378 lines
11 KiB
C
378 lines
11 KiB
C
/*
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* Copyright (C) 1996, 1997 Claus-Justus Heine
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Source: /homes/cvs/ftape-stacked/ftape/zftape/zftape-read.c,v $
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* $Revision: 1.2 $
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* $Date: 1997/10/05 19:19:06 $
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*
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* This file contains the high level reading code
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* for the QIC-117 floppy-tape driver for Linux.
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*/
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/zftape.h>
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#include <asm/uaccess.h>
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#include "../zftape/zftape-init.h"
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#include "../zftape/zftape-eof.h"
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#include "../zftape/zftape-ctl.h"
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#include "../zftape/zftape-write.h"
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#include "../zftape/zftape-read.h"
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#include "../zftape/zftape-rw.h"
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#include "../zftape/zftape-vtbl.h"
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/* Global vars.
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*/
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int zft_just_before_eof;
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/* Local vars.
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*/
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static int buf_len_rd;
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void zft_zap_read_buffers(void)
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{
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buf_len_rd = 0;
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}
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int zft_read_header_segments(void)
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{
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TRACE_FUN(ft_t_flow);
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zft_header_read = 0;
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TRACE_CATCH(zft_vmalloc_once(&zft_hseg_buf, FT_SEGMENT_SIZE),);
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TRACE_CATCH(ftape_read_header_segment(zft_hseg_buf),);
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TRACE(ft_t_info, "Segments written since first format: %d",
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(int)GET4(zft_hseg_buf, FT_SEG_CNT));
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zft_qic113 = (ft_format_code != fmt_normal &&
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ft_format_code != fmt_1100ft &&
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ft_format_code != fmt_425ft);
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TRACE(ft_t_info, "ft_first_data_segment: %d, ft_last_data_segment: %d",
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ft_first_data_segment, ft_last_data_segment);
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zft_capacity = zft_get_capacity();
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zft_old_ftape = zft_ftape_validate_label(&zft_hseg_buf[FT_LABEL]);
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if (zft_old_ftape) {
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TRACE(ft_t_info,
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"Found old ftaped tape, emulating eof marks, entering read-only mode");
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zft_ftape_extract_file_marks(zft_hseg_buf);
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TRACE_CATCH(zft_fake_volume_headers(zft_eof_map,
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zft_nr_eof_marks),);
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} else {
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/* the specs say that the volume table must be
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* initialized with zeroes during formatting, so it
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* MUST be readable, i.e. contain vaid ECC
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* information.
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*/
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TRACE_CATCH(ftape_read_segment(ft_first_data_segment,
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zft_deblock_buf,
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FT_RD_SINGLE),);
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TRACE_CATCH(zft_extract_volume_headers(zft_deblock_buf),);
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}
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zft_header_read = 1;
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zft_set_flags(zft_unit);
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zft_reset_position(&zft_pos);
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TRACE_EXIT 0;
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}
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int zft_fetch_segment_fraction(const unsigned int segment, void *buffer,
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const ft_read_mode_t read_mode,
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const unsigned int start,
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const unsigned int size)
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{
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int seg_sz;
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TRACE_FUN(ft_t_flow);
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if (segment == zft_deblock_segment) {
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TRACE(ft_t_data_flow,
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"re-using segment %d already in deblock buffer",
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segment);
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seg_sz = zft_get_seg_sz(segment);
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if (start > seg_sz) {
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TRACE_ABORT(-EINVAL, ft_t_bug,
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"trying to read beyond end of segment:\n"
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KERN_INFO "seg_sz : %d\n"
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KERN_INFO "start : %d\n"
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KERN_INFO "segment: %d",
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seg_sz, start, segment);
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}
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if ((start + size) > seg_sz) {
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TRACE_EXIT seg_sz - start;
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}
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TRACE_EXIT size;
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}
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seg_sz = ftape_read_segment_fraction(segment, buffer, read_mode,
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start, size);
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TRACE(ft_t_data_flow, "segment %d, result %d", segment, seg_sz);
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if ((int)seg_sz >= 0 && start == 0 && size == FT_SEGMENT_SIZE) {
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/* this implicitly assumes that we are always called with
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* buffer == zft_deblock_buf
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*/
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zft_deblock_segment = segment;
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} else {
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zft_deblock_segment = -1;
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}
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TRACE_EXIT seg_sz;
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}
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/*
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* out:
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*
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* int *read_cnt: the number of bytes we removed from the
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* zft_deblock_buf (result)
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*
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* int *to_do : the remaining size of the read-request. Is changed.
