aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/ftape/zftape/zftape-vtbl.c
blob: ad7f8be6340bd445274a1cbf0a5af42064639ad9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
/*
 *      Copyright (c) 1995-1997 Claus-Justus Heine 

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License as
 published by the Free Software Foundation; either version 2, or (at
 your option) any later version.
 
 This program is distributed in the hope that it will be useful, but
 WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; see the file COPYING.  If not, write to
 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 USA.

 *
 * $Source: /homes/cvs/ftape-stacked/ftape/zftape/zftape-vtbl.c,v $
 * $Revision: 1.7.6.1 $
 * $Date: 1997/11/24 13:48:31 $
 *
 *      This file defines a volume table as defined in various QIC
 *      standards.
 * 
 *      This is a minimal implementation, just allowing ordinary DOS
 *      :( prgrams to identify the cartridge as used.
 */

#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include <linux/zftape.h>
#include "../zftape/zftape-init.h"
#include "../zftape/zftape-eof.h"
#include "../zftape/zftape-ctl.h"
#include "../zftape/zftape-write.h"
#include "../zftape/zftape-read.h"
#include "../zftape/zftape-rw.h"
#include "../zftape/zftape-vtbl.h"

#define ZFT_CMAP_HACK /* leave this defined to hide the compression map */

/*
 *  global variables 
 */
int zft_qic_mode   = 1; /* use the vtbl */
int zft_old_ftape; /* prevents old ftaped tapes to be overwritten */
int zft_volume_table_changed; /* for write_header_segments() */

/*
 *  private variables (only exported for inline functions)
 */
LIST_HEAD(zft_vtbl);

/*  We could also allocate these dynamically when extracting the volume table
 *  sizeof(zft_volinfo) is about 32 or something close to that
 */
static zft_volinfo  tape_vtbl;
static zft_volinfo  eot_vtbl;
static zft_volinfo *cur_vtbl;

static inline void zft_new_vtbl_entry(void)
{
	struct list_head *tmp = &zft_last_vtbl->node;
	zft_volinfo *new = zft_kmalloc(sizeof(zft_volinfo));

	list_add(&new->node, tmp);
	new->count = zft_eom_vtbl->count ++;
}

void zft_free_vtbl(void)
{
	for (;;) {
		struct list_head *tmp = zft_vtbl.prev;
		zft_volinfo *vtbl;

		if (tmp == &zft_vtbl)
			break;
		list_del(tmp);
		vtbl = list_entry(tmp, zft_volinfo, node);
		zft_kfree(vtbl, sizeof(zft_volinfo));
	}
	INIT_LIST_HEAD(&zft_vtbl);
	cur_vtbl = NULL;
}

/*  initialize vtbl, called by ftape_new_cartridge()
 */
void zft_init_vtbl(void)
{ 
	zft_volinfo *new;

	zft_free_vtbl();
	
	/*  Create the two dummy vtbl entries
	 */
	new = zft_kmalloc(sizeof(zft_volinfo));
	list_add(&new->node, &zft_vtbl);
	new = zft_kmalloc(sizeof(zft_volinfo));
	list_add(&new->node, &zft_vtbl);
	zft_head_vtbl->end_seg   = ft_first_data_segment;
	zft_head_vtbl->blk_sz    = zft_blk_sz;
	zft_head_vtbl->count     = -1;
	zft_eom_vtbl->start_seg  = ft_first_data_segment + 1;
	zft_eom_vtbl->end_seg    = ft_last_data_segment + 1;
	zft_eom_vtbl->blk_sz     = zft_blk_sz;
	zft_eom_vtbl->count      = 0;

	/*  Reset the pointer for zft_find_volume()
	 */
	cur_vtbl = zft_eom_vtbl;

	/* initialize the dummy vtbl entries for zft_qic_mode == 0
	 */
	eot_vtbl.start_seg       = ft_last_data_segment + 1;
	eot_vtbl.end_seg         = ft_last_data_segment + 1;
	eot_vtbl.blk_sz          = zft_blk_sz;
	eot_vtbl.count           = -1;
	tape_vtbl.start_seg = ft_first_data_segment;
	tape_vtbl.end_seg   = ft_last_data_segment;
	tape_vtbl.blk_sz    = zft_blk_sz;
	tape_vtbl.size      = zft_capacity;
	tape_vtbl.count     = 0;
}

/* check for a valid VTBL signature. 
 */
static int vtbl_signature_valid(__u8 signature[4])
{
	const char *vtbl_ids[] = VTBL_IDS; /* valid signatures */
	int j;
	
	for (j = 0; 
	     (j < NR_ITEMS(vtbl_ids)) && (memcmp(signature, vtbl_ids[j], 4) != 0);
	     j++);
	return j < NR_ITEMS(vtbl_ids);
}

/* We used to store the block-size of the volume in the volume-label,
 * using the keyword "blocksize". The blocksize written to the
 * volume-label is in bytes.
 *
 * We use this now only for compatibility with old zftape version. We
 * store the blocksize directly as binary number in the vendor
 * extension part of the volume entry.
 */
static int check_volume_label(const char *label, int *blk_sz)
{ 
	int valid_format;
	char *blocksize;
	TRACE_FUN(ft_t_flow);
	
	TRACE(ft_t_noise, "called with \"%s\" / \"%s\"", label, ZFT_VOL_NAME);
	if (strncmp(label, ZFT_VOL_NAME, strlen(ZFT_VOL_NAME)) != 0) {
		*blk_sz = 1; /* smallest block size that we allow */
		valid_format = 0;
	} else {
		TRACE(ft_t_noise, "got old style zftape vtbl entry");
		/* get the default blocksize */
		/* use the kernel strstr()   */
		blocksize= strstr(label, " blocksize ");
		if (blocksize) {
			blocksize += strlen(" blocksize ");
			for(*blk_sz= 0; 
			    *blocksize >= '0' && *blocksize <= '9'; 
			    blocksize++) {
				*blk_sz *= 10;
				*blk_sz += *blocksize - '0';
			}
			if (*blk_sz > ZFT_MAX_BLK_SZ) {
				*blk_sz= 1;
				valid_format= 0;
			} else {
				valid_format = 1;
			}
		} else {
			*blk_sz= 1;
			valid_format= 0;
		}
	}
	TRACE_EXIT valid_format;
}

/*   check for a zftape volume
 */
static int check_volume(__u8 *entry, zft_volinfo *volume)
{
	TRACE_FUN(ft_t_flow);
	
	if(strncmp(&entry[VTBL_EXT+EXT_ZFTAPE_SIG], ZFTAPE_SIG,
		   strlen(ZFTAPE_SIG)) == 0) {
		TRACE(ft_t_noise, "got new style zftape vtbl entry");
		volume->blk_sz = GET2(entry, VTBL_EXT+EXT_ZFTAPE_BLKSZ);
		volume->qic113 = entry[VTBL_EXT+EXT_ZFTAPE_QIC113];
		TRACE_EXIT 1;
	} else {
		TRACE_EXIT check_volume_label(&entry[VTBL_DESC], &volume->blk_sz);
	}
}


/* create zftape specific vtbl entry, the volume bounds are inserted
 * in the calling function, zft_create_volume_headers()
 */
static void create_zft_volume(__u8 *entry, zft_volinfo *vtbl)
{
	TRACE_FUN(ft_t_flow);

