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Linux-2.6.12-rc2
[linux-2.6/next.git] / drivers / char / ftape / compressor / zftape-compress.c
blob220a227e606113c8aa4ccd33b2e666daba5d6f03
1 /*
2 * Copyright (C) 1994-1997 Claus-Justus Heine
3
4 This program is free software; you can redistribute it and/or
5 modify it under the terms of the GNU General Public License as
6 published by the Free Software Foundation; either version 2, or (at
7 your option) any later version.
8
9 This program is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; see the file COPYING. If not, write to
16 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
17 USA.
18
19 *
20 * This file implements a "generic" interface between the *
21 * zftape-driver and a compression-algorithm. The *
22 * compression-algorithm currently used is a LZ77. I use the *
23 * implementation lzrw3 by Ross N. Williams (Renaissance *
24 * Software). The compression program itself is in the file
25 * lzrw3.c * and lzrw3.h. To adopt another compression algorithm
26 * the functions * zft_compress() and zft_uncompress() must be
27 * changed * appropriately. See below.
28 */
29
30 #include <linux/errno.h>
31 #include <linux/mm.h>
32 #include <linux/module.h>
33
34 #include <linux/zftape.h>
35
36 #include <asm/uaccess.h>
37
38 #include "../zftape/zftape-init.h"
39 #include "../zftape/zftape-eof.h"
40 #include "../zftape/zftape-ctl.h"
41 #include "../zftape/zftape-write.h"
42 #include "../zftape/zftape-read.h"
43 #include "../zftape/zftape-rw.h"
44 #include "../compressor/zftape-compress.h"
45 #include "../zftape/zftape-vtbl.h"
46 #include "../compressor/lzrw3.h"
47
48 /*
49 * global variables
50 */
51
52 /* I handle the allocation of this buffer as a special case, because
53 * it's size varies depending on the tape length inserted.
54 */
55
56 /* local variables
57 */
58 static void *zftc_wrk_mem = NULL;
59 static __u8 *zftc_buf = NULL;
60 static void *zftc_scratch_buf = NULL;
61
62 /* compression statistics
63 */
64 static unsigned int zftc_wr_uncompressed = 0;
65 static unsigned int zftc_wr_compressed = 0;
66 static unsigned int zftc_rd_uncompressed = 0;
67 static unsigned int zftc_rd_compressed = 0;
68
69 /* forward */
70 static int zftc_write(int *write_cnt,
71 __u8 *dst_buf, const int seg_sz,
72 const __u8 __user *src_buf, const int req_len,
73 const zft_position *pos, const zft_volinfo *volume);
74 static int zftc_read(int *read_cnt,
75 __u8 __user *dst_buf, const int to_do,
76 const __u8 *src_buf, const int seg_sz,
77 const zft_position *pos, const zft_volinfo *volume);
78 static int zftc_seek(unsigned int new_block_pos,
79 zft_position *pos, const zft_volinfo *volume,
80 __u8 *buffer);
81 static void zftc_lock (void);
82 static void zftc_reset (void);
83 static void zftc_cleanup(void);
84 static void zftc_stats (void);
85
86 /* compressed segment. This conforms to QIC-80-MC, Revision K.
87 *
88 * Rev. K applies to tapes with `fixed length format' which is
89 * indicated by format code 2,3 and 5. See below for format code 4 and 6
90 *
91 * 2 bytes: offset of compression segment structure
92 * 29k > offset >= 29k-18: data from previous segment ens in this
93 * segment and no compressed block starts
94 * in this segment
95 * offset == 0: data from previous segment occupies entire
96 * segment and continues in next segment
97 * n bytes: remainder from previous segment
98 *
99 * Rev. K:
100 * 4 bytes: 4 bytes: files set byte offset
101 * Post Rev. K and QIC-3020/3020:
102 * 8 bytes: 8 bytes: files set byte offset
103 * 2 bytes: byte count N (amount of data following)
104 * bit 15 is set if data is compressed, bit 15 is not
105 * set if data is uncompressed
106 * N bytes: data (as much as specified in the byte count)
107 * 2 bytes: byte count N_1 of next cluster
108 * N_1 bytes: data of next cluset
109 * 2 bytes: byte count N_2 of next cluster
110 * N_2 bytes: ...
111 *
112 * Note that the `N' byte count accounts only for the bytes that in the
113 * current segment if the cluster spans to the next segment.
114 */
115
116 typedef struct
117 {
118 int cmpr_pos; /* actual position in compression buffer */
119 int cmpr_sz; /* what is left in the compression buffer
120 * when copying the compressed data to the
121 * deblock buffer
122 */
123 unsigned int first_block; /* location of header information in
124 * this segment
125 */
126 unsigned int count; /* amount of data of current block
127 * contained in current segment
128 */
129 unsigned int offset; /* offset in current segment */
130 unsigned int spans:1; /* might continue in next segment */
131 unsigned int uncmpr; /* 0x8000 if this block contains
132 * uncompressed data
133 */
134 __s64 foffs; /* file set byte offset, same as in
135 * compression map segment
136 */
137 } cmpr_info;
138
139 static cmpr_info cseg; /* static data. Must be kept uptodate and shared by
140 * read, write and seek functions
141 */
142
143 #define DUMP_CMPR_INFO(level, msg, info) \
144 TRACE(level, msg "\n" \
145 KERN_INFO "cmpr_pos : %d\n" \
146 KERN_INFO "cmpr_sz : %d\n" \
147 KERN_INFO "first_block: %d\n" \
148 KERN_INFO "count : %d\n" \
149 KERN_INFO "offset : %d\n" \
150 KERN_INFO "spans : %d\n" \
151 KERN_INFO "uncmpr : 0x%04x\n" \
152 KERN_INFO "foffs : " LL_X, \
153 (info)->cmpr_pos, (info)->cmpr_sz, (info)->first_block, \
154 (info)->count, (info)->offset, (info)->spans == 1, \
155 (info)->uncmpr, LL((info)->foffs))
156
157 /* dispatch compression segment info, return error code
158 *
159 * afterwards, cseg->offset points to start of data of the NEXT
160 * compressed block, and cseg->count contains the amount of data
161 * left in the actual compressed block. cseg->spans is set to 1 if
162 * the block is continued in the following segment. Otherwise it is
163 * set to 0.
