Thank you Dave, you were definitely right. I used the XFS mount point as
the argument to path_to_fshandle and it now woks perfectly. :-)
This leads me to another question : now that I can convert a path to
fhandle and use it to open a file or a directory, I can use getdents and
the ATFILE_SOURCE functions (mkdirat, linkat, ....) to implement the NFS
logic (I just have to "open_by_handle" to get the fs to the related fs
object and operate on it). The idea behind this is implementing a NFS
server in Userspace with XFS specific capabilites.
In fact, the NFS on which a minor issue remains is LOOKUP (and it could
become a major issue since LOOKUP is called very often). To lookup on an
object knowing its parent directory's handle and its name, I can perform
an "openat" followed by a xfs related "fd_to_handle" and close the fd
once the operation is done. But it seems a bit "heavy" to me. Is there
another (lighter) way of getting the handle to an object knowing its
name and parent directory (may be by a call to xfsctl ?).
Dave Chinner a écrit :
On Wed, May 12, 2010 at 05:39:44PM +0200, DENIEL Philippe wrote:
I start using libhandle.so from xfsprogs-3.0.3 package. I meet an
issue here : I can get a handle from files or directory.
When used on diretories, open_by_handle works fine : I can read
entries in it by using getdents, create stuff / removing stuff by
using the ATFILE_FUNCTION (mkdirat, renameat, ...)
Trouble start when I want to open a file with open_by_handle. I have
a small test program that does this :
rc = path_to_fshandle( path_dir, (void **)(&fshandle),
if( rc < 0 ) exit( -1)
rc = path_to_handle( path_dir, (void **)(&filehandle), &handlelen) ;
if( rc < 0 ) exit( -1 )
fd = open_by_handle( filehandle, handlelen, O_RDONLY ) ;
printf( "open_by_handle: fd=%d \n", fd ) ;
if( fd < 0 )
printf( "----> Error=%d | %s\n", errno, strerror( errno ) ) ;
The open_by_handle failed with errno=20 aka ENOTDIR, which is true,
this is a file and no directory.
I think that is because the path_dir points to a regular file and
so path_to_fshandle() is generating a fshandle that points to a file
instead of a directory. This handle is cached inside libhandle, and
then use for subsequent handle calls like open_by_handle(). The
kernel rejects the request is the fshandle does not point to a
Try using the mount point or a directory within the mount for
the path_to_fshandle() call and see if that fixes the problem.