Work around bug in --add handling for version-1 superblocks

In 2.6.17 (and prior), the dev_number is ignored when a device
is added to an active array.  Rather the first free number is used.
So we work around this by making sure we use the first free
number for dev_number.

Description...

ChangeLog

@@ -4,6 +4,8 @@ Changes Prior to this release
     -   Stop map_dev from returning [0:0], as that breaks things.
     -   Add 'Array Slot' line to --examine for version-1 superblocks
 	to make it a bit easier to see what is happening.
+    -   Work around bug in --add handling for  version-1 superblocks
+	in 2.6.17 (and prior).
 
 Changes Prior to 2.5.1 release
     -   Various fixes for gcc warnings

Manage.c

@@ -271,8 +271,14 @@ int Manage_subdevs(char *devname, int fd,
 				 * If so, we can simply re-add it.
 				 */
 				st->ss->uuid_from_super(duuid, dsuper);
-			
-				if (osuper) {
+
+				/* re-add doesn't work for version-1 superblocks
+				 * before 2.6.18 :-(
+				 */
+				if (array.major_version == 1 &&
+				    get_linux_version() <= 2006018)
+					;
+				else if (osuper) {
 					st->ss->uuid_from_super(ouuid, osuper);
 					if (memcmp(duuid, ouuid, sizeof(ouuid))==0) {
 						/* look close enough for now.  Kernel
@@ -295,7 +301,12 @@ int Manage_subdevs(char *devname, int fd,
 					}
 				}
 			}
-			for (j=0; j< st->max_devs; j++) {
+			/* in 2.6.17 and earlier, version-1 superblocks won't
+			 * use the number we write, but will choose a free number.
+			 * we must choose the same free number, which requires
+			 * starting at 'raid_disks' and counting up
+			 */
+			for (j = array.raid_disks; j< st->max_devs; j++) {
 				disc.number = j;
 				if (ioctl(fd, GET_DISK_INFO, &disc))
 					break;

super1.c

@@ -779,7 +779,11 @@ static int write_init_super1(struct supertype *st, void *sbv,
 		if (memcmp(sb->set_uuid, refsb->set_uuid, 16)==0) {
 			/* same array, so preserve events and dev_number */
 			sb->events = refsb->events;
-			sb->dev_number = refsb->dev_number;
+			/* bugs in 2.6.17 and earlier mean the dev_number
+			 * chosen in Manage must be preserved
+			 */
+			if (get_linux_version() >= 2006018)
+				sb->dev_number = refsb->dev_number;
 		}
 		free(refsb);
 	}