md: switch personalities to use md_submodule_head

Remove the global list 'pers_list', and switch to use md_submodule_head,
which is managed by xarry. Prepare to unify registration and unregistration
for all sub modules.

Link: https://lore.kernel.org/linux-raid/20250215092225.2427977-5-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>

drivers/md/md-linear.c

@@ -5,7 +5,6 @@
  */
 
 #include <linux/blkdev.h>
-#include <linux/raid/md_u.h>
 #include <linux/seq_file.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -320,9 +319,13 @@ static void linear_quiesce(struct mddev *mddev, int state)
 }
 
 static struct md_personality linear_personality = {
-	.name		= "linear",
-	.level		= LEVEL_LINEAR,
-	.owner		= THIS_MODULE,
+	.head = {
+		.type	= MD_PERSONALITY,
+		.id	= ID_LINEAR,
+		.name	= "linear",
+		.owner	= THIS_MODULE,
+	},
+
 	.make_request	= linear_make_request,
 	.run		= linear_run,
 	.free		= linear_free,
@@ -335,12 +338,12 @@ static struct md_personality linear_personality = {
 
 static int __init linear_init(void)
 {
-	return register_md_personality(&linear_personality);
+	return register_md_submodule(&linear_personality.head);
 }
 
 static void linear_exit(void)
 {
-	unregister_md_personality(&linear_personality);
+	unregister_md_submodule(&linear_personality.head);
 }
 
 module_init(linear_init);

drivers/md/md.c

@@ -81,8 +81,6 @@ static const char *action_name[NR_SYNC_ACTIONS] = {
 
 static DEFINE_XARRAY(md_submodule);
 
-/* pers_list is a list of registered personalities protected by pers_lock. */
-static LIST_HEAD(pers_list);
 static DEFINE_SPINLOCK(pers_lock);
 
 static const struct kobj_type md_ktype;
@@ -893,18 +891,21 @@ EXPORT_SYMBOL_GPL(md_find_rdev_rcu);
 static struct md_personality *get_pers(int level, char *clevel)
 {
 	struct md_personality *ret = NULL;
-	struct md_personality *pers;
+	struct md_submodule_head *head;
+	unsigned long i;
 
-	spin_lock(&pers_lock);
-	list_for_each_entry(pers, &pers_list, list) {
-		if ((level != LEVEL_NONE && pers->level == level) ||
-		    !strcmp(pers->name, clevel)) {
-			if (try_module_get(pers->owner))
-				ret = pers;
+	xa_lock(&md_submodule);
+	xa_for_each(&md_submodule, i, head) {
+		if (head->type != MD_PERSONALITY)
+			continue;
+		if ((level != LEVEL_NONE && head->id == level) ||
+		    !strcmp(head->name, clevel)) {
+			if (try_module_get(head->owner))
+				ret = (void *)head;
 			break;
 		}
 	}
-	spin_unlock(&pers_lock);
+	xa_unlock(&md_submodule);
 
 	if (!ret) {
 		if (level != LEVEL_NONE)
@@ -920,7 +921,7 @@ static struct md_personality *get_pers(int level, char *clevel)
 
 static void put_pers(struct md_personality *pers)
 {
-	module_put(pers->owner);
+	module_put(pers->head.owner);
 }
 
 /* return the offset of the super block in 512byte sectors */
@@ -1203,7 +1204,7 @@ int md_check_no_bitmap(struct mddev *mddev)
 	if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
 		return 0;
 	pr_warn("%s: bitmaps are not supported for %s\n",
-		mdname(mddev), mddev->pers->name);
+		mdname(mddev), mddev->pers->head.name);
 	return 1;
 }
 EXPORT_SYMBOL(md_check_no_bitmap);
@@ -3883,7 +3884,7 @@ level_show(struct mddev *mddev, char *page)
 	spin_lock(&mddev->lock);
 	p = mddev->pers;
 	if (p)
-		ret = sprintf(page, "%s\n", p->name);
+		ret = sprintf(page, "%s\n", p->head.name);
 	else if (mddev->clevel[0])
 		ret = sprintf(page, "%s\n", mddev->clevel);
 	else if (mddev->level != LEVEL_NONE)
@@ -3940,7 +3941,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
 	rv = -EINVAL;
 	if (!mddev->pers->quiesce) {
 		pr_warn("md: %s: %s does not support online personality change\n",
-			mdname(mddev), mddev->pers->name);
+			mdname(mddev), mddev->pers->head.name);
 		goto out_unlock;
 	}
 
