xref: /openbmc/linux/drivers/scsi/st.c (revision 4cff79e9)
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 (scsi_req(req)->result) {
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 (scsi_req(req)->result) {
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, blk_status_t status)
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 = rq->result;
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 	req->rq_flags |= RQF_QUIET;
553 
554 	mdata->null_mapped = 1;
555 
556 	if (bufflen) {
557 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
558 				      GFP_KERNEL);
559 		if (err) {
560 			blk_put_request(req);
561 			return DRIVER_ERROR << 24;
562 		}
563 	}
564 
565 	atomic64_inc(&STp->stats->in_flight);
566 	if (cmd[0] == WRITE_6) {
567 		atomic_set(&STp->stats->last_write_size, bufflen);
568 		STp->stats->write_time = ktime_get();
569 	} else if (cmd[0] == READ_6) {
570 		atomic_set(&STp->stats->last_read_size, bufflen);
571 		STp->stats->read_time = ktime_get();
572 	} else {
573 		STp->stats->other_time = ktime_get();
574 	}
575 
576 	SRpnt->bio = req->bio;
577 	rq->cmd_len = COMMAND_SIZE(cmd[0]);
578 	memset(rq->cmd, 0, BLK_MAX_CDB);
579 	memcpy(rq->cmd, cmd, rq->cmd_len);
580 	req->timeout = timeout;
581 	rq->retries = retries;
582 	req->end_io_data = SRpnt;
583 
584 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
585 	return 0;
586 }
587 
588 /* Do the scsi command. Waits until command performed if do_wait is true.
589    Otherwise write_behind_check() is used to check that the command
590    has finished. */
591 static struct st_request *
592 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
593 	   int bytes, int direction, int timeout, int retries, int do_wait)
594 {
595 	struct completion *waiting;
596 	struct rq_map_data *mdata = &STp->buffer->map_data;
597 	int ret;
598 
599 	/* if async, make sure there's no command outstanding */
600 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
601 		st_printk(KERN_ERR, STp,
602 			  "Async command already active.\n");
603 		if (signal_pending(current))
604 			(STp->buffer)->syscall_result = (-EINTR);
605 		else
606 			(STp->buffer)->syscall_result = (-EBUSY);
607 		return NULL;
608 	}
609 
610 	if (!SRpnt) {
611 		SRpnt = st_allocate_request(STp);
612 		if (!SRpnt)
613 			return NULL;
614 	}
615 
616 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
617 	   which IO is outstanding. It's nulled out when the IO completes. */
618 	if (!do_wait)
619 		(STp->buffer)->last_SRpnt = SRpnt;
620 
621 	waiting = &STp->wait;
622 	init_completion(waiting);
623 	SRpnt->waiting = waiting;
624 
625 	if (STp->buffer->do_dio) {
626 		mdata->page_order = 0;
627 		mdata->nr_entries = STp->buffer->sg_segs;
628 		mdata->pages = STp->buffer->mapped_pages;
629 	} else {
630 		mdata->page_order = STp->buffer->reserved_page_order;
631 		mdata->nr_entries =
632 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
633 		mdata->pages = STp->buffer->reserved_pages;
634 		mdata->offset = 0;
635 	}
636 
637 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
638 	STp->buffer->cmdstat.have_sense = 0;
639 	STp->buffer->syscall_result = 0;
640 
641 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
642 			      retries);
643 	if (ret) {
644 		/* could not allocate the buffer or request was too large */
645 		(STp->buffer)->syscall_result = (-EBUSY);
646 		(STp->buffer)->last_SRpnt = NULL;
647 	} else if (do_wait) {
648 		wait_for_completion(waiting);
649 		SRpnt->waiting = NULL;
650 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
651 	}
652 
653 	return SRpnt;
654 }
655 
656 
657 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
658    write has been correct but EOM early warning reached, -EIO if write ended in
659    error or zero if write successful. Asynchronous writes are used only in
660    variable block mode. */
661 static int write_behind_check(struct scsi_tape * STp)
662 {
663 	int retval = 0;
664 	struct st_buffer *STbuffer;
665 	struct st_partstat *STps;
666 	struct st_cmdstatus *cmdstatp;
667 	struct st_request *SRpnt;
668 
669 	STbuffer = STp->buffer;
670 	if (!STbuffer->writing)
671 		return 0;
672 
673 	DEB(
674 	if (STp->write_pending)
675 		STp->nbr_waits++;
676 	else
677 		STp->nbr_finished++;
678 	) /* end DEB */
679 
680 	wait_for_completion(&(STp->wait));
681 	SRpnt = STbuffer->last_SRpnt;
682 	STbuffer->last_SRpnt = NULL;
683 	SRpnt->waiting = NULL;
684 
685 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
686 	st_release_request(SRpnt);
687 
688 	STbuffer->buffer_bytes -= STbuffer->writing;
689 	STps = &(STp->ps[STp->partition]);
690 	if (STps->drv_block >= 0) {
691 		if (STp->block_size == 0)
692 			STps->drv_block++;
693 		else
694 			STps->drv_block += STbuffer->writing / STp->block_size;
695 	}
696 
697 	cmdstatp = &STbuffer->cmdstat;
698 	if (STbuffer->syscall_result) {
699 		retval = -EIO;
700 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
701 		    (cmdstatp->flags & SENSE_EOM) &&
702 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
703 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
704 			/* EOM at write-behind, has all data been written? */
705 			if (!cmdstatp->remainder_valid ||
706 			    cmdstatp->uremainder64 == 0)
707 				retval = -ENOSPC;
708 		}
709 		if (retval == -EIO)
710 			STps->drv_block = -1;
711 	}
712 	STbuffer->writing = 0;
713 
714 	DEB(if (debugging && retval)
715 		    st_printk(ST_DEB_MSG, STp,
716 				"Async write error %x, return value %d.\n",
717 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
718 
719 	return retval;
720 }
721 
722 
723 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
724    it messes up the block number). */
725 static int cross_eof(struct scsi_tape * STp, int forward)
726 {
727 	struct st_request *SRpnt;
728 	unsigned char cmd[MAX_COMMAND_SIZE];
729 
730 	cmd[0] = SPACE;
731 	cmd[1] = 0x01;		/* Space FileMarks */
732 	if (forward) {
733 		cmd[2] = cmd[3] = 0;
734 		cmd[4] = 1;
735 	} else
736 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
737 	cmd[5] = 0;
738 
739 	DEBC_printk(STp, "Stepping over filemark %s.\n",
740 		    forward ? "forward" : "backward");
741 
742 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
743 			   STp->device->request_queue->rq_timeout,
744 			   MAX_RETRIES, 1);
745 	if (!SRpnt)
746 		return (STp->buffer)->syscall_result;
747 
748 	st_release_request(SRpnt);
749 	SRpnt = NULL;
750 
751 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
752 		st_printk(KERN_ERR, STp,
753 			  "Stepping over filemark %s failed.\n",
754 			  forward ? "forward" : "backward");
755 
756 	return (STp->buffer)->syscall_result;
757 }
758 
759 
760 /* Flush the write buffer (never need to write if variable blocksize). */
761 static int st_flush_write_buffer(struct scsi_tape * STp)
762 {
763 	int transfer, blks;
764 	int result;
765 	unsigned char cmd[MAX_COMMAND_SIZE];
766 	struct st_request *SRpnt;
767 	struct st_partstat *STps;
768 
769 	result = write_behind_check(STp);
770 	if (result)
771 		return result;
772 
773 	result = 0;
774 	if (STp->dirty == 1) {
775 
776 		transfer = STp->buffer->buffer_bytes;
777 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
778 
779 		memset(cmd, 0, MAX_COMMAND_SIZE);
780 		cmd[0] = WRITE_6;
781 		cmd[1] = 1;
782 		blks = transfer / STp->block_size;
783 		cmd[2] = blks >> 16;
784 		cmd[3] = blks >> 8;
785 		cmd[4] = blks;
786 
787 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
788 				   STp->device->request_queue->rq_timeout,
789 				   MAX_WRITE_RETRIES, 1);
790 		if (!SRpnt)
791 			return (STp->buffer)->syscall_result;
792 
793 		STps = &(STp->ps[STp->partition]);
794 		if ((STp->buffer)->syscall_result != 0) {
795 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
796 
797 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
798 			    (cmdstatp->flags & SENSE_EOM) &&
799 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
800 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
801 			    (!cmdstatp->remainder_valid ||
802 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
803 				STp->dirty = 0;
804 				(STp->buffer)->buffer_bytes = 0;
805 				if (STps->drv_block >= 0)
806 					STps->drv_block += blks;
807 				result = (-ENOSPC);
808 			} else {
809 				st_printk(KERN_ERR, STp, "Error on flush.\n");
810 				STps->drv_block = (-1);
811 				result = (-EIO);
812 			}
813 		} else {
814 			if (STps->drv_block >= 0)
815 				STps->drv_block += blks;
816 			STp->dirty = 0;
817 			(STp->buffer)->buffer_bytes = 0;
818 		}
819 		st_release_request(SRpnt);
820 		SRpnt = NULL;
821 	}
822 	return result;
823 }
824 
825 
826 /* Flush the tape buffer. The tape will be positioned correctly unless
827    seek_next is true. */
828 static int flush_buffer(struct scsi_tape *STp, int seek_next)
829 {
830 	int backspace, result;
831 	struct st_buffer *STbuffer;
832 	struct st_partstat *STps;
833 
834 	STbuffer = STp->buffer;
835 
836 	/*
837 	 * If there was a bus reset, block further access
838 	 * to this device.
839 	 */
840 	if (STp->pos_unknown)
841 		return (-EIO);
842 
843 	if (STp->ready != ST_READY)
844 		return 0;
845 	STps = &(STp->ps[STp->partition]);
846 	if (STps->rw == ST_WRITING)	/* Writing */
847 		return st_flush_write_buffer(STp);
848 
849 	if (STp->block_size == 0)
850 		return 0;
851 
852 	backspace = ((STp->buffer)->buffer_bytes +
853 		     (STp->buffer)->read_pointer) / STp->block_size -
854 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
855 	    STp->block_size;
856 	(STp->buffer)->buffer_bytes = 0;
857 	(STp->buffer)->read_pointer = 0;
858 	result = 0;
859 	if (!seek_next) {
860 		if (STps->eof == ST_FM_HIT) {
861 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
862 			if (!result)
863 				STps->eof = ST_NOEOF;
864 			else {
865 				if (STps->drv_file >= 0)
866 					STps->drv_file++;
867 				STps->drv_block = 0;
868 			}
869 		}
870 		if (!result && backspace > 0)
871 			result = st_int_ioctl(STp, MTBSR, backspace);
872 	} else if (STps->eof == ST_FM_HIT) {
873 		if (STps->drv_file >= 0)
874 			STps->drv_file++;
875 		STps->drv_block = 0;
876 		STps->eof = ST_NOEOF;
877 	}
878 	return result;
879 
880 }
881 
882 /* Set the mode parameters */
883 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
884 {
885 	int set_it = 0;
886 	unsigned long arg;
887 
888 	if (!STp->density_changed &&
889 	    STm->default_density >= 0 &&
890 	    STm->default_density != STp->density) {
891 		arg = STm->default_density;
892 		set_it = 1;
893 	} else
894 		arg = STp->density;
895 	arg <<= MT_ST_DENSITY_SHIFT;
896 	if (!STp->blksize_changed &&
897 	    STm->default_blksize >= 0 &&
898 	    STm->default_blksize != STp->block_size) {
899 		arg |= STm->default_blksize;
900 		set_it = 1;
901 	} else
902 		arg |= STp->block_size;
903 	if (set_it &&
904 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
905 		st_printk(KERN_WARNING, STp,
906 			  "Can't set default block size to %d bytes "
907 			  "and density %x.\n",
908 			  STm->default_blksize, STm->default_density);
909 		if (modes_defined)
910 			return (-EINVAL);
911 	}
912 	return 0;
913 }
914 
915 
916 /* Lock or unlock the drive door. Don't use when st_request allocated. */
917 static int do_door_lock(struct scsi_tape * STp, int do_lock)
918 {
919 	int retval;
920 
921 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
922 
923 	retval = scsi_set_medium_removal(STp->device,
924 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
925 	if (!retval)
926 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
927 	else
928 		STp->door_locked = ST_LOCK_FAILS;
929 	return retval;
930 }
931 
932 
933 /* Set the internal state after reset */
934 static void reset_state(struct scsi_tape *STp)
935 {
936 	int i;
937 	struct st_partstat *STps;
938 
939 	STp->pos_unknown = 0;
940 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
941 		STps = &(STp->ps[i]);
942 		STps->rw = ST_IDLE;
943 		STps->eof = ST_NOEOF;
944 		STps->at_sm = 0;
945 		STps->last_block_valid = 0;
946 		STps->drv_block = -1;
947 		STps->drv_file = -1;
948 	}
949 	if (STp->can_partitions) {
950 		STp->partition = find_partition(STp);
951 		if (STp->partition < 0)
952 			STp->partition = 0;
953 		STp->new_partition = STp->partition;
954 	}
955 }
956 
957 /* Test if the drive is ready. Returns either one of the codes below or a negative system
958    error code. */
959 #define CHKRES_READY       0
960 #define CHKRES_NEW_SESSION 1
961 #define CHKRES_NOT_READY   2
962 #define CHKRES_NO_TAPE     3
963 
964 #define MAX_ATTENTIONS    10
965 
966 static int test_ready(struct scsi_tape *STp, int do_wait)
967 {
968 	int attentions, waits, max_wait, scode;
969 	int retval = CHKRES_READY, new_session = 0;
970 	unsigned char cmd[MAX_COMMAND_SIZE];
971 	struct st_request *SRpnt = NULL;
972 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
973 
974 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
975 
976 	for (attentions=waits=0; ; ) {
977 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
978 		cmd[0] = TEST_UNIT_READY;
979 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
980 				   STp->long_timeout, MAX_READY_RETRIES, 1);
981 
982 		if (!SRpnt) {
983 			retval = (STp->buffer)->syscall_result;
984 			break;
985 		}
986 
987 		if (cmdstatp->have_sense) {
988 
989 			scode = cmdstatp->sense_hdr.sense_key;
990 
991 			if (scode == UNIT_ATTENTION) { /* New media? */
992 				new_session = 1;
993 				if (attentions < MAX_ATTENTIONS) {
994 					attentions++;
995 					continue;
996 				}
997 				else {
998 					retval = (-EIO);
999 					break;
1000 				}
1001 			}
1002 
1003 			if (scode == NOT_READY) {
1004 				if (waits < max_wait) {
1005 					if (msleep_interruptible(1000)) {
1006 						retval = (-EINTR);
1007 						break;
1008 					}
1009 					waits++;
1010 					continue;
1011 				}
1012 				else {
1013 					if ((STp->device)->scsi_level >= SCSI_2 &&
1014 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1015 						retval = CHKRES_NO_TAPE;
1016 					else
1017 						retval = CHKRES_NOT_READY;
1018 					break;
1019 				}
1020 			}
1021 		}
1022 
1023 		retval = (STp->buffer)->syscall_result;
1024 		if (!retval)
1025 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1026 		break;
1027 	}
1028 
1029 	if (SRpnt != NULL)
1030 		st_release_request(SRpnt);
1031 	return retval;
1032 }
1033 
1034 
1035 /* See if the drive is ready and gather information about the tape. Return values:
1036    < 0   negative error code from errno.h
1037    0     drive ready
1038    1     drive not ready (possibly no tape)
1039 */
1040 static int check_tape(struct scsi_tape *STp, struct file *filp)
1041 {
1042 	int i, retval, new_session = 0, do_wait;
1043 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1044 	unsigned short st_flags = filp->f_flags;
1045 	struct st_request *SRpnt = NULL;
1046 	struct st_modedef *STm;
1047 	struct st_partstat *STps;
1048 	struct inode *inode = file_inode(filp);
1049 	int mode = TAPE_MODE(inode);
1050 
1051 	STp->ready = ST_READY;
1052 
1053 	if (mode != STp->current_mode) {
1054 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1055 			    STp->current_mode, mode);
1056 		new_session = 1;
1057 		STp->current_mode = mode;
1058 	}
1059 	STm = &(STp->modes[STp->current_mode]);
1060 
1061 	saved_cleaning = STp->cleaning_req;
1062 	STp->cleaning_req = 0;
1063 
1064 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1065 	retval = test_ready(STp, do_wait);
1066 
1067 	if (retval < 0)
1068 	    goto err_out;
1069 
