Re: [Qemu-devel] [PATCH 0/5] qcow2: Discard freed clusters

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

Hi, Kevin
  In normal case, qcow2 is based on raw-posix file which don't support
discard operation, so this serial doesn't change much in this case,
still real space is not freed in snapshot delete, and it completes
fast. Instead, tt affects the case that some protocol below support
discard, so delete will be more clean but slower in that case. Is this
true? Maybe add this in commit message?

> This series adds options to make qcow2 discard freed clusters, in several
> categories. By default, only freed clusters related to snapshots (i.e. mainly
> snapshot deletion) are discarded.
> 
> Kevin Wolf (5):
>    Revert "block: Disable driver-specific options for 1.5"
>    qcow2: Add refcount update reason to all callers
>    qcow2: Options to enable discard for freed clusters
>    qcow2: Batch discards
>    block: Always enable discard on the protocol level
> 
>   block.c                  |   2 +-
>   block/qcow2-cluster.c    |  38 +++++++++----
>   block/qcow2-refcount.c   | 139 ++++++++++++++++++++++++++++++++++++++++-------
>   block/qcow2-snapshot.c   |   6 +-
>   block/qcow2.c            |  30 +++++++++-
>   block/qcow2.h            |  32 ++++++++++-
>   blockdev.c               | 118 ++--------------------------------------
>   tests/qemu-iotests/group |   2 +-
>   8 files changed, 214 insertions(+), 153 deletions(-)
> 


-- 
Best Regards

Wenchao Xia