[PATCH] md/raid10: wait up frozen array in handle_write_completed

[PATCH] md/raid10: wait up frozen array in handle_write_completed

[Guoqing Jiang]

Since nr_queued is changed, we need to call wake_up here
if the array is already frozen and waiting for condition
"nr_pending == nr_queued + extra" to be true.

And commit 824e47daddbf ("RAID1: avoid unnecessary spin
locks in I/O barrier code") which has already added the
wake_up for raid1.

Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
---
 drivers/md/raid10.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 4167091..acb3f46 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2704,6 +2704,11 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
 			list_add(&r10_bio->retry_list, &conf->bio_end_io_list);
 			conf->nr_queued++;
 			spin_unlock_irq(&conf->device_lock);
+			/*
+			 * In case freeze_array() is waiting for condition
+			 * nr_pending == nr_queued + extra to be true.
+			 */
+			wake_up(&conf->wait_barrier);
 			md_wakeup_thread(conf->mddev->thread);
 		} else {
 			if (test_bit(R10BIO_WriteError,
-- 
2.10.0

Re: [PATCH] md/raid10: wait up frozen array in handle_write_completed

[NeilBrown]

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On Mon, Apr 17 2017, Guoqing Jiang wrote:

> Since nr_queued is changed, we need to call wake_up here
> if the array is already frozen and waiting for condition
> "nr_pending == nr_queued + extra" to be true.
>
> And commit 824e47daddbf ("RAID1: avoid unnecessary spin
> locks in I/O barrier code") which has already added the
> wake_up for raid1.
>
> Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
> ---
>  drivers/md/raid10.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 4167091..acb3f46 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -2704,6 +2704,11 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
>  			list_add(&r10_bio->retry_list, &conf->bio_end_io_list);
>  			conf->nr_queued++;
>  			spin_unlock_irq(&conf->device_lock);
> +			/*
> +			 * In case freeze_array() is waiting for condition
> +			 * nr_pending == nr_queued + extra to be true.
> +			 */
> +			wake_up(&conf->wait_barrier);
>  			md_wakeup_thread(conf->mddev->thread);
>  		} else {
>  			if (test_bit(R10BIO_WriteError,
> -- 
> 2.10.0

Reviewed-by: NeilBrown <neilb@suse.com>

I think I looked at this once before and convinced myself that
md_wakeup_thread() would wake up the only thread that might be waiting
in freeze_array().  This is completely wrong, so I don't know why I
thought it:-(

Thanks,
NeilBrown

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Re: [PATCH] md/raid10: wait up frozen array in handle_write_completed

[Shaohua Li]

On Mon, Apr 17, 2017 at 05:11:05PM +0800, Guoqing Jiang wrote:
> Since nr_queued is changed, we need to call wake_up here
> if the array is already frozen and waiting for condition
> "nr_pending == nr_queued + extra" to be true.
> 
> And commit 824e47daddbf ("RAID1: avoid unnecessary spin
> locks in I/O barrier code") which has already added the
> wake_up for raid1.

thanks, applied!
 
> Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
> ---
>  drivers/md/raid10.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 4167091..acb3f46 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -2704,6 +2704,11 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
>  			list_add(&r10_bio->retry_list, &conf->bio_end_io_list);
>  			conf->nr_queued++;
>  			spin_unlock_irq(&conf->device_lock);
> +			/*
> +			 * In case freeze_array() is waiting for condition
> +			 * nr_pending == nr_queued + extra to be true.
> +			 */
> +			wake_up(&conf->wait_barrier);
>  			md_wakeup_thread(conf->mddev->thread);
>  		} else {
>  			if (test_bit(R10BIO_WriteError,
> -- 
> 2.10.0
>