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

[mwilck at suse.com]

From: Martin Wilck <mwilck at 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 at suse.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