[PATCH v2 20/20] block: Mark bdrv_refresh_limits() and callers GRAPH_RDLOCK

[Kevin Wolf]

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_refresh_limits() need to hold a reader lock for the graph because
it accesses the children list of a node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/block/block-global-state.h | 5 ++++-
 include/block/block_int-common.h   | 3 ++-
 block.c                            | 9 +++++++++
 block/io.c                         | 1 -
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/block/block-global-state.h 
b/include/block/block-global-state.h
index f234bca0b6..2d93423d35 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -133,7 +133,10 @@ int bdrv_reopen_set_read_only(BlockDriverState *bs, bool 
read_only,
 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
                                           const char *backing_file);
 void bdrv_refresh_filename(BlockDriverState *bs);
-void bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error 
**errp);
+
+void GRAPH_RDLOCK
+bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp);
+
 int bdrv_commit(BlockDriverState *bs);
 int bdrv_make_empty(BdrvChild *c, Error **errp);
 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 024ded4fc2..4909876756 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -334,7 +334,8 @@ struct BlockDriver {
     int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag);
     bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
 
-    void (*bdrv_refresh_limits)(BlockDriverState *bs, Error **errp);
+    void GRAPH_RDLOCK_PTR (*bdrv_refresh_limits)(
+        BlockDriverState *bs, Error **errp);
 
     /*
      * Returns 1 if newly created images are guaranteed to contain only
diff --git a/block.c b/block.c
index 1bc766c778..dad9a4fa43 100644
--- a/block.c
+++ b/block.c
@@ -1667,7 +1667,10 @@ bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, 
const char *node_name,
         return ret;
     }
 
+    bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(bs, NULL, &local_err);
+    bdrv_graph_rdunlock_main_loop();
+
     if (local_err) {
         error_propagate(errp, local_err);
         return -EINVAL;
@@ -3419,7 +3422,9 @@ static int 
bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
     }
 
 out:
+    bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(parent_bs, tran, NULL);
+    bdrv_graph_rdunlock_main_loop();
 
     return 0;
 }
@@ -4917,7 +4922,9 @@ static void bdrv_reopen_commit(BDRVReopenState 
*reopen_state)
     qdict_del(bs->explicit_options, "backing");
     qdict_del(bs->options, "backing");
 
+    bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(bs, NULL, NULL);
+    bdrv_graph_rdunlock_main_loop();
     bdrv_refresh_total_sectors(bs, bs->total_sectors);
 }
 
@@ -5316,7 +5323,9 @@ int bdrv_append(BlockDriverState *bs_new, 
BlockDriverState *bs_top,
 out:
     tran_finalize(tran, ret);
 
+    bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(bs_top, NULL, NULL);
+    bdrv_graph_rdunlock_main_loop();
 
     if (new_context && old_context != new_context) {
         aio_context_release(new_context);
diff --git a/block/io.c b/block/io.c
index 3bf9ef9d87..58557f2f96 100644
--- a/block/io.c
+++ b/block/io.c
@@ -160,7 +160,6 @@ void bdrv_refresh_limits(BlockDriverState *bs, Transaction 
*tran, Error **errp)
     bool have_limits;
 
     GLOBAL_STATE_CODE();
-    assume_graph_lock(); /* FIXME */
 
     if (tran) {
         BdrvRefreshLimitsState *s = g_new(BdrvRefreshLimitsState, 1);
-- 
2.40.1