fabrics: support fabrics sq flow control disable

If the discovery log entry indicates that the subsystem supports
disabling sq flow control, we ask the host to connect and disable sq
flow control (omit sq_head pointer updates). Also add a connect option
to explicitly ask for disable_sqflow.

If we failed to add_ctrl in connect-all command, we retry without it
to be backward compatible with a driver that cannot accept the new
flag.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

diff --git a/fabrics.c b/fabrics.c
index f2bbd923d95bdf130a5e6c08920591734a560845..99793f8beef87c20f6a196268cc213b7cf495258 100644 (file)
--- a/fabrics.c
+++ b/fabrics.c
@@ -60,6 +60,7 @@ static struct config {
        char *raw;
        char *device;
        int  duplicate_connect;
+       int  disable_sqflow;
 } cfg = { NULL };
 
 #define BUF_SIZE               4096
@@ -129,6 +130,8 @@ static const char * const treqs[] = {
        [NVMF_TREQ_NOT_SPECIFIED]       = "not specified",
        [NVMF_TREQ_REQUIRED]            = "required",
        [NVMF_TREQ_NOT_REQUIRED]        = "not required",
+       [NVMF_TREQ_DISABLE_SQFLOW]      = "not specified, "
+                                         "sq flow control disable supported",
 };
 
 static inline const char *treq_str(__u8 treq)
@@ -595,7 +598,9 @@ static int build_options(char *argstr, int max_len)
            add_int_argument(&argstr, &max_len, "ctrl_loss_tmo",
                                cfg.ctrl_loss_tmo) ||
            add_bool_argument(&argstr, &max_len, "duplicate_connect",
-                               cfg.duplicate_connect))
+                               cfg.duplicate_connect) ||
+           add_bool_argument(&argstr, &max_len, "disable_sqflow",
+                               cfg.disable_sqflow))
                return -EINVAL;
 
        return 0;
@@ -603,9 +608,13 @@ static int build_options(char *argstr, int max_len)
 
 static int connect_ctrl(struct nvmf_disc_rsp_page_entry *e)
 {
-       char argstr[BUF_SIZE], *p = argstr;
-       bool discover = false;
-       int len;
+       char argstr[BUF_SIZE], *p;
+       bool discover, disable_sqflow = true;
+       int len, ret;
+
+retry:
+       p = argstr;
+       discover = false;
 
        switch (e->subtype) {
        case NVME_NQN_DISC:
@@ -677,6 +686,7 @@ static int connect_ctrl(struct nvmf_disc_rsp_page_entry *e)
                len = sprintf(p, ",transport=loop");
                if (len < 0)
                        return -EINVAL;
+               p += len;
                /* we can safely ignore the rest of the entries */
                break;
        case NVMF_TRTYPE_RDMA:
@@ -701,6 +711,7 @@ static int connect_ctrl(struct nvmf_disc_rsp_page_entry *e)
                                      e->trsvcid);
                        if (len < 0)
                                return -EINVAL;
+                       p += len;
                        break;
                default:
                        fprintf(stderr, "skipping unsupported adrfam\n");
@@ -720,6 +731,7 @@ static int connect_ctrl(struct nvmf_disc_rsp_page_entry *e)
                                      e->traddr);
                        if (len < 0)
                                return -EINVAL;
+                       p += len;
                        break;
                default:
                        fprintf(stderr, "skipping unsupported adrfam\n");
@@ -732,10 +744,23 @@ static int connect_ctrl(struct nvmf_disc_rsp_page_entry *e)
                return -EINVAL;
        }
 
+       if (e->treq & NVMF_TREQ_DISABLE_SQFLOW && disable_sqflow) {
+               len = sprintf(p, ",disable_sqflow");
+               if (len < 0)
+                       return -EINVAL;
+               p += len;
+       }
+
        if (discover)
-               return do_discover(argstr, true);
+               ret = do_discover(argstr, true);
        else
-               return add_ctrl(argstr);
+               ret = add_ctrl(argstr);
+       if (ret == -EINVAL && e->treq & NVMF_TREQ_DISABLE_SQFLOW) {
+               /* disable_sqflow param might not be supported, try without it */
+               disable_sqflow = false;
+               goto retry;
+       }
+       return ret;
 }
 
 static int connect_ctrls(struct nvmf_disc_rsp_page_hdr *log, int numrec)
@@ -935,6 +960,7 @@ int connect(const char *desc, int argc, char **argv)
                {"reconnect-delay", 'c', "LIST", CFG_INT, &cfg.reconnect_delay, required_argument, "reconnect timeout period in seconds" },
                {"ctrl-loss-tmo",   'l', "LIST", CFG_INT, &cfg.ctrl_loss_tmo,   required_argument, "controller loss timeout period in seconds" },
                {"duplicate_connect", 'D', "", CFG_NONE, &cfg.duplicate_connect, no_argument, "allow duplicate connections between same transport host and subsystem port" },
+               {"disable_sqflow", 'd', "", CFG_NONE, &cfg.disable_sqflow, no_argument, "disable controller sq flow control (default false)" },
                {NULL},
        };
 

diff --git a/linux/nvme.h b/linux/nvme.h
index 1ad970a4c89a8d3bb6438cec4ab28aff5b07d5b6..a6a44b06626760c86908bd1406ea2a12fdb5692a 100644 (file)
--- a/linux/nvme.h
+++ b/linux/nvme.h
@@ -58,9 +58,10 @@ enum {
 
 /* Transport Requirements codes for Discovery Log Page entry TREQ field */
 enum {
-       NVMF_TREQ_NOT_SPECIFIED = 0,    /* Not specified */
-       NVMF_TREQ_REQUIRED      = 1,    /* Required */
-       NVMF_TREQ_NOT_REQUIRED  = 2,    /* Not Required */
+       NVMF_TREQ_NOT_SPECIFIED = 0,            /* Not specified */
+       NVMF_TREQ_REQUIRED      = 1,            /* Required */
+       NVMF_TREQ_NOT_REQUIRED  = 2,            /* Not Required */
+       NVMF_TREQ_DISABLE_SQFLOW = (1 << 2),    /* SQ flow control disable supported */
 };
 
 /* RDMA QP Service Type codes for Discovery Log Page entry TSAS