1070 	if (retval == CHKRES_NEW_SESSION) {
1071 		STp->pos_unknown = 0;
1072 		STp->partition = STp->new_partition = 0;
1073 		if (STp->can_partitions)
1074 			STp->nbr_partitions = 1; /* This guess will be updated later
1075                                                     if necessary */
1076 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1077 			STps = &(STp->ps[i]);
1078 			STps->rw = ST_IDLE;
1079 			STps->eof = ST_NOEOF;
1080 			STps->at_sm = 0;
1081 			STps->last_block_valid = 0;
1082 			STps->drv_block = 0;
1083 			STps->drv_file = 0;
1084 		}
1085 		new_session = 1;
1086 	}
1087 	else {
1088 		STp->cleaning_req |= saved_cleaning;
1089 
1090 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1091 			if (retval == CHKRES_NO_TAPE)
1092 				STp->ready = ST_NO_TAPE;
1093 			else
1094 				STp->ready = ST_NOT_READY;
1095 
1096 			STp->density = 0;	/* Clear the erroneous "residue" */
1097 			STp->write_prot = 0;
1098 			STp->block_size = 0;
1099 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1100 			STp->partition = STp->new_partition = 0;
1101 			STp->door_locked = ST_UNLOCKED;
1102 			return CHKRES_NOT_READY;
1103 		}
1104 	}
1105 
1106 	if (STp->omit_blklims)
1107 		STp->min_block = STp->max_block = (-1);
1108 	else {
1109 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1110 		cmd[0] = READ_BLOCK_LIMITS;
1111 
1112 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1113 				   STp->device->request_queue->rq_timeout,
1114 				   MAX_READY_RETRIES, 1);
1115 		if (!SRpnt) {
1116 			retval = (STp->buffer)->syscall_result;
1117 			goto err_out;
1118 		}
1119 
1120 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1121 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1122 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1123 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1124 			    (STp->buffer)->b_data[5];
1125 			if ( DEB( debugging || ) !STp->inited)
1126 				st_printk(KERN_INFO, STp,
1127 					  "Block limits %d - %d bytes.\n",
1128 					  STp->min_block, STp->max_block);
1129 		} else {
1130 			STp->min_block = STp->max_block = (-1);
1131 			DEBC_printk(STp, "Can't read block limits.\n");
1132 		}
1133 	}
1134 
1135 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1136 	cmd[0] = MODE_SENSE;
1137 	cmd[4] = 12;
1138 
1139 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1140 			   STp->device->request_queue->rq_timeout,
1141 			   MAX_READY_RETRIES, 1);
1142 	if (!SRpnt) {
1143 		retval = (STp->buffer)->syscall_result;
1144 		goto err_out;
1145 	}
1146 
1147 	if ((STp->buffer)->syscall_result != 0) {
1148 		DEBC_printk(STp, "No Mode Sense.\n");
1149 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1150 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1151 		STp->drv_write_prot = 0;
1152 	} else {
1153 		DEBC_printk(STp,"Mode sense. Length %d, "
1154 			    "medium %x, WBS %x, BLL %d\n",
1155 			    (STp->buffer)->b_data[0],
1156 			    (STp->buffer)->b_data[1],
1157 			    (STp->buffer)->b_data[2],
1158 			    (STp->buffer)->b_data[3]);
1159 
1160 		if ((STp->buffer)->b_data[3] >= 8) {
1161 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1162 			STp->density = (STp->buffer)->b_data[4];
1163 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1164 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1165 			DEBC_printk(STp, "Density %x, tape length: %x, "
1166 				    "drv buffer: %d\n",
1167 				    STp->density,
1168 				    (STp->buffer)->b_data[5] * 65536 +
1169 				    (STp->buffer)->b_data[6] * 256 +
1170 				    (STp->buffer)->b_data[7],
1171 				    STp->drv_buffer);
1172 		}
1173 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1174 		if (!STp->drv_buffer && STp->immediate_filemark) {
1175 			st_printk(KERN_WARNING, STp,
1176 				  "non-buffered tape: disabling "
1177 				  "writing immediate filemarks\n");
1178 			STp->immediate_filemark = 0;
1179 		}
1180 	}
1181 	st_release_request(SRpnt);
1182 	SRpnt = NULL;
1183 	STp->inited = 1;
1184 
1185 	if (STp->block_size > 0)
1186 		(STp->buffer)->buffer_blocks =
1187 			(STp->buffer)->buffer_size / STp->block_size;
1188 	else
1189 		(STp->buffer)->buffer_blocks = 1;
1190 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1191 
1192 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1193 		    STp->block_size, (STp->buffer)->buffer_size,
1194 		    (STp->buffer)->buffer_blocks);
1195 
1196 	if (STp->drv_write_prot) {
1197 		STp->write_prot = 1;
1198 
1199 		DEBC_printk(STp, "Write protected\n");
1200 
1201 		if (do_wait &&
1202 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1203 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1204 			retval = (-EROFS);
1205 			goto err_out;
1206 		}
1207 	}
1208 
1209 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1210 		/* This code is reached when the device is opened for the first time
1211 		   after the driver has been initialized with tape in the drive and the
1212 		   partition support has been enabled. */
1213 		DEBC_printk(STp, "Updating partition number in status.\n");
1214 		if ((STp->partition = find_partition(STp)) < 0) {
1215 			retval = STp->partition;
1216 			goto err_out;
1217 		}
1218 		STp->new_partition = STp->partition;
1219 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1220 	}
1221 
1222 	if (new_session) {	/* Change the drive parameters for the new mode */
1223 		STp->density_changed = STp->blksize_changed = 0;
1224 		STp->compression_changed = 0;
1225 		if (!(STm->defaults_for_writes) &&
1226 		    (retval = set_mode_densblk(STp, STm)) < 0)
1227 		    goto err_out;
1228 
1229 		if (STp->default_drvbuffer != 0xff) {
1230 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1231 				st_printk(KERN_WARNING, STp,
1232 					  "Can't set default drive "
1233 					  "buffering to %d.\n",
1234 					  STp->default_drvbuffer);
1235 		}
1236 	}
1237 
1238 	return CHKRES_READY;
1239 
1240  err_out:
1241 	return retval;
1242 }
1243 
1244 
1245 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1246    module count. */
1247 static int st_open(struct inode *inode, struct file *filp)
1248 {
1249 	int i, retval = (-EIO);
1250 	int resumed = 0;
1251 	struct scsi_tape *STp;
1252 	struct st_partstat *STps;
1253 	int dev = TAPE_NR(inode);
1254 
1255 	/*
1256 	 * We really want to do nonseekable_open(inode, filp); here, but some
1257 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1258 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1259 	 */
1260 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1261 
1262 	if (!(STp = scsi_tape_get(dev))) {
1263 		return -ENXIO;
1264 	}
1265 
1266 	filp->private_data = STp;
1267 
1268 	spin_lock(&st_use_lock);
1269 	if (STp->in_use) {
1270 		spin_unlock(&st_use_lock);
1271 		scsi_tape_put(STp);
1272 		DEBC_printk(STp, "Device already in use.\n");
1273 		return (-EBUSY);
1274 	}
1275 
1276 	STp->in_use = 1;
1277 	spin_unlock(&st_use_lock);
1278 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1279 
1280 	if (scsi_autopm_get_device(STp->device) < 0) {
1281 		retval = -EIO;
1282 		goto err_out;
1283 	}
1284 	resumed = 1;
1285 	if (!scsi_block_when_processing_errors(STp->device)) {
1286 		retval = (-ENXIO);
1287 		goto err_out;
1288 	}
1289 
1290 	/* See that we have at least a one page buffer available */
1291 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
1292 		st_printk(KERN_WARNING, STp,
1293 			  "Can't allocate one page tape buffer.\n");
1294 		retval = (-EOVERFLOW);
1295 		goto err_out;
1296 	}
1297 
1298 	(STp->buffer)->cleared = 0;
1299 	(STp->buffer)->writing = 0;
1300 	(STp->buffer)->syscall_result = 0;
1301 
1302 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1303 
1304 	STp->dirty = 0;
1305 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1306 		STps = &(STp->ps[i]);
1307 		STps->rw = ST_IDLE;
1308 	}
1309 	STp->try_dio_now = STp->try_dio;
1310 	STp->recover_count = 0;
1311 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1312 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1313 
1314 	retval = check_tape(STp, filp);
1315 	if (retval < 0)
1316 		goto err_out;
1317 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1318 	    retval != CHKRES_READY) {
1319 		if (STp->ready == NO_TAPE)
1320 			retval = (-ENOMEDIUM);
1321 		else
1322 			retval = (-EIO);
1323 		goto err_out;
1324 	}
1325 	return 0;
1326 
1327  err_out:
1328 	normalize_buffer(STp->buffer);
1329 	spin_lock(&st_use_lock);
1330 	STp->in_use = 0;
1331 	spin_unlock(&st_use_lock);
1332 	if (resumed)
1333 		scsi_autopm_put_device(STp->device);
1334 	scsi_tape_put(STp);
1335 	return retval;
1336 
1337 }
1338 
1339 
1340 /* Flush the tape buffer before close */
1341 static int st_flush(struct file *filp, fl_owner_t id)
1342 {
1343 	int result = 0, result2;
1344 	unsigned char cmd[MAX_COMMAND_SIZE];
1345 	struct st_request *SRpnt;
1346 	struct scsi_tape *STp = filp->private_data;
1347 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1348 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1349 
1350 	if (file_count(filp) > 1)
1351 		return 0;
1352 
1353 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1354 		result = st_flush_write_buffer(STp);
1355 		if (result != 0 && result != (-ENOSPC))
1356 			goto out;
1357 	}
1358 
1359 	if (STp->can_partitions &&
1360 	    (result2 = switch_partition(STp)) < 0) {
1361 		DEBC_printk(STp, "switch_partition at close failed.\n");
1362 		if (result == 0)
1363 			result = result2;
1364 		goto out;
1365 	}
1366 
1367 	DEBC( if (STp->nbr_requests)
1368 		st_printk(KERN_DEBUG, STp,
1369 			  "Number of r/w requests %d, dio used in %d, "
1370 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1371 			  STp->nbr_pages));
1372 
1373 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1374 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1375 
1376 #if DEBUG
1377 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1378 			    STp->nbr_waits, STp->nbr_finished);
1379 #endif
1380 		memset(cmd, 0, MAX_COMMAND_SIZE);
1381 		cmd[0] = WRITE_FILEMARKS;
1382 		if (STp->immediate_filemark)
1383 			cmd[1] = 1;
1384 		cmd[4] = 1 + STp->two_fm;
1385 
1386 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1387 				   STp->device->request_queue->rq_timeout,
1388 				   MAX_WRITE_RETRIES, 1);
1389 		if (!SRpnt) {
1390 			result = (STp->buffer)->syscall_result;
1391 			goto out;
1392 		}
1393 
1394 		if (STp->buffer->syscall_result == 0 ||
1395 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1396 		     (cmdstatp->flags & SENSE_EOM) &&
1397 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1398 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1399 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1400 			/* Write successful at EOM */
1401 			st_release_request(SRpnt);
1402 			SRpnt = NULL;
1403 			if (STps->drv_file >= 0)
1404 				STps->drv_file++;
1405 			STps->drv_block = 0;
1406 			if (STp->two_fm)
1407 				cross_eof(STp, 0);
1408 			STps->eof = ST_FM;
1409 		}
1410 		else { /* Write error */
1411 			st_release_request(SRpnt);
1412 			SRpnt = NULL;
1413 			st_printk(KERN_ERR, STp,
1414 				  "Error on write filemark.\n");
1415 			if (result == 0)
1416 				result = (-EIO);
1417 		}
1418 
1419 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1420 	} else if (!STp->rew_at_close) {
1421 		STps = &(STp->ps[STp->partition]);
1422 		if (!STm->sysv || STps->rw != ST_READING) {
1423 			if (STp->can_bsr)
1424 				result = flush_buffer(STp, 0);
1425 			else if (STps->eof == ST_FM_HIT) {
1426 				result = cross_eof(STp, 0);
1427 				if (result) {
1428 					if (STps->drv_file >= 0)
1429 						STps->drv_file++;
1430 					STps->drv_block = 0;
1431 					STps->eof = ST_FM;
1432 				} else
1433 					STps->eof = ST_NOEOF;
1434 			}
1435 		} else if ((STps->eof == ST_NOEOF &&
1436 			    !(result = cross_eof(STp, 1))) ||
1437 			   STps->eof == ST_FM_HIT) {
1438 			if (STps->drv_file >= 0)
1439 				STps->drv_file++;
1440 			STps->drv_block = 0;
1441 			STps->eof = ST_FM;
1442 		}
1443 	}
1444 
1445       out:
1446 	if (STp->rew_at_close) {
1447 		result2 = st_int_ioctl(STp, MTREW, 1);
1448 		if (result == 0)
1449 			result = result2;
1450 	}
1451 	return result;
1452 }
1453 
1454 
1455 /* Close the device and release it. BKL is not needed: this is the only thread
1456    accessing this tape. */
1457 static int st_release(struct inode *inode, struct file *filp)
1458 {
1459 	int result = 0;
1460 	struct scsi_tape *STp = filp->private_data;
1461 
1462 	if (STp->door_locked == ST_LOCKED_AUTO)
1463 		do_door_lock(STp, 0);
1464 
1465 	normalize_buffer(STp->buffer);
1466 	spin_lock(&st_use_lock);
1467 	STp->in_use = 0;
1468 	spin_unlock(&st_use_lock);
1469 	scsi_autopm_put_device(STp->device);
1470 	scsi_tape_put(STp);
1471 
1472 	return result;
1473 }
1474 
1475 /* The checks common to both reading and writing */
1476 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1477 {
1478 	ssize_t retval = 0;
1479 
1480 	/*
1481 	 * If we are in the middle of error recovery, don't let anyone
1482 	 * else try and use this device.  Also, if error recovery fails, it
1483 	 * may try and take the device offline, in which case all further
1484 	 * access to the device is prohibited.
1485 	 */
1486 	if (!scsi_block_when_processing_errors(STp->device)) {
1487 		retval = (-ENXIO);
1488 		goto out;
1489 	}
1490 
1491 	if (STp->ready != ST_READY) {
1492 		if (STp->ready == ST_NO_TAPE)
1493 			retval = (-ENOMEDIUM);
1494 		else
1495 			retval = (-EIO);
1496 		goto out;
1497 	}
1498 
1499 	if (! STp->modes[STp->current_mode].defined) {
1500 		retval = (-ENXIO);
1501 		goto out;
1502 	}
1503 
1504 
1505 	/*
1506 	 * If there was a bus reset, block further access
1507 	 * to this device.
1508 	 */
1509 	if (STp->pos_unknown) {
1510 		retval = (-EIO);
1511 		goto out;
1512 	}
1513 
1514 	if (count == 0)
1515 		goto out;
1516 
1517 	DEB(
1518 	if (!STp->in_use) {
1519 		st_printk(ST_DEB_MSG, STp,
1520 			  "Incorrect device.\n");
1521 		retval = (-EIO);
1522 		goto out;
1523 	} ) /* end DEB */
1524 
1525 	if (STp->can_partitions &&
1526 	    (retval = switch_partition(STp)) < 0)
1527 		goto out;
1528 
1529 	if (STp->block_size == 0 && STp->max_block > 0 &&
1530 	    (count < STp->min_block || count > STp->max_block)) {
1531 		retval = (-EINVAL);
1532 		goto out;
1533 	}
1534 
1535 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1536 	    !do_door_lock(STp, 1))
1537 		STp->door_locked = ST_LOCKED_AUTO;
1538 
1539  out:
1540 	return retval;
1541 }
1542 
1543 
1544 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1545 			   size_t count, int is_read)
1546 {
1547 	int i, bufsize, retval = 0;
1548 	struct st_buffer *STbp = STp->buffer;
1549 
1550 	if (is_read)
1551 		i = STp->try_dio_now && try_rdio;
1552 	else
1553 		i = STp->try_dio_now && try_wdio;
1554 
1555 	if (i && ((unsigned long)buf & queue_dma_alignment(
1556 					STp->device->request_queue)) == 0) {
1557 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1558 				       count, (is_read ? READ : WRITE));
1559 		if (i > 0) {
1560 			STbp->do_dio = i;
1561 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1562 		}
1563 		else
1564 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1565 		STbp->sg_segs = STbp->do_dio;
1566 		DEB(
1567 		     if (STbp->do_dio) {
1568 			STp->nbr_dio++;
1569 			STp->nbr_pages += STbp->do_dio;
1570 		     }
1571 		)
1572 	} else
1573 		STbp->do_dio = 0;
1574 	DEB( STp->nbr_requests++; )
1575 
1576 	if (!STbp->do_dio) {
1577 		if (STp->block_size)
1578 			bufsize = STp->block_size > st_fixed_buffer_size ?
