linux-kernel - Re: [PATCH 02/12] md: add a new enum type sync

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Message-ID: <4e8fcdc7-3494-df1d-8654-28ce248850df@huaweicloud.com>
Date: Tue, 11 Jun 2024 21:30:10 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Mariusz Tkaczyk <mariusz.tkaczyk@...ux.intel.com>
Cc: agk@...hat.com, snitzer@...nel.org, mpatocka@...hat.com, song@...nel.org,
 xni@...hat.com, l@...enly.org, dm-devel@...ts.linux.dev,
 linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
 yukuai1@...weicloud.com, yi.zhang@...wei.com, yangerkun@...wei.com,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH 02/12] md: add a new enum type sync_action

Hi,

在 2024/06/11 16:31, Mariusz Tkaczyk 写道:
> On Mon, 3 Jun 2024 20:58:05 +0800
> Yu Kuai <yukuai3@...wei.com> wrote:
> 
>> In order to make code related to sync_thread cleaner in following
>> patches, also add detail comment about each sync action. And also
>> prepare to remove the related recovery_flags in the fulture.
>>
>> 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 170412a65b63..6b9d9246f260 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
>> +	 * 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,
>> +};
> 
> I like if counter is keep in same style as rest enum values, like ACTION_COUNT.

Thanks for the review, however, I didn't find this style "xxx_COUNT" in
md code, AFAIK, "NR_xxx" style is used more, for example:

enum stat_group {
         STAT_READ,
         STAT_WRITE,
         STAT_DISCARD,
         STAT_FLUSH,

         NR_STAT_GROUPS
};

Just to let you know, I'll keep this style in the next version. :)

Thanks,
Kuai
> 
> Anyway LGTM.
> 
> Mariusz
> .
>