Re: [libvirt] RFC: API additions for enhanced snapshot support
On Thu, Jul 7, 2011 at 8:34 PM, Eric Blake <eblake(a)redhat.com> wrote:
On 07/07/2011 03:13 AM, Stefan Hajnoczi wrote:
> On Wed, Jul 6, 2011 at 3:03 PM, Eric Blake <eblake(a)redhat.com> wrote:
>> In other words, it looks like we are stuck with updating XML to track
>> new file names any time we take a snapshot.
>
> Yes, but QEMU's snapshot_blkdev command takes a filename argument so
> at least you get to specify that new filename.
Well, the best thing (from libvirt's point of view) would be if
snapshot_blkdev took a single string argument, which is either a
/path/to/filename (and qemu does open()) or fd:name notation (to refer
to a previously-named fd passed via the getfd monitor command, so that
libvirt does open()). This would make SELinux integration easier, as
one of the sVirt goals is to get to the point where we can use SELinux
to forbid qemu from open()ing files on NFS shares, while still
permitting all other operations on already-open fds passed in from libvirt.
Today QEMU supports /path/to/filename. An fd argument to
snapshot_blkdev requires a little bit of work since the QEMU block
layer .bdrv_create() interface takes a filename and tries to create
it.
Jes: Is the fd argument to snapshot_blkdev in your plans?
Stefan