Re: [Qemu-devel] [PATCH v2 0/3] hostmem-file: Add "discard-data" option

[Eduardo Habkost]

Series queued on machine-next.

On Thu, Aug 24, 2017 at 04:23:12PM -0300, Eduardo Habkost wrote:
> This series adds a new "discard-data" option to
> memory-backend-file.  The new option will be useful if somebody
> is sharing RAM contents on a pre-existing file using share=on,
> but don't need data to be flushed to disk when QEMU exits.
> 
> Internally, it will trigger a madvise(MADV_REMOVE) call when the
> memory backend is removed or when QEMU exits.
> 
> To make we actually trigger the new code when QEMU exits, the
> first patch in the series ensures we destroy all user-created
> objects when exiting QEMU.
> 
> Changes v1 -> v2:
> * Original subject line of v1 was:
>   '[PATCH 0/5] hostmem-file: Add "persistent" option'
> * Replaced 'persistent=no' with 'discard-data=yes', to make it
>   clear that the flag will destroy data on the backing file.
> * Use qemu_madvise() instead of madvise()
>   * New patch added to series: "osdep: define QEMU_MADV_REMOVE"
> * Call qemu_madvise() directly from the backend unparent()
>   method, insteead of adding a new flag to the memory API and
>   reusing ram_block_discard_range()
>   * In addition to simplifying the code a lot, this fixes a bug,
>     because v1 relied on getting the memory region reference
>     count back to 0, which doesn't happen when QEMU is exiting
>     because there's no machine cleanup code to ensure that.
> 
> Eduardo Habkost (3):
>   vl: Clean up user-creatable objects when exiting
>   osdep: Define QEMU_MADV_REMOVE
>   hostmem-file: Add "discard-data" option
> 
>  include/qemu/osdep.h            |  7 +++++++
>  include/qom/object_interfaces.h |  8 ++++++++
>  backends/hostmem-file.c         | 29 +++++++++++++++++++++++++++++
>  qom/object_interfaces.c         |  5 +++++
>  vl.c                            |  1 +
>  qemu-options.hx                 |  5 ++++-
>  6 files changed, 54 insertions(+), 1 deletion(-)
> 
> -- 
> 2.9.4
> 
> 

-- 
Eduardo