_EOM) &&
798 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
799 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
800 			    (!cmdstatp->remainder_valid ||
801 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
802 				STp->dirty = 0;
803 				(STp->buffer)->buffer_bytes = 0;
804 				if (STps->drv_block >= 0)
805 					STps->drv_block += blks;
806 				result = (-ENOSPC);
807 			} else {
808 				st_printk(KERN_ERR, STp, "Error on flush.\n");
809 				STps->drv_block = (-1);
810 				result = (-EIO);
811 			}
812 		} else {
813 			if (STps->drv_block >= 0)
814 				STps->drv_block += blks;
815 			STp->dirty = 0;
816 			(STp->buffer)->buffer_bytes = 0;
817 		}
818 		st_release_request(SRpnt);
819 		SRpnt = NULL;
820 	}
821 	return result;
822 }
823 
824 
825 /* Flush the tape buffer. The tape will be positioned correctly unless
826    seek_next is true. */
827 static int flush_buffer(struct scsi_tape *STp, int seek_next)
828 {
829 	int backspace, result;
830 	struct st_partstat *STps;
831 
832 	/*
833 	 * If there was a bus reset, block further access
834 	 * to this device.
835 	 */
836 	if (STp->pos_unknown)
837 		return (-EIO);
838 
839 	if (STp->ready != ST_READY)
840 		return 0;
841 	STps = &(STp->ps[STp->partition]);
842 	if (STps->rw == ST_WRITING)	/* Writing */
843 		return st_flush_write_buffer(STp);
844 
845 	if (STp->block_size == 0)
846 		return 0;
847 
848 	backspace = ((STp->buffer)->buffer_bytes +
849 		     (STp->buffer)->read_pointer) / STp->block_size -
850 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
851 	    STp->block_size;
852 	(STp->buffer)->buffer_bytes = 0;
853 	(STp->buffer)->read_pointer = 0;
854 	result = 0;
855 	if (!seek_next) {
856 		if (STps->eof == ST_FM_HIT) {
857 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
858 			if (!result)
859 				STps->eof = ST_NOEOF;
860 			else {
861 				if (STps->drv_file >= 0)
862 					STps->drv_file++;
863 				STps->drv_block = 0;
864 			}
865 		}
866 		if (!result && backspace > 0)
867 			result = st_int_ioctl(STp, MTBSR, backspace);
868 	} else if (STps->eof == ST_FM_HIT) {
869 		if (STps->drv_file >= 0)
870 			STps->drv_file++;
871 		STps->drv_block = 0;
872 		STps->eof = ST_NOEOF;
873 	}
874 	return result;
875 
876 }
877 
878 /* Set the mode parameters */
879 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
880 {
881 	int set_it = 0;
882 	unsigned long arg;
883 
884 	if (!STp->density_changed &&
885 	    STm->default_density >= 0 &&
886 	    STm->default_density != STp->density) {
887 		arg = STm->default_density;
888 		set_it = 1;
889 	} else
890 		arg = STp->density;
891 	arg <<= MT_ST_DENSITY_SHIFT;
892 	if (!STp->blksize_changed &&
893 	    STm->default_blksize >= 0 &&
894 	    STm->default_blksize != STp->block_size) {
895 		arg |= STm->default_blksize;
896 		set_it = 1;
897 	} else
898 		arg |= STp->block_size;
899 	if (set_it &&
900 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
901 		st_printk(KERN_WARNING, STp,
902 			  "Can't set default block size to %d bytes "
903 			  "and density %x.\n",
904 			  STm->default_blksize, STm->default_density);
905 		if (modes_defined)
906 			return (-EINVAL);
907 	}
908 	return 0;
909 }
910 
911 
912 /* Lock or unlock the drive door. Don't use when st_request allocated. */
913 static int do_door_lock(struct scsi_tape * STp, int do_lock)
914 {
915 	int retval;
916 
917 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
918 
919 	retval = scsi_set_medium_removal(STp->device,
920 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
921 	if (!retval)
922 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
923 	else
924 		STp->door_locked = ST_LOCK_FAILS;
925 	return retval;
926 }
927 
928 
929 /* Set the internal state after reset */
930 static void reset_state(struct scsi_tape *STp)
931 {
932 	int i;
933 	struct st_partstat *STps;
934 
935 	STp->pos_unknown = 0;
936 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
937 		STps = &(STp->ps[i]);
938 		STps->rw = ST_IDLE;
939 		STps->eof = ST_NOEOF;
940 		STps->at_sm = 0;
941 		STps->last_block_valid = 0;
942 		STps->drv_block = -1;
943 		STps->drv_file = -1;
944 	}
945 	if (STp->can_partitions) {
946 		STp->partition = find_partition(STp);
947 		if (STp->partition < 0)
948 			STp->partition = 0;
949 		STp->new_partition = STp->partition;
950 	}
951 }
952 
953 /* Test if the drive is ready. Returns either one of the codes below or a negative system
954    error code. */
955 #define CHKRES_READY       0
956 #define CHKRES_NEW_SESSION 1
957 #define CHKRES_NOT_READY   2
958 #define CHKRES_NO_TAPE     3
959 
960 #define MAX_ATTENTIONS    10
961 
962 static int test_ready(struct scsi_tape *STp, int do_wait)
963 {
964 	int attentions, waits, max_wait, scode;
965 	int retval = CHKRES_READY, new_session = 0;
966 	unsigned char cmd[MAX_COMMAND_SIZE];
967 	struct st_request *SRpnt = NULL;
968 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
969 
970 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
971 
972 	for (attentions=waits=0; ; ) {
973 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
974 		cmd[0] = TEST_UNIT_READY;
975 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
976 				   STp->long_timeout, MAX_READY_RETRIES, 1);
977 
978 		if (!SRpnt) {
979 			retval = (STp->buffer)->syscall_result;
980 			break;
981 		}
982 
983 		if (cmdstatp->have_sense) {
984 
985 			scode = cmdstatp->sense_hdr.sense_key;
986 
987 			if (scode == UNIT_ATTENTION) { /* New media? */
988 				new_session = 1;
989 				if (attentions < MAX_ATTENTIONS) {
990 					attentions++;
991 					continue;
992 				}
993 				else {
994 					retval = (-EIO);
995 					break;
996 				}
997 			}
998 
999 			if (scode == NOT_READY) {
1000 				if (waits < max_wait) {
1001 					if (msleep_interruptible(1000)) {
1002 						retval = (-EINTR);
1003 						break;
1004 					}
1005 					waits++;
1006 					continue;
1007 				}
1008 				else {
1009 					if ((STp->device)->scsi_level >= SCSI_2 &&
1010 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1011 						retval = CHKRES_NO_TAPE;
1012 					else
1013 						retval = CHKRES_NOT_READY;
1014 					break;
1015 				}
1016 			}
1017 		}
1018 
1019 		retval = (STp->buffer)->syscall_result;
1020 		if (!retval)
1021 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1022 		break;
1023 	}
1024 
1025 	if (SRpnt != NULL)
1026 		st_release_request(SRpnt);
1027 	return retval;
1028 }
1029 
1030 
1031 /* See if the drive is ready and gather information about the tape. Return values:
1032    < 0   negative error code from errno.h
1033    0     drive ready
1034    1     drive not ready (possibly no tape)
1035 */
1036 static int check_tape(struct scsi_tape *STp, struct file *filp)
1037 {
1038 	int i, retval, new_session = 0, do_wait;
1039 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1040 	unsigned short st_flags = filp->f_flags;
1041 	struct st_request *SRpnt = NULL;
1042 	struct st_modedef *STm;
1043 	struct st_partstat *STps;
1044 	struct inode *inode = file_inode(filp);
1045 	int mode = TAPE_MODE(inode);
1046 
1047 	STp->ready = ST_READY;
1048 
1049 	if (mode != STp->current_mode) {
1050 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1051 			    STp->current_mode, mode);
1052 		new_session = 1;
1053 		STp->current_mode = mode;
1054 	}
1055 	STm = &(STp->modes[STp->current_mode]);
1056 
1057 	saved_cleaning = STp->cleaning_req;
1058 	STp->cleaning_req = 0;
1059 
1060 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1061 	retval = test_ready(STp, do_wait);
1062 
1063 	if (retval < 0)
1064 	    goto err_out;
1065 
1066 	if (retval == CHKRES_NEW_SESSION) {
1067 		STp->pos_unknown = 0;
1068 		STp->partition = STp->new_partition = 0;
1069 		if (STp->can_partitions)
1070 			STp->nbr_partitions = 1; /* This guess will be updated later
1071                                                     if necessary */
1072 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1073 			STps = &(STp->ps[i]);
1074 			STps->rw = ST_IDLE;
1075 			STps->eof = ST_NOEOF;
1076 			STps->at_sm = 0;
1077 			STps->last_block_valid = 0;
1078 			STps->drv_block = 0;
1079 			STps->drv_file = 0;
1080 		}
1081 		new_session = 1;
1082 	}
1083 	else {
1084 		STp->cleaning_req |= saved_cleaning;
1085 
1086 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1087 			if (retval == CHKRES_NO_TAPE)
1088 				STp->ready = ST_NO_TAPE;
1089 			else
1090 				STp->ready = ST_NOT_READY;
1091 
1092 			STp->density = 0;	/* Clear the erroneous "residue" */
1093 			STp->write_prot = 0;
1094 			STp->block_size = 0;
1095 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1096 			STp->partition = STp->new_partition = 0;
1097 			STp->door_locked = ST_UNLOCKED;
1098 			return CHKRES_NOT_READY;
1099 		}
1100 	}
1101 
1102 	if (STp->omit_blklims)
1103 		STp->min_block = STp->max_block = (-1);
1104 	else {
1105 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1106 		cmd[0] = READ_BLOCK_LIMITS;
1107 
1108 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1109 				   STp->device->request_queue->rq_timeout,
1110 				   MAX_READY_RETRIES, 1);
1111 		if (!SRpnt) {
1112 			retval = (STp->buffer)->syscall_result;
1113 			goto err_out;
1114 		}
1115 
1116 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1117 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1118 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1119 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1120 			    (STp->buffer)->b_data[5];
1121 			if ( DEB( debugging || ) !STp->inited)
1122 				st_printk(KERN_INFO, STp,
1123 					  "Block limits %d - %d bytes.\n",
1124 					  STp->min_block, STp->max_block);
1125 		} else {
1126 			STp->min_block = STp->max_block = (-1);
1127 			DEBC_printk(STp, "Can't read block limits.\n");
1128 		}
1129 	}
1130 
1131 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1132 	cmd[0] = MODE_SENSE;
1133 	cmd[4] = 12;
1134 
1135 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1136 			   STp->device->request_queue->rq_timeout,
1137 			   MAX_READY_RETRIES, 1);
1138 	if (!SRpnt) {
1139 		retval = (STp->buffer)->syscall_result;
1140 		goto err_out;
1141 	}
1142 
1143 	if ((STp->buffer)->syscall_result != 0) {
1144 		DEBC_printk(STp, "No Mode Sense.\n");
1145 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1146 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1147 		STp->drv_write_prot = 0;
1148 	} else {
1149 		DEBC_printk(STp,"Mode sense. Length %d, "
1150 			    "medium %x, WBS %x, BLL %d\n",
1151 			    (STp->buffer)->b_data[0],
1152 			    (STp->buffer)->b_data[1],
1153 			    (STp->buffer)->b_data[2],
1154 			    (STp->buffer)->b_data[3]);
1155 
1156 		if ((STp->buffer)->b_data[3] >= 8) {
1157 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1158 			STp->density = (STp->buffer)->b_data[4];
1159 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1160 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1161 			DEBC_printk(STp, "Density %x, tape length: %x, "
1162 				    "drv buffer: %d\n",
1163 				    STp->density,
1164 				    (STp->buffer)->b_data[5] * 65536 +
1165 				    (STp->buffer)->b_data[6] * 256 +
1166 				    (STp->buffer)->b_data[7],
1167 				    STp->drv_buffer);
1168 		}
1169 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1170 		if (!STp->drv_buffer && STp->immediate_filemark) {
1171 			st_printk(KERN_WARNING, STp,
1172 				  "non-buffered tape: disabling "
1173 				  "writing immediate filemarks\n");
1174 			STp->immediate_filemark = 0;
1175 		}
1176 	}
1177 	st_release_request(SRpnt);
1178 	SRpnt = NULL;
1179 	STp->inited = 1;
1180 
1181 	if (STp->block_size > 0)
1182 		(STp->buffer)->buffer_blocks =
1183 			(STp->buffer)->buffer_size / STp->block_size;
1184 	else
1185 		(STp->buffer)->buffer_blocks = 1;
1186 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1187 
1188 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1189 		    STp->block_size, (STp->buffer)->buffer_size,
1190 		    (STp->buffer)->buffer_blocks);
1191 
1192 	if (STp->drv_write_prot) {
1193 		STp->write_prot = 1;
1194 
1195 		DEBC_printk(STp, "Write protected\n");
1196 
1197 		if (do_wait &&
1198 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1199 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1200 			retval = (-EROFS);
1201 			goto err_out;
1202 		}
1203 	}
1204 
1205 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1206 		/* This code is reached when the device is opened for the first time
1207 		   after the driver has been initialized with tape in the drive and the
1208 		   partition support has been enabled. */
1209 		DEBC_printk(STp, "Updating partition number in status.\n");
1210 		if ((STp->partition = find_partition(STp)) < 0) {
1211 			retval = STp->partition;
1212 			goto err_out;
1213 		}
1214 		STp->new_partition = STp->partition;
1215 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1216 	}
1217 
1218 	if (new_session) {	/* Change the drive parameters for the new mode */
1219 		STp->density_changed = STp->blksize_changed = 0;
1220 		STp->compression_changed = 0;
1221 		if (!(STm->defaults_for_writes) &&
1222 		    (retval = set_mode_densblk(STp, STm)) < 0)
1223 		    goto err_out;
1224 
1225 		if (STp->default_drvbuffer != 0xff) {
1226 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1227 				st_printk(KERN_WARNING, STp,
1228 					  "Can't set default drive "
1229 					  "buffering to %d.\n",
1230 					  STp->default_drvbuffer);
1231 		}
1232 	}
1233 
1234 	return CHKRES_READY;
1235 
1236  err_out:
1237 	return retval;
1238 }
1239 
1240 
1241 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1242    module count. */
1243 static int st_open(struct inode *inode, struct file *filp)
1244 {
1245 	int i, retval = (-EIO);
1246 	int resumed = 0;
1247 	struct scsi_tape *STp;
1248 	struct st_partstat *STps;
1249 	int dev = TAPE_NR(inode);
1250 
1251 	/*
1252 	 * We really want to do nonseekable_open(inode, filp); here, but some
1253 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1254 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1255 	 */
1256 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1257 
1258 	if (!(STp = scsi_tape_get(dev))) {
1259 		return -ENXIO;
1260 	}
1261 
1262 	filp->private_data = STp;
1263 
1264 	spin_lock(&st_use_lock);
1265 	if (STp->in_use) {
1266 		spin_unlock(&st_use_lock);
1267 		DEBC_printk(STp, "Device already in use.\n");
1268 		scsi_tape_put(STp);
1269 		return (-EBUSY);
1270 	}
1271 
1272 	STp->in_use = 1;
1273 	spin_unlock(&st_use_lock);
1274 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1275 
1276 	if (scsi_autopm_get_device(STp->device) < 0) {
1277 		retval = -EIO;
1278 		goto err_out;
1279 	}
1280 	resumed = 1;
1281 	if (!scsi_block_when_processing_errors(STp->device)) {
1282 		retval = (-ENXIO);
1283 		goto err_out;
1284 	}
1285 
1286 	/* See that we have at least a one page buffer available */
1287 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE)) {
1288 		st_printk(KERN_WARNING, STp,
1289 			  "Can't allocate one page tape buffer.\n");
1290 		retval = (-EOVERFLOW);
1291 		goto err_out;
1292 	}
1293 
1294 	(STp->buffer)->cleared = 0;
1295 	(STp->buffer)->writing = 0;
1296 	(STp->buffer)->syscall_result = 0;
1297 
1298 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1299 
1300 	STp->dirty = 0;
1301 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1302 		STps = &(STp->ps[i]);
1303 		STps->rw = ST_IDLE;
1304 	}
1305 	STp->try_dio_now = STp->try_dio;
1306 	STp->recover_count = 0;
1307 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1308 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1309 
1310 	retval = check_tape(STp, filp);
1311 	if (retval < 0)
1312 		goto err_out;
1313 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1314 	    retval != CHKRES_READY) {
1315 		if (STp->ready == NO_TAPE)
1316 			retval = (-ENOMEDIUM);
1317 		else
1318 			retval = (-EIO);
1319 		goto err_out;
1320 	}
1321 	return 0;
1322 
1323  err_out:
1324 	normalize_buffer(STp->buffer);
1325 	spin_lock(&st_use_lock);
1326 	STp->in_use = 0;
1327 	spin_unlock(&st_use_lock);
1328 	if (resumed)
1329 		scsi_autopm_put_device(STp->device);
1330 	scsi_tape_put(STp);
1331 	return retval;
1332 
1333 }
1334 
1335 
1336 /* Flush the tape buffer before close */
1337 static int st_flush(struct file *filp, fl_owner_t id)
1338 {
1339 	int result = 0, result2;
1340 	unsigned char cmd[MAX_COMMAND_SIZE];
1341 	struct st_request *SRpnt;
1342 	struct scsi_tape *STp = filp->private_data;
1343 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1344 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1345 
1346 	if (file_count(filp) > 1)
1347 		return 0;
1348 
1349 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1350 		result = st_flush_write_buffer(STp);
1351 		if (result != 0 && result != (-ENOSPC))
1352 			goto out;
1353 	}
1354 
1355 	if (STp->can_partitions &&
1356 	    (result2 = switch_partition(STp)) < 0) {
1357 		DEBC_printk(STp, "switch_partition at close failed.\n");
1358 		if (result == 0)
1359 			result = result2;
1360 		goto out;
1361 	}
1362 
1363 	DEBC( if (STp->nbr_requests)
1364 		st_printk(KERN_DEBUG, STp,
1365 			  "Number of r/w requests %d, dio used in %d, "
1366 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1367 			  STp->nbr_pages));
1368 
1369 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1370 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1371 
1372 #if DEBUG
1373 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1374 			    STp->nbr_waits, STp->nbr_finished);
1375 #endif
1376 		memset(cmd, 0, MAX_COMMAND_SIZE);
1377 		cmd[0] = WRITE_FILEMARKS;
1378 		if (STp->immediate_filemark)
1379 			cmd[1] = 1;
1380 		cmd[4] = 1 + STp->two_fm;
1381 
1382 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1383 				   STp->device->request_queue->rq_timeout,
1384 				   MAX_WRITE_RETRIES, 1);
1385 		if (!SRpnt) {
1386 			result = (STp->buffer)->syscall_result;
1387 			goto out;
1388 		}
1389 
1390 		if (STp->buffer->syscall_result == 0 ||
1391 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1392 		     (cmdstatp->flags & SENSE_EOM) &&
1393 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1394 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1395 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1396 			/* Write successful at EOM */
1397 			st_release_request(SRpnt);
1398 			SRpnt = NULL;
1399 			if (STps->drv_file >= 0)
1400 				STps->drv_file++;
1401 			STps->drv_block = 0;
1402 			if (STp->two_fm)
1403 				cross_eof(STp, 0);
1404 			STps->eof = ST_FM;
1405 		}
1406 		else { /* Write error */
1407 			st_release_request(SRpnt);
1408 			SRpnt = NULL;
1409 			st_printk(KERN_ERR, STp,
1410 				  "Error on write filemark.\n");
1411 			if (result == 0)
1412 				result = (-EIO);
1413 		}
1414 
1415 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1416 	} else if (!STp->rew_at_close) {
1417 		STps = &(STp->ps[STp->partition]);
1418 		if (!STm->sysv || STps->rw != ST_READING) {
1419 			if (STp->can_bsr)
1420 				result = flush_buffer(STp, 0);
1421 			else if (STps->eof == ST_FM_HIT) {
1422 				result = cross_eof(STp, 0);
1423 				if (result) {
1424 					if (STps->drv_file >= 0)
1425 						STps->drv_file++;
1426 					STps->drv_block = 0;
1427 					STps->eof = ST_FM;
1428 				} else
1429 					STps->eof = ST_NOEOF;
1430 			}
1431 		} else if ((STps->eof == ST_NOEOF &&
1432 			    !(result = cross_eof(STp, 1))) ||
1433 			   STps->eof == ST_FM_HIT) {
1434 			if (STps->drv_file >= 0)
1435 				STps->drv_file++;
1436 			STps->drv_block = 0;
1437 			STps->eof = ST_FM;
1438 		}
1439 	}
1440 
1441       out:
1442 	if (STp->rew_at_close) {
1443 		result2 = st_int_ioctl(STp, MTREW, 1);
1444 		if (result == 0)
1445 			result = result2;
1446 	}
1447 	return result;
1448 }
1449 
1450 
1451 /* Close the device and release it. BKL is not needed: this is the only thread
1452    accessing this tape. */
1453 static int st_release(struct inode *inode, struct file *filp)
1454 {
1455 	struct scsi_tape *STp = filp->private_data;
1456 
1457 	if (STp->door_locked == ST_LOCKED_AUTO)
1458 		do_door_lock(STp, 0);
1459 
1460 	normalize_buffer(STp->buffer);
1461 	spin_lock(&st_use_lock);
1462 	STp->in_use = 0;
1463 	spin_unlock(&st_use_lock);
1464 	scsi_autopm_put_device(STp->device);
1465 	scsi_tape_put(STp);
1466 
1467 	return 0;
1468 }
1469 
1470 /* The checks common to both reading and writing */
1471 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1472 {
1473 	ssize_t retval = 0;
1474 
1475 	/*
1476 	 * If we are in the middle of error recovery, don't let anyone
1477 	 * else try and use this device.  Also, if error recovery fails, it
1478 	 * may try and take the device offline, in which case all further
1479 	 * access to the device is prohibited.
