xref: /linux/drivers/scsi/st.c (revision f3a8b6645dc2e60d11f20c1c23afd964ff4e55ae)
1 /*
2    SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
3    file Documentation/scsi/st.txt for more information.
4 
5    History:
6    Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
7    Contribution and ideas from several people including (in alphabetical
8    order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
9    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
10    Michael Schaefer, J"org Weule, and Eric Youngdale.
11 
12    Copyright 1992 - 2016 Kai Makisara
13    email Kai.Makisara@kolumbus.fi
14 
15    Some small formal changes - aeb, 950809
16 
17    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
18  */
19 
20 static const char *verstr = "20160209";
21 
22 #include <linux/module.h>
23 
24 #include <linux/fs.h>
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
27 #include <linux/mm.h>
28 #include <linux/init.h>
29 #include <linux/string.h>
30 #include <linux/slab.h>
31 #include <linux/errno.h>
32 #include <linux/mtio.h>
33 #include <linux/cdrom.h>
34 #include <linux/ioctl.h>
35 #include <linux/fcntl.h>
36 #include <linux/spinlock.h>
37 #include <linux/blkdev.h>
38 #include <linux/moduleparam.h>
39 #include <linux/cdev.h>
40 #include <linux/idr.h>
41 #include <linux/delay.h>
42 #include <linux/mutex.h>
43 
44 #include <asm/uaccess.h>
45 #include <asm/dma.h>
46 
47 #include <scsi/scsi.h>
48 #include <scsi/scsi_dbg.h>
49 #include <scsi/scsi_device.h>
50 #include <scsi/scsi_driver.h>
51 #include <scsi/scsi_eh.h>
52 #include <scsi/scsi_host.h>
53 #include <scsi/scsi_ioctl.h>
54 #include <scsi/sg.h>
55 
56 
57 /* The driver prints some debugging information on the console if DEBUG
58    is defined and non-zero. */
59 #define DEBUG 1
60 #define NO_DEBUG 0
61 
62 #define ST_DEB_MSG  KERN_NOTICE
63 #if DEBUG
64 /* The message level for the debug messages is currently set to KERN_NOTICE
65    so that people can easily see the messages. Later when the debugging messages
66    in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
67 #define DEB(a) a
68 #define DEBC(a) if (debugging) { a ; }
69 #else
70 #define DEB(a)
71 #define DEBC(a)
72 #endif
73 
74 #define ST_KILOBYTE 1024
75 
76 #include "st_options.h"
77 #include "st.h"
78 
79 static int buffer_kbs;
80 static int max_sg_segs;
81 static int try_direct_io = TRY_DIRECT_IO;
82 static int try_rdio = 1;
83 static int try_wdio = 1;
84 static int debug_flag;
85 
86 static struct class st_sysfs_class;
87 static const struct attribute_group *st_dev_groups[];
88 static const struct attribute_group *st_drv_groups[];
89 
90 MODULE_AUTHOR("Kai Makisara");
91 MODULE_DESCRIPTION("SCSI tape (st) driver");
92 MODULE_LICENSE("GPL");
93 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
94 MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
95 
96 /* Set 'perm' (4th argument) to 0 to disable module_param's definition
97  * of sysfs parameters (which module_param doesn't yet support).
98  * Sysfs parameters defined explicitly later.
99  */
100 module_param_named(buffer_kbs, buffer_kbs, int, 0);
101 MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
102 module_param_named(max_sg_segs, max_sg_segs, int, 0);
103 MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
104 module_param_named(try_direct_io, try_direct_io, int, 0);
105 MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
106 module_param_named(debug_flag, debug_flag, int, 0);
107 MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
108 
109 
110 /* Extra parameters for testing */
111 module_param_named(try_rdio, try_rdio, int, 0);
112 MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
113 module_param_named(try_wdio, try_wdio, int, 0);
114 MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");
115 
116 #ifndef MODULE
117 static int write_threshold_kbs;  /* retained for compatibility */
118 static struct st_dev_parm {
119 	char *name;
120 	int *val;
121 } parms[] __initdata = {
122 	{
123 		"buffer_kbs", &buffer_kbs
124 	},
125 	{       /* Retained for compatibility with 2.4 */
126 		"write_threshold_kbs", &write_threshold_kbs
127 	},
128 	{
129 		"max_sg_segs", NULL
130 	},
131 	{
132 		"try_direct_io", &try_direct_io
133 	},
134 	{
135 		"debug_flag", &debug_flag
136 	}
137 };
138 #endif
139 
140 /* Restrict the number of modes so that names for all are assigned */
141 #if ST_NBR_MODES > 16
142 #error "Maximum number of modes is 16"
143 #endif
144 /* Bit reversed order to get same names for same minors with all
145    mode counts */
146 static const char *st_formats[] = {
147 	"",  "r", "k", "s", "l", "t", "o", "u",
148 	"m", "v", "p", "x", "a", "y", "q", "z"};
149 
150 /* The default definitions have been moved to st_options.h */
151 
152 #define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)
153 
154 /* The buffer size should fit into the 24 bits for length in the
155    6-byte SCSI read and write commands. */
156 #if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
157 #error "Buffer size should not exceed (2 << 24 - 1) bytes!"
158 #endif
159 
160 static int debugging = DEBUG;
161 
162 #define MAX_RETRIES 0
163 #define MAX_WRITE_RETRIES 0
164 #define MAX_READY_RETRIES 0
165 #define NO_TAPE  NOT_READY
166 
167 #define ST_TIMEOUT (900 * HZ)
168 #define ST_LONG_TIMEOUT (14000 * HZ)
169 
170 /* Remove mode bits and auto-rewind bit (7) */
171 #define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
172     (iminor(x) & ~(-1 << ST_MODE_SHIFT)) )
173 #define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)
174 
175 /* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
176 #define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
177   (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )
178 
179 /* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
180    24 bits) */
181 #define SET_DENS_AND_BLK 0x10001
182 
183 static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
184 static int st_max_sg_segs = ST_MAX_SG;
185 
186 static int modes_defined;
187 
188 static int enlarge_buffer(struct st_buffer *, int, int);
189 static void clear_buffer(struct st_buffer *);
190 static void normalize_buffer(struct st_buffer *);
191 static int append_to_buffer(const char __user *, struct st_buffer *, int);
192 static int from_buffer(struct st_buffer *, char __user *, int);
193 static void move_buffer_data(struct st_buffer *, int);
194 
195 static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
196 			      unsigned long, size_t, int);
197 static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);
198 
199 static int st_probe(struct device *);
200 static int st_remove(struct device *);
201 
202 static struct scsi_driver st_template = {
203 	.gendrv = {
204 		.name		= "st",
205 		.owner		= THIS_MODULE,
206 		.probe		= st_probe,
207 		.remove		= st_remove,
208 		.groups		= st_drv_groups,
209 	},
210 };
211 
212 static int st_compression(struct scsi_tape *, int);
213 
214 static int find_partition(struct scsi_tape *);
215 static int switch_partition(struct scsi_tape *);
216 
217 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
218 
219 static void scsi_tape_release(struct kref *);
220 
221 #define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
222 
223 static DEFINE_MUTEX(st_ref_mutex);
224 static DEFINE_SPINLOCK(st_index_lock);
225 static DEFINE_SPINLOCK(st_use_lock);
226 static DEFINE_IDR(st_index_idr);
227 
228 
229 
230 #include "osst_detect.h"
231 #ifndef SIGS_FROM_OSST
232 #define SIGS_FROM_OSST \
233 	{"OnStream", "SC-", "", "osst"}, \
234 	{"OnStream", "DI-", "", "osst"}, \
235 	{"OnStream", "DP-", "", "osst"}, \
236 	{"OnStream", "USB", "", "osst"}, \
237 	{"OnStream", "FW-", "", "osst"}
238 #endif
239 
240 static struct scsi_tape *scsi_tape_get(int dev)
241 {
242 	struct scsi_tape *STp = NULL;
243 
244 	mutex_lock(&st_ref_mutex);
245 	spin_lock(&st_index_lock);
246 
247 	STp = idr_find(&st_index_idr, dev);
248 	if (!STp) goto out;
249 
250 	kref_get(&STp->kref);
251 
252 	if (!STp->device)
253 		goto out_put;
254 
255 	if (scsi_device_get(STp->device))
256 		goto out_put;
257 
258 	goto out;
259 
260 out_put:
261 	kref_put(&STp->kref, scsi_tape_release);
262 	STp = NULL;
263 out:
264 	spin_unlock(&st_index_lock);
265 	mutex_unlock(&st_ref_mutex);
266 	return STp;
267 }
268 
269 static void scsi_tape_put(struct scsi_tape *STp)
270 {
271 	struct scsi_device *sdev = STp->device;
272 
273 	mutex_lock(&st_ref_mutex);
274 	kref_put(&STp->kref, scsi_tape_release);
275 	scsi_device_put(sdev);
276 	mutex_unlock(&st_ref_mutex);
277 }
278 
279 struct st_reject_data {
280 	char *vendor;
281 	char *model;
282 	char *rev;
283 	char *driver_hint; /* Name of the correct driver, NULL if unknown */
284 };
285 
286 static struct st_reject_data reject_list[] = {
287 	/* {"XXX", "Yy-", "", NULL},  example */
288 	SIGS_FROM_OSST,
289 	{NULL, }};
290 
291 /* If the device signature is on the list of incompatible drives, the
292    function returns a pointer to the name of the correct driver (if known) */
293 static char * st_incompatible(struct scsi_device* SDp)
294 {
295 	struct st_reject_data *rp;
296 
297 	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
298 		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
299 		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
300 		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
301 			if (rp->driver_hint)
302 				return rp->driver_hint;
303 			else
304 				return "unknown";
305 		}
306 	return NULL;
307 }
308 
309 
310 static inline char *tape_name(struct scsi_tape *tape)
311 {
312 	return tape->disk->disk_name;
313 }
314 
315 #define st_printk(prefix, t, fmt, a...) \
316 	sdev_prefix_printk(prefix, (t)->device, tape_name(t), fmt, ##a)
317 #ifdef DEBUG
318 #define DEBC_printk(t, fmt, a...) \
319 	if (debugging) { st_printk(ST_DEB_MSG, t, fmt, ##a ); }
320 #else
321 #define DEBC_printk(t, fmt, a...)
322 #endif
323 
324 static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
325 {
326 	const u8 *ucp;
327 	const u8 *sense = SRpnt->sense;
328 
329 	s->have_sense = scsi_normalize_sense(SRpnt->sense,
330 				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
331 	s->flags = 0;
332 
333 	if (s->have_sense) {
334 		s->deferred = 0;
335 		s->remainder_valid =
336 			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
337 		switch (sense[0] & 0x7f) {
338 		case 0x71:
339 			s->deferred = 1;
340 		case 0x70:
341 			s->fixed_format = 1;
342 			s->flags = sense[2] & 0xe0;
343 			break;
344 		case 0x73:
345 			s->deferred = 1;
346 		case 0x72:
347 			s->fixed_format = 0;
348 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
349 			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
350 			break;
351 		}
352 	}
353 }
354 
355 
356 /* Convert the result to success code */
357 static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
358 {
359 	int result = SRpnt->result;
360 	u8 scode;
361 	DEB(const char *stp;)
362 	char *name = tape_name(STp);
363 	struct st_cmdstatus *cmdstatp;
364 
365 	if (!result)
366 		return 0;
367 
368 	cmdstatp = &STp->buffer->cmdstat;
369 	st_analyze_sense(SRpnt, cmdstatp);
370 
371 	if (cmdstatp->have_sense)
372 		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
373 	else
374 		scode = 0;
375 
376 	DEB(
377 	if (debugging) {
378 		st_printk(ST_DEB_MSG, STp,
379 			    "Error: %x, cmd: %x %x %x %x %x %x\n", result,
380 			    SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
381 			    SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
382 		if (cmdstatp->have_sense)
383 			__scsi_print_sense(STp->device, name,
384 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
385 	} ) /* end DEB */
386 	if (!debugging) { /* Abnormal conditions for tape */
387 		if (!cmdstatp->have_sense)
388 			st_printk(KERN_WARNING, STp,
389 			       "Error %x (driver bt 0x%x, host bt 0x%x).\n",
390 			       result, driver_byte(result), host_byte(result));
391 		else if (cmdstatp->have_sense &&
392 			 scode != NO_SENSE &&
393 			 scode != RECOVERED_ERROR &&
394 			 /* scode != UNIT_ATTENTION && */
395 			 scode != BLANK_CHECK &&
396 			 scode != VOLUME_OVERFLOW &&
397 			 SRpnt->cmd[0] != MODE_SENSE &&
398 			 SRpnt->cmd[0] != TEST_UNIT_READY) {
399 
400 			__scsi_print_sense(STp->device, name,
401 					   SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
402 		}
403 	}
404 
405 	if (cmdstatp->fixed_format &&
406 	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
407 		if (STp->cln_sense_value)
408 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
409 					       STp->cln_sense_mask) == STp->cln_sense_value);
410 		else
411 			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
412 					       STp->cln_sense_mask) != 0);
413 	}
414 	if (cmdstatp->have_sense &&
415 	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
416 		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */
417 
418 	STp->pos_unknown |= STp->device->was_reset;
419 
420 	if (cmdstatp->have_sense &&
421 	    scode == RECOVERED_ERROR
422 #if ST_RECOVERED_WRITE_FATAL
423 	    && SRpnt->cmd[0] != WRITE_6
424 	    && SRpnt->cmd[0] != WRITE_FILEMARKS
425 #endif
426 	    ) {
427 		STp->recover_count++;
428 		STp->recover_reg++;
429 
430 		DEB(
431 		if (debugging) {
432 			if (SRpnt->cmd[0] == READ_6)
433 				stp = "read";
434 			else if (SRpnt->cmd[0] == WRITE_6)
435 				stp = "write";
436 			else
437 				stp = "ioctl";
438 			st_printk(ST_DEB_MSG, STp,
439 				  "Recovered %s error (%d).\n",
440 				  stp, STp->recover_count);
441 		} ) /* end DEB */
442 
443 		if (cmdstatp->flags == 0)
444 			return 0;
445 	}
446 	return (-EIO);
447 }
448 
449 static struct st_request *st_allocate_request(struct scsi_tape *stp)
450 {
451 	struct st_request *streq;
452 
453 	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
454 	if (streq)
455 		streq->stp = stp;
456 	else {
457 		st_printk(KERN_ERR, stp,
458 			  "Can't get SCSI request.\n");
459 		if (signal_pending(current))
460 			stp->buffer->syscall_result = -EINTR;
461 		else
462 			stp->buffer->syscall_result = -EBUSY;
463 	}
464 
465 	return streq;
466 }
467 
468 static void st_release_request(struct st_request *streq)
469 {
470 	kfree(streq);
471 }
472 
473 static void st_do_stats(struct scsi_tape *STp, struct request *req)
474 {
475 	ktime_t now;
476 
477 	now = ktime_get();
478 	if (req->cmd[0] == WRITE_6) {
479 		now = ktime_sub(now, STp->stats->write_time);
480 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_write_time);
481 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
482 		atomic64_inc(&STp->stats->write_cnt);
483 		if (req->errors) {
484 			atomic64_add(atomic_read(&STp->stats->last_write_size)
485 				- STp->buffer->cmdstat.residual,
486 				&STp->stats->write_byte_cnt);
487 			if (STp->buffer->cmdstat.residual > 0)
488 				atomic64_inc(&STp->stats->resid_cnt);
489 		} else
490 			atomic64_add(atomic_read(&STp->stats->last_write_size),
491 				&STp->stats->write_byte_cnt);
492 	} else if (req->cmd[0] == READ_6) {
493 		now = ktime_sub(now, STp->stats->read_time);
494 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_read_time);
495 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
496 		atomic64_inc(&STp->stats->read_cnt);
497 		if (req->errors) {
498 			atomic64_add(atomic_read(&STp->stats->last_read_size)
499 				- STp->buffer->cmdstat.residual,
500 				&STp->stats->read_byte_cnt);
501 			if (STp->buffer->cmdstat.residual > 0)
502 				atomic64_inc(&STp->stats->resid_cnt);
503 		} else
504 			atomic64_add(atomic_read(&STp->stats->last_read_size),
505 				&STp->stats->read_byte_cnt);
506 	} else {
507 		now = ktime_sub(now, STp->stats->other_time);
508 		atomic64_add(ktime_to_ns(now), &STp->stats->tot_io_time);
509 		atomic64_inc(&STp->stats->other_cnt);
510 	}
511 	atomic64_dec(&STp->stats->in_flight);
512 }
513 
514 static void st_scsi_execute_end(struct request *req, int uptodate)
515 {
516 	struct st_request *SRpnt = req->end_io_data;
517 	struct scsi_tape *STp = SRpnt->stp;
518 	struct bio *tmp;
519 
520 	STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors;
521 	STp->buffer->cmdstat.residual = req->resid_len;
522 
523 	st_do_stats(STp, req);
524 
525 	tmp = SRpnt->bio;
526 	if (SRpnt->waiting)
527 		complete(SRpnt->waiting);
528 
529 	blk_rq_unmap_user(tmp);
530 	__blk_put_request(req->q, req);
531 }
532 
533 static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
534 			   int data_direction, void *buffer, unsigned bufflen,
535 			   int timeout, int retries)
536 {
537 	struct request *req;
538 	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
539 	int err = 0;
540 	int write = (data_direction == DMA_TO_DEVICE);
541 	struct scsi_tape *STp = SRpnt->stp;
542 
543 	req = blk_get_request(SRpnt->stp->device->request_queue, write,
544 			      GFP_KERNEL);
545 	if (IS_ERR(req))
546 		return DRIVER_ERROR << 24;
547 
548 	blk_rq_set_block_pc(req);
549 	req->cmd_flags |= REQ_QUIET;
550 
551 	mdata->null_mapped = 1;
552 
553 	if (bufflen) {
554 		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
555 				      GFP_KERNEL);
556 		if (err) {
557 			blk_put_request(req);
558 			return DRIVER_ERROR << 24;
559 		}
560 	}
561 
562 	atomic64_inc(&STp->stats->in_flight);
563 	if (cmd[0] == WRITE_6) {
564 		atomic_set(&STp->stats->last_write_size, bufflen);
565 		STp->stats->write_time = ktime_get();
566 	} else if (cmd[0] == READ_6) {
567 		atomic_set(&STp->stats->last_read_size, bufflen);
568 		STp->stats->read_time = ktime_get();
569 	} else {
570 		STp->stats->other_time = ktime_get();
571 	}
572 
573 	SRpnt->bio = req->bio;
574 	req->cmd_len = COMMAND_SIZE(cmd[0]);
575 	memset(req->cmd, 0, BLK_MAX_CDB);
576 	memcpy(req->cmd, cmd, req->cmd_len);
577 	req->sense = SRpnt->sense;
578 	req->sense_len = 0;
579 	req->timeout = timeout;
580 	req->retries = retries;
581 	req->end_io_data = SRpnt;
582 
583 	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
584 	return 0;
585 }
586 
587 /* Do the scsi command. Waits until command performed if do_wait is true.
