ide-tape.c

讲述linux的初始化过程

		count = IDE_MIN (bh->b_size - atomic_read(&bh->b_count), bcount);
		atapi_input_bytes (drive, bh->b_data + atomic_read(&bh->b_count), count);
		bcount -= count; atomic_add(count, &bh->b_count);
		if (atomic_read(&bh->b_count) == bh->b_size) {
			bh = bh->b_reqnext;
			if (bh)
				atomic_set(&bh->b_count, 0);
		}
	}
	pc->bh = bh;
}

static void idetape_output_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
	struct buffer_head *bh = pc->bh;
	int count;

	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk (KERN_ERR "ide-tape: bh == NULL in idetape_output_buffers\n");
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = IDE_MIN (pc->b_count, bcount);
		atapi_output_bytes (drive, pc->b_data, count);
		bcount -= count; pc->b_data += count; pc->b_count -= count;
		if (!pc->b_count) {
			pc->bh = bh = bh->b_reqnext;
			if (bh) {
				pc->b_data = bh->b_data;
				pc->b_count = atomic_read(&bh->b_count);
			}
		}
	}
}

#ifdef CONFIG_BLK_DEV_IDEDMA
static void idetape_update_buffers (idetape_pc_t *pc)
{
	struct buffer_head *bh = pc->bh;
	int count, bcount = pc->actually_transferred;

	if (test_bit (PC_WRITING, &pc->flags))
		return;
	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk (KERN_ERR "ide-tape: bh == NULL in idetape_update_buffers\n");
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = IDE_MIN (bh->b_size, bcount);
		atomic_set(&bh->b_count, count);
		if (atomic_read(&bh->b_count) == bh->b_size)
			bh = bh->b_reqnext;
		bcount -= count;
	}
	pc->bh = bh;
}
#endif /* CONFIG_BLK_DEV_IDEDMA */

/*
 *	idetape_next_pc_storage returns a pointer to a place in which we can
 *	safely store a packet command, even though we intend to leave the
 *	driver. A storage space for a maximum of IDETAPE_PC_STACK packet
 *	commands is allocated at initialization time.
 */
static idetape_pc_t *idetape_next_pc_storage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 5)
		printk (KERN_INFO "ide-tape: pc_stack_index=%d\n",tape->pc_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
	if (tape->pc_stack_index==IDETAPE_PC_STACK)
		tape->pc_stack_index=0;
	return (&tape->pc_stack[tape->pc_stack_index++]);
}

/*
 *	idetape_next_rq_storage is used along with idetape_next_pc_storage.
 *	Since we queue packet commands in the request queue, we need to
 *	allocate a request, along with the allocation of a packet command.
 */
 
/**************************************************************
 *                                                            *
 *  This should get fixed to use kmalloc(.., GFP_ATOMIC)      *
 *  followed later on by kfree().   -ml                       *
 *                                                            *
 **************************************************************/
 
static struct request *idetape_next_rq_storage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 5)
		printk (KERN_INFO "ide-tape: rq_stack_index=%d\n",tape->rq_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
	if (tape->rq_stack_index==IDETAPE_PC_STACK)
		tape->rq_stack_index=0;
	return (&tape->rq_stack[tape->rq_stack_index++]);
}

/*
 *	idetape_init_pc initializes a packet command.
 */
static void idetape_init_pc (idetape_pc_t *pc)
{
	memset (pc->c, 0, 12);
	pc->retries = 0;
	pc->flags = 0;
	pc->request_transfer = 0;
	pc->buffer = pc->pc_buffer;
	pc->buffer_size = IDETAPE_PC_BUFFER_SIZE;
	pc->bh = NULL;
	pc->b_data = NULL;
}

/*
 *	idetape_analyze_error is called on each failed packet command retry
 *	to analyze the request sense. We currently do not utilize this
 *	information.
 */
static void idetape_analyze_error (ide_drive_t *drive,idetape_request_sense_result_t *result)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->failed_pc;

	tape->sense = *result;
	tape->sense_key = result->sense_key; tape->asc = result->asc; tape->ascq = result->ascq;
#if IDETAPE_DEBUG_LOG
	/*
	 *	Without debugging, we only log an error if we decided to
	 *	give up retrying.
	 */
	if (tape->debug_level >= 1)
		printk (KERN_INFO "ide-tape: pc = %x, sense key = %x, asc = %x, ascq = %x\n",pc->c[0],result->sense_key,result->asc,result->ascq);
#if IDETAPE_DEBUG_LOG_VERBOSE
	if (tape->debug_level >= 1)
		printk (KERN_INFO "ide-tape: pc = %s, sense key = %x, asc = %x, ascq = %x\n",
			idetape_command_key_verbose((byte) pc->c[0]),
			result->sense_key,
			result->asc,
			result->ascq);
#endif /* IDETAPE_DEBUG_LOG_VERBOSE */
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->onstream && result->sense_key == 2 && result->asc == 0x53 && result->ascq == 2) {
		clear_bit(PC_DMA_ERROR, &pc->flags);
		ide_stall_queue(drive, HZ / 2);
		return;
	}
#ifdef CONFIG_BLK_DEV_IDEDMA

