Re: [PATCH] blktrace: add missing probe argument to block_bio_complete

Jens Axboe
2011-01-07T15:15:52Z

On 2011-01-07 15:13, Jeff Moyer wrote:
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:
>
>> blktrace.c block bio complete callback needs to gain a new argument to reflect
>> the newly added "error" tracepoint argument. This is needed to match the new
>> block_bio_complete TRACE_EVENT as of
>> commit de983a7bfcb7c020901ca6e2314cf55a4207ab5a.
>>
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
>> CC: Jeff Moyer <jmoyer@redhat.com>
>> CC: Steven Rostedt <rostedt@goodmis.org>
>> CC: Frederic Weisbecker <fweisbec@gmail.com>
>> CC: Ingo Molnar <mingo@elte.hu>
>> CC: Thomas Gleixner <tglx@linutronix.de>
>> CC: Jens Axboe <axboe@kernel.dk>
>> CC: Li Zefan <lizf@cn.fujitsu.com>
>> ---
>> kernel/trace/blktrace.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> Index: linux-2.6-lttng/kernel/trace/blktrace.c
>> ===================================================================
>> --- linux-2.6-lttng.orig/kernel/trace/blktrace.c
>> +++ linux-2.6-lttng/kernel/trace/blktrace.c
>> @@ -785,7 +785,8 @@ static void blk_add_trace_bio_bounce(voi
>> }
>>
>> static void blk_add_trace_bio_complete(void *ignore,
>> - struct request_queue *q, struct bio *bio)
>> + struct request_queue *q, struct bio *bio,
>> + int error)
>> {
>> blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
>> }
>
> OK, I clearly didn't look closely enough last time. There's no sense
> passing this information down if it isn't used (as you said initially).
> blk_add_trace_bio sets the error based on whether or not the
> BIO_UPTODATE bit is set. So, I think we should instead revert the patch
> I sent you (Mathieu), and then completely get rid of the error field in
> the TP macros.
>
> Does that make sense to everyone else?

We usually use BIO_UPTODATE if we have no other information available.
So if we have, then we should use it.

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index fab31af..153562d 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -758,54 +758,58 @@ static void blk_add_trace_rq_complete(void *ignore,
* @q: queue the io is for
* @bio: the source bio
* @what: the action
+ * @error: error, if any
*
* Description:
* Records an action against a bio. Will log the bio offset + size.
*
**/
static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
- u32 what)
+ u32 what, int error)
{
struct blk_trace *bt = q->blk_trace;

if (likely(!bt))
return;

+ if (!error && !bio_flagged(bio, BIO_UPTODATE))
+ error = EIO;
+
__blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
- !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
+ error, 0, NULL);
}

static void blk_add_trace_bio_bounce(void *ignore,
struct request_queue *q, struct bio *bio)
{
- blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
+ blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
}

static void blk_add_trace_bio_complete(void *ignore,
struct request_queue *q, struct bio *bio,
int error)
{
- blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
+ blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
}

static void blk_add_trace_bio_backmerge(void *ignore,
struct request_queue *q,
struct bio *bio)
{
- blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
+ blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
}

static void blk_add_trace_bio_frontmerge(void *ignore,
struct request_queue *q,
struct bio *bio)
{
- blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
+ blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
}

static void blk_add_trace_bio_queue(void *ignore,
struct request_queue *q, struct bio *bio)
{
- blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
+ blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
}

static void blk_add_trace_getrq(void *ignore,
@@ -813,7 +817,7 @@ static void blk_add_trace_getrq(void *ignore,
struct bio *bio, int rw)
{
if (bio)
- blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
+ blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
else {
struct blk_trace *bt = q->blk_trace;

@@ -828,7 +832,7 @@ static void blk_add_trace_sleeprq(void *ignore,
struct bio *bio, int rw)
{
if (bio)
- blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
+ blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
else {
struct blk_trace *bt = q->blk_trace;

--
Jens Axboe