[Qemu-block] [PATCH v7 11/24] block: Add BB-BDS remove/insert notifiers

[Max Reitz]

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 <address@hidden>
---
 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 6f9309f..8f74a54 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -48,6 +48,8 @@ struct BlockBackend {
     BlockdevOnError on_read_error, on_write_error;
     bool iostatus_enabled;
     BlockDeviceIoStatus iostatus;
+
+    NotifierList remove_bs_notifiers, insert_bs_notifiers;
 };
 
 typedef struct BlockBackendAIOCB {
@@ -98,6 +100,8 @@ 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;
 }
@@ -166,6 +170,8 @@ 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);
@@ -343,6 +349,8 @@ 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;
@@ -359,6 +367,8 @@ 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);
 }
 
 /*
@@ -1105,6 +1115,16 @@ 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 f4a68e2..632cdc0 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -162,6 +162,8 @@ 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);
-- 
2.6.2