Re: [PATCH md-6.10 3/9] md: add new helpers for sync_action

[Su Yue <l@damenly.org>]

On Tue 21 May 2024 at 11:25, Xiao Ni <xni@redhat.com> wrote:

> On Mon, May 20, 2024 at 8:38 PM Su Yue <l@damenly.org> wrote:
>>
>>
>> On Thu 09 May 2024 at 09:18, Yu Kuai <yukuai1@huaweicloud.com>
>> wrote:
>>
>> > From: Yu Kuai <yukuai3@huawei.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@huawei.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]
>>
>> > +     [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...
>
> agree+
>
>> I agree with Xiao Ni's suggestion that more comments about the
>> array
>> state should be added.
>
> In fact, I suggest to keep the logic which is in action_show 
> now. The
> logic in action_show is easier to understand for me.
>

I'm in the middle, either of new/old logic looks good to me ;)
Thanks for clarifying.

--
Su
> Best Regards
> Xiao
>>
>> > +     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.
>>
>>
>> > +     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 *'
>>
>> --
>> 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);
>>