Add APIs that allow to dynamically register driver backends so that the
list of available drivers does not need to be known during compile time.
This will allow us to modularize the storage driver on runtime.
We support gluster volumes in domain XML, so we also ought to
support them as a storage pool. Besides, a future patch will
want to take advantage of libgfapi to handle the case of a
gluster device holding qcow2 rather than raw storage, and for
that to work, we need a storage backend that can read gluster
storage volume contents. This sets up the framework.
Note that the new pool is named 'gluster' to match a
<disk type='network'><source protocol='gluster'> image source
already supported in a <domain>; it does NOT match the
<pool type='netfs'><source><target type='glusterfs'>,
since that uses a FUSE mount to a local file name rather than
a network name.
This and subsequent patches have been tested against glusterfs
3.4.1 (available on Fedora 19); there are likely bugs in older
versions that may prevent decent use of gfapi, so this patch
enforces the minimum version tested. A future patch may lower
the minimum. On the other hand, I hit at least two bugs in
3.4.1 that will be fixed in 3.5/3.4.2, where it might be worth
raising the minimum: glfs_readdir is nicer to use than
glfs_readdir_r [1], and glfs_fini should only return failure on
an actual failure [2].
[1] http://lists.gnu.org/archive/html/gluster-devel/2013-10/msg00085.html
[2] http://lists.gnu.org/archive/html/gluster-devel/2013-10/msg00086.html
* configure.ac (WITH_STORAGE_GLUSTER): New conditional.
* m4/virt-gluster.m4: new file.
* libvirt.spec.in (BuildRequires): Support gluster in spec file.
* src/conf/storage_conf.h (VIR_STORAGE_POOL_GLUSTER): New pool
type.
* src/conf/storage_conf.c (poolTypeInfo): Treat similar to
sheepdog and rbd.
(virStoragePoolDefFormat): Don't output target for gluster.
* src/storage/storage_backend_gluster.h: New file.
* src/storage/storage_backend_gluster.c: Likewise.
* po/POTFILES.in: Add new file.
* src/storage/storage_backend.c (backends): Register new type.
* src/Makefile.am (STORAGE_DRIVER_GLUSTER_SOURCES): Build new files.
* src/storage/storage_backend.h (_virStorageBackend): Documet
assumption.
Signed-off-by: Eric Blake <eblake@redhat.com>
