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/*
* Copyright (C) 1996, 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-read.c,v $
* $Revision: 1.2 $
* $Date: 1997/10/05 19:19:06 $
*
* This file contains the high level reading code
* for the QIC-117 floppy-tape driver for Linux.
*/
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/zftape.h>
#if LINUX_VERSION_CODE >= KERNEL_VER(2,1,6)
#include <asm/uaccess.h>
#else
#include <asm/segment.h>
#endif
#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"
/* Global vars.
*/
int zft_just_before_eof;
/* Local vars.
*/
static int buf_len_rd;
void zft_zap_read_buffers(void)
{
buf_len_rd = 0;
}
int zft_read_header_segments(void)
{
TRACE_FUN(ft_t_flow);
zft_header_read = 0;
TRACE_CATCH(zft_vmalloc_once(&zft_hseg_buf, FT_SEGMENT_SIZE),);
TRACE_CATCH(ftape_read_header_segment(zft_hseg_buf),);
TRACE(ft_t_info, "Segments written since first format: %d",
(int)GET4(zft_hseg_buf, FT_SEG_CNT));
zft_qic113 = (ft_format_code != fmt_normal &&
ft_format_code != fmt_1100ft &&
ft_format_code != fmt_425ft);
TRACE(ft_t_info, "ft_first_data_segment: %d, ft_last_data_segment: %d",
ft_first_data_segment, ft_last_data_segment);
zft_capacity = zft_get_capacity();
zft_old_ftape = zft_ftape_validate_label(&zft_hseg_buf[FT_LABEL]);
if (zft_old_ftape) {
TRACE(ft_t_info,
"Found old ftaped tape, emulating eof marks, entering read-only mode");
zft_ftape_extract_file_marks(zft_hseg_buf);
TRACE_CATCH(zft_fake_volume_headers(zft_eof_map,
zft_nr_eof_marks),);
} else {
/* the specs say that the volume table must be
* initialized with zeroes during formatting, so it
* MUST be readable, i.e. contain vaid ECC
* information.
*/
TRACE_CATCH(ftape_read_segment(ft_first_data_segment,
zft_deblock_buf,
FT_RD_SINGLE),);
TRACE_CATCH(zft_extract_volume_headers(zft_deblock_buf),);
}
zft_header_read = 1;
zft_set_flags(zft_unit);
zft_reset_position(&zft_pos);
TRACE_EXIT 0;
}
int zft_fetch_segment_fraction(const unsigned int segment, void *buffer,
const ft_read_mode_t read_mode,
const unsigned int start,
const unsigned int size)
{
int seg_sz;
TRACE_FUN(ft_t_flow);
if (segment == zft_deblock_segment) {
TRACE(ft_t_data_flow,
"re-using segment %d already in deblock buffer",
segment);
seg_sz = zft_get_seg_sz(segment);
if (start > seg_sz) {
TRACE_ABORT(-EINVAL, ft_t_bug,
"trying to read beyond end of segment:\n"
KERN_INFO "seg_sz : %d\n"
KERN_INFO "start : %d\n"
KERN_INFO "segment: %d",
seg_sz, start, segment);
}
if ((start + size) > seg_sz) {
TRACE_EXIT seg_sz - start;
}
TRACE_EXIT size;
}
seg_sz = ftape_read_segment_fraction(segment, buffer, read_mode,
start, size);
TRACE(ft_t_data_flow, "segment %d, result %d", segment, seg_sz);
if ((int)seg_sz >= 0 && start == 0 && size == FT_SEGMENT_SIZE) {
/* this implicitly assumes that we are always called with
* buffer == zft_deblock_buf
*/
zft_deblock_segment = segment;
} else {
zft_deblock_segment = -1;
}
TRACE_EXIT seg_sz;
}
/*
* 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. Is changed.
