.  It's
  considerably saner wrt "is the subtree busy" logics, but it's nowhere
  near being ready for merge at the moment; this changeset is one of the
  things becoming possible with that sucker, but it certainly shouldn't
  have been picked during this cycle.  My apologies..."

Noticed-by: Eric Paris <eparis@redhat.com>
Requested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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