diff options
| -rw-r--r-- | include/block/block.h | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/include/block/block.h b/include/block/block.h index bc42e50..35f1a1c 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 that parent nodes assign to 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); |