[Qemu-devel] [PATCH 1/9] block: Use BdrvChild callbacks for change_media/resize

[Kevin Wolf <kwolf@redhat.com>]

We want to get rid of BlockDriverState.blk in order to allow multiple
BlockBackends per BDS. Converting the device callbacks in block.c (which
assume a single BlockBackend) to per-child callbacks gets us rid of the
first few instances.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c                   | 38 +++++++++++++++++++++++++-------------
 block/block-backend.c     | 15 ++++++++++++++-
 include/block/block_int.h |  4 +++-
 3 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/block.c b/block.c
index fb37b91..1fb5dac 100644
--- a/block.c
+++ b/block.c
@@ -1216,6 +1216,27 @@ void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
     bdrv_root_unref_child(child);
 }
 
+
+static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
+{
+    BdrvChild *c;
+    QLIST_FOREACH(c, &bs->parents, next_parent) {
+        if (c->role->change_media) {
+            c->role->change_media(c, load);
+        }
+    }
+}
+
+static void bdrv_parent_cb_resize(BlockDriverState *bs)
+{
+    BdrvChild *c;
+    QLIST_FOREACH(c, &bs->parents, next_parent) {
+        if (c->role->resize) {
+            c->role->resize(c);
+        }
+    }
+}
+
 /*
  * Sets the backing file link of a BDS. A new reference is created; callers
  * which don't need their own reference any more must call bdrv_unref().
@@ -1674,9 +1695,7 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
     }
 
     if (!bdrv_key_required(bs)) {
-        if (bs->blk) {
-            blk_dev_change_media_cb(bs->blk, true);
-        }
+        bdrv_parent_cb_change_media(bs, true);
     } else if (!runstate_check(RUN_STATE_PRELAUNCH)
                && !runstate_check(RUN_STATE_INMIGRATE)
                && !runstate_check(RUN_STATE_PAUSED)) { /* HACK */
@@ -2122,9 +2141,7 @@ static void bdrv_close(BlockDriverState *bs)
     bdrv_release_named_dirty_bitmaps(bs);
     assert(QLIST_EMPTY(&bs->dirty_bitmaps));
 
-    if (bs->blk) {
-        blk_dev_change_media_cb(bs->blk, false);
-    }
+    bdrv_parent_cb_change_media(bs, false);
 
     if (bs->drv) {
         BdrvChild *child, *next;
@@ -2605,9 +2622,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset)
     if (ret == 0) {
         ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
         bdrv_dirty_bitmap_truncate(bs);
-        if (bs->blk) {
-            blk_dev_resize_cb(bs->blk);
-        }
+        bdrv_parent_cb_resize(bs);
     }
     return ret;
 }
@@ -2718,10 +2733,7 @@ int bdrv_set_key(BlockDriverState *bs, const char *key)
         bs->valid_key = 0;
     } else if (!bs->valid_key) {
         bs->valid_key = 1;
-        if (bs->blk) {
-            /* call the change callback now, we skipped it on open */
-            blk_dev_change_media_cb(bs->blk, true);
-        }
+        bdrv_parent_cb_change_media(bs, true);
     }
     return ret;
 }
diff --git a/block/block-backend.c b/block/block-backend.c
index 8b4eb1a..9d973ba 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -92,9 +92,15 @@ static void blk_root_inherit_options(int *child_flags, QDict *child_options,
 }
 static bool blk_drain_throttling_queue(BdrvChild *child);
 
+static void blk_root_change_media(BdrvChild *child, bool load);
+static void blk_root_resize(BdrvChild *child);
+
 static const BdrvChildRole child_root = {
     .inherit_options    = blk_root_inherit_options,
 
+    .change_media       = blk_root_change_media,
+    .resize             = blk_root_resize,
+
     .drain_queue        = blk_drain_throttling_queue,
 };
 
@@ -553,6 +559,11 @@ void blk_dev_change_media_cb(BlockBackend *blk, bool load)
     }
 }
 
+static void blk_root_change_media(BdrvChild *child, bool load)
+{
+    blk_dev_change_media_cb(child->opaque, load);
+}
+
 /*
  * Does @blk's attached device model have removable media?
  * %true if no device model is attached.
@@ -607,8 +618,10 @@ bool blk_dev_is_medium_locked(BlockBackend *blk)
 /*
  * Notify @blk's attached device model of a backend size change.
  */
-void blk_dev_resize_cb(BlockBackend *blk)
+static void blk_root_resize(BdrvChild *child)
 {
+    BlockBackend *blk = child->opaque;
+
     if (blk->dev_ops && blk->dev_ops->resize_cb) {
         blk->dev_ops->resize_cb(blk->dev_opaque);
     }
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 000d2c0..f60cb7c 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -356,6 +356,9 @@ struct BdrvChildRole {
     void (*inherit_options)(int *child_flags, QDict *child_options,
                             int parent_flags, QDict *parent_options);
 
+    void (*change_media)(BdrvChild *child, bool load);
+    void (*resize)(BdrvChild *child);
+
     bool (*drain_queue)(BdrvChild *child);
 };
 
@@ -695,7 +698,6 @@ bool blk_dev_has_tray(BlockBackend *blk);
 void blk_dev_eject_request(BlockBackend *blk, bool force);
 bool blk_dev_is_tray_open(BlockBackend *blk);
 bool blk_dev_is_medium_locked(BlockBackend *blk);
-void blk_dev_resize_cb(BlockBackend *blk);
 
 void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
 bool bdrv_requests_pending(BlockDriverState *bs);
-- 
1.8.3.1