*
* 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 buf_pos_rd
* int buf_len_read: copy of buf_len_rd
* char *zft_deblock_buf: ftape_zft_deblock_buf
*
* returns the amount of data actually copied to the user-buffer
*
* to_do MUST NOT SHRINK except to indicate an EOT. In this case to_do
* has to be set to 0. We cannot return -ENOSPC, because we return the
* amount of data actually * copied to the user-buffer
*/
static int zft_simple_read (int *read_cnt,
__u8 *dst_buf,
const int to_do,
const __u8 *src_buf,
const int seg_sz,
const zft_position *pos,
const zft_volinfo *volume)
{
TRACE_FUN(ft_t_flow);
if (seg_sz - pos->seg_byte_pos < to_do) {
*read_cnt = seg_sz - pos->seg_byte_pos;
} else {
*read_cnt = to_do;
}
#if LINUX_VERSION_CODE > KERNEL_VER(2,1,3)
if (copy_to_user(dst_buf,
src_buf + pos->seg_byte_pos, *read_cnt) != 0) {
TRACE_EXIT -EFAULT;
}
#else
TRACE_CATCH(verify_area(VERIFY_WRITE, dst_buf, *read_cnt),);
memcpy_tofs(dst_buf, src_buf + pos->seg_byte_pos, *read_cnt);
#endif
TRACE(ft_t_noise, "nr bytes just read: %d", *read_cnt);
TRACE_EXIT *read_cnt;
}
/* req_len: gets clipped due to EOT of EOF.
* req_clipped: is a flag indicating whether req_len was clipped or not
* volume: contains information on current volume (blk_sz etc.)
*/
static int check_read_access(int *req_len,
const zft_volinfo **volume,
int *req_clipped,
const zft_position *pos)
{
static __s64 remaining;
static int eod;
TRACE_FUN(ft_t_flow);
if (zft_io_state != zft_reading) {
if (zft_offline) { /* offline includes no_tape */
TRACE_ABORT(-ENXIO, ft_t_warn,
"tape is offline or no cartridge");
}
if (!ft_formatted) {
TRACE_ABORT(-EACCES,
ft_t_warn, "tape is not formatted");
}
/* now enter defined state, read header segment if not
* already done and flush write buffers
*/
TRACE_CATCH(zft_def_idle_state(),);
zft_io_state = zft_reading;
if (zft_tape_at_eod(pos)) {
eod = 1;
TRACE_EXIT 1;
}
eod = 0;
*volume = zft_find_volume(pos->seg_pos);
/* get the space left until EOF */
remaining = zft_check_for_eof(*volume, pos);
buf_len_rd = 0;
TRACE(ft_t_noise, "remaining: " LL_X ", vol_no: %d",
LL(remaining), (*volume)->count);
} else if (zft_tape_at_eod(pos)) {
if (++eod > 2) {
TRACE_EXIT -EIO; /* st.c also returns -EIO */
} else {
TRACE_EXIT 1;
}
}
if ((*req_len % (*volume)->blk_sz) != 0) {
/* this message is informational only. The user gets the
* proper return value
*/
TRACE_ABORT(-EINVAL, ft_t_info,
"req_len %d not a multiple of block size %d",
*req_len, (*volume)->blk_sz);
}
/* As GNU tar doesn't accept partial read counts when the
* multiple volume flag is set, we make sure to return the
* requested amount of data. Except, of course, at the end of
* the tape or file mark.
*/
remaining -= *req_len;
if (remaining <= 0) {
TRACE(ft_t_noise,
"clipped request from %d to %d.",
*req_len, (int)(*req_len + remaining));
*req_len += remaining;
*req_clipped = 1;
} else {
*req_clipped = 0;
}
TRACE_EXIT 0;
}
/* this_segs_size: the current segment's size.
* buff: the USER-SPACE buffer provided by the calling function.
* req_len: how much data should be read at most.
* volume: contains information on current volume (blk_sz etc.)
