Re: [PATCH 0/4] Fiemap, an extent mapping ioctl - round 2

[Jamie Lokier <jamie@shareable.org>]

Mark Fasheh wrote:
> On Wed, Jul 02, 2008 at 03:28:54PM +0100, Jamie Lokier wrote:
> > Ok, wouldn't be appropriate to include the extent of the index block
> > as well, somewhere, so that userspace can see which parts of the disk
> > must be read to read the file?
> 
> Mapping meta data doesn't belong in fiemap - we can come up with a dedicated
> interface for that at a future date.

I agree, but it seems inconsistent with the xattr / directory thing.

Because that *is* mapping metadata.  They may have no data blocks;
it's been suggested they return extents covering metadata locations only.

It seems the same use-cases where you might want metadata location
from xattrs and directories apply equally to metadata locations for a
file.  I.e. knowing which parts of a disk will be accessed.

-- Jamie