Factor out test for subarray version string.

We are about to change the syntax of the version string
for 'subarray's.  So factor out the test into a single function.

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

Create.c

@@ -523,7 +523,7 @@ int Create(struct supertype *st, char *mddev, int mdfd,
 	st->ss->getinfo_super(st, &info);
 
 	if (did_default && verbose >= 0) {
-		if (info.text_version[0] == '/') {
+		if (is_subarray(info.text_version)) {
 			int dnum = devname2devnum(info.text_version+1);
 			char *path;
 			int mdp = get_mdp_major();

Manage.c

@@ -123,7 +123,7 @@ int Manage_runstop(char *devname, int fd, int runstop, int quiet)
 		mdi = sysfs_read(fd, -1, GET_LEVEL|GET_VERSION);
 		if (mdi &&
 		    mdi->array.level > 0 &&
-		    mdi->text_version[0] == '/') {
+		    is_subarray(mdi->text_version)) {
 			char *cp;
 
 			/* This is mdmon managed. */
@@ -147,7 +147,7 @@ int Manage_runstop(char *devname, int fd, int runstop, int quiet)
 		} else if (mdi &&
 			   mdi->array.major_version == -1 &&
 			   mdi->array.minor_version == -2 &&
-			   mdi->text_version[0] != '/') {
+			   !is_subarray(mdi->text_version)) {
 			/* container, possibly mdmon-managed.
 			 * Make sure mdmon isn't opening it, which
 			 * would interfere with the 'stop'

managemon.c

@@ -492,7 +492,8 @@ void manage(struct mdstat_ent *mdstat, struct supertype *container)
 			continue;
 		}
 		if (mdstat->metadata_version == NULL ||
-		    strncmp(mdstat->metadata_version, "external:/", 10) != 0 ||
+		    strncmp(mdstat->metadata_version, "external:", 9) != 0 ||
+		    !is_subarray(mdstat->metadata_version+9) ||
 		    strncmp(mdstat->metadata_version+10, container->devname,
 			    strlen(container->devname)) != 0 ||
 		    mdstat->metadata_version[10+strlen(container->devname)]

mdadm.h

@@ -805,6 +805,11 @@ static inline int ROUND_UP(int a, int base)
 	return ((a+base-1)/base)*base;
 }
 
+static inline int is_subarray(char *vers)
+{
+	return (*vers == '/');
+}
+
 #define	LEVEL_MULTIPATH		(-4)
 #define	LEVEL_LINEAR		(-1)
 #define	LEVEL_FAULTY		(-5)

util.c

@@ -821,7 +821,7 @@ struct supertype *super_by_fd(int fd)
 		sprintf(version, "%d.%d", vers, minor);
 		verstr = version;
 	}
-	if (minor == -2 && verstr[0] == '/') {
+	if (minor == -2 && is_subarray(verstr)) {
 		char *dev = verstr+1;
 		subarray = strchr(dev, '/');
 		int devnum;