164 */
165 static int get_cseg (cmpr_info *cinfo, const __u8 *buff,
166 const unsigned int seg_sz,
167 const zft_volinfo *volume)
168 {
169 TRACE_FUN(ft_t_flow);
170
171 cinfo->first_block = GET2(buff, 0);
172 if (cinfo->first_block == 0) { /* data spans to next segment */
173 cinfo->count = seg_sz - sizeof(__u16);
174 cinfo->offset = seg_sz;
175 cinfo->spans = 1;
176 } else { /* cluster definetely ends in this segment */
177 if (cinfo->first_block > seg_sz) {
178 /* data corrupted */
179 TRACE_ABORT(-EIO, ft_t_err, "corrupted data:\n"
180 KERN_INFO "segment size: %d\n"
181 KERN_INFO "first block : %d",
182 seg_sz, cinfo->first_block);
183 }
184 cinfo->count = cinfo->first_block - sizeof(__u16);
185 cinfo->offset = cinfo->first_block;
186 cinfo->spans = 0;
187 }
188 /* now get the offset the first block should have in the
189 * uncompressed data stream.
190 *
191 * For this magic `18' refer to CRF-3 standard or QIC-80MC,
192 * Rev. K.
193 */
194 if ((seg_sz - cinfo->offset) > 18) {
195 if (volume->qic113) { /* > revision K */
196 TRACE(ft_t_data_flow, "New QIC-113 compliance");
197 cinfo->foffs = GET8(buff, cinfo->offset);
198 cinfo->offset += sizeof(__s64);
199 } else {
200 TRACE(/* ft_t_data_flow */ ft_t_noise, "pre QIC-113 version");
201 cinfo->foffs = (__s64)GET4(buff, cinfo->offset);
202 cinfo->offset += sizeof(__u32);
203 }
204 }
205 if (cinfo->foffs > volume->size) {
206 TRACE_ABORT(-EIO, ft_t_err, "Inconsistency:\n"
207 KERN_INFO "offset in current volume: %d\n"
208 KERN_INFO "size of current volume : %d",
209 (int)(cinfo->foffs>>10), (int)(volume->size>>10));
210 }
211 if (cinfo->cmpr_pos + cinfo->count > volume->blk_sz) {
212 TRACE_ABORT(-EIO, ft_t_err, "Inconsistency:\n"
213 KERN_INFO "block size : %d\n"
214 KERN_INFO "data record: %d",
215 volume->blk_sz, cinfo->cmpr_pos + cinfo->count);
216 }
217 DUMP_CMPR_INFO(ft_t_noise /* ft_t_any */, "", cinfo);
218 TRACE_EXIT 0;
219 }
220
221 /* This one is called, when a new cluster starts in same segment.
222 *
223 * Note: if this is the first cluster in the current segment, we must
224 * not check whether there are more than 18 bytes available because
225 * this have already been done in get_cseg() and there may be less
226 * than 18 bytes available due to header information.
227 *
228 */
229 static void get_next_cluster(cmpr_info *cluster, const __u8 *buff,
230 const int seg_sz, const int finish)
231 {
232 TRACE_FUN(ft_t_flow);
233
234 if (seg_sz - cluster->offset > 18 || cluster->foffs != 0) {
235 cluster->count = GET2(buff, cluster->offset);
236 cluster->uncmpr = cluster->count & 0x8000;
237 cluster->count -= cluster->uncmpr;
238 cluster->offset += sizeof(__u16);
239 cluster->foffs = 0;
240 if ((cluster->offset + cluster->count) < seg_sz) {
241 cluster->spans = 0;
242 } else if (cluster->offset + cluster->count == seg_sz) {
243 cluster->spans = !finish;
244 } else {
245 /* either an error or a volume written by an
246 * old version. If this is a data error, then we'll
247 * catch it later.
248 */
249 TRACE(ft_t_data_flow, "Either error or old volume");
250 cluster->spans = 1;
251 cluster->count = seg_sz - cluster->offset;
252 }
253 } else {
254 cluster->count = 0;
255 cluster->spans = 0;
256 cluster->foffs = 0;
257 }
258 DUMP_CMPR_INFO(ft_t_noise /* ft_t_any */ , "", cluster);
259 TRACE_EXIT;
260 }
261
262 static void zftc_lock(void)
263 {
264 }
265
266 /* this function is needed for zftape_reset_position in zftape-io.c
267 */
268 static void zftc_reset(void)
269 {
270 TRACE_FUN(ft_t_flow);
271
272 memset((void *)&cseg, '\0', sizeof(cseg));
273 zftc_stats();
274 TRACE_EXIT;
275 }
276
277 static int cmpr_mem_initialized = 0;
278 static unsigned int alloc_blksz = 0;
279
280 static int zft_allocate_cmpr_mem(unsigned int blksz)
281 {
282 TRACE_FUN(ft_t_flow);
283
284 if (cmpr_mem_initialized && blksz == alloc_blksz) {
285 TRACE_EXIT 0;
286 }
287 TRACE_CATCH(zft_vmalloc_once(&zftc_wrk_mem, CMPR_WRK_MEM_SIZE),
288 zftc_cleanup());
289 TRACE_CATCH(zft_vmalloc_always(&zftc_buf, blksz + CMPR_OVERRUN),
290 zftc_cleanup());
291 alloc_blksz = blksz;
292 TRACE_CATCH(zft_vmalloc_always(&zftc_scratch_buf, blksz+CMPR_OVERRUN),
293 zftc_cleanup());
294 cmpr_mem_initialized = 1;
295 TRACE_EXIT 0;
296 }
297
298 static void zftc_cleanup(void)
299 {
300 TRACE_FUN(ft_t_flow);
301
302 zft_vfree(&zftc_wrk_mem, CMPR_WRK_MEM_SIZE);
303 zft_vfree(&zftc_buf, alloc_blksz + CMPR_OVERRUN);
304 zft_vfree(&zftc_scratch_buf, alloc_blksz + CMPR_OVERRUN);
305 cmpr_mem_initialized = alloc_blksz = 0;
306 TRACE_EXIT;
307 }
308
309 /*****************************************************************************
310 * *
311 * The following two functions "ftape_compress()" and *
312 * "ftape_uncompress()" are the interface to the actual compression *
313 * algorithm (i.e. they are calling the "compress()" function from *
314 * the lzrw3 package for now). These routines could quite easily be *
315 * changed to adopt another compression algorithm instead of lzrw3, *
316 * which currently is used. *
317 * *
318 *****************************************************************************/
319
320 /* called by zft_compress_write() to perform the compression. Must
321 * return the size of the compressed data.