	memset(entry, 0, VTBL_SIZE);
	memcpy(&entry[VTBL_SIG], VTBL_ID, 4);
	sprintf(&entry[VTBL_DESC], ZFT_VOL_NAME" %03d", vtbl->count);
	entry[VTBL_FLAGS] = (VTBL_FL_NOT_VERIFIED | VTBL_FL_SEG_SPANNING);
	entry[VTBL_M_NO] = 1; /* multi_cartridge_count */
	strcpy(&entry[VTBL_EXT+EXT_ZFTAPE_SIG], ZFTAPE_SIG);
	PUT2(entry, VTBL_EXT+EXT_ZFTAPE_BLKSZ, vtbl->blk_sz);
	if (zft_qic113) {
		PUT8(entry, VTBL_DATA_SIZE, vtbl->size);
		entry[VTBL_CMPR] = VTBL_CMPR_UNREG; 
		if (vtbl->use_compression) { /* use compression: */
			entry[VTBL_CMPR] |= VTBL_CMPR_USED;
		}
		entry[VTBL_EXT+EXT_ZFTAPE_QIC113] = 1;
	} else {
		PUT4(entry, VTBL_DATA_SIZE, vtbl->size);
		entry[VTBL_K_CMPR] = VTBL_CMPR_UNREG; 
		if (vtbl->use_compression) { /* use compression: */
			entry[VTBL_K_CMPR] |= VTBL_CMPR_USED;
		}
	}
	if (ft_format_code == fmt_big) {
		/* SCSI like vtbl, store the number of used
		 * segments as 4 byte value 
		 */
		PUT4(entry, VTBL_SCSI_SEGS, vtbl->end_seg-vtbl->start_seg + 1);
	} else {
		/* normal, QIC-80MC like vtbl 
		 */
		PUT2(entry, VTBL_START, vtbl->start_seg);
		PUT2(entry, VTBL_END, vtbl->end_seg);
	}
	TRACE_EXIT;
}

/* this one creates the volume headers for each volume. It is assumed
 * that buffer already contains the old volume-table, so that vtbl
 * entries without the zft_volume flag set can savely be ignored.
 */
static void zft_create_volume_headers(__u8 *buffer)
{   
	__u8 *entry;
	struct list_head *tmp;
	zft_volinfo *vtbl;
	TRACE_FUN(ft_t_flow);
	
#ifdef ZFT_CMAP_HACK
	if((strncmp(&buffer[VTBL_EXT+EXT_ZFTAPE_SIG], ZFTAPE_SIG,
		    strlen(ZFTAPE_SIG)) == 0) && 
	   buffer[VTBL_EXT+EXT_ZFTAPE_CMAP] != 0) {
		TRACE(ft_t_noise, "deleting cmap volume");
		memmove(buffer, buffer + VTBL_SIZE,
			FT_SEGMENT_SIZE - VTBL_SIZE);
	}
#endif
	entry = buffer;
	for (tmp = zft_head_vtbl->node.next;
	     tmp != &zft_eom_vtbl->node;
	     tmp = tmp->next) {
		vtbl = list_entry(tmp, zft_volinfo, node);
		/* we now fill in the values only for newly created volumes.
		 */
		if (vtbl->new_volume) {
			create_zft_volume(entry, vtbl);
			vtbl->new_volume = 0; /* clear the flag */
		}
		
		DUMP_VOLINFO(ft_t_noise, &entry[VTBL_DESC], vtbl);
		entry += VTBL_SIZE;
	}
	memset(entry, 0, FT_SEGMENT_SIZE - zft_eom_vtbl->count * VTBL_SIZE);
	TRACE_EXIT;
}

/*  write volume table to tape. Calls zft_create_volume_headers()
 */
int zft_update_volume_table(unsigned int segment)
{
	int result = 0;
	__u8 *verify_buf = NULL;
	TRACE_FUN(ft_t_flow);

	TRACE_CATCH(result = ftape_read_segment(ft_first_data_segment, 
						zft_deblock_buf,
						FT_RD_SINGLE),);
	zft_create_volume_headers(zft_deblock_buf);
	TRACE(ft_t_noise, "writing volume table segment %d", segment);
	if (zft_vmalloc_once(&verify_buf, FT_SEGMENT_SIZE) == 0) {
		TRACE_CATCH(zft_verify_write_segments(segment, 
						      zft_deblock_buf, result,
						      verify_buf),
			    zft_vfree(&verify_buf, FT_SEGMENT_SIZE));
		zft_vfree(&verify_buf, FT_SEGMENT_SIZE);
	} else {
		TRACE_CATCH(ftape_write_segment(segment, zft_deblock_buf, 
						FT_WR_SINGLE),);
	}
	TRACE_EXIT 0;
}