1480 	 */
1481 	if (!scsi_block_when_processing_errors(STp->device)) {
1482 		retval = (-ENXIO);
1483 		goto out;
1484 	}
1485 
1486 	if (STp->ready != ST_READY) {
1487 		if (STp->ready == ST_NO_TAPE)
1488 			retval = (-ENOMEDIUM);
1489 		else
1490 			retval = (-EIO);
1491 		goto out;
1492 	}
1493 
1494 	if (! STp->modes[STp->current_mode].defined) {
1495 		retval = (-ENXIO);
1496 		goto out;
1497 	}
1498 
1499 
1500 	/*
1501 	 * If there was a bus reset, block further access
1502 	 * to this device.
1503 	 */
1504 	if (STp->pos_unknown) {
1505 		retval = (-EIO);
1506 		goto out;
1507 	}
1508 
1509 	if (count == 0)
1510 		goto out;
1511 
1512 	DEB(
1513 	if (!STp->in_use) {
1514 		st_printk(ST_DEB_MSG, STp,
1515 			  "Incorrect device.\n");
1516 		retval = (-EIO);
1517 		goto out;
1518 	} ) /* end DEB */
1519 
1520 	if (STp->can_partitions &&
1521 	    (retval = switch_partition(STp)) < 0)
1522 		goto out;
1523 
1524 	if (STp->block_size == 0 && STp->max_block > 0 &&
1525 	    (count < STp->min_block || count > STp->max_block)) {
1526 		retval = (-EINVAL);
1527 		goto out;
1528 	}
1529 
1530 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1531 	    !do_door_lock(STp, 1))
1532 		STp->door_locked = ST_LOCKED_AUTO;
1533 
1534  out:
1535 	return retval;
1536 }
1537 
1538 
1539 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1540 			   size_t count, int is_read)
1541 {
1542 	int i, bufsize, retval = 0;
1543 	struct st_buffer *STbp = STp->buffer;
1544 
1545 	if (is_read)
1546 		i = STp->try_dio_now && try_rdio;
1547 	else
1548 		i = STp->try_dio_now && try_wdio;
1549 
1550 	if (i && ((unsigned long)buf & queue_dma_alignment(
1551 					STp->device->request_queue)) == 0) {
1552 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1553 				       count, (is_read ? READ : WRITE));
1554 		if (i > 0) {
1555 			STbp->do_dio = i;
1556 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1557 		}
1558 		else
1559 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1560 		STbp->sg_segs = STbp->do_dio;
1561 		DEB(
1562 		     if (STbp->do_dio) {
1563 			STp->nbr_dio++;
1564 			STp->nbr_pages += STbp->do_dio;
1565 		     }
1566 		)
1567 	} else
1568 		STbp->do_dio = 0;
1569 	DEB( STp->nbr_requests++; )
1570 
1571 	if (!STbp->do_dio) {
1572 		if (STp->block_size)
1573 			bufsize = STp->block_size > st_fixed_buffer_size ?
1574 				STp->block_size : st_fixed_buffer_size;
1575 		else {
1576 			bufsize = count;
1577 			/* Make sure that data from previous user is not leaked even if
1578 			   HBA does not return correct residual */
1579 			if (is_read && STp->sili && !STbp->cleared)
1580 				clear_buffer(STbp);
1581 		}
1582 
1583 		if (bufsize > STbp->buffer_size &&
1584 		    !enlarge_buffer(STbp, bufsize)) {
1585 			st_printk(KERN_WARNING, STp,
1586 				  "Can't allocate %d byte tape buffer.\n",
1587 				  bufsize);
1588 			retval = (-EOVERFLOW);
1589 			goto out;
1590 		}
1591 		if (STp->block_size)
1592 			STbp->buffer_blocks = bufsize / STp->block_size;
1593 	}
1594 
1595  out:
1596 	return retval;
1597 }
1598 
1599 
1600 /* Can be called more than once after each setup_buffer() */
1601 static void release_buffering(struct scsi_tape *STp, int is_read)
1602 {
1603 	struct st_buffer *STbp;
1604 
1605 	STbp = STp->buffer;
1606 	if (STbp->do_dio) {
1607 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1608 		STbp->do_dio = 0;
1609 		STbp->sg_segs = 0;
1610 	}
1611 }
1612 
1613 
1614 /* Write command */
1615 static ssize_t
1616 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1617 {
1618 	ssize_t total;
1619 	ssize_t i, do_count, blks, transfer;
1620 	ssize_t retval;
1621 	int undone, retry_eot = 0, scode;
1622 	int async_write;
1623 	unsigned char cmd[MAX_COMMAND_SIZE];
1624 	const char __user *b_point;
1625 	struct st_request *SRpnt = NULL;
1626 	struct scsi_tape *STp = filp->private_data;
1627 	struct st_modedef *STm;
1628 	struct st_partstat *STps;
1629 	struct st_buffer *STbp;
1630 
1631 	if (mutex_lock_interruptible(&STp->lock))
1632 		return -ERESTARTSYS;
1633 
1634 	retval = rw_checks(STp, filp, count);
1635 	if (retval || count == 0)
1636 		goto out;
1637 
1638 	/* Write must be integral number of blocks */
1639 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1640 		st_printk(KERN_WARNING, STp,
1641 			  "Write not multiple of tape block size.\n");
1642 		retval = (-EINVAL);
1643 		goto out;
1644 	}
1645 
1646 	STm = &(STp->modes[STp->current_mode]);
1647 	STps = &(STp->ps[STp->partition]);
1648 
1649 	if (STp->write_prot) {
1650 		retval = (-EACCES);
1651 		goto out;
1652 	}
1653 
1654 
1655 	if (STps->rw == ST_READING) {
1656 		retval = flush_buffer(STp, 0);
1657 		if (retval)
1658 			goto out;
1659 		STps->rw = ST_WRITING;
1660 	} else if (STps->rw != ST_WRITING &&
1661 		   STps->drv_file == 0 && STps->drv_block == 0) {
1662 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1663 			goto out;
1664 		if (STm->default_compression != ST_DONT_TOUCH &&
1665 		    !(STp->compression_changed)) {
1666 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1667 				st_printk(KERN_WARNING, STp,
1668 					  "Can't set default compression.\n");
1669 				if (modes_defined) {
1670 					retval = (-EINVAL);
1671 					goto out;
1672 				}
1673 			}
1674 		}
1675 	}
1676 
1677 	STbp = STp->buffer;
1678 	i = write_behind_check(STp);
1679 	if (i) {
1680 		if (i == -ENOSPC)
1681 			STps->eof = ST_EOM_OK;
1682 		else
1683 			STps->eof = ST_EOM_ERROR;
1684 	}
1685 
1686 	if (STps->eof == ST_EOM_OK) {
1687 		STps->eof = ST_EOD_1;  /* allow next write */
1688 		retval = (-ENOSPC);
1689 		goto out;
1690 	}
1691 	else if (STps->eof == ST_EOM_ERROR) {
1692 		retval = (-EIO);
1693 		goto out;
1694 	}
1695 
1696 	/* Check the buffer readability in cases where copy_user might catch
1697 	   the problems after some tape movement. */
1698 	if (STp->block_size != 0 &&
1699 	    !STbp->do_dio &&
1700 	    (copy_from_user(&i, buf, 1) != 0 ||
1701 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1702 		retval = (-EFAULT);
1703 		goto out;
1704 	}
1705 
1706 	retval = setup_buffering(STp, buf, count, 0);
1707 	if (retval)
1708 		goto out;
1709 
1710 	total = count;
1711 
1712 	memset(cmd, 0, MAX_COMMAND_SIZE);
1713 	cmd[0] = WRITE_6;
1714 	cmd[1] = (STp->block_size != 0);
1715 
1716 	STps->rw = ST_WRITING;
1717 
1718 	b_point = buf;
1719 	while (count > 0 && !retry_eot) {
1720 
1721 		if (STbp->do_dio) {
1722 			do_count = count;
1723 		}
1724 		else {
1725 			if (STp->block_size == 0)
1726 				do_count = count;
1727 			else {
1728 				do_count = STbp->buffer_blocks * STp->block_size -
1729 					STbp->buffer_bytes;
1730 				if (do_count > count)
1731 					do_count = count;
1732 			}
1733 
1734 			i = append_to_buffer(b_point, STbp, do_count);
1735 			if (i) {
1736 				retval = i;
1737 				goto out;
1738 			}
1739 		}
1740 		count -= do_count;
1741 		b_point += do_count;
1742 
1743 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1744 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1745 
1746 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1747 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1748 		    STbp->buffer_bytes < STbp->buffer_size) {
1749 			STp->dirty = 1;
1750 			/* Don't write a buffer that is not full enough. */
1751 			if (!async_write && count == 0)
1752 				break;
1753 		}
1754 
1755 	retry_write:
1756 		if (STp->block_size == 0)
1757 			blks = transfer = do_count;
1758 		else {
1759 			if (!STbp->do_dio)
1760 				blks = STbp->buffer_bytes;
1761 			else
1762 				blks = do_count;
1763 			blks /= STp->block_size;
1764 			transfer = blks * STp->block_size;
1765 		}
1766 		cmd[2] = blks >> 16;
1767 		cmd[3] = blks >> 8;
1768 		cmd[4] = blks;
1769 
1770 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1771 				   STp->device->request_queue->rq_timeout,
1772 				   MAX_WRITE_RETRIES, !async_write);
1773 		if (!SRpnt) {
1774 			retval = STbp->syscall_result;
1775 			goto out;
1776 		}
1777 		if (async_write && !STbp->syscall_result) {
1778 			STbp->writing = transfer;
1779 			STp->dirty = !(STbp->writing ==
1780 				       STbp->buffer_bytes);
1781 			SRpnt = NULL;  /* Prevent releasing this request! */
1782 			DEB( STp->write_pending = 1; )
1783 			break;
1784 		}
1785 
1786 		if (STbp->syscall_result != 0) {
1787 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1788 
1789 			DEBC_printk(STp, "Error on write:\n");
1790 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1791 				scode = cmdstatp->sense_hdr.sense_key;
1792 				if (cmdstatp->remainder_valid)
1793 					undone = (int)cmdstatp->uremainder64;
1794 				else if (STp->block_size == 0 &&
1795 					 scode == VOLUME_OVERFLOW)
1796 					undone = transfer;
1797 				else
1798 					undone = 0;
1799 				if (STp->block_size != 0)
1800 					undone *= STp->block_size;
1801 				if (undone <= do_count) {
1802 					/* Only data from this write is not written */
1803 					count += undone;
1804 					b_point -= undone;
1805 					do_count -= undone;
1806 					if (STp->block_size)
1807 						blks = (transfer - undone) / STp->block_size;
1808 					STps->eof = ST_EOM_OK;
1809 					/* Continue in fixed block mode if all written
1810 					   in this request but still something left to write
1811 					   (retval left to zero)
1812 					*/
1813 					if (STp->block_size == 0 ||
1814 					    undone > 0 || count == 0)
1815 						retval = (-ENOSPC); /* EOM within current request */
1816 					DEBC_printk(STp, "EOM with %d "
1817 						    "bytes unwritten.\n",
1818 						    (int)count);
1819 				} else {
1820 					/* EOT within data buffered earlier (possible only
1821 					   in fixed block mode without direct i/o) */
1822 					if (!retry_eot && !cmdstatp->deferred &&
1823 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1824 						move_buffer_data(STp->buffer, transfer - undone);
1825 						retry_eot = 1;
1826 						if (STps->drv_block >= 0) {
1827 							STps->drv_block += (transfer - undone) /
1828 								STp->block_size;
1829 						}
1830 						STps->eof = ST_EOM_OK;
1831 						DEBC_printk(STp, "Retry "
1832 							    "write of %d "
1833 							    "bytes at EOM.\n",
1834 							    STp->buffer->buffer_bytes);
1835 						goto retry_write;
1836 					}
1837 					else {
1838 						/* Either error within data buffered by driver or
1839 						   failed retry */
1840 						count -= do_count;
1841 						blks = do_count = 0;
1842 						STps->eof = ST_EOM_ERROR;
1843 						STps->drv_block = (-1); /* Too cautious? */
1844 						retval = (-EIO);	/* EOM for old data */
1845 						DEBC_printk(STp, "EOM with "
1846 							    "lost data.\n");
1847 					}
1848 				}
1849 			} else {
1850 				count += do_count;
1851 				STps->drv_block = (-1);		/* Too cautious? */
1852 				retval = STbp->syscall_result;
1853 			}
1854 
1855 		}
1856 
1857 		if (STps->drv_block >= 0) {
1858 			if (STp->block_size == 0)
1859 				STps->drv_block += (do_count > 0);
1860 			else
1861 				STps->drv_block += blks;
1862 		}
1863 
1864 		STbp->buffer_bytes = 0;
1865 		STp->dirty = 0;
1866 
1867 		if (retval || retry_eot) {
1868 			if (count < total)
1869 				retval = total - count;
1870 			goto out;
1871 		}
1872 	}
1873 
1874 	if (STps->eof == ST_EOD_1)
1875 		STps->eof = ST_EOM_OK;
1876 	else if (STps->eof != ST_EOM_OK)
1877 		STps->eof = ST_NOEOF;
1878 	retval = total - count;
1879 
1880  out:
1881 	if (SRpnt != NULL)
1882 		st_release_request(SRpnt);
1883 	release_buffering(STp, 0);
1884 	mutex_unlock(&STp->lock);
1885 
1886 	return retval;
1887 }
1888 
1889 /* Read data from the tape. Returns zero in the normal case, one if the
1890    eof status has changed, and the negative error code in case of a
1891    fatal error. Otherwise updates the buffer and the eof state.
