target: Add target_alloc_session() helper function

Based on HCH's original patch, this adds a full version to
support percpu-ida tag pre-allocation and callback function
pointer into fabric driver code to complete session setup.

Reported-by: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 62 insertions, 0 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 867bc6d0a68a..f5ad9e063b65 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -281,6 +281,17 @@ struct se_session *transport_init_session_tags(unsigned int tag_num,
         struct se_session *se_sess;
         int rc;
 
+        if (tag_num != 0 && !tag_size) {
+                pr_err("init_session_tags called with percpu-ida tag_num:"
+                       " %u, but zero tag_size\n", tag_num);
+                return ERR_PTR(-EINVAL);
+        }
+        if (!tag_num && tag_size) {
+                pr_err("init_session_tags called with percpu-ida tag_size:"
+                       " %u, but zero tag_num\n", tag_size);
+                return ERR_PTR(-EINVAL);
+        }
+
         se_sess = transport_init_session(sup_prot_ops);
         if (IS_ERR(se_sess))
                 return se_sess;
@@ -374,6 +385,51 @@ void transport_register_session(
 }
 EXPORT_SYMBOL(transport_register_session);
 
+struct se_session *
+target_alloc_session(struct se_portal_group *tpg,
+                     unsigned int tag_num, unsigned int tag_size,
+                     enum target_prot_op prot_op,
+                     const char *initiatorname, void *private,
+                     int (*callback)(struct se_portal_group *,
+                                     struct se_session *, void *))
+{
+        struct se_session *sess;
+
+        /*
+         * If the fabric driver is using percpu-ida based pre allocation
+         * of I/O descriptor tags, go ahead and perform that setup now..
+         */
+        if (tag_num != 0)
+                sess = transport_init_session_tags(tag_num, tag_size, prot_op);
+        else
+                sess = transport_init_session(prot_op);
+
+        if (IS_ERR(sess))
+                return sess;
+
+        sess->se_node_acl = core_tpg_check_initiator_node_acl(tpg,
+                                        (unsigned char *)initiatorname);
+        if (!sess->se_node_acl) {
+                transport_free_session(sess);
+                return ERR_PTR(-EACCES);
+        }
+        /*
+         * Go ahead and perform any remaining fabric setup that is
+         * required before transport_register_session().
+         */
+        if (callback != NULL) {
+                int rc = callback(tpg, sess, private);
+                if (rc) {
+                        transport_free_session(sess);
+                        return ERR_PTR(rc);
+                }
+        }
+
+        transport_register_session(tpg, sess->se_node_acl, sess, private);
+        return sess;
+}
+EXPORT_SYMBOL(target_alloc_session);
+
 static void target_release_session(struct kref *kref)
 {
         struct se_session *se_sess = container_of(kref,
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 56653408f53b..685a51aa98cc 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -108,6 +108,12 @@ void target_unregister_template(const struct target_core_fabric_ops *fo);
 int target_depend_item(struct config_item *item);
 void target_undepend_item(struct config_item *item);
 
+struct se_session *target_alloc_session(struct se_portal_group *,
+                unsigned int, unsigned int, enum target_prot_op prot_op,
+                const char *, void *,
+                int (*callback)(struct se_portal_group *,
+                                struct se_session *, void *));
+
 struct se_session *transport_init_session(enum target_prot_op);
 int transport_alloc_session_tags(struct se_session *, unsigned int,
                 unsigned int);