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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