patch-2.1.66 linux/drivers/char/ftape/ftape-rw.c
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- Lines: 954
- Date:
Wed Dec 31 16:00:00 1969
- Orig file:
v2.1.65/linux/drivers/char/ftape/ftape-rw.c
- Orig date:
Thu Apr 11 23:49:35 1996
diff -u --recursive --new-file v2.1.65/linux/drivers/char/ftape/ftape-rw.c linux/drivers/char/ftape/ftape-rw.c
@@ -1,953 +0,0 @@
-/*
- * Copyright (C) 1993-1995 Bas Laarhoven.
-
- 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: /home/bas/distr/ftape-2.03b/RCS/ftape-rw.c,v $
- $Author: bas $
- *
- $Revision: 1.54 $
- $Date: 1995/05/27 08:55:27 $
- $State: Beta $
- *
- * This file contains some common code for the segment read and segment
- * write routines for the QIC-117 floppy-tape driver for Linux.
- */
-
-#include <linux/string.h>
-#include <linux/errno.h>
-#include <linux/ftape.h>
-
-#include "tracing.h"
-#include "ftape-rw.h"
-#include "fdc-io.h"
-#include "kernel-interface.h"
-#include "qic117.h"
-#include "ftape-io.h"
-#include "ftape-ctl.h"
-#include "ftape-read.h"
-#include "ftape-eof.h"
-#include "ecc.h"
-#include "ftape-bsm.h"
-
-/* Global vars.
- */
-volatile enum runner_status_enum runner_status = idle;
-byte deblock_buffer[(SECTORS_PER_SEGMENT - 3) * SECTOR_SIZE];
-byte scratch_buffer[(SECTORS_PER_SEGMENT - 3) * SECTOR_SIZE];
-buffer_struct buffer[NR_BUFFERS];
-struct wait_queue *wait_intr = NULL;
-volatile int head;
-volatile int tail; /* not volatile but need same type as head */
-int fdc_setup_error;
-ftape_last_segment_struct ftape_last_segment;
-int header_segment_1 = -1;
-int header_segment_2 = -1;
-int used_header_segment = -1;
-location_record location =
-{-1, 0};
-volatile int tape_running = 0;
-format_type format_code;
-
-/* Local vars.
- */
-static int overrun_count_offset = 0;
-static int inhibit_correction = 0;
-
-
-/* Increment cyclic buffer nr.
- */
-buffer_struct *
- next_buffer(volatile int *x)
-{
- if (++*x >= NR_BUFFERS) {
- *x = 0;
- }
- return &buffer[*x];
-}
-
-int valid_segment_no(unsigned segment)
-{
- return (segment >= first_data_segment && segment <= ftape_last_segment.id);
-}
-
-/* Count nr of 1's in pattern.
- */
-int count_ones(unsigned long mask)
-{
- int bits;
-
- for (bits = 0; mask != 0; mask >>= 1) {
- if (mask & 1) {
- ++bits;
- }
- }
- return bits;
-}
-
-/* Calculate Floppy Disk Controller and DMA parameters for a segment.
- * head: selects buffer struct in array.
- * offset: number of physical sectors to skip (including bad ones).
- * count: number of physical sectors to handle (including bad ones).
- */
-static int setup_segment(buffer_struct * buff, unsigned int segment_id,
- unsigned int sector_offset, unsigned int sector_count, int retry)
-{
- TRACE_FUN(8, "setup_segment");
- unsigned long offset_mask;
- unsigned long mask;
-
- buff->segment_id = segment_id;
- buff->sector_offset = sector_offset;
- buff->remaining = sector_count;
- buff->head = segment_id / segments_per_head;
- buff->cyl = (segment_id % segments_per_head) / segments_per_cylinder;
- buff->sect = (segment_id % segments_per_cylinder) * SECTORS_PER_SEGMENT + 1;
- buff->deleted = 0;
- offset_mask = (1 << buff->sector_offset) - 1;
- mask = get_bad_sector_entry(segment_id) & offset_mask;
- while (mask) {
- if (mask & 1) {
- offset_mask >>= 1; /* don't count bad sector */
- }
- mask >>= 1;
- }
- buff->data_offset = count_ones(offset_mask); /* good sectors to skip */
- buff->ptr = buff->address + buff->data_offset * SECTOR_SIZE;
- TRACEx1(5, "data offset = %d sectors", buff->data_offset);
- if (retry) {
- buff->soft_error_map &= offset_mask; /* keep skipped part */
- } else {
- buff->hard_error_map = buff->soft_error_map = 0;
- }
- buff->bad_sector_map = get_bad_sector_entry(buff->segment_id);
- if (buff->bad_sector_map != 0) {
- TRACEx2(4, "segment: %d, bad sector map: %08lx",
- buff->segment_id, buff->bad_sector_map);
- } else {
- TRACEx1(5, "segment: %d", buff->segment_id);
- }
- if (buff->sector_offset > 0) {
- buff->bad_sector_map >>= buff->sector_offset;
- }
- if (buff->sector_offset != 0 || buff->remaining != SECTORS_PER_SEGMENT) {
- TRACEx2(5, "sector offset = %d, count = %d",
- buff->sector_offset, buff->remaining);
- }
- /*
- * Segments with 3 or less sectors are not written with
- * valid data because there is no space left for the ecc.
