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

[NeilBrown <neilb@suse.com>]

[-- Attachment #1: Type: text/plain, Size: 1454 bytes --]

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]