[PATCH 01/11] iomap: add tracing for the readpage / readpages

[Christoph Hellwig]

Lift the xfs code for tracing address space operations to the iomap
layer.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/iomap/buffered-io.c       |  7 +++++++
 include/trace/events/iomap.h | 27 +++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/trace/events/iomap.h

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e25901ae3ff4..099daf0c09b8 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -19,6 +19,9 @@
 
 #include "../internal.h"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/iomap.h>
+
 static struct iomap_page *
 iomap_page_create(struct inode *inode, struct page *page)
 {
@@ -293,6 +296,8 @@ iomap_readpage(struct page *page, const struct iomap_ops *ops)
 	unsigned poff;
 	loff_t ret;
 
+	trace_iomap_readpage(page->mapping->host, 1);
+
 	for (poff = 0; poff < PAGE_SIZE; poff += ret) {
 		ret = iomap_apply(inode, page_offset(page) + poff,
 				PAGE_SIZE - poff, 0, ops, &ctx,
@@ -389,6 +394,8 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages,
 	loff_t last = page_offset(list_entry(pages->next, struct page, lru));
 	loff_t length = last - pos + PAGE_SIZE, ret = 0;
 
+	trace_iomap_readpages(mapping->host, nr_pages);
+
 	while (length > 0) {
 		ret = iomap_apply(mapping->host, pos, length, 0, ops,
 				&ctx, iomap_readpages_actor);
diff --git a/include/trace/events/iomap.h b/include/trace/events/iomap.h
new file mode 100644
index 000000000000..7d2fe2c773f3
--- /dev/null
+++ b/include/trace/events/iomap.h
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2009-2019, Christoph Hellwig
+ * All Rights Reserved.
+ *
+ * NOTE: none of these tracepoints shall be consider a stable kernel ABI
+ * as they can change at any time.
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM iomap
+
+#if !defined(_TRACE_IOMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_IOMAP_H
+
+#include <linux/tracepoint.h>
+
+#define DEFINE_READPAGE_EVENT(name)		\
+DEFINE_EVENT(iomap_readpage_class, name,	\
+	TP_PROTO(struct inode *inode, int nr_pages), \
+	TP_ARGS(inode, nr_pages))
+DEFINE_READPAGE_EVENT(iomap_readpage);
+DEFINE_READPAGE_EVENT(iomap_readpages);
+
+#endif /* _TRACE_IOMAP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
2.20.1