Bug 1612904

+++ This bug is a downstream clone. The original bug is: +++
+++   bug 1560460 +++
======================================================================

Description of problem:
NetApp snapshots feature may include symbolic links to NFS share which points to the same directory. This causes getFileStats to fail.

Example:
/rhev/data-center/mnt/<mountPoint>/.snapshot/daily.2018-02-20_0010 -> /rhev/data-center/mnt/<mountPoint>/<SD_UUID>/images/11111111-1111-1111-1111-111111111111/

Version-Release number of selected component (if applicable):
   python-ioprocess-0.16.1-1.el7ev.noarch
   ioprocess-0.16.1-1.el7ev.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Go to NFS ISO domain and create a recursive symbolic link.

     # pwd
       /rhev/data-center/mnt/10.34.1.195:_exports_rheviso01/c217bcfa-ffba-4982-b2c3-4ed418a0cd1d/images/11111111-1111-1111-1111-111111111111
     # ln -s ../ testLink

2. Try to get the list of isos in the WebAdmin


Actual results:
2018-03-26 10:08:03,596+0200 ERROR (jsonrpc/6) [storage.TaskManager.Task] (Task='70ba66b9-dd38-4042-9baa
-d390a8c44305') Unexpected error (task:872)
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/task.py", line 879, in _run
    return fn(*args, **kargs)
  File "<string>", line 2, in getFileStats
  File "/usr/lib/python2.7/site-packages/vdsm/common/api.py", line 48, in method
    ret = func(*args, **kwargs)
  File "/usr/share/vdsm/storage/hsm.py", line 2305, in getFileStats
    caseSensitive=caseSensitive)
  File "/usr/share/vdsm/storage/fileSD.py", line 496, in getFileList
    filesList = self.oop.simpleWalk(basedir)
  File "/usr/lib/python2.7/site-packages/vdsm/storage/outOfProcess.py", line 351, in simpleWalk
    files.extend(simpleWalk(ioproc, fullpath))
  File "/usr/lib/python2.7/site-packages/vdsm/storage/outOfProcess.py", line 351, in simpleWalk
    files.extend(simpleWalk(ioproc, fullpath))
  File "/usr/lib/python2.7/site-packages/vdsm/storage/outOfProcess.py", line 351, in simpleWalk
    files.extend(simpleWalk(ioproc, fullpath))
....
  File "/usr/lib/python2.7/site-packages/vdsm/storage/outOfProcess.py", line 255, in isdir
    res = self._iop.stat(path)
  File "/usr/lib/python2.7/site-packages/ioprocess/__init__.py", line 484, in stat
    resdict = self._sendCommand("stat", {"path": path}, self.timeout)
  File "/usr/lib/python2.7/site-packages/ioprocess/__init__.py", line 461, in _sendCommand
    raise OSError(errcode, errstr)
OSError: [Errno 40] Too many levels of symbolic links
....
2018-03-26 10:08:03,600+0200 ERROR (jsonrpc/6) [storage.Dispatcher] FINISH getFileStats error=[Errno 40]
 Too many levels of symbolic links (dispatcher:85)
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/dispatcher.py", line 72, in wrapper
    result = ctask.prepare(func, *args, **kwargs)
  File "/usr/share/vdsm/storage/task.py", line 105, in wrapper
    return m(self, *a, **kw)
  File "/usr/share/vdsm/storage/task.py", line 1185, in prepare
    raise self.error
OSError: [Errno 40] Too many levels of symbolic links

Expected results:
The symbolic link is skipped.

Additional info:
ioprocess tries to skip the symlinks:

def simpleWalk(ioproc, path):
    files = []
    for f in ioproc.listdir(path):
        fullpath = os.path.join(path, f)
        osPath = _IOProcessOs(ioproc).path
        if osPath.isdir(fullpath) and not osPath.islink(fullpath):
            files.extend(simpleWalk(ioproc, fullpath))
        else:
            files.append(fullpath)

    return files

The problem is that the islink function uses "stat" function from ioprocess c library which does use a stat from sys/stat.h which returns information about the target not about the link itself. So lstat function should be used instead.

(Originally by Roman Hodain)