F2FS: Backport to 3.4

Based off of patches here:
nowcomputing/f2fs-backports#1

Change-Id: I2be6d8abf4e3e4c6b9e8d635700930af432fe37a
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index c60b7b1..3be6d3d 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -450,22 +450,6 @@
 	return 0;
 }
 
-static int f2fs_freeze(struct super_block *sb)
-{
-	int err;
-
-	if (f2fs_readonly(sb))
-		return 0;
-
-	err = f2fs_sync_fs(sb, 1);
-	return err;
-}
-
-static int f2fs_unfreeze(struct super_block *sb)
-{
-	return 0;
-}
-
 static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
@@ -551,7 +535,7 @@
 
 static int segment_info_open_fs(struct inode *inode, struct file *file)
 {
-	return single_open(file, segment_info_seq_show, PDE_DATA(inode));
+	return single_open(file, segment_info_seq_show, PDE(inode)->data);
 }
 
 static const struct file_operations f2fs_seq_segment_info_fops = {
@@ -624,8 +608,6 @@
 	.evict_inode	= f2fs_evict_inode,
 	.put_super	= f2fs_put_super,
 	.sync_fs	= f2fs_sync_fs,
-	.freeze_fs	= f2fs_freeze,
-	.unfreeze_fs	= f2fs_unfreeze,
 	.statfs		= f2fs_statfs,
 	.remount_fs	= f2fs_remount,
 };