[PATCH v2 1/8] scsi: target: Make write_pending_must_be_called a bit field

[PATCH v2 1/8] scsi: target: Make write_pending_must_be_called a bit field

[Mike Christie]

The next patches add more on/off type of settings to the
target_core_fabric_ops struct so this makes write_pending_must_be_called
a bit field instead of a bool to better organize the settings.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/iscsi/iscsi_target_configfs.c | 2 +-
 include/target/target_core_fabric.h          | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 1cff6052e820..bf190dcb9eee 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1589,5 +1589,5 @@ const struct target_core_fabric_ops iscsi_ops = {
 	.tfc_tpg_nacl_auth_attrs	= lio_target_nacl_auth_attrs,
 	.tfc_tpg_nacl_param_attrs	= lio_target_nacl_param_attrs,
 
-	.write_pending_must_be_called	= true,
+	.write_pending_must_be_called	= 1,
 };
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index b188b1e90e1e..2a6c4c935666 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -113,11 +113,11 @@ struct target_core_fabric_ops {
 	struct configfs_attribute **tfc_tpg_nacl_param_attrs;
 
 	/*
-	 * Set this member variable to true if the SCSI transport protocol
+	 * Set this member variable if the SCSI transport protocol
 	 * (e.g. iSCSI) requires that the Data-Out buffer is transferred in
 	 * its entirety before a command is aborted.
 	 */
-	bool write_pending_must_be_called;
+	unsigned int write_pending_must_be_called:1;
 };
 
 int target_register_template(const struct target_core_fabric_ops *fo);
-- 
2.34.1

[PATCH v2 2/8] scsi: target: Have drivers report if they support direct submissions

[Mike Christie]

In some cases, like with multiple LUN targets or where the target has to
respond to transport level requests from the receiving context it can be
better to defer cmd submission to a helper thread. If the backend driver
blocks on something like request/tag allocation it can block the entire
target submission path and other LUs and transport IO on that session.

In other cases like single LUN targets with storage that can support all
the commands that the target can queue, then it's best to submit the cmd
to the backend from the target's cmd receiving context.

The next patches will allow the user to config what they prefer, but
drivers like loop can't directly submit because they can be called from a
context that can't sleep. And, drivers like vhost-scsi can support direct
submission, but need to keep their default behavior of deferring
execution to avoid possible regressions where the backend can block.

This patch has the drivers tell LIO core if they support direct
submissions and their current default, so in the next patch we can
prevent users from misconfiguring the system and initialize devices
correctly.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/infiniband/ulp/srpt/ib_srpt.c        | 3 +++
 drivers/scsi/elx/efct/efct_lio.c             | 5 +++++
 drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c     | 3 +++
 drivers/scsi/qla2xxx/tcm_qla2xxx.c           | 6 ++++++
 drivers/target/iscsi/iscsi_target_configfs.c | 3 +++
 drivers/target/loopback/tcm_loop.c           | 2 ++
 drivers/target/sbp/sbp_target.c              | 3 +++
 drivers/target/tcm_fc/tfc_conf.c             | 3 +++
 drivers/usb/gadget/function/f_tcm.c          | 3 +++
 drivers/vhost/scsi.c                         | 3 +++
 drivers/xen/xen-scsiback.c                   | 3 +++
 include/target/target_core_base.h            | 9 +++++++++
 include/target/target_core_fabric.h          | 9 +++++++++
 13 files changed, 55 insertions(+)

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index c12005eab14c..58f70cfec45a 100644
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -3867,6 +3867,9 @@ static const struct target_core_fabric_ops srpt_template = {
 	.tfc_discovery_attrs		= srpt_da_attrs,
 	.tfc_wwn_attrs			= srpt_wwn_attrs,
 	.tfc_tpg_attrib_attrs		= srpt_tpg_attrib_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 /**
diff --git a/drivers/scsi/elx/efct/efct_lio.c b/drivers/scsi/elx/efct/efct_lio.c
index a982b9cf9870..6a6ec32c46bd 100644
--- a/drivers/scsi/elx/efct/efct_lio.c
+++ b/drivers/scsi/elx/efct/efct_lio.c
@@ -1611,6 +1611,8 @@ static const struct target_core_fabric_ops efct_lio_ops = {
 	.sess_get_initiator_sid		= NULL,
 	.tfc_tpg_base_attrs		= efct_lio_tpg_attrs,
 	.tfc_tpg_attrib_attrs           = efct_lio_tpg_attrib_attrs,
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static const struct target_core_fabric_ops efct_lio_npiv_ops = {
@@ -1646,6 +1648,9 @@ static const struct target_core_fabric_ops efct_lio_npiv_ops = {
 	.sess_get_initiator_sid		= NULL,
 	.tfc_tpg_base_attrs		= efct_lio_npiv_tpg_attrs,
 	.tfc_tpg_attrib_attrs		= efct_lio_npiv_tpg_attrib_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 int efct_scsi_tgt_driver_init(void)
diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
index 385f812b8793..4dc411a58107 100644
--- a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
+++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
@@ -3975,6 +3975,9 @@ static const struct target_core_fabric_ops ibmvscsis_ops = {
 	.fabric_drop_tpg		= ibmvscsis_drop_tpg,
 
