[PATCH rfc 3/6] nvme-cli: allow discover to address discovery controller by persistent name

[jsmart2021@gmail.com (James Smart)]

To support discovery (connect/connect-all) to operate against a
persistent discovery controller, let the discovery controller to
be specified by its device node name rather than new connection
attributes.

Example:
  nvme connect-all ... --device=nvme5

Also centralize extraction of controller instance from the controller
name to a common helper.

Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
Signed-off-by: James Smart <jsmart2021 at gmail.com>
Reviewed-by: Max Gurtovoy <maxg at mellanox.com>

---
Patch originated from Sagi in an RFC
fix merge issue
fix contoller->controller
add cfg.device check for "none"
---
 fabrics.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/fabrics.c b/fabrics.c
index c4bbe2c..1c5ca9a 100644
--- a/fabrics.c
+++ b/fabrics.c
@@ -189,6 +189,19 @@ static const char *cms_str(__u8 cm)
 
 static int do_discover(char *argstr, bool connect);
 
+static int ctrl_instance(char *device)
+{
+	int ret, instance;
+
+	device = basename(device);
+	ret = sscanf(device, "nvme%d", &instance);
+	if (ret < 0)
+		return ret;
+	if (!ret)
+		return -1;
+	return instance;
+}
+
 static int add_ctrl(const char *argstr)
 {
 	substring_t args[MAX_OPT_ARGS];
@@ -851,7 +864,10 @@ static int do_discover(char *argstr, bool connect)
 	char *dev_name;
 	int instance, numrec = 0, ret, err;
 
-	instance = add_ctrl(argstr);
+	if (!cfg.device)
+		instance = add_ctrl(argstr);
+	else
+		instance = ctrl_instance(cfg.device);
 	if (instance < 0)
 		return instance;
 
@@ -859,7 +875,7 @@ static int do_discover(char *argstr, bool connect)
 		return -errno;
 	ret = nvmf_get_log_page_discovery(dev_name, &log, &numrec);
 	free(dev_name);
-	if (!cfg.persistent) {
+	if (!cfg.device && !cfg.persistent) {
 		err = remove_ctrl(instance);
 		if (err)
 			return err;
@@ -975,6 +991,7 @@ int discover(const char *desc, int argc, char **argv, bool connect)
 		{"hostnqn",     'q', "LIST", CFG_STRING, &cfg.hostnqn,     required_argument, "user-defined hostnqn (if default not used)" },
 		{"hostid",      'I', "LIST", CFG_STRING, &cfg.hostid,      required_argument, "user-defined hostid (if default not used)"},
 		{"raw",         'r', "LIST", CFG_STRING, &cfg.raw,         required_argument, "raw output file" },
+		{"device",      'd', "LIST", CFG_STRING, &cfg.device, required_argument, "use existing discovery controller device" },
 		{"keep-alive-tmo",  'k', "LIST", CFG_INT, &cfg.keep_alive_tmo,  required_argument, "keep alive timeout period in seconds" },
 		{"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" },
@@ -993,6 +1010,9 @@ int discover(const char *desc, int argc, char **argv, bool connect)
 	if (ret)
 		return ret;
 
+	if (cfg.device && !strcmp(cfg.device, "none"))
+		cfg.device = NULL;
+
 	cfg.nqn = NVME_DISC_SUBSYS_NAME;
 
 	if (!cfg.transport && !cfg.traddr) {
@@ -1130,15 +1150,10 @@ static int disconnect_by_nqn(char *nqn)
 static int disconnect_by_device(char *device)
 {
 	int instance;
-	int ret;
-
-	device = basename(device);
-	ret = sscanf(device, "nvme%d", &instance);
-	if (ret < 0)
-		return ret;
-	if (!ret)
-		return -1;
 
+	instance = ctrl_instance(device);
+	if (instance < 0)
+		return instance;
 	return remove_ctrl(instance);
 }
 
-- 
2.13.7