xref: /openbmc/linux/drivers/scsi/st.c (revision 5e012745)
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.txt 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/fs.h>
26 #include <linux/kernel.h>
27 #include <linux/sched/signal.h>
28 #include <linux/mm.h>
29 #include <linux/init.h>
30 #include <linux/string.h>
31 #include <linux/slab.h>
32 #include <linux/errno.h>
33 #include <linux/mtio.h>
34 #include <linux/cdrom.h>
35 #include <linux/ioctl.h>
36 #include <linux/fcntl.h>
37 #include <linux/spinlock.h>
38 #include <linux/blkdev.h>
39 #include <linux/moduleparam.h>
40 #include <linux/cdev.h>
41 #include <linux/idr.h>
42 #include <linux/delay.h>
43 #include <linux/mutex.h>
44 
45 #include <linux/uaccess.h>
46 #include <asm/dma.h>
47 
48 #include <scsi/scsi.h>
49 #include <scsi/scsi_dbg.h>
50 #include <scsi/scsi_device.h>
51 #include <scsi/scsi_driver.h>
52 #include <scsi/scsi_eh.h>
53 #include <scsi/scsi_host.h>
54 #include <scsi/scsi_ioctl.h>
55 #include <scsi/sg.h>
56 
57 
58 /* The driver prints some debugging information on the console if DEBUG
59    is defined and non-zero. */
60 #define DEBUG 1
61 #define NO_DEBUG 0
62 
63 #define ST_DEB_MSG  KERN_NOTICE
64 #if DEBUG
65 /* The message level for the debug messages is currently set to KERN_NOTICE
66    so that people can easily see the messages. Later when the debugging messages
67    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
68 #define DEB(a) a
69 #define DEBC(a) if (debugging) { a ; }
70 #else
71 #define DEB(a)
72 #define DEBC(a)
73 #endif
74 
75 #define ST_KILOBYTE 1024
76 
77 #include "st_options.h"
78 #include "st.h"
79 
80 static int buffer_kbs;
81 static int max_sg_segs;
82 static int try_direct_io = TRY_DIRECT_IO;
83 static int try_rdio = 1;
84 static int try_wdio = 1;
85 static int debug_flag;
86 
87 static struct class st_sysfs_class;
88 static const struct attribute_group *st_dev_groups[];
89 static const struct attribute_group *st_drv_groups[];
90 
91 MODULE_AUTHOR("Kai Makisara");
92 MODULE_DESCRIPTION("SCSI tape (st) driver");
93 MODULE_LICENSE("GPL");
94 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
95 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
96 
97 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
98  * of sysfs parameters (which module_param doesn't yet support).
99  * Sysfs parameters defined explicitly later.
100  */
101 module_param_named(buffer_kbs, buffer_kbs, int, 0);
102 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
103 module_param_named(max_sg_segs, max_sg_segs, int, 0);
104 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
105 module_param_named(try_direct_io, try_direct_io, int, 0);
106 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
107 module_param_named(debug_flag, debug_flag, int, 0);
108 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
109 
110 
111 /* Extra parameters for testing */
112 module_param_named(try_rdio, try_rdio, int, 0);
113 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
114 module_param_named(try_wdio, try_wdio, int, 0);
115 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
116 
117 #ifndef MODULE
118 static int write_threshold_kbs;  /* retained for compatibility */
119 static struct st_dev_parm {
120 	char *name;
121 	int *val;
122 } parms[] __initdata = {
123 	{
124 		"buffer_kbs", &buffer_kbs
125 	},
126 	{       /* Retained for compatibility with 2.4 */
127 		"write_threshold_kbs", &write_threshold_kbs
128 	},
129 	{
130 		"max_sg_segs", NULL
131 	},
132 	{
133 		"try_direct_io", &try_direct_io
134 	},
135 	{
136 		"debug_flag", &debug_flag
137 	}
138 };
139 #endif
140 
141 /* Restrict the number of modes so that names for all are assigned */
142 #if ST_NBR_MODES > 16
143 #error "Maximum number of modes is 16"
144 #endif
145 /* Bit reversed order to get same names for same minors with all
146    mode counts */
147 static const char *st_formats[] = {
148 	"",  "r", "k", "s", "l", "t", "o", "u",
149 	"m", "v", "p", "x", "a", "y", "q", "z"};
150 
151 /* The default definitions have been moved to st_options.h */
152 
153 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
154 
155 /* The buffer size should fit into the 24 bits for length in the
156    6-byte SCSI read and write commands. */
157 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
158 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
159 #endif
160 
161 static int debugging = DEBUG;
162 
163 #define MAX_RETRIES 0
164 #define MAX_WRITE_RETRIES 0
165 #define MAX_READY_RETRIES 0
166 #define NO_TAPE  NOT_READY
167 
168 #define ST_TIMEOUT (900 * HZ)
169 #define ST_LONG_TIMEOUT (14000 * HZ)
170 
171 /* Remove mode bits and auto-rewind bit (7) */
172 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
173 	(iminor(x) & ((1 << ST_MODE_SHIFT)-1)))
174 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
175 
176 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
177 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
178   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
179 
180 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
181    24 bits) */
182 #define SET_DENS_AND_BLK 0x10001
183 
184 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
185 static int st_max_sg_segs = ST_MAX_SG;
186 
187 static int modes_defined;
188 
189 static int enlarge_buffer(struct st_buffer *, int, int);
190 static void clear_buffer(struct st_buffer *);
191 static void normalize_buffer(struct st_buffer *);
192 static int append_to_buffer(const char __user *, struct st_buffer *, int);
193 static int from_buffer(struct st_buffer *, char __user *, int);
194 static void move_buffer_data(struct st_buffer *, int);
195 
196 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
197 			      unsigned long, size_t, int);
198 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
199 
200 static int st_probe(struct device *);
201 static int st_remove(struct device *);
202 
203 static struct scsi_driver st_template = {
204 	.gendrv = {
205 		.name		= "st",
206 		.owner		= THIS_MODULE,
207 		.probe		= st_probe,
208 		.remove		= st_remove,
209 		.groups		= st_drv_groups,
210 	},
211 };
212 
213 static int st_compression(struct scsi_tape *, int);
214 
215 static int find_partition(struct scsi_tape *);
216 static int switch_partition(struct scsi_tape *);
217 
218 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
219 
220 static void scsi_tape_release(struct kref *);
221 
222 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
223 
224 static DEFINE_MUTEX(st_ref_mutex);
225 static DEFINE_SPINLOCK(st_index_lock);
226 static DEFINE_SPINLOCK(st_use_lock);
227 static DEFINE_IDR(st_index_idr);
228 
229 
230 
231 #ifndef SIGS_FROM_OSST
232 #define SIGS_FROM_OSST \
233 	{"OnStream", "SC-", "", "osst"}, \
234 	{"OnStream", "DI-", "", "osst"}, \
235 	{"OnStream", "DP-", "", "osst"}, \
236 	{"OnStream", "USB", "", "osst"}, \
237 	{"OnStream", "FW-", "", "osst"}
238 #endif
239 
240 static struct scsi_tape *scsi_tape_get(int dev)
241 {
242 	struct scsi_tape *STp = NULL;
243 
244 	mutex_lock(&st_ref_mutex);
245 	spin_lock(&st_index_lock);
246 
247 	STp = idr_find(&st_index_idr, dev);
248 	if (!STp) goto out;
249 
250 	kref_get(&STp->kref);
251 
252 	if (!STp->device)
253 		goto out_put;
254 
255 	if (scsi_device_get(STp->device))
256 		goto out_put;
257 
258 	goto out;
259 
260 out_put:
261 	kref_put(&STp->kref, scsi_tape_release);
262 	STp = NULL;
263 out:
264 	spin_unlock(&st_index_lock);
265 	mutex_unlock(&st_ref_mutex);
266 	return STp;
267 }
268 
269 static void scsi_tape_put(struct scsi_tape *STp)
270 {
271 	struct scsi_device *sdev = STp->device;
272 
273 	mutex_lock(&st_ref_mutex);
274 	kref_put(&STp->kref, scsi_tape_release);
275 	scsi_device_put(sdev);
276 	mutex_unlock(&st_ref_mutex);
277 }
278 
279 struct st_reject_data {
280 	char *vendor;
281 	char *model;
282 	char *rev;
283 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
284 };
285 
286 static struct st_reject_data reject_list[] = {
287 	/* {"XXX", "Yy-", "", NULL},  example */
288 	SIGS_FROM_OSST,
289 	{NULL, }};
290 
291 /* If the device signature is on the list of incompatible drives, the
292    function returns a pointer to the name of the correct driver (if known) */
293 static char * st_incompatible(struct scsi_device* SDp)
294 {
295 	struct st_reject_data *rp;
296 
297 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
298 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
299 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
300 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
301 			if (rp->driver_hint)
302 				return rp->driver_hint;
303 			else
304 				return "unknown";
305 		}
306 	return NULL;
307 }
308 
309 
310 static inline char *tape_name(struct scsi_tape *tape)
311 {
312 	return tape->disk->disk_name;
313 }
314 
315 #define st_printk(prefix, t, fmt, a...) \
316 	sdev_prefix_printk(prefix, (t)->device, tape_name(t), fmt, ##a)
317 #ifdef DEBUG
318 #define DEBC_printk(t, fmt, a...) \
319 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
320 #else
321 #define DEBC_printk(t, fmt, a...)
322 #endif
323 
324 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
325 {
326 	const u8 *ucp;
327 	const u8 *sense = SRpnt->sense;
328 
329 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
330 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
331 	s->flags = 0;
332 
333 	if (s->have_sense) {
334 		s->deferred = 0;
335 		s->remainder_valid =
336 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
337 		switch (sense[0] & 0x7f) {
338 		case 0x71:
339 			s->deferred = 1;
340 			/* fall through */
341 		case 0x70:
342 			s->fixed_format = 1;
343 			s->flags = sense[2] & 0xe0;
344 			break;
345 		case 0x73:
346 			s->deferred = 1;
347 			/* fall through */
348 		case 0x72:
349 			s->fixed_format = 0;
350 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
351 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
352 			break;
353 		}
354 	}
355 }
356 
357 
358 /* Convert the result to success code */
359 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
360 {
361 	int result = SRpnt->result;
362 	u8 scode;
363 	DEB(const char *stp;)
364 	char *name = tape_name(STp);
365 	struct st_cmdstatus *cmdstatp;
366 
367 	if (!result)
368 		return 0;
369 
370 	cmdstatp = &STp->buffer->cmdstat;
371 	st_analyze_sense(SRpnt, cmdstatp);
372 
373 	if (cmdstatp->have_sense)
374 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
375 	else
376 		scode = 0;
377 
378 	DEB(
379 	if (debugging) {
380 		st_printk(ST_DEB_MSG, STp,
381 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
382 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
383 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
384 		if (cmdstatp->have_sense)
385 			__scsi_print_sense(STp->device, name,
386 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
387 	} ) /* end DEB */
388 	if (!debugging) { /* Abnormal conditions for tape */
389 		if (!cmdstatp->have_sense)
390 			st_printk(KERN_WARNING, STp,
391 			       "Error %x (driver bt 0x%x, host bt 0x%x).\n",
392 			       result, driver_byte(result), host_byte(result));
393 		else if (cmdstatp->have_sense &&
394 			 scode != NO_SENSE &&
395 			 scode != RECOVERED_ERROR &&
396 			 /* scode != UNIT_ATTENTION && */
397 			 scode != BLANK_CHECK &&
398 			 scode != VOLUME_OVERFLOW &&
399 			 SRpnt->cmd[0] != MODE_SENSE &&
400 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
401 
402 			__scsi_print_sense(STp->device, name,
403 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
404 		}
405 	}
406 
407 	if (cmdstatp->fixed_format &&
408 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
409 		if (STp->cln_sense_value)
410 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
411 					       STp->cln_sense_mask) == STp->cln_sense_value);
412 		else
413 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
414 					       STp->cln_sense_mask) != 0);
415 	}
416 	if (cmdstatp->have_sense &&
417 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
418 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
419 
420 	STp->pos_unknown |= STp->device->was_reset;
421 
422 	if (cmdstatp->have_sense &&
423 	    scode == RECOVERED_ERROR
424 #if ST_RECOVERED_WRITE_FATAL
425 	    && SRpnt->cmd[0] != WRITE_6
426 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
427 #endif
428 	    ) {
429 		STp->recover_count++;
430 		STp->recover_reg++;
431 
432 		DEB(
433 		if (debugging) {
434 			if (SRpnt->cmd[0] == READ_6)
435 				stp = "read";
436 			else if (SRpnt->cmd[0] == WRITE_6)
437 				stp = "write";
438 			else
439 				stp = "ioctl";
440 			st_printk(ST_DEB_MSG, STp,
441 				  "Recovered %s error (%d).\n",
442 				  stp, STp->recover_count);
443 		} ) /* end DEB */
444 
445 		if (cmdstatp->flags == 0)
446 			return 0;
447 	}
448 	return (-EIO);
449 }
450 
451 static struct st_request *st_allocate_request(struct scsi_tape *stp)
452 {
453 	struct st_request *streq;
454 
455 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
456 	if (streq)
457 		streq->stp = stp;
458 	else {
459 		st_printk(KERN_ERR, stp,
460 			  "Can't get SCSI request.\n");
461 		if (signal_pending(current))
462 			stp->buffer->syscall_result = -EINTR;
463 		else
464 			stp->buffer->syscall_result = -EBUSY;
465 	}
466 
467 	return streq;
468 }
469 
470 static void st_release_request(struct st_request *streq)
471 {
472 	kfree(streq);
473 }
474 
475 static void st_do_stats(struct scsi_tape *STp, struct request *req)
476 {
477 	ktime_t now;
478 
479 	now = ktime_get();
480 	if (scsi_req(req)->cmd[0] == WRITE_6) {
481 		now = ktime_sub(now, STp->stats->write_time);
482 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
483 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
484 		atomic64_inc(&STp->stats->write_cnt);
485 		if (scsi_req(req)->result) {
486 			atomic64_add(atomic_read(&STp->stats->last_write_size)
487 				- STp->buffer->cmdstat.residual,
488 				&STp->stats->write_byte_cnt);
489 			if (STp->buffer->cmdstat.residual > 0)
490 				atomic64_inc(&STp->stats->resid_cnt);
491 		} else
492 			atomic64_add(atomic_read(&STp->stats->last_write_size),
493 				&STp->stats->write_byte_cnt);
494 	} else if (scsi_req(req)->cmd[0] == READ_6) {
495 		now = ktime_sub(now, STp->stats->read_time);
496 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
497 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
498 		atomic64_inc(&STp->stats->read_cnt);
499 		if (scsi_req(req)->result) {
500 			atomic64_add(atomic_read(&STp->stats->last_read_size)
501 				- STp->buffer->cmdstat.residual,
502 				&STp->stats->read_byte_cnt);
503 			if (STp->buffer->cmdstat.residual > 0)
504 				atomic64_inc(&STp->stats->resid_cnt);
505 		} else
506 			atomic64_add(atomic_read(&STp->stats->last_read_size),
507 				&STp->stats->read_byte_cnt);
508 	} else {
509 		now = ktime_sub(now, STp->stats->other_time);
510 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
511 		atomic64_inc(&STp->stats->other_cnt);
512 	}
513 	atomic64_dec(&STp->stats->in_flight);
514 }
515 
516 static void st_scsi_execute_end(struct request *req, blk_status_t status)
517 {
518 	struct st_request *SRpnt = req->end_io_data;
519 	struct scsi_request *rq = scsi_req(req);
520 	struct scsi_tape *STp = SRpnt->stp;
521 	struct bio *tmp;
522 
523 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = rq->result;
524 	STp->buffer->cmdstat.residual = rq->resid_len;
525 
526 	st_do_stats(STp, req);
527 
528 	tmp = SRpnt->bio;
529 	if (rq->sense_len)
530 		memcpy(SRpnt->sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
531 	if (SRpnt->waiting)
532 		complete(SRpnt->waiting);
533 
534 	blk_rq_unmap_user(tmp);
535 	blk_put_request(req);
536 }
537 
538 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
539 			   int data_direction, void *buffer, unsigned bufflen,
540 			   int timeout, int retries)
541 {
542 	struct request *req;
543 	struct scsi_request *rq;
544 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
545 	int err = 0;
546 	struct scsi_tape *STp = SRpnt->stp;
547 
548 	req = blk_get_request(SRpnt->stp->device->request_queue,
549 			data_direction == DMA_TO_DEVICE ?
550 			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
551 	if (IS_ERR(req))
552 		return DRIVER_ERROR << 24;
553 	rq = scsi_req(req);
554 	req->rq_flags |= RQF_QUIET;
555 
556 	mdata->null_mapped = 1;
557 
558 	if (bufflen) {
559 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
560 				      GFP_KERNEL);
561 		if (err) {
562 			blk_put_request(req);
563 			return DRIVER_ERROR << 24;
564 		}
565 	}
566 
567 	atomic64_inc(&STp->stats->in_flight);
568 	if (cmd[0] == WRITE_6) {
569 		atomic_set(&STp->stats->last_write_size, bufflen);
570 		STp->stats->write_time = ktime_get();
571 	} else if (cmd[0] == READ_6) {
572 		atomic_set(&STp->stats->last_read_size, bufflen);
573 		STp->stats->read_time = ktime_get();
574 	} else {
575 		STp->stats->other_time = ktime_get();
576 	}
577 
578 	SRpnt->bio = req->bio;
579 	rq->cmd_len = COMMAND_SIZE(cmd[0]);
580 	memset(rq->cmd, 0, BLK_MAX_CDB);
581 	memcpy(rq->cmd, cmd, rq->cmd_len);
582 	req->timeout = timeout;
583 	rq->retries = retries;
584 	req->end_io_data = SRpnt;
585 
586 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
587 	return 0;
588 }
589 
590 /* Do the scsi command. Waits until command performed if do_wait is true.
