When mirroring images, it makes sense for the destination to be sparse even if it was not connected with "discard":"unmap"; the only time the destination should be fully allocated is if the user pre-allocated it, or if the source was not sparse.
Eric Blake (6): mirror: Skip pre-zeroing destination if it is already zero file-posix: Allow lseek at offset 0 when !want_zero mirror: Skip writing zeroes when target is already zero block: Expand block status mode from bool to enum file-posix: Recognize blockdev-create file as starting all zero tests: Add iotest mirror-sparse for recent patches block/coroutines.h | 4 +- include/block/block-common.h | 26 ++++ include/block/block_int-common.h | 25 ++-- include/block/block_int-io.h | 4 +- block/io.c | 51 +++---- block/blkdebug.c | 6 +- block/copy-before-write.c | 4 +- block/file-posix.c | 94 +++++++++++-- block/gluster.c | 4 +- block/iscsi.c | 6 +- block/mirror.c | 100 +++++++++++--- block/nbd.c | 4 +- block/null.c | 6 +- block/parallels.c | 6 +- block/qcow.c | 2 +- block/qcow2.c | 6 +- block/qed.c | 6 +- block/quorum.c | 4 +- block/raw-format.c | 4 +- block/rbd.c | 6 +- block/snapshot-access.c | 4 +- block/vdi.c | 4 +- block/vmdk.c | 2 +- block/vpc.c | 2 +- block/vvfat.c | 6 +- tests/unit/test-block-iothread.c | 2 +- tests/qemu-iotests/194 | 15 +- tests/qemu-iotests/194.out | 4 +- tests/qemu-iotests/tests/mirror-sparse | 100 ++++++++++++++ tests/qemu-iotests/tests/mirror-sparse.out | 153 +++++++++++++++++++++ 30 files changed, 547 insertions(+), 113 deletions(-) create mode 100755 tests/qemu-iotests/tests/mirror-sparse create mode 100644 tests/qemu-iotests/tests/mirror-sparse.out -- 2.49.0
