一、cinder-api服务的入口函数

D:\code-program\cinder-ocata_cinder\cinder\api\contrib\admin_actions.py
from cinder import volume
self.volume_api = volume.API()
class VolumeAdminController(AdminController):
"""AdminController for Volumes."""
@wsgi.Controller.api_version('3.28')
@wsgi.action('os-migrate_volume_progress')
def _get_migrate_volume_progress(self, req, id, body):
"""Get the migration progress of a volume."""
context = req.environ['cinder.context']
self.authorize(context, 'get_migrate_volume_progress')daim
volume = self._get(context, id)-----根据卷的uuid获取卷的信息
return self.volume_api.get_migrate_volume_progress(context, volume)---调用volume.api里面的接口

D:\code-program\cinder-ocata_cinder\cinder\volume\api.py
from cinder.volume import rpcapi as volume_rpcapi
self.volume_rpcapi = volume_rpcapi.VolumeAPI()
class API(base.Base):
"""API for interacting with the volume manager."""
AVAILABLE_MIGRATION_STATUS = (None, 'deleting', 'error', 'success')
#返回一个特定卷的迁移进度，入参为将被迁移或者正在被迁移的源卷信息，
#返回值包括卷uuid，迁移的状态、及迁移的进度
#如果卷的迁移状态migration_status为migrating，则获取卷的实际迁移进度
#如果卷的迁移状态migration_status为starting,则返回卷的迁移进度为0%，在源卷所在的存储节点cinder-volume服务没有接受到发送的
#卷迁移rpc.cast请求以前，此时调用获取卷的迁移进度，会一直是0%的状态
#如果卷的迁移进度migration_status为success',completing'，则返回卷的迁移进度为100%，在卷成功迁移完成之后，获取卷的迁移进度，
#那么它是100%
#对于获取到的卷的迁移进度为NA，这个值，那么一种可能情况是，卷的迁移消息还没被cinder.volume接口migrate_volume及时的处理，就调用
#获取卷的迁移进度api接口
@wrap_check_policy
def get_migrate_volume_progress(self, context, volume):
"""Return the migration progress for a specific volume.

    :param context: the context of the caller  
    :param volume: the source volume to be migrated or being migrated  
    :return the volume migration progress including volume id, migration  
            status and migration progress  
    """  
    volume\_progress = {'volume\_id': volume\['id'\],  
                       'migration\_status': volume\['migration\_status'\],  
                       'migration\_progress': 'NA'}---初始值为NA  
    if volume\['migration\_status'\] == 'migrating':  
        progress = self.volume\_rpcapi.get\_migrate\_volume\_progress(------对步骤1的详解  
            context, volume)  
        volume\_progress\['migration\_progress'\] = progress + "%"  
    elif volume\['migration\_status'\] == 'starting':  
        volume\_progress\['migration\_progress'\] = '0%'  
    elif volume\['migration\_status'\] in ('success', 'completing'):  
        volume\_progress\['migration\_progress'\] = '100%'  
    LOG.info(\_LI('Volume %(vol\_id)s has been migrated %(mig\_progress)s.'),  
             {'vol\_id': volume\['id'\],  
              'mig\_progress': volume\_progress\['migration\_progress'\]})  
    return {'volume': volume\_progress}

对步骤1的详解
给源卷所在的cinder-volume服务的存储节点，发送一个rpc.call请求，来获取迁移的进度
D:\code-program\cinder-ocata_cinder\cinder\volume\rpcapi.py
class VolumeAPI(rpc.RPCAPI):
"""Client side of the volume rpc API.
@rpc.assert_min_rpc_version('3.11')
def get_migrate_volume_progress(self, ctxt, volume):
version = self._compat_ver('3.11')
cctxt = self._get_cctxt(volume['host'], version=version)
return cctxt.call(ctxt, 'get_migrate_volume_progress',
volume=volume)

二、源卷所在的cinder-volume服务存储节点，接受rpc.call请求，并处理，虽然配置了cinder-volume对应的驱动，volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver

但是最终调用的是BaseVD里面的方法

D:\code-program\cinder-ocata_cinder\cinder\volume\driver.py
@six.add_metaclass(abc.ABCMeta)
class BaseVD(object):
def get_migrate_volume_progress(self, context, volume, src_path=None,
dest_path=None,
migration_mode='HOST_BASED'):
if migration_mode is None and volume['id'] in self._migration_info:
migration_mode = self._migration_info[volume['id']]
# NOTE(fengzy): If the volume is migrated using dd command,
# e.g. volume migration from LVM to LVM, mode is HOST_BASED.
# For the volume is migrated using file I/O, mode is FILE_BASED,
# DRIVER_BASED need driver support. And now our mode only
# HOST_BASED and FILE_BASED, no DRIVER_BASED.
#由于是lvm到lvm的迁移，因此mode是基于主机的 HOST_BASED
if migration_mode == self.HOST_BASED:-----走该分支
return self.get_host_based_volume_progress(volume, src_path,-----对步骤二进行详解
dest_path)
elif migration_mode == self.DRIVER_BASED:
progress = self.get_migration_progress(
context, volume)
if progress:
return six.text_type(progress)
else:
return self.UNKNOWN_PROGRESS
elif migration_mode == self.FILE_BASED:
key_handle = volume['id'] + 'dest_handle'
if key_handle in self._migration_info:
handle = self._migration_info[key_handle]
if handle:
try:
size_in_bytes = int(volume['size']) * units.Gi
if not handle.closed:
pro = six.text_type(
handle.tell() * 100 / size_in_bytes)
self._migration_info[volume['id'] +
'previous_progress'] = pro
return pro
else:
return '100'
except ValueError:
return self._migration_info[volume['id'] +
'previous_progress']
else:
return self._migration_info[volume['id'] +
'previous_progress']
return self.UNKNOWN_PROGRESS

对步骤二进行详解
def get_host_based_volume_progress(self, volume, src_path=None,
dest_path=None):
key_source = volume['id'] + 'source'
key_dest = volume['id'] + 'dest'
if dest_path is None:
dest_path = self._migration_info.get(key_dest, None)
if not dest_path:
return '0'
if src_path is None:
src_path = self._migration_info.get(key_source, None)
if not src_path:
return '0'

    pid = self.get\_pid\_for\_host\_based\_migration(volume\['id'\], src\_path,--获取dd拷贝命令的pid信息  
                                                dest\_path)  
    if pid:  
    #迁移进度的算法，按照文件大小的相除进行计算的  
        self.\_migration\_info\[volume\['id'\] + 'pid'\] = pid  
        size\_in\_bytes = int(volume\['size'\]) \* units.Gi  
        position\_path = ('/proc/%s/fdinfo/1') % pid  
        try:  
            output = utils.read\_file\_as\_root(position\_path)  
            position = self.\_get\_position(output)  
            progress = six.text\_type(position \* 100 / size\_in\_bytes)  
            self.\_migration\_info\[volume\['id'\] +  
                                 'previous\_progress'\] = progress  
            return progress  
        except exception.FileNotFound:  
            return self.\_migration\_info.get(  
                volume\['id'\] + 'previous\_progress', '0')  
    else:  
        return self.\_migration\_info.get(  
            volume\['id'\] + 'previous\_progress', '0')

def get\_pid\_for\_host\_based\_migration(self, volume\_id, src\_path,  
                                     dest\_path):  
    # Get the PID for the block copy command for the source volume.  
    pid = self.\_migration\_info.get(volume\_id + 'pid', None)  
    if pid is None:  
        pid = volume\_utils.get\_process\_pid('dd', src\_path,  
                                           dest\_path)  
    return pid  

D:\code-program\cinder-ocata_cinder\cinder\volume\utils.py
def get_process_pid(command_name, src_path, dest_path):
for proc in psutil.process_iter():
try:
p_info = proc.as_dict(attrs=['pid', 'name', 'cmdline'])
except psutil.NoSuchProcess:
pass
else:
is_in_path = "if=" + src_path in p_info['cmdline'] and\
"of=" + dest_path in p_info['cmdline']
if command_name == p_info['name'] and is_in_path:
return p_info['pid']
return None

