mdadm/mdopen: create new function create_named_array for writing to new_array

Split 'write to new_array' out into a function named create_named_array.
And fixed a trivial compiling warning 'warn_unused_result' against commit:
fdbf7aaa1956 (mdopen: call "modprobe md_mod" if it might be needed.)

Suggested-by: NeilBrown <neilb@suse.com>
Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>

diff --git a/mdopen.c b/mdopen.c
index dcdc6f23e6c14176a2278c3d67110545891fd4ee..4ec13f5eb5979a66234976115e1d466f7e005d76 100644 (file)
--- a/mdopen.c
+++ b/mdopen.c
@@ -100,6 +100,31 @@ void make_parts(char *dev, int cnt)
        free(name);
 }
 
+int create_named_array(char *devnm)
+{
+       int fd;
+       int n = -1;
+       static const char new_array_file[] = {
+               "/sys/module/md_mod/parameters/new_array"
+       };
+
+       fd = open(new_array_file, O_WRONLY);
+       if (fd < 0 && errno == ENOENT) {
+               if (system("modprobe md_mod") == 0)
+                       fd = open(new_array_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, new_array_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 +331,19 @@ 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();
                }