servers/procfs/const.h

   1 #ifndef _PROCFS_CONST_H
   2 #define _PROCFS_CONST_H
   3
   4 /* The minimum number of inodes depends on a number of factors:
   5  * - Each statically created inode (e.g., /proc/hz) needs an inode. As of
   6  *   writing, this requires about a dozen inodes.
   7  * - Deleted inodes that are still in use by VFS must be retained. For deleted
   8  *   directories, all their containing directories up to the root must be
   9  *   retained as well (to allow the user to "cd .." out). VTreeFS already takes
  10  *   care of this. In the case of ProcFS, only PID-based directories can be
  11  *   deleted; no other directories are dynamically created. These directories
  12  *   currently do not contain subdirectories, either. Hence, for deleted open
  13  *   inodes, we need to reserve at most NR_VNODES inodes in the worst case.
  14  * - In order for getdents to be able to return all PID-based directories,
  15  *   inodes must not be recycled while generating the list of these PID-based
  16  *   directories. In the worst case, this means (NR_TASKS + NR_PROCS) extra
  17  *   inodes.
  18  * The sum of these is the bare minimum for correct operation in all possible
  19  * circumstances. In practice, not all open files will be deleted files in
  20  * ProcFS, and not all process slots will be in use either, so the average use
  21  * will be a lot less. However, setting the value too low allows for a
  22  * potential denial-of-service attack by a non-root user.
  23  *
  24  * For the moment, we simply set this value to something reasonable.
  25  */
  26 #define NR_INODES       ((NR_TASKS + NR_PROCS) * 4)
  27
  28 /* Various file modes. */
  29 #define REG_ALL_MODE    (S_IFREG | 0444)        /* world-readable regular */
  30 #define DIR_ALL_MODE    (S_IFDIR | 0555)        /* world-accessible directory */
  31 #define LNK_ALL_MODE    (S_IFLNK | 0777)        /* symbolic link */
  32
  33 #endif /* _PROCFS_CONST_H */