osst.c

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#if DEBUG
		if (jiffies - startwait >= 2*HZ/OSST_POLL_PER_SEC && notyetprinted)
		{
			printk (OSST_DEB_MSG "osst%d:D: Wait for frame %i (>%i): %i-%i %i (%i)\n",
				dev, curr, curr+minlast, STp->first_frame_position,
				STp->last_frame_position, STp->cur_frames, result);
			notyetprinted--;
		}
#endif
		set_current_state(TASK_INTERRUPTIBLE);
		schedule_timeout (HZ / OSST_POLL_PER_SEC);
	}
#if DEBUG
	printk (OSST_DEB_MSG "osst%d:D: Fail wait f fr %i (>%i): %i-%i %i: %3li.%li s\n",
		dev, curr, curr+minlast, STp->first_frame_position,
		STp->last_frame_position, STp->cur_frames,
		(jiffies-startwait)/HZ, (((jiffies-startwait)%HZ)*10)/HZ);
#endif	
	return -EBUSY;
}

/*
 * Read the next OnStream tape frame at the current location
 */
static int osst_read_frame(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt, int timeout)
{
	unsigned char	cmd[MAX_COMMAND_SIZE];
	Scsi_Request  * SRpnt;
	int		retval = 0;
#if DEBUG
	os_aux_t      * aux    = STp->buffer->aux;
	int		dev    = TAPE_NR(STp->devt);
#endif

	/* TODO: Error handling */
	if (STp->poll)
		retval = osst_wait_frame (STp, aSRpnt, STp->first_frame_position, 0, timeout);
#if 0// DEBUG
	printk ("osst_read: wait for frame returned %i\n", retval);
#endif
	
	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = READ_6;
	cmd[1] = 1;
	cmd[4] = 1;

#if DEBUG
	if (debugging)
	    printk(OSST_DEB_MSG "osst%d:D: Reading frame from OnStream tape\n", dev);
#endif
	SRpnt = osst_do_scsi(*aSRpnt, STp, cmd, OS_FRAME_SIZE, SCSI_DATA_READ,
				      STp->timeout, MAX_RETRIES, TRUE);
	*aSRpnt = SRpnt;
	if (!SRpnt)
	    return (-EBUSY);

	if ((STp->buffer)->syscall_result) {
	    retval = 1;
	    if (STp->read_error_frame == 0) {
		STp->read_error_frame = STp->first_frame_position;
#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Recording read error at %d\n", dev, STp->read_error_frame);
#endif
	    }
#if DEBUG
	    if (debugging)
		printk(OSST_DEB_MSG "osst%d:D: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
		   dev,
		   SRpnt->sr_sense_buffer[0], SRpnt->sr_sense_buffer[1],
		   SRpnt->sr_sense_buffer[2], SRpnt->sr_sense_buffer[3],
		   SRpnt->sr_sense_buffer[4], SRpnt->sr_sense_buffer[5],
		   SRpnt->sr_sense_buffer[6], SRpnt->sr_sense_buffer[7]);
#endif
	}
	else
	    STp->first_frame_position++;
#if DEBUG
	if (debugging) {
	   printk(OSST_DEB_MSG 
		"osst%d:D: AUX: %c%c%c%c UpdFrCt#%d Wpass#%d %s FrSeq#%d LogBlk#%d Qty=%d Sz=%d\n", dev,
			aux->application_sig[0], aux->application_sig[1],
			aux->application_sig[2], aux->application_sig[3], 
			ntohl(aux->update_frame_cntr), ntohs(aux->partition.wrt_pass_cntr),
			aux->frame_type==1?"EOD":aux->frame_type==2?"MARK":
			aux->frame_type==8?"HEADR":aux->frame_type==0x80?"DATA":"FILL", 
			ntohl(aux->frame_seq_num), ntohl(aux->logical_blk_num),
			ntohs(aux->dat.dat_list[0].blk_cnt), ntohl(aux->dat.dat_list[0].blk_sz) );
	   if (aux->frame_type==2)
		printk(OSST_DEB_MSG "osst%d:D: mark_cnt=%d, last_mark_ppos=%d, last_mark_lbn=%d\n", dev,
			ntohl(aux->filemark_cnt), ntohl(aux->last_mark_ppos), ntohl(aux->last_mark_lbn));
	   printk(OSST_DEB_MSG "osst%d:D: Exit read frame from OnStream tape with code %d\n", dev, retval);
	}
#endif
	return (retval);
}

static int osst_initiate_read(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt)
{
	ST_partstat   * STps   = &(STp->ps[STp->partition]);
	Scsi_Request  * SRpnt  ;
	unsigned char	cmd[MAX_COMMAND_SIZE];
	int		retval = 0;
#if DEBUG
	int		dev    = TAPE_NR(STp->devt);
#endif

	if (STps->rw != ST_READING) {         /* Initialize read operation */
		if (STps->rw == ST_WRITING) {
                        osst_flush_write_buffer(STp, aSRpnt);
			osst_flush_drive_buffer(STp, aSRpnt);
		}
		STps->rw = ST_READING;
		STp->frame_in_buffer = 0;

