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




On 05/17/2017 12:30 PM, Michal Privoznik wrote:
> On 05/17/2017 05:42 PM, John Ferlan wrote:
>>
>>
>> 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 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..
> 
> How about this?
> 

Fine -

Reviewed-by: John Ferlan <jferlan redhat com>

John
> iff --git i/src/libvirt-storage.c w/src/libvirt-storage.c
> index 64202998b..35f9926d5 100644
> --- i/src/libvirt-storage.c
> +++ w/src/libvirt-storage.c
> @@ -1555,6 +1555,13 @@ virStorageVolCreateXMLFrom(virStoragePoolPtr pool,
>   * is zero, then the remaining contents of the volume after
>   * @offset will be downloaded.
>   *
> + * If VIR_STORAGE_VOL_DOWNLOAD_SPARSE_STREAM is set in @flags
> + * effective transmission of holes is enabled. This assumes using
> + * the @stream with combination of virStreamSparseRecvAll() or
> + * virStreamRecvFlags(stream, ..., flags =
> + * VIR_STREAM_RECV_STOP_AT_HOLE) for honouring holes sent by
> + * server.
> + *
>   * This call sets up an asynchronous stream; subsequent use of
>   * stream APIs is necessary to transfer the actual data,
>   * determine how much data is successfully transferred, and
> @@ -1621,6 +1628,11 @@ virStorageVolDownload(virStorageVolPtr vol,
>   * will be raised if an attempt is made to upload greater
>   * than @length bytes of data.
>   *
> + * If VIR_STORAGE_VOL_UPLOAD_SPARSE_STREAM is set in @flags
> + * effective transmission of holes is enabled. This assumes using
> + * the @stream with combination of virStreamSparseSendAll() or
> + * virStreamSendHole() to preserve source file sparseness.
> + *
>   * This call sets up an asynchronous stream; subsequent use of
>   * stream APIs is necessary to transfer the actual data,
>   * determine how much data is successfully transferred, and
> 
> Michal
> 


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