*/
static int empty_deblock_buf(__u8 *usr_buf, const int req_len,
const __u8 *src_buf, const int seg_sz,
zft_position *pos,
const zft_volinfo *volume)
{
int cnt;
int result = 0;
TRACE_FUN(ft_t_flow);
TRACE(ft_t_data_flow, "this_segs_size: %d", seg_sz);
if (zft_use_compression && volume->use_compression) {
TRACE_CATCH(zft_cmpr_lock(1 /* try to load */),);
TRACE_CATCH(result= (*zft_cmpr_ops->read)(&cnt,
usr_buf, req_len,
src_buf, seg_sz,
pos, volume),);
} else {
TRACE_CATCH(result= zft_simple_read (&cnt,
usr_buf, req_len,
src_buf, seg_sz,
pos, volume),);
}
pos->volume_pos += result;
pos->tape_pos += cnt;
pos->seg_byte_pos += cnt;
buf_len_rd -= cnt; /* remaining bytes in buffer */
TRACE(ft_t_data_flow, "buf_len_rd: %d, cnt: %d", buf_len_rd, cnt);
if(pos->seg_byte_pos >= seg_sz) {
pos->seg_pos++;
pos->seg_byte_pos = 0;
}
TRACE(ft_t_data_flow, "bytes moved out of deblock-buffer: %d", cnt);
TRACE_EXIT result;
}
/* note: we store the segment id of the segment that is inside the
* deblock buffer. This spares a lot of ftape_read_segment()s when we
* use small block-sizes. The block-size may be 1kb (SECTOR_SIZE). In
* this case a MTFSR 28 maybe still inside the same segment.
*/
int _zft_read(char* buff, int req_len)
{
int req_clipped;
int result = 0;
int bytes_read = 0;
static unsigned int seg_sz = 0;
static const zft_volinfo *volume = NULL;
TRACE_FUN(ft_t_flow);
zft_resid = req_len;
result = check_read_access(&req_len, &volume,
&req_clipped, &zft_pos);
switch(result) {
case 0:
break; /* nothing special */
case 1:
TRACE(ft_t_noise, "EOD reached");
TRACE_EXIT 0; /* EOD */
default:
TRACE_ABORT(result, ft_t_noise,
"check_read_access() failed with result %d",
result);
TRACE_EXIT result;
}
while (req_len > 0) {
/* Allow escape from this loop on signal !
*/
FT_SIGNAL_EXIT(_DONT_BLOCK);
/* buf_len_rd == 0 means that we need to read a new
* segment.
*/
if (buf_len_rd == 0) {
while((result = zft_fetch_segment(zft_pos.seg_pos,
zft_deblock_buf,
FT_RD_AHEAD)) == 0) {
zft_pos.seg_pos ++;
zft_pos.seg_byte_pos = 0;
}
if (result < 0) {
zft_resid -= bytes_read;
TRACE_ABORT(result, ft_t_noise,
"zft_fetch_segment(): %d",
result);
}
seg_sz = result;
buf_len_rd = seg_sz - zft_pos.seg_byte_pos;
}
TRACE_CATCH(result = empty_deblock_buf(buff,
req_len,
zft_deblock_buf,
seg_sz,
&zft_pos,
volume),
zft_resid -= bytes_read);
TRACE(ft_t_data_flow, "bytes just read: %d", result);
bytes_read += result; /* what we got so far */
buff += result; /* index in user-buffer */
req_len -= result; /* what's left from req_len */
} /* while (req_len > 0) */
if (req_clipped) {
TRACE(ft_t_data_flow,
"maybe partial count because of eof mark");
if (zft_just_before_eof && bytes_read == 0) {
/* req_len was > 0, but user didn't get
* anything the user has read in the eof-mark
*/
zft_move_past_eof(&zft_pos);
ftape_abort_operation();
} else {
/* don't skip to the next file before the user
* tried to read a second time past EOF Just
* mark that we are at EOF and maybe decrement
* zft_seg_pos to stay in the same volume;
*/
zft_just_before_eof = 1;
zft_position_before_eof(&zft_pos, volume);
TRACE(ft_t_noise, "just before eof");
}
}
zft_resid -= result; /* for MTSTATUS */
TRACE_EXIT bytes_read;
}
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