nvme: disable fabrics SQ flow control when asked by the user

As for now, we don't care about sq_head pointer updates anyway, so
at least allow the controller to micro-optimize by omiting this update.

Note that we will probably need to support it when a controller
that requires this comes along.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index bd0969db6225c5747b3105b7c5e88cffd6b6f2b1..10074ac7731bab85e869c224ade50b94d2702fda 100644 (file)
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -392,6 +392,9 @@ int nvmf_connect_admin_queue(struct nvme_ctrl *ctrl)
        cmd.connect.kato = ctrl->opts->discovery_nqn ? 0 :
                cpu_to_le32((ctrl->kato + NVME_KATO_GRACE) * 1000);
 
+       if (ctrl->opts->disable_sqflow)
+               cmd.connect.cattr |= NVME_CONNECT_DISABLE_SQFLOW;
+
        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;
@@ -451,6 +454,9 @@ int nvmf_connect_io_queue(struct nvme_ctrl *ctrl, u16 qid)
        cmd.connect.qid = cpu_to_le16(qid);
        cmd.connect.sqsize = cpu_to_le16(ctrl->sqsize);
 
+       if (ctrl->opts->disable_sqflow)
+               cmd.connect.cattr |= NVME_CONNECT_DISABLE_SQFLOW;
+
        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;
@@ -607,6 +613,7 @@ static const match_table_t opt_tokens = {
        { NVMF_OPT_HOST_TRADDR,         "host_traddr=%s"        },
        { NVMF_OPT_HOST_ID,             "hostid=%s"             },
        { NVMF_OPT_DUP_CONNECT,         "duplicate_connect"     },
+       { NVMF_OPT_DISABLE_SQFLOW,      "disable_sqflow"        },
        { NVMF_OPT_ERR,                 NULL                    }
 };
 
@@ -817,6 +824,9 @@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
                case NVMF_OPT_DUP_CONNECT:
                        opts->duplicate_connect = true;
                        break;
+               case NVMF_OPT_DISABLE_SQFLOW:
+                       opts->disable_sqflow = true;
+                       break;
                default:
                        pr_warn("unknown parameter or missing value '%s' in ctrl creation request\n",
                                p);
@@ -933,7 +943,8 @@ EXPORT_SYMBOL_GPL(nvmf_free_options);
 #define NVMF_REQUIRED_OPTS     (NVMF_OPT_TRANSPORT | NVMF_OPT_NQN)
 #define NVMF_ALLOWED_OPTS      (NVMF_OPT_QUEUE_SIZE | NVMF_OPT_NR_IO_QUEUES | \
                                 NVMF_OPT_KATO | NVMF_OPT_HOSTNQN | \
-                                NVMF_OPT_HOST_ID | NVMF_OPT_DUP_CONNECT)
+                                NVMF_OPT_HOST_ID | NVMF_OPT_DUP_CONNECT |\
+                                NVMF_OPT_DISABLE_SQFLOW)
 
 static struct nvme_ctrl *
 nvmf_create_ctrl(struct device *dev, const char *buf, size_t count)

diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
index 6ea6275f332a61263715bd1eb878a1d383c7c989..ecd9a006a0914916d80443e82adb2434e1082521 100644 (file)
--- a/drivers/nvme/host/fabrics.h
+++ b/drivers/nvme/host/fabrics.h
@@ -58,6 +58,7 @@ enum {
        NVMF_OPT_CTRL_LOSS_TMO  = 1 << 11,
        NVMF_OPT_HOST_ID        = 1 << 12,
        NVMF_OPT_DUP_CONNECT    = 1 << 13,
+       NVMF_OPT_DISABLE_SQFLOW = 1 << 14,
 };
 
 /**
@@ -101,6 +102,7 @@ struct nvmf_ctrl_options {
        unsigned int            kato;
        struct nvmf_host        *host;
        int                     max_reconnects;
+       bool                    disable_sqflow;
 };
 
 /*