1579 				STp->block_size : st_fixed_buffer_size;
1580 		else {
1581 			bufsize = count;
1582 			/* Make sure that data from previous user is not leaked even if
1583 			   HBA does not return correct residual */
1584 			if (is_read && STp->sili && !STbp->cleared)
1585 				clear_buffer(STbp);
1586 		}
1587 
1588 		if (bufsize > STbp->buffer_size &&
1589 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1590 			st_printk(KERN_WARNING, STp,
1591 				  "Can't allocate %d byte tape buffer.\n",
1592 				  bufsize);
1593 			retval = (-EOVERFLOW);
1594 			goto out;
1595 		}
1596 		if (STp->block_size)
1597 			STbp->buffer_blocks = bufsize / STp->block_size;
1598 	}
1599 
1600  out:
1601 	return retval;
1602 }
1603 
1604 
1605 /* Can be called more than once after each setup_buffer() */
1606 static void release_buffering(struct scsi_tape *STp, int is_read)
1607 {
1608 	struct st_buffer *STbp;
1609 
1610 	STbp = STp->buffer;
1611 	if (STbp->do_dio) {
1612 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1613 		STbp->do_dio = 0;
1614 		STbp->sg_segs = 0;
1615 	}
1616 }
1617 
1618 
1619 /* Write command */
1620 static ssize_t
1621 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1622 {
1623 	ssize_t total;
1624 	ssize_t i, do_count, blks, transfer;
1625 	ssize_t retval;
1626 	int undone, retry_eot = 0, scode;
1627 	int async_write;
1628 	unsigned char cmd[MAX_COMMAND_SIZE];
1629 	const char __user *b_point;
1630 	struct st_request *SRpnt = NULL;
1631 	struct scsi_tape *STp = filp->private_data;
1632 	struct st_modedef *STm;
1633 	struct st_partstat *STps;
1634 	struct st_buffer *STbp;
1635 
1636 	if (mutex_lock_interruptible(&STp->lock))
1637 		return -ERESTARTSYS;
1638 
1639 	retval = rw_checks(STp, filp, count);
1640 	if (retval || count == 0)
1641 		goto out;
1642 
1643 	/* Write must be integral number of blocks */
1644 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1645 		st_printk(KERN_WARNING, STp,
1646 			  "Write not multiple of tape block size.\n");
1647 		retval = (-EINVAL);
1648 		goto out;
1649 	}
1650 
1651 	STm = &(STp->modes[STp->current_mode]);
1652 	STps = &(STp->ps[STp->partition]);
1653 
1654 	if (STp->write_prot) {
1655 		retval = (-EACCES);
1656 		goto out;
1657 	}
1658 
1659 
1660 	if (STps->rw == ST_READING) {
1661 		retval = flush_buffer(STp, 0);
1662 		if (retval)
1663 			goto out;
1664 		STps->rw = ST_WRITING;
1665 	} else if (STps->rw != ST_WRITING &&
1666 		   STps->drv_file == 0 && STps->drv_block == 0) {
1667 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1668 			goto out;
1669 		if (STm->default_compression != ST_DONT_TOUCH &&
1670 		    !(STp->compression_changed)) {
1671 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1672 				st_printk(KERN_WARNING, STp,
1673 					  "Can't set default compression.\n");
1674 				if (modes_defined) {
1675 					retval = (-EINVAL);
1676 					goto out;
1677 				}
1678 			}
1679 		}
1680 	}
1681 
1682 	STbp = STp->buffer;
1683 	i = write_behind_check(STp);
1684 	if (i) {
1685 		if (i == -ENOSPC)
1686 			STps->eof = ST_EOM_OK;
1687 		else
1688 			STps->eof = ST_EOM_ERROR;
1689 	}
1690 
1691 	if (STps->eof == ST_EOM_OK) {
1692 		STps->eof = ST_EOD_1;  /* allow next write */
1693 		retval = (-ENOSPC);
1694 		goto out;
1695 	}
1696 	else if (STps->eof == ST_EOM_ERROR) {
1697 		retval = (-EIO);
1698 		goto out;
1699 	}
1700 
1701 	/* Check the buffer readability in cases where copy_user might catch
1702 	   the problems after some tape movement. */
1703 	if (STp->block_size != 0 &&
1704 	    !STbp->do_dio &&
1705 	    (copy_from_user(&i, buf, 1) != 0 ||
1706 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1707 		retval = (-EFAULT);
1708 		goto out;
1709 	}
1710 
1711 	retval = setup_buffering(STp, buf, count, 0);
1712 	if (retval)
1713 		goto out;
1714 
1715 	total = count;
1716 
1717 	memset(cmd, 0, MAX_COMMAND_SIZE);
1718 	cmd[0] = WRITE_6;
1719 	cmd[1] = (STp->block_size != 0);
1720 
1721 	STps->rw = ST_WRITING;
1722 
1723 	b_point = buf;
1724 	while (count > 0 && !retry_eot) {
1725 
1726 		if (STbp->do_dio) {
1727 			do_count = count;
1728 		}
1729 		else {
1730 			if (STp->block_size == 0)
1731 				do_count = count;
1732 			else {
1733 				do_count = STbp->buffer_blocks * STp->block_size -
1734 					STbp->buffer_bytes;
1735 				if (do_count > count)
1736 					do_count = count;
1737 			}
1738 
1739 			i = append_to_buffer(b_point, STbp, do_count);
1740 			if (i) {
1741 				retval = i;
1742 				goto out;
1743 			}
1744 		}
1745 		count -= do_count;
1746 		b_point += do_count;
1747 
1748 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1749 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1750 
1751 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1752 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1753 		    STbp->buffer_bytes < STbp->buffer_size) {
1754 			STp->dirty = 1;
1755 			/* Don't write a buffer that is not full enough. */
1756 			if (!async_write && count == 0)
1757 				break;
1758 		}
1759 
1760 	retry_write:
1761 		if (STp->block_size == 0)
1762 			blks = transfer = do_count;
1763 		else {
1764 			if (!STbp->do_dio)
1765 				blks = STbp->buffer_bytes;
1766 			else
1767 				blks = do_count;
1768 			blks /= STp->block_size;
1769 			transfer = blks * STp->block_size;
1770 		}
1771 		cmd[2] = blks >> 16;
1772 		cmd[3] = blks >> 8;
1773 		cmd[4] = blks;
1774 
1775 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1776 				   STp->device->request_queue->rq_timeout,
1777 				   MAX_WRITE_RETRIES, !async_write);
1778 		if (!SRpnt) {
1779 			retval = STbp->syscall_result;
1780 			goto out;
1781 		}
1782 		if (async_write && !STbp->syscall_result) {
1783 			STbp->writing = transfer;
1784 			STp->dirty = !(STbp->writing ==
1785 				       STbp->buffer_bytes);
1786 			SRpnt = NULL;  /* Prevent releasing this request! */
1787 			DEB( STp->write_pending = 1; )
1788 			break;
1789 		}
1790 
1791 		if (STbp->syscall_result != 0) {
1792 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1793 
1794 			DEBC_printk(STp, "Error on write:\n");
1795 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1796 				scode = cmdstatp->sense_hdr.sense_key;
1797 				if (cmdstatp->remainder_valid)
1798 					undone = (int)cmdstatp->uremainder64;
1799 				else if (STp->block_size == 0 &&
1800 					 scode == VOLUME_OVERFLOW)
1801 					undone = transfer;
1802 				else
1803 					undone = 0;
1804 				if (STp->block_size != 0)
1805 					undone *= STp->block_size;
1806 				if (undone <= do_count) {
1807 					/* Only data from this write is not written */
1808 					count += undone;
1809 					b_point -= undone;
1810 					do_count -= undone;
1811 					if (STp->block_size)
1812 						blks = (transfer - undone) / STp->block_size;
1813 					STps->eof = ST_EOM_OK;
1814 					/* Continue in fixed block mode if all written
1815 					   in this request but still something left to write
1816 					   (retval left to zero)
1817 					*/
1818 					if (STp->block_size == 0 ||
1819 					    undone > 0 || count == 0)
1820 						retval = (-ENOSPC); /* EOM within current request */
1821 					DEBC_printk(STp, "EOM with %d "
1822 						    "bytes unwritten.\n",
1823 						    (int)count);
1824 				} else {
1825 					/* EOT within data buffered earlier (possible only
1826 					   in fixed block mode without direct i/o) */
1827 					if (!retry_eot && !cmdstatp->deferred &&
1828 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1829 						move_buffer_data(STp->buffer, transfer - undone);
1830 						retry_eot = 1;
1831 						if (STps->drv_block >= 0) {
1832 							STps->drv_block += (transfer - undone) /
1833 								STp->block_size;
1834 						}
1835 						STps->eof = ST_EOM_OK;
1836 						DEBC_printk(STp, "Retry "
1837 							    "write of %d "
1838 							    "bytes at EOM.\n",
1839 							    STp->buffer->buffer_bytes);
1840 						goto retry_write;
1841 					}
1842 					else {
1843 						/* Either error within data buffered by driver or
1844 						   failed retry */
1845 						count -= do_count;
1846 						blks = do_count = 0;
1847 						STps->eof = ST_EOM_ERROR;
1848 						STps->drv_block = (-1); /* Too cautious? */
1849 						retval = (-EIO);	/* EOM for old data */
1850 						DEBC_printk(STp, "EOM with "
1851 							    "lost data.\n");
1852 					}
1853 				}
1854 			} else {
1855 				count += do_count;
1856 				STps->drv_block = (-1);		/* Too cautious? */
1857 				retval = STbp->syscall_result;
1858 			}
1859 
1860 		}
1861 
1862 		if (STps->drv_block >= 0) {
1863 			if (STp->block_size == 0)
1864 				STps->drv_block += (do_count > 0);
1865 			else
1866 				STps->drv_block += blks;
1867 		}
1868 
1869 		STbp->buffer_bytes = 0;
1870 		STp->dirty = 0;
1871 
1872 		if (retval || retry_eot) {
1873 			if (count < total)
1874 				retval = total - count;
1875 			goto out;
1876 		}
1877 	}
1878 
1879 	if (STps->eof == ST_EOD_1)
1880 		STps->eof = ST_EOM_OK;
1881 	else if (STps->eof != ST_EOM_OK)
1882 		STps->eof = ST_NOEOF;
1883 	retval = total - count;
1884 
1885  out:
1886 	if (SRpnt != NULL)
1887 		st_release_request(SRpnt);
1888 	release_buffering(STp, 0);
1889 	mutex_unlock(&STp->lock);
1890 
1891 	return retval;
1892 }
1893 
1894 /* Read data from the tape. Returns zero in the normal case, one if the
1895    eof status has changed, and the negative error code in case of a
1896    fatal error. Otherwise updates the buffer and the eof state.
1897 
1898    Does release user buffer mapping if it is set.
1899 */
1900 static long read_tape(struct scsi_tape *STp, long count,
1901 		      struct st_request ** aSRpnt)
1902 {
1903 	int transfer, blks, bytes;
1904 	unsigned char cmd[MAX_COMMAND_SIZE];
1905 	struct st_request *SRpnt;
1906 	struct st_modedef *STm;
1907 	struct st_partstat *STps;
1908 	struct st_buffer *STbp;
1909 	int retval = 0;
1910 
1911 	if (count == 0)
1912 		return 0;
1913 
1914 	STm = &(STp->modes[STp->current_mode]);
1915 	STps = &(STp->ps[STp->partition]);
1916 	if (STps->eof == ST_FM_HIT)
1917 		return 1;
1918 	STbp = STp->buffer;
1919 
1920 	if (STp->block_size == 0)
1921 		blks = bytes = count;
1922 	else {
1923 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1924 			blks = (STp->buffer)->buffer_blocks;
1925 			bytes = blks * STp->block_size;
1926 		} else {
1927 			bytes = count;
1928 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1929 				bytes = (STp->buffer)->buffer_size;
1930 			blks = bytes / STp->block_size;
1931 			bytes = blks * STp->block_size;
1932 		}
1933 	}
1934 
1935 	memset(cmd, 0, MAX_COMMAND_SIZE);
1936 	cmd[0] = READ_6;
1937 	cmd[1] = (STp->block_size != 0);
1938 	if (!cmd[1] && STp->sili)
1939 		cmd[1] |= 2;
1940 	cmd[2] = blks >> 16;
1941 	cmd[3] = blks >> 8;
1942 	cmd[4] = blks;
1943 
1944 	SRpnt = *aSRpnt;
1945 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1946 			   STp->device->request_queue->rq_timeout,
1947 			   MAX_RETRIES, 1);
1948 	release_buffering(STp, 1);
1949 	*aSRpnt = SRpnt;
1950 	if (!SRpnt)
1951 		return STbp->syscall_result;
1952 
1953 	STbp->read_pointer = 0;
1954 	STps->at_sm = 0;
1955 
1956 	/* Something to check */
1957 	if (STbp->syscall_result) {
1958 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1959 
1960 		retval = 1;
1961 		DEBC_printk(STp,
1962 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1963 			    SRpnt->sense[0], SRpnt->sense[1],
1964 			    SRpnt->sense[2], SRpnt->sense[3],
1965 			    SRpnt->sense[4], SRpnt->sense[5],
1966 			    SRpnt->sense[6], SRpnt->sense[7]);
1967 		if (cmdstatp->have_sense) {
1968 
1969 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1970 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1971 
1972 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1973 				/* Compute the residual count */
1974 				if (cmdstatp->remainder_valid)
1975 					transfer = (int)cmdstatp->uremainder64;
1976 				else
1977 					transfer = 0;
1978 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1979 					if (STp->block_size == 0)
1980 						transfer = bytes;
1981 					/* Some drives set ILI with MEDIUM ERROR */
1982 					cmdstatp->flags &= ~SENSE_ILI;
1983 				}
1984 
1985 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1986 					if (STp->block_size == 0 &&
1987 					    transfer < 0) {
1988 						st_printk(KERN_NOTICE, STp,
1989 							  "Failed to read %d "
1990 							  "byte block with %d "
1991 							  "byte transfer.\n",
1992 							  bytes - transfer,
1993 							  bytes);
1994 						if (STps->drv_block >= 0)
1995 							STps->drv_block += 1;
1996 						STbp->buffer_bytes = 0;
1997 						return (-ENOMEM);
1998 					} else if (STp->block_size == 0) {
1999 						STbp->buffer_bytes = bytes - transfer;
2000 					} else {
2001 						st_release_request(SRpnt);
2002 						SRpnt = *aSRpnt = NULL;
2003 						if (transfer == blks) {	/* We did not get anything, error */
2004 							st_printk(KERN_NOTICE, STp,
2005 								  "Incorrect "
2006 								  "block size.\n");
2007 							if (STps->drv_block >= 0)
2008 								STps->drv_block += blks - transfer + 1;
2009 							st_int_ioctl(STp, MTBSR, 1);
2010 							return (-EIO);
2011 						}
2012 						/* We have some data, deliver it */
2013 						STbp->buffer_bytes = (blks - transfer) *
2014 						    STp->block_size;
2015 						DEBC_printk(STp, "ILI but "
2016 							    "enough data "
2017 							    "received %ld "
2018 							    "%d.\n", count,
2019 							    STbp->buffer_bytes);
2020 						if (STps->drv_block >= 0)
2021 							STps->drv_block += 1;
2022 						if (st_int_ioctl(STp, MTBSR, 1))
2023 							return (-EIO);
2024 					}
2025 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2026 					if (STps->eof != ST_FM_HIT)
2027 						STps->eof = ST_FM_HIT;
2028 					else
2029 						STps->eof = ST_EOD_2;
2030 					if (STp->block_size == 0)
2031 						STbp->buffer_bytes = 0;
2032 					else
2033 						STbp->buffer_bytes =
2034 						    bytes - transfer * STp->block_size;
2035 					DEBC_printk(STp, "EOF detected (%d "
2036 						    "bytes read).\n",
2037 						    STbp->buffer_bytes);
2038 				} else if (cmdstatp->flags & SENSE_EOM) {
2039 					if (STps->eof == ST_FM)
2040 						STps->eof = ST_EOD_1;
2041 					else
2042 						STps->eof = ST_EOM_OK;
2043 					if (STp->block_size == 0)
2044 						STbp->buffer_bytes = bytes - transfer;
2045 					else
2046 						STbp->buffer_bytes =
2047 						    bytes - transfer * STp->block_size;
2048 
2049 					DEBC_printk(STp, "EOM detected (%d "
2050 						    "bytes read).\n",
2051 						    STbp->buffer_bytes);
2052 				}
2053 			}
2054 			/* end of EOF, EOM, ILI test */
2055 			else {	/* nonzero sense key */
2056 				DEBC_printk(STp, "Tape error while reading.\n");
2057 				STps->drv_block = (-1);
2058 				if (STps->eof == ST_FM &&
2059 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2060 					DEBC_printk(STp, "Zero returned for "
2061 						    "first BLANK CHECK "
2062 						    "after EOF.\n");
2063 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2064 				} else	/* Some other extended sense code */
2065 					retval = (-EIO);
2066 			}
2067 
2068 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2069 				STbp->buffer_bytes = 0;
2070 		}
2071 		/* End of extended sense test */
2072 		else {		/* Non-extended sense */
2073 			retval = STbp->syscall_result;
2074 		}
2075 
2076 	}
2077 	/* End of error handling */
2078 	else {			/* Read successful */
2079 		STbp->buffer_bytes = bytes;
2080 		if (STp->sili) /* In fixed block mode residual is always zero here */
2081 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2082 	}
2083 
2084 	if (STps->drv_block >= 0) {
2085 		if (STp->block_size == 0)
2086 			STps->drv_block++;
2087 		else
2088 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2089 	}
2090 	return retval;
2091 }
2092 
2093 
2094 /* Read command */
2095 static ssize_t
2096 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2097 {
2098 	ssize_t total;
2099 	ssize_t retval = 0;
2100 	ssize_t i, transfer;
2101 	int special, do_dio = 0;
2102 	struct st_request *SRpnt = NULL;
2103 	struct scsi_tape *STp = filp->private_data;
2104 	struct st_modedef *STm;
2105 	struct st_partstat *STps;
2106 	struct st_buffer *STbp = STp->buffer;
2107 
2108 	if (mutex_lock_interruptible(&STp->lock))
2109 		return -ERESTARTSYS;
2110 
2111 	retval = rw_checks(STp, filp, count);
2112 	if (retval || count == 0)
2113 		goto out;
2114 
2115 	STm = &(STp->modes[STp->current_mode]);
2116 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2117 		if (!STm->do_read_ahead) {
2118 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2119 			goto out;
2120 		}
2121 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2122 	}
2123 
2124 	STps = &(STp->ps[STp->partition]);
2125 	if (STps->rw == ST_WRITING) {
2126 		retval = flush_buffer(STp, 0);
2127 		if (retval)
2128 			goto out;
2129 		STps->rw = ST_READING;
2130 	}
2131 	DEB(
2132 	if (debugging && STps->eof != ST_NOEOF)
2133 		st_printk(ST_DEB_MSG, STp,
2134 			  "EOF/EOM flag up (%d). Bytes %d\n",
2135 			  STps->eof, STbp->buffer_bytes);
2136 	) /* end DEB */
2137 
2138 	retval = setup_buffering(STp, buf, count, 1);
2139 	if (retval)
2140 		goto out;
2141 	do_dio = STbp->do_dio;
2142 
2143 	if (STbp->buffer_bytes == 0 &&
2144 	    STps->eof >= ST_EOD_1) {
2145 		if (STps->eof < ST_EOD) {
2146 			STps->eof += 1;
2147 			retval = 0;
2148 			goto out;
2149 		}
2150 		retval = (-EIO);	/* EOM or Blank Check */
2151 		goto out;
2152 	}
2153 
2154 	if (do_dio) {
2155 		/* Check the buffer writability before any tape movement. Don't alter
2156 		   buffer data. */
2157 		if (copy_from_user(&i, buf, 1) != 0 ||
2158 		    copy_to_user(buf, &i, 1) != 0 ||
2159 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2160 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2161 			retval = (-EFAULT);
2162 			goto out;
2163 		}
2164 	}
2165 
2166 	STps->rw = ST_READING;
2167 
2168 
2169 	/* Loop until enough data in buffer or a special condition found */
2170 	for (total = 0, special = 0; total < count && !special;) {
2171 
2172 		/* Get new data if the buffer is empty */
2173 		if (STbp->buffer_bytes == 0) {
2174 			special = read_tape(STp, count - total, &SRpnt);
2175 			if (special < 0) {	/* No need to continue read */
2176 				retval = special;
2177 				goto out;
2178 			}
2179 		}
2180 
2181 		/* Move the data from driver buffer to user buffer */
2182 		if (STbp->buffer_bytes > 0) {
2183 			DEB(
2184 			if (debugging && STps->eof != ST_NOEOF)
2185 				st_printk(ST_DEB_MSG, STp,
2186 					  "EOF up (%d). Left %d, needed %d.\n",
2187 					  STps->eof, STbp->buffer_bytes,
2188 					  (int)(count - total));
2189 			) /* end DEB */
2190 			transfer = STbp->buffer_bytes < count - total ?