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*
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* in:
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*
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* char *buff : buff is the address of the upper part of the user
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* buffer, that hasn't been filled with data yet.
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* int buf_pos_read: copy of buf_pos_rd
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* int buf_len_read: copy of buf_len_rd
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* char *zft_deblock_buf: ftape_zft_deblock_buf
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*
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* returns the amount of data actually copied to the user-buffer
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*
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* to_do MUST NOT SHRINK except to indicate an EOT. In this case to_do
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* has to be set to 0. We cannot return -ENOSPC, because we return the
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* amount of data actually * copied to the user-buffer
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*/
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static int zft_simple_read (int *read_cnt,
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__u8 __user *dst_buf,
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const int to_do,
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const __u8 *src_buf,
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const int seg_sz,
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const zft_position *pos,
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const zft_volinfo *volume)
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{
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TRACE_FUN(ft_t_flow);
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if (seg_sz - pos->seg_byte_pos < to_do) {
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*read_cnt = seg_sz - pos->seg_byte_pos;
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} else {
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*read_cnt = to_do;
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}
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if (copy_to_user(dst_buf,
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src_buf + pos->seg_byte_pos, *read_cnt) != 0) {
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TRACE_EXIT -EFAULT;
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}
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TRACE(ft_t_noise, "nr bytes just read: %d", *read_cnt);
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TRACE_EXIT *read_cnt;
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}
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/* req_len: gets clipped due to EOT of EOF.
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* req_clipped: is a flag indicating whether req_len was clipped or not
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* volume: contains information on current volume (blk_sz etc.)
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*/
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static int check_read_access(int *req_len,
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const zft_volinfo **volume,
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int *req_clipped,
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const zft_position *pos)
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{
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static __s64 remaining;
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static int eod;
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TRACE_FUN(ft_t_flow);
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if (zft_io_state != zft_reading) {
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if (zft_offline) { /* offline includes no_tape */
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TRACE_ABORT(-ENXIO, ft_t_warn,
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"tape is offline or no cartridge");
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}
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if (!ft_formatted) {
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TRACE_ABORT(-EACCES,
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ft_t_warn, "tape is not formatted");
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}
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/* now enter defined state, read header segment if not
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* already done and flush write buffers
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*/
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TRACE_CATCH(zft_def_idle_state(),);
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zft_io_state = zft_reading;
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if (zft_tape_at_eod(pos)) {
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eod = 1;
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TRACE_EXIT 1;
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}
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eod = 0;
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*volume = zft_find_volume(pos->seg_pos);
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/* get the space left until EOF */
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remaining = zft_check_for_eof(*volume, pos);
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buf_len_rd = 0;
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TRACE(ft_t_noise, "remaining: " LL_X ", vol_no: %d",
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LL(remaining), (*volume)->count);
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} else if (zft_tape_at_eod(pos)) {
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if (++eod > 2) {
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TRACE_EXIT -EIO; /* st.c also returns -EIO */
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} else {
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TRACE_EXIT 1;
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}
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}
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if ((*req_len % (*volume)->blk_sz) != 0) {
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/* this message is informational only. The user gets the
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* proper return value
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*/
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TRACE_ABORT(-EINVAL, ft_t_info,
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"req_len %d not a multiple of block size %d",
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*req_len, (*volume)->blk_sz);
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}
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/* As GNU tar doesn't accept partial read counts when the
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* multiple volume flag is set, we make sure to return the
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* requested amount of data. Except, of course, at the end of
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* the tape or file mark.
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*/
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remaining -= *req_len;
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if (remaining <= 0) {
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TRACE(ft_t_noise,
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"clipped request from %d to %d.",
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*req_len, (int)(*req_len + remaining));
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*req_len += remaining;
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*req_clipped = 1;
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} else {
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*req_clipped = 0;
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}
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TRACE_EXIT 0;
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}
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/* this_segs_size: the current segment's size.
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* buff: the USER-SPACE buffer provided by the calling function.
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* req_len: how much data should be read at most.
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* volume: contains information on current volume (blk_sz etc.)
