xref: /openbmc/linux/drivers/scsi/st.c (revision 0646c28b)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3    SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
4    file Documentation/scsi/st.rst for more information.
5 
6    History:
7    Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
8    Contribution and ideas from several people including (in alphabetical
9    order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
10    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
11    Michael Schaefer, J"org Weule, and Eric Youngdale.
12 
13    Copyright 1992 - 2016 Kai Makisara
14    email Kai.Makisara@kolumbus.fi
15 
16    Some small formal changes - aeb, 950809
17 
18    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
19  */
20 
21 static const char *verstr = "20160209";
22 
23 #include <linux/module.h>
24 
25 #include <linux/compat.h>
26 #include <linux/fs.h>
27 #include <linux/kernel.h>
28 #include <linux/sched/signal.h>
29 #include <linux/mm.h>
30 #include <linux/init.h>
31 #include <linux/string.h>
32 #include <linux/slab.h>
33 #include <linux/errno.h>
34 #include <linux/mtio.h>
35 #include <linux/major.h>
36 #include <linux/cdrom.h>
37 #include <linux/ioctl.h>
38 #include <linux/fcntl.h>
39 #include <linux/spinlock.h>
40 #include <linux/blkdev.h>
41 #include <linux/moduleparam.h>
42 #include <linux/cdev.h>
43 #include <linux/idr.h>
44 #include <linux/delay.h>
45 #include <linux/mutex.h>
46 
47 #include <linux/uaccess.h>
48 #include <asm/dma.h>
49 #include <asm/unaligned.h>
50 
51 #include <scsi/scsi.h>
52 #include <scsi/scsi_dbg.h>
53 #include <scsi/scsi_device.h>
54 #include <scsi/scsi_driver.h>
55 #include <scsi/scsi_eh.h>
56 #include <scsi/scsi_host.h>
57 #include <scsi/scsi_ioctl.h>
58 #include <scsi/sg.h>
59 
60 
61 /* The driver prints some debugging information on the console if DEBUG
62    is defined and non-zero. */
63 #define DEBUG 1
64 #define NO_DEBUG 0
65 
66 #define ST_DEB_MSG  KERN_NOTICE
67 #if DEBUG
68 /* The message level for the debug messages is currently set to KERN_NOTICE
69    so that people can easily see the messages. Later when the debugging messages
70    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
71 #define DEB(a) a
72 #define DEBC(a) if (debugging) { a ; }
73 #else
74 #define DEB(a)
75 #define DEBC(a)
76 #endif
77 
78 #define ST_KILOBYTE 1024
79 
80 #include "st_options.h"
81 #include "st.h"
82 
83 static int buffer_kbs;
84 static int max_sg_segs;
85 static int try_direct_io = TRY_DIRECT_IO;
86 static int try_rdio = 1;
87 static int try_wdio = 1;
88 static int debug_flag;
89 
90 static struct class st_sysfs_class;
91 static const struct attribute_group *st_dev_groups[];
92 static const struct attribute_group *st_drv_groups[];
93 
94 MODULE_AUTHOR("Kai Makisara");
95 MODULE_DESCRIPTION("SCSI tape (st) driver");
96 MODULE_LICENSE("GPL");
97 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
98 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
99 
100 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
101  * of sysfs parameters (which module_param doesn't yet support).
102  * Sysfs parameters defined explicitly later.
103  */
104 module_param_named(buffer_kbs, buffer_kbs, int, 0);
105 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
106 module_param_named(max_sg_segs, max_sg_segs, int, 0);
107 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
108 module_param_named(try_direct_io, try_direct_io, int, 0);
109 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
110 module_param_named(debug_flag, debug_flag, int, 0);
111 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
112 
113 
114 /* Extra parameters for testing */
115 module_param_named(try_rdio, try_rdio, int, 0);
116 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
117 module_param_named(try_wdio, try_wdio, int, 0);
118 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
119 
120 #ifndef MODULE
121 static int write_threshold_kbs;  /* retained for compatibility */
122 static struct st_dev_parm {
123 	char *name;
124 	int *val;
125 } parms[] __initdata = {
126 	{
127 		"buffer_kbs", &buffer_kbs
128 	},
129 	{       /* Retained for compatibility with 2.4 */
130 		"write_threshold_kbs", &write_threshold_kbs
131 	},
132 	{
133 		"max_sg_segs", NULL
134 	},
135 	{
136 		"try_direct_io", &try_direct_io
137 	},
138 	{
139 		"debug_flag", &debug_flag
140 	}
141 };
142 #endif
143 
144 /* Restrict the number of modes so that names for all are assigned */
145 #if ST_NBR_MODES > 16
146 #error "Maximum number of modes is 16"
147 #endif
148 /* Bit reversed order to get same names for same minors with all
149    mode counts */
150 static const char *st_formats[] = {
151 	"",  "r", "k", "s", "l", "t", "o", "u",
152 	"m", "v", "p", "x", "a", "y", "q", "z"};
153 
154 /* The default definitions have been moved to st_options.h */
155 
156 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
157 
158 /* The buffer size should fit into the 24 bits for length in the
159    6-byte SCSI read and write commands. */
160 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
161 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
162 #endif
163 
164 static int debugging = DEBUG;
165 
166 #define MAX_RETRIES 0
167 #define MAX_WRITE_RETRIES 0
168 #define MAX_READY_RETRIES 0
169 #define NO_TAPE  NOT_READY
170 
171 #define ST_TIMEOUT (900 * HZ)
172 #define ST_LONG_TIMEOUT (14000 * HZ)
173 
174 /* Remove mode bits and auto-rewind bit (7) */
175 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
176 	(iminor(x) & ((1 << ST_MODE_SHIFT)-1)))
177 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
178 
179 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
180 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
181   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
182 
183 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
184    24 bits) */
185 #define SET_DENS_AND_BLK 0x10001
186 
187 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
188 static int st_max_sg_segs = ST_MAX_SG;
189 
190 static int modes_defined;
191 
192 static int enlarge_buffer(struct st_buffer *, int);
193 static void clear_buffer(struct st_buffer *);
194 static void normalize_buffer(struct st_buffer *);
195 static int append_to_buffer(const char __user *, struct st_buffer *, int);
196 static int from_buffer(struct st_buffer *, char __user *, int);
197 static void move_buffer_data(struct st_buffer *, int);
198 
199 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
200 			      unsigned long, size_t, int);
201 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
202 
203 static int st_probe(struct device *);
204 static int st_remove(struct device *);
205 
206 static struct scsi_driver st_template = {
207 	.gendrv = {
208 		.name		= "st",
209 		.owner		= THIS_MODULE,
210 		.probe		= st_probe,
211 		.remove		= st_remove,
212 		.groups		= st_drv_groups,
213 	},
214 };
215 
216 static int st_compression(struct scsi_tape *, int);
217 
218 static int find_partition(struct scsi_tape *);
219 static int switch_partition(struct scsi_tape *);
220 
221 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
222 
223 static void scsi_tape_release(struct kref *);
224 
225 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
226 
227 static DEFINE_MUTEX(st_ref_mutex);
228 static DEFINE_SPINLOCK(st_index_lock);
229 static DEFINE_SPINLOCK(st_use_lock);
230 static DEFINE_IDR(st_index_idr);
231 
232 
233 
234 #ifndef SIGS_FROM_OSST
235 #define SIGS_FROM_OSST \
236 	{"OnStream", "SC-", "", "osst"}, \
237 	{"OnStream", "DI-", "", "osst"}, \
238 	{"OnStream", "DP-", "", "osst"}, \
239 	{"OnStream", "USB", "", "osst"}, \
240 	{"OnStream", "FW-", "", "osst"}
241 #endif
242 
243 static struct scsi_tape *scsi_tape_get(int dev)
244 {
245 	struct scsi_tape *STp = NULL;
246 
247 	mutex_lock(&st_ref_mutex);
248 	spin_lock(&st_index_lock);
249 
250 	STp = idr_find(&st_index_idr, dev);
251 	if (!STp) goto out;
252 
253 	kref_get(&STp->kref);
254 
255 	if (!STp->device)
256 		goto out_put;
257 
258 	if (scsi_device_get(STp->device))
259 		goto out_put;
260 
261 	goto out;
262 
263 out_put:
264 	kref_put(&STp->kref, scsi_tape_release);
265 	STp = NULL;
266 out:
267 	spin_unlock(&st_index_lock);
268 	mutex_unlock(&st_ref_mutex);
269 	return STp;
270 }
271 
272 static void scsi_tape_put(struct scsi_tape *STp)
273 {
274 	struct scsi_device *sdev = STp->device;
275 
276 	mutex_lock(&st_ref_mutex);
277 	kref_put(&STp->kref, scsi_tape_release);
278 	scsi_device_put(sdev);
279 	mutex_unlock(&st_ref_mutex);
280 }
281 
282 struct st_reject_data {
283 	char *vendor;
284 	char *model;
285 	char *rev;
286 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
287 };
288 
289 static struct st_reject_data reject_list[] = {
290 	/* {"XXX", "Yy-", "", NULL},  example */
291 	SIGS_FROM_OSST,
292 	{NULL, }};
293 
294 /* If the device signature is on the list of incompatible drives, the
295    function returns a pointer to the name of the correct driver (if known) */
296 static char * st_incompatible(struct scsi_device* SDp)
297 {
298 	struct st_reject_data *rp;
299 
300 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
301 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
302 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
303 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
304 			if (rp->driver_hint)
305 				return rp->driver_hint;
306 			else
307 				return "unknown";
308 		}
309 	return NULL;
310 }
311 
312 
313 #define st_printk(prefix, t, fmt, a...) \
314 	sdev_prefix_printk(prefix, (t)->device, (t)->name, fmt, ##a)
315 #ifdef DEBUG
316 #define DEBC_printk(t, fmt, a...) \
317 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
318 #else
319 #define DEBC_printk(t, fmt, a...)
320 #endif
321 
322 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
323 {
324 	const u8 *ucp;
325 	const u8 *sense = SRpnt->sense;
326 
327 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
328 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
329 	s->flags = 0;
330 
331 	if (s->have_sense) {
332 		s->deferred = 0;
333 		s->remainder_valid =
334 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
335 		switch (sense[0] & 0x7f) {
336 		case 0x71:
337 			s->deferred = 1;
338 			fallthrough;
339 		case 0x70:
340 			s->fixed_format = 1;
341 			s->flags = sense[2] & 0xe0;
342 			break;
343 		case 0x73:
344 			s->deferred = 1;
345 			fallthrough;
346 		case 0x72:
347 			s->fixed_format = 0;
348 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
349 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
350 			break;
351 		}
352 	}
353 }
354 
355 
356 /* Convert the result to success code */
357 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
358 {
359 	int result = SRpnt->result;
360 	u8 scode;
361 	DEB(const char *stp;)
362 	char *name = STp->name;
363 	struct st_cmdstatus *cmdstatp;
364 
365 	if (!result)
366 		return 0;
367 
368 	cmdstatp = &STp->buffer->cmdstat;
369 	st_analyze_sense(SRpnt, cmdstatp);
370 
371 	if (cmdstatp->have_sense)
372 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
373 	else
374 		scode = 0;
375 
376 	DEB(
377 	if (debugging) {
378 		st_printk(ST_DEB_MSG, STp,
379 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
380 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
381 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
382 		if (cmdstatp->have_sense)
383 			__scsi_print_sense(STp->device, name,
384 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
385 	} ) /* end DEB */
386 	if (!debugging) { /* Abnormal conditions for tape */
387 		if (!cmdstatp->have_sense)
388 			st_printk(KERN_WARNING, STp,
389 			       "Error %x (driver bt 0, host bt 0x%x).\n",
390 			       result, host_byte(result));
391 		else if (cmdstatp->have_sense &&
392 			 scode != NO_SENSE &&
393 			 scode != RECOVERED_ERROR &&
394 			 /* scode != UNIT_ATTENTION && */
395 			 scode != BLANK_CHECK &&
396 			 scode != VOLUME_OVERFLOW &&
397 			 SRpnt->cmd[0] != MODE_SENSE &&
398 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
399 
400 			__scsi_print_sense(STp->device, name,
401 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
402 		}
403 	}
404 
405 	if (cmdstatp->fixed_format &&
406 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
407 		if (STp->cln_sense_value)
408 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
409 					       STp->cln_sense_mask) == STp->cln_sense_value);
410 		else
411 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
412 					       STp->cln_sense_mask) != 0);
413 	}
414 	if (cmdstatp->have_sense &&
415 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
416 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
417 
418 	STp->pos_unknown |= STp->device->was_reset;
419 
420 	if (cmdstatp->have_sense &&
421 	    scode == RECOVERED_ERROR
422 #if ST_RECOVERED_WRITE_FATAL
423 	    && SRpnt->cmd[0] != WRITE_6
424 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
425 #endif
426 	    ) {
427 		STp->recover_count++;
428 		STp->recover_reg++;
429 
430 		DEB(
431 		if (debugging) {
432 			if (SRpnt->cmd[0] == READ_6)
433 				stp = "read";
434 			else if (SRpnt->cmd[0] == WRITE_6)
435 				stp = "write";
436 			else
437 				stp = "ioctl";
438 			st_printk(ST_DEB_MSG, STp,
439 				  "Recovered %s error (%d).\n",
440 				  stp, STp->recover_count);
441 		} ) /* end DEB */
442 
443 		if (cmdstatp->flags == 0)
444 			return 0;
445 	}
446 	return (-EIO);
447 }
448 
449 static struct st_request *st_allocate_request(struct scsi_tape *stp)
450 {
451 	struct st_request *streq;
452 
453 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
454 	if (streq)
455 		streq->stp = stp;
456 	else {
457 		st_printk(KERN_ERR, stp,
458 			  "Can't get SCSI request.\n");
459 		if (signal_pending(current))
460 			stp->buffer->syscall_result = -EINTR;
461 		else
462 			stp->buffer->syscall_result = -EBUSY;
463 	}
464 
465 	return streq;
466 }
467 
468 static void st_release_request(struct st_request *streq)
469 {
470 	kfree(streq);
471 }
472 
473 static void st_do_stats(struct scsi_tape *STp, struct request *req)
474 {
475 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
476 	ktime_t now;
477 
478 	now = ktime_get();
479 	if (scmd->cmnd[0] == WRITE_6) {
480 		now = ktime_sub(now, STp->stats->write_time);
481 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
482 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
483 		atomic64_inc(&STp->stats->write_cnt);
484 		if (scmd->result) {
485 			atomic64_add(atomic_read(&STp->stats->last_write_size)
486 				- STp->buffer->cmdstat.residual,
487 				&STp->stats->write_byte_cnt);
488 			if (STp->buffer->cmdstat.residual > 0)
489 				atomic64_inc(&STp->stats->resid_cnt);
490 		} else
491 			atomic64_add(atomic_read(&STp->stats->last_write_size),
492 				&STp->stats->write_byte_cnt);
493 	} else if (scmd->cmnd[0] == READ_6) {
494 		now = ktime_sub(now, STp->stats->read_time);
495 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
496 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
497 		atomic64_inc(&STp->stats->read_cnt);
498 		if (scmd->result) {
499 			atomic64_add(atomic_read(&STp->stats->last_read_size)
500 				- STp->buffer->cmdstat.residual,
501 				&STp->stats->read_byte_cnt);
502 			if (STp->buffer->cmdstat.residual > 0)
503 				atomic64_inc(&STp->stats->resid_cnt);
504 		} else
505 			atomic64_add(atomic_read(&STp->stats->last_read_size),
506 				&STp->stats->read_byte_cnt);
507 	} else {
508 		now = ktime_sub(now, STp->stats->other_time);
509 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
510 		atomic64_inc(&STp->stats->other_cnt);
511 	}
512 	atomic64_dec(&STp->stats->in_flight);
513 }
514 
515 static enum rq_end_io_ret st_scsi_execute_end(struct request *req,
516 					      blk_status_t status)
517 {
518 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
519 	struct st_request *SRpnt = req->end_io_data;
520 	struct scsi_tape *STp = SRpnt->stp;
521 	struct bio *tmp;
522 
523 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = scmd->result;
524 	STp->buffer->cmdstat.residual = scmd->resid_len;
525 
526 	st_do_stats(STp, req);
527 
528 	tmp = SRpnt->bio;
529 	if (scmd->sense_len)
530 		memcpy(SRpnt->sense, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
531 	if (SRpnt->waiting)
532 		complete(SRpnt->waiting);
533 
534 	blk_rq_unmap_user(tmp);
535 	blk_mq_free_request(req);
536 	return RQ_END_IO_NONE;
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 rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
545 	int err = 0;
546 	struct scsi_tape *STp = SRpnt->stp;
547 	struct scsi_cmnd *scmd;
548 
549 	req = scsi_alloc_request(SRpnt->stp->device->request_queue,
550 			data_direction == DMA_TO_DEVICE ?