591    Otherwise write_behind_check() is used to check that the command
592    has finished. */
593 static struct st_request *
594 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
595 	   int bytes, int direction, int timeout, int retries, int do_wait)
596 {
597 	struct completion *waiting;
598 	struct rq_map_data *mdata = &STp->buffer->map_data;
599 	int ret;
600 
601 	/* if async, make sure there's no command outstanding */
602 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
603 		st_printk(KERN_ERR, STp,
604 			  "Async command already active.\n");
605 		if (signal_pending(current))
606 			(STp->buffer)->syscall_result = (-EINTR);
607 		else
608 			(STp->buffer)->syscall_result = (-EBUSY);
609 		return NULL;
610 	}
611 
612 	if (!SRpnt) {
613 		SRpnt = st_allocate_request(STp);
614 		if (!SRpnt)
615 			return NULL;
616 	}
617 
618 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
619 	   which IO is outstanding. It's nulled out when the IO completes. */
620 	if (!do_wait)
621 		(STp->buffer)->last_SRpnt = SRpnt;
622 
623 	waiting = &STp->wait;
624 	init_completion(waiting);
625 	SRpnt->waiting = waiting;
626 
627 	if (STp->buffer->do_dio) {
628 		mdata->page_order = 0;
629 		mdata->nr_entries = STp->buffer->sg_segs;
630 		mdata->pages = STp->buffer->mapped_pages;
631 	} else {
632 		mdata->page_order = STp->buffer->reserved_page_order;
633 		mdata->nr_entries =
634 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
635 		mdata->pages = STp->buffer->reserved_pages;
636 		mdata->offset = 0;
637 	}
638 
639 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
640 	STp->buffer->cmdstat.have_sense = 0;
641 	STp->buffer->syscall_result = 0;
642 
643 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
644 			      retries);
645 	if (ret) {
646 		/* could not allocate the buffer or request was too large */
647 		(STp->buffer)->syscall_result = (-EBUSY);
648 		(STp->buffer)->last_SRpnt = NULL;
649 	} else if (do_wait) {
650 		wait_for_completion(waiting);
651 		SRpnt->waiting = NULL;
652 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
653 	}
654 
655 	return SRpnt;
656 }
657 
658 
659 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
660    write has been correct but EOM early warning reached, -EIO if write ended in
661    error or zero if write successful. Asynchronous writes are used only in
662    variable block mode. */
663 static int write_behind_check(struct scsi_tape * STp)
664 {
665 	int retval = 0;
666 	struct st_buffer *STbuffer;
667 	struct st_partstat *STps;
668 	struct st_cmdstatus *cmdstatp;
669 	struct st_request *SRpnt;
670 
671 	STbuffer = STp->buffer;
672 	if (!STbuffer->writing)
673 		return 0;
674 
675 	DEB(
676 	if (STp->write_pending)
677 		STp->nbr_waits++;
678 	else
679 		STp->nbr_finished++;
680 	) /* end DEB */
681 
682 	wait_for_completion(&(STp->wait));
683 	SRpnt = STbuffer->last_SRpnt;
684 	STbuffer->last_SRpnt = NULL;
685 	SRpnt->waiting = NULL;
686 
687 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
688 	st_release_request(SRpnt);
689 
690 	STbuffer->buffer_bytes -= STbuffer->writing;
691 	STps = &(STp->ps[STp->partition]);
692 	if (STps->drv_block >= 0) {
693 		if (STp->block_size == 0)
694 			STps->drv_block++;
695 		else
696 			STps->drv_block += STbuffer->writing / STp->block_size;
697 	}
698 
699 	cmdstatp = &STbuffer->cmdstat;
700 	if (STbuffer->syscall_result) {
701 		retval = -EIO;
702 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
703 		    (cmdstatp->flags & SENSE_EOM) &&
704 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
705 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
706 			/* EOM at write-behind, has all data been written? */
707 			if (!cmdstatp->remainder_valid ||
708 			    cmdstatp->uremainder64 == 0)
709 				retval = -ENOSPC;
710 		}
711 		if (retval == -EIO)
712 			STps->drv_block = -1;
713 	}
714 	STbuffer->writing = 0;
715 
716 	DEB(if (debugging && retval)
717 		    st_printk(ST_DEB_MSG, STp,
718 				"Async write error %x, return value %d.\n",
719 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
720 
721 	return retval;
722 }
723 
724 
725 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
726    it messes up the block number). */
727 static int cross_eof(struct scsi_tape * STp, int forward)
728 {
729 	struct st_request *SRpnt;
730 	unsigned char cmd[MAX_COMMAND_SIZE];
731 
732 	cmd[0] = SPACE;
733 	cmd[1] = 0x01;		/* Space FileMarks */
734 	if (forward) {
735 		cmd[2] = cmd[3] = 0;
736 		cmd[4] = 1;
737 	} else
738 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
739 	cmd[5] = 0;
740 
741 	DEBC_printk(STp, "Stepping over filemark %s.\n",
742 		    forward ? "forward" : "backward");
743 
744 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
745 			   STp->device->request_queue->rq_timeout,
746 			   MAX_RETRIES, 1);
747 	if (!SRpnt)
748 		return (STp->buffer)->syscall_result;
749 
750 	st_release_request(SRpnt);
751 	SRpnt = NULL;
752 
753 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
754 		st_printk(KERN_ERR, STp,
755 			  "Stepping over filemark %s failed.\n",
756 			  forward ? "forward" : "backward");
757 
758 	return (STp->buffer)->syscall_result;
759 }
760 
761 
762 /* Flush the write buffer (never need to write if variable blocksize). */
763 static int st_flush_write_buffer(struct scsi_tape * STp)
764 {
765 	int transfer, blks;
766 	int result;
767 	unsigned char cmd[MAX_COMMAND_SIZE];
768 	struct st_request *SRpnt;
769 	struct st_partstat *STps;
770 
771 	result = write_behind_check(STp);
772 	if (result)
773 		return result;
774 
775 	result = 0;
776 	if (STp->dirty == 1) {
777 
778 		transfer = STp->buffer->buffer_bytes;
779 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
780 
781 		memset(cmd, 0, MAX_COMMAND_SIZE);
782 		cmd[0] = WRITE_6;
783 		cmd[1] = 1;
784 		blks = transfer / STp->block_size;
785 		cmd[2] = blks >> 16;
786 		cmd[3] = blks >> 8;
787 		cmd[4] = blks;
788 
789 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
790 				   STp->device->request_queue->rq_timeout,
791 				   MAX_WRITE_RETRIES, 1);
792 		if (!SRpnt)
793 			return (STp->buffer)->syscall_result;
794 
795 		STps = &(STp->ps[STp->partition]);
796 		if ((STp->buffer)->syscall_result != 0) {
797 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
798 
799 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
800 			    (cmdstatp->flags & SENSE_EOM) &&
801 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
802 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
803 			    (!cmdstatp->remainder_valid ||
804 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
805 				STp->dirty = 0;
806 				(STp->buffer)->buffer_bytes = 0;
807 				if (STps->drv_block >= 0)
808 					STps->drv_block += blks;
809 				result = (-ENOSPC);
810 			} else {
811 				st_printk(KERN_ERR, STp, "Error on flush.\n");
812 				STps->drv_block = (-1);
813 				result = (-EIO);
814 			}
815 		} else {
816 			if (STps->drv_block >= 0)
817 				STps->drv_block += blks;
818 			STp->dirty = 0;
819 			(STp->buffer)->buffer_bytes = 0;
820 		}
821 		st_release_request(SRpnt);
822 		SRpnt = NULL;
823 	}
824 	return result;
825 }
826 
827 
828 /* Flush the tape buffer. The tape will be positioned correctly unless
829    seek_next is true. */
830 static int flush_buffer(struct scsi_tape *STp, int seek_next)
831 {
832 	int backspace, result;
833 	struct st_partstat *STps;
834 
835 	/*
836 	 * If there was a bus reset, block further access
837 	 * to this device.
838 	 */
839 	if (STp->pos_unknown)
840 		return (-EIO);
841 
842 	if (STp->ready != ST_READY)
843 		return 0;
844 	STps = &(STp->ps[STp->partition]);
845 	if (STps->rw == ST_WRITING)	/* Writing */
846 		return st_flush_write_buffer(STp);
847 
848 	if (STp->block_size == 0)
849 		return 0;
850 
851 	backspace = ((STp->buffer)->buffer_bytes +
852 		     (STp->buffer)->read_pointer) / STp->block_size -
853 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
854 	    STp->block_size;
855 	(STp->buffer)->buffer_bytes = 0;
856 	(STp->buffer)->read_pointer = 0;
857 	result = 0;
858 	if (!seek_next) {
859 		if (STps->eof == ST_FM_HIT) {
860 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
861 			if (!result)
862 				STps->eof = ST_NOEOF;
863 			else {
864 				if (STps->drv_file >= 0)
865 					STps->drv_file++;
866 				STps->drv_block = 0;
867 			}
868 		}
869 		if (!result && backspace > 0)
870 			result = st_int_ioctl(STp, MTBSR, backspace);
871 	} else if (STps->eof == ST_FM_HIT) {
872 		if (STps->drv_file >= 0)
873 			STps->drv_file++;
874 		STps->drv_block = 0;
875 		STps->eof = ST_NOEOF;
876 	}
877 	return result;
878 
879 }
880 
881 /* Set the mode parameters */
882 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
883 {
884 	int set_it = 0;
885 	unsigned long arg;
886 
887 	if (!STp->density_changed &&
888 	    STm->default_density >= 0 &&
889 	    STm->default_density != STp->density) {
890 		arg = STm->default_density;
891 		set_it = 1;
892 	} else
893 		arg = STp->density;
894 	arg <<= MT_ST_DENSITY_SHIFT;
895 	if (!STp->blksize_changed &&
896 	    STm->default_blksize >= 0 &&
897 	    STm->default_blksize != STp->block_size) {
898 		arg |= STm->default_blksize;
899 		set_it = 1;
900 	} else
901 		arg |= STp->block_size;
902 	if (set_it &&
903 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
904 		st_printk(KERN_WARNING, STp,
905 			  "Can't set default block size to %d bytes "
906 			  "and density %x.\n",
907 			  STm->default_blksize, STm->default_density);
908 		if (modes_defined)
909 			return (-EINVAL);
910 	}
911 	return 0;
912 }
913 
914 
915 /* Lock or unlock the drive door. Don't use when st_request allocated. */
916 static int do_door_lock(struct scsi_tape * STp, int do_lock)
917 {
918 	int retval;
919 
920 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
921 
922 	retval = scsi_set_medium_removal(STp->device,
923 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
924 	if (!retval)
925 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
926 	else
927 		STp->door_locked = ST_LOCK_FAILS;
928 	return retval;
929 }
930 
931 
932 /* Set the internal state after reset */
933 static void reset_state(struct scsi_tape *STp)
934 {
935 	int i;
936 	struct st_partstat *STps;
937 
938 	STp->pos_unknown = 0;
939 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
940 		STps = &(STp->ps[i]);
941 		STps->rw = ST_IDLE;
942 		STps->eof = ST_NOEOF;
943 		STps->at_sm = 0;
944 		STps->last_block_valid = 0;
945 		STps->drv_block = -1;
946 		STps->drv_file = -1;
947 	}
948 	if (STp->can_partitions) {
949 		STp->partition = find_partition(STp);
950 		if (STp->partition < 0)
951 			STp->partition = 0;
952 		STp->new_partition = STp->partition;
953 	}
954 }
955 
956 /* Test if the drive is ready. Returns either one of the codes below or a negative system
957    error code. */
958 #define CHKRES_READY       0
959 #define CHKRES_NEW_SESSION 1
960 #define CHKRES_NOT_READY   2
961 #define CHKRES_NO_TAPE     3
962 
963 #define MAX_ATTENTIONS    10
964 
965 static int test_ready(struct scsi_tape *STp, int do_wait)
966 {
967 	int attentions, waits, max_wait, scode;
968 	int retval = CHKRES_READY, new_session = 0;
969 	unsigned char cmd[MAX_COMMAND_SIZE];
970 	struct st_request *SRpnt = NULL;
971 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
972 
973 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
974 
975 	for (attentions=waits=0; ; ) {
976 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
977 		cmd[0] = TEST_UNIT_READY;
978 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
979 				   STp->long_timeout, MAX_READY_RETRIES, 1);
980 
981 		if (!SRpnt) {
982 			retval = (STp->buffer)->syscall_result;
983 			break;
984 		}
985 
986 		if (cmdstatp->have_sense) {
987 
988 			scode = cmdstatp->sense_hdr.sense_key;
989 
990 			if (scode == UNIT_ATTENTION) { /* New media? */
991 				new_session = 1;
992 				if (attentions < MAX_ATTENTIONS) {
993 					attentions++;
994 					continue;
995 				}
996 				else {
997 					retval = (-EIO);
998 					break;
999 				}
1000 			}
1001 
1002 			if (scode == NOT_READY) {
1003 				if (waits < max_wait) {
1004 					if (msleep_interruptible(1000)) {
1005 						retval = (-EINTR);
1006 						break;
1007 					}
1008 					waits++;
1009 					continue;
1010 				}
1011 				else {
1012 					if ((STp->device)->scsi_level >= SCSI_2 &&
1013 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1014 						retval = CHKRES_NO_TAPE;
1015 					else
1016 						retval = CHKRES_NOT_READY;
1017 					break;
1018 				}
1019 			}
1020 		}
1021 
1022 		retval = (STp->buffer)->syscall_result;
1023 		if (!retval)
1024 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1025 		break;
1026 	}
1027 
1028 	if (SRpnt != NULL)
1029 		st_release_request(SRpnt);
1030 	return retval;
1031 }
1032 
1033 
1034 /* See if the drive is ready and gather information about the tape. Return values:
1035    < 0   negative error code from errno.h
1036    0     drive ready
1037    1     drive not ready (possibly no tape)
1038 */
1039 static int check_tape(struct scsi_tape *STp, struct file *filp)
1040 {
1041 	int i, retval, new_session = 0, do_wait;
1042 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1043 	unsigned short st_flags = filp->f_flags;
1044 	struct st_request *SRpnt = NULL;
1045 	struct st_modedef *STm;
1046 	struct st_partstat *STps;
1047 	struct inode *inode = file_inode(filp);
1048 	int mode = TAPE_MODE(inode);
1049 
1050 	STp->ready = ST_READY;
1051 
1052 	if (mode != STp->current_mode) {
1053 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1054 			    STp->current_mode, mode);
1055 		new_session = 1;
1056 		STp->current_mode = mode;
1057 	}
1058 	STm = &(STp->modes[STp->current_mode]);
1059 
1060 	saved_cleaning = STp->cleaning_req;
1061 	STp->cleaning_req = 0;
1062 
1063 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1064 	retval = test_ready(STp, do_wait);
1065 
1066 	if (retval < 0)
1067 	    goto err_out;
1068 
1069 	if (retval == CHKRES_NEW_SESSION) {
1070 		STp->pos_unknown = 0;
1071 		STp->partition = STp->new_partition = 0;
1072 		if (STp->can_partitions)
1073 			STp->nbr_partitions = 1; /* This guess will be updated later
1074                                                     if necessary */
1075 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1076 			STps = &(STp->ps[i]);
1077 			STps->rw = ST_IDLE;
1078 			STps->eof = ST_NOEOF;
1079 			STps->at_sm = 0;
1080 			STps->last_block_valid = 0;
1081 			STps->drv_block = 0;
1082 			STps->drv_file = 0;
1083 		}
1084 		new_session = 1;
1085 	}
1086 	else {
1087 		STp->cleaning_req |= saved_cleaning;
1088 
1089 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1090 			if (retval == CHKRES_NO_TAPE)
1091 				STp->ready = ST_NO_TAPE;
1092 			else
1093 				STp->ready = ST_NOT_READY;
1094 
1095 			STp->density = 0;	/* Clear the erroneous "residue" */
1096 			STp->write_prot = 0;
1097 			STp->block_size = 0;
1098 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1099 			STp->partition = STp->new_partition = 0;
1100 			STp->door_locked = ST_UNLOCKED;
1101 			return CHKRES_NOT_READY;
1102 		}
1103 	}
1104 
1105 	if (STp->omit_blklims)
1106 		STp->min_block = STp->max_block = (-1);
1107 	else {
1108 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1109 		cmd[0] = READ_BLOCK_LIMITS;
1110 
1111 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1112 				   STp->device->request_queue->rq_timeout,
1113 				   MAX_READY_RETRIES, 1);
1114 		if (!SRpnt) {
1115 			retval = (STp->buffer)->syscall_result;
1116 			goto err_out;
1117 		}
1118 
1119 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1120 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1121 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1122 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1123 			    (STp->buffer)->b_data[5];
1124 			if ( DEB( debugging || ) !STp->inited)
1125 				st_printk(KERN_INFO, STp,
1126 					  "Block limits %d - %d bytes.\n",
1127 					  STp->min_block, STp->max_block);
1128 		} else {
1129 			STp->min_block = STp->max_block = (-1);
1130 			DEBC_printk(STp, "Can't read block limits.\n");
1131 		}
1132 	}
1133 
1134 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1135 	cmd[0] = MODE_SENSE;
1136 	cmd[4] = 12;
1137 
1138 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1139 			   STp->device->request_queue->rq_timeout,
1140 			   MAX_READY_RETRIES, 1);
1141 	if (!SRpnt) {
1142 		retval = (STp->buffer)->syscall_result;
1143 		goto err_out;
1144 	}
1145 
1146 	if ((STp->buffer)->syscall_result != 0) {
1147 		DEBC_printk(STp, "No Mode Sense.\n");
1148 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1149 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1150 		STp->drv_write_prot = 0;
1151 	} else {
1152 		DEBC_printk(STp,"Mode sense. Length %d, "
1153 			    "medium %x, WBS %x, BLL %d\n",
1154 			    (STp->buffer)->b_data[0],
1155 			    (STp->buffer)->b_data[1],
1156 			    (STp->buffer)->b_data[2],
1157 			    (STp->buffer)->b_data[3]);
1158 
1159 		if ((STp->buffer)->b_data[3] >= 8) {
1160 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1161 			STp->density = (STp->buffer)->b_data[4];
1162 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1163 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1164 			DEBC_printk(STp, "Density %x, tape length: %x, "
1165 				    "drv buffer: %d\n",
1166 				    STp->density,
1167 				    (STp->buffer)->b_data[5] * 65536 +
1168 				    (STp->buffer)->b_data[6] * 256 +
1169 				    (STp->buffer)->b_data[7],
1170 				    STp->drv_buffer);
1171 		}
1172 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1173 		if (!STp->drv_buffer && STp->immediate_filemark) {
1174 			st_printk(KERN_WARNING, STp,
1175 				  "non-buffered tape: disabling "
1176 				  "writing immediate filemarks\n");
1177 			STp->immediate_filemark = 0;
1178 		}
1179 	}
1180 	st_release_request(SRpnt);
1181 	SRpnt = NULL;
1182 	STp->inited = 1;
1183 
1184 	if (STp->block_size > 0)
1185 		(STp->buffer)->buffer_blocks =
1186 			(STp->buffer)->buffer_size / STp->block_size;
1187 	else
1188 		(STp->buffer)->buffer_blocks = 1;
1189 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1190 
1191 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1192 		    STp->block_size, (STp->buffer)->buffer_size,
1193 		    (STp->buffer)->buffer_blocks);
1194 
1195 	if (STp->drv_write_prot) {
1196 		STp->write_prot = 1;
1197 
1198 		DEBC_printk(STp, "Write protected\n");
1199 
1200 		if (do_wait &&
1201 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1202 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1203 			retval = (-EROFS);
1204 			goto err_out;
1205 		}
1206 	}
1207 
1208 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1209 		/* This code is reached when the device is opened for the first time
1210 		   after the driver has been initialized with tape in the drive and the
1211 		   partition support has been enabled. */
1212 		DEBC_printk(STp, "Updating partition number in status.\n");
1213 		if ((STp->partition = find_partition(STp)) < 0) {
1214 			retval = STp->partition;
1215 			goto err_out;
1216 		}
1217 		STp->new_partition = STp->partition;
1218 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1219 	}
1220 
1221 	if (new_session) {	/* Change the drive parameters for the new mode */
1222 		STp->density_changed = STp->blksize_changed = 0;
1223 		STp->compression_changed = 0;