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*/
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static int empty_deblock_buf(__u8 __user *usr_buf, const int req_len,
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const __u8 *src_buf, const int seg_sz,
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zft_position *pos,
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const zft_volinfo *volume)
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{
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int cnt;
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int result = 0;
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TRACE_FUN(ft_t_flow);
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TRACE(ft_t_data_flow, "this_segs_size: %d", seg_sz);
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if (zft_use_compression && volume->use_compression) {
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TRACE_CATCH(zft_cmpr_lock(1 /* try to load */),);
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TRACE_CATCH(result= (*zft_cmpr_ops->read)(&cnt,
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usr_buf, req_len,
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src_buf, seg_sz,
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pos, volume),);
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} else {
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TRACE_CATCH(result= zft_simple_read (&cnt,
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usr_buf, req_len,
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src_buf, seg_sz,
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pos, volume),);
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}
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pos->volume_pos += result;
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pos->tape_pos += cnt;
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pos->seg_byte_pos += cnt;
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buf_len_rd -= cnt; /* remaining bytes in buffer */
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TRACE(ft_t_data_flow, "buf_len_rd: %d, cnt: %d", buf_len_rd, cnt);
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if(pos->seg_byte_pos >= seg_sz) {
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pos->seg_pos++;
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pos->seg_byte_pos = 0;
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}
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TRACE(ft_t_data_flow, "bytes moved out of deblock-buffer: %d", cnt);
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TRACE_EXIT result;
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}
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/* note: we store the segment id of the segment that is inside the
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* deblock buffer. This spares a lot of ftape_read_segment()s when we
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* use small block-sizes. The block-size may be 1kb (SECTOR_SIZE). In
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* this case a MTFSR 28 maybe still inside the same segment.
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*/
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int _zft_read(char __user *buff, int req_len)
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{
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int req_clipped;
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int result = 0;
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int bytes_read = 0;
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static unsigned int seg_sz = 0;
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static const zft_volinfo *volume = NULL;
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TRACE_FUN(ft_t_flow);
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zft_resid = req_len;
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result = check_read_access(&req_len, &volume,
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&req_clipped, &zft_pos);
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switch(result) {
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case 0:
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break; /* nothing special */
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case 1:
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TRACE(ft_t_noise, "EOD reached");
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TRACE_EXIT 0; /* EOD */
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default:
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TRACE_ABORT(result, ft_t_noise,
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"check_read_access() failed with result %d",
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result);
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TRACE_EXIT result;
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}
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while (req_len > 0) {
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/* Allow escape from this loop on signal !
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*/
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FT_SIGNAL_EXIT(_DONT_BLOCK);
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/* buf_len_rd == 0 means that we need to read a new
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* segment.
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*/
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if (buf_len_rd == 0) {
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while((result = zft_fetch_segment(zft_pos.seg_pos,
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zft_deblock_buf,
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FT_RD_AHEAD)) == 0) {
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zft_pos.seg_pos ++;
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zft_pos.seg_byte_pos = 0;
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}
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if (result < 0) {
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zft_resid -= bytes_read;
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TRACE_ABORT(result, ft_t_noise,
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"zft_fetch_segment(): %d",
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result);
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}
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seg_sz = result;
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buf_len_rd = seg_sz - zft_pos.seg_byte_pos;
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}
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TRACE_CATCH(result = empty_deblock_buf(buff,
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req_len,
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zft_deblock_buf,
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seg_sz,
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&zft_pos,
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volume),
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zft_resid -= bytes_read);
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TRACE(ft_t_data_flow, "bytes just read: %d", result);
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bytes_read += result; /* what we got so far */
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buff += result; /* index in user-buffer */
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req_len -= result; /* what's left from req_len */
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} /* while (req_len > 0) */
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if (req_clipped) {
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TRACE(ft_t_data_flow,
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"maybe partial count because of eof mark");
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if (zft_just_before_eof && bytes_read == 0) {
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/* req_len was > 0, but user didn't get
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* anything the user has read in the eof-mark
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*/
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zft_move_past_eof(&zft_pos);
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ftape_abort_operation();
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} else {
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/* don't skip to the next file before the user
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* tried to read a second time past EOF Just
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* mark that we are at EOF and maybe decrement
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* zft_seg_pos to stay in the same volume;
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*/
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zft_just_before_eof = 1;
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zft_position_before_eof(&zft_pos, volume);
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TRACE(ft_t_noise, "just before eof");
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}
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}
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zft_resid -= result; /* for MTSTATUS */
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TRACE_EXIT bytes_read;
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}
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