588    Otherwise write_behind_check() is used to check that the command
589    has finished. */
590 static struct st_request *
591 st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
592 	   int bytes, int direction, int timeout, int retries, int do_wait)
593 {
594 	struct completion *waiting;
595 	struct rq_map_data *mdata = &STp->buffer->map_data;
596 	int ret;
597 
598 	/* if async, make sure there's no command outstanding */
599 	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
600 		st_printk(KERN_ERR, STp,
601 			  "Async command already active.\n");
602 		if (signal_pending(current))
603 			(STp->buffer)->syscall_result = (-EINTR);
604 		else
605 			(STp->buffer)->syscall_result = (-EBUSY);
606 		return NULL;
607 	}
608 
609 	if (!SRpnt) {
610 		SRpnt = st_allocate_request(STp);
611 		if (!SRpnt)
612 			return NULL;
613 	}
614 
615 	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
616 	   which IO is outstanding. It's nulled out when the IO completes. */
617 	if (!do_wait)
618 		(STp->buffer)->last_SRpnt = SRpnt;
619 
620 	waiting = &STp->wait;
621 	init_completion(waiting);
622 	SRpnt->waiting = waiting;
623 
624 	if (STp->buffer->do_dio) {
625 		mdata->page_order = 0;
626 		mdata->nr_entries = STp->buffer->sg_segs;
627 		mdata->pages = STp->buffer->mapped_pages;
628 	} else {
629 		mdata->page_order = STp->buffer->reserved_page_order;
630 		mdata->nr_entries =
631 			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
632 		mdata->pages = STp->buffer->reserved_pages;
633 		mdata->offset = 0;
634 	}
635 
636 	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
637 	STp->buffer->cmdstat.have_sense = 0;
638 	STp->buffer->syscall_result = 0;
639 
640 	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
641 			      retries);
642 	if (ret) {
643 		/* could not allocate the buffer or request was too large */
644 		(STp->buffer)->syscall_result = (-EBUSY);
645 		(STp->buffer)->last_SRpnt = NULL;
646 	} else if (do_wait) {
647 		wait_for_completion(waiting);
648 		SRpnt->waiting = NULL;
649 		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
650 	}
651 
652 	return SRpnt;
653 }
654 
655 
656 /* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
657    write has been correct but EOM early warning reached, -EIO if write ended in
658    error or zero if write successful. Asynchronous writes are used only in
659    variable block mode. */
660 static int write_behind_check(struct scsi_tape * STp)
661 {
662 	int retval = 0;
663 	struct st_buffer *STbuffer;
664 	struct st_partstat *STps;
665 	struct st_cmdstatus *cmdstatp;
666 	struct st_request *SRpnt;
667 
668 	STbuffer = STp->buffer;
669 	if (!STbuffer->writing)
670 		return 0;
671 
672 	DEB(
673 	if (STp->write_pending)
674 		STp->nbr_waits++;
675 	else
676 		STp->nbr_finished++;
677 	) /* end DEB */
678 
679 	wait_for_completion(&(STp->wait));
680 	SRpnt = STbuffer->last_SRpnt;
681 	STbuffer->last_SRpnt = NULL;
682 	SRpnt->waiting = NULL;
683 
684 	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
685 	st_release_request(SRpnt);
686 
687 	STbuffer->buffer_bytes -= STbuffer->writing;
688 	STps = &(STp->ps[STp->partition]);
689 	if (STps->drv_block >= 0) {
690 		if (STp->block_size == 0)
691 			STps->drv_block++;
692 		else
693 			STps->drv_block += STbuffer->writing / STp->block_size;
694 	}
695 
696 	cmdstatp = &STbuffer->cmdstat;
697 	if (STbuffer->syscall_result) {
698 		retval = -EIO;
699 		if (cmdstatp->have_sense && !cmdstatp->deferred &&
700 		    (cmdstatp->flags & SENSE_EOM) &&
701 		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
702 		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
703 			/* EOM at write-behind, has all data been written? */
704 			if (!cmdstatp->remainder_valid ||
705 			    cmdstatp->uremainder64 == 0)
706 				retval = -ENOSPC;
707 		}
708 		if (retval == -EIO)
709 			STps->drv_block = -1;
710 	}
711 	STbuffer->writing = 0;
712 
713 	DEB(if (debugging && retval)
714 		    st_printk(ST_DEB_MSG, STp,
715 				"Async write error %x, return value %d.\n",
716 				STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */
717 
718 	return retval;
719 }
720 
721 
722 /* Step over EOF if it has been inadvertently crossed (ioctl not used because
723    it messes up the block number). */
724 static int cross_eof(struct scsi_tape * STp, int forward)
725 {
726 	struct st_request *SRpnt;
727 	unsigned char cmd[MAX_COMMAND_SIZE];
728 
729 	cmd[0] = SPACE;
730 	cmd[1] = 0x01;		/* Space FileMarks */
731 	if (forward) {
732 		cmd[2] = cmd[3] = 0;
733 		cmd[4] = 1;
734 	} else
735 		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
736 	cmd[5] = 0;
737 
738 	DEBC_printk(STp, "Stepping over filemark %s.\n",
739 		    forward ? "forward" : "backward");
740 
741 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
742 			   STp->device->request_queue->rq_timeout,
743 			   MAX_RETRIES, 1);
744 	if (!SRpnt)
745 		return (STp->buffer)->syscall_result;
746 
747 	st_release_request(SRpnt);
748 	SRpnt = NULL;
749 
750 	if ((STp->buffer)->cmdstat.midlevel_result != 0)
751 		st_printk(KERN_ERR, STp,
752 			  "Stepping over filemark %s failed.\n",
753 			  forward ? "forward" : "backward");
754 
755 	return (STp->buffer)->syscall_result;
756 }
757 
758 
759 /* Flush the write buffer (never need to write if variable blocksize). */
760 static int st_flush_write_buffer(struct scsi_tape * STp)
761 {
762 	int transfer, blks;
763 	int result;
764 	unsigned char cmd[MAX_COMMAND_SIZE];
765 	struct st_request *SRpnt;
766 	struct st_partstat *STps;
767 
768 	result = write_behind_check(STp);
769 	if (result)
770 		return result;
771 
772 	result = 0;
773 	if (STp->dirty == 1) {
774 
775 		transfer = STp->buffer->buffer_bytes;
776 		DEBC_printk(STp, "Flushing %d bytes.\n", transfer);
777 
778 		memset(cmd, 0, MAX_COMMAND_SIZE);
779 		cmd[0] = WRITE_6;
780 		cmd[1] = 1;
781 		blks = transfer / STp->block_size;
782 		cmd[2] = blks >> 16;
783 		cmd[3] = blks >> 8;
784 		cmd[4] = blks;
785 
786 		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
787 				   STp->device->request_queue->rq_timeout,
788 				   MAX_WRITE_RETRIES, 1);
789 		if (!SRpnt)
790 			return (STp->buffer)->syscall_result;
791 
792 		STps = &(STp->ps[STp->partition]);
793 		if ((STp->buffer)->syscall_result != 0) {
794 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
795 
796 			if (cmdstatp->have_sense && !cmdstatp->deferred &&
797 			    (cmdstatp->flags & SENSE_EOM) &&
798 			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
799 			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
800 			    (!cmdstatp->remainder_valid ||
801 			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
802 				STp->dirty = 0;
803 				(STp->buffer)->buffer_bytes = 0;
804 				if (STps->drv_block >= 0)
805 					STps->drv_block += blks;
806 				result = (-ENOSPC);
807 			} else {
808 				st_printk(KERN_ERR, STp, "Error on flush.\n");
809 				STps->drv_block = (-1);
810 				result = (-EIO);
811 			}
812 		} else {
813 			if (STps->drv_block >= 0)
814 				STps->drv_block += blks;
815 			STp->dirty = 0;
816 			(STp->buffer)->buffer_bytes = 0;
817 		}
818 		st_release_request(SRpnt);
819 		SRpnt = NULL;
820 	}
821 	return result;
822 }
823 
824 
825 /* Flush the tape buffer. The tape will be positioned correctly unless
826    seek_next is true. */
827 static int flush_buffer(struct scsi_tape *STp, int seek_next)
828 {
829 	int backspace, result;
830 	struct st_buffer *STbuffer;
831 	struct st_partstat *STps;
832 
833 	STbuffer = STp->buffer;
834 
835 	/*
836 	 * If there was a bus reset, block further access
837 	 * to this device.
838 	 */
839 	if (STp->pos_unknown)
840 		return (-EIO);
841 
842 	if (STp->ready != ST_READY)
843 		return 0;
844 	STps = &(STp->ps[STp->partition]);
845 	if (STps->rw == ST_WRITING)	/* Writing */
846 		return st_flush_write_buffer(STp);
847 
848 	if (STp->block_size == 0)
849 		return 0;
850 
851 	backspace = ((STp->buffer)->buffer_bytes +
852 		     (STp->buffer)->read_pointer) / STp->block_size -
853 	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
854 	    STp->block_size;
855 	(STp->buffer)->buffer_bytes = 0;
856 	(STp->buffer)->read_pointer = 0;
857 	result = 0;
858 	if (!seek_next) {
859 		if (STps->eof == ST_FM_HIT) {
860 			result = cross_eof(STp, 0);	/* Back over the EOF hit */
861 			if (!result)
862 				STps->eof = ST_NOEOF;
863 			else {
864 				if (STps->drv_file >= 0)
865 					STps->drv_file++;
866 				STps->drv_block = 0;
867 			}
868 		}
869 		if (!result && backspace > 0)
870 			result = st_int_ioctl(STp, MTBSR, backspace);
871 	} else if (STps->eof == ST_FM_HIT) {
872 		if (STps->drv_file >= 0)
873 			STps->drv_file++;
874 		STps->drv_block = 0;
875 		STps->eof = ST_NOEOF;
876 	}
877 	return result;
878 
879 }
880 
881 /* Set the mode parameters */
882 static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
883 {
884 	int set_it = 0;
885 	unsigned long arg;
886 
887 	if (!STp->density_changed &&
888 	    STm->default_density >= 0 &&
889 	    STm->default_density != STp->density) {
890 		arg = STm->default_density;
891 		set_it = 1;
892 	} else
893 		arg = STp->density;
894 	arg <<= MT_ST_DENSITY_SHIFT;
895 	if (!STp->blksize_changed &&
896 	    STm->default_blksize >= 0 &&
897 	    STm->default_blksize != STp->block_size) {
898 		arg |= STm->default_blksize;
899 		set_it = 1;
900 	} else
901 		arg |= STp->block_size;
902 	if (set_it &&
903 	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
904 		st_printk(KERN_WARNING, STp,
905 			  "Can't set default block size to %d bytes "
906 			  "and density %x.\n",
907 			  STm->default_blksize, STm->default_density);
908 		if (modes_defined)
909 			return (-EINVAL);
910 	}
911 	return 0;
912 }
913 
914 
915 /* Lock or unlock the drive door. Don't use when st_request allocated. */
916 static int do_door_lock(struct scsi_tape * STp, int do_lock)
917 {
918 	int retval;
919 
920 	DEBC_printk(STp, "%socking drive door.\n", do_lock ? "L" : "Unl");
921 
922 	retval = scsi_set_medium_removal(STp->device,
923 			do_lock ? SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
924 	if (!retval)
925 		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
926 	else
927 		STp->door_locked = ST_LOCK_FAILS;
928 	return retval;
929 }
930 
931 
932 /* Set the internal state after reset */
933 static void reset_state(struct scsi_tape *STp)
934 {
935 	int i;
936 	struct st_partstat *STps;
937 
938 	STp->pos_unknown = 0;
939 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
940 		STps = &(STp->ps[i]);
941 		STps->rw = ST_IDLE;
942 		STps->eof = ST_NOEOF;
943 		STps->at_sm = 0;
944 		STps->last_block_valid = 0;
945 		STps->drv_block = -1;
946 		STps->drv_file = -1;
947 	}
948 	if (STp->can_partitions) {
949 		STp->partition = find_partition(STp);
950 		if (STp->partition < 0)
951 			STp->partition = 0;
952 		STp->new_partition = STp->partition;
953 	}
954 }
955 
956 /* Test if the drive is ready. Returns either one of the codes below or a negative system
957    error code. */
958 #define CHKRES_READY       0
959 #define CHKRES_NEW_SESSION 1
960 #define CHKRES_NOT_READY   2
961 #define CHKRES_NO_TAPE     3
962 
963 #define MAX_ATTENTIONS    10
964 
965 static int test_ready(struct scsi_tape *STp, int do_wait)
966 {
967 	int attentions, waits, max_wait, scode;
968 	int retval = CHKRES_READY, new_session = 0;
969 	unsigned char cmd[MAX_COMMAND_SIZE];
970 	struct st_request *SRpnt = NULL;
971 	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
972 
973 	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;
974 
975 	for (attentions=waits=0; ; ) {
976 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
977 		cmd[0] = TEST_UNIT_READY;
978 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
979 				   STp->long_timeout, MAX_READY_RETRIES, 1);
980 
981 		if (!SRpnt) {
982 			retval = (STp->buffer)->syscall_result;
983 			break;
984 		}
985 
986 		if (cmdstatp->have_sense) {
987 
988 			scode = cmdstatp->sense_hdr.sense_key;
989 
990 			if (scode == UNIT_ATTENTION) { /* New media? */
991 				new_session = 1;
992 				if (attentions < MAX_ATTENTIONS) {
993 					attentions++;
994 					continue;
995 				}
996 				else {
997 					retval = (-EIO);
998 					break;
999 				}
1000 			}
1001 
1002 			if (scode == NOT_READY) {
1003 				if (waits < max_wait) {
1004 					if (msleep_interruptible(1000)) {
1005 						retval = (-EINTR);
1006 						break;
1007 					}
1008 					waits++;
1009 					continue;
1010 				}
1011 				else {
1012 					if ((STp->device)->scsi_level >= SCSI_2 &&
1013 					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
1014 						retval = CHKRES_NO_TAPE;
1015 					else
1016 						retval = CHKRES_NOT_READY;
1017 					break;
1018 				}
1019 			}
1020 		}
1021 
1022 		retval = (STp->buffer)->syscall_result;
1023 		if (!retval)
1024 			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
1025 		break;
1026 	}
1027 
1028 	if (SRpnt != NULL)
1029 		st_release_request(SRpnt);
1030 	return retval;
1031 }
1032 
1033 
1034 /* See if the drive is ready and gather information about the tape. Return values:
1035    < 0   negative error code from errno.h
1036    0     drive ready
1037    1     drive not ready (possibly no tape)
1038 */
1039 static int check_tape(struct scsi_tape *STp, struct file *filp)
1040 {
1041 	int i, retval, new_session = 0, do_wait;
1042 	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
1043 	unsigned short st_flags = filp->f_flags;
1044 	struct st_request *SRpnt = NULL;
1045 	struct st_modedef *STm;
1046 	struct st_partstat *STps;
1047 	struct inode *inode = file_inode(filp);
1048 	int mode = TAPE_MODE(inode);
1049 
1050 	STp->ready = ST_READY;
1051 
1052 	if (mode != STp->current_mode) {
1053 		DEBC_printk(STp, "Mode change from %d to %d.\n",
1054 			    STp->current_mode, mode);
1055 		new_session = 1;
1056 		STp->current_mode = mode;
1057 	}
1058 	STm = &(STp->modes[STp->current_mode]);
1059 
1060 	saved_cleaning = STp->cleaning_req;
1061 	STp->cleaning_req = 0;
1062 
1063 	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
1064 	retval = test_ready(STp, do_wait);
1065 
1066 	if (retval < 0)
1067 	    goto err_out;
1068 
1069 	if (retval == CHKRES_NEW_SESSION) {
1070 		STp->pos_unknown = 0;
1071 		STp->partition = STp->new_partition = 0;
1072 		if (STp->can_partitions)
1073 			STp->nbr_partitions = 1; /* This guess will be updated later
1074                                                     if necessary */
1075 		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1076 			STps = &(STp->ps[i]);
1077 			STps->rw = ST_IDLE;
1078 			STps->eof = ST_NOEOF;
1079 			STps->at_sm = 0;
1080 			STps->last_block_valid = 0;
1081 			STps->drv_block = 0;
1082 			STps->drv_file = 0;
1083 		}
1084 		new_session = 1;
1085 	}
1086 	else {
1087 		STp->cleaning_req |= saved_cleaning;
1088 
1089 		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
1090 			if (retval == CHKRES_NO_TAPE)