　三、迁移的例子

[root@test network-scripts]# ps -ef |grep dd
root 2 0 0 2015 ? 00:00:00 [kthreadd]
root 516 1 86 08:42 ? 08:51:10 /usr/libexec/qemu-kvm -name instance-0000dcaf -S -M rhel6.5.0 -cpu SandyBridge,+erms,+smep,+fsgsbase,+pdpe1gb,+rdrand,+f16c,+osxsave,+dca,+pcid,+pdcm,+xtpr,+tm2,+est,+smx,+vmx,+ds_cpl,+monitor,+dtes64,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme -enable-kvm -m 32768 -realtime mlock=off -smp 16,sockets=16,cores=1,threads=1 -uuid e664cce7-a4ac-410b-a775-38c19b576836 -smbios type=1,manufacturer=Red Hat Inc.,product=OpenStack Nova,version=2014.1.1-5.el6,serial=6d3753e6-3570-415a-89e3-ea2bd6e4559d,uuid=e664cce7-a4ac-410b-a775-38c19b576836 -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/instance-0000dcaf.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4 -drive file=/os_instance/e664cce7-a4ac-410b-a775-38c19b576836/disk,if=none,id=drive-virtio-disk0,format=qcow2,cache=writethrough -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive file=/dev/mapper/vg_os-volume--54549594--66ac--4edd--97a6--410071d7798e,if=none,id=drive-virtio-disk1,format=raw,serial=54549594-66ac-4edd-97a6-410071d7798e,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk1,id=virtio-disk1 -drive file=/dev/mapper/vg_os-volume--c9945a36--ac4b--4a55--92e6--4a7c361b7649,if=none,id=drive-virtio-disk2,format=raw,serial=c9945a36-ac4b-4a55-92e6-4a7c361b7649,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk2,id=virtio-disk2 -drive file=/os_instance/e664cce7-a4ac-410b-a775-38c19b576836/disk.config,if=none,media=cdrom,id=drive-ide0-1-1,readonly=on,format=raw,cache=writethrough -device ide-drive,bus=ide.1,unit=1,drive=drive-ide0-1-1,id=ide0-1-1 -netdev tap,fd=24,id=hostnet0,vhost=on,vhostfd=25 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:6e:ba:a3,bus=pci.0,addr=0x3 -chardev file,id=charserial0,path=/os_instance/e664cce7-a4ac-410b-a775-38c19b576836/console.log -device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -chardev pty,id=charchannel0 -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -spice port=5900,addr=0.0.0.0,seamless-migration=on -k en-us -vga qxl -global qxl-vga.ram_size=67108864 -global qxl-vga.vram_size=67108864 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8
root 3157 1876 0 01:38 ? 00:00:00 sudo cinder-rootwrap /etc/cinder/rootwrap.conf dd if=/dev/mapper/vg_os-volume--54549594--66ac--4edd--97a6--410071d7798e of=/dev/disk/by-path/ip-192.168.0.1:3260-iscsi-iqn.2010-10.org.openstack:volume-d39b3037-893d-4590-8fc3-ecfbc476d8b8-lun-1 count=1048576 bs=1M iflag=direct oflag=direct
root 3158 3157 0 01:38 ? 00:00:00 /usr/bin/python /usr/bin/cinder-rootwrap /etc/cinder/rootwrap.conf dd if=/dev/mapper/vg_os-volume--54549594--66ac--4edd--97a6--410071d7798e of=/dev/disk/by-path/ip-192.168.0.1:3260-iscsi-iqn.2010-10.org.openstack:volume-d39b3037-893d-4590-8fc3-ecfbc476d8b8-lun-1 count=1048576 bs=1M iflag=direct oflag=direct
root 3160 3158 0 01:38 ? 00:02:50 /bin/dd if=/dev/mapper/vg_os-volume--54549594--66ac--4edd--97a6--410071d7798e of=/dev/disk/by-path/ip-192.168.0.1:3260-iscsi-iqn.2010-10.org.openstack:volume-d39b3037-893d-4590-8fc3-ecfbc476d8b8-lun-1 count=1048576 bs=1M iflag=direct oflag=direct
root 17245 1 0 2019 ? 12:49:45 /opt/promes/exporter/node_exporter_p18/node_exporter-0.18.1.linux-amd64/node_exporter --web.listen-address=:19100
root 26012 12253 0 18:55 pts/3 00:00:00 grep dd
root 27426 2 0 2016 ? 00:00:29 [ib_addr]
[root@testnetwork-scripts]#

[root@test by-path]# ls
ip-192.168.0.2:3260-iscsi-iqn.2010-10.org.openstack:volume-d39b3037-893d-4590-8fc3-ecfbc476d8b8-lun-1 pci-0000:01:00.0-scsi-0:2:0:0-part2
pci-0000:01:00.0-scsi-0:2:0:0 pci-0000:01:00.0-scsi-0:2:1:0
pci-0000:01:00.0-scsi-0:2:0:0-part1 pci-0000:01:00.0-scsi-0:2:1:0-part1