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linux/drivers/char/ftape/compressor/zftape-compress.c

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/*
* Copyright (C) 1994-1997 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.
*
* This file implements a "generic" interface between the *
* zftape-driver and a compression-algorithm. The *
* compression-algorithm currently used is a LZ77. I use the *
* implementation lzrw3 by Ross N. Williams (Renaissance *
* Software). The compression program itself is in the file
* lzrw3.c * and lzrw3.h. To adopt another compression algorithm
* the functions * zft_compress() and zft_uncompress() must be
* changed * appropriately. See below.
*/
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/zftape.h>
#include <asm/uaccess.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 "../compressor/zftape-compress.h"
#include "../zftape/zftape-vtbl.h"
#include "../compressor/lzrw3.h"
/*
* global variables
*/
/* I handle the allocation of this buffer as a special case, because
* it's size varies depending on the tape length inserted.
*/
/* local variables
*/
static void *zftc_wrk_mem = NULL;
static __u8 *zftc_buf = NULL;
static void *zftc_scratch_buf = NULL;
/* compression statistics
*/
static unsigned int zftc_wr_uncompressed = 0;
static unsigned int zftc_wr_compressed = 0;
static unsigned int zftc_rd_uncompressed = 0;
static unsigned int zftc_rd_compressed = 0;
/* forward */
static int zftc_write(int *write_cnt,
__u8 *dst_buf, const int seg_sz,
const __u8 __user *src_buf, const int req_len,
const zft_position *pos, const zft_volinfo *volume);
static int zftc_read(int *read_cnt,
__u8 __user *dst_buf, const int to_do,
const __u8 *src_buf, const int seg_sz,
const zft_position *pos, const zft_volinfo *volume);
static int zftc_seek(unsigned int new_block_pos,
zft_position *pos, const zft_volinfo *volume,
__u8 *buffer);
static void zftc_lock (void);
static void zftc_reset (void);
static void zftc_cleanup(void);
static void zftc_stats (void);
/* compressed segment. This conforms to QIC-80-MC, Revision K.
*
* Rev. K applies to tapes with `fixed length format' which is
* indicated by format code 2,3 and 5. See below for format code 4 and 6
*
* 2 bytes: offset of compression segment structure
* 29k > offset >= 29k-18: data from previous segment ens in this
* segment and no compressed block starts
* in this segment
* offset == 0: data from previous segment occupies entire
* segment and continues in next segment
* n bytes: remainder from previous segment
*
* Rev. K:
* 4 bytes: 4 bytes: files set byte offset
* Post Rev. K and QIC-3020/3020:
* 8 bytes: 8 bytes: files set byte offset
* 2 bytes: byte count N (amount of data following)
* bit 15 is set if data is compressed, bit 15 is not
* set if data is uncompressed
* N bytes: data (as much as specified in the byte count)
* 2 bytes: byte count N_1 of next cluster
* N_1 bytes: data of next cluset
* 2 bytes: byte count N_2 of next cluster
* N_2 bytes: ...
*
* Note that the `N' byte count accounts only for the bytes that in the
* current segment if the cluster spans to the next segment.
*/
typedef struct
{
int cmpr_pos; /* actual position in compression buffer */
int cmpr_sz; /* what is left in the compression buffer
* when copying the compressed data to the
* deblock buffer
*/
unsigned int first_block; /* location of header information in
* this segment
*/
unsigned int count; /* amount of data of current block
* contained in current segment
*/
unsigned int offset; /* offset in current segment */
unsigned int spans:1; /* might continue in next segment */
unsigned int uncmpr; /* 0x8000 if this block contains
* uncompressed data
*/
__s64 foffs; /* file set byte offset, same as in
* compression map segment
*/
} cmpr_info;
static cmpr_info cseg; /* static data. Must be kept uptodate and shared by
* read, write and seek functions
*/
#define DUMP_CMPR_INFO(level, msg, info) \
TRACE(level, msg "\n" \
KERN_INFO "cmpr_pos : %d\n" \
KERN_INFO "cmpr_sz : %d\n" \
KERN_INFO "first_block: %d\n" \
KERN_INFO "count : %d\n" \
KERN_INFO "offset : %d\n" \
KERN_INFO "spans : %d\n" \
KERN_INFO "uncmpr : 0x%04x\n" \
KERN_INFO "foffs : " LL_X, \
(info)->cmpr_pos, (info)->cmpr_sz, (info)->first_block, \
(info)->count, (info)->offset, (info)->spans == 1, \
(info)->uncmpr, LL((info)->foffs))
/* dispatch compression segment info, return error code
*
* afterwards, cseg->offset points to start of data of the NEXT
* compressed block, and cseg->count contains the amount of data
* left in the actual compressed block. cseg->spans is set to 1 if
* the block is continued in the following segment. Otherwise it is
* set to 0.