		/*
		 *      Issue a read 0 command to get the OnStream drive
                 *      read frames into its buffer.
		 */
		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = READ_6;
		cmd[1] = 1;

#if DEBUG
		printk(OSST_DEB_MSG "osst%d:D: Start Read Ahead on OnStream tape\n", dev);
#endif
		SRpnt   = osst_do_scsi(*aSRpnt, STp, cmd, 0, SCSI_DATA_NONE, STp->timeout, MAX_RETRIES, TRUE);
		*aSRpnt = SRpnt;
		retval  = STp->buffer->syscall_result;
	}

	return retval;
}

static int osst_get_logical_frame(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt, int frame_seq_number, int quiet)
{
	ST_partstat * STps  = &(STp->ps[STp->partition]);
	int           dev   = TAPE_NR(STp->devt);
	int           cnt   = 0,
		      bad   = 0,
		      past  = 0,
		      x,
		      position;

	/*
         * Search and wait for the next logical tape frame
	 */
	while (1) {
		if (cnt++ > 400) {
                        printk(KERN_ERR "osst%d:E: Couldn't find logical frame %d, aborting\n",
					    dev, frame_seq_number);
			if (STp->read_error_frame) {
				osst_set_frame_position(STp, aSRpnt, STp->read_error_frame, 0);
#if DEBUG
                        	printk(OSST_DEB_MSG "osst%d:D: Repositioning tape to bad frame %d\n",
						    dev, STp->read_error_frame);
#endif
				STp->read_error_frame = 0;
			}
			return (-EIO);
		}
#if DEBUG
		if (debugging)
			printk(OSST_DEB_MSG "osst%d:D: Looking for frame %d, attempt %d\n",
					  dev, frame_seq_number, cnt);
#endif
		if ( osst_initiate_read(STp, aSRpnt)
                || ( (!STp->frame_in_buffer) && osst_read_frame(STp, aSRpnt, 30) ) ) {
			if (STp->raw)
				return (-EIO);
			position = osst_get_frame_position(STp, aSRpnt);
			if (position >= 0xbae && position < 0xbb8)
				position = 0xbb8;
			else if (position > STp->eod_frame_ppos || ++bad == 10) {
				position = STp->read_error_frame - 1;
			}
			else {
				position += 39;
				cnt += 20;
			}
#if DEBUG
			printk(OSST_DEB_MSG "osst%d:D: Bad frame detected, positioning tape to block %d\n",
					 dev, position);
#endif
			osst_set_frame_position(STp, aSRpnt, position, 0);
			continue;
		}
		if (osst_verify_frame(STp, frame_seq_number, quiet))
			break;
		if (osst_verify_frame(STp, -1, quiet)) {
			x = ntohl(STp->buffer->aux->frame_seq_num);
			if (STp->fast_open) {
				printk(KERN_WARNING
				       "osst%d:W: Found logical frame %d instead of %d after fast open\n",
				       dev, x, frame_seq_number);
				STp->header_ok = 0;
				STp->read_error_frame = 0;
				return (-EIO);
			}
			if (x > frame_seq_number) {
				if (++past > 3) {
					/* positioning backwards did not bring us to the desired frame */
					position = STp->read_error_frame - 1;
				}
				else {
			        	position = osst_get_frame_position(STp, aSRpnt)
					         + frame_seq_number - x - 1;

					if (STp->first_frame_position >= 3000 && position < 3000)
						position -= 10;
				}
#if DEBUG
                                printk(OSST_DEB_MSG
				       "osst%d:D: Found logical frame %d while looking for %d: back up %d\n",
						dev, x, frame_seq_number,
					       	STp->first_frame_position - position);
#endif
                        	osst_set_frame_position(STp, aSRpnt, position, 0);
				cnt += 10;
			}
			else
				past = 0;
		}
		if (osst_get_frame_position(STp, aSRpnt) == 0xbaf) {
#if DEBUG
			printk(OSST_DEB_MSG "osst%d:D: Skipping config partition\n", dev);
#endif
			osst_set_frame_position(STp, aSRpnt, 0xbb8, 0);
			cnt--;
		}
		STp->frame_in_buffer = 0;
	}
	if (cnt > 1) {
		STp->recover_count++;
		STp->recover_erreg++;
		printk(KERN_WARNING "osst%d:I: Don't worry, Read error at position %d recovered\n", 
					dev, STp->read_error_frame);
 	}
	STp->read_count++;

