NOMMU: Fix the RomFS Kconfig to ensure at least one backing store is selected

Fix the configuration of the RomFS to make sure that at least one 
backing store method is always selected.  This is done by rendering it 
down to a choice item that selects between Block, MTD and both.

This also works correctly in the case that CONFIG_MTD=m: MTD cannot be 
selected as a backing store unless CONFIG_ROMFS_FS is also 'm'.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 28 insertions, 6 deletions

diff --git a/fs/romfs/Kconfig b/fs/romfs/Kconfig
index 802c742f002c..ce2d6bcc6266 100644
--- a/fs/romfs/Kconfig
+++ b/fs/romfs/Kconfig
@@ -1,6 +1,6 @@
 config ROMFS_FS
         tristate "ROM file system support"
-        depends on BLOCK
+        depends on BLOCK || MTD
         ---help---
           This is a very small read-only file system mainly intended for
           initial ram disks of installation disks, but it could be used for
@@ -15,9 +15,19 @@ config ROMFS_FS
           If you don't know whether you need it, then you don't need it:
           answer N.
 
-config ROMFS_ON_BLOCK
-        bool "Block device-backed ROM file system support" if (ROMFS_ON_MTD && EMBEDDED)
-        depends on ROMFS_FS && BLOCK
+#
+# Select the backing stores to be supported
+#
+choice
+        prompt "RomFS backing stores"
+        depends on ROMFS_FS
+        default ROMFS_BACKED_BY_BLOCK
+        help
+          Select the backing stores to be supported.
+
+config ROMFS_BACKED_BY_BLOCK
+        bool "Block device-backed ROM file system support"
+        depends on BLOCK
         help
           This permits ROMFS to use block devices buffered through the page
           cache as the medium from which to retrieve data.  It does not allow
@@ -25,9 +35,8 @@ config ROMFS_ON_BLOCK
 
           If unsure, answer Y.
 
-config ROMFS_ON_MTD
+config ROMFS_BACKED_BY_MTD
         bool "MTD-backed ROM file system support"
-        depends on ROMFS_FS
         depends on MTD=y || (ROMFS_FS=m && MTD)
         help
           This permits ROMFS to use MTD based devices directly, without the
@@ -38,3 +47,16 @@ config ROMFS_ON_MTD
 
           If unsure, answer Y.
 
+config ROMFS_BACKED_BY_BOTH
+        bool "Both the above"
+        depends on BLOCK && (MTD=y || (ROMFS_FS=m && MTD))
+endchoice
+
+
+config ROMFS_ON_BLOCK
+        bool
+        default y if ROMFS_BACKED_BY_BLOCK || ROMFS_BACKED_BY_BOTH
+
+config ROMFS_ON_MTD
+        bool
+        default y if ROMFS_BACKED_BY_MTD || ROMFS_BACKED_BY_BOTH