Re: [PATCH v8 03/10] md: Neither resync nor reshape while the system is frozen

[Shaohua Li <shli@kernel.org>]

On Tue, Oct 10, 2017 at 02:03:39PM -0700, Bart Van Assche wrote:
> Some people use the md driver on laptops and use the suspend and
> resume functionality. Since it is essential that submitting of
> new I/O requests stops before a hibernation image is created,
> interrupt the md resync and reshape actions if the system is
> being frozen. Note: the resync and reshape will restart after
> the system is resumed and a message similar to the following
> will appear in the system log:
> 
> md: md0: data-check interrupted.

Where do we restart resync and reshape?
 
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Cc: Shaohua Li <shli@kernel.org>
> Cc: linux-raid@vger.kernel.org
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Johannes Thumshirn <jthumshirn@suse.de>
> ---
>  drivers/md/md.c | 30 +++++++++++++++++++++++++++++-
>  1 file changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index b99584e5d6b1..d712d3320c1d 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -66,6 +66,8 @@
>  #include <linux/raid/md_u.h>
>  #include <linux/slab.h>
>  #include <linux/percpu-refcount.h>
> +#include <linux/freezer.h>
> +#include <linux/suspend.h>
>  
>  #include <trace/events/block.h>
>  #include "md.h"
> @@ -7439,6 +7441,7 @@ static int md_thread(void *arg)
>  	 */
>  
>  	allow_signal(SIGKILL);
> +	set_freezable();
>  	while (!kthread_should_stop()) {
>  
>  		/* We need to wait INTERRUPTIBLE so that
> @@ -7449,7 +7452,7 @@ static int md_thread(void *arg)
>  		if (signal_pending(current))
>  			flush_signals(current);
>  
> -		wait_event_interruptible_timeout
> +		wait_event_freezable_timeout
>  			(thread->wqueue,
>  			 test_bit(THREAD_WAKEUP, &thread->flags)
>  			 || kthread_should_stop() || kthread_should_park(),
> @@ -8963,6 +8966,29 @@ static void md_stop_all_writes(void)
>  		mdelay(1000*1);
>  }
>  
> +/*
> + * Ensure that neither resyncing nor reshaping occurs while the system is
> + * frozen.
> + */
> +static int md_notify_pm(struct notifier_block *bl, unsigned long state,
> +			void *unused)
> +{
> +	pr_debug("%s: state = %ld\n", __func__, state);
> +
> +	switch (state) {
> +	case PM_HIBERNATION_PREPARE:
> +	case PM_SUSPEND_PREPARE:
> +	case PM_RESTORE_PREPARE:
> +		md_stop_all_writes();
> +		break;
> +	}
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block md_pm_notifier = {
> +	.notifier_call	= md_notify_pm,
> +};
> +
>  static int md_notify_reboot(struct notifier_block *this,
>  			    unsigned long code, void *x)
>  {
> @@ -9009,6 +9035,7 @@ static int __init md_init(void)
>  			    md_probe, NULL, NULL);
>  
>  	register_reboot_notifier(&md_reboot_notifier);
> +	register_pm_notifier(&md_pm_notifier);
>  	raid_table_header = register_sysctl_table(raid_root_table);
>  
>  	md_geninit();
> @@ -9248,6 +9275,7 @@ static __exit void md_exit(void)
>  
>  	unregister_blkdev(MD_MAJOR,"md");
>  	unregister_blkdev(mdp_major, "mdp");
> +	unregister_pm_notifier(&md_pm_notifier);
>  	unregister_reboot_notifier(&md_reboot_notifier);
>  	unregister_sysctl_table(raid_table_header);
>  
> -- 
> 2.14.2
>