551 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
552 	if (IS_ERR(req))
553 		return PTR_ERR(req);
554 	scmd = blk_mq_rq_to_pdu(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_mq_free_request(req);
564 			return err;
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 	scmd->cmd_len = COMMAND_SIZE(cmd[0]);
581 	memcpy(scmd->cmnd, cmd, scmd->cmd_len);
582 	req->timeout = timeout;
583 	scmd->allowed = retries;
584 	req->end_io = st_scsi_execute_end;
585 	req->end_io_data = SRpnt;
586 
587 	blk_execute_rq_nowait(req, true);
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 		DEBC_printk(STp, "Device already in use.\n");
1272 		scsi_tape_put(STp);
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)) {
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 	struct scsi_tape *STp = filp->private_data;
1460 
1461 	if (STp->door_locked == ST_LOCKED_AUTO)
1462 		do_door_lock(STp, 0);
1463 
1464 	normalize_buffer(STp->buffer);
1465 	spin_lock(&st_use_lock);
1466 	STp->in_use = 0;
1467 	spin_unlock(&st_use_lock);
1468 	scsi_autopm_put_device(STp->device);
1469 	scsi_tape_put(STp);
1470 
1471 	return 0;
1472 }
1473 
1474 /* The checks common to both reading and writing */
1475 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1476 {
1477 	ssize_t retval = 0;
1478 
1479 	/*
1480 	 * If we are in the middle of error recovery, don't let anyone
1481 	 * else try and use this device.  Also, if error recovery fails, it
1482 	 * may try and take the device offline, in which case all further
1483 	 * access to the device is prohibited.
1484 	 */
1485 	if (!scsi_block_when_processing_errors(STp->device)) {
1486 		retval = (-ENXIO);
1487 		goto out;
1488 	}
1489 
1490 	if (STp->ready != ST_READY) {
1491 		if (STp->ready == ST_NO_TAPE)
1492 			retval = (-ENOMEDIUM);
1493 		else
1494 			retval = (-EIO);
1495 		goto out;
1496 	}
1497 
1498 	if (! STp->modes[STp->current_mode].defined) {
1499 		retval = (-ENXIO);
1500 		goto out;
1501 	}
1502 
1503 
1504 	/*
1505 	 * If there was a bus reset, block further access
1506 	 * to this device.
1507 	 */
1508 	if (STp->pos_unknown) {
1509 		retval = (-EIO);
1510 		goto out;
1511 	}
1512 
1513 	if (count == 0)
1514 		goto out;
1515 
1516 	DEB(
1517 	if (!STp->in_use) {
1518 		st_printk(ST_DEB_MSG, STp,
1519 			  "Incorrect device.\n");
1520 		retval = (-EIO);
1521 		goto out;
1522 	} ) /* end DEB */
1523 
1524 	if (STp->can_partitions &&
1525 	    (retval = switch_partition(STp)) < 0)
1526 		goto out;
1527 
1528 	if (STp->block_size == 0 && STp->max_block > 0 &&
1529 	    (count < STp->min_block || count > STp->max_block)) {
1530 		retval = (-EINVAL);
1531 		goto out;
1532 	}
1533 
1534 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1535 	    !do_door_lock(STp, 1))
1536 		STp->door_locked = ST_LOCKED_AUTO;
1537 
1538  out:
1539 	return retval;
1540 }
1541 
1542 
1543 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1544 			   size_t count, int is_read)
1545 {
1546 	int i, bufsize, retval = 0;
1547 	struct st_buffer *STbp = STp->buffer;
1548 
1549 	if (is_read)
1550 		i = STp->try_dio_now && try_rdio;
1551 	else
1552 		i = STp->try_dio_now && try_wdio;
1553 
1554 	if (i && ((unsigned long)buf & queue_dma_alignment(
1555 					STp->device->request_queue)) == 0) {
1556 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1557 				       count, (is_read ? READ : WRITE));
1558 		if (i > 0) {
1559 			STbp->do_dio = i;
1560 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1561 		}
1562 		else
1563 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1564 		STbp->sg_segs = STbp->do_dio;
1565 		DEB(
1566 		     if (STbp->do_dio) {
1567 			STp->nbr_dio++;
1568 			STp->nbr_pages += STbp->do_dio;
1569 		     }
1570 		)
1571 	} else
1572 		STbp->do_dio = 0;
1573 	DEB( STp->nbr_requests++; )
1574 
1575 	if (!STbp->do_dio) {
1576 		if (STp->block_size)
1577 			bufsize = STp->block_size > st_fixed_buffer_size ?
1578 				STp->block_size : st_fixed_buffer_size;
1579 		else {
1580 			bufsize = count;
1581 			/* Make sure that data from previous user is not leaked even if
1582 			   HBA does not return correct residual */
1583 			if (is_read && STp->sili && !STbp->cleared)
1584 				clear_buffer(STbp);
1585 		}
1586 
1587 		if (bufsize > STbp->buffer_size &&
1588 		    !enlarge_buffer(STbp, bufsize)) {
1589 			st_printk(KERN_WARNING, STp,
1590 				  "Can't allocate %d byte tape buffer.\n",
1591 				  bufsize);
1592 			retval = (-EOVERFLOW);
1593 			goto out;
1594 		}
1595 		if (STp->block_size)
1596 			STbp->buffer_blocks = bufsize / STp->block_size;
1597 	}
1598 
1599  out:
1600 	return retval;
1601 }
1602 
1603 
1604 /* Can be called more than once after each setup_buffer() */
1605 static void release_buffering(struct scsi_tape *STp, int is_read)
1606 {
1607 	struct st_buffer *STbp;
1608 
1609 	STbp = STp->buffer;
1610 	if (STbp->do_dio) {
1611 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1612 		STbp->do_dio = 0;
1613 		STbp->sg_segs = 0;
1614 	}
1615 }
1616 
1617 
1618 /* Write command */
1619 static ssize_t
1620 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1621 {
1622 	ssize_t total;
1623 	ssize_t i, do_count, blks, transfer;
1624 	ssize_t retval;
1625 	int undone, retry_eot = 0, scode;
1626 	int async_write;
1627 	unsigned char cmd[MAX_COMMAND_SIZE];
1628 	const char __user *b_point;
1629 	struct st_request *SRpnt = NULL;
1630 	struct scsi_tape *STp = filp->private_data;
1631 	struct st_modedef *STm;
1632 	struct st_partstat *STps;
1633 	struct st_buffer *STbp;
1634 
1635 	if (mutex_lock_interruptible(&STp->lock))
1636 		return -ERESTARTSYS;
1637 
1638 	retval = rw_checks(STp, filp, count);
1639 	if (retval || count == 0)
1640 		goto out;
1641 
1642 	/* Write must be integral number of blocks */
1643 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1644 		st_printk(KERN_WARNING, STp,
1645 			  "Write not multiple of tape block size.\n");
1646 		retval = (-EINVAL);
1647 		goto out;
1648 	}
1649 
1650 	STm = &(STp->modes[STp->current_mode]);
1651 	STps = &(STp->ps[STp->partition]);
1652 
1653 	if (STp->write_prot) {
1654 		retval = (-EACCES);
1655 		goto out;
1656 	}
1657 
1658 
1659 	if (STps->rw == ST_READING) {
1660 		retval = flush_buffer(STp, 0);
1661 		if (retval)
1662 			goto out;
1663 		STps->rw = ST_WRITING;
1664 	} else if (STps->rw != ST_WRITING &&
1665 		   STps->drv_file == 0 && STps->drv_block == 0) {
1666 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1667 			goto out;
1668 		if (STm->default_compression != ST_DONT_TOUCH &&
1669 		    !(STp->compression_changed)) {
1670 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1671 				st_printk(KERN_WARNING, STp,
1672 					  "Can't set default compression.\n");
1673 				if (modes_defined) {
1674 					retval = (-EINVAL);
1675 					goto out;
1676 				}
1677 			}
1678 		}
1679 	}
1680 
1681 	STbp = STp->buffer;
1682 	i = write_behind_check(STp);
1683 	if (i) {
1684 		if (i == -ENOSPC)
1685 			STps->eof = ST_EOM_OK;
1686 		else
1687 			STps->eof = ST_EOM_ERROR;
1688 	}
1689 
1690 	if (STps->eof == ST_EOM_OK) {
1691 		STps->eof = ST_EOD_1;  /* allow next write */
1692 		retval = (-ENOSPC);
1693 		goto out;
1694 	}
1695 	else if (STps->eof == ST_EOM_ERROR) {
1696 		retval = (-EIO);
1697 		goto out;
1698 	}
1699 
1700 	/* Check the buffer readability in cases where copy_user might catch
1701 	   the problems after some tape movement. */
1702 	if (STp->block_size != 0 &&
1703 	    !STbp->do_dio &&
1704 	    (copy_from_user(&i, buf, 1) != 0 ||
1705 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1706 		retval = (-EFAULT);
1707 		goto out;
1708 	}
1709 
1710 	retval = setup_buffering(STp, buf, count, 0);
1711 	if (retval)
1712 		goto out;
1713 
1714 	total = count;
1715 
1716 	memset(cmd, 0, MAX_COMMAND_SIZE);
1717 	cmd[0] = WRITE_6;
1718 	cmd[1] = (STp->block_size != 0);
1719 
1720 	STps->rw = ST_WRITING;
1721 
1722 	b_point = buf;
1723 	while (count > 0 && !retry_eot) {
1724 
1725 		if (STbp->do_dio) {
1726 			do_count = count;
1727 		}
1728 		else {
1729 			if (STp->block_size == 0)
1730 				do_count = count;
1731 			else {
1732 				do_count = STbp->buffer_blocks * STp->block_size -
1733 					STbp->buffer_bytes;
1734 				if (do_count > count)
1735 					do_count = count;
1736 			}
1737 
1738 			i = append_to_buffer(b_point, STbp, do_count);
1739 			if (i) {
1740 				retval = i;
1741 				goto out;
1742 			}
1743 		}
1744 		count -= do_count;
1745 		b_point += do_count;
1746 
1747 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1748 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1749 
1750 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1751 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1752 		    STbp->buffer_bytes < STbp->buffer_size) {
1753 			STp->dirty = 1;
1754 			/* Don't write a buffer that is not full enough. */
1755 			if (!async_write && count == 0)
1756 				break;
1757 		}
1758 
1759 	retry_write:
1760 		if (STp->block_size == 0)
1761 			blks = transfer = do_count;
1762 		else {
1763 			if (!STbp->do_dio)
1764 				blks = STbp->buffer_bytes;
1765 			else
1766 				blks = do_count;
1767 			blks /= STp->block_size;
1768 			transfer = blks * STp->block_size;
1769 		}
1770 		cmd[2] = blks >> 16;
1771 		cmd[3] = blks >> 8;
1772 		cmd[4] = blks;
1773 
1774 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1775 				   STp->device->request_queue->rq_timeout,
1776 				   MAX_WRITE_RETRIES, !async_write);
1777 		if (!SRpnt) {
1778 			retval = STbp->syscall_result;
1779 			goto out;
1780 		}
1781 		if (async_write && !STbp->syscall_result) {
1782 			STbp->writing = transfer;
1783 			STp->dirty = !(STbp->writing ==
1784 				       STbp->buffer_bytes);
1785 			SRpnt = NULL;  /* Prevent releasing this request! */
1786 			DEB( STp->write_pending = 1; )
1787 			break;
1788 		}
1789 
1790 		if (STbp->syscall_result != 0) {
1791 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1792 
1793 			DEBC_printk(STp, "Error on write:\n");
1794 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1795 				scode = cmdstatp->sense_hdr.sense_key;
1796 				if (cmdstatp->remainder_valid)
1797 					undone = (int)cmdstatp->uremainder64;
1798 				else if (STp->block_size == 0 &&
1799 					 scode == VOLUME_OVERFLOW)
1800 					undone = transfer;
1801 				else
1802 					undone = 0;
1803 				if (STp->block_size != 0)
1804 					undone *= STp->block_size;
1805 				if (undone <= do_count) {
1806 					/* Only data from this write is not written */
1807 					count += undone;
1808 					b_point -= undone;
1809 					do_count -= undone;
1810 					if (STp->block_size)
1811 						blks = (transfer - undone) / STp->block_size;
1812 					STps->eof = ST_EOM_OK;
1813 					/* Continue in fixed block mode if all written
1814 					   in this request but still something left to write
1815 					   (retval left to zero)
1816 					*/
1817 					if (STp->block_size == 0 ||
1818 					    undone > 0 || count == 0)
1819 						retval = (-ENOSPC); /* EOM within current request */
1820 					DEBC_printk(STp, "EOM with %d "
1821 						    "bytes unwritten.\n",
1822 						    (int)count);
1823 				} else {
1824 					/* EOT within data buffered earlier (possible only
1825 					   in fixed block mode without direct i/o) */
1826 					if (!retry_eot && !cmdstatp->deferred &&
1827 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1828 						move_buffer_data(STp->buffer, transfer - undone);
1829 						retry_eot = 1;
1830 						if (STps->drv_block >= 0) {
1831 							STps->drv_block += (transfer - undone) /
1832 								STp->block_size;
1833 						}
1834 						STps->eof = ST_EOM_OK;
1835 						DEBC_printk(STp, "Retry "
1836 							    "write of %d "
1837 							    "bytes at EOM.\n",
1838 							    STp->buffer->buffer_bytes);
1839 						goto retry_write;
1840 					}
1841 					else {
1842 						/* Either error within data buffered by driver or
1843 						   failed retry */
1844 						count -= do_count;
1845 						blks = do_count = 0;
1846 						STps->eof = ST_EOM_ERROR;
1847 						STps->drv_block = (-1); /* Too cautious? */
1848 						retval = (-EIO);	/* EOM for old data */
1849 						DEBC_printk(STp, "EOM with "
1850 							    "lost data.\n");
1851 					}
1852 				}
1853 			} else {
1854 				count += do_count;
1855 				STps->drv_block = (-1);		/* Too cautious? */
1856 				retval = STbp->syscall_result;
1857 			}
1858 
1859 		}
1860 
1861 		if (STps->drv_block >= 0) {
1862 			if (STp->block_size == 0)
1863 				STps->drv_block += (do_count > 0);
1864 			else
1865 				STps->drv_block += blks;
1866 		}
1867 
1868 		STbp->buffer_bytes = 0;
1869 		STp->dirty = 0;
1870 
1871 		if (retval || retry_eot) {
1872 			if (count < total)
1873 				retval = total - count;
1874 			goto out;
1875 		}
1876 	}
1877 
1878 	if (STps->eof == ST_EOD_1)
1879 		STps->eof = ST_EOM_OK;
1880 	else if (STps->eof != ST_EOM_OK)
1881 		STps->eof = ST_NOEOF;
1882 	retval = total - count;
1883 
1884  out:
1885 	if (SRpnt != NULL)
1886 		st_release_request(SRpnt);
1887 	release_buffering(STp, 0);
1888 	mutex_unlock(&STp->lock);
1889 
1890 	return retval;
1891 }
1892 
1893 /* Read data from the tape. Returns zero in the normal case, one if the
1894    eof status has changed, and the negative error code in case of a
1895    fatal error. Otherwise updates the buffer and the eof state.