- * The data written is whatever happens to be in the buffer.
- * Reading such a segment will return a zero byte-count.
- * To allow us to read/write segments with all bad sectors
- * we fake one readable sector in the segment. This prevents
- * having to handle these segments in a very special way.
- * It is not important if the reading of this bad sector
- * fails or not (the data is ignored). It is only read to
- * keep the driver running.
- * The QIC-40/80 spec. has no information on how to handle
- * this case, so this is my interpretation.
- */
- if (buff->bad_sector_map == EMPTY_SEGMENT) {
- TRACE(5, "empty segment, fake first sector good");
- buff->bad_sector_map = FAKE_SEGMENT;
- }
- fdc_setup_error = 0;
- buff->next_segment = segment_id + 1;
- TRACE_EXIT;
- return 0;
-}
-
-/* Calculate Floppy Disk Controller and DMA parameters for a new segment.
- */
-int setup_new_segment(buffer_struct * buff, unsigned int segment_id, int skip)
-{
- TRACE_FUN(5, "setup_new_segment");
- int result = 0;
- static int old_segment_id = -1;
- static int old_ftape_state = idle;
- int retry = 0;
- unsigned offset = 0;
- int count = SECTORS_PER_SEGMENT;
-
- TRACEx3(5, "%s segment %d (old = %d)",
- (ftape_state == reading) ? "reading" : "writing",
- segment_id, old_segment_id);
- if (ftape_state != old_ftape_state) { /* when verifying */
- old_segment_id = -1;
- old_ftape_state = ftape_state;
- }
- if (segment_id == old_segment_id) {
- ++buff->retry;
- ++history.retries;
- TRACEx1(5, "setting up for retry nr %d", buff->retry);
- retry = 1;
- if (skip && buff->skip > 0) { /* allow skip on retry */
- offset = buff->skip;
- count -= offset;
- TRACEx1(5, "skipping %d sectors", offset);
- }
- } else {
- buff->retry = 0;
- buff->skip = 0;
- old_segment_id = segment_id;
- }
- result = setup_segment(buff, segment_id, offset, count, retry);
- TRACE_EXIT;
- return result;
-}
-
-/* Determine size of next cluster of good sectors.
- */
-int calc_next_cluster(buffer_struct * buff)
-{
- /* Skip bad sectors.
- */
- while (buff->remaining > 0 && (buff->bad_sector_map & 1) != 0) {
- buff->bad_sector_map >>= 1;
- ++buff->sector_offset;
- --buff->remaining;
- }
- /* Find next cluster of good sectors
- */
- if (buff->bad_sector_map == 0) { /* speed up */
- buff->sector_count = buff->remaining;
- } else {
- unsigned long map = buff->bad_sector_map;
-
- buff->sector_count = 0;
- while (buff->sector_count < buff->remaining && (map & 1) == 0) {
- ++buff->sector_count;
- map >>= 1;
- }
- }
- return buff->sector_count;
-}
-
-int check_bot_eot(int status)
-{
- TRACE_FUN(5, "check_bot_eot");
-
- if (status & (QIC_STATUS_AT_BOT | QIC_STATUS_AT_EOT)) {
- location.bot = ((location.track & 1) == 0 ?
