nfsd: handle seqid wraparound in nfsd4_preprocess_layout_stateid

Move the existing static function to an inline helper, and call it.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4layouts.c

@@ -289,7 +289,7 @@ nfsd4_preprocess_layout_stateid(struct svc_rqst *rqstp,
 
 		status = nfserr_bad_stateid;
 		mutex_lock(&ls->ls_mutex);
-		if (stateid->si_generation > stid->sc_stateid.si_generation)
+		if (nfsd4_stateid_generation_after(stateid, &stid->sc_stateid))
 			goto out_unlock_stid;
 		if (layout_type != ls->ls_layout_type)
 			goto out_unlock_stid;

fs/nfsd/nfs4state.c

@@ -4651,12 +4651,6 @@ grace_disallows_io(struct net *net, struct inode *inode)
 	return opens_in_grace(net) && mandatory_lock(inode);
 }
 
-/* Returns true iff a is later than b: */
-static bool stateid_generation_after(stateid_t *a, stateid_t *b)
-{
-	return (s32)(a->si_generation - b->si_generation) > 0;
-}
-
 static __be32 check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_session)
 {
 	/*
@@ -4670,7 +4664,7 @@ static __be32 check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_s
 		return nfs_ok;
 
 	/* If the client sends us a stateid from the future, it's buggy: */
-	if (stateid_generation_after(in, ref))
+	if (nfsd4_stateid_generation_after(in, ref))
 		return nfserr_bad_stateid;
 	/*
 	 * However, we could see a stateid from the past, even from a

fs/nfsd/state.h

@@ -573,6 +573,11 @@ enum nfsd4_cb_op {
 	NFSPROC4_CLNT_CB_SEQUENCE,
 };
 
+/* Returns true iff a is later than b: */
+static inline bool nfsd4_stateid_generation_after(stateid_t *a, stateid_t *b)
+{
+	return (s32)(a->si_generation - b->si_generation) > 0;
+}
 
 struct nfsd4_compound_state;
 struct nfsd_net;