[RFC][PATCH] blktrace: fix original blktrace

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

I'm wondering what we are going to do with the original blktrace which
is using relay and is used via ioctl.

The problem is currently it's totally broken. You can use ftrace to see
the output of blktrace, but user-space blktrace is unusable.

With this patch, both ioctl and ftrace can be used, but of course you
can't use both of them at the same time.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/trace/blktrace.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 6fb274f..d8dc48b 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -110,7 +110,7 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 	unsigned long flags;
 	char *buf;
 
-	if (blk_tr) {
+	if (blk_tracer_enabled) {
 		va_start(args, fmt);
 		ftrace_vprintk(fmt, args);
 		va_end(args);
@@ -169,7 +169,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	pid_t pid;
 	int cpu, pc = 0;
 
-	if (unlikely(bt->trace_state != Blktrace_running ||
+	if (unlikely(bt->trace_state != Blktrace_running &&
 		     !blk_tracer_enabled))
 		return;
 
@@ -185,7 +185,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		return;
 	cpu = raw_smp_processor_id();
 
-	if (blk_tr) {
+	if (blk_tracer_enabled) {
 		tracing_record_cmdline(current);
 
 		pc = preempt_count();
@@ -235,7 +235,7 @@ record_it:
 		if (pdu_len)
 			memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 
-		if (blk_tr) {
+		if (blk_tracer_enabled) {
 			trace_buffer_unlock_commit(blk_tr, event, 0, pc);
 			return;
 		}
@@ -1269,7 +1269,6 @@ static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
 	bt->dev = dev;
 	bt->act_mask = (u16)-1;
 	bt->end_lba = -1ULL;
-	bt->trace_state = Blktrace_running;
 
 	old_bt = xchg(&q->blk_trace, bt);
 	if (old_bt != NULL) {
-- 
1.5.4.rc3