 	.tfc_wwn_attrs			= ibmvscsis_wwn_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static void ibmvscsis_dev_release(struct device *dev) {};
diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.c b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
index 68a0e6a2fb6e..7e7460a747a4 100644
--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
@@ -1822,6 +1822,9 @@ static const struct target_core_fabric_ops tcm_qla2xxx_ops = {
 	.tfc_wwn_attrs			= tcm_qla2xxx_wwn_attrs,
 	.tfc_tpg_base_attrs		= tcm_qla2xxx_tpg_attrs,
 	.tfc_tpg_attrib_attrs		= tcm_qla2xxx_tpg_attrib_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static const struct target_core_fabric_ops tcm_qla2xxx_npiv_ops = {
@@ -1859,6 +1862,9 @@ static const struct target_core_fabric_ops tcm_qla2xxx_npiv_ops = {
 	.fabric_init_nodeacl		= tcm_qla2xxx_init_nodeacl,
 
 	.tfc_wwn_attrs			= tcm_qla2xxx_wwn_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static int tcm_qla2xxx_register_configfs(void)
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index bf190dcb9eee..88db94f382bb 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1590,4 +1590,7 @@ const struct target_core_fabric_ops iscsi_ops = {
 	.tfc_tpg_nacl_param_attrs	= lio_target_nacl_param_attrs,
 
 	.write_pending_must_be_called	= 1,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
index 4ec99a55ac30..fbacccdd2ff6 100644
--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c
@@ -1102,6 +1102,8 @@ static const struct target_core_fabric_ops loop_ops = {
 	.tfc_wwn_attrs			= tcm_loop_wwn_attrs,
 	.tfc_tpg_base_attrs		= tcm_loop_tpg_attrs,
 	.tfc_tpg_attrib_attrs		= tcm_loop_tpg_attrib_attrs,
+	.default_submit_type		= TARGET_QUEUE_SUBMIT,
+	.direct_submit_supp		= 0,
 };
 
 static int __init tcm_loop_fabric_init(void)
diff --git a/drivers/target/sbp/sbp_target.c b/drivers/target/sbp/sbp_target.c
index 2a761bc09193..b604fcae21e1 100644
--- a/drivers/target/sbp/sbp_target.c
+++ b/drivers/target/sbp/sbp_target.c
@@ -2278,6 +2278,9 @@ static const struct target_core_fabric_ops sbp_ops = {
 	.tfc_wwn_attrs			= sbp_wwn_attrs,
 	.tfc_tpg_base_attrs		= sbp_tpg_base_attrs,
 	.tfc_tpg_attrib_attrs		= sbp_tpg_attrib_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static int __init sbp_init(void)
diff --git a/drivers/target/tcm_fc/tfc_conf.c b/drivers/target/tcm_fc/tfc_conf.c
index 6ac3fc1a7d39..5ee03d1cba2b 100644
--- a/drivers/target/tcm_fc/tfc_conf.c
+++ b/drivers/target/tcm_fc/tfc_conf.c
@@ -432,6 +432,9 @@ static const struct target_core_fabric_ops ft_fabric_ops = {
 
 	.tfc_wwn_attrs			= ft_wwn_attrs,
 	.tfc_tpg_nacl_base_attrs	= ft_nacl_base_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static struct notifier_block ft_notifier = {
diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 79ed2e6e576a..ff33f31bcdf6 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1687,6 +1687,9 @@ static const struct target_core_fabric_ops usbg_ops = {
 
 	.tfc_wwn_attrs			= usbg_wwn_attrs,
 	.tfc_tpg_base_attrs		= usbg_base_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 /* Start gadget.c code */
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index abef0619c790..dc274463bdf0 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -2598,6 +2598,9 @@ static const struct target_core_fabric_ops vhost_scsi_ops = {
 	.tfc_wwn_attrs			= vhost_scsi_wwn_attrs,
 	.tfc_tpg_base_attrs		= vhost_scsi_tpg_attrs,
 	.tfc_tpg_attrib_attrs		= vhost_scsi_tpg_attrib_attrs,
+
+	.default_submit_type		= TARGET_QUEUE_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static int __init vhost_scsi_init(void)
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 8b77e4c06e43..0c51edfd13dc 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -1832,6 +1832,9 @@ static const struct target_core_fabric_ops scsiback_ops = {
 	.tfc_wwn_attrs			= scsiback_wwn_attrs,
 	.tfc_tpg_base_attrs		= scsiback_tpg_attrs,
 	.tfc_tpg_param_attrs		= scsiback_param_attrs,
+
+	.default_submit_type		= TARGET_DIRECT_SUBMIT,
+	.direct_submit_supp		= 1,
 };
 
 static const struct xenbus_device_id scsiback_ids[] = {
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 159567359bbb..401abdf8a9ef 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -108,6 +108,15 @@
 #define SE_MODE_PAGE_BUF			512
 #define SE_SENSE_BUF				96
 
