On 08/21, Andy Lutomirski wrote:
>
> On Wed, Aug 21, 2013 at 11:20 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> > Can't really comment the patch, just a nit:
> >
> > On 08/21, Andy Lutomirski wrote:
> >>
> >> +static bool may_flink(const struct path *path)
> >> +{
> >> + bool ret;
> >> + struct inode *inode = path->dentry->d_inode;
> >> +
> >> + /*
> >> + * This is racy: I_LINKABLE could be cleared between this check
> >> + * and the actual link operation.
> >
> > OK,
> >
> >> + spin_lock(&inode->i_lock);
> >> + ret = !!(inode->i_state & I_LINKABLE);
> >> + spin_unlock(&inode->i_lock);
> >
> > so why do we need to take a lock ?
> >
>
> We probably don't. But other accesses to this field take that lock,
Not if you only need to check ->i_lock,
> (In principle, someone could take the lock, write I_LINKABLE, clear
> it, and unlock, and we'd get confused if we didn't take the lock
> ourselves.)
Or it can be cleared right after we drop i_lock, I do not think there
is any difference.
But OK, I won't argue.
Oleg.
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