Description of problem:
In virStorageBackendRBDCleanupSnapshots function, '-r' is
reported as an errno for rbd_snap_is_protected and rbd_snap_unprotect
error, but it was set only on the rbd_open call, so it doesn't correspond
to rbd_snap_is_protected and rbd_snap_unprotect error. It causes
incorrect error

src/storage/storage_backend_rbd.c

static int virStorageBackendRBDCleanupSnapshots(rados_ioctx_t ioctx,
virStoragePoolSourcePtr source,
virStorageVolDefPtr vol)

int r = 0;
int max_snaps = 128;
int snap_count, protected;
size_t i;
rbd_snap_info_t *snaps = NULL;
rbd_image_t image = NULL;

r = rbd_open(ioctx, vol->name, &image, NULL);
if (r < 0) {
virReportSystemError(-r, _("failed to open the RBD image '%s'"),
vol->name);
goto cleanup;
}

if (rbd_snap_is_protected(image, snaps[i].name, &protected)) {
virReportSystemError(-r, _("failed to verify if snapshot '%s/%s@%s' is protected"),
source->name, vol->name,
snaps[i].name);
goto cleanup;
}

if (protected == 1) {
VIR_DEBUG("Snapshot %s/%s@%s is protected needs to be "
"unprotected", source->name, vol->name,
snaps[i].name);

if (rbd_snap_unprotect(image, snaps[i].name) < 0) {
virReportSystemError(-r, _("failed to unprotect snapshot '%s/%s@%s'"),
source->name, vol->name,
snaps[i].name);
goto cleanup;
}
}

Version-Release number of selected component (if applicable):
libvirt-1.3.1-1.el7.x86_64
# git describe
v1.3.1-rc1

How reproducible:
100%

Steps to Reproduce:
1. prepare a rbd pool with source 'yy'
# virsh pool-dumpxml rbd
<pool type='rbd'>
  <name>rbd</name>
  <uuid>ebda974a-4fb7-4af2-b1a0-7a94e5cdda98</uuid>
  <capacity unit='bytes'>152820314112</capacity>
  <allocation unit='bytes'>16957992</allocation>
  <available unit='bytes'>131244736512</available>
  <source>
    <host name='10.66.111.149'/>
    <name>yy</name>
  </source>
</pool>

create a vol
# virsh vol-create-as rbd vol1 1G
Vol vol1 created

2. clone a rbd snapshot
# rbd snap create yy/vol1@sn1
# rbd snap protect yy/vol1@sn1
# rbd clone yy/vol1@sn1 rbd/vol1-clone
# rbd children yy/vol1@sn1
rbd/vol1-clone

3. prepare another rbd pool with source rbd
# virsh pool-dumpxml rbdautotest
<pool type='rbd'>
  <name>rbdautotest</name>
  <uuid>942dd90f-8258-4ffc-8563-df989406a9f5</uuid>
  <capacity unit='bytes'>152820314112</capacity>
  <allocation unit='bytes'>40</allocation>
  <available unit='bytes'>131283779584</available>
  <source>
    <host name='10.66.110.36'/>
    <name>rbd</name>
  </source>
</pool>

# virsh vol-list rbdautotest
 Name                 Path                                    
------------------------------------------------------------------------------
 vol1-clone           rbd/vol1-clone                          
 vol100               rbd/vol100

# virsh vol-delete vol1 rbd --delete-snapshots
error: Failed to delete vol vol1
error: failed to unprotect snapshot 'yy/vol1@sn1': Success

Actual result

Expected result
Set 'r' correctly

Actual results:


Expected results:


Additional info: