Simple debugging patch used to watch for barrier requests. I've been using
this to watch ext4's barrier=1 behavior.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
block/blk-core.c | 4 ++++
include/trace/events/block.h | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 0 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 9fe174d..fe02ea7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -36,6 +36,7 @@
EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_barrier);
static int __make_request(struct request_queue *q, struct bio *bio);
@@ -1135,6 +1136,9 @@ void init_request_from_bio(struct request *req, struct bio *bio)
if (bio_rw_flagged(bio, BIO_RW_NOIDLE))
req->cmd_flags |= REQ_NOIDLE;
+ if (req->cmd_flags & (REQ_HARDBARRIER | REQ_SOFTBARRIER))
+ trace_block_barrier(req, bio);
+
req->errors = 0;
req->__sector = bio->bi_sector;
req->ioprio = bio_prio(bio);
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index d870a91..ccf96c3 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -198,6 +198,41 @@ TRACE_EVENT(block_bio_bounce,
);
/**
+ * block_barrier - barrier operation requested
+ * @r: request that asked for the barrier
+ * @bio: block operation
+ *
+ * This tracepoint indicates that a barrier operation has been
+ * requested and a flush will be sent to the underlying block
+ * device.
+ */
+TRACE_EVENT(block_barrier,
+
+ TP_PROTO(struct request *r, struct bio *bio),
+
+ TP_ARGS(r, bio),
+
+ TP_STRUCT__entry(
+ __field( dev_t, dev )
+ __field( sector_t, sector )
+ __field( unsigned, nr_sector )
+ __field( unsigned, cmd_flags )
+ ),
+
+ TP_fast_assign(
+ __entry->dev = bio->bi_bdev->bd_dev;
+ __entry->sector = bio->bi_sector;
+ __entry->nr_sector = bio->bi_size >> 9;
+ __entry->cmd_flags = r->cmd_flags;
+ ),
+
+ TP_printk("%d:%d %llu + %u [0x%x]",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ (unsigned long long)__entry->sector,
+ __entry->nr_sector, __entry->cmd_flags)
+);
+
+/**
* block_bio_complete - completed all work on the block operation
* @q: queue holding the block operation
* @bio: block operation completed
--
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