GFS2: fix potential NULL pointer dereference
GFS2: fix potential NULL pointer dereference

Commit [e66cf1610: GFS2: Use lockref for glocks] replaced call:
    atomic_read(&gi->gl->gl_ref) == 0
with:
    __lockref_is_dead(&gl->gl_lockref)
therefore changing how gl is accessed, from gi->gl to plan gl.
However, gl can be a NULL pointer, and so gi->gl needs to be
used instead (which is guaranteed not to be NULL because fo
the while loop checking that condition).

Signed-off-by: Michal Nazarewicz <605208d9b4c769ca62e9f9f8b592c9cd465fe6d7@mina86.com>
Signed-off-by: Steven Whitehouse <9801c4ef11586b619a1c43ac9377eea2aee672dd@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs