Fix remap handling by blktrace

This patch provides more information concerning REMAP operations on block
IOs. The additional information provides clearer details at the user level,
and supports post-processing analysis in btt.

o  Adds in partition remaps on the same device.
o  Fixed up the remap information in DM to be in the right order
o  Sent up mapped-from and mapped-to device information

Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 8c2caff87cc3..a15845c164f2 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3047,6 +3047,10 @@ static inline void blk_partition_remap(struct bio *bio)
 
                 bio->bi_sector += p->start_sect;
                 bio->bi_bdev = bdev->bd_contains;
+
+                blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio,
+                                    bdev->bd_dev, bio->bi_sector,
+                                    bio->bi_sector - p->start_sect);
         }
 }