+enum target_submit_type {
+	/* Use the fabric driver's default submission type */
+	TARGET_FABRIC_DEFAULT_SUBMIT,
+	/* Submit from the calling context */
+	TARGET_DIRECT_SUBMIT,
+	/* Defer submission to the LIO workqueue */
+	TARGET_QUEUE_SUBMIT,
+};
+
 /* struct se_hba->hba_flags */
 enum hba_flags_table {
 	HBA_FLAGS_INTERNAL_USE	= 0x01,
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 2a6c4c935666..dcd7d76d2f30 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -118,6 +118,15 @@ struct target_core_fabric_ops {
 	 * its entirety before a command is aborted.
 	 */
 	unsigned int write_pending_must_be_called:1;
+	/*
+	 * Set this if the driver supports submitting commands to the backend
+	 * from target_submit/target_submit_cmd.
+	 */
+	unsigned int direct_submit_supp:1;
+	/*
+	 * Set this to a target_submit_type value.
+	 */
+	u8 default_submit_type;
 };
 
 int target_register_template(const struct target_core_fabric_ops *fo);
-- 
2.34.1

[PATCH v2 3/8] target: Move core_alua_check_nonop_delay call

[Mike Christie]

This moves core_alua_check_nonop_delay to transport_handle_cdb_direct so
the iSCSI target driver doesn't have to call as many core functions
directly. This patchset will eventually merge transport_handle_cdb_direct
and target_submit so iSCSI and the other drivers call a common function.

It will also be helpful with the next patches which allow the iSCSI
target to defer command submission to the lio submission workqueue,
because we will have a common submission function for that which will
be based on transport_handle_cdb_direct/target_submit.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/iscsi/iscsi_target.c    |  6 ------
 drivers/target/target_core_alua.c      |  1 -
 drivers/target/target_core_transport.c | 12 ++++++------
 include/target/target_core_fabric.h    |  2 --
 4 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index b516c2893420..1d25e64b068a 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1234,12 +1234,6 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
 	spin_lock_bh(&conn->cmd_lock);
 	list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
 	spin_unlock_bh(&conn->cmd_lock);
-	/*
-	 * Check if we need to delay processing because of ALUA
-	 * Active/NonOptimized primary access state..
-	 */
-	core_alua_check_nonop_delay(&cmd->se_cmd);
-
 	return 0;
 }
 EXPORT_SYMBOL(iscsit_setup_scsi_cmd);
diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
index 3372856319f7..01751faad386 100644
--- a/drivers/target/target_core_alua.c
+++ b/drivers/target/target_core_alua.c
@@ -850,7 +850,6 @@ int core_alua_check_nonop_delay(
 	msleep_interruptible(cmd->alua_nonop_delay);
 	return 0;
 }
-EXPORT_SYMBOL(core_alua_check_nonop_delay);
 
 static int core_alua_write_tpg_metadata(
 	const char *path,
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 0686882bcbda..709314415a01 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1587,6 +1587,12 @@ int transport_handle_cdb_direct(
 
 	might_sleep();
 
+	/*
+	 * Check if we need to delay processing because of ALUA
+	 * Active/NonOptimized primary access state..
+	 */
+	core_alua_check_nonop_delay(cmd);
+
 	if (!cmd->se_lun) {
 		dump_stack();
 		pr_err("cmd->se_lun is NULL\n");
@@ -1818,12 +1824,6 @@ void target_submit(struct se_cmd *se_cmd)
 
 	}
 
-	/*
-	 * Check if we need to delay processing because of ALUA
-	 * Active/NonOptimized primary access state..
-	 */
-	core_alua_check_nonop_delay(se_cmd);
-
 	transport_handle_cdb_direct(se_cmd);
 }
 EXPORT_SYMBOL_GPL(target_submit);
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index dcd7d76d2f30..e5fcfb845529 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -206,8 +206,6 @@ void	target_stop_session(struct se_session *se_sess);
 void	target_wait_for_sess_cmds(struct se_session *);
 void	target_show_cmd(const char *pfx, struct se_cmd *cmd);
 
-int	core_alua_check_nonop_delay(struct se_cmd *);
-
 int	core_tmr_alloc_req(struct se_cmd *, void *, u8, gfp_t);
 void	core_tmr_release_req(struct se_tmr_req *);
 int	transport_generic_handle_tmr(struct se_cmd *);
-- 
2.34.1

[PATCH v2 4/8] target: Move buffer clearing hack

[Mike Christie]

This moves the hack to clear some buffers to transport_handle_cdb_direct
so we can eventually merge transport_handle_cdb_direct and target_submit.

