Add nvme_fabrics module loading function

Introduce a new function to check and load the nvme_fabrics
module when performing a connect/discover command, if it is not
already loaded.

It uses the libkmod library.

Signed-off-by: Maurizio Lombardi <[email protected]>

Author: maurizio-lombardi

README.md

@@ -54,6 +54,7 @@ built as part of nvme-cli.
 |---------|------------|-------|
 | libnvme, libnvme-mi | integrated | No external dependency, included in nvme-cli |
 | json-c | optional | Recommended; without it, all plugins are disabled and json-c output format is disabled |
+| libkmod | optional | Without it, nvme-cli won't be able to load the nvme-fabrics module when needed |
 
 ### Optional feature dependencies
 

fabrics.c

@@ -38,6 +38,10 @@
 
 #include <libnvme.h>
 
+#ifdef HAVE_LIBKMOD
+#include <libkmod.h>
+#endif
+
 #include "common.h"
 #include "nvme.h"
 #include "nvme-print.h"
@@ -469,6 +473,50 @@ static int nvme_read_config_checked(struct libnvme_global_ctx *ctx,
 	return libnvme_read_config(ctx, filename);
 }
 
+static void load_nvme_fabrics_module(void)
+{
+#ifdef HAVE_LIBKMOD
+	struct kmod_ctx *ctx;
+	struct kmod_module *mod;
+	int err, state;
+	int timeout = 20; /* 2 seconds */
+
+	ctx = kmod_new(NULL, NULL);
+	if (!ctx)
+		return;
+
+	err = kmod_module_new_from_name(ctx, "nvme-fabrics", &mod);
+	if (err)
+		goto unref;
+
+	state = kmod_module_get_initstate(mod);
+	if (state != KMOD_MODULE_LIVE && state != KMOD_MODULE_BUILTIN) {
+		err = kmod_module_probe_insert_module(mod,
+			KMOD_PROBE_APPLY_BLACKLIST, NULL, NULL, NULL, NULL);
+		if (err)
+			goto mod_unref;
+
+		while (timeout--) {
+			state = kmod_module_get_initstate(mod);
+			if (state == KMOD_MODULE_LIVE)
+				goto mod_unref;
+
+			/* 100 ms */
+			usleep(100 * 1000);
+		}
+		err = -ENOENT;
+	}
+
+mod_unref:
+	kmod_module_unref(mod);
+unref:
+	kmod_unref(ctx);
+
+	if (err)
+		fprintf(stderr, "Couldn't load the nvme-fabrics module\n");
+#endif
+}
+
 #define NBFT_SYSFS_PATH		"/sys/firmware/acpi/tables"
 
 int fabrics_discovery(const char *desc, int argc, char **argv, bool connect)
@@ -502,6 +550,8 @@ int fabrics_discovery(const char *desc, int argc, char **argv, bool connect)
 
 	libnvmf_default_config(&cfg);
 
+	load_nvme_fabrics_module();
+
 	ret = argconfig_parse(argc, argv, desc, opts);
 	if (ret)
 		return ret;
@@ -603,6 +653,8 @@ int fabrics_connect(const char *desc, int argc, char **argv)
 
 	libnvmf_default_config(&cfg);
 
+	load_nvme_fabrics_module();
+
 	ret = argconfig_parse(argc, argv, desc, opts);
 	if (ret)
 		return ret;

meson.build

@@ -55,6 +55,7 @@ want_libnvme = get_option('libnvme').disabled() == false
 want_fabrics = get_option('fabrics').disabled() == false and host_system != 'windows'
 want_mi = get_option('mi').disabled() == false and host_system != 'windows'
 want_json_c = get_option('json-c').disabled() == false and host_system != 'windows'
+want_libkmod = get_option('libkmod').disabled() == false and host_system != 'windows'
 want_tests = get_option('tests') and host_system != 'windows'
 want_examples = get_option('examples') and host_system != 'windows'
 want_docs = get_option('docs')
@@ -302,6 +303,13 @@ else
 endif
 conf.set('CONFIG_LIBURING', liburing_dep.found(), description: 'Is liburing available?')
 
+if not want_libkmod
+    libkmod_dep = dependency('', required: false)
+else
+    libkmod_dep = dependency('libkmod', required: get_option('libkmod'))
+endif
+conf.set('HAVE_LIBKMOD', libkmod_dep.found(), description: 'Is libkmod available?')
+
 if not want_fabrics or get_option('openssl').disabled()
     openssl_dep = dependency('', required: false)
 else
@@ -526,6 +534,7 @@ if want_nvme
         ccan_dep,
         libnvme_dep,
         json_c_dep,
+        libkmod_dep,
     ]
 
     if host_system == 'windows'
@@ -680,6 +689,7 @@ dep_dict = {
     'libdbus':          libdbus_dep.found(),
     'python3':          py3_dep.found(),
     'liburing':         liburing_dep.found(),
+    'libkmod':          libkmod_dep.found(),
 }
 if host_system == 'windows'
     dep_dict += {

meson_options.txt

@@ -65,6 +65,12 @@ option(
   value: 'auto',
   description: 'JSON suppport'
 )
+option(
+  'libkmod',
+  type: 'feature',
+  value: 'auto',
+  description: 'libkmod support'
+)
 option(
   'nvme-tests',
   type : 'boolean',