lwext4_fs: add Ext2/3/4 fs server using lwext4

Fixes #124.

run/lwext4_fs.run

@@ -0,0 +1,109 @@
+assert_spec linux
+
+#
+# Check used commands
+#
+set mke4fs [installed_command mkfs.ext4]
+set dd     [installed_command dd]
+
+#
+# Build
+#
+set build_components {
+	core init
+	drivers/timer
+	server/lwext4_fs
+	server/lx_block
+	server/report_rom
+	test/libc_vfs
+}
+
+build $build_components
+
+#
+# Build EXT2-file-system image
+#
+set image_size 262144
+catch { exec $dd if=/dev/zero of=bin/ext4.raw bs=1M seek=$image_size count=0 }
+catch { exec $mke4fs -F bin/ext4.raw }
+
+create_boot_directory
+
+#
+# Generate config
+#
+append config {
+<config>
+	<parent-provides>
+		<service name="ROM"/>
+		<service name="IRQ"/>
+		<service name="IO_MEM"/>
+		<service name="IO_PORT"/>
+		<service name="PD"/>
+		<service name="RM"/>
+		<service name="CPU"/>
+		<service name="LOG"/>
+	</parent-provides>
+	<default-route>
+		<any-service> <parent/> <any-child/> </any-service>
+	</default-route>
+	<default caps="100"/>
+
+	<start name="timer">
+		<resource name="RAM" quantum="1M"/>
+		<provides><service name="Timer"/></provides>
+	</start>
+
+	<start name="report_rom">
+		<resource name="RAM" quantum="1M"/>
+		<provides> <service name="Report"/> <service name="ROM"/> </provides>
+		<config verbose="yes"/>
+	</start>
+
+	<start name="lx_block" ld="no">
+		<resource name="RAM" quantum="1G"/>
+		<provides><service name="Block"/></provides>
+		<config file="ext4.raw" block_size="512" writeable="yes"/>
+	</start>
+
+	<start name="lwext4_fs" caps="100">
+		<resource name="RAM" quantum="4M" />
+		<provides><service name="File_system"/></provides>
+		<config cache_write_back="yes">
+			<report stats="yes"/>
+			<policy label_prefix="test-libc_vfs" root="/" writeable="yes"/>
+		</config>
+	</start>
+
+	<start name="test-libc_vfs">
+		<resource name="RAM" quantum="4M"/>
+		<config>
+			<large seek="yes"/>
+			<vfs>
+				<dir name="dev"> <log/> </dir>
+				<fs/>
+			</vfs>
+			<libc stdout="/dev/log" stderr="/dev/log"/>
+		</config>
+	</start>
+</config>}
+
+install_config $config
+
+#
+# Boot modules
+#
+
+# generic modules
+set boot_modules {
+	core ld.lib.so init timer report_rom lx_block
+	lwext4_fs ext4.raw libc.lib.so test-libc_vfs vfs.lib.so
+}
+
+build_boot_image $boot_modules
+
+append qemu_args "  -nographic"
+
+run_genode_until {.*child "test-libc_vfs" exited with exit value 0.*} 600
+
+#exec rm -f bin/ext4.raw