Messages in this thread | | | Date | Sat, 30 Sep 2023 09:16:11 +0800 | Subject | Re: [PATCH v3 3/4] add statmount(2) syscall | From | Ian Kent <> |
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On 29/9/23 17:10, Miklos Szeredi wrote: > On Fri, 29 Sept 2023 at 02:42, Ian Kent <raven@themaw.net> 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
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