name : plugin_mounts.py import tuned.consts as consts from . import base from .decorators import * from subprocess import Popen,PIPE import tuned.logs from tuned.utils.commands import commands import glob log = tuned.logs.get() cmd = commands() class MountsPlugin(base.Plugin): """ `mounts`:: Enables or disables barriers for mounts according to the value of the [option]`disable_barriers` option. The [option]`disable_barriers` option has an optional value `force` which disables barriers even on mountpoints with write back caches. Note that only extended file systems (ext) are supported by this plug-in. """ @classmethod def _generate_mountpoint_topology(cls): """ Gets the information about disks, partitions and mountpoints. Stores information about used filesystem and creates a list of all underlying devices (in case of LVM) for each mountpoint. """ mountpoint_topology = {} current_disk = None stdout, stderr = Popen(["lsblk", "-rno", \ "TYPE,RM,KNAME,FSTYPE,MOUNTPOINT"], \ stdout=PIPE, stderr=PIPE, close_fds=True, \ universal_newlines = True).communicate() for columns in [line.split() for line in stdout.splitlines()]: if len(columns) < 3: continue device_type, device_removable, device_name = columns[:3] filesystem = columns[3] if len(columns) > 3 else None mountpoint = columns[4] if len(columns) > 4 else None if device_type == "disk": current_disk = device_name continue # skip removable, skip nonpartitions if device_removable == "1" or device_type not in ["part", "lvm"]: continue if mountpoint is None or mountpoint == "[SWAP]": continue mountpoint_topology.setdefault(mountpoint, {"disks": set(), "device_name": device_name, "filesystem": filesystem}) mountpoint_topology[mountpoint]["disks"].add(current_disk) cls._mountpoint_topology = mountpoint_topology def _init_devices(self): self._generate_mountpoint_topology() self._devices_supported = True self._free_devices = set(self._mountpoint_topology.keys()) self._assigned_devices = set() @classmethod def _get_config_options(self): return { "disable_barriers": None, } def _instance_init(self, instance): instance._has_dynamic_tuning = False instance._has_static_tuning = True def _instance_cleanup(self, instance): pass def _get_device_cache_type(self, device): """ Get device cache type. This will work only for devices on SCSI kernel subsystem. """ source_filenames = glob.glob("/sys/block/%s/device/scsi_disk/*/cache_type" % device) for source_filename in source_filenames: return cmd.read_file(source_filename).strip() return None def _mountpoint_has_writeback_cache(self, mountpoint): """ Checks if the device has 'write back' cache. If the cache type cannot be determined, asume some other cache. """ for device in self._mountpoint_topology[mountpoint]["disks"]: if self._get_device_cache_type(device) == "write back": return True return False def _mountpoint_has_barriers(self, mountpoint): """ Checks if a given mountpoint is mounted with barriers enabled or disabled. """ with open("/proc/mounts") as mounts_file: for line in mounts_file: # device mountpoint filesystem options dump check columns = line.split() if columns[0][0] != "/": continue if columns[1] == mountpoint: option_list = columns[3] break else: return None options = option_list.split(",") for option in options: (name, sep, value) = option.partition("=") # nobarrier barrier=0 if name == "nobarrier" or (name == "barrier" and value == "0"): return False # barrier barrier=1 elif name == "barrier": return True else: # default return True def _remount_partition(self, partition, options): """ Remounts partition. """ remount_command = ["/usr/bin/mount", partition, "-o", "remount,%s" % options] cmd.execute(remount_command) @command_custom("disable_barriers", per_device=True) def _disable_barriers(self, start, value, mountpoint, verify, ignore_missing): storage_key = self._storage_key( command_name = "disable_barriers", device_name = mountpoint) force = str(value).lower() == "force" value = force or self._option_bool(value) if start: if not value: return None reject_reason = None if not self._mountpoint_topology[mountpoint]["filesystem"].startswith("ext"): reject_reason = "filesystem not supported" elif not force and self._mountpoint_has_writeback_cache(mountpoint): reject_reason = "device uses write back cache" else: original_value = self._mountpoint_has_barriers(mountpoint) if original_value is None: reject_reason = "unknown current setting" elif original_value == False: if verify: log.info(consts.STR_VERIFY_PROFILE_OK % mountpoint) return True else: reject_reason = "barriers already disabled" elif verify: log.error(consts.STR_VERIFY_PROFILE_FAIL % mountpoint) return False if reject_reason is not None: log.info("not disabling barriers on '%s' (%s)" % (mountpoint, reject_reason)) return None self._storage.set(storage_key, original_value) log.info("disabling barriers on '%s'" % mountpoint) self._remount_partition(mountpoint, "barrier=0") else: if verify: return None original_value = self._storage.get(storage_key) if original_value is None: return None log.info("enabling barriers on '%s'" % mountpoint) self._remount_partition(mountpoint, "barrier=1") self._storage.unset(storage_key) return None