On 03/23/2016 08:16 AM, Denis V. Lunev wrote: > From: Pavel Borzenkov <pborzen...@virtuozzo.com> > > With the availability of sparse storage formats, it is often needed to > query status of a particular LBA range and read only those blocks of > data that are actually present on the block device. > > To provide such information, the patch adds GET_LBA_STATUS extension > with one new NBD_CMD_GET_LBA_STATUS command. > > There exists a concept of data dirtiness, which is required during, for > example, incremental block device backup. To express this concept via > NBD protocol, this patch also adds additional mode of operation to > NBD_CMD_GET_LBA_STATUS command. > > Since NBD protocol has no notion of block size, and to mimic SCSI "GET > LBA STATUS" command more closely, it has been chosen to return a list of > extents in the response of NBD_CMD_GET_LBA_STATUS command, instead of a > bitmap. > > Signed-off-by: Pavel Borzenkov <pborzen...@virtuozzo.com> > Reviewed-by: Roman Kagan <rka...@virtuozzo.com> > Signed-off-by: Denis V. Lunev <d...@openvz.org> > CC: Wouter Verhelst <w...@uter.be> > CC: Paolo Bonzini <pbonz...@redhat.com> > CC: Kevin Wolf <kw...@redhat.com> > CC: Stefan Hajnoczi <stefa...@redhat.com> > --- > doc/proto.md | 82 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 82 insertions(+)
I've posted a v2 of this proposal under a new title, rebased on top of the recent work to add structured replies, and trying to take into account a number of the suggestions that occurred in this thread. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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