1896 
1897    Does release user buffer mapping if it is set.
1898 */
1899 static long read_tape(struct scsi_tape *STp, long count,
1900 		      struct st_request ** aSRpnt)
1901 {
1902 	int transfer, blks, bytes;
1903 	unsigned char cmd[MAX_COMMAND_SIZE];
1904 	struct st_request *SRpnt;
1905 	struct st_modedef *STm;
1906 	struct st_partstat *STps;
1907 	struct st_buffer *STbp;
1908 	int retval = 0;
1909 
1910 	if (count == 0)
1911 		return 0;
1912 
1913 	STm = &(STp->modes[STp->current_mode]);
1914 	STps = &(STp->ps[STp->partition]);
1915 	if (STps->eof == ST_FM_HIT)
1916 		return 1;
1917 	STbp = STp->buffer;
1918 
1919 	if (STp->block_size == 0)
1920 		blks = bytes = count;
1921 	else {
1922 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1923 			blks = (STp->buffer)->buffer_blocks;
1924 			bytes = blks * STp->block_size;
1925 		} else {
1926 			bytes = count;
1927 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1928 				bytes = (STp->buffer)->buffer_size;
1929 			blks = bytes / STp->block_size;
1930 			bytes = blks * STp->block_size;
1931 		}
1932 	}
1933 
1934 	memset(cmd, 0, MAX_COMMAND_SIZE);
1935 	cmd[0] = READ_6;
1936 	cmd[1] = (STp->block_size != 0);
1937 	if (!cmd[1] && STp->sili)
1938 		cmd[1] |= 2;
1939 	cmd[2] = blks >> 16;
1940 	cmd[3] = blks >> 8;
1941 	cmd[4] = blks;
1942 
1943 	SRpnt = *aSRpnt;
1944 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1945 			   STp->device->request_queue->rq_timeout,
1946 			   MAX_RETRIES, 1);
1947 	release_buffering(STp, 1);
1948 	*aSRpnt = SRpnt;
1949 	if (!SRpnt)
1950 		return STbp->syscall_result;
1951 
1952 	STbp->read_pointer = 0;
1953 	STps->at_sm = 0;
1954 
1955 	/* Something to check */
1956 	if (STbp->syscall_result) {
1957 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1958 
1959 		retval = 1;
1960 		DEBC_printk(STp,
1961 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1962 			    SRpnt->sense[0], SRpnt->sense[1],
1963 			    SRpnt->sense[2], SRpnt->sense[3],
1964 			    SRpnt->sense[4], SRpnt->sense[5],
1965 			    SRpnt->sense[6], SRpnt->sense[7]);
1966 		if (cmdstatp->have_sense) {
1967 
1968 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1969 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1970 
1971 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1972 				/* Compute the residual count */
1973 				if (cmdstatp->remainder_valid)
1974 					transfer = (int)cmdstatp->uremainder64;
1975 				else
1976 					transfer = 0;
1977 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1978 					if (STp->block_size == 0)
1979 						transfer = bytes;
1980 					/* Some drives set ILI with MEDIUM ERROR */
1981 					cmdstatp->flags &= ~SENSE_ILI;
1982 				}
1983 
1984 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1985 					if (STp->block_size == 0 &&
1986 					    transfer < 0) {
1987 						st_printk(KERN_NOTICE, STp,
1988 							  "Failed to read %d "
1989 							  "byte block with %d "
1990 							  "byte transfer.\n",
1991 							  bytes - transfer,
1992 							  bytes);
1993 						if (STps->drv_block >= 0)
1994 							STps->drv_block += 1;
1995 						STbp->buffer_bytes = 0;
1996 						return (-ENOMEM);
1997 					} else if (STp->block_size == 0) {
1998 						STbp->buffer_bytes = bytes - transfer;
1999 					} else {
2000 						st_release_request(SRpnt);
2001 						SRpnt = *aSRpnt = NULL;
2002 						if (transfer == blks) {	/* We did not get anything, error */
2003 							st_printk(KERN_NOTICE, STp,
2004 								  "Incorrect "
2005 								  "block size.\n");
2006 							if (STps->drv_block >= 0)
2007 								STps->drv_block += blks - transfer + 1;
2008 							st_int_ioctl(STp, MTBSR, 1);
2009 							return (-EIO);
2010 						}
2011 						/* We have some data, deliver it */
2012 						STbp->buffer_bytes = (blks - transfer) *
2013 						    STp->block_size;
2014 						DEBC_printk(STp, "ILI but "
2015 							    "enough data "
2016 							    "received %ld "
2017 							    "%d.\n", count,
2018 							    STbp->buffer_bytes);
2019 						if (STps->drv_block >= 0)
2020 							STps->drv_block += 1;
2021 						if (st_int_ioctl(STp, MTBSR, 1))
2022 							return (-EIO);
2023 					}
2024 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2025 					if (STps->eof != ST_FM_HIT)
2026 						STps->eof = ST_FM_HIT;
2027 					else
2028 						STps->eof = ST_EOD_2;
2029 					if (STp->block_size == 0)
2030 						STbp->buffer_bytes = 0;
2031 					else
2032 						STbp->buffer_bytes =
2033 						    bytes - transfer * STp->block_size;
2034 					DEBC_printk(STp, "EOF detected (%d "
2035 						    "bytes read).\n",
2036 						    STbp->buffer_bytes);
2037 				} else if (cmdstatp->flags & SENSE_EOM) {
2038 					if (STps->eof == ST_FM)
2039 						STps->eof = ST_EOD_1;
2040 					else
2041 						STps->eof = ST_EOM_OK;
2042 					if (STp->block_size == 0)
2043 						STbp->buffer_bytes = bytes - transfer;
2044 					else
2045 						STbp->buffer_bytes =
2046 						    bytes - transfer * STp->block_size;
2047 
2048 					DEBC_printk(STp, "EOM detected (%d "
2049 						    "bytes read).\n",
2050 						    STbp->buffer_bytes);
2051 				}
2052 			}
2053 			/* end of EOF, EOM, ILI test */
2054 			else {	/* nonzero sense key */
2055 				DEBC_printk(STp, "Tape error while reading.\n");
2056 				STps->drv_block = (-1);
2057 				if (STps->eof == ST_FM &&
2058 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2059 					DEBC_printk(STp, "Zero returned for "
2060 						    "first BLANK CHECK "
2061 						    "after EOF.\n");
2062 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2063 				} else	/* Some other extended sense code */
2064 					retval = (-EIO);
2065 			}
2066 
2067 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2068 				STbp->buffer_bytes = 0;
2069 		}
2070 		/* End of extended sense test */
2071 		else {		/* Non-extended sense */
2072 			retval = STbp->syscall_result;
2073 		}
2074 
2075 	}
2076 	/* End of error handling */
2077 	else {			/* Read successful */
2078 		STbp->buffer_bytes = bytes;
2079 		if (STp->sili) /* In fixed block mode residual is always zero here */
2080 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2081 	}
2082 
2083 	if (STps->drv_block >= 0) {
2084 		if (STp->block_size == 0)
2085 			STps->drv_block++;
2086 		else
2087 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2088 	}
2089 	return retval;
2090 }
2091 
2092 
2093 /* Read command */
2094 static ssize_t
2095 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2096 {
2097 	ssize_t total;
2098 	ssize_t retval = 0;
2099 	ssize_t i, transfer;
2100 	int special, do_dio = 0;
2101 	struct st_request *SRpnt = NULL;
2102 	struct scsi_tape *STp = filp->private_data;
2103 	struct st_modedef *STm;
2104 	struct st_partstat *STps;
2105 	struct st_buffer *STbp = STp->buffer;
2106 
2107 	if (mutex_lock_interruptible(&STp->lock))
2108 		return -ERESTARTSYS;
2109 
2110 	retval = rw_checks(STp, filp, count);
2111 	if (retval || count == 0)
2112 		goto out;
2113 
2114 	STm = &(STp->modes[STp->current_mode]);
2115 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2116 		if (!STm->do_read_ahead) {
2117 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2118 			goto out;
2119 		}
2120 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2121 	}
2122 
2123 	STps = &(STp->ps[STp->partition]);
2124 	if (STps->rw == ST_WRITING) {
2125 		retval = flush_buffer(STp, 0);
2126 		if (retval)
2127 			goto out;
2128 		STps->rw = ST_READING;
2129 	}
2130 	DEB(
2131 	if (debugging && STps->eof != ST_NOEOF)
2132 		st_printk(ST_DEB_MSG, STp,
2133 			  "EOF/EOM flag up (%d). Bytes %d\n",
2134 			  STps->eof, STbp->buffer_bytes);
2135 	) /* end DEB */
2136 
2137 	retval = setup_buffering(STp, buf, count, 1);
2138 	if (retval)
2139 		goto out;
2140 	do_dio = STbp->do_dio;
2141 
2142 	if (STbp->buffer_bytes == 0 &&
2143 	    STps->eof >= ST_EOD_1) {
2144 		if (STps->eof < ST_EOD) {
2145 			STps->eof += 1;
2146 			retval = 0;
2147 			goto out;
2148 		}
2149 		retval = (-EIO);	/* EOM or Blank Check */
2150 		goto out;
2151 	}
2152 
2153 	if (do_dio) {
2154 		/* Check the buffer writability before any tape movement. Don't alter
2155 		   buffer data. */
2156 		if (copy_from_user(&i, buf, 1) != 0 ||
2157 		    copy_to_user(buf, &i, 1) != 0 ||
2158 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2159 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2160 			retval = (-EFAULT);
2161 			goto out;
2162 		}
2163 	}
2164 
2165 	STps->rw = ST_READING;
2166 
2167 
2168 	/* Loop until enough data in buffer or a special condition found */
2169 	for (total = 0, special = 0; total < count && !special;) {
2170 
2171 		/* Get new data if the buffer is empty */
2172 		if (STbp->buffer_bytes == 0) {
2173 			special = read_tape(STp, count - total, &SRpnt);
2174 			if (special < 0) {	/* No need to continue read */
2175 				retval = special;
2176 				goto out;
2177 			}
2178 		}
2179 
2180 		/* Move the data from driver buffer to user buffer */
2181 		if (STbp->buffer_bytes > 0) {
2182 			DEB(
2183 			if (debugging && STps->eof != ST_NOEOF)
2184 				st_printk(ST_DEB_MSG, STp,
2185 					  "EOF up (%d). Left %d, needed %d.\n",
2186 					  STps->eof, STbp->buffer_bytes,
2187 					  (int)(count - total));
2188 			) /* end DEB */
2189 			transfer = STbp->buffer_bytes < count - total ?
2190 			    STbp->buffer_bytes : count - total;
2191 			if (!do_dio) {
2192 				i = from_buffer(STbp, buf, transfer);
2193 				if (i) {
2194 					retval = i;
2195 					goto out;
2196 				}
2197 			}
2198 			buf += transfer;
2199 			total += transfer;
2200 		}
2201 
2202 		if (STp->block_size == 0)
2203 			break;	/* Read only one variable length block */
2204 
2205 	}			/* for (total = 0, special = 0;
2206                                    total < count && !special; ) */
2207 
2208 	/* Change the eof state if no data from tape or buffer */
2209 	if (total == 0) {
2210 		if (STps->eof == ST_FM_HIT) {
2211 			STps->eof = ST_FM;
2212 			STps->drv_block = 0;
2213 			if (STps->drv_file >= 0)
2214 				STps->drv_file++;
2215 		} else if (STps->eof == ST_EOD_1) {
2216 			STps->eof = ST_EOD_2;
2217 			STps->drv_block = 0;
2218 			if (STps->drv_file >= 0)
2219 				STps->drv_file++;
2220 		} else if (STps->eof == ST_EOD_2)
2221 			STps->eof = ST_EOD;
2222 	} else if (STps->eof == ST_FM)
2223 		STps->eof = ST_NOEOF;
2224 	retval = total;
2225 
2226  out:
2227 	if (SRpnt != NULL) {
2228 		st_release_request(SRpnt);
2229 		SRpnt = NULL;
2230 	}
2231 	if (do_dio) {
2232 		release_buffering(STp, 1);
2233 		STbp->buffer_bytes = 0;
2234 	}
2235 	mutex_unlock(&STp->lock);
2236 
2237 	return retval;
2238 }
2239 
2240 
2241 
2242 DEB(
2243 /* Set the driver options */
2244 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2245 {
2246 	if (debugging) {
2247 		st_printk(KERN_INFO, STp,
2248 			  "Mode %d options: buffer writes: %d, "
2249 			  "async writes: %d, read ahead: %d\n",
2250 			  STp->current_mode, STm->do_buffer_writes,
2251 			  STm->do_async_writes, STm->do_read_ahead);
2252 		st_printk(KERN_INFO, STp,
2253 			  "    can bsr: %d, two FMs: %d, "
2254 			  "fast mteom: %d, auto lock: %d,\n",
2255 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2256 			  STp->do_auto_lock);
2257 		st_printk(KERN_INFO, STp,
2258 			  "    defs for wr: %d, no block limits: %d, "
2259 			  "partitions: %d, s2 log: %d\n",
2260 			  STm->defaults_for_writes, STp->omit_blklims,
2261 			  STp->can_partitions, STp->scsi2_logical);
2262 		st_printk(KERN_INFO, STp,
2263 			  "    sysv: %d nowait: %d sili: %d "
2264 			  "nowait_filemark: %d\n",
2265 			  STm->sysv, STp->immediate, STp->sili,
2266 			  STp->immediate_filemark);
2267 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2268 	}
2269 }
2270 	)
2271 
2272 
2273 static int st_set_options(struct scsi_tape *STp, long options)
2274 {
2275 	int value;
2276 	long code;
2277 	struct st_modedef *STm;
2278 	struct cdev *cd0, *cd1;
2279 	struct device *d0, *d1;
2280 
2281 	STm = &(STp->modes[STp->current_mode]);
2282 	if (!STm->defined) {
2283 		cd0 = STm->cdevs[0];
2284 		cd1 = STm->cdevs[1];
2285 		d0  = STm->devs[0];
2286 		d1  = STm->devs[1];
2287 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2288 		STm->cdevs[0] = cd0;
2289 		STm->cdevs[1] = cd1;
2290 		STm->devs[0]  = d0;
2291 		STm->devs[1]  = d1;
2292 		modes_defined = 1;
2293 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2294 			    STp->current_mode);
2295 	}
2296 
2297 	code = options & MT_ST_OPTIONS;
2298 	if (code == MT_ST_BOOLEANS) {
2299 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2300 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2301 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2302 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2303 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2304 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2305 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2306 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2307 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2308 		if ((STp->device)->scsi_level >= SCSI_2)
2309 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2310 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2311 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2312 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2313 		STm->sysv = (options & MT_ST_SYSV) != 0;
2314 		STp->sili = (options & MT_ST_SILI) != 0;
2315 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2316 		     st_log_options(STp, STm); )
2317 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2318 		value = (code == MT_ST_SETBOOLEANS);
2319 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2320 			STm->do_buffer_writes = value;
2321 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2322 			STm->do_async_writes = value;
2323 		if ((options & MT_ST_DEF_WRITES) != 0)
2324 			STm->defaults_for_writes = value;
2325 		if ((options & MT_ST_READ_AHEAD) != 0)
2326 			STm->do_read_ahead = value;
2327 		if ((options & MT_ST_TWO_FM) != 0)
2328 			STp->two_fm = value;
2329 		if ((options & MT_ST_FAST_MTEOM) != 0)
2330 			STp->fast_mteom = value;
2331 		if ((options & MT_ST_AUTO_LOCK) != 0)
2332 			STp->do_auto_lock = value;
2333 		if ((options & MT_ST_CAN_BSR) != 0)
2334 			STp->can_bsr = value;
2335 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2336 			STp->omit_blklims = value;
2337 		if ((STp->device)->scsi_level >= SCSI_2 &&
2338 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2339 			STp->can_partitions = value;
2340 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2341 			STp->scsi2_logical = value;
2342 		if ((options & MT_ST_NOWAIT) != 0)
2343 			STp->immediate = value;
2344 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2345 			STp->immediate_filemark = value;
2346 		if ((options & MT_ST_SYSV) != 0)
2347 			STm->sysv = value;
2348 		if ((options & MT_ST_SILI) != 0)
2349 			STp->sili = value;
2350 		DEB(
2351 		if ((options & MT_ST_DEBUGGING) != 0)
2352 			debugging = value;
2353 			st_log_options(STp, STm); )
2354 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2355 		/* Retained for compatibility */
2356 	} else if (code == MT_ST_DEF_BLKSIZE) {
2357 		value = (options & ~MT_ST_OPTIONS);
2358 		if (value == ~MT_ST_OPTIONS) {
2359 			STm->default_blksize = (-1);
2360 			DEBC_printk(STp, "Default block size disabled.\n");
2361 		} else {
2362 			STm->default_blksize = value;
2363 			DEBC_printk(STp,"Default block size set to "
2364 				    "%d bytes.\n", STm->default_blksize);
2365 			if (STp->ready == ST_READY) {
2366 				STp->blksize_changed = 0;
2367 				set_mode_densblk(STp, STm);
2368 			}
2369 		}
2370 	} else if (code == MT_ST_TIMEOUTS) {
2371 		value = (options & ~MT_ST_OPTIONS);
2372 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2373 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2374 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2375 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2376 		} else {
2377 			blk_queue_rq_timeout(STp->device->request_queue,
2378 					     value * HZ);
2379 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2380 				    value);
2381 		}
2382 	} else if (code == MT_ST_SET_CLN) {
2383 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2384 		if (value != 0 &&
2385 			(value < EXTENDED_SENSE_START ||
2386 				value >= SCSI_SENSE_BUFFERSIZE))
2387 			return (-EINVAL);
2388 		STp->cln_mode = value;
2389 		STp->cln_sense_mask = (options >> 8) & 0xff;
2390 		STp->cln_sense_value = (options >> 16) & 0xff;
2391 		st_printk(KERN_INFO, STp,
2392 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2393 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2394 	} else if (code == MT_ST_DEF_OPTIONS) {
2395 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2396 		value = (options & MT_ST_CLEAR_DEFAULT);
2397 		if (code == MT_ST_DEF_DENSITY) {
2398 			if (value == MT_ST_CLEAR_DEFAULT) {
2399 				STm->default_density = (-1);
2400 				DEBC_printk(STp,
2401 					    "Density default disabled.\n");
2402 			} else {
2403 				STm->default_density = value & 0xff;
2404 				DEBC_printk(STp, "Density default set to %x\n",
2405 					    STm->default_density);
2406 				if (STp->ready == ST_READY) {
2407 					STp->density_changed = 0;
2408 					set_mode_densblk(STp, STm);
2409 				}
2410 			}
2411 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2412 			if (value == MT_ST_CLEAR_DEFAULT) {
2413 				STp->default_drvbuffer = 0xff;
2414 				DEBC_printk(STp,
2415 					    "Drive buffer default disabled.\n");
2416 			} else {
2417 				STp->default_drvbuffer = value & 7;
2418 				DEBC_printk(STp,
2419 					    "Drive buffer default set to %x\n",
2420 					    STp->default_drvbuffer);
2421 				if (STp->ready == ST_READY)
2422 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2423 			}
2424 		} else if (code == MT_ST_DEF_COMPRESSION) {
2425 			if (value == MT_ST_CLEAR_DEFAULT) {
2426 				STm->default_compression = ST_DONT_TOUCH;
2427 				DEBC_printk(STp,
2428 					    "Compression default disabled.\n");
2429 			} else {
2430 				if ((value & 0xff00) != 0) {
2431 					STp->c_algo = (value & 0xff00) >> 8;
2432 					DEBC_printk(STp, "Compression "
2433 						    "algorithm set to 0x%x.\n",
2434 						    STp->c_algo);
2435 				}
2436 				if ((value & 0xff) != 0xff) {
2437 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2438 					DEBC_printk(STp, "Compression default "
2439 						    "set to %x\n",
2440 						    (value & 1));
2441 					if (STp->ready == ST_READY) {
2442 						STp->compression_changed = 0;
2443 						st_compression(STp, (STm->default_compression == ST_YES));
2444 					}
2445 				}
2446 			}
2447 		}
2448 	} else
2449 		return (-EIO);
2450 
2451 	return 0;
2452 }
2453 
2454 #define MODE_HEADER_LENGTH  4
2455 
2456 /* Mode header and page byte offsets */
2457 #define MH_OFF_DATA_LENGTH     0
2458 #define MH_OFF_MEDIUM_TYPE     1
2459 #define MH_OFF_DEV_SPECIFIC    2
2460 #define MH_OFF_BDESCS_LENGTH   3
2461 #define MP_OFF_PAGE_NBR        0
2462 #define MP_OFF_PAGE_LENGTH     1
2463 
2464 /* Mode header and page bit masks */
2465 #define MH_BIT_WP              0x80
2466 #define MP_MSK_PAGE_NBR        0x3f
2467 
2468 /* Don't return block descriptors */
2469 #define MODE_SENSE_OMIT_BDESCS 0x08
2470 
2471 #define MODE_SELECT_PAGE_FORMAT 0x10
2472 
2473 /* Read a mode page into the tape buffer. The block descriptors are included
2474    if incl_block_descs is true. The page control is ored to the page number
2475    parameter, if necessary. */
2476 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2477 {
2478 	unsigned char cmd[MAX_COMMAND_SIZE];
2479 	struct st_request *SRpnt;
2480 
2481 	memset(cmd, 0, MAX_COMMAND_SIZE);
2482 	cmd[0] = MODE_SENSE;
2483 	if (omit_block_descs)
2484 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2485 	cmd[2] = page;
2486 	cmd[4] = 255;
2487 
2488 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2489 			   STp->device->request_queue->rq_timeout, 0, 1);
2490 	if (SRpnt == NULL)
2491 		return (STp->buffer)->syscall_result;
2492 
2493 	st_release_request(SRpnt);
2494 
2495 	return STp->buffer->syscall_result;
2496 }
2497 
2498 
2499 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2500    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2501 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2502 {
2503 	int pgo;
2504 	unsigned char cmd[MAX_COMMAND_SIZE];
2505 	struct st_request *SRpnt;
2506 	int timeout;
2507 
2508 	memset(cmd, 0, MAX_COMMAND_SIZE);
2509 	cmd[0] = MODE_SELECT;
2510 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2511 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2512 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2513 
2514 	/* Clear reserved fields */
2515 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2516 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2517 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2518 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2519 
2520 	timeout = slow ?
