ANDROID: dm: dm-user: New target that proxies BIOs to userspace

dm-user is essentially FUSE for block devices: as BIOs come in through device mapper they are proxied to a userspace daemon via a control misc device. This is very much a work in progress. There's a handful of FIXMEs spread throughout the code with more details. As far as I know there is nothing broken with the current code, there's just more work to do. Test: Ran the selftests on the version of this I'm developing for Linus' tree, on both 4.19 and 5.8. Bug: 161496058 Signed-off-by: Palmer Dabbelt <[email protected]> Change-Id: If5bcd8a43c3db5b556563ba303f474dd0d2902e8
akeromi · Jan 12, 2021 · 1caf05c · 1caf05c
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diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
@@ -601,4 +601,18 @@ config DM_BOW
 
 	  If unsure, say N.
 
+config DM_USER
+	tristate "Block device in userspace"
+	depends on BLK_DEV_DM
+	default y
+	help
+	  This device-mapper target allows a userspace daemon to provide the
+	  contents of a block device.  See
+	  <file:Documentation/block/dm-user.rst> for more information.
+
+	  To compile this code as a module, choose M here: the module will be
+	  called dm-user.
+
+	  If unsure, say N.
+
 endif # MD
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
@@ -70,6 +70,7 @@ obj-$(CONFIG_DM_INTEGRITY)	+= dm-integrity.o
 obj-$(CONFIG_DM_ZONED)		+= dm-zoned.o
 obj-$(CONFIG_DM_WRITECACHE)	+= dm-writecache.o
 obj-$(CONFIG_DM_BOW)		+= dm-bow.o
+obj-$(CONFIG_DM_USER)		+= dm-user.o
 
 ifeq ($(CONFIG_DM_UEVENT),y)
 dm-mod-objs			+= dm-uevent.o