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>

1 files changed, 14 insertions, 1 deletions

diff --git a/msg.c b/msg.c
index 78fd7f7e..013bcb99 100644
--- a/msg.c
+++ b/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;