diff --git a/Assemble.c b/Assemble.c
index c7563ab2..fa5ad07e 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -23,6 +23,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"xmalloc.h"
 
 #include	<ctype.h>
@@ -120,7 +121,7 @@ static int is_member_busy(char *metadata_version)
 			continue;
 
 		/* Skip first char - it can be '/' or '-' */
-		if (strcmp(&ent->metadata_version[10], metadata_version + 1) == 0) {
+		if (strcmp(&ent->metadata_version[MD_VER_EXT_LEN + 1], metadata_version + 1) == 0) {
 			busy = 1;
 			break;
 		}
diff --git a/Detail.c b/Detail.c
index 108e9ba8..d9924b03 100644
--- a/Detail.c
+++ b/Detail.c
@@ -23,6 +23,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"xmalloc.h"
 
 #include	<ctype.h>
@@ -683,10 +684,10 @@ int Detail(char *dev, struct context *c)
 					de->d_name);
 				if (load_sys(path, vbuf, sizeof(vbuf)) < 0)
 					continue;
-				if (strncmp(vbuf, "external:", 9) ||
-				    !is_subarray(vbuf + 9) ||
-				    strncmp(vbuf + 10, sra->sys_name, nlen) ||
-				    vbuf[10 + nlen] != '/')
+				if (strncmp(vbuf, MD_VER_EXT, MD_VER_EXT_LEN) ||
+				    !is_subarray(vbuf + MD_VER_EXT_LEN) ||
+				    strncmp(vbuf + MD_VER_EXT_LEN + 1, sra->sys_name, nlen) ||
+				    vbuf[MD_VER_EXT_LEN + 1 + nlen] != '/')
 					continue;
 				devid = devnm2devid(de->d_name);
 				printf(" %s",
diff --git a/Grow.c b/Grow.c
index 083b1c26..f28abfee 100644
--- a/Grow.c
+++ b/Grow.c
@@ -22,6 +22,7 @@
  *    Email: <neilb@suse.de>
  */
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"dlink.h"
 #include	"xmalloc.h"
 
@@ -696,7 +697,7 @@ static int check_idle(struct supertype *st)
 		if (!is_container_member(e, container))
 			continue;
 		/* frozen array is not idle*/
-		if (e->percent >= 0 || e->metadata_version[9] == '-') {
+		if (e->percent >= 0 || e->metadata_version[MD_VER_BLOCKED_IDX] == '-') {
 			is_idle = 0;
 			break;
 		}
diff --git a/Incremental.c b/Incremental.c
index f717c9c3..8b748041 100644
--- a/Incremental.c
+++ b/Incremental.c
@@ -29,6 +29,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"xmalloc.h"
 #include	"udev.h"
 
diff --git a/Kill.c b/Kill.c
index 9f05a1ac..b41896c5 100644
--- a/Kill.c
+++ b/Kill.c
@@ -26,6 +26,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 
 int Kill(char *dev, struct supertype *st, int force, int verbose, int noexcl)
 {
diff --git a/Manage.c b/Manage.c
index b53e65e9..539c05e8 100644
--- a/Manage.c
+++ b/Manage.c
@@ -23,6 +23,7 @@
  */
 
 #include "mdadm.h"
+#include "mdstat.h"
 #include "udev.h"
 #include "xmalloc.h"
 
@@ -48,12 +49,12 @@ int Manage_ro(char *devname, int fd, int readonly)
 	    mdi->array.major_version == -1 &&
 	    is_subarray(mdi->text_version)) {
 		char vers[64];
-		strcpy(vers, "external:");
+		strcpy(vers, MD_VER_EXT);
 		strcat(vers, mdi->text_version);
 		if (readonly > 0) {
 			int rv;
 			/* We set readonly ourselves. */
-			vers[9] = '-';
+			vers[MD_VER_BLOCKED_IDX] = '-';
 			sysfs_set_str(mdi, NULL, "metadata_version", vers);
 
 			close_fd(&fd);
@@ -63,7 +64,7 @@ int Manage_ro(char *devname, int fd, int readonly)
 				pr_err("failed to set readonly for %s: %s\n",
 					devname, strerror(errno));
 
