Since the new json interfaces added in qemu-2.9, the former json formats in BZ1134878 and BZ1371758 don't work. Libvirt should update codes in json parsing to catch up with changes in qemu-2.9.

Also reproduce for gluster ServerType is 'inet': 

Pkgs version:
libvirt-3.2.0-10.virtcov.el7.x86_64
qemu-kvm-rhev-2.9.0-10.el7.x86_64


Steps:
1.# qemu-img create -f qcow2 -b 'json:{"file.driver":"gluster","file.volume":"gluster-vol1","file.path":"R.qcow2","file.logfile":"/tmp/log","file.debug":9,"file.server":[ {"type":"inet","host":"10.66.*.*","port":"24007"}]}' /var/lib/libvirt/images/gluster_socket.img
Formatting '/var/lib/libvirt/images/gluster_socket.img', fmt=qcow2 size=104857600 backing_file=json:{"file.driver":"gluster",,"file.volume":"gluster-vol1",,"file.path":"R.qcow2",,"file.logfile":"/tmp/log",,"file.debug":9,,"file.server":[ {"type":"inet",,"host":"10.66.*.*",,"port":"24007"}]} encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16

# ls /var/lib/libvirt/images/
gluster_socket.img

2.# virsh pool-refresh default
error: Failed to refresh pool default
error: internal error: unknown backing store transport protocol 'inet'

Inet type for gluster is added since commit fce5d538 in qemu-2.9.

Upstream fixes the issues pointed out in this bug by:

commit 1f915d40a220c6bb05d8630507eed045cabfba34
Author: Peter Krempa <pkrempa>
Date:   Mon Jun 19 14:37:47 2017 +0200

    util: storage: Add support for type 'inet' in virStorageSourceParseBackingJSONSocketAddress
    
    'SocketAddress' structure was changed to contain 'inet' instead of
    'tcp' since qemu commit c5f1ae3ae7b. Existing entries have a backward
    compatibility layer.


commit 4fac5a1935041254964313ed722fa8d59f8fa2de
Author: Peter Krempa <pkrempa>
Date:   Thu Jun 15 17:44:18 2017 +0200

    util: storage: adapt to changes in JSON format for ceph/rbd
    
    Since qemu 2.9 the options changed from a monolithic string into fine
    grained options for the json pseudo-protocol object.

Hi Peter,
Please add the patches 'util: storage: adapt to changes in JSON format for sheepdog' because libvirt also couldn't recognize the new json format in sheepdog.

Well, here is the rest of the upstream commits not mentioned above:

commit b16133b114fd0d787de1cda6bf2ff0110c523a32
Author: Peter Krempa <pkrempa>
Date:   Thu Jun 15 17:44:18 2017 +0200

    util: storage: adapt to changes in JSON format for sheepdog
    
    Since qemu 2.9 the options changed from a monolithic string into fine
    grained options for the json pseudo-protocol object.

commit ea2c418ac30628d1db021f351f0ea5440ba5e4e4
Author: Peter Krempa <pkrempa>
Date:   Thu Jun 15 17:44:18 2017 +0200

    util: storage: adapt to changes in JSON format for ssh
    
    Since qemu 2.9 the options changed from a monolithic string into fine
    grained options for the json pseudo-protocol object.

commit 35d23f90b2266adb93079755161515699a401932
Author: Peter Krempa <pkrempa>
Date:   Thu Jun 15 17:44:18 2017 +0200

    util: storage: adapt to changes in JSON format for NBD
    
    Since 2.9 the host and port for NBD are no longer directly under the
    json pseudo-protocol object, but rather belong to a sub-object called
    'server'.

commit b24bc54080b4bc444e60560c0db00c5867e74000
Author: Peter Krempa <pkrempa>
Date:   Thu Jun 15 17:12:01 2017 +0200

    util: storage: Add JSON parser for new options in iSCSI protocol
    
    Starting from qemu 2.9, more granular options are supported. Add parser
    for the relevant bits.
    
    With this patch libvirt is able to parse the host and target IQN of from
    the JSON pseudo-protocol specification.
    
    This corresponds to BlockdevOptionsIscsi in qemu qapi.

