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authorTejun Heo <tj@kernel.org>2013-01-11 13:06:33 -0800
committerJens Axboe <axboe@kernel.dk>2013-01-14 15:00:36 +0100
commit3a366e614d0837d9fc23f78cdb1a1186ebc3387f (patch)
tree5be6ec716687234ac1e6202db62c84ee1d2246be /kernel/trace/blktrace.c
parentac9a19745196388ae5d828c0be7a1d6e472101f3 (diff)
block: add missing block_bio_complete() tracepoint
bio completion didn't kick block_bio_complete TP. Only dm was explicitly triggering the TP on IO completion. This makes block_bio_complete TP useless for tracers which want to know about bios, and all other bio based drivers skip generating blktrace completion events. This patch makes all bio completions via bio_endio() generate block_bio_complete TP. * Explicit trace_block_bio_complete() invocation removed from dm and the trace point is unexported. * @rq dropped from trace_block_bio_complete(). bios may fly around w/o queue associated. Verifying and accessing the assocaited queue belongs to TP probes. * blktrace now gets both request and bio completions. Make it ignore bio completions if request completion path is happening. This makes all bio based drivers generate blktrace completion events properly and makes the block_bio_complete TP actually useful. v2: With this change, block_bio_complete TP could be invoked on sg commands which have bio's with %NULL bi_bdev. Update TP assignment code to check whether bio->bi_bdev is %NULL before dereferencing. Signed-off-by: Tejun Heo <tj@kernel.org> Original-patch-by: Namhyung Kim <namhyung@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alasdair Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Cc: Neil Brown <neilb@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'kernel/trace/blktrace.c')
-rw-r--r--kernel/trace/blktrace.c26
1 files changed, 23 insertions, 3 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index c0bd0308741c..190d98fbed27 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -739,6 +739,12 @@ static void blk_add_trace_rq_complete(void *ignore,
struct request_queue *q,
struct request *rq)
{
+ struct blk_trace *bt = q->blk_trace;
+
+ /* if control ever passes through here, it's a request based driver */
+ if (unlikely(bt && !bt->rq_based))
+ bt->rq_based = true;
+
blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
}
@@ -774,10 +780,24 @@ static void blk_add_trace_bio_bounce(void *ignore,
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)
+static void blk_add_trace_bio_complete(void *ignore, struct bio *bio, int error)
{
+ struct request_queue *q;
+ struct blk_trace *bt;
+
+ if (!bio->bi_bdev)
+ return;
+
+ q = bdev_get_queue(bio->bi_bdev);
+ bt = q->blk_trace;
+
+ /*
+ * Request based drivers will generate both rq and bio completions.
+ * Ignore bio ones.
+ */
+ if (likely(!bt) || bt->rq_based)
+ return;
+
blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
}