This also fixes up the comment so it's clear it was only for udev and
reflects that the referenced function does not exist and we now allow
more than 1 page for control CDBs.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/target_core_transport.c | 49 +++++++++++---------------
 1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 709314415a01..c2ddd09051e8 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1593,6 +1593,27 @@ int transport_handle_cdb_direct(
 	 */
 	core_alua_check_nonop_delay(cmd);
 
+	if (cmd->t_data_nents != 0) {
+		/*
+		 * This is primarily a hack for udev and tcm loop which sends
+		 * INQUIRYs with a single page and expects the data to be
+		 * cleared.
+		 */
+		if (!(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
+		    cmd->data_direction == DMA_FROM_DEVICE) {
+			struct scatterlist *sgl = cmd->t_data_sg;
+			unsigned char *buf = NULL;
+
+			BUG_ON(!sgl);
+
+			buf = kmap_local_page(sg_page(sgl));
+			if (buf) {
+				memset(buf + sgl->offset, 0, sgl->length);
+				kunmap_local(buf);
+			}
+		}
+	}
+
 	if (!cmd->se_lun) {
 		dump_stack();
 		pr_err("cmd->se_lun is NULL\n");
@@ -1796,34 +1817,6 @@ EXPORT_SYMBOL_GPL(target_submit_prep);
  */
 void target_submit(struct se_cmd *se_cmd)
 {
-	struct scatterlist *sgl = se_cmd->t_data_sg;
-	unsigned char *buf = NULL;
-
-	might_sleep();
-
-	if (se_cmd->t_data_nents != 0) {
-		BUG_ON(!sgl);
-		/*
-		 * A work-around for tcm_loop as some userspace code via
-		 * scsi-generic do not memset their associated read buffers,
-		 * so go ahead and do that here for type non-data CDBs.  Also
-		 * note that this is currently guaranteed to be a single SGL
-		 * for this case by target core in target_setup_cmd_from_cdb()
-		 * -> transport_generic_cmd_sequencer().
-		 */
-		if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
-		     se_cmd->data_direction == DMA_FROM_DEVICE) {
-			if (sgl)
-				buf = kmap(sg_page(sgl)) + sgl->offset;
-
-			if (buf) {
-				memset(buf, 0, sgl->length);
-				kunmap(sg_page(sgl));
-			}
-		}
-
-	}
-
 	transport_handle_cdb_direct(se_cmd);
 }
 EXPORT_SYMBOL_GPL(target_submit);
-- 
2.34.1

[PATCH v2 5/8] target: Kill transport_handle_cdb_direct

[Mike Christie]

This moves the code from transport_handle_cdb_direct to target_submit and
has iSCSI call target_submit.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/iscsi/iscsi_target_erl1.c |  2 +-
 drivers/target/iscsi/iscsi_target_tmr.c  |  2 +-
 drivers/target/target_core_transport.c   | 27 +++++++-----------------
 include/target/target_core_fabric.h      |  3 +--
 4 files changed, 11 insertions(+), 23 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_erl1.c b/drivers/target/iscsi/iscsi_target_erl1.c
index f460a66c0e7c..679720021183 100644
--- a/drivers/target/iscsi/iscsi_target_erl1.c
+++ b/drivers/target/iscsi/iscsi_target_erl1.c
@@ -948,7 +948,7 @@ int iscsit_execute_cmd(struct iscsit_cmd *cmd, int ooo)
 
 			iscsit_set_unsolicited_dataout(cmd);
 		}
-		return transport_handle_cdb_direct(&cmd->se_cmd);
+		return target_submit(&cmd->se_cmd);
 
 	case ISCSI_OP_NOOP_OUT:
 	case ISCSI_OP_TEXT:
diff --git a/drivers/target/iscsi/iscsi_target_tmr.c b/drivers/target/iscsi/iscsi_target_tmr.c
index afc801f255f5..9c4aa01b6351 100644
--- a/drivers/target/iscsi/iscsi_target_tmr.c
+++ b/drivers/target/iscsi/iscsi_target_tmr.c
@@ -318,7 +318,7 @@ static int iscsit_task_reassign_complete_read(
 		pr_debug("READ ITT: 0x%08x: t_state: %d never sent to"
 			" transport\n", cmd->init_task_tag,
 			cmd->se_cmd.t_state);
-		transport_handle_cdb_direct(se_cmd);
+		target_submit(se_cmd);
 		return 0;
 	}
 
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index c2ddd09051e8..d78f24c2dfcf 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1576,12 +1576,14 @@ target_cmd_parse_cdb(struct se_cmd *cmd)
 }
 EXPORT_SYMBOL(target_cmd_parse_cdb);
 
-/*
- * Used by fabric module frontends to queue tasks directly.
- * May only be used from process context.
+/**
+ * target_submit - perform final initialization and submit cmd to LIO core
+ * @cmd: command descriptor to submit
+ *
+ * target_submit_prep or something similar must have been called on the cmd,
+ * and this must be called from process context.
  */
-int transport_handle_cdb_direct(
-	struct se_cmd *cmd)
+int target_submit(struct se_cmd *cmd)
 {
 	sense_reason_t ret;
 
@@ -1641,7 +1643,7 @@ int transport_handle_cdb_direct(
 		transport_generic_request_failure(cmd, ret);
 	return 0;
 }
-EXPORT_SYMBOL(transport_handle_cdb_direct);
+EXPORT_SYMBOL_GPL(target_submit);
 
 sense_reason_t
 transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl,
@@ -1808,19 +1810,6 @@ int target_submit_prep(struct se_cmd *se_cmd, unsigned char *cdb,
 }
 EXPORT_SYMBOL_GPL(target_submit_prep);
 
-/**
- * target_submit - perform final initialization and submit cmd to LIO core
- * @se_cmd: command descriptor to submit
- *
- * target_submit_prep must have been called on the cmd, and this must be
- * called from process context.
- */
-void target_submit(struct se_cmd *se_cmd)
-{
-	transport_handle_cdb_direct(se_cmd);
-}
-EXPORT_SYMBOL_GPL(target_submit);
-
 /**
  * target_submit_cmd - lookup unpacked lun and submit uninitialized se_cmd
  *
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index e5fcfb845529..a808c3c32004 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -175,7 +175,7 @@ int	target_submit_prep(struct se_cmd *se_cmd, unsigned char *cdb,
 		struct scatterlist *sgl, u32 sgl_count,
 		struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
 		struct scatterlist *sgl_prot, u32 sgl_prot_count, gfp_t gfp);
-void	target_submit(struct se_cmd *se_cmd);
+int	target_submit(struct se_cmd *se_cmd);
 sense_reason_t transport_lookup_cmd_lun(struct se_cmd *);
 sense_reason_t target_cmd_init_cdb(struct se_cmd *se_cmd, unsigned char *cdb,
 				   gfp_t gfp);
@@ -188,7 +188,6 @@ int	target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,
 		unsigned char *sense, u64 unpacked_lun,
 		void *fabric_tmr_ptr, unsigned char tm_type,
 		gfp_t, u64, int);
-int	transport_handle_cdb_direct(struct se_cmd *);
 sense_reason_t	transport_generic_new_cmd(struct se_cmd *);
 
 void	target_put_cmd_and_wait(struct se_cmd *cmd);
-- 
2.34.1

[PATCH v2 6/8] scsi: target: Allow userspace to request direct submissions

[Mike Christie]

This allows userspace to request the fabric drivers do direct submissions
if they support it. With the new device file, submit_type, users can
write 0 - 2 to control how commands are submitted to the backend:

0 - TARGET_FABRIC_DEFAULT_SUBMIT - LIO will use the fabric's default
submission type. This is the default for compat.
1 - TARGET_DIRECT_SUBMIT - LIO will submit the cmd to the backend from
the calling context if the fabric the cmd was received on supports it,
else it will use the fabric's default type.
2 - TARGET_QUEUE_SUBMIT - LIO will queue the cmd to the LIO submission
workqueue which will pass it to the backend.

When using a nvme drive and vhost-scsi with direct submission we see
around a 20% improvement in 4K IOs:

fio jobs        1       2       4       8       10
--------------------------------------------------
defer           94K     190K    394K    770K    890K
direct          128K    252K    488K    950K    -

And when using the queueing mode, we now no longer see issues like where
the iSCSI tx thread is blocked in the block layer waiting on a tag so it
can't respond to a nop or perform IOs for other LUs.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/loopback/tcm_loop.c     |  2 +-
 drivers/target/target_core_configfs.c  | 22 ++++++++++++++
 drivers/target/target_core_device.c    |  1 +
 drivers/target/target_core_transport.c | 41 +++++++++++++++++++-------
 drivers/vhost/scsi.c                   |  2 +-
 include/target/target_core_base.h      |  1 +
 6 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
index fbacccdd2ff6..8e4035ff3674 100644
--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c
@@ -154,7 +154,7 @@ static void tcm_loop_target_queue_cmd(struct tcm_loop_cmd *tl_cmd)
 			       GFP_ATOMIC))
 		return;
 