1892 
1893    Does release user buffer mapping if it is set.
1894 */
1895 static long read_tape(struct scsi_tape *STp, long count,
1896 		      struct st_request ** aSRpnt)
1897 {
1898 	int transfer, blks, bytes;
1899 	unsigned char cmd[MAX_COMMAND_SIZE];
1900 	struct st_request *SRpnt;
1901 	struct st_modedef *STm;
1902 	struct st_partstat *STps;
1903 	struct st_buffer *STbp;
1904 	int retval = 0;
1905 
1906 	if (count == 0)
1907 		return 0;
1908 
1909 	STm = &(STp->modes[STp->current_mode]);
1910 	STps = &(STp->ps[STp->partition]);
1911 	if (STps->eof == ST_FM_HIT)
1912 		return 1;
1913 	STbp = STp->buffer;
1914 
1915 	if (STp->block_size == 0)
1916 		blks = bytes = count;
1917 	else {
1918 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1919 			blks = (STp->buffer)->buffer_blocks;
1920 			bytes = blks * STp->block_size;
1921 		} else {
1922 			bytes = count;
1923 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1924 				bytes = (STp->buffer)->buffer_size;
1925 			blks = bytes / STp->block_size;
1926 			bytes = blks * STp->block_size;
1927 		}
1928 	}
1929 
1930 	memset(cmd, 0, MAX_COMMAND_SIZE);
1931 	cmd[0] = READ_6;
1932 	cmd[1] = (STp->block_size != 0);
1933 	if (!cmd[1] && STp->sili)
1934 		cmd[1] |= 2;
1935 	cmd[2] = blks >> 16;
1936 	cmd[3] = blks >> 8;
1937 	cmd[4] = blks;
1938 
1939 	SRpnt = *aSRpnt;
1940 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1941 			   STp->device->request_queue->rq_timeout,
1942 			   MAX_RETRIES, 1);
1943 	release_buffering(STp, 1);
1944 	*aSRpnt = SRpnt;
1945 	if (!SRpnt)
1946 		return STbp->syscall_result;
1947 
1948 	STbp->read_pointer = 0;
1949 	STps->at_sm = 0;
1950 
1951 	/* Something to check */
1952 	if (STbp->syscall_result) {
1953 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1954 
1955 		retval = 1;
1956 		DEBC_printk(STp,
1957 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1958 			    SRpnt->sense[0], SRpnt->sense[1],
1959 			    SRpnt->sense[2], SRpnt->sense[3],
1960 			    SRpnt->sense[4], SRpnt->sense[5],
1961 			    SRpnt->sense[6], SRpnt->sense[7]);
1962 		if (cmdstatp->have_sense) {
1963 
1964 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1965 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1966 
1967 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1968 				/* Compute the residual count */
1969 				if (cmdstatp->remainder_valid)
1970 					transfer = (int)cmdstatp->uremainder64;
1971 				else
1972 					transfer = 0;
1973 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1974 					if (STp->block_size == 0)
1975 						transfer = bytes;
1976 					/* Some drives set ILI with MEDIUM ERROR */
1977 					cmdstatp->flags &= ~SENSE_ILI;
1978 				}
1979 
1980 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1981 					if (STp->block_size == 0 &&
1982 					    transfer < 0) {
1983 						st_printk(KERN_NOTICE, STp,
1984 							  "Failed to read %d "
1985 							  "byte block with %d "
1986 							  "byte transfer.\n",
1987 							  bytes - transfer,
1988 							  bytes);
1989 						if (STps->drv_block >= 0)
1990 							STps->drv_block += 1;
1991 						STbp->buffer_bytes = 0;
1992 						return (-ENOMEM);
1993 					} else if (STp->block_size == 0) {
1994 						STbp->buffer_bytes = bytes - transfer;
1995 					} else {
1996 						st_release_request(SRpnt);
1997 						SRpnt = *aSRpnt = NULL;
1998 						if (transfer == blks) {	/* We did not get anything, error */
1999 							st_printk(KERN_NOTICE, STp,
2000 								  "Incorrect "
2001 								  "block size.\n");
2002 							if (STps->drv_block >= 0)
2003 								STps->drv_block += blks - transfer + 1;
2004 							st_int_ioctl(STp, MTBSR, 1);
2005 							return (-EIO);
2006 						}
2007 						/* We have some data, deliver it */
2008 						STbp->buffer_bytes = (blks - transfer) *
2009 						    STp->block_size;
2010 						DEBC_printk(STp, "ILI but "
2011 							    "enough data "
2012 							    "received %ld "
2013 							    "%d.\n", count,
2014 							    STbp->buffer_bytes);
2015 						if (STps->drv_block >= 0)
2016 							STps->drv_block += 1;
2017 						if (st_int_ioctl(STp, MTBSR, 1))
2018 							return (-EIO);
2019 					}
2020 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2021 					if (STps->eof != ST_FM_HIT)
2022 						STps->eof = ST_FM_HIT;
2023 					else
2024 						STps->eof = ST_EOD_2;
2025 					if (STp->block_size == 0)
2026 						STbp->buffer_bytes = 0;
2027 					else
2028 						STbp->buffer_bytes =
2029 						    bytes - transfer * STp->block_size;
2030 					DEBC_printk(STp, "EOF detected (%d "
2031 						    "bytes read).\n",
2032 						    STbp->buffer_bytes);
2033 				} else if (cmdstatp->flags & SENSE_EOM) {
2034 					if (STps->eof == ST_FM)
2035 						STps->eof = ST_EOD_1;
2036 					else
2037 						STps->eof = ST_EOM_OK;
2038 					if (STp->block_size == 0)
2039 						STbp->buffer_bytes = bytes - transfer;
2040 					else
2041 						STbp->buffer_bytes =
2042 						    bytes - transfer * STp->block_size;
2043 
2044 					DEBC_printk(STp, "EOM detected (%d "
2045 						    "bytes read).\n",
2046 						    STbp->buffer_bytes);
2047 				}
2048 			}
2049 			/* end of EOF, EOM, ILI test */
2050 			else {	/* nonzero sense key */
2051 				DEBC_printk(STp, "Tape error while reading.\n");
2052 				STps->drv_block = (-1);
2053 				if (STps->eof == ST_FM &&
2054 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2055 					DEBC_printk(STp, "Zero returned for "
2056 						    "first BLANK CHECK "
2057 						    "after EOF.\n");
2058 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2059 				} else	/* Some other extended sense code */
2060 					retval = (-EIO);
2061 			}
2062 
2063 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2064 				STbp->buffer_bytes = 0;
2065 		}
2066 		/* End of extended sense test */
2067 		else {		/* Non-extended sense */
2068 			retval = STbp->syscall_result;
2069 		}
2070 
2071 	}
2072 	/* End of error handling */
2073 	else {			/* Read successful */
2074 		STbp->buffer_bytes = bytes;
2075 		if (STp->sili) /* In fixed block mode residual is always zero here */
2076 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2077 	}
2078 
2079 	if (STps->drv_block >= 0) {
2080 		if (STp->block_size == 0)
2081 			STps->drv_block++;
2082 		else
2083 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2084 	}
2085 	return retval;
2086 }
2087 
2088 
2089 /* Read command */
2090 static ssize_t
2091 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2092 {
2093 	ssize_t total;
2094 	ssize_t retval = 0;
2095 	ssize_t i, transfer;
2096 	int special, do_dio = 0;
2097 	struct st_request *SRpnt = NULL;
2098 	struct scsi_tape *STp = filp->private_data;
2099 	struct st_modedef *STm;
2100 	struct st_partstat *STps;
2101 	struct st_buffer *STbp = STp->buffer;
2102 
2103 	if (mutex_lock_interruptible(&STp->lock))
2104 		return -ERESTARTSYS;
2105 
2106 	retval = rw_checks(STp, filp, count);
2107 	if (retval || count == 0)
2108 		goto out;
2109 
2110 	STm = &(STp->modes[STp->current_mode]);
2111 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2112 		if (!STm->do_read_ahead) {
2113 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2114 			goto out;
2115 		}
2116 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2117 	}
2118 
2119 	STps = &(STp->ps[STp->partition]);
2120 	if (STps->rw == ST_WRITING) {
2121 		retval = flush_buffer(STp, 0);
2122 		if (retval)
2123 			goto out;
2124 		STps->rw = ST_READING;
2125 	}
2126 	DEB(
2127 	if (debugging && STps->eof != ST_NOEOF)
2128 		st_printk(ST_DEB_MSG, STp,
2129 			  "EOF/EOM flag up (%d). Bytes %d\n",
2130 			  STps->eof, STbp->buffer_bytes);
2131 	) /* end DEB */
2132 
2133 	retval = setup_buffering(STp, buf, count, 1);
2134 	if (retval)
2135 		goto out;
2136 	do_dio = STbp->do_dio;
2137 
2138 	if (STbp->buffer_bytes == 0 &&
2139 	    STps->eof >= ST_EOD_1) {
2140 		if (STps->eof < ST_EOD) {
2141 			STps->eof += 1;
2142 			retval = 0;
2143 			goto out;
2144 		}
2145 		retval = (-EIO);	/* EOM or Blank Check */
2146 		goto out;
2147 	}
2148 
2149 	if (do_dio) {
2150 		/* Check the buffer writability before any tape movement. Don't alter
2151 		   buffer data. */
2152 		if (copy_from_user(&i, buf, 1) != 0 ||
2153 		    copy_to_user(buf, &i, 1) != 0 ||
2154 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2155 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2156 			retval = (-EFAULT);
2157 			goto out;
2158 		}
2159 	}
2160 
2161 	STps->rw = ST_READING;
2162 
2163 
2164 	/* Loop until enough data in buffer or a special condition found */
2165 	for (total = 0, special = 0; total < count && !special;) {
2166 
2167 		/* Get new data if the buffer is empty */
2168 		if (STbp->buffer_bytes == 0) {
2169 			special = read_tape(STp, count - total, &SRpnt);
2170 			if (special < 0) {	/* No need to continue read */
2171 				retval = special;
2172 				goto out;
2173 			}
2174 		}
2175 
2176 		/* Move the data from driver buffer to user buffer */
2177 		if (STbp->buffer_bytes > 0) {
2178 			DEB(
2179 			if (debugging && STps->eof != ST_NOEOF)
2180 				st_printk(ST_DEB_MSG, STp,
2181 					  "EOF up (%d). Left %d, needed %d.\n",
2182 					  STps->eof, STbp->buffer_bytes,
2183 					  (int)(count - total));
2184 			) /* end DEB */
2185 			transfer = STbp->buffer_bytes < count - total ?
2186 			    STbp->buffer_bytes : count - total;
2187 			if (!do_dio) {
2188 				i = from_buffer(STbp, buf, transfer);
2189 				if (i) {
2190 					retval = i;
2191 					goto out;
2192 				}
2193 			}
2194 			buf += transfer;
2195 			total += transfer;
2196 		}
2197 
2198 		if (STp->block_size == 0)
2199 			break;	/* Read only one variable length block */
2200 
2201 	}			/* for (total = 0, special = 0;
2202                                    total < count && !special; ) */
2203 
2204 	/* Change the eof state if no data from tape or buffer */
2205 	if (total == 0) {
2206 		if (STps->eof == ST_FM_HIT) {
2207 			STps->eof = ST_FM;
2208 			STps->drv_block = 0;
2209 			if (STps->drv_file >= 0)
2210 				STps->drv_file++;
2211 		} else if (STps->eof == ST_EOD_1) {
2212 			STps->eof = ST_EOD_2;
2213 			STps->drv_block = 0;
2214 			if (STps->drv_file >= 0)
2215 				STps->drv_file++;
2216 		} else if (STps->eof == ST_EOD_2)
2217 			STps->eof = ST_EOD;
2218 	} else if (STps->eof == ST_FM)
2219 		STps->eof = ST_NOEOF;
2220 	retval = total;
2221 
2222  out:
2223 	if (SRpnt != NULL) {
2224 		st_release_request(SRpnt);
2225 		SRpnt = NULL;
2226 	}
2227 	if (do_dio) {
2228 		release_buffering(STp, 1);
2229 		STbp->buffer_bytes = 0;
2230 	}
2231 	mutex_unlock(&STp->lock);
2232 
2233 	return retval;
2234 }
2235 
2236 
2237 
2238 DEB(
2239 /* Set the driver options */
2240 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2241 {
2242 	if (debugging) {
2243 		st_printk(KERN_INFO, STp,
2244 			  "Mode %d options: buffer writes: %d, "
2245 			  "async writes: %d, read ahead: %d\n",
2246 			  STp->current_mode, STm->do_buffer_writes,
2247 			  STm->do_async_writes, STm->do_read_ahead);
2248 		st_printk(KERN_INFO, STp,
2249 			  "    can bsr: %d, two FMs: %d, "
2250 			  "fast mteom: %d, auto lock: %d,\n",
2251 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2252 			  STp->do_auto_lock);
2253 		st_printk(KERN_INFO, STp,
2254 			  "    defs for wr: %d, no block limits: %d, "
2255 			  "partitions: %d, s2 log: %d\n",
2256 			  STm->defaults_for_writes, STp->omit_blklims,
2257 			  STp->can_partitions, STp->scsi2_logical);
2258 		st_printk(KERN_INFO, STp,
2259 			  "    sysv: %d nowait: %d sili: %d "
2260 			  "nowait_filemark: %d\n",
2261 			  STm->sysv, STp->immediate, STp->sili,
2262 			  STp->immediate_filemark);
2263 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2264 	}
2265 }
2266 	)
2267 
2268 
2269 static int st_set_options(struct scsi_tape *STp, long options)
2270 {
2271 	int value;
2272 	long code;
2273 	struct st_modedef *STm;
2274 	struct cdev *cd0, *cd1;
2275 	struct device *d0, *d1;
2276 
2277 	STm = &(STp->modes[STp->current_mode]);
2278 	if (!STm->defined) {
2279 		cd0 = STm->cdevs[0];
2280 		cd1 = STm->cdevs[1];
2281 		d0  = STm->devs[0];
2282 		d1  = STm->devs[1];
2283 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2284 		STm->cdevs[0] = cd0;
2285 		STm->cdevs[1] = cd1;
2286 		STm->devs[0]  = d0;
2287 		STm->devs[1]  = d1;
2288 		modes_defined = 1;
2289 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2290 			    STp->current_mode);
2291 	}
2292 
2293 	code = options & MT_ST_OPTIONS;
2294 	if (code == MT_ST_BOOLEANS) {
2295 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2296 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2297 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2298 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2299 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2300 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2301 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2302 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2303 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2304 		if ((STp->device)->scsi_level >= SCSI_2)
2305 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2306 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2307 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2308 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2309 		STm->sysv = (options & MT_ST_SYSV) != 0;
2310 		STp->sili = (options & MT_ST_SILI) != 0;
2311 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2312 		     st_log_options(STp, STm); )
2313 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2314 		value = (code == MT_ST_SETBOOLEANS);
2315 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2316 			STm->do_buffer_writes = value;
2317 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2318 			STm->do_async_writes = value;
2319 		if ((options & MT_ST_DEF_WRITES) != 0)
2320 			STm->defaults_for_writes = value;
2321 		if ((options & MT_ST_READ_AHEAD) != 0)
2322 			STm->do_read_ahead = value;
2323 		if ((options & MT_ST_TWO_FM) != 0)
2324 			STp->two_fm = value;
2325 		if ((options & MT_ST_FAST_MTEOM) != 0)
2326 			STp->fast_mteom = value;
2327 		if ((options & MT_ST_AUTO_LOCK) != 0)
2328 			STp->do_auto_lock = value;
2329 		if ((options & MT_ST_CAN_BSR) != 0)
2330 			STp->can_bsr = value;
2331 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2332 			STp->omit_blklims = value;
2333 		if ((STp->device)->scsi_level >= SCSI_2 &&
2334 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2335 			STp->can_partitions = value;
2336 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2337 			STp->scsi2_logical = value;
2338 		if ((options & MT_ST_NOWAIT) != 0)
2339 			STp->immediate = value;
2340 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2341 			STp->immediate_filemark = value;
2342 		if ((options & MT_ST_SYSV) != 0)
2343 			STm->sysv = value;
2344 		if ((options & MT_ST_SILI) != 0)
2345 			STp->sili = value;
2346 		DEB(
2347 		if ((options & MT_ST_DEBUGGING) != 0)
2348 			debugging = value;
2349 			st_log_options(STp, STm); )
2350 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2351 		/* Retained for compatibility */
2352 	} else if (code == MT_ST_DEF_BLKSIZE) {
2353 		value = (options & ~MT_ST_OPTIONS);
2354 		if (value == ~MT_ST_OPTIONS) {
2355 			STm->default_blksize = (-1);
2356 			DEBC_printk(STp, "Default block size disabled.\n");
2357 		} else {
2358 			STm->default_blksize = value;
2359 			DEBC_printk(STp,"Default block size set to "
2360 				    "%d bytes.\n", STm->default_blksize);
2361 			if (STp->ready == ST_READY) {
2362 				STp->blksize_changed = 0;
