scoutfs: add tracepoint support with bloom example

Add the intrastucture for tracepoints.  We include an example user that
traces bloom filter hits and misses.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/Makefile

@@ -1,4 +1,6 @@
 obj-$(CONFIG_SCOUTFS_FS) := scoutfs.o
+
+CFLAGS_scoutfs_trace.o = -I$(src) # define_trace.h double include
  
 scoutfs-y += block.o bloom.o chunk.o crc.o dir.o filerw.o inode.o manifest.o \
-	     msg.o ring.o segment.o skip.o super.o
+	     msg.o ring.o scoutfs_trace.o segment.o skip.o super.o

kmod/src/bloom.c

@@ -20,6 +20,7 @@
 #include "format.h"
 #include "block.h"
 #include "bloom.h"
+#include "scoutfs_trace.h"
 
 /*
  * Each log segment starts with a bloom filters that spans multiple
@@ -100,6 +101,7 @@ int scoutfs_set_bloom_bits(struct super_block *sb, u64 blkno,
  * might, and -errno if IO fails.
  */
 int scoutfs_test_bloom_bits(struct super_block *sb, u64 blkno,
+			    struct scoutfs_key *key,
 			    struct scoutfs_bloom_bits *bits)
 {
 	struct scoutfs_bloom_block *blm;
@@ -121,5 +123,10 @@ int scoutfs_test_bloom_bits(struct super_block *sb, u64 blkno,
 			break;
 	}
 
+	if (ret)
+		trace_scoutfs_bloom_hit(key);
+	else
+		trace_scoutfs_bloom_miss(key);
+
 	return ret;
 }

kmod/src/bloom.h

@@ -9,6 +9,7 @@ struct scoutfs_bloom_bits {
 void scoutfs_calc_bloom_bits(struct scoutfs_bloom_bits *bits,
 			     struct scoutfs_key *key, __le32 *salts);
 int scoutfs_test_bloom_bits(struct super_block *sb, u64 blkno,
+			    struct scoutfs_key *key,
 			    struct scoutfs_bloom_bits *bits);
 int scoutfs_set_bloom_bits(struct super_block *sb, u64 blkno,
 			   struct scoutfs_bloom_bits *bits);

kmod/src/scoutfs_trace.c

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2016 Versity Software, Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/magic.h>
+#include <linux/buffer_head.h>
+#include <linux/random.h>
+
+#include "super.h"
+#include "format.h"
+#include "inode.h"
+#include "dir.h"
+#include "msg.h"
+#include "block.h"
+#include "manifest.h"
+#include "ring.h"
+#include "segment.h"
+
+#define CREATE_TRACE_POINTS
+#include "scoutfs_trace.h"

kmod/src/scoutfs_trace.h

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2016 Versity Software, Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+/*
+ * This has a crazy name because it's in an external module build at
+ * the moment.  When it's merged upstream it'll move to
+ * include/trace/events/scoutfs.h
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM scoutfs
+
+#if !defined(_TRACE_SCOUTFS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SCOUTFS_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(scoutfs_bloom_hit,
+	TP_PROTO(struct scoutfs_key *key),
+
+	TP_ARGS(key),
+
+	TP_STRUCT__entry(
+		__field(__u64, inode)
+		__field(__u8, type)
+		__field(__u64, offset)
+	),
+
+	TP_fast_assign(
+		__entry->inode = le64_to_cpu(key->inode);
+		__entry->type = key->type;
+		__entry->offset = le64_to_cpu(key->offset);
+	),
+
+	TP_printk("key %llu.%u.%llu",
+		  __entry->inode, __entry->type, __entry->offset)
+);
+
+TRACE_EVENT(scoutfs_bloom_miss,
+	TP_PROTO(struct scoutfs_key *key),
+
+	TP_ARGS(key),
+
+	TP_STRUCT__entry(
+		__field(__u64, inode)
+		__field(__u8, type)
+		__field(__u64, offset)
+	),
+
+	TP_fast_assign(
+		__entry->inode = le64_to_cpu(key->inode);
+		__entry->type = key->type;
+		__entry->offset = le64_to_cpu(key->offset);
+	),
+
+	TP_printk("key %llu.%u.%llu",
+		  __entry->inode, __entry->type, __entry->offset)
+);
+
+
+#endif /* _TRACE_SCOUTFS_H */
+
+/* This part must be outside protection */
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE scoutfs_trace
+#include <trace/define_trace.h>

kmod/src/segment.c

@@ -146,7 +146,7 @@ int scoutfs_read_item(struct super_block *sb, struct scoutfs_key *key,
 		/* XXX read-ahead all bloom blocks */
 
 		ret = scoutfs_test_bloom_bits(sb, le64_to_cpu(ment.blkno),
-					      &bits);
+					      key, &bits);
 		if (ret < 0)
 			break;
 		if (!ret) {