block: Mark public read/write functions GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_co_pread*/pwrite*() need to hold a reader lock for the graph.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230203152202.49054-12-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/commit.c b/block/commit.c
index 41e3599..10f6512 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -207,8 +207,9 @@
     },
 };
 
-static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs,
-    int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags)
+static int coroutine_fn GRAPH_RDLOCK
+bdrv_commit_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
+                       QEMUIOVector *qiov, BdrvRequestFlags flags)
 {
     return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
 }