fs.h: Add TRACE_IOCB_STRINGS for use in trace points

Add TRACE_IOCB_STRINGS macro which can be used in the trace point patch to
print different flag values with meaningful string output.
Tested-by: Disha Goel <disgoel@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: line up strings all prettylike]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

include/linux/fs.h

@@ -340,6 +340,20 @@ enum rw_hint {
 /* can use bio alloc cache */
 #define IOCB_ALLOC_CACHE	(1 << 21)
 
+/* for use in trace events */
+#define TRACE_IOCB_STRINGS \
+	{ IOCB_HIPRI,		"HIPRI" }, \
+	{ IOCB_DSYNC,		"DSYNC" }, \
+	{ IOCB_SYNC,		"SYNC" }, \
+	{ IOCB_NOWAIT,		"NOWAIT" }, \
+	{ IOCB_APPEND,		"APPEND" }, \
+	{ IOCB_EVENTFD,		"EVENTFD"}, \
+	{ IOCB_DIRECT,		"DIRECT" }, \
+	{ IOCB_WRITE,		"WRITE" }, \
+	{ IOCB_WAITQ,		"WAITQ" }, \
+	{ IOCB_NOIO,		"NOIO" }, \
+	{ IOCB_ALLOC_CACHE,	"ALLOC_CACHE" }
+
 struct kiocb {
 	struct file		*ki_filp;
 	loff_t			ki_pos;