ftape-rw.c

linux-2.6.15.6

	TRACE_EXIT 0;
}

static int logical_forward(void)
{
	ftape_tape_running = 1;
	return ftape_command(QIC_LOGICAL_FORWARD);
}

int ftape_stop_tape(int *pstatus)
{
	int retry = 0;
	int result;
	TRACE_FUN(ft_t_flow);

	do {
		result = ftape_command_wait(QIC_STOP_TAPE,
					    ftape_timeout.stop, pstatus);
		if (result == 0) {
			if ((*pstatus & QIC_STATUS_READY) == 0) {
				result = -EIO;
			} else {
				ftape_tape_running = 0;
			}
		}
	} while (result < 0 && ++retry <= 3);
	if (result < 0) {
		TRACE(ft_t_err, "failed ! (fatal)");
	}
	TRACE_EXIT result;
}

int ftape_dumb_stop(void)
{
	int result;
	int status;
	TRACE_FUN(ft_t_flow);

	/*  Abort current fdc operation if it's busy (probably read
	 *  or write operation pending) with a reset.
	 */
	if (fdc_ready_wait(100 /* usec */) < 0) {
		TRACE(ft_t_noise, "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);
	ft_location.known = 0;
	do {
		if (result == 0 && status & QIC_STATUS_READY) {
			/* Tape is not running any more.
			 */
			TRACE(ft_t_noise, "tape already halted");
			check_bot_eot(status);
			ftape_tape_running = 0;
		} else if (ftape_tape_running) {
			/*  Tape is (was) still moving.
			 */
#ifdef TESTING
			ftape_read_id();
#endif
			result = ftape_stop_tape(&status);
		} else {
			/*  Tape not yet ready but stopped.
			 */
			result = ftape_ready_wait(ftape_timeout.pause,&status);
		}
	} while (ftape_tape_running
		 && !(sigtestsetmask(&current->pending.signal, _NEVER_BLOCK)));
#ifndef TESTING
	ft_location.known = 0;
#endif
	if (ft_runner_status == aborting || ft_runner_status == do_abort) {
		ft_runner_status = idle;
	}
	TRACE_EXIT result;
}

/*      Wait until runner has finished tail buffer.
 *
 */
int ftape_wait_segment(buffer_state_enum state)
{
	int status;
	int result = 0;
	TRACE_FUN(ft_t_flow);

	while (ft_buffer[ft_tail]->status == state) {
		TRACE(ft_t_flow, "state: %d", ft_buffer[ft_tail]->status);
		/*  First buffer still being worked on, wait up to timeout.
		 *
		 *  Note: we check two times for being killed. 50
		 *  seconds are quite long. Note that
		 *  fdc_interrupt_wait() is not killable by any
		 *  means. ftape_read_segment() wants us to return
		 *  -EINTR in case of a signal.  
		 */
		FT_SIGNAL_EXIT(_DONT_BLOCK);
		result = fdc_interrupt_wait(50 * FT_SECOND);
		FT_SIGNAL_EXIT(_DONT_BLOCK);
		if (result < 0) {
			TRACE_ABORT(result,
				    ft_t_err, "fdc_interrupt_wait failed");
		}
		if (fdc_setup_error) {
			/* recover... FIXME */
			TRACE_ABORT(-EIO, ft_t_err, "setup error");
		}
	}
	if (ft_buffer[ft_tail]->status != error) {
		TRACE_EXIT 0;
	}
	TRACE_CATCH(ftape_report_drive_status(&status),);
	TRACE(ft_t_noise, "ftape_report_drive_status: 0x%02x", status);
	if ((status & QIC_STATUS_READY) && 
	    (status & QIC_STATUS_ERROR)) {
		unsigned int error;
		qic117_cmd_t command;
		
		/*  Report and clear error state.
		 *  In case the drive can't operate at the selected
		 *  rate, select the next lower data rate.
		 */
		ftape_report_error(&error, &command, 1);
		if (error == 31 && command == QIC_LOGICAL_FORWARD) {
			/* drive does not accept this data rate */
			if (ft_data_rate > 250) {
				TRACE(ft_t_info,
				      "Probable data rate conflict");
				TRACE(ft_t_info,
				      "Lowering data rate to %d Kbps",
				      ft_data_rate / 2);
				ftape_half_data_rate();
				if (ft_buffer[ft_tail]->retry > 0) {
					/* give it a chance */
					--ft_buffer[ft_tail]->retry;
				}
			} else {
				/* no rate is accepted... */
				TRACE(ft_t_err, "We're dead :(");
			}
		} else {
			TRACE(ft_t_err, "Unknown error");
		}
		TRACE_EXIT -EIO;   /* g.p. error */
	}
	TRACE_EXIT 0;
}

/* forward */ static int seek_forward(int segment_id, int fast);

static int fast_seek(int count, int reverse)
{
	int result = 0;
	int status;
	TRACE_FUN(ft_t_flow);

	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 (ft_location.known &&
		    ((ft_location.bot && !reverse) ||
		     (ft_location.eot && reverse))) {
			if (!reverse) {
				/*  (slow) skip to first segment on a track
				 */
				seek_forward(ft_location.track * ft_segments_per_track, 0);
				--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 {
		TRACE(ft_t_flow, "warning: zero or negative count: %d", count);
	}
	if (count > 0) {
		int i;
		int nibbles = count > 255 ? 3 : 2;

		if (count > 4095) {
			TRACE(ft_t_noise, "skipping clipped at 4095 segment");
			count = 4095;
		}
		/* Issue this tape command first. */
		if (!reverse) {
			TRACE(ft_t_noise, "skipping %d segment(s)", count);
			result = ftape_command(nibbles == 3 ?
			   QIC_SKIP_EXTENDED_FORWARD : QIC_SKIP_FORWARD);
		} else {
			TRACE(ft_t_noise, "backing up %d segment(s)", count);
			result = ftape_command(nibbles == 3 ?
			   QIC_SKIP_EXTENDED_REVERSE : QIC_SKIP_REVERSE);
		}
		if (result < 0) {
			TRACE(ft_t_noise, "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(ftape_timeout.rewind, &status);
			if (result >= 0) {
				ftape_tape_running = 0;
			}
		}
	}
	TRACE_EXIT 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 * ft_segments_per_track.
	 */
	if (ft_location.track == -1) {
		return 1; /* unforseen situation, don't generate error */
	} else {
		/* Use margin of ft_segments_per_track on both sides
		 * because ftape needs some margin and the error we're
		 * looking for is much larger !
		 */
		int lo = (ft_location.track - 1) * ft_segments_per_track;
		int hi = (ft_location.track + 2) * ft_segments_per_track;

		return (id >= lo && id < hi);
	}
}

static int seek_forward(int segment_id, int fast)
{
	int failures = 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;
	int prev_segment = ft_location.segment;
	TRACE_FUN(ft_t_flow);

	if (!ft_location.known) {
		TRACE_ABORT(-EIO, ft_t_err,
			    "fatal: cannot seek from unknown location");
	}
	if (!validate(segment_id)) {
		ftape_sleep(1 * FT_SECOND);
		ft_failure = 1;
		TRACE_ABORT(-EIO, ft_t_err,
			    "fatal: head off track (bad hardware?)");
	}
	TRACE(ft_t_noise, "from %d/%d to %d/0 - %d",
	      ft_location.segment, ft_location.sector,segment_id,margin);
	count = target - ft_location.segment - overshoot;
	fast_seeking = (fast &&
			count > (min_count + (ft_location.bot ? 1 : 0)));
	if (fast_seeking) {
		TRACE(ft_t_noise, "fast skipping %d segments", count);
		expected = segment_id - margin;
		fast_seek(count, 0);
	}
	if (!ftape_tape_running) {
		logical_forward();
	}
	while (ft_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 || !ft_location.known ||
		    sigtestsetmask(&current->pending.signal, _DONT_BLOCK)) {
			ft_location.known = 0;
			if (!ftape_tape_running ||
			    ++failures > FT_SECTORS_PER_SEGMENT) {
				TRACE_ABORT(-EIO, ft_t_err,
					    "read_id failed completely");
			}
			FT_SIGNAL_EXIT(_DONT_BLOCK);
			TRACE(ft_t_flow, "read_id failed, retry (%d)",
			      failures);
			continue;
		}
		if (fast_seeking) {
			TRACE(ft_t_noise, "ended at %d/%d (%d,%d)",
			      ft_location.segment, ft_location.sector,
			      overshoot, inhibit_correction);
			if (!inhibit_correction &&
			    (ft_location.segment < expected ||
			     ft_location.segment > expected + margin)) {
				int error = ft_location.segment - expected;
				TRACE(ft_t_noise,
				      "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 > OVERSHOOT_LIMIT) {
					if (overshoot < 0) {
						/* keep sane value */
						overshoot = -5;
					} else {
						/* keep sane value */
						overshoot = OVERSHOOT_LIMIT;
					}
					TRACE(ft_t_noise,
					      "clipped overshoot to %d",
					      overshoot);
				}
			}
			fast_seeking = 0;
		}
		if (ft_location.known) {
			if (ft_location.segment > prev_segment + 1) {
				TRACE(ft_t_noise,
				      "missed segment %d while skipping",
				      prev_segment + 1);
			}
			prev_segment = ft_location.segment;
		}
	}
	if (ft_location.segment > segment_id) {
		TRACE_ABORT(-EIO,
			    ft_t_noise, "failed: skip ended at segment %d/%d",
			    ft_location.segment, ft_location.sector);
	}
	TRACE_EXIT 0;
}

static int skip_reverse(int segment_id, int *pstatus)
{
	int failures = 0;
	static int overshoot = 1;
	static int min_rewind = 2;	/* 1 + overshoot */
	static const int margin = 1;	/* stop this before target */