Path priority for RDAC devices

Hi Christophe,

Few months ago I submitted path checker code for RDAC devices.

Recently I found that the priority of the paths are not being set properly.

Here are 2 patches that fix the problem and set the priority appropriately.

Please let me know what do you think.

Thanks

chandra

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - [email protected]   |      .......you may get it.
----------------------------------------------------------------------

While debugging I found that multipath was not selecting the preferred path many a times (inlcuding the failback scenarios).

Added a priority callout function and the expected behavior was still not seen (patch 2 of 2).

More debugging revealed that the changes I made to work in the ghost mode was wrong. Reverting those changes made the multipath behave properly.

Index: multipath-tools-0.4.7/libmultipath/discovery.c
===================================================================
@@ -699,7 +699,7 @@
 	if (mask & DI_CHECKER && get_state(pp))
 		goto blank;
 	
-	if (mask & DI_PRIO && pp->state == PATH_UP)
+	if (mask & DI_PRIO && pp->state != PATH_DOWN)
 		get_prio(pp);
 
 	if (mask & DI_WWID && !strlen(pp->wwid))

Index: multipath-tools-0.4.7/libmultipath/switchgroup.c
===================================================================
@@ -28,7 +28,7 @@
 		priority = 0;
 
 		vector_foreach_slot (pgp->paths, pp, j) {
-			if (pp->state == PATH_UP)
+			if (pp->state != PATH_DOWN)
 				priority += pp->priority;
 		}
 		pgp->priority = priority;

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - [email protected]   |      .......you may get it.
----------------------------------------------------------------------

RDAC currently doesn't have a path priority callout. This affects the expected behavior of multipath. i.e multipath's active path group doesn't always lead to the preferred path of the device.

This patch sets the priority of a path based on the preferred path that is queried from the controller through the C9 inquiry page.

Index: multipath-tools-0.4.7/path_priority/pp_rdac/Makefile
===================================================================
@@ -0,0 +1,25 @@
+EXEC		= mpath_prio_rdac
+BUILD		= glibc
+OBJS		= pp_rdac.o
+
+TOPDIR		= ../..
+include $(TOPDIR)/Makefile.inc
+
+all: $(BUILD)
+
+glibc:	$(OBJS)
+	$(CC) -o $(EXEC) $(OBJS) $(LDFLAGS)
+
+klibc:	$(OBJS)
+	$(CC) -static -o $(EXEC) $(OBJS)
+
+install: $(EXEC)
+	install -s -m 755 $(EXEC) $(DESTDIR)$(bindir)/$(EXEC)
+
+uninstall:
+	rm $(DESTDIR)$(bindir)/$(EXEC)
+clean:
+	rm -f *.o $(EXEC)
+
+%.o:	%.c
+	$(CC) $(CFLAGS) -c -o $@ $<

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - [email protected]   |      .......you may get it.
----------------------------------------------------------------------