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[PATCH v4 04/34] block: Add BdrvChildRole and BdrvChildRoleBits
From: |
Max Reitz |
Subject: |
[PATCH v4 04/34] block: Add BdrvChildRole and BdrvChildRoleBits |
Date: |
Wed, 13 May 2020 13:05:14 +0200 |
This mask will supplement BdrvChildClass when it comes to what role (or
combination of roles) a child takes for its parent. It consists of
BdrvChildRoleBits values (which is an enum).
Because empty enums are not allowed, let us just start with it filled.
Signed-off-by: Max Reitz <address@hidden>
---
include/block/block.h | 56 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/include/block/block.h b/include/block/block.h
index bc42e507bb..86cffa9ffd 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -268,6 +268,62 @@ enum {
DEFAULT_PERM_UNCHANGED = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
};
+/*
+ * Flags parent nodes give for the child nodes to specify what kind of
+ * role(s) they take.
+ *
+ * At least one of DATA, METADATA, FILTERED, or COW must be set for
+ * every child.
+ */
+enum BdrvChildRoleBits {
+ /*
+ * This child stores data.
+ * Any node may have an arbitrary number of such children.
+ */
+ BDRV_CHILD_DATA = (1 << 0),
+
+ /*
+ * This child stores metadata.
+ * Any node may have an arbitrary number of metadata-storing
+ * children.
+ */
+ BDRV_CHILD_METADATA = (1 << 1),
+
+ /*
+ * A child that always presents exactly the same visible data as
+ * the parent, e.g. by virtue of the parent forwarding all reads
+ * and writes.
+ * This flag is mutually exclusive with DATA, METADATA, and COW.
+ * Any node may have at most one filtered child at a time.
+ */
+ BDRV_CHILD_FILTERED = (1 << 2),
+
+ /*
+ * Child from which to read all data that isn’t allocated in the
+ * parent (i.e., the backing child); such data is copied to the
+ * parent through COW (and optionally COR).
+ * This field is mutually exclusive with DATA, METADATA, and
+ * FILTERED.
+ * Any node may have at most one such backing child at a time.
+ */
+ BDRV_CHILD_COW = (1 << 3),
+
+ /*
+ * The primary child. For most drivers, this is the child whose
+ * filename applies best to the parent node.
+ * Any node may have at most one primary child at a time.
+ */
+ BDRV_CHILD_PRIMARY = (1 << 4),
+
+ /* Useful combination of flags */
+ BDRV_CHILD_IMAGE = BDRV_CHILD_DATA
+ | BDRV_CHILD_METADATA
+ | BDRV_CHILD_PRIMARY,
+};
+
+/* Mask of BdrvChildRoleBits values */
+typedef unsigned int BdrvChildRole;
+
char *bdrv_perm_names(uint64_t perm);
uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm);
--
2.26.2
- [PATCH v4 00/34] block: Introduce real BdrvChildRole, Max Reitz, 2020/05/13
- [PATCH v4 01/34] block: Mark commit, mirror, blkreplay as filters, Max Reitz, 2020/05/13
- [PATCH v4 02/34] block: Add BlockDriver.is_format, Max Reitz, 2020/05/13
- [PATCH v4 04/34] block: Add BdrvChildRole and BdrvChildRoleBits,
Max Reitz <=
- [PATCH v4 03/34] block: Rename BdrvChildRole to BdrvChildClass, Max Reitz, 2020/05/13
- [PATCH v4 05/34] block: Add BdrvChildRole to BdrvChild, Max Reitz, 2020/05/13
- [PATCH v4 06/34] block: Pass BdrvChildRole to bdrv_child_perm(), Max Reitz, 2020/05/13
- [PATCH v4 07/34] block: Pass BdrvChildRole to .inherit_options(), Max Reitz, 2020/05/13
- [PATCH v4 08/34] block: Pass parent_is_format to .inherit_options(), Max Reitz, 2020/05/13
- [PATCH v4 09/34] block: Rename bdrv_inherited_options(), Max Reitz, 2020/05/13
- [PATCH v4 10/34] block: Add generic bdrv_inherited_options(), Max Reitz, 2020/05/13
- [PATCH v4 11/34] block: Use bdrv_inherited_options(), Max Reitz, 2020/05/13