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Date: Tue, 14 May 2024 16:40:28 +0800
From: Xiao Ni <xni@...hat.com>
To: 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
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.
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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