-				vers[9] = mdi->text_version[0];
+				vers[MD_VER_BLOCKED_IDX] = mdi->text_version[0];
 				sysfs_set_str(mdi, NULL, "metadata_version", vers);
 				rv = 1;
 				goto out;
@@ -71,13 +72,13 @@ int Manage_ro(char *devname, int fd, int readonly)
 		} else {
 			char *cp;
 			/* We cannot set read/write - must signal mdmon */
-			vers[9] = '/';
+			vers[MD_VER_BLOCKED_IDX] = '/';
 			sysfs_set_str(mdi, NULL, "metadata_version", vers);
 
-			cp = strchr(vers+10, '/');
+			cp = strchr(vers + MD_VER_BLOCKED_IDX + 1, '/');
 			if (cp)
 				*cp = 0;
-			ping_monitor(vers+10);
+			ping_monitor(vers + MD_VER_BLOCKED_IDX + 1);
 			if (mdi->array.level <= 0)
 				sysfs_set_str(mdi, NULL, "array_state", "active");
 		}
@@ -278,7 +279,8 @@ int Manage_stop(char *devname, int fd, int verbose, int will_retry)
 		mds = mdstat_read(0, 0);
 		for (m = mds; m; m = m->next)
 			if (is_mdstat_ent_external(m) &&
-			    metadata_container_matches(m->metadata_version + 9, devnm)) {
+			    metadata_container_matches(m->metadata_version + MD_VER_EXT_LEN,
+			    devnm)) {
 				if (verbose >= 0)
 					pr_err("Cannot stop container %s: member %s still active\n",
 					       devname, m->devnm);
diff --git a/config.c b/config.c
index 373acd48..71f5718c 100644
--- a/config.c
+++ b/config.c
@@ -23,6 +23,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"dlink.h"
 #include	"xmalloc.h"
 
diff --git a/managemon.c b/managemon.c
index 74b64bfc..cdeadf3a 100644
--- a/managemon.c
+++ b/managemon.c
@@ -103,6 +103,7 @@
 #define _GNU_SOURCE
 #endif
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"mdmon.h"
 #include	"xmalloc.h"
 
diff --git a/mapfile.c b/mapfile.c
index 33d40d9e..981a1aa9 100644
--- a/mapfile.c
+++ b/mapfile.c
@@ -43,6 +43,7 @@
  * at compile time via MAP_DIR and MAP_FILE.
  */
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"xmalloc.h"
 
 #include	<sys/file.h>
diff --git a/md_common.h b/md_common.h
new file mode 100644
index 00000000..7e0c5d7d
--- /dev/null
+++ b/md_common.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * md_common - constants shared between md driver abstractions.
+ */
+
+#ifndef MD_COMMON_H
+#define MD_COMMON_H
+
+/*
+ * Prefix used by the md driver version to mark an externally-managed array or
+ * container. The full form is:
+ *
+ *   "external:" [/-] containername [/subarray]
+ *
+ * The '/' or '-' separator distinguishes normal read-write arrays from those
+ * that mdmon must not reconfigure (read-only, reshaping, etc.).
+ */
+#define MD_EXT                  "external" /* The external keyword used in various contexts */
+
+#define MD_VER_EXT	        "external:" /* The "external:" version const prefix */
+#define MD_VER_EXT_LEN	(sizeof(MD_VER_EXT) - 1) /* Length of external prefix */
+
+/* Index of the character that blocks the version.
+ * It is the one after the prefix so the array index is MD_VER_EXT_LEN
+ */
+#define MD_VER_BLOCKED_IDX (MD_VER_EXT_LEN)
+
+#endif
diff --git a/mdadm.c b/mdadm.c
index b3b66cdb..81e8c0a3 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -26,6 +26,7 @@
  */
 
 #include "mdadm.h"
+#include "mdstat.h"
 #include "md_p.h"
 #include "xmalloc.h"
 
diff --git a/mdadm.h b/mdadm.h
index 78f498a7..f2cbbe8a 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -684,36 +684,6 @@ typedef struct mapping {
 	int num;
 } mapping_t;
 
