Re: [dm-devel] [PATCH] multipathd: give up "add missing path" after multiple failures

[Benjamin Marzinski <bmarzins@redhat.com>]

On Mon, Mar 29, 2021 at 10:39:35PM +0200, mwilck@suse.com wrote:
> From: Martin Wilck <mwilck@suse.com>
> 
> After b7aae60 ("multipathd: improve "add missing path" handling"),
> a path that failed to initialize after multiple udev retriggers
> would still be checked in check_path(). However, if a path is up,
> has been checked more than once, the failback WWID methods have
> been tried, and still there is no usable WWID, we may conclude
> that something is fishy and we shouldn't keep trying.
> 
> Without this patch, totally WWID-less devices (seen e.g. on ESXi)
> will cause a "add missing path" message in every checker iteration.
> 
> Fixes: b7aae60 ("multipathd: improve "add missing path" handling")
> Signed-off-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
> ---
>  libmultipath/discovery.c | 16 ++++++++++++++++
>  multipathd/main.c        |  6 ++++--
>  2 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> index f804414..ec99a7a 100644
> --- a/libmultipath/discovery.c
> +++ b/libmultipath/discovery.c
> @@ -2370,6 +2370,22 @@ int pathinfo(struct path *pp, struct config *conf, int mask)
>  			if (pp->initialized != INIT_FAILED) {
>  				pp->initialized = INIT_MISSING_UDEV;
>  				pp->tick = conf->retrigger_delay;
> +			} else if (pp->retriggers >= conf->retrigger_tries &&
> +				   (pp->state == PATH_UP || pp->state == PATH_GHOST)) {
> +				/*
> +				 * We have failed to read udev info for this path
> +				 * repeatedly. We used the fallback in get_uid()
> +				 * if there was any, and still got no WWID,
> +				 * although the path is allegedly up.
> +				 * It's likely that this path is not fit for
> +				 * multipath use.
> +				 */
> +				char buf[16];
> +
> +				snprint_path(buf, sizeof(buf), "%T", pp, 0);
> +				condlog(1, "%s: no WWID in state \"%s\", giving up",
> +					pp->dev, buf);
> +				return PATHINFO_SKIPPED;
>  			}
>  			return PATHINFO_OK;
>  		}
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 3579bad..102946b 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -2218,13 +2218,13 @@ check_path (struct vectors * vecs, struct path * pp, unsigned int ticks)
>  				ev_add_path(pp, vecs, 1);
>  				pp->tick = 1;
>  			} else {
> +				if (ret == PATHINFO_SKIPPED)
> +					return -1;
>  				/*
>  				 * We failed multiple times to initialize this
>  				 * path properly. Don't re-check too often.
>  				 */
>  				pp->checkint = max_checkint;
> -				if (ret == PATHINFO_SKIPPED)
> -					return -1;
>  			}
>  		}
>  		return 0;
> @@ -2504,6 +2504,8 @@ checkerloop (void *ap)
>  		vector_foreach_slot (vecs->pathvec, pp, i) {
>  			rc = check_path(vecs, pp, ticks);
>  			if (rc < 0) {
> +				condlog(1, "%s: check_path() failed, removing",
> +					pp->dev);
>  				vector_del_slot(vecs->pathvec, i);
>  				free_path(pp);
>  				i--;
> -- 
> 2.30.1

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