*/
static int get_cseg (cmpr_info *cinfo, const __u8 *buff,
const unsigned int seg_sz,
const zft_volinfo *volume)
{
TRACE_FUN(ft_t_flow);
cinfo->first_block = GET2(buff, 0);
if (cinfo->first_block == 0) { /* data spans to next segment */
cinfo->count = seg_sz - sizeof(__u16);
cinfo->offset = seg_sz;
cinfo->spans = 1;
} else { /* cluster definetely ends in this segment */
if (cinfo->first_block > seg_sz) {
/* data corrupted */
TRACE_ABORT(-EIO, ft_t_err, "corrupted data:\n"
KERN_INFO "segment size: %d\n"
KERN_INFO "first block : %d",
seg_sz, cinfo->first_block);
}
cinfo->count = cinfo->first_block - sizeof(__u16);
cinfo->offset = cinfo->first_block;
cinfo->spans = 0;
}
/* now get the offset the first block should have in the
* uncompressed data stream.
*
* For this magic `18' refer to CRF-3 standard or QIC-80MC,
* Rev. K.
*/
if ((seg_sz - cinfo->offset) > 18) {
if (volume->qic113) { /* > revision K */
TRACE(ft_t_data_flow, "New QIC-113 compliance");
cinfo->foffs = GET8(buff, cinfo->offset);
cinfo->offset += sizeof(__s64);
} else {
TRACE(/* ft_t_data_flow */ ft_t_noise, "pre QIC-113 version");
cinfo->foffs = (__s64)GET4(buff, cinfo->offset);
cinfo->offset += sizeof(__u32);
}
}
if (cinfo->foffs > volume->size) {
TRACE_ABORT(-EIO, ft_t_err, "Inconsistency:\n"
KERN_INFO "offset in current volume: %d\n"
KERN_INFO "size of current volume : %d",
(int)(cinfo->foffs>>10), (int)(volume->size>>10));
}
if (cinfo->cmpr_pos + cinfo->count > volume->blk_sz) {
TRACE_ABORT(-EIO, ft_t_err, "Inconsistency:\n"
KERN_INFO "block size : %d\n"
KERN_INFO "data record: %d",
volume->blk_sz, cinfo->cmpr_pos + cinfo->count);
}
DUMP_CMPR_INFO(ft_t_noise /* ft_t_any */, "", cinfo);
TRACE_EXIT 0;
}
/* This one is called, when a new cluster starts in same segment.
*
* Note: if this is the first cluster in the current segment, we must
* not check whether there are more than 18 bytes available because
* this have already been done in get_cseg() and there may be less
* than 18 bytes available due to header information.
*
*/
static void get_next_cluster(cmpr_info *cluster, const __u8 *buff,
const int seg_sz, const int finish)
{
TRACE_FUN(ft_t_flow);
if (seg_sz - cluster->offset > 18 || cluster->foffs != 0) {
cluster->count = GET2(buff, cluster->offset);
cluster->uncmpr = cluster->count & 0x8000;
cluster->count -= cluster->uncmpr;
cluster->offset += sizeof(__u16);
cluster->foffs = 0;
if ((cluster->offset + cluster->count) < seg_sz) {
cluster->spans = 0;
} else if (cluster->offset + cluster->count == seg_sz) {
cluster->spans = !finish;
} else {
/* either an error or a volume written by an
* old version. If this is a data error, then we'll
* catch it later.
*/
TRACE(ft_t_data_flow, "Either error or old volume");
cluster->spans = 1;
cluster->count = seg_sz - cluster->offset;
}
} else {
cluster->count = 0;
cluster->spans = 0;
cluster->foffs = 0;
}
DUMP_CMPR_INFO(ft_t_noise /* ft_t_any */ , "", cluster);
TRACE_EXIT;
}
static void zftc_lock(void)
{
}
/* this function is needed for zftape_reset_position in zftape-io.c
*/
static void zftc_reset(void)
{
TRACE_FUN(ft_t_flow);
memset((void *)&cseg, '\0', sizeof(cseg));
zftc_stats();
TRACE_EXIT;
}
static int cmpr_mem_initialized = 0;
static unsigned int alloc_blksz = 0;
static int zft_allocate_cmpr_mem(unsigned int blksz)
{
TRACE_FUN(ft_t_flow);
if (cmpr_mem_initialized && blksz == alloc_blksz) {
TRACE_EXIT 0;
}
TRACE_CATCH(zft_vmalloc_once(&zftc_wrk_mem, CMPR_WRK_MEM_SIZE),
zftc_cleanup());
TRACE_CATCH(zft_vmalloc_always(&zftc_buf, blksz + CMPR_OVERRUN),
zftc_cleanup());
alloc_blksz = blksz;
TRACE_CATCH(zft_vmalloc_always(&zftc_scratch_buf, blksz+CMPR_OVERRUN),
zftc_cleanup());
cmpr_mem_initialized = 1;
TRACE_EXIT 0;
}
static void zftc_cleanup(void)
{
TRACE_FUN(ft_t_flow);
zft_vfree(&zftc_wrk_mem, CMPR_WRK_MEM_SIZE);
zft_vfree(&zftc_buf, alloc_blksz + CMPR_OVERRUN);
zft_vfree(&zftc_scratch_buf, alloc_blksz + CMPR_OVERRUN);
cmpr_mem_initialized = alloc_blksz = 0;
TRACE_EXIT;
}
/*****************************************************************************
* *
* The following two functions "ftape_compress()" and *
* "ftape_uncompress()" are the interface to the actual compression *
* algorithm (i.e. they are calling the "compress()" function from *
* the lzrw3 package for now). These routines could quite easily be *
* changed to adopt another compression algorithm instead of lzrw3, *
* which currently is used. *
* *
*****************************************************************************/
/* called by zft_compress_write() to perform the compression. Must
* return the size of the compressed data.
