target: Convert se_portal_group->tpg_lun_list[] to RCU hlist

This patch converts the fixed size se_portal_group->tpg_lun_list[]
to use modern RCU with hlist_head in order to support an arbitary
number of se_lun ports per target endpoint.

It includes dropping core_tpg_alloc_lun() from core_dev_add_lun(),
and calling it directly from target_fabric_make_lun() to allocate
a new se_lun.  And add a new target_fabric_port_release() configfs
item callback to invoke kfree_rcu() to release memory during
se_lun->lun_group shutdown.

Also now that se_node_acl->lun_entry_hlist is using RCU, convert
existing tpg_lun_lock to struct mutex so core_tpg_add_node_to_devs()
can perform RCU updater logic without releasing ->tpg_lun_mutex.

Also, drop core_tpg_clear_object_luns() and it's single consumer
in iscsi-target, which is duplicating TPG LUN shutdown logic and
is current code results in a NOP.

Finally, sbp-target and xen-scsiback fabric driver conversions are
included, which are required due to the non-standard way they use
->tpg_lun_hlist.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index a04a6e396ae3..2c160ceaf03f 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -23,13 +23,13 @@ int	core_dev_export(struct se_device *, struct se_portal_group *,
 		struct se_lun *);
 void	core_dev_unexport(struct se_device *, struct se_portal_group *,
 		struct se_lun *);
-struct se_lun *core_dev_add_lun(struct se_portal_group *, struct se_device *, u32);
+int	core_dev_add_lun(struct se_portal_group *, struct se_device *,
+		struct se_lun *lun);
 void	core_dev_del_lun(struct se_portal_group *, struct se_lun *);
-struct se_lun *core_get_lun_from_tpg(struct se_portal_group *, u32);
 struct se_lun_acl *core_dev_init_initiator_node_lun_acl(struct se_portal_group *,
 		struct se_node_acl *, u32, int *);
 int	core_dev_add_initiator_node_lun_acl(struct se_portal_group *,
-		struct se_lun_acl *, u32, u32);
+		struct se_lun_acl *, struct se_lun *lun, u32);
 int	core_dev_del_initiator_node_lun_acl(struct se_portal_group *,
 		struct se_lun *, struct se_lun_acl *);
 void	core_dev_free_initiator_node_lun_acl(struct se_portal_group *,