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@xxxxxxxxxx>
>> ---
>> 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?
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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