add '-r' option to force devmap reload

This takes care of updating the write-protection flag
of the devmap in case the write-prot of the underlying
paths has changed (and the kernel somehow has discovered
so).

Now a RO->RW change scenario for a multipathed device can
be treated with :
1/ echo 1 >/sys/block/XX/device/rescan on all paths to dev
2/ multipath -r dev

Which minimaly fulfills my needs with Symmetrix SRDF spliting
in interim of more collaboration from other subsystems.

1 files changed, 37 insertions, 29 deletions

diff --git a/multipath/main.c b/multipath/main.c
index f1ac256..44c6bf6 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -75,34 +75,39 @@ static void
 usage (char * progname)
 {
 	fprintf (stderr, VERSION_STRING);
-	fprintf (stderr, "Usage: %s\t[-v level] [-d] [-h|-l|-ll|-f|-F]\n",
-		progname);
+	fprintf (stderr, "Usage:\n");
+	fprintf (stderr, "  %s [-d] [-r] [-v lvl] [-p pol] [-b fil] [dev]\n", progname);
+	fprintf (stderr, "  %s -l|-ll|-f [-v lvl] [-b fil] [dev]\n", progname);
+	fprintf (stderr, "  %s -F [-v lvl]\n", progname);
+	fprintf (stderr, "  %s -h\n", progname);
 	fprintf (stderr,
-		"\t\t\t[-p failover|multibus|group_by_serial|group_by_prio]\n" \
-		"\t\t\t[device]\n" \
-		"\n" \
-		"\t-v level\tverbosity level\n" \
-		"\t   0\t\t\tno output\n" \
-		"\t   1\t\t\tprint created devmap names only\n" \
-		"\t   2\t\t\tdefault verbosity\n" \
-		"\t   3\t\t\tprint debug information\n" \
-		"\t-h\t\tprint this usage text\n" \
-		"\t-b file\t\tbindings file location\n" \
-		"\t-d\t\tdry run, do not create or update devmaps\n" \
-		"\t-l\t\tshow multipath topology (sysfs and DM info)\n" \
-		"\t-ll\t\tshow multipath topology (maximum info)\n" \
-		"\t-f\t\tflush a multipath device map\n" \
-		"\t-F\t\tflush all multipath device maps\n" \
-		"\t-p policy\tforce all maps to specified policy :\n" \
-		"\t   failover\t\t1 path per priority group\n" \
-		"\t   multibus\t\tall paths in 1 priority group\n" \
-		"\t   group_by_serial\t1 priority group per serial\n" \
-		"\t   group_by_prio\t1 priority group per priority lvl\n" \
-		"\t   group_by_node_name\t1 priority group per target node\n" \
-		"\n" \
-		"\tdevice\t\tlimit scope to the device's multipath\n" \
-		"\t\t\t(udev-style $DEVNAME reference, eg /dev/sdb\n" \
-		"\t\t\tor major:minor or a device map name)\n" \
+		"\n"
+		"Where:\n"
+		"  -h      print this usage text\n" \
+		"  -l      show multipath topology (sysfs and DM info)\n" \
+		"  -ll     show multipath topology (maximum info)\n" \
+		"  -f      flush a multipath device map\n" \
+		"  -F      flush all multipath device maps\n" \
+		"  -d      dry run, do not create or update devmaps\n" \
+		"  -r      force devmap reload\n" \
+		"  -p      policy failover|multibus|group_by_serial|group_by_prio\n" \
+		"  -b fil  bindings file location\n" \
+		"  -p pol  force all maps to specified path grouping policy :\n" \
+		"          . failover            one path per priority group\n" \
+		"          . multibus            all paths in one priority group\n" \
+		"          . group_by_serial     one priority group per serial\n" \
+		"          . group_by_prio       one priority group per priority lvl\n" \
+		"          . group_by_node_name  one priority group per target node\n" \
+		"  -v lvl  verbosity level\n" \
+		"          . 0 no output\n" \
+		"          . 1 print created devmap names only\n" \
+		"          . 2 default verbosity\n" \
+		"          . 3 print debug information\n" \
+		"  dev     action limited to:\n" \
+		"          . multipath named 'dev' (ex: mpath0) or\n" \
+		"          . multipath whose wwid is 'dev' (ex: 60051..)\n" \
+		"          . multipath including the path named 'dev' (ex: /dev/sda)\n" \
+		"          . multipath including the path with maj:min 'dev' (ex: 8:0)\n" \
 		);
 
 	exit(1);
@@ -298,7 +303,7 @@ configure (void)
 	/*
 	 * core logic entry point
 	 */
-	r = coalesce_paths(&vecs, NULL, NULL);
+	r = coalesce_paths(&vecs, NULL, NULL, conf->force_reload);
 
 out:
 	if (refwwid)
@@ -341,7 +346,7 @@ main (int argc, char *argv[])
 		condlog(0, "multipath tools need sysfs mounted");
 		exit(1);
 	}
-	while ((arg = getopt(argc, argv, ":dhl::FfM:v:p:b:")) != EOF ) {
+	while ((arg = getopt(argc, argv, ":dhl::FfM:v:p:b:r")) != EOF ) {
 		switch(arg) {
 		case 1: printf("optarg : %s\n",optarg);
 			break;
@@ -384,6 +389,9 @@ main (int argc, char *argv[])
 				usage(argv[0]);
 			}                
 			break;
+		case 'r':
+			conf->force_reload = 1;
+			break;
 		case 'h':
 			usage(argv[0]);
 		case ':':