[RFC][PATCH 6/8] mark /dev/null and zero as checkpointable

[Dave Hansen <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

We currently have a special_file() check in the checkpoint
code which considers all special files as uncheckpointable.

Now that we have the f_op and a generic function, use that
to override these simple devices and make them OK to
checkpoint.

Signed-off-by: Dave Hansen <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
---

 linux-2.6.git-dave/drivers/char/mem.c |    3 +++
 1 file changed, 3 insertions(+)

diff -puN drivers/char/mem.c~make-dev-null-work drivers/char/mem.c
--- linux-2.6.git/drivers/char/mem.c~make-dev-null-work	2009-02-27 12:07:39.000000000 -0800
+++ linux-2.6.git-dave/drivers/char/mem.c	2009-02-27 12:07:39.000000000 -0800
@@ -27,6 +27,7 @@
 #include <linux/splice.h>
 #include <linux/pfn.h>
 #include <linux/smp_lock.h>
+#include <linux/checkpoint.h>
 
 #include <asm/uaccess.h>
 #include <asm/io.h>
@@ -824,6 +825,7 @@ static const struct file_operations null
 	.read		= read_null,
 	.write		= write_null,
 	.splice_write	= splice_write_null,
+	.checkpoint	= generic_file_checkpoint,
 };
 
 #ifdef CONFIG_DEVPORT
@@ -840,6 +842,7 @@ static const struct file_operations zero
 	.read		= read_zero,
 	.write		= write_zero,
 	.mmap		= mmap_zero,
+	.checkpoint	= generic_file_checkpoint,
 };
 
 /*
_