xref: /openbmc/linux/drivers/scsi/st.c (revision 726bd223)
1 /*
2    SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
3    file Documentation/scsi/st.txt for more information.
4 
5    History:
6    Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
7    Contribution and ideas from several people including (in alphabetical
8    order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
9    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
10    Michael Schaefer, J"org Weule, and Eric Youngdale.
11 
12    Copyright 1992 - 2016 Kai Makisara
13    email Kai.Makisara@kolumbus.fi
14 
15    Some small formal changes - aeb, 950809
16 
17    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
18  */
19 
20 static const char *verstr = "20160209";
21 
22 #include <linux/module.h>
23 
24 #include <linux/fs.h>
25 #include <linux/kernel.h>
26 #include <linux/sched/signal.h>
27 #include <linux/mm.h>
28 #include <linux/init.h>
29 #include <linux/string.h>
30 #include <linux/slab.h>
31 #include <linux/errno.h>
32 #include <linux/mtio.h>
33 #include <linux/cdrom.h>
34 #include <linux/ioctl.h>
35 #include <linux/fcntl.h>
36 #include <linux/spinlock.h>
37 #include <linux/blkdev.h>
38 #include <linux/moduleparam.h>
39 #include <linux/cdev.h>
40 #include <linux/idr.h>
41 #include <linux/delay.h>
42 #include <linux/mutex.h>
43 
44 #include <linux/uaccess.h>
45 #include <asm/dma.h>
46 
47 #include <scsi/scsi.h>
48 #include <scsi/scsi_dbg.h>
49 #include <scsi/scsi_device.h>
50 #include <scsi/scsi_driver.h>
51 #include <scsi/scsi_eh.h>
52 #include <scsi/scsi_host.h>
53 #include <scsi/scsi_ioctl.h>
54 #include <scsi/sg.h>
55 
56 
57 /* The driver prints some debugging information on the console if DEBUG
58    is defined and non-zero. */
59 #define DEBUG 1
60 #define NO_DEBUG 0
61 
62 #define ST_DEB_MSG  KERN_NOTICE
63 #if DEBUG
64 /* The message level for the debug messages is currently set to KERN_NOTICE
65    so that people can easily see the messages. Later when the debugging messages
66    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
67 #define DEB(a) a
68 #define DEBC(a) if (debugging) { a ; }
69 #else
70 #define DEB(a)
71 #define DEBC(a)
72 #endif
73 
74 #define ST_KILOBYTE 1024
75 
76 #include "st_options.h"
77 #include "st.h"
78 
79 static int buffer_kbs;
80 static int max_sg_segs;
81 static int try_direct_io = TRY_DIRECT_IO;
82 static int try_rdio = 1;
83 static int try_wdio = 1;
84 static int debug_flag;
85 
86 static struct class st_sysfs_class;
87 static const struct attribute_group *st_dev_groups[];
88 static const struct attribute_group *st_drv_groups[];
89 
90 MODULE_AUTHOR("Kai Makisara");
91 MODULE_DESCRIPTION("SCSI tape (st) driver");
92 MODULE_LICENSE("GPL");
93 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
94 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
95 
96 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
97  * of sysfs parameters (which module_param doesn't yet support).
98  * Sysfs parameters defined explicitly later.
99  */
100 module_param_named(buffer_kbs, buffer_kbs, int, 0);
101 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
102 module_param_named(max_sg_segs, max_sg_segs, int, 0);
103 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
104 module_param_named(try_direct_io, try_direct_io, int, 0);
105 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
106 module_param_named(debug_flag, debug_flag, int, 0);
107 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
108 
109 
110 /* Extra parameters for testing */
111 module_param_named(try_rdio, try_rdio, int, 0);
112 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
113 module_param_named(try_wdio, try_wdio, int, 0);
114 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
115 
116 #ifndef MODULE
117 static int write_threshold_kbs;  /* retained for compatibility */
118 static struct st_dev_parm {
119 	char *name;
120 	int *val;
121 } parms[] __initdata = {
122 	{
123 		"buffer_kbs", &buffer_kbs
124 	},
125 	{       /* Retained for compatibility with 2.4 */
126 		"write_threshold_kbs", &write_threshold_kbs
127 	},
128 	{
129 		"max_sg_segs", NULL
130 	},
131 	{
132 		"try_direct_io", &try_direct_io
133 	},
134 	{
135 		"debug_flag", &debug_flag
136 	}
137 };
138 #endif
139 
140 /* Restrict the number of modes so that names for all are assigned */
141 #if ST_NBR_MODES > 16
142 #error "Maximum number of modes is 16"
143 #endif
144 /* Bit reversed order to get same names for same minors with all
145    mode counts */
146 static const char *st_formats[] = {
147 	"",  "r", "k", "s", "l", "t", "o", "u",
148 	"m", "v", "p", "x", "a", "y", "q", "z"};
149 
150 /* The default definitions have been moved to st_options.h */
151 
152 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
153 
154 /* The buffer size should fit into the 24 bits for length in the
155    6-byte SCSI read and write commands. */
156 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
157 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
158 #endif
159 
160 static int debugging = DEBUG;
161 
162 #define MAX_RETRIES 0
163 #define MAX_WRITE_RETRIES 0
164 #define MAX_READY_RETRIES 0
165 #define NO_TAPE  NOT_READY
166 
167 #define ST_TIMEOUT (900 * HZ)
168 #define ST_LONG_TIMEOUT (14000 * HZ)
169 
170 /* Remove mode bits and auto-rewind bit (7) */
171 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
172     (iminor(x) & ~(-1 << ST_MODE_SHIFT)) )
173 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
174 
175 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
176 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
177   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
178 
179 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
180    24 bits) */
181 #define SET_DENS_AND_BLK 0x10001
182 
183 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
184 static int st_max_sg_segs = ST_MAX_SG;
185 
186 static int modes_defined;
187 
188 static int enlarge_buffer(struct st_buffer *, int, int);
189 static void clear_buffer(struct st_buffer *);
190 static void normalize_buffer(struct st_buffer *);
191 static int append_to_buffer(const char __user *, struct st_buffer *, int);
192 static int from_buffer(struct st_buffer *, char __user *, int);
193 static void move_buffer_data(struct st_buffer *, int);
194 
195 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
196 			      unsigned long, size_t, int);
197 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
198 
199 static int st_probe(struct device *);
200 static int st_remove(struct device *);
201 
202 static struct scsi_driver st_template = {
203 	.gendrv = {
204 		.name		= "st",
205 		.owner		= THIS_MODULE,
206 		.probe		= st_probe,
207 		.remove		= st_remove,
208 		.groups		= st_drv_groups,
209 	},
210 };
211 
212 static int st_compression(struct scsi_tape *, int);
213 
214 static int find_partition(struct scsi_tape *);
215 static int switch_partition(struct scsi_tape *);
216 
217 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
218 
219 static void scsi_tape_release(struct kref *);
220 
221 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
222 
223 static DEFINE_MUTEX(st_ref_mutex);
224 static DEFINE_SPINLOCK(st_index_lock);
225 static DEFINE_SPINLOCK(st_use_lock);
226 static DEFINE_IDR(st_index_idr);
227 
228 
229 
230 #include "osst_detect.h"
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 		case 0x70:
341 			s->fixed_format = 1;
342 			s->flags = sense[2] & 0xe0;
343 			break;
344 		case 0x73:
345 			s->deferred = 1;
346 		case 0x72:
347 			s->fixed_format = 0;
348 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
349 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
350 			break;
351 		}
352 	}
353 }
354 
355 
356 /* Convert the result to success code */
357 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
358 {
359 	int result = SRpnt->result;
360 	u8 scode;
361 	DEB(const char *stp;)
362 	char *name = tape_name(STp);
363 	struct st_cmdstatus *cmdstatp;
364 
365 	if (!result)
366 		return 0;
367 
368 	cmdstatp = &STp->buffer->cmdstat;
369 	st_analyze_sense(SRpnt, cmdstatp);
370 
371 	if (cmdstatp->have_sense)
372 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
373 	else
374 		scode = 0;
375 
376 	DEB(
377 	if (debugging) {
378 		st_printk(ST_DEB_MSG, STp,
379 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
380 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
381 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
382 		if (cmdstatp->have_sense)
383 			__scsi_print_sense(STp->device, name,
384 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
385 	} ) /* end DEB */
386 	if (!debugging) { /* Abnormal conditions for tape */
387 		if (!cmdstatp->have_sense)
388 			st_printk(KERN_WARNING, STp,
389 			       "Error %x (driver bt 0x%x, host bt 0x%x).\n",
390 			       result, driver_byte(result), host_byte(result));
391 		else if (cmdstatp->have_sense &&
392 			 scode != NO_SENSE &&
393 			 scode != RECOVERED_ERROR &&
394 			 /* scode != UNIT_ATTENTION && */
395 			 scode != BLANK_CHECK &&
396 			 scode != VOLUME_OVERFLOW &&
397 			 SRpnt->cmd[0] != MODE_SENSE &&
398 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
399 
400 			__scsi_print_sense(STp->device, name,
401 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
402 		}
403 	}
404 
405 	if (cmdstatp->fixed_format &&
406 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
407 		if (STp->cln_sense_value)
408 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
409 					       STp->cln_sense_mask) == STp->cln_sense_value);
410 		else
411 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
412 					       STp->cln_sense_mask) != 0);
413 	}
414 	if (cmdstatp->have_sense &&
415 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
416 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
417 
418 	STp->pos_unknown |= STp->device->was_reset;
419 
420 	if (cmdstatp->have_sense &&
421 	    scode == RECOVERED_ERROR
422 #if ST_RECOVERED_WRITE_FATAL
423 	    && SRpnt->cmd[0] != WRITE_6
424 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
425 #endif
426 	    ) {
427 		STp->recover_count++;
428 		STp->recover_reg++;
429 
430 		DEB(
431 		if (debugging) {
432 			if (SRpnt->cmd[0] == READ_6)
433 				stp = "read";
434 			else if (SRpnt->cmd[0] == WRITE_6)
435 				stp = "write";
436 			else
437 				stp = "ioctl";
438 			st_printk(ST_DEB_MSG, STp,
439 				  "Recovered %s error (%d).\n",
440 				  stp, STp->recover_count);
441 		} ) /* end DEB */
442 
443 		if (cmdstatp->flags == 0)
444 			return 0;
445 	}
446 	return (-EIO);
447 }
448 
449 static struct st_request *st_allocate_request(struct scsi_tape *stp)
450 {
451 	struct st_request *streq;
452 
453 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
454 	if (streq)
455 		streq->stp = stp;
456 	else {
457 		st_printk(KERN_ERR, stp,
458 			  "Can't get SCSI request.\n");
459 		if (signal_pending(current))
460 			stp->buffer->syscall_result = -EINTR;
461 		else
462 			stp->buffer->syscall_result = -EBUSY;
463 	}
464 
465 	return streq;
466 }
467 
468 static void st_release_request(struct st_request *streq)
469 {
470 	kfree(streq);
471 }
472 
473 static void st_do_stats(struct scsi_tape *STp, struct request *req)
474 {
475 	ktime_t now;
476 
477 	now = ktime_get();
478 	if (scsi_req(req)->cmd[0] == WRITE_6) {
479 		now = ktime_sub(now, STp->stats->write_time);
480 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
481 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
482 		atomic64_inc(&STp->stats->write_cnt);
483 		if (req->errors) {
484 			atomic64_add(atomic_read(&STp->stats->last_write_size)
485 				- STp->buffer->cmdstat.residual,
486 				&STp->stats->write_byte_cnt);
487 			if (STp->buffer->cmdstat.residual > 0)
488 				atomic64_inc(&STp->stats->resid_cnt);
489 		} else
490 			atomic64_add(atomic_read(&STp->stats->last_write_size),
491 				&STp->stats->write_byte_cnt);
492 	} else if (scsi_req(req)->cmd[0] == READ_6) {
493 		now = ktime_sub(now, STp->stats->read_time);
494 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
495 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
496 		atomic64_inc(&STp->stats->read_cnt);
497 		if (req->errors) {
498 			atomic64_add(atomic_read(&STp->stats->last_read_size)
499 				- STp->buffer->cmdstat.residual,
500 				&STp->stats->read_byte_cnt);
501 			if (STp->buffer->cmdstat.residual > 0)
502 				atomic64_inc(&STp->stats->resid_cnt);
503 		} else
504 			atomic64_add(atomic_read(&STp->stats->last_read_size),
505 				&STp->stats->read_byte_cnt);
506 	} else {
507 		now = ktime_sub(now, STp->stats->other_time);
508 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
509 		atomic64_inc(&STp->stats->other_cnt);
510 	}
511 	atomic64_dec(&STp->stats->in_flight);
512 }
513 
514 static void st_scsi_execute_end(struct request *req, int uptodate)
515 {
516 	struct st_request *SRpnt = req->end_io_data;
517 	struct scsi_request *rq = scsi_req(req);
518 	struct scsi_tape *STp = SRpnt->stp;
519 	struct bio *tmp;
520 
521 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors;
522 	STp->buffer->cmdstat.residual = rq->resid_len;
523 
524 	st_do_stats(STp, req);
525 
526 	tmp = SRpnt->bio;
527 	if (rq->sense_len)
528 		memcpy(SRpnt->sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
529 	if (SRpnt->waiting)
530 		complete(SRpnt->waiting);
531 
532 	blk_rq_unmap_user(tmp);
533 	__blk_put_request(req->q, req);
534 }
535 
536 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
537 			   int data_direction, void *buffer, unsigned bufflen,
538 			   int timeout, int retries)
539 {
540 	struct request *req;
541 	struct scsi_request *rq;
542 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
543 	int err = 0;
544 	struct scsi_tape *STp = SRpnt->stp;
545 
546 	req = blk_get_request(SRpnt->stp->device->request_queue,
547 			data_direction == DMA_TO_DEVICE ?