1091 				STp->ready = ST_NO_TAPE;
1092 			else
1093 				STp->ready = ST_NOT_READY;
1094 
1095 			STp->density = 0;	/* Clear the erroneous "residue" */
1096 			STp->write_prot = 0;
1097 			STp->block_size = 0;
1098 			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
1099 			STp->partition = STp->new_partition = 0;
1100 			STp->door_locked = ST_UNLOCKED;
1101 			return CHKRES_NOT_READY;
1102 		}
1103 	}
1104 
1105 	if (STp->omit_blklims)
1106 		STp->min_block = STp->max_block = (-1);
1107 	else {
1108 		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1109 		cmd[0] = READ_BLOCK_LIMITS;
1110 
1111 		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
1112 				   STp->device->request_queue->rq_timeout,
1113 				   MAX_READY_RETRIES, 1);
1114 		if (!SRpnt) {
1115 			retval = (STp->buffer)->syscall_result;
1116 			goto err_out;
1117 		}
1118 
1119 		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
1120 			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
1121 			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
1122 			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
1123 			    (STp->buffer)->b_data[5];
1124 			if ( DEB( debugging || ) !STp->inited)
1125 				st_printk(KERN_INFO, STp,
1126 					  "Block limits %d - %d bytes.\n",
1127 					  STp->min_block, STp->max_block);
1128 		} else {
1129 			STp->min_block = STp->max_block = (-1);
1130 			DEBC_printk(STp, "Can't read block limits.\n");
1131 		}
1132 	}
1133 
1134 	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
1135 	cmd[0] = MODE_SENSE;
1136 	cmd[4] = 12;
1137 
1138 	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
1139 			   STp->device->request_queue->rq_timeout,
1140 			   MAX_READY_RETRIES, 1);
1141 	if (!SRpnt) {
1142 		retval = (STp->buffer)->syscall_result;
1143 		goto err_out;
1144 	}
1145 
1146 	if ((STp->buffer)->syscall_result != 0) {
1147 		DEBC_printk(STp, "No Mode Sense.\n");
1148 		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
1149 		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
1150 		STp->drv_write_prot = 0;
1151 	} else {
1152 		DEBC_printk(STp,"Mode sense. Length %d, "
1153 			    "medium %x, WBS %x, BLL %d\n",
1154 			    (STp->buffer)->b_data[0],
1155 			    (STp->buffer)->b_data[1],
1156 			    (STp->buffer)->b_data[2],
1157 			    (STp->buffer)->b_data[3]);
1158 
1159 		if ((STp->buffer)->b_data[3] >= 8) {
1160 			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
1161 			STp->density = (STp->buffer)->b_data[4];
1162 			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
1163 			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
1164 			DEBC_printk(STp, "Density %x, tape length: %x, "
1165 				    "drv buffer: %d\n",
1166 				    STp->density,
1167 				    (STp->buffer)->b_data[5] * 65536 +
1168 				    (STp->buffer)->b_data[6] * 256 +
1169 				    (STp->buffer)->b_data[7],
1170 				    STp->drv_buffer);
1171 		}
1172 		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
1173 		if (!STp->drv_buffer && STp->immediate_filemark) {
1174 			st_printk(KERN_WARNING, STp,
1175 				  "non-buffered tape: disabling "
1176 				  "writing immediate filemarks\n");
1177 			STp->immediate_filemark = 0;
1178 		}
1179 	}
1180 	st_release_request(SRpnt);
1181 	SRpnt = NULL;
1182 	STp->inited = 1;
1183 
1184 	if (STp->block_size > 0)
1185 		(STp->buffer)->buffer_blocks =
1186 			(STp->buffer)->buffer_size / STp->block_size;
1187 	else
1188 		(STp->buffer)->buffer_blocks = 1;
1189 	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
1190 
1191 	DEBC_printk(STp, "Block size: %d, buffer size: %d (%d blocks).\n",
1192 		    STp->block_size, (STp->buffer)->buffer_size,
1193 		    (STp->buffer)->buffer_blocks);
1194 
1195 	if (STp->drv_write_prot) {
1196 		STp->write_prot = 1;
1197 
1198 		DEBC_printk(STp, "Write protected\n");
1199 
1200 		if (do_wait &&
1201 		    ((st_flags & O_ACCMODE) == O_WRONLY ||
1202 		     (st_flags & O_ACCMODE) == O_RDWR)) {
1203 			retval = (-EROFS);
1204 			goto err_out;
1205 		}
1206 	}
1207 
1208 	if (STp->can_partitions && STp->nbr_partitions < 1) {
1209 		/* This code is reached when the device is opened for the first time
1210 		   after the driver has been initialized with tape in the drive and the
1211 		   partition support has been enabled. */
1212 		DEBC_printk(STp, "Updating partition number in status.\n");
1213 		if ((STp->partition = find_partition(STp)) < 0) {
1214 			retval = STp->partition;
1215 			goto err_out;
1216 		}
1217 		STp->new_partition = STp->partition;
1218 		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
1219 	}
1220 
1221 	if (new_session) {	/* Change the drive parameters for the new mode */
1222 		STp->density_changed = STp->blksize_changed = 0;
1223 		STp->compression_changed = 0;
1224 		if (!(STm->defaults_for_writes) &&
1225 		    (retval = set_mode_densblk(STp, STm)) < 0)
1226 		    goto err_out;
1227 
1228 		if (STp->default_drvbuffer != 0xff) {
1229 			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
1230 				st_printk(KERN_WARNING, STp,
1231 					  "Can't set default drive "
1232 					  "buffering to %d.\n",
1233 					  STp->default_drvbuffer);
1234 		}
1235 	}
1236 
1237 	return CHKRES_READY;
1238 
1239  err_out:
1240 	return retval;
1241 }
1242 
1243 
1244 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host
1245    module count. */
1246 static int st_open(struct inode *inode, struct file *filp)
1247 {
1248 	int i, retval = (-EIO);
1249 	int resumed = 0;
1250 	struct scsi_tape *STp;
1251 	struct st_partstat *STps;
1252 	int dev = TAPE_NR(inode);
1253 
1254 	/*
1255 	 * We really want to do nonseekable_open(inode, filp); here, but some
1256 	 * versions of tar incorrectly call lseek on tapes and bail out if that
1257 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
1258 	 */
1259 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
1260 
1261 	if (!(STp = scsi_tape_get(dev))) {
1262 		return -ENXIO;
1263 	}
1264 
1265 	filp->private_data = STp;
1266 
1267 	spin_lock(&st_use_lock);
1268 	if (STp->in_use) {
1269 		spin_unlock(&st_use_lock);
1270 		scsi_tape_put(STp);
1271 		DEBC_printk(STp, "Device already in use.\n");
1272 		return (-EBUSY);
1273 	}
1274 
1275 	STp->in_use = 1;
1276 	spin_unlock(&st_use_lock);
1277 	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
1278 
1279 	if (scsi_autopm_get_device(STp->device) < 0) {
1280 		retval = -EIO;
1281 		goto err_out;
1282 	}
1283 	resumed = 1;
1284 	if (!scsi_block_when_processing_errors(STp->device)) {
1285 		retval = (-ENXIO);
1286 		goto err_out;
1287 	}
1288 
1289 	/* See that we have at least a one page buffer available */
1290 	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
1291 		st_printk(KERN_WARNING, STp,
1292 			  "Can't allocate one page tape buffer.\n");
1293 		retval = (-EOVERFLOW);
1294 		goto err_out;
1295 	}
1296 
1297 	(STp->buffer)->cleared = 0;
1298 	(STp->buffer)->writing = 0;
1299 	(STp->buffer)->syscall_result = 0;
1300 
1301 	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);
1302 
1303 	STp->dirty = 0;
1304 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
1305 		STps = &(STp->ps[i]);
1306 		STps->rw = ST_IDLE;
1307 	}
1308 	STp->try_dio_now = STp->try_dio;
1309 	STp->recover_count = 0;
1310 	DEB( STp->nbr_waits = STp->nbr_finished = 0;
1311 	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )
1312 
1313 	retval = check_tape(STp, filp);
1314 	if (retval < 0)
1315 		goto err_out;
1316 	if ((filp->f_flags & O_NONBLOCK) == 0 &&
1317 	    retval != CHKRES_READY) {
1318 		if (STp->ready == NO_TAPE)
1319 			retval = (-ENOMEDIUM);
1320 		else
1321 			retval = (-EIO);
1322 		goto err_out;
1323 	}
1324 	return 0;
1325 
1326  err_out:
1327 	normalize_buffer(STp->buffer);
1328 	spin_lock(&st_use_lock);
1329 	STp->in_use = 0;
1330 	spin_unlock(&st_use_lock);
1331 	if (resumed)
1332 		scsi_autopm_put_device(STp->device);
1333 	scsi_tape_put(STp);
1334 	return retval;
1335 
1336 }
1337 
1338 
1339 /* Flush the tape buffer before close */
1340 static int st_flush(struct file *filp, fl_owner_t id)
1341 {
1342 	int result = 0, result2;
1343 	unsigned char cmd[MAX_COMMAND_SIZE];
1344 	struct st_request *SRpnt;
1345 	struct scsi_tape *STp = filp->private_data;
1346 	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
1347 	struct st_partstat *STps = &(STp->ps[STp->partition]);
1348 
1349 	if (file_count(filp) > 1)
1350 		return 0;
1351 
1352 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1353 		result = st_flush_write_buffer(STp);
1354 		if (result != 0 && result != (-ENOSPC))
1355 			goto out;
1356 	}
1357 
1358 	if (STp->can_partitions &&
1359 	    (result2 = switch_partition(STp)) < 0) {
1360 		DEBC_printk(STp, "switch_partition at close failed.\n");
1361 		if (result == 0)
1362 			result = result2;
1363 		goto out;
1364 	}
1365 
1366 	DEBC( if (STp->nbr_requests)
1367 		st_printk(KERN_DEBUG, STp,
1368 			  "Number of r/w requests %d, dio used in %d, "
1369 			  "pages %d.\n", STp->nbr_requests, STp->nbr_dio,
1370 			  STp->nbr_pages));
1371 
1372 	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
1373 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1374 
1375 #if DEBUG
1376 		DEBC_printk(STp, "Async write waits %d, finished %d.\n",
1377 			    STp->nbr_waits, STp->nbr_finished);
1378 #endif
1379 		memset(cmd, 0, MAX_COMMAND_SIZE);
1380 		cmd[0] = WRITE_FILEMARKS;
1381 		if (STp->immediate_filemark)
1382 			cmd[1] = 1;
1383 		cmd[4] = 1 + STp->two_fm;
1384 
1385 		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
1386 				   STp->device->request_queue->rq_timeout,
1387 				   MAX_WRITE_RETRIES, 1);
1388 		if (!SRpnt) {
1389 			result = (STp->buffer)->syscall_result;
1390 			goto out;
1391 		}
1392 
1393 		if (STp->buffer->syscall_result == 0 ||
1394 		    (cmdstatp->have_sense && !cmdstatp->deferred &&
1395 		     (cmdstatp->flags & SENSE_EOM) &&
1396 		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
1397 		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
1398 		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
1399 			/* Write successful at EOM */
1400 			st_release_request(SRpnt);
1401 			SRpnt = NULL;
1402 			if (STps->drv_file >= 0)
1403 				STps->drv_file++;
1404 			STps->drv_block = 0;
1405 			if (STp->two_fm)
1406 				cross_eof(STp, 0);
1407 			STps->eof = ST_FM;
1408 		}
1409 		else { /* Write error */
1410 			st_release_request(SRpnt);
1411 			SRpnt = NULL;
1412 			st_printk(KERN_ERR, STp,
1413 				  "Error on write filemark.\n");
1414 			if (result == 0)
1415 				result = (-EIO);
1416 		}
1417 
1418 		DEBC_printk(STp, "Buffer flushed, %d EOF(s) written\n", cmd[4]);
1419 	} else if (!STp->rew_at_close) {
1420 		STps = &(STp->ps[STp->partition]);
1421 		if (!STm->sysv || STps->rw != ST_READING) {
1422 			if (STp->can_bsr)
1423 				result = flush_buffer(STp, 0);
1424 			else if (STps->eof == ST_FM_HIT) {
1425 				result = cross_eof(STp, 0);
1426 				if (result) {
1427 					if (STps->drv_file >= 0)
1428 						STps->drv_file++;
1429 					STps->drv_block = 0;
1430 					STps->eof = ST_FM;
1431 				} else
1432 					STps->eof = ST_NOEOF;
1433 			}
1434 		} else if ((STps->eof == ST_NOEOF &&
1435 			    !(result = cross_eof(STp, 1))) ||
1436 			   STps->eof == ST_FM_HIT) {
1437 			if (STps->drv_file >= 0)
1438 				STps->drv_file++;
1439 			STps->drv_block = 0;
1440 			STps->eof = ST_FM;
1441 		}
1442 	}
1443 
1444       out:
1445 	if (STp->rew_at_close) {
1446 		result2 = st_int_ioctl(STp, MTREW, 1);
1447 		if (result == 0)
1448 			result = result2;
1449 	}
1450 	return result;
1451 }
1452 
1453 
1454 /* Close the device and release it. BKL is not needed: this is the only thread
1455    accessing this tape. */
1456 static int st_release(struct inode *inode, struct file *filp)
1457 {
1458 	int result = 0;
1459 	struct scsi_tape *STp = filp->private_data;
1460 
1461 	if (STp->door_locked == ST_LOCKED_AUTO)
1462 		do_door_lock(STp, 0);
1463 
1464 	normalize_buffer(STp->buffer);
1465 	spin_lock(&st_use_lock);
1466 	STp->in_use = 0;
1467 	spin_unlock(&st_use_lock);
1468 	scsi_autopm_put_device(STp->device);
1469 	scsi_tape_put(STp);
1470 
1471 	return result;
1472 }
1473 
1474 /* The checks common to both reading and writing */
1475 static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
1476 {
1477 	ssize_t retval = 0;
1478 
1479 	/*
1480 	 * If we are in the middle of error recovery, don't let anyone
1481 	 * else try and use this device.  Also, if error recovery fails, it
1482 	 * may try and take the device offline, in which case all further
1483 	 * access to the device is prohibited.
1484 	 */
1485 	if (!scsi_block_when_processing_errors(STp->device)) {
1486 		retval = (-ENXIO);
1487 		goto out;
1488 	}
1489 
1490 	if (STp->ready != ST_READY) {
1491 		if (STp->ready == ST_NO_TAPE)
1492 			retval = (-ENOMEDIUM);
1493 		else
1494 			retval = (-EIO);
1495 		goto out;
1496 	}
1497 
1498 	if (! STp->modes[STp->current_mode].defined) {
1499 		retval = (-ENXIO);
1500 		goto out;
1501 	}
1502 
1503 
1504 	/*
1505 	 * If there was a bus reset, block further access
1506 	 * to this device.
1507 	 */
1508 	if (STp->pos_unknown) {
1509 		retval = (-EIO);
1510 		goto out;
1511 	}
1512 
1513 	if (count == 0)
1514 		goto out;
1515 
1516 	DEB(
1517 	if (!STp->in_use) {
1518 		st_printk(ST_DEB_MSG, STp,
1519 			  "Incorrect device.\n");
1520 		retval = (-EIO);
1521 		goto out;
1522 	} ) /* end DEB */
1523 
1524 	if (STp->can_partitions &&
1525 	    (retval = switch_partition(STp)) < 0)
1526 		goto out;
1527 
1528 	if (STp->block_size == 0 && STp->max_block > 0 &&
1529 	    (count < STp->min_block || count > STp->max_block)) {
1530 		retval = (-EINVAL);
1531 		goto out;
1532 	}
1533 
1534 	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
1535 	    !do_door_lock(STp, 1))
1536 		STp->door_locked = ST_LOCKED_AUTO;
1537 
1538  out:
1539 	return retval;
1540 }
1541 
1542 
1543 static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
1544 			   size_t count, int is_read)
1545 {
1546 	int i, bufsize, retval = 0;
1547 	struct st_buffer *STbp = STp->buffer;
1548 
1549 	if (is_read)
1550 		i = STp->try_dio_now && try_rdio;
1551 	else
1552 		i = STp->try_dio_now && try_wdio;
1553 
1554 	if (i && ((unsigned long)buf & queue_dma_alignment(
1555 					STp->device->request_queue)) == 0) {
1556 		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
1557 				       count, (is_read ? READ : WRITE));
1558 		if (i > 0) {
1559 			STbp->do_dio = i;
1560 			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
1561 		}
1562 		else
1563 			STbp->do_dio = 0;  /* fall back to buffering with any error */
1564 		STbp->sg_segs = STbp->do_dio;
1565 		DEB(
1566 		     if (STbp->do_dio) {
1567 			STp->nbr_dio++;
1568 			STp->nbr_pages += STbp->do_dio;
1569 		     }
1570 		)
1571 	} else
1572 		STbp->do_dio = 0;
1573 	DEB( STp->nbr_requests++; )
1574 
1575 	if (!STbp->do_dio) {
1576 		if (STp->block_size)
1577 			bufsize = STp->block_size > st_fixed_buffer_size ?