1224 		if (!(STm->defaults_for_writes) &&
1225 		    (retval = set_mode_densblk(STp, STm)) < 0)
1226 		    goto err_out;
1227 
1228 		if (STp->default_drvbuffer != 0xff) {
1229 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1230 				st_printk(KERN_WARNING, STp,
1231 					  "Can't set default drive "
1232 					  "buffering to %d.\n",
1233 					  STp->default_drvbuffer);
1234 		}
1235 	}
1236 
1237 	return CHKRES_READY;
1238 
1239  err_out:
1240 	return retval;
1241 }
1242 
1243 
1244 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1245    module count. */
1246 static int st_open(struct inode *inode, struct file *filp)
1247 {
1248 	int i, retval = (-EIO);
1249 	int resumed = 0;
1250 	struct scsi_tape *STp;
1251 	struct st_partstat *STps;
1252 	int dev = TAPE_NR(inode);
1253 
1254 	/*
1255 	 * We really want to do nonseekable_open(inode, filp); here, but some
1256 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1257 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1258 	 */
1259 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1260 
1261 	if (!(STp = scsi_tape_get(dev))) {
1262 		return -ENXIO;
1263 	}
1264 
1265 	filp->private_data = STp;
1266 
1267 	spin_lock(&st_use_lock);
1268 	if (STp->in_use) {
1269 		spin_unlock(&st_use_lock);
1270 		scsi_tape_put(STp);
1271 		DEBC_printk(STp, "Device already in use.\n");
1272 		return (-EBUSY);
1273 	}
1274 
1275 	STp->in_use = 1;
1276 	spin_unlock(&st_use_lock);
1277 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1278 
1279 	if (scsi_autopm_get_device(STp->device) < 0) {
1280 		retval = -EIO;
1281 		goto err_out;
1282 	}
1283 	resumed = 1;
1284 	if (!scsi_block_when_processing_errors(STp->device)) {
1285 		retval = (-ENXIO);
1286 		goto err_out;
1287 	}
1288 
1289 	/* See that we have at least a one page buffer available */
1290 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
1291 		st_printk(KERN_WARNING, STp,
1292 			  "Can't allocate one page tape buffer.\n");
1293 		retval = (-EOVERFLOW);
1294 		goto err_out;
1295 	}
1296 
1297 	(STp->buffer)->cleared = 0;
1298 	(STp->buffer)->writing = 0;
1299 	(STp->buffer)->syscall_result = 0;
1300 
1301 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1302 
1303 	STp->dirty = 0;
1304 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1305 		STps = &(STp->ps[i]);
1306 		STps->rw = ST_IDLE;
1307 	}
1308 	STp->try_dio_now = STp->try_dio;
1309 	STp->recover_count = 0;
1310 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1311 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1312 
1313 	retval = check_tape(STp, filp);
1314 	if (retval < 0)
1315 		goto err_out;
1316 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1317 	    retval != CHKRES_READY) {
1318 		if (STp->ready == NO_TAPE)
1319 			retval = (-ENOMEDIUM);
1320 		else
1321 			retval = (-EIO);
1322 		goto err_out;
1323 	}
1324 	return 0;
1325 
1326  err_out:
1327 	normalize_buffer(STp->buffer);
1328 	spin_lock(&st_use_lock);
1329 	STp->in_use = 0;
1330 	spin_unlock(&st_use_lock);
1331 	if (resumed)
1332 		scsi_autopm_put_device(STp->device);
1333 	scsi_tape_put(STp);
1334 	return retval;
1335 
1336 }
1337 
1338 
1339 /* Flush the tape buffer before close */
1340 static int st_flush(struct file *filp, fl_owner_t id)
1341 {
1342 	int result = 0, result2;
1343 	unsigned char cmd[MAX_COMMAND_SIZE];
1344 	struct st_request *SRpnt;
1345 	struct scsi_tape *STp = filp->private_data;
1346 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1347 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1348 
1349 	if (file_count(filp) > 1)
1350 		return 0;
1351 
1352 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1353 		result = st_flush_write_buffer(STp);
1354 		if (result != 0 && result != (-ENOSPC))
1355 			goto out;
1356 	}
1357 
1358 	if (STp->can_partitions &&
1359 	    (result2 = switch_partition(STp)) < 0) {
1360 		DEBC_printk(STp, "switch_partition at close failed.\n");
1361 		if (result == 0)
1362 			result = result2;
1363 		goto out;
1364 	}
1365 
1366 	DEBC( if (STp->nbr_requests)
1367 		st_printk(KERN_DEBUG, STp,
1368 			  "Number of r/w requests %d, dio used in %d, "
1369 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1370 			  STp->nbr_pages));
1371 
1372 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1373 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1374 
1375 #if DEBUG
1376 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1377 			    STp->nbr_waits, STp->nbr_finished);
1378 #endif
1379 		memset(cmd, 0, MAX_COMMAND_SIZE);
1380 		cmd[0] = WRITE_FILEMARKS;
1381 		if (STp->immediate_filemark)
1382 			cmd[1] = 1;
1383 		cmd[4] = 1 + STp->two_fm;
1384 
1385 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1386 				   STp->device->request_queue->rq_timeout,
1387 				   MAX_WRITE_RETRIES, 1);
1388 		if (!SRpnt) {
1389 			result = (STp->buffer)->syscall_result;
1390 			goto out;
1391 		}
1392 
1393 		if (STp->buffer->syscall_result == 0 ||
1394 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1395 		     (cmdstatp->flags & SENSE_EOM) &&
1396 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1397 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1398 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1399 			/* Write successful at EOM */
1400 			st_release_request(SRpnt);
1401 			SRpnt = NULL;
1402 			if (STps->drv_file >= 0)
1403 				STps->drv_file++;
1404 			STps->drv_block = 0;
1405 			if (STp->two_fm)
1406 				cross_eof(STp, 0);
1407 			STps->eof = ST_FM;
1408 		}
1409 		else { /* Write error */
1410 			st_release_request(SRpnt);
1411 			SRpnt = NULL;
1412 			st_printk(KERN_ERR, STp,
1413 				  "Error on write filemark.\n");
1414 			if (result == 0)
1415 				result = (-EIO);
1416 		}
1417 
1418 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1419 	} else if (!STp->rew_at_close) {
1420 		STps = &(STp->ps[STp->partition]);
1421 		if (!STm->sysv || STps->rw != ST_READING) {
1422 			if (STp->can_bsr)
1423 				result = flush_buffer(STp, 0);
1424 			else if (STps->eof == ST_FM_HIT) {
1425 				result = cross_eof(STp, 0);
1426 				if (result) {
1427 					if (STps->drv_file >= 0)
1428 						STps->drv_file++;
1429 					STps->drv_block = 0;
1430 					STps->eof = ST_FM;
1431 				} else
1432 					STps->eof = ST_NOEOF;
1433 			}
1434 		} else if ((STps->eof == ST_NOEOF &&
1435 			    !(result = cross_eof(STp, 1))) ||
1436 			   STps->eof == ST_FM_HIT) {
1437 			if (STps->drv_file >= 0)
1438 				STps->drv_file++;
1439 			STps->drv_block = 0;
1440 			STps->eof = ST_FM;
1441 		}
1442 	}
1443 
1444       out:
1445 	if (STp->rew_at_close) {
1446 		result2 = st_int_ioctl(STp, MTREW, 1);
1447 		if (result == 0)
1448 			result = result2;
1449 	}
1450 	return result;
1451 }
1452 
1453 
1454 /* Close the device and release it. BKL is not needed: this is the only thread
1455    accessing this tape. */
1456 static int st_release(struct inode *inode, struct file *filp)
1457 {
1458 	int result = 0;
1459 	struct scsi_tape *STp = filp->private_data;
1460 
1461 	if (STp->door_locked == ST_LOCKED_AUTO)
1462 		do_door_lock(STp, 0);
1463 
1464 	normalize_buffer(STp->buffer);
1465 	spin_lock(&st_use_lock);
1466 	STp->in_use = 0;
1467 	spin_unlock(&st_use_lock);
1468 	scsi_autopm_put_device(STp->device);
1469 	scsi_tape_put(STp);
1470 
1471 	return result;
1472 }
1473 
1474 /* The checks common to both reading and writing */
1475 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1476 {
1477 	ssize_t retval = 0;
1478 
1479 	/*
1480 	 * If we are in the middle of error recovery, don't let anyone
1481 	 * else try and use this device.  Also, if error recovery fails, it
1482 	 * may try and take the device offline, in which case all further
1483 	 * access to the device is prohibited.
1484 	 */
1485 	if (!scsi_block_when_processing_errors(STp->device)) {
1486 		retval = (-ENXIO);
1487 		goto out;
1488 	}
1489 
1490 	if (STp->ready != ST_READY) {
1491 		if (STp->ready == ST_NO_TAPE)
1492 			retval = (-ENOMEDIUM);
1493 		else
1494 			retval = (-EIO);
1495 		goto out;
1496 	}
1497 
1498 	if (! STp->modes[STp->current_mode].defined) {
1499 		retval = (-ENXIO);
1500 		goto out;
1501 	}
1502 
1503 
1504 	/*
1505 	 * If there was a bus reset, block further access
1506 	 * to this device.
1507 	 */
1508 	if (STp->pos_unknown) {
1509 		retval = (-EIO);
1510 		goto out;
1511 	}
1512 
1513 	if (count == 0)
1514 		goto out;
1515 
1516 	DEB(
1517 	if (!STp->in_use) {
1518 		st_printk(ST_DEB_MSG, STp,
1519 			  "Incorrect device.\n");
1520 		retval = (-EIO);
1521 		goto out;
1522 	} ) /* end DEB */
1523 
1524 	if (STp->can_partitions &&
1525 	    (retval = switch_partition(STp)) < 0)
1526 		goto out;
1527 
1528 	if (STp->block_size == 0 && STp->max_block > 0 &&
1529 	    (count < STp->min_block || count > STp->max_block)) {
1530 		retval = (-EINVAL);
1531 		goto out;
1532 	}
1533 
1534 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1535 	    !do_door_lock(STp, 1))
1536 		STp->door_locked = ST_LOCKED_AUTO;
1537 
1538  out:
1539 	return retval;
1540 }
1541 
1542 
1543 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1544 			   size_t count, int is_read)
1545 {
1546 	int i, bufsize, retval = 0;
1547 	struct st_buffer *STbp = STp->buffer;
1548 
1549 	if (is_read)
1550 		i = STp->try_dio_now && try_rdio;
1551 	else
1552 		i = STp->try_dio_now && try_wdio;
1553 
1554 	if (i && ((unsigned long)buf & queue_dma_alignment(
1555 					STp->device->request_queue)) == 0) {
1556 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1557 				       count, (is_read ? READ : WRITE));
1558 		if (i > 0) {
1559 			STbp->do_dio = i;
1560 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1561 		}
1562 		else
1563 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1564 		STbp->sg_segs = STbp->do_dio;
1565 		DEB(
1566 		     if (STbp->do_dio) {
1567 			STp->nbr_dio++;
1568 			STp->nbr_pages += STbp->do_dio;
1569 		     }
1570 		)
1571 	} else
1572 		STbp->do_dio = 0;
1573 	DEB( STp->nbr_requests++; )
1574 
1575 	if (!STbp->do_dio) {
1576 		if (STp->block_size)
1577 			bufsize = STp->block_size > st_fixed_buffer_size ?
1578 				STp->block_size : st_fixed_buffer_size;
1579 		else {
1580 			bufsize = count;
1581 			/* Make sure that data from previous user is not leaked even if
1582 			   HBA does not return correct residual */
1583 			if (is_read && STp->sili && !STbp->cleared)
1584 				clear_buffer(STbp);
1585 		}
1586 
1587 		if (bufsize > STbp->buffer_size &&
1588 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1589 			st_printk(KERN_WARNING, STp,
1590 				  "Can't allocate %d byte tape buffer.\n",
1591 				  bufsize);
1592 			retval = (-EOVERFLOW);
1593 			goto out;
1594 		}
1595 		if (STp->block_size)
1596 			STbp->buffer_blocks = bufsize / STp->block_size;
1597 	}
1598 
1599  out:
1600 	return retval;
1601 }
1602 
1603 
1604 /* Can be called more than once after each setup_buffer() */
1605 static void release_buffering(struct scsi_tape *STp, int is_read)
1606 {
1607 	struct st_buffer *STbp;
1608 
1609 	STbp = STp->buffer;
1610 	if (STbp->do_dio) {
1611 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1612 		STbp->do_dio = 0;
1613 		STbp->sg_segs = 0;
1614 	}
1615 }
1616 
1617 
1618 /* Write command */
1619 static ssize_t
1620 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1621 {
1622 	ssize_t total;
1623 	ssize_t i, do_count, blks, transfer;
1624 	ssize_t retval;
1625 	int undone, retry_eot = 0, scode;
1626 	int async_write;
1627 	unsigned char cmd[MAX_COMMAND_SIZE];
1628 	const char __user *b_point;
1629 	struct st_request *SRpnt = NULL;
1630 	struct scsi_tape *STp = filp->private_data;
1631 	struct st_modedef *STm;
1632 	struct st_partstat *STps;
1633 	struct st_buffer *STbp;
1634 
1635 	if (mutex_lock_interruptible(&STp->lock))
1636 		return -ERESTARTSYS;
1637 
1638 	retval = rw_checks(STp, filp, count);
1639 	if (retval || count == 0)
1640 		goto out;
1641 
1642 	/* Write must be integral number of blocks */
1643 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1644 		st_printk(KERN_WARNING, STp,
1645 			  "Write not multiple of tape block size.\n");
1646 		retval = (-EINVAL);
1647 		goto out;
1648 	}
1649 
1650 	STm = &(STp->modes[STp->current_mode]);
1651 	STps = &(STp->ps[STp->partition]);
1652 
1653 	if (STp->write_prot) {
1654 		retval = (-EACCES);
1655 		goto out;
1656 	}
1657 
1658 
1659 	if (STps->rw == ST_READING) {
1660 		retval = flush_buffer(STp, 0);
1661 		if (retval)
1662 			goto out;
1663 		STps->rw = ST_WRITING;
1664 	} else if (STps->rw != ST_WRITING &&
1665 		   STps->drv_file == 0 && STps->drv_block == 0) {
1666 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1667 			goto out;
1668 		if (STm->default_compression != ST_DONT_TOUCH &&
1669 		    !(STp->compression_changed)) {
1670 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1671 				st_printk(KERN_WARNING, STp,
1672 					  "Can't set default compression.\n");
1673 				if (modes_defined) {
1674 					retval = (-EINVAL);
1675 					goto out;
1676 				}
1677 			}
1678 		}
1679 	}
1680 
1681 	STbp = STp->buffer;
1682 	i = write_behind_check(STp);
1683 	if (i) {
1684 		if (i == -ENOSPC)
1685 			STps->eof = ST_EOM_OK;
1686 		else
1687 			STps->eof = ST_EOM_ERROR;
1688 	}
1689 
1690 	if (STps->eof == ST_EOM_OK) {
1691 		STps->eof = ST_EOD_1;  /* allow next write */
1692 		retval = (-ENOSPC);
1693 		goto out;
1694 	}
1695 	else if (STps->eof == ST_EOM_ERROR) {
1696 		retval = (-EIO);
1697 		goto out;
1698 	}
1699 
1700 	/* Check the buffer readability in cases where copy_user might catch
1701 	   the problems after some tape movement. */
1702 	if (STp->block_size != 0 &&
1703 	    !STbp->do_dio &&
1704 	    (copy_from_user(&i, buf, 1) != 0 ||
1705 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1706 		retval = (-EFAULT);
1707 		goto out;
1708 	}
1709 
1710 	retval = setup_buffering(STp, buf, count, 0);
1711 	if (retval)
1712 		goto out;
1713 
1714 	total = count;
1715 
1716 	memset(cmd, 0, MAX_COMMAND_SIZE);
1717 	cmd[0] = WRITE_6;
1718 	cmd[1] = (STp->block_size != 0);
1719 
1720 	STps->rw = ST_WRITING;
1721 
1722 	b_point = buf;
1723 	while (count > 0 && !retry_eot) {
1724 
1725 		if (STbp->do_dio) {
1726 			do_count = count;
1727 		}
1728 		else {
1729 			if (STp->block_size == 0)
1730 				do_count = count;
1731 			else {
1732 				do_count = STbp->buffer_blocks * STp->block_size -
1733 					STbp->buffer_bytes;
1734 				if (do_count > count)
1735 					do_count = count;
1736 			}
1737 
1738 			i = append_to_buffer(b_point, STbp, do_count);
1739 			if (i) {
1740 				retval = i;
1741 				goto out;
1742 			}
1743 		}
1744 		count -= do_count;
1745 		b_point += do_count;
1746 
1747 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1748 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1749 
1750 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1751 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1752 		    STbp->buffer_bytes < STbp->buffer_size) {
1753 			STp->dirty = 1;
1754 			/* Don't write a buffer that is not full enough. */
1755 			if (!async_write && count == 0)
1756 				break;
1757 		}
1758 
1759 	retry_write:
1760 		if (STp->block_size == 0)
1761 			blks = transfer = do_count;
1762 		else {
1763 			if (!STbp->do_dio)
1764 				blks = STbp->buffer_bytes;
1765 			else
1766 				blks = do_count;
1767 			blks /= STp->block_size;
1768 			transfer = blks * STp->block_size;
1769 		}
1770 		cmd[2] = blks >> 16;
1771 		cmd[3] = blks >> 8;
1772 		cmd[4] = blks;
1773 
1774 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1775 				   STp->device->request_queue->rq_timeout,
1776 				   MAX_WRITE_RETRIES, !async_write);
1777 		if (!SRpnt) {
1778 			retval = STbp->syscall_result;
1779 			goto out;
1780 		}
1781 		if (async_write && !STbp->syscall_result) {
1782 			STbp->writing = transfer;
1783 			STp->dirty = !(STbp->writing ==
1784 				       STbp->buffer_bytes);
1785 			SRpnt = NULL;  /* Prevent releasing this request! */
1786 			DEB( STp->write_pending = 1; )
1787 			break;
1788 		}
1789 
1790 		if (STbp->syscall_result != 0) {
1791 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1792 
1793 			DEBC_printk(STp, "Error on write:\n");
1794 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1795 				scode = cmdstatp->sense_hdr.sense_key;
1796 				if (cmdstatp->remainder_valid)
1797 					undone = (int)cmdstatp->uremainder64;
1798 				else if (STp->block_size == 0 &&
1799 					 scode == VOLUME_OVERFLOW)
1800 					undone = transfer;
1801 				else
1802 					undone = 0;
1803 				if (STp->block_size != 0)
1804 					undone *= STp->block_size;
1805 				if (undone <= do_count) {
1806 					/* Only data from this write is not written */
1807 					count += undone;
1808 					b_point -= undone;
1809 					do_count -= undone;
1810 					if (STp->block_size)
1811 						blks = (transfer - undone) / STp->block_size;
1812 					STps->eof = ST_EOM_OK;
1813 					/* Continue in fixed block mode if all written
1814 					   in this request but still something left to write
1815 					   (retval left to zero)
1816 					*/
1817 					if (STp->block_size == 0 ||
1818 					    undone > 0 || count == 0)
1819 						retval = (-ENOSPC); /* EOM within current request */
1820 					DEBC_printk(STp, "EOM with %d "
1821 						    "bytes unwritten.\n",
1822 						    (int)count);
1823 				} else {
1824 					/* EOT within data buffered earlier (possible only
1825 					   in fixed block mode without direct i/o) */
1826 					if (!retry_eot && !cmdstatp->deferred &&
1827 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1828 						move_buffer_data(STp->buffer, transfer - undone);
1829 						retry_eot = 1;
1830 						if (STps->drv_block >= 0) {
1831 							STps->drv_block += (transfer - undone) /
1832 								STp->block_size;
1833 						}
1834 						STps->eof = ST_EOM_OK;
1835 						DEBC_printk(STp, "Retry "
1836 							    "write of %d "
1837 							    "bytes at EOM.\n",
1838 							    STp->buffer->buffer_bytes);
1839 						goto retry_write;
1840 					}
1841 					else {
1842 						/* Either error within data buffered by driver or
1843 						   failed retry */
1844 						count -= do_count;
1845 						blks = do_count = 0;
1846 						STps->eof = ST_EOM_ERROR;
1847 						STps->drv_block = (-1); /* Too cautious? */
1848 						retval = (-EIO);	/* EOM for old data */
1849 						DEBC_printk(STp, "EOM with "
1850 							    "lost data.\n");
1851 					}
1852 				}
1853 			} else {
1854 				count += do_count;
1855 				STps->drv_block = (-1);		/* Too cautious? */
1856 				retval = STbp->syscall_result;
1857 			}
1858 
1859 		}
1860 
1861 		if (STps->drv_block >= 0) {
1862 			if (STp->block_size == 0)
1863 				STps->drv_block += (do_count > 0);
1864 			else
1865 				STps->drv_block += blks;
1866 		}
1867 
1868 		STbp->buffer_bytes = 0;
1869 		STp->dirty = 0;
1870 
1871 		if (retval || retry_eot) {
1872 			if (count < total)
1873 				retval = total - count;
1874 			goto out;
1875 		}
1876 	}
1877 
1878 	if (STps->eof == ST_EOD_1)
1879 		STps->eof = ST_EOM_OK;
1880 	else if (STps->eof != ST_EOM_OK)
1881 		STps->eof = ST_NOEOF;
1882 	retval = total - count;
1883 
1884  out:
1885 	if (SRpnt != NULL)
1886 		st_release_request(SRpnt);
1887 	release_buffering(STp, 0);
1888 	mutex_unlock(&STp->lock);
1889 
1890 	return retval;
1891 }
1892 
1893 /* Read data from the tape. Returns zero in the normal case, one if the
1894    eof status has changed, and the negative error code in case of a
1895    fatal error. Otherwise updates the buffer and the eof state.