548 			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, GFP_KERNEL);
549 	if (IS_ERR(req))
550 		return DRIVER_ERROR << 24;
551 	rq = scsi_req(req);
552 	scsi_req_init(req);
553 	req->rq_flags |= RQF_QUIET;
554 
555 	mdata->null_mapped = 1;
556 
557 	if (bufflen) {
558 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
559 				      GFP_KERNEL);
560 		if (err) {
561 			blk_put_request(req);
562 			return DRIVER_ERROR << 24;
563 		}
564 	}
565 
566 	atomic64_inc(&STp->stats->in_flight);
567 	if (cmd[0] == WRITE_6) {
568 		atomic_set(&STp->stats->last_write_size, bufflen);
569 		STp->stats->write_time = ktime_get();
570 	} else if (cmd[0] == READ_6) {
571 		atomic_set(&STp->stats->last_read_size, bufflen);
572 		STp->stats->read_time = ktime_get();
573 	} else {
574 		STp->stats->other_time = ktime_get();
575 	}
576 
577 	SRpnt->bio = req->bio;
578 	rq->cmd_len = COMMAND_SIZE(cmd[0]);
579 	memset(rq->cmd, 0, BLK_MAX_CDB);
580 	memcpy(rq->cmd, cmd, rq->cmd_len);
581 	req->timeout = timeout;
582 	req->retries = retries;
583 	req->end_io_data = SRpnt;
584 
585 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
586 	return 0;
587 }
588 
589 /* Do the scsi command. Waits until command performed if do_wait is true.
590    Otherwise write_behind_check() is used to check that the command
591    has finished. */
592 static struct st_request *
593 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
594 	   int bytes, int direction, int timeout, int retries, int do_wait)
595 {
596 	struct completion *waiting;
597 	struct rq_map_data *mdata = &STp->buffer->map_data;
598 	int ret;
599 
600 	/* if async, make sure there's no command outstanding */
601 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
602 		st_printk(KERN_ERR, STp,
603 			  "Async command already active.\n");
604 		if (signal_pending(current))
605 			(STp->buffer)->syscall_result = (-EINTR);
606 		else
607 			(STp->buffer)->syscall_result = (-EBUSY);
608 		return NULL;
609 	}
610 
611 	if (!SRpnt) {
612 		SRpnt = st_allocate_request(STp);
613 		if (!SRpnt)
614 			return NULL;
615 	}
616 
617 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
618 	   which IO is outstanding. It's nulled out when the IO completes. */
619 	if (!do_wait)
620 		(STp->buffer)->last_SRpnt = SRpnt;
621 
622 	waiting = &STp->wait;
623 	init_completion(waiting);
624 	SRpnt->waiting = waiting;
625 
626 	if (STp->buffer->do_dio) {
627 		mdata->page_order = 0;
628 		mdata->nr_entries = STp->buffer->sg_segs;
629 		mdata->pages = STp->buffer->mapped_pages;
630 	} else {
631 		mdata->page_order = STp->buffer->reserved_page_order;
632 		mdata->nr_entries =
633 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
634 		mdata->pages = STp->buffer->reserved_pages;
635 		mdata->offset = 0;
636 	}
637 
638 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
639 	STp->buffer->cmdstat.have_sense = 0;
640 	STp->buffer->syscall_result = 0;
641 
642 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
643 			      retries);
644 	if (ret) {
645 		/* could not allocate the buffer or request was too large */
646 		(STp->buffer)->syscall_result = (-EBUSY);
647 		(STp->buffer)->last_SRpnt = NULL;
648 	} else if (do_wait) {
649 		wait_for_completion(waiting);
650 		SRpnt->waiting = NULL;
651 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
652 	}
653 
654 	return SRpnt;
655 }
656 
657 
658 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
659    write has been correct but EOM early warning reached, -EIO if write ended in
660    error or zero if write successful. Asynchronous writes are used only in
661    variable block mode. */
662 static int write_behind_check(struct scsi_tape * STp)
663 {
664 	int retval = 0;
665 	struct st_buffer *STbuffer;
666 	struct st_partstat *STps;
667 	struct st_cmdstatus *cmdstatp;
668 	struct st_request *SRpnt;
669 
670 	STbuffer = STp->buffer;
671 	if (!STbuffer->writing)
672 		return 0;
673 
674 	DEB(
675 	if (STp->write_pending)
676 		STp->nbr_waits++;
677 	else
678 		STp->nbr_finished++;
679 	) /* end DEB */
680 
681 	wait_for_completion(&(STp->wait));
682 	SRpnt = STbuffer->last_SRpnt;
683 	STbuffer->last_SRpnt = NULL;
684 	SRpnt->waiting = NULL;
685 
686 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
687 	st_release_request(SRpnt);
688 
689 	STbuffer->buffer_bytes -= STbuffer->writing;
690 	STps = &(STp->ps[STp->partition]);
691 	if (STps->drv_block >= 0) {
692 		if (STp->block_size == 0)
693 			STps->drv_block++;
694 		else
695 			STps->drv_block += STbuffer->writing / STp->block_size;
696 	}
697 
698 	cmdstatp = &STbuffer->cmdstat;
699 	if (STbuffer->syscall_result) {
700 		retval = -EIO;
701 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
702 		    (cmdstatp->flags & SENSE_EOM) &&
703 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
704 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
705 			/* EOM at write-behind, has all data been written? */
706 			if (!cmdstatp->remainder_valid ||
707 			    cmdstatp->uremainder64 == 0)
708 				retval = -ENOSPC;
709 		}
710 		if (retval == -EIO)
711 			STps->drv_block = -1;
712 	}
713 	STbuffer->writing = 0;
714 
715 	DEB(if (debugging && retval)
716 		    st_printk(ST_DEB_MSG, STp,
717 				"Async write error %x, return value %d.\n",
718 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
719 
720 	return retval;
721 }
722 
723 
724 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
725    it messes up the block number). */
726 static int cross_eof(struct scsi_tape * STp, int forward)
727 {
728 	struct st_request *SRpnt;
729 	unsigned char cmd[MAX_COMMAND_SIZE];
730 
731 	cmd[0] = SPACE;
732 	cmd[1] = 0x01;		/* Space FileMarks */
733 	if (forward) {
734 		cmd[2] = cmd[3] = 0;
735 		cmd[4] = 1;
736 	} else
737 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
738 	cmd[5] = 0;
739 
740 	DEBC_printk(STp, "Stepping over filemark %s.\n",
741 		    forward ? "forward" : "backward");
742 
743 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
744 			   STp->device->request_queue->rq_timeout,
745 			   MAX_RETRIES, 1);
746 	if (!SRpnt)
747 		return (STp->buffer)->syscall_result;
748 
749 	st_release_request(SRpnt);
750 	SRpnt = NULL;
751 
752 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
753 		st_printk(KERN_ERR, STp,
754 			  "Stepping over filemark %s failed.\n",
755 			  forward ? "forward" : "backward");
756 
757 	return (STp->buffer)->syscall_result;
758 }
759 
760 
761 /* Flush the write buffer (never need to write if variable blocksize). */
762 static int st_flush_write_buffer(struct scsi_tape * STp)
763 {
764 	int transfer, blks;
765 	int result;
766 	unsigned char cmd[MAX_COMMAND_SIZE];
767 	struct st_request *SRpnt;
768 	struct st_partstat *STps;
769 
770 	result = write_behind_check(STp);
771 	if (result)
772 		return result;
773 
774 	result = 0;
775 	if (STp->dirty == 1) {
776 
777 		transfer = STp->buffer->buffer_bytes;
778 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
779 
780 		memset(cmd, 0, MAX_COMMAND_SIZE);
781 		cmd[0] = WRITE_6;
782 		cmd[1] = 1;
783 		blks = transfer / STp->block_size;
784 		cmd[2] = blks >> 16;
785 		cmd[3] = blks >> 8;
786 		cmd[4] = blks;
787 
788 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
789 				   STp->device->request_queue->rq_timeout,
790 				   MAX_WRITE_RETRIES, 1);
791 		if (!SRpnt)
792 			return (STp->buffer)->syscall_result;
793 
794 		STps = &(STp->ps[STp->partition]);
795 		if ((STp->buffer)->syscall_result != 0) {
796 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
797 
798 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
799 			    (cmdstatp->flags & SENSE_EOM) &&
800 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
801 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
802 			    (!cmdstatp->remainder_valid ||
803 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
804 				STp->dirty = 0;
805 				(STp->buffer)->buffer_bytes = 0;
806 				if (STps->drv_block >= 0)
807 					STps->drv_block += blks;
808 				result = (-ENOSPC);
809 			} else {
810 				st_printk(KERN_ERR, STp, "Error on flush.\n");
811 				STps->drv_block = (-1);
812 				result = (-EIO);
813 			}
814 		} else {
815 			if (STps->drv_block >= 0)
816 				STps->drv_block += blks;
817 			STp->dirty = 0;
818 			(STp->buffer)->buffer_bytes = 0;
819 		}
820 		st_release_request(SRpnt);
821 		SRpnt = NULL;
822 	}
823 	return result;
824 }
825 
826 
827 /* Flush the tape buffer. The tape will be positioned correctly unless
828    seek_next is true. */
829 static int flush_buffer(struct scsi_tape *STp, int seek_next)
830 {
831 	int backspace, result;
832 	struct st_buffer *STbuffer;
833 	struct st_partstat *STps;
834 
835 	STbuffer = STp->buffer;
836 
837 	/*
838 	 * If there was a bus reset, block further access
839 	 * to this device.
840 	 */
841 	if (STp->pos_unknown)
842 		return (-EIO);
843 
844 	if (STp->ready != ST_READY)
845 		return 0;
846 	STps = &(STp->ps[STp->partition]);
847 	if (STps->rw == ST_WRITING)	/* Writing */
848 		return st_flush_write_buffer(STp);
849 
850 	if (STp->block_size == 0)
851 		return 0;
852 
853 	backspace = ((STp->buffer)->buffer_bytes +
854 		     (STp->buffer)->read_pointer) / STp->block_size -
855 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
856 	    STp->block_size;
857 	(STp->buffer)->buffer_bytes = 0;
858 	(STp->buffer)->read_pointer = 0;
859 	result = 0;
860 	if (!seek_next) {
861 		if (STps->eof == ST_FM_HIT) {
862 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
863 			if (!result)
864 				STps->eof = ST_NOEOF;
865 			else {
866 				if (STps->drv_file >= 0)
867 					STps->drv_file++;
868 				STps->drv_block = 0;
869 			}
870 		}
871 		if (!result && backspace > 0)
872 			result = st_int_ioctl(STp, MTBSR, backspace);
873 	} else if (STps->eof == ST_FM_HIT) {
874 		if (STps->drv_file >= 0)
875 			STps->drv_file++;
876 		STps->drv_block = 0;
877 		STps->eof = ST_NOEOF;
878 	}
879 	return result;
880 
881 }
882 
883 /* Set the mode parameters */
884 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
885 {
886 	int set_it = 0;
887 	unsigned long arg;
888 
889 	if (!STp->density_changed &&
890 	    STm->default_density >= 0 &&
891 	    STm->default_density != STp->density) {
892 		arg = STm->default_density;
893 		set_it = 1;
894 	} else
895 		arg = STp->density;
896 	arg <<= MT_ST_DENSITY_SHIFT;
897 	if (!STp->blksize_changed &&
898 	    STm->default_blksize >= 0 &&
899 	    STm->default_blksize != STp->block_size) {
900 		arg |= STm->default_blksize;
901 		set_it = 1;
902 	} else
903 		arg |= STp->block_size;
904 	if (set_it &&
905 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
906 		st_printk(KERN_WARNING, STp,
907 			  "Can't set default block size to %d bytes "
908 			  "and density %x.\n",
909 			  STm->default_blksize, STm->default_density);
910 		if (modes_defined)
911 			return (-EINVAL);
912 	}
913 	return 0;
914 }
915 
916 
917 /* Lock or unlock the drive door. Don't use when st_request allocated. */
918 static int do_door_lock(struct scsi_tape * STp, int do_lock)
919 {
920 	int retval;
921 
922 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
923 
924 	retval = scsi_set_medium_removal(STp->device,
925 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
926 	if (!retval)
927 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
928 	else
929 		STp->door_locked = ST_LOCK_FAILS;
930 	return retval;
931 }
932 
933 
934 /* Set the internal state after reset */
935 static void reset_state(struct scsi_tape *STp)
936 {
937 	int i;
938 	struct st_partstat *STps;
939 
940 	STp->pos_unknown = 0;
941 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
942 		STps = &(STp->ps[i]);
943 		STps->rw = ST_IDLE;
944 		STps->eof = ST_NOEOF;
945 		STps->at_sm = 0;
946 		STps->last_block_valid = 0;
947 		STps->drv_block = -1;
948 		STps->drv_file = -1;
949 	}
950 	if (STp->can_partitions) {
951 		STp->partition = find_partition(STp);
952 		if (STp->partition < 0)
953 			STp->partition = 0;
954 		STp->new_partition = STp->partition;
955 	}
956 }
957 
958 /* Test if the drive is ready. Returns either one of the codes below or a negative system
959    error code. */
960 #define CHKRES_READY       0
961 #define CHKRES_NEW_SESSION 1
962 #define CHKRES_NOT_READY   2
963 #define CHKRES_NO_TAPE     3
964 
965 #define MAX_ATTENTIONS    10
966 
967 static int test_ready(struct scsi_tape *STp, int do_wait)
968 {
969 	int attentions, waits, max_wait, scode;
970 	int retval = CHKRES_READY, new_session = 0;
971 	unsigned char cmd[MAX_COMMAND_SIZE];
972 	struct st_request *SRpnt = NULL;
973 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
974 
975 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
976 
977 	for (attentions=waits=0; ; ) {
978 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
979 		cmd[0] = TEST_UNIT_READY;
980 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
981 				   STp->long_timeout, MAX_READY_RETRIES, 1);
982 
983 		if (!SRpnt) {
984 			retval = (STp->buffer)->syscall_result;
985 			break;
986 		}
987 
988 		if (cmdstatp->have_sense) {
989 
990 			scode = cmdstatp->sense_hdr.sense_key;
991 
992 			if (scode == UNIT_ATTENTION) { /* New media? */
993 				new_session = 1;
994 				if (attentions < MAX_ATTENTIONS) {
995 					attentions++;
996 					continue;
997 				}
998 				else {
999 					retval = (-EIO);
1000 					break;
1001 				}
1002 			}
1003 
1004 			if (scode == NOT_READY) {
1005 				if (waits < max_wait) {
1006 					if (msleep_interruptible(1000)) {
1007 						retval = (-EINTR);
1008 						break;
1009 					}
1010 					waits++;
1011 					continue;
1012 				}
1013 				else {
1014 					if ((STp->device)->scsi_level >= SCSI_2 &&
1015 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1016 						retval = CHKRES_NO_TAPE;
1017 					else
1018 						retval = CHKRES_NOT_READY;
1019 					break;
1020 				}
1021 			}
1022 		}
1023 
1024 		retval = (STp->buffer)->syscall_result;
1025 		if (!retval)
1026 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1027 		break;
1028 	}
1029 
1030 	if (SRpnt != NULL)
1031 		st_release_request(SRpnt);
1032 	return retval;
1033 }
1034 
1035 
1036 /* See if the drive is ready and gather information about the tape. Return values:
1037    < 0   negative error code from errno.h
1038    0     drive ready
1039    1     drive not ready (possibly no tape)
1040 */
1041 static int check_tape(struct scsi_tape *STp, struct file *filp)
1042 {
1043 	int i, retval, new_session = 0, do_wait;
1044 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1045 	unsigned short st_flags = filp->f_flags;
1046 	struct st_request *SRpnt = NULL;
1047 	struct st_modedef *STm;
1048 	struct st_partstat *STps;
1049 	struct inode *inode = file_inode(filp);
1050 	int mode = TAPE_MODE(inode);
1051 
1052 	STp->ready = ST_READY;
1053 
1054 	if (mode != STp->current_mode) {
1055 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1056 			    STp->current_mode, mode);
1057 		new_session = 1;
1058 		STp->current_mode = mode;
1059 	}
1060 	STm = &(STp->modes[STp->current_mode]);
1061 
1062 	saved_cleaning = STp->cleaning_req;
1063 	STp->cleaning_req = 0;
1064 
1065 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1066 	retval = test_ready(STp, do_wait);
1067 
1068 	if (retval < 0)
1069 	    goto err_out;
1070 
1071 	if (retval == CHKRES_NEW_SESSION) {
1072 		STp->pos_unknown = 0;
1073 		STp->partition = STp->new_partition = 0;
1074 		if (STp->can_partitions)
1075 			STp->nbr_partitions = 1; /* This guess will be updated later
1076                                                     if necessary */
1077 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1078 			STps = &(STp->ps[i]);
1079 			STps->rw = ST_IDLE;
1080 			STps->eof = ST_NOEOF;
1081 			STps->at_sm = 0;
1082 			STps->last_block_valid = 0;
1083 			STps->drv_block = 0;
1084 			STps->drv_file = 0;
1085 		}
1086 		new_session = 1;
1087 	}
1088 	else {
1089 		STp->cleaning_req |= saved_cleaning;
1090 
1091 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1092 			if (retval == CHKRES_NO_TAPE)
1093 				STp->ready = ST_NO_TAPE;
1094 			else
1095 				STp->ready = ST_NOT_READY;
1096 
1097 			STp->density = 0;	/* Clear the erroneous "residue" */
1098 			STp->write_prot = 0;
1099 			STp->block_size = 0;
1100 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1101 			STp->partition = STp->new_partition = 0;
1102 			STp->door_locked = ST_UNLOCKED;
1103 			return CHKRES_NOT_READY;
1104 		}
1105 	}
1106 
1107 	if (STp->omit_blklims)
1108 		STp->min_block = STp->max_block = (-1);
1109 	else {
1110 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1111 		cmd[0] = READ_BLOCK_LIMITS;
1112 
1113 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1114 				   STp->device->request_queue->rq_timeout,
1115 				   MAX_READY_RETRIES, 1);
1116 		if (!SRpnt) {
1117 			retval = (STp->buffer)->syscall_result;
1118 			goto err_out;
1119 		}
1120 
1121 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1122 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1123 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1124 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1125 			    (STp->buffer)->b_data[5];
1126 			if ( DEB( debugging || ) !STp->inited)
1127 				st_printk(KERN_INFO, STp,
1128 					  "Block limits %d - %d bytes.\n",
1129 					  STp->min_block, STp->max_block);
1130 		} else {
1131 			STp->min_block = STp->max_block = (-1);
1132 			DEBC_printk(STp, "Can't read block limits.\n");
1133 		}
1134 	}
1135 
1136 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1137 	cmd[0] = MODE_SENSE;
1138 	cmd[4] = 12;
1139 
1140 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1141 			   STp->device->request_queue->rq_timeout,
1142 			   MAX_READY_RETRIES, 1);
1143 	if (!SRpnt) {
1144 		retval = (STp->buffer)->syscall_result;
1145 		goto err_out;
1146 	}
1147 
1148 	if ((STp->buffer)->syscall_result != 0) {
1149 		DEBC_printk(STp, "No Mode Sense.\n");
1150 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1151 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1152 		STp->drv_write_prot = 0;
1153 	} else {
1154 		DEBC_printk(STp,"Mode sense. Length %d, "
1155 			    "medium %x, WBS %x, BLL %d\n",
1156 			    (STp->buffer)->b_data[0],
1157 			    (STp->buffer)->b_data[1],
1158 			    (STp->buffer)->b_data[2],
1159 			    (STp->buffer)->b_data[3]);
1160 
1161 		if ((STp->buffer)->b_data[3] >= 8) {
1162 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1163 			STp->density = (STp->buffer)->b_data[4];
1164 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1165 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1166 			DEBC_printk(STp, "Density %x, tape length: %x, "
1167 				    "drv buffer: %d\n",
1168 				    STp->density,
1169 				    (STp->buffer)->b_data[5] * 65536 +
1170 				    (STp->buffer)->b_data[6] * 256 +
1171 				    (STp->buffer)->b_data[7],
1172 				    STp->drv_buffer);
1173 		}
1174 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1175 		if (!STp->drv_buffer && STp->immediate_filemark) {
1176 			st_printk(KERN_WARNING, STp,
1177 				  "non-buffered tape: disabling "
1178 				  "writing immediate filemarks\n");
1179 			STp->immediate_filemark = 0;
1180 		}
1181 	}
1182 	st_release_request(SRpnt);
1183 	SRpnt = NULL;
1184 	STp->inited = 1;
1185 
1186 	if (STp->block_size > 0)
1187 		(STp->buffer)->buffer_blocks =
1188 			(STp->buffer)->buffer_size / STp->block_size;
1189 	else
1190 		(STp->buffer)->buffer_blocks = 1;
1191 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1192 
1193 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1194 		    STp->block_size, (STp->buffer)->buffer_size,
1195 		    (STp->buffer)->buffer_blocks);
1196 
1197 	if (STp->drv_write_prot) {
1198 		STp->write_prot = 1;
1199 
1200 		DEBC_printk(STp, "Write protected\n");
1201 
1202 		if (do_wait &&
1203 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1204 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1205 			retval = (-EROFS);
1206 			goto err_out;
1207 		}
1208 	}
1209 
1210 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1211 		/* This code is reached when the device is opened for the first time
1212 		   after the driver has been initialized with tape in the drive and the
1213 		   partition support has been enabled. */
1214 		DEBC_printk(STp, "Updating partition number in status.\n");
1215 		if ((STp->partition = find_partition(STp)) < 0) {
1216 			retval = STp->partition;
1217 			goto err_out;
1218 		}
1219 		STp->new_partition = STp->partition;
1220 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1221 	}
1222 
1223 	if (new_session) {	/* Change the drive parameters for the new mode */
1224 		STp->density_changed = STp->blksize_changed = 0;
1225 		STp->compression_changed = 0;
1226 		if (!(STm->defaults_for_writes) &&
1227 		    (retval = set_mode_densblk(STp, STm)) < 0)
1228 		    goto err_out;
1229 
1230 		if (STp->default_drvbuffer != 0xff) {
1231 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1232 				st_printk(KERN_WARNING, STp,
1233 					  "Can't set default drive "
1234 					  "buffering to %d.\n",
1235 					  STp->default_drvbuffer);
1236 		}
1237 	}
1238 
1239 	return CHKRES_READY;
1240 
1241  err_out:
1242 	return retval;
1243 }
1244 
1245 
1246 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1247    module count. */
1248 static int st_open(struct inode *inode, struct file *filp)
1249 {
1250 	int i, retval = (-EIO);
1251 	int resumed = 0;
1252 	struct scsi_tape *STp;
1253 	struct st_partstat *STps;
1254 	int dev = TAPE_NR(inode);
1255 
1256 	/*
1257 	 * We really want to do nonseekable_open(inode, filp); here, but some
1258 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1259 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1260 	 */
1261 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1262 
1263 	if (!(STp = scsi_tape_get(dev))) {
1264 		return -ENXIO;
1265 	}
1266 
1267 	filp->private_data = STp;
1268 
1269 	spin_lock(&st_use_lock);
1270 	if (STp->in_use) {
1271 		spin_unlock(&st_use_lock);
1272 		scsi_tape_put(STp);
1273 		DEBC_printk(STp, "Device already in use.\n");
1274 		return (-EBUSY);
1275 	}
1276 
1277 	STp->in_use = 1;
1278 	spin_unlock(&st_use_lock);
1279 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1280 
1281 	if (scsi_autopm_get_device(STp->device) < 0) {
1282 		retval = -EIO;
1283 		goto err_out;
1284 	}
1285 	resumed = 1;
1286 	if (!scsi_block_when_processing_errors(STp->device)) {
1287 		retval = (-ENXIO);
1288 		goto err_out;
1289 	}
1290 
1291 	/* See that we have at least a one page buffer available */
1292 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
1293 		st_printk(KERN_WARNING, STp,
1294 			  "Can't allocate one page tape buffer.\n");
1295 		retval = (-EOVERFLOW);
1296 		goto err_out;
1297 	}
1298 
1299 	(STp->buffer)->cleared = 0;
1300 	(STp->buffer)->writing = 0;
1301 	(STp->buffer)->syscall_result = 0;
1302 
1303 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1304 
1305 	STp->dirty = 0;
1306 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1307 		STps = &(STp->ps[i]);
1308 		STps->rw = ST_IDLE;
1309 	}
1310 	STp->try_dio_now = STp->try_dio;
1311 	STp->recover_count = 0;
1312 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1313 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1314 
1315 	retval = check_tape(STp, filp);
1316 	if (retval < 0)
1317 		goto err_out;
1318 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1319 	    retval != CHKRES_READY) {
1320 		if (STp->ready == NO_TAPE)
1321 			retval = (-ENOMEDIUM);
1322 		else
1323 			retval = (-EIO);
1324 		goto err_out;
1325 	}
1326 	return 0;
1327 
1328  err_out:
1329 	normalize_buffer(STp->buffer);
1330 	spin_lock(&st_use_lock);
1331 	STp->in_use = 0;
1332 	spin_unlock(&st_use_lock);
1333 	if (resumed)
1334 		scsi_autopm_put_device(STp->device);
1335 	scsi_tape_put(STp);
1336 	return retval;
1337 
1338 }
1339 
1340 
1341 /* Flush the tape buffer before close */
1342 static int st_flush(struct file *filp, fl_owner_t id)
1343 {
1344 	int result = 0, result2;
1345 	unsigned char cmd[MAX_COMMAND_SIZE];
1346 	struct st_request *SRpnt;
1347 	struct scsi_tape *STp = filp->private_data;
1348 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1349 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1350 
1351 	if (file_count(filp) > 1)
1352 		return 0;
1353 
1354 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1355 		result = st_flush_write_buffer(STp);
1356 		if (result != 0 && result != (-ENOSPC))
1357 			goto out;
1358 	}
1359 
1360 	if (STp->can_partitions &&
1361 	    (result2 = switch_partition(STp)) < 0) {
1362 		DEBC_printk(STp, "switch_partition at close failed.\n");
1363 		if (result == 0)
1364 			result = result2;
1365 		goto out;
1366 	}
1367 
1368 	DEBC( if (STp->nbr_requests)
1369 		st_printk(KERN_DEBUG, STp,
1370 			  "Number of r/w requests %d, dio used in %d, "
1371 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1372 			  STp->nbr_pages));
1373 
1374 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1375 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1376 
1377 #if DEBUG
1378 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1379 			    STp->nbr_waits, STp->nbr_finished);
1380 #endif
1381 		memset(cmd, 0, MAX_COMMAND_SIZE);
1382 		cmd[0] = WRITE_FILEMARKS;
1383 		if (STp->immediate_filemark)
1384 			cmd[1] = 1;
1385 		cmd[4] = 1 + STp->two_fm;
1386 
1387 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1388 				   STp->device->request_queue->rq_timeout,
1389 				   MAX_WRITE_RETRIES, 1);
1390 		if (!SRpnt) {
1391 			result = (STp->buffer)->syscall_result;
1392 			goto out;
1393 		}
1394 
1395 		if (STp->buffer->syscall_result == 0 ||
1396 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1397 		     (cmdstatp->flags & SENSE_EOM) &&
1398 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1399 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1400 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1401 			/* Write successful at EOM */
1402 			st_release_request(SRpnt);
1403 			SRpnt = NULL;
1404 			if (STps->drv_file >= 0)
1405 				STps->drv_file++;
1406 			STps->drv_block = 0;
1407 			if (STp->two_fm)
1408 				cross_eof(STp, 0);
1409 			STps->eof = ST_FM;
1410 		}
1411 		else { /* Write error */
1412 			st_release_request(SRpnt);
1413 			SRpnt = NULL;
1414 			st_printk(KERN_ERR, STp,
1415 				  "Error on write filemark.\n");
1416 			if (result == 0)
1417 				result = (-EIO);
1418 		}
1419 
1420 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1421 	} else if (!STp->rew_at_close) {
1422 		STps = &(STp->ps[STp->partition]);
1423 		if (!STm->sysv || STps->rw != ST_READING) {
1424 			if (STp->can_bsr)
1425 				result = flush_buffer(STp, 0);
1426 			else if (STps->eof == ST_FM_HIT) {
1427 				result = cross_eof(STp, 0);
1428 				if (result) {
1429 					if (STps->drv_file >= 0)
1430 						STps->drv_file++;
1431 					STps->drv_block = 0;
1432 					STps->eof = ST_FM;
1433 				} else
1434 					STps->eof = ST_NOEOF;
1435 			}
1436 		} else if ((STps->eof == ST_NOEOF &&
1437 			    !(result = cross_eof(STp, 1))) ||
1438 			   STps->eof == ST_FM_HIT) {
1439 			if (STps->drv_file >= 0)
1440 				STps->drv_file++;
1441 			STps->drv_block = 0;
1442 			STps->eof = ST_FM;
1443 		}
1444 	}
1445 
1446       out:
1447 	if (STp->rew_at_close) {
1448 		result2 = st_int_ioctl(STp, MTREW, 1);
1449 		if (result == 0)
1450 			result = result2;
1451 	}
1452 	return result;
1453 }
1454 
1455 
1456 /* Close the device and release it. BKL is not needed: this is the only thread
1457    accessing this tape. */
1458 static int st_release(struct inode *inode, struct file *filp)
1459 {
1460 	int result = 0;
1461 	struct scsi_tape *STp = filp->private_data;
1462 
1463 	if (STp->door_locked == ST_LOCKED_AUTO)
1464 		do_door_lock(STp, 0);
1465 
1466 	normalize_buffer(STp->buffer);
1467 	spin_lock(&st_use_lock);
1468 	STp->in_use = 0;
1469 	spin_unlock(&st_use_lock);
1470 	scsi_autopm_put_device(STp->device);
1471 	scsi_tape_put(STp);
1472 
1473 	return result;
1474 }
1475 
1476 /* The checks common to both reading and writing */
1477 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1478 {
1479 	ssize_t retval = 0;
1480 
1481 	/*
1482 	 * If we are in the middle of error recovery, don't let anyone
1483 	 * else try and use this device.  Also, if error recovery fails, it
1484 	 * may try and take the device offline, in which case all further
1485 	 * access to the device is prohibited.
