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.
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
libmultipath/configure.c | 8 +++++++-
libmultipath/propsel.c | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/libmultipath/configure.c b/libmultipath/configure.c
index 74b6f52a..03874f47 100644
--- a/libmultipath/configure.c
+++ b/libmultipath/configure.c
@@ -275,15 +275,21 @@ 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);
diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
index d609394e..a86207a0 100644
--- a/libmultipath/propsel.c
+++ b/libmultipath/propsel.c
@@ -19,8 +19,10 @@
#include "discovery.h"
#include "dict.h"
#include "util.h"
+#include "sysfs.h"
#include "prioritizers/alua_rtpg.h"
#include <inttypes.h>
+#include <libudev.h>
pgpolicyfn *pgpolicies[] = {
NULL,
@@ -342,9 +344,42 @@ 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);
--
2.13.1
--
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