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SubjectRe: [PATCH 04/11] vfs: check unlinked ancestors before mount
On Thu, Sep 05, 2013 at 05:52:51PM +0200, Miklos Szeredi wrote:
> On Thu, Sep 5, 2013 at 4:56 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> > I'd probably just do this, and to hell with helper functions...
> >
> > int d_set_mounted(struct dentry *dentry)
> > {
> > struct dentry *p;
> > int ret = 0;
> > write_seqlock(&rename_lock);
> > for (p = dentry; !IS_ROOT(p); p = p->d_parent) {
> > /* Need exclusion wrt. check_submounts_and_drop() */
> > spin_lock(&p->d_lock);
> > if (unlikely(d_unhashed(p))) {
> > spin_unlock(&p->d_lock);
> > ret = -ENOENT;
> > goto out;
> > }
> > spin_unlock(&p->d_lock);
> > }
> > spin_lock(&dentry->d_lock);
> > dentry->d_flags |= DCACHE_MOUNTED;
> > spin_unlock(&dentry->d_lock);
> > out:
> > write_sequnlock(&rename_lock);
> > return ret;
> > }
>
> One issue with that: the dentry should be checked and marked within
> the same d_locked region. Because e.g. d_invalidate() relies solely
> on d_lock for non-dir mounts and d_mountpoint() checking, no
> rename_lock protection there.

Point... OK, could you check if vfs.git#for-miklos looks sane now? It should
be at cf7543f...


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