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 [off-list ref] wrote:

quoted

Hi,

在 2024/05/14 14:52, Xiao Ni 写道:

quoted

On Mon, May 13, 2024 at 5:31 PM Yu Kuai [off-list ref] wrote:

quoted

From: Yu Kuai <redacted>

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 <redacted>
---
   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

quoted

+
+       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

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Thanks,
Kuai

quoted

Regards
Xiao

quoted

+}
+
+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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