Question : Using libhandle from xfsprogs and xfs actions made "by handle"

[Christoph Hellwig]

On Wed, May 05, 2010 at 03:54:59PM +0200, DENIEL Philippe wrote:
> When looking at XFS, I saw there was "open_by_handle" and  
> "path_to_handle" calls. This sounds very very good to me : this sounds  
> like kind of bridge to build a handle-based API to address XFS. But so  
> far, I am a bit stuck : for exporting XFS through my NFS server, I would  
> need to do "by handle" everything that can be done through POSIX calls,  
> open/read/write/close files, create files/directories/symlinks, erasing  
> or moving files... and so on. I do not know if this is possible with the  
> calls in libhandle.so. But if I had such handle based tools, I think I  
> could make a nice NFS server on top of XFS (I did this kind of port for  
> LUSTRE (which has a full handle based API) in my NFS server and I had  
> really good performances). Can someone provide me with information about  
> this ?

For some reason the handle code currently rejects special files
(block/char/fifo) in open_by_handle.  I can't see any good reason for
that and plan to submit a patch to lift that restriction.  Except
for that libhandle is exactly what you want - there's various tools
that use it for that kind of work, the most prominent is
xfsdump/xfsrestore.