xref: /openbmc/linux/drivers/scsi/st.c (revision 9a6b55ac)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3    SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
4    file Documentation/scsi/st.txt for more information.
5 
6    History:
7    Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
8    Contribution and ideas from several people including (in alphabetical
9    order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
10    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
11    Michael Schaefer, J"org Weule, and Eric Youngdale.
12 
13    Copyright 1992 - 2016 Kai Makisara
14    email Kai.Makisara@kolumbus.fi
15 
16    Some small formal changes - aeb, 950809
17 
18    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
19  */
20 
21 static const char *verstr = "20160209";
22 
23 #include <linux/module.h>
24 
25 #include <linux/compat.h>
26 #include <linux/fs.h>
27 #include <linux/kernel.h>
28 #include <linux/sched/signal.h>
29 #include <linux/mm.h>
30 #include <linux/init.h>
31 #include <linux/string.h>
32 #include <linux/slab.h>
33 #include <linux/errno.h>
34 #include <linux/mtio.h>
35 #include <linux/cdrom.h>
36 #include <linux/ioctl.h>
37 #include <linux/fcntl.h>
38 #include <linux/spinlock.h>
39 #include <linux/blkdev.h>
40 #include <linux/moduleparam.h>
41 #include <linux/cdev.h>
42 #include <linux/idr.h>
43 #include <linux/delay.h>
44 #include <linux/mutex.h>
45 
46 #include <linux/uaccess.h>
47 #include <asm/dma.h>
48 
49 #include <scsi/scsi.h>
50 #include <scsi/scsi_dbg.h>
51 #include <scsi/scsi_device.h>
52 #include <scsi/scsi_driver.h>
53 #include <scsi/scsi_eh.h>
54 #include <scsi/scsi_host.h>
55 #include <scsi/scsi_ioctl.h>
56 #include <scsi/sg.h>
57 
58 
59 /* The driver prints some debugging information on the console if DEBUG
60    is defined and non-zero. */
61 #define DEBUG 1
62 #define NO_DEBUG 0
63 
64 #define ST_DEB_MSG  KERN_NOTICE
65 #if DEBUG
66 /* The message level for the debug messages is currently set to KERN_NOTICE
67    so that people can easily see the messages. Later when the debugging messages
68    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
69 #define DEB(a) a
70 #define DEBC(a) if (debugging) { a ; }
71 #else
72 #define DEB(a)
73 #define DEBC(a)
74 #endif
75 
76 #define ST_KILOBYTE 1024
77 
78 #include "st_options.h"
79 #include "st.h"
80 
81 static int buffer_kbs;
82 static int max_sg_segs;
83 static int try_direct_io = TRY_DIRECT_IO;
84 static int try_rdio = 1;
85 static int try_wdio = 1;
86 static int debug_flag;
87 
88 static struct class st_sysfs_class;
89 static const struct attribute_group *st_dev_groups[];
90 static const struct attribute_group *st_drv_groups[];
91 
92 MODULE_AUTHOR("Kai Makisara");
93 MODULE_DESCRIPTION("SCSI tape (st) driver");
94 MODULE_LICENSE("GPL");
95 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
96 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
97 
98 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
99  * of sysfs parameters (which module_param doesn't yet support).
100  * Sysfs parameters defined explicitly later.
101  */
102 module_param_named(buffer_kbs, buffer_kbs, int, 0);
103 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
104 module_param_named(max_sg_segs, max_sg_segs, int, 0);
105 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
106 module_param_named(try_direct_io, try_direct_io, int, 0);
107 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
108 module_param_named(debug_flag, debug_flag, int, 0);
109 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
110 
111 
112 /* Extra parameters for testing */
113 module_param_named(try_rdio, try_rdio, int, 0);
114 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
115 module_param_named(try_wdio, try_wdio, int, 0);
116 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
117 
118 #ifndef MODULE
119 static int write_threshold_kbs;  /* retained for compatibility */
120 static struct st_dev_parm {
121 	char *name;
122 	int *val;
123 } parms[] __initdata = {
124 	{
125 		"buffer_kbs", &buffer_kbs
126 	},
127 	{       /* Retained for compatibility with 2.4 */
128 		"write_threshold_kbs", &write_threshold_kbs
129 	},
130 	{
131 		"max_sg_segs", NULL
132 	},
133 	{
134 		"try_direct_io", &try_direct_io
135 	},
136 	{
137 		"debug_flag", &debug_flag
138 	}
139 };
140 #endif
141 
142 /* Restrict the number of modes so that names for all are assigned */
143 #if ST_NBR_MODES > 16
144 #error "Maximum number of modes is 16"
145 #endif
146 /* Bit reversed order to get same names for same minors with all
147    mode counts */
148 static const char *st_formats[] = {
149 	"",  "r", "k", "s", "l", "t", "o", "u",
150 	"m", "v", "p", "x", "a", "y", "q", "z"};
151 
152 /* The default definitions have been moved to st_options.h */
153 
154 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
155 
156 /* The buffer size should fit into the 24 bits for length in the
157    6-byte SCSI read and write commands. */
158 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
159 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
160 #endif
161 
162 static int debugging = DEBUG;
163 
164 #define MAX_RETRIES 0
165 #define MAX_WRITE_RETRIES 0
166 #define MAX_READY_RETRIES 0
167 #define NO_TAPE  NOT_READY
168 
169 #define ST_TIMEOUT (900 * HZ)
170 #define ST_LONG_TIMEOUT (14000 * HZ)
171 
172 /* Remove mode bits and auto-rewind bit (7) */
173 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
174 	(iminor(x) & ((1 << ST_MODE_SHIFT)-1)))
175 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
176 
177 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
178 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
179   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
180 
181 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
182    24 bits) */
183 #define SET_DENS_AND_BLK 0x10001
184 
185 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
186 static int st_max_sg_segs = ST_MAX_SG;
187 
188 static int modes_defined;
189 
190 static int enlarge_buffer(struct st_buffer *, int, int);
191 static void clear_buffer(struct st_buffer *);
192 static void normalize_buffer(struct st_buffer *);
193 static int append_to_buffer(const char __user *, struct st_buffer *, int);
194 static int from_buffer(struct st_buffer *, char __user *, int);
195 static void move_buffer_data(struct st_buffer *, int);
196 
197 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
198 			      unsigned long, size_t, int);
199 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
200 
201 static int st_probe(struct device *);
202 static int st_remove(struct device *);
203 
204 static struct scsi_driver st_template = {
205 	.gendrv = {
206 		.name		= "st",
207 		.owner		= THIS_MODULE,
208 		.probe		= st_probe,
209 		.remove		= st_remove,
210 		.groups		= st_drv_groups,
211 	},
212 };
213 
214 static int st_compression(struct scsi_tape *, int);
215 
216 static int find_partition(struct scsi_tape *);
217 static int switch_partition(struct scsi_tape *);
218 
219 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
220 
221 static void scsi_tape_release(struct kref *);
222 
223 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
224 
225 static DEFINE_MUTEX(st_ref_mutex);
226 static DEFINE_SPINLOCK(st_index_lock);
227 static DEFINE_SPINLOCK(st_use_lock);
228 static DEFINE_IDR(st_index_idr);
229 
230 
231 
232 #ifndef SIGS_FROM_OSST
233 #define SIGS_FROM_OSST \
234 	{"OnStream", "SC-", "", "osst"}, \
235 	{"OnStream", "DI-", "", "osst"}, \
236 	{"OnStream", "DP-", "", "osst"}, \
237 	{"OnStream", "USB", "", "osst"}, \
238 	{"OnStream", "FW-", "", "osst"}
239 #endif
240 
241 static struct scsi_tape *scsi_tape_get(int dev)
242 {
243 	struct scsi_tape *STp = NULL;
244 
245 	mutex_lock(&st_ref_mutex);
246 	spin_lock(&st_index_lock);
247 
248 	STp = idr_find(&st_index_idr, dev);
249 	if (!STp) goto out;
250 
251 	kref_get(&STp->kref);
252 
253 	if (!STp->device)
254 		goto out_put;
255 
256 	if (scsi_device_get(STp->device))
257 		goto out_put;
258 
259 	goto out;
260 
261 out_put:
262 	kref_put(&STp->kref, scsi_tape_release);
263 	STp = NULL;
264 out:
265 	spin_unlock(&st_index_lock);
266 	mutex_unlock(&st_ref_mutex);
267 	return STp;
268 }
269 
270 static void scsi_tape_put(struct scsi_tape *STp)
271 {
272 	struct scsi_device *sdev = STp->device;
273 
274 	mutex_lock(&st_ref_mutex);
275 	kref_put(&STp->kref, scsi_tape_release);
276 	scsi_device_put(sdev);
277 	mutex_unlock(&st_ref_mutex);
278 }
279 
280 struct st_reject_data {
281 	char *vendor;
282 	char *model;
283 	char *rev;
284 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
285 };
286 
287 static struct st_reject_data reject_list[] = {
288 	/* {"XXX", "Yy-", "", NULL},  example */
289 	SIGS_FROM_OSST,
290 	{NULL, }};
291 
292 /* If the device signature is on the list of incompatible drives, the
293    function returns a pointer to the name of the correct driver (if known) */
294 static char * st_incompatible(struct scsi_device* SDp)
295 {
296 	struct st_reject_data *rp;
297 
298 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
299 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
300 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
301 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
302 			if (rp->driver_hint)
303 				return rp->driver_hint;
304 			else
305 				return "unknown";
306 		}
307 	return NULL;
308 }
309 
310 
311 static inline char *tape_name(struct scsi_tape *tape)
312 {
313 	return tape->disk->disk_name;
314 }
315 
316 #define st_printk(prefix, t, fmt, a...) \
317 	sdev_prefix_printk(prefix, (t)->device, tape_name(t), fmt, ##a)
318 #ifdef DEBUG
319 #define DEBC_printk(t, fmt, a...) \
320 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
321 #else
322 #define DEBC_printk(t, fmt, a...)
323 #endif
324 
325 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
326 {
327 	const u8 *ucp;
328 	const u8 *sense = SRpnt->sense;
329 
330 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
331 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
332 	s->flags = 0;
333 
334 	if (s->have_sense) {
335 		s->deferred = 0;
336 		s->remainder_valid =
337 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
338 		switch (sense[0] & 0x7f) {
339 		case 0x71:
340 			s->deferred = 1;
341 			/* fall through */
342 		case 0x70:
343 			s->fixed_format = 1;
344 			s->flags = sense[2] & 0xe0;
345 			break;
346 		case 0x73:
347 			s->deferred = 1;
348 			/* fall through */
349 		case 0x72:
350 			s->fixed_format = 0;
351 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
352 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
353 			break;
354 		}
355 	}
356 }
357 
358 
359 /* Convert the result to success code */
360 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
361 {
362 	int result = SRpnt->result;
363 	u8 scode;
364 	DEB(const char *stp;)
365 	char *name = tape_name(STp);
366 	struct st_cmdstatus *cmdstatp;
367 
368 	if (!result)
369 		return 0;
370 
371 	cmdstatp = &STp->buffer->cmdstat;
372 	st_analyze_sense(SRpnt, cmdstatp);
373 
374 	if (cmdstatp->have_sense)
375 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
376 	else
377 		scode = 0;
378 
379 	DEB(
380 	if (debugging) {
381 		st_printk(ST_DEB_MSG, STp,
382 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
383 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
384 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
385 		if (cmdstatp->have_sense)
386 			__scsi_print_sense(STp->device, name,
387 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
388 	} ) /* end DEB */
389 	if (!debugging) { /* Abnormal conditions for tape */
390 		if (!cmdstatp->have_sense)
391 			st_printk(KERN_WARNING, STp,
392 			       "Error %x (driver bt 0x%x, host bt 0x%x).\n",
393 			       result, driver_byte(result), host_byte(result));
394 		else if (cmdstatp->have_sense &&
395 			 scode != NO_SENSE &&
396 			 scode != RECOVERED_ERROR &&
397 			 /* scode != UNIT_ATTENTION && */
398 			 scode != BLANK_CHECK &&
399 			 scode != VOLUME_OVERFLOW &&
400 			 SRpnt->cmd[0] != MODE_SENSE &&
401 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
402 
403 			__scsi_print_sense(STp->device, name,
404 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
405 		}
406 	}
407 
408 	if (cmdstatp->fixed_format &&
409 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
410 		if (STp->cln_sense_value)
411 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
412 					       STp->cln_sense_mask) == STp->cln_sense_value);
413 		else
414 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
415 					       STp->cln_sense_mask) != 0);
416 	}
417 	if (cmdstatp->have_sense &&
418 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
419 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
420 
421 	STp->pos_unknown |= STp->device->was_reset;
422 
423 	if (cmdstatp->have_sense &&
424 	    scode == RECOVERED_ERROR
425 #if ST_RECOVERED_WRITE_FATAL
426 	    && SRpnt->cmd[0] != WRITE_6
427 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
428 #endif
429 	    ) {
430 		STp->recover_count++;
431 		STp->recover_reg++;
432 
433 		DEB(
434 		if (debugging) {
435 			if (SRpnt->cmd[0] == READ_6)
436 				stp = "read";
437 			else if (SRpnt->cmd[0] == WRITE_6)
438 				stp = "write";
439 			else
440 				stp = "ioctl";
441 			st_printk(ST_DEB_MSG, STp,
442 				  "Recovered %s error (%d).\n",
443 				  stp, STp->recover_count);
444 		} ) /* end DEB */
445 
446 		if (cmdstatp->flags == 0)
447 			return 0;
448 	}
449 	return (-EIO);
450 }
451 
452 static struct st_request *st_allocate_request(struct scsi_tape *stp)
453 {
454 	struct st_request *streq;
455 
456 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
457 	if (streq)
458 		streq->stp = stp;
459 	else {
460 		st_printk(KERN_ERR, stp,
461 			  "Can't get SCSI request.\n");
462 		if (signal_pending(current))
463 			stp->buffer->syscall_result = -EINTR;
464 		else
465 			stp->buffer->syscall_result = -EBUSY;
466 	}
467 
468 	return streq;
469 }
470 
471 static void st_release_request(struct st_request *streq)
472 {
473 	kfree(streq);
474 }
475 
476 static void st_do_stats(struct scsi_tape *STp, struct request *req)
477 {
478 	ktime_t now;
479 
480 	now = ktime_get();
481 	if (scsi_req(req)->cmd[0] == WRITE_6) {
482 		now = ktime_sub(now, STp->stats->write_time);
483 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
484 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
485 		atomic64_inc(&STp->stats->write_cnt);
486 		if (scsi_req(req)->result) {
487 			atomic64_add(atomic_read(&STp->stats->last_write_size)
488 				- STp->buffer->cmdstat.residual,
489 				&STp->stats->write_byte_cnt);
490 			if (STp->buffer->cmdstat.residual > 0)
491 				atomic64_inc(&STp->stats->resid_cnt);
492 		} else
493 			atomic64_add(atomic_read(&STp->stats->last_write_size),
494 				&STp->stats->write_byte_cnt);
495 	} else if (scsi_req(req)->cmd[0] == READ_6) {
496 		now = ktime_sub(now, STp->stats->read_time);
497 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
498 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
499 		atomic64_inc(&STp->stats->read_cnt);
500 		if (scsi_req(req)->result) {
501 			atomic64_add(atomic_read(&STp->stats->last_read_size)
502 				- STp->buffer->cmdstat.residual,
503 				&STp->stats->read_byte_cnt);
504 			if (STp->buffer->cmdstat.residual > 0)
505 				atomic64_inc(&STp->stats->resid_cnt);
506 		} else
507 			atomic64_add(atomic_read(&STp->stats->last_read_size),
508 				&STp->stats->read_byte_cnt);
509 	} else {
510 		now = ktime_sub(now, STp->stats->other_time);
511 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
512 		atomic64_inc(&STp->stats->other_cnt);
513 	}
514 	atomic64_dec(&STp->stats->in_flight);
515 }
516 
517 static void st_scsi_execute_end(struct request *req, blk_status_t status)
518 {
519 	struct st_request *SRpnt = req->end_io_data;
520 	struct scsi_request *rq = scsi_req(req);
521 	struct scsi_tape *STp = SRpnt->stp;
522 	struct bio *tmp;
523 
524 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = rq->result;
525 	STp->buffer->cmdstat.residual = rq->resid_len;
526 
527 	st_do_stats(STp, req);
528 
529 	tmp = SRpnt->bio;
530 	if (rq->sense_len)
531 		memcpy(SRpnt->sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
532 	if (SRpnt->waiting)
533 		complete(SRpnt->waiting);
534 
535 	blk_rq_unmap_user(tmp);
536 	blk_put_request(req);
537 }
538 
539 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
540 			   int data_direction, void *buffer, unsigned bufflen,
541 			   int timeout, int retries)
542 {
543 	struct request *req;
544 	struct scsi_request *rq;
545 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
546 	int err = 0;
547 	struct scsi_tape *STp = SRpnt->stp;
548 
549 	req = blk_get_request(SRpnt->stp->device->request_queue,
550 			data_direction == DMA_TO_DEVICE ?
551 			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
552 	if (IS_ERR(req))
553 		return DRIVER_ERROR << 24;
554 	rq = scsi_req(req);
555 	req->rq_flags |= RQF_QUIET;
556 
557 	mdata->null_mapped = 1;
558 
559 	if (bufflen) {
560 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
561 				      GFP_KERNEL);
562 		if (err) {
563 			blk_put_request(req);
564 			return DRIVER_ERROR << 24;
565 		}
566 	}
567 
568 	atomic64_inc(&STp->stats->in_flight);
569 	if (cmd[0] == WRITE_6) {
570 		atomic_set(&STp->stats->last_write_size, bufflen);
571 		STp->stats->write_time = ktime_get();
572 	} else if (cmd[0] == READ_6) {
573 		atomic_set(&STp->stats->last_read_size, bufflen);
574 		STp->stats->read_time = ktime_get();
575 	} else {
576 		STp->stats->other_time = ktime_get();
577 	}
578 
579 	SRpnt->bio = req->bio;
580 	rq->cmd_len = COMMAND_SIZE(cmd[0]);
581 	memset(rq->cmd, 0, BLK_MAX_CDB);
582 	memcpy(rq->cmd, cmd, rq->cmd_len);
583 	req->timeout = timeout;
584 	rq->retries = retries;
585 	req->end_io_data = SRpnt;
586 
587 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
588 	return 0;
589 }
590 
591 /* Do the scsi command. Waits until command performed if do_wait is true.
592    Otherwise write_behind_check() is used to check that the command
593    has finished. */
594 static struct st_request *
595 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
596 	   int bytes, int direction, int timeout, int retries, int do_wait)
597 {
598 	struct completion *waiting;
599 	struct rq_map_data *mdata = &STp->buffer->map_data;
600 	int ret;
601 
602 	/* if async, make sure there's no command outstanding */
603 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
604 		st_printk(KERN_ERR, STp,
605 			  "Async command already active.\n");
606 		if (signal_pending(current))
607 			(STp->buffer)->syscall_result = (-EINTR);
608 		else
609 			(STp->buffer)->syscall_result = (-EBUSY);
610 		return NULL;
611 	}
612 
613 	if (!SRpnt) {
614 		SRpnt = st_allocate_request(STp);
615 		if (!SRpnt)
616 			return NULL;
617 	}
618 
619 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
620 	   which IO is outstanding. It's nulled out when the IO completes. */
621 	if (!do_wait)
622 		(STp->buffer)->last_SRpnt = SRpnt;
623 
624 	waiting = &STp->wait;
625 	init_completion(waiting);
626 	SRpnt->waiting = waiting;
627 
628 	if (STp->buffer->do_dio) {
629 		mdata->page_order = 0;
630 		mdata->nr_entries = STp->buffer->sg_segs;
631 		mdata->pages = STp->buffer->mapped_pages;
632 	} else {
633 		mdata->page_order = STp->buffer->reserved_page_order;
634 		mdata->nr_entries =
635 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
636 		mdata->pages = STp->buffer->reserved_pages;
637 		mdata->offset = 0;
638 	}
639 
640 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
641 	STp->buffer->cmdstat.have_sense = 0;
642 	STp->buffer->syscall_result = 0;
643 
644 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
645 			      retries);
646 	if (ret) {
647 		/* could not allocate the buffer or request was too large */
648 		(STp->buffer)->syscall_result = (-EBUSY);
649 		(STp->buffer)->last_SRpnt = NULL;
650 	} else if (do_wait) {
651 		wait_for_completion(waiting);
652 		SRpnt->waiting = NULL;
653 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
654 	}
655 
656 	return SRpnt;
657 }
658 
659 
660 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
661    write has been correct but EOM early warning reached, -EIO if write ended in
662    error or zero if write successful. Asynchronous writes are used only in
663    variable block mode. */
664 static int write_behind_check(struct scsi_tape * STp)
665 {
666 	int retval = 0;
667 	struct st_buffer *STbuffer;
668 	struct st_partstat *STps;
669 	struct st_cmdstatus *cmdstatp;
670 	struct st_request *SRpnt;
671 
672 	STbuffer = STp->buffer;
673 	if (!STbuffer->writing)
674 		return 0;
675 
676 	DEB(
677 	if (STp->write_pending)
678 		STp->nbr_waits++;
679 	else
680 		STp->nbr_finished++;
681 	) /* end DEB */
682 
683 	wait_for_completion(&(STp->wait));
684 	SRpnt = STbuffer->last_SRpnt;
685 	STbuffer->last_SRpnt = NULL;
686 	SRpnt->waiting = NULL;
687 
688 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
689 	st_release_request(SRpnt);
690 
691 	STbuffer->buffer_bytes -= STbuffer->writing;
692 	STps = &(STp->ps[STp->partition]);
693 	if (STps->drv_block >= 0) {
694 		if (STp->block_size == 0)
695 			STps->drv_block++;
696 		else
697 			STps->drv_block += STbuffer->writing / STp->block_size;
698 	}
699 
700 	cmdstatp = &STbuffer->cmdstat;
701 	if (STbuffer->syscall_result) {
702 		retval = -EIO;
703 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
704 		    (cmdstatp->flags & SENSE_EOM) &&
705 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
706 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
707 			/* EOM at write-behind, has all data been written? */
708 			if (!cmdstatp->remainder_valid ||
709 			    cmdstatp->uremainder64 == 0)
710 				retval = -ENOSPC;
711 		}
712 		if (retval == -EIO)
713 			STps->drv_block = -1;
714 	}
715 	STbuffer->writing = 0;
716 
717 	DEB(if (debugging && retval)
718 		    st_printk(ST_DEB_MSG, STp,
719 				"Async write error %x, return value %d.\n",
720 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