2191 			    STbp->buffer_bytes : count - total;
2192 			if (!do_dio) {
2193 				i = from_buffer(STbp, buf, transfer);
2194 				if (i) {
2195 					retval = i;
2196 					goto out;
2197 				}
2198 			}
2199 			buf += transfer;
2200 			total += transfer;
2201 		}
2202 
2203 		if (STp->block_size == 0)
2204 			break;	/* Read only one variable length block */
2205 
2206 	}			/* for (total = 0, special = 0;
2207                                    total < count && !special; ) */
2208 
2209 	/* Change the eof state if no data from tape or buffer */
2210 	if (total == 0) {
2211 		if (STps->eof == ST_FM_HIT) {
2212 			STps->eof = ST_FM;
2213 			STps->drv_block = 0;
2214 			if (STps->drv_file >= 0)
2215 				STps->drv_file++;
2216 		} else if (STps->eof == ST_EOD_1) {
2217 			STps->eof = ST_EOD_2;
2218 			STps->drv_block = 0;
2219 			if (STps->drv_file >= 0)
2220 				STps->drv_file++;
2221 		} else if (STps->eof == ST_EOD_2)
2222 			STps->eof = ST_EOD;
2223 	} else if (STps->eof == ST_FM)
2224 		STps->eof = ST_NOEOF;
2225 	retval = total;
2226 
2227  out:
2228 	if (SRpnt != NULL) {
2229 		st_release_request(SRpnt);
2230 		SRpnt = NULL;
2231 	}
2232 	if (do_dio) {
2233 		release_buffering(STp, 1);
2234 		STbp->buffer_bytes = 0;
2235 	}
2236 	mutex_unlock(&STp->lock);
2237 
2238 	return retval;
2239 }
2240 
2241 
2242 
2243 DEB(
2244 /* Set the driver options */
2245 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2246 {
2247 	if (debugging) {
2248 		st_printk(KERN_INFO, STp,
2249 			  "Mode %d options: buffer writes: %d, "
2250 			  "async writes: %d, read ahead: %d\n",
2251 			  STp->current_mode, STm->do_buffer_writes,
2252 			  STm->do_async_writes, STm->do_read_ahead);
2253 		st_printk(KERN_INFO, STp,
2254 			  "    can bsr: %d, two FMs: %d, "
2255 			  "fast mteom: %d, auto lock: %d,\n",
2256 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2257 			  STp->do_auto_lock);
2258 		st_printk(KERN_INFO, STp,
2259 			  "    defs for wr: %d, no block limits: %d, "
2260 			  "partitions: %d, s2 log: %d\n",
2261 			  STm->defaults_for_writes, STp->omit_blklims,
2262 			  STp->can_partitions, STp->scsi2_logical);
2263 		st_printk(KERN_INFO, STp,
2264 			  "    sysv: %d nowait: %d sili: %d "
2265 			  "nowait_filemark: %d\n",
2266 			  STm->sysv, STp->immediate, STp->sili,
2267 			  STp->immediate_filemark);
2268 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2269 	}
2270 }
2271 	)
2272 
2273 
2274 static int st_set_options(struct scsi_tape *STp, long options)
2275 {
2276 	int value;
2277 	long code;
2278 	struct st_modedef *STm;
2279 	struct cdev *cd0, *cd1;
2280 	struct device *d0, *d1;
2281 
2282 	STm = &(STp->modes[STp->current_mode]);
2283 	if (!STm->defined) {
2284 		cd0 = STm->cdevs[0];
2285 		cd1 = STm->cdevs[1];
2286 		d0  = STm->devs[0];
2287 		d1  = STm->devs[1];
2288 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2289 		STm->cdevs[0] = cd0;
2290 		STm->cdevs[1] = cd1;
2291 		STm->devs[0]  = d0;
2292 		STm->devs[1]  = d1;
2293 		modes_defined = 1;
2294 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2295 			    STp->current_mode);
2296 	}
2297 
2298 	code = options & MT_ST_OPTIONS;
2299 	if (code == MT_ST_BOOLEANS) {
2300 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2301 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2302 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2303 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2304 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2305 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2306 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2307 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2308 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2309 		if ((STp->device)->scsi_level >= SCSI_2)
2310 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2311 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2312 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2313 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2314 		STm->sysv = (options & MT_ST_SYSV) != 0;
2315 		STp->sili = (options & MT_ST_SILI) != 0;
2316 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2317 		     st_log_options(STp, STm); )
2318 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2319 		value = (code == MT_ST_SETBOOLEANS);
2320 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2321 			STm->do_buffer_writes = value;
2322 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2323 			STm->do_async_writes = value;
2324 		if ((options & MT_ST_DEF_WRITES) != 0)
2325 			STm->defaults_for_writes = value;
2326 		if ((options & MT_ST_READ_AHEAD) != 0)
2327 			STm->do_read_ahead = value;
2328 		if ((options & MT_ST_TWO_FM) != 0)
2329 			STp->two_fm = value;
2330 		if ((options & MT_ST_FAST_MTEOM) != 0)
2331 			STp->fast_mteom = value;
2332 		if ((options & MT_ST_AUTO_LOCK) != 0)
2333 			STp->do_auto_lock = value;
2334 		if ((options & MT_ST_CAN_BSR) != 0)
2335 			STp->can_bsr = value;
2336 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2337 			STp->omit_blklims = value;
2338 		if ((STp->device)->scsi_level >= SCSI_2 &&
2339 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2340 			STp->can_partitions = value;
2341 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2342 			STp->scsi2_logical = value;
2343 		if ((options & MT_ST_NOWAIT) != 0)
2344 			STp->immediate = value;
2345 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2346 			STp->immediate_filemark = value;
2347 		if ((options & MT_ST_SYSV) != 0)
2348 			STm->sysv = value;
2349 		if ((options & MT_ST_SILI) != 0)
2350 			STp->sili = value;
2351 		DEB(
2352 		if ((options & MT_ST_DEBUGGING) != 0)
2353 			debugging = value;
2354 			st_log_options(STp, STm); )
2355 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2356 		/* Retained for compatibility */
2357 	} else if (code == MT_ST_DEF_BLKSIZE) {
2358 		value = (options & ~MT_ST_OPTIONS);
2359 		if (value == ~MT_ST_OPTIONS) {
2360 			STm->default_blksize = (-1);
2361 			DEBC_printk(STp, "Default block size disabled.\n");
2362 		} else {
2363 			STm->default_blksize = value;
2364 			DEBC_printk(STp,"Default block size set to "
2365 				    "%d bytes.\n", STm->default_blksize);
2366 			if (STp->ready == ST_READY) {
2367 				STp->blksize_changed = 0;
2368 				set_mode_densblk(STp, STm);
2369 			}
2370 		}
2371 	} else if (code == MT_ST_TIMEOUTS) {
2372 		value = (options & ~MT_ST_OPTIONS);
2373 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2374 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2375 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2376 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2377 		} else {
2378 			blk_queue_rq_timeout(STp->device->request_queue,
2379 					     value * HZ);
2380 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2381 				    value);
2382 		}
2383 	} else if (code == MT_ST_SET_CLN) {
2384 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2385 		if (value != 0 &&
2386 			(value < EXTENDED_SENSE_START ||
2387 				value >= SCSI_SENSE_BUFFERSIZE))
2388 			return (-EINVAL);
2389 		STp->cln_mode = value;
2390 		STp->cln_sense_mask = (options >> 8) & 0xff;
2391 		STp->cln_sense_value = (options >> 16) & 0xff;
2392 		st_printk(KERN_INFO, STp,
2393 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2394 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2395 	} else if (code == MT_ST_DEF_OPTIONS) {
2396 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2397 		value = (options & MT_ST_CLEAR_DEFAULT);
2398 		if (code == MT_ST_DEF_DENSITY) {
2399 			if (value == MT_ST_CLEAR_DEFAULT) {
2400 				STm->default_density = (-1);
2401 				DEBC_printk(STp,
2402 					    "Density default disabled.\n");
2403 			} else {
2404 				STm->default_density = value & 0xff;
2405 				DEBC_printk(STp, "Density default set to %x\n",
2406 					    STm->default_density);
2407 				if (STp->ready == ST_READY) {
2408 					STp->density_changed = 0;
2409 					set_mode_densblk(STp, STm);
2410 				}
2411 			}
2412 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2413 			if (value == MT_ST_CLEAR_DEFAULT) {
2414 				STp->default_drvbuffer = 0xff;
2415 				DEBC_printk(STp,
2416 					    "Drive buffer default disabled.\n");
2417 			} else {
2418 				STp->default_drvbuffer = value & 7;
2419 				DEBC_printk(STp,
2420 					    "Drive buffer default set to %x\n",
2421 					    STp->default_drvbuffer);
2422 				if (STp->ready == ST_READY)
2423 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2424 			}
2425 		} else if (code == MT_ST_DEF_COMPRESSION) {
2426 			if (value == MT_ST_CLEAR_DEFAULT) {
2427 				STm->default_compression = ST_DONT_TOUCH;
2428 				DEBC_printk(STp,
2429 					    "Compression default disabled.\n");
2430 			} else {
2431 				if ((value & 0xff00) != 0) {
2432 					STp->c_algo = (value & 0xff00) >> 8;
2433 					DEBC_printk(STp, "Compression "
2434 						    "algorithm set to 0x%x.\n",
2435 						    STp->c_algo);
2436 				}
2437 				if ((value & 0xff) != 0xff) {
2438 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2439 					DEBC_printk(STp, "Compression default "
2440 						    "set to %x\n",
2441 						    (value & 1));
2442 					if (STp->ready == ST_READY) {
2443 						STp->compression_changed = 0;
2444 						st_compression(STp, (STm->default_compression == ST_YES));
2445 					}
2446 				}
2447 			}
2448 		}
2449 	} else
2450 		return (-EIO);
2451 
2452 	return 0;
2453 }
2454 
2455 #define MODE_HEADER_LENGTH  4
2456 
2457 /* Mode header and page byte offsets */
2458 #define MH_OFF_DATA_LENGTH     0
2459 #define MH_OFF_MEDIUM_TYPE     1
2460 #define MH_OFF_DEV_SPECIFIC    2
2461 #define MH_OFF_BDESCS_LENGTH   3
2462 #define MP_OFF_PAGE_NBR        0
2463 #define MP_OFF_PAGE_LENGTH     1
2464 
2465 /* Mode header and page bit masks */
2466 #define MH_BIT_WP              0x80
2467 #define MP_MSK_PAGE_NBR        0x3f
2468 
2469 /* Don't return block descriptors */
2470 #define MODE_SENSE_OMIT_BDESCS 0x08
2471 
2472 #define MODE_SELECT_PAGE_FORMAT 0x10
2473 
2474 /* Read a mode page into the tape buffer. The block descriptors are included
2475    if incl_block_descs is true. The page control is ored to the page number
2476    parameter, if necessary. */
2477 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2478 {
2479 	unsigned char cmd[MAX_COMMAND_SIZE];
2480 	struct st_request *SRpnt;
2481 
2482 	memset(cmd, 0, MAX_COMMAND_SIZE);
2483 	cmd[0] = MODE_SENSE;
2484 	if (omit_block_descs)
2485 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2486 	cmd[2] = page;
2487 	cmd[4] = 255;
2488 
2489 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2490 			   STp->device->request_queue->rq_timeout, 0, 1);
2491 	if (SRpnt == NULL)
2492 		return (STp->buffer)->syscall_result;
2493 
2494 	st_release_request(SRpnt);
2495 
2496 	return STp->buffer->syscall_result;
2497 }
2498 
2499 
2500 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2501    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2502 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2503 {
2504 	int pgo;
2505 	unsigned char cmd[MAX_COMMAND_SIZE];
2506 	struct st_request *SRpnt;
2507 	int timeout;
2508 
2509 	memset(cmd, 0, MAX_COMMAND_SIZE);
2510 	cmd[0] = MODE_SELECT;
2511 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2512 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2513 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2514 
2515 	/* Clear reserved fields */
2516 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2517 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2518 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2519 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2520 
2521 	timeout = slow ?
2522 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2523 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2524 			   timeout, 0, 1);
2525 	if (SRpnt == NULL)
2526 		return (STp->buffer)->syscall_result;
2527 
2528 	st_release_request(SRpnt);
2529 
2530 	return STp->buffer->syscall_result;
2531 }
2532 
2533 
2534 #define COMPRESSION_PAGE        0x0f
2535 #define COMPRESSION_PAGE_LENGTH 16
2536 
2537 #define CP_OFF_DCE_DCC          2
2538 #define CP_OFF_C_ALGO           7
2539 
2540 #define DCE_MASK  0x80
2541 #define DCC_MASK  0x40
2542 #define RED_MASK  0x60
2543 
2544 
2545 /* Control the compression with mode page 15. Algorithm not changed if zero.
2546 
2547    The block descriptors are read and written because Sony SDT-7000 does not
2548    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2549    Including block descriptors should not cause any harm to other drives. */
2550 
2551 static int st_compression(struct scsi_tape * STp, int state)
2552 {
2553 	int retval;
2554 	int mpoffs;  /* Offset to mode page start */
2555 	unsigned char *b_data = (STp->buffer)->b_data;
2556 
2557 	if (STp->ready != ST_READY)
2558 		return (-EIO);
2559 
2560 	/* Read the current page contents */
2561 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2562 	if (retval) {
2563 		DEBC_printk(STp, "Compression mode page not supported.\n");
2564 		return (-EIO);
2565 	}
2566 
2567 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2568 	DEBC_printk(STp, "Compression state is %d.\n",
2569 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2570 
2571 	/* Check if compression can be changed */
2572 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2573 		DEBC_printk(STp, "Compression not supported.\n");
2574 		return (-EIO);
2575 	}
2576 
2577 	/* Do the change */
2578 	if (state) {
2579 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2580 		if (STp->c_algo != 0)
2581 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2582 	}
2583 	else {
2584 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2585 		if (STp->c_algo != 0)
2586 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2587 	}
2588 
2589 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2590 	if (retval) {
2591 		DEBC_printk(STp, "Compression change failed.\n");
2592 		return (-EIO);
2593 	}
2594 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2595 
2596 	STp->compression_changed = 1;
2597 	return 0;
2598 }
2599 
2600 
2601 /* Process the load and unload commands (does unload if the load code is zero) */
2602 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2603 {
2604 	int retval = (-EIO), timeout;
2605 	unsigned char cmd[MAX_COMMAND_SIZE];
2606 	struct st_partstat *STps;
2607 	struct st_request *SRpnt;
2608 
2609 	if (STp->ready != ST_READY && !load_code) {
2610 		if (STp->ready == ST_NO_TAPE)
2611 			return (-ENOMEDIUM);
2612 		else
2613 			return (-EIO);
2614 	}
2615 
2616 	memset(cmd, 0, MAX_COMMAND_SIZE);
2617 	cmd[0] = START_STOP;
2618 	if (load_code)
2619 		cmd[4] |= 1;
2620 	/*
2621 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2622 	 */
2623 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2624 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2625 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2626 			    (cmd[4]) ? "" : "un",
2627 			    load_code - MT_ST_HPLOADER_OFFSET);
2628 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2629 	}
2630 	if (STp->immediate) {
2631 		cmd[1] = 1;	/* Don't wait for completion */
2632 		timeout = STp->device->request_queue->rq_timeout;
2633 	}
2634 	else
2635 		timeout = STp->long_timeout;
2636 
2637 	DEBC(
2638 		if (!load_code)
2639 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2640 		else
2641 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2642 		);
2643 
2644 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2645 			   timeout, MAX_RETRIES, 1);
2646 	if (!SRpnt)
2647 		return (STp->buffer)->syscall_result;
2648 
2649 	retval = (STp->buffer)->syscall_result;
2650 	st_release_request(SRpnt);
2651 
2652 	if (!retval) {	/* SCSI command successful */
2653 
2654 		if (!load_code) {
2655 			STp->rew_at_close = 0;
2656 			STp->ready = ST_NO_TAPE;
2657 		}
2658 		else {
2659 			STp->rew_at_close = STp->autorew_dev;
2660 			retval = check_tape(STp, filp);
2661 			if (retval > 0)
2662 				retval = 0;
2663 		}
2664 	}
2665 	else {
2666 		STps = &(STp->ps[STp->partition]);
2667 		STps->drv_file = STps->drv_block = (-1);
2668 	}
2669 
2670 	return retval;
2671 }
2672 
2673 #if DEBUG
2674 #define ST_DEB_FORWARD  0
2675 #define ST_DEB_BACKWARD 1
2676 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2677 {
2678 	s32 sc;
2679 
2680 	if (!debugging)
2681 		return;
2682 
2683 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2684 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2685 	if (direction)
2686 		sc = -sc;
2687 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2688 		  direction ? "backward" : "forward", sc, units);
2689 }
2690 #else
2691 #define ST_DEB_FORWARD  0
2692 #define ST_DEB_BACKWARD 1
2693 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2694 #endif
2695 
2696 
2697 /* Internal ioctl function */
2698 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2699 {
2700 	int timeout;
2701 	long ltmp;
2702 	int ioctl_result;
2703 	int chg_eof = 1;
2704 	unsigned char cmd[MAX_COMMAND_SIZE];
2705 	struct st_request *SRpnt;
2706 	struct st_partstat *STps;
2707 	int fileno, blkno, at_sm, undone;
2708 	int datalen = 0, direction = DMA_NONE;
2709 
2710 	WARN_ON(STp->buffer->do_dio != 0);
2711 	if (STp->ready != ST_READY) {
2712 		if (STp->ready == ST_NO_TAPE)
2713 			return (-ENOMEDIUM);
2714 		else
2715 			return (-EIO);
2716 	}
2717 	timeout = STp->long_timeout;
2718 	STps = &(STp->ps[STp->partition]);
2719 	fileno = STps->drv_file;
2720 	blkno = STps->drv_block;
2721 	at_sm = STps->at_sm;
2722 
2723 	memset(cmd, 0, MAX_COMMAND_SIZE);
2724 	switch (cmd_in) {
2725 	case MTFSFM:
2726 		chg_eof = 0;	/* Changed from the FSF after this */
2727 	case MTFSF:
2728 		cmd[0] = SPACE;
2729 		cmd[1] = 0x01;	/* Space FileMarks */
2730 		cmd[2] = (arg >> 16);
2731 		cmd[3] = (arg >> 8);
2732 		cmd[4] = arg;
2733 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2734 		if (fileno >= 0)
2735 			fileno += arg;
2736 		blkno = 0;
2737 		at_sm &= (arg == 0);
2738 		break;
2739 	case MTBSFM:
2740 		chg_eof = 0;	/* Changed from the FSF after this */
2741 	case MTBSF:
2742 		cmd[0] = SPACE;
2743 		cmd[1] = 0x01;	/* Space FileMarks */
2744 		ltmp = (-arg);
2745 		cmd[2] = (ltmp >> 16);
2746 		cmd[3] = (ltmp >> 8);
2747 		cmd[4] = ltmp;
2748 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2749 		if (fileno >= 0)
2750 			fileno -= arg;
2751 		blkno = (-1);	/* We can't know the block number */
2752 		at_sm &= (arg == 0);
2753 		break;
2754 	case MTFSR:
2755 		cmd[0] = SPACE;
2756 		cmd[1] = 0x00;	/* Space Blocks */
2757 		cmd[2] = (arg >> 16);
2758 		cmd[3] = (arg >> 8);
2759 		cmd[4] = arg;
2760 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2761 		if (blkno >= 0)
2762 			blkno += arg;
2763 		at_sm &= (arg == 0);
2764 		break;
2765 	case MTBSR:
2766 		cmd[0] = SPACE;
2767 		cmd[1] = 0x00;	/* Space Blocks */
2768 		ltmp = (-arg);
2769 		cmd[2] = (ltmp >> 16);
2770 		cmd[3] = (ltmp >> 8);
2771 		cmd[4] = ltmp;
2772 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2773 		if (blkno >= 0)
2774 			blkno -= arg;
2775 		at_sm &= (arg == 0);
2776 		break;
2777 	case MTFSS:
2778 		cmd[0] = SPACE;
2779 		cmd[1] = 0x04;	/* Space Setmarks */
2780 		cmd[2] = (arg >> 16);
2781 		cmd[3] = (arg >> 8);
2782 		cmd[4] = arg;
2783 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2784 		if (arg != 0) {
2785 			blkno = fileno = (-1);
2786 			at_sm = 1;
2787 		}
2788 		break;
2789 	case MTBSS:
2790 		cmd[0] = SPACE;
2791 		cmd[1] = 0x04;	/* Space Setmarks */
2792 		ltmp = (-arg);
2793 		cmd[2] = (ltmp >> 16);
2794 		cmd[3] = (ltmp >> 8);
2795 		cmd[4] = ltmp;
2796 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2797 		if (arg != 0) {
2798 			blkno = fileno = (-1);
2799 			at_sm = 1;
2800 		}
2801 		break;
2802 	case MTWEOF:
2803 	case MTWEOFI:
2804 	case MTWSM:
2805 		if (STp->write_prot)
2806 			return (-EACCES);
2807 		cmd[0] = WRITE_FILEMARKS;
2808 		if (cmd_in == MTWSM)
2809 			cmd[1] = 2;
2810 		if (cmd_in == MTWEOFI ||
2811 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2812 			cmd[1] |= 1;
2813 		cmd[2] = (arg >> 16);
2814 		cmd[3] = (arg >> 8);
2815 		cmd[4] = arg;
2816 		timeout = STp->device->request_queue->rq_timeout;
2817 		DEBC(
2818 			if (cmd_in != MTWSM)
2819 				st_printk(ST_DEB_MSG, STp,
2820 					  "Writing %d filemarks.\n",
2821 					  cmd[2] * 65536 +
2822 					  cmd[3] * 256 +
2823 					  cmd[4]);
2824 			else
2825 				st_printk(ST_DEB_MSG, STp,
2826 					  "Writing %d setmarks.\n",
2827 					  cmd[2] * 65536 +
2828 					  cmd[3] * 256 +
2829 					  cmd[4]);
2830 		)
2831 		if (fileno >= 0)
2832 			fileno += arg;
2833 		blkno = 0;
2834 		at_sm = (cmd_in == MTWSM);
2835 		break;
2836 	case MTREW:
2837 		cmd[0] = REZERO_UNIT;
2838 		if (STp->immediate) {
2839 			cmd[1] = 1;	/* Don't wait for completion */
2840 			timeout = STp->device->request_queue->rq_timeout;
2841 		}
2842 		DEBC_printk(STp, "Rewinding tape.\n");
2843 		fileno = blkno = at_sm = 0;
2844 		break;
2845 	case MTNOP:
2846 		DEBC_printk(STp, "No op on tape.\n");
2847 		return 0;	/* Should do something ? */
2848 		break;
2849 	case MTRETEN:
2850 		cmd[0] = START_STOP;
2851 		if (STp->immediate) {
2852 			cmd[1] = 1;	/* Don't wait for completion */
2853 			timeout = STp->device->request_queue->rq_timeout;
2854 		}
2855 		cmd[4] = 3;
2856 		DEBC_printk(STp, "Retensioning tape.\n");
2857 		fileno = blkno = at_sm = 0;
2858 		break;
2859 	case MTEOM:
2860 		if (!STp->fast_mteom) {
2861 			/* space to the end of tape */
2862 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2863 			fileno = STps->drv_file;
2864 			if (STps->eof >= ST_EOD_1)
2865 				return 0;
2866 			/* The next lines would hide the number of spaced FileMarks
2867 			   That's why I inserted the previous lines. I had no luck
2868 			   with detecting EOM with FSF, so we go now to EOM.
