st.c

linux 内核源代码

{
	struct completion *waiting;

	/* if async, make sure there's no command outstanding */
	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
		printk(KERN_ERR "%s: Async command already active.\n",
		       tape_name(STp));
		if (signal_pending(current))
			(STp->buffer)->syscall_result = (-EINTR);
		else
			(STp->buffer)->syscall_result = (-EBUSY);
		return NULL;
	}

	if (SRpnt == NULL) {
		SRpnt = st_allocate_request();
		if (SRpnt == NULL) {
			DEBC( printk(KERN_ERR "%s: Can't get SCSI request.\n",
				     tape_name(STp)); );
			if (signal_pending(current))
				(STp->buffer)->syscall_result = (-EINTR);
			else
				(STp->buffer)->syscall_result = (-EBUSY);
			return NULL;
		}
		SRpnt->stp = STp;
	}

	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
	   which IO is outstanding. It's nulled out when the IO completes. */
	if (!do_wait)
		(STp->buffer)->last_SRpnt = SRpnt;

	waiting = &STp->wait;
	init_completion(waiting);
	SRpnt->waiting = waiting;

	if (!STp->buffer->do_dio)
		buf_to_sg(STp->buffer, bytes);

	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
	STp->buffer->cmdstat.have_sense = 0;
	STp->buffer->syscall_result = 0;

	if (scsi_execute_async(STp->device, cmd, COMMAND_SIZE(cmd[0]), direction,
			&((STp->buffer)->sg[0]), bytes, (STp->buffer)->sg_segs,
			       timeout, retries, SRpnt, st_sleep_done, GFP_KERNEL)) {
		/* could not allocate the buffer or request was too large */
		(STp->buffer)->syscall_result = (-EBUSY);
		(STp->buffer)->last_SRpnt = NULL;
	}
	else if (do_wait) {
		wait_for_completion(waiting);
		SRpnt->waiting = NULL;
		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
	}

	return SRpnt;
}


/* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
   write has been correct but EOM early warning reached, -EIO if write ended in
   error or zero if write successful. Asynchronous writes are used only in
   variable block mode. */
static int write_behind_check(struct scsi_tape * STp)
{
	int retval = 0;
	struct st_buffer *STbuffer;
	struct st_partstat *STps;
	struct st_cmdstatus *cmdstatp;
	struct st_request *SRpnt;

	STbuffer = STp->buffer;
	if (!STbuffer->writing)
		return 0;

        DEB(
	if (STp->write_pending)
		STp->nbr_waits++;
	else
		STp->nbr_finished++;
        ) /* end DEB */

	wait_for_completion(&(STp->wait));
	SRpnt = STbuffer->last_SRpnt;
	STbuffer->last_SRpnt = NULL;
	SRpnt->waiting = NULL;

	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
	st_release_request(SRpnt);

	STbuffer->buffer_bytes -= STbuffer->writing;
	STps = &(STp->ps[STp->partition]);
	if (STps->drv_block >= 0) {
		if (STp->block_size == 0)
			STps->drv_block++;
		else
			STps->drv_block += STbuffer->writing / STp->block_size;
	}

	cmdstatp = &STbuffer->cmdstat;
	if (STbuffer->syscall_result) {
		retval = -EIO;
		if (cmdstatp->have_sense && !cmdstatp->deferred &&
		    (cmdstatp->flags & SENSE_EOM) &&
		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
			/* EOM at write-behind, has all data been written? */
			if (!cmdstatp->remainder_valid ||
			    cmdstatp->uremainder64 == 0)
				retval = -ENOSPC;
		}
		if (retval == -EIO)
			STps->drv_block = -1;
	}
	STbuffer->writing = 0;

	DEB(if (debugging && retval)
	    printk(ST_DEB_MSG "%s: Async write error %x, return value %d.\n",
		   tape_name(STp), STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */

	return retval;
}


/* Step over EOF if it has been inadvertently crossed (ioctl not used because
   it messes up the block number). */
static int cross_eof(struct scsi_tape * STp, int forward)
{
	struct st_request *SRpnt;
	unsigned char cmd[MAX_COMMAND_SIZE];

	cmd[0] = SPACE;
	cmd[1] = 0x01;		/* Space FileMarks */
	if (forward) {
		cmd[2] = cmd[3] = 0;
		cmd[4] = 1;
	} else
		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
	cmd[5] = 0;

        DEBC(printk(ST_DEB_MSG "%s: Stepping over filemark %s.\n",
		   tape_name(STp), forward ? "forward" : "backward"));