2363 				set_mode_densblk(STp, STm);
2364 			}
2365 		}
2366 	} else if (code == MT_ST_TIMEOUTS) {
2367 		value = (options & ~MT_ST_OPTIONS);
2368 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2369 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2370 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2371 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2372 		} else {
2373 			blk_queue_rq_timeout(STp->device->request_queue,
2374 					     value * HZ);
2375 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2376 				    value);
2377 		}
2378 	} else if (code == MT_ST_SET_CLN) {
2379 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2380 		if (value != 0 &&
2381 			(value < EXTENDED_SENSE_START ||
2382 				value >= SCSI_SENSE_BUFFERSIZE))
2383 			return (-EINVAL);
2384 		STp->cln_mode = value;
2385 		STp->cln_sense_mask = (options >> 8) & 0xff;
2386 		STp->cln_sense_value = (options >> 16) & 0xff;
2387 		st_printk(KERN_INFO, STp,
2388 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2389 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2390 	} else if (code == MT_ST_DEF_OPTIONS) {
2391 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2392 		value = (options & MT_ST_CLEAR_DEFAULT);
2393 		if (code == MT_ST_DEF_DENSITY) {
2394 			if (value == MT_ST_CLEAR_DEFAULT) {
2395 				STm->default_density = (-1);
2396 				DEBC_printk(STp,
2397 					    "Density default disabled.\n");
2398 			} else {
2399 				STm->default_density = value & 0xff;
2400 				DEBC_printk(STp, "Density default set to %x\n",
2401 					    STm->default_density);
2402 				if (STp->ready == ST_READY) {
2403 					STp->density_changed = 0;
2404 					set_mode_densblk(STp, STm);
2405 				}
2406 			}
2407 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2408 			if (value == MT_ST_CLEAR_DEFAULT) {
2409 				STp->default_drvbuffer = 0xff;
2410 				DEBC_printk(STp,
2411 					    "Drive buffer default disabled.\n");
2412 			} else {
2413 				STp->default_drvbuffer = value & 7;
2414 				DEBC_printk(STp,
2415 					    "Drive buffer default set to %x\n",
2416 					    STp->default_drvbuffer);
2417 				if (STp->ready == ST_READY)
2418 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2419 			}
2420 		} else if (code == MT_ST_DEF_COMPRESSION) {
2421 			if (value == MT_ST_CLEAR_DEFAULT) {
2422 				STm->default_compression = ST_DONT_TOUCH;
2423 				DEBC_printk(STp,
2424 					    "Compression default disabled.\n");
2425 			} else {
2426 				if ((value & 0xff00) != 0) {
2427 					STp->c_algo = (value & 0xff00) >> 8;
2428 					DEBC_printk(STp, "Compression "
2429 						    "algorithm set to 0x%x.\n",
2430 						    STp->c_algo);
2431 				}
2432 				if ((value & 0xff) != 0xff) {
2433 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2434 					DEBC_printk(STp, "Compression default "
2435 						    "set to %x\n",
2436 						    (value & 1));
2437 					if (STp->ready == ST_READY) {
2438 						STp->compression_changed = 0;
2439 						st_compression(STp, (STm->default_compression == ST_YES));
2440 					}
2441 				}
2442 			}
2443 		}
2444 	} else
2445 		return (-EIO);
2446 
2447 	return 0;
2448 }
2449 
2450 #define MODE_HEADER_LENGTH  4
2451 
2452 /* Mode header and page byte offsets */
2453 #define MH_OFF_DATA_LENGTH     0
2454 #define MH_OFF_MEDIUM_TYPE     1
2455 #define MH_OFF_DEV_SPECIFIC    2
2456 #define MH_OFF_BDESCS_LENGTH   3
2457 #define MP_OFF_PAGE_NBR        0
2458 #define MP_OFF_PAGE_LENGTH     1
2459 
2460 /* Mode header and page bit masks */
2461 #define MH_BIT_WP              0x80
2462 #define MP_MSK_PAGE_NBR        0x3f
2463 
2464 /* Don't return block descriptors */
2465 #define MODE_SENSE_OMIT_BDESCS 0x08
2466 
2467 #define MODE_SELECT_PAGE_FORMAT 0x10
2468 
2469 /* Read a mode page into the tape buffer. The block descriptors are included
2470    if incl_block_descs is true. The page control is ored to the page number
2471    parameter, if necessary. */
2472 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2473 {
2474 	unsigned char cmd[MAX_COMMAND_SIZE];
2475 	struct st_request *SRpnt;
2476 
2477 	memset(cmd, 0, MAX_COMMAND_SIZE);
2478 	cmd[0] = MODE_SENSE;
2479 	if (omit_block_descs)
2480 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2481 	cmd[2] = page;
2482 	cmd[4] = 255;
2483 
2484 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2485 			   STp->device->request_queue->rq_timeout, 0, 1);
2486 	if (SRpnt == NULL)
2487 		return (STp->buffer)->syscall_result;
2488 
2489 	st_release_request(SRpnt);
2490 
2491 	return STp->buffer->syscall_result;
2492 }
2493 
2494 
2495 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2496    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2497 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2498 {
2499 	int pgo;
2500 	unsigned char cmd[MAX_COMMAND_SIZE];
2501 	struct st_request *SRpnt;
2502 	int timeout;
2503 
2504 	memset(cmd, 0, MAX_COMMAND_SIZE);
2505 	cmd[0] = MODE_SELECT;
2506 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2507 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2508 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2509 
2510 	/* Clear reserved fields */
2511 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2512 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2513 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2514 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2515 
2516 	timeout = slow ?
2517 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2518 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2519 			   timeout, 0, 1);
2520 	if (SRpnt == NULL)
2521 		return (STp->buffer)->syscall_result;
2522 
2523 	st_release_request(SRpnt);
2524 
2525 	return STp->buffer->syscall_result;
2526 }
2527 
2528 
2529 #define COMPRESSION_PAGE        0x0f
2530 #define COMPRESSION_PAGE_LENGTH 16
2531 
2532 #define CP_OFF_DCE_DCC          2
2533 #define CP_OFF_C_ALGO           7
2534 
2535 #define DCE_MASK  0x80
2536 #define DCC_MASK  0x40
2537 #define RED_MASK  0x60
2538 
2539 
2540 /* Control the compression with mode page 15. Algorithm not changed if zero.
2541 
2542    The block descriptors are read and written because Sony SDT-7000 does not
2543    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2544    Including block descriptors should not cause any harm to other drives. */
2545 
2546 static int st_compression(struct scsi_tape * STp, int state)
2547 {
2548 	int retval;
2549 	int mpoffs;  /* Offset to mode page start */
2550 	unsigned char *b_data = (STp->buffer)->b_data;
2551 
2552 	if (STp->ready != ST_READY)
2553 		return (-EIO);
2554 
2555 	/* Read the current page contents */
2556 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2557 	if (retval) {
2558 		DEBC_printk(STp, "Compression mode page not supported.\n");
2559 		return (-EIO);
2560 	}
2561 
2562 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2563 	DEBC_printk(STp, "Compression state is %d.\n",
2564 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2565 
2566 	/* Check if compression can be changed */
2567 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2568 		DEBC_printk(STp, "Compression not supported.\n");
2569 		return (-EIO);
2570 	}
2571 
2572 	/* Do the change */
2573 	if (state) {
2574 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2575 		if (STp->c_algo != 0)
2576 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2577 	}
2578 	else {
2579 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2580 		if (STp->c_algo != 0)
2581 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2582 	}
2583 
2584 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2585 	if (retval) {
2586 		DEBC_printk(STp, "Compression change failed.\n");
2587 		return (-EIO);
2588 	}
2589 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2590 
2591 	STp->compression_changed = 1;
2592 	return 0;
2593 }
2594 
2595 
2596 /* Process the load and unload commands (does unload if the load code is zero) */
2597 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2598 {
2599 	int retval = (-EIO), timeout;
2600 	unsigned char cmd[MAX_COMMAND_SIZE];
2601 	struct st_partstat *STps;
2602 	struct st_request *SRpnt;
2603 
2604 	if (STp->ready != ST_READY && !load_code) {
2605 		if (STp->ready == ST_NO_TAPE)
2606 			return (-ENOMEDIUM);
2607 		else
2608 			return (-EIO);
2609 	}
2610 
2611 	memset(cmd, 0, MAX_COMMAND_SIZE);
2612 	cmd[0] = START_STOP;
2613 	if (load_code)
2614 		cmd[4] |= 1;
2615 	/*
2616 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2617 	 */
2618 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2619 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2620 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2621 			    (cmd[4]) ? "" : "un",
2622 			    load_code - MT_ST_HPLOADER_OFFSET);
2623 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2624 	}
2625 	if (STp->immediate) {
2626 		cmd[1] = 1;	/* Don't wait for completion */
2627 		timeout = STp->device->request_queue->rq_timeout;
2628 	}
2629 	else
2630 		timeout = STp->long_timeout;
2631 
2632 	DEBC(
2633 		if (!load_code)
2634 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2635 		else
2636 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2637 		);
2638 
2639 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2640 			   timeout, MAX_RETRIES, 1);
2641 	if (!SRpnt)
2642 		return (STp->buffer)->syscall_result;
2643 
2644 	retval = (STp->buffer)->syscall_result;
2645 	st_release_request(SRpnt);
2646 
2647 	if (!retval) {	/* SCSI command successful */
2648 
2649 		if (!load_code) {
2650 			STp->rew_at_close = 0;
2651 			STp->ready = ST_NO_TAPE;
2652 		}
2653 		else {
2654 			STp->rew_at_close = STp->autorew_dev;
2655 			retval = check_tape(STp, filp);
2656 			if (retval > 0)
2657 				retval = 0;
2658 		}
2659 	}
2660 	else {
2661 		STps = &(STp->ps[STp->partition]);
2662 		STps->drv_file = STps->drv_block = (-1);
2663 	}
2664 
2665 	return retval;
2666 }
2667 
2668 #if DEBUG
2669 #define ST_DEB_FORWARD  0
2670 #define ST_DEB_BACKWARD 1
2671 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2672 {
2673 	s32 sc;
2674 
2675 	if (!debugging)
2676 		return;
2677 
2678 	sc = sign_extend32(get_unaligned_be24(&cmd[2]), 23);
2679 	if (direction)
2680 		sc = -sc;
2681 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2682 		  direction ? "backward" : "forward", sc, units);
2683 }
2684 #else
2685 #define ST_DEB_FORWARD  0
2686 #define ST_DEB_BACKWARD 1
2687 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2688 #endif
2689 
2690 
2691 /* Internal ioctl function */
2692 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2693 {
2694 	int timeout;
2695 	long ltmp;
2696 	int ioctl_result;
2697 	int chg_eof = 1;
2698 	unsigned char cmd[MAX_COMMAND_SIZE];
2699 	struct st_request *SRpnt;
2700 	struct st_partstat *STps;
2701 	int fileno, blkno, at_sm, undone;
2702 	int datalen = 0, direction = DMA_NONE;
2703 
2704 	WARN_ON(STp->buffer->do_dio != 0);
2705 	if (STp->ready != ST_READY) {
2706 		if (STp->ready == ST_NO_TAPE)
2707 			return (-ENOMEDIUM);
2708 		else
2709 			return (-EIO);
2710 	}
2711 	timeout = STp->long_timeout;
2712 	STps = &(STp->ps[STp->partition]);
2713 	fileno = STps->drv_file;
2714 	blkno = STps->drv_block;
2715 	at_sm = STps->at_sm;
2716 
2717 	memset(cmd, 0, MAX_COMMAND_SIZE);
2718 	switch (cmd_in) {
2719 	case MTFSFM:
2720 		chg_eof = 0;	/* Changed from the FSF after this */
2721 		fallthrough;
2722 	case MTFSF:
2723 		cmd[0] = SPACE;
2724 		cmd[1] = 0x01;	/* Space FileMarks */
2725 		cmd[2] = (arg >> 16);
2726 		cmd[3] = (arg >> 8);
2727 		cmd[4] = arg;
2728 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2729 		if (fileno >= 0)
2730 			fileno += arg;
2731 		blkno = 0;
2732 		at_sm &= (arg == 0);
2733 		break;
2734 	case MTBSFM:
2735 		chg_eof = 0;	/* Changed from the FSF after this */
2736 		fallthrough;
2737 	case MTBSF:
2738 		cmd[0] = SPACE;
2739 		cmd[1] = 0x01;	/* Space FileMarks */
2740 		ltmp = (-arg);
2741 		cmd[2] = (ltmp >> 16);
2742 		cmd[3] = (ltmp >> 8);
2743 		cmd[4] = ltmp;
2744 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2745 		if (fileno >= 0)
2746 			fileno -= arg;
2747 		blkno = (-1);	/* We can't know the block number */
2748 		at_sm &= (arg == 0);
2749 		break;
2750 	case MTFSR:
2751 		cmd[0] = SPACE;
2752 		cmd[1] = 0x00;	/* Space Blocks */
2753 		cmd[2] = (arg >> 16);
2754 		cmd[3] = (arg >> 8);
2755 		cmd[4] = arg;
2756 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2757 		if (blkno >= 0)
2758 			blkno += arg;
2759 		at_sm &= (arg == 0);
2760 		break;
2761 	case MTBSR:
2762 		cmd[0] = SPACE;
2763 		cmd[1] = 0x00;	/* Space Blocks */
2764 		ltmp = (-arg);
2765 		cmd[2] = (ltmp >> 16);
2766 		cmd[3] = (ltmp >> 8);
2767 		cmd[4] = ltmp;
2768 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2769 		if (blkno >= 0)
2770 			blkno -= arg;
2771 		at_sm &= (arg == 0);
2772 		break;
2773 	case MTFSS:
2774 		cmd[0] = SPACE;
2775 		cmd[1] = 0x04;	/* Space Setmarks */
2776 		cmd[2] = (arg >> 16);
2777 		cmd[3] = (arg >> 8);
2778 		cmd[4] = arg;
2779 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2780 		if (arg != 0) {
2781 			blkno = fileno = (-1);
2782 			at_sm = 1;
2783 		}
2784 		break;
2785 	case MTBSS:
2786 		cmd[0] = SPACE;
2787 		cmd[1] = 0x04;	/* Space Setmarks */
2788 		ltmp = (-arg);
2789 		cmd[2] = (ltmp >> 16);
2790 		cmd[3] = (ltmp >> 8);
2791 		cmd[4] = ltmp;
2792 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2793 		if (arg != 0) {
2794 			blkno = fileno = (-1);
2795 			at_sm = 1;
2796 		}
2797 		break;
2798 	case MTWEOF:
2799 	case MTWEOFI:
2800 	case MTWSM:
2801 		if (STp->write_prot)
2802 			return (-EACCES);
2803 		cmd[0] = WRITE_FILEMARKS;
2804 		if (cmd_in == MTWSM)
2805 			cmd[1] = 2;
2806 		if (cmd_in == MTWEOFI ||
2807 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2808 			cmd[1] |= 1;
2809 		cmd[2] = (arg >> 16);
2810 		cmd[3] = (arg >> 8);
2811 		cmd[4] = arg;
2812 		timeout = STp->device->request_queue->rq_timeout;
2813 		DEBC(
2814 			if (cmd_in != MTWSM)
2815 				st_printk(ST_DEB_MSG, STp,
2816 					  "Writing %d filemarks.\n",
2817 					  cmd[2] * 65536 +
2818 					  cmd[3] * 256 +
2819 					  cmd[4]);
2820 			else
2821 				st_printk(ST_DEB_MSG, STp,
2822 					  "Writing %d setmarks.\n",
2823 					  cmd[2] * 65536 +
2824 					  cmd[3] * 256 +
2825 					  cmd[4]);
2826 		)
2827 		if (fileno >= 0)
2828 			fileno += arg;
2829 		blkno = 0;
2830 		at_sm = (cmd_in == MTWSM);
2831 		break;
2832 	case MTREW:
2833 		cmd[0] = REZERO_UNIT;
2834 		if (STp->immediate) {
2835 			cmd[1] = 1;	/* Don't wait for completion */
2836 			timeout = STp->device->request_queue->rq_timeout;
2837 		}
2838 		DEBC_printk(STp, "Rewinding tape.\n");
2839 		fileno = blkno = at_sm = 0;
2840 		break;
2841 	case MTNOP:
2842 		DEBC_printk(STp, "No op on tape.\n");
2843 		return 0;	/* Should do something ? */
2844 	case MTRETEN:
2845 		cmd[0] = START_STOP;
2846 		if (STp->immediate) {
2847 			cmd[1] = 1;	/* Don't wait for completion */
2848 			timeout = STp->device->request_queue->rq_timeout;
2849 		}
2850 		cmd[4] = 3;
2851 		DEBC_printk(STp, "Retensioning tape.\n");
2852 		fileno = blkno = at_sm = 0;
2853 		break;
2854 	case MTEOM:
2855 		if (!STp->fast_mteom) {
2856 			/* space to the end of tape */
2857 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2858 			fileno = STps->drv_file;
2859 			if (STps->eof >= ST_EOD_1)
2860 				return 0;
2861 			/* The next lines would hide the number of spaced FileMarks
2862 			   That's why I inserted the previous lines. I had no luck
2863 			   with detecting EOM with FSF, so we go now to EOM.
