Re: [Qemu-devel] [PATCH v6 0/8] Implement reference count for BlockDriverState

[Stefan Hajnoczi]

On Fri, Aug 23, 2013 at 09:14:43AM +0800, Fam Zheng wrote:
> BlockDriverState lifecycle management is needed by future features such as
> image fleecing and blockdev-add. This series adds reference count to
> BlockDriverState.
> 
> The first two patches clean up two odd BlockDriverState use cases, so all code
> uses bdrv_new() to create BlockDriverState instance.
> 
> Then implemented bdrv_ref() and bdrv_unref() to operate on refcnt: Initially,
> refcnt is 1, which means bdrv_unref is effectively a bdrv_delete() here. So
> patch 04 has a search and replace to convert bdrv_delete to bdrv_unref, before
> bdrv_ref is used anywhere. 05~08 patches calls bdrv_ref for device attach,
> block-migration and nbd.
> 
> The rule is: Either bdrv_ref() or bdrv_new() must have a matching
> bdrv_unref() call, and the last matching bdrv_unref deletes the bs.
> 
> v6:
>     08: Use BH to release reference, this fixes the iotest.
> 
> v5: resend v4 to a right list.
> 
> v4:
>     08: Added, let block job use BDS reference.
>     02: Fix leak of bs.opaque
> 
> v3:
>     03: Removed unnecessary bdrv_close() call.
> 
> v2:
>     05: Removed: "block: use BlockDriverState refcnt for device attach/detach"
>     07: Fix xen_disk blk_disconnect() as it depended on device attach refcnt.
> 
> 
> Fam Zheng (8):
>   vvfat: use bdrv_new() to allocate BlockDriverState
>   iscsi: use bdrv_new() instead of stack structure
>   block: implement reference count for BlockDriverState
>   block: make bdrv_delete() static
>   migration: omit drive ref as we have bdrv_ref now
>   xen_disk: simplify blk_disconnect with refcnt
>   nbd: use BlockDriverState refcnt
>   block: use BDS ref for block jobs
> 
>  block-migration.c         |  4 +--
>  block.c                   | 44 ++++++++++++++++++++++++---------
>  block/backup.c            |  2 +-
>  block/blkverify.c         |  4 +--
>  block/cow.c               |  2 +-
>  block/iscsi.c             | 16 ++++++------
>  block/mirror.c            |  2 +-
>  block/qcow.c              |  2 +-
>  block/qcow2.c             |  2 +-
>  block/qed.c               |  2 +-
>  block/sheepdog.c          |  6 ++---
>  block/snapshot.c          |  2 +-
>  block/stream.c            |  2 +-
>  block/vmdk.c              | 10 ++++----
>  block/vvfat.c             |  6 ++---
>  blockdev-nbd.c            | 10 +-------
>  blockdev.c                | 63 
> +++++++++++++++++------------------------------
>  blockjob.c                |  1 +
>  hw/block/xen_disk.c       | 13 +++++-----
>  include/block/block.h     |  3 ++-
>  include/block/block_int.h |  1 +
>  nbd.c                     |  5 ++++
>  qemu-img.c                | 26 +++++++++----------
>  qemu-io.c                 |  6 ++---
>  24 files changed, 119 insertions(+), 115 deletions(-)
> 
> -- 
> 1.8.3.1
> 
> 

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan