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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 37 insertions, 120 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 087bbea46cdc..5267198688fe 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -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 *);
 
 /*
@@ -3705,68 +3682,6 @@ out:
 }
 
 /*
- * 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
  * ->write_pending instead. Otherwise place it on the execution queue.
@@ -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) {
-                atomic_inc(&cmd->t_fe_count);
-                atomic_inc(&cmd->t_se_count);
+        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;
         }
 
-        cmd->t_task_list_num = (task_cdbs + task_cdbs_bidi);
+        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 = 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);