721 
722 	return retval;
723 }
724 
725 
726 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
727    it messes up the block number). */
728 static int cross_eof(struct scsi_tape * STp, int forward)
729 {
730 	struct st_request *SRpnt;
731 	unsigned char cmd[MAX_COMMAND_SIZE];
732 
733 	cmd[0] = SPACE;
734 	cmd[1] = 0x01;		/* Space FileMarks */
735 	if (forward) {
736 		cmd[2] = cmd[3] = 0;
737 		cmd[4] = 1;
738 	} else
739 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
740 	cmd[5] = 0;
741 
742 	DEBC_printk(STp, "Stepping over filemark %s.\n",
743 		    forward ? "forward" : "backward");
744 
745 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
746 			   STp->device->request_queue->rq_timeout,
747 			   MAX_RETRIES, 1);
748 	if (!SRpnt)
749 		return (STp->buffer)->syscall_result;
750 
751 	st_release_request(SRpnt);
752 	SRpnt = NULL;
753 
754 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
755 		st_printk(KERN_ERR, STp,
756 			  "Stepping over filemark %s failed.\n",
757 			  forward ? "forward" : "backward");
758 
759 	return (STp->buffer)->syscall_result;
760 }
761 
762 
763 /* Flush the write buffer (never need to write if variable blocksize). */
764 static int st_flush_write_buffer(struct scsi_tape * STp)
765 {
766 	int transfer, blks;
767 	int result;
768 	unsigned char cmd[MAX_COMMAND_SIZE];
769 	struct st_request *SRpnt;
770 	struct st_partstat *STps;
771 
772 	result = write_behind_check(STp);
773 	if (result)
774 		return result;
775 
776 	result = 0;
777 	if (STp->dirty == 1) {
778 
779 		transfer = STp->buffer->buffer_bytes;
780 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
781 
782 		memset(cmd, 0, MAX_COMMAND_SIZE);
783 		cmd[0] = WRITE_6;
784 		cmd[1] = 1;
785 		blks = transfer / STp->block_size;
786 		cmd[2] = blks >> 16;
787 		cmd[3] = blks >> 8;
788 		cmd[4] = blks;
789 
790 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
791 				   STp->device->request_queue->rq_timeout,
792 				   MAX_WRITE_RETRIES, 1);
793 		if (!SRpnt)
794 			return (STp->buffer)->syscall_result;
795 
796 		STps = &(STp->ps[STp->partition]);
797 		if ((STp->buffer)->syscall_result != 0) {
798 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
799 
800 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
801 			    (cmdstatp->flags & SENSE_EOM) &&
802 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
803 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
804 			    (!cmdstatp->remainder_valid ||
805 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
806 				STp->dirty = 0;
807 				(STp->buffer)->buffer_bytes = 0;
808 				if (STps->drv_block >= 0)
809 					STps->drv_block += blks;
810 				result = (-ENOSPC);
811 			} else {
812 				st_printk(KERN_ERR, STp, "Error on flush.\n");
813 				STps->drv_block = (-1);
814 				result = (-EIO);
815 			}
816 		} else {
817 			if (STps->drv_block >= 0)
818 				STps->drv_block += blks;
819 			STp->dirty = 0;
820 			(STp->buffer)->buffer_bytes = 0;
821 		}
822 		st_release_request(SRpnt);
823 		SRpnt = NULL;
824 	}
825 	return result;
826 }
827 
828 
829 /* Flush the tape buffer. The tape will be positioned correctly unless
830    seek_next is true. */
831 static int flush_buffer(struct scsi_tape *STp, int seek_next)
832 {
833 	int backspace, result;
834 	struct st_partstat *STps;
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 		/* fall through */
2728 	case MTFSF:
2729 		cmd[0] = SPACE;
2730 		cmd[1] = 0x01;	/* Space FileMarks */
2731 		cmd[2] = (arg >> 16);
2732 		cmd[3] = (arg >> 8);
2733 		cmd[4] = arg;
2734 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2735 		if (fileno >= 0)
2736 			fileno += arg;
2737 		blkno = 0;
2738 		at_sm &= (arg == 0);
2739 		break;
2740 	case MTBSFM:
2741 		chg_eof = 0;	/* Changed from the FSF after this */
2742 		/* fall through */
2743 	case MTBSF:
2744 		cmd[0] = SPACE;
2745 		cmd[1] = 0x01;	/* Space FileMarks */
2746 		ltmp = (-arg);
2747 		cmd[2] = (ltmp >> 16);
2748 		cmd[3] = (ltmp >> 8);
2749 		cmd[4] = ltmp;
2750 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2751 		if (fileno >= 0)
2752 			fileno -= arg;
2753 		blkno = (-1);	/* We can't know the block number */
2754 		at_sm &= (arg == 0);
2755 		break;
2756 	case MTFSR:
2757 		cmd[0] = SPACE;
2758 		cmd[1] = 0x00;	/* Space Blocks */
2759 		cmd[2] = (arg >> 16);
2760 		cmd[3] = (arg >> 8);
2761 		cmd[4] = arg;
2762 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2763 		if (blkno >= 0)
2764 			blkno += arg;
2765 		at_sm &= (arg == 0);
2766 		break;
2767 	case MTBSR:
2768 		cmd[0] = SPACE;
2769 		cmd[1] = 0x00;	/* Space Blocks */
2770 		ltmp = (-arg);
2771 		cmd[2] = (ltmp >> 16);
2772 		cmd[3] = (ltmp >> 8);
2773 		cmd[4] = ltmp;
2774 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2775 		if (blkno >= 0)
2776 			blkno -= arg;
2777 		at_sm &= (arg == 0);
2778 		break;
2779 	case MTFSS:
2780 		cmd[0] = SPACE;
2781 		cmd[1] = 0x04;	/* Space Setmarks */
2782 		cmd[2] = (arg >> 16);
2783 		cmd[3] = (arg >> 8);
2784 		cmd[4] = arg;
2785 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2786 		if (arg != 0) {
2787 			blkno = fileno = (-1);
2788 			at_sm = 1;
2789 		}
2790 		break;
2791 	case MTBSS:
2792 		cmd[0] = SPACE;
2793 		cmd[1] = 0x04;	/* Space Setmarks */
2794 		ltmp = (-arg);
2795 		cmd[2] = (ltmp >> 16);
2796 		cmd[3] = (ltmp >> 8);
2797 		cmd[4] = ltmp;
2798 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2799 		if (arg != 0) {
2800 			blkno = fileno = (-1);
2801 			at_sm = 1;
2802 		}
2803 		break;
2804 	case MTWEOF:
2805 	case MTWEOFI:
2806 	case MTWSM:
2807 		if (STp->write_prot)
2808 			return (-EACCES);
2809 		cmd[0] = WRITE_FILEMARKS;
2810 		if (cmd_in == MTWSM)
2811 			cmd[1] = 2;
2812 		if (cmd_in == MTWEOFI ||
2813 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2814 			cmd[1] |= 1;
2815 		cmd[2] = (arg >> 16);
2816 		cmd[3] = (arg >> 8);
2817 		cmd[4] = arg;
2818 		timeout = STp->device->request_queue->rq_timeout;
2819 		DEBC(
2820 			if (cmd_in != MTWSM)
2821 				st_printk(ST_DEB_MSG, STp,
2822 					  "Writing %d filemarks.\n",
2823 					  cmd[2] * 65536 +
2824 					  cmd[3] * 256 +
2825 					  cmd[4]);
2826 			else
2827 				st_printk(ST_DEB_MSG, STp,
2828 					  "Writing %d setmarks.\n",
2829 					  cmd[2] * 65536 +
2830 					  cmd[3] * 256 +
2831 					  cmd[4]);
2832 		)
2833 		if (fileno >= 0)
2834 			fileno += arg;
2835 		blkno = 0;
2836 		at_sm = (cmd_in == MTWSM);
2837 		break;
2838 	case MTREW:
2839 		cmd[0] = REZERO_UNIT;
2840 		if (STp->immediate) {
2841 			cmd[1] = 1;	/* Don't wait for completion */
2842 			timeout = STp->device->request_queue->rq_timeout;
2843 		}
2844 		DEBC_printk(STp, "Rewinding tape.\n");
2845 		fileno = blkno = at_sm = 0;
2846 		break;
2847 	case MTNOP:
2848 		DEBC_printk(STp, "No op on tape.\n");
2849 		return 0;	/* Should do something ? */
2850 		break;
2851 	case MTRETEN:
2852 		cmd[0] = START_STOP;
2853 		if (STp->immediate) {
2854 			cmd[1] = 1;	/* Don't wait for completion */
2855 			timeout = STp->device->request_queue->rq_timeout;
2856 		}
2857 		cmd[4] = 3;
2858 		DEBC_printk(STp, "Retensioning tape.\n");
2859 		fileno = blkno = at_sm = 0;
2860 		break;
2861 	case MTEOM:
2862 		if (!STp->fast_mteom) {
2863 			/* space to the end of tape */
2864 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2865 			fileno = STps->drv_file;
2866 			if (STps->eof >= ST_EOD_1)
2867 				return 0;
2868 			/* The next lines would hide the number of spaced FileMarks
2869 			   That's why I inserted the previous lines. I had no luck
2870 			   with detecting EOM with FSF, so we go now to EOM.
2871 			   Joerg Weule */
2872 		} else
2873 			fileno = (-1);
2874 		cmd[0] = SPACE;
2875 		cmd[1] = 3;
2876 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2877 		blkno = -1;
2878 		at_sm = 0;
2879 		break;
2880 	case MTERASE:
2881 		if (STp->write_prot)
2882 			return (-EACCES);
2883 		cmd[0] = ERASE;
2884 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2885 		if (STp->immediate) {
2886 			cmd[1] |= 2;	/* Don't wait for completion */
2887 			timeout = STp->device->request_queue->rq_timeout;
2888 		}
2889 		else
2890 			timeout = STp->long_timeout * 8;
2891 
2892 		DEBC_printk(STp, "Erasing tape.\n");
2893 		fileno = blkno = at_sm = 0;
2894 		break;
2895 	case MTSETBLK:		/* Set block length */
2896 	case MTSETDENSITY:	/* Set tape density */
2897 	case MTSETDRVBUFFER:	/* Set drive buffering */
2898 	case SET_DENS_AND_BLK:	/* Set density and block size */
2899 		chg_eof = 0;
2900 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2901 			return (-EIO);	/* Not allowed if data in buffer */
2902 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2903 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2904 		    STp->max_block > 0 &&
2905 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2906 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2907 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2908 			return (-EINVAL);
2909 		}
2910 		cmd[0] = MODE_SELECT;
2911 		if ((STp->use_pf & USE_PF))
2912 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2913 		cmd[4] = datalen = 12;
2914 		direction = DMA_TO_DEVICE;
2915 
2916 		memset((STp->buffer)->b_data, 0, 12);
2917 		if (cmd_in == MTSETDRVBUFFER)
2918 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2919 		else
2920 			(STp->buffer)->b_data[2] =
2921 			    STp->drv_buffer << 4;
2922 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2923 		if (cmd_in == MTSETDENSITY) {
2924 			(STp->buffer)->b_data[4] = arg;
2925 			STp->density_changed = 1;	/* At least we tried ;-) */
2926 		} else if (cmd_in == SET_DENS_AND_BLK)
2927 			(STp->buffer)->b_data[4] = arg >> 24;
2928 		else
2929 			(STp->buffer)->b_data[4] = STp->density;
2930 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2931 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2932 			if (cmd_in == MTSETBLK)
2933 				STp->blksize_changed = 1; /* At least we tried ;-) */
2934 		} else
2935 			ltmp = STp->block_size;
2936 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2937 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2938 		(STp->buffer)->b_data[11] = ltmp;
2939 		timeout = STp->device->request_queue->rq_timeout;
2940 		DEBC(
2941 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2942 				st_printk(ST_DEB_MSG, STp,
2943 					  "Setting block size to %d bytes.\n",
2944 					  (STp->buffer)->b_data[9] * 65536 +
2945 					  (STp->buffer)->b_data[10] * 256 +
2946 					  (STp->buffer)->b_data[11]);
2947 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2948 				st_printk(ST_DEB_MSG, STp,
2949 					  "Setting density code to %x.\n",
2950 					  (STp->buffer)->b_data[4]);
2951 			if (cmd_in == MTSETDRVBUFFER)
2952 				st_printk(ST_DEB_MSG, STp,
2953 					  "Setting drive buffer code to %d.\n",
2954 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2955 		)
2956 		break;
2957 	default:
2958 		return (-ENOSYS);
2959 	}
2960 
2961 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2962 			   timeout, MAX_RETRIES, 1);
2963 	if (!SRpnt)
2964 		return (STp->buffer)->syscall_result;
2965 
2966 	ioctl_result = (STp->buffer)->syscall_result;
2967 
2968 	if (!ioctl_result) {	/* SCSI command successful */
2969 		st_release_request(SRpnt);
2970 		SRpnt = NULL;
2971 		STps->drv_block = blkno;
2972 		STps->drv_file = fileno;
2973 		STps->at_sm = at_sm;
2974 
2975 		if (cmd_in == MTBSFM)
2976 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2977 		else if (cmd_in == MTFSFM)
2978 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2979 
2980 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2981 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2982 			if (STp->block_size != 0) {
2983 				(STp->buffer)->buffer_blocks =
2984 				    (STp->buffer)->buffer_size / STp->block_size;
2985 			}
2986 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2987 			if (cmd_in == SET_DENS_AND_BLK)
2988 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2989 		} else if (cmd_in == MTSETDRVBUFFER)
2990 			STp->drv_buffer = (arg & 7);
2991 		else if (cmd_in == MTSETDENSITY)
2992 			STp->density = arg;
2993 
2994 		if (cmd_in == MTEOM)
2995 			STps->eof = ST_EOD;
2996 		else if (cmd_in == MTFSF)
2997 			STps->eof = ST_FM;
2998 		else if (chg_eof)
2999 			STps->eof = ST_NOEOF;
3000 
