CIFS: Fix credits calculations for reads with errors

Currently we mark MID as malformed if we get an error from server
in a read response. This leads to not properly processing credits
in the readv callback. Fix this by marking such a response as
normal received response and process it appropriately.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifssmb.c

@@ -1549,18 +1549,26 @@ cifs_discard_remaining_data(struct TCP_Server_Info *server)
 }
 
 static int
-cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+__cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid,
+		     bool malformed)
 {
 	int length;
-	struct cifs_readdata *rdata = mid->callback_data;
 
 	length = cifs_discard_remaining_data(server);
-	dequeue_mid(mid, rdata->result);
+	dequeue_mid(mid, malformed);
 	mid->resp_buf = server->smallbuf;
 	server->smallbuf = NULL;
 	return length;
 }
 
+static int
+cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+	struct cifs_readdata *rdata = mid->callback_data;
+
+	return  __cifs_readv_discard(server, mid, rdata->result);
+}
+
 int
 cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 {
@@ -1602,12 +1610,23 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 		return -1;
 	}
 
+	/* set up first two iov for signature check and to get credits */
+	rdata->iov[0].iov_base = buf;
+	rdata->iov[0].iov_len = 4;
+	rdata->iov[1].iov_base = buf + 4;
+	rdata->iov[1].iov_len = server->total_read - 4;
+	cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
+	cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[1].iov_base, rdata->iov[1].iov_len);
+
 	/* Was the SMB read successful? */
 	rdata->result = server->ops->map_error(buf, false);
 	if (rdata->result != 0) {
 		cifs_dbg(FYI, "%s: server returned error %d\n",
 			 __func__, rdata->result);
-		return cifs_readv_discard(server, mid);
+		/* normal error on read response */
+		return __cifs_readv_discard(server, mid, false);
 	}
 
 	/* Is there enough to get to the rest of the READ_RSP header? */
@@ -1651,14 +1670,6 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 		server->total_read += length;
 	}
 
-	/* set up first iov for signature check */
-	rdata->iov[0].iov_base = buf;
-	rdata->iov[0].iov_len = 4;
-	rdata->iov[1].iov_base = buf + 4;
-	rdata->iov[1].iov_len = server->total_read - 4;
-	cifs_dbg(FYI, "0: iov_base=%p iov_len=%u\n",
-		 rdata->iov[0].iov_base, server->total_read);
-
 	/* how much data is in the response? */
 #ifdef CONFIG_CIFS_SMB_DIRECT
 	use_rdma_mr = rdata->mr;