linux-kernel - Re: [PATCH md-6.10 3/9] md: add new helpers for sync

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Date: Tue, 14 May 2024 14:52:05 +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 3/9] md: add new helpers for sync_action

On Mon, May 13, 2024 at 5:31 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@...wei.com>
>
> The new helpers will get current sync_action of the array, will be used
> in later patches to make code cleaner.
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>  drivers/md/md.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/md/md.h |  3 +++
>  2 files changed, 67 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 00bbafcd27bb..48ec35342d1b 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -69,6 +69,16 @@
>  #include "md-bitmap.h"
>  #include "md-cluster.h"
>
> +static char *action_name[NR_SYNC_ACTIONS] = {
> +       [ACTION_RESYNC]         = "resync",
> +       [ACTION_RECOVER]        = "recover",
> +       [ACTION_CHECK]          = "check",
> +       [ACTION_REPAIR]         = "repair",
> +       [ACTION_RESHAPE]        = "reshape",
> +       [ACTION_FROZEN]         = "frozen",
> +       [ACTION_IDLE]           = "idle",
> +};
> +
>  /* pers_list is a list of registered personalities protected by pers_lock. */
>  static LIST_HEAD(pers_list);
>  static DEFINE_SPINLOCK(pers_lock);
> @@ -4867,6 +4877,60 @@ metadata_store(struct mddev *mddev, const char *buf, size_t len)
>  static struct md_sysfs_entry md_metadata =
>  __ATTR_PREALLOC(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
>
> +enum sync_action md_sync_action(struct mddev *mddev)
> +{
> +       unsigned long recovery = mddev->recovery;
> +
> +       /*
> +        * frozen has the highest priority, means running sync_thread will be
> +        * stopped immediately, and no new sync_thread can start.
> +        */
> +       if (test_bit(MD_RECOVERY_FROZEN, &recovery))
> +               return ACTION_FROZEN;
> +
> +       /*
> +        * idle means no sync_thread is running, and no new sync_thread is
> +        * requested.
> +        */
> +       if (!test_bit(MD_RECOVERY_RUNNING, &recovery) &&
> +           (!md_is_rdwr(mddev) || !test_bit(MD_RECOVERY_NEEDED, &recovery)))
> +               return ACTION_IDLE;

Hi Kuai

Can I think the above judgement cover these two situations:
1. The array is readonly / readauto and it doesn't have
MD_RECOVERY_RUNNING. Now maybe it has MD_RECOVERY_NEEDED, it means one
array may want to do some sync action, but the array state is not
readwrite and it can't start.
2. The array doesn't have MD_RECOVERY_RUNNING and MD_RECOVERY_NEEDED

> +
> +       if (test_bit(MD_RECOVERY_RESHAPE, &recovery) ||
> +           mddev->reshape_position != MaxSector)
> +               return ACTION_RESHAPE;
> +
> +       if (test_bit(MD_RECOVERY_RECOVER, &recovery))
> +               return ACTION_RECOVER;
> +
> +       if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
> +               if (test_bit(MD_RECOVERY_CHECK, &recovery))
> +                       return ACTION_CHECK;
> +               if (test_bit(MD_RECOVERY_REQUESTED, &recovery))
> +                       return ACTION_REPAIR;
> +               return ACTION_RESYNC;
> +       }
> +
> +       return ACTION_IDLE;

Does it need this? I guess it's the reason in case there are other
situations, right?

Regards
Xiao

> +}
> +
> +enum sync_action md_sync_action_by_name(char *page)
> +{
> +       enum sync_action action;
> +
> +       for (action = 0; action < NR_SYNC_ACTIONS; ++action) {
> +               if (cmd_match(page, action_name[action]))
> +                       return action;
> +       }
> +
> +       return NR_SYNC_ACTIONS;
> +}
> +
> +char *md_sync_action_name(enum sync_action action)
> +{
> +       return action_name[action];
> +}
> +
>  static ssize_t
>  action_show(struct mddev *mddev, char *page)
>  {
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 2edad966f90a..72ca7a796df5 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -864,6 +864,9 @@ extern void md_unregister_thread(struct mddev *mddev, struct md_thread __rcu **t
>  extern void md_wakeup_thread(struct md_thread __rcu *thread);
>  extern void md_check_recovery(struct mddev *mddev);
>  extern void md_reap_sync_thread(struct mddev *mddev);
> +extern enum sync_action md_sync_action(struct mddev *mddev);
> +extern enum sync_action md_sync_action_by_name(char *page);
> +extern char *md_sync_action_name(enum sync_action action);
>  extern bool md_write_start(struct mddev *mddev, struct bio *bi);
>  extern void md_write_inc(struct mddev *mddev, struct bio *bi);
>  extern void md_write_end(struct mddev *mddev);
> --
> 2.39.2
>