Re: [PATCH 00/25] vfs: atomic open RFC

From: Christoph Hellwig
Date: Tue Mar 13 2012 - 08:01:36 EST


On Tue, Mar 13, 2012 at 12:00:05PM +0100, Miklos Szeredi wrote:
> > Do we really need the opendata structure?
> >
> > It seems like we could just pass a struct path instead of the dentry
> > passed directly and the vfsmount in it. There should be no need to
> > preallocate the file before calling into ->atomic_open, as it's only
> > used to pass around f_flags - but we already pass that one to
> > ->atomic_open directly and might as well pass it on to finish_open and
> > allocate the file there.
>
> We really don't want to get into the situation where the open fails
> after a successful create(*). Which means the file needs to be allocated
> prior to calling ->atomic_open and needs to be passed to finish_open()
> toghether with the vfsmount and dentry.
>
> In the first version of the patch I set filp->f_path.mnt to nd->path.mnt
> and passed the half initialized filp to ->atomic_open. But then decided
> that it's confusing for the filesystem code to deal with a half baked
> filp (does it need to be fput on error? etc...)
>
> Doing it with an opaque opendata makes this cleaner I think.

Make sense. Can you throw in another cleanup patch to really just make
it a pass-through and not also use it as a boolean flag if open_flags
should be obeyed? This probably will change sematincs for the various
filesystems, but given that they should behave the same way that's a
good thing.
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