2521 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2522 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2523 			   timeout, 0, 1);
2524 	if (SRpnt == NULL)
2525 		return (STp->buffer)->syscall_result;
2526 
2527 	st_release_request(SRpnt);
2528 
2529 	return STp->buffer->syscall_result;
2530 }
2531 
2532 
2533 #define COMPRESSION_PAGE        0x0f
2534 #define COMPRESSION_PAGE_LENGTH 16
2535 
2536 #define CP_OFF_DCE_DCC          2
2537 #define CP_OFF_C_ALGO           7
2538 
2539 #define DCE_MASK  0x80
2540 #define DCC_MASK  0x40
2541 #define RED_MASK  0x60
2542 
2543 
2544 /* Control the compression with mode page 15. Algorithm not changed if zero.
2545 
2546    The block descriptors are read and written because Sony SDT-7000 does not
2547    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2548    Including block descriptors should not cause any harm to other drives. */
2549 
2550 static int st_compression(struct scsi_tape * STp, int state)
2551 {
2552 	int retval;
2553 	int mpoffs;  /* Offset to mode page start */
2554 	unsigned char *b_data = (STp->buffer)->b_data;
2555 
2556 	if (STp->ready != ST_READY)
2557 		return (-EIO);
2558 
2559 	/* Read the current page contents */
2560 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2561 	if (retval) {
2562 		DEBC_printk(STp, "Compression mode page not supported.\n");
2563 		return (-EIO);
2564 	}
2565 
2566 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2567 	DEBC_printk(STp, "Compression state is %d.\n",
2568 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2569 
2570 	/* Check if compression can be changed */
2571 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2572 		DEBC_printk(STp, "Compression not supported.\n");
2573 		return (-EIO);
2574 	}
2575 
2576 	/* Do the change */
2577 	if (state) {
2578 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2579 		if (STp->c_algo != 0)
2580 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2581 	}
2582 	else {
2583 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2584 		if (STp->c_algo != 0)
2585 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2586 	}
2587 
2588 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2589 	if (retval) {
2590 		DEBC_printk(STp, "Compression change failed.\n");
2591 		return (-EIO);
2592 	}
2593 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2594 
2595 	STp->compression_changed = 1;
2596 	return 0;
2597 }
2598 
2599 
2600 /* Process the load and unload commands (does unload if the load code is zero) */
2601 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2602 {
2603 	int retval = (-EIO), timeout;
2604 	unsigned char cmd[MAX_COMMAND_SIZE];
2605 	struct st_partstat *STps;
2606 	struct st_request *SRpnt;
2607 
2608 	if (STp->ready != ST_READY && !load_code) {
2609 		if (STp->ready == ST_NO_TAPE)
2610 			return (-ENOMEDIUM);
2611 		else
2612 			return (-EIO);
2613 	}
2614 
2615 	memset(cmd, 0, MAX_COMMAND_SIZE);
2616 	cmd[0] = START_STOP;
2617 	if (load_code)
2618 		cmd[4] |= 1;
2619 	/*
2620 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2621 	 */
2622 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2623 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2624 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2625 			    (cmd[4]) ? "" : "un",
2626 			    load_code - MT_ST_HPLOADER_OFFSET);
2627 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2628 	}
2629 	if (STp->immediate) {
2630 		cmd[1] = 1;	/* Don't wait for completion */
2631 		timeout = STp->device->request_queue->rq_timeout;
2632 	}
2633 	else
2634 		timeout = STp->long_timeout;
2635 
2636 	DEBC(
2637 		if (!load_code)
2638 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2639 		else
2640 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2641 		);
2642 
2643 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2644 			   timeout, MAX_RETRIES, 1);
2645 	if (!SRpnt)
2646 		return (STp->buffer)->syscall_result;
2647 
2648 	retval = (STp->buffer)->syscall_result;
2649 	st_release_request(SRpnt);
2650 
2651 	if (!retval) {	/* SCSI command successful */
2652 
2653 		if (!load_code) {
2654 			STp->rew_at_close = 0;
2655 			STp->ready = ST_NO_TAPE;
2656 		}
2657 		else {
2658 			STp->rew_at_close = STp->autorew_dev;
2659 			retval = check_tape(STp, filp);
2660 			if (retval > 0)
2661 				retval = 0;
2662 		}
2663 	}
2664 	else {
2665 		STps = &(STp->ps[STp->partition]);
2666 		STps->drv_file = STps->drv_block = (-1);
2667 	}
2668 
2669 	return retval;
2670 }
2671 
2672 #if DEBUG
2673 #define ST_DEB_FORWARD  0
2674 #define ST_DEB_BACKWARD 1
2675 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2676 {
2677 	s32 sc;
2678 
2679 	if (!debugging)
2680 		return;
2681 
2682 	sc = sign_extend32(get_unaligned_be24(&cmd[2]), 23);
2683 	if (direction)
2684 		sc = -sc;
2685 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2686 		  direction ? "backward" : "forward", sc, units);
2687 }
2688 #else
2689 #define ST_DEB_FORWARD  0
2690 #define ST_DEB_BACKWARD 1
2691 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2692 #endif
2693 
2694 
2695 /* Internal ioctl function */
2696 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2697 {
2698 	int timeout;
2699 	long ltmp;
2700 	int ioctl_result;
2701 	int chg_eof = 1;
2702 	unsigned char cmd[MAX_COMMAND_SIZE];
2703 	struct st_request *SRpnt;
2704 	struct st_partstat *STps;
2705 	int fileno, blkno, at_sm, undone;
2706 	int datalen = 0, direction = DMA_NONE;
2707 
2708 	WARN_ON(STp->buffer->do_dio != 0);
2709 	if (STp->ready != ST_READY) {
2710 		if (STp->ready == ST_NO_TAPE)
2711 			return (-ENOMEDIUM);
2712 		else
2713 			return (-EIO);
2714 	}
2715 	timeout = STp->long_timeout;
2716 	STps = &(STp->ps[STp->partition]);
2717 	fileno = STps->drv_file;
2718 	blkno = STps->drv_block;
2719 	at_sm = STps->at_sm;
2720 
2721 	memset(cmd, 0, MAX_COMMAND_SIZE);
2722 	switch (cmd_in) {
2723 	case MTFSFM:
2724 		chg_eof = 0;	/* Changed from the FSF after this */
2725 		fallthrough;
2726 	case MTFSF:
2727 		cmd[0] = SPACE;
2728 		cmd[1] = 0x01;	/* Space FileMarks */
2729 		cmd[2] = (arg >> 16);
2730 		cmd[3] = (arg >> 8);
2731 		cmd[4] = arg;
2732 		deb_space_print(STp, ST_DEB_FORWARD, "filemarks", cmd);
2733 		if (fileno >= 0)
2734 			fileno += arg;
2735 		blkno = 0;
2736 		at_sm &= (arg == 0);
2737 		break;
2738 	case MTBSFM:
2739 		chg_eof = 0;	/* Changed from the FSF after this */
2740 		fallthrough;
2741 	case MTBSF:
2742 		cmd[0] = SPACE;
2743 		cmd[1] = 0x01;	/* Space FileMarks */
2744 		ltmp = (-arg);
2745 		cmd[2] = (ltmp >> 16);
2746 		cmd[3] = (ltmp >> 8);
2747 		cmd[4] = ltmp;
2748 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2749 		if (fileno >= 0)
2750 			fileno -= arg;
2751 		blkno = (-1);	/* We can't know the block number */
2752 		at_sm &= (arg == 0);
2753 		break;
2754 	case MTFSR:
2755 		cmd[0] = SPACE;
2756 		cmd[1] = 0x00;	/* Space Blocks */
2757 		cmd[2] = (arg >> 16);
2758 		cmd[3] = (arg >> 8);
2759 		cmd[4] = arg;
2760 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2761 		if (blkno >= 0)
2762 			blkno += arg;
2763 		at_sm &= (arg == 0);
2764 		break;
2765 	case MTBSR:
2766 		cmd[0] = SPACE;
2767 		cmd[1] = 0x00;	/* Space Blocks */
2768 		ltmp = (-arg);
2769 		cmd[2] = (ltmp >> 16);
2770 		cmd[3] = (ltmp >> 8);
2771 		cmd[4] = ltmp;
2772 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2773 		if (blkno >= 0)
2774 			blkno -= arg;
2775 		at_sm &= (arg == 0);
2776 		break;
2777 	case MTFSS:
2778 		cmd[0] = SPACE;
2779 		cmd[1] = 0x04;	/* Space Setmarks */
2780 		cmd[2] = (arg >> 16);
2781 		cmd[3] = (arg >> 8);
2782 		cmd[4] = arg;
2783 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2784 		if (arg != 0) {
2785 			blkno = fileno = (-1);
2786 			at_sm = 1;
2787 		}
2788 		break;
2789 	case MTBSS:
2790 		cmd[0] = SPACE;
2791 		cmd[1] = 0x04;	/* Space Setmarks */
2792 		ltmp = (-arg);
2793 		cmd[2] = (ltmp >> 16);
2794 		cmd[3] = (ltmp >> 8);
2795 		cmd[4] = ltmp;
2796 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2797 		if (arg != 0) {
2798 			blkno = fileno = (-1);
2799 			at_sm = 1;
2800 		}
2801 		break;
2802 	case MTWEOF:
2803 	case MTWEOFI:
2804 	case MTWSM:
2805 		if (STp->write_prot)
2806 			return (-EACCES);
2807 		cmd[0] = WRITE_FILEMARKS;
2808 		if (cmd_in == MTWSM)
2809 			cmd[1] = 2;
2810 		if (cmd_in == MTWEOFI ||
2811 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2812 			cmd[1] |= 1;
2813 		cmd[2] = (arg >> 16);
2814 		cmd[3] = (arg >> 8);
2815 		cmd[4] = arg;
2816 		timeout = STp->device->request_queue->rq_timeout;
2817 		DEBC(
2818 			if (cmd_in != MTWSM)
2819 				st_printk(ST_DEB_MSG, STp,
2820 					  "Writing %d filemarks.\n",
2821 					  cmd[2] * 65536 +
2822 					  cmd[3] * 256 +
2823 					  cmd[4]);
2824 			else
2825 				st_printk(ST_DEB_MSG, STp,
2826 					  "Writing %d setmarks.\n",
2827 					  cmd[2] * 65536 +
2828 					  cmd[3] * 256 +
2829 					  cmd[4]);
2830 		)
2831 		if (fileno >= 0)
2832 			fileno += arg;
2833 		blkno = 0;
2834 		at_sm = (cmd_in == MTWSM);
2835 		break;
2836 	case MTREW:
2837 		cmd[0] = REZERO_UNIT;
2838 		if (STp->immediate) {
2839 			cmd[1] = 1;	/* Don't wait for completion */
2840 			timeout = STp->device->request_queue->rq_timeout;
2841 		}
2842 		DEBC_printk(STp, "Rewinding tape.\n");
2843 		fileno = blkno = at_sm = 0;
2844 		break;
2845 	case MTNOP:
2846 		DEBC_printk(STp, "No op on tape.\n");
2847 		return 0;	/* Should do something ? */
2848 	case MTRETEN:
2849 		cmd[0] = START_STOP;
2850 		if (STp->immediate) {
2851 			cmd[1] = 1;	/* Don't wait for completion */
2852 			timeout = STp->device->request_queue->rq_timeout;
2853 		}
2854 		cmd[4] = 3;
2855 		DEBC_printk(STp, "Retensioning tape.\n");
2856 		fileno = blkno = at_sm = 0;
2857 		break;
2858 	case MTEOM:
2859 		if (!STp->fast_mteom) {
2860 			/* space to the end of tape */
2861 			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
2862 			fileno = STps->drv_file;
2863 			if (STps->eof >= ST_EOD_1)
2864 				return 0;
2865 			/* The next lines would hide the number of spaced FileMarks
2866 			   That's why I inserted the previous lines. I had no luck
2867 			   with detecting EOM with FSF, so we go now to EOM.
