[PATCH v4 08/34] block: Pass parent_is_format to .inherit_options()

[Max Reitz]

We plan to unify the generic .inherit_options() functions.  The
resulting common function will need to decide whether to force-enable
format probing, force-disable it, or leave it as-is.  To make this
decision, it will need to know whether the parent node is a format node
or not (because we never want format probing if the parent is a format
node already (except for the backing chain)).

Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
 include/block/block_int.h |  2 +-
 block.c                   | 37 +++++++++++++++++++++++++++----------
 block/block-backend.c     |  2 +-
 block/vvfat.c             |  2 +-
 4 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 8c1160a577..6245d8a18d 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -677,7 +677,7 @@ struct BdrvChildClass {
      * non-BDS parents. */
     bool parent_is_bds;
 
-    void (*inherit_options)(BdrvChildRole role,
+    void (*inherit_options)(BdrvChildRole role, bool parent_is_format,
                             int *child_flags, QDict *child_options,
                             int parent_flags, QDict *parent_options);
 
diff --git a/block.c b/block.c
index 40db0b78b9..b78e2dc141 100644
--- a/block.c
+++ b/block.c
@@ -1154,7 +1154,7 @@ static void bdrv_temp_snapshot_options(int *child_flags, 
QDict *child_options,
  * Returns the options and flags that bs->file should get if a protocol driver
  * is expected, based on the given options and flags for the parent BDS
  */
-static void bdrv_inherited_options(BdrvChildRole role,
+static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
                                    int *child_flags, QDict *child_options,
                                    int parent_flags, QDict *parent_options)
 {
@@ -1205,10 +1205,12 @@ const BdrvChildClass child_file = {
  * flags for the parent BDS
  */
 static void bdrv_inherited_fmt_options(BdrvChildRole role,
+                                       bool parent_is_format,
                                        int *child_flags, QDict *child_options,
                                        int parent_flags, QDict *parent_options)
 {
-    child_file.inherit_options(role, child_flags, child_options,
+    child_file.inherit_options(role, parent_is_format,
+                               child_flags, child_options,
                                parent_flags, parent_options);
 
     *child_flags &= ~(BDRV_O_PROTOCOL | BDRV_O_NO_IO);
@@ -1289,7 +1291,7 @@ static void bdrv_backing_detach(BdrvChild *c)
  * Returns the options and flags that bs->backing should get, based on the
  * given options and flags for the parent BDS
  */
-static void bdrv_backing_options(BdrvChildRole role,
+static void bdrv_backing_options(BdrvChildRole role, bool parent_is_format,
                                  int *child_flags, QDict *child_options,
                                  int parent_flags, QDict *parent_options)
 {
@@ -3173,8 +3175,22 @@ static BlockDriverState *bdrv_open_inherit(const char 
*filename,
     bs->explicit_options = qdict_clone_shallow(options);
 
     if (child_class) {
+        bool parent_is_format;
+
+        if (parent->drv) {
+            parent_is_format = parent->drv->is_format;
+        } else {
+            /*
+             * parent->drv is not set yet because this node is opened for
+             * (potential) format probing.  That means that @parent is going
+             * to be a format node.
+             */
+            parent_is_format = true;
+        }
+
         bs->inherits_from = parent;
-        child_class->inherit_options(child_role, &flags, options,
+        child_class->inherit_options(child_role, parent_is_format,
+                                     &flags, options,
                                      parent->open_flags, parent->options);
     }
 
@@ -3203,7 +3219,7 @@ static BlockDriverState *bdrv_open_inherit(const char 
*filename,
                                    flags, options);
         /* Let bdrv_backing_options() override "read-only" */
         qdict_del(options, BDRV_OPT_READ_ONLY);
-        bdrv_backing_options(0, &flags, options, flags, options);
+        bdrv_backing_options(0, true, &flags, options, flags, options);
     }
 
     bs->open_flags = flags;
@@ -3488,6 +3504,7 @@ static BlockReopenQueue 
*bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
                                                  QDict *options,
                                                  const BdrvChildClass *klass,
                                                  BdrvChildRole role,
+                                                 bool parent_is_format,
                                                  QDict *parent_options,
                                                  int parent_flags,
                                                  bool keep_old_opts)
@@ -3543,7 +3560,7 @@ static BlockReopenQueue 
*bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
     /* Inherit from parent node */
     if (parent_options) {
         flags = 0;
-        klass->inherit_options(role, &flags, options,
+        klass->inherit_options(role, parent_is_format, &flags, options,
                                parent_flags, parent_options);
     } else {
         flags = bdrv_get_flags(bs);
@@ -3635,8 +3652,8 @@ static BlockReopenQueue 
*bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
         }
 
         bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
-                                child->klass, child->role, options, flags,
-                                child_keep_old);
+                                child->klass, child->role, bs->drv->is_format,
+                                options, flags, child_keep_old);
     }
 
     return bs_queue;
@@ -3646,8 +3663,8 @@ BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue 
*bs_queue,
                                     BlockDriverState *bs,
                                     QDict *options, bool keep_old_opts)
 {
-    return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, NULL, 0,
-                                   keep_old_opts);
+    return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
+                                   NULL, 0, keep_old_opts);
 }
 
 /*
diff --git a/block/block-backend.c b/block/block-backend.c
index 5539ca8816..f2e81af27d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -120,7 +120,7 @@ static QTAILQ_HEAD(, BlockBackend) block_backends =
 static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
     QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
 
-static void blk_root_inherit_options(BdrvChildRole role,
+static void blk_root_inherit_options(BdrvChildRole role, bool parent_is_format,
                                      int *child_flags, QDict *child_options,
                                      int parent_flags, QDict *parent_options)
 {
diff --git a/block/vvfat.c b/block/vvfat.c
index 4033e4f369..b4c8417dbd 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -3128,7 +3128,7 @@ static BlockDriver vvfat_write_target = {
     .bdrv_co_pwritev    = write_target_commit,
 };
 
-static void vvfat_qcow_options(BdrvChildRole role,
+static void vvfat_qcow_options(BdrvChildRole role, bool parent_is_format,
                                int *child_flags, QDict *child_options,
                                int parent_flags, QDict *parent_options)
 {
-- 
2.26.2