+ char path[256];
+ char *e;
+ DIR *dir;
+ struct dirent *de;
+ int dfd, n;
+ char buf[200];
+ int major, minor;
+ struct stat st;
+
+ if (fstat(fd, &st) != 0)
+ return -1;
+ sprintf(path, "/sys/dev/block/%d:%d/holders",
+ (int)major(st.st_rdev), (int)minor(st.st_rdev));
+ e = path + strlen(path);
+
+ dir = opendir(path);
+ if (!dir)
+ return -1;
+ while ((de = readdir(dir))) {
+ if (de->d_ino == 0)
+ continue;
+ if (de->d_name[0] == '.')
+ continue;
+ sprintf(e, "/%s/dev", de->d_name);
+ dfd = open(path, O_RDONLY);
+ if (dfd < 0)
+ continue;
+ n = read(dfd, buf, sizeof(buf));
+ close(dfd);
+ if (n <= 0 || n >= sizeof(buf))
+ continue;
+ buf[n] = 0;
+ if (sscanf(buf, "%d:%d", &major, &minor) != 2)
+ continue;
+ sprintf(buf, "%d:%d", major, minor);
+ dfd = dev_open(buf, O_RDONLY);
+ if (dfd >= 0) {
+ closedir(dir);
+ return dfd;
+ }
+ }
+ closedir(dir);
+ return -1;
+}
+
+char *devnum2devname(int num)
+{
+ char name[100];
+ if (num > 0)
+ sprintf(name, "md%d", num);
+ else
+ sprintf(name, "md_d%d", -1-num);
+ return strdup(name);
+}
+
+int devname2devnum(char *name)
+{
+ char *ep;
+ int num;
+ if (strncmp(name, "md_d", 4)==0)
+ num = -1-strtoul(name+4, &ep, 10);
+ else
+ num = strtoul(name+2, &ep, 10);
+ return num;
+}
+
+int fd2devnum(int fd)
+{