nilfs2: add tracepoints for analyzing reading and writing metadata files

This patch adds tracepoints for analyzing requests of reading and writing
metadata files.  The tracepoints cover every in-place mdt files (cpfile,
sufile, and datfile).

Example of tracing mdt_insert_new_block():
              cp-14635 [000] ...1 30598.199309: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 155
              cp-14635 [000] ...1 30598.199520: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 5
              cp-14635 [000] ...1 30598.200828: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 253

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: TK Kato <TK.Kato@wdc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index dee34d9..1125f40 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -33,6 +33,7 @@
 #include "page.h"
 #include "mdt.h"
 
+#include <trace/events/nilfs2.h>
 
 #define NILFS_MDT_MAX_RA_BLOCKS		(16 - 1)
 
@@ -68,6 +69,9 @@
 	set_buffer_uptodate(bh);
 	mark_buffer_dirty(bh);
 	nilfs_mdt_mark_dirty(inode);
+
+	trace_nilfs2_mdt_insert_new_block(inode, inode->i_ino, block);
+
 	return 0;
 }
 
@@ -158,6 +162,8 @@
 	get_bh(bh);
 	submit_bh(mode, bh);
 	ret = 0;
+
+	trace_nilfs2_mdt_submit_block(inode, inode->i_ino, blkoff, mode);
  out:
 	get_bh(bh);
 	*out_bh = bh;