1896 
1897    Does release user buffer mapping if it is set.
1898 */
1899 static long read_tape(struct scsi_tape *STp, long count,
1900 		      struct st_request ** aSRpnt)
1901 {
1902 	int transfer, blks, bytes;
1903 	unsigned char cmd[MAX_COMMAND_SIZE];
1904 	struct st_request *SRpnt;
1905 	struct st_modedef *STm;
1906 	struct st_partstat *STps;
1907 	struct st_buffer *STbp;
1908 	int retval = 0;
1909 
1910 	if (count == 0)
1911 		return 0;
1912 
1913 	STm = &(STp->modes[STp->current_mode]);
1914 	STps = &(STp->ps[STp->partition]);
1915 	if (STps->eof == ST_FM_HIT)
1916 		return 1;
1917 	STbp = STp->buffer;
1918 
1919 	if (STp->block_size == 0)
1920 		blks = bytes = count;
1921 	else {
1922 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1923 			blks = (STp->buffer)->buffer_blocks;
1924 			bytes = blks * STp->block_size;
1925 		} else {
1926 			bytes = count;
1927 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1928 				bytes = (STp->buffer)->buffer_size;
1929 			blks = bytes / STp->block_size;
1930 			bytes = blks * STp->block_size;
1931 		}
1932 	}
1933 
1934 	memset(cmd, 0, MAX_COMMAND_SIZE);
1935 	cmd[0] = READ_6;
1936 	cmd[1] = (STp->block_size != 0);
1937 	if (!cmd[1] && STp->sili)
1938 		cmd[1] |= 2;
1939 	cmd[2] = blks >> 16;
1940 	cmd[3] = blks >> 8;
1941 	cmd[4] = blks;
1942 
1943 	SRpnt = *aSRpnt;
1944 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1945 			   STp->device->request_queue->rq_timeout,
1946 			   MAX_RETRIES, 1);
1947 	release_buffering(STp, 1);
1948 	*aSRpnt = SRpnt;
1949 	if (!SRpnt)
1950 		return STbp->syscall_result;
1951 
1952 	STbp->read_pointer = 0;
1953 	STps->at_sm = 0;
1954 
1955 	/* Something to check */
1956 	if (STbp->syscall_result) {
1957 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1958 
1959 		retval = 1;
1960 		DEBC_printk(STp,
1961 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1962 			    SRpnt->sense[0], SRpnt->sense[1],
1963 			    SRpnt->sense[2], SRpnt->sense[3],
1964 			    SRpnt->sense[4], SRpnt->sense[5],
1965 			    SRpnt->sense[6], SRpnt->sense[7]);
1966 		if (cmdstatp->have_sense) {
1967 
1968 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1969 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1970 
1971 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1972 				/* Compute the residual count */
1973 				if (cmdstatp->remainder_valid)
1974 					transfer = (int)cmdstatp->uremainder64;
1975 				else
1976 					transfer = 0;
1977 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1978 					if (STp->block_size == 0)
1979 						transfer = bytes;
1980 					/* Some drives set ILI with MEDIUM ERROR */
1981 					cmdstatp->flags &= ~SENSE_ILI;
1982 				}
1983 
1984 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1985 					if (STp->block_size == 0 &&
1986 					    transfer < 0) {
1987 						st_printk(KERN_NOTICE, STp,
1988 							  "Failed to read %d "
1989 							  "byte block with %d "
1990 							  "byte transfer.\n",
1991 							  bytes - transfer,
1992 							  bytes);
1993 						if (STps->drv_block >= 0)
1994 							STps->drv_block += 1;
1995 						STbp->buffer_bytes = 0;
1996 						return (-ENOMEM);
1997 					} else if (STp->block_size == 0) {
1998 						STbp->buffer_bytes = bytes - transfer;
1999 					} else {
2000 						st_release_request(SRpnt);
2001 						SRpnt = *aSRpnt = NULL;
2002 						if (transfer == blks) {	/* We did not get anything, error */
2003 							st_printk(KERN_NOTICE, STp,
2004 								  "Incorrect "
2005 								  "block size.\n");
2006 							if (STps->drv_block >= 0)
2007 								STps->drv_block += blks - transfer + 1;
2008 							st_int_ioctl(STp, MTBSR, 1);
2009 							return (-EIO);
2010 						}
2011 						/* We have some data, deliver it */
2012 						STbp->buffer_bytes = (blks - transfer) *
2013 						    STp->block_size;
2014 						DEBC_printk(STp, "ILI but "
2015 							    "enough data "
2016 							    "received %ld "
2017 							    "%d.\n", count,
2018 							    STbp->buffer_bytes);
2019 						if (STps->drv_block >= 0)
2020 							STps->drv_block += 1;
2021 						if (st_int_ioctl(STp, MTBSR, 1))
2022 							return (-EIO);
2023 					}
2024 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2025 					if (STps->eof != ST_FM_HIT)
2026 						STps->eof = ST_FM_HIT;
2027 					else
2028 						STps->eof = ST_EOD_2;
2029 					if (STp->block_size == 0)
2030 						STbp->buffer_bytes = 0;
2031 					else
2032 						STbp->buffer_bytes =
2033 						    bytes - transfer * STp->block_size;
2034 					DEBC_printk(STp, "EOF detected (%d "
2035 						    "bytes read).\n",
2036 						    STbp->buffer_bytes);
2037 				} else if (cmdstatp->flags & SENSE_EOM) {
2038 					if (STps->eof == ST_FM)
2039 						STps->eof = ST_EOD_1;
2040 					else
2041 						STps->eof = ST_EOM_OK;
2042 					if (STp->block_size == 0)
2043 						STbp->buffer_bytes = bytes - transfer;
2044 					else
2045 						STbp->buffer_bytes =
2046 						    bytes - transfer * STp->block_size;
2047 
2048 					DEBC_printk(STp, "EOM detected (%d "
2049 						    "bytes read).\n",
2050 						    STbp->buffer_bytes);
2051 				}
2052 			}
2053 			/* end of EOF, EOM, ILI test */
2054 			else {	/* nonzero sense key */
2055 				DEBC_printk(STp, "Tape error while reading.\n");
2056 				STps->drv_block = (-1);
2057 				if (STps->eof == ST_FM &&
2058 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2059 					DEBC_printk(STp, "Zero returned for "
2060 						    "first BLANK CHECK "
2061 						    "after EOF.\n");
2062 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2063 				} else	/* Some other extended sense code */
2064 					retval = (-EIO);
2065 			}
2066 
2067 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2068 				STbp->buffer_bytes = 0;
2069 		}
2070 		/* End of extended sense test */
2071 		else {		/* Non-extended sense */
2072 			retval = STbp->syscall_result;
2073 		}
2074 
2075 	}
2076 	/* End of error handling */
2077 	else {			/* Read successful */
2078 		STbp->buffer_bytes = bytes;
2079 		if (STp->sili) /* In fixed block mode residual is always zero here */
2080 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2081 	}
2082 
2083 	if (STps->drv_block >= 0) {
2084 		if (STp->block_size == 0)
2085 			STps->drv_block++;
2086 		else
2087 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2088 	}
2089 	return retval;
2090 }
2091 
2092 
2093 /* Read command */
2094 static ssize_t
2095 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2096 {
2097 	ssize_t total;
2098 	ssize_t retval = 0;
2099 	ssize_t i, transfer;
2100 	int special, do_dio = 0;
2101 	struct st_request *SRpnt = NULL;
2102 	struct scsi_tape *STp = filp->private_data;
2103 	struct st_modedef *STm;
2104 	struct st_partstat *STps;
2105 	struct st_buffer *STbp = STp->buffer;
2106 
2107 	if (mutex_lock_interruptible(&STp->lock))
2108 		return -ERESTARTSYS;
2109 
2110 	retval = rw_checks(STp, filp, count);
2111 	if (retval || count == 0)
2112 		goto out;
2113 
2114 	STm = &(STp->modes[STp->current_mode]);
2115 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2116 		if (!STm->do_read_ahead) {
2117 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2118 			goto out;
2119 		}
2120 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2121 	}
2122 
2123 	STps = &(STp->ps[STp->partition]);
2124 	if (STps->rw == ST_WRITING) {
2125 		retval = flush_buffer(STp, 0);
2126 		if (retval)
2127 			goto out;
2128 		STps->rw = ST_READING;
2129 	}
2130 	DEB(
2131 	if (debugging && STps->eof != ST_NOEOF)
2132 		st_printk(ST_DEB_MSG, STp,
2133 			  "EOF/EOM flag up (%d). Bytes %d\n",
2134 			  STps->eof, STbp->buffer_bytes);
2135 	) /* end DEB */
2136 
2137 	retval = setup_buffering(STp, buf, count, 1);
2138 	if (retval)
2139 		goto out;
2140 	do_dio = STbp->do_dio;
2141 
2142 	if (STbp->buffer_bytes == 0 &&
2143 	    STps->eof >= ST_EOD_1) {
2144 		if (STps->eof < ST_EOD) {
2145 			STps->eof += 1;
2146 			retval = 0;
2147 			goto out;
2148 		}
2149 		retval = (-EIO);	/* EOM or Blank Check */
2150 		goto out;
2151 	}
2152 
2153 	if (do_dio) {
2154 		/* Check the buffer writability before any tape movement. Don't alter
2155 		   buffer data. */
2156 		if (copy_from_user(&i, buf, 1) != 0 ||
2157 		    copy_to_user(buf, &i, 1) != 0 ||
2158 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2159 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2160 			retval = (-EFAULT);
2161 			goto out;
2162 		}
2163 	}
2164 
2165 	STps->rw = ST_READING;
2166 
2167 
2168 	/* Loop until enough data in buffer or a special condition found */
2169 	for (total = 0, special = 0; total < count && !special;) {
2170 
2171 		/* Get new data if the buffer is empty */
2172 		if (STbp->buffer_bytes == 0) {
2173 			special = read_tape(STp, count - total, &SRpnt);
2174 			if (special < 0) {	/* No need to continue read */
2175 				retval = special;
2176 				goto out;
2177 			}
2178 		}
2179 
2180 		/* Move the data from driver buffer to user buffer */
2181 		if (STbp->buffer_bytes > 0) {
2182 			DEB(
2183 			if (debugging && STps->eof != ST_NOEOF)
2184 				st_printk(ST_DEB_MSG, STp,
2185 					  "EOF up (%d). Left %d, needed %d.\n",
2186 					  STps->eof, STbp->buffer_bytes,
2187 					  (int)(count - total));
2188 			) /* end DEB */
2189 			transfer = STbp->buffer_bytes < count - total ?
2190 			    STbp->buffer_bytes : count - total;
2191 			if (!do_dio) {
2192 				i = from_buffer(STbp, buf, transfer);
2193 				if (i) {
2194 					retval = i;
2195 					goto out;
2196 				}
2197 			}
2198 			buf += transfer;
2199 			total += transfer;
2200 		}
2201 
2202 		if (STp->block_size == 0)
2203 			break;	/* Read only one variable length block */
2204 
2205 	}			/* for (total = 0, special = 0;
2206                                    total < count && !special; ) */
2207 
2208 	/* Change the eof state if no data from tape or buffer */
2209 	if (total == 0) {
2210 		if (STps->eof == ST_FM_HIT) {
2211 			STps->eof = ST_FM;
2212 			STps->drv_block = 0;
2213 			if (STps->drv_file >= 0)
2214 				STps->drv_file++;
2215 		} else if (STps->eof == ST_EOD_1) {
2216 			STps->eof = ST_EOD_2;
2217 			STps->drv_block = 0;
2218 			if (STps->drv_file >= 0)
2219 				STps->drv_file++;
2220 		} else if (STps->eof == ST_EOD_2)
2221 			STps->eof = ST_EOD;
2222 	} else if (STps->eof == ST_FM)
2223 		STps->eof = ST_NOEOF;
2224 	retval = total;
2225 
2226  out:
2227 	if (SRpnt != NULL) {
2228 		st_release_request(SRpnt);
2229 		SRpnt = NULL;
2230 	}
2231 	if (do_dio) {
2232 		release_buffering(STp, 1);
2233 		STbp->buffer_bytes = 0;
2234 	}
2235 	mutex_unlock(&STp->lock);
2236 
2237 	return retval;
2238 }
2239 
2240 
2241 
2242 DEB(
2243 /* Set the driver options */
2244 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2245 {
2246 	if (debugging) {
2247 		st_printk(KERN_INFO, STp,
2248 			  "Mode %d options: buffer writes: %d, "
2249 			  "async writes: %d, read ahead: %d\n",
2250 			  STp->current_mode, STm->do_buffer_writes,
2251 			  STm->do_async_writes, STm->do_read_ahead);
2252 		st_printk(KERN_INFO, STp,
2253 			  "    can bsr: %d, two FMs: %d, "
2254 			  "fast mteom: %d, auto lock: %d,\n",
2255 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2256 			  STp->do_auto_lock);
2257 		st_printk(KERN_INFO, STp,
2258 			  "    defs for wr: %d, no block limits: %d, "
2259 			  "partitions: %d, s2 log: %d\n",
2260 			  STm->defaults_for_writes, STp->omit_blklims,
2261 			  STp->can_partitions, STp->scsi2_logical);
2262 		st_printk(KERN_INFO, STp,
2263 			  "    sysv: %d nowait: %d sili: %d "
2264 			  "nowait_filemark: %d\n",
2265 			  STm->sysv, STp->immediate, STp->sili,
2266 			  STp->immediate_filemark);
2267 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2268 	}
2269 }
2270 	)
2271 
2272 
2273 static int st_set_options(struct scsi_tape *STp, long options)
2274 {
2275 	int value;
2276 	long code;
2277 	struct st_modedef *STm;
2278 	struct cdev *cd0, *cd1;
2279 	struct device *d0, *d1;
2280 
2281 	STm = &(STp->modes[STp->current_mode]);
2282 	if (!STm->defined) {
2283 		cd0 = STm->cdevs[0];
2284 		cd1 = STm->cdevs[1];
2285 		d0  = STm->devs[0];
2286 		d1  = STm->devs[1];
2287 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2288 		STm->cdevs[0] = cd0;
2289 		STm->cdevs[1] = cd1;
2290 		STm->devs[0]  = d0;
2291 		STm->devs[1]  = d1;
2292 		modes_defined = 1;
2293 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2294 			    STp->current_mode);
2295 	}
2296 
2297 	code = options & MT_ST_OPTIONS;
2298 	if (code == MT_ST_BOOLEANS) {
2299 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2300 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2301 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2302 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2303 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2304 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2305 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2306 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2307 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2308 		if ((STp->device)->scsi_level >= SCSI_2)
2309 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2310 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2311 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2312 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2313 		STm->sysv = (options & MT_ST_SYSV) != 0;
2314 		STp->sili = (options & MT_ST_SILI) != 0;
2315 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2316 		     st_log_options(STp, STm); )
2317 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2318 		value = (code == MT_ST_SETBOOLEANS);
2319 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2320 			STm->do_buffer_writes = value;
2321 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2322 			STm->do_async_writes = value;
2323 		if ((options & MT_ST_DEF_WRITES) != 0)
2324 			STm->defaults_for_writes = value;
2325 		if ((options & MT_ST_READ_AHEAD) != 0)
2326 			STm->do_read_ahead = value;
2327 		if ((options & MT_ST_TWO_FM) != 0)
2328 			STp->two_fm = value;
2329 		if ((options & MT_ST_FAST_MTEOM) != 0)
2330 			STp->fast_mteom = value;
2331 		if ((options & MT_ST_AUTO_LOCK) != 0)
2332 			STp->do_auto_lock = value;
2333 		if ((options & MT_ST_CAN_BSR) != 0)
2334 			STp->can_bsr = value;
2335 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2336 			STp->omit_blklims = value;
2337 		if ((STp->device)->scsi_level >= SCSI_2 &&
2338 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2339 			STp->can_partitions = value;
2340 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2341 			STp->scsi2_logical = value;
2342 		if ((options & MT_ST_NOWAIT) != 0)
2343 			STp->immediate = value;
2344 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2345 			STp->immediate_filemark = value;
2346 		if ((options & MT_ST_SYSV) != 0)
2347 			STm->sysv = value;
2348 		if ((options & MT_ST_SILI) != 0)
2349 			STp->sili = value;
2350 		DEB(
2351 		if ((options & MT_ST_DEBUGGING) != 0)
2352 			debugging = value;
2353 			st_log_options(STp, STm); )
2354 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2355 		/* Retained for compatibility */
2356 	} else if (code == MT_ST_DEF_BLKSIZE) {
2357 		value = (options & ~MT_ST_OPTIONS);
2358 		if (value == ~MT_ST_OPTIONS) {
2359 			STm->default_blksize = (-1);
2360 			DEBC_printk(STp, "Default block size disabled.\n");
2361 		} else {
2362 			STm->default_blksize = value;
2363 			DEBC_printk(STp,"Default block size set to "
2364 				    "%d bytes.\n", STm->default_blksize);
2365 			if (STp->ready == ST_READY) {
2366 				STp->blksize_changed = 0;
2367 				set_mode_densblk(STp, STm);
2368 			}
2369 		}
2370 	} else if (code == MT_ST_TIMEOUTS) {
2371 		value = (options & ~MT_ST_OPTIONS);
2372 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2373 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2374 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2375 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2376 		} else {
2377 			blk_queue_rq_timeout(STp->device->request_queue,
2378 					     value * HZ);
2379 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2380 				    value);
2381 		}
2382 	} else if (code == MT_ST_SET_CLN) {
2383 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2384 		if (value != 0 &&
2385 			(value < EXTENDED_SENSE_START ||
2386 				value >= SCSI_SENSE_BUFFERSIZE))
2387 			return (-EINVAL);
2388 		STp->cln_mode = value;
2389 		STp->cln_sense_mask = (options >> 8) & 0xff;
2390 		STp->cln_sense_value = (options >> 16) & 0xff;
2391 		st_printk(KERN_INFO, STp,
2392 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2393 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2394 	} else if (code == MT_ST_DEF_OPTIONS) {
2395 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2396 		value = (options & MT_ST_CLEAR_DEFAULT);
2397 		if (code == MT_ST_DEF_DENSITY) {
2398 			if (value == MT_ST_CLEAR_DEFAULT) {
2399 				STm->default_density = (-1);
2400 				DEBC_printk(STp,
2401 					    "Density default disabled.\n");
2402 			} else {
2403 				STm->default_density = value & 0xff;
2404 				DEBC_printk(STp, "Density default set to %x\n",
2405 					    STm->default_density);
2406 				if (STp->ready == ST_READY) {
2407 					STp->density_changed = 0;
2408 					set_mode_densblk(STp, STm);
2409 				}
2410 			}
2411 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2412 			if (value == MT_ST_CLEAR_DEFAULT) {
2413 				STp->default_drvbuffer = 0xff;
2414 				DEBC_printk(STp,
2415 					    "Drive buffer default disabled.\n");
2416 			} else {
2417 				STp->default_drvbuffer = value & 7;
2418 				DEBC_printk(STp,
2419 					    "Drive buffer default set to %x\n",
2420 					    STp->default_drvbuffer);
2421 				if (STp->ready == ST_READY)
2422 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2423 			}
2424 		} else if (code == MT_ST_DEF_COMPRESSION) {
2425 			if (value == MT_ST_CLEAR_DEFAULT) {
2426 				STm->default_compression = ST_DONT_TOUCH;
2427 				DEBC_printk(STp,
2428 					    "Compression default disabled.\n");
2429 			} else {
2430 				if ((value & 0xff00) != 0) {
2431 					STp->c_algo = (value & 0xff00) >> 8;
2432 					DEBC_printk(STp, "Compression "
2433 						    "algorithm set to 0x%x.\n",
2434 						    STp->c_algo);
2435 				}
2436 				if ((value & 0xff) != 0xff) {
2437 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2438 					DEBC_printk(STp, "Compression default "
2439 						    "set to %x\n",
2440 						    (value & 1));
2441 					if (STp->ready == ST_READY) {
2442 						STp->compression_changed = 0;
2443 						st_compression(STp, (STm->default_compression == ST_YES));
2444 					}
2445 				}
2446 			}
2447 		}
2448 	} else
2449 		return (-EIO);
2450 
2451 	return 0;
2452 }
2453 
2454 #define MODE_HEADER_LENGTH  4
2455 
2456 /* Mode header and page byte offsets */
2457 #define MH_OFF_DATA_LENGTH     0
2458 #define MH_OFF_MEDIUM_TYPE     1
2459 #define MH_OFF_DEV_SPECIFIC    2
2460 #define MH_OFF_BDESCS_LENGTH   3
2461 #define MP_OFF_PAGE_NBR        0
2462 #define MP_OFF_PAGE_LENGTH     1
2463 
2464 /* Mode header and page bit masks */
2465 #define MH_BIT_WP              0x80
2466 #define MP_MSK_PAGE_NBR        0x3f
2467 
2468 /* Don't return block descriptors */
2469 #define MODE_SENSE_OMIT_BDESCS 0x08
2470 
2471 #define MODE_SELECT_PAGE_FORMAT 0x10
2472 
2473 /* Read a mode page into the tape buffer. The block descriptors are included
2474    if incl_block_descs is true. The page control is ored to the page number
2475    parameter, if necessary. */
2476 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2477 {
2478 	unsigned char cmd[MAX_COMMAND_SIZE];
2479 	struct st_request *SRpnt;
2480 
2481 	memset(cmd, 0, MAX_COMMAND_SIZE);
2482 	cmd[0] = MODE_SENSE;
2483 	if (omit_block_descs)
2484 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2485 	cmd[2] = page;
2486 	cmd[4] = 255;
2487 
2488 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2489 			   STp->device->request_queue->rq_timeout, 0, 1);
2490 	if (SRpnt == NULL)
2491 		return (STp->buffer)->syscall_result;
2492 
2493 	st_release_request(SRpnt);
2494 
2495 	return STp->buffer->syscall_result;
2496 }
2497 
2498 
2499 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2500    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2501 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2502 {
2503 	int pgo;
2504 	unsigned char cmd[MAX_COMMAND_SIZE];
2505 	struct st_request *SRpnt;
2506 	int timeout;
2507 
2508 	memset(cmd, 0, MAX_COMMAND_SIZE);
2509 	cmd[0] = MODE_SELECT;
2510 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2511 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2512 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2513 
2514 	/* Clear reserved fields */
2515 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2516 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2517 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2518 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2519 
2520 	timeout = slow ?
2521 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2522 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2523 			   timeout, 0, 1);
2524 	if (SRpnt == NULL)
2525 		return (STp->buffer)->syscall_result;
2526 
2527 	st_release_request(SRpnt);
2528 
2529 	return STp->buffer->syscall_result;
2530 }
2531 
2532 
2533 #define COMPRESSION_PAGE        0x0f
2534 #define COMPRESSION_PAGE_LENGTH 16
2535 
2536 #define CP_OFF_DCE_DCC          2
2537 #define CP_OFF_C_ALGO           7
2538 
2539 #define DCE_MASK  0x80
2540 #define DCC_MASK  0x40
2541 #define RED_MASK  0x60
2542 
2543 
2544 /* Control the compression with mode page 15. Algorithm not changed if zero.
2545 
2546    The block descriptors are read and written because Sony SDT-7000 does not
2547    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2548    Including block descriptors should not cause any harm to other drives. */
2549 
2550 static int st_compression(struct scsi_tape * STp, int state)
2551 {
2552 	int retval;
2553 	int mpoffs;  /* Offset to mode page start */
2554 	unsigned char *b_data = (STp->buffer)->b_data;
2555 
2556 	if (STp->ready != ST_READY)
2557 		return (-EIO);
2558 
2559 	/* Read the current page contents */
2560 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2561 	if (retval) {
2562 		DEBC_printk(STp, "Compression mode page not supported.\n");
2563 		return (-EIO);
2564 	}
2565 
2566 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2567 	DEBC_printk(STp, "Compression state is %d.\n",
2568 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2569 
2570 	/* Check if compression can be changed */
2571 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2572 		DEBC_printk(STp, "Compression not supported.\n");
2573 		return (-EIO);
2574 	}
2575 
2576 	/* Do the change */
2577 	if (state) {
2578 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2579 		if (STp->c_algo != 0)
2580 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2581 	}
2582 	else {
2583 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2584 		if (STp->c_algo != 0)
2585 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2586 	}
2587 
2588 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2589 	if (retval) {
2590 		DEBC_printk(STp, "Compression change failed.\n");
2591 		return (-EIO);
2592 	}
2593 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2594 
2595 	STp->compression_changed = 1;
2596 	return 0;
2597 }
2598 
2599 
2600 /* Process the load and unload commands (does unload if the load code is zero) */
2601 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2602 {
2603 	int retval = (-EIO), timeout;
2604 	unsigned char cmd[MAX_COMMAND_SIZE];
2605 	struct st_partstat *STps;
2606 	struct st_request *SRpnt;
2607 
2608 	if (STp->ready != ST_READY && !load_code) {
2609 		if (STp->ready == ST_NO_TAPE)
2610 			return (-ENOMEDIUM);
2611 		else
2612 			return (-EIO);
2613 	}
2614 
2615 	memset(cmd, 0, MAX_COMMAND_SIZE);
2616 	cmd[0] = START_STOP;
2617 	if (load_code)
2618 		cmd[4] |= 1;
2619 	/*
2620 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2621 	 */
2622 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2623 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2624 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2625 			    (cmd[4]) ? "" : "un",
2626 			    load_code - MT_ST_HPLOADER_OFFSET);
2627 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2628 	}
2629 	if (STp->immediate) {
2630 		cmd[1] = 1;	/* Don't wait for completion */
2631 		timeout = STp->device->request_queue->rq_timeout;
2632 	}
2633 	else
2634 		timeout = STp->long_timeout;
2635 
2636 	DEBC(
2637 		if (!load_code)
2638 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2639 		else
2640 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2641 		);
2642 
2643 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2644 			   timeout, MAX_RETRIES, 1);
2645 	if (!SRpnt)
2646 		return (STp->buffer)->syscall_result;
2647 
2648 	retval = (STp->buffer)->syscall_result;
2649 	st_release_request(SRpnt);
2650 
2651 	if (!retval) {	/* SCSI command successful */
2652 
2653 		if (!load_code) {
2654 			STp->rew_at_close = 0;
2655 			STp->ready = ST_NO_TAPE;
2656 		}
2657 		else {
2658 			STp->rew_at_close = STp->autorew_dev;
2659 			retval = check_tape(STp, filp);
2660 			if (retval > 0)
2661 				retval = 0;
2662 		}
2663 	}
2664 	else {
2665 		STps = &(STp->ps[STp->partition]);
2666 		STps->drv_file = STps->drv_block = (-1);
2667 	}
2668 
2669 	return retval;
2670 }
2671 
2672 #if DEBUG
2673 #define ST_DEB_FORWARD  0
2674 #define ST_DEB_BACKWARD 1
2675 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2676 {
2677 	s32 sc;
2678 
2679 	if (!debugging)
2680 		return;
2681 
2682 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2683 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2684 	if (direction)
2685 		sc = -sc;
2686 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2687 		  direction ? "backward" : "forward", sc, units);
2688 }
2689 #else
2690 #define ST_DEB_FORWARD  0
2691 #define ST_DEB_BACKWARD 1
2692 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2693 #endif
2694 
2695 
2696 /* Internal ioctl function */
2697 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2698 {
2699 	int timeout;
2700 	long ltmp;
2701 	int ioctl_result;
2702 	int chg_eof = 1;
2703 	unsigned char cmd[MAX_COMMAND_SIZE];
2704 	struct st_request *SRpnt;
2705 	struct st_partstat *STps;
2706 	int fileno, blkno, at_sm, undone;
2707 	int datalen = 0, direction = DMA_NONE;
2708 
2709 	WARN_ON(STp->buffer->do_dio != 0);
2710 	if (STp->ready != ST_READY) {
2711 		if (STp->ready == ST_NO_TAPE)
2712 			return (-ENOMEDIUM);
2713 		else
2714 			return (-EIO);
2715 	}
2716 	timeout = STp->long_timeout;
2717 	STps = &(STp->ps[STp->partition]);
2718 	fileno = STps->drv_file;
2719 	blkno = STps->drv_block;
2720 	at_sm = STps->at_sm;
2721 
2722 	memset(cmd, 0, MAX_COMMAND_SIZE);
2723 	switch (cmd_in) {
2724 	case MTFSFM:
2725 		chg_eof = 0;	/* Changed from the FSF after this */
2726 		/* fall through */
2727 	case MTFSF:
2728 		cmd[0] = SPACE;
2729 		cmd[1] = 0x01;	/* Space FileMarks */
2730 		cmd[2] = (arg >> 16);
2731 		cmd[3] = (arg >> 8);
2732 		cmd[4] = arg;
2733 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2734 		if (fileno >= 0)
2735 			fileno += arg;
2736 		blkno = 0;
2737 		at_sm &= (arg == 0);
2738 		break;
2739 	case MTBSFM:
2740 		chg_eof = 0;	/* Changed from the FSF after this */
2741 		/* fall through */
2742 	case MTBSF:
2743 		cmd[0] = SPACE;
2744 		cmd[1] = 0x01;	/* Space FileMarks */
2745 		ltmp = (-arg);
2746 		cmd[2] = (ltmp >> 16);
2747 		cmd[3] = (ltmp >> 8);
2748 		cmd[4] = ltmp;
2749 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2750 		if (fileno >= 0)
2751 			fileno -= arg;
2752 		blkno = (-1);	/* We can't know the block number */
2753 		at_sm &= (arg == 0);
2754 		break;
2755 	case MTFSR:
2756 		cmd[0] = SPACE;
2757 		cmd[1] = 0x00;	/* Space Blocks */
2758 		cmd[2] = (arg >> 16);
2759 		cmd[3] = (arg >> 8);
2760 		cmd[4] = arg;
2761 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2762 		if (blkno >= 0)
2763 			blkno += arg;
2764 		at_sm &= (arg == 0);
2765 		break;
2766 	case MTBSR:
2767 		cmd[0] = SPACE;
2768 		cmd[1] = 0x00;	/* Space Blocks */
2769 		ltmp = (-arg);
2770 		cmd[2] = (ltmp >> 16);
2771 		cmd[3] = (ltmp >> 8);
2772 		cmd[4] = ltmp;
2773 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2774 		if (blkno >= 0)
2775 			blkno -= arg;
2776 		at_sm &= (arg == 0);
2777 		break;
2778 	case MTFSS:
2779 		cmd[0] = SPACE;
2780 		cmd[1] = 0x04;	/* Space Setmarks */
2781 		cmd[2] = (arg >> 16);
2782 		cmd[3] = (arg >> 8);
2783 		cmd[4] = arg;
2784 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2785 		if (arg != 0) {
2786 			blkno = fileno = (-1);
2787 			at_sm = 1;
2788 		}
2789 		break;
2790 	case MTBSS:
2791 		cmd[0] = SPACE;
2792 		cmd[1] = 0x04;	/* Space Setmarks */
2793 		ltmp = (-arg);
2794 		cmd[2] = (ltmp >> 16);
2795 		cmd[3] = (ltmp >> 8);
2796 		cmd[4] = ltmp;
2797 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2798 		if (arg != 0) {
2799 			blkno = fileno = (-1);
2800 			at_sm = 1;
2801 		}
2802 		break;
2803 	case MTWEOF:
2804 	case MTWEOFI:
2805 	case MTWSM:
2806 		if (STp->write_prot)
2807 			return (-EACCES);
2808 		cmd[0] = WRITE_FILEMARKS;
2809 		if (cmd_in == MTWSM)
2810 			cmd[1] = 2;
2811 		if (cmd_in == MTWEOFI ||
2812 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2813 			cmd[1] |= 1;
2814 		cmd[2] = (arg >> 16);
2815 		cmd[3] = (arg >> 8);
2816 		cmd[4] = arg;
2817 		timeout = STp->device->request_queue->rq_timeout;
2818 		DEBC(
2819 			if (cmd_in != MTWSM)
2820 				st_printk(ST_DEB_MSG, STp,
2821 					  "Writing %d filemarks.\n",
2822 					  cmd[2] * 65536 +
2823 					  cmd[3] * 256 +
2824 					  cmd[4]);
2825 			else
2826 				st_printk(ST_DEB_MSG, STp,
2827 					  "Writing %d setmarks.\n",
2828 					  cmd[2] * 65536 +
2829 					  cmd[3] * 256 +
2830 					  cmd[4]);
2831 		)
2832 		if (fileno >= 0)
2833 			fileno += arg;
2834 		blkno = 0;
2835 		at_sm = (cmd_in == MTWSM);
2836 		break;
2837 	case MTREW:
2838 		cmd[0] = REZERO_UNIT;
2839 		if (STp->immediate) {
2840 			cmd[1] = 1;	/* Don't wait for completion */
2841 			timeout = STp->device->request_queue->rq_timeout;
2842 		}
2843 		DEBC_printk(STp, "Rewinding tape.\n");
2844 		fileno = blkno = at_sm = 0;
2845 		break;
2846 	case MTNOP:
2847 		DEBC_printk(STp, "No op on tape.\n");
2848 		return 0;	/* Should do something ? */
2849 		break;
2850 	case MTRETEN:
2851 		cmd[0] = START_STOP;
2852 		if (STp->immediate) {
2853 			cmd[1] = 1;	/* Don't wait for completion */
2854 			timeout = STp->device->request_queue->rq_timeout;
2855 		}
2856 		cmd[4] = 3;
2857 		DEBC_printk(STp, "Retensioning tape.\n");
2858 		fileno = blkno = at_sm = 0;
2859 		break;
2860 	case MTEOM:
2861 		if (!STp->fast_mteom) {
2862 			/* space to the end of tape */
2863 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2864 			fileno = STps->drv_file;
2865 			if (STps->eof >= ST_EOD_1)
2866 				return 0;
2867 			/* The next lines would hide the number of spaced FileMarks
2868 			   That's why I inserted the previous lines. I had no luck
2869 			   with detecting EOM with FSF, so we go now to EOM.
2870 			   Joerg Weule */
2871 		} else
2872 			fileno = (-1);
2873 		cmd[0] = SPACE;
2874 		cmd[1] = 3;
2875 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2876 		blkno = -1;
2877 		at_sm = 0;
2878 		break;
2879 	case MTERASE:
2880 		if (STp->write_prot)
2881 			return (-EACCES);
2882 		cmd[0] = ERASE;
2883 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2884 		if (STp->immediate) {
2885 			cmd[1] |= 2;	/* Don't wait for completion */
2886 			timeout = STp->device->request_queue->rq_timeout;
2887 		}
2888 		else
2889 			timeout = STp->long_timeout * 8;
2890 
2891 		DEBC_printk(STp, "Erasing tape.\n");
2892 		fileno = blkno = at_sm = 0;
2893 		break;
2894 	case MTSETBLK:		/* Set block length */
2895 	case MTSETDENSITY:	/* Set tape density */
2896 	case MTSETDRVBUFFER:	/* Set drive buffering */
2897 	case SET_DENS_AND_BLK:	/* Set density and block size */
2898 		chg_eof = 0;
2899 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2900 			return (-EIO);	/* Not allowed if data in buffer */
2901 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2902 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2903 		    STp->max_block > 0 &&
2904 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2905 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2906 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2907 			return (-EINVAL);
2908 		}
2909 		cmd[0] = MODE_SELECT;
2910 		if ((STp->use_pf & USE_PF))
2911 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2912 		cmd[4] = datalen = 12;
2913 		direction = DMA_TO_DEVICE;
2914 
2915 		memset((STp->buffer)->b_data, 0, 12);
2916 		if (cmd_in == MTSETDRVBUFFER)
2917 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2918 		else
2919 			(STp->buffer)->b_data[2] =
2920 			    STp->drv_buffer << 4;
2921 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2922 		if (cmd_in == MTSETDENSITY) {
2923 			(STp->buffer)->b_data[4] = arg;
2924 			STp->density_changed = 1;	/* At least we tried ;-) */
2925 		} else if (cmd_in == SET_DENS_AND_BLK)
2926 			(STp->buffer)->b_data[4] = arg >> 24;
2927 		else
2928 			(STp->buffer)->b_data[4] = STp->density;
2929 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2930 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2931 			if (cmd_in == MTSETBLK)
2932 				STp->blksize_changed = 1; /* At least we tried ;-) */
2933 		} else
2934 			ltmp = STp->block_size;
2935 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2936 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2937 		(STp->buffer)->b_data[11] = ltmp;
2938 		timeout = STp->device->request_queue->rq_timeout;
2939 		DEBC(
2940 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2941 				st_printk(ST_DEB_MSG, STp,
2942 					  "Setting block size to %d bytes.\n",
2943 					  (STp->buffer)->b_data[9] * 65536 +
2944 					  (STp->buffer)->b_data[10] * 256 +
2945 					  (STp->buffer)->b_data[11]);
2946 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2947 				st_printk(ST_DEB_MSG, STp,
2948 					  "Setting density code to %x.\n",
2949 					  (STp->buffer)->b_data[4]);
2950 			if (cmd_in == MTSETDRVBUFFER)
2951 				st_printk(ST_DEB_MSG, STp,
2952 					  "Setting drive buffer code to %d.\n",
2953 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2954 		)
2955 		break;
2956 	default:
2957 		return (-ENOSYS);
2958 	}
2959 
2960 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2961 			   timeout, MAX_RETRIES, 1);
2962 	if (!SRpnt)
2963 		return (STp->buffer)->syscall_result;
2964 
2965 	ioctl_result = (STp->buffer)->syscall_result;
2966 
2967 	if (!ioctl_result) {	/* SCSI command successful */
2968 		st_release_request(SRpnt);
2969 		SRpnt = NULL;
2970 		STps->drv_block = blkno;
2971 		STps->drv_file = fileno;
2972 		STps->at_sm = at_sm;
2973 
2974 		if (cmd_in == MTBSFM)
2975 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2976 		else if (cmd_in == MTFSFM)
2977 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2978 
2979 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2980 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2981 			if (STp->block_size != 0) {
2982 				(STp->buffer)->buffer_blocks =
2983 				    (STp->buffer)->buffer_size / STp->block_size;
2984 			}
2985 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2986 			if (cmd_in == SET_DENS_AND_BLK)
2987 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2988 		} else if (cmd_in == MTSETDRVBUFFER)
2989 			STp->drv_buffer = (arg & 7);
2990 		else if (cmd_in == MTSETDENSITY)
2991 			STp->density = arg;
2992 
2993 		if (cmd_in == MTEOM)
2994 			STps->eof = ST_EOD;
2995 		else if (cmd_in == MTFSF)
2996 			STps->eof = ST_FM;
2997 		else if (chg_eof)
2998 			STps->eof = ST_NOEOF;
2999 
3000 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
3001 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
3002 	} else { /* SCSI command was not completely successful. Don't return
3003                     from this block without releasing the SCSI command block! */
3004 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
3005 
3006 		if (cmdstatp->flags & SENSE_EOM) {
3007 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3008 			    cmd_in != MTBSR && cmd_in != MTBSS)
3009 				STps->eof = ST_EOM_OK;
3010 			STps->drv_block = 0;
3011 		}
3012 
3013 		if (cmdstatp->remainder_valid)
3014 			undone = (int)cmdstatp->uremainder64;
3015 		else
3016 			undone = 0;
3017 
3018 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3019 		    cmdstatp->have_sense &&
3020 		    (cmdstatp->flags & SENSE_EOM)) {
3021 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3022 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3023 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3024 				STps->eof = ST_NOEOF;
3025 			} else {  /* Writing EOF(s) failed */
3026 				if (fileno >= 0)
3027 					fileno -= undone;
3028 				if (undone < arg)
3029 					STps->eof = ST_NOEOF;
3030 			}
3031 			STps->drv_file = fileno;
3032 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3033 			if (fileno >= 0)
3034 				STps->drv_file = fileno - undone;
3035 			else
3036 				STps->drv_file = fileno;
3037 			STps->drv_block = -1;
3038 			STps->eof = ST_NOEOF;
3039 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3040 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3041 				undone = (-undone);
3042 			if (STps->drv_file >= 0)
3043 				STps->drv_file = fileno + undone;
3044 			STps->drv_block = 0;
3045 			STps->eof = ST_NOEOF;
3046 		} else if (cmd_in == MTFSR) {
3047 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3048 				if (STps->drv_file >= 0)
3049 					STps->drv_file++;
3050 				STps->drv_block = 0;
3051 				STps->eof = ST_FM;
3052 			} else {
3053 				if (blkno >= undone)
3054 					STps->drv_block = blkno - undone;
3055 				else
3056 					STps->drv_block = (-1);
3057 				STps->eof = ST_NOEOF;
3058 			}
3059 		} else if (cmd_in == MTBSR) {
3060 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3061 				STps->drv_file--;
3062 				STps->drv_block = (-1);
3063 			} else {
3064 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3065 					undone = (-undone);
3066 				if (STps->drv_block >= 0)
3067 					STps->drv_block = blkno + undone;
3068 			}
3069 			STps->eof = ST_NOEOF;
3070 		} else if (cmd_in == MTEOM) {
3071 			STps->drv_file = (-1);
3072 			STps->drv_block = (-1);
3073 			STps->eof = ST_EOD;
3074 		} else if (cmd_in == MTSETBLK ||
3075 			   cmd_in == MTSETDENSITY ||
3076 			   cmd_in == MTSETDRVBUFFER ||
