target: Add generic active I/O shutdown logic
This patch adds the initial pieces of generic active I/O shutdown logic.
This is intended to be a 'opt-in' feature for fabric modules that
includes the following functions to provide a mechinism for fabric
modules to track se_cmd via se_session->sess_cmd_list:
*) target_get_sess_cmd() - Add se_cmd to sess->sess_cmd_list, called
from fabric module incoming I/O path.
*) target_put_sess_cmd() - Check for completion or drop se_cmd from
->sess_cmd_list
*) target_splice_sess_cmd_list() - Splice active I/O list from
->sess_cmd_list to ->sess_wait_list, can called with HW fabric
lock held.
*) target_wait_for_sess_cmds() - Walk ->sess_wait_list waiting on
individual ->cmd_wait_comp. Optional transport_wait_for_tasks()
call.
target_splice_sess_cmd_list() is allowed to be called under HW fabric
lock, and performs the splice into se_sess->sess_wait_list and set
se_cmd->cmd_wait_set. Then target_wait_for_sess_cmds() walks the list
waiting for individual target_put_sess_cmd() fabric callbacks to
complete.
It also adds TFO->check_release_cmd() to split the completion and memory
release calls, where a fabric module uses target_put_sess_cmd() to check
for I/O completion during session shutdown. This is currently pushed out
into fabric modules as current fabric code may sleep here waiting for
TFO->check_stop_free() to complete in main response path, and because
target_wait_for_sess_cmds() calling TFO->release_cmd() to free fabric
descriptor memory directly.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 81bc355..e84b26f 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -268,6 +268,9 @@
}
INIT_LIST_HEAD(&se_sess->sess_list);
INIT_LIST_HEAD(&se_sess->sess_acl_list);
+ INIT_LIST_HEAD(&se_sess->sess_cmd_list);
+ INIT_LIST_HEAD(&se_sess->sess_wait_list);
+ spin_lock_init(&se_sess->sess_cmd_lock);
return se_sess;
}
@@ -1505,11 +1508,12 @@
INIT_LIST_HEAD(&cmd->se_ordered_node);
INIT_LIST_HEAD(&cmd->se_qf_node);
INIT_LIST_HEAD(&cmd->se_queue_node);
-
+ INIT_LIST_HEAD(&cmd->se_cmd_list);
INIT_LIST_HEAD(&cmd->t_task_list);
init_completion(&cmd->transport_lun_fe_stop_comp);
init_completion(&cmd->transport_lun_stop_comp);
init_completion(&cmd->t_transport_stop_comp);
+ init_completion(&cmd->cmd_wait_comp);
spin_lock_init(&cmd->t_state_lock);
atomic_set(&cmd->transport_dev_active, 1);
@@ -3950,6 +3954,14 @@
core_tmr_release_req(cmd->se_tmr_req);
if (cmd->t_task_cdb != cmd->__t_task_cdb)
kfree(cmd->t_task_cdb);
+ /*
+ * Check if target_wait_for_sess_cmds() is expecting to
+ * release se_cmd directly here..