322 *
323 * NOTE: The size of the compressed data should not exceed the size of
324 * the uncompressed data. Most compression algorithms have means
325 * to store data unchanged if the "compressed" data amount would
326 * exceed the original one. Mostly this is done by storing some
327 * flag-bytes in front of the compressed data to indicate if it
328 * is compressed or not. Thus the worst compression result
329 * length is the original length plus those flag-bytes.
330 *
331 * We don't want that, as the QIC-80 standard provides a means
332 * of marking uncompressed blocks by simply setting bit 15 of
333 * the compressed block's length. Thus a compessed block can
334 * have at most a length of 2^15-1 bytes. The QIC-80 standard
335 * restricts the block-length even further, allowing only 29k -
336 * 6 bytes.
337 *
338 * Currently, the maximum blocksize used by zftape is 28k.
339 *
340 * In short: don't exceed the length of the input-package, set
341 * bit 15 of the compressed size to 1 if you have copied data
342 * instead of compressing it.
343 */
344 static int zft_compress(__u8 *in_buffer, unsigned int in_sz, __u8 *out_buffer)
345 {
346 __s32 compressed_sz;
347 TRACE_FUN(ft_t_flow);
348
349
350 lzrw3_compress(COMPRESS_ACTION_COMPRESS, zftc_wrk_mem,
351 in_buffer, in_sz, out_buffer, &compressed_sz);
352 if (TRACE_LEVEL >= ft_t_info) {
353 /* the compiler will optimize this away when
354 * compiled with NO_TRACE_AT_ALL option
355 */
356 TRACE(ft_t_data_flow, "\n"
357 KERN_INFO "before compression: %d bytes\n"
358 KERN_INFO "after compresison : %d bytes",
359 in_sz,
360 (int)(compressed_sz < 0
361 ? -compressed_sz : compressed_sz));
362 /* for statistical purposes
363 */
364 zftc_wr_compressed += (compressed_sz < 0
365 ? -compressed_sz : compressed_sz);
366 zftc_wr_uncompressed += in_sz;
367 }
368 TRACE_EXIT (int)compressed_sz;
369 }
370
371 /* called by zft_compress_read() to decompress the data. Must
372 * return the size of the decompressed data for sanity checks
373 * (compared with zft_blk_sz)
374 *
375 * NOTE: Read the note for zft_compress() above! If bit 15 of the
376 * parameter in_sz is set, then the data in in_buffer isn't
377 * compressed, which must be handled by the un-compression
378 * algorithm. (I changed lzrw3 to handle this.)
379 *
380 * The parameter max_out_sz is needed to prevent buffer overruns when
381 * uncompressing corrupt data.
382 */
383 static unsigned int zft_uncompress(__u8 *in_buffer,
384 int in_sz,
385 __u8 *out_buffer,
386 unsigned int max_out_sz)
387 {
388 TRACE_FUN(ft_t_flow);
389
390 lzrw3_compress(COMPRESS_ACTION_DECOMPRESS, zftc_wrk_mem,
391 in_buffer, (__s32)in_sz,
392 out_buffer, (__u32 *)&max_out_sz);
393
394 if (TRACE_LEVEL >= ft_t_info) {
395 TRACE(ft_t_data_flow, "\n"
396 KERN_INFO "before decompression: %d bytes\n"
397 KERN_INFO "after decompression : %d bytes",
398 in_sz < 0 ? -in_sz : in_sz,(int)max_out_sz);
399 /* for statistical purposes
400 */
401 zftc_rd_compressed += in_sz < 0 ? -in_sz : in_sz;
402 zftc_rd_uncompressed += max_out_sz;
403 }
404 TRACE_EXIT (unsigned int)max_out_sz;
405 }
406
407 /* print some statistics about the efficiency of the compression to
408 * the kernel log
409 */
410 static void zftc_stats(void)
411 {
412 TRACE_FUN(ft_t_flow);
413
414 if (TRACE_LEVEL < ft_t_info) {
415 TRACE_EXIT;
416 }
417 if (zftc_wr_uncompressed != 0) {
418 if (zftc_wr_compressed > (1<<14)) {
419 TRACE(ft_t_info, "compression statistics (writing):\n"
420 KERN_INFO " compr./uncmpr. : %3d %%",
421 (((zftc_wr_compressed>>10) * 100)
422 / (zftc_wr_uncompressed>>10)));
423 } else {
424 TRACE(ft_t_info, "compression statistics (writing):\n"
425 KERN_INFO " compr./uncmpr. : %3d %%",
426 ((zftc_wr_compressed * 100)
427 / zftc_wr_uncompressed));
428 }
429 }
430 if (zftc_rd_uncompressed != 0) {
431 if (zftc_rd_compressed > (1<<14)) {
432 TRACE(ft_t_info, "compression statistics (reading):\n"
433 KERN_INFO " compr./uncmpr. : %3d %%",
434 (((zftc_rd_compressed>>10) * 100)
435 / (zftc_rd_uncompressed>>10)));
436 } else {
437 TRACE(ft_t_info, "compression statistics (reading):\n"
438 KERN_INFO " compr./uncmpr. : %3d %%",
439 ((zftc_rd_compressed * 100)
440 / zftc_rd_uncompressed));
441 }
442 }
443 /* only print it once: */
444 zftc_wr_uncompressed =
445 zftc_wr_compressed =
446 zftc_rd_uncompressed =
447 zftc_rd_compressed = 0;
