Description of problem:
On POSIXFS storage domain creation, if nothing is given after '/' in the path, the '/' is ignored in the mount command that vdsm executes. 
For example, the following path, which has nothing after '/' is executed on vdsm without the '/':

Path = 10.35.65.18:/

VFS Type = ceph


jsonrpc.Executor/3::DEBUG::2016-01-26 17:51:04,338::mount::229::Storage.Misc.excCmd::(_runcmd) /usr/bin/taskset --cpu-list 0-1 /usr/bin/sudo -n /usr/bin/mount -t ceph -o name=ad
min,secret=AQC3W1dWhplVLBAARW/zKtQzjafZDKAGfVpWbQ== 10.35.65.18: /rhev/data-center/mnt/10.35.65.18:___ (cwd None)


This is mainly relevant for cephfs.


Version-Release number of selected component (if applicable):
vdsm-4.17.19-0.el7ev.noarch

How reproducible:
Always

Steps to Reproduce:
1. Try to create a POSIXFS with path that has nothing after '/'
For example:
Path = 10.35.65.18:/


Actual results:
mount command on vdsm is executed without the '/'

Expected results:
vdsm should execute the mount command with the exact syntax provided in the path.


Additional info:

The following syntax works while mounting manually from host:

# mount -t ceph ceph-1.qa.lab:6789:/ /mnt/cephfs/ -o name=admin,secret=<key>

(The key is not hidden in the actual mount command).

Tried to use this way for ceph based POSIX storage domain creation as follows:

=======================================
Path = 10.35.65.18:/

VFS Type = ceph

Mount Options = name=admin,secret=<key>
=======================================

The failure in vdsm.log:

jsonrpc.Executor/3::ERROR::2016-01-26 17:51:04,372::hsm::2473::Storage.HSM::(connectStorageServer) Could not connect to storageServer
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/hsm.py", line 2470, in connectStorageServer
    conObj.connect()
  File "/usr/share/vdsm/storage/storageServer.py", line 234, in connect
    six.reraise(t, v, tb)
  File "/usr/share/vdsm/storage/storageServer.py", line 226, in connect
    self._mount.mount(self.options, self._vfsType, cgroup=self.CGROUP)
  File "/usr/share/vdsm/storage/mount.py", line 225, in mount
    return self._runcmd(cmd, timeout)
  File "/usr/share/vdsm/storage/mount.py", line 241, in _runcmd
    raise MountError(rc, ";".join((out, err)))
MountError: (1, 'source mount path was not specified\nfailed to resolve source\n;')



Seems that no matter how many '/' are given, vdsm ignores all if there is nothing after them. (I tried a path with '//' at the end, didn't work.)

This has to be fixed for ceph fs to work as a VFS type for POSIXFS compliant storage domain creation.