-struct mdstat_ent {
-	char		devnm[32];
-	int		active;
-	char		*level;
-	char		*pattern; /* U for up, _ for down */
-	int		percent; /* -1 if no resync */
-	int		resync; /* 3 if check, 2 if reshape, 1 if resync, 0 if recovery */
-	int		devcnt;
-	int		raid_disks;
-	char *		metadata_version;
-	struct dev_member {
-		char			*name;
-		struct dev_member	*next;
-	}		*members;
-	struct mdstat_ent *next;
-};
-
-extern struct mdstat_ent *mdstat_read(int hold, int start);
-extern void mdstat_close(void);
-extern void free_mdstat(struct mdstat_ent *ms);
-extern int mdstat_wait(int seconds);
-extern void mdstat_wait_fd(int fd, const sigset_t *sigmask);
-extern int mddev_busy(char *devnm);
-extern struct mdstat_ent *mdstat_by_component(char *name);
-extern struct mdstat_ent *mdstat_find_by_member_name(struct mdstat_ent *mdstat, char *member_devnm);
-extern struct mdstat_ent *mdstat_by_subdev(char *subdev, char *container);
-
-extern bool is_mdstat_ent_external(struct mdstat_ent *ent);
-extern bool is_mdstat_ent_subarray(struct mdstat_ent *ent);
-
 struct map_ent {
 	struct map_ent *next;
 	char	devnm[32];
@@ -1727,8 +1697,6 @@ extern int is_mddev(char *dev);
 extern int open_container(int fd);
 extern int metadata_container_matches(char *metadata, char *devnm);
 extern int metadata_subdev_matches(char *metadata, char *devnm);
-extern bool is_container_member(struct mdstat_ent *ent, char *devname);
-extern int is_subarray_active(char *subarray, char *devname);
 extern int open_subarray(char *dev, char *subarray, struct supertype *st, int quiet);
 extern struct superswitch *version_to_superswitch(char *vers);
 
@@ -1823,11 +1791,6 @@ static inline int is_subarray(char *vers)
 	return (*vers == '/' || *vers == '-');
 }
 
-static inline char *to_subarray(struct mdstat_ent *ent, char *container)
-{
-	return &ent->metadata_version[10+strlen(container)+1];
-}
-
 /**
  * signal_s() - Wrapper for sigaction() with signal()-like interface.
  * @sig: The signal to set the signal handler to.
diff --git a/mdmon.c b/mdmon.c
index 302d0248..037602ab 100644
--- a/mdmon.c
+++ b/mdmon.c
@@ -64,6 +64,7 @@
 #endif
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"mdmon.h"
 #include	"xmalloc.h"
 
diff --git a/mdmon.h b/mdmon.h
index 37f5841a..a68499b1 100644
--- a/mdmon.h
+++ b/mdmon.h
@@ -84,9 +84,6 @@ void do_manager(struct supertype *container);
 extern volatile sig_atomic_t sigterm;
 
 int read_dev_state(int fd);
-bool is_container_member(struct mdstat_ent *mdstat, char *container);
-
-struct mdstat_ent *mdstat_read(int hold, int start);
 
 extern int exit_now, manager_ready;
 extern int mon_tid, mgr_tid;
diff --git a/mdmonitor.c b/mdmonitor.c
index 314dafb4..b06fa46a 100644
--- a/mdmonitor.c
+++ b/mdmonitor.c
@@ -23,6 +23,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"udev.h"
 #include	"xmalloc.h"
 