1486 	 */
1487 	if (!scsi_block_when_processing_errors(STp->device)) {
1488 		retval = (-ENXIO);
1489 		goto out;
1490 	}
1491 
1492 	if (STp->ready != ST_READY) {
1493 		if (STp->ready == ST_NO_TAPE)
1494 			retval = (-ENOMEDIUM);
1495 		else
1496 			retval = (-EIO);
1497 		goto out;
1498 	}
1499 
1500 	if (! STp->modes[STp->current_mode].defined) {
1501 		retval = (-ENXIO);
1502 		goto out;
1503 	}
1504 
1505 
1506 	/*
1507 	 * If there was a bus reset, block further access
1508 	 * to this device.
1509 	 */
1510 	if (STp->pos_unknown) {
1511 		retval = (-EIO);
1512 		goto out;
1513 	}
1514 
1515 	if (count == 0)
1516 		goto out;
1517 
1518 	DEB(
1519 	if (!STp->in_use) {
1520 		st_printk(ST_DEB_MSG, STp,
1521 			  "Incorrect device.\n");
1522 		retval = (-EIO);
1523 		goto out;
1524 	} ) /* end DEB */
1525 
1526 	if (STp->can_partitions &&
1527 	    (retval = switch_partition(STp)) < 0)
1528 		goto out;
1529 
1530 	if (STp->block_size == 0 && STp->max_block > 0 &&
1531 	    (count < STp->min_block || count > STp->max_block)) {
1532 		retval = (-EINVAL);
1533 		goto out;
1534 	}
1535 
1536 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1537 	    !do_door_lock(STp, 1))
1538 		STp->door_locked = ST_LOCKED_AUTO;
1539 
1540  out:
1541 	return retval;
1542 }
1543 
1544 
1545 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1546 			   size_t count, int is_read)
1547 {
1548 	int i, bufsize, retval = 0;
1549 	struct st_buffer *STbp = STp->buffer;
1550 
1551 	if (is_read)
1552 		i = STp->try_dio_now && try_rdio;
1553 	else
1554 		i = STp->try_dio_now && try_wdio;
1555 
1556 	if (i && ((unsigned long)buf & queue_dma_alignment(
1557 					STp->device->request_queue)) == 0) {
1558 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1559 				       count, (is_read ? READ : WRITE));
1560 		if (i > 0) {
1561 			STbp->do_dio = i;
1562 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1563 		}
1564 		else
1565 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1566 		STbp->sg_segs = STbp->do_dio;
1567 		DEB(
1568 		     if (STbp->do_dio) {
1569 			STp->nbr_dio++;
1570 			STp->nbr_pages += STbp->do_dio;
1571 		     }
1572 		)
1573 	} else
1574 		STbp->do_dio = 0;
1575 	DEB( STp->nbr_requests++; )
1576 
1577 	if (!STbp->do_dio) {
1578 		if (STp->block_size)
1579 			bufsize = STp->block_size > st_fixed_buffer_size ?
1580 				STp->block_size : st_fixed_buffer_size;
1581 		else {
1582 			bufsize = count;
1583 			/* Make sure that data from previous user is not leaked even if
1584 			   HBA does not return correct residual */
1585 			if (is_read && STp->sili && !STbp->cleared)
1586 				clear_buffer(STbp);
1587 		}
1588 
1589 		if (bufsize > STbp->buffer_size &&
1590 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1591 			st_printk(KERN_WARNING, STp,
1592 				  "Can't allocate %d byte tape buffer.\n",
1593 				  bufsize);
1594 			retval = (-EOVERFLOW);
1595 			goto out;
1596 		}
1597 		if (STp->block_size)
1598 			STbp->buffer_blocks = bufsize / STp->block_size;
1599 	}
1600 
1601  out:
1602 	return retval;
1603 }
1604 
1605 
1606 /* Can be called more than once after each setup_buffer() */
1607 static void release_buffering(struct scsi_tape *STp, int is_read)
1608 {
1609 	struct st_buffer *STbp;
1610 
1611 	STbp = STp->buffer;
1612 	if (STbp->do_dio) {
1613 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1614 		STbp->do_dio = 0;
1615 		STbp->sg_segs = 0;
1616 	}
1617 }
1618 
1619 
1620 /* Write command */
1621 static ssize_t
1622 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1623 {
1624 	ssize_t total;
1625 	ssize_t i, do_count, blks, transfer;
1626 	ssize_t retval;
1627 	int undone, retry_eot = 0, scode;
1628 	int async_write;
1629 	unsigned char cmd[MAX_COMMAND_SIZE];
1630 	const char __user *b_point;
1631 	struct st_request *SRpnt = NULL;
1632 	struct scsi_tape *STp = filp->private_data;
1633 	struct st_modedef *STm;
1634 	struct st_partstat *STps;
1635 	struct st_buffer *STbp;
1636 
1637 	if (mutex_lock_interruptible(&STp->lock))
1638 		return -ERESTARTSYS;
1639 
1640 	retval = rw_checks(STp, filp, count);
1641 	if (retval || count == 0)
1642 		goto out;
1643 
1644 	/* Write must be integral number of blocks */
1645 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1646 		st_printk(KERN_WARNING, STp,
1647 			  "Write not multiple of tape block size.\n");
1648 		retval = (-EINVAL);
1649 		goto out;
1650 	}
1651 
1652 	STm = &(STp->modes[STp->current_mode]);
1653 	STps = &(STp->ps[STp->partition]);
1654 
1655 	if (STp->write_prot) {
1656 		retval = (-EACCES);
1657 		goto out;
1658 	}
1659 
1660 
1661 	if (STps->rw == ST_READING) {
1662 		retval = flush_buffer(STp, 0);
1663 		if (retval)
1664 			goto out;
1665 		STps->rw = ST_WRITING;
1666 	} else if (STps->rw != ST_WRITING &&
1667 		   STps->drv_file == 0 && STps->drv_block == 0) {
1668 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1669 			goto out;
1670 		if (STm->default_compression != ST_DONT_TOUCH &&
1671 		    !(STp->compression_changed)) {
1672 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1673 				st_printk(KERN_WARNING, STp,
1674 					  "Can't set default compression.\n");
1675 				if (modes_defined) {
1676 					retval = (-EINVAL);
1677 					goto out;
1678 				}
1679 			}
1680 		}
1681 	}
1682 
1683 	STbp = STp->buffer;
1684 	i = write_behind_check(STp);
1685 	if (i) {
1686 		if (i == -ENOSPC)
1687 			STps->eof = ST_EOM_OK;
1688 		else
1689 			STps->eof = ST_EOM_ERROR;
1690 	}
1691 
1692 	if (STps->eof == ST_EOM_OK) {
1693 		STps->eof = ST_EOD_1;  /* allow next write */
1694 		retval = (-ENOSPC);
1695 		goto out;
1696 	}
1697 	else if (STps->eof == ST_EOM_ERROR) {
1698 		retval = (-EIO);
1699 		goto out;
1700 	}
1701 
1702 	/* Check the buffer readability in cases where copy_user might catch
1703 	   the problems after some tape movement. */
1704 	if (STp->block_size != 0 &&
1705 	    !STbp->do_dio &&
1706 	    (copy_from_user(&i, buf, 1) != 0 ||
1707 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1708 		retval = (-EFAULT);
1709 		goto out;
1710 	}
1711 
1712 	retval = setup_buffering(STp, buf, count, 0);
1713 	if (retval)
1714 		goto out;
1715 
1716 	total = count;
1717 
1718 	memset(cmd, 0, MAX_COMMAND_SIZE);
1719 	cmd[0] = WRITE_6;
1720 	cmd[1] = (STp->block_size != 0);
1721 
1722 	STps->rw = ST_WRITING;
1723 
1724 	b_point = buf;
1725 	while (count > 0 && !retry_eot) {
1726 
1727 		if (STbp->do_dio) {
1728 			do_count = count;
1729 		}
1730 		else {
1731 			if (STp->block_size == 0)
1732 				do_count = count;
1733 			else {
1734 				do_count = STbp->buffer_blocks * STp->block_size -
1735 					STbp->buffer_bytes;
1736 				if (do_count > count)
1737 					do_count = count;
1738 			}
1739 
1740 			i = append_to_buffer(b_point, STbp, do_count);
1741 			if (i) {
1742 				retval = i;
1743 				goto out;
1744 			}
1745 		}
1746 		count -= do_count;
1747 		b_point += do_count;
1748 
1749 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1750 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1751 
1752 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1753 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1754 		    STbp->buffer_bytes < STbp->buffer_size) {
1755 			STp->dirty = 1;
1756 			/* Don't write a buffer that is not full enough. */
1757 			if (!async_write && count == 0)
1758 				break;
1759 		}
1760 
1761 	retry_write:
1762 		if (STp->block_size == 0)
1763 			blks = transfer = do_count;
1764 		else {
1765 			if (!STbp->do_dio)
1766 				blks = STbp->buffer_bytes;
1767 			else
1768 				blks = do_count;
1769 			blks /= STp->block_size;
1770 			transfer = blks * STp->block_size;
1771 		}
1772 		cmd[2] = blks >> 16;
1773 		cmd[3] = blks >> 8;
1774 		cmd[4] = blks;
1775 
1776 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1777 				   STp->device->request_queue->rq_timeout,
1778 				   MAX_WRITE_RETRIES, !async_write);
1779 		if (!SRpnt) {
1780 			retval = STbp->syscall_result;
1781 			goto out;
1782 		}
1783 		if (async_write && !STbp->syscall_result) {
1784 			STbp->writing = transfer;
1785 			STp->dirty = !(STbp->writing ==
1786 				       STbp->buffer_bytes);
1787 			SRpnt = NULL;  /* Prevent releasing this request! */
1788 			DEB( STp->write_pending = 1; )
1789 			break;
1790 		}
1791 
1792 		if (STbp->syscall_result != 0) {
1793 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1794 
1795 			DEBC_printk(STp, "Error on write:\n");
1796 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1797 				scode = cmdstatp->sense_hdr.sense_key;
1798 				if (cmdstatp->remainder_valid)
1799 					undone = (int)cmdstatp->uremainder64;
1800 				else if (STp->block_size == 0 &&
1801 					 scode == VOLUME_OVERFLOW)
1802 					undone = transfer;
1803 				else
1804 					undone = 0;
1805 				if (STp->block_size != 0)
1806 					undone *= STp->block_size;
1807 				if (undone <= do_count) {
1808 					/* Only data from this write is not written */
1809 					count += undone;
1810 					b_point -= undone;
1811 					do_count -= undone;
1812 					if (STp->block_size)
1813 						blks = (transfer - undone) / STp->block_size;
1814 					STps->eof = ST_EOM_OK;
1815 					/* Continue in fixed block mode if all written
1816 					   in this request but still something left to write
1817 					   (retval left to zero)
1818 					*/
1819 					if (STp->block_size == 0 ||
1820 					    undone > 0 || count == 0)
1821 						retval = (-ENOSPC); /* EOM within current request */
1822 					DEBC_printk(STp, "EOM with %d "
1823 						    "bytes unwritten.\n",
1824 						    (int)count);
1825 				} else {
1826 					/* EOT within data buffered earlier (possible only
1827 					   in fixed block mode without direct i/o) */
1828 					if (!retry_eot && !cmdstatp->deferred &&
1829 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1830 						move_buffer_data(STp->buffer, transfer - undone);
1831 						retry_eot = 1;
1832 						if (STps->drv_block >= 0) {
1833 							STps->drv_block += (transfer - undone) /
1834 								STp->block_size;
1835 						}
1836 						STps->eof = ST_EOM_OK;
1837 						DEBC_printk(STp, "Retry "
1838 							    "write of %d "
1839 							    "bytes at EOM.\n",
1840 							    STp->buffer->buffer_bytes);
1841 						goto retry_write;
1842 					}
1843 					else {
1844 						/* Either error within data buffered by driver or
1845 						   failed retry */
1846 						count -= do_count;
1847 						blks = do_count = 0;
1848 						STps->eof = ST_EOM_ERROR;
1849 						STps->drv_block = (-1); /* Too cautious? */
1850 						retval = (-EIO);	/* EOM for old data */
1851 						DEBC_printk(STp, "EOM with "
1852 							    "lost data.\n");
1853 					}
1854 				}
1855 			} else {
1856 				count += do_count;
1857 				STps->drv_block = (-1);		/* Too cautious? */
1858 				retval = STbp->syscall_result;
1859 			}
1860 
1861 		}
1862 
1863 		if (STps->drv_block >= 0) {
1864 			if (STp->block_size == 0)
1865 				STps->drv_block += (do_count > 0);
1866 			else
1867 				STps->drv_block += blks;
1868 		}
1869 
1870 		STbp->buffer_bytes = 0;
1871 		STp->dirty = 0;
1872 
1873 		if (retval || retry_eot) {
1874 			if (count < total)
1875 				retval = total - count;
1876 			goto out;
1877 		}
1878 	}
1879 
1880 	if (STps->eof == ST_EOD_1)
1881 		STps->eof = ST_EOM_OK;
1882 	else if (STps->eof != ST_EOM_OK)
1883 		STps->eof = ST_NOEOF;
1884 	retval = total - count;
1885 
1886  out:
1887 	if (SRpnt != NULL)
1888 		st_release_request(SRpnt);
1889 	release_buffering(STp, 0);
1890 	mutex_unlock(&STp->lock);
1891 
1892 	return retval;
1893 }
1894 
1895 /* Read data from the tape. Returns zero in the normal case, one if the
1896    eof status has changed, and the negative error code in case of a
1897    fatal error. Otherwise updates the buffer and the eof state.