2868 			   Joerg Weule */
2869 		} else
2870 			fileno = (-1);
2871 		cmd[0] = SPACE;
2872 		cmd[1] = 3;
2873 		DEBC_printk(STp, "Spacing to end of recorded medium.\n");
2874 		blkno = -1;
2875 		at_sm = 0;
2876 		break;
2877 	case MTERASE:
2878 		if (STp->write_prot)
2879 			return (-EACCES);
2880 		cmd[0] = ERASE;
2881 		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
2882 		if (STp->immediate) {
2883 			cmd[1] |= 2;	/* Don't wait for completion */
2884 			timeout = STp->device->request_queue->rq_timeout;
2885 		}
2886 		else
2887 			timeout = STp->long_timeout * 8;
2888 
2889 		DEBC_printk(STp, "Erasing tape.\n");
2890 		fileno = blkno = at_sm = 0;
2891 		break;
2892 	case MTSETBLK:		/* Set block length */
2893 	case MTSETDENSITY:	/* Set tape density */
2894 	case MTSETDRVBUFFER:	/* Set drive buffering */
2895 	case SET_DENS_AND_BLK:	/* Set density and block size */
2896 		chg_eof = 0;
2897 		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
2898 			return (-EIO);	/* Not allowed if data in buffer */
2899 		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
2900 		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
2901 		    STp->max_block > 0 &&
2902 		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
2903 		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
2904 			st_printk(KERN_WARNING, STp, "Illegal block size.\n");
2905 			return (-EINVAL);
2906 		}
2907 		cmd[0] = MODE_SELECT;
2908 		if ((STp->use_pf & USE_PF))
2909 			cmd[1] = MODE_SELECT_PAGE_FORMAT;
2910 		cmd[4] = datalen = 12;
2911 		direction = DMA_TO_DEVICE;
2912 
2913 		memset((STp->buffer)->b_data, 0, 12);
2914 		if (cmd_in == MTSETDRVBUFFER)
2915 			(STp->buffer)->b_data[2] = (arg & 7) << 4;
2916 		else
2917 			(STp->buffer)->b_data[2] =
2918 			    STp->drv_buffer << 4;
2919 		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
2920 		if (cmd_in == MTSETDENSITY) {
2921 			(STp->buffer)->b_data[4] = arg;
2922 			STp->density_changed = 1;	/* At least we tried ;-) */
2923 		} else if (cmd_in == SET_DENS_AND_BLK)
2924 			(STp->buffer)->b_data[4] = arg >> 24;
2925 		else
2926 			(STp->buffer)->b_data[4] = STp->density;
2927 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2928 			ltmp = arg & MT_ST_BLKSIZE_MASK;
2929 			if (cmd_in == MTSETBLK)
2930 				STp->blksize_changed = 1; /* At least we tried ;-) */
2931 		} else
2932 			ltmp = STp->block_size;
2933 		(STp->buffer)->b_data[9] = (ltmp >> 16);
2934 		(STp->buffer)->b_data[10] = (ltmp >> 8);
2935 		(STp->buffer)->b_data[11] = ltmp;
2936 		timeout = STp->device->request_queue->rq_timeout;
2937 		DEBC(
2938 			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
2939 				st_printk(ST_DEB_MSG, STp,
2940 					  "Setting block size to %d bytes.\n",
2941 					  (STp->buffer)->b_data[9] * 65536 +
2942 					  (STp->buffer)->b_data[10] * 256 +
2943 					  (STp->buffer)->b_data[11]);
2944 			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
2945 				st_printk(ST_DEB_MSG, STp,
2946 					  "Setting density code to %x.\n",
2947 					  (STp->buffer)->b_data[4]);
2948 			if (cmd_in == MTSETDRVBUFFER)
2949 				st_printk(ST_DEB_MSG, STp,
2950 					  "Setting drive buffer code to %d.\n",
2951 					  ((STp->buffer)->b_data[2] >> 4) & 7);
2952 		)
2953 		break;
2954 	default:
2955 		return (-ENOSYS);
2956 	}
2957 
2958 	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
2959 			   timeout, MAX_RETRIES, 1);
2960 	if (!SRpnt)
2961 		return (STp->buffer)->syscall_result;
2962 
2963 	ioctl_result = (STp->buffer)->syscall_result;
2964 
2965 	if (!ioctl_result) {	/* SCSI command successful */
2966 		st_release_request(SRpnt);
2967 		SRpnt = NULL;
2968 		STps->drv_block = blkno;
2969 		STps->drv_file = fileno;
2970 		STps->at_sm = at_sm;
2971 
2972 		if (cmd_in == MTBSFM)
2973 			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
2974 		else if (cmd_in == MTFSFM)
2975 			ioctl_result = st_int_ioctl(STp, MTBSF, 1);
2976 
2977 		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
2978 			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
2979 			if (STp->block_size != 0) {
2980 				(STp->buffer)->buffer_blocks =
2981 				    (STp->buffer)->buffer_size / STp->block_size;
2982 			}
2983 			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
2984 			if (cmd_in == SET_DENS_AND_BLK)
2985 				STp->density = arg >> MT_ST_DENSITY_SHIFT;
2986 		} else if (cmd_in == MTSETDRVBUFFER)
2987 			STp->drv_buffer = (arg & 7);
2988 		else if (cmd_in == MTSETDENSITY)
2989 			STp->density = arg;
2990 
2991 		if (cmd_in == MTEOM)
2992 			STps->eof = ST_EOD;
2993 		else if (cmd_in == MTFSF)
2994 			STps->eof = ST_FM;
2995 		else if (chg_eof)
2996 			STps->eof = ST_NOEOF;
2997 
2998 		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
2999 			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
3000 	} else { /* SCSI command was not completely successful. Don't return
3001                     from this block without releasing the SCSI command block! */
3002 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
3003 
3004 		if (cmdstatp->flags & SENSE_EOM) {
3005 			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
3006 			    cmd_in != MTBSR && cmd_in != MTBSS)
3007 				STps->eof = ST_EOM_OK;
3008 			STps->drv_block = 0;
3009 		}
3010 
3011 		if (cmdstatp->remainder_valid)
3012 			undone = (int)cmdstatp->uremainder64;
3013 		else
3014 			undone = 0;
3015 
3016 		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
3017 		    cmdstatp->have_sense &&
3018 		    (cmdstatp->flags & SENSE_EOM)) {
3019 			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
3020 			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
3021 				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
3022 				STps->eof = ST_NOEOF;
3023 			} else {  /* Writing EOF(s) failed */
3024 				if (fileno >= 0)
3025 					fileno -= undone;
3026 				if (undone < arg)
3027 					STps->eof = ST_NOEOF;
3028 			}
3029 			STps->drv_file = fileno;
3030 		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
3031 			if (fileno >= 0)
3032 				STps->drv_file = fileno - undone;
3033 			else
3034 				STps->drv_file = fileno;
3035 			STps->drv_block = -1;
3036 			STps->eof = ST_NOEOF;
3037 		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
3038 			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3039 				undone = (-undone);
3040 			if (STps->drv_file >= 0)
3041 				STps->drv_file = fileno + undone;
3042 			STps->drv_block = 0;
3043 			STps->eof = ST_NOEOF;
3044 		} else if (cmd_in == MTFSR) {
3045 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3046 				if (STps->drv_file >= 0)
3047 					STps->drv_file++;
3048 				STps->drv_block = 0;
3049 				STps->eof = ST_FM;
3050 			} else {
3051 				if (blkno >= undone)
3052 					STps->drv_block = blkno - undone;
3053 				else
3054 					STps->drv_block = (-1);
3055 				STps->eof = ST_NOEOF;
3056 			}
3057 		} else if (cmd_in == MTBSR) {
3058 			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
3059 				STps->drv_file--;
3060 				STps->drv_block = (-1);
3061 			} else {
3062 				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
3063 					undone = (-undone);
3064 				if (STps->drv_block >= 0)
3065 					STps->drv_block = blkno + undone;
3066 			}
3067 			STps->eof = ST_NOEOF;
3068 		} else if (cmd_in == MTEOM) {
3069 			STps->drv_file = (-1);
3070 			STps->drv_block = (-1);
3071 			STps->eof = ST_EOD;
3072 		} else if (cmd_in == MTSETBLK ||
3073 			   cmd_in == MTSETDENSITY ||
3074 			   cmd_in == MTSETDRVBUFFER ||
3075 			   cmd_in == SET_DENS_AND_BLK) {
3076 			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
3077 			    !(STp->use_pf & PF_TESTED)) {
3078 				/* Try the other possible state of Page Format if not
3079 				   already tried */
3080 				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
3081 				st_release_request(SRpnt);
3082 				SRpnt = NULL;
3083 				return st_int_ioctl(STp, cmd_in, arg);
3084 			}
3085 		} else if (chg_eof)
3086 			STps->eof = ST_NOEOF;
3087 
3088 		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
3089 			STps->eof = ST_EOD;
3090 
3091 		st_release_request(SRpnt);
3092 		SRpnt = NULL;
3093 	}
3094 
3095 	return ioctl_result;
3096 }
3097 
3098 
3099 /* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
3100    structure. */
3101 
3102 static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
3103 			int logical)
3104 {
3105 	int result;
3106 	unsigned char scmd[MAX_COMMAND_SIZE];
3107 	struct st_request *SRpnt;
3108 
3109 	if (STp->ready != ST_READY)
3110 		return (-EIO);
3111 
3112 	memset(scmd, 0, MAX_COMMAND_SIZE);
3113 	if ((STp->device)->scsi_level < SCSI_2) {
3114 		scmd[0] = QFA_REQUEST_BLOCK;
3115 		scmd[4] = 3;
3116 	} else {
3117 		scmd[0] = READ_POSITION;
3118 		if (!logical && !STp->scsi2_logical)
3119 			scmd[1] = 1;
3120 	}
3121 	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
3122 			   STp->device->request_queue->rq_timeout,
3123 			   MAX_READY_RETRIES, 1);
3124 	if (!SRpnt)
3125 		return (STp->buffer)->syscall_result;
3126 
3127 	if ((STp->buffer)->syscall_result != 0 ||
3128 	    (STp->device->scsi_level >= SCSI_2 &&
3129 	     ((STp->buffer)->b_data[0] & 4) != 0)) {
3130 		*block = *partition = 0;
3131 		DEBC_printk(STp, " Can't read tape position.\n");
3132 		result = (-EIO);
3133 	} else {
3134 		result = 0;
3135 		if ((STp->device)->scsi_level < SCSI_2) {
3136 			*block = ((STp->buffer)->b_data[0] << 16)
3137 			    + ((STp->buffer)->b_data[1] << 8)
3138 			    + (STp->buffer)->b_data[2];
3139 			*partition = 0;
3140 		} else {
3141 			*block = ((STp->buffer)->b_data[4] << 24)
3142 			    + ((STp->buffer)->b_data[5] << 16)
3143 			    + ((STp->buffer)->b_data[6] << 8)
3144 			    + (STp->buffer)->b_data[7];
3145 			*partition = (STp->buffer)->b_data[1];
3146 			if (((STp->buffer)->b_data[0] & 0x80) &&
3147 			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
3148 				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
3149 		}
3150 		DEBC_printk(STp, "Got tape pos. blk %d part %d.\n",
3151 			    *block, *partition);
3152 	}
3153 	st_release_request(SRpnt);
3154 	SRpnt = NULL;
3155 
3156 	return result;
3157 }
3158 
3159 
3160 /* Set the tape block and partition. Negative partition means that only the
3161    block should be set in vendor specific way. */
3162 static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
3163 			int logical)
3164 {
3165 	struct st_partstat *STps;
3166 	int result, p;
3167 	unsigned int blk;
3168 	int timeout;
3169 	unsigned char scmd[MAX_COMMAND_SIZE];
3170 	struct st_request *SRpnt;
3171 
3172 	if (STp->ready != ST_READY)
3173 		return (-EIO);
3174 	timeout = STp->long_timeout;
3175 	STps = &(STp->ps[STp->partition]);
3176 
3177 	DEBC_printk(STp, "Setting block to %d and partition to %d.\n",
3178 		    block, partition);
3179 	DEB(if (partition < 0)
3180 		return (-EIO); )
3181 
3182 	/* Update the location at the partition we are leaving */
3183 	if ((!STp->can_partitions && partition != 0) ||
3184 	    partition >= ST_NBR_PARTITIONS)
3185 		return (-EINVAL);
3186 	if (partition != STp->partition) {
3187 		if (get_location(STp, &blk, &p, 1))
3188 			STps->last_block_valid = 0;
3189 		else {
3190 			STps->last_block_valid = 1;
3191 			STps->last_block_visited = blk;
3192 			DEBC_printk(STp, "Visited block %d for "
3193 				    "partition %d saved.\n",
3194 				    blk, STp->partition);
3195 		}
3196 	}
3197 
3198 	memset(scmd, 0, MAX_COMMAND_SIZE);
3199 	if ((STp->device)->scsi_level < SCSI_2) {
3200 		scmd[0] = QFA_SEEK_BLOCK;
3201 		scmd[2] = (block >> 16);
3202 		scmd[3] = (block >> 8);
3203 		scmd[4] = block;
3204 		scmd[5] = 0;
3205 	} else {
3206 		scmd[0] = SEEK_10;
3207 		scmd[3] = (block >> 24);
3208 		scmd[4] = (block >> 16);
3209 		scmd[5] = (block >> 8);
3210 		scmd[6] = block;
3211 		if (!logical && !STp->scsi2_logical)
3212 			scmd[1] = 4;
3213 		if (STp->partition != partition) {
3214 			scmd[1] |= 2;
3215 			scmd[8] = partition;
3216 			DEBC_printk(STp, "Trying to change partition "
3217 				    "from %d to %d\n", STp->partition,
3218 				    partition);
3219 		}
3220 	}
3221 	if (STp->immediate) {
3222 		scmd[1] |= 1;		/* Don't wait for completion */
3223 		timeout = STp->device->request_queue->rq_timeout;
3224 	}
3225 
3226 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3227 			   timeout, MAX_READY_RETRIES, 1);
3228 	if (!SRpnt)
3229 		return (STp->buffer)->syscall_result;
3230 
3231 	STps->drv_block = STps->drv_file = (-1);
3232 	STps->eof = ST_NOEOF;
3233 	if ((STp->buffer)->syscall_result != 0) {
3234 		result = (-EIO);
3235 		if (STp->can_partitions &&
3236 		    (STp->device)->scsi_level >= SCSI_2 &&
3237 		    (p = find_partition(STp)) >= 0)
3238 			STp->partition = p;
3239 	} else {
3240 		if (STp->can_partitions) {
3241 			STp->partition = partition;
3242 			STps = &(STp->ps[partition]);
3243 			if (!STps->last_block_valid ||
3244 			    STps->last_block_visited != block) {
3245 				STps->at_sm = 0;
3246 				STps->rw = ST_IDLE;
3247 			}
3248 		} else
3249 			STps->at_sm = 0;
3250 		if (block == 0)
3251 			STps->drv_block = STps->drv_file = 0;
3252 		result = 0;
3253 	}
3254 
3255 	st_release_request(SRpnt);
3256 	SRpnt = NULL;
3257 
3258 	return result;
3259 }
3260 
3261 
3262 /* Find the current partition number for the drive status. Called from open and
3263    returns either partition number of negative error code. */
3264 static int find_partition(struct scsi_tape *STp)
3265 {
3266 	int i, partition;
3267 	unsigned int block;
3268 
3269 	if ((i = get_location(STp, &block, &partition, 1)) < 0)
3270 		return i;
3271 	if (partition >= ST_NBR_PARTITIONS)
3272 		return (-EIO);
3273 	return partition;
3274 }
3275 
3276 
3277 /* Change the partition if necessary */
3278 static int switch_partition(struct scsi_tape *STp)
3279 {
3280 	struct st_partstat *STps;
3281 
3282 	if (STp->partition == STp->new_partition)
3283 		return 0;
3284 	STps = &(STp->ps[STp->new_partition]);
3285 	if (!STps->last_block_valid)
3286 		STps->last_block_visited = 0;
3287 	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
3288 }
3289 
3290 /* Functions for reading and writing the medium partition mode page. */
3291 
3292 #define PART_PAGE   0x11
3293 #define PART_PAGE_FIXED_LENGTH 8
3294 
3295 #define PP_OFF_MAX_ADD_PARTS   2
3296 #define PP_OFF_NBR_ADD_PARTS   3
3297 #define PP_OFF_FLAGS           4
3298 #define PP_OFF_PART_UNITS      6
3299 #define PP_OFF_RESERVED        7
3300 
3301 #define PP_BIT_IDP             0x20
3302 #define PP_BIT_FDP             0x80
3303 #define PP_MSK_PSUM_MB         0x10
3304 #define PP_MSK_PSUM_UNITS      0x18
3305 #define PP_MSK_POFM            0x04
3306 
3307 /* Get the number of partitions on the tape. As a side effect reads the
3308    mode page into the tape buffer. */
3309 static int nbr_partitions(struct scsi_tape *STp)
3310 {
3311 	int result;
3312 
3313 	if (STp->ready != ST_READY)
3314 		return (-EIO);
3315 
3316 	result = read_mode_page(STp, PART_PAGE, 1);
3317 
3318 	if (result) {
3319 		DEBC_printk(STp, "Can't read medium partition page.\n");
3320 		result = (-EIO);
3321 	} else {
3322 		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
3323 					      PP_OFF_NBR_ADD_PARTS] + 1;
3324 		DEBC_printk(STp, "Number of partitions %d.\n", result);
3325 	}
3326 
3327 	return result;
3328 }
3329 
3330 
3331 static int format_medium(struct scsi_tape *STp, int format)
3332 {
3333 	int result = 0;
3334 	int timeout = STp->long_timeout;
3335 	unsigned char scmd[MAX_COMMAND_SIZE];
3336 	struct st_request *SRpnt;
3337 
3338 	memset(scmd, 0, MAX_COMMAND_SIZE);
3339 	scmd[0] = FORMAT_UNIT;
3340 	scmd[2] = format;
3341 	if (STp->immediate) {
3342 		scmd[1] |= 1;		/* Don't wait for completion */
3343 		timeout = STp->device->request_queue->rq_timeout;
3344 	}
3345 	DEBC_printk(STp, "Sending FORMAT MEDIUM\n");
3346 	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
3347 			   timeout, MAX_RETRIES, 1);
3348 	if (!SRpnt)
3349 		result = STp->buffer->syscall_result;
3350 	return result;
3351 }
3352 
3353 
3354 /* Partition the tape into two partitions if size > 0 or one partition if
3355    size == 0.
3356 
3357    The block descriptors are read and written because Sony SDT-7000 does not
3358    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
3359 
3360    My HP C1533A drive returns only one partition size field. This is used to
3361    set the size of partition 1. There is no size field for the default partition.
3362    Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
3363    used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
3364    The following algorithm is used to accommodate both drives: if the number of
3365    partition size fields is greater than the maximum number of additional partitions
3366    in the mode page, the second field is used. Otherwise the first field is used.