- (status & QIC_STATUS_AT_BOT) :
- (status & QIC_STATUS_AT_EOT));
- location.eot = !location.bot;
- location.segment = (location.track +
- (location.bot ? 0 : 1)) * segments_per_track - 1;
- location.sector = -1;
- location.known = 1;
- TRACEx1(5, "tape at logical %s", location.bot ? "bot" : "eot");
- TRACEx1(5, "segment = %d", location.segment);
- } else {
- location.known = 0;
- }
- TRACE_EXIT;
- return location.known;
-}
-
-/* Read Id of first sector passing tape head.
- */
-int ftape_read_id(void)
-{
- TRACE_FUN(8, "ftape_read_id");
- int result;
- int status;
- byte out[2];
-
- /* Assume tape is running on entry, be able to handle
- * situation where it stopped or is stopping.
- */
- location.known = 0; /* default is location not known */
- out[0] = FDC_READID;
- out[1] = FTAPE_UNIT;
- result = fdc_command(out, 2);
- if (result < 0) {
- TRACE(1, "fdc_command failed");
- } else {
- result = fdc_interrupt_wait(20 * SECOND);
- if (result == 0) {
- if (fdc_sect == 0) {
- result = ftape_report_drive_status(&status);
- if (result == 0) {
- if (status & QIC_STATUS_READY) {
- tape_running = 0;
- TRACE(5, "tape has stopped");
- check_bot_eot(status);
- if (!location.known) {
- result = -EIO;
- }
- } else {
- /* If read-id failed because of a hard or soft
- * error, return an error. Higher level must retry!
- */
- result = -EIO;
- }
- }
- } else {
- location.known = 1;
- location.segment = (segments_per_head * fdc_head
- + segments_per_cylinder * fdc_cyl
- + (fdc_sect - 1) / SECTORS_PER_SEGMENT);
- location.sector = (fdc_sect - 1) % SECTORS_PER_SEGMENT;
- location.eot =
- location.bot = 0;
- }
- } else if (result == -ETIME) {
- /* Didn't find id on tape, must be near end: Wait until stopped.
- */
- result = ftape_ready_wait(FOREVER, &status);
- if (result >= 0) {
- tape_running = 0;
- TRACE(5, "tape has stopped");
- check_bot_eot(status);
- if (!location.known) {
- result = -EIO;
- }
- }
- } else {
- /* Interrupted or otherwise failing fdc_interrupt_wait()
- */
- TRACE(1, "fdc_interrupt_wait failed :(");
- result = -EIO;
- }
- }
- if (!location.known) {
- TRACE(5, "no id found");
- } else {
- if (location.sector == 0) {
- TRACEx2(5, "passing segment %d/%d", location.segment, location.sector);
- } else {
- TRACEx2(6, "passing segment %d/%d", location.segment, location.sector);
- }
- }
- TRACE_EXIT;
- return result;
-}
-
-static int logical_forward(void)
-{
- tape_running = 1;
- return ftape_command(QIC_LOGICAL_FORWARD);
-}
-
-static int stop_tape(int *pstatus)
-{
- TRACE_FUN(5, "stop_tape");
- int retry = 0;
- int result;
-
- do {
- result = ftape_command_wait(QIC_STOP_TAPE, timeout.stop, pstatus);
- if (result == 0) {
- if ((*pstatus & QIC_STATUS_READY) == 0) {
- result = -EIO;
- } else {
- tape_running = 0;
- }
- }
- } while (result < 0 && ++retry <= 3);
- if (result < 0) {
- TRACE(1, "failed ! (fatal)");
- }
- TRACE_EXIT;
- return result;
-}
-
-int ftape_dumb_stop(void)
-{
- TRACE_FUN(5, "ftape_dumb_stop");
- int result;
- int status;
-
- /* Abort current fdc operation if it's busy (probably read
- * or write operation pending) with a reset.
- */
- result = fdc_ready_wait(100 /* usec */ );
- if (result < 0) {
- TRACE(1, "aborting fdc operation");
- fdc_reset();
- }
- /* Reading id's after the last segment on a track may fail
- * but eventually the drive will become ready (logical eot).
- */
- result = ftape_report_drive_status(&status);
- location.known = 0;
- do {
- if (result == 0 && status & QIC_STATUS_READY) {
- /* Tape is not running any more.
- */
- TRACE(5, "tape already halted");
- check_bot_eot(status);
- tape_running = 0;
- } else if (tape_running) {
- /* Tape is (was) still moving.
- */
-#ifdef TESTING
- ftape_read_id();
-#endif
- result = stop_tape(&status);
- } else {
- /* Tape not yet ready but stopped.
