Hi,
在 2025/05/26 14:52, Xiao Ni 写道:
On Sat, May 24, 2025 at 2:18 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
From: Yu Kuai <yukuai3@xxxxxxxxxx>
Currently bitmap_ops is registered while allocating mddev, this is fine
when there is only one bitmap_ops, however, after introduing a new
bitmap_ops, user space need a time window to choose which bitmap_ops to
use while creating new array.
Could you give more explanation about what the time window is? Is it
between setting llbitmap by bitmap_type and md_bitmap_create?
The window after this patch is that user can write the new sysfs after
allocating mddev, and before running the array.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/md.c | 86 +++++++++++++++++++++++++++++++------------------
1 file changed, 55 insertions(+), 31 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4eb0c6effd5b..dc4b85f30e13 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -674,39 +674,50 @@ static void no_op(struct percpu_ref *r) {}
static bool mddev_set_bitmap_ops(struct mddev *mddev)
{
+ struct bitmap_operations *old = mddev->bitmap_ops;
+ struct md_submodule_head *head;
+
+ if (mddev->bitmap_id == ID_BITMAP_NONE ||
+ (old && old->head.id == mddev->bitmap_id))
+ return true;
+
xa_lock(&md_submodule);
- mddev->bitmap_ops = xa_load(&md_submodule, mddev->bitmap_id);
+ head = xa_load(&md_submodule, mddev->bitmap_id);
xa_unlock(&md_submodule);
- if (!mddev->bitmap_ops) {
- pr_warn_once("md: can't find bitmap id %d\n", mddev->bitmap_id);
+ if (WARN_ON_ONCE(!head || head->type != MD_BITMAP)) {
+ pr_err("md: can't find bitmap id %d\n", mddev->bitmap_id);
return false;
}
+ if (old && old->group)
+ sysfs_remove_group(&mddev->kobj, old->group);
I think you're handling a competition problem here. But I don't know
how the old/old->group is already created when creating an array.
Could you explain this?
It's not possible now, this is because I think we want to be able to
switch existing array with old bitmap to new bitmap.
Thanks,
Kuai
Regards
Xiao
