Am 27.02.2019 um 18:22 hat Kevin Wolf geschrieben: > There are use cases where raw images are given (e.g. existing physical > disks), but advanced features like dirty bitmaps or backing files are > wanted that require use of a proper image format like qcow2. > > This series adds an incompatible feature bit to qcow2 which allows to > use an external data file: Metadata is kept in the qcow2 file like > usual, but guest data is written to an external file. Clusters in the > data file are not reference counted, instead we use a flat layout where > host cluster offset == guest cluster offset. The external data file is > therefore readable as a raw image (though writing to it invalidates the > associated qcow2 metadata). Features that require refcounting such as > internal snapshots or compression are not supposed in such setups. > > Major changes since the RFC (many more minor changes): > > - Added a 'data-file-raw' flag to the spec to keep the data file a valid > self-consistent raw image (write_zeroes must always be propagated) > - Added QAPI documentation > - Added some test cases > - Implemented data file support or error paths for discard, check, > compressed writes, snapshots > - Fixed qcow2_co_block_status() > - Rearranged qcow2_do_open() code for data files for better error > handling (e.g. no more fallback to default data file if an explicit, > but invalid data-file option is given)
Thanks, made the trivial changes suggested during review and applied to the block branch. Kevin
