[libvirt] [PATCH v3 29/31] Introduce virStorageVol{Download, Upload}Flags

[John Ferlan]

On 05/16/2017 10:04 AM, Michal Privoznik wrote:
> These flags to APIs will tell if caller wants to use sparse
> stream for storage transfer. At the same time, it's safe to
> enable them in storage driver frontend and rely on our backends
> checking the flags. This way we can enable specific flags only on
> some specific backends, e.g. enable
> VIR_STORAGE_VOL_DOWNLOAD_SPARSE_STREAM for filesystem backend but
> not iSCSI backend.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  include/libvirt/libvirt-storage.h |  9 +++++++++
>  src/libvirt-storage.c             |  4 ++--
>  src/remote/remote_protocol.x      |  2 ++
>  src/storage/storage_driver.c      |  4 ++--
>  src/storage/storage_util.c        | 10 ++++++----
>  5 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/include/libvirt/libvirt-storage.h b/include/libvirt/libvirt-storage.h
> index 45ec72065..4517f713c 100644
> --- a/include/libvirt/libvirt-storage.h
> +++ b/include/libvirt/libvirt-storage.h
> @@ -346,11 +346,20 @@ virStorageVolPtr        virStorageVolCreateXMLFrom      (virStoragePoolPtr pool,
>                                                           const char *xmldesc,
>                                                           virStorageVolPtr clonevol,
>                                                           unsigned int flags);
> +
> +typedef enum {
> +    VIR_STORAGE_VOL_DOWNLOAD_SPARSE_STREAM = 1 << 0, /* Use sparse stream */
> +} virStorageVolDownloadFlags;
> +
>  int                     virStorageVolDownload           (virStorageVolPtr vol,
>                                                           virStreamPtr stream,
>                                                           unsigned long long offset,
>                                                           unsigned long long length,
>                                                           unsigned int flags);
> +typedef enum {
> +    VIR_STORAGE_VOL_UPLOAD_SPARSE_STREAM = 1 << 0,  /* Use sparse stream */
> +} virStorageVolUploadFlags;
> +

/me wonders should the backend specific concerns be described in
comments prior to each enum or is that too specific. Maybe it's more of
a 'specific backends' that perform "file based manipulation" (rather
than block based)...  I dunno.  I'll leave it to you though - the more
documentation now while it's fresh in your mind the better.


>  int                     virStorageVolUpload             (virStorageVolPtr vol,
>                                                           virStreamPtr stream,
>                                                           unsigned long long offset,
> diff --git a/src/libvirt-storage.c b/src/libvirt-storage.c
> index 05eec8a9d..64202998b 100644
> --- a/src/libvirt-storage.c
> +++ b/src/libvirt-storage.c
> @@ -1549,7 +1549,7 @@ virStorageVolCreateXMLFrom(virStoragePoolPtr pool,
>   * @stream: stream to use as output
>   * @offset: position in @vol to start reading from
>   * @length: limit on amount of data to download
> - * @flags: extra flags; not used yet, so callers should always pass 0
> + * @flags: bitwise-OR of virStorageVolDownloadFlags
>   *
>   * Download the content of the volume as a stream. If @length
>   * is zero, then the remaining contents of the volume after
> @@ -1613,7 +1613,7 @@ virStorageVolDownload(virStorageVolPtr vol,
>   * @stream: stream to use as input
>   * @offset: position to start writing to
>   * @length: limit on amount of data to upload
> - * @flags: extra flags; not used yet, so callers should always pass 0
> + * @flags: bitwise-OR of virStorageVolUploadFlags
>   *
>   * Upload new content to the volume from a stream. This call
>   * will fail if @offset + @length exceeds the size of the

I suppose for each you c(sh)ould have documented what the specific FLAG
does and the expectations therein..

Reviewed-by: John Ferlan <jferlan at redhat.com>

John