2869 			   Joerg Weule */
2870 		} else
2871 			fileno = (-1);
2872 		cmd[0] = SPACE;
2873 		cmd[1] = 3;
2874 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2875 		blkno = -1;
2876 		at_sm = 0;
2877 		break;
2878 	case MTERASE:
2879 		if (STp->write_prot)
2880 			return (-EACCES);
2881 		cmd[0] = ERASE;
2882 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2883 		if (STp->immediate) {
2884 			cmd[1] |= 2;	/* Don't wait for completion */
2885 			timeout = STp->device->request_queue->rq_timeout;
2886 		}
2887 		else
2888 			timeout = STp->long_timeout * 8;
2889 
2890 		DEBC_printk(STp, "Erasing tape.\n");
2891 		fileno = blkno = at_sm = 0;
2892 		break;
2893 	case MTSETBLK:		/* Set block length */
2894 	case MTSETDENSITY:	/* Set tape density */
2895 	case MTSETDRVBUFFER:	/* Set drive buffering */
2896 	case SET_DENS_AND_BLK:	/* Set density and block size */
2897 		chg_eof = 0;
2898 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2899 			return (-EIO);	/* Not allowed if data in buffer */
2900 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2901 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2902 		    STp->max_block > 0 &&
2903 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2904 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2905 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2906 			return (-EINVAL);
2907 		}
2908 		cmd[0] = MODE_SELECT;
2909 		if ((STp->use_pf & USE_PF))
2910 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2911 		cmd[4] = datalen = 12;
2912 		direction = DMA_TO_DEVICE;
2913 
2914 		memset((STp->buffer)->b_data, 0, 12);
2915 		if (cmd_in == MTSETDRVBUFFER)
2916 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2917 		else
2918 			(STp->buffer)->b_data[2] =
2919 			    STp->drv_buffer << 4;
2920 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2921 		if (cmd_in == MTSETDENSITY) {
2922 			(STp->buffer)->b_data[4] = arg;
2923 			STp->density_changed = 1;	/* At least we tried ;-) */
2924 		} else if (cmd_in == SET_DENS_AND_BLK)
2925 			(STp->buffer)->b_data[4] = arg >> 24;
2926 		else
2927 			(STp->buffer)->b_data[4] = STp->density;
2928 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2929 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2930 			if (cmd_in == MTSETBLK)
2931 				STp->blksize_changed = 1; /* At least we tried ;-) */
2932 		} else
2933 			ltmp = STp->block_size;
2934 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2935 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2936 		(STp->buffer)->b_data[11] = ltmp;
2937 		timeout = STp->device->request_queue->rq_timeout;
2938 		DEBC(
2939 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2940 				st_printk(ST_DEB_MSG, STp,
2941 					  "Setting block size to %d bytes.\n",
2942 					  (STp->buffer)->b_data[9] * 65536 +
2943 					  (STp->buffer)->b_data[10] * 256 +
2944 					  (STp->buffer)->b_data[11]);
2945 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2946 				st_printk(ST_DEB_MSG, STp,
2947 					  "Setting density code to %x.\n",
2948 					  (STp->buffer)->b_data[4]);
2949 			if (cmd_in == MTSETDRVBUFFER)
2950 				st_printk(ST_DEB_MSG, STp,
2951 					  "Setting drive buffer code to %d.\n",
2952 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2953 		)
2954 		break;
2955 	default:
2956 		return (-ENOSYS);
2957 	}
2958 
2959 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2960 			   timeout, MAX_RETRIES, 1);
2961 	if (!SRpnt)
2962 		return (STp->buffer)->syscall_result;
2963 
2964 	ioctl_result = (STp->buffer)->syscall_result;
2965 
2966 	if (!ioctl_result) {	/* SCSI command successful */
2967 		st_release_request(SRpnt);
2968 		SRpnt = NULL;
2969 		STps->drv_block = blkno;
2970 		STps->drv_file = fileno;
2971 		STps->at_sm = at_sm;
2972 
2973 		if (cmd_in == MTBSFM)
2974 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2975 		else if (cmd_in == MTFSFM)
2976 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2977 
2978 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2979 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2980 			if (STp->block_size != 0) {
2981 				(STp->buffer)->buffer_blocks =
2982 				    (STp->buffer)->buffer_size / STp->block_size;
2983 			}
2984 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2985 			if (cmd_in == SET_DENS_AND_BLK)
2986 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2987 		} else if (cmd_in == MTSETDRVBUFFER)
2988 			STp->drv_buffer = (arg & 7);
2989 		else if (cmd_in == MTSETDENSITY)
2990 			STp->density = arg;
2991 
2992 		if (cmd_in == MTEOM)
2993 			STps->eof = ST_EOD;
2994 		else if (cmd_in == MTFSF)
2995 			STps->eof = ST_FM;
2996 		else if (chg_eof)
2997 			STps->eof = ST_NOEOF;
2998 
2999 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
3000 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
3001 	} else { /* SCSI command was not completely successful. Don't return
3002                     from this block without releasing the SCSI command block! */
3003 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
3004 
3005 		if (cmdstatp->flags & SENSE_EOM) {
3006 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3007 			    cmd_in != MTBSR && cmd_in != MTBSS)
3008 				STps->eof = ST_EOM_OK;
3009 			STps->drv_block = 0;
3010 		}
3011 
3012 		if (cmdstatp->remainder_valid)
3013 			undone = (int)cmdstatp->uremainder64;
3014 		else
3015 			undone = 0;
3016 
3017 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3018 		    cmdstatp->have_sense &&
3019 		    (cmdstatp->flags & SENSE_EOM)) {
3020 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3021 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3022 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3023 				STps->eof = ST_NOEOF;
3024 			} else {  /* Writing EOF(s) failed */
3025 				if (fileno >= 0)
3026 					fileno -= undone;
3027 				if (undone < arg)
3028 					STps->eof = ST_NOEOF;
3029 			}
3030 			STps->drv_file = fileno;
3031 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3032 			if (fileno >= 0)
3033 				STps->drv_file = fileno - undone;
3034 			else
3035 				STps->drv_file = fileno;
3036 			STps->drv_block = -1;
3037 			STps->eof = ST_NOEOF;
3038 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3039 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3040 				undone = (-undone);
3041 			if (STps->drv_file >= 0)
3042 				STps->drv_file = fileno + undone;
3043 			STps->drv_block = 0;
3044 			STps->eof = ST_NOEOF;
3045 		} else if (cmd_in == MTFSR) {
3046 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3047 				if (STps->drv_file >= 0)
3048 					STps->drv_file++;
3049 				STps->drv_block = 0;
3050 				STps->eof = ST_FM;
3051 			} else {
3052 				if (blkno >= undone)
3053 					STps->drv_block = blkno - undone;
3054 				else
3055 					STps->drv_block = (-1);
3056 				STps->eof = ST_NOEOF;
3057 			}
3058 		} else if (cmd_in == MTBSR) {
3059 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3060 				STps->drv_file--;
3061 				STps->drv_block = (-1);
3062 			} else {
3063 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3064 					undone = (-undone);
3065 				if (STps->drv_block >= 0)
3066 					STps->drv_block = blkno + undone;
3067 			}
3068 			STps->eof = ST_NOEOF;
3069 		} else if (cmd_in == MTEOM) {
3070 			STps->drv_file = (-1);
3071 			STps->drv_block = (-1);
3072 			STps->eof = ST_EOD;
3073 		} else if (cmd_in == MTSETBLK ||
3074 			   cmd_in == MTSETDENSITY ||
3075 			   cmd_in == MTSETDRVBUFFER ||
3076 			   cmd_in == SET_DENS_AND_BLK) {
3077 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3078 			    !(STp->use_pf & PF_TESTED)) {
3079 				/* Try the other possible state of Page Format if not
3080 				   already tried */
3081 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3082 				st_release_request(SRpnt);
3083 				SRpnt = NULL;
3084 				return st_int_ioctl(STp, cmd_in, arg);
3085 			}
3086 		} else if (chg_eof)
3087 			STps->eof = ST_NOEOF;
3088 
3089 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3090 			STps->eof = ST_EOD;
3091 
3092 		st_release_request(SRpnt);
3093 		SRpnt = NULL;
3094 	}
3095 
3096 	return ioctl_result;
3097 }
3098 
3099 
3100 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3101    structure. */
3102 
3103 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3104 			int logical)
3105 {
3106 	int result;
3107 	unsigned char scmd[MAX_COMMAND_SIZE];
3108 	struct st_request *SRpnt;
3109 
3110 	if (STp->ready != ST_READY)
3111 		return (-EIO);
3112 
3113 	memset(scmd, 0, MAX_COMMAND_SIZE);
3114 	if ((STp->device)->scsi_level < SCSI_2) {
3115 		scmd[0] = QFA_REQUEST_BLOCK;
3116 		scmd[4] = 3;
3117 	} else {
3118 		scmd[0] = READ_POSITION;
3119 		if (!logical && !STp->scsi2_logical)
3120 			scmd[1] = 1;
3121 	}
3122 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3123 			   STp->device->request_queue->rq_timeout,
3124 			   MAX_READY_RETRIES, 1);
3125 	if (!SRpnt)
3126 		return (STp->buffer)->syscall_result;
3127 
3128 	if ((STp->buffer)->syscall_result != 0 ||
3129 	    (STp->device->scsi_level >= SCSI_2 &&
3130 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3131 		*block = *partition = 0;
3132 		DEBC_printk(STp, " Can't read tape position.\n");
3133 		result = (-EIO);
3134 	} else {
3135 		result = 0;
3136 		if ((STp->device)->scsi_level < SCSI_2) {
3137 			*block = ((STp->buffer)->b_data[0] << 16)
3138 			    + ((STp->buffer)->b_data[1] << 8)
3139 			    + (STp->buffer)->b_data[2];
3140 			*partition = 0;
3141 		} else {
3142 			*block = ((STp->buffer)->b_data[4] << 24)
3143 			    + ((STp->buffer)->b_data[5] << 16)
3144 			    + ((STp->buffer)->b_data[6] << 8)
3145 			    + (STp->buffer)->b_data[7];
3146 			*partition = (STp->buffer)->b_data[1];
3147 			if (((STp->buffer)->b_data[0] & 0x80) &&
3148 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3149 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3150 		}
3151 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3152 			    *block, *partition);
3153 	}
3154 	st_release_request(SRpnt);
3155 	SRpnt = NULL;
3156 
3157 	return result;
3158 }
3159 
3160 
3161 /* Set the tape block and partition. Negative partition means that only the
3162    block should be set in vendor specific way. */
3163 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3164 			int logical)
3165 {
3166 	struct st_partstat *STps;
3167 	int result, p;
3168 	unsigned int blk;
3169 	int timeout;
3170 	unsigned char scmd[MAX_COMMAND_SIZE];
3171 	struct st_request *SRpnt;
3172 
3173 	if (STp->ready != ST_READY)
3174 		return (-EIO);
3175 	timeout = STp->long_timeout;
3176 	STps = &(STp->ps[STp->partition]);
3177 
3178 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3179 		    block, partition);
3180 	DEB(if (partition < 0)
3181 		return (-EIO); )
3182 
3183 	/* Update the location at the partition we are leaving */
3184 	if ((!STp->can_partitions && partition != 0) ||
3185 	    partition >= ST_NBR_PARTITIONS)
3186 		return (-EINVAL);
3187 	if (partition != STp->partition) {
3188 		if (get_location(STp, &blk, &p, 1))
3189 			STps->last_block_valid = 0;
3190 		else {
3191 			STps->last_block_valid = 1;
3192 			STps->last_block_visited = blk;
3193 			DEBC_printk(STp, "Visited block %d for "
3194 				    "partition %d saved.\n",
3195 				    blk, STp->partition);
3196 		}
3197 	}
3198 
3199 	memset(scmd, 0, MAX_COMMAND_SIZE);
3200 	if ((STp->device)->scsi_level < SCSI_2) {
3201 		scmd[0] = QFA_SEEK_BLOCK;
3202 		scmd[2] = (block >> 16);
3203 		scmd[3] = (block >> 8);
3204 		scmd[4] = block;
3205 		scmd[5] = 0;
3206 	} else {
3207 		scmd[0] = SEEK_10;
3208 		scmd[3] = (block >> 24);
3209 		scmd[4] = (block >> 16);
3210 		scmd[5] = (block >> 8);
3211 		scmd[6] = block;
3212 		if (!logical && !STp->scsi2_logical)
3213 			scmd[1] = 4;
3214 		if (STp->partition != partition) {
3215 			scmd[1] |= 2;
3216 			scmd[8] = partition;
3217 			DEBC_printk(STp, "Trying to change partition "
3218 				    "from %d to %d\n", STp->partition,
3219 				    partition);
3220 		}
3221 	}
3222 	if (STp->immediate) {
3223 		scmd[1] |= 1;		/* Don't wait for completion */
3224 		timeout = STp->device->request_queue->rq_timeout;
3225 	}
3226 
3227 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3228 			   timeout, MAX_READY_RETRIES, 1);
3229 	if (!SRpnt)
3230 		return (STp->buffer)->syscall_result;
3231 
3232 	STps->drv_block = STps->drv_file = (-1);
3233 	STps->eof = ST_NOEOF;
3234 	if ((STp->buffer)->syscall_result != 0) {
3235 		result = (-EIO);
3236 		if (STp->can_partitions &&
3237 		    (STp->device)->scsi_level >= SCSI_2 &&
3238 		    (p = find_partition(STp)) >= 0)
3239 			STp->partition = p;
3240 	} else {
3241 		if (STp->can_partitions) {
3242 			STp->partition = partition;
3243 			STps = &(STp->ps[partition]);
3244 			if (!STps->last_block_valid ||
3245 			    STps->last_block_visited != block) {
3246 				STps->at_sm = 0;
3247 				STps->rw = ST_IDLE;
3248 			}
3249 		} else
3250 			STps->at_sm = 0;
3251 		if (block == 0)
3252 			STps->drv_block = STps->drv_file = 0;
3253 		result = 0;
3254 	}
3255 
3256 	st_release_request(SRpnt);
3257 	SRpnt = NULL;
3258 
3259 	return result;
3260 }
3261 
3262 
3263 /* Find the current partition number for the drive status. Called from open and
3264    returns either partition number of negative error code. */
3265 static int find_partition(struct scsi_tape *STp)
3266 {
3267 	int i, partition;
3268 	unsigned int block;
3269 
3270 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3271 		return i;
3272 	if (partition >= ST_NBR_PARTITIONS)
3273 		return (-EIO);
3274 	return partition;
3275 }
3276 
3277 
3278 /* Change the partition if necessary */
3279 static int switch_partition(struct scsi_tape *STp)
3280 {
3281 	struct st_partstat *STps;
3282 
3283 	if (STp->partition == STp->new_partition)
3284 		return 0;
3285 	STps = &(STp->ps[STp->new_partition]);
3286 	if (!STps->last_block_valid)
3287 		STps->last_block_visited = 0;
3288 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3289 }
3290 
3291 /* Functions for reading and writing the medium partition mode page. */
3292 
3293 #define PART_PAGE   0x11
3294 #define PART_PAGE_FIXED_LENGTH 8
3295 
3296 #define PP_OFF_MAX_ADD_PARTS   2
3297 #define PP_OFF_NBR_ADD_PARTS   3
3298 #define PP_OFF_FLAGS           4
3299 #define PP_OFF_PART_UNITS      6
3300 #define PP_OFF_RESERVED        7
3301 
3302 #define PP_BIT_IDP             0x20
3303 #define PP_BIT_FDP             0x80
3304 #define PP_MSK_PSUM_MB         0x10
3305 #define PP_MSK_PSUM_UNITS      0x18
3306 #define PP_MSK_POFM            0x04
3307 
3308 /* Get the number of partitions on the tape. As a side effect reads the
3309    mode page into the tape buffer. */
3310 static int nbr_partitions(struct scsi_tape *STp)
3311 {
3312 	int result;
3313 
3314 	if (STp->ready != ST_READY)
3315 		return (-EIO);
3316 
3317 	result = read_mode_page(STp, PART_PAGE, 1);
3318 
3319 	if (result) {
3320 		DEBC_printk(STp, "Can't read medium partition page.\n");
3321 		result = (-EIO);
3322 	} else {
3323 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3324 					      PP_OFF_NBR_ADD_PARTS] + 1;
3325 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3326 	}
3327 
3328 	return result;
3329 }
3330 
3331 
3332 static int format_medium(struct scsi_tape *STp, int format)
3333 {
3334 	int result = 0;
3335 	int timeout = STp->long_timeout;
3336 	unsigned char scmd[MAX_COMMAND_SIZE];
3337 	struct st_request *SRpnt;
3338 
3339 	memset(scmd, 0, MAX_COMMAND_SIZE);
3340 	scmd[0] = FORMAT_UNIT;
3341 	scmd[2] = format;
3342 	if (STp->immediate) {
3343 		scmd[1] |= 1;		/* Don't wait for completion */
3344 		timeout = STp->device->request_queue->rq_timeout;
3345 	}
3346 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3347 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3348 			   timeout, MAX_RETRIES, 1);
3349 	if (!SRpnt)
3350 		result = STp->buffer->syscall_result;
3351 	return result;
3352 }
3353 
3354 
3355 /* Partition the tape into two partitions if size > 0 or one partition if
3356    size == 0.
