From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Benjamin Marzinski <bmarzins@redhat.com>

Date: Mon, 18 Feb 2019 13:32:45 -0600

Subject: [PATCH] BZ 1673167: Fix miscounting active paths

When multipathd gets a change uevent, it calls pathinfo with DI_NOIO.

This sets the path state to the return value of path_offline(). If a

path is in the PATH_DOWN state but path_offline() returns PATH_UP, when

that path gets a change event, its state will get moved to PATH_UP

without either reinstating the path, or reloading the map.  The next

call to check_path() will move the path back to PATH_DOWN. Since

check_path() simply increments and decrements nr_active instead of

calculating it based on the actual number of active paths, nr_active

will get decremented a second time for this failed path, potentially

putting the multipath device into recovery mode.

To avoid this situation, pathinfo() will now only set pp->state with

DI_NOIO if DI_CHECKER is also set. This isn't set in uev_update_path()

to avoid changing the path state in this case.

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

---

 libmultipath/discovery.c | 11 ++++++-----

 multipath/main.c         |  2 +-

 2 files changed, 7 insertions(+), 6 deletions(-)

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

index b267f07..5de087c 100644

--- a/libmultipath/discovery.c

+++ b/libmultipath/discovery.c

@@ -1914,11 +1914,12 @@ int pathinfo(struct path *pp, struct config *conf, int mask)

 	if (path_state == PATH_REMOVED)

 		goto blank;

 	else if (mask & DI_NOIO) {

-		/*

-		 * Avoid any IO on the device itself.

-		 * Behave like DI_CHECKER in the "path unavailable" case.

-		 */

-		pp->chkrstate = pp->state = path_state;

+		if (mask & DI_CHECKER)

+			/*

+			 * Avoid any IO on the device itself.

+			 * simply use the path_offline() return as its state

+			 */

+			pp->chkrstate = pp->state = path_state;

 		return PATHINFO_OK;

 	}

diff --git a/multipath/main.c b/multipath/main.c

index 2c4054d..0545226 100644

--- a/multipath/main.c

+++ b/multipath/main.c

@@ -345,7 +345,7 @@ static int check_usable_paths(struct config *conf,

 			pp->udev = get_udev_device(pp->dev_t, DEV_DEVT);

 			if (pp->udev == NULL)

 				continue;

-			if (pathinfo(pp, conf, DI_SYSFS|DI_NOIO) != PATHINFO_OK)

+			if (pathinfo(pp, conf, DI_SYSFS|DI_NOIO|DI_CHECKER) != PATHINFO_OK)

 				continue;

 			if (pp->state == PATH_UP &&

-- 

2.17.2