Verified on qemu-kvm-rhev-2.10.0-5.el7.x86_64 libvirt-3.9.0-1.el7.x86_64

##################################################
Prepare json backing images
####################
1. On rbd protocol
Build ceph server environment

i. with "conf" key
Prepare a ceoh conf file:
# cat /tmp/ceph.conf
[global]
fsid = ab720744-845c-4f18-bd3c-fa61d62f0840
mon_initial_members = mon, osd1, osd2
mon_host = XX.XX.XX.XX,XX.XX.XX.XX,XX.XX.XX.XX
auth_cluster_required = none 
auth_service_required = none
auth_client_required = none
filestore_xattr_use_omap = true

# qemu-img create -b 'json:{"file": { "driver": "rbd", "pool": "rbd", "image": "lmen.img","conf": "/tmp/ceph.conf" } }' -f qcow2 /var/lib/libvirt/images/ceph-conf.qcow2
Formatting '/var/lib/libvirt/images/ceph-conf.qcow2', fmt=qcow2 size=104857600 backing_file=json:{"file": { "driver": "rbd",, "pool": "rbd",, "image": "lmen.img",,"conf": "/tmp/ceph.conf" } } cluster_size=65536 lazy_refcounts=off refcount_bits=16

ii. with "server" key
# qemu-img create -b 'json:{"file": { "driver": "rbd", "pool": "rbd", "image": "lmen.img", "server": [{"host": "XX.XX.XX.XX", "port": "6789"}] } }' -f qcow2 /var/lib/libvir
t/images/ceph-server.qcow2
Formatting '/var/lib/libvirt/images/ceph-server.qcow2', fmt=qcow2 size=104857600 backing_file=json:{"file": { "driver": "rbd",, "pool": "rbd",, "image": "lmen.img",, "serve
r": [{"host": "XX.XX.XX.XX",, "port": "6789"}] } } cluster_size=65536 lazy_refcounts=off refcount_bits=16

iii. with snapshot
# qemu-img create -b 'json:{"file": { "driver": "rbd", "pool": "rbd", "image": "lmen.img","conf": "/tmp/ceph.conf", "snapshot": "sn1" } }' -f qcow2 /var/lib/libvirt/images/ceph-server-snap.qcow2
Formatting '/var/lib/libvirt/images/ceph-server-snap.qcow2', fmt=qcow2 size=104857600 backing_file=json:{"file": { "driver": "rbd",, "pool": "rbd",, "image": "lmen.img",,"conf": "/tmp/ceph.conf",, "snapshot": "sn1" } } cluster_size=65536 lazy_refcounts=off refcount_bits=16


2. On sheepdog protocol:
Build sheepdog server

# qemu-img create -b 'json:{"file":{"driver":"sheepdog","server":{"host":"XX.XX.XX.XX","port":"7000","type":"inet"},"tag":"","vdi":"Alice"}}' -f qcow2 /var/lib/libvirt/images/sheepdog.qcow2
Formatting '/var/lib/libvirt/images/sheepdog.qcow2', fmt=qcow2 size=5368709120 backing_file=json:{"file":{"driver":"sheepdog",,"server":{"host":"XX.XX.XX.XX",,"port":"7000",,"type":"inet"},,"tag":"",,"vdi":"Alice"}} cluster_size=65536 lazy_refcounts=off refcount_bits=16

3. On ssh protocol:
# eval ssh-agent
# ssh-add /root/.ssh/id_rsa
Identity added: /root/.ssh/id_rsa (/root/.ssh/id_rsa)

# qemu-img create -b 'json:{"file":{"driver":"ssh","server":{"host":"XX.XX.XX.XX","port":"22"},"path":"/tmp/ssh","user":"root","host_key_check":"no"}}' -f qcow2 /var/lib/libvirt/images/ssh.qcow2
Formatting '/var/lib/libvirt/images/ssh.qcow2', fmt=qcow2 size=104857600 backing_file=json:{"file":{"driver":"ssh",,"server":{"host":"XX.XX.XX.XX",,"port":"22"},,"path":"/tmp/ssh",,"user":"root",,"host_key_check":"no"}} cluster_size=65536 lazy_refcounts=off refcount_bits=16

4. On nbd protocol:
Setup nbd server, one with exportname, one without exportname

# qemu-img create -b 'json:{"file":{"driver":"nbd","server":{"host":"XX.XX.XX.XX","port":"10000", "type":"inet"}}}' -f qcow2 /var/lib/libvirt/images/nbd.qcow2
Formatting '/var/lib/libvirt/images/nbd.qcow2', fmt=qcow2 size=1073741824 backing_file=json:{"file":{"driver":"nbd",,"server":{"host":"XX.XX.XX.XX",,"port":"10000",, "type":"inet"}}} cluster_size=65536 lazy_refcounts=off refcount_bits=16