1578 				STp->block_size : st_fixed_buffer_size;
1579 		else {
1580 			bufsize = count;
1581 			/* Make sure that data from previous user is not leaked even if
1582 			   HBA does not return correct residual */
1583 			if (is_read && STp->sili && !STbp->cleared)
1584 				clear_buffer(STbp);
1585 		}
1586 
1587 		if (bufsize > STbp->buffer_size &&
1588 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1589 			st_printk(KERN_WARNING, STp,
1590 				  "Can't allocate %d byte tape buffer.\n",
1591 				  bufsize);
1592 			retval = (-EOVERFLOW);
1593 			goto out;
1594 		}
1595 		if (STp->block_size)
1596 			STbp->buffer_blocks = bufsize / STp->block_size;
1597 	}
1598 
1599  out:
1600 	return retval;
1601 }
1602 
1603 
1604 /* Can be called more than once after each setup_buffer() */
1605 static void release_buffering(struct scsi_tape *STp, int is_read)
1606 {
1607 	struct st_buffer *STbp;
1608 
1609 	STbp = STp->buffer;
1610 	if (STbp->do_dio) {
1611 		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
1612 		STbp->do_dio = 0;
1613 		STbp->sg_segs = 0;
1614 	}
1615 }
1616 
1617 
1618 /* Write command */
1619 static ssize_t
1620 st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
1621 {
1622 	ssize_t total;
1623 	ssize_t i, do_count, blks, transfer;
1624 	ssize_t retval;
1625 	int undone, retry_eot = 0, scode;
1626 	int async_write;
1627 	unsigned char cmd[MAX_COMMAND_SIZE];
1628 	const char __user *b_point;
1629 	struct st_request *SRpnt = NULL;
1630 	struct scsi_tape *STp = filp->private_data;
1631 	struct st_modedef *STm;
1632 	struct st_partstat *STps;
1633 	struct st_buffer *STbp;
1634 
1635 	if (mutex_lock_interruptible(&STp->lock))
1636 		return -ERESTARTSYS;
1637 
1638 	retval = rw_checks(STp, filp, count);
1639 	if (retval || count == 0)
1640 		goto out;
1641 
1642 	/* Write must be integral number of blocks */
1643 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
1644 		st_printk(KERN_WARNING, STp,
1645 			  "Write not multiple of tape block size.\n");
1646 		retval = (-EINVAL);
1647 		goto out;
1648 	}
1649 
1650 	STm = &(STp->modes[STp->current_mode]);
1651 	STps = &(STp->ps[STp->partition]);
1652 
1653 	if (STp->write_prot) {
1654 		retval = (-EACCES);
1655 		goto out;
1656 	}
1657 
1658 
1659 	if (STps->rw == ST_READING) {
1660 		retval = flush_buffer(STp, 0);
1661 		if (retval)
1662 			goto out;
1663 		STps->rw = ST_WRITING;
1664 	} else if (STps->rw != ST_WRITING &&
1665 		   STps->drv_file == 0 && STps->drv_block == 0) {
1666 		if ((retval = set_mode_densblk(STp, STm)) < 0)
1667 			goto out;
1668 		if (STm->default_compression != ST_DONT_TOUCH &&
1669 		    !(STp->compression_changed)) {
1670 			if (st_compression(STp, (STm->default_compression == ST_YES))) {
1671 				st_printk(KERN_WARNING, STp,
1672 					  "Can't set default compression.\n");
1673 				if (modes_defined) {
1674 					retval = (-EINVAL);
1675 					goto out;
1676 				}
1677 			}
1678 		}
1679 	}
1680 
1681 	STbp = STp->buffer;
1682 	i = write_behind_check(STp);
1683 	if (i) {
1684 		if (i == -ENOSPC)
1685 			STps->eof = ST_EOM_OK;
1686 		else
1687 			STps->eof = ST_EOM_ERROR;
1688 	}
1689 
1690 	if (STps->eof == ST_EOM_OK) {
1691 		STps->eof = ST_EOD_1;  /* allow next write */
1692 		retval = (-ENOSPC);
1693 		goto out;
1694 	}
1695 	else if (STps->eof == ST_EOM_ERROR) {
1696 		retval = (-EIO);
1697 		goto out;
1698 	}
1699 
1700 	/* Check the buffer readability in cases where copy_user might catch
1701 	   the problems after some tape movement. */
1702 	if (STp->block_size != 0 &&
1703 	    !STbp->do_dio &&
1704 	    (copy_from_user(&i, buf, 1) != 0 ||
1705 	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
1706 		retval = (-EFAULT);
1707 		goto out;
1708 	}
1709 
1710 	retval = setup_buffering(STp, buf, count, 0);
1711 	if (retval)
1712 		goto out;
1713 
1714 	total = count;
1715 
1716 	memset(cmd, 0, MAX_COMMAND_SIZE);
1717 	cmd[0] = WRITE_6;
1718 	cmd[1] = (STp->block_size != 0);
1719 
1720 	STps->rw = ST_WRITING;
1721 
1722 	b_point = buf;
1723 	while (count > 0 && !retry_eot) {
1724 
1725 		if (STbp->do_dio) {
1726 			do_count = count;
1727 		}
1728 		else {
1729 			if (STp->block_size == 0)
1730 				do_count = count;
1731 			else {
1732 				do_count = STbp->buffer_blocks * STp->block_size -
1733 					STbp->buffer_bytes;
1734 				if (do_count > count)
1735 					do_count = count;
1736 			}
1737 
1738 			i = append_to_buffer(b_point, STbp, do_count);
1739 			if (i) {
1740 				retval = i;
1741 				goto out;
1742 			}
1743 		}
1744 		count -= do_count;
1745 		b_point += do_count;
1746 
1747 		async_write = STp->block_size == 0 && !STbp->do_dio &&
1748 			STm->do_async_writes && STps->eof < ST_EOM_OK;
1749 
1750 		if (STp->block_size != 0 && STm->do_buffer_writes &&
1751 		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
1752 		    STbp->buffer_bytes < STbp->buffer_size) {
1753 			STp->dirty = 1;
1754 			/* Don't write a buffer that is not full enough. */
1755 			if (!async_write && count == 0)
1756 				break;
1757 		}
1758 
1759 	retry_write:
1760 		if (STp->block_size == 0)
1761 			blks = transfer = do_count;
1762 		else {
1763 			if (!STbp->do_dio)
1764 				blks = STbp->buffer_bytes;
1765 			else
1766 				blks = do_count;
1767 			blks /= STp->block_size;
1768 			transfer = blks * STp->block_size;
1769 		}
1770 		cmd[2] = blks >> 16;
1771 		cmd[3] = blks >> 8;
1772 		cmd[4] = blks;
1773 
1774 		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
1775 				   STp->device->request_queue->rq_timeout,
1776 				   MAX_WRITE_RETRIES, !async_write);
1777 		if (!SRpnt) {
1778 			retval = STbp->syscall_result;
1779 			goto out;
1780 		}
1781 		if (async_write && !STbp->syscall_result) {
1782 			STbp->writing = transfer;
1783 			STp->dirty = !(STbp->writing ==
1784 				       STbp->buffer_bytes);
1785 			SRpnt = NULL;  /* Prevent releasing this request! */
1786 			DEB( STp->write_pending = 1; )
1787 			break;
1788 		}
1789 
1790 		if (STbp->syscall_result != 0) {
1791 			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1792 
1793 			DEBC_printk(STp, "Error on write:\n");
1794 			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
1795 				scode = cmdstatp->sense_hdr.sense_key;
1796 				if (cmdstatp->remainder_valid)
1797 					undone = (int)cmdstatp->uremainder64;
1798 				else if (STp->block_size == 0 &&
1799 					 scode == VOLUME_OVERFLOW)
1800 					undone = transfer;
1801 				else
1802 					undone = 0;
1803 				if (STp->block_size != 0)
1804 					undone *= STp->block_size;
1805 				if (undone <= do_count) {
1806 					/* Only data from this write is not written */
1807 					count += undone;
1808 					b_point -= undone;
1809 					do_count -= undone;
1810 					if (STp->block_size)
1811 						blks = (transfer - undone) / STp->block_size;
1812 					STps->eof = ST_EOM_OK;
1813 					/* Continue in fixed block mode if all written
1814 					   in this request but still something left to write
1815 					   (retval left to zero)
1816 					*/
1817 					if (STp->block_size == 0 ||
1818 					    undone > 0 || count == 0)
1819 						retval = (-ENOSPC); /* EOM within current request */
1820 					DEBC_printk(STp, "EOM with %d "
1821 						    "bytes unwritten.\n",
1822 						    (int)count);
1823 				} else {
1824 					/* EOT within data buffered earlier (possible only
1825 					   in fixed block mode without direct i/o) */
1826 					if (!retry_eot && !cmdstatp->deferred &&
1827 					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
1828 						move_buffer_data(STp->buffer, transfer - undone);
1829 						retry_eot = 1;
1830 						if (STps->drv_block >= 0) {
1831 							STps->drv_block += (transfer - undone) /
1832 								STp->block_size;
1833 						}
1834 						STps->eof = ST_EOM_OK;
1835 						DEBC_printk(STp, "Retry "
1836 							    "write of %d "
1837 							    "bytes at EOM.\n",
1838 							    STp->buffer->buffer_bytes);
1839 						goto retry_write;
1840 					}
1841 					else {
1842 						/* Either error within data buffered by driver or
1843 						   failed retry */
1844 						count -= do_count;
1845 						blks = do_count = 0;
1846 						STps->eof = ST_EOM_ERROR;
1847 						STps->drv_block = (-1); /* Too cautious? */
1848 						retval = (-EIO);	/* EOM for old data */
1849 						DEBC_printk(STp, "EOM with "
1850 							    "lost data.\n");
1851 					}
1852 				}
1853 			} else {
1854 				count += do_count;
1855 				STps->drv_block = (-1);		/* Too cautious? */
1856 				retval = STbp->syscall_result;
1857 			}
1858 
1859 		}
1860 
1861 		if (STps->drv_block >= 0) {
1862 			if (STp->block_size == 0)
1863 				STps->drv_block += (do_count > 0);
1864 			else
1865 				STps->drv_block += blks;
1866 		}
1867 
1868 		STbp->buffer_bytes = 0;
1869 		STp->dirty = 0;
1870 
1871 		if (retval || retry_eot) {
1872 			if (count < total)
1873 				retval = total - count;
1874 			goto out;
1875 		}
1876 	}
1877 
1878 	if (STps->eof == ST_EOD_1)
1879 		STps->eof = ST_EOM_OK;
1880 	else if (STps->eof != ST_EOM_OK)
1881 		STps->eof = ST_NOEOF;
1882 	retval = total - count;
1883 
1884  out:
1885 	if (SRpnt != NULL)
1886 		st_release_request(SRpnt);
1887 	release_buffering(STp, 0);
1888 	mutex_unlock(&STp->lock);
1889 
1890 	return retval;
1891 }
1892 
1893 /* Read data from the tape. Returns zero in the normal case, one if the
1894    eof status has changed, and the negative error code in case of a
1895    fatal error. Otherwise updates the buffer and the eof state.
1896 
1897    Does release user buffer mapping if it is set.
1898 */
1899 static long read_tape(struct scsi_tape *STp, long count,
1900 		      struct st_request ** aSRpnt)
1901 {
1902 	int transfer, blks, bytes;
1903 	unsigned char cmd[MAX_COMMAND_SIZE];
1904 	struct st_request *SRpnt;
1905 	struct st_modedef *STm;
1906 	struct st_partstat *STps;
1907 	struct st_buffer *STbp;
1908 	int retval = 0;
1909 
1910 	if (count == 0)
1911 		return 0;
1912 
1913 	STm = &(STp->modes[STp->current_mode]);
1914 	STps = &(STp->ps[STp->partition]);
1915 	if (STps->eof == ST_FM_HIT)
1916 		return 1;
1917 	STbp = STp->buffer;
1918 
1919 	if (STp->block_size == 0)
1920 		blks = bytes = count;
1921 	else {
1922 		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
1923 			blks = (STp->buffer)->buffer_blocks;
1924 			bytes = blks * STp->block_size;
1925 		} else {
1926 			bytes = count;
1927 			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
1928 				bytes = (STp->buffer)->buffer_size;
1929 			blks = bytes / STp->block_size;
1930 			bytes = blks * STp->block_size;
1931 		}
1932 	}
1933 
1934 	memset(cmd, 0, MAX_COMMAND_SIZE);
1935 	cmd[0] = READ_6;
1936 	cmd[1] = (STp->block_size != 0);
1937 	if (!cmd[1] && STp->sili)
1938 		cmd[1] |= 2;
1939 	cmd[2] = blks >> 16;
1940 	cmd[3] = blks >> 8;
1941 	cmd[4] = blks;
1942 
1943 	SRpnt = *aSRpnt;
1944 	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
1945 			   STp->device->request_queue->rq_timeout,
1946 			   MAX_RETRIES, 1);
1947 	release_buffering(STp, 1);
1948 	*aSRpnt = SRpnt;
1949 	if (!SRpnt)
1950 		return STbp->syscall_result;
1951 
1952 	STbp->read_pointer = 0;
1953 	STps->at_sm = 0;
1954 
1955 	/* Something to check */
1956 	if (STbp->syscall_result) {
1957 		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
1958 
1959 		retval = 1;
1960 		DEBC_printk(STp,
1961 			    "Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
1962 			    SRpnt->sense[0], SRpnt->sense[1],
1963 			    SRpnt->sense[2], SRpnt->sense[3],
1964 			    SRpnt->sense[4], SRpnt->sense[5],
1965 			    SRpnt->sense[6], SRpnt->sense[7]);
1966 		if (cmdstatp->have_sense) {
1967 
1968 			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
1969 				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */
1970 
1971 			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
1972 				/* Compute the residual count */
1973 				if (cmdstatp->remainder_valid)
1974 					transfer = (int)cmdstatp->uremainder64;
1975 				else
1976 					transfer = 0;
1977 				if (cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR) {
1978 					if (STp->block_size == 0)
1979 						transfer = bytes;
1980 					/* Some drives set ILI with MEDIUM ERROR */
1981 					cmdstatp->flags &= ~SENSE_ILI;
1982 				}
1983 
1984 				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
1985 					if (STp->block_size == 0 &&
1986 					    transfer < 0) {
1987 						st_printk(KERN_NOTICE, STp,
1988 							  "Failed to read %d "
1989 							  "byte block with %d "
1990 							  "byte transfer.\n",
1991 							  bytes - transfer,
1992 							  bytes);
1993 						if (STps->drv_block >= 0)
1994 							STps->drv_block += 1;
1995 						STbp->buffer_bytes = 0;
1996 						return (-ENOMEM);
1997 					} else if (STp->block_size == 0) {
1998 						STbp->buffer_bytes = bytes - transfer;
1999 					} else {
2000 						st_release_request(SRpnt);
2001 						SRpnt = *aSRpnt = NULL;
2002 						if (transfer == blks) {	/* We did not get anything, error */
2003 							st_printk(KERN_NOTICE, STp,
2004 								  "Incorrect "
2005 								  "block size.\n");
2006 							if (STps->drv_block >= 0)
2007 								STps->drv_block += blks - transfer + 1;
2008 							st_int_ioctl(STp, MTBSR, 1);
2009 							return (-EIO);
2010 						}
2011 						/* We have some data, deliver it */
2012 						STbp->buffer_bytes = (blks - transfer) *
2013 						    STp->block_size;
2014 						DEBC_printk(STp, "ILI but "
2015 							    "enough data "
2016 							    "received %ld "
2017 							    "%d.\n", count,
2018 							    STbp->buffer_bytes);
2019 						if (STps->drv_block >= 0)
2020 							STps->drv_block += 1;
2021 						if (st_int_ioctl(STp, MTBSR, 1))
2022 							return (-EIO);
2023 					}
2024 				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
2025 					if (STps->eof != ST_FM_HIT)
2026 						STps->eof = ST_FM_HIT;
2027 					else
2028 						STps->eof = ST_EOD_2;
2029 					if (STp->block_size == 0)
2030 						STbp->buffer_bytes = 0;
2031 					else
2032 						STbp->buffer_bytes =
2033 						    bytes - transfer * STp->block_size;
2034 					DEBC_printk(STp, "EOF detected (%d "
2035 						    "bytes read).\n",
2036 						    STbp->buffer_bytes);
2037 				} else if (cmdstatp->flags & SENSE_EOM) {
2038 					if (STps->eof == ST_FM)
2039 						STps->eof = ST_EOD_1;
2040 					else
2041 						STps->eof = ST_EOM_OK;
2042 					if (STp->block_size == 0)
2043 						STbp->buffer_bytes = bytes - transfer;
2044 					else
2045 						STbp->buffer_bytes =
2046 						    bytes - transfer * STp->block_size;
2047 
2048 					DEBC_printk(STp, "EOM detected (%d "
2049 						    "bytes read).\n",
2050 						    STbp->buffer_bytes);
2051 				}
2052 			}
2053 			/* end of EOF, EOM, ILI test */
2054 			else {	/* nonzero sense key */
2055 				DEBC_printk(STp, "Tape error while reading.\n");
2056 				STps->drv_block = (-1);
2057 				if (STps->eof == ST_FM &&
2058 				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
2059 					DEBC_printk(STp, "Zero returned for "
2060 						    "first BLANK CHECK "
2061 						    "after EOF.\n");
2062 					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
2063 				} else	/* Some other extended sense code */
2064 					retval = (-EIO);
2065 			}
2066 
2067 			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
2068 				STbp->buffer_bytes = 0;
2069 		}
2070 		/* End of extended sense test */
2071 		else {		/* Non-extended sense */
2072 			retval = STbp->syscall_result;
2073 		}
2074 
2075 	}
2076 	/* End of error handling */
2077 	else {			/* Read successful */
2078 		STbp->buffer_bytes = bytes;
2079 		if (STp->sili) /* In fixed block mode residual is always zero here */
2080 			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
2081 	}
2082 
2083 	if (STps->drv_block >= 0) {
2084 		if (STp->block_size == 0)
2085 			STps->drv_block++;
2086 		else
2087 			STps->drv_block += STbp->buffer_bytes / STp->block_size;
2088 	}
2089 	return retval;
2090 }
2091 
2092 
2093 /* Read command */
2094 static ssize_t
2095 st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
2096 {
2097 	ssize_t total;
2098 	ssize_t retval = 0;
2099 	ssize_t i, transfer;
2100 	int special, do_dio = 0;
2101 	struct st_request *SRpnt = NULL;
2102 	struct scsi_tape *STp = filp->private_data;
2103 	struct st_modedef *STm;
2104 	struct st_partstat *STps;
2105 	struct st_buffer *STbp = STp->buffer;
2106 
2107 	if (mutex_lock_interruptible(&STp->lock))
2108 		return -ERESTARTSYS;
2109 
2110 	retval = rw_checks(STp, filp, count);
2111 	if (retval || count == 0)
2112 		goto out;
2113 
2114 	STm = &(STp->modes[STp->current_mode]);
2115 	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
2116 		if (!STm->do_read_ahead) {
2117 			retval = (-EINVAL);	/* Read must be integral number of blocks */
2118 			goto out;
2119 		}
2120 		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
2121 	}
2122 
2123 	STps = &(STp->ps[STp->partition]);
2124 	if (STps->rw == ST_WRITING) {
2125 		retval = flush_buffer(STp, 0);
2126 		if (retval)
2127 			goto out;
2128 		STps->rw = ST_READING;
2129 	}
2130 	DEB(
2131 	if (debugging && STps->eof != ST_NOEOF)
2132 		st_printk(ST_DEB_MSG, STp,
2133 			  "EOF/EOM flag up (%d). Bytes %d\n",
2134 			  STps->eof, STbp->buffer_bytes);
2135 	) /* end DEB */
2136 
2137 	retval = setup_buffering(STp, buf, count, 1);
2138 	if (retval)
2139 		goto out;
2140 	do_dio = STbp->do_dio;
2141 
2142 	if (STbp->buffer_bytes == 0 &&
2143 	    STps->eof >= ST_EOD_1) {
2144 		if (STps->eof < ST_EOD) {
2145 			STps->eof += 1;
2146 			retval = 0;
2147 			goto out;
2148 		}
2149 		retval = (-EIO);	/* EOM or Blank Check */
2150 		goto out;
2151 	}
2152 
2153 	if (do_dio) {
2154 		/* Check the buffer writability before any tape movement. Don't alter
2155 		   buffer data. */
2156 		if (copy_from_user(&i, buf, 1) != 0 ||
2157 		    copy_to_user(buf, &i, 1) != 0 ||
2158 		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
2159 		    copy_to_user(buf + count - 1, &i, 1) != 0) {
2160 			retval = (-EFAULT);
2161 			goto out;
2162 		}
2163 	}
2164 
2165 	STps->rw = ST_READING;
2166 
2167 
2168 	/* Loop until enough data in buffer or a special condition found */
2169 	for (total = 0, special = 0; total < count && !special;) {
2170 
2171 		/* Get new data if the buffer is empty */
2172 		if (STbp->buffer_bytes == 0) {
2173 			special = read_tape(STp, count - total, &SRpnt);
2174 			if (special < 0) {	/* No need to continue read */
2175 				retval = special;
2176 				goto out;
2177 			}
2178 		}
2179 
2180 		/* Move the data from driver buffer to user buffer */
2181 		if (STbp->buffer_bytes > 0) {
2182 			DEB(
2183 			if (debugging && STps->eof != ST_NOEOF)
2184 				st_printk(ST_DEB_MSG, STp,
2185 					  "EOF up (%d). Left %d, needed %d.\n",
2186 					  STps->eof, STbp->buffer_bytes,
2187 					  (int)(count - total));
2188 			) /* end DEB */
2189 			transfer = STbp->buffer_bytes < count - total ?
