block: Add nr_bios to block_rq_remap tracepoint
Adding the number of bios in a remapped request to 'block_rq_remap'
tracepoint.
Request remapper clones bios in a request to track the completion
status of each bio. So the number of bios can be useful information
for investigation.
Related discussions:
http://www.redhat.com/archives/dm-devel/2013-August/msg00084.html
http://www.redhat.com/archives/dm-devel/2013-September/msg00024.html
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 2fdb4a4..0e6f765 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -862,6 +862,17 @@
return blk_queue_get_max_sectors(q, rq->cmd_flags);
}
+static inline unsigned int blk_rq_count_bios(struct request *rq)
+{
+ unsigned int nr_bios = 0;
+ struct bio *bio;
+
+ __rq_for_each_bio(bio, rq)
+ nr_bios++;
+
+ return nr_bios;
+}
+
/*
* Request issue related functions.
*/