448 TRACE_EXIT;
449 }
450
451 /* start new compressed block
452 */
453 static int start_new_cseg(cmpr_info *cluster,
454 char *dst_buf,
455 const zft_position *pos,
456 const unsigned int blk_sz,
457 const char *src_buf,
458 const int this_segs_sz,
459 const int qic113)
460 {
461 int size_left;
462 int cp_cnt;
463 int buf_pos;
464 TRACE_FUN(ft_t_flow);
465
466 size_left = this_segs_sz - sizeof(__u16) - cluster->cmpr_sz;
467 TRACE(ft_t_data_flow,"\n"
468 KERN_INFO "segment size : %d\n"
469 KERN_INFO "compressed_sz: %d\n"
470 KERN_INFO "size_left : %d",
471 this_segs_sz, cluster->cmpr_sz, size_left);
472 if (size_left > 18) { /* start a new cluseter */
473 cp_cnt = cluster->cmpr_sz;
474 cluster->cmpr_sz = 0;
475 buf_pos = cp_cnt + sizeof(__u16);
476 PUT2(dst_buf, 0, buf_pos);
477
478 if (qic113) {
479 __s64 foffs = pos->volume_pos;
480 if (cp_cnt) foffs += (__s64)blk_sz;
481
482 TRACE(ft_t_data_flow, "new style QIC-113 header");
483 PUT8(dst_buf, buf_pos, foffs);
484 buf_pos += sizeof(__s64);
485 } else {
486 __u32 foffs = (__u32)pos->volume_pos;
487 if (cp_cnt) foffs += (__u32)blk_sz;
488
489 TRACE(ft_t_data_flow, "old style QIC-80MC header");
490 PUT4(dst_buf, buf_pos, foffs);
491 buf_pos += sizeof(__u32);
492 }
493 } else if (size_left >= 0) {
494 cp_cnt = cluster->cmpr_sz;
495 cluster->cmpr_sz = 0;
496 buf_pos = cp_cnt + sizeof(__u16);
497 PUT2(dst_buf, 0, buf_pos);
498 /* zero unused part of segment. */
499 memset(dst_buf + buf_pos, '\0', size_left);
500 buf_pos = this_segs_sz;
501 } else { /* need entire segment and more space */
502 PUT2(dst_buf, 0, 0);
503 cp_cnt = this_segs_sz - sizeof(__u16);
504 cluster->cmpr_sz -= cp_cnt;
505 buf_pos = this_segs_sz;
506 }
507 memcpy(dst_buf + sizeof(__u16), src_buf + cluster->cmpr_pos, cp_cnt);
508 cluster->cmpr_pos += cp_cnt;
509 TRACE_EXIT buf_pos;
510 }
511
512 /* return-value: the number of bytes removed from the user-buffer
513 * `src_buf' or error code
514 *
515 * int *write_cnt : how much actually has been moved to the
516 * dst_buf. Need not be initialized when
517 * function returns with an error code
518 * (negativ return value)
519 * __u8 *dst_buf : kernel space buffer where the has to be
520 * copied to. The contents of this buffers
521 * goes to a specific segment.
522 * const int seg_sz : the size of the segment dst_buf will be
523 * copied to.
524 * const zft_position *pos : struct containing the coordinates in
525 * the current volume (byte position,
526 * segment id of current segment etc)
527 * const zft_volinfo *volume: information about the current volume,
528 * size etc.
529 * const __u8 *src_buf : user space buffer that contains the
530 * data the user wants to be written to
531 * tape.
532 * const int req_len : the amount of data the user wants to be
533 * written to tape.
534 */
535 static int zftc_write(int *write_cnt,
536 __u8 *dst_buf, const int seg_sz,
537 const __u8 __user *src_buf, const int req_len,
538 const zft_position *pos, const zft_volinfo *volume)
539 {
540 int req_len_left = req_len;
541 int result;
542 int len_left;
543 int buf_pos_write = pos->seg_byte_pos;
544 TRACE_FUN(ft_t_flow);
545
546 /* Note: we do not unlock the module because
547 * there are some values cached in that `cseg' variable. We
548 * don't don't want to use this information when being
549 * unloaded by kerneld even when the tape is full or when we
550 * cannot allocate enough memory.
551 */
552 if (pos->tape_pos > (volume->size-volume->blk_sz-ZFT_CMPR_OVERHEAD)) {
553 TRACE_EXIT -ENOSPC;
554 }
555 if (zft_allocate_cmpr_mem(volume->blk_sz) < 0) {
556 /* should we unlock the module? But it shouldn't
557 * be locked anyway ...
558 */
559 TRACE_EXIT -ENOMEM;
560 }
561 if (buf_pos_write == 0) { /* fill a new segment */
562 *write_cnt = buf_pos_write = start_new_cseg(&cseg,
563 dst_buf,
564 pos,
565 volume->blk_sz,
566 zftc_buf,
567 seg_sz,
568 volume->qic113);
569 if (cseg.cmpr_sz == 0 && cseg.cmpr_pos != 0) {
570 req_len_left -= result = volume->blk_sz;
571 cseg.cmpr_pos = 0;
572 } else {
573 result = 0;
574 }
575 } else {
576 *write_cnt = result = 0;
577 }
578
579 len_left = seg_sz - buf_pos_write;
580 while ((req_len_left > 0) && (len_left > 18)) {
581 /* now we have some size left for a new compressed
582 * block. We know, that the compression buffer is
583 * empty (else there wouldn't be any space left).