@@ -4003,7 +4004,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
 	oldpriv = mddev->private;
 	mddev->pers = pers;
 	mddev->private = priv;
-	strscpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
+	strscpy(mddev->clevel, pers->head.name, sizeof(mddev->clevel));
 	mddev->level = mddev->new_level;
 	mddev->layout = mddev->new_layout;
 	mddev->chunk_sectors = mddev->new_chunk_sectors;
@@ -5603,7 +5604,7 @@ __ATTR(fail_last_dev, S_IRUGO | S_IWUSR, fail_last_dev_show,
 
 static ssize_t serialize_policy_show(struct mddev *mddev, char *page)
 {
-	if (mddev->pers == NULL || (mddev->pers->level != 1))
+	if (mddev->pers == NULL || (mddev->pers->head.id != ID_RAID1))
 		return sprintf(page, "n/a\n");
 	else
 		return sprintf(page, "%d\n", mddev->serialize_policy);
@@ -5629,7 +5630,7 @@ serialize_policy_store(struct mddev *mddev, const char *buf, size_t len)
 	err = mddev_suspend_and_lock(mddev);
 	if (err)
 		return err;
-	if (mddev->pers == NULL || (mddev->pers->level != 1)) {
+	if (mddev->pers == NULL || (mddev->pers->head.id != ID_RAID1)) {
 		pr_err("md: serialize_policy is only effective for raid1\n");
 		err = -EINVAL;
 		goto unlock;
@@ -6120,11 +6121,11 @@ int md_run(struct mddev *mddev)
 		err = -EINVAL;
 		goto abort;
 	}
-	if (mddev->level != pers->level) {
-		mddev->level = pers->level;
-		mddev->new_level = pers->level;
+	if (mddev->level != pers->head.id) {
+		mddev->level = pers->head.id;
+		mddev->new_level = pers->head.id;
 	}
-	strscpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
+	strscpy(mddev->clevel, pers->head.name, sizeof(mddev->clevel));
 
 	if (mddev->reshape_position != MaxSector &&
 	    pers->start_reshape == NULL) {
@@ -8134,7 +8135,8 @@ void md_error(struct mddev *mddev, struct md_rdev *rdev)
 		return;
 	mddev->pers->error_handler(mddev, rdev);
 
-	if (mddev->pers->level == 0 || mddev->pers->level == LEVEL_LINEAR)
+	if (mddev->pers->head.id == ID_RAID0 ||
+	    mddev->pers->head.id == ID_LINEAR)
 		return;
 
 	if (mddev->degraded && !test_bit(MD_BROKEN, &mddev->flags))
@@ -8172,14 +8174,17 @@ static void status_unused(struct seq_file *seq)
 
 static void status_personalities(struct seq_file *seq)
 {
-	struct md_personality *pers;
+	struct md_submodule_head *head;
+	unsigned long i;
 
 	seq_puts(seq, "Personalities : ");
-	spin_lock(&pers_lock);
-	list_for_each_entry(pers, &pers_list, list)
-		seq_printf(seq, "[%s] ", pers->name);
 
-	spin_unlock(&pers_lock);
+	xa_lock(&md_submodule);
+	xa_for_each(&md_submodule, i, head)
+		if (head->type == MD_PERSONALITY)
+			seq_printf(seq, "[%s] ", head->name);
+	xa_unlock(&md_submodule);
+
 	seq_puts(seq, "\n");
 }
 
@@ -8402,7 +8407,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
 				seq_printf(seq, " (read-only)");
 			if (mddev->ro == MD_AUTO_READ)
 				seq_printf(seq, " (auto-read-only)");
-			seq_printf(seq, " %s", mddev->pers->name);
+			seq_printf(seq, " %s", mddev->pers->head.name);
 		} else {
 			seq_printf(seq, "inactive");
 		}
@@ -8536,27 +8541,6 @@ void unregister_md_submodule(struct md_submodule_head *msh)
 }
 EXPORT_SYMBOL_GPL(unregister_md_submodule);
 
-int register_md_personality(struct md_personality *p)
-{
-	pr_debug("md: %s personality registered for level %d\n",
-		 p->name, p->level);
-	spin_lock(&pers_lock);
-	list_add_tail(&p->list, &pers_list);
-	spin_unlock(&pers_lock);
-	return 0;
-}
-EXPORT_SYMBOL(register_md_personality);
-
-int unregister_md_personality(struct md_personality *p)
-{
-	pr_debug("md: %s personality unregistered\n", p->name);
-	spin_lock(&pers_lock);
-	list_del_init(&p->list);
-	spin_unlock(&pers_lock);
-	return 0;
-}
-EXPORT_SYMBOL(unregister_md_personality);
-
 int register_md_cluster_operations(const struct md_cluster_operations *ops,
 				   struct module *module)
 {

drivers/md/md.h

@@ -726,10 +726,7 @@ static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
 struct md_personality
 {
 	struct md_submodule_head head;
-	char *name;
-	int level;
-	struct list_head list;
-	struct module *owner;
+
 	bool __must_check (*make_request)(struct mddev *mddev, struct bio *bio);
 	/*
 	 * start up works that do NOT require md_thread. tasks that
@@ -873,8 +870,6 @@ static inline void safe_put_page(struct page *p)
 int register_md_submodule(struct md_submodule_head *msh);
 void unregister_md_submodule(struct md_submodule_head *msh);
 
