Add --test option to --re-add and similar

--test can be given in Manage mode.
This can be used when there is an attempt to fail or remove 'faulty',
'failed' or 'detached' devices, or to re-add 'missing' devices.
If no devices were failed, removed, or re-added, then mdadm will
exit with status '2'.

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

Incremental.c

@@ -900,7 +900,7 @@ int IncrementalRemove(char *devname, int verbose)
 	memset(&devlist, 0, sizeof(devlist));
 	devlist.devname = devname;
 	devlist.disposition = 'f';
-	Manage_subdevs(ent->dev, mdfd, &devlist, verbose);
+	Manage_subdevs(ent->dev, mdfd, &devlist, verbose, 0);
 	devlist.disposition = 'r';
-	return Manage_subdevs(ent->dev, mdfd, &devlist, verbose);
+	return Manage_subdevs(ent->dev, mdfd, &devlist, verbose, 0);
 }

Manage.c

@@ -326,7 +326,7 @@ int Manage_resize(char *devname, int fd, long long size, int raid_disks)
 }
 
 int Manage_subdevs(char *devname, int fd,
-		   mddev_dev_t devlist, int verbose)
+		   mddev_dev_t devlist, int verbose, int test)
 {
 	/* do something to each dev.
 	 * devmode can be
@@ -355,6 +355,7 @@ int Manage_subdevs(char *devname, int fd,
 	int ouuid[4];
 	int lfd = -1;
 	int sysfd = -1;
+	int count = 0; /* number of actions taken */
 
 	if (ioctl(fd, GET_ARRAY_INFO, &array)) {
 		fprintf(stderr, Name ": cannot get array info for %s\n",
@@ -684,6 +685,7 @@ int Manage_subdevs(char *devname, int fd,
 						    ioctl(fd, ADD_NEW_DISK, &disc) == 0) {
 							if (verbose >= 0)
 								fprintf(stderr, Name ": re-added %s\n", add_dev);
+							count++;
 							continue;
 						}
 						if (errno == ENOMEM || errno == EROFS) {
@@ -959,6 +961,7 @@ int Manage_subdevs(char *devname, int fd,
 			}
 			if (lfd >= 0)
 				close(lfd);
+			count++;
 			if (verbose >= 0)
 				fprintf(stderr, Name ": hot removed %s from %s\n",
 					dnprintable, devname);
@@ -978,14 +981,16 @@ int Manage_subdevs(char *devname, int fd,
 			if (sysfd >= 0)
 				close(sysfd);
 			sysfd = -1;
+			count++;
 			if (verbose >= 0)
 				fprintf(stderr, Name ": set %s faulty in %s\n",
 					dnprintable, devname);
 			break;
 		}
 	}
+	if (test && count == 0)
+		return 2;
 	return 0;
-
 }
 
 int autodetect(void)

Monitor.c

@@ -491,15 +491,15 @@ int Monitor(mddev_dev_t devlist,
 							sprintf(devname, "%d:%d", major(dev), minor(dev));
 
 							devlist.disposition = 'r';
-							if (Manage_subdevs(st2->devname, fd2, &devlist, -1) == 0) {
+							if (Manage_subdevs(st2->devname, fd2, &devlist, -1, 0) == 0) {
 								devlist.disposition = 'a';
-								if (Manage_subdevs(st->devname, fd1, &devlist, -1) == 0) {
+								if (Manage_subdevs(st->devname, fd1, &devlist, -1, 0) == 0) {
 									alert("MoveSpare", st->devname, st2->devname, mailaddr, mailfrom, alert_cmd, dosyslog);
 									close(fd1);
 									close(fd2);
 									break;
 								}
-								else Manage_subdevs(st2->devname, fd2, &devlist, -1);
+								else Manage_subdevs(st2->devname, fd2, &devlist, -1, 0);
 							}
 						}
 						close(fd1);

mdadm.c

@@ -796,6 +796,9 @@ int main(int argc, char *argv[])
 			}
 			runstop = -1;
 			continue;
+		case O(MANAGE,'t'):
+			test = 1;
+			continue;
 
 		case O(MISC,'Q'):
 		case O(MISC,'D'):
@@ -1064,7 +1067,7 @@ int main(int argc, char *argv[])
 			rv = Manage_ro(devlist->devname, mdfd, readonly);
 		if (!rv && devs_found>1)
 			rv = Manage_subdevs(devlist->devname, mdfd,
-					    devlist->next, verbose-quiet);
+					    devlist->next, verbose-quiet, test);
 		if (!rv && readonly < 0)
 			rv = Manage_ro(devlist->devname, mdfd, readonly);
 		if (!rv && runstop)

mdadm.h

@@ -769,7 +769,7 @@ extern int Manage_ro(char *devname, int fd, int readonly);
 extern int Manage_runstop(char *devname, int fd, int runstop, int quiet);
 extern int Manage_resize(char *devname, int fd, long long size, int raid_disks);
 extern int Manage_subdevs(char *devname, int fd,
-			  mddev_dev_t devlist, int verbose);
+			  mddev_dev_t devlist, int verbose, int test);
 extern int autodetect(void);
 extern int Grow_Add_device(char *devname, int fd, char *newdev);
 extern int Grow_addbitmap(char *devname, int fd, char *file, int chunk, int delay, int write_behind, int force);