target: Convert se_node_acl->device_list[] to RCU hlist
This patch converts se_node_acl->device_list[] table for mappedluns
to modern RCU hlist_head usage in order to support an arbitrary number
of node_acl lun mappings.
It converts transport_lookup_*_lun() fast-path code to use RCU read path
primitives when looking up se_dev_entry. It adds a new hlist_head at
se_node_acl->lun_entry_hlist for this purpose.
For transport_lookup_cmd_lun() code, it works with existing per-cpu
se_lun->lun_ref when associating se_cmd with se_lun + se_device.
Also, go ahead and update core_create_device_list_for_node() +
core_free_device_list_for_node() to use ->lun_entry_hlist.
It also converts se_dev_entry->pr_ref_count access to use modern
struct kref counting, and updates core_disable_device_list_for_node()
to kref_put() and block on se_deve->pr_comp waiting for outstanding PR
special-case PR references to drop, then invoke kfree_rcu() to wait
for the RCU grace period to complete before releasing memory.
So now that se_node_acl->lun_entry_hlist fast path access uses RCU
protected pointers, go ahead and convert remaining non-fast path
RCU updater code using ->lun_entry_lock to struct mutex to allow
callers to block while walking se_node_acl->lun_entry_hlist.
Finally drop the left-over core_clear_initiator_node_from_tpg() that
originally cleared lun_access during se_node_acl shutdown, as post
RCU conversion it now becomes duplicated logic.
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>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index d0344ad..a04a6e3 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -9,13 +9,15 @@
extern struct list_head g_device_list;
struct se_dev_entry *core_get_se_deve_from_rtpi(struct se_node_acl *, u16);
-int core_free_device_list_for_node(struct se_node_acl *,
+void target_pr_kref_release(struct kref *);
+void core_free_device_list_for_node(struct se_node_acl *,
struct se_portal_group *);
void core_update_device_list_access(u32, u32, struct se_node_acl *);
+struct se_dev_entry *target_nacl_find_deve(struct se_node_acl *, u32);
int core_enable_device_list_for_node(struct se_lun *, struct se_lun_acl *,
u32, u32, struct se_node_acl *, struct se_portal_group *);
-int core_disable_device_list_for_node(struct se_lun *, struct se_lun_acl *,
- u32, u32, struct se_node_acl *, struct se_portal_group *);
+void core_disable_device_list_for_node(struct se_lun *, struct se_dev_entry *,
+ struct se_node_acl *, struct se_portal_group *);
void core_clear_lun_from_tpg(struct se_lun *, struct se_portal_group *);
int core_dev_export(struct se_device *, struct se_portal_group *,
struct se_lun *);