osst.c

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		osst_set_frame_position(STp, aSRpnt, frame + STp->cur_frames + pending, 0);
		retval = -EIO;
		break;
	   case OS_WRITE_HEADER:
		printk(KERN_WARNING "osst%d:I: Bad frame in header partition, skipped\n", dev);
		retval = osst_read_back_buffer_and_rewrite(STp, aSRpnt, frame, 1, pending);
		break;
	   default:
		printk(KERN_INFO "osst%d:I: Bad frame in filler, ignored\n", dev);
		osst_set_frame_position(STp, aSRpnt, frame + STp->cur_frames + pending, 0);
	}
	osst_get_frame_position(STp, aSRpnt);
#if DEBUG
	printk(OSST_DEB_MSG "osst%d:D: Positioning complete, cur_frames %d, pos %d, tape pos %d\n", 
			dev, STp->cur_frames, STp->first_frame_position, STp->last_frame_position);
	printk(OSST_DEB_MSG "osst%d:D: next logical frame to write: %d\n", dev, STp->logical_blk_num);
#endif
	if (retval == 0) {
		STp->recover_count++;
		STp->recover_erreg++;
	}
	STps->rw = rw_state;
	return retval;
}

static int osst_space_over_filemarks_backward(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt,
								 int mt_op, int mt_count)
{
	int     dev = TAPE_NR(STp->devt);
	int     cnt;
	int     last_mark_ppos = -1;

#if DEBUG
	printk(OSST_DEB_MSG "osst%d:D: Reached space_over_filemarks_backwards %d %d\n", dev, mt_op, mt_count);
#endif
	if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks_bwd\n", dev);
#endif
		return -EIO;
	}
	if (STp->linux_media_version >= 4) {
		/*
		 * direct lookup in header filemark list
		 */
		cnt = ntohl(STp->buffer->aux->filemark_cnt);
		if (STp->header_ok                         && 
		    STp->header_cache != NULL              &&
		    (cnt - mt_count)  >= 0                 &&
		    (cnt - mt_count)   < OS_FM_TAB_MAX     &&
		    (cnt - mt_count)   < STp->filemark_cnt &&
		    STp->header_cache->dat_fm_tab.fm_tab_ent[cnt-1] == STp->buffer->aux->last_mark_ppos)

			last_mark_ppos = ntohl(STp->header_cache->dat_fm_tab.fm_tab_ent[cnt - mt_count]);
#if DEBUG
		if (STp->header_cache == NULL || (cnt - mt_count) < 0 || (cnt - mt_count) >= OS_FM_TAB_MAX)
			printk(OSST_DEB_MSG "osst%d:D: Filemark lookup fail due to %s\n", dev,
			       STp->header_cache == NULL?"lack of header cache":"count out of range");
		else
			printk(OSST_DEB_MSG "osst%d:D: Filemark lookup: prev mark %d (%s), skip %d to %d\n",
				dev, cnt,
				((cnt == -1 && ntohl(STp->buffer->aux->last_mark_ppos) == -1) ||
				 (STp->header_cache->dat_fm_tab.fm_tab_ent[cnt-1] ==
					 STp->buffer->aux->last_mark_ppos))?"match":"error",
			       mt_count, last_mark_ppos);
#endif
		if (last_mark_ppos > 10 && last_mark_ppos < STp->eod_frame_ppos) {
			osst_position_tape_and_confirm(STp, aSRpnt, last_mark_ppos);
			if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
				printk(OSST_DEB_MSG 
					"osst%d:D: Couldn't get logical blk num in space_filemarks\n", dev);
#endif
				return (-EIO);
			}
			if (STp->buffer->aux->frame_type != OS_FRAME_TYPE_MARKER) {
				printk(KERN_WARNING "osst%d:W: Expected to find marker at ppos %d, not found\n",
						 dev, last_mark_ppos);
				return (-EIO);
			}
			if (mt_op == MTBSFM) {
				STp->frame_seq_number++;
				STp->frame_in_buffer  = 0;
				STp->logical_blk_num += ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt);
			}
			return 0;
		}
#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Reverting to scan filemark backwards\n", dev);
#endif
	}
	cnt = 0;
	while (cnt != mt_count) {
		last_mark_ppos = ntohl(STp->buffer->aux->last_mark_ppos);
		if (last_mark_ppos == -1)
			return (-EIO);
#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Positioning to last mark at %d\n", dev, last_mark_ppos);
#endif
		osst_position_tape_and_confirm(STp, aSRpnt, last_mark_ppos);
		cnt++;
		if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
			printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks\n", dev);
#endif
			return (-EIO);
		}
		if (STp->buffer->aux->frame_type != OS_FRAME_TYPE_MARKER) {
			printk(KERN_WARNING "osst%d:W: Expected to find marker at ppos %d, not found\n",
					 dev, last_mark_ppos);
			return (-EIO);
		}
	}
	if (mt_op == MTBSFM) {
		STp->frame_seq_number++;
		STp->frame_in_buffer  = 0;
		STp->logical_blk_num += ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt);
	}
	return 0;
}

