shadowfs

[Kalle Olavi Niemitalo <tosi@stekt.oulu.fi>]

Tomasz Wegrzanowski <maniek@beer.com> writes:

> Am I very wrong
> or readonly shadowfs
> needs only to check, upon open request,
> if file exist on first fs
>   if not, if on the next one, etc,
> and if yes forward everything to good fs
> and if not return simple error ???

If the file is actually a directory, shadowfs should open
directories with that name in all many file systems it can, and
set up a nested shadowfs.  Symlinks to directories should be left
as symlinks; if the shadowfs showed them as directories, its
clients could get in infinite loops.

Hmmh -- what happens if the user:

- creates directories ~/1 and ~/2 and sets up sets up a shadowfs
  ~/shadow which merges them

- creates a directory ~/1/dir

- changes directory to ~/shadow/dir: This should give him either
  a reparented ~/1/dir or a shadowfs which forwards to it.

- creates a directory ~/2/dir and then a file ~/2/dir/file

- attempts to open file in the current directory (~/shadow/dir):
  Can this be made to work?  The shadowfs doesn't have a port to
  ~/2/dir yet -- it would have to notice that ~/2/dir was created
  after ~/shadow/dir was opened.  <hurd/fs.defs> has a routine
  dir_notice_changes; would the shadowfs have to use that?