quoted

I hadn't noticed that there are two places where we write to new_array.
Maybe that should be split out into a function.
Both should use modprobe if the open fails.

how about this changing? Thanks for your patience to have a look at it.

diff --git a/mdopen.c b/mdopen.c
index dcdc6f2..6d8402d 100644
--- a/mdopen.c
+++ b/mdopen.c

@@ -100,6 +100,29 @@ void make_parts(char *dev, int cnt)
         free(name);
  }

+int create_named_array(char *devnm)
+{
+       const char *file = "/sys/module/md_mod/parameters/new_array";
+       int fd;
+       int n = -1;
+
+       fd = open(file, O_WRONLY);
+       if (fd < 0 && errno == ENOENT) {
+               if (system("modprobe md_mod") == 0)
+                       fd = open(file, O_WRONLY);
+       }
+       if (fd >= 0) {
+               n = write(fd, devnm, strlen(devnm));
+               close(fd);
+       }
+       if (fd < 0 || n != (int)strlen(devnm)) {
+               pr_err("Fail create %s when using %s\n", devnm, file);
+               return 0;
+       }
+
+       return 1;
+}
+
  /*
   * We need a new md device to assemble/build/create an array.
   * 'dev' is a name given us by the user (command line or mdadm.conf)

@@ -306,37 +329,19 @@ int create_mddev(char *dev, char *name, int autof, 

int trustworthy,

         devnm[0] = 0;
         if (num < 0 && cname && ci->names) {
-               int fd;
-               int n = -1;
                 sprintf(devnm, "md_%s", cname);
                 if (block_udev)
                         udev_block(devnm);
-               fd = open("/sys/module/md_mod/parameters/new_array", 
O_WRONLY);
-               if (fd < 0 && errno == ENOENT) {
-                       system("modprobe md_mod");
-                       fd = 
open("/sys/module/md_mod/parameters/new_array", O_WRONLY);
-               }
-               if (fd >= 0) {
-                       n = write(fd, devnm, strlen(devnm));
-                       close(fd);
-               }
-               if (n < 0) {
+               if (!create_named_array(devnm)) {
                         devnm[0] = 0;
                         udev_unblock();
                 }
         }
         if (num >= 0) {
-               int fd;
-               int n = -1;
                 sprintf(devnm, "md%d", num);
                 if (block_udev)
                         udev_block(devnm);
-               fd = open("/sys/module/md_mod/parameters/new_array", 
O_WRONLY);
-               if (fd >= 0) {
-                       n = write(fd, devnm, strlen(devnm));
-                       close(fd);
-               }
-               if (n < 0) {
+               if (!create_named_array(devnm)) {
                         devnm[0] = 0;
                         udev_unblock();
                 }

Thanks,
-Zhilong

quoted

Thanks,
NeilBrown