3357 
3358    The block descriptors are read and written because Sony SDT-7000 does not
3359    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3360 
3361    My HP C1533A drive returns only one partition size field. This is used to
3362    set the size of partition 1. There is no size field for the default partition.
3363    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3364    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3365    The following algorithm is used to accommodate both drives: if the number of
3366    partition size fields is greater than the maximum number of additional partitions
3367    in the mode page, the second field is used. Otherwise the first field is used.
3368 
3369    For Seagate DDS drives the page length must be 8 when no partitions is defined
3370    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3371    is acceptable also to some other old drives and enforced if the first partition
3372    size field is used for the first additional partition size.
3373 
3374    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3375  */
3376 static int partition_tape(struct scsi_tape *STp, int size)
3377 {
3378 	int result;
3379 	int target_partition;
3380 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3381 	int pgo, psd_cnt, psdo;
3382 	int psum = PP_MSK_PSUM_MB, units = 0;
3383 	unsigned char *bp;
3384 
3385 	result = read_mode_page(STp, PART_PAGE, 0);
3386 	if (result) {
3387 		DEBC_printk(STp, "Can't read partition mode page.\n");
3388 		return result;
3389 	}
3390 	target_partition = 1;
3391 	if (size < 0) {
3392 		target_partition = 0;
3393 		size = -size;
3394 	}
3395 
3396 	/* The mode page is in the buffer. Let's modify it and write it. */
3397 	bp = (STp->buffer)->b_data;
3398 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3399 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3400 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3401 
3402 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3403 
3404 	if (scsi3) {
3405 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3406 		if (needs_format && size == 0) {
3407 			/* No need to write the mode page when clearing
3408 			 *  partitioning
3409 			 */
3410 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3411 			result = format_medium(STp, 0);
3412 			goto out;
3413 		}
3414 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3415 			psd_cnt = 2;
3416 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3417 			/* Use units scaling for large partitions if the device
3418 			 * suggests it and no precision lost. Required for IBM
3419 			 * TS1140/50 drives that don't support MB units.
3420 			 */
3421 			if (size >= 1000 && (size % 1000) == 0) {
3422 				size /= 1000;
3423 				psum = PP_MSK_PSUM_UNITS;
3424 				units = 9; /* GB */
3425 			}
3426 		}
3427 		/* Try it anyway if too large to specify in MB */
3428 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3429 			size /= 1000;
3430 			psum = PP_MSK_PSUM_UNITS;
3431 			units = 9;  /* GB */
3432 		}
3433 	}
3434 
3435 	if (size >= 65535 ||  /* Does not fit into two bytes */
3436 	    (target_partition == 0 && psd_cnt < 2)) {
3437 		result = -EINVAL;
3438 		goto out;
3439 	}
3440 
3441 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3442 	/* The second condition is for HP DDS which use only one partition size
3443 	 * descriptor
3444 	 */
3445 	if (target_partition > 0 &&
3446 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3447 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3448 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3449 		psdo += 2;
3450 	}
3451 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3452 
3453 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3454 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3455 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3456 
3457 	if (size == 0) {
3458 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3459 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3460 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3461 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3462 	} else {
3463 		bp[psdo] = (size >> 8) & 0xff;
3464 		bp[psdo + 1] = size & 0xff;
3465 		if (target_partition == 0)
3466 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3467 		bp[pgo + 3] = 1;
3468 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3469 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3470 		DEBC_printk(STp,
3471 			    "Formatting tape with two partitions (%i = %d MB).\n",
3472 			    target_partition, units > 0 ? size * 1000 : size);
3473 	}
3474 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3475 	bp[pgo + PP_OFF_RESERVED] = 0;
3476 	if (size != 1 || units != 0) {
3477 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3478 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3479 		bp[pgo + PP_OFF_PART_UNITS] = units;
3480 	} else
3481 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3482 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3483 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3484 
3485 	result = write_mode_page(STp, PART_PAGE, 1);
3486 
3487 	if (!result && needs_format)
3488 		result = format_medium(STp, 1);
3489 
3490 	if (result) {
3491 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3492 		result = (-EIO);
3493 	}
3494 
3495 out:
3496 	return result;
3497 }
3498 
3499 
3500 
3501 /* The ioctl command */
3502 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3503 {
3504 	int i, cmd_nr, cmd_type, bt;
3505 	int retval = 0;
3506 	unsigned int blk;
3507 	struct scsi_tape *STp = file->private_data;
3508 	struct st_modedef *STm;
3509 	struct st_partstat *STps;
3510 	void __user *p = (void __user *)arg;
3511 
3512 	if (mutex_lock_interruptible(&STp->lock))
3513 		return -ERESTARTSYS;
3514 
3515 	DEB(
3516 	if (debugging && !STp->in_use) {
3517 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3518 		retval = (-EIO);
3519 		goto out;
3520 	} ) /* end DEB */
3521 
3522 	STm = &(STp->modes[STp->current_mode]);
3523 	STps = &(STp->ps[STp->partition]);
3524 
3525 	/*
3526 	 * If we are in the middle of error recovery, don't let anyone
3527 	 * else try and use this device.  Also, if error recovery fails, it
3528 	 * may try and take the device offline, in which case all further
3529 	 * access to the device is prohibited.
3530 	 */
3531 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3532 			file->f_flags & O_NDELAY);
3533 	if (retval)
3534 		goto out;
3535 
3536 	cmd_type = _IOC_TYPE(cmd_in);
3537 	cmd_nr = _IOC_NR(cmd_in);
3538 
3539 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3540 		struct mtop mtc;
3541 
3542 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3543 			retval = (-EINVAL);
3544 			goto out;
3545 		}
3546 
3547 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3548 		if (i) {
3549 			retval = (-EFAULT);
3550 			goto out;
3551 		}
3552 
3553 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3554 			st_printk(KERN_WARNING, STp,
3555 				  "MTSETDRVBUFFER only allowed for root.\n");
3556 			retval = (-EPERM);
3557 			goto out;
3558 		}
3559 		if (!STm->defined &&
3560 		    (mtc.mt_op != MTSETDRVBUFFER &&
3561 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3562 			retval = (-ENXIO);
3563 			goto out;
3564 		}
3565 
3566 		if (!STp->pos_unknown) {
3567 
3568 			if (STps->eof == ST_FM_HIT) {
3569 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3570                                     mtc.mt_op == MTEOM) {
3571 					mtc.mt_count -= 1;
3572 					if (STps->drv_file >= 0)
3573 						STps->drv_file += 1;
3574 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3575 					mtc.mt_count += 1;
3576 					if (STps->drv_file >= 0)
3577 						STps->drv_file += 1;
3578 				}
3579 			}
3580 
3581 			if (mtc.mt_op == MTSEEK) {
3582 				/* Old position must be restored if partition will be
3583                                    changed */
3584 				i = !STp->can_partitions ||
3585 				    (STp->new_partition != STp->partition);
3586 			} else {
3587 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3588 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3589 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3590 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3591 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3592 				    mtc.mt_op == MTCOMPRESSION;
3593 			}
3594 			i = flush_buffer(STp, i);
3595 			if (i < 0) {
3596 				retval = i;
3597 				goto out;
3598 			}
3599 			if (STps->rw == ST_WRITING &&
3600 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3601 			     mtc.mt_op == MTSEEK ||
3602 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3603 				i = st_int_ioctl(STp, MTWEOF, 1);
3604 				if (i < 0) {
3605 					retval = i;
3606 					goto out;
3607 				}
3608 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3609 					mtc.mt_count++;
3610 				STps->rw = ST_IDLE;
3611 			     }
3612 
3613 		} else {
3614 			/*
3615 			 * If there was a bus reset, block further access
3616 			 * to this device.  If the user wants to rewind the tape,
3617 			 * then reset the flag and allow access again.
3618 			 */
3619 			if (mtc.mt_op != MTREW &&
3620 			    mtc.mt_op != MTOFFL &&
3621 			    mtc.mt_op != MTRETEN &&
3622 			    mtc.mt_op != MTERASE &&
3623 			    mtc.mt_op != MTSEEK &&
3624 			    mtc.mt_op != MTEOM) {
3625 				retval = (-EIO);
3626 				goto out;
3627 			}
3628 			reset_state(STp);
3629 			/* remove this when the midlevel properly clears was_reset */
3630 			STp->device->was_reset = 0;
3631 		}
3632 
3633 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3634 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3635 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3636 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3637 
3638 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3639 			do_door_lock(STp, 0);	/* Ignore result! */
3640 
3641 		if (mtc.mt_op == MTSETDRVBUFFER &&
3642 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3643 			retval = st_set_options(STp, mtc.mt_count);
3644 			goto out;
3645 		}
3646 
3647 		if (mtc.mt_op == MTSETPART) {
3648 			if (!STp->can_partitions ||
3649 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3650 				retval = (-EINVAL);
3651 				goto out;
3652 			}
3653 			if (mtc.mt_count >= STp->nbr_partitions &&
3654 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3655 				retval = (-EIO);
3656 				goto out;
3657 			}
3658 			if (mtc.mt_count >= STp->nbr_partitions) {
3659 				retval = (-EINVAL);
3660 				goto out;
3661 			}
3662 			STp->new_partition = mtc.mt_count;
3663 			retval = 0;
3664 			goto out;
3665 		}
3666 
3667 		if (mtc.mt_op == MTMKPART) {
3668 			if (!STp->can_partitions) {
3669 				retval = (-EINVAL);
3670 				goto out;
3671 			}
3672 			i = do_load_unload(STp, file, 1);
3673 			if (i < 0) {
3674 				retval = i;
3675 				goto out;
3676 			}
3677 			i = partition_tape(STp, mtc.mt_count);
3678 			if (i < 0) {
3679 				retval = i;
3680 				goto out;
3681 			}
3682 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3683 				STp->ps[i].rw = ST_IDLE;
3684 				STp->ps[i].at_sm = 0;
3685 				STp->ps[i].last_block_valid = 0;
3686 			}
3687 			STp->partition = STp->new_partition = 0;
3688 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3689 			STps->drv_block = STps->drv_file = 0;
3690 			retval = 0;
3691 			goto out;
3692 		}
3693 
3694 		if (mtc.mt_op == MTSEEK) {
3695 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3696 			if (!STp->can_partitions)
3697 				STp->ps[0].rw = ST_IDLE;
3698 			retval = i;
3699 			goto out;
3700 		}
3701 
3702 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3703 			retval = do_load_unload(STp, file, 0);
3704 			goto out;
3705 		}
3706 
3707 		if (mtc.mt_op == MTLOAD) {
3708 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3709 			goto out;
3710 		}
3711 
3712 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3713 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3714 			goto out;
3715 		}
3716 
3717 		if (STp->can_partitions && STp->ready == ST_READY &&
3718 		    (i = switch_partition(STp)) < 0) {
3719 			retval = i;
3720 			goto out;
3721 		}
3722 
3723 		if (mtc.mt_op == MTCOMPRESSION)
3724 			retval = st_compression(STp, (mtc.mt_count & 1));
3725 		else
3726 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3727 		goto out;
3728 	}
3729 	if (!STm->defined) {
3730 		retval = (-ENXIO);
3731 		goto out;
3732 	}
3733 
3734 	if ((i = flush_buffer(STp, 0)) < 0) {
3735 		retval = i;
3736 		goto out;
3737 	}
3738 	if (STp->can_partitions &&
3739 	    (i = switch_partition(STp)) < 0) {
3740 		retval = i;
3741 		goto out;
3742 	}
3743 
3744 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3745 		struct mtget mt_status;
3746 
3747 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3748 			 retval = (-EINVAL);
3749 			 goto out;
3750 		}
3751 
3752 		mt_status.mt_type = STp->tape_type;
3753 		mt_status.mt_dsreg =
3754 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3755 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3756 		mt_status.mt_blkno = STps->drv_block;
3757 		mt_status.mt_fileno = STps->drv_file;
3758 		if (STp->block_size != 0) {
3759 			if (STps->rw == ST_WRITING)
3760 				mt_status.mt_blkno +=
3761 				    (STp->buffer)->buffer_bytes / STp->block_size;
3762 			else if (STps->rw == ST_READING)
3763 				mt_status.mt_blkno -=
3764                                         ((STp->buffer)->buffer_bytes +
3765                                          STp->block_size - 1) / STp->block_size;
3766 		}
3767 
3768 		mt_status.mt_gstat = 0;
3769 		if (STp->drv_write_prot)
3770 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3771 		if (mt_status.mt_blkno == 0) {
3772 			if (mt_status.mt_fileno == 0)
3773 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3774 			else
3775 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3776 		}
3777 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3778 		mt_status.mt_resid = STp->partition;
3779 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3780 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3781 		else if (STps->eof >= ST_EOM_OK)
3782 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3783 		if (STp->density == 1)
3784 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3785 		else if (STp->density == 2)
3786 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3787 		else if (STp->density == 3)
3788 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3789 		if (STp->ready == ST_READY)
3790 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3791 		if (STp->ready == ST_NO_TAPE)
3792 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3793 		if (STps->at_sm)
3794 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3795 		if (STm->do_async_writes ||
3796                     (STm->do_buffer_writes && STp->block_size != 0) ||
3797 		    STp->drv_buffer != 0)
3798 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3799 		if (STp->cleaning_req)
3800 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3801 
3802 		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
3803 		if (i) {
3804 			retval = (-EFAULT);
3805 			goto out;
3806 		}
3807 
3808 		STp->recover_reg = 0;		/* Clear after read */
3809 		retval = 0;
3810 		goto out;
3811 	}			/* End of MTIOCGET */
3812 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3813 		struct mtpos mt_pos;
3814 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3815 			 retval = (-EINVAL);
3816 			 goto out;
3817 		}
3818 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3819 			retval = i;
3820 			goto out;
3821 		}
3822 		mt_pos.mt_blkno = blk;
3823 		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
3824 		if (i)
3825 			retval = (-EFAULT);
3826 		goto out;
3827 	}
3828 	mutex_unlock(&STp->lock);
3829 	switch (cmd_in) {
3830 		case SCSI_IOCTL_GET_IDLUN:
3831 		case SCSI_IOCTL_GET_BUS_NUMBER:
3832 			break;
3833 		default:
3834 			if ((cmd_in == SG_IO ||
3835 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3836 			     cmd_in == CDROM_SEND_PACKET) &&
3837 			    !capable(CAP_SYS_RAWIO))
3838 				i = -EPERM;
3839 			else
3840 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3841 						   file->f_mode, cmd_in, p);
3842 			if (i != -ENOTTY)
3843 				return i;
3844 			break;
3845 	}
3846 	retval = scsi_ioctl(STp->device, cmd_in, p);
3847 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3848 		STp->rew_at_close = 0;
3849 		STp->ready = ST_NO_TAPE;
3850 	}
3851 	return retval;
3852 
3853  out:
3854 	mutex_unlock(&STp->lock);
3855 	return retval;
3856 }
3857 
3858 #ifdef CONFIG_COMPAT
3859 static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3860 {
3861 	struct scsi_tape *STp = file->private_data;
3862 	struct scsi_device *sdev = STp->device;
3863 	int ret = -ENOIOCTLCMD;
3864 	if (sdev->host->hostt->compat_ioctl) {
3865 
3866 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
3867 
3868 	}
3869 	return ret;
3870 }
3871 #endif
3872 
3873 
3874 
3875 /* Try to allocate a new tape buffer. Calling function must not hold
3876    dev_arr_lock. */
