cifs: prepare SMB2_Flush to be usable in compounds

Create smb2_flush_init() and smb2_flush_free() so we can use the flush command
in compounds.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/smb2pdu.c

@@ -3287,44 +3287,64 @@ SMB2_echo(struct TCP_Server_Info *server)
 	return rc;
 }
 
+void
+SMB2_flush_free(struct smb_rqst *rqst)
+{
+	if (rqst && rqst->rq_iov)
+		cifs_small_buf_release(rqst->rq_iov[0].iov_base); /* request */
+}
+
 int
-SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
-	   u64 volatile_fid)
+SMB2_flush_init(const unsigned int xid, struct smb_rqst *rqst,
+		struct cifs_tcon *tcon, u64 persistent_fid, u64 volatile_fid)
 {
-	struct smb_rqst rqst;
 	struct smb2_flush_req *req;
-	struct cifs_ses *ses = tcon->ses;
-	struct kvec iov[1];
-	struct kvec rsp_iov;
-	int resp_buftype;
-	int rc = 0;
-	int flags = 0;
+	struct kvec *iov = rqst->rq_iov;
 	unsigned int total_len;
-
-	cifs_dbg(FYI, "Flush\n");
-
-	if (!ses || !(ses->server))
-		return -EIO;
+	int rc;
 
 	rc = smb2_plain_req_init(SMB2_FLUSH, tcon, (void **) &req, &total_len);
 	if (rc)
 		return rc;
 
-	if (smb3_encryption_required(tcon))
-		flags |= CIFS_TRANSFORM_REQ;
-
 	req->PersistentFileId = persistent_fid;
 	req->VolatileFileId = volatile_fid;
 
 	iov[0].iov_base = (char *)req;
 	iov[0].iov_len = total_len;
 
+	return 0;
+}
+
+int
+SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
+	   u64 volatile_fid)
+{
+	struct cifs_ses *ses = tcon->ses;
+	struct smb_rqst rqst;
+	struct kvec iov[1];
+	struct kvec rsp_iov = {NULL, 0};
+	int resp_buftype = CIFS_NO_BUFFER;
+	int flags = 0;
+	int rc = 0;
+
+	cifs_dbg(FYI, "flush\n");
+	if (!ses || !(ses->server))
+		return -EIO;
+
+	if (smb3_encryption_required(tcon))
+		flags |= CIFS_TRANSFORM_REQ;
+
 	memset(&rqst, 0, sizeof(struct smb_rqst));
+	memset(&iov, 0, sizeof(iov));
 	rqst.rq_iov = iov;
 	rqst.rq_nvec = 1;
 
+	rc = SMB2_flush_init(xid, &rqst, tcon, persistent_fid, volatile_fid);
+	if (rc)
+		goto flush_exit;
+
 	rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
-	cifs_small_buf_release(req);
 
 	if (rc != 0) {
 		cifs_stats_fail_inc(tcon, SMB2_FLUSH_HE);
@@ -3332,6 +3352,8 @@ SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
 				     rc);
 	}
 
+ flush_exit:
+	SMB2_flush_free(&rqst);
 	free_rsp_buf(resp_buftype, rsp_iov.iov_base);
 	return rc;
 }

fs/cifs/smb2proto.h

@@ -158,6 +158,10 @@ extern int SMB2_close_init(struct cifs_tcon *tcon, struct smb_rqst *rqst,
 extern void SMB2_close_free(struct smb_rqst *rqst);
 extern int SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon,
 		      u64 persistent_file_id, u64 volatile_file_id);
+extern int SMB2_flush_init(const unsigned int xid, struct smb_rqst *rqst,
+			   struct cifs_tcon *tcon,
+			   u64 persistent_file_id, u64 volatile_file_id);
+extern void SMB2_flush_free(struct smb_rqst *rqst);
 extern int SMB2_query_info(const unsigned int xid, struct cifs_tcon *tcon,
 			   u64 persistent_file_id, u64 volatile_file_id,
 			   struct smb2_file_all_info *data);