scsi_lib.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,742 行 · 第 1/4 页

	sdev->device_busy--;
	if(sdev->device_busy == 0)
		blk_plug_device(q);
 out:
	/* must be careful here...if we trigger the ->remove() function
	 * we cannot be holding the q lock */
	spin_unlock_irq(q->queue_lock);
	put_device(&sdev->sdev_gendev);
	spin_lock_irq(q->queue_lock);
}

u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
{
	struct device *host_dev;

	if (shost->unchecked_isa_dma)
		return BLK_BOUNCE_ISA;

	host_dev = scsi_get_device(shost);
	if (PCI_DMA_BUS_IS_PHYS && host_dev && host_dev->dma_mask)
		return *host_dev->dma_mask;

	/*
	 * Platforms with virtual-DMA translation
	 * hardware have no practical limit.
	 */
	return BLK_BOUNCE_ANY;
}

struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
{
	struct Scsi_Host *shost = sdev->host;
	struct request_queue *q;

	q = blk_init_queue(scsi_request_fn, &sdev->sdev_lock);
	if (!q)
		return NULL;

	blk_queue_prep_rq(q, scsi_prep_fn);

	blk_queue_max_hw_segments(q, shost->sg_tablesize);
	blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
	blk_queue_max_sectors(q, shost->max_sectors);
	blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
	blk_queue_segment_boundary(q, shost->dma_boundary);
	blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);

	if (!shost->use_clustering)
		clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
	return q;
}

void scsi_free_queue(struct request_queue *q)
{
	blk_cleanup_queue(q);
}

/*
 * Function:    scsi_block_requests()
 *
 * Purpose:     Utility function used by low-level drivers to prevent further
 *		commands from being queued to the device.
 *
 * Arguments:   shost       - Host in question
 *
 * Returns:     Nothing
 *
 * Lock status: No locks are assumed held.
 *
 * Notes:       There is no timer nor any other means by which the requests
 *		get unblocked other than the low-level driver calling
 *		scsi_unblock_requests().
 */
void scsi_block_requests(struct Scsi_Host *shost)
{
	shost->host_self_blocked = 1;
}

/*
 * Function:    scsi_unblock_requests()
 *
 * Purpose:     Utility function used by low-level drivers to allow further
 *		commands from being queued to the device.
 *
 * Arguments:   shost       - Host in question
 *
 * Returns:     Nothing
 *
 * Lock status: No locks are assumed held.
 *
 * Notes:       There is no timer nor any other means by which the requests
 *		get unblocked other than the low-level driver calling
 *		scsi_unblock_requests().
 *
 *		This is done as an API function so that changes to the
 *		internals of the scsi mid-layer won't require wholesale
 *		changes to drivers that use this feature.
 */
void scsi_unblock_requests(struct Scsi_Host *shost)
{
	shost->host_self_blocked = 0;
	scsi_run_host_queues(shost);
}

int __init scsi_init_queue(void)
{
	int i;

	for (i = 0; i < SG_MEMPOOL_NR; i++) {
		struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
		int size = sgp->size * sizeof(struct scatterlist);

		sgp->slab = kmem_cache_create(sgp->name, size, 0,
				SLAB_HWCACHE_ALIGN, NULL, NULL);
		if (!sgp->slab) {
			printk(KERN_ERR "SCSI: can't init sg slab %s\n",
					sgp->name);
		}

		sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
				mempool_alloc_slab, mempool_free_slab,
				sgp->slab);
		if (!sgp->pool) {
			printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
					sgp->name);
		}
	}

	return 0;
}

void scsi_exit_queue(void)
{
	int i;

