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SubjectRe: [Unionfs] Re: [PATCH -mm] unionfs: build fixes
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On Tue, 2008-07-29 at 21:02 -0400, Erez Zadok wrote:
> In message <20080729172216.84e958f7.akpm@linux-foundation.org>, Andrew Morton writes:
> > On Tue, 29 Jul 2008 19:12:47 +0100 (BST)
> > Hugh Dickins <hugh@veritas.com> wrote:
> >
> > > Get unionfs building and working in mmotm with the 2.6.27-rc1 VFS changes:
> > > permission() has been replaced by inode_permission() without nameidata arg;
> > > unionfs_permission() without nameidata arg; vfs_symlink() without mode arg;
> > > LOOKUP_ACCESS no longer defined; and kmem_cache_create() no longer passes
> > > kmem_cachep to the init_once() constructor.
> > >
> > > Note: while okay for inclusion in -mm for now, unionfs_permission() mods
> > > will need review and perhaps correction by Erez: without a nameidata arg,
> > > some locking vanishes from unionfs_permission(), and a MNT_NOEXEC check on
> > > its lower_inode; I have not studied the VFS changes enough to tell whether
> > > that amounts to a real issue for unionfs, or just removal of dead code.
> >
> > thanks.
> >
> > > This should follow git-unionfs.patch
> > > I notice my unionfs-fix-memory-leak.patch
> > > and fsstack-fsstack_copy_inode_size-locking.patch
> > > are currently commented out, yet I don't recall the
> > > mm-commits dispatch rider bringing me a telegram to explain why?
> >
> > git-unionfs got commented out because of some upstream git (or build)
> > catastrophe. So its fixes got comemnted out too. Then git-unionfs was
> > restored but I forgot to manually restore the followon fixes. It
> > happens.
>
> Shortly I'm going to post fixes which include Hugh's stuff and more. Sorry
> for the delay.
>
> > I must say that I'm not really sure why we're struggling along with
> > unionfs. Last I heard there were fundamental, unresolveable design
> > disagreements with the VFS guys. Those issues should be where 100% of
> > the effort is being devoted, but instead we seem to be cruising along
> > in a different direction?
>
> Some of my upcoming patches begin to address this (took longer than
> expected):
>
> - extracting all whiteout related code into callable methods in unionfs, so
> that I can "drop in" the new whiteout code that Bharata et al. are
> reportedly working on. I really hope to see some new whiteout code in -mm
> soon. Bharata?
>
> - reworking the lookup code to handle vfsmounts: this'll be needed when we
> switch from vfs_* to path_* (Miklos's patches).
>
> As for other fundamental issues, I've been posting some suggestions in
> recent months. For example
>
> - the need for cleaner handling of vma->fault(), a relatively minor patch I
> posted, based on hch's LSF08 suggestions. Got no response from any of the
> VFS folks.
>
> - a post I made regarding suggestions on how to handle lower f/s changes,
> based on Viro's LSF08 comments: to have a superblock level writers count
> (I suggested that it's a superset of the superblock->s_vfs_rename_mutex,
> and perhaps be elevated to be one). Again, got no responses from anyone
> on the VFS team.

Erez, do you have links to email threads or a commentary of the things
that are causing concern somewhere?

I spotted one but it seems light on for descriptive value (or maybe it's
me who's light on for understanding, ;)).

>
> So I'm not sure how much the VFS guys have time now to review such patches
> and help me address these issues. We can't seem to get through even simpler
> issues, nor get simple patches merged (ala the copy_inode_size) despite
> repeated attempts.

Yeah, life is like that a lot for me too.

But why not assume that, given a reasonable amount of time, a "no
response" is equivalent to a "no complaints" and push on with the
updates. Sooner or later someone who cares enough will take a look and
give the needed feedback.

Ian




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