blktrace: fix wrong calculation of RWBS

Impact: fix the output of IO type category characters

Trace categories are the upper 16 bits, not the lower 16 bits.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49C89432.8010805@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 1ffcbd4..9af4143 100644 (file)
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -922,23 +922,24 @@ static void blk_unregister_tracepoints(void)
 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
 {
        int i = 0;
+       int tc = t->action >> BLK_TC_SHIFT;
 
-       if (t->action & BLK_TC_DISCARD)
+       if (tc & BLK_TC_DISCARD)
                rwbs[i++] = 'D';
-       else if (t->action & BLK_TC_WRITE)
+       else if (tc & BLK_TC_WRITE)
                rwbs[i++] = 'W';
        else if (t->bytes)
                rwbs[i++] = 'R';
        else
                rwbs[i++] = 'N';
 
-       if (t->action & BLK_TC_AHEAD)
+       if (tc & BLK_TC_AHEAD)
                rwbs[i++] = 'A';
-       if (t->action & BLK_TC_BARRIER)
+       if (tc & BLK_TC_BARRIER)
                rwbs[i++] = 'B';
-       if (t->action & BLK_TC_SYNC)
+       if (tc & BLK_TC_SYNC)
                rwbs[i++] = 'S';
-       if (t->action & BLK_TC_META)
+       if (tc & BLK_TC_META)
                rwbs[i++] = 'M';
 
        rwbs[i] = '\0';