rbd: merge diff files

RBD supplies the 'export-diff' to export a diff file between two clones. This is inconvinient for periodical backup, since a bunch of diff files wastes the disk space by keeping multiple copies of the data on the same location, and complicates and slows down the recovery process. In this case, only one diff file is expected. This motivates us to develop a 'merge-diff' tool. The semantic is straightforward, it merges two diff files into one single diff file. Multiple diff files could be easily merged by further using some simple shell tricks.

The patches are at:
https://github.com/ceph/ceph/pull/3292

MingXin Liu (6):
rbd: add an option merge-diff
rbd: parse merge-diff arguments
rbd: write a diff description into the merged diff file
rbd: parse diff file header for diff merging
rbd: parse diff file body for diff merging
rbd: test case for rbd merge-diff

Yunchuan Wen (1):
rbd: merge two diff files into one single file

 qa/workunits/rbd/merge_diff.sh | 475 +++++++++++++++++++++++++++++++++++++++++
 src/rbd.cc                     | 384 ++++++++++++++++++++++++++++++++-
 2 files changed, 855 insertions(+), 4 deletions(-)
 create mode 100755 qa/workunits/rbd/merge_diff.sh

1.9.1