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

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Date: Tue, 14 May 2024 15:39:12 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Xiao Ni <xni@...hat.com>, 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, yi.zhang@...wei.com, yangerkun@...wei.com,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH md-6.10 3/9] md: add new helpers for sync_action

Hi,

在 2024/05/14 14:52, Xiao Ni 写道:
> 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?

Yes, we need this, because they are many places to set
MD_RECOVERY_NEEDED, while there are no sync action actually, this case
is 'idle'.

Thanks,
Kuai

> 
> 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
>>
> 
> .
>