Re: bd_mount_mutex -> bd_mount_sem (was Re: xfs_file_ioctl / xfs_freeze: BUG: warning at kernel/mutex-debug.c:80/debug_mutex_unlock())

[Eric Sandeen <sandeen@sandeen.net>]

Andrew Morton wrote:
> On Mon, 08 Jan 2007 21:12:40 -0600
> Eric Sandeen <sandeen@sandeen.net> wrote:
>
> > Andrew Morton wrote:
> > > On Tue, 9 Jan 2007 10:47:28 +1100
> > > David Chinner <dgc@sgi.com> wrote:
> > >
> > > > On Mon, Jan 08, 2007 at 10:40:54AM -0600, Eric Sandeen wrote:
> > > > > Sami Farin wrote:
> > > > > > On Mon, Jan 08, 2007 at 08:37:34 +1100, David Chinner wrote:
> > > > > > ...
> > > > > > > > fstab was there just fine after -u.
> > > > > > > Oh, that still hasn't been fixed?
> > > > > > Looked like it =)
> > > > > Hm, it was proposed upstream a while ago:
> > > > >
> > > > > http://lkml.org/lkml/2006/9/27/137
> > > > >
> > > > > I guess it got lost?
> > > > Seems like it. Andrew, did this ever get queued for merge?
> > > Seems not.  I think people were hoping that various nasties in there
> > > would go away.  We return to userspace with a kernel lock held??
> > Is a semaphore any worse than the current mutex in this respect?  At 
> > least unlocking from another thread doesn't violate semaphore rules.  :)
>
> I assume that if we weren't returning to userspace with a lock held, this
> mutex problem would simply go away.

Well nobody's asserting that the filesystem must always be locked & 
unlocked by the same thread, are they?  That'd be a strange rule to 
enforce upon the userspace doing the filesystem management wouldn't it? 
 Or am I thinking about this wrong...

-Eric
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