linux-kernel - Re: [PATCH v5 7/8] md: sync blockdev before stopping raid or setting readonly

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Date: Fri, 2 Feb 2024 10:12:08 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: linan666@...weicloud.com, song@...nel.org, neilb@...e.com,
 mariusz.tkaczyk@...ux.intel.com, shli@...com
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
 yi.zhang@...wei.com, houtao1@...wei.com, yangerkun@...wei.com,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v5 7/8] md: sync blockdev before stopping raid or setting
 readonly

Hi,

在 2024/02/01 14:34, linan666@...weicloud.com 写道:
> From: Li Nan <linan122@...wei.com>
> 
> Commit a05b7ea03d72 ("md: avoid crash when stopping md array races
> with closing other open fds.") added sync_block before stopping raid and
> setting readonly. Later in commit 260fa034ef7a ("md: avoid deadlock when
> dirty buffers during md_stop.") it is moved to ioctl. array_state_store()
> was ignored. Add sync blockdev to array_state_store() now.

You're not just adding sync_blockdev() here. Please rewrite the tittle
and commit message.

> 
> Signed-off-by: Li Nan <linan122@...wei.com>
> ---
>   drivers/md/md.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 4c7a0225f77d..86becf0015f5 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4493,6 +4493,16 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
>   	case broken:		/* cannot be set */
>   	case bad_word:
>   		return -EINVAL;
> +	case clear:
> +	case readonly:
> +	case inactive:
> +	case read_auto:
> +		if (!mddev->pers || !md_is_rdwr(mddev))
> +			break;
> +		err = mddev_set_closing_and_sync_blockdev(mddev);

In this context, mddev->openers should be zero, and such check is in
do_md_stop() and md_set_readonly():

if (atomic_read(&mddev->openers) > !!bdev).

Thanks,
Kuai

> +		if (err)
> +			return err;
> +		break;
>   	default:
>   		break;
>   	}
> @@ -4518,6 +4528,7 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
>   		spin_unlock(&mddev->lock);
>   		return err ?: len;
>   	}
> +
>   	err = mddev_lock(mddev);
>   	if (err)
>   		return err;
> @@ -4592,6 +4603,11 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
>   		sysfs_notify_dirent_safe(mddev->sysfs_state);
>   	}
>   	mddev_unlock(mddev);
> +
> +	if (st == readonly || st == read_auto || st == inactive ||
> +	    (err && st == clear))
> +		clear_bit(MD_CLOSING, &mddev->flags);
> +
>   	return err ?: len;
>   }
>   static struct md_sysfs_entry md_array_state =
>