Re: Understanding locking for buf

Reply: Alexander Lochmann : "Re: Understanding locking for buf"
In reply to: Alexander Lochmann : "Re: Understanding locking for buf"
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From: Konstantin Belousov <kostikbel_at_gmail.com>
Date: Tue, 28 Feb 2023 15:37:51 UTC

On Mon, Feb 27, 2023 at 04:04:30PM +0100, Alexander Lochmann wrote:
> 
> 
> On 27.02.23 15:23, Konstantin Belousov wrote:
> > Not quite.  Sync io (bread()) means that caller performs bufwait() on the
> > buffer.  It is still subject to the LK_KERNPROC ownership move.
> Ehm. Has this behavior changed recently?
> Our kernel version uses LK_KERNPROC to distinguish between sync and async
> IO. How would that be possible if ownershipt changes in either case?
> https://iris.cs.tu-dortmund.de/freebsd-lockdoc/latest/source/sys/geom/geom_vfs.c#L127
I think this is simply not _very_ accurate.  It would still catch some sync
operations.