*
* NOTE: The size of the compressed data should not exceed the size of
* the uncompressed data. Most compression algorithms have means
* to store data unchanged if the "compressed" data amount would
* exceed the original one. Mostly this is done by storing some
* flag-bytes in front of the compressed data to indicate if it
* is compressed or not. Thus the worst compression result
* length is the original length plus those flag-bytes.
*
* We don't want that, as the QIC-80 standard provides a means
* of marking uncompressed blocks by simply setting bit 15 of
* the compressed block's length. Thus a compessed block can
* have at most a length of 2^15-1 bytes. The QIC-80 standard
* restricts the block-length even further, allowing only 29k -
* 6 bytes.
*
* Currently, the maximum blocksize used by zftape is 28k.
*
* In short: don't exceed the length of the input-package, set
* bit 15 of the compressed size to 1 if you have copied data
* instead of compressing it.
*/
static int zft_compress(__u8 *in_buffer, unsigned int in_sz, __u8 *out_buffer)
{
__s32 compressed_sz;
TRACE_FUN(ft_t_flow);
lzrw3_compress(COMPRESS_ACTION_COMPRESS, zftc_wrk_mem,
in_buffer, in_sz, out_buffer, &compressed_sz);
if (TRACE_LEVEL >= ft_t_info) {
/* the compiler will optimize this away when
* compiled with NO_TRACE_AT_ALL option
*/
TRACE(ft_t_data_flow, "\n"
KERN_INFO "before compression: %d bytes\n"
KERN_INFO "after compresison : %d bytes",
in_sz,
(int)(compressed_sz < 0
? -compressed_sz : compressed_sz));
/* for statistical purposes
*/
zftc_wr_compressed += (compressed_sz < 0
? -compressed_sz : compressed_sz);
zftc_wr_uncompressed += in_sz;
}
TRACE_EXIT (int)compressed_sz;
}
/* called by zft_compress_read() to decompress the data. Must
* return the size of the decompressed data for sanity checks
* (compared with zft_blk_sz)
*
* NOTE: Read the note for zft_compress() above! If bit 15 of the
* parameter in_sz is set, then the data in in_buffer isn't
* compressed, which must be handled by the un-compression
* algorithm. (I changed lzrw3 to handle this.)
*
* The parameter max_out_sz is needed to prevent buffer overruns when
* uncompressing corrupt data.
*/
static unsigned int zft_uncompress(__u8 *in_buffer,
int in_sz,
__u8 *out_buffer,
unsigned int max_out_sz)
{
TRACE_FUN(ft_t_flow);
lzrw3_compress(COMPRESS_ACTION_DECOMPRESS, zftc_wrk_mem,
in_buffer, (__s32)in_sz,
out_buffer, (__u32 *)&max_out_sz);
if (TRACE_LEVEL >= ft_t_info) {
TRACE(ft_t_data_flow, "\n"
KERN_INFO "before decompression: %d bytes\n"
KERN_INFO "after decompression : %d bytes",
in_sz < 0 ? -in_sz : in_sz,(int)max_out_sz);
/* for statistical purposes
*/
zftc_rd_compressed += in_sz < 0 ? -in_sz : in_sz;
zftc_rd_uncompressed += max_out_sz;
}
TRACE_EXIT (unsigned int)max_out_sz;
}
/* print some statistics about the efficiency of the compression to
* the kernel log
*/
static void zftc_stats(void)
{
TRACE_FUN(ft_t_flow);
if (TRACE_LEVEL < ft_t_info) {
TRACE_EXIT;
}
if (zftc_wr_uncompressed != 0) {
if (zftc_wr_compressed > (1<<14)) {
TRACE(ft_t_info, "compression statistics (writing):\n"
KERN_INFO " compr./uncmpr. : %3d %%",
(((zftc_wr_compressed>>10) * 100)
/ (zftc_wr_uncompressed>>10)));
} else {
TRACE(ft_t_info, "compression statistics (writing):\n"
KERN_INFO " compr./uncmpr. : %3d %%",
((zftc_wr_compressed * 100)
/ zftc_wr_uncompressed));
}
}
if (zftc_rd_uncompressed != 0) {
if (zftc_rd_compressed > (1<<14)) {
TRACE(ft_t_info, "compression statistics (reading):\n"
KERN_INFO " compr./uncmpr. : %3d %%",
(((zftc_rd_compressed>>10) * 100)
/ (zftc_rd_uncompressed>>10)));
} else {
TRACE(ft_t_info, "compression statistics (reading):\n"
KERN_INFO " compr./uncmpr. : %3d %%",
((zftc_rd_compressed * 100)
/ zftc_rd_uncompressed));
}
}
/* only print it once: */
zftc_wr_uncompressed =
zftc_wr_compressed =
zftc_rd_uncompressed =
