On Mon, Apr 28, 2008 at 10:15 AM, Al Viro<viro@xxxxxxxxxxxxxxxxxx> wrote:On Mon, Apr 28, 2008 at 03:13:09AM +0100, Al Viro wrote:
> On Mon, Apr 28, 2008 at 10:10:22AM +0800, Dave Young wrote:
> > [Fixing bug 10504]
> >
> > If the bakingfile is a block device file, losetuo -d will trigger lockdep
> > warning of "circular locking dependency".
> >
> > open/release lock order : bdev->bd_mutex ---> lo->lo_ctl_mutex
> > loop_clr_fd lock order : lo->lo_ctl_mutex ---> bdev->bd_mutex (fput)
> >
> > Don't hold the lo_ctl_mutex while fput in loop_clr_fd to fix it. It's safe
> > because all loop device state will be consistent here.
>
> Explain.
Hi, Maybe I have some mis-understood, thanks for pointing out in advance.
IMO the lo_ctl_mutex is for the lo->* state locking, they are all set
to proper values before fput(filp), so I think it's safe to do that.
BTW, explain also why open() at that spot will not do interesting things
wrt BLKRRPART done a bit below, please.
open with a loop device unbound? Sorry, I don't understand. Could you
explain a bit? Thanks