Add action=spare-same-slot policy.

When "mdadm -I" is given a device with no metadata, mdadm tries to add
it as a 'spare' somewhere based on policy.

This patch changes the behaviour in two ways:

1/ If the device is at a 'path' where a previous device was removed
  from an array or container, then we preferentially add the spare to
  that array or container.

2/ Previously only 'bare' devices were considered for adding as
  spares.  Now if action=spare-same-slot is active, we will add
  non-bare devices, but *only* if the path was previously in use
  for some array, and the device will only be added to that array.

Based on code
  From: Przemyslaw Czarnowski <przemyslaw.hawrylewicz.czarnowski@intel.com>

Signed-off-by: Przemyslaw Czarnowski <przemyslaw.hawrylewicz.czarnowski@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/policy.c b/policy.c
index 28751fb9..cc126949 100644
--- a/policy.c
+++ b/policy.c
@@ -519,6 +519,8 @@ static enum policy_action map_act(char *act)
 		return act_re_add;
 	if (strcmp(act, "spare") == 0)
 		return act_spare;
+	if (strcmp(act, "spare-same-slot") == 0)
+		return act_spare_same_slot;
 	if (strcmp(act, "force-spare") == 0)
 		return act_force_spare;
 	return act_err;