[PATCH] block: trace completion of all bios.

From: NeilBrown <neilb@suse.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-raid@vger.kernel.org,
	dm-devel@redhat.com, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@redhat.com>, Shaohua Li <shli@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] block: trace completion of all bios.
Date: Wed, 22 Mar 2017 13:38:09 +1100	[thread overview]
Message-ID: <877f3iave6.fsf@notabene.neil.brown.name> (raw)

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Currently only dm and md/raid5 bios trigger trace_block_bio_complete().
Now that we have bio_chain(), it is not possible, in general, for a
driver to know when the bio is really complete.  Only bio_endio()
knows that.

So move the trace_block_bio_complete() call to bio_endio().

Now trace_block_bio_complete() pairs with trace_block_bio_queue().
Any bio for which a 'queue' event is traced, will subsequently
generate a 'complete' event.

Signed-off-by: NeilBrown <neilb@suse.com>
---
 block/bio.c        | 3 +++
 drivers/md/dm.c    | 1 -
 drivers/md/raid5.c | 8 --------
 3 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 5eec5e08417f..c89d83b3ca32 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1838,6 +1838,9 @@ void bio_endio(struct bio *bio)
 		goto again;
 	}
 
+	if (bio->bi_bdev)
+		trace_block_bio_complete(bdev_get_queue(bio->bi_bdev),
+					 bio, bio->bi_error);
 	if (bio->bi_end_io)
 		bio->bi_end_io(bio);
 }
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f4ffd1eb8f44..f5f09ace690a 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -810,7 +810,6 @@ static void dec_pending(struct dm_io *io, int error)
 			queue_io(md, bio);
 		} else {
 			/* done with normal IO or empty flush */
-			trace_block_bio_complete(md->queue, bio, io_error);
 			bio->bi_error = io_error;
 			bio_endio(bio);
 		}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9a3b7da34137..f684cb566721 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5141,8 +5141,6 @@ static void raid5_align_endio(struct bio *bi)
 	rdev_dec_pending(rdev, conf->mddev);
 
 	if (!error) {
-		trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
-					 raid_bi, 0);
 		bio_endio(raid_bi);
 		if (atomic_dec_and_test(&conf->active_aligned_reads))
 			wake_up(&conf->wait_for_quiescent);
@@ -5727,10 +5725,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi)
 		md_write_end(mddev);
 	remaining = raid5_dec_bi_active_stripes(bi);
 	if (remaining == 0) {
-
-
-		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
-					 bi, 0);
 		bio_endio(bi);
 	}
 }
@@ -6138,8 +6132,6 @@ static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
 	}
 	remaining = raid5_dec_bi_active_stripes(raid_bio);
 	if (remaining == 0) {
-		trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
-					 raid_bio, 0);
 		bio_endio(raid_bio);
 	}
 	if (atomic_dec_and_test(&conf->active_aligned_reads))
-- 
2.12.0


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