3001 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
3002 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
3003 	} else { /* SCSI command was not completely successful. Don't return
3004                     from this block without releasing the SCSI command block! */
3005 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
3006 
3007 		if (cmdstatp->flags & SENSE_EOM) {
3008 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3009 			    cmd_in != MTBSR && cmd_in != MTBSS)
3010 				STps->eof = ST_EOM_OK;
3011 			STps->drv_block = 0;
3012 		}
3013 
3014 		if (cmdstatp->remainder_valid)
3015 			undone = (int)cmdstatp->uremainder64;
3016 		else
3017 			undone = 0;
3018 
3019 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3020 		    cmdstatp->have_sense &&
3021 		    (cmdstatp->flags & SENSE_EOM)) {
3022 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3023 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3024 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3025 				STps->eof = ST_NOEOF;
3026 			} else {  /* Writing EOF(s) failed */
3027 				if (fileno >= 0)
3028 					fileno -= undone;
3029 				if (undone < arg)
3030 					STps->eof = ST_NOEOF;
3031 			}
3032 			STps->drv_file = fileno;
3033 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3034 			if (fileno >= 0)
3035 				STps->drv_file = fileno - undone;
3036 			else
3037 				STps->drv_file = fileno;
3038 			STps->drv_block = -1;
3039 			STps->eof = ST_NOEOF;
3040 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3041 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3042 				undone = (-undone);
3043 			if (STps->drv_file >= 0)
3044 				STps->drv_file = fileno + undone;
3045 			STps->drv_block = 0;
3046 			STps->eof = ST_NOEOF;
3047 		} else if (cmd_in == MTFSR) {
3048 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3049 				if (STps->drv_file >= 0)
3050 					STps->drv_file++;
3051 				STps->drv_block = 0;
3052 				STps->eof = ST_FM;
3053 			} else {
3054 				if (blkno >= undone)
3055 					STps->drv_block = blkno - undone;
3056 				else
3057 					STps->drv_block = (-1);
3058 				STps->eof = ST_NOEOF;
3059 			}
3060 		} else if (cmd_in == MTBSR) {
3061 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3062 				STps->drv_file--;
3063 				STps->drv_block = (-1);
3064 			} else {
3065 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3066 					undone = (-undone);
3067 				if (STps->drv_block >= 0)
3068 					STps->drv_block = blkno + undone;
3069 			}
3070 			STps->eof = ST_NOEOF;
3071 		} else if (cmd_in == MTEOM) {
3072 			STps->drv_file = (-1);
3073 			STps->drv_block = (-1);
3074 			STps->eof = ST_EOD;
3075 		} else if (cmd_in == MTSETBLK ||
3076 			   cmd_in == MTSETDENSITY ||
3077 			   cmd_in == MTSETDRVBUFFER ||
3078 			   cmd_in == SET_DENS_AND_BLK) {
3079 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3080 			    !(STp->use_pf & PF_TESTED)) {
3081 				/* Try the other possible state of Page Format if not
3082 				   already tried */
3083 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3084 				st_release_request(SRpnt);
3085 				SRpnt = NULL;
3086 				return st_int_ioctl(STp, cmd_in, arg);
3087 			}
3088 		} else if (chg_eof)
3089 			STps->eof = ST_NOEOF;
3090 
3091 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3092 			STps->eof = ST_EOD;
3093 
3094 		st_release_request(SRpnt);
3095 		SRpnt = NULL;
3096 	}
3097 
3098 	return ioctl_result;
3099 }
3100 
3101 
3102 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3103    structure. */
3104 
3105 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3106 			int logical)
3107 {
3108 	int result;
3109 	unsigned char scmd[MAX_COMMAND_SIZE];
3110 	struct st_request *SRpnt;
3111 
3112 	if (STp->ready != ST_READY)
3113 		return (-EIO);
3114 
3115 	memset(scmd, 0, MAX_COMMAND_SIZE);
3116 	if ((STp->device)->scsi_level < SCSI_2) {
3117 		scmd[0] = QFA_REQUEST_BLOCK;
3118 		scmd[4] = 3;
3119 	} else {
3120 		scmd[0] = READ_POSITION;
3121 		if (!logical && !STp->scsi2_logical)
3122 			scmd[1] = 1;
3123 	}
3124 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3125 			   STp->device->request_queue->rq_timeout,
3126 			   MAX_READY_RETRIES, 1);
3127 	if (!SRpnt)
3128 		return (STp->buffer)->syscall_result;
3129 
3130 	if ((STp->buffer)->syscall_result != 0 ||
3131 	    (STp->device->scsi_level >= SCSI_2 &&
3132 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3133 		*block = *partition = 0;
3134 		DEBC_printk(STp, " Can't read tape position.\n");
3135 		result = (-EIO);
3136 	} else {
3137 		result = 0;
3138 		if ((STp->device)->scsi_level < SCSI_2) {
3139 			*block = ((STp->buffer)->b_data[0] << 16)
3140 			    + ((STp->buffer)->b_data[1] << 8)
3141 			    + (STp->buffer)->b_data[2];
3142 			*partition = 0;
3143 		} else {
3144 			*block = ((STp->buffer)->b_data[4] << 24)
3145 			    + ((STp->buffer)->b_data[5] << 16)
3146 			    + ((STp->buffer)->b_data[6] << 8)
3147 			    + (STp->buffer)->b_data[7];
3148 			*partition = (STp->buffer)->b_data[1];
3149 			if (((STp->buffer)->b_data[0] & 0x80) &&
3150 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3151 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3152 		}
3153 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3154 			    *block, *partition);
3155 	}
3156 	st_release_request(SRpnt);
3157 	SRpnt = NULL;
3158 
3159 	return result;
3160 }
3161 
3162 
3163 /* Set the tape block and partition. Negative partition means that only the
3164    block should be set in vendor specific way. */
3165 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3166 			int logical)
3167 {
3168 	struct st_partstat *STps;
3169 	int result, p;
3170 	unsigned int blk;
3171 	int timeout;
3172 	unsigned char scmd[MAX_COMMAND_SIZE];
3173 	struct st_request *SRpnt;
3174 
3175 	if (STp->ready != ST_READY)
3176 		return (-EIO);
3177 	timeout = STp->long_timeout;
3178 	STps = &(STp->ps[STp->partition]);
3179 
3180 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3181 		    block, partition);
3182 	DEB(if (partition < 0)
3183 		return (-EIO); )
3184 
3185 	/* Update the location at the partition we are leaving */
3186 	if ((!STp->can_partitions && partition != 0) ||
3187 	    partition >= ST_NBR_PARTITIONS)
3188 		return (-EINVAL);
3189 	if (partition != STp->partition) {
3190 		if (get_location(STp, &blk, &p, 1))
3191 			STps->last_block_valid = 0;
3192 		else {
3193 			STps->last_block_valid = 1;
3194 			STps->last_block_visited = blk;
3195 			DEBC_printk(STp, "Visited block %d for "
3196 				    "partition %d saved.\n",
3197 				    blk, STp->partition);
3198 		}
3199 	}
3200 
3201 	memset(scmd, 0, MAX_COMMAND_SIZE);
3202 	if ((STp->device)->scsi_level < SCSI_2) {
3203 		scmd[0] = QFA_SEEK_BLOCK;
3204 		scmd[2] = (block >> 16);
3205 		scmd[3] = (block >> 8);
3206 		scmd[4] = block;
3207 		scmd[5] = 0;
3208 	} else {
3209 		scmd[0] = SEEK_10;
3210 		scmd[3] = (block >> 24);
3211 		scmd[4] = (block >> 16);
3212 		scmd[5] = (block >> 8);
3213 		scmd[6] = block;
3214 		if (!logical && !STp->scsi2_logical)
3215 			scmd[1] = 4;
3216 		if (STp->partition != partition) {
3217 			scmd[1] |= 2;
3218 			scmd[8] = partition;
3219 			DEBC_printk(STp, "Trying to change partition "
3220 				    "from %d to %d\n", STp->partition,
3221 				    partition);
3222 		}
3223 	}
3224 	if (STp->immediate) {
3225 		scmd[1] |= 1;		/* Don't wait for completion */
3226 		timeout = STp->device->request_queue->rq_timeout;
3227 	}
3228 
3229 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3230 			   timeout, MAX_READY_RETRIES, 1);
3231 	if (!SRpnt)
3232 		return (STp->buffer)->syscall_result;
3233 
3234 	STps->drv_block = STps->drv_file = (-1);
3235 	STps->eof = ST_NOEOF;
3236 	if ((STp->buffer)->syscall_result != 0) {
3237 		result = (-EIO);
3238 		if (STp->can_partitions &&
3239 		    (STp->device)->scsi_level >= SCSI_2 &&
3240 		    (p = find_partition(STp)) >= 0)
3241 			STp->partition = p;
3242 	} else {
3243 		if (STp->can_partitions) {
3244 			STp->partition = partition;
3245 			STps = &(STp->ps[partition]);
3246 			if (!STps->last_block_valid ||
3247 			    STps->last_block_visited != block) {
3248 				STps->at_sm = 0;
3249 				STps->rw = ST_IDLE;
3250 			}
3251 		} else
3252 			STps->at_sm = 0;
3253 		if (block == 0)
3254 			STps->drv_block = STps->drv_file = 0;
3255 		result = 0;
3256 	}
3257 
3258 	st_release_request(SRpnt);
3259 	SRpnt = NULL;
3260 
3261 	return result;
3262 }
3263 
3264 
3265 /* Find the current partition number for the drive status. Called from open and
3266    returns either partition number of negative error code. */
3267 static int find_partition(struct scsi_tape *STp)
3268 {
3269 	int i, partition;
3270 	unsigned int block;
3271 
3272 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3273 		return i;
3274 	if (partition >= ST_NBR_PARTITIONS)
3275 		return (-EIO);
3276 	return partition;
3277 }
3278 
3279 
3280 /* Change the partition if necessary */
3281 static int switch_partition(struct scsi_tape *STp)
3282 {
3283 	struct st_partstat *STps;
3284 
3285 	if (STp->partition == STp->new_partition)
3286 		return 0;
3287 	STps = &(STp->ps[STp->new_partition]);
3288 	if (!STps->last_block_valid)
3289 		STps->last_block_visited = 0;
3290 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3291 }
3292 
3293 /* Functions for reading and writing the medium partition mode page. */
3294 
3295 #define PART_PAGE   0x11
3296 #define PART_PAGE_FIXED_LENGTH 8
3297 
3298 #define PP_OFF_MAX_ADD_PARTS   2
3299 #define PP_OFF_NBR_ADD_PARTS   3
3300 #define PP_OFF_FLAGS           4
3301 #define PP_OFF_PART_UNITS      6
3302 #define PP_OFF_RESERVED        7
3303 
3304 #define PP_BIT_IDP             0x20
3305 #define PP_BIT_FDP             0x80
3306 #define PP_MSK_PSUM_MB         0x10
3307 #define PP_MSK_PSUM_UNITS      0x18
3308 #define PP_MSK_POFM            0x04
3309 
3310 /* Get the number of partitions on the tape. As a side effect reads the
3311    mode page into the tape buffer. */
3312 static int nbr_partitions(struct scsi_tape *STp)
3313 {
3314 	int result;
3315 
3316 	if (STp->ready != ST_READY)
3317 		return (-EIO);
3318 
3319 	result = read_mode_page(STp, PART_PAGE, 1);
3320 
3321 	if (result) {
3322 		DEBC_printk(STp, "Can't read medium partition page.\n");
3323 		result = (-EIO);
3324 	} else {
3325 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3326 					      PP_OFF_NBR_ADD_PARTS] + 1;
3327 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3328 	}
3329 
3330 	return result;
3331 }
3332 
3333 
3334 static int format_medium(struct scsi_tape *STp, int format)
3335 {
3336 	int result = 0;
3337 	int timeout = STp->long_timeout;
3338 	unsigned char scmd[MAX_COMMAND_SIZE];
3339 	struct st_request *SRpnt;
3340 
3341 	memset(scmd, 0, MAX_COMMAND_SIZE);
3342 	scmd[0] = FORMAT_UNIT;
3343 	scmd[2] = format;
3344 	if (STp->immediate) {
3345 		scmd[1] |= 1;		/* Don't wait for completion */
3346 		timeout = STp->device->request_queue->rq_timeout;
3347 	}
3348 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3349 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3350 			   timeout, MAX_RETRIES, 1);
3351 	if (!SRpnt)
3352 		result = STp->buffer->syscall_result;
3353 	return result;
3354 }
3355 
3356 
3357 /* Partition the tape into two partitions if size > 0 or one partition if
3358    size == 0.
3359 
3360    The block descriptors are read and written because Sony SDT-7000 does not
3361    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3362 
3363    My HP C1533A drive returns only one partition size field. This is used to
3364    set the size of partition 1. There is no size field for the default partition.
3365    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3366    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3367    The following algorithm is used to accommodate both drives: if the number of
3368    partition size fields is greater than the maximum number of additional partitions
3369    in the mode page, the second field is used. Otherwise the first field is used.
3370 
3371    For Seagate DDS drives the page length must be 8 when no partitions is defined
3372    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3373    is acceptable also to some other old drives and enforced if the first partition
3374    size field is used for the first additional partition size.
