Re: [PATCH v4 0/5] ceph: reduce mdsc->mutex contention in the cephfs kclient

Hi Alex,

Thanks for the feedback and for spotting those issues in patch 4 and
5. You are right, I will fix them and respin as v5.

Thanks
- Xiubo

On Mon, 17 Aug 2026 at 04:05, Alex Markuze <[email protected]> wrote:
>
> Hi Xiubo,
>
> Patches 1-4 look good — the xarray replacement and the wait_list_lock
> are clean, and the mutex narrowing is the right direction. One blocker
> in patch 5:
>
> replay_unsafe_requests() calls list_del_init(&req->r_unsafe_item) before
> parking the request on the local walk list via r_aux_item. That permanently
> removes the request from session->s_unsafe. After replay, the request is
> no longer tracked as unsafe — subsequent reconnects won't replay it, and
> cleanup_session_requests() can't drop it with -EIO on session teardown.
> The request can get stuck in the xarray with no error surfaced to userspace.
>
> The fix is to not unlink from s_unsafe at all — just add to the local list
> via r_aux_item and leave r_unsafe_item in place. That's the whole point of
> having r_aux_item.
>
> Also r_aux_item is added to the struct in patch 4 but never initialized
> with INIT_LIST_HEAD() in ceph_mdsc_create_request().
>
> Could you respin as v5?
>
> --
> Alex Markuze
>