/* non zftape volumes are handled in raw mode. Thus we need to
 * calculate the raw amount of data contained in those segments.  
 */
static void extract_alien_volume(__u8 *entry, zft_volinfo *vtbl)
{
	TRACE_FUN(ft_t_flow);

	vtbl->size  = (zft_calc_tape_pos(zft_last_vtbl->end_seg+1) -
		       zft_calc_tape_pos(zft_last_vtbl->start_seg));
	vtbl->use_compression = 0;
	vtbl->qic113 = zft_qic113;
	if (vtbl->qic113) {
		TRACE(ft_t_noise, 
		      "Fake alien volume's size from " LL_X " to " LL_X, 
		      LL(GET8(entry, VTBL_DATA_SIZE)), LL(vtbl->size));
	} else {
		TRACE(ft_t_noise,
		      "Fake alien volume's size from %d to " LL_X, 
		      (int)GET4(entry, VTBL_DATA_SIZE), LL(vtbl->size));
	}
	TRACE_EXIT;
}


/* extract an zftape specific volume
 */
static void extract_zft_volume(__u8 *entry, zft_volinfo *vtbl)
{
	TRACE_FUN(ft_t_flow);

	if (vtbl->qic113) {
		vtbl->size = GET8(entry, VTBL_DATA_SIZE);
		vtbl->use_compression = 
			(entry[VTBL_CMPR] & VTBL_CMPR_USED) != 0; 
	} else {
		vtbl->size = GET4(entry, VTBL_DATA_SIZE);
		if (entry[VTBL_K_CMPR] & VTBL_CMPR_UNREG) {
			vtbl->use_compression = 
				(entry[VTBL_K_CMPR] & VTBL_CMPR_USED) != 0;
		} else if (entry[VTBL_CMPR] & VTBL_CMPR_UNREG) {
			vtbl->use_compression = 
				(entry[VTBL_CMPR] & VTBL_CMPR_USED) != 0; 
		} else {
			TRACE(ft_t_warn, "Geeh! There is something wrong:\n"
			      KERN_INFO "QIC compression (Rev = K): %x\n"
			      KERN_INFO "QIC compression (Rev > K): %x",
			      entry[VTBL_K_CMPR], entry[VTBL_CMPR]);
		}
	}
	TRACE_EXIT;
}

/* extract the volume table from buffer. "buffer" must already contain
 * the vtbl-segment 
 */
int zft_extract_volume_headers(__u8 *buffer)
{                            
        __u8 *entry;
	TRACE_FUN(ft_t_flow);
	
	zft_init_vtbl();
	entry = buffer;
#ifdef ZFT_CMAP_HACK
	if ((strncmp(&entry[VTBL_EXT+EXT_ZFTAPE_SIG], ZFTAPE_SIG,
		     strlen(ZFTAPE_SIG)) == 0) &&
	    entry[VTBL_EXT+EXT_ZFTAPE_CMAP] != 0) {
		TRACE(ft_t_noise, "ignoring cmap volume");
		entry += VTBL_SIZE;
	} 
#endif
	/* the end of the vtbl is indicated by an invalid signature 
	 */
	while (vtbl_signature_valid(&entry[VTBL_SIG]) &&
	       (entry - buffer) < FT_SEGMENT_SIZE) {
		zft_new_vtbl_entry();
		if (ft_format_code == fmt_big) {
			/* SCSI like vtbl, stores only the number of
			 * segments used 
			 */
			unsigned int num_segments= GET4(entry, VTBL_SCSI_SEGS);
			zft_last_vtbl->start_seg = zft_eom_vtbl->start_seg;
			zft_last_vtbl->end_seg = 
				zft_last_vtbl->start_seg + num_segments - 1;
		} else {
			/* `normal', QIC-80 like vtbl 
			 */
			zft_last_vtbl->start_seg = GET2(entry, VTBL_START);
			zft_last_vtbl->end_seg   = GET2(entry, VTBL_END);
		}
		zft_eom_vtbl->start_seg  = zft_last_vtbl->end_seg + 1;
		/* check if we created this volume and get the
		 * blk_sz 
		 */
		zft_last_vtbl->zft_volume = check_volume(entry, zft_last_vtbl);
		if (zft_last_vtbl->zft_volume == 0) {
			extract_alien_volume(entry, zft_last_vtbl);
		} else {
			extract_zft_volume(entry, zft_last_vtbl);
		}
		DUMP_VOLINFO(ft_t_noise, &entry[VTBL_DESC], zft_last_vtbl);
		entry +=VTBL_SIZE;
	}
#if 0
/*
 *  undefine to test end of tape handling
 */
	zft_new_vtbl_entry();
	zft_last_vtbl->start_seg = zft_eom_vtbl->start_seg;
	zft_last_vtbl->end_seg   = ft_last_data_segment - 10;
	zft_last_vtbl->blk_sz          = zft_blk_sz;
	zft_last_vtbl->zft_volume      = 1;
	zft_last_vtbl->qic113          = zft_qic113;
	zft_last_vtbl->size = (zft_calc_tape_pos(zft_last_vtbl->end_seg+1)
			       - zft_calc_tape_pos(zft_last_vtbl->start_seg));
#endif
	TRACE_EXIT 0;
}

/* this functions translates the failed_sector_log, misused as
 * EOF-marker list, into a virtual volume table. The table mustn't be
 * written to tape, because this would occupy the first data segment,
 * which should be the volume table, but is actually the first segment
 * that is filled with data (when using standard ftape).  We assume,
 * that we get a non-empty failed_sector_log.
 */
int zft_fake_volume_headers (eof_mark_union *eof_map, int num_failed_sectors)
{
	unsigned int segment, sector;
	int have_eom = 0;
	int vol_no;
	TRACE_FUN(ft_t_flow);

	if ((num_failed_sectors >= 2) &&
	    (GET2(&eof_map[num_failed_sectors - 1].mark.segment, 0) 
	     == 
	     GET2(&eof_map[num_failed_sectors - 2].mark.segment, 0) + 1) &&
	    (GET2(&eof_map[num_failed_sectors - 1].mark.date, 0) == 1)) {
		/* this should be eom. We keep the remainder of the
		 * tape as another volume.
		 */
		have_eom = 1;
	}
	zft_init_vtbl();
	zft_eom_vtbl->start_seg = ft_first_data_segment;
	for(vol_no = 0; vol_no < num_failed_sectors - have_eom; vol_no ++) {
		zft_new_vtbl_entry();

		segment = GET2(&eof_map[vol_no].mark.segment, 0);
		sector  = GET2(&eof_map[vol_no].mark.date, 0);

		zft_last_vtbl->start_seg  = zft_eom_vtbl->start_seg;
		zft_last_vtbl->end_seg    = segment;
		zft_eom_vtbl->start_seg  = segment + 1;
		zft_last_vtbl->blk_sz     = 1;
		zft_last_vtbl->size       = 
			(zft_calc_tape_pos(zft_last_vtbl->end_seg)
			 - zft_calc_tape_pos(zft_last_vtbl->start_seg)
			 + (sector-1) * FT_SECTOR_SIZE);
		TRACE(ft_t_noise, 
		      "failed sector log: segment: %d, sector: %d", 
		      segment, sector);
		DUMP_VOLINFO(ft_t_noise, "Faked volume", zft_last_vtbl);
	}
	if (!have_eom) {
		zft_new_vtbl_entry();
		zft_last_vtbl->start_seg = zft_eom_vtbl->start_seg;
		zft_last_vtbl->end_seg   = ft_last_data_segment;
		zft_eom_vtbl->start_seg  = ft_last_data_segment + 1;
		zft_last_vtbl->size      = zft_capacity;
		zft_last_vtbl->size     -= zft_calc_tape_pos(zft_last_vtbl->start_seg);
		zft_last_vtbl->blk_sz    = 1;
		DUMP_VOLINFO(ft_t_noise, "Faked volume",zft_last_vtbl);
	}
	TRACE_EXIT 0;
}

