On Thu, Sep 5, 2013 at 4:56 PM, Al Viro <v...@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.
Thanks,
Miklos
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