linux-kernel - Re: [PATCH md-6.10 2/9] md: add a new enum type sync

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Message-ID: <CALTww28Qjce6jG+v6=8vubiBWoCt5=21_-VE6hgOMU2HZxnF=g@mail.gmail.com>
Date: Tue, 14 May 2024 14:13:30 +0800
From: Xiao Ni <xni@...hat.com>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: agk@...hat.com, snitzer@...nel.org, mpatocka@...hat.com, song@...nel.org, 
	dm-devel@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	linux-raid@...r.kernel.org, yukuai3@...wei.com, yi.zhang@...wei.com, 
	yangerkun@...wei.com
Subject: Re: [PATCH md-6.10 2/9] md: add a new enum type sync_action

On Mon, May 13, 2024 at 6:19 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@...wei.com>
>
> In order to make code related to sync_thread cleaner in following
> patches, also add detail comment about each sync action.
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>  drivers/md/md.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 56 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 2a1cb7b889e5..2edad966f90a 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -34,6 +34,61 @@
>   */
>  #define        MD_FAILFAST     (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT)
>
> +/* Status of sync thread. */
> +enum sync_action {
> +       /*
> +        * Represent by MD_RECOVERY_SYNC, start when:
> +        * 1) after assemble, sync data from first rdev to other copies, this
> +        * must be done first before other sync actions and will only execute
> +        * once;
> +        * 2) resize the array(notice that this is not reshape), sync data for
> +        * the new range;
> +        */
> +       ACTION_RESYNC,
> +       /*
> +        * Represent by MD_RECOVERY_RECOVER, start when:
> +        * 1) for new replacement, sync data based on the replace rdev or
> +        * available copies from other rdev;
> +        * 2) for new member disk while the array is degraded, sync data from
> +        * other rdev;
> +        * 3) reassemble after power failure or re-add a hot removed rdev, sync
> +        * data from first rdev to other copies based on bitmap;
> +        */
> +       ACTION_RECOVER,
> +       /*
> +        * Represent by MD_RECOVERY_SYNC | MD_RECOVERY_REQUESTED |
> +        * MD_RECOVERY_CHECK, start when user echo "check" to sysfs api

Same question with patch 01 here

Regards
Xiao

> +        * sync_action, used to check if data copies from differenct rdev are
> +        * the same. The number of mismatch sectors will be exported to user
> +        * by sysfs api mismatch_cnt;
> +        */
> +       ACTION_CHECK,
> +       /*
> +        * Represent by MD_RECOVERY_SYNC | MD_RECOVERY_REQUESTED, start when
> +        * user echo "repair" to sysfs api sync_action, usually paired with
> +        * ACTION_CHECK, used to force syncing data once user found that there
> +        * are inconsistent data,
> +        */
> +       ACTION_REPAIR,
> +       /*
> +        * Represent by MD_RECOVERY_RESHAPE, start when new member disk is added
> +        * to the conf, notice that this is different from spares or
> +        * replacement;
> +        */
> +       ACTION_RESHAPE,
> +       /*
> +        * Represent by MD_RECOVERY_FROZEN, can be set by sysfs api sync_action
> +        * or internal usage like setting the array read-only, will forbid above
> +        * actions.
> +        */
> +       ACTION_FROZEN,
> +       /*
> +        * All above actions don't match.
> +        */
> +       ACTION_IDLE,
> +       NR_SYNC_ACTIONS,
> +};
> +
>  /*
>   * The struct embedded in rdev is used to serialize IO.
>   */
> @@ -571,7 +626,7 @@ enum recovery_flags {
>         /* interrupted because io-error */
>         MD_RECOVERY_ERROR,
>
> -       /* flags determines sync action */
> +       /* flags determines sync action, see details in enum sync_action */
>
>         /* if just this flag is set, action is resync. */
>         MD_RECOVERY_SYNC,
> --
> 2.39.2
>