/* update the internal volume table
 *
 * if before start of last volume: erase all following volumes if
 * inside a volume: set end of volume to infinity
 *
 * this function is intended to be called every time _ftape_write() is
 * called
 *
 * return: 0 if no new volume was created, 1 if a new volume was
 * created
 *
 * NOTE: we don't need to check for zft_mode as ftape_write() does
 * that already. This function gets never called without accessing
 * zftape via the *qft* devices 
 */

int zft_open_volume(zft_position *pos, int blk_sz, int use_compression)
{ 
	TRACE_FUN(ft_t_flow);
	
	if (!zft_qic_mode) {
		TRACE_EXIT 0;
	}
	if (zft_tape_at_lbot(pos)) {
		zft_init_vtbl();
		if(zft_old_ftape) {
			/* clear old ftape's eof marks */
			zft_clear_ftape_file_marks();
			zft_old_ftape = 0; /* no longer old ftape */
		}
		zft_reset_position(pos);
	}
	if (pos->seg_pos != zft_last_vtbl->end_seg + 1) {
		TRACE_ABORT(-EIO, ft_t_bug, 
		      "BUG: seg_pos: %d, zft_last_vtbl->end_seg: %d", 
		      pos->seg_pos, zft_last_vtbl->end_seg);
	}                            
	TRACE(ft_t_noise, "create new volume");
	if (zft_eom_vtbl->count >= ZFT_MAX_VOLUMES) {
		TRACE_ABORT(-ENOSPC, ft_t_err,
			    "Error: maxmimal number of volumes exhausted "
			    "(maxmimum is %d)", ZFT_MAX_VOLUMES);
	}
	zft_new_vtbl_entry();
	pos->volume_pos = pos->seg_byte_pos = 0;
	zft_last_vtbl->start_seg       = pos->seg_pos;
	zft_last_vtbl->end_seg         = ft_last_data_segment; /* infinity */
	zft_last_vtbl->blk_sz          = blk_sz;
	zft_last_vtbl->size            = zft_capacity;
	zft_last_vtbl->zft_volume      = 1;
	zft_last_vtbl->use_compression = use_compression;
	zft_last_vtbl->qic113          = zft_qic113;
	zft_last_vtbl->new_volume      = 1;
	zft_last_vtbl->open            = 1;
	zft_volume_table_changed = 1;
	zft_eom_vtbl->start_seg  = ft_last_data_segment + 1;
	TRACE_EXIT 0;
}

/*  perform mtfsf, mtbsf, not allowed without zft_qic_mode
 */
int zft_skip_volumes(int count, zft_position *pos)
{ 
	const zft_volinfo *vtbl;
	TRACE_FUN(ft_t_flow);
	
	TRACE(ft_t_noise, "count: %d", count);
	
