btrfs.js

'use strict';

var Promise = require('bluebird');
var _ = require('lodash');
var fs = require('fs-extra');

var sbutil = require('./util');

// btrfs

function btrfs() {
  return sbutil.execFilePromise('btrfs', _.toArray(arguments));
}

function isBtrfs(path) {
  return btrfs('filesystem', 'label', path)
    .catch(sbutil.rethrow('\'%s\' does not appear to be a btrfs filesystem', path))
    .return();
}

function enableQuota(path) {
  return btrfs('quota', 'enable', path)
    .catch(sbutil.rethrow('Failed to enable quota for \'%s\'', path));
}

function setQuota(path, size) {
  return btrfs('qgroup', 'limit', '-e', size, path)
    .catch(sbutil.rethrow('Failed to set quota for \'%s\'', path));
}

function destroyQuota(path) {
  return btrfs('qgroup', 'show', '-F', path)
    .spread(function (stdout) {
      var line = stdout.split('\n')[2];

      if (line) {
        var matches = line.match(/^(\d+\/\d+) /);

        if (matches) {
          return btrfs('qgroup', 'destroy', matches[1], path);
        }
      }

      var err = new Error('Unable to find qgroup id in \'btrfs qgroup show\' output');
      err.stdout = stdout;

      throw err;
    })
    .catch(sbutil.rethrow('Failed to destroy quota for \'%s\'', path));
}

exports.isBtrfs = isBtrfs;
exports.enableQuota = enableQuota;
exports.setQuota = setQuota;
exports.destroyQuota = destroyQuota;

// loop mounts

function mountLoopFile(file, dir) {
  return sbutil.execFilePromise('mount', [
    '-o', 'loop',
    file, dir
  ]);
}

function createLoopMount(file, dir, size) {
  return Promise.using(sbutil.withOpen(file, 'wx'), function (fd) {
      return fs.ftruncateAsync(fd, size);
  }).then(function () {
    return sbutil.execFilePromise('mkfs.btrfs', [file])
      .then(function () {
        return exports.mountLoopFile(file, dir);
      })
      .catch(function (err) {
        return fs.unlinkAsync(file)
          .throw(err);
      });
  });
}

function destroyLoopMount(dir) {
  return sbutil.execFilePromise('umount', [dir])
    .then(function () {
      return fs.removeAsync(dir);
    });
}

exports.mountLoopFile = mountLoopFile;
exports.createLoopMount = createLoopMount;
exports.destroyLoopMount = destroyLoopMount;