volumes: wait for mount during add/update

this is a better feedback mechanism for the user

src/mounts.js

@@ -4,7 +4,8 @@ exports = module.exports = {
     writeMountFile,
     removeMountFile,
     validateMountOptions,
-    getStatus
+    getStatus,
+    waitForMount
 };
 
 const assert = require('assert'),
@@ -16,6 +17,7 @@ const assert = require('assert'),
     paths = require('./paths.js'),
     safe = require('safetydance'),
     shell = require('./shell.js');
+const promiseRetry = require('./promise-retry.js');
 
 const ADD_MOUNT_CMD = path.join(__dirname, 'scripts/addmount.sh');
 const RM_MOUNT_CMD = path.join(__dirname, 'scripts/rmmount.sh');
@@ -79,7 +81,7 @@ async function writeMountFile(volume) {
         what = mountOptions.diskPath; // like /dev/disk/by-uuid/uuid or /dev/disk/by-id/scsi-id
         options = 'discard,defaults,noatime';
         break;
-    case 'sshfs':
+    case 'sshfs': {
         const keyFilePath = path.join(paths.SSHFS_KEYS_DIR, `id_rsa_${mountOptions.host}`);
 
         safe.fs.mkdirSync(paths.SSHFS_KEYS_DIR);
@@ -90,6 +92,10 @@ async function writeMountFile(volume) {
         options = `defaults,allow_other,port=${mountOptions.port},IdentityFile=${keyFilePath},reconnect,uid=yellowtent,gid=yellowtent`;
         break;
     }
+    case 'noop': // volume provider
+    case 'mountpoint': // backup provider
+        return;
+    }
 
     const mountFileContents = ejs.render(SYSTEMD_MOUNT_EJS, { name, what, where: hostPath, options, type });
     await shell.promises.sudo('generateMountFile', [ ADD_MOUNT_CMD, mountFileContents ], {});
@@ -116,7 +122,7 @@ async function getStatus(mountType, hostPath) {
     }
 
     let output = safe.child_process.execSync(`systemctl show --value -p ActiveState $(systemd-escape -p --suffix=mount ${hostPath})`, { encoding: 'utf8' });
-    let state = output ? output.trim() : '';
+    const state = output ? output.trim() : '';
     let message;
 
     if (state !== 'active') { // find why it failed
@@ -134,3 +140,17 @@ async function getStatus(mountType, hostPath) {
 
     return { state, message };
 }
+
+async function waitForMount(mountType, hostPath, options) {
+    assert.strictEqual(typeof mountType, 'string');
+    assert.strictEqual(typeof hostPath, 'string');
+    assert.strictEqual(typeof options, 'object');
+
+    if (mountType === 'noop' || mountType === 'mountpoint') return;  // noop is from volume provider and mountpoint is from backup provider
+
+    await promiseRetry(options, async function () {
+        const status = await getStatus(mountType, hostPath);
+        if (status.state === 'active') return true;
+        throw new BoxError(BoxError.MOUNT_ERROR, `Mount is not active (${status.state}): ${status.message}`);
+    });
+}