[libvirt PATCH 0/4] storage: support controlling COW attribute for pool

[Neal Gompa]

On Mon, Jul 20, 2020 at 1:33 PM Daniel P. Berrangé <berrange at 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 at gmail.com>


-- 
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