On Thu, Aug 29, 2013 at 04:00:00PM +0200, Paolo Bonzini wrote: > This series adds a subcommand to "qemu-img" that can dump file metadata. > Metadata that is dumped includes: > > - whether blocks are allocated in bs->file and, if so, where > > - whether blocks are zero > > - whether data is read from bs or bs->backing_hd > > Metadata is dumped for an entire chain of images. One example usage is > (for non-compressed, non-encrypted images) to transform the metadata > into a Linux device-mapper setup, and make a qcow2 image available (for > read only) as a block device. Another possible usage is to determine > the used areas of a file, and convert it in place to another format. > Alternatively, the richer data can be used by block jobs to quickly > determine if a block is zero without reading it. > > The patches implement a new operation, bdrv_co_get_block_status, that > supersedes bdrv_co_is_allocated. The bdrv_is_allocated API is still > available of course, and implemented on top of the new operation. > > Patches 1-3 touch cow, which uses bdrv_co_is_allocated during its reads > and writes. I optimized it a bit because it was unbearably slow during > testing. With these patches (also tested with blkverify), booting of > a cow guest image is not particularly slow. > > Patch 4 fixes the bs->total_sectors file size cache, which is used in > bdrv_co_get_block_status to clamp invalid input. > > Patches 5 to 8 clean up the bdrv_is_allocated and bdrv_is_allocated_above > implementation, eliminating some code duplication. > > Patches 9 and 10 tweak bdrv_has_zero_init and its usage in qemu-img in > a way that helps when implementing the new API. > > Patches 11 to 15 implement bdrv_get_block_status and change the formats > to report all the available information. > > Patch 16 and 17 adds the "map" subcommand to qemu-img, and the relevant > documentation. > > Finally, patches 18 to 21 tweak the implementation to extract more > information from protocols, and combine this information with format > metadata whenever possible.
Please rebase on qemu.git/master (includes raw BSD and other potential conflicts). Stefan
