[libvirt] [PATCH 6/6] storage:dir: adapts .refreshVol .refreshPool for ploop volumes

[Ján Tomko]

On Wed, Feb 17, 2016 at 02:40:05PM +0300, Olga Krishtal wrote:
> To update information about ploop volumes inside the a single pool we need
> to be sure that it is the ploop directory and not some other directory.
> Ploop volume directory obligatory contains root.hds - image file and disk
> descriptor - DiskDescriptor.xml. If path to a volume is a path to some
> directory, we check the existance of this files.
> 

With each ploop volume being a directory with a ploop disk image and the
XML, I think they deserve a separate pool type.
The ploop image (root.hds) could be detected as such by the fs pool,
but creating and deleting the directories feels out of place in this
backend.

Also, this should be documented in docs/storage.html.in, maybe with some
examples.

> The capacity of a ploop volume is obtained via offset
> in the header file:
> https://openvz.org/Ploop/format
> 
> Signed-off-by: Olga Krishtal <okrishtal at virtuozzo.com>
> ---
>  src/storage/storage_backend.c         | 92 ++++++++++++++++++++++++++---------
>  src/storage/storage_backend.h         |  2 +-
>  src/storage/storage_backend_fs.c      |  6 ++-
>  src/storage/storage_backend_logical.c |  2 +-
>  src/util/virstoragefile.c             |  9 +++-
>  5 files changed, 84 insertions(+), 27 deletions(-)
> 

> @@ -1636,6 +1661,18 @@ virStorageBackendVolOpen(const char *path, struct stat *sb,
>          virReportError(VIR_ERR_INTERNAL_ERROR,
>                         _("Volume path '%s' is a socket"), path);
>          return -1;
> +    } else if (S_ISDIR(sb->st_mode)) {
> +        if (virStorageBackendIsPloopDir(path)) {
> +            if (virAsprintf(&ploop_path, "%s/%s", target->path, "root.hds") < 0)
> +                return -1;
> +            path = ploop_path;
> +            target->format = VIR_STORAGE_FILE_PLOOP;

virStorageBackendVolOpen should be just opening the volume, not probing
its format.


Also, this is not really a 'ploop file', but a 'ploop dir' - wouldn't
the lone disk images matching the magic in virstoragefile.c be
indistinguishable form the directories?

> +            if (lstat(path, sb) < 0) {
> +                FAILED_STAT(path, ret);
> +                VIR_FREE(ploop_path);
> +                return ret;
> +            }
> +        }
>      }
>  
>      /* O_NONBLOCK should only matter during open() for fifos and

> diff --git a/src/storage/storage_backend.h b/src/storage/storage_backend.h
> index 65e91dc..de48012 100644
> --- a/src/storage/storage_backend.h
> +++ b/src/storage/storage_backend.h
> @@ -203,7 +203,7 @@ enum {
>  # define VIR_STORAGE_VOL_OPEN_DEFAULT (VIR_STORAGE_VOL_OPEN_REG      |\
>                                         VIR_STORAGE_VOL_OPEN_BLOCK)
>  
> -int virStorageBackendVolOpen(const char *path, struct stat *sb,
> +int virStorageBackendVolOpen(virStorageSourcePtr target, struct stat *sb,
>                               unsigned int flags)

This should not be needed if the format is detected outside
virStorageBackendVolOpen.

Jan