- */
- result = ftape_ready_wait(timeout.pause, &status);
- }
- } while (tape_running);
-#ifndef TESTING
- location.known = 0;
-#endif
- TRACE_EXIT;
- return result;
-}
-
-/* Wait until runner has finished tail buffer.
- */
-int wait_segment(buffer_state_enum state)
-{
- TRACE_FUN(5, "wait_segment");
- int result = 0;
-
- while (buffer[tail].status == state) {
- /* First buffer still being worked on, wait up to timeout.
- */
- result = fdc_interrupt_wait(50 * SECOND);
- if (result < 0) {
- if (result != -EINTR) {
- TRACE(1, "fdc_interrupt_wait failed");
- result = -ETIME;
- }
- break;
- }
- if (fdc_setup_error) {
- TRACE(1, "setup error");
- /* recover... */
- result = -EIO;
- break;
- }
- }
- TRACE_EXIT;
- return result;
-}
-
-/* forward */ static int seek_forward(int segment_id);
-
-int fast_seek(int count, int reverse)
-{
- TRACE_FUN(5, "fast_seek");
- int result = 0;
- int status;
-
- if (count > 0) {
- /* If positioned at begin or end of tape, fast seeking needs
- * special treatment.
- * Starting from logical bot needs a (slow) seek to the first
- * segment before the high speed seek. Most drives do this
- * automatically but some older don't, so we treat them
- * all the same.
- * Starting from logical eot is even more difficult because
- * we cannot (slow) reverse seek to the last segment.
- * TO BE IMPLEMENTED.
- */
- inhibit_correction = 0;
- if (location.known &&
- ((location.bot && !reverse) ||
- (location.eot && reverse))) {
- if (!reverse) {
- /* (slow) skip to first segment on a track
- */
- seek_forward(location.track * segments_per_track);
- --count;
- } else {
- /* When seeking backwards from end-of-tape the number
- * of erased gaps found seems to be higher than expected.
- * Therefor the drive must skip some more segments than
- * calculated, but we don't know how many.
- * Thus we will prevent the re-calculation of offset
- * and overshoot when seeking backwards.
- */
- inhibit_correction = 1;
- count += 3; /* best guess */
- }
- }
- } else {
- TRACEx1(5, "warning: zero or negative count: %d", count);
- }
- if (count > 0) {
- int i;
- int nibbles = count > 255 ? 3 : 2;
-
- if (count > 4095) {
- TRACE(4, "skipping clipped at 4095 segment");
- count = 4095;
- }
- /* Issue this tape command first. */
- if (!reverse) {
- TRACEx1(4, "skipping %d segment(s)", count);
- result = ftape_command(nibbles == 3 ?
- QIC_SKIP_EXTENDED_FORWARD : QIC_SKIP_FORWARD);
- } else {
- TRACEx1(4, "backing up %d segment(s)", count);
- result = ftape_command(nibbles == 3 ?
- QIC_SKIP_EXTENDED_REVERSE : QIC_SKIP_REVERSE);
- }
- if (result < 0) {
- TRACE(4, "Skip command failed");
- } else {
- --count; /* 0 means one gap etc. */
- for (i = 0; i < nibbles; ++i) {
- if (result >= 0) {
- result = ftape_parameter(count & 15);
- count /= 16;
- }
- }
- result = ftape_ready_wait(timeout.rewind, &status);
- if (result >= 0) {
- tape_running = 0;
- }
- }
- }
- TRACE_EXIT;
- return result;
-}
-
-static int validate(int id)
-{
- /* Check to see if position found is off-track as reported once.
- * Because all tracks in one direction lie next to each other,
- * if off-track the error will be approximately 2 * segments_per_track.
- */
- if (location.track == -1) {
- return 1; /* unforeseen situation, don't generate error */
- } else {
- /* Use margin of segments_per_track on both sides because ftape
- * needs some margin and the error we're looking for is much larger !
- */
- int lo = (location.track - 1) * segments_per_track;
- int hi = (location.track + 2) * segments_per_track;
-
- return (id >= lo && id < hi);
- }
-}
-
-static int seek_forward(int segment_id)
-{
- TRACE_FUN(5, "seek_forward");
- int failures = 0;
- int result = 0;
- int count;
- static int margin = 1; /* fixed: stop this before target */
- static int overshoot = 1;
- static int min_count = 8;
- int expected = -1;
- int target = segment_id - margin;
- int fast_seeking;
-
- if (!location.known) {
- TRACE(1, "fatal: cannot seek from unknown location");
- result = -EIO;
- } else if (!validate(segment_id)) {
- TRACE(1, "fatal: head off track (bad hardware?)");
- ftape_sleep(1 * SECOND);
- ftape_failure = 1;
- result = -EIO;
- } else {
- int prev_segment = location.segment;
-
- TRACEx4(4, "from %d/%d to %d/0 - %d", location.segment,
- location.sector, segment_id, margin);
- count = target - location.segment - overshoot;
- fast_seeking = (count > min_count + (location.bot ? 1 : 0));
- if (fast_seeking) {
- TRACEx1(5, "fast skipping %d segments", count);
- expected = segment_id - margin;
- fast_seek(count, 0);
- }
- if (!tape_running) {
- logical_forward();
- }
- while (location.segment < segment_id) {
- /* This requires at least one sector in a (bad) segment to
- * have a valid and readable sector id !
- * It looks like this is not guaranteed, so we must try
- * to find a way to skip an EMPTY_SEGMENT. !!! FIXME !!!
- */
- if (ftape_read_id() < 0 || !location.known) {
- location.known = 0;
- if (!tape_running || ++failures > SECTORS_PER_SEGMENT ||
- (current->signal & _DONT_BLOCK)) {
- TRACE(1, "read_id failed completely");
- result = -EIO;
- break;
- } else {
- TRACEx1(5, "read_id failed, retry (%d)", failures);
- }
- } else if (fast_seeking) {
- TRACEx4(4, "ended at %d/%d (%d,%d)", location.segment,
- location.sector, overshoot, inhibit_correction);
- if (!inhibit_correction &&
- (location.segment < expected ||
- location.segment > expected + margin)) {
- int error = location.segment - expected;
- TRACEx2(4, "adjusting overshoot from %d to %d",
- overshoot, overshoot + error);
- overshoot += error;
- /* All overshoots have the same direction, so it should
- * never become negative, but who knows.
- */
- if (overshoot < -5 || overshoot > 10) {
- if (overshoot < 0) {
- overshoot = -5; /* keep sane value */
- } else {
- overshoot = 10; /* keep sane value */
- }
- TRACEx1(4, "clipped overshoot to %d", overshoot);
- }
- }
- fast_seeking = 0;
- }
- if (location.known) {
- if (location.segment > prev_segment + 1) {
- TRACEx1(4, "missed segment %d while skipping", prev_segment + 1);
- }
- prev_segment = location.segment;
- }
- }
- if (location.segment > segment_id) {
- TRACEx2(4, "failed: skip ended at segment %d/%d",
- location.segment, location.sector);
- result = -EIO;
- }
- }
- TRACE_EXIT;
- return result;
-}
-
-static int skip_reverse(int segment_id, int *pstatus)
-{
- TRACE_FUN(5, "skip_reverse");
- int result = 0;
- int failures = 0;
- static int overshoot = 1;
- static int min_rewind = 2; /* 1 + overshoot */
- static const int margin = 1; /* stop this before target */
- int expected = 0;
- int count;
- int short_seek;
- int target = segment_id - margin;
-
- if (location.known && !validate(segment_id)) {
- TRACE(1, "fatal: head off track (bad hardware?)");
- ftape_sleep(1 * SECOND);
- ftape_failure = 1;
- result = -EIO;
- } else
- do {
- if (!location.known) {
- TRACE(-1, "warning: location not known");
- }
- TRACEx4(4, "from %d/%d to %d/0 - %d",
- location.segment, location.sector, segment_id, margin);
- /* min_rewind == 1 + overshoot_when_doing_minimum_rewind
- * overshoot == overshoot_when_doing_larger_rewind
- * Initially min_rewind == 1 + overshoot, optimization
- * of both values will be done separately.
- * overshoot and min_rewind can be negative as both are
- * sums of three components:
- * any_overshoot == rewind_overshoot - stop_overshoot - start_overshoot
- */
- if (location.segment - target - (min_rewind - 1) < 1) {
- short_seek = 1;
- } else {
- count = location.segment - target - overshoot;
- short_seek = (count < 1);
- }
- if (short_seek) {
- count = 1; /* do shortest rewind */
- expected = location.segment - min_rewind;
- if (expected / segments_per_track != location.track) {
- expected = location.track * segments_per_track;
- }
- } else {
- expected = target;
- }
- fast_seek(count, 1);
- logical_forward();
- result = ftape_read_id();
- if (result == 0 && location.known) {
- TRACEx5(4, "ended at %d/%d (%d,%d,%d)", location.segment,
- location.sector, min_rewind, overshoot, inhibit_correction);
- if (!inhibit_correction &&
- (location.segment < expected ||
- location.segment > expected + margin)) {
- int error = expected - location.segment;
- if (short_seek) {
- TRACEx2(4, "adjusting min_rewind from %d to %d",
- min_rewind, min_rewind + error);
- min_rewind += error;
- if (min_rewind < -5) { /* is this right ? FIXME ! */
- min_rewind = -5; /* keep sane value */
- TRACEx1(4, "clipped min_rewind to %d", min_rewind);
- }
- } else {
- TRACEx2(4, "adjusting overshoot from %d to %d",
- overshoot, overshoot + error);
- overshoot += error;
- if (overshoot < -5 || overshoot > 10) {
- if (overshoot < 0) {
- overshoot = -5; /* keep sane value */
- } else {
- overshoot = 10; /* keep sane value */
- }
- TRACEx1(4, "clipped overshoot to %d", overshoot);
- }
- }
- }
- } else {
- if ((!tape_running && !location.known) ||
- ++failures > SECTORS_PER_SEGMENT) {
- TRACE(1, "read_id failed completely");
- result = -EIO;
- break;
- } else {
- TRACEx1(5, "ftape_read_id failed, retry (%d)", failures);
- }
- result = ftape_report_drive_status(pstatus);
- if (result < 0) {
- TRACEi(1, "ftape_report_drive_status failed with code", result);
- break;
- }
- }
- } while (location.segment > segment_id &&
- (current->signal & _DONT_BLOCK) == 0);
- if (location.known) {
- TRACEx2(4, "current location: %d/%d", location.segment, location.sector);
- }
- TRACE_EXIT;
- return result;
-}
-
-static int determine_position(void)
-{
- TRACE_FUN(5, "determine_position");
- int retry = 0;
- int fatal = 0;
- int status;
- int result;
-
- if (!tape_running) {
- /* This should only happen if tape is stopped by isr.
- */
- TRACE(5, "waiting for tape stop");
- result = ftape_ready_wait(timeout.pause, &status);
- if (result < 0) {
- TRACE(5, "drive still running (fatal)");
- tape_running = 1; /* ? */
- }
- } else {
- ftape_report_drive_status(&status);
- }
- if (status & QIC_STATUS_READY) {
- /* Drive must be ready to check error state !
- */
- TRACE(5, "drive is ready");
- if (status & QIC_STATUS_ERROR) {
- int error;
- int command;
-
- /* Report and clear error state, try to continue.
- */
- TRACE(5, "error status set");
- ftape_report_error(&error, &command, 1);
- ftape_ready_wait(timeout.reset, &status);
- tape_running = 0; /* ? */
- }
- if (check_bot_eot(status)) {
- if (location.bot) {
- if ((status & QIC_STATUS_READY) == 0) {
- /* tape moving away from bot/eot, let's see if we
- * can catch up with the first segment on this track.
- */
- } else {
- TRACE(5, "start tape from logical bot");
- logical_forward(); /* start moving */
- }
- } else {
- if ((status & QIC_STATUS_READY) == 0) {
- TRACE(4, "waiting for logical end of track");
- result = ftape_ready_wait(timeout.reset, &status);
- /* error handling needed ? */
- } else {
- TRACE(4, "tape at logical end of track");
- }
- }
- } else {
- TRACE(5, "start tape");
- logical_forward(); /* start moving */
- location.known = 0; /* not cleared by logical forward ! */
- }
- }
- if (!location.known) {
- /* tape should be moving now, start reading id's
- */
- TRACE(5, "location unknown");
- do {
- result = ftape_read_id();
- if (result < 0) {
- /* read-id somehow failed, tape may have reached end
- * or some other error happened.
