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Commit 4101f0a8 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Nicholas Bellinger
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target: always allocate a single task 



Simply transport_generic_new_cmd to only allocate a single task.  For normal
unidirection commands nothing changes except that the code is a lot simpler
now.  Any BIDI support that used to work will stop now for the next few
patches at least.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 6bb35e00

drivers/target/target_core_transport.c

+37 −120
Original line number Diff line number Diff line
@@ -1474,29 +1474,6 @@ static inline void transport_generic_prepare_cdb( 
	}

}



static struct se_task *

transport_generic_get_task(struct se_cmd *cmd,

		enum dma_data_direction data_direction)

{

	struct se_task *task;

	struct se_device *dev = cmd->se_dev;



	task = dev->transport->alloc_task(cmd->t_task_cdb);

	if (!task) {

		pr_err("Unable to allocate struct se_task\n");

		return NULL;

	}



	INIT_LIST_HEAD(&task->t_list);

	INIT_LIST_HEAD(&task->t_execute_list);

	INIT_LIST_HEAD(&task->t_state_list);

	init_completion(&task->task_stop_comp);

	task->task_se_cmd = cmd;

	task->task_data_direction = data_direction;



	return task;

}



static int transport_generic_cmd_sequencer(struct se_cmd *, unsigned char *);



/*
@@ -3704,68 +3681,6 @@ transport_generic_get_mem(struct se_cmd *cmd) 
	return -ENOMEM;

}



/*

 * Break up cmd into chunks transport can handle

 */

static int

transport_allocate_data_tasks(struct se_cmd *cmd,

	enum dma_data_direction data_direction,

	struct scatterlist *cmd_sg, unsigned int sgl_nents)

{

	struct se_device *dev = cmd->se_dev;

	struct se_dev_attrib *attr = &dev->se_sub_dev->se_dev_attrib;

	sector_t sectors;

	struct se_task *task;

	unsigned long flags;



	if (transport_cmd_get_valid_sectors(cmd) < 0)

		return -EINVAL;



	sectors = DIV_ROUND_UP(cmd->data_length, attr->block_size);



	BUG_ON(cmd->data_length % attr->block_size);

	BUG_ON(sectors > attr->max_sectors);



	task = transport_generic_get_task(cmd, data_direction);

	if (!task)

		return -ENOMEM;



	task->task_sg = cmd_sg;

	task->task_sg_nents = sgl_nents;



	spin_lock_irqsave(&cmd->t_state_lock, flags);

	list_add_tail(&task->t_list, &cmd->t_task_list);

	spin_unlock_irqrestore(&cmd->t_state_lock, flags);



	return 1;

}



static int

transport_allocate_control_task(struct se_cmd *cmd)

{

	struct se_task *task;

	unsigned long flags;



	/* Workaround for handling zero-length control CDBs */

	if ((cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB) &&

	    !cmd->data_length)

		return 0;



	task = transport_generic_get_task(cmd, cmd->data_direction);

	if (!task)

		return -ENOMEM;



	task->task_sg = cmd->t_data_sg;

	task->task_sg_nents = cmd->t_data_nents;



	spin_lock_irqsave(&cmd->t_state_lock, flags);

	list_add_tail(&task->t_list, &cmd->t_task_list);

	spin_unlock_irqrestore(&cmd->t_state_lock, flags);



	/* Success! Return number of tasks allocated */

	return 1;

}



/*

 * Allocate any required resources to execute the command.  For writes we

 * might not have the payload yet, so notify the fabric via a call to
@@ -3774,8 +3689,8 @@ transport_allocate_control_task(struct se_cmd *cmd) 
int transport_generic_new_cmd(struct se_cmd *cmd)

{

	struct se_device *dev = cmd->se_dev;

	int task_cdbs, task_cdbs_bidi = 0;

	int set_counts = 1;

	struct se_task *task;

	unsigned long flags;

	int ret = 0;



	/*
@@ -3790,35 +3705,9 @@ int transport_generic_new_cmd(struct se_cmd *cmd) 
			goto out_fail;

	}



	/*

	 * For BIDI command set up the read tasks first.

	 */

	if (cmd->t_bidi_data_sg &&

	    dev->transport->transport_type != TRANSPORT_PLUGIN_PHBA_PDEV) {

		BUG_ON(!(cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB));



		task_cdbs_bidi = transport_allocate_data_tasks(cmd,

				DMA_FROM_DEVICE, cmd->t_bidi_data_sg,

				cmd->t_bidi_data_nents);

		if (task_cdbs_bidi <= 0)

			goto out_fail;



		atomic_inc(&cmd->t_fe_count);

		atomic_inc(&cmd->t_se_count);

		set_counts = 0;

	}



	if (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB) {

		task_cdbs = transport_allocate_data_tasks(cmd,

					cmd->data_direction, cmd->t_data_sg,

					cmd->t_data_nents);

	} else {

		task_cdbs = transport_allocate_control_task(cmd);

	}



	if (task_cdbs < 0)

		goto out_fail;

	else if (!task_cdbs && (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB)) {

	/* Workaround for handling zero-length control CDBs */

	if ((cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB) &&

	    !cmd->data_length) {

		spin_lock_irq(&cmd->t_state_lock);

		cmd->t_state = TRANSPORT_COMPLETE;

		cmd->transport_state |= CMD_T_ACTIVE;
@@ -3836,12 +3725,40 @@ int transport_generic_new_cmd(struct se_cmd *cmd) 
		return 0;

	}



	if (set_counts) {

	if (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB) {

		struct se_dev_attrib *attr = &dev->se_sub_dev->se_dev_attrib;



		if (transport_cmd_get_valid_sectors(cmd) < 0)

			return -EINVAL;



		BUG_ON(cmd->data_length % attr->block_size);

		BUG_ON(DIV_ROUND_UP(cmd->data_length, attr->block_size) >

			attr->max_sectors);

	}



	task = dev->transport->alloc_task(cmd->t_task_cdb);

	if (!task) {

		pr_err("Unable to allocate struct se_task\n");

		goto out_fail;

	}



	INIT_LIST_HEAD(&task->t_list);

	INIT_LIST_HEAD(&task->t_execute_list);

	INIT_LIST_HEAD(&task->t_state_list);

	init_completion(&task->task_stop_comp);

	task->task_se_cmd = cmd;

	task->task_data_direction = cmd->data_direction;

	task->task_sg = cmd->t_data_sg;

	task->task_sg_nents = cmd->t_data_nents;



	spin_lock_irqsave(&cmd->t_state_lock, flags);

	list_add_tail(&task->t_list, &cmd->t_task_list);

	spin_unlock_irqrestore(&cmd->t_state_lock, flags);



	atomic_inc(&cmd->t_fe_count);

	atomic_inc(&cmd->t_se_count);

	}



	cmd->t_task_list_num = (task_cdbs + task_cdbs_bidi);

	cmd->t_task_list_num = 1;

	atomic_set(&cmd->t_task_cdbs_left, cmd->t_task_list_num);

	atomic_set(&cmd->t_task_cdbs_ex_left, cmd->t_task_list_num);