1898 
1899    Does release user buffer mapping if it is set.
1900 */
1901 static long read_tape(struct scsi_tape *STp, long count,
1902 		      struct st_request ** aSRpnt)
1903 {
1904 	int transfer, blks, bytes;
1905 	unsigned char cmd[MAX_COMMAND_SIZE];
1906 	struct st_request *SRpnt;
1907 	struct st_modedef *STm;
1908 	struct st_partstat *STps;
1909 	struct st_buffer *STbp;
1910 	int retval = 0;
1911 
1912 	if (count == 0)
1913 		return 0;
1914 
1915 	STm = &(STp->modes[STp->current_mode]);
1916 	STps = &(STp->ps[STp->partition]);
1917 	if (STps->eof == ST_FM_HIT)
1918 		return 1;
1919 	STbp = STp->buffer;
1920 
1921 	if (STp->block_size == 0)
1922 		blks = bytes = count;
1923 	else {
1924 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1925 			blks = (STp->buffer)->buffer_blocks;
1926 			bytes = blks * STp->block_size;
1927 		} else {
1928 			bytes = count;
1929 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1930 				bytes = (STp->buffer)->buffer_size;
1931 			blks = bytes / STp->block_size;
1932 			bytes = blks * STp->block_size;
1933 		}
1934 	}
1935 
1936 	memset(cmd, 0, MAX_COMMAND_SIZE);
1937 	cmd[0] = READ_6;
1938 	cmd[1] = (STp->block_size != 0);
1939 	if (!cmd[1] && STp->sili)
1940 		cmd[1] |= 2;
1941 	cmd[2] = blks >> 16;
1942 	cmd[3] = blks >> 8;
1943 	cmd[4] = blks;
1944 
1945 	SRpnt = *aSRpnt;
1946 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1947 			   STp->device->request_queue->rq_timeout,
1948 			   MAX_RETRIES, 1);
1949 	release_buffering(STp, 1);
1950 	*aSRpnt = SRpnt;
1951 	if (!SRpnt)
1952 		return STbp->syscall_result;
1953 
1954 	STbp->read_pointer = 0;
1955 	STps->at_sm = 0;
1956 
1957 	/* Something to check */
1958 	if (STbp->syscall_result) {
1959 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1960 
1961 		retval = 1;
1962 		DEBC_printk(STp,
1963 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1964 			    SRpnt->sense[0], SRpnt->sense[1],
1965 			    SRpnt->sense[2], SRpnt->sense[3],
1966 			    SRpnt->sense[4], SRpnt->sense[5],
1967 			    SRpnt->sense[6], SRpnt->sense[7]);
1968 		if (cmdstatp->have_sense) {
1969 
1970 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1971 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1972 
1973 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1974 				/* Compute the residual count */
1975 				if (cmdstatp->remainder_valid)
1976 					transfer = (int)cmdstatp->uremainder64;
1977 				else
1978 					transfer = 0;
1979 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1980 					if (STp->block_size == 0)
1981 						transfer = bytes;
1982 					/* Some drives set ILI with MEDIUM ERROR */
1983 					cmdstatp->flags &= ~SENSE_ILI;
1984 				}
1985 
1986 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1987 					if (STp->block_size == 0 &&
1988 					    transfer < 0) {
1989 						st_printk(KERN_NOTICE, STp,
1990 							  "Failed to read %d "
1991 							  "byte block with %d "
1992 							  "byte transfer.\n",
1993 							  bytes - transfer,
1994 							  bytes);
1995 						if (STps->drv_block >= 0)
1996 							STps->drv_block += 1;
1997 						STbp->buffer_bytes = 0;
1998 						return (-ENOMEM);
1999 					} else if (STp->block_size == 0) {
2000 						STbp->buffer_bytes = bytes - transfer;
2001 					} else {
2002 						st_release_request(SRpnt);
2003 						SRpnt = *aSRpnt = NULL;
2004 						if (transfer == blks) {	/* We did not get anything, error */
2005 							st_printk(KERN_NOTICE, STp,
2006 								  "Incorrect "
2007 								  "block size.\n");
2008 							if (STps->drv_block >= 0)
2009 								STps->drv_block += blks - transfer + 1;
2010 							st_int_ioctl(STp, MTBSR, 1);
2011 							return (-EIO);
2012 						}
2013 						/* We have some data, deliver it */
2014 						STbp->buffer_bytes = (blks - transfer) *
2015 						    STp->block_size;
2016 						DEBC_printk(STp, "ILI but "
2017 							    "enough data "
2018 							    "received %ld "
2019 							    "%d.\n", count,
2020 							    STbp->buffer_bytes);
2021 						if (STps->drv_block >= 0)
2022 							STps->drv_block += 1;
2023 						if (st_int_ioctl(STp, MTBSR, 1))
2024 							return (-EIO);
2025 					}
2026 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2027 					if (STps->eof != ST_FM_HIT)
2028 						STps->eof = ST_FM_HIT;
2029 					else
2030 						STps->eof = ST_EOD_2;
2031 					if (STp->block_size == 0)
2032 						STbp->buffer_bytes = 0;
2033 					else
2034 						STbp->buffer_bytes =
2035 						    bytes - transfer * STp->block_size;
2036 					DEBC_printk(STp, "EOF detected (%d "
2037 						    "bytes read).\n",
2038 						    STbp->buffer_bytes);
2039 				} else if (cmdstatp->flags & SENSE_EOM) {
2040 					if (STps->eof == ST_FM)
2041 						STps->eof = ST_EOD_1;
2042 					else
2043 						STps->eof = ST_EOM_OK;
2044 					if (STp->block_size == 0)
2045 						STbp->buffer_bytes = bytes - transfer;
2046 					else
2047 						STbp->buffer_bytes =
2048 						    bytes - transfer * STp->block_size;
2049 
2050 					DEBC_printk(STp, "EOM detected (%d "
2051 						    "bytes read).\n",
2052 						    STbp->buffer_bytes);
2053 				}
2054 			}
2055 			/* end of EOF, EOM, ILI test */
2056 			else {	/* nonzero sense key */
2057 				DEBC_printk(STp, "Tape error while reading.\n");
2058 				STps->drv_block = (-1);
2059 				if (STps->eof == ST_FM &&
2060 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2061 					DEBC_printk(STp, "Zero returned for "
2062 						    "first BLANK CHECK "
2063 						    "after EOF.\n");
2064 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2065 				} else	/* Some other extended sense code */
2066 					retval = (-EIO);
2067 			}
2068 
2069 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2070 				STbp->buffer_bytes = 0;
2071 		}
2072 		/* End of extended sense test */
2073 		else {		/* Non-extended sense */
2074 			retval = STbp->syscall_result;
2075 		}
2076 
2077 	}
2078 	/* End of error handling */
2079 	else {			/* Read successful */
2080 		STbp->buffer_bytes = bytes;
2081 		if (STp->sili) /* In fixed block mode residual is always zero here */
2082 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2083 	}
2084 
2085 	if (STps->drv_block >= 0) {
2086 		if (STp->block_size == 0)
2087 			STps->drv_block++;
2088 		else
2089 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2090 	}
2091 	return retval;
2092 }
2093 
2094 
2095 /* Read command */
2096 static ssize_t
2097 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2098 {
2099 	ssize_t total;
2100 	ssize_t retval = 0;
2101 	ssize_t i, transfer;
2102 	int special, do_dio = 0;
2103 	struct st_request *SRpnt = NULL;
2104 	struct scsi_tape *STp = filp->private_data;
2105 	struct st_modedef *STm;
2106 	struct st_partstat *STps;
2107 	struct st_buffer *STbp = STp->buffer;
2108 
2109 	if (mutex_lock_interruptible(&STp->lock))
2110 		return -ERESTARTSYS;
2111 
2112 	retval = rw_checks(STp, filp, count);
2113 	if (retval || count == 0)
2114 		goto out;
2115 
2116 	STm = &(STp->modes[STp->current_mode]);
2117 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2118 		if (!STm->do_read_ahead) {
2119 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2120 			goto out;
2121 		}
2122 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2123 	}
2124 
2125 	STps = &(STp->ps[STp->partition]);
2126 	if (STps->rw == ST_WRITING) {
2127 		retval = flush_buffer(STp, 0);
2128 		if (retval)
2129 			goto out;
2130 		STps->rw = ST_READING;
2131 	}
2132 	DEB(
2133 	if (debugging && STps->eof != ST_NOEOF)
2134 		st_printk(ST_DEB_MSG, STp,
2135 			  "EOF/EOM flag up (%d). Bytes %d\n",
2136 			  STps->eof, STbp->buffer_bytes);
2137 	) /* end DEB */
2138 
2139 	retval = setup_buffering(STp, buf, count, 1);
2140 	if (retval)
2141 		goto out;
2142 	do_dio = STbp->do_dio;
2143 
2144 	if (STbp->buffer_bytes == 0 &&
2145 	    STps->eof >= ST_EOD_1) {
2146 		if (STps->eof < ST_EOD) {
2147 			STps->eof += 1;
2148 			retval = 0;
2149 			goto out;
2150 		}
2151 		retval = (-EIO);	/* EOM or Blank Check */
2152 		goto out;
2153 	}
2154 
2155 	if (do_dio) {
2156 		/* Check the buffer writability before any tape movement. Don't alter
2157 		   buffer data. */
2158 		if (copy_from_user(&i, buf, 1) != 0 ||
2159 		    copy_to_user(buf, &i, 1) != 0 ||
2160 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2161 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2162 			retval = (-EFAULT);
2163 			goto out;
2164 		}
2165 	}
2166 
2167 	STps->rw = ST_READING;
2168 
2169 
2170 	/* Loop until enough data in buffer or a special condition found */
2171 	for (total = 0, special = 0; total < count && !special;) {
2172 
2173 		/* Get new data if the buffer is empty */
2174 		if (STbp->buffer_bytes == 0) {
2175 			special = read_tape(STp, count - total, &SRpnt);
2176 			if (special < 0) {	/* No need to continue read */
2177 				retval = special;
2178 				goto out;
2179 			}
2180 		}
2181 
2182 		/* Move the data from driver buffer to user buffer */
2183 		if (STbp->buffer_bytes > 0) {
2184 			DEB(
2185 			if (debugging && STps->eof != ST_NOEOF)
2186 				st_printk(ST_DEB_MSG, STp,
2187 					  "EOF up (%d). Left %d, needed %d.\n",
2188 					  STps->eof, STbp->buffer_bytes,
2189 					  (int)(count - total));
2190 			) /* end DEB */
2191 			transfer = STbp->buffer_bytes < count - total ?