3077 			   cmd_in == SET_DENS_AND_BLK) {
3078 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3079 			    !(STp->use_pf & PF_TESTED)) {
3080 				/* Try the other possible state of Page Format if not
3081 				   already tried */
3082 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3083 				st_release_request(SRpnt);
3084 				SRpnt = NULL;
3085 				return st_int_ioctl(STp, cmd_in, arg);
3086 			}
3087 		} else if (chg_eof)
3088 			STps->eof = ST_NOEOF;
3089 
3090 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3091 			STps->eof = ST_EOD;
3092 
3093 		st_release_request(SRpnt);
3094 		SRpnt = NULL;
3095 	}
3096 
3097 	return ioctl_result;
3098 }
3099 
3100 
3101 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3102    structure. */
3103 
3104 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3105 			int logical)
3106 {
3107 	int result;
3108 	unsigned char scmd[MAX_COMMAND_SIZE];
3109 	struct st_request *SRpnt;
3110 
3111 	if (STp->ready != ST_READY)
3112 		return (-EIO);
3113 
3114 	memset(scmd, 0, MAX_COMMAND_SIZE);
3115 	if ((STp->device)->scsi_level < SCSI_2) {
3116 		scmd[0] = QFA_REQUEST_BLOCK;
3117 		scmd[4] = 3;
3118 	} else {
3119 		scmd[0] = READ_POSITION;
3120 		if (!logical && !STp->scsi2_logical)
3121 			scmd[1] = 1;
3122 	}
3123 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3124 			   STp->device->request_queue->rq_timeout,
3125 			   MAX_READY_RETRIES, 1);
3126 	if (!SRpnt)
3127 		return (STp->buffer)->syscall_result;
3128 
3129 	if ((STp->buffer)->syscall_result != 0 ||
3130 	    (STp->device->scsi_level >= SCSI_2 &&
3131 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3132 		*block = *partition = 0;
3133 		DEBC_printk(STp, " Can't read tape position.\n");
3134 		result = (-EIO);
3135 	} else {
3136 		result = 0;
3137 		if ((STp->device)->scsi_level < SCSI_2) {
3138 			*block = ((STp->buffer)->b_data[0] << 16)
3139 			    + ((STp->buffer)->b_data[1] << 8)
3140 			    + (STp->buffer)->b_data[2];
3141 			*partition = 0;
3142 		} else {
3143 			*block = ((STp->buffer)->b_data[4] << 24)
3144 			    + ((STp->buffer)->b_data[5] << 16)
3145 			    + ((STp->buffer)->b_data[6] << 8)
3146 			    + (STp->buffer)->b_data[7];
3147 			*partition = (STp->buffer)->b_data[1];
3148 			if (((STp->buffer)->b_data[0] & 0x80) &&
3149 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3150 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3151 		}
3152 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3153 			    *block, *partition);
3154 	}
3155 	st_release_request(SRpnt);
3156 	SRpnt = NULL;
3157 
3158 	return result;
3159 }
3160 
3161 
3162 /* Set the tape block and partition. Negative partition means that only the
3163    block should be set in vendor specific way. */
3164 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3165 			int logical)
3166 {
3167 	struct st_partstat *STps;
3168 	int result, p;
3169 	unsigned int blk;
3170 	int timeout;
3171 	unsigned char scmd[MAX_COMMAND_SIZE];
3172 	struct st_request *SRpnt;
3173 
3174 	if (STp->ready != ST_READY)
3175 		return (-EIO);
3176 	timeout = STp->long_timeout;
3177 	STps = &(STp->ps[STp->partition]);
3178 
3179 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3180 		    block, partition);
3181 	DEB(if (partition < 0)
3182 		return (-EIO); )
3183 
3184 	/* Update the location at the partition we are leaving */
3185 	if ((!STp->can_partitions && partition != 0) ||
3186 	    partition >= ST_NBR_PARTITIONS)
3187 		return (-EINVAL);
3188 	if (partition != STp->partition) {
3189 		if (get_location(STp, &blk, &p, 1))
3190 			STps->last_block_valid = 0;
3191 		else {
3192 			STps->last_block_valid = 1;
3193 			STps->last_block_visited = blk;
3194 			DEBC_printk(STp, "Visited block %d for "
3195 				    "partition %d saved.\n",
3196 				    blk, STp->partition);
3197 		}
3198 	}
3199 
3200 	memset(scmd, 0, MAX_COMMAND_SIZE);
3201 	if ((STp->device)->scsi_level < SCSI_2) {
3202 		scmd[0] = QFA_SEEK_BLOCK;
3203 		scmd[2] = (block >> 16);
3204 		scmd[3] = (block >> 8);
3205 		scmd[4] = block;
3206 		scmd[5] = 0;
3207 	} else {
3208 		scmd[0] = SEEK_10;
3209 		scmd[3] = (block >> 24);
3210 		scmd[4] = (block >> 16);
3211 		scmd[5] = (block >> 8);
3212 		scmd[6] = block;
3213 		if (!logical && !STp->scsi2_logical)
3214 			scmd[1] = 4;
3215 		if (STp->partition != partition) {
3216 			scmd[1] |= 2;
3217 			scmd[8] = partition;
3218 			DEBC_printk(STp, "Trying to change partition "
3219 				    "from %d to %d\n", STp->partition,
3220 				    partition);
3221 		}
3222 	}
3223 	if (STp->immediate) {
3224 		scmd[1] |= 1;		/* Don't wait for completion */
3225 		timeout = STp->device->request_queue->rq_timeout;
3226 	}
3227 
3228 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3229 			   timeout, MAX_READY_RETRIES, 1);
3230 	if (!SRpnt)
3231 		return (STp->buffer)->syscall_result;
3232 
3233 	STps->drv_block = STps->drv_file = (-1);
3234 	STps->eof = ST_NOEOF;
3235 	if ((STp->buffer)->syscall_result != 0) {
3236 		result = (-EIO);
3237 		if (STp->can_partitions &&
3238 		    (STp->device)->scsi_level >= SCSI_2 &&
3239 		    (p = find_partition(STp)) >= 0)
3240 			STp->partition = p;
3241 	} else {
3242 		if (STp->can_partitions) {
3243 			STp->partition = partition;
3244 			STps = &(STp->ps[partition]);
3245 			if (!STps->last_block_valid ||
3246 			    STps->last_block_visited != block) {
3247 				STps->at_sm = 0;
3248 				STps->rw = ST_IDLE;
3249 			}
3250 		} else
3251 			STps->at_sm = 0;
3252 		if (block == 0)
3253 			STps->drv_block = STps->drv_file = 0;
3254 		result = 0;
3255 	}
3256 
3257 	st_release_request(SRpnt);
3258 	SRpnt = NULL;
3259 
3260 	return result;
3261 }
3262 
3263 
3264 /* Find the current partition number for the drive status. Called from open and
3265    returns either partition number of negative error code. */
3266 static int find_partition(struct scsi_tape *STp)
3267 {
3268 	int i, partition;
3269 	unsigned int block;
3270 
3271 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3272 		return i;
3273 	if (partition >= ST_NBR_PARTITIONS)
3274 		return (-EIO);
3275 	return partition;
3276 }
3277 
3278 
3279 /* Change the partition if necessary */
3280 static int switch_partition(struct scsi_tape *STp)
3281 {
3282 	struct st_partstat *STps;
3283 
3284 	if (STp->partition == STp->new_partition)
3285 		return 0;
3286 	STps = &(STp->ps[STp->new_partition]);
3287 	if (!STps->last_block_valid)
3288 		STps->last_block_visited = 0;
3289 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3290 }
3291 
3292 /* Functions for reading and writing the medium partition mode page. */
3293 
3294 #define PART_PAGE   0x11
3295 #define PART_PAGE_FIXED_LENGTH 8
3296 
3297 #define PP_OFF_MAX_ADD_PARTS   2
3298 #define PP_OFF_NBR_ADD_PARTS   3
3299 #define PP_OFF_FLAGS           4
3300 #define PP_OFF_PART_UNITS      6
3301 #define PP_OFF_RESERVED        7
3302 
3303 #define PP_BIT_IDP             0x20
3304 #define PP_BIT_FDP             0x80
3305 #define PP_MSK_PSUM_MB         0x10
3306 #define PP_MSK_PSUM_UNITS      0x18
3307 #define PP_MSK_POFM            0x04
3308 
3309 /* Get the number of partitions on the tape. As a side effect reads the
3310    mode page into the tape buffer. */
3311 static int nbr_partitions(struct scsi_tape *STp)
3312 {
3313 	int result;
3314 
3315 	if (STp->ready != ST_READY)
3316 		return (-EIO);
3317 
3318 	result = read_mode_page(STp, PART_PAGE, 1);
3319 
3320 	if (result) {
3321 		DEBC_printk(STp, "Can't read medium partition page.\n");
3322 		result = (-EIO);
3323 	} else {
3324 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3325 					      PP_OFF_NBR_ADD_PARTS] + 1;
3326 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3327 	}
3328 
3329 	return result;
3330 }
3331 
3332 
3333 static int format_medium(struct scsi_tape *STp, int format)
3334 {
3335 	int result = 0;
3336 	int timeout = STp->long_timeout;
3337 	unsigned char scmd[MAX_COMMAND_SIZE];
3338 	struct st_request *SRpnt;
3339 
3340 	memset(scmd, 0, MAX_COMMAND_SIZE);
3341 	scmd[0] = FORMAT_UNIT;
3342 	scmd[2] = format;
3343 	if (STp->immediate) {
3344 		scmd[1] |= 1;		/* Don't wait for completion */
3345 		timeout = STp->device->request_queue->rq_timeout;
3346 	}
3347 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3348 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3349 			   timeout, MAX_RETRIES, 1);
3350 	if (!SRpnt)
3351 		result = STp->buffer->syscall_result;
3352 	return result;
3353 }
3354 
3355 
3356 /* Partition the tape into two partitions if size > 0 or one partition if
3357    size == 0.
3358 
3359    The block descriptors are read and written because Sony SDT-7000 does not
3360    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3361 
3362    My HP C1533A drive returns only one partition size field. This is used to
3363    set the size of partition 1. There is no size field for the default partition.
3364    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3365    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3366    The following algorithm is used to accommodate both drives: if the number of
3367    partition size fields is greater than the maximum number of additional partitions
3368    in the mode page, the second field is used. Otherwise the first field is used.
3369 
3370    For Seagate DDS drives the page length must be 8 when no partitions is defined
3371    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3372    is acceptable also to some other old drives and enforced if the first partition
3373    size field is used for the first additional partition size.
3374 
3375    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3376  */
3377 static int partition_tape(struct scsi_tape *STp, int size)
3378 {
3379 	int result;
3380 	int target_partition;
3381 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3382 	int pgo, psd_cnt, psdo;
3383 	int psum = PP_MSK_PSUM_MB, units = 0;
3384 	unsigned char *bp;
3385 
3386 	result = read_mode_page(STp, PART_PAGE, 0);
3387 	if (result) {
3388 		DEBC_printk(STp, "Can't read partition mode page.\n");
3389 		return result;
3390 	}
3391 	target_partition = 1;
3392 	if (size < 0) {
3393 		target_partition = 0;
3394 		size = -size;
3395 	}
3396 
3397 	/* The mode page is in the buffer. Let's modify it and write it. */
3398 	bp = (STp->buffer)->b_data;
3399 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3400 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3401 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3402 
3403 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3404 
3405 	if (scsi3) {
3406 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3407 		if (needs_format && size == 0) {
3408 			/* No need to write the mode page when clearing
3409 			 *  partitioning
3410 			 */
3411 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3412 			result = format_medium(STp, 0);
3413 			goto out;
3414 		}
3415 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3416 			psd_cnt = 2;
3417 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3418 			/* Use units scaling for large partitions if the device
3419 			 * suggests it and no precision lost. Required for IBM
3420 			 * TS1140/50 drives that don't support MB units.
3421 			 */
3422 			if (size >= 1000 && (size % 1000) == 0) {
3423 				size /= 1000;
3424 				psum = PP_MSK_PSUM_UNITS;
3425 				units = 9; /* GB */
3426 			}
3427 		}
3428 		/* Try it anyway if too large to specify in MB */
3429 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3430 			size /= 1000;
3431 			psum = PP_MSK_PSUM_UNITS;
3432 			units = 9;  /* GB */
3433 		}
3434 	}
3435 
3436 	if (size >= 65535 ||  /* Does not fit into two bytes */
3437 	    (target_partition == 0 && psd_cnt < 2)) {
3438 		result = -EINVAL;
3439 		goto out;
3440 	}
3441 
3442 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3443 	/* The second condition is for HP DDS which use only one partition size
3444 	 * descriptor
3445 	 */
3446 	if (target_partition > 0 &&
3447 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3448 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3449 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3450 		psdo += 2;
3451 	}
3452 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3453 
3454 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3455 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3456 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3457 
3458 	if (size == 0) {
3459 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3460 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3461 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3462 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3463 	} else {
3464 		bp[psdo] = (size >> 8) & 0xff;
3465 		bp[psdo + 1] = size & 0xff;
3466 		if (target_partition == 0)
3467 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3468 		bp[pgo + 3] = 1;
3469 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3470 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3471 		DEBC_printk(STp,
3472 			    "Formatting tape with two partitions (%i = %d MB).\n",
3473 			    target_partition, units > 0 ? size * 1000 : size);
3474 	}
3475 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3476 	bp[pgo + PP_OFF_RESERVED] = 0;
3477 	if (size != 1 || units != 0) {
3478 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3479 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3480 		bp[pgo + PP_OFF_PART_UNITS] = units;
3481 	} else
3482 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3483 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3484 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3485 
3486 	result = write_mode_page(STp, PART_PAGE, 1);
3487 
3488 	if (!result && needs_format)
3489 		result = format_medium(STp, 1);
3490 
3491 	if (result) {
3492 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3493 		result = (-EIO);
3494 	}
3495 
3496 out:
3497 	return result;
3498 }
3499 
3500 
3501 
3502 /* The ioctl command */
3503 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3504 {
3505 	int i, cmd_nr, cmd_type, bt;
3506 	int retval = 0;
3507 	unsigned int blk;
3508 	struct scsi_tape *STp = file->private_data;
3509 	struct st_modedef *STm;
3510 	struct st_partstat *STps;
3511 	void __user *p = (void __user *)arg;
3512 
3513 	if (mutex_lock_interruptible(&STp->lock))
3514 		return -ERESTARTSYS;
3515 
3516 	DEB(
3517 	if (debugging && !STp->in_use) {
3518 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3519 		retval = (-EIO);
3520 		goto out;
3521 	} ) /* end DEB */
3522 
3523 	STm = &(STp->modes[STp->current_mode]);
3524 	STps = &(STp->ps[STp->partition]);
3525 
3526 	/*
3527 	 * If we are in the middle of error recovery, don't let anyone
3528 	 * else try and use this device.  Also, if error recovery fails, it
3529 	 * may try and take the device offline, in which case all further
3530 	 * access to the device is prohibited.
3531 	 */
3532 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3533 			file->f_flags & O_NDELAY);
3534 	if (retval)
3535 		goto out;
3536 
3537 	cmd_type = _IOC_TYPE(cmd_in);
3538 	cmd_nr = _IOC_NR(cmd_in);
3539 
3540 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3541 		struct mtop mtc;
3542 
3543 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3544 			retval = (-EINVAL);
3545 			goto out;
3546 		}
3547 
3548 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3549 		if (i) {
3550 			retval = (-EFAULT);
3551 			goto out;
3552 		}
3553 
3554 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3555 			st_printk(KERN_WARNING, STp,
3556 				  "MTSETDRVBUFFER only allowed for root.\n");
3557 			retval = (-EPERM);
3558 			goto out;
3559 		}
3560 		if (!STm->defined &&
3561 		    (mtc.mt_op != MTSETDRVBUFFER &&
3562 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3563 			retval = (-ENXIO);
3564 			goto out;
3565 		}
3566 
3567 		if (!STp->pos_unknown) {
3568 
3569 			if (STps->eof == ST_FM_HIT) {
3570 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3571                                     mtc.mt_op == MTEOM) {
3572 					mtc.mt_count -= 1;
3573 					if (STps->drv_file >= 0)
3574 						STps->drv_file += 1;
3575 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3576 					mtc.mt_count += 1;
3577 					if (STps->drv_file >= 0)
3578 						STps->drv_file += 1;
3579 				}
3580 			}
3581 
3582 			if (mtc.mt_op == MTSEEK) {
3583 				/* Old position must be restored if partition will be
3584                                    changed */
3585 				i = !STp->can_partitions ||
3586 				    (STp->new_partition != STp->partition);
3587 			} else {
3588 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3589 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3590 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3591 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3592 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3593 				    mtc.mt_op == MTCOMPRESSION;
3594 			}
3595 			i = flush_buffer(STp, i);
3596 			if (i < 0) {
3597 				retval = i;
3598 				goto out;
3599 			}
3600 			if (STps->rw == ST_WRITING &&
3601 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3602 			     mtc.mt_op == MTSEEK ||
3603 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3604 				i = st_int_ioctl(STp, MTWEOF, 1);
3605 				if (i < 0) {
3606 					retval = i;
3607 					goto out;
3608 				}
3609 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3610 					mtc.mt_count++;
3611 				STps->rw = ST_IDLE;
3612 			     }
3613 
3614 		} else {
3615 			/*
3616 			 * If there was a bus reset, block further access
3617 			 * to this device.  If the user wants to rewind the tape,
3618 			 * then reset the flag and allow access again.