/*
 * ADRL 1.1 compatible "slow" space filemarks fwd version
 *
 * Just scans for the filemark sequentially.
 */
static int osst_space_over_filemarks_forward_slow(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt,
								     int mt_op, int mt_count)
{
	int	cnt = 0;
#if DEBUG
	int	dev = TAPE_NR(STp->devt);

	printk(OSST_DEB_MSG "osst%d:D: Reached space_over_filemarks_forward_slow %d %d\n", dev, mt_op, mt_count);
#endif
	if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks_fwd\n", dev);
#endif
		return (-EIO);
	}
	while (1) {
		if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
			printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks\n", dev);
#endif
			return (-EIO);
		}
		if (STp->buffer->aux->frame_type == OS_FRAME_TYPE_MARKER)
			cnt++;
		if (STp->buffer->aux->frame_type == OS_FRAME_TYPE_EOD) {
#if DEBUG
			printk(OSST_DEB_MSG "osst%d:D: space_fwd: EOD reached\n", dev);
#endif
			if (STp->first_frame_position > STp->eod_frame_ppos+1) {
#if DEBUG
				printk(OSST_DEB_MSG "osst%d:D: EOD position corrected (%d=>%d)\n",
					       	dev, STp->eod_frame_ppos, STp->first_frame_position-1);
#endif
				STp->eod_frame_ppos = STp->first_frame_position-1;
			}
			return (-EIO);
		}
		if (cnt == mt_count)
			break;
		STp->frame_in_buffer = 0;
	}
	if (mt_op == MTFSF) {
		STp->frame_seq_number++;
		STp->frame_in_buffer  = 0;
		STp->logical_blk_num += ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt);
	}
	return 0;
}

/*
 * Fast linux specific version of OnStream FSF
 */
static int osst_space_over_filemarks_forward_fast(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt,
								     int mt_op, int mt_count)
{
	int	dev = TAPE_NR(STp->devt);
	int	cnt = 0,
		next_mark_ppos = -1;

#if DEBUG
	printk(OSST_DEB_MSG "osst%d:D: Reached space_over_filemarks_forward_fast %d %d\n", dev, mt_op, mt_count);
#endif
	if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks_fwd\n", dev);
#endif
		return (-EIO);
	}

	if (STp->linux_media_version >= 4) {
		/*
		 * direct lookup in header filemark list
		 */
		cnt = ntohl(STp->buffer->aux->filemark_cnt) - 1;
		if (STp->header_ok                         && 
		    STp->header_cache != NULL              &&
		    (cnt + mt_count)   < OS_FM_TAB_MAX     &&
		    (cnt + mt_count)   < STp->filemark_cnt &&
		    ((cnt == -1 && ntohl(STp->buffer->aux->last_mark_ppos) == -1) ||
		     (STp->header_cache->dat_fm_tab.fm_tab_ent[cnt] == STp->buffer->aux->last_mark_ppos)))