	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
			   STp->device->timeout, MAX_RETRIES, 1);
	if (!SRpnt)
		return (STp->buffer)->syscall_result;

	st_release_request(SRpnt);
	SRpnt = NULL;

	if ((STp->buffer)->cmdstat.midlevel_result != 0)
		printk(KERN_ERR "%s: Stepping over filemark %s failed.\n",
		   tape_name(STp), forward ? "forward" : "backward");

	return (STp->buffer)->syscall_result;
}


/* Flush the write buffer (never need to write if variable blocksize). */
static int flush_write_buffer(struct scsi_tape * STp)
{
	int offset, transfer, blks;
	int result;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	struct st_partstat *STps;

	result = write_behind_check(STp);
	if (result)
		return result;

	result = 0;
	if (STp->dirty == 1) {

		offset = (STp->buffer)->buffer_bytes;
		transfer = ((offset + STp->block_size - 1) /
			    STp->block_size) * STp->block_size;
                DEBC(printk(ST_DEB_MSG "%s: Flushing %d bytes.\n",
                               tape_name(STp), transfer));

		memset((STp->buffer)->b_data + offset, 0, transfer - offset);

		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = WRITE_6;
		cmd[1] = 1;
		blks = transfer / STp->block_size;
		cmd[2] = blks >> 16;
		cmd[3] = blks >> 8;
		cmd[4] = blks;

		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
				   STp->device->timeout, MAX_WRITE_RETRIES, 1);
		if (!SRpnt)
			return (STp->buffer)->syscall_result;

		STps = &(STp->ps[STp->partition]);
		if ((STp->buffer)->syscall_result != 0) {
			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

			if (cmdstatp->have_sense && !cmdstatp->deferred &&
			    (cmdstatp->flags & SENSE_EOM) &&
			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
			    (!cmdstatp->remainder_valid ||
			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
				STp->dirty = 0;
				(STp->buffer)->buffer_bytes = 0;
				if (STps->drv_block >= 0)
					STps->drv_block += blks;
				result = (-ENOSPC);
			} else {
				printk(KERN_ERR "%s: Error on flush.\n",
                                       tape_name(STp));
				STps->drv_block = (-1);
				result = (-EIO);
			}
		} else {
			if (STps->drv_block >= 0)
				STps->drv_block += blks;
			STp->dirty = 0;
			(STp->buffer)->buffer_bytes = 0;
		}
		st_release_request(SRpnt);
		SRpnt = NULL;
	}
	return result;
}


/* Flush the tape buffer. The tape will be positioned correctly unless
   seek_next is true. */
static int flush_buffer(struct scsi_tape *STp, int seek_next)
{
	int backspace, result;
	struct st_buffer *STbuffer;
	struct st_partstat *STps;

	STbuffer = STp->buffer;

	/*
	 * If there was a bus reset, block further access
	 * to this device.
	 */
	if (STp->pos_unknown)
		return (-EIO);

	if (STp->ready != ST_READY)
		return 0;
	STps = &(STp->ps[STp->partition]);
	if (STps->rw == ST_WRITING)	/* Writing */
		return flush_write_buffer(STp);

	if (STp->block_size == 0)
		return 0;

	backspace = ((STp->buffer)->buffer_bytes +
		     (STp->buffer)->read_pointer) / STp->block_size -
	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
	    STp->block_size;
	(STp->buffer)->buffer_bytes = 0;
	(STp->buffer)->read_pointer = 0;
	result = 0;
	if (!seek_next) {
		if (STps->eof == ST_FM_HIT) {
			result = cross_eof(STp, 0);	/* Back over the EOF hit */
			if (!result)
				STps->eof = ST_NOEOF;
			else {
				if (STps->drv_file >= 0)
					STps->drv_file++;
				STps->drv_block = 0;
			}
		}
		if (!result && backspace > 0)
			result = st_int_ioctl(STp, MTBSR, backspace);
	} else if (STps->eof == ST_FM_HIT) {
		if (STps->drv_file >= 0)
			STps->drv_file++;
		STps->drv_block = 0;
		STps->eof = ST_NOEOF;
	}
	return result;

