mdadm: added --no-sharing option for Monitor mode

--no-sharing option disables moving spares between arrays/containers.
Without the option spares are moved if needed according to config rules.
We only allow one process moving spares started with --scan option.
If there is such process running and another instance of Monitor
is starting without --scan, then we issue a warning but allow it
to continue.

Signed-off-by: Anna Czarnowska <anna.czarnowska@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Monitor.c

@@ -41,7 +41,8 @@ static void alert(char *event, char *dev, char *disc, char *mailaddr, char *mail
 int Monitor(struct mddev_dev *devlist,
 	    char *mailaddr, char *alert_cmd,
 	    int period, int daemonise, int scan, int oneshot,
-	    int dosyslog, int test, char* pidfile, int increments)
+	    int dosyslog, int test, char *pidfile, int increments,
+	    int share)
 {
 	/*
 	 * Every few seconds, scan every md device looking for changes
@@ -149,6 +150,45 @@ int Monitor(struct mddev_dev *devlist,
 		setsid();
 	}
 
+	if (share) {
+		int pid, rv;
+		FILE *fp;
+		char dir[20];
+		struct stat buf;
+		fp = fopen("/var/run/mdadm/autorebuild.pid", "r");
+		if (fp) {
+			fscanf(fp, "%d", &pid);
+			sprintf(dir, "/proc/%d", pid);
+			rv = stat(dir, &buf);
+			if (rv != -1) {
+				if (scan) {
+					fprintf(stderr, Name ": Only one "
+						"autorebuild process allowed"
+						" in scan mode, aborting\n");
+					fclose(fp);
+					return 1;
+				} else {
+					fprintf(stderr, Name ": Warning: One"
+						" autorebuild process already"
+						" running.");
+				}
+			}
+			fclose(fp);
+		}
+		if (scan) {
+			fp = fopen("/var/run/mdadm/autorebuild.pid", "w");
+			if (!fp)
+				fprintf(stderr, Name ": Cannot create"
+					" autorebuild.pid "
+					"file\n");
+			else {
+				pid = getpid();
+				fprintf(fp, "%d\n", pid);
+				fclose(fp);
+			}
+		}
+	}
+
 	if (devlist == NULL) {
 		struct mddev_ident *mdlist = conf_get_ident(NULL);
 		for (; mdlist; mdlist=mdlist->next) {
@@ -453,7 +493,7 @@ int Monitor(struct mddev_dev *devlist,
 		 * Look for another array with spare > 0 and active == raid and same spare_group
 		 *  if found, choose a device and hotremove/hotadd
 		 */
-		for (st = statelist; st; st=st->next)
+		if (share) for (st = statelist; st; st=st->next)
 			if (st->active < st->raid &&
 			    st->spare == 0 &&
 			    st->spare_group != NULL) {

ReadMe.c

@@ -185,6 +185,8 @@ struct option long_options[] = {
     {"oneshot",   0, 0, '1'},
     {"pid-file",  1, 0, 'i'},
     {"syslog",    0, 0, 'y'},
+    {"no-sharing", 0, 0, NoSharing},
+
     /* For Grow */
     {"backup-file", 1,0, BackupFile},
     {"array-size", 1, 0, 'Z'},

mdadm.c

@@ -96,6 +96,7 @@ int main(int argc, char *argv[])
 	int daemonise = 0;
 	char *pidfile = NULL;
 	int oneshot = 0;
+	int spare_sharing = 1;
 	struct supertype *ss = NULL;
 	int writemostly = 0;
 	int re_add = 0;
@@ -228,6 +229,7 @@ int main(int argc, char *argv[])
 				subarray = optarg;
 			}
 		case 'K': if (!mode) newmode = MISC; break;
+		case NoSharing: newmode = MONITOR; break;
 		}
 		if (mode && newmode == mode) {
 			/* everybody happy ! */
@@ -777,7 +779,9 @@ int main(int argc, char *argv[])
 			openlog("mdadm", LOG_PID, SYSLOG_FACILITY);
 			dosyslog = 1;
 			continue;
-
+		case O(MONITOR, NoSharing):
+			spare_sharing = 0;
+			continue;
 			/* now the general management options.  Some are applicable
 			 * to other modes. None have arguments.
 			 */
@@ -1494,7 +1498,7 @@ int main(int argc, char *argv[])
 		}
 		rv= Monitor(devlist, mailaddr, program,
 			    delay?delay:60, daemonise, scan, oneshot,
-			    dosyslog, test, pidfile, increments);
+			    dosyslog, test, pidfile, increments, spare_sharing);
 		break;
 
 	case GROW:

mdadm.h

@@ -288,7 +288,8 @@ enum special_options {
 	DetailPlatform,
 	KillSubarray,
 	UpdateSubarray, /* 16 */
-	IncrementalPath
+	IncrementalPath,
+	NoSharing
 };
 
 /* structures read from config file */
@@ -930,7 +931,8 @@ extern int Examine(struct mddev_dev *devlist, int brief, int export, int scan,
 extern int Monitor(struct mddev_dev *devlist,
 		   char *mailaddr, char *alert_cmd,
 		   int period, int daemonise, int scan, int oneshot,
-		   int dosyslog, int test, char *pidfile, int increments);
+		   int dosyslog, int test, char *pidfile, int increments,
+		   int share);
 
 extern int Kill(char *dev, struct supertype *st, int force, int quiet, int noexcl);
 extern int Kill_subarray(char *dev, char *subarray, int quiet);