Re: [patch 3/7] fs, notify: Add file handle entry into inotify_inode_mark

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 13 Nov 2012 11:20:57 +0400 Cyrill Gorcunov <gorcunov@openvz.org> wrote:

> > >  struct inotify_inode_mark {
> > >  	struct fsnotify_mark fsn_mark;
> > >  	int wd;
> > > +#ifdef INOTIFY_USE_FHANDLE
> > > +	__u8 fhandle[sizeof(struct file_handle) + MAX_HANDLE_SZ];
> > > +#endif
> > >  };
> > 
> > Whoa.  This adds 128+8 bytes to the inotify_inode_mark.  That's a lot of
> > bloat, and there can be a lot of inotify_inode_mark's in the system?
> 
> Yes, that's why it's not turned on by default, only if is c/r turned on.
> iirc I've been said that usually only about 40 bytes is used (in the tests
> I met only 8 bytes). Letme re-check all things.

The question is, how many `struct inotify_inode_mark's are instantiated
system-wide?  Could be millions?

Dumb question: do we really need inotify_inode_mark.fhandle at all? 
What prevents us from assembling this info on demand when ->show_fdinfo() is
called?