-	target_queue_submission(se_cmd);
+	target_submit(se_cmd);
 	return;
 
 out_done:
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index d5860c1c1f46..a5f58988130a 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -577,6 +577,7 @@ DEF_CONFIGFS_ATTRIB_SHOW(unmap_granularity_alignment);
 DEF_CONFIGFS_ATTRIB_SHOW(unmap_zeroes_data);
 DEF_CONFIGFS_ATTRIB_SHOW(max_write_same_len);
 DEF_CONFIGFS_ATTRIB_SHOW(emulate_rsoc);
+DEF_CONFIGFS_ATTRIB_SHOW(submit_type);
 
 #define DEF_CONFIGFS_ATTRIB_STORE_U32(_name)				\
 static ssize_t _name##_store(struct config_item *item, const char *page,\
@@ -1231,6 +1232,24 @@ static ssize_t emulate_rsoc_store(struct config_item *item,
 	return count;
 }
 
+static ssize_t submit_type_store(struct config_item *item, const char *page,
+				 size_t count)
+{
+	struct se_dev_attrib *da = to_attrib(item);
+	int ret;
+	u8 val;
+
+	ret = kstrtou8(page, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val > TARGET_QUEUE_SUBMIT)
+		return -EINVAL;
+
+	da->submit_type = val;
+	return count;
+}
+
 CONFIGFS_ATTR(, emulate_model_alias);
 CONFIGFS_ATTR(, emulate_dpo);
 CONFIGFS_ATTR(, emulate_fua_write);
@@ -1266,6 +1285,7 @@ CONFIGFS_ATTR(, unmap_zeroes_data);
 CONFIGFS_ATTR(, max_write_same_len);
 CONFIGFS_ATTR(, alua_support);
 CONFIGFS_ATTR(, pgr_support);
+CONFIGFS_ATTR(, submit_type);
 
 /*
  * dev_attrib attributes for devices using the target core SBC/SPC
@@ -1308,6 +1328,7 @@ struct configfs_attribute *sbc_attrib_attrs[] = {
 	&attr_alua_support,
 	&attr_pgr_support,
 	&attr_emulate_rsoc,
+	&attr_submit_type,
 	NULL,
 };
 EXPORT_SYMBOL(sbc_attrib_attrs);
@@ -1325,6 +1346,7 @@ struct configfs_attribute *passthrough_attrib_attrs[] = {
 	&attr_emulate_pr,
 	&attr_alua_support,
 	&attr_pgr_support,
+	&attr_submit_type,
 	NULL,
 };
 EXPORT_SYMBOL(passthrough_attrib_attrs);
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index b7ac60f4a219..0f3fd775fe6d 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -779,6 +779,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
 	dev->dev_attrib.unmap_zeroes_data =
 				DA_UNMAP_ZEROES_DATA_DEFAULT;
 	dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;
+	dev->dev_attrib.submit_type = TARGET_FABRIC_DEFAULT_SUBMIT;
 
 	xcopy_lun = &dev->xcopy_lun;
 	rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index d78f24c2dfcf..1fde18e1ef3f 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1576,14 +1576,7 @@ target_cmd_parse_cdb(struct se_cmd *cmd)
 }
 EXPORT_SYMBOL(target_cmd_parse_cdb);
 
-/**
- * target_submit - perform final initialization and submit cmd to LIO core
- * @cmd: command descriptor to submit
- *
- * target_submit_prep or something similar must have been called on the cmd,
- * and this must be called from process context.
- */
-int target_submit(struct se_cmd *cmd)
+static int __target_submit(struct se_cmd *cmd)
 {
 	sense_reason_t ret;
 
@@ -1643,7 +1636,6 @@ int target_submit(struct se_cmd *cmd)
 		transport_generic_request_failure(cmd, ret);
 	return 0;
 }
-EXPORT_SYMBOL_GPL(target_submit);
 
 sense_reason_t
 transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl,
@@ -1905,7 +1897,7 @@ void target_queued_submit_work(struct work_struct *work)
 			se_plug = target_plug_device(se_dev);
 		}
 
-		target_submit(se_cmd);
+		__target_submit(se_cmd);
 	}
 
 	if (se_plug)
@@ -1928,6 +1920,35 @@ void target_queue_submission(struct se_cmd *se_cmd)
 }
 EXPORT_SYMBOL_GPL(target_queue_submission);
 
