[PATCH 02/14] block: Convert bdrv_io_plug() to co_wrapper

[Kevin Wolf <kwolf@redhat.com>]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

BlockDriver->bdrv_io_plug is categorized as IO callback, and it
currently doesn't run in a coroutine. We should let it take a graph
rdlock since the callback traverses the block nodes graph, which however
is only possible in a coroutine.

The only caller of this function is blk_io_plug(), therefore make
blk_io_plug() a co_wrapper, so that we're always running in a coroutine
where the lock can be taken.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-io.h          | 3 ++-
 include/block/block_int-common.h  | 2 +-
 include/sysemu/block-backend-io.h | 4 +++-
 block/block-backend.c             | 4 ++--
 block/io.c                        | 4 ++--
 5 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/include/block/block-io.h b/include/block/block-io.h
index 2ed6214909..d96168375e 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -217,7 +217,8 @@ 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 c34c525fa6..4a1c1e348a 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -729,7 +729,7 @@ struct BlockDriver {
     void (*bdrv_debug_event)(BlockDriverState *bs, BlkdebugEvent event);
 
     /* io queue for linux-aio */
-    void (*bdrv_io_plug)(BlockDriverState *bs);
+    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 7ec6d978d4..70b73f7d11 100644
--- a/include/sysemu/block-backend-io.h
+++ b/include/sysemu/block-backend-io.h
@@ -73,7 +73,9 @@ 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 co_wrapper blk_io_plug(BlockBackend *blk);
+
 void blk_io_unplug(BlockBackend *blk);
 AioContext *blk_get_aio_context(BlockBackend *blk);
 BlockAcctStats *blk_get_stats(BlockBackend *blk);
diff --git a/block/block-backend.c b/block/block-backend.c
index 2852a892de..f862fd1950 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2315,13 +2315,13 @@ 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();
 
     if (bs) {
-        bdrv_io_plug(bs);
+        bdrv_co_io_plug(bs);
     }
 }
 
diff --git a/block/io.c b/block/io.c
index d87788dfbb..3d27836420 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3127,13 +3127,13 @@ 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();
 
     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) {
-- 
2.38.1