			next_mark_ppos = ntohl(STp->header_cache->dat_fm_tab.fm_tab_ent[cnt + mt_count]);
#if DEBUG
		if (STp->header_cache == NULL || (cnt + mt_count) >= OS_FM_TAB_MAX)
			printk(OSST_DEB_MSG "osst%d:D: Filemark lookup fail due to %s\n", dev,
			       STp->header_cache == NULL?"lack of header cache":"count out of range");
		else
			printk(OSST_DEB_MSG "osst%d:D: Filemark lookup: prev mark %d (%s), skip %d to %d\n",
			       dev, cnt,
			       ((cnt == -1 && ntohl(STp->buffer->aux->last_mark_ppos) == -1) ||
				(STp->header_cache->dat_fm_tab.fm_tab_ent[cnt] ==
					 STp->buffer->aux->last_mark_ppos))?"match":"error",
			       mt_count, next_mark_ppos);
#endif
		if (next_mark_ppos <= 10 || next_mark_ppos > STp->eod_frame_ppos) {
#if DEBUG
			printk(OSST_DEB_MSG "osst%d:D: Reverting to slow filemark space\n", dev);
#endif
			return osst_space_over_filemarks_forward_slow(STp, aSRpnt, mt_op, mt_count);
		} else {
			osst_position_tape_and_confirm(STp, aSRpnt, next_mark_ppos);
			if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
				printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks\n",
						 dev);
#endif
				return (-EIO);
			}
			if (STp->buffer->aux->frame_type != OS_FRAME_TYPE_MARKER) {
				printk(KERN_WARNING "osst%d:W: Expected to find marker at ppos %d, not found\n",
						 dev, next_mark_ppos);
				return (-EIO);
			}
			if (ntohl(STp->buffer->aux->filemark_cnt) != cnt + mt_count) {
				printk(KERN_WARNING "osst%d:W: Expected to find marker %d at ppos %d, not %d\n",
						 dev, cnt+mt_count, next_mark_ppos,
						 ntohl(STp->buffer->aux->filemark_cnt));
       				return (-EIO);
			}
		}
	} else {
		/*
		 * Find nearest (usually previous) marker, then jump from marker to marker
		 */
		while (1) {
			if (STp->buffer->aux->frame_type == OS_FRAME_TYPE_MARKER)
				break;
			if (STp->buffer->aux->frame_type == OS_FRAME_TYPE_EOD) {
#if DEBUG
				printk(OSST_DEB_MSG "osst%d:D: space_fwd: EOD reached\n", dev);
#endif
				return (-EIO);
			}
			if (ntohl(STp->buffer->aux->filemark_cnt) == 0) {
				if (STp->first_mark_ppos == -1) {
#if DEBUG
					printk(OSST_DEB_MSG "osst%d:D: Reverting to slow filemark space\n", dev);
#endif
					return osst_space_over_filemarks_forward_slow(STp, aSRpnt, mt_op, mt_count);
				}
				osst_position_tape_and_confirm(STp, aSRpnt, STp->first_mark_ppos);
				if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
					printk(OSST_DEB_MSG
					       "osst%d:D: Couldn't get logical blk num in space_filemarks_fwd_fast\n",
					       dev);
#endif
					return (-EIO);
				}
				if (STp->buffer->aux->frame_type != OS_FRAME_TYPE_MARKER) {
					printk(KERN_WARNING "osst%d:W: Expected to find filemark at %d\n",
							 dev, STp->first_mark_ppos);
					return (-EIO);
				}
			} else {
				if (osst_space_over_filemarks_backward(STp, aSRpnt, MTBSF, 1) < 0)
					return (-EIO);
				mt_count++;
			}
		}
		cnt++;
		while (cnt != mt_count) {
			next_mark_ppos = ntohl(STp->buffer->aux->next_mark_ppos);
			if (!next_mark_ppos || next_mark_ppos > STp->eod_frame_ppos) {
#if DEBUG
				printk(OSST_DEB_MSG "osst%d:D: Reverting to slow filemark space\n", dev);
#endif
				return osst_space_over_filemarks_forward_slow(STp, aSRpnt, mt_op, mt_count - cnt);
			}
#if DEBUG
			else printk(OSST_DEB_MSG "osst%d:D: Positioning to next mark at %d\n", dev, next_mark_ppos);
#endif
			osst_position_tape_and_confirm(STp, aSRpnt, next_mark_ppos);
			cnt++;
			if (osst_get_logical_frame(STp, aSRpnt, -1, 0) < 0) {
#if DEBUG
				printk(OSST_DEB_MSG "osst%d:D: Couldn't get logical blk num in space_filemarks\n",
						 dev);
#endif
				return (-EIO);
			}
			if (STp->buffer->aux->frame_type != OS_FRAME_TYPE_MARKER) {
				printk(KERN_WARNING "osst%d:W: Expected to find marker at ppos %d, not found\n",
						 dev, next_mark_ppos);
				return (-EIO);
			}
		}
	}
	if (mt_op == MTFSF) {
		STp->frame_seq_number++;
		STp->frame_in_buffer  = 0;
		STp->logical_blk_num += ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt);
	}
	return 0;
}