	vtbl= zft_find_volume(pos->seg_pos);
	while (count > 0 && vtbl != zft_eom_vtbl) {
		vtbl = list_entry(vtbl->node.next, zft_volinfo, node);
		count --;
	}
	while (count < 0 && vtbl != zft_first_vtbl) {
		vtbl = list_entry(vtbl->node.prev, zft_volinfo, node);
		count ++;
	}
	pos->seg_pos        = vtbl->start_seg;
	pos->seg_byte_pos   = 0;
	pos->volume_pos     = 0;
	pos->tape_pos       = zft_calc_tape_pos(pos->seg_pos);
	zft_just_before_eof = vtbl->size == 0;
	if (zft_cmpr_ops) {
		(*zft_cmpr_ops->reset)();
	}
	zft_deblock_segment = -1; /* no need to keep cache */
	TRACE(ft_t_noise, "repositioning to:\n"
	      KERN_INFO "zft_seg_pos        : %d\n"
	      KERN_INFO "zft_seg_byte_pos   : %d\n"
	      KERN_INFO "zft_tape_pos       : " LL_X "\n"
	      KERN_INFO "zft_volume_pos     : " LL_X "\n"
	      KERN_INFO "file number        : %d",
	      pos->seg_pos, pos->seg_byte_pos, 
	      LL(pos->tape_pos), LL(pos->volume_pos), vtbl->count);
	zft_resid = count < 0 ? -count : count;
	TRACE_EXIT zft_resid ? -EINVAL : 0;
}

/* the following simply returns the raw data position of the EOM
 * marker, MTIOCSIZE ioctl 
 */
__s64 zft_get_eom_pos(void)
{
	if (zft_qic_mode) {
		return zft_calc_tape_pos(zft_eom_vtbl->start_seg);
	} else {
		/* there is only one volume in raw mode */
		return zft_capacity;
	}
}

/* skip to eom, used for MTEOM
 */
void zft_skip_to_eom(zft_position *pos)
{
	TRACE_FUN(ft_t_flow);
	pos->seg_pos      = zft_eom_vtbl->start_seg;
	pos->seg_byte_pos = 
		pos->volume_pos     = 
		zft_just_before_eof = 0;
	pos->tape_pos = zft_calc_tape_pos(pos->seg_pos);
	TRACE(ft_t_noise, "ftape positioned to segment %d, data pos " LL_X, 
	      pos->seg_pos, LL(pos->tape_pos));
	TRACE_EXIT;
}

/*  write an EOF-marker by setting zft_last_vtbl->end_seg to seg_pos.
 *  NOTE: this function assumes that zft_last_vtbl points to a valid
 *  vtbl entry
 *
 *  NOTE: this routine always positions before the EOF marker
 */
int zft_close_volume(zft_position *pos)
{
	TRACE_FUN(ft_t_any);

	if (zft_vtbl_empty || !zft_last_vtbl->open) { /* should not happen */
		TRACE(ft_t_noise, "There are no volumes to finish");
		TRACE_EXIT -EIO;
	}
	if (pos->seg_byte_pos == 0 && 
	    pos->seg_pos != zft_last_vtbl->start_seg) {
		pos->seg_pos --;
		pos->seg_byte_pos      = zft_get_seg_sz(pos->seg_pos);
	}
	zft_last_vtbl->end_seg   = pos->seg_pos;
	zft_last_vtbl->size      = pos->volume_pos;
	zft_volume_table_changed = 1;
	zft_just_before_eof      = 1;
	zft_eom_vtbl->start_seg  = zft_last_vtbl->end_seg + 1;
	zft_last_vtbl->open      = 0; /* closed */
	TRACE_EXIT 0;
}

/* write count file-marks at current position. 
 *
 *  The tape is positioned after the eof-marker, that is at byte 0 of
 *  the segment following the eof-marker
 *
 *  this function is only allowed in zft_qic_mode
 *
 *  Only allowed when tape is at BOT or EOD.
 */
int zft_weof(unsigned int count, zft_position *pos)
{
	
