md: do not require mddev_lock() for all options in array_state_store()

We don't need to lock device to reject not supported request
in array_state_store(). No functional changes intended.

There are differences between ioctl and sysfs handling during stopping.
With this change, it will be easier to add additional steps which needs
to be completed before mddev_lock() is taken.

Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230928125517.12356-1-mariusz.tkaczyk@linux.intel.com

Author: mtkaczyk

drivers/md/md.c

@@ -4415,6 +4415,18 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 	int err = 0;
 	enum array_state st = match_word(buf, array_states);
 
+	/* No lock dependent actions */
+	switch (st) {
+	case suspended:		/* not supported yet */
+	case write_pending:	/* cannot be set */
+	case active_idle:	/* cannot be set */
+	case broken:		/* cannot be set */
+	case bad_word:
+		return -EINVAL;
+	default:
+		break;
+	}
+
 	if (mddev->pers && (st == active || st == clean) &&
 	    mddev->ro != MD_RDONLY) {
 		/* don't take reconfig_mutex when toggling between
@@ -4439,23 +4451,16 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 	err = mddev_lock(mddev);
 	if (err)
 		return err;
-	err = -EINVAL;
-	switch(st) {
-	case bad_word:
-		break;
-	case clear:
-		/* stopping an active array */
-		err = do_md_stop(mddev, 0, NULL);
-		break;
+
+	switch (st) {
 	case inactive:
-		/* stopping an active array */
+		/* stop an active array, return 0 otherwise */
 		if (mddev->pers)
 			err = do_md_stop(mddev, 2, NULL);
-		else
-			err = 0; /* already inactive */
 		break;
-	case suspended:
-		break; /* not supported yet */
+	case clear:
+		err = do_md_stop(mddev, 0, NULL);
+		break;
 	case readonly:
 		if (mddev->pers)
 			err = md_set_readonly(mddev, NULL);
@@ -4506,10 +4511,8 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 			err = do_md_run(mddev);
 		}
 		break;
-	case write_pending:
-	case active_idle:
-	case broken:
-		/* these cannot be set */
+	default:
+		err = -EINVAL;
 		break;
 	}