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Message-ID: <2d457d0f-8bb5-39cb-0b8a-0bfdde1f560f@huaweicloud.com>
Date: Tue, 14 May 2024 16:52:34 +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
在 2024/05/14 16:40, Xiao Ni 写道:
> On Tue, May 14, 2024 at 3:39 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>>
>> 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'.
>
> To be frank, the logic in action_show is easier to understand than the
> logic above. I have taken more than half an hour to think if the logic
> here is right or not. In action_show, it only needs to think when it's
> not idle and it's easy.
>
> Now this patch logic needs to think in the opposite direction: when
> it's idle. And it returns ACTION_IDLE at two places which means it
> still needs to think about when it has sync action. So it's better to
> keep the original logic in action_show now. It's just my 2 cents
> point.
Hi,
but the logical is exactlly the same as action_show(), and there are
no functional changes. I just remove the local variable and return
early, because I think code is cleaner this way...
action_show:
char *type = "idle"
if (test_bit() || xxx) {
if (xxx)
type ="reshape"
else if(xxx)
type ="resync/check/repair"
else if(xxx)
type = "recover"
else if (xxx)
type = "reshape"
-> else is idle
}
-> else is idle
The above two place are corresponding to the new code to return
ACTION_IDLE.
Thanks,
Kuai
>
> Best Regards
> Xiao
>
>>
>> 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
>>>>
>>>
>>> .
>>>
>>
>>
>
> .
>
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