2190 			    STbp->buffer_bytes : count - total;
2191 			if (!do_dio) {
2192 				i = from_buffer(STbp, buf, transfer);
2193 				if (i) {
2194 					retval = i;
2195 					goto out;
2196 				}
2197 			}
2198 			buf += transfer;
2199 			total += transfer;
2200 		}
2201 
2202 		if (STp->block_size == 0)
2203 			break;	/* Read only one variable length block */
2204 
2205 	}			/* for (total = 0, special = 0;
2206                                    total < count && !special; ) */
2207 
2208 	/* Change the eof state if no data from tape or buffer */
2209 	if (total == 0) {
2210 		if (STps->eof == ST_FM_HIT) {
2211 			STps->eof = ST_FM;
2212 			STps->drv_block = 0;
2213 			if (STps->drv_file >= 0)
2214 				STps->drv_file++;
2215 		} else if (STps->eof == ST_EOD_1) {
2216 			STps->eof = ST_EOD_2;
2217 			STps->drv_block = 0;
2218 			if (STps->drv_file >= 0)
2219 				STps->drv_file++;
2220 		} else if (STps->eof == ST_EOD_2)
2221 			STps->eof = ST_EOD;
2222 	} else if (STps->eof == ST_FM)
2223 		STps->eof = ST_NOEOF;
2224 	retval = total;
2225 
2226  out:
2227 	if (SRpnt != NULL) {
2228 		st_release_request(SRpnt);
2229 		SRpnt = NULL;
2230 	}
2231 	if (do_dio) {
2232 		release_buffering(STp, 1);
2233 		STbp->buffer_bytes = 0;
2234 	}
2235 	mutex_unlock(&STp->lock);
2236 
2237 	return retval;
2238 }
2239 
2240 
2241 
2242 DEB(
2243 /* Set the driver options */
2244 static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm)
2245 {
2246 	if (debugging) {
2247 		st_printk(KERN_INFO, STp,
2248 			  "Mode %d options: buffer writes: %d, "
2249 			  "async writes: %d, read ahead: %d\n",
2250 			  STp->current_mode, STm->do_buffer_writes,
2251 			  STm->do_async_writes, STm->do_read_ahead);
2252 		st_printk(KERN_INFO, STp,
2253 			  "    can bsr: %d, two FMs: %d, "
2254 			  "fast mteom: %d, auto lock: %d,\n",
2255 			  STp->can_bsr, STp->two_fm, STp->fast_mteom,
2256 			  STp->do_auto_lock);
2257 		st_printk(KERN_INFO, STp,
2258 			  "    defs for wr: %d, no block limits: %d, "
2259 			  "partitions: %d, s2 log: %d\n",
2260 			  STm->defaults_for_writes, STp->omit_blklims,
2261 			  STp->can_partitions, STp->scsi2_logical);
2262 		st_printk(KERN_INFO, STp,
2263 			  "    sysv: %d nowait: %d sili: %d "
2264 			  "nowait_filemark: %d\n",
2265 			  STm->sysv, STp->immediate, STp->sili,
2266 			  STp->immediate_filemark);
2267 		st_printk(KERN_INFO, STp, "    debugging: %d\n", debugging);
2268 	}
2269 }
2270 	)
2271 
2272 
2273 static int st_set_options(struct scsi_tape *STp, long options)
2274 {
2275 	int value;
2276 	long code;
2277 	struct st_modedef *STm;
2278 	struct cdev *cd0, *cd1;
2279 	struct device *d0, *d1;
2280 
2281 	STm = &(STp->modes[STp->current_mode]);
2282 	if (!STm->defined) {
2283 		cd0 = STm->cdevs[0];
2284 		cd1 = STm->cdevs[1];
2285 		d0  = STm->devs[0];
2286 		d1  = STm->devs[1];
2287 		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
2288 		STm->cdevs[0] = cd0;
2289 		STm->cdevs[1] = cd1;
2290 		STm->devs[0]  = d0;
2291 		STm->devs[1]  = d1;
2292 		modes_defined = 1;
2293 		DEBC_printk(STp, "Initialized mode %d definition from mode 0\n",
2294 			    STp->current_mode);
2295 	}
2296 
2297 	code = options & MT_ST_OPTIONS;
2298 	if (code == MT_ST_BOOLEANS) {
2299 		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
2300 		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
2301 		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
2302 		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
2303 		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
2304 		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
2305 		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
2306 		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
2307 		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
2308 		if ((STp->device)->scsi_level >= SCSI_2)
2309 			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
2310 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2311 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
2312 		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
2313 		STm->sysv = (options & MT_ST_SYSV) != 0;
2314 		STp->sili = (options & MT_ST_SILI) != 0;
2315 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2316 		     st_log_options(STp, STm); )
2317 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
2318 		value = (code == MT_ST_SETBOOLEANS);
2319 		if ((options & MT_ST_BUFFER_WRITES) != 0)
2320 			STm->do_buffer_writes = value;
2321 		if ((options & MT_ST_ASYNC_WRITES) != 0)
2322 			STm->do_async_writes = value;
2323 		if ((options & MT_ST_DEF_WRITES) != 0)
2324 			STm->defaults_for_writes = value;
2325 		if ((options & MT_ST_READ_AHEAD) != 0)
2326 			STm->do_read_ahead = value;
2327 		if ((options & MT_ST_TWO_FM) != 0)
2328 			STp->two_fm = value;
2329 		if ((options & MT_ST_FAST_MTEOM) != 0)
2330 			STp->fast_mteom = value;
2331 		if ((options & MT_ST_AUTO_LOCK) != 0)
2332 			STp->do_auto_lock = value;
2333 		if ((options & MT_ST_CAN_BSR) != 0)
2334 			STp->can_bsr = value;
2335 		if ((options & MT_ST_NO_BLKLIMS) != 0)
2336 			STp->omit_blklims = value;
2337 		if ((STp->device)->scsi_level >= SCSI_2 &&
2338 		    (options & MT_ST_CAN_PARTITIONS) != 0)
2339 			STp->can_partitions = value;
2340 		if ((options & MT_ST_SCSI2LOGICAL) != 0)
2341 			STp->scsi2_logical = value;
2342 		if ((options & MT_ST_NOWAIT) != 0)
2343 			STp->immediate = value;
2344 		if ((options & MT_ST_NOWAIT_EOF) != 0)
2345 			STp->immediate_filemark = value;
2346 		if ((options & MT_ST_SYSV) != 0)
2347 			STm->sysv = value;
2348 		if ((options & MT_ST_SILI) != 0)
2349 			STp->sili = value;
2350 		DEB(
2351 		if ((options & MT_ST_DEBUGGING) != 0)
2352 			debugging = value;
2353 			st_log_options(STp, STm); )
2354 	} else if (code == MT_ST_WRITE_THRESHOLD) {
2355 		/* Retained for compatibility */
2356 	} else if (code == MT_ST_DEF_BLKSIZE) {
2357 		value = (options & ~MT_ST_OPTIONS);
2358 		if (value == ~MT_ST_OPTIONS) {
2359 			STm->default_blksize = (-1);
2360 			DEBC_printk(STp, "Default block size disabled.\n");
2361 		} else {
2362 			STm->default_blksize = value;
2363 			DEBC_printk(STp,"Default block size set to "
2364 				    "%d bytes.\n", STm->default_blksize);
2365 			if (STp->ready == ST_READY) {
2366 				STp->blksize_changed = 0;
2367 				set_mode_densblk(STp, STm);
2368 			}
2369 		}
2370 	} else if (code == MT_ST_TIMEOUTS) {
2371 		value = (options & ~MT_ST_OPTIONS);
2372 		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
2373 			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
2374 			DEBC_printk(STp, "Long timeout set to %d seconds.\n",
2375 				    (value & ~MT_ST_SET_LONG_TIMEOUT));
2376 		} else {
2377 			blk_queue_rq_timeout(STp->device->request_queue,
2378 					     value * HZ);
2379 			DEBC_printk(STp, "Normal timeout set to %d seconds.\n",
2380 				    value);
2381 		}
2382 	} else if (code == MT_ST_SET_CLN) {
2383 		value = (options & ~MT_ST_OPTIONS) & 0xff;
2384 		if (value != 0 &&
2385 			(value < EXTENDED_SENSE_START ||
2386 				value >= SCSI_SENSE_BUFFERSIZE))
2387 			return (-EINVAL);
2388 		STp->cln_mode = value;
2389 		STp->cln_sense_mask = (options >> 8) & 0xff;
2390 		STp->cln_sense_value = (options >> 16) & 0xff;
2391 		st_printk(KERN_INFO, STp,
2392 			  "Cleaning request mode %d, mask %02x, value %02x\n",
2393 			  value, STp->cln_sense_mask, STp->cln_sense_value);
2394 	} else if (code == MT_ST_DEF_OPTIONS) {
2395 		code = (options & ~MT_ST_CLEAR_DEFAULT);
2396 		value = (options & MT_ST_CLEAR_DEFAULT);
2397 		if (code == MT_ST_DEF_DENSITY) {
2398 			if (value == MT_ST_CLEAR_DEFAULT) {
2399 				STm->default_density = (-1);
2400 				DEBC_printk(STp,
2401 					    "Density default disabled.\n");
2402 			} else {
2403 				STm->default_density = value & 0xff;
2404 				DEBC_printk(STp, "Density default set to %x\n",
2405 					    STm->default_density);
2406 				if (STp->ready == ST_READY) {
2407 					STp->density_changed = 0;
2408 					set_mode_densblk(STp, STm);
2409 				}
2410 			}
2411 		} else if (code == MT_ST_DEF_DRVBUFFER) {
2412 			if (value == MT_ST_CLEAR_DEFAULT) {
2413 				STp->default_drvbuffer = 0xff;
2414 				DEBC_printk(STp,
2415 					    "Drive buffer default disabled.\n");
2416 			} else {
2417 				STp->default_drvbuffer = value & 7;
2418 				DEBC_printk(STp,
2419 					    "Drive buffer default set to %x\n",
2420 					    STp->default_drvbuffer);
2421 				if (STp->ready == ST_READY)
2422 					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
2423 			}
2424 		} else if (code == MT_ST_DEF_COMPRESSION) {
2425 			if (value == MT_ST_CLEAR_DEFAULT) {
2426 				STm->default_compression = ST_DONT_TOUCH;
2427 				DEBC_printk(STp,
2428 					    "Compression default disabled.\n");
2429 			} else {
2430 				if ((value & 0xff00) != 0) {
2431 					STp->c_algo = (value & 0xff00) >> 8;
2432 					DEBC_printk(STp, "Compression "
2433 						    "algorithm set to 0x%x.\n",
2434 						    STp->c_algo);
2435 				}
2436 				if ((value & 0xff) != 0xff) {
2437 					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
2438 					DEBC_printk(STp, "Compression default "
2439 						    "set to %x\n",
2440 						    (value & 1));
2441 					if (STp->ready == ST_READY) {
2442 						STp->compression_changed = 0;
2443 						st_compression(STp, (STm->default_compression == ST_YES));
2444 					}
2445 				}
2446 			}
2447 		}
2448 	} else
2449 		return (-EIO);
2450 
2451 	return 0;
2452 }
2453 
2454 #define MODE_HEADER_LENGTH  4
2455 
2456 /* Mode header and page byte offsets */
2457 #define MH_OFF_DATA_LENGTH     0
2458 #define MH_OFF_MEDIUM_TYPE     1
2459 #define MH_OFF_DEV_SPECIFIC    2
2460 #define MH_OFF_BDESCS_LENGTH   3
2461 #define MP_OFF_PAGE_NBR        0
2462 #define MP_OFF_PAGE_LENGTH     1
2463 
2464 /* Mode header and page bit masks */
2465 #define MH_BIT_WP              0x80
2466 #define MP_MSK_PAGE_NBR        0x3f
2467 
2468 /* Don't return block descriptors */
2469 #define MODE_SENSE_OMIT_BDESCS 0x08
2470 
2471 #define MODE_SELECT_PAGE_FORMAT 0x10
2472 
2473 /* Read a mode page into the tape buffer. The block descriptors are included
2474    if incl_block_descs is true. The page control is ored to the page number
2475    parameter, if necessary. */
2476 static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
2477 {
2478 	unsigned char cmd[MAX_COMMAND_SIZE];
2479 	struct st_request *SRpnt;
2480 
2481 	memset(cmd, 0, MAX_COMMAND_SIZE);
2482 	cmd[0] = MODE_SENSE;
2483 	if (omit_block_descs)
2484 		cmd[1] = MODE_SENSE_OMIT_BDESCS;
2485 	cmd[2] = page;
2486 	cmd[4] = 255;
2487 
2488 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
2489 			   STp->device->request_queue->rq_timeout, 0, 1);
2490 	if (SRpnt == NULL)
2491 		return (STp->buffer)->syscall_result;
2492 
2493 	st_release_request(SRpnt);
2494 
2495 	return STp->buffer->syscall_result;
2496 }
2497 
2498 
2499 /* Send the mode page in the tape buffer to the drive. Assumes that the mode data
2500    in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
2501 static int write_mode_page(struct scsi_tape *STp, int page, int slow)
2502 {
2503 	int pgo;
2504 	unsigned char cmd[MAX_COMMAND_SIZE];
2505 	struct st_request *SRpnt;
2506 	int timeout;
2507 
2508 	memset(cmd, 0, MAX_COMMAND_SIZE);
2509 	cmd[0] = MODE_SELECT;
2510 	cmd[1] = MODE_SELECT_PAGE_FORMAT;
2511 	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
2512 	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;
2513 
2514 	/* Clear reserved fields */
2515 	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
2516 	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
2517 	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
2518 	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;
2519 
2520 	timeout = slow ?
2521 		STp->long_timeout : STp->device->request_queue->rq_timeout;
2522 	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
2523 			   timeout, 0, 1);
2524 	if (SRpnt == NULL)
2525 		return (STp->buffer)->syscall_result;
2526 
2527 	st_release_request(SRpnt);
2528 
2529 	return STp->buffer->syscall_result;
2530 }
2531 
2532 
2533 #define COMPRESSION_PAGE        0x0f
2534 #define COMPRESSION_PAGE_LENGTH 16
2535 
2536 #define CP_OFF_DCE_DCC          2
2537 #define CP_OFF_C_ALGO           7
2538 
2539 #define DCE_MASK  0x80
2540 #define DCC_MASK  0x40
2541 #define RED_MASK  0x60
2542 
2543 
2544 /* Control the compression with mode page 15. Algorithm not changed if zero.