zftc_rd_compressed = 0;
TRACE_EXIT;
}
/* start new compressed block
*/
static int start_new_cseg(cmpr_info *cluster,
char *dst_buf,
const zft_position *pos,
const unsigned int blk_sz,
const char *src_buf,
const int this_segs_sz,
const int qic113)
{
int size_left;
int cp_cnt;
int buf_pos;
TRACE_FUN(ft_t_flow);
size_left = this_segs_sz - sizeof(__u16) - cluster->cmpr_sz;
TRACE(ft_t_data_flow,"\n"
KERN_INFO "segment size : %d\n"
KERN_INFO "compressed_sz: %d\n"
KERN_INFO "size_left : %d",
this_segs_sz, cluster->cmpr_sz, size_left);
if (size_left > 18) { /* start a new cluseter */
cp_cnt = cluster->cmpr_sz;
cluster->cmpr_sz = 0;
buf_pos = cp_cnt + sizeof(__u16);
PUT2(dst_buf, 0, buf_pos);
if (qic113) {
__s64 foffs = pos->volume_pos;
if (cp_cnt) foffs += (__s64)blk_sz;
TRACE(ft_t_data_flow, "new style QIC-113 header");
PUT8(dst_buf, buf_pos, foffs);
buf_pos += sizeof(__s64);
} else {
__u32 foffs = (__u32)pos->volume_pos;
if (cp_cnt) foffs += (__u32)blk_sz;
TRACE(ft_t_data_flow, "old style QIC-80MC header");
PUT4(dst_buf, buf_pos, foffs);
buf_pos += sizeof(__u32);
}
} else if (size_left >= 0) {
cp_cnt = cluster->cmpr_sz;
cluster->cmpr_sz = 0;
buf_pos = cp_cnt + sizeof(__u16);
PUT2(dst_buf, 0, buf_pos);
/* zero unused part of segment. */
memset(dst_buf + buf_pos, '\0', size_left);
buf_pos = this_segs_sz;
} else { /* need entire segment and more space */
PUT2(dst_buf, 0, 0);
cp_cnt = this_segs_sz - sizeof(__u16);
cluster->cmpr_sz -= cp_cnt;
buf_pos = this_segs_sz;
}
memcpy(dst_buf + sizeof(__u16), src_buf + cluster->cmpr_pos, cp_cnt);
cluster->cmpr_pos += cp_cnt;
TRACE_EXIT buf_pos;
}
/* return-value: the number of bytes removed from the user-buffer
* `src_buf' or error code
*
* int *write_cnt : how much actually has been moved to the
* dst_buf. Need not be initialized when
* function returns with an error code
* (negativ return value)
* __u8 *dst_buf : kernel space buffer where the has to be
* copied to. The contents of this buffers
* goes to a specific segment.
* const int seg_sz : the size of the segment dst_buf will be
* copied to.
* const zft_position *pos : struct containing the coordinates in
* the current volume (byte position,
* segment id of current segment etc)
* const zft_volinfo *volume: information about the current volume,
* size etc.
* const __u8 *src_buf : user space buffer that contains the
* data the user wants to be written to
* tape.
* const int req_len : the amount of data the user wants to be
* written to tape.
*/
static int zftc_write(int *write_cnt,
__u8 *dst_buf, const int seg_sz,
const __u8 __user *src_buf, const int req_len,
const zft_position *pos, const zft_volinfo *volume)
{
int req_len_left = req_len;
int result;
int len_left;
int buf_pos_write = pos->seg_byte_pos;
TRACE_FUN(ft_t_flow);
/* Note: we do not unlock the module because
* there are some values cached in that `cseg' variable. We
* don't don't want to use this information when being
* unloaded by kerneld even when the tape is full or when we
* cannot allocate enough memory.
*/
if (pos->tape_pos > (volume->size-volume->blk_sz-ZFT_CMPR_OVERHEAD)) {
TRACE_EXIT -ENOSPC;
}
if (zft_allocate_cmpr_mem(volume->blk_sz) < 0) {
/* should we unlock the module? But it shouldn't
* be locked anyway ...
*/
TRACE_EXIT -ENOMEM;
}
if (buf_pos_write == 0) { /* fill a new segment */
*write_cnt = buf_pos_write = start_new_cseg(&cseg,
dst_buf,
pos,
volume->blk_sz,
zftc_buf,
seg_sz,
volume->qic113);
if (cseg.cmpr_sz == 0 && cseg.cmpr_pos != 0) {
req_len_left -= result = volume->blk_sz;
cseg.cmpr_pos = 0;
} else {
result = 0;
}
} else {
*write_cnt = result = 0;
}
len_left = seg_sz - buf_pos_write;
while ((req_len_left > 0) && (len_left > 18)) {
/* now we have some size left for a new compressed
* block. We know, that the compression buffer is
* empty (else there wouldn't be any space left).
