On Sat, Dec 07, 2024 at 12:36:07AM +0100, Martin Wilck wrote:
> We previously didn't allow map removal inside the checker loop. But
> with the late updates to the checkerloop code, it should be safe to orphan
> paths and delete maps even in this situation. We remove such maps everywhere
> else in the code already, whenever refresh_multipath() or setup_multipath()
> is called.
I don't think that this is safe. It's possible that the multipath device
has paths in the INIT_REMOVED or INIT_PARTIAL state. These will get
silently removed from the pathvec if we remove the map here. This will
mess up our iteration through the pathvec in update_paths(). Perhaps a
better idea would be to set mpp->sync_ticks to 0 if
update_multipath_strings() fails in do_sync_mpp(). This would force a
refresh by sync_mpp() at the start of the next loop in checkerloop(),
where it can safely remove the multipath device.
-Ben
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> multipathd/main.c | 43 ++++++++++++++++++++-----------------------
> 1 file changed, 20 insertions(+), 23 deletions(-)
>
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 4a28fbb..131dab6 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -2446,34 +2446,30 @@ get_new_state(struct path *pp)
> return newstate;
> }
>
> -static void
> -do_sync_mpp(struct vectors * vecs, struct multipath *mpp)
> +/* Returns true if the mpp was deleted */
> +static int
> +do_sync_mpp(struct vectors *vecs, struct multipath *mpp)
> {
> - int i, ret;
> - struct path *pp;
> + int ret;
> +
> + ret = refresh_multipath(vecs, mpp);
> + if (ret)
> + return ret;
>
> - ret = update_multipath_strings(mpp, vecs->pathvec);
> - if (ret != DMP_OK) {
> - condlog(1, "%s: %s", mpp->alias, ret == DMP_NOT_FOUND ?
> - "device not found" :
> - "couldn't synchronize with kernel state");
> - vector_foreach_slot (mpp->paths, pp, i)
> - pp->dmstate = PSTATE_UNDEF;
> - return;
> - }
> set_no_path_retry(mpp);
> + return 0;
> }
>
> -static void
> +static int
> sync_mpp(struct vectors * vecs, struct multipath *mpp, unsigned int ticks)
> {
> if (mpp->sync_tick)
> mpp->sync_tick -= (mpp->sync_tick > ticks) ? ticks :
> mpp->sync_tick;
> if (mpp->sync_tick)
> - return;
> + return 0;
>
> - do_sync_mpp(vecs, mpp);
> + return do_sync_mpp(vecs, mpp);
> }
>
> static int
> @@ -2513,12 +2509,10 @@ update_path_state (struct vectors * vecs, struct path * pp)
> return handle_path_wwid_change(pp, vecs)? CHECK_PATH_REMOVED :
> CHECK_PATH_SKIPPED;
> }
> - if (pp->mpp->synced_count == 0) {
> - do_sync_mpp(vecs, pp->mpp);
> + if (pp->mpp->synced_count == 0 && do_sync_mpp(vecs, pp->mpp))
> /* if update_multipath_strings orphaned the path, quit early */
> - if (!pp->mpp)
> - return CHECK_PATH_SKIPPED;
> - }
> + return CHECK_PATH_SKIPPED;
> +
> if ((newstate != PATH_UP && newstate != PATH_GHOST &&
> newstate != PATH_PENDING) && (pp->state == PATH_DELAYED)) {
> /* If path state become failed again cancel path delay state */
> @@ -3018,8 +3012,11 @@ checkerloop (void *ap)
> mpp->synced_count = 0;
> if (checker_state == CHECKER_STARTING) {
> vector_foreach_slot(vecs->mpvec, mpp, i) {
> - sync_mpp(vecs, mpp, ticks);
> - mpp->prio_update = PRIO_UPDATE_NONE;
> + if (sync_mpp(vecs, mpp, ticks))
> + /* map deleted */
> + i--;
> + else
> + mpp->prio_update = PRIO_UPDATE_NONE;
> }
> vector_foreach_slot(vecs->pathvec, pp, i)
> pp->is_checked = CHECK_PATH_UNCHECKED;
> --
> 2.47.0