2192 			    STbp->buffer_bytes : count - total;
2193 			if (!do_dio) {
2194 				i = from_buffer(STbp, buf, transfer);
2195 				if (i) {
2196 					retval = i;
2197 					goto out;
2198 				}
2199 			}
2200 			buf += transfer;
2201 			total += transfer;
2202 		}
2203 
2204 		if (STp->block_size == 0)
2205 			break;	/* Read only one variable length block */
2206 
2207 	}			/* for (total = 0, special = 0;
2208                                    total < count && !special; ) */
2209 
2210 	/* Change the eof state if no data from tape or buffer */
2211 	if (total == 0) {
2212 		if (STps->eof == ST_FM_HIT) {
2213 			STps->eof = ST_FM;
2214 			STps->drv_block = 0;
2215 			if (STps->drv_file >= 0)
2216 				STps->drv_file++;
2217 		} else if (STps->eof == ST_EOD_1) {
2218 			STps->eof = ST_EOD_2;
2219 			STps->drv_block = 0;
2220 			if (STps->drv_file >= 0)
2221 				STps->drv_file++;
2222 		} else if (STps->eof == ST_EOD_2)
2223 			STps->eof = ST_EOD;
2224 	} else if (STps->eof == ST_FM)
2225 		STps->eof = ST_NOEOF;
2226 	retval = total;
2227 
2228  out:
2229 	if (SRpnt != NULL) {
2230 		st_release_request(SRpnt);
2231 		SRpnt = NULL;
2232 	}
2233 	if (do_dio) {
2234 		release_buffering(STp, 1);
2235 		STbp->buffer_bytes = 0;
2236 	}
2237 	mutex_unlock(&STp->lock);
2238 
2239 	return retval;
2240 }
2241 
2242 
2243 
2244 DEB(
2245 /* Set the driver options */
2246 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2247 {
2248 	if (debugging) {
2249 		st_printk(KERN_INFO, STp,
2250 			  "Mode %d options: buffer writes: %d, "
2251 			  "async writes: %d, read ahead: %d\n",
2252 			  STp->current_mode, STm->do_buffer_writes,
2253 			  STm->do_async_writes, STm->do_read_ahead);
2254 		st_printk(KERN_INFO, STp,
2255 			  "    can bsr: %d, two FMs: %d, "
2256 			  "fast mteom: %d, auto lock: %d,\n",
2257 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2258 			  STp->do_auto_lock);
2259 		st_printk(KERN_INFO, STp,
2260 			  "    defs for wr: %d, no block limits: %d, "
2261 			  "partitions: %d, s2 log: %d\n",
2262 			  STm->defaults_for_writes, STp->omit_blklims,
2263 			  STp->can_partitions, STp->scsi2_logical);
2264 		st_printk(KERN_INFO, STp,
2265 			  "    sysv: %d nowait: %d sili: %d "
2266 			  "nowait_filemark: %d\n",
2267 			  STm->sysv, STp->immediate, STp->sili,
2268 			  STp->immediate_filemark);
2269 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2270 	}
2271 }
2272 	)
2273 
2274 
2275 static int st_set_options(struct scsi_tape *STp, long options)
2276 {
2277 	int value;
2278 	long code;
2279 	struct st_modedef *STm;
2280 	struct cdev *cd0, *cd1;
2281 	struct device *d0, *d1;
2282 
2283 	STm = &(STp->modes[STp->current_mode]);
2284 	if (!STm->defined) {
2285 		cd0 = STm->cdevs[0];
2286 		cd1 = STm->cdevs[1];
2287 		d0  = STm->devs[0];
2288 		d1  = STm->devs[1];
2289 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2290 		STm->cdevs[0] = cd0;
2291 		STm->cdevs[1] = cd1;
2292 		STm->devs[0]  = d0;
2293 		STm->devs[1]  = d1;
2294 		modes_defined = 1;
2295 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2296 			    STp->current_mode);
2297 	}
2298 
2299 	code = options & MT_ST_OPTIONS;
2300 	if (code == MT_ST_BOOLEANS) {
2301 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2302 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2303 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2304 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2305 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2306 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2307 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2308 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2309 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2310 		if ((STp->device)->scsi_level >= SCSI_2)
2311 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2312 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2313 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2314 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2315 		STm->sysv = (options & MT_ST_SYSV) != 0;
2316 		STp->sili = (options & MT_ST_SILI) != 0;
2317 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2318 		     st_log_options(STp, STm); )
2319 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2320 		value = (code == MT_ST_SETBOOLEANS);
2321 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2322 			STm->do_buffer_writes = value;
2323 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2324 			STm->do_async_writes = value;
2325 		if ((options & MT_ST_DEF_WRITES) != 0)
2326 			STm->defaults_for_writes = value;
2327 		if ((options & MT_ST_READ_AHEAD) != 0)
2328 			STm->do_read_ahead = value;
2329 		if ((options & MT_ST_TWO_FM) != 0)
2330 			STp->two_fm = value;
2331 		if ((options & MT_ST_FAST_MTEOM) != 0)
2332 			STp->fast_mteom = value;
2333 		if ((options & MT_ST_AUTO_LOCK) != 0)
2334 			STp->do_auto_lock = value;
2335 		if ((options & MT_ST_CAN_BSR) != 0)
2336 			STp->can_bsr = value;
2337 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2338 			STp->omit_blklims = value;
2339 		if ((STp->device)->scsi_level >= SCSI_2 &&
2340 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2341 			STp->can_partitions = value;
2342 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2343 			STp->scsi2_logical = value;
2344 		if ((options & MT_ST_NOWAIT) != 0)
2345 			STp->immediate = value;
2346 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2347 			STp->immediate_filemark = value;
2348 		if ((options & MT_ST_SYSV) != 0)
2349 			STm->sysv = value;
2350 		if ((options & MT_ST_SILI) != 0)
2351 			STp->sili = value;
2352 		DEB(
2353 		if ((options & MT_ST_DEBUGGING) != 0)
2354 			debugging = value;
2355 			st_log_options(STp, STm); )
2356 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2357 		/* Retained for compatibility */
2358 	} else if (code == MT_ST_DEF_BLKSIZE) {
2359 		value = (options & ~MT_ST_OPTIONS);
2360 		if (value == ~MT_ST_OPTIONS) {
2361 			STm->default_blksize = (-1);
2362 			DEBC_printk(STp, "Default block size disabled.\n");
2363 		} else {
2364 			STm->default_blksize = value;
2365 			DEBC_printk(STp,"Default block size set to "
2366 				    "%d bytes.\n", STm->default_blksize);
2367 			if (STp->ready == ST_READY) {
2368 				STp->blksize_changed = 0;
2369 				set_mode_densblk(STp, STm);
2370 			}
2371 		}
2372 	} else if (code == MT_ST_TIMEOUTS) {
2373 		value = (options & ~MT_ST_OPTIONS);
2374 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2375 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2376 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2377 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2378 		} else {
2379 			blk_queue_rq_timeout(STp->device->request_queue,
2380 					     value * HZ);
2381 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2382 				    value);
2383 		}
2384 	} else if (code == MT_ST_SET_CLN) {
2385 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2386 		if (value != 0 &&
2387 			(value < EXTENDED_SENSE_START ||
2388 				value >= SCSI_SENSE_BUFFERSIZE))
2389 			return (-EINVAL);
2390 		STp->cln_mode = value;
2391 		STp->cln_sense_mask = (options >> 8) & 0xff;
2392 		STp->cln_sense_value = (options >> 16) & 0xff;
2393 		st_printk(KERN_INFO, STp,
2394 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2395 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2396 	} else if (code == MT_ST_DEF_OPTIONS) {
2397 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2398 		value = (options & MT_ST_CLEAR_DEFAULT);
2399 		if (code == MT_ST_DEF_DENSITY) {
2400 			if (value == MT_ST_CLEAR_DEFAULT) {
2401 				STm->default_density = (-1);
2402 				DEBC_printk(STp,
2403 					    "Density default disabled.\n");
2404 			} else {
2405 				STm->default_density = value & 0xff;
2406 				DEBC_printk(STp, "Density default set to %x\n",
2407 					    STm->default_density);
2408 				if (STp->ready == ST_READY) {
2409 					STp->density_changed = 0;
2410 					set_mode_densblk(STp, STm);
2411 				}
2412 			}
2413 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2414 			if (value == MT_ST_CLEAR_DEFAULT) {
2415 				STp->default_drvbuffer = 0xff;
2416 				DEBC_printk(STp,
2417 					    "Drive buffer default disabled.\n");
2418 			} else {
2419 				STp->default_drvbuffer = value & 7;
2420 				DEBC_printk(STp,
2421 					    "Drive buffer default set to %x\n",
2422 					    STp->default_drvbuffer);
2423 				if (STp->ready == ST_READY)
2424 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2425 			}
2426 		} else if (code == MT_ST_DEF_COMPRESSION) {
2427 			if (value == MT_ST_CLEAR_DEFAULT) {
2428 				STm->default_compression = ST_DONT_TOUCH;
2429 				DEBC_printk(STp,
2430 					    "Compression default disabled.\n");
2431 			} else {
2432 				if ((value & 0xff00) != 0) {
2433 					STp->c_algo = (value & 0xff00) >> 8;
2434 					DEBC_printk(STp, "Compression "
2435 						    "algorithm set to 0x%x.\n",
2436 						    STp->c_algo);
2437 				}
2438 				if ((value & 0xff) != 0xff) {
2439 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2440 					DEBC_printk(STp, "Compression default "
2441 						    "set to %x\n",
2442 						    (value & 1));
2443 					if (STp->ready == ST_READY) {
2444 						STp->compression_changed = 0;
2445 						st_compression(STp, (STm->default_compression == ST_YES));
2446 					}
2447 				}
2448 			}
2449 		}
2450 	} else
2451 		return (-EIO);
2452 
2453 	return 0;
2454 }
2455 
2456 #define MODE_HEADER_LENGTH  4
2457 
2458 /* Mode header and page byte offsets */
2459 #define MH_OFF_DATA_LENGTH     0
2460 #define MH_OFF_MEDIUM_TYPE     1
2461 #define MH_OFF_DEV_SPECIFIC    2
2462 #define MH_OFF_BDESCS_LENGTH   3
2463 #define MP_OFF_PAGE_NBR        0
2464 #define MP_OFF_PAGE_LENGTH     1
2465 
2466 /* Mode header and page bit masks */
2467 #define MH_BIT_WP              0x80
2468 #define MP_MSK_PAGE_NBR        0x3f
2469 
2470 /* Don't return block descriptors */
2471 #define MODE_SENSE_OMIT_BDESCS 0x08
2472 
2473 #define MODE_SELECT_PAGE_FORMAT 0x10
2474 
2475 /* Read a mode page into the tape buffer. The block descriptors are included
2476    if incl_block_descs is true. The page control is ored to the page number
2477    parameter, if necessary. */
2478 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2479 {
2480 	unsigned char cmd[MAX_COMMAND_SIZE];
2481 	struct st_request *SRpnt;
2482 
2483 	memset(cmd, 0, MAX_COMMAND_SIZE);
2484 	cmd[0] = MODE_SENSE;
2485 	if (omit_block_descs)
2486 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2487 	cmd[2] = page;
2488 	cmd[4] = 255;
2489 
2490 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2491 			   STp->device->request_queue->rq_timeout, 0, 1);
2492 	if (SRpnt == NULL)
2493 		return (STp->buffer)->syscall_result;
2494 
2495 	st_release_request(SRpnt);
2496 
2497 	return STp->buffer->syscall_result;
2498 }
2499 
2500 
2501 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2502    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2503 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2504 {
2505 	int pgo;
2506 	unsigned char cmd[MAX_COMMAND_SIZE];
2507 	struct st_request *SRpnt;
2508 	int timeout;
2509 
2510 	memset(cmd, 0, MAX_COMMAND_SIZE);
2511 	cmd[0] = MODE_SELECT;
2512 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2513 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2514 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2515 
2516 	/* Clear reserved fields */
2517 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2518 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2519 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2520 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2521 
2522 	timeout = slow ?
2523 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2524 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2525 			   timeout, 0, 1);
2526 	if (SRpnt == NULL)
2527 		return (STp->buffer)->syscall_result;
2528 
2529 	st_release_request(SRpnt);
2530 
2531 	return STp->buffer->syscall_result;
2532 }
2533 
2534 
2535 #define COMPRESSION_PAGE        0x0f
2536 #define COMPRESSION_PAGE_LENGTH 16
2537 
2538 #define CP_OFF_DCE_DCC          2
2539 #define CP_OFF_C_ALGO           7
2540 
2541 #define DCE_MASK  0x80
2542 #define DCC_MASK  0x40
2543 #define RED_MASK  0x60
2544 
2545 
2546 /* Control the compression with mode page 15. Algorithm not changed if zero.