*/
if (copy_from_user(zftc_scratch_buf, src_buf + result,
volume->blk_sz) != 0) {
TRACE_EXIT -EFAULT;
}
req_len_left -= volume->blk_sz;
cseg.cmpr_sz = zft_compress(zftc_scratch_buf, volume->blk_sz,
zftc_buf);
if (cseg.cmpr_sz < 0) {
cseg.uncmpr = 0x8000;
cseg.cmpr_sz = -cseg.cmpr_sz;
} else {
cseg.uncmpr = 0;
}
/* increment "result" iff we copied the entire
* compressed block to the zft_deblock_buf
*/
len_left -= sizeof(__u16);
if (len_left >= cseg.cmpr_sz) {
len_left -= cseg.count = cseg.cmpr_sz;
cseg.cmpr_pos = cseg.cmpr_sz = 0;
result += volume->blk_sz;
} else {
cseg.cmpr_sz -=
cseg.cmpr_pos =
cseg.count = len_left;
len_left = 0;
}
PUT2(dst_buf, buf_pos_write, cseg.uncmpr | cseg.count);
buf_pos_write += sizeof(__u16);
memcpy(dst_buf + buf_pos_write, zftc_buf, cseg.count);
buf_pos_write += cseg.count;
*write_cnt += cseg.count + sizeof(__u16);
FT_SIGNAL_EXIT(_DONT_BLOCK);
}
/* erase the remainder of the segment if less than 18 bytes
* left (18 bytes is due to the QIC-80 standard)
*/
if (len_left <= 18) {
memset(dst_buf + buf_pos_write, '\0', len_left);
(*write_cnt) += len_left;
}
TRACE(ft_t_data_flow, "returning %d", result);
TRACE_EXIT result;
}
/* out:
*
* int *read_cnt: the number of bytes we removed from the zft_deblock_buf
* (result)
* int *to_do : the remaining size of the read-request.
*
* in:
*
* char *buff : buff is the address of the upper part of the user
* buffer, that hasn't been filled with data yet.
* int buf_pos_read : copy of from _ftape_read()
* int buf_len_read : copy of buf_len_rd from _ftape_read()
* char *zft_deblock_buf: zft_deblock_buf
* unsigned short blk_sz: the block size valid for this volume, may differ
* from zft_blk_sz.
* int finish: if != 0 means that this is the last segment belonging
* to this volume
* returns the amount of data actually copied to the user-buffer
*
* to_do MUST NOT SHRINK except to indicate an EOF. In this case *to_do has to
* be set to 0
*/
static int zftc_read (int *read_cnt,
__u8 __user *dst_buf, const int to_do,
const __u8 *src_buf, const int seg_sz,
const zft_position *pos, const zft_volinfo *volume)
{
int uncompressed_sz;
int result = 0;
int remaining = to_do;
TRACE_FUN(ft_t_flow);
TRACE_CATCH(zft_allocate_cmpr_mem(volume->blk_sz),);
if (pos->seg_byte_pos == 0) {
/* new segment just read
*/
TRACE_CATCH(get_cseg(&cseg, src_buf, seg_sz, volume),
*read_cnt = 0);
memcpy(zftc_buf + cseg.cmpr_pos, src_buf + sizeof(__u16),
cseg.count);
cseg.cmpr_pos += cseg.count;
*read_cnt = cseg.offset;
DUMP_CMPR_INFO(ft_t_noise /* ft_t_any */, "", &cseg);
} else {
*read_cnt = 0;
}
/* loop and uncompress until user buffer full or
* deblock-buffer empty
*/
TRACE(ft_t_data_flow, "compressed_sz: %d, compos : %d, *read_cnt: %d",
cseg.cmpr_sz, cseg.cmpr_pos, *read_cnt);
while ((cseg.spans == 0) && (remaining > 0)) {
if (cseg.cmpr_pos != 0) { /* cmpr buf is not empty */
uncompressed_sz =
zft_uncompress(zftc_buf,
cseg.uncmpr == 0x8000 ?
-cseg.cmpr_pos : cseg.cmpr_pos,
zftc_scratch_buf,
volume->blk_sz);
if (uncompressed_sz != volume->blk_sz) {
*read_cnt = 0;
TRACE_ABORT(-EIO, ft_t_warn,
"Uncompressed blk (%d) != blk size (%d)",
uncompressed_sz, volume->blk_sz);
}
if (copy_to_user(dst_buf + result,
zftc_scratch_buf,
uncompressed_sz) != 0 ) {
TRACE_EXIT -EFAULT;
}
remaining -= uncompressed_sz;
result += uncompressed_sz;
cseg.cmpr_pos = 0;
}
if (remaining > 0) {
get_next_cluster(&cseg, src_buf, seg_sz,
volume->end_seg == pos->seg_pos);
if (cseg.count != 0) {
memcpy(zftc_buf, src_buf + cseg.offset,
cseg.count);
cseg.cmpr_pos = cseg.count;
cseg.offset += cseg.count;
*read_cnt += cseg.count + sizeof(__u16);
} else {
remaining = 0;
}
}
TRACE(ft_t_data_flow, "\n"
KERN_INFO "compressed_sz: %d\n"
KERN_INFO "compos : %d\n"
KERN_INFO "*read_cnt : %d",
cseg.cmpr_sz, cseg.cmpr_pos, *read_cnt);
}
if (seg_sz - cseg.offset <= 18) {
*read_cnt += seg_sz - cseg.offset;
TRACE(ft_t_data_flow, "expanding read cnt to: %d", *read_cnt);
}
TRACE(ft_t_data_flow, "\n"
KERN_INFO "segment size : %d\n"
KERN_INFO "read count : %d\n"
KERN_INFO "buf_pos_read : %d\n"
KERN_INFO "remaining : %d",
seg_sz, *read_cnt, pos->seg_byte_pos,
seg_sz - *read_cnt - pos->seg_byte_pos);
TRACE(ft_t_data_flow, "returning: %d", result);
TRACE_EXIT result;
}
/* seeks to the new data-position. Reads sometimes a segment.
