Re: Question about pseudo filesystems

From: Alexander Viro (viro@math.psu.edu)
Date: Sat Sep 07 2002 - 14:47:00 EST


On Sat, 7 Sep 2002, Jamie Lokier wrote:

> Alexander Viro wrote:
> > If your rules are "it's pinned as long as there are opened files created
> > by foo()" - very well, there are two variants. The basic idea is the same
> > - have sum of ->mnt_count for all vfsmounts of our type bumped whenever we
> > call foo() and drop whenever final fput() is done on a file created by foo().
>
> Thanks -- that's what I implemented, except I used a semaphore instead
> of a spinlock.
>
> I wanted to check that it's safe to call `mntput' from `->release()',
> which seems like quite a dubious thing to depend on. But if you say it
> is safe, that's cool.

It is neither safe nor needed. Please, look at the previous posting again -
neither variant calls mntput() in ->release().

Now, __fput() _does_ call mntput() - always. And yes, if that happens to
be the final reference - it's OK.

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