3375 
3376    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3377  */
3378 static int partition_tape(struct scsi_tape *STp, int size)
3379 {
3380 	int result;
3381 	int target_partition;
3382 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3383 	int pgo, psd_cnt, psdo;
3384 	int psum = PP_MSK_PSUM_MB, units = 0;
3385 	unsigned char *bp;
3386 
3387 	result = read_mode_page(STp, PART_PAGE, 0);
3388 	if (result) {
3389 		DEBC_printk(STp, "Can't read partition mode page.\n");
3390 		return result;
3391 	}
3392 	target_partition = 1;
3393 	if (size < 0) {
3394 		target_partition = 0;
3395 		size = -size;
3396 	}
3397 
3398 	/* The mode page is in the buffer. Let's modify it and write it. */
3399 	bp = (STp->buffer)->b_data;
3400 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3401 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3402 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3403 
3404 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3405 
3406 	if (scsi3) {
3407 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3408 		if (needs_format && size == 0) {
3409 			/* No need to write the mode page when clearing
3410 			 *  partitioning
3411 			 */
3412 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3413 			result = format_medium(STp, 0);
3414 			goto out;
3415 		}
3416 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3417 			psd_cnt = 2;
3418 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3419 			/* Use units scaling for large partitions if the device
3420 			 * suggests it and no precision lost. Required for IBM
3421 			 * TS1140/50 drives that don't support MB units.
3422 			 */
3423 			if (size >= 1000 && (size % 1000) == 0) {
3424 				size /= 1000;
3425 				psum = PP_MSK_PSUM_UNITS;
3426 				units = 9; /* GB */
3427 			}
3428 		}
3429 		/* Try it anyway if too large to specify in MB */
3430 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3431 			size /= 1000;
3432 			psum = PP_MSK_PSUM_UNITS;
3433 			units = 9;  /* GB */
3434 		}
3435 	}
3436 
3437 	if (size >= 65535 ||  /* Does not fit into two bytes */
3438 	    (target_partition == 0 && psd_cnt < 2)) {
3439 		result = -EINVAL;
3440 		goto out;
3441 	}
3442 
3443 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3444 	/* The second condition is for HP DDS which use only one partition size
3445 	 * descriptor
3446 	 */
3447 	if (target_partition > 0 &&
3448 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3449 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3450 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3451 		psdo += 2;
3452 	}
3453 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3454 
3455 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3456 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3457 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3458 
3459 	if (size == 0) {
3460 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3461 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3462 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3463 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3464 	} else {
3465 		bp[psdo] = (size >> 8) & 0xff;
3466 		bp[psdo + 1] = size & 0xff;
3467 		if (target_partition == 0)
3468 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3469 		bp[pgo + 3] = 1;
3470 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3471 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3472 		DEBC_printk(STp,
3473 			    "Formatting tape with two partitions (%i = %d MB).\n",
3474 			    target_partition, units > 0 ? size * 1000 : size);
3475 	}
3476 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3477 	bp[pgo + PP_OFF_RESERVED] = 0;
3478 	if (size != 1 || units != 0) {
3479 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3480 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3481 		bp[pgo + PP_OFF_PART_UNITS] = units;
3482 	} else
3483 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3484 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3485 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3486 
3487 	result = write_mode_page(STp, PART_PAGE, 1);
3488 
3489 	if (!result && needs_format)
3490 		result = format_medium(STp, 1);
3491 
3492 	if (result) {
3493 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3494 		result = (-EIO);
3495 	}
3496 
3497 out:
3498 	return result;
3499 }
3500 
3501 
3502 
3503 /* The ioctl command */
3504 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3505 {
3506 	int i, cmd_nr, cmd_type, bt;
3507 	int retval = 0;
3508 	unsigned int blk;
3509 	struct scsi_tape *STp = file->private_data;
3510 	struct st_modedef *STm;
3511 	struct st_partstat *STps;
3512 	void __user *p = (void __user *)arg;
3513 
3514 	if (mutex_lock_interruptible(&STp->lock))
3515 		return -ERESTARTSYS;
3516 
3517 	DEB(
3518 	if (debugging && !STp->in_use) {
3519 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3520 		retval = (-EIO);
3521 		goto out;
3522 	} ) /* end DEB */
3523 
3524 	STm = &(STp->modes[STp->current_mode]);
3525 	STps = &(STp->ps[STp->partition]);
3526 
3527 	/*
3528 	 * If we are in the middle of error recovery, don't let anyone
3529 	 * else try and use this device.  Also, if error recovery fails, it
3530 	 * may try and take the device offline, in which case all further
3531 	 * access to the device is prohibited.
3532 	 */
3533 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3534 			file->f_flags & O_NDELAY);
3535 	if (retval)
3536 		goto out;
3537 
3538 	cmd_type = _IOC_TYPE(cmd_in);
3539 	cmd_nr = _IOC_NR(cmd_in);
3540 
3541 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3542 		struct mtop mtc;
3543 
3544 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3545 			retval = (-EINVAL);
3546 			goto out;
3547 		}
3548 
3549 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3550 		if (i) {
3551 			retval = (-EFAULT);
3552 			goto out;
3553 		}
3554 
3555 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3556 			st_printk(KERN_WARNING, STp,
3557 				  "MTSETDRVBUFFER only allowed for root.\n");
3558 			retval = (-EPERM);
3559 			goto out;
3560 		}
3561 		if (!STm->defined &&
3562 		    (mtc.mt_op != MTSETDRVBUFFER &&
3563 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3564 			retval = (-ENXIO);
3565 			goto out;
3566 		}
3567 
3568 		if (!STp->pos_unknown) {
3569 
3570 			if (STps->eof == ST_FM_HIT) {
3571 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3572                                     mtc.mt_op == MTEOM) {
3573 					mtc.mt_count -= 1;
3574 					if (STps->drv_file >= 0)
3575 						STps->drv_file += 1;
3576 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3577 					mtc.mt_count += 1;
3578 					if (STps->drv_file >= 0)
3579 						STps->drv_file += 1;
3580 				}
3581 			}
3582 
3583 			if (mtc.mt_op == MTSEEK) {
3584 				/* Old position must be restored if partition will be
3585                                    changed */
3586 				i = !STp->can_partitions ||
3587 				    (STp->new_partition != STp->partition);
3588 			} else {
3589 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3590 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3591 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3592 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3593 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3594 				    mtc.mt_op == MTCOMPRESSION;
3595 			}
3596 			i = flush_buffer(STp, i);
3597 			if (i < 0) {
3598 				retval = i;
3599 				goto out;
3600 			}
3601 			if (STps->rw == ST_WRITING &&
3602 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3603 			     mtc.mt_op == MTSEEK ||
3604 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3605 				i = st_int_ioctl(STp, MTWEOF, 1);
3606 				if (i < 0) {
3607 					retval = i;
3608 					goto out;
3609 				}
3610 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3611 					mtc.mt_count++;
3612 				STps->rw = ST_IDLE;
3613 			     }
3614 
3615 		} else {
3616 			/*
3617 			 * If there was a bus reset, block further access
3618 			 * to this device.  If the user wants to rewind the tape,
3619 			 * then reset the flag and allow access again.
3620 			 */
3621 			if (mtc.mt_op != MTREW &&
3622 			    mtc.mt_op != MTOFFL &&
3623 			    mtc.mt_op != MTRETEN &&
3624 			    mtc.mt_op != MTERASE &&
3625 			    mtc.mt_op != MTSEEK &&
3626 			    mtc.mt_op != MTEOM) {
3627 				retval = (-EIO);
3628 				goto out;
3629 			}
3630 			reset_state(STp);
3631 			/* remove this when the midlevel properly clears was_reset */
3632 			STp->device->was_reset = 0;
3633 		}
3634 
3635 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3636 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3637 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3638 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3639 
3640 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3641 			do_door_lock(STp, 0);	/* Ignore result! */
3642 
3643 		if (mtc.mt_op == MTSETDRVBUFFER &&
3644 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3645 			retval = st_set_options(STp, mtc.mt_count);
3646 			goto out;
3647 		}
3648 
3649 		if (mtc.mt_op == MTSETPART) {
3650 			if (!STp->can_partitions ||
3651 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3652 				retval = (-EINVAL);
3653 				goto out;
3654 			}
3655 			if (mtc.mt_count >= STp->nbr_partitions &&
3656 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3657 				retval = (-EIO);
3658 				goto out;
3659 			}
3660 			if (mtc.mt_count >= STp->nbr_partitions) {
3661 				retval = (-EINVAL);
3662 				goto out;
3663 			}
3664 			STp->new_partition = mtc.mt_count;
3665 			retval = 0;
3666 			goto out;
3667 		}
3668 
3669 		if (mtc.mt_op == MTMKPART) {
3670 			if (!STp->can_partitions) {
3671 				retval = (-EINVAL);
3672 				goto out;
3673 			}
3674 			i = do_load_unload(STp, file, 1);
3675 			if (i < 0) {
3676 				retval = i;
3677 				goto out;
3678 			}
3679 			i = partition_tape(STp, mtc.mt_count);
3680 			if (i < 0) {
3681 				retval = i;
3682 				goto out;
3683 			}
3684 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3685 				STp->ps[i].rw = ST_IDLE;
3686 				STp->ps[i].at_sm = 0;
3687 				STp->ps[i].last_block_valid = 0;
3688 			}
3689 			STp->partition = STp->new_partition = 0;
3690 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3691 			STps->drv_block = STps->drv_file = 0;
3692 			retval = 0;
3693 			goto out;
3694 		}
3695 
3696 		if (mtc.mt_op == MTSEEK) {
3697 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3698 			if (!STp->can_partitions)
3699 				STp->ps[0].rw = ST_IDLE;
3700 			retval = i;
3701 			goto out;
3702 		}
3703 
3704 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3705 			retval = do_load_unload(STp, file, 0);
3706 			goto out;
3707 		}
3708 
3709 		if (mtc.mt_op == MTLOAD) {
3710 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3711 			goto out;
3712 		}
3713 
3714 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3715 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3716 			goto out;
3717 		}
3718 
3719 		if (STp->can_partitions && STp->ready == ST_READY &&
3720 		    (i = switch_partition(STp)) < 0) {
3721 			retval = i;
3722 			goto out;
3723 		}
3724 
3725 		if (mtc.mt_op == MTCOMPRESSION)
3726 			retval = st_compression(STp, (mtc.mt_count & 1));
3727 		else
3728 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3729 		goto out;
3730 	}
3731 	if (!STm->defined) {
3732 		retval = (-ENXIO);
3733 		goto out;
3734 	}
3735 
3736 	if ((i = flush_buffer(STp, 0)) < 0) {
3737 		retval = i;
3738 		goto out;
3739 	}
3740 	if (STp->can_partitions &&
3741 	    (i = switch_partition(STp)) < 0) {
3742 		retval = i;
3743 		goto out;
3744 	}
3745 
3746 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3747 		struct mtget mt_status;
3748 
3749 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3750 			 retval = (-EINVAL);
3751 			 goto out;
3752 		}
3753 
3754 		mt_status.mt_type = STp->tape_type;
3755 		mt_status.mt_dsreg =
3756 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3757 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3758 		mt_status.mt_blkno = STps->drv_block;
3759 		mt_status.mt_fileno = STps->drv_file;
3760 		if (STp->block_size != 0) {
3761 			if (STps->rw == ST_WRITING)
3762 				mt_status.mt_blkno +=
