Description of problem:
Remove RBD images from ceph server through rbd while refreshing the pool. Pool
refreshing is completed without error. However, libvirtd is killed
while getting rbd volume name which is already removed

Version-Release number of selected component (if applicable):
libvirt-1.3.1-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. prepare a running rbd pool
# virsh pool-dumpxml rbd
<pool type='rbd'>
  <name>rbd</name>
  <uuid>ebda974a-4fb7-4af2-b1a0-7a94e5cdda98</uuid>
  <capacity unit='bytes'>0</capacity>
  <allocation unit='bytes'>0</allocation>
  <available unit='bytes'>0</available>
  <source>
    <host name='10.66.110.191'/>
    <name>yy</name>
  </source>
</pool>

2. create volumes
# for i in {1..100}; do virsh vol-create-as rbd vol$i 100M; done

3. refresh rbd pool, meanwhile, remove 2 rbd vols from rbd server
# virsh pool-refresh rbd

[root@osd1 ~]# rbd rm yy/vol97
Removing image: 100% complete...done.
[root@osd1 ~]# rbd rm yy/vol96
Removing image: 100% complete...done.

4. list vol
# virsh vol-list rbd
error: Failed to list volumes
error: key in virGetStorageVol must not be NULL

5. get volume name which is removed in step 3
# virsh vol-name yy/vol97
error: Disconnected from qemu:///system due to I/O error
error: failed to get vol 'yy/vol97'
error: internal error: client socket is closed

error: One or more references were leaked after disconnect from the hypervisor

Actual results:


Expected results:
Pool refreshing should properly handle the volumes which are deleted through
other route than libvirt 

Additional info:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f2c47cd7700 (LWP 17954)]
0x00007f2c556c7fc6 in __strcmp_sse42 () from /lib64/libc.so.6
(gdb) bt
#0  0x00007f2c556c7fc6 in __strcmp_sse42 () from /lib64/libc.so.6
#1  0x00007f2c58362c99 in virStorageVolDefFindByKey (pool=<optimized out>,
    key=key@entry=0x7f2c3001c250 "yy/vol97") at conf/storage_conf.c:1734
#2  0x00007f2c3eb05698 in storageVolLookupByKey (conn=0x7f2c34003d40,
    key=0x7f2c3001c250 "yy/vol97") at storage/storage_driver.c:1501
#3  0x00007f2c583bad57 in virStorageVolLookupByKey (conn=0x7f2c34003d40,
    key=0x7f2c3001c250 "yy/vol97") at libvirt-storage.c:1342
#4  0x00007f2c58fe64d8 in remoteDispatchStorageVolLookupByKey (
    server=0x7f2c5ae1afb0, msg=0x7f2c5ae3cda0, ret=0x7f2c3001c3a0,
    args=0x7f2c3001c4e0, rerr=0x7f2c47cd6c30, client=0x7f2c5ae3c290)
    at remote_dispatch.h:15967
#5  remoteDispatchStorageVolLookupByKeyHelper (server=0x7f2c5ae1afb0,
    client=0x7f2c5ae3c290, msg=0x7f2c5ae3cda0, rerr=0x7f2c47cd6c30,
    args=0x7f2c3001c4e0, ret=0x7f2c3001c3a0) at remote_dispatch.h:15945
#6  0x00007f2c584033a2 in virNetServerProgramDispatchCall (msg=0x7f2c5ae3cda0,
    client=0x7f2c5ae3c290, server=0x7f2c5ae1afb0, prog=0x7f2c5ae37fa0)
    at rpc/virnetserverprogram.c:437
#7  virNetServerProgramDispatch (prog=0x7f2c5ae37fa0,
    server=server@entry=0x7f2c5ae1afb0, client=0x7f2c5ae3c290,
    msg=0x7f2c5ae3cda0) at rpc/virnetserverprogram.c:307
#8  0x00007f2c583fe61d in virNetServerProcessMsg (msg=<optimized out>,
    prog=<optimized out>, client=<optimized out>, srv=0x7f2c5ae1afb0)
    at rpc/virnetserver.c:135
---Type <return> to continue, or q <return> to quit---
#9  virNetServerHandleJob (jobOpaque=<optimized out>, opaque=0x7f2c5ae1afb0)
    at rpc/virnetserver.c:156
#10 0x00007f2c582f78e5 in virThreadPoolWorker (
    opaque=opaque@entry=0x7f2c5ae0ff60) at util/virthreadpool.c:145
#11 0x00007f2c582f6e08 in virThreadHelper (data=<optimized out>)
    at util/virthread.c:206
#12 0x00007f2c5595edc5 in start_thread () from /lib64/libpthread.so.0
#13 0x00007f2c5568c1cd in clone () from /lib64/libc.so.6