st.c

Linux Kernel 2.6.9 for OMAP1710

	}

	STm = &(STp->modes[STp->current_mode]);
	STps = &(STp->ps[STp->partition]);

	if (STp->write_prot) {
		retval = (-EACCES);
		goto out;
	}


	if (STps->rw == ST_READING) {
		retval = flush_buffer(STp, 0);
		if (retval)
			goto out;
		STps->rw = ST_WRITING;
	} else if (STps->rw != ST_WRITING &&
		   STps->drv_file == 0 && STps->drv_block == 0) {
		if ((retval = set_mode_densblk(STp, STm)) < 0)
			goto out;
		if (STm->default_compression != ST_DONT_TOUCH &&
		    !(STp->compression_changed)) {
			if (st_compression(STp, (STm->default_compression == ST_YES))) {
				printk(KERN_WARNING "%s: Can't set default compression.\n",
				       name);
				if (modes_defined) {
					retval = (-EINVAL);
					goto out;
				}
			}
		}
	}

	STbp = STp->buffer;
	if (STbp->writing) {
		write_behind_check(STp);
		if (STbp->syscall_result) {
                        DEBC(printk(ST_DEB_MSG "%s: Async write error (write) %x.\n",
                                    name, STbp->midlevel_result));
			if (STbp->midlevel_result == INT_MAX)
				STps->eof = ST_EOM_OK;
			else
				STps->eof = ST_EOM_ERROR;
		}
	}

	if (STps->eof == ST_EOM_OK) {
		STps->eof = ST_EOD_1;  /* allow next write */
		retval = (-ENOSPC);
		goto out;
	}
	else if (STps->eof == ST_EOM_ERROR) {
		retval = (-EIO);
		goto out;
	}

	/* Check the buffer readability in cases where copy_user might catch
	   the problems after some tape movement. */
	if (STp->block_size != 0 &&
	    !STbp->do_dio &&
	    (copy_from_user(&i, buf, 1) != 0 ||
	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
		retval = (-EFAULT);
		goto out;
	}

	retval = setup_buffering(STp, buf, count, FALSE);
	if (retval)
		goto out;

	total = count;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = WRITE_6;
	cmd[1] = (STp->block_size != 0);

	STps->rw = ST_WRITING;

	b_point = buf;
	while (count > 0 && !retry_eot) {

		if (STbp->do_dio) {
			do_count = count;
		}
		else {
			if (STp->block_size == 0)
				do_count = count;
			else {
				do_count = STbp->buffer_blocks * STp->block_size -
					STbp->buffer_bytes;
				if (do_count > count)
					do_count = count;
			}

			i = append_to_buffer(b_point, STbp, do_count);
			if (i) {
				retval = i;
				goto out;
			}
		}
		count -= do_count;
		filp->f_pos += do_count;
		b_point += do_count;

		async_write = STp->block_size == 0 && !STbp->do_dio &&
			STm->do_async_writes && STps->eof < ST_EOM_OK;

		if (STp->block_size != 0 && STm->do_buffer_writes &&
		    !(STp->try_dio && try_wdio) && STps->eof < ST_EOM_OK &&
		    STbp->buffer_bytes < STbp->buffer_size) {
			STp->dirty = TRUE;
			/* Don't write a buffer that is not full enough. */
			if (!async_write && count == 0)
				break;
		}

	retry_write:
		if (STp->block_size == 0)
			blks = transfer = do_count;
		else {
			if (!STbp->do_dio)
				blks = STbp->buffer_bytes;
			else
				blks = do_count;
			blks /= STp->block_size;
			transfer = blks * STp->block_size;
		}
		cmd[2] = blks >> 16;
		cmd[3] = blks >> 8;
		cmd[4] = blks;

		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, SCSI_DATA_WRITE,
				   STp->device->timeout, MAX_WRITE_RETRIES, !async_write);
		if (!SRpnt) {
			retval = STbp->syscall_result;
			goto out;
		}
		if (async_write) {
			STbp->writing = transfer;
			STp->dirty = !(STbp->writing ==
				       STbp->buffer_bytes);
			SRpnt = NULL;  /* Prevent releasing this request! */
			DEB( STp->write_pending = 1; )
			break;
		}