3877 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3878 {
3879 	struct st_buffer *tb;
3880 
3881 	tb = kzalloc(sizeof(struct st_buffer), GFP_ATOMIC);
3882 	if (!tb) {
3883 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3884 		return NULL;
3885 	}
3886 	tb->frp_segs = 0;
3887 	tb->use_sg = max_sg;
3888 	tb->dma = need_dma;
3889 	tb->buffer_size = 0;
3890 
3891 	tb->reserved_pages = kzalloc(max_sg * sizeof(struct page *),
3892 				     GFP_ATOMIC);
3893 	if (!tb->reserved_pages) {
3894 		kfree(tb);
3895 		return NULL;
3896 	}
3897 
3898 	return tb;
3899 }
3900 
3901 
3902 /* Try to allocate enough space in the tape buffer */
3903 #define ST_MAX_ORDER 6
3904 
3905 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3906 {
3907 	int segs, max_segs, b_size, order, got;
3908 	gfp_t priority;
3909 
3910 	if (new_size <= STbuffer->buffer_size)
3911 		return 1;
3912 
3913 	if (STbuffer->buffer_size <= PAGE_SIZE)
3914 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3915 
3916 	max_segs = STbuffer->use_sg;
3917 
3918 	priority = GFP_KERNEL | __GFP_NOWARN;
3919 	if (need_dma)
3920 		priority |= GFP_DMA;
3921 
3922 	if (STbuffer->cleared)
3923 		priority |= __GFP_ZERO;
3924 
3925 	if (STbuffer->frp_segs) {
3926 		order = STbuffer->reserved_page_order;
3927 		b_size = PAGE_SIZE << order;
3928 	} else {
3929 		for (b_size = PAGE_SIZE, order = 0;
3930 		     order < ST_MAX_ORDER &&
3931 			     max_segs * (PAGE_SIZE << order) < new_size;
3932 		     order++, b_size *= 2)
3933 			;  /* empty */
3934 		STbuffer->reserved_page_order = order;
3935 	}
3936 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3937 		if (order == ST_MAX_ORDER)
3938 			return 0;
3939 		normalize_buffer(STbuffer);
3940 		return enlarge_buffer(STbuffer, new_size, need_dma);
3941 	}
3942 
3943 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3944 	     segs < max_segs && got < new_size;) {
3945 		struct page *page;
3946 
3947 		page = alloc_pages(priority, order);
3948 		if (!page) {
3949 			DEB(STbuffer->buffer_size = got);
3950 			normalize_buffer(STbuffer);
3951 			return 0;
3952 		}
3953 
3954 		STbuffer->frp_segs += 1;
3955 		got += b_size;
3956 		STbuffer->buffer_size = got;
3957 		STbuffer->reserved_pages[segs] = page;
3958 		segs++;
3959 	}
3960 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3961 
3962 	return 1;
3963 }
3964 
3965 
3966 /* Make sure that no data from previous user is in the internal buffer */
3967 static void clear_buffer(struct st_buffer * st_bp)
3968 {
3969 	int i;
3970 
3971 	for (i=0; i < st_bp->frp_segs; i++)
3972 		memset(page_address(st_bp->reserved_pages[i]), 0,
3973 		       PAGE_SIZE << st_bp->reserved_page_order);
3974 	st_bp->cleared = 1;
3975 }
3976 
3977 
3978 /* Release the extra buffer */
3979 static void normalize_buffer(struct st_buffer * STbuffer)
3980 {
3981 	int i, order = STbuffer->reserved_page_order;
3982 
3983 	for (i = 0; i < STbuffer->frp_segs; i++) {
3984 		__free_pages(STbuffer->reserved_pages[i], order);
3985 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3986 	}
3987 	STbuffer->frp_segs = 0;
3988 	STbuffer->sg_segs = 0;
3989 	STbuffer->reserved_page_order = 0;
3990 	STbuffer->map_data.offset = 0;
3991 }
3992 
3993 
3994 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3995    negative error code. */
3996 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3997 {
3998 	int i, cnt, res, offset;
3999 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4000 
4001 	for (i = 0, offset = st_bp->buffer_bytes;
4002 	     i < st_bp->frp_segs && offset >= length; i++)
4003 		offset -= length;
4004 	if (i == st_bp->frp_segs) {	/* Should never happen */
4005 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
4006 		return (-EIO);
4007 	}
4008 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4009 		struct page *page = st_bp->reserved_pages[i];
4010 		cnt = length - offset < do_count ? length - offset : do_count;
4011 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4012 		if (res)
4013 			return (-EFAULT);
4014 		do_count -= cnt;
4015 		st_bp->buffer_bytes += cnt;
4016 		ubp += cnt;
4017 		offset = 0;
4018 	}
4019 	if (do_count) /* Should never happen */
4020 		return (-EIO);
4021 
4022 	return 0;
4023 }
4024 
4025 
4026 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4027    negative error code. */
4028 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4029 {
4030 	int i, cnt, res, offset;
4031 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4032 
4033 	for (i = 0, offset = st_bp->read_pointer;
4034 	     i < st_bp->frp_segs && offset >= length; i++)
4035 		offset -= length;
4036 	if (i == st_bp->frp_segs) {	/* Should never happen */
4037 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4038 		return (-EIO);
4039 	}
4040 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4041 		struct page *page = st_bp->reserved_pages[i];
4042 		cnt = length - offset < do_count ? length - offset : do_count;
4043 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4044 		if (res)
4045 			return (-EFAULT);
4046 		do_count -= cnt;
4047 		st_bp->buffer_bytes -= cnt;
4048 		st_bp->read_pointer += cnt;
4049 		ubp += cnt;
4050 		offset = 0;
4051 	}
4052 	if (do_count) /* Should never happen */
4053 		return (-EIO);
4054 
4055 	return 0;
4056 }
4057 
4058 
4059 /* Move data towards start of buffer */
4060 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4061 {
4062 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4063 	int count, total;
4064 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4065 
4066 	if (offset == 0)
4067 		return;
4068 
4069 	total=st_bp->buffer_bytes - offset;
4070 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4071 		src_offset = offset;
4072 		if (src_offset < length)
4073 			break;
4074 		offset -= length;
4075 	}
4076 
4077 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4078 	for (dst_seg=dst_offset=0; total > 0; ) {
4079 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4080 		struct page *spage = st_bp->reserved_pages[src_seg];
4081 
4082 		count = min(length - dst_offset, length - src_offset);
4083 		memmove(page_address(dpage) + dst_offset,
4084 			page_address(spage) + src_offset, count);
4085 		src_offset += count;
4086 		if (src_offset >= length) {
4087 			src_seg++;
4088 			src_offset = 0;
4089 		}
4090 		dst_offset += count;
4091 		if (dst_offset >= length) {
4092 			dst_seg++;
4093 			dst_offset = 0;
4094 		}
4095 		total -= count;
4096 	}
4097 }
4098 
4099 /* Validate the options from command line or module parameters */
4100 static void validate_options(void)
4101 {
4102 	if (buffer_kbs > 0)
4103 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4104 	if (max_sg_segs >= ST_FIRST_SG)
4105 		st_max_sg_segs = max_sg_segs;
4106 }
4107 
4108 #ifndef MODULE
4109 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4110  */
4111 static int __init st_setup(char *str)
4112 {
4113 	int i, len, ints[5];
4114 	char *stp;
4115 
4116 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4117 
4118 	if (ints[0] > 0) {
4119 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4120 			if (parms[i].val)
4121 				*parms[i].val = ints[i + 1];
4122 	} else {
4123 		while (stp != NULL) {
4124 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4125 				len = strlen(parms[i].name);
4126 				if (!strncmp(stp, parms[i].name, len) &&
4127 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4128 					if (parms[i].val)
4129 						*parms[i].val =
4130 							simple_strtoul(stp + len + 1, NULL, 0);
4131 					else
4132 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4133 						       parms[i].name);
4134 					break;
4135 				}
4136 			}
4137 			if (i >= ARRAY_SIZE(parms))
4138 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4139 					stp);
4140 			stp = strchr(stp, ',');
4141 			if (stp)
4142 				stp++;
4143 		}
4144 	}
4145 
4146 	validate_options();
4147 
4148 	return 1;
4149 }
4150 
4151 __setup("st=", st_setup);
4152 
4153 #endif
4154 
4155 static const struct file_operations st_fops =
4156 {
4157 	.owner =	THIS_MODULE,
4158 	.read =		st_read,
4159 	.write =	st_write,
4160 	.unlocked_ioctl = st_ioctl,
4161 #ifdef CONFIG_COMPAT
4162 	.compat_ioctl = st_compat_ioctl,
4163 #endif
4164 	.open =		st_open,
4165 	.flush =	st_flush,
4166 	.release =	st_release,
4167 	.llseek =	noop_llseek,
4168 };
4169 
4170 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4171 {
4172 	int i, error;
4173 	dev_t cdev_devno;
4174 	struct cdev *cdev;
4175 	struct device *dev;
4176 	struct st_modedef *STm = &(tape->modes[mode]);
4177 	char name[10];
4178 	int dev_num = tape->index;
4179 
4180 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4181 
4182 	cdev = cdev_alloc();
4183 	if (!cdev) {
4184 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4185 		error = -ENOMEM;
4186 		goto out;
4187 	}
4188 	cdev->owner = THIS_MODULE;
4189 	cdev->ops = &st_fops;
4190 	STm->cdevs[rew] = cdev;
4191 
4192 	error = cdev_add(cdev, cdev_devno, 1);
4193 	if (error) {
4194 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4195 		       rew ? "non" : "auto", mode);
4196 		pr_err("st%d: Device not attached.\n", dev_num);
4197 		goto out_free;
4198 	}
4199 
4200 	i = mode << (4 - ST_NBR_MODE_BITS);
4201 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4202 		 tape->disk->disk_name, st_formats[i]);
4203 
4204 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4205 			    cdev_devno, &tape->modes[mode], "%s", name);
4206 	if (IS_ERR(dev)) {
4207 		pr_err("st%d: device_create failed\n", dev_num);
4208 		error = PTR_ERR(dev);
4209 		goto out_free;
4210 	}
4211 
4212 	STm->devs[rew] = dev;
4213 
4214 	return 0;
4215 out_free:
4216 	cdev_del(STm->cdevs[rew]);
4217 out:
4218 	STm->cdevs[rew] = NULL;
4219 	STm->devs[rew] = NULL;
4220 	return error;
4221 }
4222 
4223 static int create_cdevs(struct scsi_tape *tape)
4224 {
4225 	int mode, error;
4226 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4227 		error = create_one_cdev(tape, mode, 0);
4228 		if (error)
4229 			return error;
4230 		error = create_one_cdev(tape, mode, 1);
4231 		if (error)
4232 			return error;
4233 	}
4234 
4235 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4236 				 &tape->modes[0].devs[0]->kobj, "tape");
4237 }
4238 
4239 static void remove_cdevs(struct scsi_tape *tape)
4240 {
4241 	int mode, rew;
4242 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4243 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4244 		struct st_modedef *STm = &(tape->modes[mode]);
4245 		for (rew = 0; rew < 2; rew++) {
4246 			if (STm->cdevs[rew])
4247 				cdev_del(STm->cdevs[rew]);
4248 			if (STm->devs[rew])
4249 				device_unregister(STm->devs[rew]);
4250 		}
4251 	}
4252 }
4253 
4254 static int st_probe(struct device *dev)
4255 {
4256 	struct scsi_device *SDp = to_scsi_device(dev);
4257 	struct gendisk *disk = NULL;
4258 	struct scsi_tape *tpnt = NULL;
4259 	struct st_modedef *STm;
4260 	struct st_partstat *STps;
4261 	struct st_buffer *buffer;
4262 	int i, error;
4263 	char *stp;
4264 
4265 	if (SDp->type != TYPE_TAPE)
4266 		return -ENODEV;
4267 	if ((stp = st_incompatible(SDp))) {
4268 		sdev_printk(KERN_INFO, SDp, "Found incompatible tape\n");
4269 		sdev_printk(KERN_INFO, SDp,
4270 			    "st: The suggested driver is %s.\n", stp);
4271 		return -ENODEV;
4272 	}
4273 
4274 	scsi_autopm_get_device(SDp);
4275 	i = queue_max_segments(SDp->request_queue);
4276 	if (st_max_sg_segs < i)
4277 		i = st_max_sg_segs;
4278 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
4279 	if (buffer == NULL) {
4280 		sdev_printk(KERN_ERR, SDp,
4281 			    "st: Can't allocate new tape buffer. "
4282 			    "Device not attached.\n");
4283 		goto out;
4284 	}
4285 
4286 	disk = alloc_disk(1);
4287 	if (!disk) {
4288 		sdev_printk(KERN_ERR, SDp,
4289 			    "st: out of memory. Device not attached.\n");
4290 		goto out_buffer_free;
4291 	}
4292 
4293 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
4294 	if (tpnt == NULL) {
4295 		sdev_printk(KERN_ERR, SDp,
4296 			    "st: Can't allocate device descriptor.\n");
4297 		goto out_put_disk;
4298 	}
4299 	kref_init(&tpnt->kref);
4300 	tpnt->disk = disk;
4301 	disk->private_data = &tpnt->driver;
4302 	/* SCSI tape doesn't register this gendisk via add_disk().  Manually
4303 	 * take queue reference that release_disk() expects. */
4304 	if (!blk_get_queue(SDp->request_queue))
4305 		goto out_put_disk;
4306 	disk->queue = SDp->request_queue;
4307 	tpnt->driver = &st_template;
4308 
4309 	tpnt->device = SDp;
4310 	if (SDp->scsi_level <= 2)
4311 		tpnt->tape_type = MT_ISSCSI1;
4312 	else
4313 		tpnt->tape_type = MT_ISSCSI2;
4314 
4315 	tpnt->buffer = buffer;
4316 	tpnt->buffer->last_SRpnt = NULL;
4317 
4318 	tpnt->inited = 0;
4319 	tpnt->dirty = 0;
4320 	tpnt->in_use = 0;
4321 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4322 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4323 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4324 	tpnt->density = 0;
4325 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4326 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4327 	tpnt->can_partitions = 0;
4328 	tpnt->two_fm = ST_TWO_FM;
4329 	tpnt->fast_mteom = ST_FAST_MTEOM;
4330 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4331 	tpnt->sili = ST_SILI;
4332 	tpnt->immediate = ST_NOWAIT;
4333 	tpnt->immediate_filemark = 0;
4334 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4335 	tpnt->partition = 0;
4336 	tpnt->new_partition = 0;
4337 	tpnt->nbr_partitions = 0;
4338 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4339 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4340 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4341 
4342 	for (i = 0; i < ST_NBR_MODES; i++) {
4343 		STm = &(tpnt->modes[i]);
4344 		STm->defined = 0;
4345 		STm->sysv = ST_SYSV;
4346 		STm->defaults_for_writes = 0;
4347 		STm->do_async_writes = ST_ASYNC_WRITES;
4348 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4349 		STm->do_read_ahead = ST_READ_AHEAD;
4350 		STm->default_compression = ST_DONT_TOUCH;
4351 		STm->default_blksize = (-1);	/* No forced size */
4352 		STm->default_density = (-1);	/* No forced density */
4353 		STm->tape = tpnt;
4354 	}
4355 
4356 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4357 		STps = &(tpnt->ps[i]);
4358 		STps->rw = ST_IDLE;
4359 		STps->eof = ST_NOEOF;
4360 		STps->at_sm = 0;
4361 		STps->last_block_valid = 0;
4362 		STps->drv_block = (-1);
4363 		STps->drv_file = (-1);
4364 	}
4365 
4366 	tpnt->current_mode = 0;
4367 	tpnt->modes[0].defined = 1;
4368 
4369 	tpnt->density_changed = tpnt->compression_changed =
4370 	    tpnt->blksize_changed = 0;
4371 	mutex_init(&tpnt->lock);
4372 
4373 	idr_preload(GFP_KERNEL);
4374 	spin_lock(&st_index_lock);
4375 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4376 	spin_unlock(&st_index_lock);
4377 	idr_preload_end();
4378 	if (error < 0) {
4379 		pr_warn("st: idr allocation failed: %d\n", error);
4380 		goto out_put_queue;
4381 	}
4382 	tpnt->index = error;
4383 	sprintf(disk->disk_name, "st%d", tpnt->index);
4384 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4385 	if (tpnt->stats == NULL) {
4386 		sdev_printk(KERN_ERR, SDp,
4387 			    "st: Can't allocate statistics.\n");
4388 		goto out_idr_remove;
4389 	}
4390 
4391 	dev_set_drvdata(dev, tpnt);
4392 
4393 
4394 	error = create_cdevs(tpnt);
4395 	if (error)
4396 		goto out_remove_devs;
4397 	scsi_autopm_put_device(SDp);
4398 
4399 	sdev_printk(KERN_NOTICE, SDp,
4400 		    "Attached scsi tape %s\n", tape_name(tpnt));
4401 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4402 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4403 		    queue_dma_alignment(SDp->request_queue) + 1);
4404 
4405 	return 0;
4406 
4407 out_remove_devs:
4408 	remove_cdevs(tpnt);
4409 	kfree(tpnt->stats);
4410 out_idr_remove:
4411 	spin_lock(&st_index_lock);
4412 	idr_remove(&st_index_idr, tpnt->index);
4413 	spin_unlock(&st_index_lock);
4414 out_put_queue:
4415 	blk_put_queue(disk->queue);
4416 out_put_disk:
4417 	put_disk(disk);
4418 	kfree(tpnt);
4419 out_buffer_free:
4420 	kfree(buffer);
4421 out:
4422 	scsi_autopm_put_device(SDp);
4423 	return -ENODEV;
4424 };
4425 
4426 
4427 static int st_remove(struct device *dev)
4428 {
4429 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4430 	int index = tpnt->index;
4431 
4432 	scsi_autopm_get_device(to_scsi_device(dev));
4433 	remove_cdevs(tpnt);
4434 
4435 	mutex_lock(&st_ref_mutex);
4436 	kref_put(&tpnt->kref, scsi_tape_release);
4437 	mutex_unlock(&st_ref_mutex);
4438 	spin_lock(&st_index_lock);
4439 	idr_remove(&st_index_idr, index);
4440 	spin_unlock(&st_index_lock);
4441 	return 0;
4442 }
4443 
4444 /**
4445  *      scsi_tape_release - Called to free the Scsi_Tape structure
4446  *      @kref: pointer to embedded kref
4447  *
4448  *      st_ref_mutex must be held entering this routine.  Because it is
4449  *      called on last put, you should always use the scsi_tape_get()
4450  *      scsi_tape_put() helpers which manipulate the semaphore directly
4451  *      and never do a direct kref_put().
