[PATCH 3/4] maps: introduce generic_maps_open()

[Fengguang Wu <wfg@mail.ustc.edu.cn>]

[-- Attachment #1: maps-generic-open.patch --]
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Introduce generic_maps_open(). It is an extended version of do_maps_open().
The new function supports batch_size and custom sized seqfile/private buffers.
This function will be reused by pmaps.

Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
 fs/proc/task_mmu.c |   51 ++++++++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 15 deletions(-)

--- linux-2.6.23-rc2-mm2.orig/fs/proc/task_mmu.c
+++ linux-2.6.23-rc2-mm2/fs/proc/task_mmu.c
@@ -178,24 +178,45 @@ static void m_stop(struct seq_file *m, v
 		put_task_struct(priv->task);
 }
 
+static int generic_maps_open(struct inode *inode, struct file *file,
+			struct seq_operations *ops, unsigned long batch_size,
+			int bufsize, int privsize)
+{
+	struct seq_file *m;
+	struct proc_maps_private *priv = NULL;
+	char *buf = NULL;
+	int ret = -ENOMEM;
+
+	priv = kzalloc(privsize, GFP_KERNEL);
+	if (!priv)
+		goto out;
+
+	buf = kmalloc(bufsize, GFP_KERNEL);
+	if (!buf)
+		goto out;
+
+	ret = seq_open(file, ops);
+	if (ret)
+		goto out;
+
+	m = file->private_data;
+	m->private = priv;
+	m->buf = buf;
+	m->size = bufsize;
+	priv->pid = proc_pid(inode);
+	priv->batch_size = batch_size;
+	return 0;
+out:
+	kfree(priv);
+	kfree(buf);
+	return ret;
+}
+
 static int do_maps_open(struct inode *inode, struct file *file,
 			struct seq_operations *ops)
 {
-	struct proc_maps_private *priv;
-	int ret = -ENOMEM;
-	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-	if (priv) {
-		priv->pid = proc_pid(inode);
-		priv->batch_size = ~0;
-		ret = seq_open(file, ops);
-		if (!ret) {
-			struct seq_file *m = file->private_data;
-			m->private = priv;
-		} else {
-			kfree(priv);
-		}
-	}
-	return ret;
+	return generic_maps_open(inode, file, ops, ~0, 2 * PAGE_SIZE,
+				 sizeof(struct proc_maps_private));
 }
 
 static int show_map(struct seq_file *m, void *v)

--