[PATCH v7 md-6.18 04/11] md: add a new mddev field 'bitmap_id'

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Prepare to store the bitmap id selected by user, also refactor
mddev_set_bitmap_ops a bit in case the value is invalid.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Reviewed-by: Li Nan <linan122@xxxxxxxxxx>
Reviewed-by: Xiao Ni <xni@xxxxxxxxxx>
---
 drivers/md/md.c | 37 +++++++++++++++++++++++++++++++------
 drivers/md/md.h |  2 ++
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2e088196d42c..82c84bdabe79 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -676,13 +676,33 @@ static void active_io_release(struct percpu_ref *ref)
 
 static void no_op(struct percpu_ref *r) {}
 
-static void mddev_set_bitmap_ops(struct mddev *mddev, enum md_submodule_id id)
+static bool mddev_set_bitmap_ops(struct mddev *mddev)
 {
+	struct md_submodule_head *head;
+
+	if (mddev->bitmap_id == ID_BITMAP_NONE)
+		return true;
+
 	xa_lock(&md_submodule);
-	mddev->bitmap_ops = xa_load(&md_submodule, id);
+	head = xa_load(&md_submodule, mddev->bitmap_id);
+
+	if (!head) {
+		pr_warn("md: can't find bitmap id %d\n", mddev->bitmap_id);
+		goto err;
+	}
+
+	if (head->type != MD_BITMAP) {
+		pr_warn("md: invalid bitmap id %d\n", mddev->bitmap_id);
+		goto err;
+	}
+
+	mddev->bitmap_ops = (void *)head;
 	xa_unlock(&md_submodule);
-	if (!mddev->bitmap_ops)
-		pr_warn_once("md: can't find bitmap id %d\n", id);
+	return true;
+
+err:
+	xa_unlock(&md_submodule);
+	return false;
 }
 
 static void mddev_clear_bitmap_ops(struct mddev *mddev)
@@ -692,8 +712,13 @@ static void mddev_clear_bitmap_ops(struct mddev *mddev)
 
 int mddev_init(struct mddev *mddev)
 {
-	/* TODO: support more versions */
-	mddev_set_bitmap_ops(mddev, ID_BITMAP);
+	if (!IS_ENABLED(CONFIG_MD_BITMAP)) {
+		mddev->bitmap_id = ID_BITMAP_NONE;
+	} else {
+		mddev->bitmap_id = ID_BITMAP;
+		if (!mddev_set_bitmap_ops(mddev))
+			return -EINVAL;
+	}
 
 	if (percpu_ref_init(&mddev->active_io, active_io_release,
 			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 1b767b5320cf..4fa5a3e68a0c 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -40,6 +40,7 @@ enum md_submodule_id {
 	ID_CLUSTER,
 	ID_BITMAP,
 	ID_LLBITMAP,	/* TODO */
+	ID_BITMAP_NONE,
 };
 
 struct md_submodule_head {
@@ -565,6 +566,7 @@ struct mddev {
 	struct percpu_ref		writes_pending;
 	int				sync_checkers;	/* # of threads checking writes_pending */
 
+	enum md_submodule_id		bitmap_id;
 	void				*bitmap; /* the bitmap for the device */
 	struct bitmap_operations	*bitmap_ops;
 	struct {
-- 
2.39.2