[v8,03/16] block: Add BB-BDS remove/insert notifiers

bdrv_close() no longer signifies ejection of a medium, this is now done
by removing the BDS from the BB. Therefore, we want to have a notifier
for that in the BB instead of a close notifier in the BDS. The former is
added now, the latter is removed later.

Symmetrically, another notifier list is added that is invoked whenever a
BDS is inserted. We will need that for virtio-blk and virtio-scsi, which
can then remove their op blockers on BDS ejection and set them up on
insertion.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 block/block-backend.c          | 20 ++++++++++++++++++++
 include/sysemu/block-backend.h |  2 ++
 2 files changed, 22 insertions(+)

On Wed, 01/27 18:59, Max Reitz wrote:
> bdrv_close() no longer signifies ejection of a medium, this is now done
> by removing the BDS from the BB. Therefore, we want to have a notifier
> for that in the BB instead of a close notifier in the BDS. The former is
> added now, the latter is removed later.
> 
> Symmetrically, another notifier list is added that is invoked whenever a
> BDS is inserted. We will need that for virtio-blk and virtio-scsi, which
> can then remove their op blockers on BDS ejection and set them up on
> insertion.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/block-backend.c          | 20 ++++++++++++++++++++
>  include/sysemu/block-backend.h |  2 ++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/block/block-backend.c b/block/block-backend.c
> index a4208f1..1872191 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -49,6 +49,8 @@ struct BlockBackend {
>      BlockdevOnError on_read_error, on_write_error;
>      bool iostatus_enabled;
>      BlockDeviceIoStatus iostatus;
> +
> +    NotifierList remove_bs_notifiers, insert_bs_notifiers;
>  };
>  
>  typedef struct BlockBackendAIOCB {
> @@ -99,6 +101,8 @@ BlockBackend *blk_new(const char *name, Error **errp)
>      blk = g_new0(BlockBackend, 1);
>      blk->name = g_strdup(name);
>      blk->refcnt = 1;
> +    notifier_list_init(&blk->remove_bs_notifiers);
> +    notifier_list_init(&blk->insert_bs_notifiers);
>      QTAILQ_INSERT_TAIL(&blk_backends, blk, link);
>      return blk;
>  }
> @@ -167,6 +171,8 @@ static void blk_delete(BlockBackend *blk)
>          bdrv_unref(blk->bs);
>          blk->bs = NULL;
>      }
> +    assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers));
> +    assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers));
>      if (blk->root_state.throttle_state) {
>          g_free(blk->root_state.throttle_group);
>          throttle_group_unref(blk->root_state.throttle_state);
> @@ -345,6 +351,8 @@ void blk_hide_on_behalf_of_hmp_drive_del(BlockBackend *blk)
>   */
>  void blk_remove_bs(BlockBackend *blk)
>  {
> +    notifier_list_notify(&blk->remove_bs_notifiers, blk);
> +
>      blk_update_root_state(blk);
>  
>      blk->bs->blk = NULL;
> @@ -361,6 +369,8 @@ void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs)
>      bdrv_ref(bs);
>      blk->bs = bs;
>      bs->blk = blk;
> +
> +    notifier_list_notify(&blk->insert_bs_notifiers, blk);
>  }
>  
>  /*
> @@ -1126,6 +1136,16 @@ void blk_remove_aio_context_notifier(BlockBackend *blk,
>      }
>  }
>  
> +void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify)
> +{
> +    notifier_list_add(&blk->remove_bs_notifiers, notify);
> +}
> +
> +void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify)
> +{
> +    notifier_list_add(&blk->insert_bs_notifiers, notify);
> +}
> +
>  void blk_add_close_notifier(BlockBackend *blk, Notifier *notify)
>  {
>      if (blk->bs) {
> diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
> index 1568554..e12be67 100644
> --- a/include/sysemu/block-backend.h
> +++ b/include/sysemu/block-backend.h
> @@ -164,6 +164,8 @@ void blk_remove_aio_context_notifier(BlockBackend *blk,
>                                                                    void *),
>                                       void (*detach_aio_context)(void *),
>                                       void *opaque);
> +void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify);
> +void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify);
>  void blk_add_close_notifier(BlockBackend *blk, Notifier *notify);
>  void blk_io_plug(BlockBackend *blk);
>  void blk_io_unplug(BlockBackend *blk);
> -- 
> 2.7.0
> 

Reviewed-by: Fam Zheng <famz@redhat.com>