		if (STbp->syscall_result != 0) {
                        DEBC(printk(ST_DEB_MSG "%s: Error on write:\n", name));
			if ((SRpnt->sr_sense_buffer[0] & 0x70) == 0x70 &&
			    (SRpnt->sr_sense_buffer[2] & 0x40)) {
				scode = SRpnt->sr_sense_buffer[2] & 0x0f;
				if ((SRpnt->sr_sense_buffer[0] & 0x80) != 0)
					undone = (SRpnt->sr_sense_buffer[3] << 24) |
					    (SRpnt->sr_sense_buffer[4] << 16) |
					    (SRpnt->sr_sense_buffer[5] << 8) |
                                                SRpnt->sr_sense_buffer[6];
				else if (STp->block_size == 0 &&
					 scode == VOLUME_OVERFLOW)
					undone = transfer;
				else
					undone = 0;
				if (STp->block_size != 0)
					undone *= STp->block_size;
				filp->f_pos -= undone;
				if (undone <= do_count) {
					/* Only data from this write is not written */
					count += undone;
					do_count -= undone;
					if (STp->block_size)
						blks = (transfer - undone) / STp->block_size;
					STps->eof = ST_EOM_OK;
					/* Continue in fixed block mode if all written
					   in this request but still something left to write
					   (retval left to zero)
					*/
					if (STp->block_size == 0 ||
					    undone > 0 || count == 0)
						retval = (-ENOSPC); /* EOM within current request */
                                        DEBC(printk(ST_DEB_MSG
                                                       "%s: EOM with %d bytes unwritten.\n",
						       name, count));
				} else {
					/* EOT within data buffered earlier (possible only
					   in fixed block mode without direct i/o) */
					if (!retry_eot && (SRpnt->sr_sense_buffer[0] & 1) == 0 &&
					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
						move_buffer_data(STp->buffer, transfer - undone);
						retry_eot = TRUE;
						if (STps->drv_block >= 0) {
							STps->drv_block += (transfer - undone) /
								STp->block_size;
						}
						STps->eof = ST_EOM_OK;
						DEBC(printk(ST_DEB_MSG
							    "%s: Retry write of %d bytes at EOM.\n",
							    name, STp->buffer->buffer_bytes));
						goto retry_write;
					}
					else {
						/* Either error within data buffered by driver or
						   failed retry */
						count -= do_count;
						blks = do_count = 0;
						STps->eof = ST_EOM_ERROR;
						STps->drv_block = (-1); /* Too cautious? */
						retval = (-EIO);	/* EOM for old data */
						DEBC(printk(ST_DEB_MSG
							    "%s: EOM with lost data.\n",
							    name));
					}
				}
			} else {
				filp->f_pos -= do_count;
				count += do_count;
				STps->drv_block = (-1);		/* Too cautious? */
				retval = (-EIO);
			}

		}

		if (STps->drv_block >= 0) {
			if (STp->block_size == 0)
				STps->drv_block += (do_count > 0);
			else
				STps->drv_block += blks;
		}

		STbp->buffer_bytes = 0;
		STp->dirty = 0;

		if (retval || retry_eot) {
			if (count < total)
				retval = total - count;
			goto out;
		}
	}

	if (STps->eof == ST_EOD_1)
		STps->eof = ST_EOM_OK;
	else if (STps->eof != ST_EOM_OK)
		STps->eof = ST_NOEOF;
	retval = total - count;

 out:
	if (SRpnt != NULL)
		scsi_release_request(SRpnt);
	release_buffering(STp);
	up(&STp->lock);

	return retval;
}

/* Read data from the tape. Returns zero in the normal case, one if the
   eof status has changed, and the negative error code in case of a
   fatal error. Otherwise updates the buffer and the eof state.

   Does release user buffer mapping if it is set.
*/
static long read_tape(Scsi_Tape *STp, long count, Scsi_Request ** aSRpnt)
{
	int transfer, blks, bytes;
	unsigned char cmd[MAX_COMMAND_SIZE];
	Scsi_Request *SRpnt;
	ST_mode *STm;
	ST_partstat *STps;
	ST_buffer *STbp;
	int retval = 0;
	char *name = tape_name(STp);

	if (count == 0)
		return 0;

	STm = &(STp->modes[STp->current_mode]);
	STps = &(STp->ps[STp->partition]);
	if (STps->eof == ST_FM_HIT)
		return 1;
	STbp = STp->buffer;

	if (STp->block_size == 0)
		blks = bytes = count;
	else {
		if (!(STp->try_dio && try_rdio) && STm->do_read_ahead) {
			blks = (STp->buffer)->buffer_blocks;
			bytes = blks * STp->block_size;
		} else {
			bytes = count;
			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
				bytes = (STp->buffer)->buffer_size;
			blks = bytes / STp->block_size;
			bytes = blks * STp->block_size;
		}
	}

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = READ_6;
	cmd[1] = (STp->block_size != 0);
	cmd[2] = blks >> 16;
	cmd[3] = blks >> 8;
	cmd[4] = blks;

	SRpnt = *aSRpnt;
	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, SCSI_DATA_READ,
			   STp->device->timeout, MAX_RETRIES, TRUE);
	release_buffering(STp);
	*aSRpnt = SRpnt;
	if (!SRpnt)
		return STbp->syscall_result;

	STbp->read_pointer = 0;
	STps->at_sm = 0;

