On Tue, Aug 22, 2023 at 8:04 PM Yu Kuai [off-list ref] wrote:

quoted

Hi,

在 2023/08/22 10:17, Yu Kuai 写道:

quoted

Hi,

在 2023/08/22 7:22, Song Liu 写道:

quoted

On Sun, Aug 20, 2023 at 2:13 AM Yu Kuai [off-list ref] wrote:

quoted

From: Yu Kuai <redacted>

There are no functional changes, just to make the code simpler and
prepare to delay remove_and_add_spares() to md_start_sync().

Signed-off-by: Yu Kuai <redacted>
---
   drivers/md/md.c | 28 ++++++++++++++++------------
   1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 11d27c934fdd..cdc361c521d4 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -9177,6 +9177,20 @@ static bool rdev_is_spare(struct md_rdev *rdev)
                 !test_bit(Faulty, &rdev->flags);
   }

+static bool rdev_addable(struct md_rdev *rdev)
+{
+       if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
+           test_bit(Faulty, &rdev->flags))
+               return false;
+
+       if (!test_bit(Journal, &rdev->flags) &&

!md_is_rdwr(rdev->mddev) &&

Instead of straightforward refactoring, I hope we can make these rdev_*
helpers more meaningful, and hopefullly reusable. For example, let's
define
the meaning of "addable", and write the function to match that
meaning. In
this case, I think we shouldn't check md_is_rdwr() inside rdev_addable().

Does this make sense?

Yes, this make sense, rdev can be added to read-only array.

There are total three callers of pers->hot_add_sisk, I'll try to find if
they have common conditions.

Unfortunately, the conditions is quite different, and It's difficult to
factor out a common helper for them to use.

In this case, !md_is_rdwr() is one of the four conditions, which means
if the array is read-only, there is a special case that rdev can't be
added to the configuration. Perhaps it's okay to keep this?

My main concern is that rdev_addable() is not making the code easier to
understand. We have a few different cases at this point:

1. rdev is not suitable for add (Faulty, raid_disk>=0, Candidate);
2. rdev is Journal;
3. Re-add rdev to RO array;
4. Non-re-add rdev to RO array;
5. Other cases.

Current rdev_addable() handles more or less all of this, which is
confusing. Maybe we can do something along similar to the
following (not tested). Does this look more clear?

Thanks,
Song

diff --git i/drivers/md/md.c w/drivers/md/md.c
index 78be7811a89f..8cb855d03e0a 100644
--- i/drivers/md/md.c
+++ w/drivers/md/md.c

@@ -9117,6 +9117,20 @@ void md_do_sync(struct md_thread *thread)
  }
  EXPORT_SYMBOL_GPL(md_do_sync);

+static bool rdev_addable(struct md_rdev *rdev)
+{
+       if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
+           test_bit(Faulty, &rdev->flags))
+               return false;
+       return true;
+}
+
+static bool rdev_is_readd(struct md_rdev *rdev)
+{
+       return rdev->saved_raid_disk >= 0 ||
+               !test_bit(Bitmap_sync, &rdev->flags);

+}
+
  static int remove_and_add_spares(struct mddev *mddev,
                                  struct md_rdev *this)
  {

@@ -9176,25 +9190,24 @@ static int remove_and_add_spares(struct mddev *mddev,
         rdev_for_each(rdev, mddev) {
                 if (this && this != rdev)
                         continue;
-               if (test_bit(Candidate, &rdev->flags))
-                       continue;
                 if (rdev->raid_disk >= 0 &&
                     !test_bit(In_sync, &rdev->flags) &&
                     !test_bit(Journal, &rdev->flags) &&
                     !test_bit(Faulty, &rdev->flags))
                         spares++;
-               if (rdev->raid_disk >= 0)
+
+               if (!rdev_addable(rdev))
                         continue;
-               if (test_bit(Faulty, &rdev->flags))
+
+               if (test_bit(Journal, &rdev->flags))
+                       goto hot_add_disk;
+