1. 05 Nov, 2002 1 commit
    • Andrew Morton's avatar
      [PATCH] `event' removal: core kernel · 4ccf7a32
      Andrew Morton authored
      Patch from Manfred Spraul
      
      f_version and i_version are used by filesystems to check if it can
      reuse the f_pos position across readdir calls without validation.
      
      Right now f_version and i_version are modified by
          f_version = ++event;
          i_version = ++event;
          if (f_version != i_version) goto revalidate
      and event is a global, exported variable.
      
      But that's not needed,
          f_version  = 0;
          i_version++;
          if (f_version != i_version) goto revalidate
      works too, without the ugly 'event' variable.
      
      I got an ok from viro, and I had notified the fs maintainers, no
      complaints either
      
      - block_dev.c, block_llseek updates f_version to '++event'.
         grep showed that no device driver uses f_version, this is dead
         code copied from the default llseek implementation.
      
      - the llseek implementations and get_empty_flip set f_version
         to '++event'
         This is not dead code, but
                  filp->f_version = 0
         achieves the same effect:
         f_version is used by the readdir() implementation of several
         filesystems to skip the revalidation of f_pos at the beginning
         of a readdir call: If llseek was not called and the filesystem
         did not change since the last readdir call, then the value in
         f_pos can be trusted.
         The implementation (for example in ext2) is
           inode->i_version = ++event;
         in all operations that change a directory
         At the beginning of file_operation->readdir():
           if(inode->i_version != flip->f_version)
                      revalidate();
           filp->f_version = inode->i_version;
         There are other users of f_version, but none of them use the
         default llseek implementation (e.g. fs/pipe.c)
      4ccf7a32
  2. 04 Nov, 2002 7 commits
  3. 03 Nov, 2002 32 commits