#if DEBUG
	if (debugging || STps->eof)
		printk(OSST_DEB_MSG
			"osst%d:D: Exit get logical frame (%d=>%d) from OnStream tape with code %d\n",
			dev, frame_seq_number, STp->frame_seq_number, STps->eof);
#endif
	STp->fast_open = FALSE;
	STp->read_error_frame = 0;
	return (STps->eof);
}

static int osst_seek_logical_blk(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt, int logical_blk_num)
{
        ST_partstat * STps = &(STp->ps[STp->partition]);
	int	dev        = TAPE_NR(STp->devt);
	int	retries    = 0;
	int	frame_seq_estimate, ppos_estimate, move;
	
	if (logical_blk_num < 0) logical_blk_num = 0;
#if DEBUG
	printk(OSST_DEB_MSG "osst%d:D: Seeking logical block %d (now at %d, size %d%c)\n",
				dev, logical_blk_num, STp->logical_blk_num, 
				STp->block_size<1024?STp->block_size:STp->block_size/1024,
				STp->block_size<1024?'b':'k');
#endif
	/* Do we know where we are? */
	if (STps->drv_block >= 0) {
		move                = logical_blk_num - STp->logical_blk_num;
		if (move < 0) move -= (OS_DATA_SIZE / STp->block_size) - 1;
		move               /= (OS_DATA_SIZE / STp->block_size);
		frame_seq_estimate  = STp->frame_seq_number + move;
	} else
		frame_seq_estimate  = logical_blk_num * STp->block_size / OS_DATA_SIZE;

	if (frame_seq_estimate < 2980) ppos_estimate = frame_seq_estimate + 10;
	else			       ppos_estimate = frame_seq_estimate + 20;
	while (++retries < 10) {
	   if (ppos_estimate > STp->eod_frame_ppos-2) {
	       frame_seq_estimate += STp->eod_frame_ppos - 2 - ppos_estimate;
	       ppos_estimate       = STp->eod_frame_ppos - 2;
	   }
	   if (frame_seq_estimate < 0) {
	       frame_seq_estimate = 0;
	       ppos_estimate      = 10;
	   }
	   osst_set_frame_position(STp, aSRpnt, ppos_estimate, 0);
	   if (osst_get_logical_frame(STp, aSRpnt, frame_seq_estimate, 1) >= 0) {
	      /* we've located the estimated frame, now does it have our block? */
	      if (logical_blk_num <  STp->logical_blk_num ||
	          logical_blk_num >= STp->logical_blk_num + ntohs(STp->buffer->aux->dat.dat_list[0].blk_cnt)) {
		 if (STps->eof == ST_FM_HIT)
		    move = logical_blk_num < STp->logical_blk_num? -2 : 1;
		 else {
		    move                = logical_blk_num - STp->logical_blk_num;
		    if (move < 0) move -= (OS_DATA_SIZE / STp->block_size) - 1;
		    move               /= (OS_DATA_SIZE / STp->block_size);
		 }
#if DEBUG
		 printk(OSST_DEB_MSG
			"osst%d:D: Seek retry %d at ppos %d fsq %d (est %d) lbn %d (need %d) move %d\n",
				dev, retries, ppos_estimate, STp->frame_seq_number, frame_seq_estimate, 
				STp->logical_blk_num, logical_blk_num, move);
#endif
		 frame_seq_estimate += move;
		 ppos_estimate      += move;
		 continue;
	      } else {
		 STp->buffer->read_pointer  = (logical_blk_num - STp->logical_blk_num) * STp->block_size;
		 STp->buffer->buffer_bytes -= STp->buffer->read_pointer;
		 STp->logical_blk_num       =  logical_blk_num;
#if DEBUG
		 printk(OSST_DEB_MSG 
			"osst%d:D: Seek success at ppos %d fsq %d in_buf %d, bytes %d, ptr %d*%d\n",
				dev, ppos_estimate, STp->frame_seq_number, STp->frame_in_buffer, 
				STp->buffer->buffer_bytes, STp->buffer->read_pointer / STp->block_size, 
				STp->block_size);
#endif
		 STps->drv_file = ntohl(STp->buffer->aux->filemark_cnt);
		 if (STps->eof == ST_FM_HIT) {
		     STps->drv_file++;
		     STps->drv_block = 0;
		 } else {
		     STps->drv_block = ntohl(STp->buffer->aux->last_mark_lbn)?
					  STp->logical_blk_num -
					     (STps->drv_file ? ntohl(STp->buffer->aux->last_mark_lbn) + 1 : 0):
					-1;
		 }
		 STps->eof = (STp->first_frame_position >= STp->eod_frame_ppos)?ST_EOD:ST_NOEOF;
		 return 0;
	      }
	   }
	   if (osst_get_logical_frame(STp, aSRpnt, -1, 1) < 0)
	      goto error;
	   /* we are not yet at the estimated frame, adjust our estimate of its physical position */
#if DEBUG
	   printk(OSST_DEB_MSG "osst%d:D: Seek retry %d at ppos %d fsq %d (est %d) lbn %d (need %d)\n", 
			   dev, retries, ppos_estimate, STp->frame_seq_number, frame_seq_estimate, 
			   STp->logical_blk_num, logical_blk_num);
#endif
	   if (frame_seq_estimate != STp->frame_seq_number)
	      ppos_estimate += frame_seq_estimate - STp->frame_seq_number;
	   else
	      break;
	}
error:
	printk(KERN_ERR "osst%d:E: Couldn't seek to logical block %d (at %d), %d retries\n", 
			    dev, logical_blk_num, STp->logical_blk_num, retries);
	return (-EIO);
}

