libmultipath: don't try to set hwhandler if it is retained
authorMartin Wilck <mwilck@suse.com>
Sat, 13 Jan 2018 21:19:19 +0000 (22:19 +0100)
committerChristophe Varoqui <christophe.varoqui@opensvc.com>
Wed, 7 Mar 2018 08:27:48 +0000 (09:27 +0100)
Setting a device handler only works if retain_attached_hw_handler
is 'no', or if the kernel didn't auto-assign a handler. If this
is not the case, don't even attempt to set a different handler.

This requires reading the sysfs "dh_state" path attribute.

libmultipath/configure.c
libmultipath/propsel.c

index 22c11a2..13e14cc 100644 (file)
@@ -277,15 +277,21 @@ int setup_map(struct multipath *mpp, char *params, int params_size)
 
        /*
         * properties selectors
+        *
+        * Ordering matters for some properties:
+        * - features after no_path_retry and retain_hwhandler
+        * - hwhandler after retain_hwhandler
+        * No guarantee that this list is complete, check code in
+        * propsel.c if in doubt.
         */
        conf = get_multipath_config();
        select_pgfailback(conf, mpp);
        select_pgpolicy(conf, mpp);
        select_selector(conf, mpp);
-       select_hwhandler(conf, mpp);
        select_no_path_retry(conf, mpp);
        select_retain_hwhandler(conf, mpp);
        select_features(conf, mpp);
+       select_hwhandler(conf, mpp);
        select_rr_weight(conf, mpp);
        select_minio(conf, mpp);
        select_mode(conf, mpp);
index be371fc..4db0913 100644 (file)
 #include "discovery.h"
 #include "dict.h"
 #include "util.h"
+#include "sysfs.h"
 #include "prioritizers/alua_rtpg.h"
 #include "prkey.h"
 #include <inttypes.h>
+#include <libudev.h>
 
 pgpolicyfn *pgpolicies[] = {
        NULL,
@@ -353,9 +355,42 @@ out:
        return 0;
 }
 
+static int get_dh_state(struct path *pp, char *value, size_t value_len)
+{
+       struct udev_device *ud;
+
+       if (pp->udev == NULL)
+               return -1;
+
+       ud = udev_device_get_parent_with_subsystem_devtype(
+               pp->udev, "scsi", "scsi_device");
+       if (ud == NULL)
+               return -1;
+
+       return sysfs_attr_get_value(ud, "dh_state", value, value_len);
+}
+
 int select_hwhandler(struct config *conf, struct multipath *mp)
 {
        char *origin;
+       struct path *pp;
+       /* dh_state is no longer than "detached" */
+       char handler[12];
+       char *dh_state;
+       int i;
+
+       dh_state = &handler[2];
+       if (mp->retain_hwhandler != RETAIN_HWHANDLER_OFF) {
+               vector_foreach_slot(mp->paths, pp, i) {
+                       if (get_dh_state(pp, dh_state, sizeof(handler) - 2) > 0
+                           && strcmp(dh_state, "detached")) {
+                               memcpy(handler, "1 ", 2);
+                               mp->hwhandler = handler;
+                               origin = "(setting: retained by kernel driver)";
+                               goto out;
+                       }
+               }
+       }
 
        mp_set_hwe(hwhandler);
        mp_set_conf(hwhandler);