	/* Something to check */
	if (STbp->syscall_result) {
		retval = 1;
		DEBC(printk(ST_DEB_MSG "%s: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
                            name,
                            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]));
		if ((SRpnt->sr_sense_buffer[0] & 0x70) == 0x70) {	/* extended sense */

			if ((SRpnt->sr_sense_buffer[2] & 0x0f) == BLANK_CHECK)
				SRpnt->sr_sense_buffer[2] &= 0xcf;	/* No need for EOM in this case */

			if ((SRpnt->sr_sense_buffer[2] & 0xe0) != 0) { /* EOF, EOM, or ILI */
				/* Compute the residual count */
				if ((SRpnt->sr_sense_buffer[0] & 0x80) != 0)
					transfer = (SRpnt->sr_sense_buffer[3] << 24) |
					    (SRpnt->sr_sense_buffer[4] << 16) |
					    (SRpnt->sr_sense_buffer[5] << 8) |
					    SRpnt->sr_sense_buffer[6];
				else
					transfer = 0;
				if (STp->block_size == 0 &&
				    (SRpnt->sr_sense_buffer[2] & 0x0f) == MEDIUM_ERROR)
					transfer = bytes;

				if (SRpnt->sr_sense_buffer[2] & 0x20) {	/* ILI */
					if (STp->block_size == 0) {
						if (transfer <= 0) {
							if (transfer < 0)
								printk(KERN_NOTICE
								       "%s: Failed to read %d byte block with %d byte transfer.\n",
								       name, bytes - transfer, bytes);
							if (STps->drv_block >= 0)
								STps->drv_block += 1;
							STbp->buffer_bytes = 0;
							return (-ENOMEM);
						}
						STbp->buffer_bytes = bytes - transfer;
					} else {
						scsi_release_request(SRpnt);
						SRpnt = *aSRpnt = NULL;
						if (transfer == blks) {	/* We did not get anything, error */
							printk(KERN_NOTICE "%s: Incorrect block size.\n", name);
							if (STps->drv_block >= 0)
								STps->drv_block += blks - transfer + 1;
							st_int_ioctl(STp, MTBSR, 1);
							return (-EIO);
						}
						/* We have some data, deliver it */
						STbp->buffer_bytes = (blks - transfer) *
						    STp->block_size;
                                                DEBC(printk(ST_DEB_MSG
                                                            "%s: ILI but enough data received %ld %d.\n",
                                                            name, count, STbp->buffer_bytes));
						if (STps->drv_block >= 0)
							STps->drv_block += 1;
						if (st_int_ioctl(STp, MTBSR, 1))
							return (-EIO);
					}
				} else if (SRpnt->sr_sense_buffer[2] & 0x80) {	/* FM overrides EOM */
					if (STps->eof != ST_FM_HIT)
						STps->eof = ST_FM_HIT;
					else
						STps->eof = ST_EOD_2;
					if (STp->block_size == 0)
						STbp->buffer_bytes = 0;
					else
						STbp->buffer_bytes =
						    bytes - transfer * STp->block_size;
                                        DEBC(printk(ST_DEB_MSG
                                                    "%s: EOF detected (%d bytes read).\n",
                                                    name, STbp->buffer_bytes));
				} else if (SRpnt->sr_sense_buffer[2] & 0x40) {
					if (STps->eof == ST_FM)
						STps->eof = ST_EOD_1;
					else
						STps->eof = ST_EOM_OK;
					if (STp->block_size == 0)
						STbp->buffer_bytes = bytes - transfer;
					else
						STbp->buffer_bytes =
						    bytes - transfer * STp->block_size;

                                        DEBC(printk(ST_DEB_MSG "%s: EOM detected (%d bytes read).\n",
                                                    name, STbp->buffer_bytes));
				}
			}
			/* end of EOF, EOM, ILI test */ 
			else {	/* nonzero sense key */
                                DEBC(printk(ST_DEB_MSG
                                            "%s: Tape error while reading.\n", name));
				STps->drv_block = (-1);
				if (STps->eof == ST_FM &&
				    (SRpnt->sr_sense_buffer[2] & 0x0f) == BLANK_CHECK) {
                                        DEBC(printk(ST_DEB_MSG
                                                    "%s: Zero returned for first BLANK CHECK after EOF.\n",
                                                    name));
					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
				} else	/* Some other extended sense code */
					retval = (-EIO);
			}

			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
				STbp->buffer_bytes = 0;
		}
		/* End of extended sense test */ 
		else {		/* Non-extended sense */
			retval = STbp->syscall_result;
		}

	}
	/* End of error handling */ 
	else			/* Read successful */
		STbp->buffer_bytes = bytes;

	if (STps->drv_block >= 0) {
		if (STp->block_size == 0)
			STps->drv_block++;
		else
			STps->drv_block += STbp->buffer_bytes / STp->block_size;
	}
	return retval;
}


/* Read command */
static ssize_t
st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
{
	ssize_t total;
	ssize_t retval = 0;
	ssize_t i, transfer;
	int special, do_dio = 0;
	Scsi_Request *SRpnt = NULL;
	Scsi_Tape *STp = filp->private_data;
	ST_mode *STm;
	ST_partstat *STps;
	ST_buffer *STbp = STp->buffer;
	DEB( char *name = tape_name(STp); )

	if (down_interruptible(&STp->lock))
		return -ERESTARTSYS;

	retval = rw_checks(STp, filp, count);
	if (retval || count == 0)