2547 
2548    The block descriptors are read and written because Sony SDT-7000 does not
2549    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2550    Including block descriptors should not cause any harm to other drives. */
2551 
2552 static int st_compression(struct scsi_tape * STp, int state)
2553 {
2554 	int retval;
2555 	int mpoffs;  /* Offset to mode page start */
2556 	unsigned char *b_data = (STp->buffer)->b_data;
2557 
2558 	if (STp->ready != ST_READY)
2559 		return (-EIO);
2560 
2561 	/* Read the current page contents */
2562 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2563 	if (retval) {
2564 		DEBC_printk(STp, "Compression mode page not supported.\n");
2565 		return (-EIO);
2566 	}
2567 
2568 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2569 	DEBC_printk(STp, "Compression state is %d.\n",
2570 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2571 
2572 	/* Check if compression can be changed */
2573 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2574 		DEBC_printk(STp, "Compression not supported.\n");
2575 		return (-EIO);
2576 	}
2577 
2578 	/* Do the change */
2579 	if (state) {
2580 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2581 		if (STp->c_algo != 0)
2582 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2583 	}
2584 	else {
2585 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2586 		if (STp->c_algo != 0)
2587 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2588 	}
2589 
2590 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2591 	if (retval) {
2592 		DEBC_printk(STp, "Compression change failed.\n");
2593 		return (-EIO);
2594 	}
2595 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2596 
2597 	STp->compression_changed = 1;
2598 	return 0;
2599 }
2600 
2601 
2602 /* Process the load and unload commands (does unload if the load code is zero) */
2603 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2604 {
2605 	int retval = (-EIO), timeout;
2606 	unsigned char cmd[MAX_COMMAND_SIZE];
2607 	struct st_partstat *STps;
2608 	struct st_request *SRpnt;
2609 
2610 	if (STp->ready != ST_READY && !load_code) {
2611 		if (STp->ready == ST_NO_TAPE)
2612 			return (-ENOMEDIUM);
2613 		else
2614 			return (-EIO);
2615 	}
2616 
2617 	memset(cmd, 0, MAX_COMMAND_SIZE);
2618 	cmd[0] = START_STOP;
2619 	if (load_code)
2620 		cmd[4] |= 1;
2621 	/*
2622 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2623 	 */
2624 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2625 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2626 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2627 			    (cmd[4]) ? "" : "un",
2628 			    load_code - MT_ST_HPLOADER_OFFSET);
2629 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2630 	}
2631 	if (STp->immediate) {
2632 		cmd[1] = 1;	/* Don't wait for completion */
2633 		timeout = STp->device->request_queue->rq_timeout;
2634 	}
2635 	else
2636 		timeout = STp->long_timeout;
2637 
2638 	DEBC(
2639 		if (!load_code)
2640 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2641 		else
2642 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2643 		);
2644 
2645 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2646 			   timeout, MAX_RETRIES, 1);
2647 	if (!SRpnt)
2648 		return (STp->buffer)->syscall_result;
2649 
2650 	retval = (STp->buffer)->syscall_result;
2651 	st_release_request(SRpnt);
2652 
2653 	if (!retval) {	/* SCSI command successful */
2654 
2655 		if (!load_code) {
2656 			STp->rew_at_close = 0;
2657 			STp->ready = ST_NO_TAPE;
2658 		}
2659 		else {
2660 			STp->rew_at_close = STp->autorew_dev;
2661 			retval = check_tape(STp, filp);
2662 			if (retval > 0)
2663 				retval = 0;
2664 		}
2665 	}
2666 	else {
2667 		STps = &(STp->ps[STp->partition]);
2668 		STps->drv_file = STps->drv_block = (-1);
2669 	}
2670 
2671 	return retval;
2672 }
2673 
2674 #if DEBUG
2675 #define ST_DEB_FORWARD  0
2676 #define ST_DEB_BACKWARD 1
2677 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2678 {
2679 	s32 sc;
2680 
2681 	if (!debugging)
2682 		return;
2683 
2684 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2685 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2686 	if (direction)
2687 		sc = -sc;
2688 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2689 		  direction ? "backward" : "forward", sc, units);
2690 }
2691 #else
2692 #define ST_DEB_FORWARD  0
2693 #define ST_DEB_BACKWARD 1
2694 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2695 #endif
2696 
2697 
2698 /* Internal ioctl function */
2699 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2700 {
2701 	int timeout;
2702 	long ltmp;
2703 	int ioctl_result;
2704 	int chg_eof = 1;
2705 	unsigned char cmd[MAX_COMMAND_SIZE];
2706 	struct st_request *SRpnt;
2707 	struct st_partstat *STps;
2708 	int fileno, blkno, at_sm, undone;
2709 	int datalen = 0, direction = DMA_NONE;
2710 
2711 	WARN_ON(STp->buffer->do_dio != 0);
2712 	if (STp->ready != ST_READY) {
2713 		if (STp->ready == ST_NO_TAPE)
2714 			return (-ENOMEDIUM);
2715 		else
2716 			return (-EIO);
2717 	}
2718 	timeout = STp->long_timeout;
2719 	STps = &(STp->ps[STp->partition]);
2720 	fileno = STps->drv_file;
2721 	blkno = STps->drv_block;
2722 	at_sm = STps->at_sm;
2723 
2724 	memset(cmd, 0, MAX_COMMAND_SIZE);
2725 	switch (cmd_in) {
2726 	case MTFSFM:
2727 		chg_eof = 0;	/* Changed from the FSF after this */
2728 	case MTFSF:
2729 		cmd[0] = SPACE;
2730 		cmd[1] = 0x01;	/* Space FileMarks */
2731 		cmd[2] = (arg >> 16);
2732 		cmd[3] = (arg >> 8);
2733 		cmd[4] = arg;
2734 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2735 		if (fileno >= 0)
2736 			fileno += arg;
2737 		blkno = 0;
2738 		at_sm &= (arg == 0);
2739 		break;
2740 	case MTBSFM:
2741 		chg_eof = 0;	/* Changed from the FSF after this */
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_ATOMIC);
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 = kzalloc(max_sg * sizeof(struct page *),
3893 				     GFP_ATOMIC);
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, "Found incompatible tape\n");
4270 		sdev_printk(KERN_INFO, SDp,
4271 			    "st: The suggested driver is %s.\n", stp);
4272 		return -ENODEV;
4273 	}
4274 
4275 	scsi_autopm_get_device(SDp);
4276 	i = queue_max_segments(SDp->request_queue);
4277 	if (st_max_sg_segs < i)
4278 		i = st_max_sg_segs;
4279 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
4280 	if (buffer == NULL) {
4281 		sdev_printk(KERN_ERR, SDp,
4282 			    "st: Can't allocate new tape buffer. "
4283 			    "Device not attached.\n");
4284 		goto out;
4285 	}
4286 
4287 	disk = alloc_disk(1);
4288 	if (!disk) {
4289 		sdev_printk(KERN_ERR, SDp,
4290 			    "st: out of memory. Device not attached.\n");
4291 		goto out_buffer_free;
4292 	}
4293 
4294 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
4295 	if (tpnt == NULL) {
4296 		sdev_printk(KERN_ERR, SDp,
4297 			    "st: Can't allocate device descriptor.\n");
4298 		goto out_put_disk;
4299 	}
4300 	kref_init(&tpnt->kref);
4301 	tpnt->disk = disk;
4302 	disk->private_data = &tpnt->driver;
4303 	disk->queue = SDp->request_queue;
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(disk->queue))
4307 		goto out_put_disk;
4308 	tpnt->driver = &st_template;
4309 
4310 	tpnt->device = SDp;
4311 	if (SDp->scsi_level <= 2)
4312 		tpnt->tape_type = MT_ISSCSI1;
4313 	else
4314 		tpnt->tape_type = MT_ISSCSI2;
4315 
4316 	tpnt->buffer = buffer;
4317 	tpnt->buffer->last_SRpnt = NULL;
4318 
4319 	tpnt->inited = 0;
4320 	tpnt->dirty = 0;
4321 	tpnt->in_use = 0;
4322 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4323 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4324 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4325 	tpnt->density = 0;
4326 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4327 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4328 	tpnt->can_partitions = 0;
4329 	tpnt->two_fm = ST_TWO_FM;
4330 	tpnt->fast_mteom = ST_FAST_MTEOM;
4331 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4332 	tpnt->sili = ST_SILI;
4333 	tpnt->immediate = ST_NOWAIT;
4334 	tpnt->immediate_filemark = 0;
4335 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4336 	tpnt->partition = 0;
4337 	tpnt->new_partition = 0;
4338 	tpnt->nbr_partitions = 0;
4339 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4340 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4341 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4342 
4343 	for (i = 0; i < ST_NBR_MODES; i++) {
4344 		STm = &(tpnt->modes[i]);
4345 		STm->defined = 0;
4346 		STm->sysv = ST_SYSV;
4347 		STm->defaults_for_writes = 0;
4348 		STm->do_async_writes = ST_ASYNC_WRITES;
4349 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4350 		STm->do_read_ahead = ST_READ_AHEAD;
4351 		STm->default_compression = ST_DONT_TOUCH;
4352 		STm->default_blksize = (-1);	/* No forced size */
4353 		STm->default_density = (-1);	/* No forced density */
4354 		STm->tape = tpnt;
4355 	}
4356 
4357 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4358 		STps = &(tpnt->ps[i]);
4359 		STps->rw = ST_IDLE;
4360 		STps->eof = ST_NOEOF;
4361 		STps->at_sm = 0;
4362 		STps->last_block_valid = 0;
4363 		STps->drv_block = (-1);
4364 		STps->drv_file = (-1);
4365 	}
4366 
4367 	tpnt->current_mode = 0;
4368 	tpnt->modes[0].defined = 1;
4369 
4370 	tpnt->density_changed = tpnt->compression_changed =
4371 	    tpnt->blksize_changed = 0;
4372 	mutex_init(&tpnt->lock);
4373 
4374 	idr_preload(GFP_KERNEL);
4375 	spin_lock(&st_index_lock);
4376 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4377 	spin_unlock(&st_index_lock);
4378 	idr_preload_end();
4379 	if (error < 0) {
4380 		pr_warn("st: idr allocation failed: %d\n", error);
4381 		goto out_put_queue;
4382 	}
4383 	tpnt->index = error;
4384 	sprintf(disk->disk_name, "st%d", tpnt->index);
4385 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4386 	if (tpnt->stats == NULL) {
4387 		sdev_printk(KERN_ERR, SDp,
4388 			    "st: Can't allocate statistics.\n");
4389 		goto out_idr_remove;
4390 	}
4391 
4392 	dev_set_drvdata(dev, tpnt);
4393 
4394 
4395 	error = create_cdevs(tpnt);
4396 	if (error)
4397 		goto out_remove_devs;
4398 	scsi_autopm_put_device(SDp);
4399 
4400 	sdev_printk(KERN_NOTICE, SDp,
4401 		    "Attached scsi tape %s\n", tape_name(tpnt));
4402 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4403 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4404 		    queue_dma_alignment(SDp->request_queue) + 1);
4405 
4406 	return 0;
4407 
4408 out_remove_devs:
4409 	remove_cdevs(tpnt);
4410 	kfree(tpnt->stats);
4411 out_idr_remove:
4412 	spin_lock(&st_index_lock);
4413 	idr_remove(&st_index_idr, tpnt->index);
4414 	spin_unlock(&st_index_lock);
4415 out_put_queue:
4416 	blk_put_queue(disk->queue);
4417 out_put_disk:
4418 	put_disk(disk);
4419 	kfree(tpnt);
4420 out_buffer_free:
4421 	kfree(buffer);
4422 out:
4423 	scsi_autopm_put_device(SDp);
4424 	return -ENODEV;
4425 };
4426 
4427 
4428 static int st_remove(struct device *dev)
4429 {
4430 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4431 	int index = tpnt->index;
4432 
4433 	scsi_autopm_get_device(to_scsi_device(dev));
4434 	remove_cdevs(tpnt);
4435 
4436 	mutex_lock(&st_ref_mutex);
4437 	kref_put(&tpnt->kref, scsi_tape_release);
4438 	mutex_unlock(&st_ref_mutex);
4439 	spin_lock(&st_index_lock);
4440 	idr_remove(&st_index_idr, index);
4441 	spin_unlock(&st_index_lock);
4442 	return 0;
4443 }
4444 
4445 /**
4446  *      scsi_tape_release - Called to free the Scsi_Tape structure
4447  *      @kref: pointer to embedded kref
4448  *
4449  *      st_ref_mutex must be held entering this routine.  Because it is
4450  *      called on last put, you should always use the scsi_tape_get()
4451  *      scsi_tape_put() helpers which manipulate the semaphore directly
4452  *      and never do a direct kref_put().
4453  **/
4454 static void scsi_tape_release(struct kref *kref)
4455 {
4456 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4457 	struct gendisk *disk = tpnt->disk;
4458 
4459 	tpnt->device = NULL;
4460 
4461 	if (tpnt->buffer) {
4462 		normalize_buffer(tpnt->buffer);
4463 		kfree(tpnt->buffer->reserved_pages);
4464 		kfree(tpnt->buffer);
4465 	}
4466 
4467 	disk->private_data = NULL;
4468 	put_disk(disk);
4469 	kfree(tpnt->stats);
4470 	kfree(tpnt);
4471 	return;
4472 }
4473 
4474 static struct class st_sysfs_class = {
4475 	.name = "scsi_tape",
4476 	.dev_groups = st_dev_groups,
4477 };
4478 
4479 static int __init init_st(void)
4480 {
4481 	int err;
4482 
4483 	validate_options();
4484 
4485 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4486 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4487 
4488 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4489 	if (debugging) {
4490 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4491 			debugging);
4492 	}
4493 
4494 	err = class_register(&st_sysfs_class);
4495 	if (err) {
4496 		pr_err("Unable register sysfs class for SCSI tapes\n");
4497 		return err;
4498 	}
4499 
4500 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4501 				     ST_MAX_TAPE_ENTRIES, "st");
4502 	if (err) {
4503 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4504 		       SCSI_TAPE_MAJOR);
4505 		goto err_class;
4506 	}
4507 
4508 	err = scsi_register_driver(&st_template.gendrv);
4509 	if (err)
4510 		goto err_chrdev;
4511 
4512 	return 0;
4513 
4514 err_chrdev:
4515 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4516 				 ST_MAX_TAPE_ENTRIES);
4517 err_class:
4518 	class_unregister(&st_sysfs_class);
4519 	return err;
4520 }
4521 
4522 static void __exit exit_st(void)
4523 {
4524 	scsi_unregister_driver(&st_template.gendrv);
4525 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4526 				 ST_MAX_TAPE_ENTRIES);
4527 	class_unregister(&st_sysfs_class);
4528 	idr_destroy(&st_index_idr);
4529 	printk(KERN_INFO "st: Unloaded.\n");
4530 }
4531 
4532 module_init(init_st);
4533 module_exit(exit_st);
4534 
4535 
4536 /* The sysfs driver interface. Read-only at the moment */
4537 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4538 {
4539 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4540 }
4541 static DRIVER_ATTR_RO(try_direct_io);
4542 
4543 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4544 {
4545 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4546 }
4547 static DRIVER_ATTR_RO(fixed_buffer_size);
4548 
4549 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4550 {
4551 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4552 }
4553 static DRIVER_ATTR_RO(max_sg_segs);
4554 
4555 static ssize_t version_show(struct device_driver *ddd, char *buf)
4556 {
4557 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4558 }
4559 static DRIVER_ATTR_RO(version);
4560 
4561 #if DEBUG
4562 static ssize_t debug_flag_store(struct device_driver *ddp,
4563 	const char *buf, size_t count)
4564 {
4565 /* We only care what the first byte of the data is the rest is unused.
