nvmet: add transport discovery change op

Some transports, such as FC-NVME, support discovery controller change
events without the use of a persistent discovery controller. FC receives
events via RSCN from the FC Fabric Controller or subsystem FC port.

This patch adds a nvmet transport op that is called whenever a
discovery change event occurs in the nvmet layer.

To facilitate the callback without adding another layer to cross into
core.c to reference the transport ops, the port structure snapshots
the transport ops when the port is enabled and clears them when disabled.

Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 7734a6acff85..43e8c4adc1f4 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -311,6 +311,7 @@ int nvmet_enable_port(struct nvmet_port *port)
 		port->inline_data_size = 0;
 
 	port->enabled = true;
+	port->tr_ops = ops;
 	return 0;
 }
 
@@ -321,6 +322,7 @@ void nvmet_disable_port(struct nvmet_port *port)
 	lockdep_assert_held(&nvmet_config_sem);
 
 	port->enabled = false;
+	port->tr_ops = NULL;
 
 	ops = nvmet_transports[port->disc_addr.trtype];
 	ops->remove_port(port);