/* The values below are based on the OnStream frame payload size of 32K == 2**15,
 * that is, OSST_FRAME_SHIFT + OSST_SECTOR_SHIFT must be 15. With a minimum block
 * size of 512 bytes, we need to be able to resolve 32K/512 == 64 == 2**6 positions
 * inside each frame. Finaly, OSST_SECTOR_MASK == 2**OSST_FRAME_SHIFT - 1.
 */
#define OSST_FRAME_SHIFT  6
#define OSST_SECTOR_SHIFT 9
#define OSST_SECTOR_MASK  0x03F

static int osst_get_sector(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt)
{
	int	sector;
#if DEBUG
	int	dev = TAPE_NR(STp->devt);
	
	printk(OSST_DEB_MSG 
		"osst%d:D: Positioned at ppos %d, frame %d, lbn %d, file %d, blk %d, %cptr %d, eof %d\n",
		dev, STp->first_frame_position, STp->frame_seq_number, STp->logical_blk_num,
		STp->ps[STp->partition].drv_file, STp->ps[STp->partition].drv_block, 
		STp->ps[STp->partition].rw == ST_WRITING?'w':'r',
		STp->ps[STp->partition].rw == ST_WRITING?STp->buffer->buffer_bytes:
		STp->buffer->read_pointer, STp->ps[STp->partition].eof);
#endif
	/* do we know where we are inside a file? */
	if (STp->ps[STp->partition].drv_block >= 0) {
		sector = (STp->frame_in_buffer ? STp->first_frame_position-1 :
				STp->first_frame_position) << OSST_FRAME_SHIFT;
		if (STp->ps[STp->partition].rw == ST_WRITING)
		       	sector |= (STp->buffer->buffer_bytes >> OSST_SECTOR_SHIFT) & OSST_SECTOR_MASK;
		else
	       		sector |= (STp->buffer->read_pointer >> OSST_SECTOR_SHIFT) & OSST_SECTOR_MASK;
	} else {
		sector = osst_get_frame_position(STp, aSRpnt);
		if (sector > 0)
			sector <<= OSST_FRAME_SHIFT;
	}
	return sector;
}

static int osst_seek_sector(OS_Scsi_Tape * STp, Scsi_Request ** aSRpnt, int sector)
{
        ST_partstat   * STps   = &(STp->ps[STp->partition]);
	int		frame  = sector >> OSST_FRAME_SHIFT,
			offset = (sector & OSST_SECTOR_MASK) << OSST_SECTOR_SHIFT, 
			r;
#if DEBUG
	int		dev    = TAPE_NR(STp->devt);

	printk(OSST_DEB_MSG "osst%d:D: Seeking sector %d in frame %d at offset %d\n",
				dev, sector, frame, offset);