3763 				    (STp->buffer)->buffer_bytes / STp->block_size;
3764 			else if (STps->rw == ST_READING)
3765 				mt_status.mt_blkno -=
3766                                         ((STp->buffer)->buffer_bytes +
3767                                          STp->block_size - 1) / STp->block_size;
3768 		}
3769 
3770 		mt_status.mt_gstat = 0;
3771 		if (STp->drv_write_prot)
3772 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3773 		if (mt_status.mt_blkno == 0) {
3774 			if (mt_status.mt_fileno == 0)
3775 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3776 			else
3777 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3778 		}
3779 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3780 		mt_status.mt_resid = STp->partition;
3781 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3782 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3783 		else if (STps->eof >= ST_EOM_OK)
3784 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3785 		if (STp->density == 1)
3786 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3787 		else if (STp->density == 2)
3788 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3789 		else if (STp->density == 3)
3790 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3791 		if (STp->ready == ST_READY)
3792 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3793 		if (STp->ready == ST_NO_TAPE)
3794 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3795 		if (STps->at_sm)
3796 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3797 		if (STm->do_async_writes ||
3798                     (STm->do_buffer_writes && STp->block_size != 0) ||
3799 		    STp->drv_buffer != 0)
3800 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3801 		if (STp->cleaning_req)
3802 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3803 
3804 		retval = put_user_mtget(p, &mt_status);
3805 		if (retval)
3806 			goto out;
3807 
3808 		STp->recover_reg = 0;		/* Clear after read */
3809 		goto out;
3810 	}			/* End of MTIOCGET */
3811 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3812 		struct mtpos mt_pos;
3813 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3814 			 retval = (-EINVAL);
3815 			 goto out;
3816 		}
3817 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3818 			retval = i;
3819 			goto out;
3820 		}
3821 		mt_pos.mt_blkno = blk;
3822 		retval = put_user_mtpos(p, &mt_pos);
3823 		goto out;
3824 	}
3825 	mutex_unlock(&STp->lock);
3826 	switch (cmd_in) {
3827 		case SCSI_IOCTL_GET_IDLUN:
3828 		case SCSI_IOCTL_GET_BUS_NUMBER:
3829 			break;
3830 		default:
3831 			if ((cmd_in == SG_IO ||
3832 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3833 			     cmd_in == CDROM_SEND_PACKET) &&
3834 			    !capable(CAP_SYS_RAWIO))
3835 				i = -EPERM;
3836 			else
3837 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3838 						   file->f_mode, cmd_in, p);
3839 			if (i != -ENOTTY)
3840 				return i;
3841 			break;
3842 	}
3843 	retval = scsi_ioctl(STp->device, cmd_in, p);
3844 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3845 		STp->rew_at_close = 0;
3846 		STp->ready = ST_NO_TAPE;
3847 	}
3848 	return retval;
3849 
3850  out:
3851 	mutex_unlock(&STp->lock);
3852 	return retval;
3853 }
3854 
3855 #ifdef CONFIG_COMPAT
3856 static long st_compat_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3857 {
3858 	void __user *p = compat_ptr(arg);
3859 	struct scsi_tape *STp = file->private_data;
3860 	struct scsi_device *sdev = STp->device;
3861 	int ret = -ENOIOCTLCMD;
3862 
3863 	/* argument conversion is handled using put_user_mtpos/put_user_mtget */
3864 	switch (cmd_in) {
3865 	case MTIOCTOP:
3866 		return st_ioctl(file, MTIOCTOP, (unsigned long)p);
3867 	case MTIOCPOS32:
3868 		return st_ioctl(file, MTIOCPOS, (unsigned long)p);
3869 	case MTIOCGET32:
3870 		return st_ioctl(file, MTIOCGET, (unsigned long)p);
3871 	}
3872 
3873 	if (sdev->host->hostt->compat_ioctl) {
3874 
3875 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd_in, (void __user *)arg);
3876 
3877 	}
3878 	return ret;
3879 }
3880 #endif
3881 
3882 
3883 
3884 /* Try to allocate a new tape buffer. Calling function must not hold
3885    dev_arr_lock. */
3886 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3887 {
3888 	struct st_buffer *tb;
3889 
3890 	tb = kzalloc(sizeof(struct st_buffer), GFP_KERNEL);
3891 	if (!tb) {
3892 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3893 		return NULL;
3894 	}
3895 	tb->frp_segs = 0;
3896 	tb->use_sg = max_sg;
3897 	tb->dma = need_dma;
3898 	tb->buffer_size = 0;
3899 
3900 	tb->reserved_pages = kcalloc(max_sg, sizeof(struct page *),
3901 				     GFP_KERNEL);
3902 	if (!tb->reserved_pages) {
3903 		kfree(tb);
3904 		return NULL;
3905 	}
3906 
3907 	return tb;
3908 }
3909 
3910 
3911 /* Try to allocate enough space in the tape buffer */
3912 #define ST_MAX_ORDER 6
3913 
3914 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3915 {
3916 	int segs, max_segs, b_size, order, got;
3917 	gfp_t priority;
3918 
3919 	if (new_size <= STbuffer->buffer_size)
3920 		return 1;
3921 
3922 	if (STbuffer->buffer_size <= PAGE_SIZE)
3923 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3924 
3925 	max_segs = STbuffer->use_sg;
3926 
3927 	priority = GFP_KERNEL | __GFP_NOWARN;
3928 	if (need_dma)
3929 		priority |= GFP_DMA;
3930 
3931 	if (STbuffer->cleared)
3932 		priority |= __GFP_ZERO;
3933 
3934 	if (STbuffer->frp_segs) {
3935 		order = STbuffer->reserved_page_order;
3936 		b_size = PAGE_SIZE << order;
3937 	} else {
3938 		for (b_size = PAGE_SIZE, order = 0;
3939 		     order < ST_MAX_ORDER &&
3940 			     max_segs * (PAGE_SIZE << order) < new_size;
3941 		     order++, b_size *= 2)
3942 			;  /* empty */
3943 		STbuffer->reserved_page_order = order;
3944 	}
3945 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3946 		if (order == ST_MAX_ORDER)
3947 			return 0;
3948 		normalize_buffer(STbuffer);
3949 		return enlarge_buffer(STbuffer, new_size, need_dma);
3950 	}
3951 
3952 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3953 	     segs < max_segs && got < new_size;) {
3954 		struct page *page;
3955 
3956 		page = alloc_pages(priority, order);
3957 		if (!page) {
3958 			DEB(STbuffer->buffer_size = got);
3959 			normalize_buffer(STbuffer);
3960 			return 0;
3961 		}
3962 
3963 		STbuffer->frp_segs += 1;
3964 		got += b_size;
3965 		STbuffer->buffer_size = got;
3966 		STbuffer->reserved_pages[segs] = page;
3967 		segs++;
3968 	}
3969 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3970 
3971 	return 1;
3972 }
3973 
3974 
3975 /* Make sure that no data from previous user is in the internal buffer */
3976 static void clear_buffer(struct st_buffer * st_bp)
3977 {
3978 	int i;
3979 
3980 	for (i=0; i < st_bp->frp_segs; i++)
3981 		memset(page_address(st_bp->reserved_pages[i]), 0,
3982 		       PAGE_SIZE << st_bp->reserved_page_order);
3983 	st_bp->cleared = 1;
3984 }
3985 
3986 
3987 /* Release the extra buffer */
3988 static void normalize_buffer(struct st_buffer * STbuffer)
3989 {
3990 	int i, order = STbuffer->reserved_page_order;
3991 
3992 	for (i = 0; i < STbuffer->frp_segs; i++) {
3993 		__free_pages(STbuffer->reserved_pages[i], order);
3994 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3995 	}
3996 	STbuffer->frp_segs = 0;
3997 	STbuffer->sg_segs = 0;
3998 	STbuffer->reserved_page_order = 0;
3999 	STbuffer->map_data.offset = 0;
4000 }
4001 
4002 
4003 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
4004    negative error code. */
4005 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
4006 {
4007 	int i, cnt, res, offset;
4008 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4009 
4010 	for (i = 0, offset = st_bp->buffer_bytes;
4011 	     i < st_bp->frp_segs && offset >= length; i++)
4012 		offset -= length;
4013 	if (i == st_bp->frp_segs) {	/* Should never happen */
4014 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
4015 		return (-EIO);
4016 	}
4017 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4018 		struct page *page = st_bp->reserved_pages[i];
4019 		cnt = length - offset < do_count ? length - offset : do_count;
4020 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4021 		if (res)
4022 			return (-EFAULT);
4023 		do_count -= cnt;
4024 		st_bp->buffer_bytes += cnt;
4025 		ubp += cnt;
4026 		offset = 0;
4027 	}
4028 	if (do_count) /* Should never happen */
4029 		return (-EIO);
4030 
4031 	return 0;
4032 }
4033 
4034 
4035 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4036    negative error code. */
4037 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4038 {
4039 	int i, cnt, res, offset;
4040 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4041 
4042 	for (i = 0, offset = st_bp->read_pointer;
4043 	     i < st_bp->frp_segs && offset >= length; i++)
4044 		offset -= length;
4045 	if (i == st_bp->frp_segs) {	/* Should never happen */
4046 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4047 		return (-EIO);
4048 	}
4049 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4050 		struct page *page = st_bp->reserved_pages[i];
4051 		cnt = length - offset < do_count ? length - offset : do_count;
4052 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4053 		if (res)
4054 			return (-EFAULT);
4055 		do_count -= cnt;
4056 		st_bp->buffer_bytes -= cnt;
4057 		st_bp->read_pointer += cnt;
4058 		ubp += cnt;
4059 		offset = 0;
4060 	}
4061 	if (do_count) /* Should never happen */
4062 		return (-EIO);
4063 
4064 	return 0;
4065 }
4066 
4067 
4068 /* Move data towards start of buffer */
4069 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4070 {
4071 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4072 	int count, total;
4073 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4074 
4075 	if (offset == 0)
4076 		return;
4077 
4078 	total=st_bp->buffer_bytes - offset;
4079 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4080 		src_offset = offset;
4081 		if (src_offset < length)
4082 			break;
4083 		offset -= length;
4084 	}
4085 
4086 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4087 	for (dst_seg=dst_offset=0; total > 0; ) {
4088 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4089 		struct page *spage = st_bp->reserved_pages[src_seg];
4090 
4091 		count = min(length - dst_offset, length - src_offset);
4092 		memmove(page_address(dpage) + dst_offset,
4093 			page_address(spage) + src_offset, count);
4094 		src_offset += count;
4095 		if (src_offset >= length) {
4096 			src_seg++;
4097 			src_offset = 0;
4098 		}
4099 		dst_offset += count;
4100 		if (dst_offset >= length) {
4101 			dst_seg++;
4102 			dst_offset = 0;
4103 		}
4104 		total -= count;
4105 	}
4106 }
4107 
4108 /* Validate the options from command line or module parameters */
4109 static void validate_options(void)
4110 {
4111 	if (buffer_kbs > 0)
4112 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4113 	if (max_sg_segs >= ST_FIRST_SG)
4114 		st_max_sg_segs = max_sg_segs;
4115 }
4116 
4117 #ifndef MODULE
4118 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4119  */
4120 static int __init st_setup(char *str)
4121 {
4122 	int i, len, ints[5];
4123 	char *stp;
4124 
4125 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4126 
4127 	if (ints[0] > 0) {
4128 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4129 			if (parms[i].val)
4130 				*parms[i].val = ints[i + 1];
4131 	} else {
4132 		while (stp != NULL) {
4133 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4134 				len = strlen(parms[i].name);
4135 				if (!strncmp(stp, parms[i].name, len) &&
4136 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4137 					if (parms[i].val)
4138 						*parms[i].val =
4139 							simple_strtoul(stp + len + 1, NULL, 0);
4140 					else
4141 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4142 						       parms[i].name);
4143 					break;
4144 				}
4145 			}
4146 			if (i >= ARRAY_SIZE(parms))
4147 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4148 					stp);
4149 			stp = strchr(stp, ',');
4150 			if (stp)
4151 				stp++;
4152 		}
4153 	}
4154 
4155 	validate_options();
4156 
4157 	return 1;
4158 }
4159 
4160 __setup("st=", st_setup);
4161 
4162 #endif
4163 
4164 static const struct file_operations st_fops =
4165 {
4166 	.owner =	THIS_MODULE,
4167 	.read =		st_read,
