[PATCH v2 7/7] blktrace: support filtering of BLK_TN_MESSAGE

[Li Zefan <lizf@cn.fujitsu.com>]

I found large bunk of the output of blktrace are BLK_TN_MESSAGE events:

 % blktrace -d /dev/sda -o - | blkparse -i - -o ~/blk.log
 (after some seconds)
 % cat ~/blk.log | wc -l
 69041
 % cat ~/blk.log | grep "m   N" | wc -l
 38232

It will be useful to be able to filter those events.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/trace/blktrace.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 947c5b3..dcabe59 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -131,6 +131,9 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 		     !blk_tracer_enabled))
 		return;
 
+	if (!(bt->act_mask & BLK_TC_NOTIFY))
+		return;
+
 	local_irq_save(flags);
 	buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 	va_start(args, fmt);
@@ -1366,6 +1369,7 @@ static const struct {
 	{ BLK_TC_COMPLETE,	"complete"	},
 	{ BLK_TC_FS,		"fs"		},
 	{ BLK_TC_PC,		"pc"		},
+	{ BLK_TC_NOTIFY,	"notify"	},
 	{ BLK_TC_AHEAD,		"ahead"		},
 	{ BLK_TC_META,		"meta"		},
 	{ BLK_TC_DISCARD,	"discard"	},
-- 
1.5.4.rc3