# qemu-img create -b 'json:{"file":{"driver":"nbd","server":{"host":"XX.XX.XX.XX","port":"10001", "type":"inet"}, "export": "nbd"}}' -f qcow2 /var/lib/libvirt/images/nbd-export.qcow2
Formatting '/var/lib/libvirt/images/nbd-export.qcow2', fmt=qcow2 size=1073741824 backing_file=json:{"file":{"driver":"nbd",,"server":{"host":"XX.XX.XX.XX",,"port":"10001",, "type":"inet"},, "export": "nbd"}} cluster_size=65536 lazy_refcounts=off refcount_bits=16

5. On iscsi protocol:
Setup iscsi server

# qemu-img create -b 'json:{"file":{"driver":"iscsi", "transport": "tcp", "portal": "XX.XX.XX.XX:3260", "target": "iqn.2017-08.com.virttest:emulated-iscsi-noauth.target1"}}' -f qcow2 /var/lib/libvirt/images/iscsi.qcow2
Formatting '/var/lib/libvirt/images/iscsi.qcow2', fmt=qcow2 size=0 backing_file=json:{"file":{"driver":"iscsi",, "transport": "tcp",, "portal": "XX.XX.XX.XX:3260",, "target": "iqn.2017-08.com.virttest:emulated-iscsi-noauth.target1"}} cluster_size=65536 lazy_refcounts=off refcount_bits=16

##################################################
Pool refresh
####################
Refresh the pool where images are located in
# virsh pool-dumpxml default                                          
<pool type='dir'>
  <name>default</name>
  <uuid>03a38a8d-a7fc-4f6a-be13-b9c4b6935758</uuid>
  <capacity unit='bytes'>107347968000</capacity>
  <allocation unit='bytes'>40656568320</allocation>
  <available unit='bytes'>66691399680</available>
  <source>
  </source>
  <target>
    <path>/var/lib/libvirt/images</path>
    <permissions>
      <mode>0711</mode>
      <owner>0</owner>
      <group>0</group>
      <label>system_u:object_r:virt_image_t:s0</label>
    </permissions>
  </target>
</pool>

# virsh pool-refresh default                                                             
Pool default refreshed

Pool refresh operation works well.

##################################################
Attach/detach backing images
####################
Images backing on rbd, nbd, iscsi supports attach/detach operations

# virsh list
 Id    Name                           State
----------------------------------------------------
 2     V                              running

# virsh attach-disk V /var/lib/libvirt/images/ceph-conf.qcow2 vdb --subdriver qcow2
Disk attached successfully

# virsh attach-disk V /var/lib/libvirt/images/ceph-server.qcow2 vdc --subdriver qcow2
Disk attached successfully

# virsh attach-disk V /var/lib/libvirt/images/ceph-server-snap.qcow2 vdd --subdriver qcow2
Disk attached successfully

# virsh attach-disk V /var/lib/libvirt/images/nbd.qcow2 vde --subdriver qcow2
Disk attached successfully

# virsh attach-disk V /var/lib/libvirt/images/nbd-export.qcow2 vdf --subdriver qcow2
Disk attached successfully

# virsh attach-disk V /var/lib/libvirt/images/iscsi.qcow2 vdg --subdriver qcow2
Disk attached successfully

# virsh domblklist V
Target     Source
------------------------------------------------
vda        /var/lib/libvirt/images/V.qcow2
vdb        /var/lib/libvirt/images/ceph-conf.qcow2
vdc        /var/lib/libvirt/images/ceph-server.qcow2
vdd        /var/lib/libvirt/images/ceph-server-snap.qcow2
vde        /var/lib/libvirt/images/nbd.qcow2
vdf        /var/lib/libvirt/images/nbd-export.qcow2
vdg        /var/lib/libvirt/images/iscsi.qcow2

