diff options
Diffstat (limited to 'include/block/block_int.h')
| -rw-r--r-- | include/block/block_int.h | 44 |
1 files changed, 41 insertions, 3 deletions
diff --git a/include/block/block_int.h b/include/block/block_int.h index 9da7a42927..f280a95b26 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -92,9 +92,17 @@ struct BlockDriver { int instance_size; /* set to true if the BlockDriver is a block filter. Block filters pass - * certain callbacks that refer to data (see block.c) to their bs->file if - * the driver doesn't implement them. Drivers that do not wish to forward - * must implement them and return -ENOTSUP. + * certain callbacks that refer to data (see block.c) to their bs->file + * or bs->backing (whichever one exists) if the driver doesn't implement + * them. Drivers that do not wish to forward must implement them and return + * -ENOTSUP. + * Note that filters are not allowed to modify data. + * + * Filters generally cannot have more than a single filtered child, + * because the data they present must at all times be the same as + * that on their filtered child. That would be impossible to + * achieve for multiple filtered children. + * (And this filtered child must then be bs->file or bs->backing.) */ bool is_filter; /* @@ -1382,4 +1390,34 @@ BdrvDirtyBitmap *block_dirty_bitmap_remove(const char *node, const char *name, BlockDriverState **bitmap_bs, Error **errp); +BdrvChild *bdrv_cow_child(BlockDriverState *bs); +BdrvChild *bdrv_filter_child(BlockDriverState *bs); +BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs); +BdrvChild *bdrv_primary_child(BlockDriverState *bs); + +static inline BlockDriverState *child_bs(BdrvChild *child) +{ + return child ? child->bs : NULL; +} + +static inline BlockDriverState *bdrv_cow_bs(BlockDriverState *bs) +{ + return child_bs(bdrv_cow_child(bs)); +} + +static inline BlockDriverState *bdrv_filter_bs(BlockDriverState *bs) +{ + return child_bs(bdrv_filter_child(bs)); +} + +static inline BlockDriverState *bdrv_filter_or_cow_bs(BlockDriverState *bs) +{ + return child_bs(bdrv_filter_or_cow_child(bs)); +} + +static inline BlockDriverState *bdrv_primary_bs(BlockDriverState *bs) +{ + return child_bs(bdrv_primary_child(bs)); +} + #endif /* BLOCK_INT_H */ |