4566  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4567  * other values have -EINVAL returned if they are passed in.
4568  */
4569 	if (count > 0) {
4570 		if (buf[0] == '0') {
4571 			debugging = NO_DEBUG;
4572 			return count;
4573 		} else if (buf[0] == '1') {
4574 			debugging = 1;
4575 			return count;
4576 		}
4577 	}
4578 	return -EINVAL;
4579 }
4580 
4581 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4582 {
4583 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4584 }
4585 static DRIVER_ATTR_RW(debug_flag);
4586 #endif
4587 
4588 static struct attribute *st_drv_attrs[] = {
4589 	&driver_attr_try_direct_io.attr,
4590 	&driver_attr_fixed_buffer_size.attr,
4591 	&driver_attr_max_sg_segs.attr,
4592 	&driver_attr_version.attr,
4593 #if DEBUG
4594 	&driver_attr_debug_flag.attr,
4595 #endif
4596 	NULL,
4597 };
4598 ATTRIBUTE_GROUPS(st_drv);
4599 
4600 /* The sysfs simple class interface */
4601 static ssize_t
4602 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4603 {
4604 	struct st_modedef *STm = dev_get_drvdata(dev);
4605 	ssize_t l = 0;
4606 
4607 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4608 	return l;
4609 }
4610 static DEVICE_ATTR_RO(defined);
4611 
4612 static ssize_t
4613 default_blksize_show(struct device *dev, struct device_attribute *attr,
4614 		     char *buf)
4615 {
4616 	struct st_modedef *STm = dev_get_drvdata(dev);
4617 	ssize_t l = 0;
4618 
4619 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4620 	return l;
4621 }
4622 static DEVICE_ATTR_RO(default_blksize);
4623 
4624 static ssize_t
4625 default_density_show(struct device *dev, struct device_attribute *attr,
4626 		     char *buf)
4627 {
4628 	struct st_modedef *STm = dev_get_drvdata(dev);
4629 	ssize_t l = 0;
4630 	char *fmt;
4631 
4632 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4633 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4634 	return l;
4635 }
4636 static DEVICE_ATTR_RO(default_density);
4637 
4638 static ssize_t
4639 default_compression_show(struct device *dev, struct device_attribute *attr,
4640 			 char *buf)
4641 {
4642 	struct st_modedef *STm = dev_get_drvdata(dev);
4643 	ssize_t l = 0;
4644 
4645 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4646 	return l;
4647 }
4648 static DEVICE_ATTR_RO(default_compression);
4649 
4650 static ssize_t
4651 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4652 {
4653 	struct st_modedef *STm = dev_get_drvdata(dev);
4654 	struct scsi_tape *STp = STm->tape;
4655 	int options;
4656 	ssize_t l = 0;
4657 
4658 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4659 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4660 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4661 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4662 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4663 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4664 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4665 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4666 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4667 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4668 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4669 	options |= STm->sysv ? MT_ST_SYSV : 0;
4670 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4671 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4672 	options |= STp->sili ? MT_ST_SILI : 0;
4673 
4674 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4675 	return l;
4676 }
4677 static DEVICE_ATTR_RO(options);
4678 
4679 /* Support for tape stats */
4680 
4681 /**
4682  * read_cnt_show - return read count - count of reads made from tape drive
4683  * @dev: struct device
4684  * @attr: attribute structure
4685  * @buf: buffer to return formatted data in
4686  */
4687 static ssize_t read_cnt_show(struct device *dev,
4688 	struct device_attribute *attr, char *buf)
4689 {
4690 	struct st_modedef *STm = dev_get_drvdata(dev);
4691 
4692 	return sprintf(buf, "%lld",
4693 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4694 }
4695 static DEVICE_ATTR_RO(read_cnt);
4696 
4697 /**
4698  * read_byte_cnt_show - return read byte count - tape drives
4699  * may use blocks less than 512 bytes this gives the raw byte count of
4700  * of data read from the tape drive.
4701  * @dev: struct device
4702  * @attr: attribute structure
4703  * @buf: buffer to return formatted data in
4704  */
4705 static ssize_t read_byte_cnt_show(struct device *dev,
4706 	struct device_attribute *attr, char *buf)
4707 {
4708 	struct st_modedef *STm = dev_get_drvdata(dev);
4709 
4710 	return sprintf(buf, "%lld",
4711 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4712 }
4713 static DEVICE_ATTR_RO(read_byte_cnt);
4714 
4715 /**
4716  * read_us_show - return read us - overall time spent waiting on reads in ns.
4717  * @dev: struct device
4718  * @attr: attribute structure
4719  * @buf: buffer to return formatted data in
4720  */
4721 static ssize_t read_ns_show(struct device *dev,
4722 	struct device_attribute *attr, char *buf)
4723 {
4724 	struct st_modedef *STm = dev_get_drvdata(dev);
4725 
4726 	return sprintf(buf, "%lld",
4727 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4728 }
4729 static DEVICE_ATTR_RO(read_ns);
4730 
4731 /**
4732  * write_cnt_show - write count - number of user calls
4733  * to write(2) that have written data to tape.
4734  * @dev: struct device
4735  * @attr: attribute structure
4736  * @buf: buffer to return formatted data in
4737  */
4738 static ssize_t write_cnt_show(struct device *dev,
4739 	struct device_attribute *attr, char *buf)
4740 {
4741 	struct st_modedef *STm = dev_get_drvdata(dev);
4742 
4743 	return sprintf(buf, "%lld",
4744 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4745 }
4746 static DEVICE_ATTR_RO(write_cnt);
4747 
4748 /**
4749  * write_byte_cnt_show - write byte count - raw count of
4750  * bytes written to tape.
4751  * @dev: struct device
4752  * @attr: attribute structure
4753  * @buf: buffer to return formatted data in
4754  */
4755 static ssize_t write_byte_cnt_show(struct device *dev,
4756 	struct device_attribute *attr, char *buf)
4757 {
4758 	struct st_modedef *STm = dev_get_drvdata(dev);
4759 
4760 	return sprintf(buf, "%lld",
4761 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4762 }
4763 static DEVICE_ATTR_RO(write_byte_cnt);
4764 
4765 /**
4766  * write_ns_show - write ns - number of nanoseconds waiting on write
4767  * requests to complete.
4768  * @dev: struct device
4769  * @attr: attribute structure
4770  * @buf: buffer to return formatted data in
4771  */
4772 static ssize_t write_ns_show(struct device *dev,
4773 	struct device_attribute *attr, char *buf)
4774 {
4775 	struct st_modedef *STm = dev_get_drvdata(dev);
4776 
4777 	return sprintf(buf, "%lld",
4778 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4779 }
4780 static DEVICE_ATTR_RO(write_ns);
4781 
4782 /**
4783  * in_flight_show - number of I/Os currently in flight -
4784  * in most cases this will be either 0 or 1. It may be higher if someone
4785  * has also issued other SCSI commands such as via an ioctl.
4786  * @dev: struct device
4787  * @attr: attribute structure
4788  * @buf: buffer to return formatted data in
4789  */
4790 static ssize_t in_flight_show(struct device *dev,
4791 	struct device_attribute *attr, char *buf)
4792 {
4793 	struct st_modedef *STm = dev_get_drvdata(dev);
4794 
4795 	return sprintf(buf, "%lld",
4796 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4797 }
4798 static DEVICE_ATTR_RO(in_flight);
4799 
4800 /**
4801  * io_ns_show - io wait ns - this is the number of ns spent
4802  * waiting on all I/O to complete. This includes tape movement commands
4803  * such as rewinding, seeking to end of file or tape, it also includes
4804  * read and write. To determine the time spent on tape movement
4805  * subtract the read and write ns from this value.
4806  * @dev: struct device
4807  * @attr: attribute structure
4808  * @buf: buffer to return formatted data in
4809  */
4810 static ssize_t io_ns_show(struct device *dev,
4811 	struct device_attribute *attr, char *buf)
4812 {
4813 	struct st_modedef *STm = dev_get_drvdata(dev);
4814 
4815 	return sprintf(buf, "%lld",
4816 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4817 }
4818 static DEVICE_ATTR_RO(io_ns);
4819 
4820 /**
4821  * other_cnt_show - other io count - this is the number of
4822  * I/O requests other than read and write requests.
4823  * Typically these are tape movement requests but will include driver
4824  * tape movement. This includes only requests issued by the st driver.
4825  * @dev: struct device
4826  * @attr: attribute structure
4827  * @buf: buffer to return formatted data in
4828  */
4829 static ssize_t other_cnt_show(struct device *dev,
4830 	struct device_attribute *attr, char *buf)
4831 {
4832 	struct st_modedef *STm = dev_get_drvdata(dev);
4833 
4834 	return sprintf(buf, "%lld",
4835 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4836 }
4837 static DEVICE_ATTR_RO(other_cnt);
4838 
4839 /**
4840  * resid_cnt_show - A count of the number of times we get a residual
4841  * count - this should indicate someone issuing reads larger than the
4842  * block size on tape.
4843  * @dev: struct device
4844  * @attr: attribute structure
4845  * @buf: buffer to return formatted data in
4846  */
4847 static ssize_t resid_cnt_show(struct device *dev,
4848 	struct device_attribute *attr, char *buf)
4849 {
4850 	struct st_modedef *STm = dev_get_drvdata(dev);
4851 
4852 	return sprintf(buf, "%lld",
4853 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4854 }
4855 static DEVICE_ATTR_RO(resid_cnt);
4856 
4857 static struct attribute *st_dev_attrs[] = {
4858 	&dev_attr_defined.attr,
4859 	&dev_attr_default_blksize.attr,
4860 	&dev_attr_default_density.attr,
4861 	&dev_attr_default_compression.attr,
4862 	&dev_attr_options.attr,
4863 	NULL,
4864 };
4865 
4866 static struct attribute *st_stats_attrs[] = {
4867 	&dev_attr_read_cnt.attr,
4868 	&dev_attr_read_byte_cnt.attr,
4869 	&dev_attr_read_ns.attr,
4870 	&dev_attr_write_cnt.attr,
4871 	&dev_attr_write_byte_cnt.attr,
4872 	&dev_attr_write_ns.attr,
4873 	&dev_attr_in_flight.attr,
4874 	&dev_attr_io_ns.attr,
4875 	&dev_attr_other_cnt.attr,
4876 	&dev_attr_resid_cnt.attr,
4877 	NULL,
4878 };
4879 
4880 static struct attribute_group stats_group = {
4881 	.name = "stats",
4882 	.attrs = st_stats_attrs,
4883 };
4884 
4885 static struct attribute_group st_group = {
4886 	.attrs = st_dev_attrs,
4887 };
4888 
4889 static const struct attribute_group *st_dev_groups[] = {
4890 	&st_group,
4891 	&stats_group,
4892 	NULL,
4893 };
4894 
4895 /* The following functions may be useful for a larger audience. */
4896 static int sgl_map_user_pages(struct st_buffer *STbp,
4897 			      const unsigned int max_pages, unsigned long uaddr,
4898 			      size_t count, int rw)
4899 {
4900 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4901 	unsigned long start = uaddr >> PAGE_SHIFT;
4902 	const int nr_pages = end - start;
4903 	int res, i, j;
4904 	struct page **pages;
4905 	struct rq_map_data *mdata = &STbp->map_data;
4906 
4907 	/* User attempted Overflow! */
4908 	if ((uaddr + count) < uaddr)
4909 		return -EINVAL;
4910 
4911 	/* Too big */
4912         if (nr_pages > max_pages)
4913 		return -ENOMEM;
4914 
4915 	/* Hmm? */
4916 	if (count == 0)
4917 		return 0;
4918 
4919 	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
4920 		return -ENOMEM;
4921 
4922         /* Try to fault in all of the necessary pages */
4923         /* rw==READ means read from drive, write into memory area */
4924 	res = get_user_pages_unlocked(
4925 		uaddr,
4926 		nr_pages,
4927 		pages,
4928 		rw == READ ? FOLL_WRITE : 0); /* don't force */
4929 
4930 	/* Errors and no page mapped should return here */
4931 	if (res < nr_pages)
4932 		goto out_unmap;
4933 
4934         for (i=0; i < nr_pages; i++) {
4935                 /* FIXME: flush superflous for rw==READ,
4936                  * probably wrong function for rw==WRITE
4937                  */
4938 		flush_dcache_page(pages[i]);
4939         }
4940 
4941 	mdata->offset = uaddr & ~PAGE_MASK;
4942 	STbp->mapped_pages = pages;
4943 
4944 	return nr_pages;
4945  out_unmap:
4946 	if (res > 0) {
4947 		for (j=0; j < res; j++)
4948 			put_page(pages[j]);
4949 		res = 0;
4950 	}
4951 	kfree(pages);
4952 	return res;
4953 }
4954 
4955 
4956 /* And unmap them... */
4957 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4958 				const unsigned int nr_pages, int dirtied)
4959 {
4960 	int i;
4961 
4962 	for (i=0; i < nr_pages; i++) {
4963 		struct page *page = STbp->mapped_pages[i];
4964 
4965 		if (dirtied)
4966 			SetPageDirty(page);
4967 		/* FIXME: cache flush missing for rw==READ
4968 		 * FIXME: call the correct reference counting function
4969 		 */
4970 		put_page(page);
4971 	}
4972 	kfree(STbp->mapped_pages);
4973 	STbp->mapped_pages = NULL;
4974 
4975 	return 0;
4976 }
4977