[PATCH] block: remove the error argument to the block_bio_complete tracepoint

[PATCH] block: remove the error argument to the block_bio_complete tracepoint

[Christoph Hellwig]

The status can be trivially derived from the bio itself.  That also avoid
callers like NVMe to incorrectly pass a blk_status_t instead of the errno,
and the overhead of translating the blk_status_t to the errno in the I/O
completion fast path when no tracing is enabled.

Fixes: 35fe0d12c8a3 ("nvme: trace bio completion")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bio.c                  | 3 +--
 drivers/nvme/host/nvme.h     | 3 +--
 include/trace/events/block.h | 6 +++---
 kernel/trace/blktrace.c      | 6 +++---
 4 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 5235da6434aab..a7366c02c9b57 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1434,8 +1434,7 @@ void bio_endio(struct bio *bio)
 	}
 
 	if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
-		trace_block_bio_complete(bio->bi_disk->queue, bio,
-					 blk_status_to_errno(bio->bi_status));
+		trace_block_bio_complete(bio->bi_disk->queue, bio);
 		bio_clear_flag(bio, BIO_TRACE_COMPLETION);
 	}
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index fa5c75501049d..c0f4226d32992 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -599,8 +599,7 @@ static inline void nvme_trace_bio_complete(struct request *req,
 	struct nvme_ns *ns = req->q->queuedata;
 
 	if (req->cmd_flags & REQ_NVME_MPATH)
-		trace_block_bio_complete(ns->head->disk->queue,
-					 req->bio, status);
+		trace_block_bio_complete(ns->head->disk->queue, req->bio);
 }
 
 extern struct device_attribute dev_attr_ana_grpid;
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index 81b43f5bdf237..1257f26bb887b 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -261,9 +261,9 @@ TRACE_EVENT(block_bio_bounce,
  */
 TRACE_EVENT(block_bio_complete,
 
-	TP_PROTO(struct request_queue *q, struct bio *bio, int error),
+	TP_PROTO(struct request_queue *q, struct bio *bio),
 
-	TP_ARGS(q, bio, error),
+	TP_ARGS(q, bio),
 
 	TP_STRUCT__entry(
 		__field( dev_t,		dev		)
@@ -277,7 +277,7 @@ TRACE_EVENT(block_bio_complete,
 		__entry->dev		= bio_dev(bio);
 		__entry->sector		= bio->bi_iter.bi_sector;
 		__entry->nr_sector	= bio_sectors(bio);
-		__entry->error		= error;
+		__entry->error		= blk_status_to_errno(bio->bi_status);
 		blk_fill_rwbs(__entry->rwbs, bio->bi_opf, bio->bi_iter.bi_size);
 	),
 
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index ea47f20840870..1e5499414cdf1 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -885,10 +885,10 @@ static void blk_add_trace_bio_bounce(void *ignore,
 }
 
 static void blk_add_trace_bio_complete(void *ignore,
-				       struct request_queue *q, struct bio *bio,
-				       int error)
+				       struct request_queue *q, struct bio *bio)
 {
-	blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
+	blk_add_trace_bio(q, bio, BLK_TA_COMPLETE,
+			  blk_status_to_errno(bio->bi_status));
 }
 
 static void blk_add_trace_bio_backmerge(void *ignore,
-- 
2.26.2

Re: [PATCH] block: remove the error argument to the block_bio_complete tracepoint

[Chaitanya Kulkarni]

On 6/2/20 10:14 PM, Christoph Hellwig wrote:
> The status can be trivially derived from the bio itself.  That also avoid
> callers like NVMe to incorrectly pass a blk_status_t instead of the errno,
> and the overhead of translating the blk_status_t to the errno in the I/O
> completion fast path when no tracing is enabled.
> 
> Fixes: 35fe0d12c8a3 ("nvme: trace bio completion")
> Signed-off-by: Christoph Hellwig<hch@lst.de>

Looks good to me.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

Re: [PATCH] block: remove the error argument to the block_bio_complete tracepoint

[Sagi Grimberg]

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

Re: [PATCH] block: remove the error argument to the block_bio_complete tracepoint

[Jens Axboe]

On 6/2/20 11:14 PM, Christoph Hellwig wrote:
> The status can be trivially derived from the bio itself.  That also avoid
> callers like NVMe to incorrectly pass a blk_status_t instead of the errno,
> and the overhead of translating the blk_status_t to the errno in the I/O
> completion fast path when no tracing is enabled.

Applied, thanks.

-- 
Jens Axboe