[PATCH] xfs: allow disabling xfs tracepoints via Kconfig

[Rasmus Villemoes <linux@rasmusvillemoes.dk>]

linux/tracepoints.h allows individual subsystems to disable their
tracepoints. Add such a knob for xfs. Disabling XFS_TRACEPOINTS
reduces the resident size of xfs.ko by about a third, or ~350 KiB.

$ size /tmp/xfs/{a,b}/xfs.ko
   text    data     bss     dec     hex filename
 671726    4129     632  676487   a5287 /tmp/xfs/a/xfs.ko
 893192  166737     632 1060561  102ed1 /tmp/xfs/b/xfs.ko

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 fs/xfs/Kconfig     | 9 +++++++++
 fs/xfs/xfs_trace.h | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/fs/xfs/Kconfig b/fs/xfs/Kconfig
index 457ac9f97377..d099e6d9f6c5 100644
--- a/fs/xfs/Kconfig
+++ b/fs/xfs/Kconfig
@@ -141,3 +141,12 @@ config XFS_ASSERT_FATAL
 	  result in warnings.
 
 	  This behavior can be modified at runtime via sysfs.
+
+config XFS_TRACEPOINTS
+	bool "XFS tracepoints"
+	default y
+	depends on XFS_FS && TRACEPOINTS
+	help
+	  Say Y here to build XFS with tracepoints.
+
+	  You can say N here to reduce the size of the kernel image.
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 6fcc893dfc91..5fb3d5c0483e 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -6,6 +6,10 @@
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM xfs
 
+#ifndef CONFIG_XFS_TRACEPOINTS
+#define NOTRACE
+#endif
+
 #if !defined(_TRACE_XFS_H) || defined(TRACE_HEADER_MULTI_READ)
 #define _TRACE_XFS_H
 
-- 
2.20.1