Add ping_monitor() to mdadm --wait

The action we are waiting for may not be complete until the monitor has
had a chance to take action on the result.

The following script can now remove the device on the first attempt,
versus a few attempts with the original Wait():
#!/bin/bash
#export MDADM_NO_MDMON=1
export IMSM_DEVNAME_AS_SERIAL=1
./mdadm -Ss
./mdadm --zero-superblock /dev/loop[0-3]
echo 2 > /proc/sys/dev/raid/speed_limit_max
./mdadm --create /dev/imsm /dev/loop[0-3] -n 4 -e imsm -a md
./mdadm --create /dev/md/r1 /dev/loop[0-3] -n 4 -l 5 --force -a mdp
./mdadm --fail /dev/md/r1 /dev/loop3
./mdadm --wait /dev/md/r1
x=0
while  ! ./mdadm --remove /dev/imsm /dev/loop3 > /dev/null 2>&1
do
        x=$((x+1))
done
echo "removed after $x attempts"
./mdadm --add /dev/imsm /dev/loop3

Include 2 small cleanups:
* remove the almost open coded fd2devnum() in Wait() by introducing a
  new utility routine stat2devnum()
* teach connect_monitor() to parse the container device from a subarray
  string

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

Manage.c

@@ -167,8 +167,6 @@ int Manage_runstop(char *devname, int fd, int runstop, int quiet)
 		if (mdi &&
 		    mdi->array.level > 0 &&
 		    is_subarray(mdi->text_version)) {
-			char *cp;
-
 			/* This is mdmon managed. */
 			close(fd);
 			if (sysfs_set_str(mdi, NULL,
@@ -181,10 +179,7 @@ int Manage_runstop(char *devname, int fd, int runstop, int quiet)
 			}
 
 			/* Give monitor a chance to act */
-			cp = strchr(mdi->text_version+1, '/');
-			if (*cp)
-				*cp = 0;
-			ping_monitor(mdi->text_version+1);
+			ping_monitor(mdi->text_version);
 
 			fd = open(devname, O_RDONLY);
 		} else if (mdi &&

Monitor.c

@@ -602,10 +602,7 @@ int Wait(char *dev)
 			strerror(errno));
 		return 2;
 	}
-	if (major(stb.st_rdev) == MD_MAJOR)
-		devnum = minor(stb.st_rdev);
-	else
-		devnum = -1-(minor(stb.st_rdev)/64);
+	devnum = stat2devnum(&stb);
 
 	while(1) {
 		struct mdstat_ent *ms = mdstat_read(1, 0);
@@ -616,6 +613,13 @@ int Wait(char *dev)
 				break;
 
 		if (!e || e->percent < 0) {
+			if (e &&
+			    strncmp(e->metadata_version, "external:", 9) == 0) {
+				if (is_subarray(&e->metadata_version[9]))
+					ping_monitor(&e->metadata_version[9]);
+				else
+					ping_monitor(devnum2devname(devnum));
+			}
 			free_mdstat(ms);
 			return rv;
 		}

mdadm.h

@@ -785,6 +785,7 @@ extern int start_mdmon(int devnum);
 
 extern char *devnum2devname(int num);
 extern int devname2devnum(char *name);
+extern int stat2devnum(struct stat *st);
 extern int fd2devnum(int fd);
 
 static inline int dev2major(int d)

msg.c

@@ -144,8 +144,21 @@ int connect_monitor(char *devname)
 	int sfd;
 	long fl;
 	struct sockaddr_un addr;
+	int pos;
+	char *c;
+
+	pos = sprintf(path, "/var/run/mdadm/");
+	if (is_subarray(devname)) {
+		devname++;
+		c = strchr(devname, '/');
+		if (!c)
+			return -1;
+		snprintf(&path[pos], c - devname + 1, "%s", devname);
+		pos += c - devname;
+	} else
+		pos += sprintf(&path[pos], "%s", devname);
+	sprintf(&path[pos], ".sock");
 
-	sprintf(path, "/var/run/mdadm/%s.sock", devname);
 	sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 	if (sfd < 0)
 		return -1;

util.c

@@ -1022,16 +1022,23 @@ int devname2devnum(char *name)
 	return num;
 }
 
+int stat2devnum(struct stat *st)
+{
+	if ((S_IFMT & st->st_mode) == S_IFBLK) {
+		if (major(st->st_rdev) == MD_MAJOR)
+			return minor(st->st_rdev);
+		else
+			return -1- (minor(st->st_rdev)>>6);
+	}
+	return -1;
+
+}
+
 int fd2devnum(int fd)
 {
 	struct stat stb;
-	if (fstat(fd, &stb) == 0 &&
-	    (S_IFMT&stb.st_mode)==S_IFBLK) {
-		if (major(stb.st_rdev) == MD_MAJOR)
-			return minor(stb.st_rdev);
-		else
-			return -1- (minor(stb.st_rdev)>>6);
-	}
+	if (fstat(fd, &stb) == 0)
+		return stat2devnum(&stb);
 	return -1;
 }