+/**
+ * target_submit - perform final initialization and submit cmd to LIO core
+ * @cmd: command descriptor to submit
+ *
+ * target_submit_prep or something similar must have been called on the cmd,
+ * and this must be called from process context.
+ */
+int target_submit(struct se_cmd *se_cmd)
+{
+	const struct target_core_fabric_ops *tfo = se_cmd->se_sess->se_tpg->se_tpg_tfo;
+	struct se_dev_attrib *da = &se_cmd->se_dev->dev_attrib;
+	u8 submit_type;
+
+	if (da->submit_type == TARGET_FABRIC_DEFAULT_SUBMIT)
+		submit_type = tfo->default_submit_type;
+	else if (da->submit_type == TARGET_DIRECT_SUBMIT &&
+		 tfo->direct_submit_supp)
+		submit_type = TARGET_DIRECT_SUBMIT;
+	else
+		submit_type = TARGET_QUEUE_SUBMIT;
+
+	if (submit_type == TARGET_DIRECT_SUBMIT)
+		return __target_submit(se_cmd);
+
+	target_queue_submission(se_cmd);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(target_submit);
+
 static void target_complete_tmr_failure(struct work_struct *work)
 {
 	struct se_cmd *se_cmd = container_of(work, struct se_cmd, work);
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index dc274463bdf0..4e3b2c25c721 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -909,7 +909,7 @@ static void vhost_scsi_target_queue_cmd(struct vhost_scsi_cmd *cmd)
 			       cmd->tvc_prot_sgl_count, GFP_KERNEL))
 		return;
 
-	target_queue_submission(se_cmd);
+	target_submit(se_cmd);
 }
 
 static void
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 401abdf8a9ef..97099a5e3f6c 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -726,6 +726,7 @@ struct se_dev_attrib {
 	u32		unmap_granularity;
 	u32		unmap_granularity_alignment;
 	u32		max_write_same_len;
+	u8		submit_type;
 	struct se_device *da_dev;
 	struct config_group da_group;
 };
-- 
2.34.1

[PATCH v2 7/8] scsi: target: Unexport target_queue_submission

[Mike Christie]

target_queue_submission is not called by drivers anymore so unexport it.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/target_core_transport.c | 3 +--
 include/target/target_core_fabric.h    | 1 -
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 1fde18e1ef3f..c81def3c96df 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1908,7 +1908,7 @@ void target_queued_submit_work(struct work_struct *work)
  * target_queue_submission - queue the cmd to run on the LIO workqueue
  * @se_cmd: command descriptor to submit
  */
-void target_queue_submission(struct se_cmd *se_cmd)
+static void target_queue_submission(struct se_cmd *se_cmd)
 {
 	struct se_device *se_dev = se_cmd->se_dev;
 	int cpu = se_cmd->cpuid;
@@ -1918,7 +1918,6 @@ void target_queue_submission(struct se_cmd *se_cmd)
 	llist_add(&se_cmd->se_cmd_list, &sq->cmd_list);
 	queue_work_on(cpu, target_submission_wq, &sq->work);
 }
-EXPORT_SYMBOL_GPL(target_queue_submission);
 
 /**
  * target_submit - perform final initialization and submit cmd to LIO core
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index a808c3c32004..3378ff9ee271 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -182,7 +182,6 @@ sense_reason_t target_cmd_init_cdb(struct se_cmd *se_cmd, unsigned char *cdb,
 sense_reason_t target_cmd_parse_cdb(struct se_cmd *);
 void	target_submit_cmd(struct se_cmd *, struct se_session *, unsigned char *,
 		unsigned char *, u64, u32, int, int, int);
-void	target_queue_submission(struct se_cmd *se_cmd);
 
 int	target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,
 		unsigned char *sense, u64 unpacked_lun,
-- 
2.34.1

[PATCH v2 8/8] scsi: target: Export fabric driver direct submit settings

[Mike Christie]

This exports the fabric driver's direct submit settings, so users know
what the driver supports. It will be helpful when they are exporting
a device through different targets and one doesn't support direct
submission.

The new files allow the fabric to report what submission types they
default to and if they support direct submission:

default_submit_type:
1 - TARGET_DIRECT_SUBMIT - If the user has not requested a specific
value then the fabric requests direction submission.
2 - TARGET_QUEUE_SUBMIT - If the user has not requested a specific
value then the fabric requests queued submission.