@@ -892,7 +893,8 @@ static int check_array(struct state *st, struct mdstat_ent *mdstat,
 
 	if (is_mdstat_ent_subarray(mse)) {
 		char *sl;
-		snprintf(st->parent_devnm, MD_NAME_MAX, "%s", mse->metadata_version + 10);
+		snprintf(st->parent_devnm, MD_NAME_MAX, "%s",
+			 mse->metadata_version + MD_VER_EXT_LEN + 1);
 		sl = strchr(st->parent_devnm, '/');
 		if (sl)
 			*sl = 0;
@@ -1005,7 +1007,7 @@ static int add_new_arrays(struct mdstat_ent *mdstat, struct state **statelist)
 				char *sl;
 
 				snprintf(st->parent_devnm, MD_NAME_MAX, "%s",
-					 mse->metadata_version + 10);
+					 mse->metadata_version + MD_VER_EXT_LEN + 1);
 				sl = strchr(st->parent_devnm, '/');
 				if (sl)
 					*sl = 0;
@@ -1306,8 +1308,8 @@ int Wait(char *dev)
 		}
 		if (!e || e->percent == RESYNC_NONE) {
 			if (e && is_mdstat_ent_external(e)) {
-				if (is_subarray(&e->metadata_version[9]))
-					ping_monitor(&e->metadata_version[9]);
+				if (is_subarray(&e->metadata_version[MD_VER_EXT_LEN]))
+					ping_monitor(&e->metadata_version[MD_VER_EXT_LEN]);
 				else
 					ping_monitor(devnm);
 			}
diff --git a/mdopen.c b/mdopen.c
index 9af0284b..e196aa80 100644
--- a/mdopen.c
+++ b/mdopen.c
@@ -23,6 +23,7 @@
  */
 
 #include "mdadm.h"
+#include "mdstat.h"
 #include "udev.h"
 #include "md_p.h"
 #include "xmalloc.h"
diff --git a/mdstat.c b/mdstat.c
index 8d97a2fc..f7f89ea8 100644
--- a/mdstat.c
+++ b/mdstat.c
@@ -79,6 +79,7 @@
  */
 
 #include	"mdadm.h"
+#include	"mdstat.h"
 #include	"dlink.h"
 #include	"xmalloc.h"
 
@@ -155,14 +156,14 @@ bool is_mdstat_ent_external(struct mdstat_ent *ent)
 	if (!ent->metadata_version)
 		return false;
 
-	if (strncmp(ent->metadata_version, "external:", 9) == 0)
+	if (strncmp(ent->metadata_version, MD_VER_EXT, MD_VER_EXT_LEN) == 0)
 		return true;
 	return false;
 }
 
 bool is_mdstat_ent_subarray(struct mdstat_ent *ent)
 {
-	if (is_mdstat_ent_external(ent) && is_subarray(ent->metadata_version + 9))
+	if (is_mdstat_ent_external(ent) && is_subarray(ent->metadata_version + MD_VER_EXT_LEN))
 		return true;
 	return false;
 }
@@ -170,12 +171,27 @@ bool is_mdstat_ent_subarray(struct mdstat_ent *ent)
 bool is_container_member(struct mdstat_ent *mdstat, char *container)
 {
 	if (is_mdstat_ent_external(mdstat) &&
-	    metadata_container_matches(mdstat->metadata_version + 9, container))
+	    metadata_container_matches(mdstat->metadata_version + MD_VER_EXT_LEN, container))
 		return true;
 
 	return false;
 }
 
+int is_subarray_active(char *subarray, char *container)
+{
+	struct mdstat_ent *mdstat = mdstat_read(0, 0);
+	struct mdstat_ent *ent;
+
+	for (ent = mdstat; ent; ent = ent->next)
+		if (is_container_member(ent, container))
+			if (strcmp(to_subarray(ent, container), subarray) == 0)
+				break;
+
+	free_mdstat(mdstat);
+
+	return ent != NULL;
+}
+
 static int mdstat_fd = -1;
 struct mdstat_ent *mdstat_read(int hold, int start)
 {
@@ -493,9 +509,9 @@ struct mdstat_ent *mdstat_by_subdev(char *subdev, char *container)
 		if (!is_mdstat_ent_external(ent))
 			continue;
 