2864 			   Joerg Weule */
2865 		} else
2866 			fileno = (-1);
2867 		cmd[0] = SPACE;
2868 		cmd[1] = 3;
2869 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2870 		blkno = -1;
2871 		at_sm = 0;
2872 		break;
2873 	case MTERASE:
2874 		if (STp->write_prot)
2875 			return (-EACCES);
2876 		cmd[0] = ERASE;
2877 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2878 		if (STp->immediate) {
2879 			cmd[1] |= 2;	/* Don't wait for completion */
2880 			timeout = STp->device->request_queue->rq_timeout;
2881 		}
2882 		else
2883 			timeout = STp->long_timeout * 8;
2884 
2885 		DEBC_printk(STp, "Erasing tape.\n");
2886 		fileno = blkno = at_sm = 0;
2887 		break;
2888 	case MTSETBLK:		/* Set block length */
2889 	case MTSETDENSITY:	/* Set tape density */
2890 	case MTSETDRVBUFFER:	/* Set drive buffering */
2891 	case SET_DENS_AND_BLK:	/* Set density and block size */
2892 		chg_eof = 0;
2893 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2894 			return (-EIO);	/* Not allowed if data in buffer */
2895 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2896 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2897 		    STp->max_block > 0 &&
2898 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2899 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2900 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2901 			return (-EINVAL);
2902 		}
2903 		cmd[0] = MODE_SELECT;
2904 		if ((STp->use_pf & USE_PF))
2905 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2906 		cmd[4] = datalen = 12;
2907 		direction = DMA_TO_DEVICE;
2908 
2909 		memset((STp->buffer)->b_data, 0, 12);
2910 		if (cmd_in == MTSETDRVBUFFER)
2911 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2912 		else
2913 			(STp->buffer)->b_data[2] =
2914 			    STp->drv_buffer << 4;
2915 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2916 		if (cmd_in == MTSETDENSITY) {
2917 			(STp->buffer)->b_data[4] = arg;
2918 			STp->density_changed = 1;	/* At least we tried ;-) */
2919 		} else if (cmd_in == SET_DENS_AND_BLK)
2920 			(STp->buffer)->b_data[4] = arg >> 24;
2921 		else
2922 			(STp->buffer)->b_data[4] = STp->density;
2923 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2924 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2925 			if (cmd_in == MTSETBLK)
2926 				STp->blksize_changed = 1; /* At least we tried ;-) */
2927 		} else
2928 			ltmp = STp->block_size;
2929 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2930 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2931 		(STp->buffer)->b_data[11] = ltmp;
2932 		timeout = STp->device->request_queue->rq_timeout;
2933 		DEBC(
2934 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2935 				st_printk(ST_DEB_MSG, STp,
2936 					  "Setting block size to %d bytes.\n",
2937 					  (STp->buffer)->b_data[9] * 65536 +
2938 					  (STp->buffer)->b_data[10] * 256 +
2939 					  (STp->buffer)->b_data[11]);
2940 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2941 				st_printk(ST_DEB_MSG, STp,
2942 					  "Setting density code to %x.\n",
2943 					  (STp->buffer)->b_data[4]);
2944 			if (cmd_in == MTSETDRVBUFFER)
2945 				st_printk(ST_DEB_MSG, STp,
2946 					  "Setting drive buffer code to %d.\n",
2947 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2948 		)
2949 		break;
2950 	default:
2951 		return (-ENOSYS);
2952 	}
2953 
2954 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2955 			   timeout, MAX_RETRIES, 1);
2956 	if (!SRpnt)
2957 		return (STp->buffer)->syscall_result;
2958 
2959 	ioctl_result = (STp->buffer)->syscall_result;
2960 
2961 	if (!ioctl_result) {	/* SCSI command successful */
2962 		st_release_request(SRpnt);
2963 		SRpnt = NULL;
2964 		STps->drv_block = blkno;
2965 		STps->drv_file = fileno;
2966 		STps->at_sm = at_sm;
2967 
2968 		if (cmd_in == MTBSFM)
2969 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2970 		else if (cmd_in == MTFSFM)
2971 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2972 
2973 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2974 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2975 			if (STp->block_size != 0) {
2976 				(STp->buffer)->buffer_blocks =
2977 				    (STp->buffer)->buffer_size / STp->block_size;
2978 			}
2979 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2980 			if (cmd_in == SET_DENS_AND_BLK)
2981 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2982 		} else if (cmd_in == MTSETDRVBUFFER)
2983 			STp->drv_buffer = (arg & 7);
2984 		else if (cmd_in == MTSETDENSITY)
2985 			STp->density = arg;
2986 
2987 		if (cmd_in == MTEOM)
2988 			STps->eof = ST_EOD;
2989 		else if (cmd_in == MTFSF)
2990 			STps->eof = ST_FM;
2991 		else if (chg_eof)
2992 			STps->eof = ST_NOEOF;
2993 
2994 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
2995 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
2996 	} else { /* SCSI command was not completely successful. Don't return
2997                     from this block without releasing the SCSI command block! */
2998 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
2999 
3000 		if (cmdstatp->flags & SENSE_EOM) {
3001 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3002 			    cmd_in != MTBSR && cmd_in != MTBSS)
3003 				STps->eof = ST_EOM_OK;
3004 			STps->drv_block = 0;
3005 		}
3006 
3007 		if (cmdstatp->remainder_valid)
3008 			undone = (int)cmdstatp->uremainder64;
3009 		else
3010 			undone = 0;
3011 
3012 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3013 		    cmdstatp->have_sense &&
3014 		    (cmdstatp->flags & SENSE_EOM)) {
3015 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3016 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3017 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3018 				STps->eof = ST_NOEOF;
3019 			} else {  /* Writing EOF(s) failed */
3020 				if (fileno >= 0)
3021 					fileno -= undone;
3022 				if (undone < arg)
3023 					STps->eof = ST_NOEOF;
3024 			}
3025 			STps->drv_file = fileno;
3026 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3027 			if (fileno >= 0)
3028 				STps->drv_file = fileno - undone;
3029 			else
3030 				STps->drv_file = fileno;
3031 			STps->drv_block = -1;
3032 			STps->eof = ST_NOEOF;
3033 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3034 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3035 				undone = (-undone);
3036 			if (STps->drv_file >= 0)
3037 				STps->drv_file = fileno + undone;
3038 			STps->drv_block = 0;
3039 			STps->eof = ST_NOEOF;
3040 		} else if (cmd_in == MTFSR) {
3041 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3042 				if (STps->drv_file >= 0)
3043 					STps->drv_file++;
3044 				STps->drv_block = 0;
3045 				STps->eof = ST_FM;
3046 			} else {
3047 				if (blkno >= undone)
3048 					STps->drv_block = blkno - undone;
3049 				else
3050 					STps->drv_block = (-1);
3051 				STps->eof = ST_NOEOF;
3052 			}
3053 		} else if (cmd_in == MTBSR) {
3054 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3055 				STps->drv_file--;
3056 				STps->drv_block = (-1);
3057 			} else {
3058 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3059 					undone = (-undone);
3060 				if (STps->drv_block >= 0)
3061 					STps->drv_block = blkno + undone;
3062 			}
3063 			STps->eof = ST_NOEOF;
3064 		} else if (cmd_in == MTEOM) {
3065 			STps->drv_file = (-1);
3066 			STps->drv_block = (-1);
3067 			STps->eof = ST_EOD;
3068 		} else if (cmd_in == MTSETBLK ||
3069 			   cmd_in == MTSETDENSITY ||
3070 			   cmd_in == MTSETDRVBUFFER ||
3071 			   cmd_in == SET_DENS_AND_BLK) {
3072 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3073 			    !(STp->use_pf & PF_TESTED)) {
3074 				/* Try the other possible state of Page Format if not
3075 				   already tried */
3076 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3077 				st_release_request(SRpnt);
3078 				SRpnt = NULL;
3079 				return st_int_ioctl(STp, cmd_in, arg);
3080 			}
3081 		} else if (chg_eof)
3082 			STps->eof = ST_NOEOF;
3083 
3084 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3085 			STps->eof = ST_EOD;
3086 
3087 		st_release_request(SRpnt);
3088 		SRpnt = NULL;
3089 	}
3090 
3091 	return ioctl_result;
3092 }
3093 
3094 
3095 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3096    structure. */
3097 
3098 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3099 			int logical)
3100 {
3101 	int result;
3102 	unsigned char scmd[MAX_COMMAND_SIZE];
3103 	struct st_request *SRpnt;
3104 
3105 	if (STp->ready != ST_READY)
3106 		return (-EIO);
3107 
3108 	memset(scmd, 0, MAX_COMMAND_SIZE);
3109 	if ((STp->device)->scsi_level < SCSI_2) {
3110 		scmd[0] = QFA_REQUEST_BLOCK;
3111 		scmd[4] = 3;
3112 	} else {
3113 		scmd[0] = READ_POSITION;
3114 		if (!logical && !STp->scsi2_logical)
3115 			scmd[1] = 1;
3116 	}
3117 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3118 			   STp->device->request_queue->rq_timeout,
3119 			   MAX_READY_RETRIES, 1);
3120 	if (!SRpnt)
3121 		return (STp->buffer)->syscall_result;
3122 
3123 	if ((STp->buffer)->syscall_result != 0 ||
3124 	    (STp->device->scsi_level >= SCSI_2 &&
3125 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3126 		*block = *partition = 0;
3127 		DEBC_printk(STp, " Can't read tape position.\n");
3128 		result = (-EIO);
3129 	} else {
3130 		result = 0;
3131 		if ((STp->device)->scsi_level < SCSI_2) {
3132 			*block = ((STp->buffer)->b_data[0] << 16)
3133 			    + ((STp->buffer)->b_data[1] << 8)
3134 			    + (STp->buffer)->b_data[2];
3135 			*partition = 0;
3136 		} else {
3137 			*block = ((STp->buffer)->b_data[4] << 24)
3138 			    + ((STp->buffer)->b_data[5] << 16)
3139 			    + ((STp->buffer)->b_data[6] << 8)
3140 			    + (STp->buffer)->b_data[7];
3141 			*partition = (STp->buffer)->b_data[1];
3142 			if (((STp->buffer)->b_data[0] & 0x80) &&
3143 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3144 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3145 		}
3146 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3147 			    *block, *partition);
3148 	}
3149 	st_release_request(SRpnt);
3150 	SRpnt = NULL;
3151 
3152 	return result;
3153 }
3154 
3155 
3156 /* Set the tape block and partition. Negative partition means that only the
3157    block should be set in vendor specific way. */
3158 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3159 			int logical)
3160 {
3161 	struct st_partstat *STps;
3162 	int result, p;
3163 	unsigned int blk;
3164 	int timeout;
3165 	unsigned char scmd[MAX_COMMAND_SIZE];
3166 	struct st_request *SRpnt;
3167 
3168 	if (STp->ready != ST_READY)
3169 		return (-EIO);
3170 	timeout = STp->long_timeout;
3171 	STps = &(STp->ps[STp->partition]);
3172 
3173 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3174 		    block, partition);
3175 	DEB(if (partition < 0)
3176 		return (-EIO); )
3177 
3178 	/* Update the location at the partition we are leaving */
3179 	if ((!STp->can_partitions && partition != 0) ||
3180 	    partition >= ST_NBR_PARTITIONS)
3181 		return (-EINVAL);
3182 	if (partition != STp->partition) {
3183 		if (get_location(STp, &blk, &p, 1))
3184 			STps->last_block_valid = 0;
3185 		else {
3186 			STps->last_block_valid = 1;
3187 			STps->last_block_visited = blk;
3188 			DEBC_printk(STp, "Visited block %d for "
3189 				    "partition %d saved.\n",
3190 				    blk, STp->partition);
3191 		}
3192 	}
3193 
3194 	memset(scmd, 0, MAX_COMMAND_SIZE);
3195 	if ((STp->device)->scsi_level < SCSI_2) {
3196 		scmd[0] = QFA_SEEK_BLOCK;
3197 		scmd[2] = (block >> 16);
3198 		scmd[3] = (block >> 8);
3199 		scmd[4] = block;
3200 		scmd[5] = 0;
3201 	} else {
3202 		scmd[0] = SEEK_10;
3203 		scmd[3] = (block >> 24);
3204 		scmd[4] = (block >> 16);
3205 		scmd[5] = (block >> 8);
3206 		scmd[6] = block;
3207 		if (!logical && !STp->scsi2_logical)
3208 			scmd[1] = 4;
3209 		if (STp->partition != partition) {
3210 			scmd[1] |= 2;
3211 			scmd[8] = partition;
3212 			DEBC_printk(STp, "Trying to change partition "
3213 				    "from %d to %d\n", STp->partition,
3214 				    partition);
3215 		}
3216 	}
3217 	if (STp->immediate) {
3218 		scmd[1] |= 1;		/* Don't wait for completion */
3219 		timeout = STp->device->request_queue->rq_timeout;
3220 	}
3221 
3222 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3223 			   timeout, MAX_READY_RETRIES, 1);
3224 	if (!SRpnt)
3225 		return (STp->buffer)->syscall_result;
3226 
3227 	STps->drv_block = STps->drv_file = (-1);
3228 	STps->eof = ST_NOEOF;
3229 	if ((STp->buffer)->syscall_result != 0) {
3230 		result = (-EIO);
3231 		if (STp->can_partitions &&
3232 		    (STp->device)->scsi_level >= SCSI_2 &&
3233 		    (p = find_partition(STp)) >= 0)
3234 			STp->partition = p;
3235 	} else {
3236 		if (STp->can_partitions) {
3237 			STp->partition = partition;
3238 			STps = &(STp->ps[partition]);
3239 			if (!STps->last_block_valid ||
3240 			    STps->last_block_visited != block) {
3241 				STps->at_sm = 0;
3242 				STps->rw = ST_IDLE;
3243 			}
3244 		} else
3245 			STps->at_sm = 0;
3246 		if (block == 0)
3247 			STps->drv_block = STps->drv_file = 0;
3248 		result = 0;
3249 	}
3250 
3251 	st_release_request(SRpnt);
3252 	SRpnt = NULL;
3253 
3254 	return result;
3255 }
3256 
3257 
3258 /* Find the current partition number for the drive status. Called from open and
3259    returns either partition number of negative error code. */
3260 static int find_partition(struct scsi_tape *STp)
3261 {
3262 	int i, partition;
3263 	unsigned int block;
3264 
3265 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3266 		return i;
3267 	if (partition >= ST_NBR_PARTITIONS)
3268 		return (-EIO);
3269 	return partition;
3270 }
3271 
3272 
3273 /* Change the partition if necessary */
3274 static int switch_partition(struct scsi_tape *STp)
3275 {
3276 	struct st_partstat *STps;
3277 
3278 	if (STp->partition == STp->new_partition)
3279 		return 0;
3280 	STps = &(STp->ps[STp->new_partition]);
3281 	if (!STps->last_block_valid)
3282 		STps->last_block_visited = 0;
3283 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3284 }
3285 
3286 /* Functions for reading and writing the medium partition mode page. */
3287 
3288 #define PART_PAGE   0x11
3289 #define PART_PAGE_FIXED_LENGTH 8
3290 
3291 #define PP_OFF_MAX_ADD_PARTS   2
3292 #define PP_OFF_NBR_ADD_PARTS   3
3293 #define PP_OFF_FLAGS           4
3294 #define PP_OFF_PART_UNITS      6
3295 #define PP_OFF_RESERVED        7
3296 
3297 #define PP_BIT_IDP             0x20
3298 #define PP_BIT_FDP             0x80
3299 #define PP_MSK_PSUM_MB         0x10
3300 #define PP_MSK_PSUM_UNITS      0x18
3301 #define PP_MSK_POFM            0x04
3302 
3303 /* Get the number of partitions on the tape. As a side effect reads the
3304    mode page into the tape buffer. */
3305 static int nbr_partitions(struct scsi_tape *STp)
3306 {
3307 	int result;
3308 
3309 	if (STp->ready != ST_READY)
3310 		return (-EIO);
3311 
3312 	result = read_mode_page(STp, PART_PAGE, 1);
3313 
3314 	if (result) {
3315 		DEBC_printk(STp, "Can't read medium partition page.\n");
3316 		result = (-EIO);
3317 	} else {
3318 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3319 					      PP_OFF_NBR_ADD_PARTS] + 1;
3320 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3321 	}
3322 
3323 	return result;
3324 }
3325 
3326 
3327 static int format_medium(struct scsi_tape *STp, int format)
3328 {
3329 	int result = 0;
3330 	int timeout = STp->long_timeout;
3331 	unsigned char scmd[MAX_COMMAND_SIZE];
3332 	struct st_request *SRpnt;
3333 
3334 	memset(scmd, 0, MAX_COMMAND_SIZE);
3335 	scmd[0] = FORMAT_UNIT;
3336 	scmd[2] = format;
3337 	if (STp->immediate) {
3338 		scmd[1] |= 1;		/* Don't wait for completion */
3339 		timeout = STp->device->request_queue->rq_timeout;
3340 	}
3341 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3342 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3343 			   timeout, MAX_RETRIES, 1);
3344 	if (!SRpnt)
3345 		result = STp->buffer->syscall_result;
3346 	return result;
3347 }
3348 
3349 
3350 /* Partition the tape into two partitions if size > 0 or one partition if
3351    size == 0.
