[PATCH v2] md/r5cache: run_no_space_stripes() when R5C_LOG_CRITICAL == 0

[PATCH v2] md/r5cache: run_no_space_stripes() when R5C_LOG_CRITICAL == 0

[Song Liu]

With writeback cache, we define log space critical as

   free_space < 2 * reclaim_required_space

So the deassert of R5C_LOG_CRITICAL could happen when
  1. free_space increases
  2. reclaim_required_space decreases

Currently, run_no_space_stripes() is called when 1 happens, but
not (always) when 2 happens.

With this patch, run_no_space_stripes() is call when
R5C_LOG_CRITICAL is cleared.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
 drivers/md/raid5-cache.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index e786d4e..c36f86b 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -370,6 +370,7 @@ static inline void r5c_update_log_state(struct r5l_log *log)
 	struct r5conf *conf = log->rdev->mddev->private;
 	sector_t free_space;
 	sector_t reclaim_space;
+	bool wake_reclaim = false;
 
 	if (!r5c_is_writeback(log))
 		return;
@@ -379,12 +380,18 @@ static inline void r5c_update_log_state(struct r5l_log *log)
 	reclaim_space = r5c_log_required_to_flush_cache(conf);
 	if (free_space < 2 * reclaim_space)
 		set_bit(R5C_LOG_CRITICAL, &conf->cache_state);
-	else
+	else {
+		if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
+			wake_reclaim = true;
 		clear_bit(R5C_LOG_CRITICAL, &conf->cache_state);
+	}
 	if (free_space < 3 * reclaim_space)
 		set_bit(R5C_LOG_TIGHT, &conf->cache_state);
 	else
 		clear_bit(R5C_LOG_TIGHT, &conf->cache_state);
+
+	if (wake_reclaim)
+		r5l_wake_reclaim(log, 0);
 }
 
 /*
@@ -1345,6 +1352,10 @@ static void r5c_do_reclaim(struct r5conf *conf)
 		spin_unlock(&conf->device_lock);
 		spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
 	}
+
+	if (!test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
+		r5l_run_no_space_stripes(log);
+
 	md_wakeup_thread(conf->mddev->thread);
 }
 
@@ -2401,6 +2412,7 @@ void r5c_finish_stripe_write_out(struct r5conf *conf,
 	spin_unlock_irq(&conf->log->stripe_in_journal_lock);
 	sh->log_start = MaxSector;
 	atomic_dec(&conf->log->stripe_in_journal_count);
+	r5c_update_log_state(conf->log);
 }
 
 int
-- 
2.9.3

Re: [PATCH v2] md/r5cache: run_no_space_stripes() when R5C_LOG_CRITICAL == 0

[Shaohua Li]

On Wed, Nov 30, 2016 at 04:57:54PM -0800, Song Liu wrote:
> With writeback cache, we define log space critical as
> 
>    free_space < 2 * reclaim_required_space
> 
> So the deassert of R5C_LOG_CRITICAL could happen when
>   1. free_space increases
>   2. reclaim_required_space decreases
> 
> Currently, run_no_space_stripes() is called when 1 happens, but
> not (always) when 2 happens.
> 
> With this patch, run_no_space_stripes() is call when
> R5C_LOG_CRITICAL is cleared.
> 
> Signed-off-by: Song Liu <songliubraving@fb.com>

applied, thanks!

> ---
>  drivers/md/raid5-cache.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> index e786d4e..c36f86b 100644
> --- a/drivers/md/raid5-cache.c
> +++ b/drivers/md/raid5-cache.c
> @@ -370,6 +370,7 @@ static inline void r5c_update_log_state(struct r5l_log *log)
>  	struct r5conf *conf = log->rdev->mddev->private;
>  	sector_t free_space;
>  	sector_t reclaim_space;
> +	bool wake_reclaim = false;
>  
>  	if (!r5c_is_writeback(log))
>  		return;
> @@ -379,12 +380,18 @@ static inline void r5c_update_log_state(struct r5l_log *log)
>  	reclaim_space = r5c_log_required_to_flush_cache(conf);
>  	if (free_space < 2 * reclaim_space)
>  		set_bit(R5C_LOG_CRITICAL, &conf->cache_state);
> -	else
> +	else {
> +		if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
> +			wake_reclaim = true;
>  		clear_bit(R5C_LOG_CRITICAL, &conf->cache_state);
> +	}
>  	if (free_space < 3 * reclaim_space)
>  		set_bit(R5C_LOG_TIGHT, &conf->cache_state);
>  	else
>  		clear_bit(R5C_LOG_TIGHT, &conf->cache_state);
> +
> +	if (wake_reclaim)
> +		r5l_wake_reclaim(log, 0);
>  }
>  
>  /*
> @@ -1345,6 +1352,10 @@ static void r5c_do_reclaim(struct r5conf *conf)
>  		spin_unlock(&conf->device_lock);
>  		spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
>  	}
> +
> +	if (!test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
> +		r5l_run_no_space_stripes(log);
> +
>  	md_wakeup_thread(conf->mddev->thread);
>  }
>  
> @@ -2401,6 +2412,7 @@ void r5c_finish_stripe_write_out(struct r5conf *conf,
>  	spin_unlock_irq(&conf->log->stripe_in_journal_lock);
>  	sh->log_start = MaxSector;
>  	atomic_dec(&conf->log->stripe_in_journal_count);
> +	r5c_update_log_state(conf->log);
>  }
>  
>  int
> -- 
> 2.9.3
> 
> --
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