target: Check -ENOMEM to signal QUEUE_FULL from fabric callbacks

This patch changes target core to also check for -ENOMEM from fabric callbacks
to signal QUEUE_FULL status, instead of just -EAGAIN in order to catch a
larger set of fabric failure cases that want to trigger QUEUE_FULL logic.
This includes the callbacks for ->write_pending(), ->queue_data_in() and
->queue_status().

It also makes transport_generic_write_pending() return zero upon QUEUE_FULL,
and removes two unnecessary -EAGAIN checks to catch write pending QUEUE_FULL
cases from transport_generic_new_cmd() failures in transport_handle_cdb_direct()
and transport_processing_thread():TRANSPORT_NEW_CMD_MAP state.

Reported-by: Bart Van Assche <bvanassche@acm.org>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index d75255804481b8340774e88cf60494eed3c0bd7c..5dee44639f8ffc4f29a7e074e3b9d6be3ad3179e 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -908,7 +908,7 @@ void transport_remove_task_from_execute_queue(
 }
 
 /*
- * Handle QUEUE_FULL / -EAGAIN status
+ * Handle QUEUE_FULL / -EAGAIN and -ENOMEM status
  */
 
 static void target_qf_do_work(struct work_struct *work)
@@ -1645,9 +1645,7 @@ int transport_handle_cdb_direct(
         * and call transport_generic_request_failure() if necessary..
         */
        ret = transport_generic_new_cmd(cmd);
-       if (ret == -EAGAIN)
-               return 0;
-       else if (ret < 0) {
+       if (ret < 0) {
                cmd->transport_error_status = ret;
                transport_generic_request_failure(cmd, 0,
                                (cmd->data_direction != DMA_TO_DEVICE));
@@ -1886,7 +1884,7 @@ static void transport_generic_request_failure(
                                ASCQ_2CH_PREVIOUS_RESERVATION_CONFLICT_STATUS);
 
                ret = cmd->se_tfo->queue_status(cmd);
-               if (ret == -EAGAIN)
+               if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                goto check_stop;
        case PYX_TRANSPORT_USE_SENSE_REASON:
@@ -1913,7 +1911,7 @@ static void transport_generic_request_failure(
        else {
                ret = transport_send_check_condition_and_sense(cmd,
                                cmd->scsi_sense_reason, 0);
-               if (ret == -EAGAIN)
+               if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
        }
 
@@ -3308,7 +3306,7 @@ static void target_complete_ok_work(struct work_struct *work)
                if (cmd->scsi_status) {
                        ret = transport_send_check_condition_and_sense(
                                        cmd, reason, 1);
-                       if (ret == -EAGAIN)
+                       if (ret == -EAGAIN || ret == -ENOMEM)
                                goto queue_full;
 
                        transport_lun_remove_cmd(cmd);
@@ -3333,7 +3331,7 @@ static void target_complete_ok_work(struct work_struct *work)
                spin_unlock(&cmd->se_lun->lun_sep_lock);
 
                ret = cmd->se_tfo->queue_data_in(cmd);
-               if (ret == -EAGAIN)
+               if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                break;
        case DMA_TO_DEVICE:
@@ -3354,14 +3352,14 @@ static void target_complete_ok_work(struct work_struct *work)
                        }
                        spin_unlock(&cmd->se_lun->lun_sep_lock);
                        ret = cmd->se_tfo->queue_data_in(cmd);
-                       if (ret == -EAGAIN)
+                       if (ret == -EAGAIN || ret == -ENOMEM)
                                goto queue_full;
                        break;
                }
                /* Fall through for DMA_TO_DEVICE */
        case DMA_NONE:
                ret = cmd->se_tfo->queue_status(cmd);
-               if (ret == -EAGAIN)
+               if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                break;
        default:
@@ -3890,7 +3888,10 @@ EXPORT_SYMBOL(transport_generic_process_write);
 
 static void transport_write_pending_qf(struct se_cmd *cmd)
 {
-       if (cmd->se_tfo->write_pending(cmd) == -EAGAIN) {
+       int ret;
+
+       ret = cmd->se_tfo->write_pending(cmd);
+       if (ret == -EAGAIN || ret == -ENOMEM) {
                pr_debug("Handling write_pending QUEUE__FULL: se_cmd: %p\n",
                         cmd);
                transport_handle_queue_full(cmd, cmd->se_dev);
@@ -3920,7 +3921,7 @@ static int transport_generic_write_pending(struct se_cmd *cmd)
         * frontend know that WRITE buffers are ready.
         */
        ret = cmd->se_tfo->write_pending(cmd);
-       if (ret == -EAGAIN)
+       if (ret == -EAGAIN || ret == -ENOMEM)
                goto queue_full;
        else if (ret < 0)
                return ret;
@@ -3931,7 +3932,7 @@ queue_full:
        pr_debug("Handling write_pending QUEUE__FULL: se_cmd: %p\n", cmd);
        cmd->t_state = TRANSPORT_COMPLETE_QF_WP;
        transport_handle_queue_full(cmd, cmd->se_dev);
-       return ret;
+       return 0;
 }
 
 /**
@@ -4583,9 +4584,7 @@ get_cmd:
                                break;
                        }
                        ret = transport_generic_new_cmd(cmd);
-                       if (ret == -EAGAIN)
-                               break;
-                       else if (ret < 0) {
+                       if (ret < 0) {
                                cmd->transport_error_status = ret;
                                transport_generic_request_failure(cmd,
                                        0, (cmd->data_direction !=