On Mon, Jul 20, 2020 at 1:33 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> We already support a "nocow" flag for storage volumes, but this requires
> extra work by the mgmt app or user when creating images on btrfs. We
> want to "do the right thing" out of the box for btrfs.
>
> We achieve this by changint the storage pool code so that when creating
> a storage pool we always try to disable COW on btrfs filesystems. We
> then add an <cow state="yes|no"/> feature in the pool XML to let apps
> override the default logic.
>
> The COW setting on the pool is inherited by any volumes.
>
> The main thing not solved here is that the default directory at
> /var/lib/libvirt/images is created by the RPM itself, not by a
> normal "pool-build" command.
>
> Fortunately it appears that virt-install will explicitly invoke a
> storage pool build even if the directory already exists.
>
> Daniel P. Berrangé (4):
> util: add a helper method for controlling the COW flag on btrfs
> storage: convert to use virFileSetCOW
> storage: attempt to disable COW by default
> conf: add control over COW for storage pool directories
>
> docs/formatstorage.html.in | 25 +++++++
> docs/schemas/storagepool.rng | 30 ++++++++
> src/conf/storage_conf.c | 49 +++++++++++++
> src/conf/storage_conf.h | 8 +++
> src/libvirt_private.syms | 1 +
> src/storage/storage_util.c | 46 +++++-------
> src/util/virfile.c | 76 ++++++++++++++++++++
> src/util/virfile.h | 3 +
> tests/storagepoolxml2xmlin/pool-dir-cow.xml | 10 +++
> tests/storagepoolxml2xmlout/pool-dir-cow.xml | 15 ++++
> tests/storagepoolxml2xmltest.c | 1 +
> 11 files changed, 237 insertions(+), 27 deletions(-)
> create mode 100644 tests/storagepoolxml2xmlin/pool-dir-cow.xml
> create mode 100644 tests/storagepoolxml2xmlout/pool-dir-cow.xml
>
Patch series looks fine. Tested it and it seemed to automatically do
what I expected on a fresh Fedora Rawhide system.
Reviewed-by: Neal Gompa <ngompa13@gmail.com>
--
真実はいつも一つ！/ Always, there's only one truth!