*
* start_seg and end_seg give the boundaries of the current volume
* blk_sz is the blk_sz of the current volume as stored in the
* volume label
*
* We don't allow blocksizes less than 1024 bytes, therefore we don't need
* a 64 bit argument for new_block_pos.
*/
static int seek_in_segment(const unsigned int to_do, cmpr_info *c_info,
const char *src_buf, const int seg_sz,
const int seg_pos, const zft_volinfo *volume);
static int slow_seek_forward_until_error(const unsigned int distance,
cmpr_info *c_info, zft_position *pos,
const zft_volinfo *volume, __u8 *buf);
static int search_valid_segment(unsigned int segment,
const unsigned int end_seg,
const unsigned int max_foffs,
zft_position *pos, cmpr_info *c_info,
const zft_volinfo *volume, __u8 *buf);
static int slow_seek_forward(unsigned int dest, cmpr_info *c_info,
zft_position *pos, const zft_volinfo *volume,
__u8 *buf);
static int compute_seg_pos(unsigned int dest, zft_position *pos,
const zft_volinfo *volume);
#define ZFT_SLOW_SEEK_THRESHOLD 10 /* segments */
#define ZFT_FAST_SEEK_MAX_TRIALS 10 /* times */
#define ZFT_FAST_SEEK_BACKUP 10 /* segments */
static int zftc_seek(unsigned int new_block_pos,
zft_position *pos, const zft_volinfo *volume, __u8 *buf)
{
unsigned int dest;
int limit;
int distance;
int result = 0;
int seg_dist;
int new_seg;
int old_seg = 0;
int fast_seek_trials = 0;
TRACE_FUN(ft_t_flow);
if (new_block_pos == 0) {
pos->seg_pos = volume->start_seg;
pos->seg_byte_pos = 0;
pos->volume_pos = 0;
zftc_reset();
TRACE_EXIT 0;
}
dest = new_block_pos * (volume->blk_sz >> 10);
distance = dest - (pos->volume_pos >> 10);
while (distance != 0) {
seg_dist = compute_seg_pos(dest, pos, volume);
TRACE(ft_t_noise, "\n"
KERN_INFO "seg_dist: %d\n"
KERN_INFO "distance: %d\n"
KERN_INFO "dest : %d\n"
KERN_INFO "vpos : %d\n"
KERN_INFO "seg_pos : %d\n"
KERN_INFO "trials : %d",
seg_dist, distance, dest,
(unsigned int)(pos->volume_pos>>10), pos->seg_pos,
fast_seek_trials);
if (distance > 0) {
if (seg_dist < 0) {
TRACE(ft_t_bug, "BUG: distance %d > 0, "
"segment difference %d < 0",
distance, seg_dist);
result = -EIO;
break;
}
new_seg = pos->seg_pos + seg_dist;
if (new_seg > volume->end_seg) {
new_seg = volume->end_seg;
}
if (old_seg == new_seg || /* loop */
seg_dist <= ZFT_SLOW_SEEK_THRESHOLD ||
fast_seek_trials >= ZFT_FAST_SEEK_MAX_TRIALS) {
TRACE(ft_t_noise, "starting slow seek:\n"
KERN_INFO "fast seek failed too often: %s\n"
KERN_INFO "near target position : %s\n"
KERN_INFO "looping between two segs : %s",
(fast_seek_trials >=
ZFT_FAST_SEEK_MAX_TRIALS)
? "yes" : "no",
(seg_dist <= ZFT_SLOW_SEEK_THRESHOLD)
? "yes" : "no",
(old_seg == new_seg)
? "yes" : "no");
result = slow_seek_forward(dest, &cseg,
pos, volume, buf);
break;
}
old_seg = new_seg;
limit = volume->end_seg;
fast_seek_trials ++;
for (;;) {
result = search_valid_segment(new_seg, limit,
volume->size,
pos, &cseg,
volume, buf);
if (result == 0 || result == -EINTR) {
break;
}
if (new_seg == volume->start_seg) {
result = -EIO; /* set errror
* condition
*/
break;
}
limit = new_seg;
new_seg -= ZFT_FAST_SEEK_BACKUP;
if (new_seg < volume->start_seg) {
new_seg = volume->start_seg;
}
}
if (result < 0) {
TRACE(ft_t_warn,
"Couldn't find a readable segment");
break;
}
} else /* if (distance < 0) */ {
if (seg_dist > 0) {
TRACE(ft_t_bug, "BUG: distance %d < 0, "
"segment difference %d >0",
distance, seg_dist);
result = -EIO;
break;
}
new_seg = pos->seg_pos + seg_dist;
if (fast_seek_trials > 0 && seg_dist == 0) {
/* this avoids sticking to the same
* segment all the time. On the other hand:
* if we got here for the first time, and the
* deblock_buffer still contains a valid
* segment, then there is no need to skip to
* the previous segment if the desired position
* is inside this segment.