2545 
2546    The block descriptors are read and written because Sony SDT-7000 does not
2547    work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
2548    Including block descriptors should not cause any harm to other drives. */
2549 
2550 static int st_compression(struct scsi_tape * STp, int state)
2551 {
2552 	int retval;
2553 	int mpoffs;  /* Offset to mode page start */
2554 	unsigned char *b_data = (STp->buffer)->b_data;
2555 
2556 	if (STp->ready != ST_READY)
2557 		return (-EIO);
2558 
2559 	/* Read the current page contents */
2560 	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
2561 	if (retval) {
2562 		DEBC_printk(STp, "Compression mode page not supported.\n");
2563 		return (-EIO);
2564 	}
2565 
2566 	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
2567 	DEBC_printk(STp, "Compression state is %d.\n",
2568 		    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0));
2569 
2570 	/* Check if compression can be changed */
2571 	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
2572 		DEBC_printk(STp, "Compression not supported.\n");
2573 		return (-EIO);
2574 	}
2575 
2576 	/* Do the change */
2577 	if (state) {
2578 		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
2579 		if (STp->c_algo != 0)
2580 			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
2581 	}
2582 	else {
2583 		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
2584 		if (STp->c_algo != 0)
2585 			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
2586 	}
2587 
2588 	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
2589 	if (retval) {
2590 		DEBC_printk(STp, "Compression change failed.\n");
2591 		return (-EIO);
2592 	}
2593 	DEBC_printk(STp, "Compression state changed to %d.\n", state);
2594 
2595 	STp->compression_changed = 1;
2596 	return 0;
2597 }
2598 
2599 
2600 /* Process the load and unload commands (does unload if the load code is zero) */
2601 static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
2602 {
2603 	int retval = (-EIO), timeout;
2604 	unsigned char cmd[MAX_COMMAND_SIZE];
2605 	struct st_partstat *STps;
2606 	struct st_request *SRpnt;
2607 
2608 	if (STp->ready != ST_READY && !load_code) {
2609 		if (STp->ready == ST_NO_TAPE)
2610 			return (-ENOMEDIUM);
2611 		else
2612 			return (-EIO);
2613 	}
2614 
2615 	memset(cmd, 0, MAX_COMMAND_SIZE);
2616 	cmd[0] = START_STOP;
2617 	if (load_code)
2618 		cmd[4] |= 1;
2619 	/*
2620 	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
2621 	 */
2622 	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
2623 	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
2624 		DEBC_printk(STp, " Enhanced %sload slot %2d.\n",
2625 			    (cmd[4]) ? "" : "un",
2626 			    load_code - MT_ST_HPLOADER_OFFSET);
2627 		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
2628 	}
2629 	if (STp->immediate) {
2630 		cmd[1] = 1;	/* Don't wait for completion */
2631 		timeout = STp->device->request_queue->rq_timeout;
2632 	}
2633 	else
2634 		timeout = STp->long_timeout;
2635 
2636 	DEBC(
2637 		if (!load_code)
2638 			st_printk(ST_DEB_MSG, STp, "Unloading tape.\n");
2639 		else
2640 			st_printk(ST_DEB_MSG, STp, "Loading tape.\n");
2641 		);
2642 
2643 	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
2644 			   timeout, MAX_RETRIES, 1);
2645 	if (!SRpnt)
2646 		return (STp->buffer)->syscall_result;
2647 
2648 	retval = (STp->buffer)->syscall_result;
2649 	st_release_request(SRpnt);
2650 
2651 	if (!retval) {	/* SCSI command successful */
2652 
2653 		if (!load_code) {
2654 			STp->rew_at_close = 0;
2655 			STp->ready = ST_NO_TAPE;
2656 		}
2657 		else {
2658 			STp->rew_at_close = STp->autorew_dev;
2659 			retval = check_tape(STp, filp);
2660 			if (retval > 0)
2661 				retval = 0;
2662 		}
2663 	}
2664 	else {
2665 		STps = &(STp->ps[STp->partition]);
2666 		STps->drv_file = STps->drv_block = (-1);
2667 	}
2668 
2669 	return retval;
2670 }
2671 
2672 #if DEBUG
2673 #define ST_DEB_FORWARD  0
2674 #define ST_DEB_BACKWARD 1
2675 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd)
2676 {
2677 	s32 sc;
2678 
2679 	if (!debugging)
2680 		return;
2681 
2682 	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
2683 	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
2684 	if (direction)
2685 		sc = -sc;
2686 	st_printk(ST_DEB_MSG, STp, "Spacing tape %s over %d %s.\n",
2687 		  direction ? "backward" : "forward", sc, units);
2688 }
2689 #else
2690 #define ST_DEB_FORWARD  0
2691 #define ST_DEB_BACKWARD 1
2692 static void deb_space_print(struct scsi_tape *STp, int direction, char *units, unsigned char *cmd) {}
2693 #endif
2694 
2695 
2696 /* Internal ioctl function */
2697 static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
2698 {
2699 	int timeout;
2700 	long ltmp;
2701 	int ioctl_result;
2702 	int chg_eof = 1;
2703 	unsigned char cmd[MAX_COMMAND_SIZE];
2704 	struct st_request *SRpnt;
2705 	struct st_partstat *STps;
2706 	int fileno, blkno, at_sm, undone;
2707 	int datalen = 0, direction = DMA_NONE;
2708 
2709 	WARN_ON(STp->buffer->do_dio != 0);
2710 	if (STp->ready != ST_READY) {
2711 		if (STp->ready == ST_NO_TAPE)
2712 			return (-ENOMEDIUM);
2713 		else
2714 			return (-EIO);
2715 	}
2716 	timeout = STp->long_timeout;
2717 	STps = &(STp->ps[STp->partition]);
2718 	fileno = STps->drv_file;
2719 	blkno = STps->drv_block;
2720 	at_sm = STps->at_sm;
2721 
2722 	memset(cmd, 0, MAX_COMMAND_SIZE);
2723 	switch (cmd_in) {
2724 	case MTFSFM:
2725 		chg_eof = 0;	/* Changed from the FSF after this */
2726 	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 	case MTBSF:
2741 		cmd[0] = SPACE;
2742 		cmd[1] = 0x01;	/* Space FileMarks */
2743 		ltmp = (-arg);
2744 		cmd[2] = (ltmp >> 16);
2745 		cmd[3] = (ltmp >> 8);
2746 		cmd[4] = ltmp;
2747 		deb_space_print(STp, ST_DEB_BACKWARD, "filemarks", cmd);
2748 		if (fileno >= 0)
2749 			fileno -= arg;
2750 		blkno = (-1);	/* We can't know the block number */
2751 		at_sm &= (arg == 0);
2752 		break;
2753 	case MTFSR:
2754 		cmd[0] = SPACE;
2755 		cmd[1] = 0x00;	/* Space Blocks */
2756 		cmd[2] = (arg >> 16);
2757 		cmd[3] = (arg >> 8);
2758 		cmd[4] = arg;
2759 		deb_space_print(STp, ST_DEB_FORWARD, "blocks", cmd);
2760 		if (blkno >= 0)
2761 			blkno += arg;
2762 		at_sm &= (arg == 0);
2763 		break;
2764 	case MTBSR:
2765 		cmd[0] = SPACE;
2766 		cmd[1] = 0x00;	/* Space Blocks */
2767 		ltmp = (-arg);
2768 		cmd[2] = (ltmp >> 16);
2769 		cmd[3] = (ltmp >> 8);
2770 		cmd[4] = ltmp;
2771 		deb_space_print(STp, ST_DEB_BACKWARD, "blocks", cmd);
2772 		if (blkno >= 0)
2773 			blkno -= arg;
2774 		at_sm &= (arg == 0);
2775 		break;
2776 	case MTFSS:
2777 		cmd[0] = SPACE;
2778 		cmd[1] = 0x04;	/* Space Setmarks */
2779 		cmd[2] = (arg >> 16);
2780 		cmd[3] = (arg >> 8);
2781 		cmd[4] = arg;
2782 		deb_space_print(STp, ST_DEB_FORWARD, "setmarks", cmd);
2783 		if (arg != 0) {
2784 			blkno = fileno = (-1);
2785 			at_sm = 1;
2786 		}
2787 		break;
2788 	case MTBSS:
2789 		cmd[0] = SPACE;
2790 		cmd[1] = 0x04;	/* Space Setmarks */
2791 		ltmp = (-arg);
2792 		cmd[2] = (ltmp >> 16);
2793 		cmd[3] = (ltmp >> 8);
2794 		cmd[4] = ltmp;
2795 		deb_space_print(STp, ST_DEB_BACKWARD, "setmarks", cmd);
2796 		if (arg != 0) {
2797 			blkno = fileno = (-1);
2798 			at_sm = 1;
2799 		}
2800 		break;
2801 	case MTWEOF:
2802 	case MTWEOFI:
2803 	case MTWSM:
2804 		if (STp->write_prot)
2805 			return (-EACCES);
2806 		cmd[0] = WRITE_FILEMARKS;
2807 		if (cmd_in == MTWSM)
2808 			cmd[1] = 2;
2809 		if (cmd_in == MTWEOFI ||
2810 		    (cmd_in == MTWEOF && STp->immediate_filemark))
2811 			cmd[1] |= 1;
2812 		cmd[2] = (arg >> 16);
2813 		cmd[3] = (arg >> 8);
2814 		cmd[4] = arg;
2815 		timeout = STp->device->request_queue->rq_timeout;
2816 		DEBC(
2817 			if (cmd_in != MTWSM)
2818 				st_printk(ST_DEB_MSG, STp,
2819 					  "Writing %d filemarks.\n",
2820 					  cmd[2] * 65536 +
2821 					  cmd[3] * 256 +
2822 					  cmd[4]);
2823 			else
2824 				st_printk(ST_DEB_MSG, STp,
2825 					  "Writing %d setmarks.\n",
2826 					  cmd[2] * 65536 +
2827 					  cmd[3] * 256 +
2828 					  cmd[4]);
2829 		)
2830 		if (fileno >= 0)
2831 			fileno += arg;
2832 		blkno = 0;
2833 		at_sm = (cmd_in == MTWSM);
2834 		break;
2835 	case MTREW:
2836 		cmd[0] = REZERO_UNIT;
2837 		if (STp->immediate) {
2838 			cmd[1] = 1;	/* Don't wait for completion */
2839 			timeout = STp->device->request_queue->rq_timeout;
2840 		}
2841 		DEBC_printk(STp, "Rewinding tape.\n");
2842 		fileno = blkno = at_sm = 0;
2843 		break;
2844 	case MTNOP:
2845 		DEBC_printk(STp, "No op on tape.\n");
2846 		return 0;	/* Should do something ? */
2847 		break;
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 	int i, cmd_nr, cmd_type, bt;
3504 	int retval = 0;
3505 	unsigned int blk;
3506 	struct scsi_tape *STp = file->private_data;
3507 	struct st_modedef *STm;
3508 	struct st_partstat *STps;
3509 	void __user *p = (void __user *)arg;
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 		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
3802 		if (i) {
3803 			retval = (-EFAULT);
3804 			goto out;
3805 		}
3806 
3807 		STp->recover_reg = 0;		/* Clear after read */
3808 		retval = 0;
3809 		goto out;
3810 	}			/* End of MTIOCGET */
3811 	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
3812 		struct mtpos mt_pos;
3813 		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
3814 			 retval = (-EINVAL);
3815 			 goto out;
3816 		}
3817 		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
3818 			retval = i;
3819 			goto out;
3820 		}
3821 		mt_pos.mt_blkno = blk;
3822 		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
3823 		if (i)
3824 			retval = (-EFAULT);
3825 		goto out;
3826 	}
3827 	mutex_unlock(&STp->lock);
3828 	switch (cmd_in) {
3829 		case SCSI_IOCTL_GET_IDLUN:
3830 		case SCSI_IOCTL_GET_BUS_NUMBER:
3831 			break;
3832 		default:
3833 			if ((cmd_in == SG_IO ||
3834 			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
3835 			     cmd_in == CDROM_SEND_PACKET) &&
3836 			    !capable(CAP_SYS_RAWIO))
3837 				i = -EPERM;
3838 			else
3839 				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
3840 						   file->f_mode, cmd_in, p);
3841 			if (i != -ENOTTY)
3842 				return i;
3843 			break;
3844 	}
3845 	retval = scsi_ioctl(STp->device, cmd_in, p);
3846 	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
3847 		STp->rew_at_close = 0;
3848 		STp->ready = ST_NO_TAPE;
3849 	}
3850 	return retval;
3851 
3852  out:
3853 	mutex_unlock(&STp->lock);
3854 	return retval;
3855 }
3856 
3857 #ifdef CONFIG_COMPAT
3858 static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3859 {
3860 	struct scsi_tape *STp = file->private_data;
3861 	struct scsi_device *sdev = STp->device;
3862 	int ret = -ENOIOCTLCMD;
3863 	if (sdev->host->hostt->compat_ioctl) {
3864 
3865 		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);
3866 
3867 	}
3868 	return ret;
3869 }
3870 #endif
3871 
3872 
3873 
3874 /* Try to allocate a new tape buffer. Calling function must not hold
3875    dev_arr_lock. */
3876 static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
3877 {
3878 	struct st_buffer *tb;
3879 
3880 	tb = kzalloc(sizeof(struct st_buffer), GFP_ATOMIC);
3881 	if (!tb) {
3882 		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
3883 		return NULL;
3884 	}
3885 	tb->frp_segs = 0;
3886 	tb->use_sg = max_sg;
3887 	tb->dma = need_dma;
3888 	tb->buffer_size = 0;
3889 
3890 	tb->reserved_pages = kzalloc(max_sg * sizeof(struct page *),
3891 				     GFP_ATOMIC);
3892 	if (!tb->reserved_pages) {
3893 		kfree(tb);
3894 		return NULL;
3895 	}
3896 
3897 	return tb;
3898 }
3899 
3900 
3901 /* Try to allocate enough space in the tape buffer */
3902 #define ST_MAX_ORDER 6
3903 
3904 static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
3905 {
3906 	int segs, max_segs, b_size, order, got;
3907 	gfp_t priority;
3908 
3909 	if (new_size <= STbuffer->buffer_size)
3910 		return 1;
3911 
3912 	if (STbuffer->buffer_size <= PAGE_SIZE)
3913 		normalize_buffer(STbuffer);  /* Avoid extra segment */
3914 
3915 	max_segs = STbuffer->use_sg;
3916 
3917 	priority = GFP_KERNEL | __GFP_NOWARN;
3918 	if (need_dma)
3919 		priority |= GFP_DMA;
3920 
3921 	if (STbuffer->cleared)
3922 		priority |= __GFP_ZERO;
3923 
3924 	if (STbuffer->frp_segs) {
3925 		order = STbuffer->reserved_page_order;
3926 		b_size = PAGE_SIZE << order;
3927 	} else {
3928 		for (b_size = PAGE_SIZE, order = 0;
3929 		     order < ST_MAX_ORDER &&
3930 			     max_segs * (PAGE_SIZE << order) < new_size;
3931 		     order++, b_size *= 2)
3932 			;  /* empty */
3933 		STbuffer->reserved_page_order = order;
3934 	}
3935 	if (max_segs * (PAGE_SIZE << order) < new_size) {
3936 		if (order == ST_MAX_ORDER)
3937 			return 0;
3938 		normalize_buffer(STbuffer);
3939 		return enlarge_buffer(STbuffer, new_size, need_dma);
3940 	}
3941 
3942 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
3943 	     segs < max_segs && got < new_size;) {
3944 		struct page *page;
3945 
3946 		page = alloc_pages(priority, order);
3947 		if (!page) {
3948 			DEB(STbuffer->buffer_size = got);
3949 			normalize_buffer(STbuffer);
3950 			return 0;
3951 		}
3952 
3953 		STbuffer->frp_segs += 1;
3954 		got += b_size;
3955 		STbuffer->buffer_size = got;
3956 		STbuffer->reserved_pages[segs] = page;
3957 		segs++;
3958 	}
3959 	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
3960 
3961 	return 1;
3962 }
3963 
3964 
3965 /* Make sure that no data from previous user is in the internal buffer */
3966 static void clear_buffer(struct st_buffer * st_bp)
3967 {
3968 	int i;
3969 
3970 	for (i=0; i < st_bp->frp_segs; i++)
3971 		memset(page_address(st_bp->reserved_pages[i]), 0,
3972 		       PAGE_SIZE << st_bp->reserved_page_order);
3973 	st_bp->cleared = 1;
3974 }
3975 
3976 
3977 /* Release the extra buffer */
3978 static void normalize_buffer(struct st_buffer * STbuffer)
3979 {
3980 	int i, order = STbuffer->reserved_page_order;
3981 
3982 	for (i = 0; i < STbuffer->frp_segs; i++) {
3983 		__free_pages(STbuffer->reserved_pages[i], order);
3984 		STbuffer->buffer_size -= (PAGE_SIZE << order);
3985 	}
3986 	STbuffer->frp_segs = 0;
3987 	STbuffer->sg_segs = 0;
3988 	STbuffer->reserved_page_order = 0;
3989 	STbuffer->map_data.offset = 0;
3990 }
3991 
3992 
3993 /* Move data from the user buffer to the tape buffer. Returns zero (success) or
3994    negative error code. */
3995 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
3996 {
3997 	int i, cnt, res, offset;
3998 	int length = PAGE_SIZE << st_bp->reserved_page_order;
3999 
4000 	for (i = 0, offset = st_bp->buffer_bytes;
4001 	     i < st_bp->frp_segs && offset >= length; i++)
4002 		offset -= length;
4003 	if (i == st_bp->frp_segs) {	/* Should never happen */
4004 		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
4005 		return (-EIO);
4006 	}
4007 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4008 		struct page *page = st_bp->reserved_pages[i];
4009 		cnt = length - offset < do_count ? length - offset : do_count;
4010 		res = copy_from_user(page_address(page) + offset, ubp, cnt);
4011 		if (res)
4012 			return (-EFAULT);
4013 		do_count -= cnt;
4014 		st_bp->buffer_bytes += cnt;
4015 		ubp += cnt;
4016 		offset = 0;
4017 	}
4018 	if (do_count) /* Should never happen */
4019 		return (-EIO);
4020 
4021 	return 0;
4022 }
4023 
4024 
4025 /* Move data from the tape buffer to the user buffer. Returns zero (success) or
4026    negative error code. */
4027 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
4028 {
4029 	int i, cnt, res, offset;
4030 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4031 
4032 	for (i = 0, offset = st_bp->read_pointer;
4033 	     i < st_bp->frp_segs && offset >= length; i++)
4034 		offset -= length;
4035 	if (i == st_bp->frp_segs) {	/* Should never happen */
4036 		printk(KERN_WARNING "st: from_buffer offset overflow.\n");
4037 		return (-EIO);
4038 	}
4039 	for (; i < st_bp->frp_segs && do_count > 0; i++) {
4040 		struct page *page = st_bp->reserved_pages[i];
4041 		cnt = length - offset < do_count ? length - offset : do_count;
4042 		res = copy_to_user(ubp, page_address(page) + offset, cnt);
4043 		if (res)
4044 			return (-EFAULT);
4045 		do_count -= cnt;
4046 		st_bp->buffer_bytes -= cnt;
4047 		st_bp->read_pointer += cnt;
4048 		ubp += cnt;
4049 		offset = 0;
4050 	}
4051 	if (do_count) /* Should never happen */
4052 		return (-EIO);
4053 
4054 	return 0;
4055 }
4056 
4057 
4058 /* Move data towards start of buffer */
4059 static void move_buffer_data(struct st_buffer * st_bp, int offset)
4060 {
4061 	int src_seg, dst_seg, src_offset = 0, dst_offset;
4062 	int count, total;
4063 	int length = PAGE_SIZE << st_bp->reserved_page_order;
4064 
4065 	if (offset == 0)
4066 		return;
4067 
4068 	total=st_bp->buffer_bytes - offset;
4069 	for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
4070 		src_offset = offset;
4071 		if (src_offset < length)
4072 			break;
4073 		offset -= length;
4074 	}
4075 
4076 	st_bp->buffer_bytes = st_bp->read_pointer = total;
4077 	for (dst_seg=dst_offset=0; total > 0; ) {
4078 		struct page *dpage = st_bp->reserved_pages[dst_seg];
4079 		struct page *spage = st_bp->reserved_pages[src_seg];
4080 
4081 		count = min(length - dst_offset, length - src_offset);
4082 		memmove(page_address(dpage) + dst_offset,
4083 			page_address(spage) + src_offset, count);
4084 		src_offset += count;
4085 		if (src_offset >= length) {
4086 			src_seg++;
4087 			src_offset = 0;
4088 		}
4089 		dst_offset += count;
4090 		if (dst_offset >= length) {
4091 			dst_seg++;
4092 			dst_offset = 0;
4093 		}
4094 		total -= count;
4095 	}
4096 }
4097 
4098 /* Validate the options from command line or module parameters */
4099 static void validate_options(void)
4100 {
4101 	if (buffer_kbs > 0)
4102 		st_fixed_buffer_size = buffer_kbs * ST_KILOBYTE;
4103 	if (max_sg_segs >= ST_FIRST_SG)
4104 		st_max_sg_segs = max_sg_segs;
4105 }
4106 
4107 #ifndef MODULE
4108 /* Set the boot options. Syntax is defined in Documenation/scsi/st.txt.