+ */
+ if (cmd->check_release != 0 && cmd->se_tfo->check_release_cmd)
+ if (cmd->se_tfo->check_release_cmd(cmd) != 0)
+ return;
+
cmd->se_tfo->release_cmd(cmd);
}
EXPORT_SYMBOL(transport_release_cmd);
@@ -3977,6 +3989,114 @@
}
EXPORT_SYMBOL(transport_generic_free_cmd);
+/* target_get_sess_cmd - Add command to active ->sess_cmd_list
+ * @se_sess: session to reference
+ * @se_cmd: command descriptor to add
+ */
+void target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
+ list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);
+ se_cmd->check_release = 1;
+ spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+}
+EXPORT_SYMBOL(target_get_sess_cmd);
+
+/* target_put_sess_cmd - Check for active I/O shutdown or list delete
+ * @se_sess: session to reference
+ * @se_cmd: command descriptor to drop
+ */
+int target_put_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
+ if (list_empty(&se_cmd->se_cmd_list)) {
+ spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+ WARN_ON(1);
+ return 0;
+ }
+
+ if (se_sess->sess_tearing_down && se_cmd->cmd_wait_set) {
+ spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+ complete(&se_cmd->cmd_wait_comp);
+ return 1;
+ }
+ list_del(&se_cmd->se_cmd_list);
+ spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL(target_put_sess_cmd);
+
+/* target_splice_sess_cmd_list - Split active cmds into sess_wait_list
+ * @se_sess: session to split
+ */
+void target_splice_sess_cmd_list(struct se_session *se_sess)
+{
+ struct se_cmd *se_cmd;
+ unsigned long flags;
+
+ WARN_ON(!list_empty(&se_sess->sess_wait_list));
+ INIT_LIST_HEAD(&se_sess->sess_wait_list);
+
+ spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
+ se_sess->sess_tearing_down = 1;
+
+ list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list);
+
+ list_for_each_entry(se_cmd, &se_sess->sess_wait_list, se_cmd_list)
+ se_cmd->cmd_wait_set = 1;
+
+ spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+}
+EXPORT_SYMBOL(target_splice_sess_cmd_list);
+
+/* target_wait_for_sess_cmds - Wait for outstanding descriptors
+ * @se_sess: session to wait for active I/O
+ * @wait_for_tasks: Make extra transport_wait_for_tasks call
+ */
+void target_wait_for_sess_cmds(
+ struct se_session *se_sess,
+ int wait_for_tasks)
+{
+ struct se_cmd *se_cmd, *tmp_cmd;
+ bool rc = false;
+
+ list_for_each_entry_safe(se_cmd, tmp_cmd,
+ &se_sess->sess_wait_list, se_cmd_list) {
+ list_del(&se_cmd->se_cmd_list);
+
+ pr_debug("Waiting for se_cmd: %p t_state: %d, fabric state:"
+ " %d\n", se_cmd, se_cmd->t_state,
+ se_cmd->se_tfo->get_cmd_state(se_cmd));
+
+ if (wait_for_tasks) {
+ pr_debug("Calling transport_wait_for_tasks se_cmd: %p t_state: %d,"
+ " fabric state: %d\n", se_cmd, se_cmd->t_state,
+ se_cmd->se_tfo->get_cmd_state(se_cmd));
+
+ rc = transport_wait_for_tasks(se_cmd);
+
+ pr_debug("After transport_wait_for_tasks se_cmd: %p t_state: %d,"
+ " fabric state: %d\n", se_cmd, se_cmd->t_state,
+ se_cmd->se_tfo->get_cmd_state(se_cmd));
+ }
+
+ if (!rc) {
+ wait_for_completion(&se_cmd->cmd_wait_comp);
+ pr_debug("After cmd_wait_comp: se_cmd: %p t_state: %d"
+ " fabric state: %d\n", se_cmd, se_cmd->t_state,
+ se_cmd->se_tfo->get_cmd_state(se_cmd));
+ }
+
+ se_cmd->se_tfo->release_cmd(se_cmd);
+ }
+}
+EXPORT_SYMBOL(target_wait_for_sess_cmds);
+
/* transport_lun_wait_for_tasks():
*
* Called from ConfigFS context to stop the passed struct se_cmd to allow
@@ -4153,14 +4273,14 @@
* Called from frontend fabric context to wait for storage engine
* to pause and/or release frontend generated struct se_cmd.
*/
-void transport_wait_for_tasks(struct se_cmd *cmd)
+bool transport_wait_for_tasks(struct se_cmd *cmd)
{
unsigned long flags;
spin_lock_irqsave(&cmd->t_state_lock, flags);
if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD) && !(cmd->se_tmr_req)) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- return;
+ return false;
}
/*
* Only perform a possible wait_for_tasks if SCF_SUPPORTED_SAM_OPCODE
@@ -4168,7 +4288,7 @@
*/
if (!(cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE) && !cmd->se_tmr_req) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- return;
+ return false;
}
/*
* If we are already stopped due to an external event (ie: LUN shutdown)
@@ -4211,7 +4331,7 @@
if (!atomic_read(&cmd->t_transport_active) ||
atomic_read(&cmd->t_transport_aborted)) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- return;
+ return false;
}
atomic_set(&cmd->t_transport_stop, 1);
@@ -4236,6 +4356,8 @@
cmd->se_tfo->get_task_tag(cmd));
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
+ return true;
}
EXPORT_SYMBOL(transport_wait_for_tasks);
