job_container/tmpfs - Cleanup any mounts in BasePath.

Sharing the root filesystem for autofs also permits previously launched
job containers to appear in new jobs. This is not desired, so clean
them out of the container.

Bug 12567

src/plugins/job_container/tmpfs/job_container_tmpfs.c

@@ -396,6 +396,41 @@ static int _rm_data(const char *path, const struct stat *st_buf,
 	return rc;
 }
 
+static int _clean_job_basepath(uint32_t job_id)
+{
+	DIR *dp;
+	struct dirent *ep;
+	char path[PATH_MAX];
+	int rc;
+
+	if (!(dp = opendir(jc_conf->basepath))) {
+		error("%s: Unable to open %s", __func__, jc_conf->basepath);
+		return SLURM_ERROR;
+	}
+
+	while ((ep = readdir(dp))) {
+		if (!xstrcmp(ep->d_name, ".") || !xstrcmp(ep->d_name, ".."))
+			continue;
+		/* If possible, only attempt with directories */
+		if ((ep->d_type == DT_DIR) || (ep->d_type == DT_UNKNOWN)) {
+			rc = snprintf(path, PATH_MAX, "%s/%s",
+				      jc_conf->basepath, ep->d_name);
+			if (rc >= PATH_MAX) {
+				error("%s: Unable to build path: %m",
+				      __func__);
+				continue;
+			}
+			/* it is not important if this fails */
+			if (umount2(path, MNT_DETACH))
+				debug2("failed to unmount %s for job %u",
+				       path, job_id);
+		}
+	}
+	closedir(dp);
+
+	return SLURM_SUCCESS;
+}
+
 static int _create_ns(uint32_t job_id, stepd_step_rec_t *step)
 {
 	char job_mount[PATH_MAX];
@@ -618,9 +653,9 @@ static int _create_ns(uint32_t job_id, stepd_step_rec_t *step)
 		 * mounts inside the job, they will only see their job mount
 		 * but not the basepath mount.
 		 */
-		rc = umount2(job_mount, MNT_DETACH);
+		rc = _clean_job_basepath(job_id);
 		if (rc) {
-			error("%s: umount2 failed: %m", __func__);
+			error("%s: failed to clean job mounts: %m", __func__);
 			goto child_exit;
 		}
 	child_exit: