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Date: Tue, 21 May 2024 10:30:20 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Su Yue <l@...enly.org>, Yu Kuai <yukuai1@...weicloud.com>
Cc: agk@...hat.com, snitzer@...nel.org, mpatocka@...hat.com, song@...nel.org,
xni@...hat.com, 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 2024/05/20 19:51, Su Yue 写道:
>
> On Thu 09 May 2024 at 09:18, 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] = {
>>
>
> Th array will not be modified, so:
>
> static const char * const action_names[NR_SYNC_ACTIONS]
Yes, this make sense.
>
>> + [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;
> My brain was lost sometimes looking into nested conditions of md code...
> I agree with Xiao Ni's suggestion that more comments about the array
> state should be added.
Okay, perhaps you're refering md_is_rdwr()? which is supposed to be
related to "no new sync_thread is requestd", perhaps following is
better:
/* only read-write array can start sync_thread */
if (!(md_is_rdwr(mddev))
return ACTION_IDLE;
/* sync_thread is not running, and no new sync_thread is requested */
if (!test_bit(MD_RECOVERY_RUNNING, &recovery) &&
!test_bit(MD_RECOVERY_NEEDED, &recovery)
return ACTION_IDLE;
>
>> + if (test_bit(MD_RECOVERY_RESHAPE, &recovery) ||
>> + mddev->reshape_position != MaxSector)
>> + return ACTION_RESHAPE;
>> +
>> + if (test_bit(MD_RECOVERY_RECOVER, &recovery))
>> + return ACTION_RECOVER;
>> +
>>
> In action_show, MD_RECOVERY_SYNC is tested first then MD_RECOVERY_RECOVER.
> After looking through the logic of MD_RECOVERY_RECOVER clear/set_bit, the
> change is fine to me. However, better to follow old pattern unless there
> have resons.
It's just because MD_RECOVERY_SYNC is more complicated, and I move it to
the last, just programming habits. :)
>
>
>> + 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;
>> +}
>> +
>> +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)
>>
>
> And 'const char *'
Yes
Thanks,
Kuai
>
> --
> Su
>
>> +{
>> + 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);
> .
>
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