# virsh domstats V
Domain: 'V'
  state.state=1
  state.reason=1
  cpu.time=26280337141
  cpu.user=2470000000
  cpu.system=4630000000
  balloon.current=1048576
  balloon.maximum=1048576
  balloon.swap_in=0
  balloon.swap_out=0
  balloon.major_fault=194
  balloon.minor_fault=174428
  balloon.unused=899064
  balloon.available=1016140
  balloon.usable=848020
  balloon.last-update=1510294598
  balloon.rss=493100
  vcpu.current=1
  vcpu.maximum=1
  vcpu.0.state=1
  vcpu.0.time=20610000000
  vcpu.0.wait=0
  vcpu.0.halted=yes
  net.count=1
  net.0.name=vnet0
  net.0.rx.bytes=2461498
  net.0.rx.pkts=32506
  net.0.rx.errs=0
  net.0.rx.drop=0
  net.0.tx.bytes=26284
  net.0.tx.pkts=353
  net.0.tx.errs=0
  net.0.tx.drop=0
  block.count=7
  block.0.name=vda
  block.0.path=/var/lib/libvirt/images/V.qcow2
  block.0.rd.reqs=5436
  block.0.rd.bytes=134632960
  block.0.rd.times=20979604363
  block.0.wr.reqs=879
  block.0.wr.bytes=15651328
  block.0.wr.times=701348343
  block.0.fl.reqs=325
  block.0.fl.times=5570312840
  block.0.allocation=1091702784
  block.0.capacity=10737418240
  block.0.physical=1336868864
  block.1.name=vdb
  block.1.path=/var/lib/libvirt/images/ceph-conf.qcow2
  block.1.rd.reqs=45
  block.1.rd.bytes=1069056
  block.1.rd.times=4312097
  block.1.wr.reqs=0
  block.1.wr.bytes=0
  block.1.wr.times=0
  block.1.fl.reqs=0
  block.1.fl.times=0
  block.1.allocation=0
  block.1.capacity=104857600
  block.1.physical=200704
  block.2.name=vdc
  block.2.path=/var/lib/libvirt/images/ceph-server.qcow2
  block.2.rd.reqs=45
  block.2.rd.bytes=1069056
  block.2.rd.times=4373913
  block.2.wr.reqs=0
  block.2.wr.bytes=0
  block.2.wr.times=0
  block.2.fl.reqs=0
  block.2.fl.times=0
  block.2.allocation=0
  block.2.capacity=104857600
  block.2.physical=200704
  block.3.name=vdd                                                                                                                                                                                                                                                                                                                                                               [139/785]
  block.3.path=/var/lib/libvirt/images/ceph-server-snap.qcow2
  block.3.rd.reqs=45
  block.3.rd.bytes=1069056
  block.3.rd.times=2498727
  block.3.wr.reqs=0
  block.3.wr.bytes=0
  block.3.wr.times=0
  block.3.fl.reqs=0
  block.3.fl.times=0
  block.3.allocation=0
  block.3.capacity=104857600
  block.3.physical=200704
  block.4.name=vde
  block.4.path=/var/lib/libvirt/images/nbd.qcow2
  block.4.rd.reqs=45
  block.4.rd.bytes=1069056
  block.4.rd.times=146089292
  block.4.wr.reqs=0
  block.4.wr.bytes=0
  block.4.wr.times=0
  block.4.fl.reqs=0
  block.4.fl.times=0
  block.4.allocation=0
  block.4.capacity=1073741824
  block.4.physical=200704
  block.5.name=vdf
  block.5.path=/var/lib/libvirt/images/nbd-export.qcow2
  block.5.rd.reqs=42
  block.5.rd.bytes=1015808
  block.5.rd.times=45997635
  block.5.wr.reqs=0
  block.5.wr.bytes=0
  block.5.wr.times=0
  block.5.fl.reqs=0
  block.5.fl.times=0
  block.5.allocation=0
  block.5.capacity=1073741824
  block.5.physical=200704
  block.6.name=vdg
  block.6.path=/var/lib/libvirt/images/iscsi.qcow2
  block.6.rd.reqs=0
  block.6.rd.bytes=0
  block.6.rd.times=0
  block.6.wr.reqs=0
  block.6.wr.bytes=0
  block.6.wr.times=0
  block.6.fl.reqs=0
  block.6.fl.times=0
  block.6.allocation=0
  block.6.physical=196608

# virsh detach-disk V /var/lib/libvirt/images/ceph-conf.qcow2
Disk detached successfully

# virsh detach-disk V /var/lib/libvirt/images/ceph-server.qcow2
Disk detached successfully

# virsh detach-disk V /var/lib/libvirt/images/ceph-server-snap.qcow2
Disk detached successfully

# virsh detach-disk V /var/lib/libvirt/images/nbd.qcow2
Disk detached successfully

# virsh detach-disk V /var/lib/libvirt/images/nbd-export.qcow2
Disk detached successfully

# virsh detach-disk V /var/lib/libvirt/images/iscsi.qcow2
Disk detached successfully

Attach/detach works well.

Bug fixed.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2018:0704