[PATCH -next RESEND] tracing: fix iomap.h build warnings

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Fix 30 warnings for missing "struct inode" declaration (like these) by
adding a forward reference for it.
These warnings come from 'headers_check' (CONFIG_HEADERS_CHECK):
  CC      include/trace/events/iomap.h.s

./../include/trace/events/iomap.h:49:18: warning: 'struct inode' declared inside parameter list will not be visible outside of this definition or declaration
./../include/trace/events/iomap.h:77:18: warning: 'struct inode' declared inside parameter list will not be visible outside of this definition or declaration

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
Resend to correct maintainer(s).

 include/trace/events/iomap.h |    2 ++
 1 file changed, 2 insertions(+)

--- linux-next-20190829.orig/include/trace/events/iomap.h
+++ linux-next-20190829/include/trace/events/iomap.h
@@ -44,6 +44,8 @@ DECLARE_EVENT_CLASS(iomap_page_class,
 		  __entry->length)
 )
 
+struct inode;
+
 #define DEFINE_PAGE_EVENT(name)		\
 DEFINE_EVENT(iomap_page_class, name,	\
 	TP_PROTO(struct inode *inode, struct page *page, unsigned long off, \