[PATCH 1/3] block/block-backend: add converter from BlockAcctStats to BlockBackend

[Denis V. Lunev]

Right now BlockAcctStats is always reside on BlockBackend. This structure
is not used in any other place. Thus we are able to create a converter
from one pointer to another.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
---
 block/block-backend.c          | 5 +++++
 include/sysemu/block-backend.h | 1 +
 2 files changed, 6 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 3a13cb5f0b..88e531df98 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2153,6 +2153,11 @@ BlockAcctStats *blk_get_stats(BlockBackend *blk)
     return &blk->stats;
 }
 
+BlockBackend *blk_stats2blk(BlockAcctStats *s)
+{
+    return container_of(s, BlockBackend, stats);
+}
+
 void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
                   BlockCompletionFunc *cb, void *opaque)
 {
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 8203d7f6f9..bd4694e7bc 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -227,6 +227,7 @@ void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier 
*notify);
 void blk_io_plug(BlockBackend *blk);
 void blk_io_unplug(BlockBackend *blk);
 BlockAcctStats *blk_get_stats(BlockBackend *blk);
+BlockBackend *blk_stats2blk(BlockAcctStats *stats);
 BlockBackendRootState *blk_get_root_state(BlockBackend *blk);
 void blk_update_root_state(BlockBackend *blk);
 bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk);
-- 
2.17.1