On Thu, Oct 12, 2017 at 04:59:01PM +0000, Bart Van Assche wrote:
> On Wed, 2017-10-11 at 12:32 -0700, Shaohua Li wrote:
> > On Wed, Oct 11, 2017 at 05:17:56PM +0000, Bart Van Assche wrote:
> > > On Tue, 2017-10-10 at 18:48 -0700, Shaohua Li wrote:
> > > > The problem is __md_stop_writes set some bit like MD_RECOVERY_FROZEN, which
> > > > will prevent md_check_recovery restarting resync/reshape. I think we need
> > > > preserve mddev->recovery in suspend prepare and restore after resume
> > >
> > > Hello Shaohua,
> > >
> > > As far as I can see __md_stop_writes() sets MD_RECOVERY_FROZEN and can set
> > > MD_RECOVERY_INTR. Since md_check_recovery() clears MD_RECOVERY_INTR I think
> > > it should be sufficient to save and restore the state of the
> > > MD_RECOVERY_FROZEN flag. However, when I ran the following test:
> > > * echo frozen > /sys/block/md0/md/sync_action
> > > * cat /sys/block/md0/md/sync_action
> > > * systemctl hibernate
> > > * (power on system again)
> > > * cat /sys/block/md0/md/sync_action
> > >
> > > the output that appeared was as follows:
> > >
> > > frozen
> > > idle
> > > Does that mean that a hibernate or suspend followed by a resume is sufficient
> > > to clear the MD_RECOVERY_FROZEN flag for the md drivers and hence that the
> > > patch at the start of this e-mail thread does not need any further
> > > modifications?
> >
> > Have no idea why it shows 'idle'. From my understanding, after resume, previous
> > memory is stored and MD_RECOVERY_FROZEN bit should be set. Was trying to
> > understand what happens.
>
> Hello Shaohua,
>
> I think a user space action causes the MD_RECOVERY_FROZEN bit to be cleared.
> After I had added a few debug statements in the md driver this is what I
> found in the system log:
>
> Oct 12 09:38:39 kernel: action_store: storing action check
> Oct 12 09:38:39 kernel: md: data-check of RAID array md0
> Oct 12 09:38:40 systemd[1]: Starting Hibernate...
> Oct 12 09:38:40 kernel: md: md0: data-check interrupted.
> [ powered on system manually ]
> Oct 12 09:39:05 kernel: action_store: storing action check
> Oct 12 09:39:05 kernel: md: data-check of RAID array md0
> Oct 12 09:39:11 kernel: action_store: storing action idle
> Oct 12 09:39:11 kernel: md: md0: data-check interrupted.
>
> Anyway, how about the patch below? I have verified by adding a debug pr_info()
> statement that the newly added code really clears the MD_RECOVERY_FROZEN bit.
Ok, for patch 1-3:
Reviewed-by: Shaohua Li <shli@xxxxxxxxxx>
> Subject: [PATCH] md: Neither resync nor reshape while the system is frozen
>
> 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.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
> Cc: Shaohua Li <shli@xxxxxxxxxx>
> Cc: linux-raid@xxxxxxxxxxxxxxx
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxxx>
> Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
> ---
> drivers/md/md.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
> drivers/md/md.h | 8 ++++++++
> 2 files changed, 57 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index b99584e5d6b1..8b2fc750f97f 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(),
> @@ -8944,6 +8947,8 @@ static void md_stop_all_writes(void)
> int need_delay = 0;
>
> for_each_mddev(mddev, tmp) {
> + mddev->frozen_before_suspend =
> + test_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
> if (mddev_trylock(mddev)) {
> if (mddev->pers)
> __md_stop_writes(mddev);
> @@ -8963,6 +8968,47 @@ static void md_stop_all_writes(void)
> mdelay(1000*1);
> }
>
> +static void md_restore_frozen_flag(void)
> +{
> + struct list_head *tmp;
> + struct mddev *mddev;
> +
> + for_each_mddev(mddev, tmp) {
> + if (mddev->frozen_before_suspend)
> + set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
> + else
> + clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
> + }
> +}
> +
> +/*
> + * 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;
> + case PM_POST_HIBERNATION:
> + case PM_POST_SUSPEND:
> + case PM_POST_RESTORE:
> + md_restore_frozen_flag();
> + 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 +9055,7 @@ 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 +9295,7 @@ 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);
>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index d8287d3cd1bf..727b3aef4d26 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -356,6 +356,14 @@ struct mddev {
> */
> int recovery_disabled;
>
> + /* Writes are stopped before hibernation, suspend and restore by
> + * calling md_stop_all_writes(). That function sets the
> + * MD_RECOVERY_FROZEN flag. The value of that flag is saved before
> + * writes are stopped such that it can be restored after hibernation,
> + * suspend or restore have finished.
> + */
> + bool frozen_before_suspend;
> +
> int in_sync; /* know to not need resync */
> /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
> * that we are never stopping an array while it is open.
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