linux-kernel - Re: [PATCH v2 2/2] md: fix sync_action incorrect display during resync

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Message-ID: <1775d473-a77f-4ac8-8195-8547dd48d754@molgen.mpg.de>
Date: Tue, 12 Aug 2025 11:22:24 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Zheng Qixing <zhengqixing@...weicloud.com>
Cc: song@...nel.org, yukuai3@...wei.com, linan122@...wei.com,
 linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
 yi.zhang@...wei.com, yangerkun@...wei.com, houtao1@...wei.com,
 zhengqixing@...wei.com
Subject: Re: [PATCH v2 2/2] md: fix sync_action incorrect display during
 resync

Dear Zheng,


Thank you for your patch.

Am 12.08.25 um 04:17 schrieb Zheng Qixing:
> From: Zheng Qixing <zhengqixing@...wei.com>
> 
> During raid resync, if a disk becomes faulty, the operation is
> briefly interrupted. The MD_RECOVERY_RECOVER flag triggered by
> the disk failure causes sync_action to incorrectly show "recover"
> instead of "resync". The same issue affects reshape operations.
> 
> Reproduction steps:
>    mdadm -Cv /dev/md1 -l1 -n4 -e1.2 /dev/sd{a..d} // -> resync happended
>    mdadm -f /dev/md1 /dev/sda                     // -> resync interrupted
>    cat sync_action
>    -> recover
> 
> Add progress checks in md_sync_action() for resync/recover/reshape
> to ensure the interface correctly reports the actual operation type.
> 
> Fixes: 4b10a3bc67c1 ("md: ensure resync is prioritized over recovery")
> Signed-off-by: Zheng Qixing <zhengqixing@...wei.com>
> ---
>   drivers/md/md.c | 38 ++++++++++++++++++++++++++++++++++++--
>   1 file changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 4ea956a80343..798428d0870b 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4845,9 +4845,34 @@ static bool rdev_needs_recovery(struct md_rdev *rdev, sector_t sectors)
>   	return false;
>   }
>   
> +static enum sync_action md_get_active_sync_action(struct mddev *mddev)
> +{
> +	struct md_rdev *rdev;
> +	bool is_recover = false;

`is_recover` sounds strange to me, but I am not an expert with the code. 
Maybe `needs_recovery`?

> +
> +	if (mddev->resync_offset < MaxSector)
> +		return ACTION_RESYNC;
> +
> +	if (mddev->reshape_position != MaxSector)
> +		return ACTION_RESHAPE;
> +
> +	rcu_read_lock();
> +	rdev_for_each_rcu(rdev, mddev) {
> +		if (rdev->raid_disk >= 0 &&
> +		    rdev_needs_recovery(rdev, MaxSector)) {
> +			is_recover = true;
> +			break;
> +		}
> +	}
> +	rcu_read_unlock();
> +
> +	return is_recover ? ACTION_RECOVER : ACTION_IDLE;
> +}
> +
>   enum sync_action md_sync_action(struct mddev *mddev)
>   {
>   	unsigned long recovery = mddev->recovery;
> +	enum sync_action active_action;
>   
>   	/*
>   	 * frozen has the highest priority, means running sync_thread will be
> @@ -4871,8 +4896,17 @@ enum sync_action md_sync_action(struct mddev *mddev)
>   	    !test_bit(MD_RECOVERY_NEEDED, &recovery))
>   		return ACTION_IDLE;
>   
> -	if (test_bit(MD_RECOVERY_RESHAPE, &recovery) ||
> -	    mddev->reshape_position != MaxSector)
> +	/*
> +	 * Check if any sync operation (resync/recover/reshape) is
> +	 * currently active. This ensures that only one sync operation
> +	 * can run at a time. Returns the type of active operation, or
> +	 * ACTION_IDLE if none are active.
> +	 */
> +	active_action = md_get_active_sync_action(mddev);
> +	if (active_action != ACTION_IDLE)
> +		return active_action;
> +
> +	if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
>   		return ACTION_RESHAPE;
>   
>   	if (test_bit(MD_RECOVERY_RECOVER, &recovery))

Reviewed-by: Paul Menzel <pmenzel@...gen.mpg.de>


Kind regards,

Paul