4109  */
4110 static int __init st_setup(char *str)
4111 {
4112 	int i, len, ints[5];
4113 	char *stp;
4114 
4115 	stp = get_options(str, ARRAY_SIZE(ints), ints);
4116 
4117 	if (ints[0] > 0) {
4118 		for (i = 0; i < ints[0] && i < ARRAY_SIZE(parms); i++)
4119 			if (parms[i].val)
4120 				*parms[i].val = ints[i + 1];
4121 	} else {
4122 		while (stp != NULL) {
4123 			for (i = 0; i < ARRAY_SIZE(parms); i++) {
4124 				len = strlen(parms[i].name);
4125 				if (!strncmp(stp, parms[i].name, len) &&
4126 				    (*(stp + len) == ':' || *(stp + len) == '=')) {
4127 					if (parms[i].val)
4128 						*parms[i].val =
4129 							simple_strtoul(stp + len + 1, NULL, 0);
4130 					else
4131 						printk(KERN_WARNING "st: Obsolete parameter %s\n",
4132 						       parms[i].name);
4133 					break;
4134 				}
4135 			}
4136 			if (i >= ARRAY_SIZE(parms))
4137 				 printk(KERN_WARNING "st: invalid parameter in '%s'\n",
4138 					stp);
4139 			stp = strchr(stp, ',');
4140 			if (stp)
4141 				stp++;
4142 		}
4143 	}
4144 
4145 	validate_options();
4146 
4147 	return 1;
4148 }
4149 
4150 __setup("st=", st_setup);
4151 
4152 #endif
4153 
4154 static const struct file_operations st_fops =
4155 {
4156 	.owner =	THIS_MODULE,
4157 	.read =		st_read,
4158 	.write =	st_write,
4159 	.unlocked_ioctl = st_ioctl,
4160 #ifdef CONFIG_COMPAT
4161 	.compat_ioctl = st_compat_ioctl,
4162 #endif
4163 	.open =		st_open,
4164 	.flush =	st_flush,
4165 	.release =	st_release,
4166 	.llseek =	noop_llseek,
4167 };
4168 
4169 static int create_one_cdev(struct scsi_tape *tape, int mode, int rew)
4170 {
4171 	int i, error;
4172 	dev_t cdev_devno;
4173 	struct cdev *cdev;
4174 	struct device *dev;
4175 	struct st_modedef *STm = &(tape->modes[mode]);
4176 	char name[10];
4177 	int dev_num = tape->index;
4178 
4179 	cdev_devno = MKDEV(SCSI_TAPE_MAJOR, TAPE_MINOR(dev_num, mode, rew));
4180 
4181 	cdev = cdev_alloc();
4182 	if (!cdev) {
4183 		pr_err("st%d: out of memory. Device not attached.\n", dev_num);
4184 		error = -ENOMEM;
4185 		goto out;
4186 	}
4187 	cdev->owner = THIS_MODULE;
4188 	cdev->ops = &st_fops;
4189 	STm->cdevs[rew] = cdev;
4190 
4191 	error = cdev_add(cdev, cdev_devno, 1);
4192 	if (error) {
4193 		pr_err("st%d: Can't add %s-rewind mode %d\n", dev_num,
4194 		       rew ? "non" : "auto", mode);
4195 		pr_err("st%d: Device not attached.\n", dev_num);
4196 		goto out_free;
4197 	}
4198 
4199 	i = mode << (4 - ST_NBR_MODE_BITS);
4200 	snprintf(name, 10, "%s%s%s", rew ? "n" : "",
4201 		 tape->disk->disk_name, st_formats[i]);
4202 
4203 	dev = device_create(&st_sysfs_class, &tape->device->sdev_gendev,
4204 			    cdev_devno, &tape->modes[mode], "%s", name);
4205 	if (IS_ERR(dev)) {
4206 		pr_err("st%d: device_create failed\n", dev_num);
4207 		error = PTR_ERR(dev);
4208 		goto out_free;
4209 	}
4210 
4211 	STm->devs[rew] = dev;
4212 
4213 	return 0;
4214 out_free:
4215 	cdev_del(STm->cdevs[rew]);
4216 out:
4217 	STm->cdevs[rew] = NULL;
4218 	STm->devs[rew] = NULL;
4219 	return error;
4220 }
4221 
4222 static int create_cdevs(struct scsi_tape *tape)
4223 {
4224 	int mode, error;
4225 	for (mode = 0; mode < ST_NBR_MODES; ++mode) {
4226 		error = create_one_cdev(tape, mode, 0);
4227 		if (error)
4228 			return error;
4229 		error = create_one_cdev(tape, mode, 1);
4230 		if (error)
4231 			return error;
4232 	}
4233 
4234 	return sysfs_create_link(&tape->device->sdev_gendev.kobj,
4235 				 &tape->modes[0].devs[0]->kobj, "tape");
4236 }
4237 
4238 static void remove_cdevs(struct scsi_tape *tape)
4239 {
4240 	int mode, rew;
4241 	sysfs_remove_link(&tape->device->sdev_gendev.kobj, "tape");
4242 	for (mode = 0; mode < ST_NBR_MODES; mode++) {
4243 		struct st_modedef *STm = &(tape->modes[mode]);
4244 		for (rew = 0; rew < 2; rew++) {
4245 			if (STm->cdevs[rew])
4246 				cdev_del(STm->cdevs[rew]);
4247 			if (STm->devs[rew])
4248 				device_unregister(STm->devs[rew]);
4249 		}
4250 	}
4251 }
4252 
4253 static int st_probe(struct device *dev)
4254 {
4255 	struct scsi_device *SDp = to_scsi_device(dev);
4256 	struct gendisk *disk = NULL;
4257 	struct scsi_tape *tpnt = NULL;
4258 	struct st_modedef *STm;
4259 	struct st_partstat *STps;
4260 	struct st_buffer *buffer;
4261 	int i, error;
4262 	char *stp;
4263 
4264 	if (SDp->type != TYPE_TAPE)
4265 		return -ENODEV;
4266 	if ((stp = st_incompatible(SDp))) {
4267 		sdev_printk(KERN_INFO, SDp, "Found incompatible tape\n");
4268 		sdev_printk(KERN_INFO, SDp,
4269 			    "st: The suggested driver is %s.\n", stp);
4270 		return -ENODEV;
4271 	}
4272 
4273 	scsi_autopm_get_device(SDp);
4274 	i = queue_max_segments(SDp->request_queue);
4275 	if (st_max_sg_segs < i)
4276 		i = st_max_sg_segs;
4277 	buffer = new_tape_buffer((SDp->host)->unchecked_isa_dma, i);
4278 	if (buffer == NULL) {
4279 		sdev_printk(KERN_ERR, SDp,
4280 			    "st: Can't allocate new tape buffer. "
4281 			    "Device not attached.\n");
4282 		goto out;
4283 	}
4284 
4285 	disk = alloc_disk(1);
4286 	if (!disk) {
4287 		sdev_printk(KERN_ERR, SDp,
4288 			    "st: out of memory. Device not attached.\n");
4289 		goto out_buffer_free;
4290 	}
4291 
4292 	tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
4293 	if (tpnt == NULL) {
4294 		sdev_printk(KERN_ERR, SDp,
4295 			    "st: Can't allocate device descriptor.\n");
4296 		goto out_put_disk;
4297 	}
4298 	kref_init(&tpnt->kref);
4299 	tpnt->disk = disk;
4300 	disk->private_data = &tpnt->driver;
4301 	disk->queue = SDp->request_queue;
4302 	/* SCSI tape doesn't register this gendisk via add_disk().  Manually
4303 	 * take queue reference that release_disk() expects. */
4304 	if (!blk_get_queue(disk->queue))
4305 		goto out_put_disk;
4306 	tpnt->driver = &st_template;
4307 
4308 	tpnt->device = SDp;
4309 	if (SDp->scsi_level <= 2)
4310 		tpnt->tape_type = MT_ISSCSI1;
4311 	else
4312 		tpnt->tape_type = MT_ISSCSI2;
4313 
4314 	tpnt->buffer = buffer;
4315 	tpnt->buffer->last_SRpnt = NULL;
4316 
4317 	tpnt->inited = 0;
4318 	tpnt->dirty = 0;
4319 	tpnt->in_use = 0;
4320 	tpnt->drv_buffer = 1;	/* Try buffering if no mode sense */
4321 	tpnt->restr_dma = (SDp->host)->unchecked_isa_dma;
4322 	tpnt->use_pf = (SDp->scsi_level >= SCSI_2);
4323 	tpnt->density = 0;
4324 	tpnt->do_auto_lock = ST_AUTO_LOCK;
4325 	tpnt->can_bsr = (SDp->scsi_level > 2 ? 1 : ST_IN_FILE_POS); /* BSR mandatory in SCSI3 */
4326 	tpnt->can_partitions = 0;
4327 	tpnt->two_fm = ST_TWO_FM;
4328 	tpnt->fast_mteom = ST_FAST_MTEOM;
4329 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
4330 	tpnt->sili = ST_SILI;
4331 	tpnt->immediate = ST_NOWAIT;
4332 	tpnt->immediate_filemark = 0;
4333 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
4334 	tpnt->partition = 0;
4335 	tpnt->new_partition = 0;
4336 	tpnt->nbr_partitions = 0;
4337 	blk_queue_rq_timeout(tpnt->device->request_queue, ST_TIMEOUT);
4338 	tpnt->long_timeout = ST_LONG_TIMEOUT;
4339 	tpnt->try_dio = try_direct_io && !SDp->host->unchecked_isa_dma;
4340 
4341 	for (i = 0; i < ST_NBR_MODES; i++) {
4342 		STm = &(tpnt->modes[i]);
4343 		STm->defined = 0;
4344 		STm->sysv = ST_SYSV;
4345 		STm->defaults_for_writes = 0;
4346 		STm->do_async_writes = ST_ASYNC_WRITES;
4347 		STm->do_buffer_writes = ST_BUFFER_WRITES;
4348 		STm->do_read_ahead = ST_READ_AHEAD;
4349 		STm->default_compression = ST_DONT_TOUCH;
4350 		STm->default_blksize = (-1);	/* No forced size */
4351 		STm->default_density = (-1);	/* No forced density */
4352 		STm->tape = tpnt;
4353 	}
4354 
4355 	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
4356 		STps = &(tpnt->ps[i]);
4357 		STps->rw = ST_IDLE;
4358 		STps->eof = ST_NOEOF;
4359 		STps->at_sm = 0;
4360 		STps->last_block_valid = 0;
4361 		STps->drv_block = (-1);
4362 		STps->drv_file = (-1);
4363 	}
4364 
4365 	tpnt->current_mode = 0;
4366 	tpnt->modes[0].defined = 1;
4367 
4368 	tpnt->density_changed = tpnt->compression_changed =
4369 	    tpnt->blksize_changed = 0;
4370 	mutex_init(&tpnt->lock);
4371 
4372 	idr_preload(GFP_KERNEL);
4373 	spin_lock(&st_index_lock);
4374 	error = idr_alloc(&st_index_idr, tpnt, 0, ST_MAX_TAPES + 1, GFP_NOWAIT);
4375 	spin_unlock(&st_index_lock);
4376 	idr_preload_end();
4377 	if (error < 0) {
4378 		pr_warn("st: idr allocation failed: %d\n", error);
4379 		goto out_put_queue;
4380 	}
4381 	tpnt->index = error;
4382 	sprintf(disk->disk_name, "st%d", tpnt->index);
4383 	tpnt->stats = kzalloc(sizeof(struct scsi_tape_stats), GFP_KERNEL);
4384 	if (tpnt->stats == NULL) {
4385 		sdev_printk(KERN_ERR, SDp,
4386 			    "st: Can't allocate statistics.\n");
4387 		goto out_idr_remove;
4388 	}
4389 
4390 	dev_set_drvdata(dev, tpnt);
4391 
4392 
4393 	error = create_cdevs(tpnt);
4394 	if (error)
4395 		goto out_remove_devs;
4396 	scsi_autopm_put_device(SDp);
4397 
4398 	sdev_printk(KERN_NOTICE, SDp,
4399 		    "Attached scsi tape %s\n", tape_name(tpnt));
4400 	sdev_printk(KERN_INFO, SDp, "%s: try direct i/o: %s (alignment %d B)\n",
4401 		    tape_name(tpnt), tpnt->try_dio ? "yes" : "no",
4402 		    queue_dma_alignment(SDp->request_queue) + 1);
4403 
4404 	return 0;
4405 
4406 out_remove_devs:
4407 	remove_cdevs(tpnt);
4408 	kfree(tpnt->stats);
4409 out_idr_remove:
4410 	spin_lock(&st_index_lock);
4411 	idr_remove(&st_index_idr, tpnt->index);
4412 	spin_unlock(&st_index_lock);
4413 out_put_queue:
4414 	blk_put_queue(disk->queue);
4415 out_put_disk:
4416 	put_disk(disk);
4417 	kfree(tpnt);
4418 out_buffer_free:
4419 	kfree(buffer);
4420 out:
4421 	scsi_autopm_put_device(SDp);
4422 	return -ENODEV;
4423 };
4424 
4425 
4426 static int st_remove(struct device *dev)
4427 {
4428 	struct scsi_tape *tpnt = dev_get_drvdata(dev);
4429 	int index = tpnt->index;
4430 
4431 	scsi_autopm_get_device(to_scsi_device(dev));
4432 	remove_cdevs(tpnt);
4433 
4434 	mutex_lock(&st_ref_mutex);
4435 	kref_put(&tpnt->kref, scsi_tape_release);
4436 	mutex_unlock(&st_ref_mutex);
4437 	spin_lock(&st_index_lock);
4438 	idr_remove(&st_index_idr, index);
4439 	spin_unlock(&st_index_lock);
4440 	return 0;
4441 }
4442 
4443 /**
4444  *      scsi_tape_release - Called to free the Scsi_Tape structure
4445  *      @kref: pointer to embedded kref
4446  *
4447  *      st_ref_mutex must be held entering this routine.  Because it is
4448  *      called on last put, you should always use the scsi_tape_get()
4449  *      scsi_tape_put() helpers which manipulate the semaphore directly
4450  *      and never do a direct kref_put().
