device-mapper-multipath/0009-libmultipath-make-group_paths-handle-marginal-paths.patch

From 227a9fceb8c20f153f4f136caeb28faff5bd80fe Mon Sep 17 00:00:00 2001
From: Benjamin Marzinski <bmarzins@redhat.com>
Date: Fri, 12 Jul 2019 15:39:26 -0500
Subject: [PATCH] libmultipath: make group_paths handle marginal paths

group_paths() will now create seperate path groups for marginal and
normal paths, and place all of the marginal path groups after the normal
ones, in order by priority.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/pgpolicies.c  | 83 +++++++++++++++++++++++++++++++++-----
 libmultipath/switchgroup.c | 15 ++++++-
 2 files changed, 88 insertions(+), 10 deletions(-)

diff --git a/libmultipath/pgpolicies.c b/libmultipath/pgpolicies.c
index 2e7c0502..6fb2d28a 100644
--- a/libmultipath/pgpolicies.c
+++ b/libmultipath/pgpolicies.c
@@ -72,9 +72,11 @@ sort_pathgroups (struct multipath *mp) {
 			pgp2 = VECTOR_SLOT(mp->pg, j);
 			if (!pgp2)
 				continue;
-			if (pgp2->priority > pgp1->priority ||
-			    (pgp2->priority == pgp1->priority &&
-			     pgp2->enabled_paths >= pgp1->enabled_paths)) {
+			if (pgp2->marginal < pgp1->marginal ||
+			    (pgp2->marginal == pgp1->marginal &&
+			     (pgp2->priority > pgp1->priority ||
+			      (pgp2->priority == pgp1->priority &&
+			       pgp2->enabled_paths >= pgp1->enabled_paths)))) {
 				vector_move_up(mp->pg, i, j + 1);
 				break;
 			}
@@ -84,25 +86,88 @@ sort_pathgroups (struct multipath *mp) {
 	}
 }
 
+static int
+split_marginal_paths(vector paths, vector *normal_p, vector *marginal_p)
+{
+	int i;
+	int has_marginal = 0;
+	int has_normal = 0;
+	struct path *pp;
+	vector normal = NULL;
+	vector marginal = NULL;
+
+	*normal_p = *marginal_p = NULL;
+	vector_foreach_slot(paths, pp, i) {
+		if (pp->marginal)
+			has_marginal = 1;
+		else
+			has_normal = 1;
+	}
+
+	if (!has_marginal || !has_normal)
+		return -1;
+
+	normal = vector_alloc();
+	marginal = vector_alloc();
+	if (!normal || !marginal)
+		goto fail;
+
+	vector_foreach_slot(paths, pp, i) {
+		if (pp->marginal) {
+			if (store_path(marginal, pp))
+				goto fail;
+		}
+		else {
+			if (store_path(normal, pp))
+				goto fail;
+		}
+	}
+	*normal_p = normal;
+	*marginal_p = marginal;
+	return 0;
+fail:
+	vector_free(normal);
+	vector_free(marginal);
+	return -1;
+}
 
 int group_paths(struct multipath *mp)
 {
+	vector normal, marginal;
+
 	if (!mp->pg)
 		mp->pg = vector_alloc();
 	if (!mp->pg)
 		return 1;
 
-	if (VECTOR_SIZE(mp->paths) > 0 &&
-	    (!mp->pgpolicyfn || mp->pgpolicyfn(mp, mp->paths))) {
-		vector_free(mp->pg);
-		mp->pg = NULL;
-		return 1;
+	if (VECTOR_SIZE(mp->paths) == 0)
+		goto out;
+	if (!mp->pgpolicyfn)
+		goto fail;
+
+	if (split_marginal_paths(mp->paths, &normal, &marginal) != 0) {
+		if (mp->pgpolicyfn(mp, mp->paths) != 0)
+			goto fail;
+	} else {
+		if (mp->pgpolicyfn(mp, normal) != 0)
+			goto fail_marginal;
+		if (mp->pgpolicyfn(mp, marginal) != 0)
+			goto fail_marginal;
+		vector_free(normal);
+		vector_free(marginal);
 	}
-
 	sort_pathgroups(mp);
+out:
 	vector_free(mp->paths);
 	mp->paths = NULL;
 	return 0;
+fail_marginal:
+	vector_free(normal);
+	vector_free(marginal);
+fail:
+	vector_free(mp->pg);
+	mp->pg = NULL;
+	return 1;
 }
 
 typedef bool (path_match_fn)(struct path *pp1, struct path *pp2);
diff --git a/libmultipath/switchgroup.c b/libmultipath/switchgroup.c
index 9632ce2d..6fdfcfa7 100644
--- a/libmultipath/switchgroup.c
+++ b/libmultipath/switchgroup.c
@@ -11,6 +11,7 @@ void path_group_prio_update(struct pathgroup *pgp)
 {
 	int i;
 	int priority = 0;
+	int marginal = 0;
 	struct path * pp;
 
 	pgp->enabled_paths = 0;
@@ -19,6 +20,8 @@ void path_group_prio_update(struct pathgroup *pgp)
 		return;
 	}
 	vector_foreach_slot (pgp->paths, pp, i) {
+		if (pp->marginal)
+			marginal++;
 		if (pp->state == PATH_UP ||
 		    pp->state == PATH_GHOST) {
 			priority += pp->priority;
@@ -29,11 +32,14 @@ void path_group_prio_update(struct pathgroup *pgp)
 		pgp->priority = priority / pgp->enabled_paths;
 	else
 		pgp->priority = 0;
+	if (marginal && marginal == i)
+		pgp->marginal = 1;
 }
 
 int select_path_group(struct multipath *mpp)
 {
 	int i;
+	int normal_pgp = 0;
 	int max_priority = 0;
 	int bestpg = 1;
 	int max_enabled_paths = 1;
@@ -47,8 +53,15 @@ int select_path_group(struct multipath *mpp)
 			continue;
 
 		path_group_prio_update(pgp);
+		if (pgp->marginal && normal_pgp)
+			continue;
 		if (pgp->enabled_paths) {
-			if (pgp->priority > max_priority) {
+			if (!pgp->marginal && !normal_pgp) {
+				normal_pgp = 1;
+				max_priority = pgp->priority;
+				max_enabled_paths = pgp->enabled_paths;
+				bestpg = i + 1;
+			} else if (pgp->priority > max_priority) {
 				max_priority = pgp->priority;
 				max_enabled_paths = pgp->enabled_paths;
 				bestpg = i + 1;
-- 
2.17.2