target: allow ALUA setup for some passthrough backends

This patch allows passthrough backends to use the core/base LIO
ALUA setup and state checks, but still handle the execution of
commands.

This will allow the target_core_user module to execute STPG and RTPG
in userspace, and not have to duplicate the ALUA state checks, path
information (needed so we can check if command is executable on
specific paths) and setup (rtslib sets/updates the configfs ALUA
interface like it does for iblock or file).

For STPG, the target_core_user userspace daemon, tcmu-runner will
still execute the STPG, and to update the core/base LIO state it
will use the existing configfs interface. For RTPG, tcmu-runner
will loop over configfs and/or cache the state.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_alua.c

@@ -691,7 +691,7 @@ target_alua_state_check(struct se_cmd *cmd)
 
 	if (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE)
 		return 0;
-	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
+	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA)
 		return 0;
 
 	/*
@@ -1973,7 +1973,7 @@ ssize_t core_alua_store_tg_pt_gp_info(
 	unsigned char buf[TG_PT_GROUP_NAME_BUF];
 	int move = 0;
 
-	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH ||
+	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA ||
 	    (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
 		return -ENODEV;
 
@@ -2230,7 +2230,7 @@ ssize_t core_alua_store_offline_bit(
 	unsigned long tmp;
 	int ret;
 
-	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH ||
+	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA ||
 	    (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
 		return -ENODEV;
 
@@ -2316,7 +2316,8 @@ ssize_t core_alua_store_secondary_write_metadata(
 
 int core_setup_alua(struct se_device *dev)
 {
-	if (!(dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH) &&
+	if (!(dev->transport->transport_flags &
+	     TRANSPORT_FLAG_PASSTHROUGH_ALUA) &&
 	    !(dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE)) {
 		struct t10_alua_lu_gp_member *lu_gp_mem;
 

drivers/target/target_core_pscsi.c

@@ -1080,7 +1080,8 @@ static void pscsi_req_done(struct request *req, int uptodate)
 static const struct target_backend_ops pscsi_ops = {
 	.name			= "pscsi",
 	.owner			= THIS_MODULE,
-	.transport_flags	= TRANSPORT_FLAG_PASSTHROUGH,
+	.transport_flags	= TRANSPORT_FLAG_PASSTHROUGH |
+				  TRANSPORT_FLAG_PASSTHROUGH_ALUA,
 	.attach_hba		= pscsi_attach_hba,
 	.detach_hba		= pscsi_detach_hba,
 	.pmode_enable_hba	= pscsi_pmode_enable_hba,

drivers/target/target_core_tpg.c

@@ -602,7 +602,8 @@ int core_tpg_add_lun(
 	if (ret)
 		goto out_kill_ref;
 
-	if (!(dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH) &&
+	if (!(dev->transport->transport_flags &
+	     TRANSPORT_FLAG_PASSTHROUGH_ALUA) &&
 	    !(dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
 		target_attach_tg_pt_gp(lun, dev->t10_alua.default_tg_pt_gp);
 

include/target/target_core_backend.h

@@ -4,7 +4,12 @@
 #include <linux/types.h>
 #include <target/target_core_base.h>
 
-#define TRANSPORT_FLAG_PASSTHROUGH		1
+#define TRANSPORT_FLAG_PASSTHROUGH		0x1
+/*
+ * ALUA commands, state checks and setup operations are handled by the
+ * backend module.
+ */
+#define TRANSPORT_FLAG_PASSTHROUGH_ALUA		0x2
 
 struct request_queue;
 struct scatterlist;