Re: [Xen-devel] [PATCH v4 1/5] define snapshot API

["Bamvor Jian Zhang" <bjzhang@xxxxxxxx>]

Hi, Chunyan
> >>> On 6/23/2014 at 07:25 PM, in message
> <1403522755-6894-2-git-send-email-bjzhang@xxxxxxxx>, Bamvor Jian Zhang
> <bjzhang@xxxxxxxx> wrote:
> > it includes two parts APIs: domain snapshot configuration file operation
> > (load, store, delete, it base on Wei Liu's libxl-json api) and disk
> > snapshot operation(create, delete, revert, including implementation
> > details: choose qmp or qemu-img command).
> >
> > about xl and libvirt cooperation. currently, libvirt use xml for description
> > domain snapshot for both user interface and store the snapshot information
> > on disks. if libvirt libxl driver could use libxl-json format in load/store
> > domain snapshot configuration, it would be easier for the user who may be
> > switch xl and libvirt. this will not affect the libvirt user experience.
> >
> > Signed-off-by: Bamvor Jian Zhang <bjzhang@xxxxxxxx>
> > ---
> >  tools/libxl/libxl.h | 37 +++++++++++++++++++++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> >
> > diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
> > index be722b6..8106f4b 100644
> > --- a/tools/libxl/libxl.h
> > +++ b/tools/libxl/libxl.h
> > @@ -1261,6 +1261,43 @@ int libxl_load_domain_configuration(libxl_ctx *ctx,
> > uint32_t domid,
> >  int libxl_store_domain_configuration(libxl_ctx *ctx, uint32_t domid,
> >                                       libxl_domain_config *d_config);
> >
> > +/* snapshot relative APIs */
> > +
> > +/* management functions for domain snapshot configuration */
> > +
> > +/* Load, save, delete domain snapshot configuration file. */
> > +int libxl_load_dom_snapshot_conf(libxl_ctx *ctx, uint32_t domid,
> > +                                    libxl_domain_snapshot *snapshot);
> > +int libxl_store_dom_snapshot_conf(libxl_ctx *ctx, uint32_t domid,
> > +                                     libxl_domain_snapshot *snapshot);
> > +int libxl_delete_dom_snapshot_conf(libxl_ctx *ctx, uint32_t domid,
> > +                                   libxl_domain_snapshot *snapshot);
>
> Do we need libxl_domain_snapshot as parameter here? Why not
> 'ctx, domid, snapshot-name'?
yes, i only need the name of snapshot for deleting. i put libxl_domain_snapshot
here in order to consistent with load and store functions above.
>
> > +
> > +/* retrieve all the snapshot information from disk, put the number of it to
> > num.
>
> Typo  here. Is it to retrieve the snapshot info of the domain?
> If  domain has 2 snapshots, return the 2 snapshots' info and set num=2.
yes. thanks.
>
> > + * caller is responsible for free the libxl_domain_snapshot array.
> > + */
> > +libxl_domain_snapshot *libxl_domain_snapshot_list(libxl_ctx *ctx,
> > +                                                  uint32_t domid, int
> > *num);
> > +
> > +/* functions for disk snapshot operations */
> > +/* create disk snapshot through qmp transaction */
> > +int libxl_disk_snapshot_create(libxl_ctx *ctx, int domid,
> > +                               libxl_disk_snapshot *snapshot, int nb);
> > +
> > +/* delete disk snapshot through qmp delete */
> > +int libxl_disk_snapshot_delete(libxl_ctx *ctx, int domid,
> > +                               libxl_disk_snapshot *snapshot, int nb);
> > +
> > +/* revert disk snapshot through qemu-img snapshot apply command */
> > +int libxl_disk_snapshot_revert(libxl_ctx *ctx, uint32_t domid,
> > +                               libxl_disk_snapshot *snapshot, int nb);
> > +
> > +/* create libxl_disk_snapshot from libxl_device_disk
> > + * will alloc disks if disks empty
> > + */
> > +int libxl_disk_to_snapshot(libxl_ctx *ctx, uint32_t domid,
> > +                           libxl_domain_snapshot *snapshot);
>
> What is this function for? And how would we use it? It's better to have some
> explanation to the functionality and the parameters.
sorry for confuse. this function will save disk parameter to libxl_disk_snapshot
from libxl_diskinfo. reference my next reply for structure definition.
libxl_disk_to_snapshot will get disk list through libxl_device_disk_list, and
get libxl_diskinfo through libxl_device_disk_getinfo. and it will only process
the disk support snapshot in current implementaiton. e.g.
for internal snapshot: only qcow2 is supported.
for external snapshot: raw and qcow2 is supported.

regards

bamvor


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