- */
- TRACE(5, "read-id failed");
- ftape_report_drive_status(&status);
- if (status & QIC_STATUS_READY) {
- tape_running = 0;
- TRACEx1(4, "tape stopped for unknown reason ! status = 0x%02x",
- status);
- if (status & QIC_STATUS_ERROR) {
- fatal = 1;
- } else {
- if (check_bot_eot(status)) {
- result = 0;
- } else {
- fatal = 1; /* oops, tape stopped but not at end ! */
- }
- }
- }
- result = -EIO;
- }
- } while (result < 0 && !fatal && ++retry < SECTORS_PER_SEGMENT);
- } else {
- result = 0;
- }
- TRACEx1(5, "tape is positioned at segment %d", location.segment);
- TRACE_EXIT;
- return result;
-}
-
-/* Get the tape running and position it just before the
- * requested segment.
- * Seek tape-track and reposition as needed.
- */
-int ftape_start_tape(int segment_id, int sector_offset)
-{
- TRACE_FUN(5, "ftape_start_tape");
- int track = segment_id / segments_per_track;
- int result = -EIO;
- int status;
- static int last_segment = -1;
- static int bad_bus_timing = 0;
- /* number of segments passing the head between starting the tape
- * and being able to access the first sector.
- */
- static int start_offset = 1;
- int retry = 0;
-
- /* If sector_offset > 0, seek into wanted segment instead of
- * into previous.
- * This allows error recovery if a part of the segment is bad
- * (erased) causing the tape drive to generate an index pulse
- * thus causing a no-data error before the requested sector
- * is reached.
- */
- tape_running = 0;
- TRACEx3(4, "target segment: %d/%d%s", segment_id, sector_offset,
- buffer[head].retry > 0 ? " retry" : "");
- if (buffer[head].retry > 0) { /* this is a retry */
- if (!bad_bus_timing && ftape_data_rate == 1 &&
- history.overrun_errors - overrun_count_offset >= 8) {
- ftape_set_data_rate(ftape_data_rate + 1);
- bad_bus_timing = 1;
- TRACE(2, "reduced datarate because of excessive overrun errors");
- }
- }
- last_segment = segment_id;
- if (location.track != track || (might_be_off_track &&
- buffer[head].retry == 0)) {
- /* current track unknown or not equal to destination
- */
- ftape_ready_wait(timeout.seek, &status);
- ftape_seek_head_to_track(track);
- overrun_count_offset = history.overrun_errors;
- }
- do {
- if (!location.known) {
- determine_position();
- }
- /* Check if we are able to catch the requested segment in time.
- */
- if (location.known && location.segment >= segment_id -
- ((tape_running || location.bot) ? 0 : start_offset)) {
- /* Too far ahead (in or past target segment).
- */
- if (tape_running) {
- result = stop_tape(&status);
- if (result < 0) {
- TRACEi(1, "stop tape failed with code", result);
- break;
- }
- TRACE(5, "tape stopped");
- tape_running = 0;
- }
- TRACE(5, "repositioning");
- ++history.rewinds;
- if (segment_id % segments_per_track < start_offset) {
- /* If seeking to first segments on track better do a complete
- * rewind to logical begin of track to get a more steady tape
- * motion.
- */
- result = ftape_command_wait((location.track & 1) ?
- QIC_PHYSICAL_FORWARD :
- QIC_PHYSICAL_REVERSE,
- timeout.rewind, &status);
- check_bot_eot(status); /* update location */
- } else {
- result = skip_reverse(segment_id - start_offset, &status);
- }
- }
- if (!location.known) {
- TRACE(-1, "panic: location not known");
- result = -EIO;
- if ((current->signal & _DONT_BLOCK) || ftape_failure) {
- break;
- } else {
- continue;
- }
- }
- TRACEx2(4, "current segment: %d/%d", location.segment, location.sector);
- /* We're on the right track somewhere before the wanted segment.
- * Start tape movement if needed and skip to just before or inside
- * the requested segment. Keep tape running.
- */
- result = 0;
- if (location.segment < segment_id -
- ((tape_running || location.bot) ? 0 : start_offset)) {
- if (sector_offset > 0) {
- result = seek_forward(segment_id);
- } else {
- result = seek_forward(segment_id - 1);
- }
- }
- if (result == 0 &&
- location.segment != segment_id - (sector_offset > 0 ? 0 : 1)) {
- result = -EIO;
- }
- } while (result < 0 && !ftape_failure &&
- (current->signal & _DONT_BLOCK) == 0 &&
- ++retry <= 5);
- if (result < 0) {
- TRACE(1, "failed to reposition");
- }
- TRACE_EXIT;
- return result;
-}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen, slshen@lbl.gov