On Tue, Aug 19 2025, Chunsheng Luo wrote:
> On Mon, 7 Jul 2025 16:34:13 Luis Henriques wrote:
>
>>+static void fuse_dentry_tree_add_node(struct dentry *dentry)
>>+{
>>+ struct fuse_conn *fc = get_fuse_conn_super(dentry->d_sb);
>>+ struct fuse_dentry *fd = dentry->d_fsdata;
>>+ struct fuse_dentry *cur;
>>+ struct rb_node **p, *parent = NULL;
>>+ bool start_work = false;
>>+
>>+ if (!fc->inval_wq)
>>+ return;
>
> First check.
>
>>+
>>+ spin_lock(&fc->dentry_tree_lock);
>>+
>>+ if (!fc->inval_wq) {
>>+ spin_unlock(&fc->dentry_tree_lock);
>>+ return;
>>+ }
>
> Check again.
>
> I don't think the if (!fc->inval_wq) check needs to be re-evaluated
> while holding the lock. The reason is that the inval_wq variable
> doesn't appear to require lock protection. It only gets assigned
> during fuse_conn_init and fuse_conn_destroy. Furthermore,
> in fuse_conn_destroy we set inval_wq to zero without holding a lock,
> and then synchronously cancel any pending work items.
>
> Therefore, performing this check twice with if (!fc->inval_wq)
> seems unnecessary.
Thank you for your feedback, Chunsheng. Having two checks here was just a
small optimisation, the second one is the _real_ one. So yeah, I guess
it's fine to drop the first one.
Cheers,
--
Luís
> Also, in the subject, it would be more appropriate to change
> "work queue" to "workqueue".
>
> Thanks
> Chunsheng Luo
>
>>+
>>+ start_work = RB_EMPTY_ROOT(&fc->dentry_tree);
>>+ __fuse_dentry_tree_del_node(fc, fd);
>>+
>>+ p = &fc->dentry_tree.rb_node;
>>+ while (*p) {
>>+ parent = *p;
>>+ cur = rb_entry(*p, struct fuse_dentry, node);
>>+ if (fd->time > cur->time)
>>+ p = &(*p)->rb_left;
>>+ else
>>+ p = &(*p)->rb_right;
>>+ }
>>+ rb_link_node(&fd->node, parent, p);
>>+ rb_insert_color(&fd->node, &fc->dentry_tree);
>>+ spin_unlock(&fc->dentry_tree_lock);
>>+
>>+ if (start_work)
>>+ schedule_delayed_work(&fc->dentry_tree_work,
>>+ secs_to_jiffies(fc->inval_wq));
>>+}