/*
 * In debug mode, we want to see as many errors as possible
 * to test the error recovery mechanism.
 */
#if DEBUG
static void osst_set_retries(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt, int retries)
{
	unsigned char	cmd[MAX_COMMAND_SIZE];
	Scsi_Request     * SRpnt  = * aSRpnt;
	int		dev  = TAPE_NR(STp->devt);

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = MODE_SELECT;
	cmd[1] = 0x10;
	cmd[4] = NUMBER_RETRIES_PAGE_LENGTH + MODE_HEADER_LENGTH;

	(STp->buffer)->b_data[0] = cmd[4] - 1;
	(STp->buffer)->b_data[1] = 0;			/* Medium Type - ignoring */
	(STp->buffer)->b_data[2] = 0;			/* Reserved */
	(STp->buffer)->b_data[3] = 0;			/* Block Descriptor Length */
	(STp->buffer)->b_data[MODE_HEADER_LENGTH + 0] = NUMBER_RETRIES_PAGE | (1 << 7);
	(STp->buffer)->b_data[MODE_HEADER_LENGTH + 1] = 2;
	(STp->buffer)->b_data[MODE_HEADER_LENGTH + 2] = 4;
	(STp->buffer)->b_data[MODE_HEADER_LENGTH + 3] = retries;

	if (debugging)
	    printk(OSST_DEB_MSG "osst%d:D: Setting number of retries on OnStream tape to %d\n", dev, retries);

	SRpnt = osst_do_scsi(SRpnt, STp, cmd, cmd[4], SCSI_DATA_WRITE, STp->timeout, 0, TRUE);
	*aSRpnt = SRpnt;

	if ((STp->buffer)->syscall_result)
	    printk (KERN_ERR "osst%d:D: Couldn't set retries to %d\n", dev, retries);
}
#endif


static int osst_write_filemark(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt)
{
	int	result;
	int	this_mark_ppos = STp->first_frame_position;
	int	this_mark_lbn  = STp->logical_blk_num;
#if DEBUG
	int	dev = TAPE_NR(STp->devt);
#endif

	if (STp->raw) return 0;

	STp->write_type = OS_WRITE_NEW_MARK;
#if DEBUG
	printk(OSST_DEB_MSG "osst%d:D: Writing Filemark %i at fppos %d (fseq %d, lblk %d)\n", 
	       dev, STp->filemark_cnt, this_mark_ppos, STp->frame_seq_number, this_mark_lbn);
#endif
	STp->dirty = 1;
	result  = osst_flush_write_buffer(STp, aSRpnt);
	result |= osst_flush_drive_buffer(STp, aSRpnt);
	STp->last_mark_ppos = this_mark_ppos;
	STp->last_mark_lbn  = this_mark_lbn;
	if (STp->header_cache != NULL && STp->filemark_cnt < OS_FM_TAB_MAX)
		STp->header_cache->dat_fm_tab.fm_tab_ent[STp->filemark_cnt] = htonl(this_mark_ppos);
	if (STp->filemark_cnt++ == 0)
		STp->first_mark_ppos = this_mark_ppos;
	return result;
}

static int osst_write_eod(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt)
{
	int	result;
#if DEBUG
	int	dev = TAPE_NR(STp->devt);
#endif

	if (STp->raw