md: remove old apis to suspend the array

Now that mddev_suspend() and mddev_resume() is not used anywhere, remove
them, and remove 'MD_ALLOW_SB_UPDATE' and 'MD_UPDATING_SB' as well.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-19-yukuai1@huaweicloud.com

drivers/md/md.c

@@ -418,74 +418,10 @@ static void md_submit_bio(struct bio *bio)
 	md_handle_request(mddev, bio);
 }
 
-/* mddev_suspend makes sure no new requests are submitted
- * to the device, and that any requests that have been submitted
- * are completely handled.
- * Once mddev_detach() is called and completes, the module will be
- * completely unused.
- */
-void mddev_suspend(struct mddev *mddev)
-{
-	struct md_thread *thread = rcu_dereference_protected(mddev->thread,
-			lockdep_is_held(&mddev->reconfig_mutex));
-
-	WARN_ON_ONCE(thread && current == thread->tsk);
-
-	/* can't concurrent with __mddev_suspend() and __mddev_resume() */
-	mutex_lock(&mddev->suspend_mutex);
-	if (mddev->suspended++) {
-		mutex_unlock(&mddev->suspend_mutex);
-		return;
-	}
-
-	wake_up(&mddev->sb_wait);
-	set_bit(MD_ALLOW_SB_UPDATE, &mddev->flags);
-	percpu_ref_kill(&mddev->active_io);
-
-	/*
-	 * TODO: cleanup 'pers->prepare_suspend after all callers are replaced
-	 * by __mddev_suspend().
+/*
+ * Make sure no new requests are submitted to the device, and any requests that
+ * have been submitted are completely handled.
  */
-	if (mddev->pers && mddev->pers->prepare_suspend)
-		mddev->pers->prepare_suspend(mddev);
-
-	wait_event(mddev->sb_wait, percpu_ref_is_zero(&mddev->active_io));
-	clear_bit_unlock(MD_ALLOW_SB_UPDATE, &mddev->flags);
-	wait_event(mddev->sb_wait, !test_bit(MD_UPDATING_SB, &mddev->flags));
-
-	del_timer_sync(&mddev->safemode_timer);
-	/* restrict memory reclaim I/O during raid array is suspend */
-	mddev->noio_flag = memalloc_noio_save();
-
-	mutex_unlock(&mddev->suspend_mutex);
-}
-EXPORT_SYMBOL_GPL(mddev_suspend);
-
-void mddev_resume(struct mddev *mddev)
-{
-	lockdep_assert_held(&mddev->reconfig_mutex);
-
-	/* can't concurrent with __mddev_suspend() and __mddev_resume() */
-	mutex_lock(&mddev->suspend_mutex);
-	if (--mddev->suspended) {
-		mutex_unlock(&mddev->suspend_mutex);
-		return;
-	}
-
-	/* entred the memalloc scope from mddev_suspend() */
-	memalloc_noio_restore(mddev->noio_flag);
-
-	percpu_ref_resurrect(&mddev->active_io);
-	wake_up(&mddev->sb_wait);
-
-	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-	md_wakeup_thread(mddev->thread);
-	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
-
-	mutex_unlock(&mddev->suspend_mutex);
-}
-EXPORT_SYMBOL_GPL(mddev_resume);
-
 int __mddev_suspend(struct mddev *mddev, bool interruptible)
 {
 	int err = 0;
@@ -9503,18 +9439,6 @@ static void md_start_sync(struct work_struct *ws)
  */
 void md_check_recovery(struct mddev *mddev)
 {
-	if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags) && mddev->sb_flags) {
-		/* Write superblock - thread that called mddev_suspend()
-		 * holds reconfig_mutex for us.
-		 */
-		set_bit(MD_UPDATING_SB, &mddev->flags);
-		smp_mb__after_atomic();
-		if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags))
-			md_update_sb(mddev, 0);
-		clear_bit_unlock(MD_UPDATING_SB, &mddev->flags);
-		wake_up(&mddev->sb_wait);
-	}
-
 	if (READ_ONCE(mddev->suspended))
 		return;
 

drivers/md/md.h

@@ -248,10 +248,6 @@ struct md_cluster_info;
  *			    become failed.
  * @MD_HAS_PPL:  The raid array has PPL feature set.
  * @MD_HAS_MULTIPLE_PPLS: The raid array has multiple PPLs feature set.
- * @MD_ALLOW_SB_UPDATE: md_check_recovery is allowed to update the metadata
- *			 without taking reconfig_mutex.
- * @MD_UPDATING_SB: md_check_recovery is updating the metadata without
- *		     explicitly holding reconfig_mutex.
  * @MD_NOT_READY: do_md_run() is active, so 'array_state', ust not report that
  *		   array is ready yet.
  * @MD_BROKEN: This is used to stop writes and mark array as failed.
@@ -268,8 +264,6 @@ enum mddev_flags {
 	MD_FAILFAST_SUPPORTED,
 	MD_HAS_PPL,
 	MD_HAS_MULTIPLE_PPLS,
-	MD_ALLOW_SB_UPDATE,
-	MD_UPDATING_SB,
 	MD_NOT_READY,
 	MD_BROKEN,
 	MD_DELETED,
@@ -810,8 +804,6 @@ extern int md_rdev_init(struct md_rdev *rdev);
 extern void md_rdev_clear(struct md_rdev *rdev);
 
 extern void md_handle_request(struct mddev *mddev, struct bio *bio);
-extern void mddev_suspend(struct mddev *mddev);
-extern void mddev_resume(struct mddev *mddev);
 extern int __mddev_suspend(struct mddev *mddev, bool interruptible);
 extern void __mddev_resume(struct mddev *mddev);