4168 	.write =	st_write,
4169 	.unlocked_ioctl = st_ioctl,
4170 #ifdef CONFIG_COMPAT
4171 	.compat_ioctl = st_compat_ioctl,
4172 #endif
4173 	.open =		st_open,
4174 	.flush =	st_flush,
4175 	.release =	st_release,
4176 	.llseek =	noop_llseek,
4177 };
4178 
4179 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4180 {
4181 	int i, error;
4182 	dev_t cdev_devno;
4183 	struct cdev *cdev;
4184 	struct device *dev;
4185 	struct st_modedef *STm = &(tape->modes[mode]);
4186 	char name[10];
4187 	int dev_num = tape->index;
4188 
4189 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4190 
4191 	cdev = cdev_alloc();
4192 	if (!cdev) {
4193 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4194 		error = -ENOMEM;
4195 		goto out;
4196 	}
4197 	cdev->owner = THIS_MODULE;
4198 	cdev->ops = &st_fops;
4199 	STm->cdevs[rew] = cdev;
4200 
4201 	error = cdev_add(cdev, cdev_devno, 1);
4202 	if (error) {
4203 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4204 		       rew ? "non" : "auto", mode);
4205 		pr_err("st%d: Device not attached.\n", dev_num);
4206 		goto out_free;
4207 	}
4208 
4209 	i = mode << (4 - ST_NBR_MODE_BITS);
4210 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4211 		 tape->disk->disk_name, st_formats[i]);
4212 
4213 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4214 			    cdev_devno, &tape->modes[mode], "%s", name);
4215 	if (IS_ERR(dev)) {
4216 		pr_err("st%d: device_create failed\n", dev_num);
4217 		error = PTR_ERR(dev);
4218 		goto out_free;
4219 	}
4220 
4221 	STm->devs[rew] = dev;
4222 
4223 	return 0;
4224 out_free:
4225 	cdev_del(STm->cdevs[rew]);
4226 out:
4227 	STm->cdevs[rew] = NULL;
4228 	STm->devs[rew] = NULL;
4229 	return error;
4230 }
4231 
4232 static int create_cdevs(struct scsi_tape *tape)
4233 {
4234 	int mode, error;
4235 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4236 		error = create_one_cdev(tape, mode, 0);
4237 		if (error)
4238 			return error;
4239 		error = create_one_cdev(tape, mode, 1);
4240 		if (error)
4241 			return error;
4242 	}
4243 
4244 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4245 				 &tape->modes[0].devs[0]->kobj, "tape");
4246 }
4247 
4248 static void remove_cdevs(struct scsi_tape *tape)
4249 {
4250 	int mode, rew;
4251 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4252 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4253 		struct st_modedef *STm = &(tape->modes[mode]);
4254 		for (rew = 0; rew < 2; rew++) {
4255 			if (STm->cdevs[rew])
4256 				cdev_del(STm->cdevs[rew]);
4257 			if (STm->devs[rew])
4258 				device_unregister(STm->devs[rew]);
4259 		}
4260 	}
4261 }
4262 
4263 static int st_probe(struct device *dev)
4264 {
4265 	struct scsi_device *SDp = to_scsi_device(dev);
4266 	struct gendisk *disk = NULL;
4267 	struct scsi_tape *tpnt = NULL;
4268 	struct st_modedef *STm;
4269 	struct st_partstat *STps;
4270 	struct st_buffer *buffer;
4271 	int i, error;
4272 	char *stp;
4273 
4274 	if (SDp->type != TYPE_TAPE)
4275 		return -ENODEV;
4276 	if ((stp = st_incompatible(SDp))) {
4277 		sdev_printk(KERN_INFO, SDp,
4278 			    "OnStream tapes are no longer supported;\n");
4279 		sdev_printk(KERN_INFO, SDp,
4280 			    "please mail to linux-scsi@vger.kernel.org.\n");
4281 		return -ENODEV;
4282 	}
4283 
4284 	scsi_autopm_get_device(SDp);
4285 	i = queue_max_segments(SDp->request_queue);
4286 	if (st_max_sg_segs < i)
4287 		i = st_max_sg_segs;
4288 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
4289 	if (buffer == NULL) {
4290 		sdev_printk(KERN_ERR, SDp,
4291 			    "st: Can't allocate new tape buffer. "
4292 			    "Device not attached.\n");
4293 		goto out;
4294 	}
4295 
4296 	disk = alloc_disk(1);
4297 	if (!disk) {
4298 		sdev_printk(KERN_ERR, SDp,
4299 			    "st: out of memory. Device not attached.\n");
4300 		goto out_buffer_free;
4301 	}
4302 
4303 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
4304 	if (tpnt == NULL) {
4305 		sdev_printk(KERN_ERR, SDp,
4306 			    "st: Can't allocate device descriptor.\n");
4307 		goto out_put_disk;
4308 	}
4309 	kref_init(&tpnt->kref);
4310 	tpnt->disk = disk;
4311 	disk->private_data = &tpnt->driver;
4312 	/* SCSI tape doesn't register this gendisk via add_disk().  Manually
4313 	 * take queue reference that release_disk() expects. */
4314 	if (!blk_get_queue(SDp->request_queue))
4315 		goto out_put_disk;
4316 	disk->queue = SDp->request_queue;
4317 	tpnt->driver = &st_template;
4318 
4319 	tpnt->device = SDp;
4320 	if (SDp->scsi_level <= 2)
4321 		tpnt->tape_type = MT_ISSCSI1;
4322 	else
4323 		tpnt->tape_type = MT_ISSCSI2;
4324 
4325 	tpnt->buffer = buffer;
4326 	tpnt->buffer->last_SRpnt = NULL;
4327 
4328 	tpnt->inited = 0;
4329 	tpnt->dirty = 0;
4330 	tpnt->in_use = 0;
4331 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4332 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4333 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4334 	tpnt->density = 0;
4335 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4336 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4337 	tpnt->can_partitions = 0;
4338 	tpnt->two_fm = ST_TWO_FM;
4339 	tpnt->fast_mteom = ST_FAST_MTEOM;
4340 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4341 	tpnt->sili = ST_SILI;
4342 	tpnt->immediate = ST_NOWAIT;
4343 	tpnt->immediate_filemark = 0;
4344 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4345 	tpnt->partition = 0;
4346 	tpnt->new_partition = 0;
4347 	tpnt->nbr_partitions = 0;
4348 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4349 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4350 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4351 
4352 	for (i = 0; i < ST_NBR_MODES; i++) {
4353 		STm = &(tpnt->modes[i]);
4354 		STm->defined = 0;
4355 		STm->sysv = ST_SYSV;
4356 		STm->defaults_for_writes = 0;
4357 		STm->do_async_writes = ST_ASYNC_WRITES;
4358 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4359 		STm->do_read_ahead = ST_READ_AHEAD;
4360 		STm->default_compression = ST_DONT_TOUCH;
4361 		STm->default_blksize = (-1);	/* No forced size */
4362 		STm->default_density = (-1);	/* No forced density */
4363 		STm->tape = tpnt;
4364 	}
4365 
4366 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4367 		STps = &(tpnt->ps[i]);
4368 		STps->rw = ST_IDLE;
4369 		STps->eof = ST_NOEOF;
4370 		STps->at_sm = 0;
4371 		STps->last_block_valid = 0;
4372 		STps->drv_block = (-1);
4373 		STps->drv_file = (-1);
4374 	}
4375 
4376 	tpnt->current_mode = 0;
4377 	tpnt->modes[0].defined = 1;
4378 
4379 	tpnt->density_changed = tpnt->compression_changed =
4380 	    tpnt->blksize_changed = 0;
4381 	mutex_init(&tpnt->lock);
4382 
4383 	idr_preload(GFP_KERNEL);
4384 	spin_lock(&st_index_lock);
4385 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4386 	spin_unlock(&st_index_lock);
4387 	idr_preload_end();
4388 	if (error < 0) {
4389 		pr_warn("st: idr allocation failed: %d\n", error);
4390 		goto out_put_queue;
4391 	}
4392 	tpnt->index = error;
4393 	sprintf(disk->disk_name, "st%d", tpnt->index);
4394 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4395 	if (tpnt->stats == NULL) {
4396 		sdev_printk(KERN_ERR, SDp,
4397 			    "st: Can't allocate statistics.\n");
4398 		goto out_idr_remove;
4399 	}
4400 
4401 	dev_set_drvdata(dev, tpnt);
4402 
4403 
4404 	error = create_cdevs(tpnt);
4405 	if (error)
4406 		goto out_remove_devs;
4407 	scsi_autopm_put_device(SDp);
4408 
4409 	sdev_printk(KERN_NOTICE, SDp,
4410 		    "Attached scsi tape %s\n", tape_name(tpnt));
4411 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4412 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4413 		    queue_dma_alignment(SDp->request_queue) + 1);
4414 
4415 	return 0;
4416 
4417 out_remove_devs:
4418 	remove_cdevs(tpnt);
4419 	kfree(tpnt->stats);
4420 out_idr_remove:
4421 	spin_lock(&st_index_lock);
4422 	idr_remove(&st_index_idr, tpnt->index);
4423 	spin_unlock(&st_index_lock);
4424 out_put_queue:
4425 	blk_put_queue(disk->queue);
4426 out_put_disk:
4427 	put_disk(disk);
4428 	kfree(tpnt);
4429 out_buffer_free:
4430 	kfree(buffer);
4431 out:
4432 	scsi_autopm_put_device(SDp);
4433 	return -ENODEV;
4434 };
4435 
4436 
4437 static int st_remove(struct device *dev)
4438 {
4439 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4440 	int index = tpnt->index;
4441 
4442 	scsi_autopm_get_device(to_scsi_device(dev));
4443 	remove_cdevs(tpnt);
4444 
4445 	mutex_lock(&st_ref_mutex);
4446 	kref_put(&tpnt->kref, scsi_tape_release);
4447 	mutex_unlock(&st_ref_mutex);
4448 	spin_lock(&st_index_lock);
4449 	idr_remove(&st_index_idr, index);
4450 	spin_unlock(&st_index_lock);
4451 	return 0;
4452 }
4453 
4454 /**
4455  *      scsi_tape_release - Called to free the Scsi_Tape structure
4456  *      @kref: pointer to embedded kref
4457  *
4458  *      st_ref_mutex must be held entering this routine.  Because it is
4459  *      called on last put, you should always use the scsi_tape_get()
4460  *      scsi_tape_put() helpers which manipulate the semaphore directly
4461  *      and never do a direct kref_put().
4462  **/
4463 static void scsi_tape_release(struct kref *kref)
4464 {
4465 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4466 	struct gendisk *disk = tpnt->disk;
4467 
4468 	tpnt->device = NULL;
4469 
4470 	if (tpnt->buffer) {
4471 		normalize_buffer(tpnt->buffer);
4472 		kfree(tpnt->buffer->reserved_pages);
4473 		kfree(tpnt->buffer);
4474 	}
4475 
4476 	disk->private_data = NULL;
4477 	put_disk(disk);
4478 	kfree(tpnt->stats);
4479 	kfree(tpnt);
4480 	return;
4481 }
4482 
4483 static struct class st_sysfs_class = {
4484 	.name = "scsi_tape",
4485 	.dev_groups = st_dev_groups,
4486 };
4487 
4488 static int __init init_st(void)
4489 {
4490 	int err;
4491 
4492 	validate_options();
4493 
4494 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4495 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4496 
4497 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4498 	if (debugging) {
4499 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4500 			debugging);
4501 	}
4502 
4503 	err = class_register(&st_sysfs_class);
4504 	if (err) {
4505 		pr_err("Unable register sysfs class for SCSI tapes\n");
4506 		return err;
4507 	}
4508 
4509 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4510 				     ST_MAX_TAPE_ENTRIES, "st");
4511 	if (err) {
4512 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4513 		       SCSI_TAPE_MAJOR);
4514 		goto err_class;
4515 	}
4516 
4517 	err = scsi_register_driver(&st_template.gendrv);
4518 	if (err)
4519 		goto err_chrdev;
4520 
4521 	return 0;
4522 
4523 err_chrdev:
4524 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4525 				 ST_MAX_TAPE_ENTRIES);
4526 err_class:
4527 	class_unregister(&st_sysfs_class);
4528 	return err;
4529 }
4530 
4531 static void __exit exit_st(void)
4532 {
4533 	scsi_unregister_driver(&st_template.gendrv);
4534 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4535 				 ST_MAX_TAPE_ENTRIES);
4536 	class_unregister(&st_sysfs_class);
4537 	idr_destroy(&st_index_idr);
4538 	printk(KERN_INFO "st: Unloaded.\n");
4539 }
4540 
4541 module_init(init_st);
4542 module_exit(exit_st);
4543 
4544 
4545 /* The sysfs driver interface. Read-only at the moment */
4546 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4547 {
4548 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4549 }
4550 static DRIVER_ATTR_RO(try_direct_io);
4551 
4552 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4553 {
4554 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4555 }
4556 static DRIVER_ATTR_RO(fixed_buffer_size);
4557 
4558 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4559 {
4560 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4561 }
4562 static DRIVER_ATTR_RO(max_sg_segs);
4563 
4564 static ssize_t version_show(struct device_driver *ddd, char *buf)
4565 {
4566 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4567 }
4568 static DRIVER_ATTR_RO(version);
4569 
4570 #if DEBUG
4571 static ssize_t debug_flag_store(struct device_driver *ddp,
4572 	const char *buf, size_t count)
4573 {
4574 /* We only care what the first byte of the data is the rest is unused.
4575  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4576  * other values have -EINVAL returned if they are passed in.
4577  */
4578 	if (count > 0) {
4579 		if (buf[0] == '0') {
4580 			debugging = NO_DEBUG;
4581 			return count;
4582 		} else if (buf[0] == '1') {
4583 			debugging = 1;
4584 			return count;
4585 		}
4586 	}
4587 	return -EINVAL;
4588 }
4589 
4590 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4591 {
4592 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4593 }
4594 static DRIVER_ATTR_RW(debug_flag);
4595 #endif
4596 
4597 static struct attribute *st_drv_attrs[] = {
4598 	&driver_attr_try_direct_io.attr,
4599 	&driver_attr_fixed_buffer_size.attr,
4600 	&driver_attr_max_sg_segs.attr,
4601 	&driver_attr_version.attr,
4602 #if DEBUG
4603 	&driver_attr_debug_flag.attr,
4604 #endif
4605 	NULL,
4606 };
4607 ATTRIBUTE_GROUPS(st_drv);
4608 
4609 /* The sysfs simple class interface */
4610 static ssize_t
4611 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4612 {
4613 	struct st_modedef *STm = dev_get_drvdata(dev);
4614 	ssize_t l = 0;
4615 
4616 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4617 	return l;
4618 }
4619 static DEVICE_ATTR_RO(defined);
4620 
4621 static ssize_t
4622 default_blksize_show(struct device *dev, struct device_attribute *attr,
4623 		     char *buf)
4624 {
4625 	struct st_modedef *STm = dev_get_drvdata(dev);
4626 	ssize_t l = 0;
4627 
4628 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4629 	return l;
4630 }
4631 static DEVICE_ATTR_RO(default_blksize);
4632 
4633 static ssize_t
4634 default_density_show(struct device *dev, struct device_attribute *attr,
4635 		     char *buf)
4636 {
4637 	struct st_modedef *STm = dev_get_drvdata(dev);
4638 	ssize_t l = 0;
4639 	char *fmt;
4640 
4641 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4642 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4643 	return l;
4644 }
4645 static DEVICE_ATTR_RO(default_density);
4646 
4647 static ssize_t
4648 default_compression_show(struct device *dev, struct device_attribute *attr,
4649 			 char *buf)
4650 {
4651 	struct st_modedef *STm = dev_get_drvdata(dev);
4652 	ssize_t l = 0;
4653 
4654 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4655 	return l;
4656 }
4657 static DEVICE_ATTR_RO(default_compression);
4658 
4659 static ssize_t
4660 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4661 {
4662 	struct st_modedef *STm = dev_get_drvdata(dev);
4663 	struct scsi_tape *STp = STm->tape;
4664 	int options;
4665 	ssize_t l = 0;
4666 
4667 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4668 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4669 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4670 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4671 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4672 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4673 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4674 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4675 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4676 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4677 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4678 	options |= STm->sysv ? MT_ST_SYSV : 0;
4679 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4680 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4681 	options |= STp->sili ? MT_ST_SILI : 0;
4682 
4683 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4684 	return l;
4685 }
4686 static DEVICE_ATTR_RO(options);
4687 
4688 /* Support for tape stats */
4689 
4690 /**
4691  * read_cnt_show - return read count - count of reads made from tape drive
4692  * @dev: struct device
4693  * @attr: attribute structure
4694  * @buf: buffer to return formatted data in
4695  */
4696 static ssize_t read_cnt_show(struct device *dev,
4697 	struct device_attribute *attr, char *buf)
4698 {
4699 	struct st_modedef *STm = dev_get_drvdata(dev);
4700 
4701 	return sprintf(buf, "%lld",
4702 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4703 }
4704 static DEVICE_ATTR_RO(read_cnt);
4705 
4706 /**
4707  * read_byte_cnt_show - return read byte count - tape drives
4708  * may use blocks less than 512 bytes this gives the raw byte count of
4709  * of data read from the tape drive.
4710  * @dev: struct device
4711  * @attr: attribute structure
4712  * @buf: buffer to return formatted data in
4713  */
4714 static ssize_t read_byte_cnt_show(struct device *dev,
4715 	struct device_attribute *attr, char *buf)
4716 {
4717 	struct st_modedef *STm = dev_get_drvdata(dev);
4718 
4719 	return sprintf(buf, "%lld",
4720 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4721 }
4722 static DEVICE_ATTR_RO(read_byte_cnt);
4723 
4724 /**
4725  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4726  * @dev: struct device
4727  * @attr: attribute structure
4728  * @buf: buffer to return formatted data in
4729  */
4730 static ssize_t read_ns_show(struct device *dev,
4731 	struct device_attribute *attr, char *buf)
4732 {
4733 	struct st_modedef *STm = dev_get_drvdata(dev);
4734 
4735 	return sprintf(buf, "%lld",
4736 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4737 }
4738 static DEVICE_ATTR_RO(read_ns);
4739 
4740 /**
4741  * write_cnt_show - write count - number of user calls
4742  * to write(2) that have written data to tape.
4743  * @dev: struct device
4744  * @attr: attribute structure
4745  * @buf: buffer to return formatted data in
4746  */
4747 static ssize_t write_cnt_show(struct device *dev,
4748 	struct device_attribute *attr, char *buf)
4749 {
4750 	struct st_modedef *STm = dev_get_drvdata(dev);
4751 
4752 	return sprintf(buf, "%lld",
4753 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4754 }
4755 static DEVICE_ATTR_RO(write_cnt);
4756 
4757 /**
4758  * write_byte_cnt_show - write byte count - raw count of
4759  * bytes written to tape.
4760  * @dev: struct device
4761  * @attr: attribute structure
4762  * @buf: buffer to return formatted data in
4763  */
4764 static ssize_t write_byte_cnt_show(struct device *dev,
4765 	struct device_attribute *attr, char *buf)
4766 {
4767 	struct st_modedef *STm = dev_get_drvdata(dev);
4768 
4769 	return sprintf(buf, "%lld",
4770 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4771 }
4772 static DEVICE_ATTR_RO(write_byte_cnt);
4773 
4774 /**
4775  * write_ns_show - write ns - number of nanoseconds waiting on write
4776  * requests to complete.
4777  * @dev: struct device
4778  * @attr: attribute structure
4779  * @buf: buffer to return formatted data in
4780  */
4781 static ssize_t write_ns_show(struct device *dev,
4782 	struct device_attribute *attr, char *buf)
4783 {
4784 	struct st_modedef *STm = dev_get_drvdata(dev);
4785 
4786 	return sprintf(buf, "%lld",
4787 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4788 }
4789 static DEVICE_ATTR_RO(write_ns);
4790 
4791 /**
4792  * in_flight_show - number of I/Os currently in flight -
4793  * in most cases this will be either 0 or 1. It may be higher if someone
4794  * has also issued other SCSI commands such as via an ioctl.
4795  * @dev: struct device
4796  * @attr: attribute structure
4797  * @buf: buffer to return formatted data in
4798  */
4799 static ssize_t in_flight_show(struct device *dev,
4800 	struct device_attribute *attr, char *buf)
4801 {
4802 	struct st_modedef *STm = dev_get_drvdata(dev);
4803 
4804 	return sprintf(buf, "%lld",
4805 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4806 }
4807 static DEVICE_ATTR_RO(in_flight);
4808 
4809 /**
4810  * io_ns_show - io wait ns - this is the number of ns spent
4811  * waiting on all I/O to complete. This includes tape movement commands
4812  * such as rewinding, seeking to end of file or tape, it also includes
4813  * read and write. To determine the time spent on tape movement
4814  * subtract the read and write ns from this value.
4815  * @dev: struct device
4816  * @attr: attribute structure
4817  * @buf: buffer to return formatted data in
4818  */
4819 static ssize_t io_ns_show(struct device *dev,
4820 	struct device_attribute *attr, char *buf)
4821 {
4822 	struct st_modedef *STm = dev_get_drvdata(dev);
4823 
4824 	return sprintf(buf, "%lld",
4825 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4826 }
4827 static DEVICE_ATTR_RO(io_ns);
4828 
4829 /**
4830  * other_cnt_show - other io count - this is the number of
4831  * I/O requests other than read and write requests.
4832  * Typically these are tape movement requests but will include driver
4833  * tape movement. This includes only requests issued by the st driver.
4834  * @dev: struct device
4835  * @attr: attribute structure
4836  * @buf: buffer to return formatted data in
4837  */
4838 static ssize_t other_cnt_show(struct device *dev,
4839 	struct device_attribute *attr, char *buf)
4840 {
4841 	struct st_modedef *STm = dev_get_drvdata(dev);
4842 
4843 	return sprintf(buf, "%lld",
4844 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4845 }
4846 static DEVICE_ATTR_RO(other_cnt);
4847 
4848 /**
4849  * resid_cnt_show - A count of the number of times we get a residual
4850  * count - this should indicate someone issuing reads larger than the
4851  * block size on tape.
4852  * @dev: struct device
4853  * @attr: attribute structure
4854  * @buf: buffer to return formatted data in
4855  */
4856 static ssize_t resid_cnt_show(struct device *dev,
4857 	struct device_attribute *attr, char *buf)
4858 {
4859 	struct st_modedef *STm = dev_get_drvdata(dev);
4860 
4861 	return sprintf(buf, "%lld",
4862 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4863 }
4864 static DEVICE_ATTR_RO(resid_cnt);
4865 
4866 static struct attribute *st_dev_attrs[] = {
4867 	&dev_attr_defined.attr,
4868 	&dev_attr_default_blksize.attr,
4869 	&dev_attr_default_density.attr,
4870 	&dev_attr_default_compression.attr,
4871 	&dev_attr_options.attr,
4872 	NULL,
4873 };
4874 
4875 static struct attribute *st_stats_attrs[] = {
4876 	&dev_attr_read_cnt.attr,
4877 	&dev_attr_read_byte_cnt.attr,
4878 	&dev_attr_read_ns.attr,
4879 	&dev_attr_write_cnt.attr,
4880 	&dev_attr_write_byte_cnt.attr,
4881 	&dev_attr_write_ns.attr,
4882 	&dev_attr_in_flight.attr,
4883 	&dev_attr_io_ns.attr,
4884 	&dev_attr_other_cnt.attr,
4885 	&dev_attr_resid_cnt.attr,
4886 	NULL,
4887 };
4888 
4889 static struct attribute_group stats_group = {
4890 	.name = "stats",
4891 	.attrs = st_stats_attrs,
4892 };
4893 
4894 static struct attribute_group st_group = {
4895 	.attrs = st_dev_attrs,
4896 };
4897 
4898 static const struct attribute_group *st_dev_groups[] = {
4899 	&st_group,
4900 	&stats_group,
4901 	NULL,
4902 };
4903 
4904 /* The following functions may be useful for a larger audience. */
4905 static int sgl_map_user_pages(struct st_buffer *STbp,
4906 			      const unsigned int max_pages, unsigned long uaddr,
4907 			      size_t count, int rw)
4908 {
4909 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4910 	unsigned long start = uaddr >> PAGE_SHIFT;
4911 	const int nr_pages = end - start;
4912 	int res, i, j;
4913 	struct page **pages;
4914 	struct rq_map_data *mdata = &STbp->map_data;
4915 
4916 	/* User attempted Overflow! */
4917 	if ((uaddr + count) < uaddr)
4918 		return -EINVAL;
4919 
4920 	/* Too big */
4921         if (nr_pages > max_pages)
4922 		return -ENOMEM;
4923 
4924 	/* Hmm? */
4925 	if (count == 0)
4926 		return 0;
4927 
4928 	pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
4929 	if (pages == NULL)
4930 		return -ENOMEM;
4931 
4932         /* Try to fault in all of the necessary pages */
4933         /* rw==READ means read from drive, write into memory area */
4934 	res = get_user_pages_fast(uaddr, nr_pages, rw == READ ? FOLL_WRITE : 0,
4935 				  pages);
4936 
4937 	/* Errors and no page mapped should return here */
4938 	if (res < nr_pages)
4939 		goto out_unmap;
4940 
4941         for (i=0; i < nr_pages; i++) {
4942                 /* FIXME: flush superflous for rw==READ,
4943                  * probably wrong function for rw==WRITE
4944                  */
4945 		flush_dcache_page(pages[i]);
4946         }
4947 
4948 	mdata->offset = uaddr & ~PAGE_MASK;
4949 	STbp->mapped_pages = pages;
4950 
4951 	return nr_pages;
4952  out_unmap:
4953 	if (res > 0) {
4954 		for (j=0; j < res; j++)
4955 			put_page(pages[j]);
4956 		res = 0;
4957 	}
4958 	kfree(pages);
4959 	return res;
4960 }
4961 
4962 
4963 /* And unmap them... */
4964 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4965 				const unsigned int nr_pages, int dirtied)
4966 {
4967 	int i;
4968 
4969 	for (i=0; i < nr_pages; i++) {
4970 		struct page *page = STbp->mapped_pages[i];
4971 
4972 		if (dirtied)
4973 			SetPageDirty(page);
4974 		/* FIXME: cache flush missing for rw==READ
4975 		 * FIXME: call the correct reference counting function
4976 		 */
4977 		put_page(page);
4978 	}
4979 	kfree(STbp->mapped_pages);
4980 	STbp->mapped_pages = NULL;
4981 
4982 	return 0;
4983 }
4984