	TRACE_FUN(ft_t_flow);

	if (!count) { /* write zero EOF marks should be a real no-op */
		TRACE_EXIT 0;
	}
	zft_volume_table_changed = 1;
	if (zft_tape_at_lbot(pos)) {
		zft_init_vtbl();
		if(zft_old_ftape) {
			/* clear old ftape's eof marks */
			zft_clear_ftape_file_marks();
			zft_old_ftape = 0;    /* no longer old ftape */
		}
	}
	if (zft_last_vtbl->open) {
		zft_close_volume(pos);
		zft_move_past_eof(pos);
		count --;
	}
	/* now it's easy, just append eof-marks, that is empty
	 * volumes, to the end of the already recorded media.
	 */
	while (count > 0 && 
	       pos->seg_pos <= ft_last_data_segment && 
	       zft_eom_vtbl->count < ZFT_MAX_VOLUMES) {
		TRACE(ft_t_noise,
		      "Writing zero sized file at segment %d", pos->seg_pos);
		zft_new_vtbl_entry();
		zft_last_vtbl->start_seg       = pos->seg_pos;
		zft_last_vtbl->end_seg         = pos->seg_pos;
		zft_last_vtbl->size            = 0;
		zft_last_vtbl->blk_sz          = zft_blk_sz;
		zft_last_vtbl->zft_volume      = 1;
		zft_last_vtbl->use_compression = 0;
		pos->tape_pos += zft_get_seg_sz(pos->seg_pos);
		zft_eom_vtbl->start_seg = ++ pos->seg_pos;
		count --;
	} 
	if (count > 0) {
		/*  there are two possibilities: end of tape, or the
		 *  maximum number of files is exhausted.
		 */
		zft_resid = count;
		TRACE(ft_t_noise,"Number of marks NOT written: %d", zft_resid);
		if (zft_eom_vtbl->count == ZFT_MAX_VOLUMES) {
			TRACE_ABORT(-EINVAL, ft_t_warn,
				    "maximum allowed number of files "
				    "exhausted: %d", ZFT_MAX_VOLUMES);
		} else {
			TRACE_ABORT(-ENOSPC,
				    ft_t_noise, "reached end of tape");
		}
	}
	TRACE_EXIT 0;
}

const zft_volinfo *zft_find_volume(unsigned int seg_pos)
{
	TRACE_FUN(ft_t_flow);
	
	TRACE(ft_t_any, "called with seg_pos %d",seg_pos);
	if (!zft_qic_mode) {
		if (seg_pos > ft_last_data_segment) {
			TRACE_EXIT &eot_vtbl;
		}
		tape_vtbl.blk_sz =  zft_blk_sz;
		TRACE_EXIT &tape_vtbl;
	}
	if (seg_pos < zft_first_vtbl->start_seg) {
		TRACE_EXIT (cur_vtbl = zft_first_vtbl);
	}
	while (seg_pos > cur_vtbl->end_seg) {
		cur_vtbl = list_entry(cur_vtbl->node.next, zft_volinfo, node);
		TRACE(ft_t_noise, "%d - %d", cur_vtbl->start_seg, cur_vtbl->end_seg);
	}
	while (seg_pos < cur_vtbl->start_seg) {
		cur_vtbl = list_entry(cur_vtbl->node.prev, zft_volinfo, node);
		TRACE(ft_t_noise, "%d - %d", cur_vtbl->start_seg, cur_vtbl->end_seg);
	}
	if (seg_pos > cur_vtbl->end_seg || seg_pos < cur_vtbl->start_seg) {
		TRACE(ft_t_bug, "This cannot happen");
	}
	DUMP_VOLINFO(ft_t_noise, "", cur_vtbl);
	TRACE_EXIT cur_vtbl;
}

/* this function really assumes that we are just before eof
 */
void zft_move_past_eof(zft_position *pos)
{ 
	TRACE_FUN(ft_t_flow);

	TRACE(ft_t_noise, "old seg. pos: %d", pos->seg_pos);
	pos->tape_pos += zft_get_seg_sz(pos->seg_pos++) - pos->seg_byte_pos;
	pos->seg_byte_pos = 0;
	pos->volume_pos   = 0;
	if (zft_cmpr_ops) {
		(*zft_cmpr_ops->reset)();
	}
	zft_just_before_eof =  0;
	zft_deblock_segment = -1; /* no need to cache it anymore */
	TRACE(ft_t_noise, "new seg. pos: %d", pos->seg_pos);
	TRACE_EXIT;
}