nfs : add NULL check for call state in nfs3_call_state_wipe

Refcounting added for nfs call state in https://review.gluster.org/17696.
This is based on assumption that call state won't NULL when it is freed.
But currently gluster nfs server is crashing in different scenarios at
nfs3_getattr() with following bt

#0  0x00007ff1cfea9205 in _gf_ref_put (ref=ref@entry=0x0) at refcount.c:36
#1  0x00007ff1c1997455 in nfs3_call_state_wipe (cs=cs@entry=0x0) at nfs3.c:559
#2  0x00007ff1c1998931 in nfs3_getattr (req=req@entry=0x7ff1bc0b26d0, fh=fh@entry=0x7ff1c2f76ae0) at nfs3.c:962
#3  0x00007ff1c1998c8a in nfs3svc_getattr (req=0x7ff1bc0b26d0) at nfs3.c:987
#4  0x00007ff1cfbfd8c5 in rpcsvc_handle_rpc_call (svc=0x7ff1bc03e500, trans=trans@entry=0x7ff1bc0c8020, msg=<optimized out>) at rpcsvc.c:695
#5  0x00007ff1cfbfdaab in rpcsvc_notify (trans=0x7ff1bc0c8020, mydata=<optimized out>, event=<optimized out>, data=<optimized out>) at rpcsvc.c:789
#6  0x00007ff1cfbff9e3 in rpc_transport_notify (this=this@entry=0x7ff1bc0c8020, event=event@entry=RPC_TRANSPORT_MSG_RECEIVED, data=data@entry=0x7ff1bc0038d0)
    at rpc-transport.c:538
#7  0x00007ff1c4a2e3d6 in socket_event_poll_in (this=this@entry=0x7ff1bc0c8020, notify_handled=<optimized out>) at socket.c:2306
#8  0x00007ff1c4a3097c in socket_event_handler (fd=21, idx=9, gen=19, data=0x7ff1bc0c8020, poll_in=1, poll_out=0, poll_err=0) at socket.c:2458
#9  0x00007ff1cfe950f6 in event_dispatch_epoll_handler (event=0x7ff1c2f76e80, event_pool=0x5618154d5ee0) at event-epoll.c:572
#10 event_dispatch_epoll_worker (data=0x56181551cbd0) at event-epoll.c:648
#11 0x00007ff1cec99e25 in start_thread () from /lib64/libpthread.so.0
#12 0x00007ff1ce56634d in clone () from /lib64/libc.so.6

This patch add previous NULL check move from __nfs3_call_state_wipe() to nfs3_call_state_wipe()

Change-Id: I2d73632f4be23f14d8467be3d908b09b3a2d87ea
BUG: 1479030
Signed-off-by: Jiffin Tony Thottan <[email protected]>
Reviewed-on: https://review.gluster.org/17989
Smoke: Gluster Build System <[email protected]>
CentOS-regression: Gluster Build System <[email protected]>
Reviewed-by: Niels de Vos <[email protected]>

xlators/nfs/server/src/nfs3.c

@@ -538,9 +538,6 @@ typedef ssize_t (*nfs3_serializer) (struct iovec outmsg, void *args);
 static void
 __nfs3_call_state_wipe (nfs3_call_state_t *cs)
 {
-        if (!cs)
-                return;
-
         if (cs->fd) {
                 gf_msg_trace (GF_NFS3, 0, "fd 0x%lx ref: %d",
                         (long)cs->fd, cs->fd->refcount);
@@ -599,6 +596,10 @@ nfs3_call_state_init (struct nfs3_state *s, rpcsvc_request_t *req, xlator_t *v)
 void
 nfs3_call_state_wipe (nfs3_call_state_t *cs)
 {
+        if (!cs) {
+                gf_log_callingfn ("nfs", GF_LOG_WARNING, "nfs calling state NULL");
+                return;
+        }
         GF_REF_PUT (cs);
 }