584 */
585 if (copy_from_user(zftc_scratch_buf, src_buf + result,
586 volume->blk_sz) != 0) {
587 TRACE_EXIT -EFAULT;
588 }
589 req_len_left -= volume->blk_sz;
590 cseg.cmpr_sz = zft_compress(zftc_scratch_buf, volume->blk_sz,
591 zftc_buf);
592 if (cseg.cmpr_sz < 0) {
593 cseg.uncmpr = 0x8000;
594 cseg.cmpr_sz = -cseg.cmpr_sz;
595 } else {
596 cseg.uncmpr = 0;
597 }
598 /* increment "result" iff we copied the entire
599 * compressed block to the zft_deblock_buf
600 */
601 len_left -= sizeof(__u16);
602 if (len_left >= cseg.cmpr_sz) {
603 len_left -= cseg.count = cseg.cmpr_sz;
604 cseg.cmpr_pos = cseg.cmpr_sz = 0;
605 result += volume->blk_sz;
606 } else {
607 cseg.cmpr_sz -=
608 cseg.cmpr_pos =
609 cseg.count = len_left;
610 len_left = 0;
611 }
612 PUT2(dst_buf, buf_pos_write, cseg.uncmpr | cseg.count);
613 buf_pos_write += sizeof(__u16);
614 memcpy(dst_buf + buf_pos_write, zftc_buf, cseg.count);
615 buf_pos_write += cseg.count;
616 *write_cnt += cseg.count + sizeof(__u16);
617 FT_SIGNAL_EXIT(_DONT_BLOCK);
618 }
619 /* erase the remainder of the segment if less than 18 bytes
620 * left (18 bytes is due to the QIC-80 standard)
621 */
622 if (len_left <= 18) {
623 memset(dst_buf + buf_pos_write, '\0', len_left);
624 (*write_cnt) += len_left;
625 }
626 TRACE(ft_t_data_flow, "returning %d", result);
627 TRACE_EXIT result;
628 }
629
630 /* out:
631 *
632 * int *read_cnt: the number of bytes we removed from the zft_deblock_buf
633 * (result)
634 * int *to_do : the remaining size of the read-request.
635 *
636 * in:
637 *
638 * char *buff : buff is the address of the upper part of the user
639 * buffer, that hasn't been filled with data yet.
640
641 * int buf_pos_read : copy of from _ftape_read()
642 * int buf_len_read : copy of buf_len_rd from _ftape_read()
643 * char *zft_deblock_buf: zft_deblock_buf
644 * unsigned short blk_sz: the block size valid for this volume, may differ
645 * from zft_blk_sz.
646 * int finish: if != 0 means that this is the last segment belonging
647 * to this volume
648 * returns the amount of data actually copied to the user-buffer
649 *
650 * to_do MUST NOT SHRINK except to indicate an EOF. In this case *to_do has to
651 * be set to 0
652 */
653 static int zftc_read (int *read_cnt,
654 __u8 __user *dst_buf, const int to_do,
655 const __u8 *src_buf, const int seg_sz,
656 const zft_position *pos, const zft_volinfo *volume)
657 {
658 int uncompressed_sz;
659 int result = 0;
660 int remaining = to_do;
661 TRACE_FUN(ft_t_flow);
662
663 TRACE_CATCH(zft_allocate_cmpr_mem(volume->blk_sz),);
664 if (pos->seg_byte_pos == 0) {
665 /* new segment just read
666 */
667 TRACE_CATCH(get_cseg(&cseg, src_buf, seg_sz, volume),
668 *read_cnt = 0);
669 memcpy(zftc_buf + cseg.cmpr_pos, src_buf + sizeof(__u16),
670 cseg.count);
671 cseg.cmpr_pos += cseg.count;
672 *read_cnt = cseg.offset;
673 DUMP_CMPR_INFO(ft_t_noise /* ft_t_any */, "", &cseg);
674 } else {
675 *read_cnt = 0;
676 }
677 /* loop and uncompress until user buffer full or
678 * deblock-buffer empty
679 */
680 TRACE(ft_t_data_flow, "compressed_sz: %d, compos : %d, *read_cnt: %d",
681 cseg.cmpr_sz, cseg.cmpr_pos, *read_cnt);
682 while ((cseg.spans == 0) && (remaining > 0)) {
683 if (cseg.cmpr_pos != 0) { /* cmpr buf is not empty */
684 uncompressed_sz =
685 zft_uncompress(zftc_buf,
686 cseg.uncmpr == 0x8000 ?
687 -cseg.cmpr_pos : cseg.cmpr_pos,
688 zftc_scratch_buf,
689 volume->blk_sz);
690 if (uncompressed_sz != volume->blk_sz) {
691 *read_cnt = 0;
692 TRACE_ABORT(-EIO, ft_t_warn,
693 "Uncompressed blk (%d) != blk size (%d)",
694 uncompressed_sz, volume->blk_sz);
695 }
696 if (copy_to_user(dst_buf + result,
697 zftc_scratch_buf,
698 uncompressed_sz) != 0 ) {
699 TRACE_EXIT -EFAULT;
700 }
701 remaining -= uncompressed_sz;
702 result += uncompressed_sz;
703 cseg.cmpr_pos = 0;
704 }
705 if (remaining > 0) {
706 get_next_cluster(&cseg, src_buf, seg_sz,
707 volume->end_seg == pos->seg_pos);
708 if (cseg.count != 0) {
709 memcpy(zftc_buf, src_buf + cseg.offset,
710 cseg.count);
711 cseg.cmpr_pos = cseg.count;
712 cseg.offset += cseg.count;
713 *read_cnt += cseg.count + sizeof(__u16);
714 } else {
715 remaining = 0;
716 }
717 }
718 TRACE(ft_t_data_flow, "\n"
719 KERN_INFO "compressed_sz: %d\n"
720 KERN_INFO "compos : %d\n"
721 KERN_INFO "*read_cnt : %d",
722 cseg.cmpr_sz, cseg.cmpr_pos, *read_cnt);
723 }
724 if (seg_sz - cseg.offset <= 18) {
725 *read_cnt += seg_sz - cseg.offset;
726 TRACE(ft_t_data_flow, "expanding read cnt to: %d", *read_cnt);
727 }
728 TRACE(ft_t_data_flow, "\n"
729 KERN_INFO "segment size : %d\n"
730 KERN_INFO "read count : %d\n"
731 KERN_INFO "buf_pos_read : %d\n"
732 KERN_INFO "remaining : %d",
733 seg_sz, *read_cnt, pos->seg_byte_pos,
734 seg_sz - *read_cnt - pos->seg_byte_pos);
735 TRACE(ft_t_data_flow, "returning: %d", result);
736 TRACE_EXIT result;
737 }
738
739 /* seeks to the new data-position. Reads sometimes a segment.
740 *
741 * start_seg and end_seg give the boundaries of the current volume
742 * blk_sz is the blk_sz of the current volume as stored in the
743 * volume label
744 *
745 * We don't allow blocksizes less than 1024 bytes, therefore we don't need
746 * a 64 bit argument for new_block_pos.
747 */
748
749 static int seek_in_segment(const unsigned int to_do, cmpr_info *c_info,
750 const char *src_buf, const int seg_sz,
751 const int seg_pos, const zft_volinfo *volume);
752 static int slow_seek_forward_until_error(const unsigned int distance,
753 cmpr_info *c_info, zft_position *pos,
754 const zft_volinfo *volume, __u8 *buf);
755 static int search_valid_segment(unsigned int segment,
756 const unsigned int end_seg,
757 const unsigned int max_foffs,
758 zft_position *pos, cmpr_info *c_info,
759 const zft_volinfo *volume, __u8 *buf);
760 static int slow_seek_forward(unsigned int dest, cmpr_info *c_info,
761 zft_position *pos, const zft_volinfo *volume,
762 __u8 *buf);
763 static int compute_seg_pos(unsigned int dest, zft_position *pos,
764 const zft_volinfo *volume);
765
766 #define ZFT_SLOW_SEEK_THRESHOLD 10 /* segments */
767 #define ZFT_FAST_SEEK_MAX_TRIALS 10 /* times */
768 #define ZFT_FAST_SEEK_BACKUP 10 /* segments */
769
770 static int zftc_seek(unsigned int new_block_pos,
771 zft_position *pos, const zft_volinfo *volume, __u8 *buf)
772 {
773 unsigned int dest;
774 int limit;
775 int distance;
776 int result = 0;
777 int seg_dist;
778 int new_seg;
779 int old_seg = 0;
780 int fast_seek_trials = 0;
781 TRACE_FUN(ft_t_flow);
782
783 if (new_block_pos == 0) {
784 pos->seg_pos = volume->start_seg;
785 pos->seg_byte_pos = 0;
786 pos->volume_pos = 0;
787 zftc_reset();
788 TRACE_EXIT 0;
789 }
790 dest = new_block_pos * (volume->blk_sz >> 10);
791 distance = dest - (pos->volume_pos >> 10);
792 while (distance != 0) {
793 seg_dist = compute_seg_pos(dest, pos, volume);
794 TRACE(ft_t_noise, "\n"
795 KERN_INFO "seg_dist: %d\n"
796 KERN_INFO "distance: %d\n"
797 KERN_INFO "dest : %d\n"
798 KERN_INFO "vpos : %d\n"
799 KERN_INFO "seg_pos : %d\n"
800 KERN_INFO "trials : %d",
801 seg_dist, distance, dest,
802 (unsigned int)(pos->volume_pos>>10), pos->seg_pos,
803 fast_seek_trials);
804 if (distance > 0) {
805 if (seg_dist < 0) {
806 TRACE(ft_t_bug, "BUG: distance %d > 0, "
807 "segment difference %d < 0",
808 distance, seg_dist);
809 result = -EIO;
810 break;
811 }
812 new_seg = pos->seg_pos + seg_dist;
813 if (new_seg > volume->end_seg) {
814 new_seg = volume->end_seg;
815 }
816 if (old_seg == new_seg || /* loop */
817 seg_dist <= ZFT_SLOW_SEEK_THRESHOLD ||
818 fast_seek_trials >= ZFT_FAST_SEEK_MAX_TRIALS) {
819 TRACE(ft_t_noise, "starting slow seek:\n"
820 KERN_INFO "fast seek failed too often: %s\n"
821 KERN_INFO "near target position : %s\n"
822 KERN_INFO "looping between two segs : %s",
823 (fast_seek_trials >=
824 ZFT_FAST_SEEK_MAX_TRIALS)
825 ? "yes" : "no",
826 (seg_dist <= ZFT_SLOW_SEEK_THRESHOLD)
827 ? "yes" : "no",
828 (old_seg == new_seg)
829 ? "yes" : "no");
830 result = slow_seek_forward(dest, &cseg,
831 pos, volume, buf);
832 break;
833 }
834 old_seg = new_seg;
835 limit = volume->end_seg;
836 fast_seek_trials ++;
837 for (;;) {
838 result = search_valid_segment(new_seg, limit,
839 volume->size,
840 pos, &cseg,
841 volume, buf);
842 if (result == 0 || result == -EINTR) {
843 break;
844 }
845 if (new_seg == volume->start_seg) {
846 result = -EIO; /* set errror
847 * condition
848 */
849 break;
850 }
851 limit = new_seg;
852 new_seg -= ZFT_FAST_SEEK_BACKUP;
853 if (new_seg < volume->start_seg) {
854 new_seg = volume->start_seg;
855 }
856 }
857 if (result < 0) {
858 TRACE(ft_t_warn,
859 "Couldn't find a readable segment");
860 break;
861 }
862 } else /* if (distance < 0) */ {
863 if (seg_dist > 0) {
864 TRACE(ft_t_bug, "BUG: distance %d < 0, "
865 "segment difference %d >0",
866 distance, seg_dist);
867 result = -EIO;
868 break;
869 }
870 new_seg = pos->seg_pos + seg_dist;
871 if (fast_seek_trials > 0 && seg_dist == 0) {
872 /* this avoids sticking to the same
873 * segment all the time. On the other hand:
874 * if we got here for the first time, and the
875 * deblock_buffer still contains a valid
876 * segment, then there is no need to skip to
877 * the previous segment if the desired position
878 * is inside this segment.