-		if (!metadata_container_matches(ent->metadata_version + 9, container))
+		if (!metadata_container_matches(ent->metadata_version + MD_VER_EXT_LEN, container))
 			continue;
-		if (!metadata_subdev_matches(ent->metadata_version + 9, subdev))
+		if (!metadata_subdev_matches(ent->metadata_version + MD_VER_EXT_LEN, subdev))
 			continue;
 
 		break;
diff --git a/mdstat.h b/mdstat.h
new file mode 100644
index 00000000..227a68b2
--- /dev/null
+++ b/mdstat.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef MDSTAT_H
+#define MDSTAT_H
+
+#include <signal.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include "md_common.h"
+
+struct mdstat_ent {
+	char devnm[32];
+
+	char *metadata_version;
+	int raid_disks;
+	char *pattern;		/* U for up, _ for down */
+	char *level;
+	int percent;		/* -1 if no resync */
+	int active;
+	int resync;		/* 3 if check, 2 if reshape, 1 if resync, 0 if recovery */
+	int devcnt;
+
+	struct dev_member {
+		char *name;
+		struct dev_member *next;
+	} *members;
+	struct mdstat_ent *next;
+};
+
+struct mdstat_ent *mdstat_find_by_member_name(struct mdstat_ent *mdstat, char *member_devnm);
+struct mdstat_ent *mdstat_by_subdev(char *subdev, char *container);
+struct mdstat_ent *mdstat_by_component(char *name);
+struct mdstat_ent *mdstat_read(int hold, int start);
+
+void free_mdstat(struct mdstat_ent *ms);
+void mdstat_close(void);
+
+void mdstat_wait_fd(int fd, const sigset_t *sigmask);
+int mdstat_wait(int seconds);
+int mddev_busy(char *devnm);
+
+bool is_mdstat_ent_external(struct mdstat_ent *ent);
+bool is_mdstat_ent_subarray(struct mdstat_ent *ent);
+bool is_container_member(struct mdstat_ent *ent, char *devname);
+
+int is_subarray_active(char *subarray, char *container);
+
+static inline char *to_subarray(struct mdstat_ent *ent, char *container)
+{
+	/* Skip: "external:" prefix, [/-] separator, container name, '/'. */
+	return &ent->metadata_version[MD_VER_EXT_LEN + 1 + strlen(container) + 1];
+}
+
+#endif
diff --git a/msg.c b/msg.c
index 0cc7fc5d..19e59186 100644
--- a/msg.c
+++ b/msg.c
@@ -29,6 +29,7 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 #include "mdadm.h"
+#include "mdstat.h"
 #include "mdmon.h"
 #include "xmalloc.h"
 
@@ -251,7 +252,7 @@ int unblock_subarray(struct mdinfo *sra, const int unfreeze)
 	int rc = 0;
 
 	if (sra) {
-		sprintf(buf, "external:%s\n", sra->text_version);
+		sprintf(buf, MD_VER_EXT "%s\n", sra->text_version);
 		buf[9] = '/';
 	} else
 		buf[9] = '-';
@@ -270,7 +271,7 @@ int block_subarray(struct mdinfo *sra)
 	char buf[64];
 	int rc = 0;
 
-	sprintf(buf, "external:%s\n", sra->text_version);
+	sprintf(buf, MD_VER_EXT "%s\n", sra->text_version);
 	buf[9] = '-';
 	if (sysfs_set_str(sra, NULL, "metadata_version", buf))
 		rc = -1;
diff --git a/super-intel.c b/super-intel.c
index c158a271..dd268d23 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -19,6 +19,7 @@
 
 #define HAVE_STDINT_H 1
 #include "mdadm.h"
+#include "mdstat.h"
 #include "mdmon.h"
 #include "dlink.h"
 #include "drive_encryption.h"
@@ -7082,8 +7083,9 @@ active_arrays_by_format(char *name, char* hba, struct md_list **devlist,
 	int found;
 
 	for (memb = mdstat ; memb ; memb = memb->next) {
-		if (is_mdstat_ent_external(memb) && !is_subarray(memb->metadata_version + 9) &&
-		    strcmp(&memb->metadata_version[9], name) == 0 && memb->members) {
+		if (is_mdstat_ent_external(memb) &&
+		    !is_subarray(memb->metadata_version + MD_VER_EXT_LEN) &&
+		    strcmp(&memb->metadata_version[MD_VER_EXT_LEN], name) == 0 && memb->members) {
 			struct dev_member *dev = memb->members;
 			int fd = -1;
 
@@ -13190,7 +13192,7 @@ static int set_bitmap_sysfs(struct mdinfo *info, unsigned long long chunksize,
 	 * related to the device's first lba (in opposition to the "internal" case
 	 * when this value is related to the beginning of the superblock).
 	 */
-	if (sysfs_set_str(info, NULL, "bitmap/metadata", "external")) {
+	if (sysfs_set_str(info, NULL, "bitmap/metadata", MD_EXT)) {
 		dprintf("failed to set bitmap/metadata\n");
 		return -1;
 	}
diff --git a/sysfs.c b/sysfs.c
index 7589e944..96bfd5a7 100644
--- a/sysfs.c
+++ b/sysfs.c
@@ -24,6 +24,7 @@
  */
 
 #include	"mdadm.h"
+#include	"md_common.h"
 #include	"dlink.h"
 #include	"xmalloc.h"
 
@@ -293,10 +294,10 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 			sra->array.major_version =
 				sra->array.minor_version = -1;
 			strcpy(sra->text_version, "");
-		} else if (strncmp(buf, "external:", 9) == 0) {
+		} else if (strncmp(buf, MD_VER_EXT, MD_VER_EXT_LEN) == 0) {
 			sra->array.major_version = -1;
 			sra->array.minor_version = -2;
-			strcpy(sra->text_version, buf+9);
+			strcpy(sra->text_version, buf + MD_VER_EXT_LEN);
 			sra->text_version[sizeof(sra->text_version) - 1] = '\0';
 		} else {
 			sscanf(buf, "%d.%d",
@@ -809,7 +810,7 @@ int sysfs_set_array(struct mdinfo *info)
 	    info->array.minor_version == -2) {
 		char buf[SYSFS_MAX_BUF_SIZE];
 
-		strcat(strcpy(ver, "external:"), info->text_version);
+		strcat(strcpy(ver, MD_VER_EXT), info->text_version);
 
 		/* meta version might already be set if we are setting
 		 * new geometry for a reshape.  In that case we don't
@@ -819,8 +820,9 @@ int sysfs_set_array(struct mdinfo *info)
 		 */
 		if (sysfs_get_str(info, NULL, "metadata_version",
 				  buf, sizeof(buf)) > 0)
-			if (strlen(buf) >= 9 && buf[9] == '-')
-				ver[9] = '-';
+			if (strlen(buf) >= MD_VER_BLOCKED_IDX &&
+			    buf[MD_VER_BLOCKED_IDX] == '-')
+				ver[MD_VER_BLOCKED_IDX] = '-';
 
 		if (sysfs_set_str(info, NULL, "metadata_version", ver) < 0) {
 			pr_err("This kernel does not support external metadata.\n");
diff --git a/util.c b/util.c
index cdc55435..3bd4829a 100644
--- a/util.c
+++ b/util.c
@@ -23,6 +23,7 @@
  */
 
 #include	"mdadm.h"
+#include	"md_common.h"
 #include	"md_p.h"
 #include	"xmalloc.h"
 
@@ -1559,7 +1560,7 @@ int open_container(int fd)
 		if (n <= 0 || (unsigned)n >= sizeof(buf))
 			continue;
 		buf[n] = 0;
-		if (strncmp(buf, "external", 8) != 0 ||
+		if (strncmp(buf, MD_EXT, strlen(MD_EXT)) != 0 ||
 		    n < 10 ||
 		    buf[9] == '/')
 			continue;
@@ -1635,21 +1636,6 @@ int metadata_subdev_matches(char *metadata, char *devnm)
 	return 0;
 }
 
-int is_subarray_active(char *subarray, char *container)
-{
-	struct mdstat_ent *mdstat = mdstat_read(0, 0);
-	struct mdstat_ent *ent;
-
-	for (ent = mdstat; ent; ent = ent->next)
-		if (is_container_member(ent, container))
-			if (strcmp(to_subarray(ent, container), subarray) == 0)
-				break;
-
-	free_mdstat(mdstat);
-
-	return ent != NULL;
-}
-
 /* open_subarray - opens a subarray in a container
  * @dev: container device name
  * @st: empty supertype