4451  **/
4452 static void scsi_tape_release(struct kref *kref)
4453 {
4454 	struct scsi_tape *tpnt = to_scsi_tape(kref);
4455 	struct gendisk *disk = tpnt->disk;
4456 
4457 	tpnt->device = NULL;
4458 
4459 	if (tpnt->buffer) {
4460 		normalize_buffer(tpnt->buffer);
4461 		kfree(tpnt->buffer->reserved_pages);
4462 		kfree(tpnt->buffer);
4463 	}
4464 
4465 	disk->private_data = NULL;
4466 	put_disk(disk);
4467 	kfree(tpnt->stats);
4468 	kfree(tpnt);
4469 	return;
4470 }
4471 
4472 static struct class st_sysfs_class = {
4473 	.name = "scsi_tape",
4474 	.dev_groups = st_dev_groups,
4475 };
4476 
4477 static int __init init_st(void)
4478 {
4479 	int err;
4480 
4481 	validate_options();
4482 
4483 	printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
4484 		verstr, st_fixed_buffer_size, st_max_sg_segs);
4485 
4486 	debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
4487 	if (debugging) {
4488 		printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
4489 			debugging);
4490 	}
4491 
4492 	err = class_register(&st_sysfs_class);
4493 	if (err) {
4494 		pr_err("Unable register sysfs class for SCSI tapes\n");
4495 		return err;
4496 	}
4497 
4498 	err = register_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4499 				     ST_MAX_TAPE_ENTRIES, "st");
4500 	if (err) {
4501 		printk(KERN_ERR "Unable to get major %d for SCSI tapes\n",
4502 		       SCSI_TAPE_MAJOR);
4503 		goto err_class;
4504 	}
4505 
4506 	err = scsi_register_driver(&st_template.gendrv);
4507 	if (err)
4508 		goto err_chrdev;
4509 
4510 	return 0;
4511 
4512 err_chrdev:
4513 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4514 				 ST_MAX_TAPE_ENTRIES);
4515 err_class:
4516 	class_unregister(&st_sysfs_class);
4517 	return err;
4518 }
4519 
4520 static void __exit exit_st(void)
4521 {
4522 	scsi_unregister_driver(&st_template.gendrv);
4523 	unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
4524 				 ST_MAX_TAPE_ENTRIES);
4525 	class_unregister(&st_sysfs_class);
4526 	idr_destroy(&st_index_idr);
4527 	printk(KERN_INFO "st: Unloaded.\n");
4528 }
4529 
4530 module_init(init_st);
4531 module_exit(exit_st);
4532 
4533 
4534 /* The sysfs driver interface. Read-only at the moment */
4535 static ssize_t try_direct_io_show(struct device_driver *ddp, char *buf)
4536 {
4537 	return scnprintf(buf, PAGE_SIZE, "%d\n", try_direct_io);
4538 }
4539 static DRIVER_ATTR_RO(try_direct_io);
4540 
4541 static ssize_t fixed_buffer_size_show(struct device_driver *ddp, char *buf)
4542 {
4543 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_fixed_buffer_size);
4544 }
4545 static DRIVER_ATTR_RO(fixed_buffer_size);
4546 
4547 static ssize_t max_sg_segs_show(struct device_driver *ddp, char *buf)
4548 {
4549 	return scnprintf(buf, PAGE_SIZE, "%d\n", st_max_sg_segs);
4550 }
4551 static DRIVER_ATTR_RO(max_sg_segs);
4552 
4553 static ssize_t version_show(struct device_driver *ddd, char *buf)
4554 {
4555 	return scnprintf(buf, PAGE_SIZE, "[%s]\n", verstr);
4556 }
4557 static DRIVER_ATTR_RO(version);
4558 
4559 #if DEBUG
4560 static ssize_t debug_flag_store(struct device_driver *ddp,
4561 	const char *buf, size_t count)
4562 {
4563 /* We only care what the first byte of the data is the rest is unused.
4564  * if it's a '1' we turn on debug and if it's a '0' we disable it. All
4565  * other values have -EINVAL returned if they are passed in.
4566  */
4567 	if (count > 0) {
4568 		if (buf[0] == '0') {
4569 			debugging = NO_DEBUG;
4570 			return count;
4571 		} else if (buf[0] == '1') {
4572 			debugging = 1;
4573 			return count;
4574 		}
4575 	}
4576 	return -EINVAL;
4577 }
4578 
4579 static ssize_t debug_flag_show(struct device_driver *ddp, char *buf)
4580 {
4581 	return scnprintf(buf, PAGE_SIZE, "%d\n", debugging);
4582 }
4583 static DRIVER_ATTR_RW(debug_flag);
4584 #endif
4585 
4586 static struct attribute *st_drv_attrs[] = {
4587 	&driver_attr_try_direct_io.attr,
4588 	&driver_attr_fixed_buffer_size.attr,
4589 	&driver_attr_max_sg_segs.attr,
4590 	&driver_attr_version.attr,
4591 #if DEBUG
4592 	&driver_attr_debug_flag.attr,
4593 #endif
4594 	NULL,
4595 };
4596 ATTRIBUTE_GROUPS(st_drv);
4597 
4598 /* The sysfs simple class interface */
4599 static ssize_t
4600 defined_show(struct device *dev, struct device_attribute *attr, char *buf)
4601 {
4602 	struct st_modedef *STm = dev_get_drvdata(dev);
4603 	ssize_t l = 0;
4604 
4605 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->defined);
4606 	return l;
4607 }
4608 static DEVICE_ATTR_RO(defined);
4609 
4610 static ssize_t
4611 default_blksize_show(struct device *dev, struct device_attribute *attr,
4612 		     char *buf)
4613 {
4614 	struct st_modedef *STm = dev_get_drvdata(dev);
4615 	ssize_t l = 0;
4616 
4617 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_blksize);
4618 	return l;
4619 }
4620 static DEVICE_ATTR_RO(default_blksize);
4621 
4622 static ssize_t
4623 default_density_show(struct device *dev, struct device_attribute *attr,
4624 		     char *buf)
4625 {
4626 	struct st_modedef *STm = dev_get_drvdata(dev);
4627 	ssize_t l = 0;
4628 	char *fmt;
4629 
4630 	fmt = STm->default_density >= 0 ? "0x%02x\n" : "%d\n";
4631 	l = snprintf(buf, PAGE_SIZE, fmt, STm->default_density);
4632 	return l;
4633 }
4634 static DEVICE_ATTR_RO(default_density);
4635 
4636 static ssize_t
4637 default_compression_show(struct device *dev, struct device_attribute *attr,
4638 			 char *buf)
4639 {
4640 	struct st_modedef *STm = dev_get_drvdata(dev);
4641 	ssize_t l = 0;
4642 
4643 	l = snprintf(buf, PAGE_SIZE, "%d\n", STm->default_compression - 1);
4644 	return l;
4645 }
4646 static DEVICE_ATTR_RO(default_compression);
4647 
4648 static ssize_t
4649 options_show(struct device *dev, struct device_attribute *attr, char *buf)
4650 {
4651 	struct st_modedef *STm = dev_get_drvdata(dev);
4652 	struct scsi_tape *STp = STm->tape;
4653 	int options;
4654 	ssize_t l = 0;
4655 
4656 	options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
4657 	options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
4658 	options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
4659 	DEB( options |= debugging ? MT_ST_DEBUGGING : 0 );
4660 	options |= STp->two_fm ? MT_ST_TWO_FM : 0;
4661 	options |= STp->fast_mteom ? MT_ST_FAST_MTEOM : 0;
4662 	options |= STm->defaults_for_writes ? MT_ST_DEF_WRITES : 0;
4663 	options |= STp->can_bsr ? MT_ST_CAN_BSR : 0;
4664 	options |= STp->omit_blklims ? MT_ST_NO_BLKLIMS : 0;
4665 	options |= STp->can_partitions ? MT_ST_CAN_PARTITIONS : 0;
4666 	options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
4667 	options |= STm->sysv ? MT_ST_SYSV : 0;
4668 	options |= STp->immediate ? MT_ST_NOWAIT : 0;
4669 	options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
4670 	options |= STp->sili ? MT_ST_SILI : 0;
4671 
4672 	l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);
4673 	return l;
4674 }
4675 static DEVICE_ATTR_RO(options);
4676 
4677 /* Support for tape stats */
4678 
4679 /**
4680  * read_cnt_show - return read count - count of reads made from tape drive
4681  * @dev: struct device
4682  * @attr: attribute structure
4683  * @buf: buffer to return formatted data in
4684  */
4685 static ssize_t read_cnt_show(struct device *dev,
4686 	struct device_attribute *attr, char *buf)
4687 {
4688 	struct st_modedef *STm = dev_get_drvdata(dev);
4689 
4690 	return sprintf(buf, "%lld",
4691 		       (long long)atomic64_read(&STm->tape->stats->read_cnt));
4692 }
4693 static DEVICE_ATTR_RO(read_cnt);
4694 
4695 /**
4696  * read_byte_cnt_show - return read byte count - tape drives
4697  * may use blocks less than 512 bytes this gives the raw byte count of
4698  * of data read from the tape drive.
4699  * @dev: struct device
4700  * @attr: attribute structure
4701  * @buf: buffer to return formatted data in
4702  */
4703 static ssize_t read_byte_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->read_byte_cnt));
4710 }
4711 static DEVICE_ATTR_RO(read_byte_cnt);
4712 
4713 /**
4714  * read_us_show - return read us - overall time spent waiting on reads in ns.
4715  * @dev: struct device
4716  * @attr: attribute structure
4717  * @buf: buffer to return formatted data in
4718  */
4719 static ssize_t read_ns_show(struct device *dev,
4720 	struct device_attribute *attr, char *buf)
4721 {
4722 	struct st_modedef *STm = dev_get_drvdata(dev);
4723 
4724 	return sprintf(buf, "%lld",
4725 		       (long long)atomic64_read(&STm->tape->stats->tot_read_time));
4726 }
4727 static DEVICE_ATTR_RO(read_ns);
4728 
4729 /**
4730  * write_cnt_show - write count - number of user calls
4731  * to write(2) that have written data to tape.
4732  * @dev: struct device
4733  * @attr: attribute structure
4734  * @buf: buffer to return formatted data in
4735  */
4736 static ssize_t write_cnt_show(struct device *dev,
4737 	struct device_attribute *attr, char *buf)
4738 {
4739 	struct st_modedef *STm = dev_get_drvdata(dev);
4740 
4741 	return sprintf(buf, "%lld",
4742 		       (long long)atomic64_read(&STm->tape->stats->write_cnt));
4743 }
4744 static DEVICE_ATTR_RO(write_cnt);
4745 
4746 /**
4747  * write_byte_cnt_show - write byte count - raw count of
4748  * bytes written to tape.
4749  * @dev: struct device
4750  * @attr: attribute structure
4751  * @buf: buffer to return formatted data in
4752  */
4753 static ssize_t write_byte_cnt_show(struct device *dev,
4754 	struct device_attribute *attr, char *buf)
4755 {
4756 	struct st_modedef *STm = dev_get_drvdata(dev);
4757 
4758 	return sprintf(buf, "%lld",
4759 		       (long long)atomic64_read(&STm->tape->stats->write_byte_cnt));
4760 }
4761 static DEVICE_ATTR_RO(write_byte_cnt);
4762 
4763 /**
4764  * write_ns_show - write ns - number of nanoseconds waiting on write
4765  * requests to complete.
4766  * @dev: struct device
4767  * @attr: attribute structure
4768  * @buf: buffer to return formatted data in
4769  */
4770 static ssize_t write_ns_show(struct device *dev,
4771 	struct device_attribute *attr, char *buf)
4772 {
4773 	struct st_modedef *STm = dev_get_drvdata(dev);
4774 
4775 	return sprintf(buf, "%lld",
4776 		       (long long)atomic64_read(&STm->tape->stats->tot_write_time));
4777 }
4778 static DEVICE_ATTR_RO(write_ns);
4779 
4780 /**
4781  * in_flight_show - number of I/Os currently in flight -
4782  * in most cases this will be either 0 or 1. It may be higher if someone
4783  * has also issued other SCSI commands such as via an ioctl.
4784  * @dev: struct device
4785  * @attr: attribute structure
4786  * @buf: buffer to return formatted data in
4787  */
4788 static ssize_t in_flight_show(struct device *dev,
4789 	struct device_attribute *attr, char *buf)
4790 {
4791 	struct st_modedef *STm = dev_get_drvdata(dev);
4792 
4793 	return sprintf(buf, "%lld",
4794 		       (long long)atomic64_read(&STm->tape->stats->in_flight));
4795 }
4796 static DEVICE_ATTR_RO(in_flight);
4797 
4798 /**
4799  * io_ns_show - io wait ns - this is the number of ns spent
4800  * waiting on all I/O to complete. This includes tape movement commands
4801  * such as rewinding, seeking to end of file or tape, it also includes
4802  * read and write. To determine the time spent on tape movement
4803  * subtract the read and write ns from this value.
4804  * @dev: struct device
4805  * @attr: attribute structure
4806  * @buf: buffer to return formatted data in
4807  */
4808 static ssize_t io_ns_show(struct device *dev,
4809 	struct device_attribute *attr, char *buf)
4810 {
4811 	struct st_modedef *STm = dev_get_drvdata(dev);
4812 
4813 	return sprintf(buf, "%lld",
4814 		       (long long)atomic64_read(&STm->tape->stats->tot_io_time));
4815 }
4816 static DEVICE_ATTR_RO(io_ns);
4817 
4818 /**
4819  * other_cnt_show - other io count - this is the number of
4820  * I/O requests other than read and write requests.
4821  * Typically these are tape movement requests but will include driver
4822  * tape movement. This includes only requests issued by the st driver.
4823  * @dev: struct device
4824  * @attr: attribute structure
4825  * @buf: buffer to return formatted data in
4826  */
4827 static ssize_t other_cnt_show(struct device *dev,
4828 	struct device_attribute *attr, char *buf)
4829 {
4830 	struct st_modedef *STm = dev_get_drvdata(dev);
4831 
4832 	return sprintf(buf, "%lld",
4833 		       (long long)atomic64_read(&STm->tape->stats->other_cnt));
4834 }
4835 static DEVICE_ATTR_RO(other_cnt);
4836 
4837 /**
4838  * resid_cnt_show - A count of the number of times we get a residual
4839  * count - this should indicate someone issuing reads larger than the
4840  * block size on tape.
4841  * @dev: struct device
4842  * @attr: attribute structure
4843  * @buf: buffer to return formatted data in
4844  */
4845 static ssize_t resid_cnt_show(struct device *dev,
4846 	struct device_attribute *attr, char *buf)
4847 {
4848 	struct st_modedef *STm = dev_get_drvdata(dev);
4849 
4850 	return sprintf(buf, "%lld",
4851 		       (long long)atomic64_read(&STm->tape->stats->resid_cnt));
4852 }
4853 static DEVICE_ATTR_RO(resid_cnt);
4854 
4855 static struct attribute *st_dev_attrs[] = {
4856 	&dev_attr_defined.attr,
4857 	&dev_attr_default_blksize.attr,
4858 	&dev_attr_default_density.attr,
4859 	&dev_attr_default_compression.attr,
4860 	&dev_attr_options.attr,
4861 	NULL,
4862 };
4863 
4864 static struct attribute *st_stats_attrs[] = {
4865 	&dev_attr_read_cnt.attr,
4866 	&dev_attr_read_byte_cnt.attr,
4867 	&dev_attr_read_ns.attr,
4868 	&dev_attr_write_cnt.attr,
4869 	&dev_attr_write_byte_cnt.attr,
4870 	&dev_attr_write_ns.attr,
4871 	&dev_attr_in_flight.attr,
4872 	&dev_attr_io_ns.attr,
4873 	&dev_attr_other_cnt.attr,
4874 	&dev_attr_resid_cnt.attr,
4875 	NULL,
4876 };
4877 
4878 static struct attribute_group stats_group = {
4879 	.name = "stats",
4880 	.attrs = st_stats_attrs,
4881 };
4882 
4883 static struct attribute_group st_group = {
4884 	.attrs = st_dev_attrs,
4885 };
4886 
4887 static const struct attribute_group *st_dev_groups[] = {
4888 	&st_group,
4889 	&stats_group,
4890 	NULL,
4891 };
4892 
4893 /* The following functions may be useful for a larger audience. */
4894 static int sgl_map_user_pages(struct st_buffer *STbp,
4895 			      const unsigned int max_pages, unsigned long uaddr,
4896 			      size_t count, int rw)
4897 {
4898 	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
4899 	unsigned long start = uaddr >> PAGE_SHIFT;
4900 	const int nr_pages = end - start;
4901 	int res, i, j;
4902 	struct page **pages;
4903 	struct rq_map_data *mdata = &STbp->map_data;
4904 
4905 	/* User attempted Overflow! */
4906 	if ((uaddr + count) < uaddr)
4907 		return -EINVAL;
4908 
4909 	/* Too big */
4910         if (nr_pages > max_pages)
4911 		return -ENOMEM;
4912 
4913 	/* Hmm? */
4914 	if (count == 0)
4915 		return 0;
4916 
4917 	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_KERNEL)) == NULL)
4918 		return -ENOMEM;
4919 
4920         /* Try to fault in all of the necessary pages */
4921         /* rw==READ means read from drive, write into memory area */
4922 	res = get_user_pages_unlocked(
4923 		uaddr,
4924 		nr_pages,
4925 		pages,
4926 		rw == READ ? FOLL_WRITE : 0); /* don't force */
4927 
4928 	/* Errors and no page mapped should return here */
4929 	if (res < nr_pages)
4930 		goto out_unmap;
4931 
4932         for (i=0; i < nr_pages; i++) {
4933                 /* FIXME: flush superflous for rw==READ,
4934                  * probably wrong function for rw==WRITE
4935                  */
4936 		flush_dcache_page(pages[i]);
4937         }
4938 
4939 	mdata->offset = uaddr & ~PAGE_MASK;
4940 	STbp->mapped_pages = pages;
4941 
4942 	return nr_pages;
4943  out_unmap:
4944 	if (res > 0) {
4945 		for (j=0; j < res; j++)
4946 			put_page(pages[j]);
4947 		res = 0;
4948 	}
4949 	kfree(pages);
4950 	return res;
4951 }
4952 
4953 
4954 /* And unmap them... */
4955 static int sgl_unmap_user_pages(struct st_buffer *STbp,
4956 				const unsigned int nr_pages, int dirtied)
4957 {
4958 	int i;
4959 
4960 	for (i=0; i < nr_pages; i++) {
4961 		struct page *page = STbp->mapped_pages[i];
4962 
4963 		if (dirtied)
4964 			SetPageDirty(page);
4965 		/* FIXME: cache flush missing for rw==READ
4966 		 * FIXME: call the correct reference counting function
4967 		 */
4968 		put_page(page);
4969 	}
4970 	kfree(STbp->mapped_pages);
4971 	STbp->mapped_pages = NULL;
4972 
4973 	return 0;
4974 }
4975