[PATCH 13/15] block: convert bdrv_io_plug in generated_co_wrapper_simple

[Emanuele Giuseppe Esposito <eesposit@redhat.com>]

BlockDriver->bdrv_io_plug is categorized as IO callback, and
it currently doesn't run in a coroutine.
This makes very difficult to add the graph rdlock, since the
callback traverses the block nodes graph.

The only caller of this function is blk_plug, therefore
make blk_plug a generated_co_wrapper_simple, so that
it always creates a new coroutine, and then make bdrv_plug
coroutine_fn.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 block/block-backend.c             | 5 +++--
 block/io.c                        | 5 +++--
 include/block/block-io.h          | 3 ++-
 include/block/block_int-common.h  | 4 ++--
 include/sysemu/block-backend-io.h | 4 +++-
 5 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 75e2f2124f..826a936beb 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2329,13 +2329,14 @@ void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify)
     notifier_list_add(&blk->insert_bs_notifiers, notify);
 }
 
-void blk_io_plug(BlockBackend *blk)
+void coroutine_fn blk_co_io_plug(BlockBackend *blk)
 {
     BlockDriverState *bs = blk_bs(blk);
     IO_CODE();
+    assert_bdrv_graph_readable();
 
     if (bs) {
-        bdrv_io_plug(bs);
+        bdrv_co_io_plug(bs);
     }
 }
 
diff --git a/block/io.c b/block/io.c
index 11d2c5dcde..d3b8c1e4b2 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3068,13 +3068,14 @@ void *qemu_try_blockalign0(BlockDriverState *bs, size_t size)
     return mem;
 }
 
-void bdrv_io_plug(BlockDriverState *bs)
+void coroutine_fn bdrv_co_io_plug(BlockDriverState *bs)
 {
     BdrvChild *child;
     IO_CODE();
+    assert_bdrv_graph_readable();
 
     QLIST_FOREACH(child, &bs->children, next) {
-        bdrv_io_plug(child->bs);
+        bdrv_co_io_plug(child->bs);
     }
 
     if (qatomic_fetch_inc(&bs->io_plugged) == 0) {
diff --git a/include/block/block-io.h b/include/block/block-io.h
index 176e3cc734..a045643b26 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -215,7 +215,8 @@ void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co);
 
 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c);
 
-void bdrv_io_plug(BlockDriverState *bs);
+void coroutine_fn bdrv_co_io_plug(BlockDriverState *bs);
+
 void bdrv_io_unplug(BlockDriverState *bs);
 
 bool coroutine_fn bdrv_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index b509855c19..ed96bc3241 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -785,8 +785,8 @@ struct BlockDriver {
     void coroutine_fn (*bdrv_debug_event)(BlockDriverState *bs,
                                           BlkdebugEvent event);
 
-    /* io queue for linux-aio */
-    void (*bdrv_io_plug)(BlockDriverState *bs);
+    /* io queue for linux-aio. Called with graph rdlock taken. */
+    void coroutine_fn (*bdrv_io_plug)(BlockDriverState *bs);
     void (*bdrv_io_unplug)(BlockDriverState *bs);
 
     /**
diff --git a/include/sysemu/block-backend-io.h b/include/sysemu/block-backend-io.h
index dd8566ee69..703fcc3ac5 100644
--- a/include/sysemu/block-backend-io.h
+++ b/include/sysemu/block-backend-io.h
@@ -87,7 +87,9 @@ void blk_iostatus_set_err(BlockBackend *blk, int error);
 int blk_get_max_iov(BlockBackend *blk);
 int blk_get_max_hw_iov(BlockBackend *blk);
 
-void blk_io_plug(BlockBackend *blk);
+void coroutine_fn blk_co_io_plug(BlockBackend *blk);
+void generated_co_wrapper_simple blk_io_plug(BlockBackend *blk);
+
 void blk_io_unplug(BlockBackend *blk);
 AioContext *blk_get_aio_context(BlockBackend *blk);
 BlockAcctStats *blk_get_stats(BlockBackend *blk);
-- 
2.31.1