fabrics: Allow discover params to come from a conf file

Allow the user to just run "nvme discover" or "nvme connect-all"
in case it finds a default /etc/nvme/nvmf_disc conf file.

We allow multiple discovery addresses by iterating over the
lines of the file and executing a discover (with or without
connect) for each line. We allow newlines and '#' prefixed comments.

The return value is or'ed on all discover attempts.

In order to minimize some parsing code, I just convert the
file line into an (argc, argv) pair and feed it to argconfig_parse()
which dictates that the file lines are identical to what one would
pass nvme discover <params>. I'm open to better ideas.

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

diff --git a/fabrics.c b/fabrics.c
index 1bcd6fc8cf177e089735de24b1130bd8fbbc00c3..6bbe239c1f704e78c97c72b781ad88a50e8be5b6 100644 (file)
--- a/fabrics.c
+++ b/fabrics.c
@@ -56,6 +56,8 @@ struct config {
 
 #define BUF_SIZE               4096
 #define PATH_NVME_FABRICS      "/dev/nvme-fabrics"
+#define PATH_NVMF_DISC         "/etc/nvme/discovery.conf"
+#define MAX_DISC_ARGS          10
 
 enum {
        OPT_INSTANCE,
@@ -578,6 +580,66 @@ static int do_discover(char *argstr, bool connect)
        return ret;
 }
 
+static int discover_from_conf_file(const char *desc, char *argstr,
+               const struct argconfig_commandline_options *opts, bool connect)
+{
+       FILE *f;
+       char line[256], *ptr, *args, **argv;
+       int argc, err, ret = 0;
+
+       f = fopen(PATH_NVMF_DISC, "r");
+       if (f == NULL) {
+               fprintf(stderr, "No discover params given and no %s conf\n", PATH_NVMF_DISC);
+               return -EINVAL;
+       }
+
+       while (fgets(line, sizeof(line), f) != NULL) {
+               if (line[0] == '#' || line[0] == '\n')
+                       continue;
+
+               args = strdup(line);
+               if (!args) {
+                       fprintf(stderr, "failed to strdup args\n");
+                       ret = -ENOMEM;
+                       goto out;
+               }
+
+               argv = calloc(MAX_DISC_ARGS, BUF_SIZE);
+               if (!argv) {
+                       fprintf(stderr, "failed to allocate argv vector\n");
+                       free(args);
+                       ret = -ENOMEM;
+                       goto out;
+               }
+
+               argc = 0;
+               argv[argc++] = "discover";
+               while ((ptr = strsep(&args, " =\n")) != NULL)
+                       argv[argc++] = ptr;
+
+               argconfig_parse(argc, argv, desc, opts, &cfg, sizeof(cfg));
+
+               err = build_options(argstr, BUF_SIZE);
+               if (err) {
+                       ret = err;
+                       continue;
+               }
+
+               err = do_discover(argstr, connect);
+               if (err) {
+                       ret = err;
+                       continue;
+               }
+
+               free(args);
+               free(argv);
+       }
+
+out:
+       fclose(f);
+       return ret;
+}
+
 int discover(const char *desc, int argc, char **argv, bool connect)
 {
        char argstr[BUF_SIZE];
@@ -600,11 +662,16 @@ int discover(const char *desc, int argc, char **argv, bool connect)
 
        cfg.nqn = NVME_DISC_SUBSYS_NAME;
 
-       ret = build_options(argstr, BUF_SIZE);
-       if (ret)
-               return ret;
+       if (!cfg.transport && !cfg.traddr) {
+               return discover_from_conf_file(desc, argstr,
+                               command_line_options, connect);
+       } else {
+               ret = build_options(argstr, BUF_SIZE);
+               if (ret)
+                       return ret;
 
-       return do_discover(argstr, connect);
+               return do_discover(argstr, connect);
+       }
 }
 
 int connect(const char *desc, int argc, char **argv)