Handle device removal from container

[thirdparty/mdadm.git] / sysfs.c

diff --git a/sysfs.c b/sysfs.c
index ae10b1e96c9b186d81a7b9b233cacbcce572ca4b..a28442137c3399cdd3146882c3f3db158698c4d3 100644 (file)
--- a/sysfs.c
+++ b/sysfs.c
@@ -515,3 +515,66 @@ int sysfs_disk_to_scsi_id(int fd, __u32 *id)
 
        return 0;
 }
+
+
+int sysfs_unique_holder(int devnum, long rdev)
+{
+       /* Check that devnum is a holder of rdev,
+        * and is the only holder.
+        * we should be locked against races by
+        * an O_EXCL on devnum
+        */
+       DIR *dir;
+       struct dirent *de;
+       char dirname[100];
+       char l;
+       int found = 0;
+       sprintf(dirname, "/sys/dev/block/%d:%d/holders",
+               major(rdev), minor(rdev));
+       dir = opendir(dirname);
+       errno = ENOENT;
+       if (!dir)
+               return 0;
+       l = strlen(dirname);
+       while ((de = readdir(dir)) != NULL) {
+               char buf[10];
+               int n;
+               int mj, mn;
+               char c;
+               int fd;
+
+               if (de->d_ino == 0)
+                       continue;
+               if (de->d_name[0] == '.')
+                       continue;
+               strcpy(dirname+l, "/");
+               strcat(dirname+l, de->d_name);
+               strcat(dirname+l, "/dev");
+               fd = open(dirname, O_RDONLY);
+               if (fd < 0) {
+                       errno = ENOENT;
+                       break;
+               }
+               n = read(fd, buf, sizeof(buf)-1);
+               close(fd);
+               buf[n] = 0;
+               if (sscanf(buf, "%d:%d%c", &mj, &mn, &c) != 3 ||
+                   c != '\n') {
+                       errno = ENOENT;
+                       break;
+               }
+               if (mj != MD_MAJOR)
+                       mn = -1-(mn>>6);
+
+               if (devnum != mn) {
+                       errno = EEXIST;
+                       break;
+               }
+               found = 1;
+       }
+       closedir(dir);
+       if (de)
+               return 0;
+       else
+               return found;
+}