This series adds a subcommand to "map" 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.
Patches 4 to 6 clean up the bdrv_is_allocated and bdrv_is_allocated_above
implementation, eliminating some code duplication.
Patches 7 and 8 tweak bdrv_has_zero_init and its usage in qemu-img in
a way that helps when implementing the new API.
Patches 9 to 11 implement bdrv_get_block_status and change the formats
to report all the available information.
Patch 12 adds the "map" subcommand to qemu-img.
Finally, patches 13 to 17 tweak the implementation to extract more
information from protocols, and combine this information with format
metadata whenever possible.
Paolo
Paolo Bonzini (17):
cow: make reads go at a decent speed
cow: make writes go at a less indecent speed
cow: do not call bdrv_co_is_allocated
block: make bdrv_co_is_allocated static
block: remove bdrv_is_allocated_above/bdrv_co_is_allocated_above
distinction
block: expect errors from bdrv_co_is_allocated
qemu-img: always probe the input image for allocated sectors
block: make bdrv_has_zero_init return false for copy-on-write-images
block: introduce bdrv_get_block_status API
block: define get_block_status return value
block: return get_block_status data and flags for formats
qemu-img: add a "map" subcommand
block: use bdrv_has_zero_init to return BDRV_BLOCK_ZERO
raw-posix: return get_block_status data and flags
raw-posix: detect XFS unwritten extents
block: add default get_block_status implementation for protocols
block: look for zero blocks in bs->file
block.c | 134 +++++++++++++--------------
block/commit.c | 6 +-
block/cow.c | 90 +++++++++++++------
block/mirror.c | 4 +-
block/qcow.c | 13 ++-
block/qcow2.c | 24 +++--
block/qed.c | 39 ++++++--
block/raw-posix.c | 24 +++--
block/raw.c | 6 +-
block/sheepdog.c | 14 +--
block/stream.c | 10 +--
block/vdi.c | 17 +++-
block/vmdk.c | 20 ++++-
block/vvfat.c | 15 ++--
include/block/block.h | 31 +++++--
include/block/block_int.h | 2 +-
qemu-img-cmds.hx | 6 ++
qemu-img.c | 225 +++++++++++++++++++++++++++++++++++++++++-----
18 files changed, 497 insertions(+), 183 deletions(-)