On 29/9/23 17:10, Miklos Szeredi wrote:
On Fri, 29 Sept 2023 at 02:42, Ian Kent <raven@xxxxxxxxxx> wrote:
On 28/9/23 21:01, Miklos Szeredi wrote:
+static struct vfsmount *lookup_mnt_in_ns(u64 id, struct mnt_namespace *ns)
+{
+ struct mount *mnt;
+ struct vfsmount *res = NULL;
+
+ lock_ns_list(ns);
+ list_for_each_entry(mnt, &ns->list, mnt_list) {
+ if (!mnt_is_cursor(mnt) && id == mnt->mnt_id_unique) {
+ res = &mnt->mnt;
+ break;
+ }
+ }
+ unlock_ns_list(ns);
+ return res;
+}
Seems like we might need to consider making (struct mnt_namespace)->list
a hashed list.
Yes, linear search needs to go. A hash table is probably the easiest solution.
But I'd also consider replacing ns->list with an rbtree. Not as
trivial as adding a system hash table and probably also slightly
slower, but it would have some advantages:
- most space efficient (no overhead of hash buckets)
- cursor can go away (f_pos can just contain last ID)
I guess that would be ok.
Avoiding the cursor is a big plus.
An rbtree is used in kernfs and its readdir function is rather painful so
I wonder what the implications might be for other enumeration needs.
Ian
