smb3: add dynamic trace point for smb3_cmd_enter

Add tracepoint before sending an SMB3 command on the wire (ie add
an smb3_cmd_enter tracepoint). This allows us to look in much
more detail at response times (between request and response).
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/smb2transport.c

@@ -602,6 +602,8 @@ smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
 
 	atomic_inc(&midCount);
 	temp->mid_state = MID_REQUEST_ALLOCATED;
+	trace_smb3_cmd_enter(shdr->TreeId, shdr->SessionId,
+		le16_to_cpu(shdr->Command), temp->mid);
 	return temp;
 }
 
@@ -636,6 +638,7 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
 	spin_lock(&GlobalMid_Lock);
 	list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
 	spin_unlock(&GlobalMid_Lock);
+
 	return 0;
 }
 

fs/cifs/trace.h

@@ -275,6 +275,7 @@ DEFINE_EVENT(smb3_cmd_done_class, smb3_##name,    \
 		__u64	mid),			\
 	TP_ARGS(tid, sesid, cmd, mid))
 
+DEFINE_SMB3_CMD_DONE_EVENT(cmd_enter);
 DEFINE_SMB3_CMD_DONE_EVENT(cmd_done);
 DEFINE_SMB3_CMD_DONE_EVENT(ses_expired);