3352 
3353    The block descriptors are read and written because Sony SDT-7000 does not
3354    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3355 
3356    My HP C1533A drive returns only one partition size field. This is used to
3357    set the size of partition 1. There is no size field for the default partition.
3358    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3359    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3360    The following algorithm is used to accommodate both drives: if the number of
3361    partition size fields is greater than the maximum number of additional partitions
3362    in the mode page, the second field is used. Otherwise the first field is used.
3363 
3364    For Seagate DDS drives the page length must be 8 when no partitions is defined
3365    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3366    is acceptable also to some other old drives and enforced if the first partition
3367    size field is used for the first additional partition size.
3368 
3369    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3370  */
3371 static int partition_tape(struct scsi_tape *STp, int size)
3372 {
3373 	int result;
3374 	int target_partition;
3375 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3376 	int pgo, psd_cnt, psdo;
3377 	int psum = PP_MSK_PSUM_MB, units = 0;
3378 	unsigned char *bp;
3379 
3380 	result = read_mode_page(STp, PART_PAGE, 0);
3381 	if (result) {
3382 		DEBC_printk(STp, "Can't read partition mode page.\n");
3383 		return result;
3384 	}
3385 	target_partition = 1;
3386 	if (size < 0) {
3387 		target_partition = 0;
3388 		size = -size;
3389 	}
3390 
3391 	/* The mode page is in the buffer. Let's modify it and write it. */
3392 	bp = (STp->buffer)->b_data;
3393 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3394 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3395 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3396 
3397 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3398 
3399 	if (scsi3) {
3400 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3401 		if (needs_format && size == 0) {
3402 			/* No need to write the mode page when clearing
3403 			 *  partitioning
3404 			 */
3405 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3406 			result = format_medium(STp, 0);
3407 			goto out;
3408 		}
3409 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3410 			psd_cnt = 2;
3411 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3412 			/* Use units scaling for large partitions if the device
3413 			 * suggests it and no precision lost. Required for IBM
3414 			 * TS1140/50 drives that don't support MB units.
3415 			 */
3416 			if (size >= 1000 && (size % 1000) == 0) {
3417 				size /= 1000;
3418 				psum = PP_MSK_PSUM_UNITS;
3419 				units = 9; /* GB */
3420 			}
3421 		}
3422 		/* Try it anyway if too large to specify in MB */
3423 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3424 			size /= 1000;
3425 			psum = PP_MSK_PSUM_UNITS;
3426 			units = 9;  /* GB */
3427 		}
3428 	}
3429 
3430 	if (size >= 65535 ||  /* Does not fit into two bytes */
3431 	    (target_partition == 0 && psd_cnt < 2)) {
3432 		result = -EINVAL;
3433 		goto out;
3434 	}
3435 
3436 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3437 	/* The second condition is for HP DDS which use only one partition size
3438 	 * descriptor
3439 	 */
3440 	if (target_partition > 0 &&
3441 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3442 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3443 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3444 		psdo += 2;
3445 	}
3446 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3447 
3448 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3449 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3450 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3451 
3452 	if (size == 0) {
3453 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3454 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3455 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3456 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3457 	} else {
3458 		bp[psdo] = (size >> 8) & 0xff;
3459 		bp[psdo + 1] = size & 0xff;
3460 		if (target_partition == 0)
3461 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3462 		bp[pgo + 3] = 1;
3463 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3464 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3465 		DEBC_printk(STp,
3466 			    "Formatting tape with two partitions (%i = %d MB).\n",
3467 			    target_partition, units > 0 ? size * 1000 : size);
3468 	}
3469 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3470 	bp[pgo + PP_OFF_RESERVED] = 0;
3471 	if (size != 1 || units != 0) {
3472 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3473 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3474 		bp[pgo + PP_OFF_PART_UNITS] = units;
3475 	} else
3476 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3477 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3478 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3479 
3480 	result = write_mode_page(STp, PART_PAGE, 1);
3481 
3482 	if (!result && needs_format)
3483 		result = format_medium(STp, 1);
3484 
3485 	if (result) {
3486 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3487 		result = (-EIO);
3488 	}
3489 
3490 out:
3491 	return result;
3492 }
3493 
3494 
3495 
3496 /* The ioctl command */
3497 static long st_ioctl_common(struct file *file, unsigned int cmd_in, void __user *p)
3498 {
3499 	int i, cmd_nr, cmd_type, bt;
3500 	int retval = 0;
3501 	unsigned int blk;
3502 	struct scsi_tape *STp = file->private_data;
3503 	struct st_modedef *STm;
3504 	struct st_partstat *STps;
3505 
3506 	if (mutex_lock_interruptible(&STp->lock))
3507 		return -ERESTARTSYS;
3508 
3509 	DEB(
3510 	if (debugging && !STp->in_use) {
3511 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3512 		retval = (-EIO);
3513 		goto out;
3514 	} ) /* end DEB */
3515 
3516 	STm = &(STp->modes[STp->current_mode]);
3517 	STps = &(STp->ps[STp->partition]);
3518 
3519 	/*
3520 	 * If we are in the middle of error recovery, don't let anyone
3521 	 * else try and use this device.  Also, if error recovery fails, it
3522 	 * may try and take the device offline, in which case all further
3523 	 * access to the device is prohibited.
3524 	 */
3525 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3526 			file->f_flags & O_NDELAY);
3527 	if (retval)
3528 		goto out;
3529 
3530 	cmd_type = _IOC_TYPE(cmd_in);
3531 	cmd_nr = _IOC_NR(cmd_in);
3532 
3533 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3534 		struct mtop mtc;
3535 
3536 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3537 			retval = (-EINVAL);
3538 			goto out;
3539 		}
3540 
3541 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3542 		if (i) {
3543 			retval = (-EFAULT);
3544 			goto out;
3545 		}
3546 
3547 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3548 			st_printk(KERN_WARNING, STp,
3549 				  "MTSETDRVBUFFER only allowed for root.\n");
3550 			retval = (-EPERM);
3551 			goto out;
3552 		}
3553 		if (!STm->defined &&
3554 		    (mtc.mt_op != MTSETDRVBUFFER &&
3555 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3556 			retval = (-ENXIO);
3557 			goto out;
3558 		}
3559 
3560 		if (!STp->pos_unknown) {
3561 
3562 			if (STps->eof == ST_FM_HIT) {
3563 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3564                                     mtc.mt_op == MTEOM) {
3565 					mtc.mt_count -= 1;
3566 					if (STps->drv_file >= 0)
3567 						STps->drv_file += 1;
3568 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3569 					mtc.mt_count += 1;
3570 					if (STps->drv_file >= 0)
3571 						STps->drv_file += 1;
3572 				}
3573 			}
3574 
3575 			if (mtc.mt_op == MTSEEK) {
3576 				/* Old position must be restored if partition will be
3577                                    changed */
3578 				i = !STp->can_partitions ||
3579 				    (STp->new_partition != STp->partition);
3580 			} else {
3581 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3582 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3583 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3584 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3585 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3586 				    mtc.mt_op == MTCOMPRESSION;
3587 			}
3588 			i = flush_buffer(STp, i);
3589 			if (i < 0) {
3590 				retval = i;
3591 				goto out;
3592 			}
3593 			if (STps->rw == ST_WRITING &&
3594 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3595 			     mtc.mt_op == MTSEEK ||
3596 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3597 				i = st_int_ioctl(STp, MTWEOF, 1);
3598 				if (i < 0) {
3599 					retval = i;
3600 					goto out;
3601 				}
3602 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3603 					mtc.mt_count++;
3604 				STps->rw = ST_IDLE;
3605 			     }
3606 
3607 		} else {
3608 			/*
3609 			 * If there was a bus reset, block further access
3610 			 * to this device.  If the user wants to rewind the tape,
3611 			 * then reset the flag and allow access again.
3612 			 */
3613 			if (mtc.mt_op != MTREW &&
3614 			    mtc.mt_op != MTOFFL &&
3615 			    mtc.mt_op != MTRETEN &&
3616 			    mtc.mt_op != MTERASE &&
3617 			    mtc.mt_op != MTSEEK &&
3618 			    mtc.mt_op != MTEOM) {
3619 				retval = (-EIO);
3620 				goto out;
3621 			}
3622 			reset_state(STp);
3623 			/* remove this when the midlevel properly clears was_reset */
3624 			STp->device->was_reset = 0;
3625 		}
3626 
3627 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3628 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3629 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3630 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3631 
3632 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3633 			do_door_lock(STp, 0);	/* Ignore result! */
3634 
3635 		if (mtc.mt_op == MTSETDRVBUFFER &&
3636 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3637 			retval = st_set_options(STp, mtc.mt_count);
3638 			goto out;
3639 		}
3640 
3641 		if (mtc.mt_op == MTSETPART) {
3642 			if (!STp->can_partitions ||
3643 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3644 				retval = (-EINVAL);
3645 				goto out;
3646 			}
3647 			if (mtc.mt_count >= STp->nbr_partitions &&
3648 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3649 				retval = (-EIO);
3650 				goto out;
3651 			}
3652 			if (mtc.mt_count >= STp->nbr_partitions) {
3653 				retval = (-EINVAL);
3654 				goto out;
3655 			}
3656 			STp->new_partition = mtc.mt_count;
3657 			retval = 0;
3658 			goto out;
3659 		}
3660 
3661 		if (mtc.mt_op == MTMKPART) {
3662 			if (!STp->can_partitions) {
3663 				retval = (-EINVAL);
3664 				goto out;
3665 			}
3666 			i = do_load_unload(STp, file, 1);
3667 			if (i < 0) {
3668 				retval = i;
3669 				goto out;
3670 			}
3671 			i = partition_tape(STp, mtc.mt_count);
3672 			if (i < 0) {
3673 				retval = i;
3674 				goto out;
3675 			}
3676 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3677 				STp->ps[i].rw = ST_IDLE;
3678 				STp->ps[i].at_sm = 0;
3679 				STp->ps[i].last_block_valid = 0;
3680 			}
3681 			STp->partition = STp->new_partition = 0;
3682 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3683 			STps->drv_block = STps->drv_file = 0;
3684 			retval = 0;
3685 			goto out;
3686 		}
3687 
3688 		if (mtc.mt_op == MTSEEK) {
3689 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3690 			if (!STp->can_partitions)
3691 				STp->ps[0].rw = ST_IDLE;
3692 			retval = i;
3693 			goto out;
3694 		}
3695 
3696 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3697 			retval = do_load_unload(STp, file, 0);
3698 			goto out;
3699 		}
3700 
3701 		if (mtc.mt_op == MTLOAD) {
3702 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3703 			goto out;
3704 		}
3705 
3706 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3707 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3708 			goto out;
3709 		}
3710 
3711 		if (STp->can_partitions && STp->ready == ST_READY &&
3712 		    (i = switch_partition(STp)) < 0) {
3713 			retval = i;
3714 			goto out;
3715 		}
3716 
3717 		if (mtc.mt_op == MTCOMPRESSION)
3718 			retval = st_compression(STp, (mtc.mt_count & 1));
3719 		else
3720 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3721 		goto out;
3722 	}
3723 	if (!STm->defined) {
3724 		retval = (-ENXIO);
3725 		goto out;
3726 	}
3727 
3728 	if ((i = flush_buffer(STp, 0)) < 0) {
3729 		retval = i;
3730 		goto out;
3731 	}
3732 	if (STp->can_partitions &&
3733 	    (i = switch_partition(STp)) < 0) {
3734 		retval = i;
3735 		goto out;
3736 	}
3737 
3738 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3739 		struct mtget mt_status;
3740 
3741 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3742 			 retval = (-EINVAL);
3743 			 goto out;
3744 		}
3745 
3746 		mt_status.mt_type = STp->tape_type;
3747 		mt_status.mt_dsreg =
3748 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3749 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3750 		mt_status.mt_blkno = STps->drv_block;
3751 		mt_status.mt_fileno = STps->drv_file;
3752 		if (STp->block_size != 0) {
3753 			if (STps->rw == ST_WRITING)
3754 				mt_status.mt_blkno +=
3755 				    (STp->buffer)->buffer_bytes / STp->block_size;
3756 			else if (STps->rw == ST_READING)
3757 				mt_status.mt_blkno -=
3758                                         ((STp->buffer)->buffer_bytes +
3759                                          STp->block_size - 1) / STp->block_size;
3760 		}
3761 
3762 		mt_status.mt_gstat = 0;
3763 		if (STp->drv_write_prot)
3764 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3765 		if (mt_status.mt_blkno == 0) {
3766 			if (mt_status.mt_fileno == 0)
3767 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3768 			else
3769 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3770 		}
3771 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3772 		mt_status.mt_resid = STp->partition;
3773 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3774 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3775 		else if (STps->eof >= ST_EOM_OK)
3776 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3777 		if (STp->density == 1)
3778 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3779 		else if (STp->density == 2)
3780 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3781 		else if (STp->density == 3)
3782 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3783 		if (STp->ready == ST_READY)
3784 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3785 		if (STp->ready == ST_NO_TAPE)
3786 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3787 		if (STps->at_sm)
3788 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3789 		if (STm->do_async_writes ||
3790                     (STm->do_buffer_writes && STp->block_size != 0) ||
3791 		    STp->drv_buffer != 0)
3792 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3793 		if (STp->cleaning_req)
3794 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3795 
3796 		retval = put_user_mtget(p, &mt_status);
3797 		if (retval)
3798 			goto out;
3799 
3800 		STp->recover_reg = 0;		/* Clear after read */
3801 		goto out;
3802 	}			/* End of MTIOCGET */
3803 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3804 		struct mtpos mt_pos;
3805 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3806 			 retval = (-EINVAL);
3807 			 goto out;
3808 		}
3809 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3810 			retval = i;
3811 			goto out;
3812 		}
3813 		mt_pos.mt_blkno = blk;
3814 		retval = put_user_mtpos(p, &mt_pos);
3815 		goto out;
3816 	}
3817 	mutex_unlock(&STp->lock);
3818 	switch (cmd_in) {
3819 		case SCSI_IOCTL_STOP_UNIT:
3820 			/* unload */
3821 			retval = scsi_ioctl(STp->device, cmd_in, p);
3822 			if (!retval) {
3823 				STp->rew_at_close = 0;
3824 				STp->ready = ST_NO_TAPE;
3825 			}
3826 			return retval;
3827 
3828 		case SCSI_IOCTL_GET_IDLUN:
3829 		case SCSI_IOCTL_GET_BUS_NUMBER:
3830 			break;
3831 
3832 		default:
3833 			if ((cmd_in == SG_IO ||
3834 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3835 			     cmd_in == CDROM_SEND_PACKET) &&
3836 			    !capable(CAP_SYS_RAWIO))
3837 				i = -EPERM;
3838 			else
3839 				i = scsi_cmd_ioctl(STp->device->request_queue,
3840 						   NULL, file->f_mode, cmd_in,
3841 						   p);
3842 			if (i != -ENOTTY)
3843 				return i;
3844 			break;
3845 	}
3846 	return -ENOTTY;
3847 
3848  out:
3849 	mutex_unlock(&STp->lock);
3850 	return retval;
3851 }
3852 
3853 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3854 {
3855 	void __user *p = (void __user *)arg;
3856 	struct scsi_tape *STp = file->private_data;
3857 	int ret;
3858 
3859 	ret = st_ioctl_common(file, cmd_in, p);
3860 	if (ret != -ENOTTY)
3861 		return ret;
3862 
3863 	return scsi_ioctl(STp->device, cmd_in, p);
3864 }
3865 
3866 #ifdef CONFIG_COMPAT
3867 static long st_compat_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3868 {