Note that these fabric values are based on what the fabric driver
currently defaults to for compat with exiting setups.

direct_submit_supported:
0 - The fabric does not support direct submission.
1 - The fabric supports direct submission.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/target_core_fabric_configfs.c | 24 ++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/target/target_core_fabric_configfs.c b/drivers/target/target_core_fabric_configfs.c
index b7c637644cd4..7156a4dc1ca7 100644
--- a/drivers/target/target_core_fabric_configfs.c
+++ b/drivers/target/target_core_fabric_configfs.c
@@ -1065,8 +1065,32 @@ target_fabric_wwn_cmd_completion_affinity_store(struct config_item *item,
 }
 CONFIGFS_ATTR(target_fabric_wwn_, cmd_completion_affinity);
 
+static ssize_t
+target_fabric_wwn_default_submit_type_show(struct config_item *item,
+					   char *page)
+{
+	struct se_wwn *wwn = container_of(to_config_group(item), struct se_wwn,
+					  param_group);
+	return sysfs_emit(page, "%u\n",
+			  wwn->wwn_tf->tf_ops->default_submit_type);
+}
+CONFIGFS_ATTR_RO(target_fabric_wwn_, default_submit_type);
+
+static ssize_t
+target_fabric_wwn_direct_submit_supported_show(struct config_item *item,
+					       char *page)
+{
+	struct se_wwn *wwn = container_of(to_config_group(item), struct se_wwn,
+					  param_group);
+	return sysfs_emit(page, "%u\n",
+			  wwn->wwn_tf->tf_ops->direct_submit_supp);
+}
+CONFIGFS_ATTR_RO(target_fabric_wwn_, direct_submit_supported);
+
 static struct configfs_attribute *target_fabric_wwn_param_attrs[] = {
 	&target_fabric_wwn_attr_cmd_completion_affinity,
+	&target_fabric_wwn_attr_default_submit_type,
+	&target_fabric_wwn_attr_direct_submit_supported,
 	NULL,
 };
 
-- 
2.34.1

[PATCH v2 0/8] scsi: target: Allow userspace to config cmd submission

[Mike Christie]

The following patches were made over Linus's tree but apply over Martin's
branches. They allow userspace to configure how fabric drivers submit cmds
to backend drivers.

Right now loop and vhost use a worker thread, and the other drivers submit
from the contexts they receive/process the cmd from. For multiple LUN
cases where the target can queue more cmds than the backend can handle
then deferring to a worker thread is safest because the backend driver can
block when doing things like waiting for a free request/tag. Deferring also
helps when the target has to handle transport level requests from the
recv context.

For cases where the backend devices can queue everything the target sends,
then there is no need to defer to a workqueue and you can see a perf boost of
up to 26% for small IO workloads. For a nvme device and vhost-scsi I can
see with 4K IOs:

fio jobs        1       2       4       8       10
--------------------------------------------------
workqueue
submit           94K     190K    394K    770K    890K

direct
submit          128K    252K    488K    950K    -



v2:
- Use sysfs_emit.
- Add iSCSI target support so now all targets are supported.

Re: [PATCH v2 0/8] scsi: target: Allow userspace to config cmd submission

[Martin K. Petersen]

Mike,

> The following patches were made over Linus's tree but apply over Martin's
> branches. They allow userspace to configure how fabric drivers submit cmds
> to backend drivers.

Applied to 6.7/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH v2 0/8] scsi: target: Allow userspace to config cmd submission

[Martin K. Petersen]

On Wed, 27 Sep 2023 21:31:32 -0500, Mike Christie wrote:

> The following patches were made over Linus's tree but apply over Martin's
> branches. They allow userspace to configure how fabric drivers submit cmds
> to backend drivers.
> 
> Right now loop and vhost use a worker thread, and the other drivers submit
> from the contexts they receive/process the cmd from. For multiple LUN
> cases where the target can queue more cmds than the backend can handle
> then deferring to a worker thread is safest because the backend driver can
> block when doing things like waiting for a free request/tag. Deferring also
> helps when the target has to handle transport level requests from the
> recv context.
> 
> [...]

Applied to 6.7/scsi-queue, thanks!

[1/8] scsi: target: Make write_pending_must_be_called a bit field
      https://git.kernel.org/mkp/scsi/c/40ddd6df93a3
[2/8] scsi: target: Have drivers report if they support direct submissions
      https://git.kernel.org/mkp/scsi/c/194605d45dcb
[3/8] target: Move core_alua_check_nonop_delay call
      https://git.kernel.org/mkp/scsi/c/ee48345e1cca
[4/8] target: Move buffer clearing hack
      https://git.kernel.org/mkp/scsi/c/5c48a4ea3280
[5/8] target: Kill transport_handle_cdb_direct
      https://git.kernel.org/mkp/scsi/c/428926796e7f
[6/8] scsi: target: Allow userspace to request direct submissions
      https://git.kernel.org/mkp/scsi/c/e2f4ea40138e
[7/8] scsi: target: Unexport target_queue_submission
      https://git.kernel.org/mkp/scsi/c/e344c00e7ccd
[8/8] scsi: target: Export fabric driver direct submit settings
      https://git.kernel.org/mkp/scsi/c/6dbc829d101d

-- 
Martin K. Petersen	Oracle Linux Engineering