Re: [PATCH 1/6] md: Revert "md: Don't register sync_thread for reshape directly"

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

Hi,

在 2024/02/29 23:49, Xiao Ni 写道:
> This reverts commit ad39c08186f8a0f221337985036ba86731d6aafe.
>
> Function stop_sync_thread only wakes up sync task. It also needs to
> wake up sync thread. This problem will be fixed in the following
> patch.

I don't think so, unlike mddev->thread, sync_thread will only be
executed once and must be executed each time it's registered, and caller
must make sure to wake up registered sync_thread.

Thanks,
Kuai
> Signed-off-by: Xiao Ni <xni@xxxxxxxxxx>
> ---
>   drivers/md/md.c     |  5 +----
>   drivers/md/raid10.c | 16 ++++++++++++++--
>   drivers/md/raid5.c  | 29 +++++++++++++++++++++++++++--
>   3 files changed, 42 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 9e41a9aaba8b..db4743ba7f6c 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -9376,7 +9376,6 @@ static void md_start_sync(struct work_struct *ws)
>   	struct mddev *mddev = container_of(ws, struct mddev, sync_work);
>   	int spares = 0;
>   	bool suspend = false;
> -	char *name;
>   
>   	/*
>   	 * If reshape is still in progress, spares won't be added or removed
> @@ -9414,10 +9413,8 @@ static void md_start_sync(struct work_struct *ws)
>   	if (spares)
>   		md_bitmap_write_all(mddev->bitmap);
>   
> -	name = test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ?
> -			"reshape" : "resync";
>   	rcu_assign_pointer(mddev->sync_thread,
> -			   md_register_thread(md_do_sync, mddev, name));
> +			   md_register_thread(md_do_sync, mddev, "resync"));
>   	if (!mddev->sync_thread) {
>   		pr_warn("%s: could not start resync thread...\n",
>   			mdname(mddev));
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index a5f8419e2df1..7412066ea22c 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -4175,7 +4175,11 @@ static int raid10_run(struct mddev *mddev)
>   		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
>   		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
>   		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> -		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> +		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> +		rcu_assign_pointer(mddev->sync_thread,
> +			md_register_thread(md_do_sync, mddev, "reshape"));
> +		if (!mddev->sync_thread)
> +			goto out_free_conf;
>   	}
>   
>   	return 0;
> @@ -4569,8 +4573,16 @@ static int raid10_start_reshape(struct mddev *mddev)
>   	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
>   	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
>   	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> -	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> +	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> +
> +	rcu_assign_pointer(mddev->sync_thread,
> +			   md_register_thread(md_do_sync, mddev, "reshape"));
> +	if (!mddev->sync_thread) {
> +		ret = -EAGAIN;
> +		goto abort;
> +	}
>   	conf->reshape_checkpoint = jiffies;
> +	md_wakeup_thread(mddev->sync_thread);
>   	md_new_event();
>   	return 0;
>   
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 6a7a32f7fb91..8497880135ee 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -7936,7 +7936,11 @@ static int raid5_run(struct mddev *mddev)
>   		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
>   		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
>   		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> -		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> +		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> +		rcu_assign_pointer(mddev->sync_thread,
> +			md_register_thread(md_do_sync, mddev, "reshape"));
> +		if (!mddev->sync_thread)
> +			goto abort;
>   	}
>   
>   	/* Ok, everything is just fine now */
> @@ -8502,8 +8506,29 @@ static int raid5_start_reshape(struct mddev *mddev)
>   	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
>   	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
>   	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
> -	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> +	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
> +	rcu_assign_pointer(mddev->sync_thread,
> +			   md_register_thread(md_do_sync, mddev, "reshape"));
> +	if (!mddev->sync_thread) {
> +		mddev->recovery = 0;
> +		spin_lock_irq(&conf->device_lock);
> +		write_seqcount_begin(&conf->gen_lock);
> +		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
> +		mddev->new_chunk_sectors =
> +			conf->chunk_sectors = conf->prev_chunk_sectors;
> +		mddev->new_layout = conf->algorithm = conf->prev_algo;
> +		rdev_for_each(rdev, mddev)
> +			rdev->new_data_offset = rdev->data_offset;
> +		smp_wmb();
> +		conf->generation--;
> +		conf->reshape_progress = MaxSector;
> +		mddev->reshape_position = MaxSector;
> +		write_seqcount_end(&conf->gen_lock);
> +		spin_unlock_irq(&conf->device_lock);
> +		return -EAGAIN;
> +	}
>   	conf->reshape_checkpoint = jiffies;
> +	md_wakeup_thread(mddev->sync_thread);
>   	md_new_event();
>   	return 0;
>   }