3619 			 */
3620 			if (mtc.mt_op != MTREW &&
3621 			    mtc.mt_op != MTOFFL &&
3622 			    mtc.mt_op != MTRETEN &&
3623 			    mtc.mt_op != MTERASE &&
3624 			    mtc.mt_op != MTSEEK &&
3625 			    mtc.mt_op != MTEOM) {
3626 				retval = (-EIO);
3627 				goto out;
3628 			}
3629 			reset_state(STp);
3630 			/* remove this when the midlevel properly clears was_reset */
3631 			STp->device->was_reset = 0;
3632 		}
3633 
3634 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3635 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3636 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3637 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3638 
3639 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3640 			do_door_lock(STp, 0);	/* Ignore result! */
3641 
3642 		if (mtc.mt_op == MTSETDRVBUFFER &&
3643 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3644 			retval = st_set_options(STp, mtc.mt_count);
3645 			goto out;
3646 		}
3647 
3648 		if (mtc.mt_op == MTSETPART) {
3649 			if (!STp->can_partitions ||
3650 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3651 				retval = (-EINVAL);
3652 				goto out;
3653 			}
3654 			if (mtc.mt_count >= STp->nbr_partitions &&
3655 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3656 				retval = (-EIO);
3657 				goto out;
3658 			}
3659 			if (mtc.mt_count >= STp->nbr_partitions) {
3660 				retval = (-EINVAL);
3661 				goto out;
3662 			}
3663 			STp->new_partition = mtc.mt_count;
3664 			retval = 0;
3665 			goto out;
3666 		}
3667 
3668 		if (mtc.mt_op == MTMKPART) {
3669 			if (!STp->can_partitions) {
3670 				retval = (-EINVAL);
3671 				goto out;
3672 			}
3673 			i = do_load_unload(STp, file, 1);
3674 			if (i < 0) {
3675 				retval = i;
3676 				goto out;
3677 			}
3678 			i = partition_tape(STp, mtc.mt_count);
3679 			if (i < 0) {
3680 				retval = i;
3681 				goto out;
3682 			}
3683 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3684 				STp->ps[i].rw = ST_IDLE;
3685 				STp->ps[i].at_sm = 0;
3686 				STp->ps[i].last_block_valid = 0;
3687 			}
3688 			STp->partition = STp->new_partition = 0;
3689 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3690 			STps->drv_block = STps->drv_file = 0;
3691 			retval = 0;
3692 			goto out;
3693 		}
3694 
3695 		if (mtc.mt_op == MTSEEK) {
3696 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3697 			if (!STp->can_partitions)
3698 				STp->ps[0].rw = ST_IDLE;
3699 			retval = i;
3700 			goto out;
3701 		}
3702 
3703 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3704 			retval = do_load_unload(STp, file, 0);
3705 			goto out;
3706 		}
3707 
3708 		if (mtc.mt_op == MTLOAD) {
3709 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3710 			goto out;
3711 		}
3712 
3713 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3714 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3715 			goto out;
3716 		}
3717 
3718 		if (STp->can_partitions && STp->ready == ST_READY &&
3719 		    (i = switch_partition(STp)) < 0) {
3720 			retval = i;
3721 			goto out;
3722 		}
3723 
3724 		if (mtc.mt_op == MTCOMPRESSION)
3725 			retval = st_compression(STp, (mtc.mt_count & 1));
3726 		else
3727 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3728 		goto out;
3729 	}
3730 	if (!STm->defined) {
3731 		retval = (-ENXIO);
3732 		goto out;
3733 	}
3734 
3735 	if ((i = flush_buffer(STp, 0)) < 0) {
3736 		retval = i;
3737 		goto out;
3738 	}
3739 	if (STp->can_partitions &&
3740 	    (i = switch_partition(STp)) < 0) {
3741 		retval = i;
3742 		goto out;
3743 	}
3744 
3745 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3746 		struct mtget mt_status;
3747 
3748 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3749 			 retval = (-EINVAL);
3750 			 goto out;
3751 		}
3752 
3753 		mt_status.mt_type = STp->tape_type;
3754 		mt_status.mt_dsreg =
3755 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3756 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3757 		mt_status.mt_blkno = STps->drv_block;
3758 		mt_status.mt_fileno = STps->drv_file;
3759 		if (STp->block_size != 0) {
3760 			if (STps->rw == ST_WRITING)
3761 				mt_status.mt_blkno +=
3762 				    (STp->buffer)->buffer_bytes / STp->block_size;
3763 			else if (STps->rw == ST_READING)
3764 				mt_status.mt_blkno -=
3765                                         ((STp->buffer)->buffer_bytes +
3766                                          STp->block_size - 1) / STp->block_size;
3767 		}
3768 
3769 		mt_status.mt_gstat = 0;
3770 		if (STp->drv_write_prot)
3771 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3772 		if (mt_status.mt_blkno == 0) {
3773 			if (mt_status.mt_fileno == 0)
3774 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3775 			else
3776 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3777 		}
3778 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3779 		mt_status.mt_resid = STp->partition;
3780 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3781 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3782 		else if (STps->eof >= ST_EOM_OK)
3783 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3784 		if (STp->density == 1)
3785 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3786 		else if (STp->density == 2)
3787 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3788 		else if (STp->density == 3)
3789 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3790 		if (STp->ready == ST_READY)
3791 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3792 		if (STp->ready == ST_NO_TAPE)
3793 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3794 		if (STps->at_sm)
3795 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3796 		if (STm->do_async_writes ||
3797                     (STm->do_buffer_writes && STp->block_size != 0) ||
3798 		    STp->drv_buffer != 0)
3799 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3800 		if (STp->cleaning_req)
3801 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3802 
3803 		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
3804 		if (i) {
3805 			retval = (-EFAULT);
3806 			goto out;
3807 		}
3808 
3809 		STp->recover_reg = 0;		/* Clear after read */
3810 		retval = 0;
3811 		goto out;
3812 	}			/* End of MTIOCGET */
3813 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3814 		struct mtpos mt_pos;
3815 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3816 			 retval = (-EINVAL);
3817 			 goto out;
3818 		}
3819 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3820 			retval = i;
3821 			goto out;
3822 		}
3823 		mt_pos.mt_blkno = blk;
3824 		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
3825 		if (i)
3826 			retval = (-EFAULT);
3827 		goto out;
3828 	}
3829 	mutex_unlock(&STp->lock);
3830 	switch (cmd_in) {
3831 		case SCSI_IOCTL_GET_IDLUN:
3832 		case SCSI_IOCTL_GET_BUS_NUMBER:
3833 			break;
3834 		default:
3835 			if ((cmd_in == SG_IO ||
3836 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3837 			     cmd_in == CDROM_SEND_PACKET) &&
3838 			    !capable(CAP_SYS_RAWIO))
3839 				i = -EPERM;
3840 			else
3841 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3842 						   file->f_mode, cmd_in, p);
3843 			if (i != -ENOTTY)
3844 				return i;
3845 			break;
3846 	}
3847 	retval = scsi_ioctl(STp->device, cmd_in, p);
3848 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3849 		STp->rew_at_close = 0;
3850 		STp->ready = ST_NO_TAPE;
3851 	}
3852 	return retval;
3853 
3854  out:
3855 	mutex_unlock(&STp->lock);
3856 	return retval;
3857 }
3858 
3859 #ifdef CONFIG_COMPAT
3860 static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3861 {
3862 	struct scsi_tape *STp = file->private_data;
3863 	struct scsi_device *sdev = STp->device;
3864 	int ret = -ENOIOCTLCMD;
3865 	if (sdev->host->hostt->compat_ioctl) {
3866 
3867 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
3868 
3869 	}
3870 	return ret;
3871 }
3872 #endif
3873 
3874 
3875 
3876 /* Try to allocate a new tape buffer. Calling function must not hold
3877    dev_arr_lock. */
3878 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3879 {
3880 	struct st_buffer *tb;
3881 
3882 	tb = kzalloc(sizeof(struct st_buffer), GFP_KERNEL);
3883 	if (!tb) {
3884 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3885 		return NULL;
3886 	}
3887 	tb->frp_segs = 0;
3888 	tb->use_sg = max_sg;
3889 	tb->dma = need_dma;
3890 	tb->buffer_size = 0;
3891 
3892 	tb->reserved_pages = kcalloc(max_sg, sizeof(struct page *),
3893 				     GFP_KERNEL);
3894 	if (!tb->reserved_pages) {
3895 		kfree(tb);
3896 		return NULL;
3897 	}
3898 
3899 	return tb;
3900 }
3901 
3902 
3903 /* Try to allocate enough space in the tape buffer */
3904 #define ST_MAX_ORDER 6
3905 
3906 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3907 {
3908 	int segs, max_segs, b_size, order, got;
3909 	gfp_t priority;
3910 
3911 	if (new_size <= STbuffer->buffer_size)
3912 		return 1;
3913 
3914 	if (STbuffer->buffer_size <= PAGE_SIZE)
3915 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3916 
3917 	max_segs = STbuffer->use_sg;
3918 
3919 	priority = GFP_KERNEL | __GFP_NOWARN;
3920 	if (need_dma)
3921 		priority |= GFP_DMA;
3922 
3923 	if (STbuffer->cleared)
3924 		priority |= __GFP_ZERO;
3925 
3926 	if (STbuffer->frp_segs) {
3927 		order = STbuffer->reserved_page_order;
3928 		b_size = PAGE_SIZE << order;
3929 	} else {
3930 		for (b_size = PAGE_SIZE, order = 0;
3931 		     order < ST_MAX_ORDER &&
3932 			     max_segs * (PAGE_SIZE << order) < new_size;
3933 		     order++, b_size *= 2)
3934 			;  /* empty */
3935 		STbuffer->reserved_page_order = order;
3936 	}
3937 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3938 		if (order == ST_MAX_ORDER)
3939 			return 0;
3940 		normalize_buffer(STbuffer);
3941 		return enlarge_buffer(STbuffer, new_size, need_dma);
3942 	}
3943 
3944 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3945 	     segs < max_segs && got < new_size;) {
3946 		struct page *page;
3947 
3948 		page = alloc_pages(priority, order);
3949 		if (!page) {
3950 			DEB(STbuffer->buffer_size = got);
3951 			normalize_buffer(STbuffer);
3952 			return 0;
3953 		}
3954 
3955 		STbuffer->frp_segs += 1;
3956 		got += b_size;
3957 		STbuffer->buffer_size = got;
3958 		STbuffer->reserved_pages[segs] = page;
3959 		segs++;
3960 	}
3961 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3962 
3963 	return 1;
3964 }
3965 
3966 
3967 /* Make sure that no data from previous user is in the internal buffer */
3968 static void clear_buffer(struct st_buffer * st_bp)
3969 {
3970 	int i;
3971 
3972 	for (i=0; i < st_bp->frp_segs; i++)
3973 		memset(page_address(st_bp->reserved_pages[i]), 0,
3974 		       PAGE_SIZE << st_bp->reserved_page_order);
3975 	st_bp->cleared = 1;
3976 }
3977 
3978 
3979 /* Release the extra buffer */
3980 static void normalize_buffer(struct st_buffer * STbuffer)
3981 {
3982 	int i, order = STbuffer->reserved_page_order;
3983 
3984 	for (i = 0; i < STbuffer->frp_segs; i++) {
3985 		__free_pages(STbuffer->reserved_pages[i], order);
3986 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3987 	}
3988 	STbuffer->frp_segs = 0;
3989 	STbuffer->sg_segs = 0;
3990 	STbuffer->reserved_page_order = 0;
3991 	STbuffer->map_data.offset = 0;
3992 }
3993 
3994 
3995 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3996    negative error code. */
3997 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3998 {
3999 	int i, cnt, res, offset;
4000 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4001 
4002 	for (i = 0, offset = st_bp->buffer_bytes;
4003 	     i < st_bp->frp_segs && offset >= length; i++)
4004 		offset -= length;
4005 	if (i == st_bp->frp_segs) {	/* Should never happen */
4006 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
4007 		return (-EIO);
4008 	}
4009 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4010 		struct page *page = st_bp->reserved_pages[i];
4011 		cnt = length - offset < do_count ? length - offset : do_count;
4012 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4013 		if (res)
4014 			return (-EFAULT);
4015 		do_count -= cnt;
4016 		st_bp->buffer_bytes += cnt;
4017 		ubp += cnt;
4018 		offset = 0;
4019 	}
4020 	if (do_count) /* Should never happen */
4021 		return (-EIO);
4022 
4023 	return 0;
4024 }
4025 
4026 
4027 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4028    negative error code. */
4029 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4030 {
4031 	int i, cnt, res, offset;
4032 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4033 
4034 	for (i = 0, offset = st_bp->read_pointer;
4035 	     i < st_bp->frp_segs && offset >= length; i++)
4036 		offset -= length;
4037 	if (i == st_bp->frp_segs) {	/* Should never happen */
4038 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4039 		return (-EIO);
4040 	}
4041 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4042 		struct page *page = st_bp->reserved_pages[i];
4043 		cnt = length - offset < do_count ? length - offset : do_count;
4044 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4045 		if (res)
4046 			return (-EFAULT);
4047 		do_count -= cnt;
4048 		st_bp->buffer_bytes -= cnt;
4049 		st_bp->read_pointer += cnt;
4050 		ubp += cnt;
4051 		offset = 0;
4052 	}
4053 	if (do_count) /* Should never happen */
4054 		return (-EIO);
4055 
4056 	return 0;
4057 }
4058 
4059 
4060 /* Move data towards start of buffer */
4061 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4062 {
4063 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4064 	int count, total;
4065 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4066 
4067 	if (offset == 0)
4068 		return;
4069 
4070 	total=st_bp->buffer_bytes - offset;
4071 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4072 		src_offset = offset;
4073 		if (src_offset < length)
4074 			break;
4075 		offset -= length;
4076 	}
4077 
4078 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4079 	for (dst_seg=dst_offset=0; total > 0; ) {
4080 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4081 		struct page *spage = st_bp->reserved_pages[src_seg];
4082 
4083 		count = min(length - dst_offset, length - src_offset);
4084 		memmove(page_address(dpage) + dst_offset,
4085 			page_address(spage) + src_offset, count);
4086 		src_offset += count;
4087 		if (src_offset >= length) {
4088 			src_seg++;
4089 			src_offset = 0;
4090 		}
4091 		dst_offset += count;
4092 		if (dst_offset >= length) {
4093 			dst_seg++;
4094 			dst_offset = 0;
4095 		}
4096 		total -= count;
4097 	}
4098 }
4099 
4100 /* Validate the options from command line or module parameters */
4101 static void validate_options(void)
4102 {
4103 	if (buffer_kbs > 0)
4104 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4105 	if (max_sg_segs >= ST_FIRST_SG)
4106 		st_max_sg_segs = max_sg_segs;
4107 }
4108 
4109 #ifndef MODULE
4110 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4111  */
4112 static int __init st_setup(char *str)
4113 {
4114 	int i, len, ints[5];
4115 	char *stp;
4116 
4117 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4118 
4119 	if (ints[0] > 0) {
4120 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4121 			if (parms[i].val)
4122 				*parms[i].val = ints[i + 1];
4123 	} else {
4124 		while (stp != NULL) {
4125 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4126 				len = strlen(parms[i].name);
4127 				if (!strncmp(stp, parms[i].name, len) &&
4128 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4129 					if (parms[i].val)
4130 						*parms[i].val =
4131 							simple_strtoul(stp + len + 1, NULL, 0);
4132 					else
4133 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4134 						       parms[i].name);
4135 					break;
4136 				}
4137 			}
4138 			if (i >= ARRAY_SIZE(parms))
4139 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4140 					stp);
4141 			stp = strchr(stp, ',');
4142 			if (stp)
4143 				stp++;
4144 		}
4145 	}
4146 
4147 	validate_options();
4148 
4149 	return 1;
4150 }
4151 
4152 __setup("st=", st_setup);
4153 
4154 #endif
4155 
4156 static const struct file_operations st_fops =
4157 {
4158 	.owner =	THIS_MODULE,
4159 	.read =		st_read,
4160 	.write =	st_write,
4161 	.unlocked_ioctl = st_ioctl,
4162 #ifdef CONFIG_COMPAT
4163 	.compat_ioctl = st_compat_ioctl,
4164 #endif
4165 	.open =		st_open,
4166 	.flush =	st_flush,
4167 	.release =	st_release,
4168 	.llseek =	noop_llseek,
4169 };
4170 
4171 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4172 {
4173 	int i, error;
4174 	dev_t cdev_devno;
4175 	struct cdev *cdev;
4176 	struct device *dev;
4177 	struct st_modedef *STm = &(tape->modes[mode]);
4178 	char name[10];
4179 	int dev_num = tape->index;
4180 
4181 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4182 
4183 	cdev = cdev_alloc();
4184 	if (!cdev) {
4185 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4186 		error = -ENOMEM;
4187 		goto out;
4188 	}
4189 	cdev->owner = THIS_MODULE;
4190 	cdev->ops = &st_fops;
4191 	STm->cdevs[rew] = cdev;
4192 
4193 	error = cdev_add(cdev, cdev_devno, 1);
4194 	if (error) {
4195 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4196 		       rew ? "non" : "auto", mode);
4197 		pr_err("st%d: Device not attached.\n", dev_num);
4198 		goto out_free;
4199 	}
4200 
4201 	i = mode << (4 - ST_NBR_MODE_BITS);
4202 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4203 		 tape->disk->disk_name, st_formats[i]);
4204 
4205 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4206 			    cdev_devno, &tape->modes[mode], "%s", name);
4207 	if (IS_ERR(dev)) {
4208 		pr_err("st%d: device_create failed\n", dev_num);
4209 		error = PTR_ERR(dev);
4210 		goto out_free;
4211 	}
4212 
4213 	STm->devs[rew] = dev;
4214 
4215 	return 0;
4216 out_free:
4217 	cdev_del(STm->cdevs[rew]);
4218 out:
4219 	STm->cdevs[rew] = NULL;
4220 	STm->devs[rew] = NULL;
4221 	return error;
4222 }
4223 
4224 static int create_cdevs(struct scsi_tape *tape)
4225 {
4226 	int mode, error;
4227 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4228 		error = create_one_cdev(tape, mode, 0);
4229 		if (error)
4230 			return error;
4231 		error = create_one_cdev(tape, mode, 1);
4232 		if (error)
4233 			return error;
4234 	}
4235 
4236 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4237 				 &tape->modes[0].devs[0]->kobj, "tape");
4238 }
4239 
4240 static void remove_cdevs(struct scsi_tape *tape)
4241 {
4242 	int mode, rew;
4243 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4244 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4245 		struct st_modedef *STm = &(tape->modes[mode]);
4246 		for (rew = 0; rew < 2; rew++) {
4247 			if (STm->cdevs[rew])
4248 				cdev_del(STm->cdevs[rew]);
4249 			if (STm->devs[rew])
4250 				device_unregister(STm->devs[rew]);
4251 		}
4252 	}
4253 }
4254 
4255 static int st_probe(struct device *dev)
4256 {
4257 	struct scsi_device *SDp = to_scsi_device(dev);
4258 	struct gendisk *disk = NULL;
4259 	struct scsi_tape *tpnt = NULL;
4260 	struct st_modedef *STm;
4261 	struct st_partstat *STps;
4262 	struct st_buffer *buffer;
4263 	int i, error;
4264 	char *stp;
4265 
4266 	if (SDp->type != TYPE_TAPE)
4267 		return -ENODEV;
4268 	if ((stp = st_incompatible(SDp))) {
4269 		sdev_printk(KERN_INFO, SDp,
4270 			    "OnStream tapes are no longer supported;\n");
4271 		sdev_printk(KERN_INFO, SDp,
4272 			    "please mail to linux-scsi@vger.kernel.org.\n");
4273 		return -ENODEV;
4274 	}
4275 
4276 	scsi_autopm_get_device(SDp);
4277 	i = queue_max_segments(SDp->request_queue);
4278 	if (st_max_sg_segs < i)
4279 		i = st_max_sg_segs;
4280 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
4281 	if (buffer == NULL) {
4282 		sdev_printk(KERN_ERR, SDp,
4283 			    "st: Can't allocate new tape buffer. "
4284 			    "Device not attached.\n");
4285 		goto out;
4286 	}
4287 
4288 	disk = alloc_disk(1);
4289 	if (!disk) {
4290 		sdev_printk(KERN_ERR, SDp,
4291 			    "st: out of memory. Device not attached.\n");
4292 		goto out_buffer_free;
4293 	}
4294 
4295 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
4296 	if (tpnt == NULL) {
4297 		sdev_printk(KERN_ERR, SDp,
4298 			    "st: Can't allocate device descriptor.\n");
4299 		goto out_put_disk;
4300 	}
4301 	kref_init(&tpnt->kref);
4302 	tpnt->disk = disk;
4303 	disk->private_data = &tpnt->driver;
4304 	/* SCSI tape doesn't register this gendisk via add_disk().  Manually
4305 	 * take queue reference that release_disk() expects. */
4306 	if (!blk_get_queue(SDp->request_queue))
4307 		goto out_put_disk;
4308 	disk->queue = SDp->request_queue;
4309 	tpnt->driver = &st_template;
4310 
4311 	tpnt->device = SDp;
4312 	if (SDp->scsi_level <= 2)
4313 		tpnt->tape_type = MT_ISSCSI1;
4314 	else
4315 		tpnt->tape_type = MT_ISSCSI2;
4316 
4317 	tpnt->buffer = buffer;
4318 	tpnt->buffer->last_SRpnt = NULL;
4319 
4320 	tpnt->inited = 0;
4321 	tpnt->dirty = 0;
4322 	tpnt->in_use = 0;
4323 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4324 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4325 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4326 	tpnt->density = 0;
4327 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4328 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4329 	tpnt->can_partitions = 0;
4330 	tpnt->two_fm = ST_TWO_FM;
4331 	tpnt->fast_mteom = ST_FAST_MTEOM;
4332 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4333 	tpnt->sili = ST_SILI;
4334 	tpnt->immediate = ST_NOWAIT;
4335 	tpnt->immediate_filemark = 0;
4336 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4337 	tpnt->partition = 0;
4338 	tpnt->new_partition = 0;
4339 	tpnt->nbr_partitions = 0;
4340 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4341 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4342 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4343 
4344 	for (i = 0; i < ST_NBR_MODES; i++) {
4345 		STm = &(tpnt->modes[i]);
4346 		STm->defined = 0;
4347 		STm->sysv = ST_SYSV;
4348 		STm->defaults_for_writes = 0;
4349 		STm->do_async_writes = ST_ASYNC_WRITES;
4350 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4351 		STm->do_read_ahead = ST_READ_AHEAD;
4352 		STm->default_compression = ST_DONT_TOUCH;
4353 		STm->default_blksize = (-1);	/* No forced size */
4354 		STm->default_density = (-1);	/* No forced density */
4355 		STm->tape = tpnt;
4356 	}
4357 
4358 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4359 		STps = &(tpnt->ps[i]);
4360 		STps->rw = ST_IDLE;
4361 		STps->eof = ST_NOEOF;
4362 		STps->at_sm = 0;
4363 		STps->last_block_valid = 0;
4364 		STps->drv_block = (-1);
4365 		STps->drv_file = (-1);
4366 	}
4367 
4368 	tpnt->current_mode = 0;
4369 	tpnt->modes[0].defined = 1;
4370 
4371 	tpnt->density_changed = tpnt->compression_changed =
4372 	    tpnt->blksize_changed = 0;
4373 	mutex_init(&tpnt->lock);
4374 
4375 	idr_preload(GFP_KERNEL);
4376 	spin_lock(&st_index_lock);
4377 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4378 	spin_unlock(&st_index_lock);
4379 	idr_preload_end();
4380 	if (error < 0) {
4381 		pr_warn("st: idr allocation failed: %d\n", error);
4382 		goto out_put_queue;
4383 	}
4384 	tpnt->index = error;
4385 	sprintf(disk->disk_name, "st%d", tpnt->index);
4386 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4387 	if (tpnt->stats == NULL) {
4388 		sdev_printk(KERN_ERR, SDp,
4389 			    "st: Can't allocate statistics.\n");
4390 		goto out_idr_remove;
4391 	}
4392 
4393 	dev_set_drvdata(dev, tpnt);
4394 
4395 
4396 	error = create_cdevs(tpnt);
4397 	if (error)
4398 		goto out_remove_devs;
4399 	scsi_autopm_put_device(SDp);
4400 
4401 	sdev_printk(KERN_NOTICE, SDp,
4402 		    "Attached scsi tape %s\n", tape_name(tpnt));
4403 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4404 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4405 		    queue_dma_alignment(SDp->request_queue) + 1);
4406 
4407 	return 0;
4408 
4409 out_remove_devs:
4410 	remove_cdevs(tpnt);
4411 	kfree(tpnt->stats);
4412 out_idr_remove:
4413 	spin_lock(&st_index_lock);
4414 	idr_remove(&st_index_idr, tpnt->index);
4415 	spin_unlock(&st_index_lock);
4416 out_put_queue:
4417 	blk_put_queue(disk->queue);
4418 out_put_disk:
4419 	put_disk(disk);
4420 	kfree(tpnt);
4421 out_buffer_free:
4422 	kfree(buffer);
4423 out:
4424 	scsi_autopm_put_device(SDp);
4425 	return -ENODEV;
4426 };
4427 
4428 
4429 static int st_remove(struct device *dev)
4430 {
4431 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4432 	int index = tpnt->index;
4433 
4434 	scsi_autopm_get_device(to_scsi_device(dev));
4435 	remove_cdevs(tpnt);
4436 
4437 	mutex_lock(&st_ref_mutex);
4438 	kref_put(&tpnt->kref, scsi_tape_release);
4439 	mutex_unlock(&st_ref_mutex);
4440 	spin_lock(&st_index_lock);
4441 	idr_remove(&st_index_idr, index);
4442 	spin_unlock(&st_index_lock);
4443 	return 0;
4444 }
4445 
4446 /**
4447  *      scsi_tape_release - Called to free the Scsi_Tape structure
4448  *      @kref: pointer to embedded kref
4449  *
4450  *      st_ref_mutex must be held entering this routine.  Because it is
4451  *      called on last put, you should always use the scsi_tape_get()
4452  *      scsi_tape_put() helpers which manipulate the semaphore directly
4453  *      and never do a direct kref_put().
4454  **/
4455 static void scsi_tape_release(struct kref *kref)
4456 {
4457 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4458 	struct gendisk *disk = tpnt->disk;
4459 
4460 	tpnt->device = NULL;
4461 
4462 	if (tpnt->buffer) {
4463 		normalize_buffer(tpnt->buffer);
4464 		kfree(tpnt->buffer->reserved_pages);
4465 		kfree(tpnt->buffer);
4466 	}
4467 
4468 	disk->private_data = NULL;
4469 	put_disk(disk);
4470 	kfree(tpnt->stats);
4471 	kfree(tpnt);
4472 	return;
4473 }
4474 
4475 static struct class st_sysfs_class = {
4476 	.name = "scsi_tape",
4477 	.dev_groups = st_dev_groups,
4478 };
4479 
4480 static int __init init_st(void)
4481 {
4482 	int err;
4483 
4484 	validate_options();
4485 
4486 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4487 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4488 
4489 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4490 	if (debugging) {
4491 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4492 			debugging);
4493 	}
4494 
4495 	err = class_register(&st_sysfs_class);
4496 	if (err) {
4497 		pr_err("Unable register sysfs class for SCSI tapes\n");
4498 		return err;
4499 	}
4500 
4501 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4502 				     ST_MAX_TAPE_ENTRIES, "st");
4503 	if (err) {
4504 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4505 		       SCSI_TAPE_MAJOR);
4506 		goto err_class;
4507 	}
4508 
4509 	err = scsi_register_driver(&st_template.gendrv);
4510 	if (err)
4511 		goto err_chrdev;
4512 
4513 	return 0;
4514 
4515 err_chrdev:
4516 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4517 				 ST_MAX_TAPE_ENTRIES);
4518 err_class:
4519 	class_unregister(&st_sysfs_class);
4520 	return err;
4521 }
4522 
4523 static void __exit exit_st(void)
4524 {
4525 	scsi_unregister_driver(&st_template.gendrv);
4526 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4527 				 ST_MAX_TAPE_ENTRIES);
4528 	class_unregister(&st_sysfs_class);
4529 	idr_destroy(&st_index_idr);
4530 	printk(KERN_INFO "st: Unloaded.\n");
4531 }
4532 
4533 module_init(init_st);
4534 module_exit(exit_st);
4535 
4536 
4537 /* The sysfs driver interface. Read-only at the moment */
4538 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4539 {
4540 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4541 }
4542 static DRIVER_ATTR_RO(try_direct_io);
4543 
4544 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4545 {
4546 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4547 }
4548 static DRIVER_ATTR_RO(fixed_buffer_size);
4549 
4550 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4551 {
4552 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4553 }
4554 static DRIVER_ATTR_RO(max_sg_segs);
4555 
4556 static ssize_t version_show(struct device_driver *ddd, char *buf)
4557 {
4558 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4559 }
4560 static DRIVER_ATTR_RO(version);
4561 
4562 #if DEBUG
4563 static ssize_t debug_flag_store(struct device_driver *ddp,
4564 	const char *buf, size_t count)
4565 {
4566 /* We only care what the first byte of the data is the rest is unused.
4567  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4568  * other values have -EINVAL returned if they are passed in.
4569  */
4570 	if (count > 0) {
4571 		if (buf[0] == '0') {
4572 			debugging = NO_DEBUG;
4573 			return count;
4574 		} else if (buf[0] == '1') {
4575 			debugging = 1;
4576 			return count;
4577 		}
4578 	}
4579 	return -EINVAL;
4580 }
4581 
4582 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4583 {
4584 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4585 }
4586 static DRIVER_ATTR_RW(debug_flag);
4587 #endif
4588 
4589 static struct attribute *st_drv_attrs[] = {
4590 	&driver_attr_try_direct_io.attr,
4591 	&driver_attr_fixed_buffer_size.attr,
4592 	&driver_attr_max_sg_segs.attr,
4593 	&driver_attr_version.attr,
4594 #if DEBUG
4595 	&driver_attr_debug_flag.attr,
4596 #endif
4597 	NULL,
4598 };
4599 ATTRIBUTE_GROUPS(st_drv);
4600 
4601 /* The sysfs simple class interface */
4602 static ssize_t
4603 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4604 {
4605 	struct st_modedef *STm = dev_get_drvdata(dev);
4606 	ssize_t l = 0;
4607 
4608 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4609 	return l;
4610 }
4611 static DEVICE_ATTR_RO(defined);
4612 
4613 static ssize_t
4614 default_blksize_show(struct device *dev, struct device_attribute *attr,
4615 		     char *buf)
4616 {
4617 	struct st_modedef *STm = dev_get_drvdata(dev);
4618 	ssize_t l = 0;
4619 
4620 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4621 	return l;
4622 }
4623 static DEVICE_ATTR_RO(default_blksize);
4624 
4625 static ssize_t
4626 default_density_show(struct device *dev, struct device_attribute *attr,
4627 		     char *buf)
4628 {
4629 	struct st_modedef *STm = dev_get_drvdata(dev);
4630 	ssize_t l = 0;
4631 	char *fmt;
4632 
4633 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4634 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4635 	return l;
4636 }
4637 static DEVICE_ATTR_RO(default_density);
4638 
4639 static ssize_t
4640 default_compression_show(struct device *dev, struct device_attribute *attr,
4641 			 char *buf)
4642 {
4643 	struct st_modedef *STm = dev_get_drvdata(dev);
4644 	ssize_t l = 0;
4645 
4646 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4647 	return l;
4648 }
4649 static DEVICE_ATTR_RO(default_compression);
4650 
4651 static ssize_t
4652 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4653 {
4654 	struct st_modedef *STm = dev_get_drvdata(dev);
4655 	struct scsi_tape *STp = STm->tape;
4656 	int options;
4657 	ssize_t l = 0;
4658 
4659 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4660 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4661 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4662 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4663 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4664 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4665 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4666 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4667 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4668 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4669 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4670 	options |= STm->sysv ? MT_ST_SYSV : 0;
4671 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4672 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4673 	options |= STp->sili ? MT_ST_SILI : 0;
4674 
4675 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4676 	return l;
4677 }
4678 static DEVICE_ATTR_RO(options);
4679 
4680 /* Support for tape stats */
4681 
4682 /**
4683  * read_cnt_show - return read count - count of reads made from tape drive
4684  * @dev: struct device
4685  * @attr: attribute structure
4686  * @buf: buffer to return formatted data in
4687  */
4688 static ssize_t read_cnt_show(struct device *dev,
4689 	struct device_attribute *attr, char *buf)
4690 {
4691 	struct st_modedef *STm = dev_get_drvdata(dev);
4692 
4693 	return sprintf(buf, "%lld",
4694 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4695 }
4696 static DEVICE_ATTR_RO(read_cnt);
4697 
4698 /**
4699  * read_byte_cnt_show - return read byte count - tape drives
4700  * may use blocks less than 512 bytes this gives the raw byte count of
4701  * of data read from the tape drive.
4702  * @dev: struct device
4703  * @attr: attribute structure
4704  * @buf: buffer to return formatted data in
4705  */
4706 static ssize_t read_byte_cnt_show(struct device *dev,
4707 	struct device_attribute *attr, char *buf)
4708 {
4709 	struct st_modedef *STm = dev_get_drvdata(dev);
4710 
4711 	return sprintf(buf, "%lld",
4712 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4713 }
4714 static DEVICE_ATTR_RO(read_byte_cnt);
4715 
4716 /**
4717  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4718  * @dev: struct device
4719  * @attr: attribute structure
4720  * @buf: buffer to return formatted data in
4721  */
4722 static ssize_t read_ns_show(struct device *dev,
4723 	struct device_attribute *attr, char *buf)
4724 {
4725 	struct st_modedef *STm = dev_get_drvdata(dev);
4726 
4727 	return sprintf(buf, "%lld",
4728 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4729 }
4730 static DEVICE_ATTR_RO(read_ns);
4731 
4732 /**
4733  * write_cnt_show - write count - number of user calls
4734  * to write(2) that have written data to tape.
4735  * @dev: struct device
4736  * @attr: attribute structure
4737  * @buf: buffer to return formatted data in
4738  */
4739 static ssize_t write_cnt_show(struct device *dev,
4740 	struct device_attribute *attr, char *buf)
4741 {
4742 	struct st_modedef *STm = dev_get_drvdata(dev);
4743 
4744 	return sprintf(buf, "%lld",
4745 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4746 }
4747 static DEVICE_ATTR_RO(write_cnt);
4748 
4749 /**
4750  * write_byte_cnt_show - write byte count - raw count of
4751  * bytes written to tape.
4752  * @dev: struct device
4753  * @attr: attribute structure
4754  * @buf: buffer to return formatted data in
4755  */
4756 static ssize_t write_byte_cnt_show(struct device *dev,
4757 	struct device_attribute *attr, char *buf)
4758 {
4759 	struct st_modedef *STm = dev_get_drvdata(dev);
4760 
4761 	return sprintf(buf, "%lld",
4762 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4763 }
4764 static DEVICE_ATTR_RO(write_byte_cnt);
4765 
4766 /**
4767  * write_ns_show - write ns - number of nanoseconds waiting on write
4768  * requests to complete.
4769  * @dev: struct device
4770  * @attr: attribute structure
4771  * @buf: buffer to return formatted data in
4772  */
4773 static ssize_t write_ns_show(struct device *dev,
4774 	struct device_attribute *attr, char *buf)
4775 {
4776 	struct st_modedef *STm = dev_get_drvdata(dev);
4777 
4778 	return sprintf(buf, "%lld",
4779 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4780 }
4781 static DEVICE_ATTR_RO(write_ns);
4782 
4783 /**
4784  * in_flight_show - number of I/Os currently in flight -
4785  * in most cases this will be either 0 or 1. It may be higher if someone
4786  * has also issued other SCSI commands such as via an ioctl.
4787  * @dev: struct device
4788  * @attr: attribute structure
4789  * @buf: buffer to return formatted data in
4790  */
4791 static ssize_t in_flight_show(struct device *dev,
4792 	struct device_attribute *attr, char *buf)
4793 {
4794 	struct st_modedef *STm = dev_get_drvdata(dev);
4795 
4796 	return sprintf(buf, "%lld",
4797 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4798 }
4799 static DEVICE_ATTR_RO(in_flight);
4800 
4801 /**
4802  * io_ns_show - io wait ns - this is the number of ns spent
4803  * waiting on all I/O to complete. This includes tape movement commands
4804  * such as rewinding, seeking to end of file or tape, it also includes
4805  * read and write. To determine the time spent on tape movement
4806  * subtract the read and write ns from this value.
4807  * @dev: struct device
4808  * @attr: attribute structure
4809  * @buf: buffer to return formatted data in
4810  */
4811 static ssize_t io_ns_show(struct device *dev,
4812 	struct device_attribute *attr, char *buf)
4813 {
4814 	struct st_modedef *STm = dev_get_drvdata(dev);
4815 
4816 	return sprintf(buf, "%lld",
4817 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4818 }
4819 static DEVICE_ATTR_RO(io_ns);
4820 
4821 /**
4822  * other_cnt_show - other io count - this is the number of
4823  * I/O requests other than read and write requests.
4824  * Typically these are tape movement requests but will include driver
4825  * tape movement. This includes only requests issued by the st driver.
4826  * @dev: struct device
4827  * @attr: attribute structure
4828  * @buf: buffer to return formatted data in
4829  */
4830 static ssize_t other_cnt_show(struct device *dev,
4831 	struct device_attribute *attr, char *buf)
4832 {
4833 	struct st_modedef *STm = dev_get_drvdata(dev);
4834 
4835 	return sprintf(buf, "%lld",
4836 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4837 }
4838 static DEVICE_ATTR_RO(other_cnt);
4839 
4840 /**
4841  * resid_cnt_show - A count of the number of times we get a residual
4842  * count - this should indicate someone issuing reads larger than the
4843  * block size on tape.
4844  * @dev: struct device
4845  * @attr: attribute structure
4846  * @buf: buffer to return formatted data in
4847  */
4848 static ssize_t resid_cnt_show(struct device *dev,
4849 	struct device_attribute *attr, char *buf)
4850 {
4851 	struct st_modedef *STm = dev_get_drvdata(dev);
4852 
4853 	return sprintf(buf, "%lld",
4854 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4855 }
4856 static DEVICE_ATTR_RO(resid_cnt);
4857 
4858 static struct attribute *st_dev_attrs[] = {
4859 	&dev_attr_defined.attr,
4860 	&dev_attr_default_blksize.attr,
4861 	&dev_attr_default_density.attr,
4862 	&dev_attr_default_compression.attr,
4863 	&dev_attr_options.attr,
4864 	NULL,
4865 };
4866 
4867 static struct attribute *st_stats_attrs[] = {
4868 	&dev_attr_read_cnt.attr,
4869 	&dev_attr_read_byte_cnt.attr,
4870 	&dev_attr_read_ns.attr,
4871 	&dev_attr_write_cnt.attr,
4872 	&dev_attr_write_byte_cnt.attr,
4873 	&dev_attr_write_ns.attr,
4874 	&dev_attr_in_flight.attr,
4875 	&dev_attr_io_ns.attr,
4876 	&dev_attr_other_cnt.attr,
4877 	&dev_attr_resid_cnt.attr,
4878 	NULL,
4879 };
4880 
4881 static struct attribute_group stats_group = {
4882 	.name = "stats",
4883 	.attrs = st_stats_attrs,
4884 };
4885 
4886 static struct attribute_group st_group = {
4887 	.attrs = st_dev_attrs,
4888 };
4889 
4890 static const struct attribute_group *st_dev_groups[] = {
4891 	&st_group,
4892 	&stats_group,
4893 	NULL,
4894 };
4895 
4896 /* The following functions may be useful for a larger audience. */
4897 static int sgl_map_user_pages(struct st_buffer *STbp,
4898 			      const unsigned int max_pages, unsigned long uaddr,
4899 			      size_t count, int rw)
4900 {
4901 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4902 	unsigned long start = uaddr >> PAGE_SHIFT;
4903 	const int nr_pages = end - start;
4904 	int res, i, j;
4905 	struct page **pages;
4906 	struct rq_map_data *mdata = &STbp->map_data;
4907 
4908 	/* User attempted Overflow! */
4909 	if ((uaddr + count) < uaddr)
4910 		return -EINVAL;
4911 
4912 	/* Too big */
4913         if (nr_pages > max_pages)
4914 		return -ENOMEM;
4915 
4916 	/* Hmm? */
4917 	if (count == 0)
4918 		return 0;
4919 
4920 	pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
4921 	if (pages == NULL)
4922 		return -ENOMEM;
4923 
4924         /* Try to fault in all of the necessary pages */
4925         /* rw==READ means read from drive, write into memory area */
4926 	res = get_user_pages_fast(uaddr, nr_pages, rw == READ ? FOLL_WRITE : 0,
4927 				  pages);
4928 
4929 	/* Errors and no page mapped should return here */
4930 	if (res < nr_pages)
4931 		goto out_unmap;
4932 
4933         for (i=0; i < nr_pages; i++) {
4934                 /* FIXME: flush superflous for rw==READ,
4935                  * probably wrong function for rw==WRITE
4936                  */
4937 		flush_dcache_page(pages[i]);
4938         }
4939 
4940 	mdata->offset = uaddr & ~PAGE_MASK;
4941 	STbp->mapped_pages = pages;
4942 
4943 	return nr_pages;
4944  out_unmap:
4945 	if (res > 0) {
4946 		for (j=0; j < res; j++)
4947 			put_page(pages[j]);
4948 		res = 0;
4949 	}
4950 	kfree(pages);
4951 	return res;
4952 }
4953 
4954 
4955 /* And unmap them... */
4956 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4957 				const unsigned int nr_pages, int dirtied)
4958 {
4959 	int i;
4960 
4961 	for (i=0; i < nr_pages; i++) {
4962 		struct page *page = STbp->mapped_pages[i];
4963 
4964 		if (dirtied)
4965 			SetPageDirty(page);
4966 		/* FIXME: cache flush missing for rw==READ
4967 		 * FIXME: call the correct reference counting function
4968 		 */
4969 		put_page(page);
4970 	}
4971 	kfree(STbp->mapped_pages);
4972 	STbp->mapped_pages = NULL;
4973 
4974 	return 0;
4975 }
4976