*/
new_seg --;
}
if (new_seg < volume->start_seg) {
new_seg = volume->start_seg;
}
limit = pos->seg_pos;
fast_seek_trials ++;
for (;;) {
result = search_valid_segment(new_seg, limit,
pos->volume_pos,
pos, &cseg,
volume, buf);
if (result == 0 || result == -EINTR) {
break;
}
if (new_seg == volume->start_seg) {
result = -EIO; /* set errror
* condition
*/
break;
}
limit = new_seg;
new_seg -= ZFT_FAST_SEEK_BACKUP;
if (new_seg < volume->start_seg) {
new_seg = volume->start_seg;
}
}
if (result < 0) {
TRACE(ft_t_warn,
"Couldn't find a readable segment");
break;
}
}
distance = dest - (pos->volume_pos >> 10);
}
TRACE_EXIT result;
}
/* advance inside the given segment at most to_do bytes.
* of kilobytes moved
*/
static int seek_in_segment(const unsigned int to_do,
cmpr_info *c_info,
const char *src_buf,
const int seg_sz,
const int seg_pos,
const zft_volinfo *volume)
{
int result = 0;
int blk_sz = volume->blk_sz >> 10;
int remaining = to_do;
TRACE_FUN(ft_t_flow);
if (c_info->offset == 0) {
/* new segment just read
*/
TRACE_CATCH(get_cseg(c_info, src_buf, seg_sz, volume),);
c_info->cmpr_pos += c_info->count;
DUMP_CMPR_INFO(ft_t_noise, "", c_info);
}
/* loop and uncompress until user buffer full or
* deblock-buffer empty
*/
TRACE(ft_t_noise, "compressed_sz: %d, compos : %d",
c_info->cmpr_sz, c_info->cmpr_pos);
while (c_info->spans == 0 && remaining > 0) {
if (c_info->cmpr_pos != 0) { /* cmpr buf is not empty */
result += blk_sz;
remaining -= blk_sz;
c_info->cmpr_pos = 0;
}
if (remaining > 0) {
get_next_cluster(c_info, src_buf, seg_sz,
volume->end_seg == seg_pos);
if (c_info->count != 0) {
c_info->cmpr_pos = c_info->count;
c_info->offset += c_info->count;
} else {
break;
}
}
/* Allow escape from this loop on signal!
*/
FT_SIGNAL_EXIT(_DONT_BLOCK);
DUMP_CMPR_INFO(ft_t_noise, "", c_info);
TRACE(ft_t_noise, "to_do: %d", remaining);
}
if (seg_sz - c_info->offset <= 18) {
c_info->offset = seg_sz;
}
TRACE(ft_t_noise, "\n"
KERN_INFO "segment size : %d\n"
KERN_INFO "buf_pos_read : %d\n"
KERN_INFO "remaining : %d",
seg_sz, c_info->offset,
seg_sz - c_info->offset);
TRACE_EXIT result;
}
static int slow_seek_forward_until_error(const unsigned int distance,
cmpr_info *c_info,
zft_position *pos,
const zft_volinfo *volume,
__u8 *buf)
{
unsigned int remaining = distance;
int seg_sz;
int seg_pos;
int result;
TRACE_FUN(ft_t_flow);
seg_pos = pos->seg_pos;
do {
TRACE_CATCH(seg_sz = zft_fetch_segment(seg_pos, buf,
FT_RD_AHEAD),);
/* now we have the contents of the actual segment in
* the deblock buffer
*/
TRACE_CATCH(result = seek_in_segment(remaining, c_info, buf,
seg_sz, seg_pos,volume),);
remaining -= result;
pos->volume_pos += result<<10;
pos->seg_pos = seg_pos;
pos->seg_byte_pos = c_info->offset;
seg_pos ++;
if (seg_pos <= volume->end_seg && c_info->offset == seg_sz) {
pos->seg_pos ++;
pos->seg_byte_pos = 0;
c_info->offset = 0;
}
/* Allow escape from this loop on signal!