3367 
3368    For Seagate DDS drives the page length must be 8 when no partitions is defined
3369    and 10 when 1 partition is defined (information from Eric Lee Green). This is
3370    is acceptable also to some other old drives and enforced if the first partition
3371    size field is used for the first additional partition size.
3372 
3373    For drives that advertize SCSI-3 or newer, use the SSC-3 methods.
3374  */
3375 static int partition_tape(struct scsi_tape *STp, int size)
3376 {
3377 	int result;
3378 	int target_partition;
3379 	bool scsi3 = STp->device->scsi_level >= SCSI_3, needs_format = false;
3380 	int pgo, psd_cnt, psdo;
3381 	int psum = PP_MSK_PSUM_MB, units = 0;
3382 	unsigned char *bp;
3383 
3384 	result = read_mode_page(STp, PART_PAGE, 0);
3385 	if (result) {
3386 		DEBC_printk(STp, "Can't read partition mode page.\n");
3387 		return result;
3388 	}
3389 	target_partition = 1;
3390 	if (size < 0) {
3391 		target_partition = 0;
3392 		size = -size;
3393 	}
3394 
3395 	/* The mode page is in the buffer. Let's modify it and write it. */
3396 	bp = (STp->buffer)->b_data;
3397 	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
3398 	DEBC_printk(STp, "Partition page length is %d bytes.\n",
3399 		    bp[pgo + MP_OFF_PAGE_LENGTH] + 2);
3400 
3401 	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
3402 
3403 	if (scsi3) {
3404 		needs_format = (bp[pgo + PP_OFF_FLAGS] & PP_MSK_POFM) != 0;
3405 		if (needs_format && size == 0) {
3406 			/* No need to write the mode page when clearing
3407 			 *  partitioning
3408 			 */
3409 			DEBC_printk(STp, "Formatting tape with one partition.\n");
3410 			result = format_medium(STp, 0);
3411 			goto out;
3412 		}
3413 		if (needs_format)  /* Leave the old value for HP DATs claiming SCSI_3 */
3414 			psd_cnt = 2;
3415 		if ((bp[pgo + PP_OFF_FLAGS] & PP_MSK_PSUM_UNITS) == PP_MSK_PSUM_UNITS) {
3416 			/* Use units scaling for large partitions if the device
3417 			 * suggests it and no precision lost. Required for IBM
3418 			 * TS1140/50 drives that don't support MB units.
3419 			 */
3420 			if (size >= 1000 && (size % 1000) == 0) {
3421 				size /= 1000;
3422 				psum = PP_MSK_PSUM_UNITS;
3423 				units = 9; /* GB */
3424 			}
3425 		}
3426 		/* Try it anyway if too large to specify in MB */
3427 		if (psum == PP_MSK_PSUM_MB && size >= 65534) {
3428 			size /= 1000;
3429 			psum = PP_MSK_PSUM_UNITS;
3430 			units = 9;  /* GB */
3431 		}
3432 	}
3433 
3434 	if (size >= 65535 ||  /* Does not fit into two bytes */
3435 	    (target_partition == 0 && psd_cnt < 2)) {
3436 		result = -EINVAL;
3437 		goto out;
3438 	}
3439 
3440 	psdo = pgo + PART_PAGE_FIXED_LENGTH;
3441 	/* The second condition is for HP DDS which use only one partition size
3442 	 * descriptor
3443 	 */
3444 	if (target_partition > 0 &&
3445 	    (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS] ||
3446 	     bp[pgo + PP_OFF_MAX_ADD_PARTS] != 1)) {
3447 		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest to partition 0 */
3448 		psdo += 2;
3449 	}
3450 	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);
3451 
3452 	DEBC_printk(STp, "psd_cnt %d, max.parts %d, nbr_parts %d\n",
3453 		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
3454 		    bp[pgo + PP_OFF_NBR_ADD_PARTS]);
3455 
3456 	if (size == 0) {
3457 		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
3458 		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
3459 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
3460 		DEBC_printk(STp, "Formatting tape with one partition.\n");
3461 	} else {
3462 		bp[psdo] = (size >> 8) & 0xff;
3463 		bp[psdo + 1] = size & 0xff;
3464 		if (target_partition == 0)
3465 			bp[psdo + 2] = bp[psdo + 3] = 0xff;
3466 		bp[pgo + 3] = 1;
3467 		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
3468 		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
3469 		DEBC_printk(STp,
3470 			    "Formatting tape with two partitions (%i = %d MB).\n",
3471 			    target_partition, units > 0 ? size * 1000 : size);
3472 	}
3473 	bp[pgo + PP_OFF_PART_UNITS] = 0;
3474 	bp[pgo + PP_OFF_RESERVED] = 0;
3475 	if (size != 1 || units != 0) {
3476 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | psum |
3477 			(bp[pgo + PP_OFF_FLAGS] & 0x07);
3478 		bp[pgo + PP_OFF_PART_UNITS] = units;
3479 	} else
3480 		bp[pgo + PP_OFF_FLAGS] = PP_BIT_FDP |
3481 			(bp[pgo + PP_OFF_FLAGS] & 0x1f);
3482 	bp[pgo + MP_OFF_PAGE_LENGTH] = 6 + psd_cnt * 2;
3483 
3484 	result = write_mode_page(STp, PART_PAGE, 1);
3485 
3486 	if (!result && needs_format)
3487 		result = format_medium(STp, 1);
3488 
3489 	if (result) {
3490 		st_printk(KERN_INFO, STp, "Partitioning of tape failed.\n");
3491 		result = (-EIO);
3492 	}
3493 
3494 out:
3495 	return result;
3496 }
3497 
3498 
3499 
3500 /* The ioctl command */
3501 static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3502 {
3503 	void __user *p = (void __user *)arg;
3504 	int i, cmd_nr, cmd_type, bt;
3505 	int retval = 0;
3506 	unsigned int blk;
3507 	struct scsi_tape *STp = file->private_data;
3508 	struct st_modedef *STm;
3509 	struct st_partstat *STps;
3510 
3511 	if (mutex_lock_interruptible(&STp->lock))
3512 		return -ERESTARTSYS;
3513 
3514 	DEB(
3515 	if (debugging && !STp->in_use) {
3516 		st_printk(ST_DEB_MSG, STp, "Incorrect device.\n");
3517 		retval = (-EIO);
3518 		goto out;
3519 	} ) /* end DEB */
3520 
3521 	STm = &(STp->modes[STp->current_mode]);
3522 	STps = &(STp->ps[STp->partition]);
3523 
3524 	/*
3525 	 * If we are in the middle of error recovery, don't let anyone
3526 	 * else try and use this device.  Also, if error recovery fails, it
3527 	 * may try and take the device offline, in which case all further
3528 	 * access to the device is prohibited.
3529 	 */
3530 	retval = scsi_ioctl_block_when_processing_errors(STp->device, cmd_in,
3531 			file->f_flags & O_NDELAY);
3532 	if (retval)
3533 		goto out;
3534 
3535 	cmd_type = _IOC_TYPE(cmd_in);
3536 	cmd_nr = _IOC_NR(cmd_in);
3537 
3538 	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
3539 		struct mtop mtc;
3540 
3541 		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
3542 			retval = (-EINVAL);
3543 			goto out;
3544 		}
3545 
3546 		i = copy_from_user(&mtc, p, sizeof(struct mtop));
3547 		if (i) {
3548 			retval = (-EFAULT);
3549 			goto out;
3550 		}
3551 
3552 		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
3553 			st_printk(KERN_WARNING, STp,
3554 				  "MTSETDRVBUFFER only allowed for root.\n");
3555 			retval = (-EPERM);
3556 			goto out;
3557 		}
3558 		if (!STm->defined &&
3559 		    (mtc.mt_op != MTSETDRVBUFFER &&
3560 		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
3561 			retval = (-ENXIO);
3562 			goto out;
3563 		}
3564 
3565 		if (!STp->pos_unknown) {
3566 
3567 			if (STps->eof == ST_FM_HIT) {
3568 				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3569                                     mtc.mt_op == MTEOM) {
3570 					mtc.mt_count -= 1;
3571 					if (STps->drv_file >= 0)
3572 						STps->drv_file += 1;
3573 				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
3574 					mtc.mt_count += 1;
3575 					if (STps->drv_file >= 0)
3576 						STps->drv_file += 1;
3577 				}
3578 			}
3579 
3580 			if (mtc.mt_op == MTSEEK) {
3581 				/* Old position must be restored if partition will be
3582                                    changed */
3583 				i = !STp->can_partitions ||
3584 				    (STp->new_partition != STp->partition);
3585 			} else {
3586 				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3587 				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
3588 				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
3589 				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
3590 				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
3591 				    mtc.mt_op == MTCOMPRESSION;
3592 			}
3593 			i = flush_buffer(STp, i);
3594 			if (i < 0) {
3595 				retval = i;
3596 				goto out;
3597 			}
3598 			if (STps->rw == ST_WRITING &&
3599 			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
3600 			     mtc.mt_op == MTSEEK ||
3601 			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
3602 				i = st_int_ioctl(STp, MTWEOF, 1);
3603 				if (i < 0) {
3604 					retval = i;
3605 					goto out;
3606 				}
3607 				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
3608 					mtc.mt_count++;
3609 				STps->rw = ST_IDLE;
3610 			     }
3611 
3612 		} else {
3613 			/*
3614 			 * If there was a bus reset, block further access
3615 			 * to this device.  If the user wants to rewind the tape,
3616 			 * then reset the flag and allow access again.
3617 			 */
3618 			if (mtc.mt_op != MTREW &&
3619 			    mtc.mt_op != MTOFFL &&
3620 			    mtc.mt_op != MTRETEN &&
3621 			    mtc.mt_op != MTERASE &&
3622 			    mtc.mt_op != MTSEEK &&
3623 			    mtc.mt_op != MTEOM) {
3624 				retval = (-EIO);
3625 				goto out;
3626 			}
3627 			reset_state(STp);
3628 			/* remove this when the midlevel properly clears was_reset */
3629 			STp->device->was_reset = 0;
3630 		}
3631 
3632 		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
3633 		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
3634 		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
3635 			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */
3636 
3637 		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
3638 			do_door_lock(STp, 0);	/* Ignore result! */
3639 
3640 		if (mtc.mt_op == MTSETDRVBUFFER &&
3641 		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
3642 			retval = st_set_options(STp, mtc.mt_count);
3643 			goto out;
3644 		}
3645 
3646 		if (mtc.mt_op == MTSETPART) {
3647 			if (!STp->can_partitions ||
3648 			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
3649 				retval = (-EINVAL);
3650 				goto out;
3651 			}
3652 			if (mtc.mt_count >= STp->nbr_partitions &&
3653 			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
3654 				retval = (-EIO);
3655 				goto out;
3656 			}
3657 			if (mtc.mt_count >= STp->nbr_partitions) {
3658 				retval = (-EINVAL);
3659 				goto out;
3660 			}
3661 			STp->new_partition = mtc.mt_count;
3662 			retval = 0;
3663 			goto out;
3664 		}
3665 
3666 		if (mtc.mt_op == MTMKPART) {
3667 			if (!STp->can_partitions) {
3668 				retval = (-EINVAL);
3669 				goto out;
3670 			}
3671 			i = do_load_unload(STp, file, 1);
3672 			if (i < 0) {
3673 				retval = i;
3674 				goto out;
3675 			}
3676 			i = partition_tape(STp, mtc.mt_count);
3677 			if (i < 0) {
3678 				retval = i;
3679 				goto out;
3680 			}
3681 			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
3682 				STp->ps[i].rw = ST_IDLE;
3683 				STp->ps[i].at_sm = 0;
3684 				STp->ps[i].last_block_valid = 0;
3685 			}
3686 			STp->partition = STp->new_partition = 0;
3687 			STp->nbr_partitions = mtc.mt_count != 0 ? 2 : 1;
3688 			STps->drv_block = STps->drv_file = 0;
3689 			retval = 0;
3690 			goto out;
3691 		}
3692 
3693 		if (mtc.mt_op == MTSEEK) {
3694 			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
3695 			if (!STp->can_partitions)
3696 				STp->ps[0].rw = ST_IDLE;
3697 			retval = i;
3698 			goto out;
3699 		}
3700 
3701 		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
3702 			retval = do_load_unload(STp, file, 0);
3703 			goto out;
3704 		}
3705 
3706 		if (mtc.mt_op == MTLOAD) {
3707 			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
3708 			goto out;
3709 		}
3710 
3711 		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
3712 			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
3713 			goto out;
3714 		}
3715 
3716 		if (STp->can_partitions && STp->ready == ST_READY &&
3717 		    (i = switch_partition(STp)) < 0) {
3718 			retval = i;
3719 			goto out;
3720 		}
3721 
3722 		if (mtc.mt_op == MTCOMPRESSION)
3723 			retval = st_compression(STp, (mtc.mt_count & 1));
3724 		else
3725 			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
3726 		goto out;
3727 	}
3728 	if (!STm->defined) {
3729 		retval = (-ENXIO);
3730 		goto out;
3731 	}
3732 
3733 	if ((i = flush_buffer(STp, 0)) < 0) {
3734 		retval = i;
3735 		goto out;
3736 	}
3737 	if (STp->can_partitions &&
3738 	    (i = switch_partition(STp)) < 0) {
3739 		retval = i;
3740 		goto out;
3741 	}
3742 
3743 	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
3744 		struct mtget mt_status;
3745 
3746 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
3747 			 retval = (-EINVAL);
3748 			 goto out;
3749 		}
3750 
3751 		mt_status.mt_type = STp->tape_type;
3752 		mt_status.mt_dsreg =
3753 		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
3754 		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
3755 		mt_status.mt_blkno = STps->drv_block;
3756 		mt_status.mt_fileno = STps->drv_file;
3757 		if (STp->block_size != 0) {
3758 			if (STps->rw == ST_WRITING)
3759 				mt_status.mt_blkno +=
3760 				    (STp->buffer)->buffer_bytes / STp->block_size;
3761 			else if (STps->rw == ST_READING)
3762 				mt_status.mt_blkno -=
3763                                         ((STp->buffer)->buffer_bytes +
3764                                          STp->block_size - 1) / STp->block_size;
3765 		}
3766 
3767 		mt_status.mt_gstat = 0;
3768 		if (STp->drv_write_prot)
3769 			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
3770 		if (mt_status.mt_blkno == 0) {
3771 			if (mt_status.mt_fileno == 0)
3772 				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
3773 			else
3774 				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
3775 		}
3776 		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
3777 		mt_status.mt_resid = STp->partition;
3778 		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
3779 			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
3780 		else if (STps->eof >= ST_EOM_OK)
3781 			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
3782 		if (STp->density == 1)
3783 			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
3784 		else if (STp->density == 2)
3785 			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
3786 		else if (STp->density == 3)
3787 			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
3788 		if (STp->ready == ST_READY)
3789 			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
3790 		if (STp->ready == ST_NO_TAPE)
3791 			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
3792 		if (STps->at_sm)
3793 			mt_status.mt_gstat |= GMT_SM(0xffffffff);
3794 		if (STm->do_async_writes ||
3795                     (STm->do_buffer_writes && STp->block_size != 0) ||
3796 		    STp->drv_buffer != 0)
3797 			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
3798 		if (STp->cleaning_req)
3799 			mt_status.mt_gstat |= GMT_CLN(0xffffffff);
3800 
3801 		retval = put_user_mtget(p, &mt_status);
3802 		if (retval)
3803 			goto out;
3804 
3805 		STp->recover_reg = 0;		/* Clear after read */
3806 		goto out;
3807 	}			/* End of MTIOCGET */
3808 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3809 		struct mtpos mt_pos;
3810 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3811 			 retval = (-EINVAL);
3812 			 goto out;
3813 		}
3814 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3815 			retval = i;
3816 			goto out;
3817 		}
3818 		mt_pos.mt_blkno = blk;
3819 		retval = put_user_mtpos(p, &mt_pos);
3820 		goto out;
3821 	}
3822 	mutex_unlock(&STp->lock);
3823 
3824 	switch (cmd_in) {
3825 	case SG_IO:
3826 	case SCSI_IOCTL_SEND_COMMAND:
3827 	case CDROM_SEND_PACKET:
3828 		if (!capable(CAP_SYS_RAWIO))
3829 			return -EPERM;
3830 		break;
3831 	default:
3832 		break;
3833 	}
3834 
3835 	retval = scsi_ioctl(STp->device, file->f_mode, cmd_in, p);
3836 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) {
3837 		/* unload */
3838 		STp->rew_at_close = 0;
3839 		STp->ready = ST_NO_TAPE;
3840 	}
3841 	return retval;
3842 
3843  out:
3844 	mutex_unlock(&STp->lock);
3845 	return retval;
3846 }
3847 
3848 #ifdef CONFIG_COMPAT
3849 static long st_compat_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
3850 {
3851 	/* argument conversion is handled using put_user_mtpos/put_user_mtget */
3852 	switch (cmd_in) {
3853 	case MTIOCPOS32:
3854 		cmd_in = MTIOCPOS;
3855 		break;
3856 	case MTIOCGET32:
3857 		cmd_in = MTIOCGET;
3858 		break;
3859 	}
3860 
3861 	return st_ioctl(file, cmd_in, arg);
3862 }
3863 #endif
3864 
3865 
3866 
3867 /* Try to allocate a new tape buffer. Calling function must not hold
