nvme: update invalid device handling for list-subsys

The list-subsys command fails to error out if one passes an invalid
or non-existent ns device as part of the <device> option. One would
have ideally expected the nvme_match_device_filter() to catch this,
but such cases would be better handled with a simple stat check for
ns device validity before proceeding to the filter in the first place.
That way, the stat check can take care of ns device validity whereas
the filter can focus on filtering the subsystems and controllers,
ignoring checking for invalid ns devices, as logically expected in a
list subsystems command.

Signed-off-by: Martin George <[email protected]>

Author: martin-gpy

nvme.c

@@ -3460,6 +3460,14 @@ static int list_subsys(int argc, char **argv, struct command *cmd,
 
 	if (devname) {
 		int subsys_num;
+		struct stat st;
+		char path[512];
+
+		sprintf(path, "/dev/%s", devname);
+		if (stat(path, &st) != 0) {
+			nvme_show_error("%s does not exist", path);
+			return -EINVAL;
+		}
 
 		if (sscanf(devname, "nvme%dn%d", &subsys_num, &nsid) != 2) {
 			nvme_show_error("Invalid device name %s", devname);