[PATCH] ramfs breaks without CONFIG_BLOCK

ramfs doesn't provide the .set_dirty_page a_op, and when the BLOCK layer is
not configured in, 'set_page_dirty' makes a call via a NULL pointer.

Signed-off-by: Dimitri Gorokhovik <dimitri.gorokhovik@free.fr>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/ramfs/file-mmu.c

@@ -25,11 +25,13 @@
  */
 
 #include <linux/fs.h>
+#include <linux/mm.h>
 
 const struct address_space_operations ramfs_aops = {
 	.readpage	= simple_readpage,
 	.prepare_write	= simple_prepare_write,
-	.commit_write	= simple_commit_write
+	.commit_write	= simple_commit_write,
+	.set_page_dirty = __set_page_dirty_nobuffers,
 };
 
 const struct file_operations ramfs_file_operations = {