NLM: nlm_lookup_file() may return NLMv4-specific error codes

If the filehandle is stale, or open access is denied for some reason,
nlm_fopen() may return one of the NLMv4-specific error codes nlm4_stale_fh
or nlm4_failed. These get passed right through nlm_lookup_file(),
and so when nlmsvc_retrieve_args() calls the latter, it needs to filter
the result through the cast_status() machinery.

Failure to do so, will trigger the BUG_ON() in encode_nlm_stat...

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Reported-by: Larry McVoy <lm@bitmover.com>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/lockd/clntxdr.c b/fs/lockd/clntxdr.c
index d269ada..982d267 100644
--- a/fs/lockd/clntxdr.c
+++ b/fs/lockd/clntxdr.c
@@ -223,7 +223,7 @@
 {
 	__be32 *p;
 
-	BUG_ON(be32_to_cpu(stat) > NLM_LCK_DENIED_GRACE_PERIOD);
+	WARN_ON_ONCE(be32_to_cpu(stat) > NLM_LCK_DENIED_GRACE_PERIOD);
 	p = xdr_reserve_space(xdr, 4);
 	*p = stat;
 }
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 3009a36..21171f0 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -68,7 +68,8 @@
 
 	/* Obtain file pointer. Not used by FREE_ALL call. */
 	if (filp != NULL) {
-		if ((error = nlm_lookup_file(rqstp, &file, &lock->fh)) != 0)
+		error = cast_status(nlm_lookup_file(rqstp, &file, &lock->fh));
+		if (error != 0)
 			goto no_locks;
 		*filp = file;