On Sun, Feb 22, 2004 at 10:16:52AM -0800, Ram Pai wrote:
> Looking through the xfs dmapi code, 2 questions pop up:
> 1. How can the pre_unmount event, when generated through the put_super()
> code provide the DM_UNMOUNT_FORCE information. There is now way for the
> put_super() code to know if the unmount is a forceful one or not.
It can't.
> 2. And finally I find that all the DMAPI event generators are stubbed
> to fs_nosys or fs_noerr or fs_noval . So does XFS ever generate DM
> events ?
You need to load the xfs_dmapi module to get an implementation. It's
in the CVS repository at oss.sgi.com.
> > Al Viro is distinctly anti dmapi, so chances are slim to none I would
> > say.
>
> hmm...that makes it difficult. Is he against Dmapi implemented in VFS or
> against the overall idea of supporting DMAPI anywhere in linux? I hope
> he is just against DMAPI implemented at the VFS level and is ok with
> supporting filesystems to implement it.
DMAPI is an extremly broken specification, it fits hardly into an unix
enviroment and not into Linux at all. SGI tries to provide a best-fit
dmapi implementation anyways, but it's just not something that should
go into an mainline kernel.
If you want to see HSM support in a kernel.org kernel start by designing
a saner specification than dmapi.
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