This patch clears mnt_namespace on unmount.

Not clearing mnt_namespace has two effects:

   1) It is possible to attach a new mount to a detached mount,
      because check_mnt() returns true.

      This means, that when no other references to the detached mount
      remain, it still can't be freed.  This causes a resource leak,
      and possibly un-removable modules.

   2) If mnt_namespace is dereferenced (only in mark_mounts_for_expiry())
      after the namspace has been freed, it can cause an Oops, memory
      corruption, etc.

1) has been tested before and after the patch, 2) is only speculation.
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Another rollup of patches which give various symbols static scope
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!