From 7159242be31dbb3f25aa67920462107bc2bc5fe0 Mon Sep 17 00:00:00 2001

From: Benjamin Marzinski <bmarzins@redhat.com>

Date: Thu, 9 Jul 2020 18:20:18 -0500

Subject: [PATCH] libmultipath: count pending paths as active on loads

When multipath loads a table, it signals to udev if there are no active

paths.  Multipath wasn't counting pending paths as active.  This meant

that if all the paths were pending, udev would treat the device as not

ready, and not run kpartx on it.  Even if the pending paths later

because active and were reinstated, the kernel would not send a new

uevent, because from its point of view, they were always up.

The alternative would be to continue to treat them as failed in the udev

rules, but then also tell the kernel that they were down, so that it

would trigger a uevent when they were reinstated. However, this could

lead to newly created multipath devices failing IO, simply because the

path checkers hadn't returned yet. Having udev assume that the the

device is up, like the kernel does, seems like the safer option.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

---

 libmultipath/devmapper.c |  3 ++-

 libmultipath/structs.c   | 20 ++++++++++++++++++++

 libmultipath/structs.h   |  1 +

 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c

index 7f98bf9d..91ff0b3d 100644

--- a/libmultipath/devmapper.c

+++ b/libmultipath/devmapper.c

@@ -408,7 +408,8 @@ static uint16_t build_udev_flags(const struct multipath *mpp, int reload)

 	/* DM_UDEV_DISABLE_LIBRARY_FALLBACK is added in dm_addmap */

 	return	(mpp->skip_kpartx == SKIP_KPARTX_ON ?

 		 MPATH_UDEV_NO_KPARTX_FLAG : 0) |

-		((count_active_paths(mpp) == 0 || mpp->ghost_delay_tick > 0) ?

+		((count_active_pending_paths(mpp) == 0 ||

+		  mpp->ghost_delay_tick > 0) ?

 		 MPATH_UDEV_NO_PATHS_FLAG : 0) |

 		(reload && !mpp->force_udev_reload ?

 		 MPATH_UDEV_RELOAD_FLAG : 0);

diff --git a/libmultipath/structs.c b/libmultipath/structs.c

index 2dd378c4..dda9884c 100644

--- a/libmultipath/structs.c

+++ b/libmultipath/structs.c

@@ -500,6 +500,26 @@ int count_active_paths(const struct multipath *mpp)

 	return count;

 }

+int count_active_pending_paths(const struct multipath *mpp)

+{

+	struct pathgroup *pgp;

+	struct path *pp;

+	int count = 0;

+	int i, j;

+

+	if (!mpp->pg)

+		return 0;

+

+	vector_foreach_slot (mpp->pg, pgp, i) {

+		vector_foreach_slot (pgp->paths, pp, j) {

+			if (pp->state == PATH_UP || pp->state == PATH_GHOST ||

+			    pp->state == PATH_PENDING)

+				count++;

+		}

+	}

+	return count;

+}

+

 int pathcmp(const struct pathgroup *pgp, const struct pathgroup *cpgp)

 {

 	int i, j;

diff --git a/libmultipath/structs.h b/libmultipath/structs.h

index 9bd39eb1..8e78b8c0 100644

--- a/libmultipath/structs.h

+++ b/libmultipath/structs.h

@@ -465,6 +465,7 @@ struct path * first_path (const struct multipath *mpp);

 int pathcountgr (const struct pathgroup *, int);

 int pathcount (const struct multipath *, int);

 int count_active_paths(const struct multipath *);

+int count_active_pending_paths(const struct multipath *);

 int pathcmp (const struct pathgroup *, const struct pathgroup *);

 int add_feature (char **, const char *);

 int remove_feature (char **, const char *);

-- 

2.17.2