879 */
880 new_seg --;
881 }
882 if (new_seg < volume->start_seg) {
883 new_seg = volume->start_seg;
884 }
885 limit = pos->seg_pos;
886 fast_seek_trials ++;
887 for (;;) {
888 result = search_valid_segment(new_seg, limit,
889 pos->volume_pos,
890 pos, &cseg,
891 volume, buf);
892 if (result == 0 || result == -EINTR) {
893 break;
894 }
895 if (new_seg == volume->start_seg) {
896 result = -EIO; /* set errror
897 * condition
898 */
899 break;
900 }
901 limit = new_seg;
902 new_seg -= ZFT_FAST_SEEK_BACKUP;
903 if (new_seg < volume->start_seg) {
904 new_seg = volume->start_seg;
905 }
906 }
907 if (result < 0) {
908 TRACE(ft_t_warn,
909 "Couldn't find a readable segment");
910 break;
911 }
912 }
913 distance = dest - (pos->volume_pos >> 10);
914 }
915 TRACE_EXIT result;
916 }
917
918
919 /* advance inside the given segment at most to_do bytes.
920 * of kilobytes moved
921 */
922
923 static int seek_in_segment(const unsigned int to_do,
924 cmpr_info *c_info,
925 const char *src_buf,
926 const int seg_sz,
927 const int seg_pos,
928 const zft_volinfo *volume)
929 {
930 int result = 0;
931 int blk_sz = volume->blk_sz >> 10;
932 int remaining = to_do;
933 TRACE_FUN(ft_t_flow);
934
935 if (c_info->offset == 0) {
936 /* new segment just read
937 */
938 TRACE_CATCH(get_cseg(c_info, src_buf, seg_sz, volume),);
939 c_info->cmpr_pos += c_info->count;
940 DUMP_CMPR_INFO(ft_t_noise, "", c_info);
941 }
942 /* loop and uncompress until user buffer full or
943 * deblock-buffer empty
944 */
945 TRACE(ft_t_noise, "compressed_sz: %d, compos : %d",
946 c_info->cmpr_sz, c_info->cmpr_pos);
947 while (c_info->spans == 0 && remaining > 0) {
948 if (c_info->cmpr_pos != 0) { /* cmpr buf is not empty */
949 result += blk_sz;
950 remaining -= blk_sz;
951 c_info->cmpr_pos = 0;
952 }
953 if (remaining > 0) {
954 get_next_cluster(c_info, src_buf, seg_sz,
955 volume->end_seg == seg_pos);
956 if (c_info->count != 0) {
957 c_info->cmpr_pos = c_info->count;
958 c_info->offset += c_info->count;
959 } else {
960 break;
961 }
962 }
963 /* Allow escape from this loop on signal!
964 */
965 FT_SIGNAL_EXIT(_DONT_BLOCK);
966 DUMP_CMPR_INFO(ft_t_noise, "", c_info);
967 TRACE(ft_t_noise, "to_do: %d", remaining);
968 }
969 if (seg_sz - c_info->offset <= 18) {
970 c_info->offset = seg_sz;
971 }
972 TRACE(ft_t_noise, "\n"
973 KERN_INFO "segment size : %d\n"
974 KERN_INFO "buf_pos_read : %d\n"
975 KERN_INFO "remaining : %d",
976 seg_sz, c_info->offset,
977 seg_sz - c_info->offset);
978 TRACE_EXIT result;
979 }
980
981 static int slow_seek_forward_until_error(const unsigned int distance,
982 cmpr_info *c_info,
983 zft_position *pos,
984 const zft_volinfo *volume,
985 __u8 *buf)
986 {
987 unsigned int remaining = distance;
988 int seg_sz;
989 int seg_pos;
990 int result;
991 TRACE_FUN(ft_t_flow);
992
993 seg_pos = pos->seg_pos;
994 do {
995 TRACE_CATCH(seg_sz = zft_fetch_segment(seg_pos, buf,
996 FT_RD_AHEAD),);
997 /* now we have the contents of the actual segment in
998 * the deblock buffer
999 */
1000 TRACE_CATCH(result = seek_in_segment(remaining, c_info, buf,
1001 seg_sz, seg_pos,volume),);
1002 remaining -= result;
1003 pos->volume_pos += result<<10;
1004 pos->seg_pos = seg_pos;
1005 pos->seg_byte_pos = c_info->offset;
1006 seg_pos ++;
1007 if (seg_pos <= volume->end_seg && c_info->offset == seg_sz) {
1008 pos->seg_pos ++;
1009 pos->seg_byte_pos = 0;
1010 c_info->offset = 0;
1011 }
1012 /* Allow escape from this loop on signal!
1013 */
1014 FT_SIGNAL_EXIT(_DONT_BLOCK);
1015 TRACE(ft_t_noise, "\n"
1016 KERN_INFO "remaining: %d\n"
1017 KERN_INFO "seg_pos: %d\n"
1018 KERN_INFO "end_seg: %d\n"
1019 KERN_INFO "result: %d",
1020 remaining, seg_pos, volume->end_seg, result);
1021 } while (remaining > 0 && seg_pos <= volume->end_seg);
1022 TRACE_EXIT 0;
1023 }
1024
1025 /* return segment id of next segment containing valid data, -EIO otherwise
1026 */
1027 static int search_valid_segment(unsigned int segment,
1028 const unsigned int end_seg,
1029 const unsigned int max_foffs,
1030 zft_position *pos,
1031 cmpr_info *c_info,
1032 const zft_volinfo *volume,
1033 __u8 *buf)
1034 {
1035 cmpr_info tmp_info;
1036 int seg_sz;
1037 TRACE_FUN(ft_t_flow);
1038
1039 memset(&tmp_info, 0, sizeof(cmpr_info));
1040 while (segment <= end_seg) {
1041 FT_SIGNAL_EXIT(_DONT_BLOCK);
1042 TRACE(ft_t_noise,
1043 "Searching readable segment between %d and %d",
1044 segment, end_seg);
1045 seg_sz = zft_fetch_segment(segment, buf, FT_RD_AHEAD);
1046 if ((seg_sz > 0) &&
1047 (get_cseg (&tmp_info, buf, seg_sz, volume) >= 0) &&
1048 (tmp_info.foffs != 0 || segment == volume->start_seg)) {
1049 if ((tmp_info.foffs>>10) > max_foffs) {
1050 TRACE_ABORT(-EIO, ft_t_noise, "\n"
1051 KERN_INFO "cseg.foff: %d\n"
1052 KERN_INFO "dest : %d",
1053 (int)(tmp_info.foffs >> 10),
1054 max_foffs);
1055 }
1056 DUMP_CMPR_INFO(ft_t_noise, "", &tmp_info);
1057 *c_info = tmp_info;
1058 pos->seg_pos = segment;
1059 pos->volume_pos = c_info->foffs;
1060 pos->seg_byte_pos = c_info->offset;
1061 TRACE(ft_t_noise, "found segment at %d", segment);
1062 TRACE_EXIT 0;
1063 }
1064 segment++;
1065 }
1066 TRACE_EXIT -EIO;
1067 }
1068
1069 static int slow_seek_forward(unsigned int dest,
1070 cmpr_info *c_info,
1071 zft_position *pos,
1072 const zft_volinfo *volume,
1073 __u8 *buf)
1074 {
1075 unsigned int distance;
1076 int result = 0;
1077 TRACE_FUN(ft_t_flow);
1078
1079 distance = dest - (pos->volume_pos >> 10);
1080 while ((distance > 0) &&
1081 (result = slow_seek_forward_until_error(distance,
1082 c_info,
1083 pos,
1084 volume,
1085 buf)) < 0) {
1086 if (result == -EINTR) {
1087 break;
1088 }
1089 TRACE(ft_t_noise, "seg_pos: %d", pos->seg_pos);
1090 /* the failing segment is either pos->seg_pos or
1091 * pos->seg_pos + 1. There is no need to further try
1092 * that segment, because ftape_read_segment() already
1093 * has tried very much to read it. So we start with
1094 * following segment, which is pos->seg_pos + 1
1095 */
1096 if(search_valid_segment(pos->seg_pos+1, volume->end_seg, dest,
1097 pos, c_info,
1098 volume, buf) < 0) {
1099 TRACE(ft_t_noise, "search_valid_segment() failed");
1100 result = -EIO;
1101 break;
1102 }
1103 distance = dest - (pos->volume_pos >> 10);
1104 result = 0;
1105 TRACE(ft_t_noise, "segment: %d", pos->seg_pos);
1106 /* found valid segment, retry the seek */
1107 }
1108 TRACE_EXIT result;
1109 }
1110
1111 static int compute_seg_pos(const unsigned int dest,
1112 zft_position *pos,
1113 const zft_volinfo *volume)
1114 {
1115 int segment;
1116 int distance = dest - (pos->volume_pos >> 10);
1117 unsigned int raw_size;
1118 unsigned int virt_size;
1119 unsigned int factor;
1120 TRACE_FUN(ft_t_flow);
1121
1122 if (distance >= 0) {
1123 raw_size = volume->end_seg - pos->seg_pos + 1;
1124 virt_size = ((unsigned int)(volume->size>>10)
1125 - (unsigned int)(pos->volume_pos>>10)
1126 + FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS - 1);
1127 virt_size /= FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS;
1128 if (virt_size == 0 || raw_size == 0) {
1129 TRACE_EXIT 0;
1130 }
1131 if (raw_size >= (1<<25)) {
1132 factor = raw_size/(virt_size>>7);
1133 } else {
1134 factor = (raw_size<<7)/virt_size;
1135 }
1136 segment = distance/(FT_SECTORS_PER_SEGMENT-FT_ECC_SECTORS);
1137 segment = (segment * factor)>>7;
1138 } else {
1139 raw_size = pos->seg_pos - volume->start_seg + 1;
1140 virt_size = ((unsigned int)(pos->volume_pos>>10)
1141 + FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS - 1);
1142 virt_size /= FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS;
1143 if (virt_size == 0 || raw_size == 0) {
1144 TRACE_EXIT 0;
1145 }
1146 if (raw_size >= (1<<25)) {
1147 factor = raw_size/(virt_size>>7);
1148 } else {
1149 factor = (raw_size<<7)/virt_size;
1150 }
1151 segment = distance/(FT_SECTORS_PER_SEGMENT-FT_ECC_SECTORS);
1152 }
1153 TRACE(ft_t_noise, "factor: %d/%d", factor, 1<<7);
1154 TRACE_EXIT segment;
1155 }
1156
1157 static struct zft_cmpr_ops cmpr_ops = {
1158 zftc_write,
1159 zftc_read,
1160 zftc_seek,
1161 zftc_lock,
1162 zftc_reset,
1163 zftc_cleanup
1164 };
1165
1166 int zft_compressor_init(void)
1167 {
1168 TRACE_FUN(ft_t_flow);
1169
1170 #ifdef MODULE
1171 printk(KERN_INFO "zftape compressor v1.00a 970514 for " FTAPE_VERSION "\n");
1172 if (TRACE_LEVEL >= ft_t_info) {
1173 printk(
1174 KERN_INFO "(c) 1997 Claus-Justus Heine (claus@momo.math.rwth-aachen.de)\n"
1175 KERN_INFO "Compressor for zftape (lzrw3 algorithm)\n");
1176 }
1177 #else /* !MODULE */
1178 /* print a short no-nonsense boot message */
1179 printk("zftape compressor v1.00a 970514\n");
1180 printk("For use with " FTAPE_VERSION "\n");
1181 #endif /* MODULE */
1182 TRACE(ft_t_info, "zft_compressor_init @ 0x%p", zft_compressor_init);
1183 TRACE(ft_t_info, "installing compressor for zftape ...");
1184 TRACE_CATCH(zft_cmpr_register(&cmpr_ops),);
1185 TRACE_EXIT 0;
1186 }
1187
1188 #ifdef MODULE
1189
1190 MODULE_AUTHOR(
1191 "(c) 1996, 1997 Claus-Justus Heine (claus@momo.math.rwth-aachen.de");
1192 MODULE_DESCRIPTION(
1193 "Compression routines for zftape. Uses the lzrw3 algorithm by Ross Williams");
1194 MODULE_LICENSE("GPL");
1195
1196 /* Called by modules package when installing the driver
1197 */
1198 int init_module(void)
1199 {
1200 return zft_compressor_init();
1201 }
1202
1203 #endif /* MODULE */
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