reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show()

Don't access the proc_dir_entry in ReiserFS's r_open(), r_start() r_show()
procfs interface functions.

ReiserFS stores the ->show() method pointer in PDE->data and the super_block
pointer in PDE->parent->data.  This isn't changing.

Currently, ReiserFS passes the PDE pointer into seq_file::private from
r_open() so that r_start() and r_show() can then access it.  Instead, use
seq_open_private() to allocate a two-pointer struct that's passed through
seq_file::private and put the ->show() method and the sb pointers in there.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: reiserfs-devel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/reiserfs/procfs.c

@@ -394,20 +394,24 @@ static int set_sb(struct super_block *sb, void *data)
 	return -ENOENT;
 }
 
+struct reiserfs_seq_private {
+	struct super_block *sb;
+	int (*show) (struct seq_file *, struct super_block *);
+};
+
 static void *r_start(struct seq_file *m, loff_t * pos)
 {
-	struct proc_dir_entry *de = m->private;
-	struct super_block *s = de->parent->data;
+	struct reiserfs_seq_private *priv = m->private;
 	loff_t l = *pos;
 
 	if (l)
 		return NULL;
 
-	if (IS_ERR(sget(&reiserfs_fs_type, test_sb, set_sb, 0, s)))
+	if (IS_ERR(sget(&reiserfs_fs_type, test_sb, set_sb, 0, priv->sb)))
 		return NULL;
 
-	up_write(&s->s_umount);
-	return s;
+	up_write(&priv->sb->s_umount);
+	return priv->sb;
 }
 
 static void *r_next(struct seq_file *m, void *v, loff_t * pos)
@@ -426,9 +430,8 @@ static void r_stop(struct seq_file *m, void *v)
 
 static int r_show(struct seq_file *m, void *v)
 {
-	struct proc_dir_entry *de = m->private;
-	int (*show) (struct seq_file *, struct super_block *) = de->data;
-	return show(m, v);
+	struct reiserfs_seq_private *priv = m->private;
+	return priv->show(m, v);
 }
 
 static const struct seq_operations r_ops = {
@@ -440,11 +443,15 @@ static const struct seq_operations r_ops = {
 
 static int r_open(struct inode *inode, struct file *file)
 {
-	int ret = seq_open(file, &r_ops);
+	struct reiserfs_seq_private *priv;
+	int ret = seq_open_private(file, &r_ops,
+				   sizeof(struct reiserfs_seq_private));
 
 	if (!ret) {
 		struct seq_file *m = file->private_data;
-		m->private = PDE(inode);
+		priv = m->private;
+		priv->sb = proc_get_parent_data(inode);
+		priv->show = PDE_DATA(inode);
 	}
 	return ret;
 }
@@ -453,7 +460,7 @@ static const struct file_operations r_file_operations = {
 	.open = r_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
-	.release = seq_release,
+	.release = seq_release_private,
 	.owner = THIS_MODULE,
 };