NFSD: Add helper for decoding locker4

[ Upstream commit 8918cc0d2b72db9997390626010b182c4500d749 ]

Refactor for clarity.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/nfsd/nfs4xdr.c

@@ -833,6 +833,48 @@ nfsd4_decode_link(struct nfsd4_compoundargs *argp, struct nfsd4_link *link)
 	return nfsd4_decode_component4(argp, &link->li_name, &link->li_namelen);
 }
 
+static __be32
+nfsd4_decode_open_to_lock_owner4(struct nfsd4_compoundargs *argp,
+				 struct nfsd4_lock *lock)
+{
+	__be32 status;
+
+	if (xdr_stream_decode_u32(argp->xdr, &lock->lk_new_open_seqid) < 0)
+		return nfserr_bad_xdr;
+	status = nfsd4_decode_stateid4(argp, &lock->lk_new_open_stateid);
+	if (status)
+		return status;
+	if (xdr_stream_decode_u32(argp->xdr, &lock->lk_new_lock_seqid) < 0)
+		return nfserr_bad_xdr;
+	return nfsd4_decode_state_owner4(argp, &lock->lk_new_clientid,
+					 &lock->lk_new_owner);
+}
+
+static __be32
+nfsd4_decode_exist_lock_owner4(struct nfsd4_compoundargs *argp,
+			       struct nfsd4_lock *lock)
+{
+	__be32 status;
+
+	status = nfsd4_decode_stateid4(argp, &lock->lk_old_lock_stateid);
+	if (status)
+		return status;
+	if (xdr_stream_decode_u32(argp->xdr, &lock->lk_old_lock_seqid) < 0)
+		return nfserr_bad_xdr;
+
+	return nfs_ok;
+}
+
+static __be32
+nfsd4_decode_locker4(struct nfsd4_compoundargs *argp, struct nfsd4_lock *lock)
+{
+	if (xdr_stream_decode_bool(argp->xdr, &lock->lk_is_new) < 0)
+		return nfserr_bad_xdr;
+	if (lock->lk_is_new)
+		return nfsd4_decode_open_to_lock_owner4(argp, lock);
+	return nfsd4_decode_exist_lock_owner4(argp, lock);
+}
+
 static __be32
 nfsd4_decode_lock(struct nfsd4_compoundargs *argp, struct nfsd4_lock *lock)
 {
@@ -848,27 +890,7 @@ nfsd4_decode_lock(struct nfsd4_compoundargs *argp, struct nfsd4_lock *lock)
 	lock->lk_reclaim = be32_to_cpup(p++);
 	p = xdr_decode_hyper(p, &lock->lk_offset);
 	p = xdr_decode_hyper(p, &lock->lk_length);
-	lock->lk_is_new = be32_to_cpup(p++);
+	status = nfsd4_decode_locker4(argp, lock);
-
-	if (lock->lk_is_new) {
-		READ_BUF(4);
-		lock->lk_new_open_seqid = be32_to_cpup(p++);
-		status = nfsd4_decode_stateid(argp, &lock->lk_new_open_stateid);
-		if (status)
-			return status;
-		READ_BUF(4);
-		lock->lk_new_lock_seqid = be32_to_cpup(p++);
-		status = nfsd4_decode_state_owner4(argp, &lock->lk_new_clientid,
-						   &lock->lk_new_owner);
-		if (status)
-			return status;
-	} else {
-		status = nfsd4_decode_stateid(argp, &lock->lk_old_lock_stateid);
-		if (status)
-			return status;
-		READ_BUF(4);
-		lock->lk_old_lock_seqid = be32_to_cpup(p++);
-	}
 
 	DECODE_TAIL;
 }

include/linux/sunrpc/xdr.h

@@ -548,6 +548,27 @@ static inline bool xdr_item_is_present(const __be32 *p)
 	return *p != xdr_zero;
 }
 
+/**
+ * xdr_stream_decode_bool - Decode a boolean
+ * @xdr: pointer to xdr_stream
+ * @ptr: pointer to a u32 in which to store the result
+ *
+ * Return values:
+ *   %0 on success
+ *   %-EBADMSG on XDR buffer overflow
+ */
+static inline ssize_t
+xdr_stream_decode_bool(struct xdr_stream *xdr, __u32 *ptr)
+{
+	const size_t count = sizeof(*ptr);
+	__be32 *p = xdr_inline_decode(xdr, count);
+
+	if (unlikely(!p))
+		return -EBADMSG;
+	*ptr = (*p != xdr_zero);
+	return 0;
+}
+
 /**
  * xdr_stream_decode_u32 - Decode a 32-bit integer
  * @xdr: pointer to xdr_stream