rnull: move driver to separate directory

The rust null block driver is about to gain some additional modules. Rather
than pollute the current directory, move the driver to a subdirectory.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250902-rnull-up-v6-16-v7-12-b5212cc89b98@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Andreas Hindborg

MAINTAINERS

@@ -4343,7 +4343,7 @@ W:	https://rust-for-linux.com
 B:	https://github.com/Rust-for-Linux/linux/issues
 C:	https://rust-for-linux.zulipchat.com/#narrow/stream/Block
 T:	git https://github.com/Rust-for-Linux/linux.git rust-block-next
-F:	drivers/block/rnull.rs
+F:	drivers/block/rnull/
 F:	rust/kernel/block.rs
 F:	rust/kernel/block/
 

drivers/block/Kconfig

@@ -17,6 +17,7 @@ menuconfig BLK_DEV
 if BLK_DEV
 
 source "drivers/block/null_blk/Kconfig"
+source "drivers/block/rnull/Kconfig"
 
 config BLK_DEV_FD
 	tristate "Normal floppy disk support"
@@ -311,15 +312,6 @@ config VIRTIO_BLK
 	  This is the virtual block driver for virtio.  It can be used with
           QEMU based VMMs (like KVM or Xen).  Say Y or M.
 
-config BLK_DEV_RUST_NULL
-	tristate "Rust null block driver (Experimental)"
-	depends on RUST
-	help
-	  This is the Rust implementation of the null block driver. For now it
-	  is only a minimal stub.
-
-	  If unsure, say N.
-
 config BLK_DEV_RBD
 	tristate "Rados block device (RBD)"
 	depends on INET && BLOCK

drivers/block/Makefile

@@ -9,9 +9,6 @@
 # needed for trace events
 ccflags-y				+= -I$(src)
 
-obj-$(CONFIG_BLK_DEV_RUST_NULL) += rnull_mod.o
-rnull_mod-y := rnull.o
-
 obj-$(CONFIG_MAC_FLOPPY)	+= swim3.o
 obj-$(CONFIG_BLK_DEV_SWIM)	+= swim_mod.o
 obj-$(CONFIG_BLK_DEV_FD)	+= floppy.o
@@ -38,6 +35,7 @@ obj-$(CONFIG_ZRAM) += zram/
 obj-$(CONFIG_BLK_DEV_RNBD)	+= rnbd/
 
 obj-$(CONFIG_BLK_DEV_NULL_BLK)	+= null_blk/
+obj-$(CONFIG_BLK_DEV_RUST_NULL) += rnull/
 
 obj-$(CONFIG_BLK_DEV_UBLK)			+= ublk_drv.o
 obj-$(CONFIG_BLK_DEV_ZONED_LOOP) += zloop.o

drivers/block/rnull/Kconfig

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Rust null block device driver configuration
+
+config BLK_DEV_RUST_NULL
+	tristate "Rust null block driver (Experimental)"
+	depends on RUST
+	help
+	  This is the Rust implementation of the null block driver. Like
+	  the C version, the driver allows the user to create virutal block
+	  devices that can be configured via various configuration options.
+
+	  If unsure, say N.

drivers/block/rnull/Makefile

@@ -0,0 +1,3 @@
+
+obj-$(CONFIG_BLK_DEV_RUST_NULL) += rnull_mod.o
+rnull_mod-y := rnull.o