}

/* Set the mode parameters */
static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
{
	int set_it = 0;
	unsigned long arg;
	char *name = tape_name(STp);

	if (!STp->density_changed &&
	    STm->default_density >= 0 &&
	    STm->default_density != STp->density) {
		arg = STm->default_density;
		set_it = 1;
	} else
		arg = STp->density;
	arg <<= MT_ST_DENSITY_SHIFT;
	if (!STp->blksize_changed &&
	    STm->default_blksize >= 0 &&
	    STm->default_blksize != STp->block_size) {
		arg |= STm->default_blksize;
		set_it = 1;
	} else
		arg |= STp->block_size;
	if (set_it &&
	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
		printk(KERN_WARNING
		       "%s: Can't set default block size to %d bytes and density %x.\n",
		       name, STm->default_blksize, STm->default_density);
		if (modes_defined)
			return (-EINVAL);
	}
	return 0;
}


/* Lock or unlock the drive door. Don't use when st_request allocated. */
static int do_door_lock(struct scsi_tape * STp, int do_lock)
{
	int retval, cmd;
	DEB(char *name = tape_name(STp);)


	cmd = do_lock ? SCSI_IOCTL_DOORLOCK : SCSI_IOCTL_DOORUNLOCK;
	DEBC(printk(ST_DEB_MSG "%s: %socking drive door.\n", name,
		    do_lock ? "L" : "Unl"));
	retval = scsi_ioctl(STp->device, cmd, NULL);
	if (!retval) {
		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
	}
	else {
		STp->door_locked = ST_LOCK_FAILS;
	}
	return retval;
}


/* Set the internal state after reset */
static void reset_state(struct scsi_tape *STp)
{
	int i;
	struct st_partstat *STps;

	STp->pos_unknown = 0;
	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
		STps = &(STp->ps[i]);
		STps->rw = ST_IDLE;
		STps->eof = ST_NOEOF;
		STps->at_sm = 0;
		STps->last_block_valid = 0;
		STps->drv_block = -1;
		STps->drv_file = -1;
	}
	if (STp->can_partitions) {
		STp->partition = find_partition(STp);
		if (STp->partition < 0)
			STp->partition = 0;
		STp->new_partition = STp->partition;
	}
}

/* Test if the drive is ready. Returns either one of the codes below or a negative system
   error code. */
#define CHKRES_READY       0
#define CHKRES_NEW_SESSION 1
#define CHKRES_NOT_READY   2
#define CHKRES_NO_TAPE     3

#define MAX_ATTENTIONS    10

static int test_ready(struct scsi_tape *STp, int do_wait)
{
	int attentions, waits, max_wait, scode;
	int retval = CHKRES_READY, new_session = 0;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt = NULL;
	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;

	for (attentions=waits=0; ; ) {
		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
		cmd[0] = TEST_UNIT_READY;
		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
				   STp->long_timeout, MAX_READY_RETRIES, 1);

		if (!SRpnt) {
			retval = (STp->buffer)->syscall_result;
			break;
		}

		if (cmdstatp->have_sense) {

			scode = cmdstatp->sense_hdr.sense_key;

			if (scode == UNIT_ATTENTION) { /* New media? */
				new_session = 1;
				if (attentions < MAX_ATTENTIONS) {
					attentions++;
					continue;
				}
				else {
					retval = (-EIO);
					break;
				}
			}

			if (scode == NOT_READY) {
				if (waits < max_wait) {
					if (msleep_interruptible(1000)) {
						retval = (-EINTR);
						break;
					}
					waits++;
					continue;
				}
				else {
					if ((STp->device)->scsi_level >= SCSI_2 &&
					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
						retval = CHKRES_NO_TAPE;
					else
						retval = CHKRES_NOT_READY;
					break;
				}
			}
		}

		retval = (STp->buffer)->syscall_result;
		if (!retval)
			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
		break;
	}

	if (SRpnt != NULL)
		st_release_request(SRpnt);
	return retval;
}


/* See if the drive is ready and gather information about the tape. Return values:
   < 0   negative error code from errno.h
   0     drive ready
   1     drive not ready (possibly no tape)
*/
static int check_tape(struct scsi_tape *STp, struct file *filp)
{
	int i, retval, new_session = 0, do_wait;
	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
	unsigned short st_flags = filp->f_flags;
	struct st_request *SRpnt = NULL;
	struct st_modedef *STm;
	struct st_partstat *STps;
	char *name = tape_name(STp);
	struct inode *inode = filp->f_path.dentry->d_inode;
	int mode = TAPE_MODE(inode);

	STp->ready = ST_READY;

	if (mode != STp->current_mode) {
                DEBC(printk(ST_DEB_MSG "%s: Mode change from %d to %d.\n",