On Fri, Aug 09, 2019 at 02:42:26PM +0200, Jan Kara wrote:
> Hello,
>
> This series is derived from Thomas' series to get rid of bit spinlocks in
> buffer head code. These patches convert BH_State bit spinlock to an ordinary
> spinlock inside struct journal_head and somewhat reduce the critical section
> under BH_JournalHead bit spinlock so that it is fine for RT.
>
> Motivation from original Thomas' series:
>
> Bit spinlocks are problematic if PREEMPT_RT is enabled. They disable
> preemption, which is undesired for latency reasons and breaks when regular
> spinlocks are taken within the bit_spinlock locked region because regular
> spinlocks are converted to 'sleeping spinlocks' on RT.
>
> Bit spinlocks are also not covered by lock debugging, e.g. lockdep. With
> the spinlock substitution in place, they can be exposed via a new config
> switch: CONFIG_DEBUG_BIT_SPINLOCKS.
>
> Ted, can you pick up these patches? Thanks!
I've landed this patch set on the ext4 git tree. Thanks!
- Ted
