target: Add target_show_dynamic_sessions attribute helper

This patch adds a new helper function that can be used by fabric driver
TPG attributes for dumping the list of active sessions with a dynamically
generated se_node_acl. (generate_node_acl=1).

It prints one se_node_acl->initiatorname per line, up to PAGE_SIZE which
is due to the current limitiation of single page attribute output within
sysfs and configfs code.

Note that if a session is referencing a explicit NodeACL, the InitiatorName
will not appear within dynamic_sessions output.

Reported-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

3 files changed, 30 insertions, 0 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 0adc0f650213..e06c136ff839 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -404,6 +404,30 @@ void target_put_session(struct se_session *se_sess)
 }
 EXPORT_SYMBOL(target_put_session);
 
+ssize_t target_show_dynamic_sessions(struct se_portal_group *se_tpg, char *page)
+{
+        struct se_session *se_sess;
+        ssize_t len = 0;
+
+        spin_lock_bh(&se_tpg->session_lock);
+        list_for_each_entry(se_sess, &se_tpg->tpg_sess_list, sess_list) {
+                if (!se_sess->se_node_acl)
+                        continue;
+                if (!se_sess->se_node_acl->dynamic_node_acl)
+                        continue;
+                if (strlen(se_sess->se_node_acl->initiatorname) + 1 + len > PAGE_SIZE)
+                        break;
+
+                len += snprintf(page + len, PAGE_SIZE - len, "%s\n",
+                                se_sess->se_node_acl->initiatorname);
+                len += 1; /* Include NULL terminator */
+        }
+        spin_unlock_bh(&se_tpg->session_lock);
+
+        return len;
+}
+EXPORT_SYMBOL(target_show_dynamic_sessions);
+
 static void target_complete_nacl(struct kref *kref)
 {
         struct se_node_acl *nacl = container_of(kref,
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 22a4e98eec80..2f4a2505db4c 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -95,6 +95,7 @@ void	transport_register_session(struct se_portal_group *,
                 struct se_node_acl *, struct se_session *, void *);
 void    target_get_session(struct se_session *);
 void    target_put_session(struct se_session *);
+ssize_t target_show_dynamic_sessions(struct se_portal_group *, char *);
 void    transport_free_session(struct se_session *);
 void    target_put_nacl(struct se_node_acl *);
 void    transport_deregister_session_configfs(struct se_session *);
diff --git a/include/target/target_core_fabric_configfs.h b/include/target/target_core_fabric_configfs.h
index b32a14905cfa..7a0649c09e79 100644
--- a/include/target/target_core_fabric_configfs.h
+++ b/include/target/target_core_fabric_configfs.h
@@ -90,6 +90,11 @@ static struct target_fabric_tpg_attribute _fabric##_tpg_##_name =	\
         _fabric##_tpg_store_##_name);
 
 
+#define TF_TPG_BASE_ATTR_RO(_fabric, _name)                             \
+static struct target_fabric_tpg_attribute _fabric##_tpg_##_name =       \
+        __CONFIGFS_EATTR_RO(_name,                                      \
+        _fabric##_tpg_show_##_name);
+
 CONFIGFS_EATTR_STRUCT(target_fabric_wwn, target_fabric_configfs);
 #define TF_WWN_ATTR(_fabric, _name, _mode)                              \
 static struct target_fabric_wwn_attribute _fabric##_wwn_##_name =       \