[PATCH for-5.0 16/31] block: Add bdrv_default_perms()

[Max Reitz <mreitz@redhat.com>]

This callback can be used by BDSs that use child_of_bds with the
appropriate BdrvChildRole for their children.

Also, make bdrv_format_default_perms() use it for child_of_bds children
(just a temporary solution until we can drop bdrv_format_default_perms()
altogether).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c                   | 46 ++++++++++++++++++++++++++++++++-------
 include/block/block_int.h | 11 ++++++++++
 2 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/block.c b/block.c
index 33abd7f64e..5b38c7799a 100644
--- a/block.c
+++ b/block.c
@@ -2337,14 +2337,12 @@ static void bdrv_default_perms_for_metadata(BlockDriverState *bs, BdrvChild *c,
     *nshared = shared;
 }
 
-/* TODO: Use */
-static void __attribute__((unused))
-bdrv_default_perms_for_data(BlockDriverState *bs, BdrvChild *c,
-                            const BdrvChildClass *child_class,
-                            BdrvChildRole role,
-                            BlockReopenQueue *reopen_queue,
-                            uint64_t perm, uint64_t shared,
-                            uint64_t *nperm, uint64_t *nshared)
+static void bdrv_default_perms_for_data(BlockDriverState *bs, BdrvChild *c,
+                                        const BdrvChildClass *child_class,
+                                        BdrvChildRole role,
+                                        BlockReopenQueue *reopen_queue,
+                                        uint64_t perm, uint64_t shared,
+                                        uint64_t *nperm, uint64_t *nshared)
 {
     assert(child_class == &child_of_bds && (role & BDRV_CHILD_DATA));
 
@@ -2379,6 +2377,13 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
                                uint64_t *nperm, uint64_t *nshared)
 {
     bool backing = (child_class == &child_backing);
+
+    if (child_class == &child_of_bds) {
+        bdrv_default_perms(bs, c, child_class, role, reopen_queue,
+                           perm, shared, nperm, nshared);
+        return;
+    }
+
     assert(child_class == &child_backing || child_class == &child_file);
 
     if (!backing) {
@@ -2390,6 +2395,31 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
     }
 }
 
+void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
+                        const BdrvChildClass *child_class, BdrvChildRole role,
+                        BlockReopenQueue *reopen_queue,
+                        uint64_t perm, uint64_t shared,
+                        uint64_t *nperm, uint64_t *nshared)
+{
+    assert(child_class == &child_of_bds);
+
+    if (role & BDRV_CHILD_FILTERED) {
+        bdrv_filter_default_perms(bs, c, child_class, role, reopen_queue,
+                                  perm, shared, nperm, nshared);
+    } else if (role & BDRV_CHILD_COW) {
+        bdrv_default_perms_for_backing(bs, c, child_class, role, reopen_queue,
+                                       perm, shared, nperm, nshared);
+    } else if (role & BDRV_CHILD_METADATA) {
+        bdrv_default_perms_for_metadata(bs, c, child_class, role, reopen_queue,
+                                        perm, shared, nperm, nshared);
+    } else if (role & BDRV_CHILD_DATA) {
+        bdrv_default_perms_for_data(bs, c, child_class, role, reopen_queue,
+                                    perm, shared, nperm, nshared);
+    } else {
+        g_assert_not_reached();
+    }
+}
+
 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
 {
     static const uint64_t permissions[] = {
diff --git a/include/block/block_int.h b/include/block/block_int.h
index f2f8d770c6..b9375ceb1c 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -1272,6 +1272,17 @@ bool bdrv_recurse_can_replace(BlockDriverState *bs,
 bool bdrv_is_child_of(BlockDriverState *child, BlockDriverState *parent,
                       int min_level);
 
+/*
+ * Default implementation for BlockDriver.bdrv_child_perm() that can
+ * be used by block filters and image formats, as long as they use the
+ * child_of_bds child class and set an appropriate BdrvChildRole.
+ */
+void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
+                        const BdrvChildClass *child_class, BdrvChildRole role,
+                        BlockReopenQueue *reopen_queue,
+                        uint64_t perm, uint64_t shared,
+                        uint64_t *nperm, uint64_t *nshared);
+
 /*
  * Default implementation for drivers to pass bdrv_co_block_status() to
  * their file.
-- 
2.23.0