3869 	void __user *p = compat_ptr(arg);
3870 	struct scsi_tape *STp = file->private_data;
3871 	int ret;
3872 
3873 	/* argument conversion is handled using put_user_mtpos/put_user_mtget */
3874 	switch (cmd_in) {
3875 	case MTIOCPOS32:
3876 		return st_ioctl_common(file, MTIOCPOS, p);
3877 	case MTIOCGET32:
3878 		return st_ioctl_common(file, MTIOCGET, p);
3879 	}
3880 
3881 	ret = st_ioctl_common(file, cmd_in, p);
3882 	if (ret != -ENOTTY)
3883 		return ret;
3884 
3885 	return scsi_compat_ioctl(STp->device, cmd_in, p);
3886 }
3887 #endif
3888 
3889 
3890 
3891 /* Try to allocate a new tape buffer. Calling function must not hold
3892    dev_arr_lock. */
3893 static struct st_buffer *new_tape_buffer(int max_sg)
3894 {
3895 	struct st_buffer *tb;
3896 
3897 	tb = kzalloc(sizeof(struct st_buffer), GFP_KERNEL);
3898 	if (!tb) {
3899 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3900 		return NULL;
3901 	}
3902 	tb->frp_segs = 0;
3903 	tb->use_sg = max_sg;
3904 	tb->buffer_size = 0;
3905 
3906 	tb->reserved_pages = kcalloc(max_sg, sizeof(struct page *),
3907 				     GFP_KERNEL);
3908 	if (!tb->reserved_pages) {
3909 		kfree(tb);
3910 		return NULL;
3911 	}
3912 
3913 	return tb;
3914 }
3915 
3916 
3917 /* Try to allocate enough space in the tape buffer */
3918 #define ST_MAX_ORDER 6
3919 
3920 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size)
3921 {
3922 	int segs, max_segs, b_size, order, got;
3923 	gfp_t priority;
3924 
3925 	if (new_size <= STbuffer->buffer_size)
3926 		return 1;
3927 
3928 	if (STbuffer->buffer_size <= PAGE_SIZE)
3929 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3930 
3931 	max_segs = STbuffer->use_sg;
3932 
3933 	priority = GFP_KERNEL | __GFP_NOWARN;
3934 
3935 	if (STbuffer->cleared)
3936 		priority |= __GFP_ZERO;
3937 
3938 	if (STbuffer->frp_segs) {
3939 		order = STbuffer->reserved_page_order;
3940 		b_size = PAGE_SIZE << order;
3941 	} else {
3942 		for (b_size = PAGE_SIZE, order = 0;
3943 		     order < ST_MAX_ORDER &&
3944 			     max_segs * (PAGE_SIZE << order) < new_size;
3945 		     order++, b_size *= 2)
3946 			;  /* empty */
3947 		STbuffer->reserved_page_order = order;
3948 	}
3949 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3950 		if (order == ST_MAX_ORDER)
3951 			return 0;
3952 		normalize_buffer(STbuffer);
3953 		return enlarge_buffer(STbuffer, new_size);
3954 	}
3955 
3956 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3957 	     segs < max_segs && got < new_size;) {
3958 		struct page *page;
3959 
3960 		page = alloc_pages(priority, order);
3961 		if (!page) {
3962 			DEB(STbuffer->buffer_size = got);
3963 			normalize_buffer(STbuffer);
3964 			return 0;
3965 		}
3966 
3967 		STbuffer->frp_segs += 1;
3968 		got += b_size;
3969 		STbuffer->buffer_size = got;
3970 		STbuffer->reserved_pages[segs] = page;
3971 		segs++;
3972 	}
3973 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3974 
3975 	return 1;
3976 }
3977 
3978 
3979 /* Make sure that no data from previous user is in the internal buffer */
3980 static void clear_buffer(struct st_buffer * st_bp)
3981 {
3982 	int i;
3983 
3984 	for (i=0; i < st_bp->frp_segs; i++)
3985 		memset(page_address(st_bp->reserved_pages[i]), 0,
3986 		       PAGE_SIZE << st_bp->reserved_page_order);
3987 	st_bp->cleared = 1;
3988 }
3989 
3990 
3991 /* Release the extra buffer */
3992 static void normalize_buffer(struct st_buffer * STbuffer)
3993 {
3994 	int i, order = STbuffer->reserved_page_order;
3995 
3996 	for (i = 0; i < STbuffer->frp_segs; i++) {
3997 		__free_pages(STbuffer->reserved_pages[i], order);
3998 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3999 	}
4000 	STbuffer->frp_segs = 0;
4001 	STbuffer->sg_segs = 0;
4002 	STbuffer->reserved_page_order = 0;
4003 	STbuffer->map_data.offset = 0;
4004 }
4005 
4006 
4007 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
4008    negative error code. */
4009 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
4010 {
4011 	int i, cnt, res, offset;
4012 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4013 
4014 	for (i = 0, offset = st_bp->buffer_bytes;
4015 	     i < st_bp->frp_segs && offset >= length; i++)
4016 		offset -= length;
4017 	if (i == st_bp->frp_segs) {	/* Should never happen */
4018 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
4019 		return (-EIO);
4020 	}
4021 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4022 		struct page *page = st_bp->reserved_pages[i];
4023 		cnt = length - offset < do_count ? length - offset : do_count;
4024 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4025 		if (res)
4026 			return (-EFAULT);
4027 		do_count -= cnt;
4028 		st_bp->buffer_bytes += cnt;
4029 		ubp += cnt;
4030 		offset = 0;
4031 	}
4032 	if (do_count) /* Should never happen */
4033 		return (-EIO);
4034 
4035 	return 0;
4036 }
4037 
4038 
4039 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4040    negative error code. */
4041 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4042 {
4043 	int i, cnt, res, offset;
4044 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4045 
4046 	for (i = 0, offset = st_bp->read_pointer;
4047 	     i < st_bp->frp_segs && offset >= length; i++)
4048 		offset -= length;
4049 	if (i == st_bp->frp_segs) {	/* Should never happen */
4050 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4051 		return (-EIO);
4052 	}
4053 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4054 		struct page *page = st_bp->reserved_pages[i];
4055 		cnt = length - offset < do_count ? length - offset : do_count;
4056 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4057 		if (res)
4058 			return (-EFAULT);
4059 		do_count -= cnt;
4060 		st_bp->buffer_bytes -= cnt;
4061 		st_bp->read_pointer += cnt;
4062 		ubp += cnt;
4063 		offset = 0;
4064 	}
4065 	if (do_count) /* Should never happen */
4066 		return (-EIO);
4067 
4068 	return 0;
4069 }
4070 
4071 
4072 /* Move data towards start of buffer */
4073 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4074 {
4075 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4076 	int count, total;
4077 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4078 
4079 	if (offset == 0)
4080 		return;
4081 
4082 	total=st_bp->buffer_bytes - offset;
4083 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4084 		src_offset = offset;
4085 		if (src_offset < length)
4086 			break;
4087 		offset -= length;
4088 	}
4089 
4090 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4091 	for (dst_seg=dst_offset=0; total > 0; ) {
4092 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4093 		struct page *spage = st_bp->reserved_pages[src_seg];
4094 
4095 		count = min(length - dst_offset, length - src_offset);
4096 		memmove(page_address(dpage) + dst_offset,
4097 			page_address(spage) + src_offset, count);
4098 		src_offset += count;
4099 		if (src_offset >= length) {
4100 			src_seg++;
4101 			src_offset = 0;
4102 		}
4103 		dst_offset += count;
4104 		if (dst_offset >= length) {
4105 			dst_seg++;
4106 			dst_offset = 0;
4107 		}
4108 		total -= count;
4109 	}
4110 }
4111 
4112 /* Validate the options from command line or module parameters */
4113 static void validate_options(void)
4114 {
4115 	if (buffer_kbs > 0)
4116 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4117 	if (max_sg_segs >= ST_FIRST_SG)
4118 		st_max_sg_segs = max_sg_segs;
4119 }
4120 
4121 #ifndef MODULE
4122 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4123  */
4124 static int __init st_setup(char *str)
4125 {
4126 	int i, len, ints[5];
4127 	char *stp;
4128 
4129 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4130 
4131 	if (ints[0] > 0) {
4132 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4133 			if (parms[i].val)
4134 				*parms[i].val = ints[i + 1];
4135 	} else {
4136 		while (stp != NULL) {
4137 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4138 				len = strlen(parms[i].name);
4139 				if (!strncmp(stp, parms[i].name, len) &&
4140 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4141 					if (parms[i].val)
4142 						*parms[i].val =
4143 							simple_strtoul(stp + len + 1, NULL, 0);
4144 					else
4145 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4146 						       parms[i].name);
4147 					break;
4148 				}
4149 			}
4150 			if (i >= ARRAY_SIZE(parms))
4151 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4152 					stp);
4153 			stp = strchr(stp, ',');
4154 			if (stp)
4155 				stp++;
4156 		}
4157 	}
4158 
4159 	validate_options();
4160 
4161 	return 1;
4162 }
4163 
4164 __setup("st=", st_setup);
4165 
4166 #endif
4167 
4168 static const struct file_operations st_fops =
4169 {
4170 	.owner =	THIS_MODULE,
4171 	.read =		st_read,
4172 	.write =	st_write,
4173 	.unlocked_ioctl = st_ioctl,
4174 #ifdef CONFIG_COMPAT
4175 	.compat_ioctl = st_compat_ioctl,
4176 #endif
4177 	.open =		st_open,
4178 	.flush =	st_flush,
4179 	.release =	st_release,
4180 	.llseek =	noop_llseek,
4181 };
4182 
4183 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4184 {
4185 	int i, error;
4186 	dev_t cdev_devno;
4187 	struct cdev *cdev;
4188 	struct device *dev;
4189 	struct st_modedef *STm = &(tape->modes[mode]);
4190 	char name[10];
4191 	int dev_num = tape->index;
4192 
4193 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4194 
4195 	cdev = cdev_alloc();
4196 	if (!cdev) {
4197 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4198 		error = -ENOMEM;
4199 		goto out;
4200 	}
4201 	cdev->owner = THIS_MODULE;
4202 	cdev->ops = &st_fops;
4203 	STm->cdevs[rew] = cdev;
4204 
4205 	error = cdev_add(cdev, cdev_devno, 1);
4206 	if (error) {
4207 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4208 		       rew ? "non" : "auto", mode);
4209 		pr_err("st%d: Device not attached.\n", dev_num);
4210 		goto out_free;
4211 	}
4212 
4213 	i = mode << (4 - ST_NBR_MODE_BITS);
4214 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4215 		 tape->name, st_formats[i]);
4216 
4217 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4218 			    cdev_devno, &tape->modes[mode], "%s", name);
4219 	if (IS_ERR(dev)) {
4220 		pr_err("st%d: device_create failed\n", dev_num);
4221 		error = PTR_ERR(dev);
4222 		goto out_free;
4223 	}
4224 
4225 	STm->devs[rew] = dev;
4226 
4227 	return 0;
4228 out_free:
4229 	cdev_del(STm->cdevs[rew]);
4230 out:
4231 	STm->cdevs[rew] = NULL;
4232 	STm->devs[rew] = NULL;
4233 	return error;
4234 }
4235 
4236 static int create_cdevs(struct scsi_tape *tape)
4237 {
4238 	int mode, error;
4239 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4240 		error = create_one_cdev(tape, mode, 0);
4241 		if (error)
4242 			return error;
4243 		error = create_one_cdev(tape, mode, 1);
4244 		if (error)
4245 			return error;
4246 	}
4247 
4248 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4249 				 &tape->modes[0].devs[0]->kobj, "tape");
4250 }
4251 
4252 static void remove_cdevs(struct scsi_tape *tape)
4253 {
4254 	int mode, rew;
4255 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4256 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4257 		struct st_modedef *STm = &(tape->modes[mode]);
4258 		for (rew = 0; rew < 2; rew++) {
4259 			if (STm->cdevs[rew])
4260 				cdev_del(STm->cdevs[rew]);
4261 			if (STm->devs[rew])
4262 				device_unregister(STm->devs[rew]);
4263 		}
4264 	}
4265 }
4266 
4267 static int st_probe(struct device *dev)
4268 {
4269 	struct scsi_device *SDp = to_scsi_device(dev);
4270 	struct scsi_tape *tpnt = NULL;
4271 	struct st_modedef *STm;
4272 	struct st_partstat *STps;
4273 	struct st_buffer *buffer;
4274 	int i, error;
4275 	char *stp;
4276 
4277 	if (SDp->type != TYPE_TAPE)
4278 		return -ENODEV;
4279 	if ((stp = st_incompatible(SDp))) {
4280 		sdev_printk(KERN_INFO, SDp,
4281 			    "OnStream tapes are no longer supported;\n");
4282 		sdev_printk(KERN_INFO, SDp,
4283 			    "please mail to linux-scsi@vger.kernel.org.\n");
4284 		return -ENODEV;
4285 	}
4286 
4287 	scsi_autopm_get_device(SDp);
4288 	i = queue_max_segments(SDp->request_queue);
4289 	if (st_max_sg_segs < i)
4290 		i = st_max_sg_segs;
4291 	buffer = new_tape_buffer(i);
4292 	if (buffer == NULL) {
4293 		sdev_printk(KERN_ERR, SDp,
4294 			    "st: Can't allocate new tape buffer. "
4295 			    "Device not attached.\n");
4296 		goto out;
4297 	}
4298 
4299 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
4300 	if (tpnt == NULL) {
4301 		sdev_printk(KERN_ERR, SDp,
4302 			    "st: Can't allocate device descriptor.\n");
4303 		goto out_buffer_free;
4304 	}
4305 	kref_init(&tpnt->kref);
4306 	tpnt->driver = &st_template;
4307 
4308 	tpnt->device = SDp;
4309 	if (SDp->scsi_level <= 2)
4310 		tpnt->tape_type = MT_ISSCSI1;
4311 	else
4312 		tpnt->tape_type = MT_ISSCSI2;
4313 
4314 	tpnt->buffer = buffer;
4315 	tpnt->buffer->last_SRpnt = NULL;
4316 
4317 	tpnt->inited = 0;
4318 	tpnt->dirty = 0;
4319 	tpnt->in_use = 0;
4320 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4321 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4322 	tpnt->density = 0;
4323 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4324 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4325 	tpnt->can_partitions = 0;
4326 	tpnt->two_fm = ST_TWO_FM;
4327 	tpnt->fast_mteom = ST_FAST_MTEOM;
4328 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4329 	tpnt->sili = ST_SILI;
4330 	tpnt->immediate = ST_NOWAIT;
4331 	tpnt->immediate_filemark = 0;
4332 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4333 	tpnt->partition = 0;
4334 	tpnt->new_partition = 0;
4335 	tpnt->nbr_partitions = 0;
4336 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4337 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4338 	tpnt->try_dio = try_direct_io;
4339 
4340 	for (i = 0; i < ST_NBR_MODES; i++) {
4341 		STm = &(tpnt->modes[i]);
4342 		STm->defined = 0;
4343 		STm->sysv = ST_SYSV;
4344 		STm->defaults_for_writes = 0;
4345 		STm->do_async_writes = ST_ASYNC_WRITES;
4346 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4347 		STm->do_read_ahead = ST_READ_AHEAD;
4348 		STm->default_compression = ST_DONT_TOUCH;
4349 		STm->default_blksize = (-1);	/* No forced size */
4350 		STm->default_density = (-1);	/* No forced density */
4351 		STm->tape = tpnt;
4352 	}
4353 
4354 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4355 		STps = &(tpnt->ps[i]);
4356 		STps->rw = ST_IDLE;
4357 		STps->eof = ST_NOEOF;
4358 		STps->at_sm = 0;
4359 		STps->last_block_valid = 0;
4360 		STps->drv_block = (-1);
4361 		STps->drv_file = (-1);
4362 	}
4363 
4364 	tpnt->current_mode = 0;
4365 	tpnt->modes[0].defined = 1;
4366 
4367 	tpnt->density_changed = tpnt->compression_changed =
4368 	    tpnt->blksize_changed = 0;
4369 	mutex_init(&tpnt->lock);
4370 
4371 	idr_preload(GFP_KERNEL);
4372 	spin_lock(&st_index_lock);
4373 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4374 	spin_unlock(&st_index_lock);
4375 	idr_preload_end();
4376 	if (error < 0) {
4377 		pr_warn("st: idr allocation failed: %d\n", error);
4378 		goto out_free_tape;
4379 	}
4380 	tpnt->index = error;
4381 	sprintf(tpnt->name, "st%d", tpnt->index);
4382 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4383 	if (tpnt->stats == NULL) {
4384 		sdev_printk(KERN_ERR, SDp,
4385 			    "st: Can't allocate statistics.\n");
4386 		goto out_idr_remove;
4387 	}
4388 
4389 	dev_set_drvdata(dev, tpnt);
4390 
4391 
4392 	error = create_cdevs(tpnt);
4393 	if (error)
4394 		goto out_remove_devs;
4395 	scsi_autopm_put_device(SDp);
4396 
4397 	sdev_printk(KERN_NOTICE, SDp,
4398 		    "Attached scsi tape %s\n", tpnt->name);
4399 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4400 		    tpnt->name, tpnt->try_dio ? "yes" : "no",
4401 		    queue_dma_alignment(SDp->request_queue) + 1);
4402 
4403 	return 0;
4404 
4405 out_remove_devs:
4406 	remove_cdevs(tpnt);
4407 	kfree(tpnt->stats);
4408 out_idr_remove:
4409 	spin_lock(&st_index_lock);
4410 	idr_remove(&st_index_idr, tpnt->index);
4411 	spin_unlock(&st_index_lock);
4412 out_free_tape:
4413 	kfree(tpnt);
4414 out_buffer_free:
4415 	kfree(buffer);
4416 out:
4417 	scsi_autopm_put_device(SDp);
4418 	return -ENODEV;
4419 };
4420 
4421 
4422 static int st_remove(struct device *dev)
4423 {
4424 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4425 	int index = tpnt->index;
4426 
4427 	scsi_autopm_get_device(to_scsi_device(dev));
4428 	remove_cdevs(tpnt);
4429 
4430 	mutex_lock(&st_ref_mutex);
4431 	kref_put(&tpnt->kref, scsi_tape_release);
4432 	mutex_unlock(&st_ref_mutex);
4433 	spin_lock(&st_index_lock);
4434 	idr_remove(&st_index_idr, index);
4435 	spin_unlock(&st_index_lock);
4436 	return 0;
4437 }
4438 
4439 /**
4440  *      scsi_tape_release - Called to free the Scsi_Tape structure
4441  *      @kref: pointer to embedded kref
4442  *
4443  *      st_ref_mutex must be held entering this routine.  Because it is
4444  *      called on last put, you should always use the scsi_tape_get()
4445  *      scsi_tape_put() helpers which manipulate the semaphore directly
4446  *      and never do a direct kref_put().
