On Thu, Jul 21, 2011 at 11:07 AM, Jes Sorensen <Jes.Sorensen@redhat.com> wrote:
On 07/20/11 21:51, Blue Swirl wrote:
a new qcow2 image on the fly, while referencing the name of an existing file. What backing name do you put in the new qcow2 file unless you already have a name association for all fds already open for the existing backing file? For backing file with original name of "/path/in/storage", QEMU could
And the snapshot_blkdev monitor command is a case where qemu needs to create present the fd and the backin path by requesting something like "fd:12,/path/in/storage". The next file in chain "/path2/file" would be "fd:12,fd:34,/path2/file". Or if possible, -fd 12 -backing /path/in/storage with spaces and funny characters escaped etc.
Rather than trying to do this by mangling files on the disk, I would suggest we allow registering a call-back open function, which calls back into libvirt and requests it to open a given file. It can then do all it's security foo to decide whether or not to allow the file to be open.
Just to clarify: I was not proposing any mangling of the files.
This is relatively clean and avoids the mess of relying on outside processes messing about in the images.
Cheers, Jes