3868    dev_arr_lock. */
3869 static struct st_buffer *new_tape_buffer(int max_sg)
3870 {
3871 	struct st_buffer *tb;
3872 
3873 	tb = kzalloc(sizeof(struct st_buffer), GFP_KERNEL);
3874 	if (!tb) {
3875 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3876 		return NULL;
3877 	}
3878 	tb->frp_segs = 0;
3879 	tb->use_sg = max_sg;
3880 	tb->buffer_size = 0;
3881 
3882 	tb->reserved_pages = kcalloc(max_sg, sizeof(struct page *),
3883 				     GFP_KERNEL);
3884 	if (!tb->reserved_pages) {
3885 		kfree(tb);
3886 		return NULL;
3887 	}
3888 
3889 	return tb;
3890 }
3891 
3892 
3893 /* Try to allocate enough space in the tape buffer */
3894 #define ST_MAX_ORDER 6
3895 
3896 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size)
3897 {
3898 	int segs, max_segs, b_size, order, got;
3899 	gfp_t priority;
3900 
3901 	if (new_size <= STbuffer->buffer_size)
3902 		return 1;
3903 
3904 	if (STbuffer->buffer_size <= PAGE_SIZE)
3905 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3906 
3907 	max_segs = STbuffer->use_sg;
3908 
3909 	priority = GFP_KERNEL | __GFP_NOWARN;
3910 
3911 	if (STbuffer->cleared)
3912 		priority |= __GFP_ZERO;
3913 
3914 	if (STbuffer->frp_segs) {
3915 		order = STbuffer->reserved_page_order;
3916 		b_size = PAGE_SIZE << order;
3917 	} else {
3918 		for (b_size = PAGE_SIZE, order = 0;
3919 		     order < ST_MAX_ORDER &&
3920 			     max_segs * (PAGE_SIZE << order) < new_size;
3921 		     order++, b_size *= 2)
3922 			;  /* empty */
3923 		STbuffer->reserved_page_order = order;
3924 	}
3925 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3926 		if (order == ST_MAX_ORDER)
3927 			return 0;
3928 		normalize_buffer(STbuffer);
3929 		return enlarge_buffer(STbuffer, new_size);
3930 	}
3931 
3932 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3933 	     segs < max_segs && got < new_size;) {
3934 		struct page *page;
3935 
3936 		page = alloc_pages(priority, order);
3937 		if (!page) {
3938 			DEB(STbuffer->buffer_size = got);
3939 			normalize_buffer(STbuffer);
3940 			return 0;
3941 		}
3942 
3943 		STbuffer->frp_segs += 1;
3944 		got += b_size;
3945 		STbuffer->buffer_size = got;
3946 		STbuffer->reserved_pages[segs] = page;
3947 		segs++;
3948 	}
3949 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3950 
3951 	return 1;
3952 }
3953 
3954 
3955 /* Make sure that no data from previous user is in the internal buffer */
3956 static void clear_buffer(struct st_buffer * st_bp)
3957 {
3958 	int i;
3959 
3960 	for (i=0; i < st_bp->frp_segs; i++)
3961 		memset(page_address(st_bp->reserved_pages[i]), 0,
3962 		       PAGE_SIZE << st_bp->reserved_page_order);
3963 	st_bp->cleared = 1;
3964 }
3965 
3966 
3967 /* Release the extra buffer */
3968 static void normalize_buffer(struct st_buffer * STbuffer)
3969 {
3970 	int i, order = STbuffer->reserved_page_order;
3971 
3972 	for (i = 0; i < STbuffer->frp_segs; i++) {
3973 		__free_pages(STbuffer->reserved_pages[i], order);
3974 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3975 	}
3976 	STbuffer->frp_segs = 0;
3977 	STbuffer->sg_segs = 0;
3978 	STbuffer->reserved_page_order = 0;
3979 	STbuffer->map_data.offset = 0;
3980 }
3981 
3982 
3983 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3984    negative error code. */
3985 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3986 {
3987 	int i, cnt, res, offset;
3988 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3989 
3990 	for (i = 0, offset = st_bp->buffer_bytes;
3991 	     i < st_bp->frp_segs && offset >= length; i++)
3992 		offset -= length;
3993 	if (i == st_bp->frp_segs) {	/* Should never happen */
3994 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
3995 		return (-EIO);
3996 	}
3997 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
3998 		struct page *page = st_bp->reserved_pages[i];
3999 		cnt = length - offset < do_count ? length - offset : do_count;
4000 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4001 		if (res)
4002 			return (-EFAULT);
4003 		do_count -= cnt;
4004 		st_bp->buffer_bytes += cnt;
4005 		ubp += cnt;
4006 		offset = 0;
4007 	}
4008 	if (do_count) /* Should never happen */
4009 		return (-EIO);
4010 
4011 	return 0;
4012 }
4013 
4014 
4015 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4016    negative error code. */
4017 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4018 {
4019 	int i, cnt, res, offset;
4020 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4021 
4022 	for (i = 0, offset = st_bp->read_pointer;
4023 	     i < st_bp->frp_segs && offset >= length; i++)
4024 		offset -= length;
4025 	if (i == st_bp->frp_segs) {	/* Should never happen */
4026 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4027 		return (-EIO);
4028 	}
4029 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4030 		struct page *page = st_bp->reserved_pages[i];
4031 		cnt = length - offset < do_count ? length - offset : do_count;
4032 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4033 		if (res)
4034 			return (-EFAULT);
4035 		do_count -= cnt;
4036 		st_bp->buffer_bytes -= cnt;
4037 		st_bp->read_pointer += cnt;
4038 		ubp += cnt;
4039 		offset = 0;
4040 	}
4041 	if (do_count) /* Should never happen */
4042 		return (-EIO);
4043 
4044 	return 0;
4045 }
4046 
4047 
4048 /* Move data towards start of buffer */
4049 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4050 {
4051 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4052 	int count, total;
4053 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4054 
4055 	if (offset == 0)
4056 		return;
4057 
4058 	total=st_bp->buffer_bytes - offset;
4059 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4060 		src_offset = offset;
4061 		if (src_offset < length)
4062 			break;
4063 		offset -= length;
4064 	}
4065 
4066 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4067 	for (dst_seg=dst_offset=0; total > 0; ) {
4068 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4069 		struct page *spage = st_bp->reserved_pages[src_seg];
4070 
4071 		count = min(length - dst_offset, length - src_offset);
4072 		memmove(page_address(dpage) + dst_offset,
4073 			page_address(spage) + src_offset, count);
4074 		src_offset += count;
4075 		if (src_offset >= length) {
4076 			src_seg++;
4077 			src_offset = 0;
4078 		}
4079 		dst_offset += count;
4080 		if (dst_offset >= length) {
4081 			dst_seg++;
4082 			dst_offset = 0;
4083 		}
4084 		total -= count;
4085 	}
4086 }
4087 
4088 /* Validate the options from command line or module parameters */
4089 static void validate_options(void)
4090 {
4091 	if (buffer_kbs > 0)
4092 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4093 	if (max_sg_segs >= ST_FIRST_SG)
4094 		st_max_sg_segs = max_sg_segs;
4095 }
4096 
4097 #ifndef MODULE
4098 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4099  */
4100 static int __init st_setup(char *str)
4101 {
4102 	int i, len, ints[5];
4103 	char *stp;
4104 
4105 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4106 
4107 	if (ints[0] > 0) {
4108 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4109 			if (parms[i].val)
4110 				*parms[i].val = ints[i + 1];
4111 	} else {
4112 		while (stp != NULL) {
4113 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4114 				len = strlen(parms[i].name);
4115 				if (!strncmp(stp, parms[i].name, len) &&
4116 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4117 					if (parms[i].val)
4118 						*parms[i].val =
4119 							simple_strtoul(stp + len + 1, NULL, 0);
4120 					else
4121 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4122 						       parms[i].name);
4123 					break;
4124 				}
4125 			}
4126 			if (i >= ARRAY_SIZE(parms))
4127 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4128 					stp);
4129 			stp = strchr(stp, ',');
4130 			if (stp)
4131 				stp++;
4132 		}
4133 	}
4134 
4135 	validate_options();
4136 
4137 	return 1;
4138 }
4139 
4140 __setup("st=", st_setup);
4141 
4142 #endif
4143 
4144 static const struct file_operations st_fops =
4145 {
4146 	.owner =	THIS_MODULE,
4147 	.read =		st_read,
4148 	.write =	st_write,
4149 	.unlocked_ioctl = st_ioctl,
4150 #ifdef CONFIG_COMPAT
4151 	.compat_ioctl = st_compat_ioctl,
4152 #endif
4153 	.open =		st_open,
4154 	.flush =	st_flush,
4155 	.release =	st_release,
4156 	.llseek =	noop_llseek,
4157 };
4158 
4159 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4160 {
4161 	int i, error;
4162 	dev_t cdev_devno;
4163 	struct cdev *cdev;
4164 	struct device *dev;
4165 	struct st_modedef *STm = &(tape->modes[mode]);
4166 	char name[10];
4167 	int dev_num = tape->index;
4168 
4169 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4170 
4171 	cdev = cdev_alloc();
4172 	if (!cdev) {
4173 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4174 		error = -ENOMEM;
4175 		goto out;
4176 	}
4177 	cdev->owner = THIS_MODULE;
4178 	cdev->ops = &st_fops;
4179 	STm->cdevs[rew] = cdev;
4180 
4181 	error = cdev_add(cdev, cdev_devno, 1);
4182 	if (error) {
4183 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4184 		       rew ? "non" : "auto", mode);
4185 		pr_err("st%d: Device not attached.\n", dev_num);
4186 		goto out_free;
4187 	}
4188 
4189 	i = mode << (4 - ST_NBR_MODE_BITS);
4190 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4191 		 tape->name, st_formats[i]);
4192 
4193 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4194 			    cdev_devno, &tape->modes[mode], "%s", name);
4195 	if (IS_ERR(dev)) {
4196 		pr_err("st%d: device_create failed\n", dev_num);
4197 		error = PTR_ERR(dev);
4198 		goto out_free;
4199 	}
4200 
4201 	STm->devs[rew] = dev;
4202 
4203 	return 0;
4204 out_free:
4205 	cdev_del(STm->cdevs[rew]);
4206 out:
4207 	STm->cdevs[rew] = NULL;
4208 	STm->devs[rew] = NULL;
4209 	return error;
4210 }
4211 
4212 static int create_cdevs(struct scsi_tape *tape)
4213 {
4214 	int mode, error;
4215 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4216 		error = create_one_cdev(tape, mode, 0);
4217 		if (error)
4218 			return error;
4219 		error = create_one_cdev(tape, mode, 1);
4220 		if (error)
4221 			return error;
4222 	}
4223 
4224 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4225 				 &tape->modes[0].devs[0]->kobj, "tape");
4226 }
4227 
4228 static void remove_cdevs(struct scsi_tape *tape)
4229 {
4230 	int mode, rew;
4231 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4232 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4233 		struct st_modedef *STm = &(tape->modes[mode]);
4234 		for (rew = 0; rew < 2; rew++) {
4235 			if (STm->cdevs[rew])
4236 				cdev_del(STm->cdevs[rew]);
4237 			if (STm->devs[rew])
4238 				device_unregister(STm->devs[rew]);
4239 		}
4240 	}
4241 }
4242 
4243 static int st_probe(struct device *dev)
4244 {
4245 	struct scsi_device *SDp = to_scsi_device(dev);
4246 	struct scsi_tape *tpnt = NULL;
4247 	struct st_modedef *STm;
4248 	struct st_partstat *STps;
4249 	struct st_buffer *buffer;
4250 	int i, error;
4251 
4252 	if (SDp->type != TYPE_TAPE)
4253 		return -ENODEV;
4254 	if (st_incompatible(SDp)) {
4255 		sdev_printk(KERN_INFO, SDp,
4256 			    "OnStream tapes are no longer supported;\n");
4257 		sdev_printk(KERN_INFO, SDp,
4258 			    "please mail to linux-scsi@vger.kernel.org.\n");
4259 		return -ENODEV;
4260 	}
4261 
4262 	scsi_autopm_get_device(SDp);
4263 	i = queue_max_segments(SDp->request_queue);
4264 	if (st_max_sg_segs < i)
4265 		i = st_max_sg_segs;
4266 	buffer = new_tape_buffer(i);
4267 	if (buffer == NULL) {
4268 		sdev_printk(KERN_ERR, SDp,
4269 			    "st: Can't allocate new tape buffer. "
4270 			    "Device not attached.\n");
4271 		goto out;
4272 	}
4273 
4274 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
4275 	if (tpnt == NULL) {
4276 		sdev_printk(KERN_ERR, SDp,
4277 			    "st: Can't allocate device descriptor.\n");
4278 		goto out_buffer_free;
4279 	}
4280 	kref_init(&tpnt->kref);
4281 
4282 	tpnt->device = SDp;
4283 	if (SDp->scsi_level <= 2)
4284 		tpnt->tape_type = MT_ISSCSI1;
4285 	else
4286 		tpnt->tape_type = MT_ISSCSI2;
4287 
4288 	tpnt->buffer = buffer;
4289 	tpnt->buffer->last_SRpnt = NULL;
4290 
4291 	tpnt->inited = 0;
4292 	tpnt->dirty = 0;
4293 	tpnt->in_use = 0;
4294 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4295 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4296 	tpnt->density = 0;
4297 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4298 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4299 	tpnt->can_partitions = 0;
4300 	tpnt->two_fm = ST_TWO_FM;
4301 	tpnt->fast_mteom = ST_FAST_MTEOM;
4302 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4303 	tpnt->sili = ST_SILI;
4304 	tpnt->immediate = ST_NOWAIT;
4305 	tpnt->immediate_filemark = 0;
4306 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4307 	tpnt->partition = 0;
4308 	tpnt->new_partition = 0;
4309 	tpnt->nbr_partitions = 0;
4310 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4311 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4312 	tpnt->try_dio = try_direct_io;
4313 
4314 	for (i = 0; i < ST_NBR_MODES; i++) {
4315 		STm = &(tpnt->modes[i]);
4316 		STm->defined = 0;
4317 		STm->sysv = ST_SYSV;
4318 		STm->defaults_for_writes = 0;
4319 		STm->do_async_writes = ST_ASYNC_WRITES;
4320 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4321 		STm->do_read_ahead = ST_READ_AHEAD;
4322 		STm->default_compression = ST_DONT_TOUCH;
4323 		STm->default_blksize = (-1);	/* No forced size */
4324 		STm->default_density = (-1);	/* No forced density */
4325 		STm->tape = tpnt;
4326 	}
4327 
4328 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4329 		STps = &(tpnt->ps[i]);
4330 		STps->rw = ST_IDLE;
4331 		STps->eof = ST_NOEOF;
4332 		STps->at_sm = 0;
4333 		STps->last_block_valid = 0;
4334 		STps->drv_block = (-1);
4335 		STps->drv_file = (-1);
4336 	}
4337 
4338 	tpnt->current_mode = 0;
4339 	tpnt->modes[0].defined = 1;
4340 
4341 	tpnt->density_changed = tpnt->compression_changed =
4342 	    tpnt->blksize_changed = 0;
4343 	mutex_init(&tpnt->lock);
4344 
4345 	idr_preload(GFP_KERNEL);
4346 	spin_lock(&st_index_lock);
4347 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4348 	spin_unlock(&st_index_lock);
4349 	idr_preload_end();
4350 	if (error < 0) {
4351 		pr_warn("st: idr allocation failed: %d\n", error);
4352 		goto out_free_tape;
4353 	}
4354 	tpnt->index = error;
4355 	sprintf(tpnt->name, "st%d", tpnt->index);
4356 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4357 	if (tpnt->stats == NULL) {
4358 		sdev_printk(KERN_ERR, SDp,
4359 			    "st: Can't allocate statistics.\n");
4360 		goto out_idr_remove;
4361 	}
4362 
4363 	dev_set_drvdata(dev, tpnt);
4364 
4365 
4366 	error = create_cdevs(tpnt);
4367 	if (error)
4368 		goto out_remove_devs;
4369 	scsi_autopm_put_device(SDp);
4370 
4371 	sdev_printk(KERN_NOTICE, SDp,
4372 		    "Attached scsi tape %s\n", tpnt->name);
4373 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4374 		    tpnt->name, tpnt->try_dio ? "yes" : "no",
4375 		    queue_dma_alignment(SDp->request_queue) + 1);
4376 
4377 	return 0;
4378 
4379 out_remove_devs:
4380 	remove_cdevs(tpnt);
4381 	kfree(tpnt->stats);
4382 out_idr_remove:
4383 	spin_lock(&st_index_lock);
4384 	idr_remove(&st_index_idr, tpnt->index);
4385 	spin_unlock(&st_index_lock);
4386 out_free_tape:
4387 	kfree(tpnt);
4388 out_buffer_free:
4389 	kfree(buffer);
4390 out:
4391 	scsi_autopm_put_device(SDp);
4392 	return -ENODEV;
4393 };
4394 
4395 
4396 static int st_remove(struct device *dev)
4397 {
4398 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4399 	int index = tpnt->index;
4400 
4401 	scsi_autopm_get_device(to_scsi_device(dev));
4402 	remove_cdevs(tpnt);
4403 
4404 	mutex_lock(&st_ref_mutex);
4405 	kref_put(&tpnt->kref, scsi_tape_release);
4406 	mutex_unlock(&st_ref_mutex);
4407 	spin_lock(&st_index_lock);
4408 	idr_remove(&st_index_idr, index);
4409 	spin_unlock(&st_index_lock);
4410 	return 0;
4411 }
4412 
4413 /**
4414  *      scsi_tape_release - Called to free the Scsi_Tape structure
4415  *      @kref: pointer to embedded kref
4416  *
4417  *      st_ref_mutex must be held entering this routine.  Because it is
4418  *      called on last put, you should always use the scsi_tape_get()
4419  *      scsi_tape_put() helpers which manipulate the semaphore directly
4420  *      and never do a direct kref_put().
