This preserves any data that the backing file had on a cluster when
doing a write to a subset of that cluster. These writes cause a
performance penalty on creating new clusters if a backing file is
present.
This commit is based on crosvm implementation:
5ad3bc3459
Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>
Reads to qcow files with backing files will fall through to the backing
file if there is no allocated cluster. As of this change, a write will
still trash the cluster and hide any data already present.
This commit is based on crosvm implementation:
d8144a56e2
Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>
This commit allows opening qcow with a backing file, which supports any
type implementing `BlockBackend`.
This commit is based on crosvm implementation:
9ca6039b03
Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>
This commit introduces the trait `BlockBackend` with generic ops
including read, write and seek, which can be used for common I/O
interfaces for the block types without using `DiskFile` and `AsyncIo`.
Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>
This commit merges crates `qcow`, `vhdx` and `block_util` into the
crate `block`, which can allow `qcow` to use functions from `block_util`
without introducing a circular crate dependency.
This commit is based on crosvm implementation:
f2eecc4152
Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>
