#!/usr/bin/python
#
# Copyright (C) Citrix Systems Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation; version 2.1 only.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#
# A plugin for enabling trim on LVM based SRs to free up storage space
# in Storage arrays.
import xml
import os
import time
import util
import lock
import lvhdutil
import vhdutil
import lvutil
TRIM_LV_TAG = "_trim_lv"
TRIM_CAP = "SR_TRIM"
LOCK_RETRY_ATTEMPTS = 3
LOCK_RETRY_INTERVAL = 1
ERROR_CODE_KEY = "errcode"
ERROR_MSG_KEY = "errmsg"
TRIM_LAST_TRIGGERED_KEY = "trim_last_triggered"
MASTER_LVM_CONF = '/etc/lvm/master'
def _vg_by_sr_uuid(sr_uuid):
return lvhdutil.VG_PREFIX + sr_uuid
def _lvpath_by_vg_lv_name(vg_name, lv_name):
return os.path.join(lvhdutil.VG_LOCATION, vg_name, lv_name)
def to_xml(d):
dom = xml.dom.minidom.Document()
trim_response = dom.createElement("trim_response")
dom.appendChild(trim_response)
for key, value in sorted(d.items()):
key_value_element = dom.createElement("key_value_pair")
trim_response.appendChild(key_value_element)
key_element = dom.createElement("key")
key_text_node = dom.createTextNode(key)
key_element.appendChild(key_text_node)
key_value_element.appendChild(key_element)
value_element = dom.createElement("value")
value_text_mode = dom.createTextNode(value)
value_element.appendChild(value_text_mode)
key_value_element.appendChild(value_element)
return dom.toxml()
# Note: This function is expected to be called from a context where
# the SR is locked by the thread calling the function; therefore removing
# any risk of a race condition updating the LAST_TRIGGERED value.
def _log_last_triggered(session, sr_uuid):
try:
sr_ref = session.xenapi.SR.get_by_uuid(sr_uuid)
other_config = session.xenapi.SR.get_other_config(sr_ref)
if other_config.has_key(TRIM_LAST_TRIGGERED_KEY):
session.xenapi.SR.remove_from_other_config(sr_ref, TRIM_LAST_TRIGGERED_KEY)
session.xenapi.SR.add_to_other_config(sr_ref, TRIM_LAST_TRIGGERED_KEY, str(time.time()))
except:
util.logException("Unable to set other-config:%s" % TRIM_LAST_TRIGGERED_KEY)
def do_trim(session, args):
"""Attempt to trim the given LVHDSR"""
util.SMlog("do_trim: %s" % args)
sr_uuid = args["sr_uuid"]
os.environ['LVM_SYSTEM_DIR'] = MASTER_LVM_CONF
if TRIM_CAP not in util.sr_get_capability(sr_uuid):
util.SMlog("Trim command ignored on unsupported SR %s" % sr_uuid)
err_msg = {ERROR_CODE_KEY: 'UnsupportedSRForTrim',
ERROR_MSG_KEY: 'Trim on [%s] not supported' % sr_uuid}
return to_xml(err_msg)
# Lock SR, get vg empty space details
sr_lock = lock.Lock(vhdutil.LOCK_TYPE_SR, sr_uuid)
got_lock = False
for i in range(LOCK_RETRY_ATTEMPTS):
got_lock = sr_lock.acquireNoblock()
if got_lock:
break
time.sleep(LOCK_RETRY_INTERVAL)
if got_lock:
try:
vg_name = _vg_by_sr_uuid(sr_uuid)
lv_name = sr_uuid + TRIM_LV_TAG
lv_path = _lvpath_by_vg_lv_name(vg_name, lv_name)
# Clean trim LV in case the previous trim attemp failed
if lvutil.exists(lv_path):
lvutil.remove(lv_path)
#Check if VG limits are enough for creating LV.
stats = lvutil._getVGstats(vg_name)
if (stats['freespace'] < lvutil.LVM_SIZE_INCREMENT):
util.SMlog("No space to claim on a full SR %s" % sr_uuid)
err_msg = {ERROR_CODE_KEY: 'Trim failed on full SR',
ERROR_MSG_KEY: 'No space to claim on a full SR'}
result = to_xml(err_msg)
else:
# Perform a lvcreate, blkdiscard and lvremove to
# trigger trim on the array
lvutil.create(lv_name, 0, vg_name, size_in_percentage="100%F")
cmd = ["/usr/sbin/blkdiscard", "-v", lv_path]
stdout = util.pread2(cmd)
util.SMlog("Stdout is %s" % stdout)
util.SMlog("Trim on SR: %s complete. " % sr_uuid)
result = str(True)
except util.CommandException, e:
err_msg = {
ERROR_CODE_KEY: 'TrimException',
ERROR_MSG_KEY: e.reason
}
result = to_xml(err_msg)
except:
err_msg = {
ERROR_CODE_KEY: 'UnknownTrimException',
ERROR_MSG_KEY: 'Unknown Exception: trim failed on SR [%s]'
% sr_uuid
}
result = to_xml(err_msg)
finally:
if lvutil.exists(lv_path):
lvutil.remove(lv_path)
_log_last_triggered(session, sr_uuid)
sr_lock.release()
return result
else:
util.SMlog("Could not complete Trim on %s, Lock unavailable !" \
% sr_uuid)
err_msg = {ERROR_CODE_KEY: 'SRUnavailable',
ERROR_MSG_KEY: 'Unable to get SR lock [%s]' % sr_uuid}
return to_xml(err_msg)
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