Add support for --add-spare

--add-spare is like --add, but a --re-add is never attempted.
So it is equivalent to two separate commands:

 --zero-metadata
 --add

Signed-off-by: NeilBrown <neilb@suse.de>

Manage.c

@@ -783,7 +783,8 @@ int Manage_add(int fd, int tfd, struct mddev_dev *dv,
 				break;
 			}
 		/* FIXME this is a bad test to be using */
-		if (!tst->sb && dv->disposition != 'a') {
+		if (!tst->sb && (dv->disposition != 'a'
+				 && dv->disposition != 'S')) {
 			/* we are re-adding a device to a
 			 * completely dead array - have to depend
 			 * on kernel to check
@@ -813,7 +814,7 @@ int Manage_add(int fd, int tfd, struct mddev_dev *dv,
 			dev_st = dup_super(tst);
 			dev_st->ss->load_super(dev_st, tfd, NULL);
 		}
-		if (dev_st && dev_st->sb) {
+		if (dev_st && dev_st->sb && dv->disposition != 'S') {
 			int rv = attempt_re_add(fd, tfd, dv,
 						dev_st, tst,
 						rdev,
@@ -1237,6 +1238,7 @@ int Manage_subdevs(char *devname, int fd,
 	 *  'a' - add the device
 	 *	   try HOT_ADD_DISK
 	 *         If that fails EINVAL, try ADD_NEW_DISK
+	 *  'S' - add the device as a spare - don't try re-add
 	 *  'A' - re-add the device
 	 *  'r' - remove the device: HOT_REMOVE_DISK
 	 *        device can be 'faulty' or 'detached' in which case all
@@ -1447,6 +1449,7 @@ int Manage_subdevs(char *devname, int fd,
 				dv->devname, dv->disposition);
 			goto abort;
 		case 'a':
+		case 'S': /* --add-spare */
 		case 'A':
 		case 'M': /* --re-add missing */
 		case 'F': /* --re-add faulty  */

ReadMe.c

@@ -153,6 +153,7 @@ struct option long_options[] = {
 
     /* Management */
     {"add",       0, 0, Add},
+    {"add-spare", 0, 0, AddSpare},
     {"remove",    0, 0, Remove},
     {"fail",      0, 0, Fail},
     {"set-faulty",0, 0, Fail},

mdadm.8.in

@@ -214,7 +214,10 @@ to detect and assemble arrays \(em possibly in an
 
 .P
 If a device is given before any options, or if the first option is
+and of
 .BR \-\-add ,
+.BR \-\-re\-add ,
+.BR \-\-add\-spare ,
 .BR \-\-fail ,
 .BR \-\-remove ,
 or
@@ -1297,6 +1300,15 @@ remove them and attempt to immediately re\-add them.  This can be
 useful if you are certain that the reason for failure has been
 resolved.
 
+.TP
+.B \-\-add\-spare
+Add a device as a spare.  This is similar to
+.B \-\-add
+except that it does not attempt
+.B \-\-re\-add
+first.  The device will be added as a spare even if it looks like it
+could be an recent member of the array.
+
 .TP
 .BR \-r ", " \-\-remove
 remove listed devices.  They must not be active.  i.e. they should

mdadm.c

@@ -187,6 +187,7 @@ int main(int argc, char *argv[])
 			break;
 		case 'a':
 		case Add:
+		case AddSpare:
 		case 'r':
 		case Remove:
 		case Replace:
@@ -915,6 +916,9 @@ int main(int argc, char *argv[])
 		case O(MANAGE,Add): /* add a drive */
 			devmode = 'a';
 			continue;
+		case O(MANAGE,AddSpare): /* add drive - never re-add */
+			devmode = 'S';
+			continue;
 		case O(MANAGE,ReAdd):
 			devmode = 'A';
 			continue;

mdadm.h

@@ -311,6 +311,7 @@ enum special_options {
 	Brief,
 	ManageOpt,
 	Add,
+	AddSpare,
 	Remove,
 	Fail,
 	Replace,