On 06/18/2013 05:53 AM, Ben Myers wrote:
> Hey Jeff,
> On Thu, Jun 06, 2013 at 06:24:01AM -0700, Jeff Liu wrote:
>> From: Jie Liu <jeff.liu@xxxxxxxxxx>
>> For FIEMAP ioctl(2), if an extent is in delayed allocation
>> state, we need to return the FIEMAP_EXTENT_UNKNOWN flag except
>> the FIEMAP_EXTENT_DELALLOC because its data location is unknown.
>> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
> Looks fine. Is there an email thread I can reference?
I can't found an email thread to verify that, but according to
the specification of fiemap interface in kernel doc:
The location of this extent is currently unknown. This may indicate
the data is stored on an inaccessible volume or that no storage has
been allocated for the file yet.
- This will also set FIEMAP_EXTENT_UNKNOWN.
^^^^^ <-- so the unknown flags should be set as well.
Delayed allocation - while there is data for this extent, its
physical location has not been allocated yet.
Also, Btrfs did it.