Hi Bernd,
Thank you for taking time to review this issue.
I'm writing to inquire about any recent updates or plans for atomic
open threads?
It will help a lot if the negative d_entry issue could be solved.
Best,
Yuan
On Mon, Feb 19, 2024 at 8:37 PM Bernd Schubert
<bernd.schubert@xxxxxxxxxxx> wrote:
>
>
>
> On 2/9/24 08:46, Yuan Yao wrote:
> > Hi Bernd,
> >
> > Thank you for taking a look at this patch! I appreciate it a lot for
> > adding this patch to the next version. However, I just found that
> > there’s a bug with my patch. The *BUG_ON(!d_unhashed(dentry));* in
> > d_splice_alias() function will be triggered when doing the parallel
> > lookup on a non-exist file.
> >
> >> struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
> >> {
> >> if (IS_ERR(inode))
> >> return ERR_CAST(inode);
> >>
> >> BUG_ON(!d_unhashed(dentry));
> >
> > This bug can be easily reproduced by adding 3 seconds sleep in fuse
> > server’s atomic_open handler, and execute the following commands in
> > fuse filesystem:
> > cat non-exist-file &
> > cat non-exist-file &
> >
> > I think this bug can be addressed by following two approaches:
> >
> > 1. adding check for d_in_lookup(entry)
> > -----------------------------------------------------------------------
> > if (outentry.entry_valid) {
> > + if (d_in_lookup(entry)) {
> > inode = NULL;
> > d_splice_alias(inode, entry);
> > fuse_change_entry_timeout(entry, &outentry);
> > + }
> > goto free_and_no_open;
> > }
> >
> > 2. adding d_drop(entry)
> > -----------------------------------------------------------------------
> > if (outentry.entry_valid) {
> > inode = NULL;
> > + d_drop(entry)
> > d_splice_alias(inode, entry);
> > fuse_change_entry_timeout(entry, &outentry);
> > goto free_and_no_open;
> > }
> >
> > But I'm not so sure which one is preferable, or maybe the handling
> > should be elsewhere?
> >
>
> Sorry for my terribly late reply, will look into it in the evening.
>
>
> Thanks,
> Bernd
