diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 40c53632512b764eee3b720a973b55930096e06c..9617688b58b3228873c9f6710f387bcc6eb71520 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -16,13 +16,7 @@ menuconfig BLK_DEV
 
 if BLK_DEV
 
-config BLK_DEV_NULL_BLK
-	tristate "Null test block driver"
-	select CONFIGFS_FS
-
-config BLK_DEV_NULL_BLK_FAULT_INJECTION
-	bool "Support fault injection for Null test block driver"
-	depends on BLK_DEV_NULL_BLK && FAULT_INJECTION
+source "drivers/block/null_blk/Kconfig"
 
 config BLK_DEV_FD
 	tristate "Normal floppy disk support"
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index e1f63117ee94f1aea008208bce017570151294b0..a3170859e01d48440abda99a8e09da221bd5b76d 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -41,12 +41,7 @@ obj-$(CONFIG_BLK_DEV_RSXX) += rsxx/
 obj-$(CONFIG_ZRAM) += zram/
 obj-$(CONFIG_BLK_DEV_RNBD)	+= rnbd/
 
-obj-$(CONFIG_BLK_DEV_NULL_BLK)	+= null_blk.o
-null_blk-objs	:= null_blk_main.o
-ifeq ($(CONFIG_BLK_DEV_ZONED), y)
-null_blk-$(CONFIG_TRACING) += null_blk_trace.o
-endif
-null_blk-$(CONFIG_BLK_DEV_ZONED) += null_blk_zoned.o
+obj-$(CONFIG_BLK_DEV_NULL_BLK)	+= null_blk/
 
 skd-y		:= skd_main.o
 swim_mod-y	:= swim.o swim_asm.o
diff --git a/drivers/block/null_blk/Kconfig b/drivers/block/null_blk/Kconfig
new file mode 100644
index 0000000000000000000000000000000000000000..6bf1f8ca20a24b054572b9cb56bf9695daff4b65
--- /dev/null
+++ b/drivers/block/null_blk/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Null block device driver configuration
+#
+
+config BLK_DEV_NULL_BLK
+	tristate "Null test block driver"
+	select CONFIGFS_FS
+
+config BLK_DEV_NULL_BLK_FAULT_INJECTION
+	bool "Support fault injection for Null test block driver"
+	depends on BLK_DEV_NULL_BLK && FAULT_INJECTION
diff --git a/drivers/block/null_blk/Makefile b/drivers/block/null_blk/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..84c36e512ab89f659638c219b4262a2749c974ea
--- /dev/null
+++ b/drivers/block/null_blk/Makefile
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+
+# needed for trace events
+ccflags-y			+= -I$(src)
+
+obj-$(CONFIG_BLK_DEV_NULL_BLK)	+= null_blk.o
+null_blk-objs			:= main.o
+ifeq ($(CONFIG_BLK_DEV_ZONED), y)
+null_blk-$(CONFIG_TRACING) 	+= trace.o
+endif
+null_blk-$(CONFIG_BLK_DEV_ZONED) += zoned.o
diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk/main.c
similarity index 99%
rename from drivers/block/null_blk_main.c
rename to drivers/block/null_blk/main.c
index c6ba8f9f3f3116dc6082fe31de4f46b0f2d0879a..209b95f8883995c74d05fb1be3165b91b400c2ef 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk/main.c
@@ -323,11 +323,9 @@ CONFIGFS_ATTR(nullb_device_, NAME);
 static int nullb_apply_submit_queues(struct nullb_device *dev,
 				     unsigned int submit_queues)
 {
-	struct nullb *nullb = dev->nullb;
+	struct nullb *nullb;
 	struct blk_mq_tag_set *set;
-
-	if (!nullb)
-		return 0;
+	int ret = 0;
 
 	/*
 	 * Make sure that null_init_hctx() does not access nullb->queues[] past
@@ -335,9 +333,20 @@ static int nullb_apply_submit_queues(struct nullb_device *dev,
 	 */
 	if (submit_queues > nr_cpu_ids)
 		return -EINVAL;
+
+	mutex_lock(&lock);
+
+	nullb = dev->nullb;
+	if (!nullb)
+		goto out;
+
 	set = nullb->tag_set;
 	blk_mq_update_nr_hw_queues(set, submit_queues);
-	return set->nr_hw_queues == submit_queues ? 0 : -ENOMEM;
+	ret = set->nr_hw_queues == submit_queues ? 0 : -ENOMEM;
+
+out:
+	mutex_unlock(&lock);
+	return ret;
 }
 
 NULLB_DEVICE_ATTR(size, ulong, NULL);
@@ -378,27 +387,31 @@ static ssize_t nullb_device_power_store(struct config_item *item,
 	if (ret < 0)
 		return ret;
 
