seq_file: constify seq_operations

Make all seq_operations structs const, to help mitigate against
revectoring user-triggerable function pointers.

This is derived from the grsecurity patch, although generated from scratch
because it's simpler than extracting the changes from there.

Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index a8a358b..53b86e1 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -768,7 +768,7 @@
 {
 }
 
-static struct seq_operations jbd2_seq_history_ops = {
+static const struct seq_operations jbd2_seq_history_ops = {
 	.start  = jbd2_seq_history_start,
 	.next   = jbd2_seq_history_next,
 	.stop   = jbd2_seq_history_stop,
@@ -872,7 +872,7 @@
 {
 }
 
-static struct seq_operations jbd2_seq_info_ops = {
+static const struct seq_operations jbd2_seq_info_ops = {
 	.start  = jbd2_seq_info_start,
 	.next   = jbd2_seq_info_next,
 	.stop   = jbd2_seq_info_stop,