	for (i = 0; i < SG_MEMPOOL_NR; i++) {
		struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
		mempool_destroy(sgp->pool);
		kmem_cache_destroy(sgp->slab);
	}
}
/**
 *	__scsi_mode_sense - issue a mode sense, falling back from 10 to 
 *		six bytes if necessary.
 *	@sreq:	SCSI request to fill in with the MODE_SENSE
 *	@dbd:	set if mode sense will allow block descriptors to be returned
 *	@modepage: mode page being requested
 *	@buffer: request buffer (may not be smaller than eight bytes)
 *	@len:	length of request buffer.
 *	@timeout: command timeout
 *	@retries: number of retries before failing
 *	@data: returns a structure abstracting the mode header data
 *
 *	Returns zero if unsuccessful, or the header offset (either 4
 *	or 8 depending on whether a six or ten byte command was
 *	issued) if successful.
 **/
int
__scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
		  unsigned char *buffer, int len, int timeout, int retries,
		  struct scsi_mode_data *data) {
	unsigned char cmd[12];
	int use_10_for_ms;
	int header_length;

	memset(data, 0, sizeof(*data));
	memset(&cmd[0], 0, 12);
	cmd[1] = dbd & 0x18;	/* allows DBD and LLBA bits */
	cmd[2] = modepage;

 retry:
	use_10_for_ms = sreq->sr_device->use_10_for_ms;

	if (use_10_for_ms) {
		if (len < 8)
			len = 8;

		cmd[0] = MODE_SENSE_10;
		cmd[8] = len;
		header_length = 8;
	} else {
		if (len < 4)
			len = 4;

		cmd[0] = MODE_SENSE;
		cmd[4] = len;
		header_length = 4;
	}

	sreq->sr_cmd_len = 0;
	sreq->sr_sense_buffer[0] = 0;
	sreq->sr_sense_buffer[2] = 0;
	sreq->sr_data_direction = DMA_FROM_DEVICE;

	memset(buffer, 0, len);

	scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);

	/* This code looks awful: what it's doing is making sure an
	 * ILLEGAL REQUEST sense return identifies the actual command
	 * byte as the problem.  MODE_SENSE commands can return
	 * ILLEGAL REQUEST if the code page isn't supported */
	if (use_10_for_ms && ! scsi_status_is_good(sreq->sr_result) &&
	    (driver_byte(sreq->sr_result) & DRIVER_SENSE) &&
	    sreq->sr_sense_buffer[2] == ILLEGAL_REQUEST &&
	    (sreq->sr_sense_buffer[4] & 0x40) == 0x40 &&
	    sreq->sr_sense_buffer[5] == 0 &&
	    sreq->sr_sense_buffer[6] == 0 ) {
		sreq->sr_device->use_10_for_ms = 0;
		goto retry;
	}

	if(scsi_status_is_good(sreq->sr_result)) {
		data->header_length = header_length;
		if(use_10_for_ms) {
			data->length = buffer[0]*256 + buffer[1] + 2;
			data->medium_type = buffer[2];
			data->device_specific = buffer[3];
			data->longlba = buffer[4] & 0x01;
			data->block_descriptor_length = buffer[6]*256
				+ buffer[7];
		} else {
			data->length = buffer[0] + 1;
			data->medium_type = buffer[1];
			data->device_specific = buffer[2];
			data->block_descriptor_length = buffer[3];
		}
	}

	return sreq->sr_result;
}

/**
 *	scsi_mode_sense - issue a mode sense, falling back from 10 to 
 *		six bytes if necessary.
 *	@sdev:	scsi device to send command to.
 *	@dbd:	set if mode sense will disable block descriptors in the return
 *	@modepage: mode page being requested
 *	@buffer: request buffer (may not be smaller than eight bytes)
 *	@len:	length of request buffer.
 *	@timeout: command timeout
 *	@retries: number of retries before failing
 *
 *	Returns zero if unsuccessful, or the header offset (either 4
 *	or 8 depending on whether a six or ten byte command was
 *	issued) if successful.
 **/
int
scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
		unsigned char *buffer, int len, int timeout, int retries,
		struct scsi_mode_data *data)
{
	struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
	int ret;

	if (!sreq)
		return -1;

	ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
				timeout, retries, data);

	scsi_release_request(sreq);

	return ret;
}

int
scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
{
	struct scsi_request *sreq;
	char cmd[] = {
		TEST_UNIT_READY, 0, 0, 0, 0, 0,
	};
	int result;
	
	sreq = scsi_allocate_request(sdev, GFP_KERNEL);
	if (!sreq)
		return -ENOMEM;

		sreq->sr_data_direction = DMA_NONE;
        scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);

	if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) &&
	    (sreq->sr_sense_buffer[2] & 0x0f) == UNIT_ATTENTION &&
	    sdev->removable) {
		sdev->changed = 1;
		sreq->sr_result = 0;
	}
	result = sreq->sr_result;
	scsi_release_request(sreq);
	return result;
}
EXPORT_SYMBOL(scsi_test_unit_ready);

/**
 *	scsi_device_set_state - Take the given device through the device
 *		state model.
 *	@sdev:	scsi device to change the state of.
 *	@state:	state to change to.
 *
 *	Returns zero if unsuccessful or an error if the requested 
 *	transition is illegal.
 **/
int
scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
{
	enum scsi_device_state oldstate = sdev->sdev_state;

	if (state == oldstate)
		return 0;

	switch (state) {
	case SDEV_CREATED:
		/* There are no legal states that come back to
		 * created.  This is the manually initialised start
		 * state */
		goto illegal;
			
	case SDEV_RUNNING:
		switch (oldstate) {
		case SDEV_CREATED:
		case SDEV_OFFLINE:
		case SDEV_QUIESCE:
			break;
		default:
			goto illegal;
		}
		break;

	case SDEV_QUIESCE:
		switch (oldstate) {
		case SDEV_RUNNING:
		case SDEV_OFFLINE:
			break;
		default:
			goto illegal;
		}
		break;

	case SDEV_OFFLINE:
		switch (oldstate) {
		case SDEV_CREATED:
		case SDEV_RUNNING:
		case SDEV_QUIESCE:
			break;
		default:
			goto illegal;
		}
		break;

	case SDEV_CANCEL:
		switch (oldstate) {
		case SDEV_CREATED:
		case SDEV_RUNNING:
		case SDEV_OFFLINE:
			break;
		default:
			goto illegal;
		}
		break;

	case SDEV_DEL:
		switch (oldstate) {
		case SDEV_CANCEL:
			break;
		default:
			goto illegal;
		}
		break;

	}
	sdev->sdev_state = state;
	return 0;

 illegal:
	dev_printk(KERN_ERR, &sdev->sdev_gendev,
		   "Illegal state transition %s->%s\n",
		   scsi_device_state_name(oldstate),
		   scsi_device_state_name(state));
	WARN_ON(1);
	return -EINVAL;
}
EXPORT_SYMBOL(scsi_device_set_state);

/**
 *	scsi_device_quiesce - Block user issued commands.
 *	@sdev:	scsi device to quiesce.
 *
 *	This works by trying to transition to the SDEV_QUIESCE state
 *	(which must be a legal transition).  When the device is in this
 *	state, only special requests will be accepted, all others will
 *	be deferred.  Since special requests may also be requeued requests,
 *	a successful return doesn't guarantee the device will be 
 *	totally quiescent.
 *
 *	Must be called with user context, may sleep.
 *
 *	Returns zero if unsuccessful or an error if not.
 **/
int
scsi_device_quiesce(struct scsi_device *sdev)
{
	int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
	if (err)
		return err;

	scsi_run_queue(sdev->request_queue);
	while (sdev->device_busy) {
		schedule_timeout(HZ/5);
		scsi_run_queue(sdev->request_queue);
	}
	return 0;
}
EXPORT_SYMBOL(scsi_device_quiesce);

/**
 *	scsi_device_resume - Restart user issued commands to a quiesced device.
 *	@sdev:	scsi device to resume.
 *
 *	Moves the device from quiesced back to running and restarts the
 *	queues.
 *
 *	Must be called with user context, may sleep.
 **/
void
scsi_device_resume(struct scsi_device *sdev)
{
	if(scsi_device_set_state(sdev, SDEV_RUNNING))
		return;
	scsi_run_queue(sdev->request_queue);
}
EXPORT_SYMBOL(scsi_device_resume);