-extern int register_md_personality(struct md_personality *p);
-extern int unregister_md_personality(struct md_personality *p);
 extern struct md_thread *md_register_thread(
 	void (*run)(struct md_thread *thread),
 	struct mddev *mddev,

drivers/md/raid0.c

@@ -811,9 +811,13 @@ static void raid0_quiesce(struct mddev *mddev, int quiesce)
 
 static struct md_personality raid0_personality=
 {
-	.name		= "raid0",
-	.level		= 0,
-	.owner		= THIS_MODULE,
+	.head = {
+		.type	= MD_PERSONALITY,
+		.id	= ID_RAID0,
+		.name	= "raid0",
+		.owner	= THIS_MODULE,
+	},
+
 	.make_request	= raid0_make_request,
 	.run		= raid0_run,
 	.free		= raid0_free,
@@ -824,14 +828,14 @@ static struct md_personality raid0_personality=
 	.error_handler	= raid0_error,
 };
 
-static int __init raid0_init (void)
+static int __init raid0_init(void)
 {
-	return register_md_personality (&raid0_personality);
+	return register_md_submodule(&raid0_personality.head);
 }
 
-static void raid0_exit (void)
+static void __exit raid0_exit(void)
 {
-	unregister_md_personality (&raid0_personality);
+	unregister_md_submodule(&raid0_personality.head);
 }
 
 module_init(raid0_init);

drivers/md/raid1.c

@@ -3500,9 +3500,13 @@ static void *raid1_takeover(struct mddev *mddev)
 
 static struct md_personality raid1_personality =
 {
-	.name		= "raid1",
-	.level		= 1,
-	.owner		= THIS_MODULE,
+	.head = {
+		.type	= MD_PERSONALITY,
+		.id	= ID_RAID1,
+		.name	= "raid1",
+		.owner	= THIS_MODULE,
+	},
+
 	.make_request	= raid1_make_request,
 	.run		= raid1_run,
 	.free		= raid1_free,
@@ -3519,18 +3523,18 @@ static struct md_personality raid1_personality =
 	.takeover	= raid1_takeover,
 };
 
-static int __init raid_init(void)
+static int __init raid1_init(void)
 {
-	return register_md_personality(&raid1_personality);
+	return register_md_submodule(&raid1_personality.head);
 }
 
-static void raid_exit(void)
+static void __exit raid1_exit(void)
 {
-	unregister_md_personality(&raid1_personality);
+	unregister_md_submodule(&raid1_personality.head);
 }
 
-module_init(raid_init);
-module_exit(raid_exit);
+module_init(raid1_init);
+module_exit(raid1_exit);
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
 MODULE_ALIAS("md-personality-3"); /* RAID1 */

drivers/md/raid10.c

@@ -5126,9 +5126,13 @@ static void raid10_finish_reshape(struct mddev *mddev)
 
 static struct md_personality raid10_personality =
 {
-	.name		= "raid10",
-	.level		= 10,
-	.owner		= THIS_MODULE,
+	.head = {
+		.type	= MD_PERSONALITY,
+		.id	= ID_RAID10,
+		.name	= "raid10",
+		.owner	= THIS_MODULE,
+	},
+
 	.make_request	= raid10_make_request,
 	.run		= raid10_run,
 	.free		= raid10_free,
@@ -5148,18 +5152,18 @@ static struct md_personality raid10_personality =
 	.update_reshape_pos = raid10_update_reshape_pos,
 };
 
-static int __init raid_init(void)
+static int __init raid10_init(void)
 {
-	return register_md_personality(&raid10_personality);
+	return register_md_submodule(&raid10_personality.head);
 }
 
-static void raid_exit(void)
+static void __exit raid10_exit(void)
 {
-	unregister_md_personality(&raid10_personality);
+	unregister_md_submodule(&raid10_personality.head);
 }
 
-module_init(raid_init);
-module_exit(raid_exit);
+module_init(raid10_init);
+module_exit(raid10_exit);
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
 MODULE_ALIAS("md-personality-9"); /* RAID10 */