4447  **/
4448 static void scsi_tape_release(struct kref *kref)
4449 {
4450 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4451 
4452 	tpnt->device = NULL;
4453 
4454 	if (tpnt->buffer) {
4455 		normalize_buffer(tpnt->buffer);
4456 		kfree(tpnt->buffer->reserved_pages);
4457 		kfree(tpnt->buffer);
4458 	}
4459 
4460 	kfree(tpnt->stats);
4461 	kfree(tpnt);
4462 	return;
4463 }
4464 
4465 static struct class st_sysfs_class = {
4466 	.name = "scsi_tape",
4467 	.dev_groups = st_dev_groups,
4468 };
4469 
4470 static int __init init_st(void)
4471 {
4472 	int err;
4473 
4474 	validate_options();
4475 
4476 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4477 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4478 
4479 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4480 	if (debugging) {
4481 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4482 			debugging);
4483 	}
4484 
4485 	err = class_register(&st_sysfs_class);
4486 	if (err) {
4487 		pr_err("Unable register sysfs class for SCSI tapes\n");
4488 		return err;
4489 	}
4490 
4491 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4492 				     ST_MAX_TAPE_ENTRIES, "st");
4493 	if (err) {
4494 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4495 		       SCSI_TAPE_MAJOR);
4496 		goto err_class;
4497 	}
4498 
4499 	err = scsi_register_driver(&st_template.gendrv);
4500 	if (err)
4501 		goto err_chrdev;
4502 
4503 	return 0;
4504 
4505 err_chrdev:
4506 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4507 				 ST_MAX_TAPE_ENTRIES);
4508 err_class:
4509 	class_unregister(&st_sysfs_class);
4510 	return err;
4511 }
4512 
4513 static void __exit exit_st(void)
4514 {
4515 	scsi_unregister_driver(&st_template.gendrv);
4516 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4517 				 ST_MAX_TAPE_ENTRIES);
4518 	class_unregister(&st_sysfs_class);
4519 	idr_destroy(&st_index_idr);
4520 	printk(KERN_INFO "st: Unloaded.\n");
4521 }
4522 
4523 module_init(init_st);
4524 module_exit(exit_st);
4525 
4526 
4527 /* The sysfs driver interface. Read-only at the moment */
4528 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4529 {
4530 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4531 }
4532 static DRIVER_ATTR_RO(try_direct_io);
4533 
4534 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4535 {
4536 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4537 }
4538 static DRIVER_ATTR_RO(fixed_buffer_size);
4539 
4540 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4541 {
4542 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4543 }
4544 static DRIVER_ATTR_RO(max_sg_segs);
4545 
4546 static ssize_t version_show(struct device_driver *ddd, char *buf)
4547 {
4548 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4549 }
4550 static DRIVER_ATTR_RO(version);
4551 
4552 #if DEBUG
4553 static ssize_t debug_flag_store(struct device_driver *ddp,
4554 	const char *buf, size_t count)
4555 {
4556 /* We only care what the first byte of the data is the rest is unused.
4557  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4558  * other values have -EINVAL returned if they are passed in.
4559  */
4560 	if (count > 0) {
4561 		if (buf[0] == '0') {
4562 			debugging = NO_DEBUG;
4563 			return count;
4564 		} else if (buf[0] == '1') {
4565 			debugging = 1;
4566 			return count;
4567 		}
4568 	}
4569 	return -EINVAL;
4570 }
4571 
4572 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4573 {
4574 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4575 }
4576 static DRIVER_ATTR_RW(debug_flag);
4577 #endif
4578 
4579 static struct attribute *st_drv_attrs[] = {
4580 	&driver_attr_try_direct_io.attr,
4581 	&driver_attr_fixed_buffer_size.attr,
4582 	&driver_attr_max_sg_segs.attr,
4583 	&driver_attr_version.attr,
4584 #if DEBUG
4585 	&driver_attr_debug_flag.attr,
4586 #endif
4587 	NULL,
4588 };
4589 ATTRIBUTE_GROUPS(st_drv);
4590 
4591 /* The sysfs simple class interface */
4592 static ssize_t
4593 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4594 {
4595 	struct st_modedef *STm = dev_get_drvdata(dev);
4596 	ssize_t l = 0;
4597 
4598 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4599 	return l;
4600 }
4601 static DEVICE_ATTR_RO(defined);
4602 
4603 static ssize_t
4604 default_blksize_show(struct device *dev, struct device_attribute *attr,
4605 		     char *buf)
4606 {
4607 	struct st_modedef *STm = dev_get_drvdata(dev);
4608 	ssize_t l = 0;
4609 
4610 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4611 	return l;
4612 }
4613 static DEVICE_ATTR_RO(default_blksize);
4614 
4615 static ssize_t
4616 default_density_show(struct device *dev, struct device_attribute *attr,
4617 		     char *buf)
4618 {
4619 	struct st_modedef *STm = dev_get_drvdata(dev);
4620 	ssize_t l = 0;
4621 	char *fmt;
4622 
4623 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4624 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4625 	return l;
4626 }
4627 static DEVICE_ATTR_RO(default_density);
4628 
4629 static ssize_t
4630 default_compression_show(struct device *dev, struct device_attribute *attr,
4631 			 char *buf)
4632 {
4633 	struct st_modedef *STm = dev_get_drvdata(dev);
4634 	ssize_t l = 0;
4635 
4636 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4637 	return l;
4638 }
4639 static DEVICE_ATTR_RO(default_compression);
4640 
4641 static ssize_t
4642 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4643 {
4644 	struct st_modedef *STm = dev_get_drvdata(dev);
4645 	struct scsi_tape *STp = STm->tape;
4646 	int options;
4647 	ssize_t l = 0;
4648 
4649 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4650 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4651 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4652 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4653 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4654 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4655 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4656 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4657 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4658 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4659 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4660 	options |= STm->sysv ? MT_ST_SYSV : 0;
4661 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4662 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4663 	options |= STp->sili ? MT_ST_SILI : 0;
4664 
4665 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4666 	return l;
4667 }
4668 static DEVICE_ATTR_RO(options);
4669 
4670 /* Support for tape stats */
4671 
4672 /**
4673  * read_cnt_show - return read count - count of reads made from tape drive
4674  * @dev: struct device
4675  * @attr: attribute structure
4676  * @buf: buffer to return formatted data in
4677  */
4678 static ssize_t read_cnt_show(struct device *dev,
4679 	struct device_attribute *attr, char *buf)
4680 {
4681 	struct st_modedef *STm = dev_get_drvdata(dev);
4682 
4683 	return sprintf(buf, "%lld",
4684 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4685 }
4686 static DEVICE_ATTR_RO(read_cnt);
4687 
4688 /**
4689  * read_byte_cnt_show - return read byte count - tape drives
4690  * may use blocks less than 512 bytes this gives the raw byte count of
4691  * of data read from the tape drive.
4692  * @dev: struct device
4693  * @attr: attribute structure
4694  * @buf: buffer to return formatted data in
4695  */
4696 static ssize_t read_byte_cnt_show(struct device *dev,
4697 	struct device_attribute *attr, char *buf)
4698 {
4699 	struct st_modedef *STm = dev_get_drvdata(dev);
4700 
4701 	return sprintf(buf, "%lld",
4702 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4703 }
4704 static DEVICE_ATTR_RO(read_byte_cnt);
4705 
4706 /**
4707  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4708  * @dev: struct device
4709  * @attr: attribute structure
4710  * @buf: buffer to return formatted data in
4711  */
4712 static ssize_t read_ns_show(struct device *dev,
4713 	struct device_attribute *attr, char *buf)
4714 {
4715 	struct st_modedef *STm = dev_get_drvdata(dev);
4716 
4717 	return sprintf(buf, "%lld",
4718 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4719 }
4720 static DEVICE_ATTR_RO(read_ns);
4721 
4722 /**
4723  * write_cnt_show - write count - number of user calls
4724  * to write(2) that have written data to tape.
4725  * @dev: struct device
4726  * @attr: attribute structure
4727  * @buf: buffer to return formatted data in
4728  */
4729 static ssize_t write_cnt_show(struct device *dev,
4730 	struct device_attribute *attr, char *buf)
4731 {
4732 	struct st_modedef *STm = dev_get_drvdata(dev);
4733 
4734 	return sprintf(buf, "%lld",
4735 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4736 }
4737 static DEVICE_ATTR_RO(write_cnt);
4738 
4739 /**
4740  * write_byte_cnt_show - write byte count - raw count of
4741  * bytes written to tape.
4742  * @dev: struct device
4743  * @attr: attribute structure
4744  * @buf: buffer to return formatted data in
4745  */
4746 static ssize_t write_byte_cnt_show(struct device *dev,
4747 	struct device_attribute *attr, char *buf)
4748 {
4749 	struct st_modedef *STm = dev_get_drvdata(dev);
4750 
4751 	return sprintf(buf, "%lld",
4752 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4753 }
4754 static DEVICE_ATTR_RO(write_byte_cnt);
4755 
4756 /**
4757  * write_ns_show - write ns - number of nanoseconds waiting on write
4758  * requests to complete.
4759  * @dev: struct device
4760  * @attr: attribute structure
4761  * @buf: buffer to return formatted data in
4762  */
4763 static ssize_t write_ns_show(struct device *dev,
4764 	struct device_attribute *attr, char *buf)
4765 {
4766 	struct st_modedef *STm = dev_get_drvdata(dev);
4767 
4768 	return sprintf(buf, "%lld",
4769 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4770 }
4771 static DEVICE_ATTR_RO(write_ns);
4772 
4773 /**
4774  * in_flight_show - number of I/Os currently in flight -
4775  * in most cases this will be either 0 or 1. It may be higher if someone
4776  * has also issued other SCSI commands such as via an ioctl.
4777  * @dev: struct device
4778  * @attr: attribute structure
4779  * @buf: buffer to return formatted data in
4780  */
4781 static ssize_t in_flight_show(struct device *dev,
4782 	struct device_attribute *attr, char *buf)
4783 {
4784 	struct st_modedef *STm = dev_get_drvdata(dev);
4785 
4786 	return sprintf(buf, "%lld",
4787 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4788 }
4789 static DEVICE_ATTR_RO(in_flight);
4790 
4791 /**
4792  * io_ns_show - io wait ns - this is the number of ns spent
4793  * waiting on all I/O to complete. This includes tape movement commands
4794  * such as rewinding, seeking to end of file or tape, it also includes
4795  * read and write. To determine the time spent on tape movement
4796  * subtract the read and write ns from this value.
4797  * @dev: struct device
4798  * @attr: attribute structure
4799  * @buf: buffer to return formatted data in
4800  */
4801 static ssize_t io_ns_show(struct device *dev,
4802 	struct device_attribute *attr, char *buf)
4803 {
4804 	struct st_modedef *STm = dev_get_drvdata(dev);
4805 
4806 	return sprintf(buf, "%lld",
4807 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4808 }
4809 static DEVICE_ATTR_RO(io_ns);
4810 
4811 /**
4812  * other_cnt_show - other io count - this is the number of
4813  * I/O requests other than read and write requests.
4814  * Typically these are tape movement requests but will include driver
4815  * tape movement. This includes only requests issued by the st driver.
4816  * @dev: struct device
4817  * @attr: attribute structure
4818  * @buf: buffer to return formatted data in
4819  */
4820 static ssize_t other_cnt_show(struct device *dev,
4821 	struct device_attribute *attr, char *buf)
4822 {
4823 	struct st_modedef *STm = dev_get_drvdata(dev);
4824 
4825 	return sprintf(buf, "%lld",
4826 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4827 }
4828 static DEVICE_ATTR_RO(other_cnt);
4829 
4830 /**
4831  * resid_cnt_show - A count of the number of times we get a residual
4832  * count - this should indicate someone issuing reads larger than the
4833  * block size on tape.
4834  * @dev: struct device
4835  * @attr: attribute structure
4836  * @buf: buffer to return formatted data in
4837  */
4838 static ssize_t resid_cnt_show(struct device *dev,
4839 	struct device_attribute *attr, char *buf)
4840 {
4841 	struct st_modedef *STm = dev_get_drvdata(dev);
4842 
4843 	return sprintf(buf, "%lld",
4844 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4845 }
4846 static DEVICE_ATTR_RO(resid_cnt);
4847 
4848 static struct attribute *st_dev_attrs[] = {
4849 	&dev_attr_defined.attr,
4850 	&dev_attr_default_blksize.attr,
4851 	&dev_attr_default_density.attr,
4852 	&dev_attr_default_compression.attr,
4853 	&dev_attr_options.attr,
4854 	NULL,
4855 };
4856 
4857 static struct attribute *st_stats_attrs[] = {
4858 	&dev_attr_read_cnt.attr,
4859 	&dev_attr_read_byte_cnt.attr,
4860 	&dev_attr_read_ns.attr,
4861 	&dev_attr_write_cnt.attr,
4862 	&dev_attr_write_byte_cnt.attr,
4863 	&dev_attr_write_ns.attr,
4864 	&dev_attr_in_flight.attr,
4865 	&dev_attr_io_ns.attr,
4866 	&dev_attr_other_cnt.attr,
4867 	&dev_attr_resid_cnt.attr,
4868 	NULL,
4869 };
4870 
4871 static struct attribute_group stats_group = {
4872 	.name = "stats",
4873 	.attrs = st_stats_attrs,
4874 };
4875 
4876 static struct attribute_group st_group = {
4877 	.attrs = st_dev_attrs,
4878 };
4879 
4880 static const struct attribute_group *st_dev_groups[] = {
4881 	&st_group,
4882 	&stats_group,
4883 	NULL,
4884 };
4885 
4886 /* The following functions may be useful for a larger audience. */
4887 static int sgl_map_user_pages(struct st_buffer *STbp,
4888 			      const unsigned int max_pages, unsigned long uaddr,
4889 			      size_t count, int rw)
4890 {
4891 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4892 	unsigned long start = uaddr >> PAGE_SHIFT;
4893 	const int nr_pages = end - start;
4894 	int res, i;
4895 	struct page **pages;
4896 	struct rq_map_data *mdata = &STbp->map_data;
4897 
4898 	/* User attempted Overflow! */
4899 	if ((uaddr + count) < uaddr)
4900 		return -EINVAL;
4901 
4902 	/* Too big */
4903         if (nr_pages > max_pages)
4904 		return -ENOMEM;
4905 
4906 	/* Hmm? */
4907 	if (count == 0)
4908 		return 0;
4909 
4910 	pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
4911 	if (pages == NULL)
4912 		return -ENOMEM;
4913 
4914         /* Try to fault in all of the necessary pages */
4915         /* rw==READ means read from drive, write into memory area */
4916 	res = pin_user_pages_fast(uaddr, nr_pages, rw == READ ? FOLL_WRITE : 0,
4917 				  pages);
4918 
4919 	/* Errors and no page mapped should return here */
4920 	if (res < nr_pages)
4921 		goto out_unmap;
4922 
4923         for (i=0; i < nr_pages; i++) {
4924                 /* FIXME: flush superflous for rw==READ,
4925                  * probably wrong function for rw==WRITE
4926                  */
4927 		flush_dcache_page(pages[i]);
4928         }
4929 
4930 	mdata->offset = uaddr & ~PAGE_MASK;
4931 	STbp->mapped_pages = pages;
4932 
4933 	return nr_pages;
4934  out_unmap:
4935 	if (res > 0) {
4936 		unpin_user_pages(pages, res);
4937 		res = 0;
4938 	}
4939 	kfree(pages);
4940 	return res;
4941 }
4942 
4943 
4944 /* And unmap them... */
4945 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4946 				const unsigned int nr_pages, int dirtied)
4947 {
4948 	/* FIXME: cache flush missing for rw==READ */
4949 	unpin_user_pages_dirty_lock(STbp->mapped_pages, nr_pages, dirtied);
4950 
4951 	kfree(STbp->mapped_pages);
4952 	STbp->mapped_pages = NULL;
4953 
4954 	return 0;
4955 }
4956