	/*
	 *	Correct pc->actually_transferred by asking the tape.
	 */
	if (test_bit (PC_DMA_ERROR, &pc->flags)) {
		pc->actually_transferred = pc->request_transfer - tape->tape_block_size * ntohl (get_unaligned (&result->information));
		idetape_update_buffers (pc);
	}
#endif /* CONFIG_BLK_DEV_IDEDMA */
	if (pc->c[0] == IDETAPE_READ_CMD && result->filemark) {
		pc->error = IDETAPE_ERROR_FILEMARK;
		set_bit (PC_ABORT, &pc->flags);
	}
	if (pc->c[0] == IDETAPE_WRITE_CMD) {
		if (result->eom || (result->sense_key == 0xd && result->asc == 0x0 && result->ascq == 0x2)) {
			pc->error = IDETAPE_ERROR_EOD;
			set_bit (PC_ABORT, &pc->flags);
		}
	}
	if (pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD) {
		if (result->sense_key == 8) {
			pc->error = IDETAPE_ERROR_EOD;
			set_bit (PC_ABORT, &pc->flags);
		}
		if (!test_bit (PC_ABORT, &pc->flags) && (tape->onstream || pc->actually_transferred))
			pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
	}
}

static void idetape_abort_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage = tape->next_stage;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: %s: idetape_abort_pipeline called\n", tape->name);
#endif
	while (stage) {
		if (stage->rq.cmd == IDETAPE_WRITE_RQ)
			stage->rq.cmd = IDETAPE_ABORTED_WRITE_RQ;
		else if (stage->rq.cmd == IDETAPE_READ_RQ)
			stage->rq.cmd = IDETAPE_ABORTED_READ_RQ;
		stage = stage->next;
	}
}

/*
 *	idetape_active_next_stage will declare the next stage as "active".
 */
static void idetape_active_next_stage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage=tape->next_stage;
	struct request *rq = &stage->rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_active_next_stage\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (stage == NULL) {
		printk (KERN_ERR "ide-tape: bug: Trying to activate a non existing stage\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */	

	rq->buffer = NULL;
	rq->bh = stage->bh;
	tape->active_data_request=rq;
	tape->active_stage=stage;
	tape->next_stage=stage->next;
}

/*
 *	idetape_increase_max_pipeline_stages is a part of the feedback
 *	loop which tries to find the optimum number of stages. In the
 *	feedback loop, we are starting from a minimum maximum number of
 *	stages, and if we sense that the pipeline is empty, we try to
 *	increase it, until we reach the user compile time memory limit.
 */
static void idetape_increase_max_pipeline_stages (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int increase = (tape->max_pipeline - tape->min_pipeline) / 10;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_increase_max_pipeline_stages\n");
#endif /* IDETAPE_DEBUG_LOG */

	tape->max_stages += increase;
	tape->max_stages = IDE_MAX(tape->max_stages, tape->min_pipeline);
	tape->max_stages = IDE_MIN(tape->max_stages, tape->max_pipeline);
}

/*
 *	idetape_kfree_stage calls kfree to completely free a stage, along with
 *	its related buffers.
 */
static void __idetape_kfree_stage (idetape_stage_t *stage)
{
	struct buffer_head *prev_bh, *bh = stage->bh;
	int size;

	while (bh != NULL) {
		if (bh->b_data != NULL) {
			size = (int) bh->b_size;
			while (size > 0) {
				free_page ((unsigned long) bh->b_data);
				size -= PAGE_SIZE;
				bh->b_data += PAGE_SIZE;
			}
		}
		prev_bh = bh;
		bh = bh->b_reqnext;
		kfree (prev_bh);
	}
	kfree (stage);
}

static void idetape_kfree_stage (idetape_tape_t *tape, idetape_stage_t *stage)
{
	__idetape_kfree_stage (stage);
}

/*
 *	idetape_remove_stage_head removes tape->first_stage from the pipeline.
 *	The caller should avoid race conditions.
 */
static void idetape_remove_stage_head (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_remove_stage_head\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (tape->first_stage == NULL) {
		printk (KERN_ERR "ide-tape: bug: tape->first_stage is NULL\n");
		return;		
	}
	if (tape->active_stage == tape->first_stage) {
		printk (KERN_ERR "ide-tape: bug: Trying to free our active pipeline stage\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	stage=tape->first_stage;
	tape->first_stage=stage->next;
	idetape_kfree_stage (tape, stage);
	tape->nr_stages--;
	if (tape->first_stage == NULL) {
		tape->last_stage=NULL;
#if IDETAPE_DEBUG_BUGS
		if (tape->next_stage != NULL)
			printk (KERN_ERR "ide-tape: bug: tape->next_stage != NULL\n");
		if (tape->nr_stages)
			printk (KERN_ERR "ide-tape: bug: nr_stages should be 0 now\n");
#endif /* IDETAPE_DEBUG_BUGS */
	}
}

/*
 *	idetape_end_request is used to finish servicing a request, and to
 *	insert a pending pipeline request into the main device queue.
 */
static void idetape_end_request (byte uptodate, ide_hwgroup_t *hwgroup)
{
	ide_drive_t *drive = hwgroup->drive;
	struct request *rq = hwgroup->rq;
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	int error;
	int remove_stage = 0;
#if ONSTREAM_DEBUG
	idetape_stage_t *stage;
	os_aux_t *aux;
	unsigned char *p;
#endif

#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
	printk (KERN_INFO "ide-tape: Reached idetape_end_request\n");
#endif /* IDETAPE_DEBUG_LOG */

	switch (uptodate) {
		case 0:	error = IDETAPE_ERROR_GENERAL; break;
		case 1: error = 0; break;
		default: error = uptodate;
	}
	rq->errors = error;
	if (error)
		tape->failed_pc = NULL;

	spin_lock_irqsave(&tape->spinlock, flags);
	if (tape->active_data_request == rq) {		/* The request was a pipelined data transfer request */
		tape->active_stage = NULL;
		tape->active_data_request = NULL;
		tape->nr_pending_stages--;
		if (rq->cmd == IDETAPE_WRITE_RQ) {
#if ONSTREAM_DEBUG
			if (tape->de