[libvirt] [PATCH RFC 0/3] Add a "flags" element to storage pool source

https://bugzilla.redhat.com/show_bug.cgi?id=1265694 Posting as an RFC mainly to get buyin/feedback over the concept of using a <flags> field in the <pool> <source> as a way to allow or direct the pool/storage backend code to use specific algorithms. The issue is described in the bz, but the shorter version is the disk backend needs a way to tell libvirt_parthelper to format output for dm-multipath volumes in a slight different manner. In order to do that I chose a new flag to call libvirt_parthelper to indicate the way to output, but I needed a way to have the disk backend determine whether to add the flag or not. Could have read /etc/multipath.conf - not a good option... Don't want to read their config file. If there was an API to get that data, it would have been nice, but then we'd have to rely on a specific version of multipath that had the API (a dependency that we don't want). So I chose to roll our own. I figure there could be other uses of such kind of flags - for example currently logical volume pools use a model of thin volume support that is "older". A newer model is there, but IIRC the "format" of the lvs output wouldn't mesh. So if there was a way to say, use this format of support in preference, then we could easily add that support with the caveat that one couldn't expect an "old" thin pool to work. IOW, use the much improved algorithm knowing that it's a "new" pool rather than having to mess with "conversions"... Perhaps other pools may find uses, but this one came to mind since I have a long dormant set of changes that uses the new thin pool options... John Ferlan (3): conf: Add flags to the storage pool source storage: Add new flag for libvirt_parthelper conf: Parse/use a flags argument in the storage pool xml docs/formatstorage.html.in | 33 ++++++++++++++++++++ docs/schemas/storagepool.rng | 9 ++++++ src/conf/storage_conf.c | 41 +++++++++++++++++++++++++ src/conf/storage_conf.h | 11 +++++++ src/storage/parthelper.c | 15 +++++++-- src/storage/storage_backend_disk.c | 7 +++++ tests/storagepoolxml2xmlin/pool-disk-flags.xml | 15 +++++++++ tests/storagepoolxml2xmlout/pool-disk-flags.xml | 15 +++++++++ tests/storagepoolxml2xmltest.c | 1 + 9 files changed, 144 insertions(+), 3 deletions(-) create mode 100644 tests/storagepoolxml2xmlin/pool-disk-flags.xml create mode 100644 tests/storagepoolxml2xmlout/pool-disk-flags.xml -- 2.5.0