Am 19.09.2013 um 10:26 hat Stefan Hajnoczi geschrieben: > On Wed, Sep 18, 2013 at 05:05:27PM +0200, Benoît Canet wrote: > > Le Tuesday 17 Sep 2013 à 14:44:13 (+0200), Stefan Hajnoczi a écrit : > > > Hi Benoit, > > > Kevin and I had a chance to chat face-to-face and we discussed what > > > concrete changes are necessary to merge quorum (without solving all the > > > other block layers problems at once). > > > > > > I think quorum could be merged relatively quickly (and without massive > > > BlockFilter investments) by changing the following: > > > > > > 1. Defining children on the command-line > > > > > > Existing "filter" drivers use the protocol filename to embed their > > > children, for example the blkverify driver. This is a big hack because > > > we have no proper syntax or escaping for the embedded drive definitions > > > in the file= option. > > > > > > This was one of the main arguments against merging quorum. Now that > > > Kevin has implemented driver-specific open options (see > > > block/qcow2.c:qcow2_runtime_opts), it is possible for the quorum driver > > > to open children specific on the command-line: > > > > > > -drive if=none,file.driver=quorum,format=raw,\ > > > file.children0.file=/nfs1/test.qcow2,\ > > > file.children1.file=/nfs2/test.qcow2,\ > > > file.children2.file=/nfs3/test.qcow2
By the way, I think he concrete syntax might have to be a bit different so it can be mapped to QAPI for blockdev-add. I think we'll want to use a JSON list for the children; a mapping to QDict and to the command line is yet to be implemented I guess. You can use my blockdev development branch if you want to play with the QAPI part: git://repo.or.cz/qemu/kevin.git blockdev > > Hello Stefan, > > > > I started writing the code. > > > > How would the quorum treshold be specified with this command line style ? > > Kevin can correct me but I think: > > -drive ...,file.vote_threshold=2 > > BlockDrivers can have custom options. The voting threshold is a good > example. > > quorum_open() can check for "vote_threshold" in its options qdict. Yup, that's the right way. Kevin
