Re: [PATCH 4/4] block/file: Add file-specific image info

[Hanna Reitz <hreitz@redhat.com>]

On 04.05.22 10:46, Kevin Wolf wrote:
> Am 03.05.2022 um 16:55 hat Hanna Reitz geschrieben:
>> Add some (optional) information that the file driver can provide for
>> image files, namely the extent size.
>>
>> Signed-off-by: Hanna Reitz <hreitz@redhat.com>
>> ---
>>   qapi/block-core.json | 26 ++++++++++++++++++++++++--
>>   block/file-posix.c   | 30 ++++++++++++++++++++++++++++++
>>   2 files changed, 54 insertions(+), 2 deletions(-)
>>
>> diff --git a/qapi/block-core.json b/qapi/block-core.json
>> index e7d6c2e0cc..728da051ae 100644
>> --- a/qapi/block-core.json
>> +++ b/qapi/block-core.json
>> @@ -139,16 +139,29 @@
>>         '*encryption-format': 'RbdImageEncryptionFormat'
>>     } }
>>   
>> +##
>> +# @ImageInfoSpecificFile:
>> +#
>> +# @extent-size: Extent size (if available)
>> +#
>> +# Since: 7.1
>> +##
>> +{ 'struct': 'ImageInfoSpecificFile',
>> +  'data': {
>> +      '*extent-size': 'size'
>> +  } }
> It's not "the extent size" (the whole point of extents is that they
> don't have a fixed size like blocks), but an extent size *hint* that
> tells the filesystem the minimum size to allocate for an extent. The
> xfs_io man page calls it the preferred extent size for allocatino, which
> works for the documentation if you prefer, but BlockdevCreateOptionsFile
> has 'extent-size-hint', so I'd prefer consistency on the wire at least.

Got it.