+	ret = count;
+	mutex_lock(&lock);
 	if (!dev->power && newp) {
 		if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))
-			return count;
+			goto out;
+
 		if (null_add_dev(dev)) {
 			clear_bit(NULLB_DEV_FL_UP, &dev->flags);
-			return -ENOMEM;
+			ret = -ENOMEM;
+			goto out;
 		}
 
 		set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 		dev->power = newp;
 	} else if (dev->power && !newp) {
 		if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
-			mutex_lock(&lock);
 			dev->power = newp;
 			null_del_dev(dev->nullb);
-			mutex_unlock(&lock);
 		}
 		clear_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 	}
 
-	return count;
+out:
+	mutex_unlock(&lock);
+	return ret;
 }
 
 CONFIGFS_ATTR(nullb_device_, power);
@@ -1875,15 +1888,11 @@ static int null_add_dev(struct nullb_device *dev)
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
 
-	mutex_lock(&lock);
 	rv = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
-	if (rv < 0) {
-		mutex_unlock(&lock);
+	if (rv < 0)
 		goto out_cleanup_zone;
-	}
 	nullb->index = rv;
 	dev->index = rv;
-	mutex_unlock(&lock);
 
 	blk_queue_logical_block_size(nullb->q, dev->blocksize);
 	blk_queue_physical_block_size(nullb->q, dev->blocksize);
@@ -1896,9 +1905,7 @@ static int null_add_dev(struct nullb_device *dev)
 	if (rv)
 		goto out_ida_free;
 
-	mutex_lock(&lock);
 	list_add_tail(&nullb->list, &nullb_list);
-	mutex_unlock(&lock);
 
 	return 0;
 
@@ -1980,7 +1987,9 @@ static int __init null_init(void)
 			ret = -ENOMEM;
 			goto err_dev;
 		}
+		mutex_lock(&lock);
 		ret = null_add_dev(dev);
+		mutex_unlock(&lock);
 		if (ret) {
 			null_free_dev(dev);
 			goto err_dev;
diff --git a/drivers/block/null_blk.h b/drivers/block/null_blk/null_blk.h
similarity index 100%
rename from drivers/block/null_blk.h
rename to drivers/block/null_blk/null_blk.h
diff --git a/drivers/block/null_blk_trace.c b/drivers/block/null_blk/trace.c
similarity index 93%
rename from drivers/block/null_blk_trace.c
rename to drivers/block/null_blk/trace.c
index f246e7bff69820385edc1832f55e26842eeca023..3711cba160715afc1734f43fd040e4ff7885ea42 100644
--- a/drivers/block/null_blk_trace.c
+++ b/drivers/block/null_blk/trace.c
@@ -4,7 +4,7 @@
  *
  * Copyright (C) 2020 Western Digital Corporation or its affiliates.
  */
-#include "null_blk_trace.h"
+#include "trace.h"
 
 /*
  * Helper to use for all null_blk traces to extract disk name.
diff --git a/drivers/block/null_blk_trace.h b/drivers/block/null_blk/trace.h
similarity index 97%
rename from drivers/block/null_blk_trace.h
rename to drivers/block/null_blk/trace.h
index 4f83032eb54418e066465b88154078003cfc4d8a..ce3b430e88c57f28223dafea7cac48f9b92c0989 100644
--- a/drivers/block/null_blk_trace.h
+++ b/drivers/block/null_blk/trace.h
@@ -73,7 +73,7 @@ TRACE_EVENT(nullb_report_zones,
 #undef TRACE_INCLUDE_PATH
 #define TRACE_INCLUDE_PATH .
 #undef TRACE_INCLUDE_FILE
-#define TRACE_INCLUDE_FILE null_blk_trace
+#define TRACE_INCLUDE_FILE trace
 
 /* This part must be outside protection */
 #include <trace/define_trace.h>
diff --git a/drivers/block/null_blk_zoned.c b/drivers/block/null_blk/zoned.c
similarity index 99%
rename from drivers/block/null_blk_zoned.c
rename to drivers/block/null_blk/zoned.c
index f5df82c26c16f24ca4ecbee2837e252e01b01d09..41220ce59659b7c151e85827413fddb1f6c862af 100644
--- a/drivers/block/null_blk_zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -4,7 +4,7 @@
 #include "null_blk.h"
 
 #define CREATE_TRACE_POINTS
-#include "null_blk_trace.h"
+#include "trace.h"
 
 #define MB_TO_SECTS(mb) (((sector_t)mb * SZ_1M) >> SECTOR_SHIFT)