*/
FT_SIGNAL_EXIT(_DONT_BLOCK);
TRACE(ft_t_noise, "\n"
KERN_INFO "remaining: %d\n"
KERN_INFO "seg_pos: %d\n"
KERN_INFO "end_seg: %d\n"
KERN_INFO "result: %d",
remaining, seg_pos, volume->end_seg, result);
} while (remaining > 0 && seg_pos <= volume->end_seg);
TRACE_EXIT 0;
}
/* return segment id of next segment containing valid data, -EIO otherwise
*/
static int search_valid_segment(unsigned int segment,
const unsigned int end_seg,
const unsigned int max_foffs,
zft_position *pos,
cmpr_info *c_info,
const zft_volinfo *volume,
__u8 *buf)
{
cmpr_info tmp_info;
int seg_sz;
TRACE_FUN(ft_t_flow);
memset(&tmp_info, 0, sizeof(cmpr_info));
while (segment <= end_seg) {
FT_SIGNAL_EXIT(_DONT_BLOCK);
TRACE(ft_t_noise,
"Searching readable segment between %d and %d",
segment, end_seg);
seg_sz = zft_fetch_segment(segment, buf, FT_RD_AHEAD);
if ((seg_sz > 0) &&
(get_cseg (&tmp_info, buf, seg_sz, volume) >= 0) &&
(tmp_info.foffs != 0 || segment == volume->start_seg)) {
if ((tmp_info.foffs>>10) > max_foffs) {
TRACE_ABORT(-EIO, ft_t_noise, "\n"
KERN_INFO "cseg.foff: %d\n"
KERN_INFO "dest : %d",
(int)(tmp_info.foffs >> 10),
max_foffs);
}
DUMP_CMPR_INFO(ft_t_noise, "", &tmp_info);
*c_info = tmp_info;
pos->seg_pos = segment;
pos->volume_pos = c_info->foffs;
pos->seg_byte_pos = c_info->offset;
TRACE(ft_t_noise, "found segment at %d", segment);
TRACE_EXIT 0;
}
segment++;
}
TRACE_EXIT -EIO;
}
static int slow_seek_forward(unsigned int dest,
cmpr_info *c_info,
zft_position *pos,
const zft_volinfo *volume,
__u8 *buf)
{
unsigned int distance;
int result = 0;
TRACE_FUN(ft_t_flow);
distance = dest - (pos->volume_pos >> 10);
while ((distance > 0) &&
(result = slow_seek_forward_until_error(distance,
c_info,
pos,
volume,
buf)) < 0) {
if (result == -EINTR) {
break;
}
TRACE(ft_t_noise, "seg_pos: %d", pos->seg_pos);
/* the failing segment is either pos->seg_pos or
* pos->seg_pos + 1. There is no need to further try
* that segment, because ftape_read_segment() already
* has tried very much to read it. So we start with
* following segment, which is pos->seg_pos + 1
*/
if(search_valid_segment(pos->seg_pos+1, volume->end_seg, dest,
pos, c_info,
volume, buf) < 0) {
TRACE(ft_t_noise, "search_valid_segment() failed");
result = -EIO;
break;
}
distance = dest - (pos->volume_pos >> 10);
result = 0;
TRACE(ft_t_noise, "segment: %d", pos->seg_pos);
/* found valid segment, retry the seek */
}
TRACE_EXIT result;
}
static int compute_seg_pos(const unsigned int dest,
zft_position *pos,
const zft_volinfo *volume)
{
int segment;
int distance = dest - (pos->volume_pos >> 10);
unsigned int raw_size;
unsigned int virt_size;
unsigned int factor;
TRACE_FUN(ft_t_flow);
if (distance >= 0) {
raw_size = volume->end_seg - pos->seg_pos + 1;
virt_size = ((unsigned int)(volume->size>>10)
- (unsigned int)(pos->volume_pos>>10)
+ FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS - 1);
virt_size /= FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS;
if (virt_size == 0 || raw_size == 0) {
TRACE_EXIT 0;
}
if (raw_size >= (1<<25)) {
factor = raw_size/(virt_size>>7);
} else {
factor = (raw_size<<7)/virt_size;
}
segment = distance/(FT_SECTORS_PER_SEGMENT-FT_ECC_SECTORS);
segment = (segment * factor)>>7;
} else {
raw_size = pos->seg_pos - volume->start_seg + 1;
virt_size = ((unsigned int)(pos->volume_pos>>10)
+ FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS - 1);
virt_size /= FT_SECTORS_PER_SEGMENT - FT_ECC_SECTORS;
if (virt_size == 0 || raw_size == 0) {
TRACE_EXIT 0;
}
if (raw_size >= (1<<25)) {
factor = raw_size/(virt_size>>7);
} else {
factor = (raw_size<<7)/virt_size;
}
segment = distance/(FT_SECTORS_PER_SEGMENT-FT_ECC_SECTORS);
}
TRACE(ft_t_noise, "factor: %d/%d", factor, 1<<7);
TRACE_EXIT segment;
}
static struct zft_cmpr_ops cmpr_ops = {
zftc_write,
zftc_read,
zftc_seek,
zftc_lock,
zftc_reset,
zftc_cleanup
};
int zft_compressor_init(void)
{
TRACE_FUN(ft_t_flow);
#ifdef MODULE
printk(KERN_INFO "zftape compressor v1.00a 970514 for " FTAPE_VERSION "\n");
if (TRACE_LEVEL >= ft_t_info) {
printk(
KERN_INFO "(c) 1997 Claus-Justus Heine (claus@momo.math.rwth-aachen.de)\n"
KERN_INFO "Compressor for zftape (lzrw3 algorithm)\n");
}
#else /* !MODULE */
/* print a short no-nonsense boot message */
printk(KERN_INFO "zftape compressor v1.00a 970514\n");
printk(KERN_INFO "For use with " FTAPE_VERSION "\n");
#endif /* MODULE */
TRACE(ft_t_info, "zft_compressor_init @ 0x%p", zft_compressor_init);
TRACE(ft_t_info, "installing compressor for zftape ...");
TRACE_CATCH(zft_cmpr_register(&cmpr_ops),);
TRACE_EXIT 0;
}
#ifdef MODULE
MODULE_AUTHOR(
"(c) 1996, 1997 Claus-Justus Heine (claus@momo.math.rwth-aachen.de");
MODULE_DESCRIPTION(
"Compression routines for zftape. Uses the lzrw3 algorithm by Ross Williams");
MODULE_LICENSE("GPL");
/* Called by modules package when installing the driver
*/
int init_module(void)
{
return zft_compressor_init();
}
#endif /* MODULE */
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