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SubjectRe: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore
On 07/17, Dave Chinner wrote:
>
> On Thu, Jul 16, 2015 at 07:32:56PM +0200, Oleg Nesterov wrote:
> >
> > #ifdef CONFIG_LOCKDEP
> > /*
> > * We want lockdep to tell us about possible deadlocks with freezing but
> > * it's it bit tricky to properly instrument it. Getting a freeze protection
> > * works as getting a read lock but there are subtle problems. XFS for example
> > * gets freeze protection on internal level twice in some cases, which is OK
>
> Sorry, I've missed something here - where is XFS nesting
> sb_start_intwrite() calls?

Heh ;) I too tried to understand thi but failed. I was not surprized,
I know nothing about fs/.

Dave, I didn't write this comment. Please look at acquire_freeze_lock().
If we can remove this logic - great! but this needs a separate change.

Oleg.



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