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dmmp.py
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dmmp.py
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"""
Python API for multipath-tools
"""
# Copyright (C) 2016-2018 Red Hat, Inc.
# This library 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; either
# version 3 of the License, or (at your option) any later version.
#
# This library 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 library; If not, see <http://www.gnu.org/licenses/>.
#
# Author: Gris Ge <fge@redhat.com>
# Nir Soffer <nsoffer@redhat.com>
import json
import socket
import ctypes
import sys
import struct
_API_VERSION_MAJOR = 0
_IPC_ADDR = "\0/org/kernel/linux/storage/multipathd"
_IPC_LEN_SIZE = ctypes.sizeof(ctypes.c_ssize_t(0))
if sys.version_info[0] < 3:
_CMD_HEAD = struct.Struct("q" if _IPC_LEN_SIZE == 8 else "i")
else:
_CMD_HEAD = struct.Struct("n")
class DMMP_path(object):
"""
DMMP_pathgroup is the abstraction of path in multipath-tools.
"""
def __init__(self, path):
"""
Internal function. For mpaths_get() only.
"""
for key, value in path.items():
setattr(self, "_%s" % key, value)
STATUS_UNKNOWN = 0
STATUS_DOWN = 2
STATUS_UP = 3
STATUS_SHAKY = 4
STATUS_GHOST = 5
STATUS_PENDING = 6
STATUS_TIMEOUT = 7
STATUS_DELAYED = 9
_STATUS_CONV = {
"undef": STATUS_UNKNOWN,
"faulty": STATUS_DOWN,
"ready": STATUS_UP,
"shaky": STATUS_SHAKY,
"ghost": STATUS_GHOST,
"i/o pending": STATUS_PENDING,
"i/o timeout": STATUS_TIMEOUT,
"delayed": STATUS_DELAYED,
}
@property
def blk_name(self):
"""
String. Block name of current path. Examples: "sda", "nvme0n1".
"""
return self._dev
@property
def status(self):
"""
Integer. Status of current path. Possible values are:
* DMMP_path.STATUS_UNKNOWN
Unknown status.
* DMMP_path.STATUS_DOWN
Path is down and you shouldn't try to send commands to it.
* DMMP_path.STATUS_UP
Path is up and I/O can be sent to it.
* DMMP_path.STATUS_SHAKY
Only emc_clariion checker when path not available for "normal"
operations.
* DMMP_path.STATUS_GHOST
Only hp_sw and rdac checkers. Indicates a "passive/standby" path
on active/passive HP arrays. These paths will return valid answers
to certain SCSI commands (tur, read_capacity, inquiry, start_stop),
but will fail I/O commands.
The path needs an initialization command to be sent to it in order
for I/Os to succeed.
* DMMP_path.STATUS_PENDING
Available for all async checkers when a check IO is in flight.
* DMMP_path.STATUS_TIMEOUT
Only tur checker when command timed out.
* DMMP_path.STATUS_DELAYED
If a path fails after being up for less than delay_watch_checks
checks, when it comes back up again, it will not be marked as up
until it has been up for delay_wait_checks checks. During this
time, it is marked as "delayed".
"""
return self._STATUS_CONV.get(self.status_string, self.STATUS_UNKNOWN)
@property
def status_string(self):
"""
String. Status of current path. Possible values are:
* "undef"
STATUS_UNKNOWN
* "faulty"
STATUS_DOWN
* "ready"
STATUS_UP
* "shaky"
STATUS_SHAKY
* "ghost"
STATUS_GHOST
* "i/o pending"
STATUS_PENDING
* "i/o timeout"
STATUS_TIMEOUT
* "delayed"
STATUS_DELAYED
"""
return self._chk_st
def __str__(self):
return "%s|%s" % (self.blk_name, self.status_string)
class DMMP_pathgroup(object):
"""
DMMP_pathgroup is the abstraction of path group in multipath-tools.
"""
def __init__(self, pg):
"""
Internal function. For mpaths_get() only.
