From: Christoph Hellwig <hch@lst.de>
Date: Wed, 3 Mar 2021 13:28:22 +0100
Subject: nvme-fabrics: only reserve a single tag
Patch-mainline: v5.12-rc4
Git-commit: ed01fee283a067c72b2d6500046080dbc1bb9dae
References: bsc#1182077

Fabrics drivers currently reserve two tags on the admin queue.  But
given that the connect command is only run on a freshly created queue
or after all commands have been force aborted we only need to reserve
a single tag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/nvme/host/fabrics.h |    7 +++++++
 drivers/nvme/host/fc.c      |    4 ++--
 drivers/nvme/host/rdma.c    |    4 ++--
 drivers/nvme/host/tcp.c     |    4 ++--
 drivers/nvme/target/loop.c  |    4 ++--
 5 files changed, 15 insertions(+), 8 deletions(-)

--- a/drivers/nvme/host/fabrics.h
+++ b/drivers/nvme/host/fabrics.h
@@ -19,6 +19,13 @@
 #define NVMF_DEF_FAIL_FAST_TMO		-1
 
 /*
+ * Reserved one command for internal usage.  This command is used for sending
+ * the connect command, as well as for the keep alive command on the admin
+ * queue once live.
+ */
+#define NVMF_RESERVED_TAGS     1
+
+/*
  * Define a host as seen by the target.  We allocate one at boot, but also
  * allow the override it when creating controllers.  This is both to provide
  * persistence of the Host NQN over multiple boots, and to allow using
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -2852,7 +2852,7 @@ nvme_fc_create_io_queues(struct nvme_fc_
 	memset(&ctrl->tag_set, 0, sizeof(ctrl->tag_set));
 	ctrl->tag_set.ops = &nvme_fc_mq_ops;
 	ctrl->tag_set.queue_depth = ctrl->ctrl.opts->queue_size;
-	ctrl->tag_set.reserved_tags = 1; /* fabric connect */
+	ctrl->tag_set.reserved_tags = NVMF_RESERVED_TAGS;
 	ctrl->tag_set.numa_node = ctrl->ctrl.numa_node;
 	ctrl->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 	ctrl->tag_set.cmd_size =
@@ -3472,7 +3472,7 @@ nvme_fc_init_ctrl(struct device *dev, st
 	memset(&ctrl->admin_tag_set, 0, sizeof(ctrl->admin_tag_set));
 	ctrl->admin_tag_set.ops = &nvme_fc_admin_mq_ops;
 	ctrl->admin_tag_set.queue_depth = NVME_AQ_MQ_TAG_DEPTH;
-	ctrl->admin_tag_set.reserved_tags = 2; /* fabric connect + Keep-Alive */
+	ctrl->admin_tag_set.reserved_tags = NVMF_RESERVED_TAGS;
 	ctrl->admin_tag_set.numa_node = ctrl->ctrl.numa_node;
 	ctrl->admin_tag_set.cmd_size =
 		struct_size((struct nvme_fcp_op_w_sgl *)NULL, priv,
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -806,7 +806,7 @@ static struct blk_mq_tag_set *nvme_rdma_
 		memset(set, 0, sizeof(*set));
 		set->ops = &nvme_rdma_admin_mq_ops;
 		set->queue_depth = NVME_AQ_MQ_TAG_DEPTH;
-		set->reserved_tags = 2; /* connect + keep-alive */
+		set->reserved_tags = NVMF_RESERVED_TAGS;
 		set->numa_node = nctrl->numa_node;
 		set->cmd_size = sizeof(struct nvme_rdma_request) +
 				NVME_RDMA_DATA_SGL_SIZE;
@@ -819,7 +819,7 @@ static struct blk_mq_tag_set *nvme_rdma_
 		memset(set, 0, sizeof(*set));
 		set->ops = &nvme_rdma_mq_ops;
 		set->queue_depth = nctrl->sqsize + 1;
-		set->reserved_tags = 1; /* fabric connect */
+		set->reserved_tags = NVMF_RESERVED_TAGS;
 		set->numa_node = nctrl->numa_node;
 		set->flags = BLK_MQ_F_SHOULD_MERGE;
 		set->cmd_size = sizeof(struct nvme_rdma_request) +
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1577,7 +1577,7 @@ static struct blk_mq_tag_set *nvme_tcp_a
 		memset(set, 0, sizeof(*set));
 		set->ops = &nvme_tcp_admin_mq_ops;
 		set->queue_depth = NVME_AQ_MQ_TAG_DEPTH;
-		set->reserved_tags = 2; /* connect + keep-alive */
+		set->reserved_tags = NVMF_RESERVED_TAGS;
 		set->numa_node = nctrl->numa_node;
 		set->flags = BLK_MQ_F_BLOCKING;
 		set->cmd_size = sizeof(struct nvme_tcp_request);
@@ -1589,7 +1589,7 @@ static struct blk_mq_tag_set *nvme_tcp_a
 		memset(set, 0, sizeof(*set));
 		set->ops = &nvme_tcp_mq_ops;
 		set->queue_depth = nctrl->sqsize + 1;
-		set->reserved_tags = 1; /* fabric connect */
+		set->reserved_tags = NVMF_RESERVED_TAGS;
 		set->numa_node = nctrl->numa_node;
 		set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING;
 		set->cmd_size = sizeof(struct nvme_tcp_request);
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -339,7 +339,7 @@ static int nvme_loop_configure_admin_que
 	memset(&ctrl->admin_tag_set, 0, sizeof(ctrl->admin_tag_set));
 	ctrl->admin_tag_set.ops = &nvme_loop_admin_mq_ops;
 	ctrl->admin_tag_set.queue_depth = NVME_AQ_MQ_TAG_DEPTH;
-	ctrl->admin_tag_set.reserved_tags = 2; /* connect + keep-alive */
+	ctrl->admin_tag_set.reserved_tags = NVMF_RESERVED_TAGS;
 	ctrl->admin_tag_set.numa_node = ctrl->ctrl.numa_node;
 	ctrl->admin_tag_set.cmd_size = sizeof(struct nvme_loop_iod) +
 		NVME_INLINE_SG_CNT * sizeof(struct scatterlist);
@@ -510,7 +510,7 @@ static int nvme_loop_create_io_queues(st
 	memset(&ctrl->tag_set, 0, sizeof(ctrl->tag_set));
 	ctrl->tag_set.ops = &nvme_loop_mq_ops;
 	ctrl->tag_set.queue_depth = ctrl->ctrl.opts->queue_size;
-	ctrl->tag_set.reserved_tags = 1; /* fabric connect */
+	ctrl->tag_set.reserved_tags = NVMF_RESERVED_TAGS;
 	ctrl->tag_set.numa_node = ctrl->ctrl.numa_node;
 	ctrl->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 	ctrl->tag_set.cmd_size = sizeof(struct nvme_loop_iod) +