Re: [Review] Fixes to the VFS layer

[Francois Tigeot <ftigeot@xxxxxxxxxxxx>]

Francois Tigeot wrote:
> Alex Hornung wrote:
> > as I said previously on IRC I disagree with this approach to statfs and
> > hence to your first two patches. You should be using the statfs entry
> > point and not inspect the statfs structure in the mount point.
> >
> > For that, you need to simply fix the right thing, which would be the
> > VOP_STATFS entry of nullfs and make it populate the fields you need as
> > you expect.
>
> To be honest, I had forgotten about this conversation; I'll try to
> replace the direct struct mount accesses by the use of VOP_STATFS.

I'm focusing on the first patch for now, the one which initializes 
mp->mnt_stat.f_mntonname from nullfs_mount()

> > That the stat field in the mount point is not populated as you would
> > like it is *not* a bug and doesn't really need fixing, you should be
> > using the right approach instead, one that is using the API instead of
> > raw accesses.

Guess where VOP_STATFS takes the values it returns ? From mp->mnt_stat :
http://opengrok.wolfpond.org/source/xref/sys/vfs/nullfs/null_vfsops.c#nullfs_statfs

nullfs_statfs is a very simple function; it only copies existing values.

The initial name of the mount point can only be known from the 
nullfs_mount function; if this patch is not applied, VOP_STATFS will 
never be able to return the correct values.

I'm afraid patch-0008 has to be applied.

--
Francois Tigeot