4452  **/
4453 static void scsi_tape_release(struct kref *kref)
4454 {
4455 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4456 	struct gendisk *disk = tpnt->disk;
4457 
4458 	tpnt->device = NULL;
4459 
4460 	if (tpnt->buffer) {
4461 		normalize_buffer(tpnt->buffer);
4462 		kfree(tpnt->buffer->reserved_pages);
4463 		kfree(tpnt->buffer);
4464 	}
4465 
4466 	disk->private_data = NULL;
4467 	put_disk(disk);
4468 	kfree(tpnt->stats);
4469 	kfree(tpnt);
4470 	return;
4471 }
4472 
4473 static struct class st_sysfs_class = {
4474 	.name = "scsi_tape",
4475 	.dev_groups = st_dev_groups,
4476 };
4477 
4478 static int __init init_st(void)
4479 {
4480 	int err;
4481 
4482 	validate_options();
4483 
4484 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4485 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4486 
4487 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4488 	if (debugging) {
4489 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4490 			debugging);
4491 	}
4492 
4493 	err = class_register(&st_sysfs_class);
4494 	if (err) {
4495 		pr_err("Unable register sysfs class for SCSI tapes\n");
4496 		return err;
4497 	}
4498 
4499 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4500 				     ST_MAX_TAPE_ENTRIES, "st");
4501 	if (err) {
4502 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4503 		       SCSI_TAPE_MAJOR);
4504 		goto err_class;
4505 	}
4506 
4507 	err = scsi_register_driver(&st_template.gendrv);
4508 	if (err)
4509 		goto err_chrdev;
4510 
4511 	return 0;
4512 
4513 err_chrdev:
4514 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4515 				 ST_MAX_TAPE_ENTRIES);
4516 err_class:
4517 	class_unregister(&st_sysfs_class);
4518 	return err;
4519 }
4520 
4521 static void __exit exit_st(void)
4522 {
4523 	scsi_unregister_driver(&st_template.gendrv);
4524 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4525 				 ST_MAX_TAPE_ENTRIES);
4526 	class_unregister(&st_sysfs_class);
4527 	idr_destroy(&st_index_idr);
4528 	printk(KERN_INFO "st: Unloaded.\n");
4529 }
4530 
4531 module_init(init_st);
4532 module_exit(exit_st);
4533 
4534 
4535 /* The sysfs driver interface. Read-only at the moment */
4536 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4537 {
4538 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4539 }
4540 static DRIVER_ATTR_RO(try_direct_io);
4541 
4542 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4543 {
4544 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4545 }
4546 static DRIVER_ATTR_RO(fixed_buffer_size);
4547 
4548 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4549 {
4550 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4551 }
4552 static DRIVER_ATTR_RO(max_sg_segs);
4553 
4554 static ssize_t version_show(struct device_driver *ddd, char *buf)
4555 {
4556 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4557 }
4558 static DRIVER_ATTR_RO(version);
4559 
4560 #if DEBUG
4561 static ssize_t debug_flag_store(struct device_driver *ddp,
4562 	const char *buf, size_t count)
4563 {
4564 /* We only care what the first byte of the data is the rest is unused.
4565  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4566  * other values have -EINVAL returned if they are passed in.
4567  */
4568 	if (count > 0) {
4569 		if (buf[0] == '0') {
4570 			debugging = NO_DEBUG;
4571 			return count;
4572 		} else if (buf[0] == '1') {
4573 			debugging = 1;
4574 			return count;
4575 		}
4576 	}
4577 	return -EINVAL;
4578 }
4579 
4580 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4581 {
4582 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4583 }
4584 static DRIVER_ATTR_RW(debug_flag);
4585 #endif
4586 
4587 static struct attribute *st_drv_attrs[] = {
4588 	&driver_attr_try_direct_io.attr,
4589 	&driver_attr_fixed_buffer_size.attr,
4590 	&driver_attr_max_sg_segs.attr,
4591 	&driver_attr_version.attr,
4592 #if DEBUG
4593 	&driver_attr_debug_flag.attr,
4594 #endif
4595 	NULL,
4596 };
4597 ATTRIBUTE_GROUPS(st_drv);
4598 
4599 /* The sysfs simple class interface */
4600 static ssize_t
4601 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4602 {
4603 	struct st_modedef *STm = dev_get_drvdata(dev);
4604 	ssize_t l = 0;
4605 
4606 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4607 	return l;
4608 }
4609 static DEVICE_ATTR_RO(defined);
4610 
4611 static ssize_t
4612 default_blksize_show(struct device *dev, struct device_attribute *attr,
4613 		     char *buf)
4614 {
4615 	struct st_modedef *STm = dev_get_drvdata(dev);
4616 	ssize_t l = 0;
4617 
4618 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4619 	return l;
4620 }
4621 static DEVICE_ATTR_RO(default_blksize);
4622 
4623 static ssize_t
4624 default_density_show(struct device *dev, struct device_attribute *attr,
4625 		     char *buf)
4626 {
4627 	struct st_modedef *STm = dev_get_drvdata(dev);
4628 	ssize_t l = 0;
4629 	char *fmt;
4630 
4631 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4632 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4633 	return l;
4634 }
4635 static DEVICE_ATTR_RO(default_density);
4636 
4637 static ssize_t
4638 default_compression_show(struct device *dev, struct device_attribute *attr,
4639 			 char *buf)
4640 {
4641 	struct st_modedef *STm = dev_get_drvdata(dev);
4642 	ssize_t l = 0;
4643 
4644 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4645 	return l;
4646 }
4647 static DEVICE_ATTR_RO(default_compression);
4648 
4649 static ssize_t
4650 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4651 {
4652 	struct st_modedef *STm = dev_get_drvdata(dev);
4653 	struct scsi_tape *STp = STm->tape;
4654 	int options;
4655 	ssize_t l = 0;
4656 
4657 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4658 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4659 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4660 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4661 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4662 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4663 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4664 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4665 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4666 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4667 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4668 	options |= STm->sysv ? MT_ST_SYSV : 0;
4669 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4670 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4671 	options |= STp->sili ? MT_ST_SILI : 0;
4672 
4673 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4674 	return l;
4675 }
4676 static DEVICE_ATTR_RO(options);
4677 
4678 /* Support for tape stats */
4679 
4680 /**
4681  * read_cnt_show - return read count - count of reads made from tape drive
4682  * @dev: struct device
4683  * @attr: attribute structure
4684  * @buf: buffer to return formatted data in
4685  */
4686 static ssize_t read_cnt_show(struct device *dev,
4687 	struct device_attribute *attr, char *buf)
4688 {
4689 	struct st_modedef *STm = dev_get_drvdata(dev);
4690 
4691 	return sprintf(buf, "%lld",
4692 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4693 }
4694 static DEVICE_ATTR_RO(read_cnt);
4695 
4696 /**
4697  * read_byte_cnt_show - return read byte count - tape drives
4698  * may use blocks less than 512 bytes this gives the raw byte count of
4699  * of data read from the tape drive.
4700  * @dev: struct device
4701  * @attr: attribute structure
4702  * @buf: buffer to return formatted data in
4703  */
4704 static ssize_t read_byte_cnt_show(struct device *dev,
4705 	struct device_attribute *attr, char *buf)
4706 {
4707 	struct st_modedef *STm = dev_get_drvdata(dev);
4708 
4709 	return sprintf(buf, "%lld",
4710 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4711 }
4712 static DEVICE_ATTR_RO(read_byte_cnt);
4713 
4714 /**
4715  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4716  * @dev: struct device
4717  * @attr: attribute structure
4718  * @buf: buffer to return formatted data in
4719  */
4720 static ssize_t read_ns_show(struct device *dev,
4721 	struct device_attribute *attr, char *buf)
4722 {
4723 	struct st_modedef *STm = dev_get_drvdata(dev);
4724 
4725 	return sprintf(buf, "%lld",
4726 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4727 }
4728 static DEVICE_ATTR_RO(read_ns);
4729 
4730 /**
4731  * write_cnt_show - write count - number of user calls
4732  * to write(2) that have written data to tape.
4733  * @dev: struct device
4734  * @attr: attribute structure
4735  * @buf: buffer to return formatted data in
4736  */
4737 static ssize_t write_cnt_show(struct device *dev,
4738 	struct device_attribute *attr, char *buf)
4739 {
4740 	struct st_modedef *STm = dev_get_drvdata(dev);
4741 
4742 	return sprintf(buf, "%lld",
4743 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4744 }
4745 static DEVICE_ATTR_RO(write_cnt);
4746 
4747 /**
4748  * write_byte_cnt_show - write byte count - raw count of
4749  * bytes written to tape.
4750  * @dev: struct device
4751  * @attr: attribute structure
4752  * @buf: buffer to return formatted data in
4753  */
4754 static ssize_t write_byte_cnt_show(struct device *dev,
4755 	struct device_attribute *attr, char *buf)
4756 {
4757 	struct st_modedef *STm = dev_get_drvdata(dev);
4758 
4759 	return sprintf(buf, "%lld",
4760 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4761 }
4762 static DEVICE_ATTR_RO(write_byte_cnt);
4763 
4764 /**
4765  * write_ns_show - write ns - number of nanoseconds waiting on write
4766  * requests to complete.
4767  * @dev: struct device
4768  * @attr: attribute structure
4769  * @buf: buffer to return formatted data in
4770  */
4771 static ssize_t write_ns_show(struct device *dev,
4772 	struct device_attribute *attr, char *buf)
4773 {
4774 	struct st_modedef *STm = dev_get_drvdata(dev);
4775 
4776 	return sprintf(buf, "%lld",
4777 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4778 }
4779 static DEVICE_ATTR_RO(write_ns);
4780 
4781 /**
4782  * in_flight_show - number of I/Os currently in flight -
4783  * in most cases this will be either 0 or 1. It may be higher if someone
4784  * has also issued other SCSI commands such as via an ioctl.
4785  * @dev: struct device
4786  * @attr: attribute structure
4787  * @buf: buffer to return formatted data in
4788  */
4789 static ssize_t in_flight_show(struct device *dev,
4790 	struct device_attribute *attr, char *buf)
4791 {
4792 	struct st_modedef *STm = dev_get_drvdata(dev);
4793 
4794 	return sprintf(buf, "%lld",
4795 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4796 }
4797 static DEVICE_ATTR_RO(in_flight);
4798 
4799 /**
4800  * io_ns_show - io wait ns - this is the number of ns spent
4801  * waiting on all I/O to complete. This includes tape movement commands
4802  * such as rewinding, seeking to end of file or tape, it also includes
4803  * read and write. To determine the time spent on tape movement
4804  * subtract the read and write ns from this value.
4805  * @dev: struct device
4806  * @attr: attribute structure
4807  * @buf: buffer to return formatted data in
4808  */
4809 static ssize_t io_ns_show(struct device *dev,
4810 	struct device_attribute *attr, char *buf)
4811 {
4812 	struct st_modedef *STm = dev_get_drvdata(dev);
4813 
4814 	return sprintf(buf, "%lld",
4815 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4816 }
4817 static DEVICE_ATTR_RO(io_ns);
4818 
4819 /**
4820  * other_cnt_show - other io count - this is the number of
4821  * I/O requests other than read and write requests.
4822  * Typically these are tape movement requests but will include driver
4823  * tape movement. This includes only requests issued by the st driver.
4824  * @dev: struct device
4825  * @attr: attribute structure
4826  * @buf: buffer to return formatted data in
4827  */
4828 static ssize_t other_cnt_show(struct device *dev,
4829 	struct device_attribute *attr, char *buf)
4830 {
4831 	struct st_modedef *STm = dev_get_drvdata(dev);
4832 
4833 	return sprintf(buf, "%lld",
4834 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4835 }
4836 static DEVICE_ATTR_RO(other_cnt);
4837 
4838 /**
4839  * resid_cnt_show - A count of the number of times we get a residual
4840  * count - this should indicate someone issuing reads larger than the
4841  * block size on tape.
4842  * @dev: struct device
4843  * @attr: attribute structure
4844  * @buf: buffer to return formatted data in
4845  */
4846 static ssize_t resid_cnt_show(struct device *dev,
4847 	struct device_attribute *attr, char *buf)
4848 {
4849 	struct st_modedef *STm = dev_get_drvdata(dev);
4850 
4851 	return sprintf(buf, "%lld",
4852 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4853 }
4854 static DEVICE_ATTR_RO(resid_cnt);
4855 
4856 static struct attribute *st_dev_attrs[] = {
4857 	&dev_attr_defined.attr,
4858 	&dev_attr_default_blksize.attr,
4859 	&dev_attr_default_density.attr,
4860 	&dev_attr_default_compression.attr,
4861 	&dev_attr_options.attr,
4862 	NULL,
4863 };
4864 
4865 static struct attribute *st_stats_attrs[] = {
4866 	&dev_attr_read_cnt.attr,
4867 	&dev_attr_read_byte_cnt.attr,
4868 	&dev_attr_read_ns.attr,
4869 	&dev_attr_write_cnt.attr,
4870 	&dev_attr_write_byte_cnt.attr,
4871 	&dev_attr_write_ns.attr,
4872 	&dev_attr_in_flight.attr,
4873 	&dev_attr_io_ns.attr,
4874 	&dev_attr_other_cnt.attr,
4875 	&dev_attr_resid_cnt.attr,
4876 	NULL,
4877 };
4878 
4879 static struct attribute_group stats_group = {
4880 	.name = "stats",
4881 	.attrs = st_stats_attrs,
4882 };
4883 
4884 static struct attribute_group st_group = {
4885 	.attrs = st_dev_attrs,
4886 };
4887 
4888 static const struct attribute_group *st_dev_groups[] = {
4889 	&st_group,
4890 	&stats_group,
4891 	NULL,
4892 };
4893 
4894 /* The following functions may be useful for a larger audience. */
4895 static int sgl_map_user_pages(struct st_buffer *STbp,
4896 			      const unsigned int max_pages, unsigned long uaddr,
4897 			      size_t count, int rw)
4898 {
4899 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4900 	unsigned long start = uaddr >> PAGE_SHIFT;
4901 	const int nr_pages = end - start;
4902 	int res, i, j;
4903 	struct page **pages;
4904 	struct rq_map_data *mdata = &STbp->map_data;
4905 
4906 	/* User attempted Overflow! */
4907 	if ((uaddr + count) < uaddr)
4908 		return -EINVAL;
4909 
4910 	/* Too big */
4911         if (nr_pages > max_pages)
4912 		return -ENOMEM;
4913 
4914 	/* Hmm? */
4915 	if (count == 0)
4916 		return 0;
4917 
4918 	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
4919 		return -ENOMEM;
4920 
4921         /* Try to fault in all of the necessary pages */
4922         /* rw==READ means read from drive, write into memory area */
4923 	res = get_user_pages_fast(uaddr, nr_pages, rw == READ, pages);
4924 
4925 	/* Errors and no page mapped should return here */
4926 	if (res < nr_pages)
4927 		goto out_unmap;
4928 
4929         for (i=0; i < nr_pages; i++) {
4930                 /* FIXME: flush superflous for rw==READ,
4931                  * probably wrong function for rw==WRITE
4932                  */
4933 		flush_dcache_page(pages[i]);
4934         }
4935 
4936 	mdata->offset = uaddr & ~PAGE_MASK;
4937 	STbp->mapped_pages = pages;
4938 
4939 	return nr_pages;
4940  out_unmap:
4941 	if (res > 0) {
4942 		for (j=0; j < res; j++)
4943 			put_page(pages[j]);
4944 		res = 0;
4945 	}
4946 	kfree(pages);
4947 	return res;
4948 }
4949 
4950 
4951 /* And unmap them... */
4952 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4953 				const unsigned int nr_pages, int dirtied)
4954 {
4955 	int i;
4956 
4957 	for (i=0; i < nr_pages; i++) {
4958 		struct page *page = STbp->mapped_pages[i];
4959 
4960 		if (dirtied)
4961 			SetPageDirty(page);
4962 		/* FIXME: cache flush missing for rw==READ
4963 		 * FIXME: call the correct reference counting function
4964 		 */
4965 		put_page(page);
4966 	}
4967 	kfree(STbp->mapped_pages);
4968 	STbp->mapped_pages = NULL;
4969 
4970 	return 0;
4971 }
4972