4421  **/
4422 static void scsi_tape_release(struct kref *kref)
4423 {
4424 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4425 
4426 	tpnt->device = NULL;
4427 
4428 	if (tpnt->buffer) {
4429 		normalize_buffer(tpnt->buffer);
4430 		kfree(tpnt->buffer->reserved_pages);
4431 		kfree(tpnt->buffer);
4432 	}
4433 
4434 	kfree(tpnt->stats);
4435 	kfree(tpnt);
4436 	return;
4437 }
4438 
4439 static struct class st_sysfs_class = {
4440 	.name = "scsi_tape",
4441 	.dev_groups = st_dev_groups,
4442 };
4443 
4444 static int __init init_st(void)
4445 {
4446 	int err;
4447 
4448 	validate_options();
4449 
4450 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4451 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4452 
4453 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4454 	if (debugging) {
4455 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4456 			debugging);
4457 	}
4458 
4459 	err = class_register(&st_sysfs_class);
4460 	if (err) {
4461 		pr_err("Unable register sysfs class for SCSI tapes\n");
4462 		return err;
4463 	}
4464 
4465 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4466 				     ST_MAX_TAPE_ENTRIES, "st");
4467 	if (err) {
4468 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4469 		       SCSI_TAPE_MAJOR);
4470 		goto err_class;
4471 	}
4472 
4473 	err = scsi_register_driver(&st_template.gendrv);
4474 	if (err)
4475 		goto err_chrdev;
4476 
4477 	return 0;
4478 
4479 err_chrdev:
4480 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4481 				 ST_MAX_TAPE_ENTRIES);
4482 err_class:
4483 	class_unregister(&st_sysfs_class);
4484 	return err;
4485 }
4486 
4487 static void __exit exit_st(void)
4488 {
4489 	scsi_unregister_driver(&st_template.gendrv);
4490 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4491 				 ST_MAX_TAPE_ENTRIES);
4492 	class_unregister(&st_sysfs_class);
4493 	idr_destroy(&st_index_idr);
4494 	printk(KERN_INFO "st: Unloaded.\n");
4495 }
4496 
4497 module_init(init_st);
4498 module_exit(exit_st);
4499 
4500 
4501 /* The sysfs driver interface. Read-only at the moment */
4502 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4503 {
4504 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4505 }
4506 static DRIVER_ATTR_RO(try_direct_io);
4507 
4508 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4509 {
4510 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4511 }
4512 static DRIVER_ATTR_RO(fixed_buffer_size);
4513 
4514 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4515 {
4516 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4517 }
4518 static DRIVER_ATTR_RO(max_sg_segs);
4519 
4520 static ssize_t version_show(struct device_driver *ddd, char *buf)
4521 {
4522 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4523 }
4524 static DRIVER_ATTR_RO(version);
4525 
4526 #if DEBUG
4527 static ssize_t debug_flag_store(struct device_driver *ddp,
4528 	const char *buf, size_t count)
4529 {
4530 /* We only care what the first byte of the data is the rest is unused.
4531  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4532  * other values have -EINVAL returned if they are passed in.
4533  */
4534 	if (count > 0) {
4535 		if (buf[0] == '0') {
4536 			debugging = NO_DEBUG;
4537 			return count;
4538 		} else if (buf[0] == '1') {
4539 			debugging = 1;
4540 			return count;
4541 		}
4542 	}
4543 	return -EINVAL;
4544 }
4545 
4546 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4547 {
4548 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4549 }
4550 static DRIVER_ATTR_RW(debug_flag);
4551 #endif
4552 
4553 static struct attribute *st_drv_attrs[] = {
4554 	&driver_attr_try_direct_io.attr,
4555 	&driver_attr_fixed_buffer_size.attr,
4556 	&driver_attr_max_sg_segs.attr,
4557 	&driver_attr_version.attr,
4558 #if DEBUG
4559 	&driver_attr_debug_flag.attr,
4560 #endif
4561 	NULL,
4562 };
4563 ATTRIBUTE_GROUPS(st_drv);
4564 
4565 /* The sysfs simple class interface */
4566 static ssize_t
4567 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4568 {
4569 	struct st_modedef *STm = dev_get_drvdata(dev);
4570 	ssize_t l = 0;
4571 
4572 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4573 	return l;
4574 }
4575 static DEVICE_ATTR_RO(defined);
4576 
4577 static ssize_t
4578 default_blksize_show(struct device *dev, struct device_attribute *attr,
4579 		     char *buf)
4580 {
4581 	struct st_modedef *STm = dev_get_drvdata(dev);
4582 	ssize_t l = 0;
4583 
4584 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4585 	return l;
4586 }
4587 static DEVICE_ATTR_RO(default_blksize);
4588 
4589 static ssize_t
4590 default_density_show(struct device *dev, struct device_attribute *attr,
4591 		     char *buf)
4592 {
4593 	struct st_modedef *STm = dev_get_drvdata(dev);
4594 	ssize_t l = 0;
4595 	char *fmt;
4596 
4597 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4598 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4599 	return l;
4600 }
4601 static DEVICE_ATTR_RO(default_density);
4602 
4603 static ssize_t
4604 default_compression_show(struct device *dev, struct device_attribute *attr,
4605 			 char *buf)
4606 {
4607 	struct st_modedef *STm = dev_get_drvdata(dev);
4608 	ssize_t l = 0;
4609 
4610 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4611 	return l;
4612 }
4613 static DEVICE_ATTR_RO(default_compression);
4614 
4615 static ssize_t
4616 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4617 {
4618 	struct st_modedef *STm = dev_get_drvdata(dev);
4619 	struct scsi_tape *STp = STm->tape;
4620 	int options;
4621 	ssize_t l = 0;
4622 
4623 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4624 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4625 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4626 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4627 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4628 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4629 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4630 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4631 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4632 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4633 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4634 	options |= STm->sysv ? MT_ST_SYSV : 0;
4635 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4636 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4637 	options |= STp->sili ? MT_ST_SILI : 0;
4638 
4639 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4640 	return l;
4641 }
4642 static DEVICE_ATTR_RO(options);
4643 
4644 /* Support for tape stats */
4645 
4646 /**
4647  * read_cnt_show - return read count - count of reads made from tape drive
4648  * @dev: struct device
4649  * @attr: attribute structure
4650  * @buf: buffer to return formatted data in
4651  */
4652 static ssize_t read_cnt_show(struct device *dev,
4653 	struct device_attribute *attr, char *buf)
4654 {
4655 	struct st_modedef *STm = dev_get_drvdata(dev);
4656 
4657 	return sprintf(buf, "%lld",
4658 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4659 }
4660 static DEVICE_ATTR_RO(read_cnt);
4661 
4662 /**
4663  * read_byte_cnt_show - return read byte count - tape drives
4664  * may use blocks less than 512 bytes this gives the raw byte count of
4665  * of data read from the tape drive.
4666  * @dev: struct device
4667  * @attr: attribute structure
4668  * @buf: buffer to return formatted data in
4669  */
4670 static ssize_t read_byte_cnt_show(struct device *dev,
4671 	struct device_attribute *attr, char *buf)
4672 {
4673 	struct st_modedef *STm = dev_get_drvdata(dev);
4674 
4675 	return sprintf(buf, "%lld",
4676 		       (long long)atomic64_read(&STm->tape->stats->read_byte_cnt));
4677 }
4678 static DEVICE_ATTR_RO(read_byte_cnt);
4679 
4680 /**
4681  * read_ns_show - return read ns - overall time spent waiting on reads in ns.
4682  * @dev: struct device
4683  * @attr: attribute structure
4684  * @buf: buffer to return formatted data in
4685  */
4686 static ssize_t read_ns_show(struct device *dev,
4687 	struct device_attribute *attr, char *buf)
4688 {
4689 	struct st_modedef *STm = dev_get_drvdata(dev);
4690 
4691 	return sprintf(buf, "%lld",
4692 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4693 }
4694 static DEVICE_ATTR_RO(read_ns);
4695 
4696 /**
4697  * write_cnt_show - write count - number of user calls
4698  * to write(2) that have written data to tape.
4699  * @dev: struct device
4700  * @attr: attribute structure
4701  * @buf: buffer to return formatted data in
4702  */
4703 static ssize_t write_cnt_show(struct device *dev,
4704 	struct device_attribute *attr, char *buf)
4705 {
4706 	struct st_modedef *STm = dev_get_drvdata(dev);
4707 
4708 	return sprintf(buf, "%lld",
4709 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4710 }
4711 static DEVICE_ATTR_RO(write_cnt);
4712 
4713 /**
4714  * write_byte_cnt_show - write byte count - raw count of
4715  * bytes written to tape.
4716  * @dev: struct device
4717  * @attr: attribute structure
4718  * @buf: buffer to return formatted data in
4719  */
4720 static ssize_t write_byte_cnt_show(struct device *dev,
4721 	struct device_attribute *attr, char *buf)
4722 {
4723 	struct st_modedef *STm = dev_get_drvdata(dev);
4724 
4725 	return sprintf(buf, "%lld",
4726 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4727 }
4728 static DEVICE_ATTR_RO(write_byte_cnt);
4729 
4730 /**
4731  * write_ns_show - write ns - number of nanoseconds waiting on write
4732  * requests to complete.
4733  * @dev: struct device
4734  * @attr: attribute structure
4735  * @buf: buffer to return formatted data in
4736  */
4737 static ssize_t write_ns_show(struct device *dev,
4738 	struct device_attribute *attr, char *buf)
4739 {
4740 	struct st_modedef *STm = dev_get_drvdata(dev);
4741 
4742 	return sprintf(buf, "%lld",
4743 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4744 }
4745 static DEVICE_ATTR_RO(write_ns);
4746 
4747 /**
4748  * in_flight_show - number of I/Os currently in flight -
4749  * in most cases this will be either 0 or 1. It may be higher if someone
4750  * has also issued other SCSI commands such as via an ioctl.
4751  * @dev: struct device
4752  * @attr: attribute structure
4753  * @buf: buffer to return formatted data in
4754  */
4755 static ssize_t in_flight_show(struct device *dev,
4756 	struct device_attribute *attr, char *buf)
4757 {
4758 	struct st_modedef *STm = dev_get_drvdata(dev);
4759 
4760 	return sprintf(buf, "%lld",
4761 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4762 }
4763 static DEVICE_ATTR_RO(in_flight);
4764 
4765 /**
4766  * io_ns_show - io wait ns - this is the number of ns spent
4767  * waiting on all I/O to complete. This includes tape movement commands
4768  * such as rewinding, seeking to end of file or tape, it also includes
4769  * read and write. To determine the time spent on tape movement
4770  * subtract the read and write ns from this value.
4771  * @dev: struct device
4772  * @attr: attribute structure
4773  * @buf: buffer to return formatted data in
4774  */
4775 static ssize_t io_ns_show(struct device *dev,
4776 	struct device_attribute *attr, char *buf)
4777 {
4778 	struct st_modedef *STm = dev_get_drvdata(dev);
4779 
4780 	return sprintf(buf, "%lld",
4781 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4782 }
4783 static DEVICE_ATTR_RO(io_ns);
4784 
4785 /**
4786  * other_cnt_show - other io count - this is the number of
4787  * I/O requests other than read and write requests.
4788  * Typically these are tape movement requests but will include driver
4789  * tape movement. This includes only requests issued by the st driver.
4790  * @dev: struct device
4791  * @attr: attribute structure
4792  * @buf: buffer to return formatted data in
4793  */
4794 static ssize_t other_cnt_show(struct device *dev,
4795 	struct device_attribute *attr, char *buf)
4796 {
4797 	struct st_modedef *STm = dev_get_drvdata(dev);
4798 
4799 	return sprintf(buf, "%lld",
4800 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4801 }
4802 static DEVICE_ATTR_RO(other_cnt);
4803 
4804 /**
4805  * resid_cnt_show - A count of the number of times we get a residual
4806  * count - this should indicate someone issuing reads larger than the
4807  * block size on tape.
4808  * @dev: struct device
4809  * @attr: attribute structure
4810  * @buf: buffer to return formatted data in
4811  */
4812 static ssize_t resid_cnt_show(struct device *dev,
4813 	struct device_attribute *attr, char *buf)
4814 {
4815 	struct st_modedef *STm = dev_get_drvdata(dev);
4816 
4817 	return sprintf(buf, "%lld",
4818 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4819 }
4820 static DEVICE_ATTR_RO(resid_cnt);
4821 
4822 static struct attribute *st_dev_attrs[] = {
4823 	&dev_attr_defined.attr,
4824 	&dev_attr_default_blksize.attr,
4825 	&dev_attr_default_density.attr,
4826 	&dev_attr_default_compression.attr,
4827 	&dev_attr_options.attr,
4828 	NULL,
4829 };
4830 
4831 static struct attribute *st_stats_attrs[] = {
4832 	&dev_attr_read_cnt.attr,
4833 	&dev_attr_read_byte_cnt.attr,
4834 	&dev_attr_read_ns.attr,
4835 	&dev_attr_write_cnt.attr,
4836 	&dev_attr_write_byte_cnt.attr,
4837 	&dev_attr_write_ns.attr,
4838 	&dev_attr_in_flight.attr,
4839 	&dev_attr_io_ns.attr,
4840 	&dev_attr_other_cnt.attr,
4841 	&dev_attr_resid_cnt.attr,
4842 	NULL,
4843 };
4844 
4845 static struct attribute_group stats_group = {
4846 	.name = "stats",
4847 	.attrs = st_stats_attrs,
4848 };
4849 
4850 static struct attribute_group st_group = {
4851 	.attrs = st_dev_attrs,
4852 };
4853 
4854 static const struct attribute_group *st_dev_groups[] = {
4855 	&st_group,
4856 	&stats_group,
4857 	NULL,
4858 };
4859 
4860 /* The following functions may be useful for a larger audience. */
4861 static int sgl_map_user_pages(struct st_buffer *STbp,
4862 			      const unsigned int max_pages, unsigned long uaddr,
4863 			      size_t count, int rw)
4864 {
4865 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4866 	unsigned long start = uaddr >> PAGE_SHIFT;
4867 	const int nr_pages = end - start;
4868 	int res, i;
4869 	struct page **pages;
4870 	struct rq_map_data *mdata = &STbp->map_data;
4871 
4872 	/* User attempted Overflow! */
4873 	if ((uaddr + count) < uaddr)
4874 		return -EINVAL;
4875 
4876 	/* Too big */
4877         if (nr_pages > max_pages)
4878 		return -ENOMEM;
4879 
4880 	/* Hmm? */
4881 	if (count == 0)
4882 		return 0;
4883 
4884 	pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
4885 	if (pages == NULL)
4886 		return -ENOMEM;
4887 
4888         /* Try to fault in all of the necessary pages */
4889         /* rw==READ means read from drive, write into memory area */
4890 	res = pin_user_pages_fast(uaddr, nr_pages, rw == READ ? FOLL_WRITE : 0,
4891 				  pages);
4892 
4893 	/* Errors and no page mapped should return here */
4894 	if (res < nr_pages)
4895 		goto out_unmap;
4896 
4897         for (i=0; i < nr_pages; i++) {
4898                 /* FIXME: flush superflous for rw==READ,
4899                  * probably wrong function for rw==WRITE
4900                  */
4901 		flush_dcache_page(pages[i]);
4902         }
4903 
4904 	mdata->offset = uaddr & ~PAGE_MASK;
4905 	STbp->mapped_pages = pages;
4906 
4907 	return nr_pages;
4908  out_unmap:
4909 	if (res > 0) {
4910 		unpin_user_pages(pages, res);
4911 		res = 0;
4912 	}
4913 	kfree(pages);
4914 	return res;
4915 }
4916 
4917 
4918 /* And unmap them... */
4919 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4920 				const unsigned int nr_pages, int dirtied)
4921 {
4922 	/* FIXME: cache flush missing for rw==READ */
4923 	unpin_user_pages_dirty_lock(STbp->mapped_pages, nr_pages, dirtied);
4924 
4925 	kfree(STbp->mapped_pages);
4926 	STbp->mapped_pages = NULL;
4927 
4928 	return 0;
4929 }
4930