mdmon: remove devices from container

Once the monitor thread has kicked a drive from all managed arrays mdadm
-r is permitted.  We are guaranteed that the drive is marked failed at
this point, so allow the drive to be re-added as a spare.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

managemon.c

@@ -228,12 +228,35 @@ static void manage_container(struct mdstat_ent *mdstat,
 	 * about spare assignment.... probably not.
 	 */
 	if (mdstat->devcnt != container->devcnt) {
+		struct mdinfo **cdp, *cd, *di, *mdi;
+		int found;
+
 		/* read /sys/block/NAME/md/dev-??/block/dev to find out
 		 * what is there, and compare with container->info.devs
 		 * To see what is removed and what is added.
 		 * These need to be remove from, or added to, the array
 		 */
-		// FIXME
+		mdi = sysfs_read(-1, mdstat->devnum, GET_DEVS);
+		if (!mdi)
+			return;
+
+		/* check for removals */
+		for (cdp = &container->devs; *cdp; ) {
+			found = 0;
+			for (di = mdi->devs; di; di = di->next)
+				if (di->disk.major == (*cdp)->disk.major &&
+				    di->disk.minor == (*cdp)->disk.minor) {
+					found = 1;
+					break;
+				}
+			if (!found) {
+				cd = *cdp;
+				*cdp = (*cdp)->next;
+				free(cd);
+			} else
+				cdp = &(*cdp)->next;
+		}
+		sysfs_free(mdi);
 		container->devcnt = mdstat->devcnt;
 	}
 }

mdmon.c

@@ -292,7 +292,7 @@ int main(int argc, char *argv[])
 	container->devs = NULL;
 	for (di = mdi->devs; di; di = di->next) {
 		struct mdinfo *cd = malloc(sizeof(*cd));
-		cd = di;
+		*cd = *di;
 		cd->next = container->devs;
 		container->devs = cd;
 	}