"""
self._paths = []
for key, value in pg.items():
if key == "paths":
for path in pg["paths"]:
self._paths.append(DMMP_path(path))
else:
setattr(self, "_%s" % key, value)
STATUS_UNKNOWN = 0
STATUS_ENABLED = 1
STATUS_DISABLED = 2
STATUS_ACTIVE = 3
_STATUS_CONV = {
"undef": STATUS_UNKNOWN,
"enabled": STATUS_ENABLED,
"disabled": STATUS_DISABLED,
"active": STATUS_ACTIVE,
}
@property
def id(self):
"""
Integer. Group ID of current path group. Could be used for
switching active path group.
"""
return self._group
@property
def status(self):
"""
Integer. Status of current path group. Possible values are:
* DMMP_pathgroup.STATUS_UNKNOWN
Unknown status
* DMMP_pathgroup.STATUS_ENABLED
Standby to be active
* DMMP_pathgroup.STATUS_DISABLED
Disabled due to all path down
* DMMP_pathgroup.STATUS_ACTIVE
Selected to handle I/O
"""
return self._STATUS_CONV.get(self.status_string, self.STATUS_UNKNOWN)
@property
def status_string(self):
"""
String. Status of current path group. Possible values are:
* "undef"
STATUS_UNKNOWN
* "enabled"
STATUS_ENABLED
* "disabled"
STATUS_DISABLED
* "active"
STATUS_ACTIVE
"""
return self._dm_st
@property
def priority(self):
"""
Integer. Priority of current path group. The enabled path group with
highest priority will be next active path group if active path group
down.
"""
return self._pri
@property
def selector(self):
"""
String. Selector of current path group. Path group selector determines
which path in active path group will be use to next I/O.
"""
return self._selector
@property
def paths(self):
"""
List of DMMP_path objects.
"""
return self._paths
def __str__(self):
return "%s|%s|%d" % (self.id, self.status_string, self.priority)
class DMMP_mpath(object):
"""
DMMP_mpath is the abstraction of mpath(aka. map) in multipath-tools.
"""
def __init__(self, mpath):
"""
Internal function. For mpaths_get() only.
"""
self._path_groups = []
for key, value in mpath.items():
if key == "path_groups":
for pg in mpath["path_groups"]:
self._path_groups.append(DMMP_pathgroup(pg))
else:
setattr(self, "_%s" % key, value)
@property
def wwid(self):
"""
String. WWID of current mpath.
"""
return self._uuid
@property
def name(self):
"""
String. Name(alias) of current mpath.
"""
return self._name
@property
def path_groups(self):
"""
List of DMMP_mpath objects.
"""
return self._path_groups
@property
def paths(self):
"""
List of DMMP_path objects
"""
rc = []
for pg in self.path_groups:
rc.extend(pg.paths)
return rc
@property
def kdev_name(self):
"""
The string for DEVNAME used by kernel in uevent.
"""
return self._sysfs
def __str__(self):
return "'%s'|'%s'" % (self.wwid, self.name)
def _ipc_exec(s, cmd):
buff = _CMD_HEAD.pack(len(cmd) + 1) + bytearray(cmd, 'utf-8') + b'\0'
s.sendall(buff)
buff = s.recv(_IPC_LEN_SIZE)
if not buff:
return ""
output_len = _CMD_HEAD.unpack(buff)[0]
output = s.recv(output_len).decode("utf-8")
return output.strip('\x00')
def mpaths_get():
"""
Usage:
Query all multipath devices.
Parameters:
void
Returns:
[DMMP_mpath,] List of DMMP_mpath objects.
"""
rc = []
s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
s.settimeout(60)
s.connect(_IPC_ADDR)
json_str = _ipc_exec(s, "show maps json")
s.close()
if len(json_str) == 0:
return rc
all_data = json.loads(json_str)
if all_data["major_version"] != _API_VERSION_MAJOR:
raise exception("incorrect version")
for mpath in all_data["maps"]:
rc.append(DMMP_mpath(mpath))
return rc