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

[Su Yue]

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

> On Mon, May 20, 2024 at 8:38 PM Su Yue <l@xxxxxxxxxxx> wrote:
> > On Thu 09 May 2024 at 09:18, Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>
> > wrote:
> >
> > > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxx>
> > > ---
> > >  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);