Re: [PATCH] loop: prevent bdev freeing while device in use

[Al Viro]

On Mon, Apr 01, 2013 at 10:58:55PM -0700, Anatol Pomozov wrote:
> >>
> >> loop_set_fd/loop_clr_fd (and any other loop ioctl) is called under
> >> loop_device->lo_ctl_mutex.
> >
> > Ok, good enough for me, I applied it, and it's commit
> > c1681bf8a7b1b98edee8b862a42c19c4e53205fd in my tree.
> >
> > I assume it should go to stable too, because none of this is new, is
> > it? Did you check how far back this applies? I assume this goes back
> > pretty much forever, no?
> 
> I bisected kernel using test from my commit and it points to
> 4c823cc3d568277aa6340d8df6981e34f4c4dee5 (appeared in kernel 3.2).
> 
> But even despite i cannot repro the crash on 3.0-stable, the
> underlying issue (block_device is not locked) still exists there. So I
> think patch should go to stable as well.

... except that you are doing invalidate *after* having done bdput.  Which
is probably valid (we have the same bdev pinned down by opened file used
to issue the ioclt), but it's a really bad style; this should be in opposite
order.
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