1 files changed, 90 insertions, 0 deletions
diff --git a/fs/file_table.c b/fs/file_table.c
new file mode 100644
index 000000000..6438162a0
--- /dev/null
+++ b/fs/file_table.c
@@ -0,0 +1,90 @@
+/*
+ *  linux/fs/file_table.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+
+struct file * first_file;
+int nr_files = 0;
+
+static void insert_file_free(struct file *file)
+{
+	file->f_next = first_file;
+	file->f_prev = first_file->f_prev;
+	file->f_next->f_prev = file;
+	file->f_prev->f_next = file;
+	first_file = file;
+}
+
+static void remove_file_free(struct file *file)
+{
+	if (first_file == file)
+		first_file = first_file->f_next;
+	if (file->f_next)
+		file->f_next->f_prev = file->f_prev;
+	if (file->f_prev)
+		file->f_prev->f_next = file->f_next;
+	file->f_next = file->f_prev = NULL;
+}
+
+static void put_last_free(struct file *file)
+{
+	remove_file_free(file);
+	file->f_prev = first_file->f_prev;
+	file->f_prev->f_next = file;
+	file->f_next = first_file;
+	file->f_next->f_prev = file;
+}
+
+void grow_files(void)
+{
+	struct file * file;
+	int i;
+
+	file = (struct file *) get_free_page(GFP_KERNEL);
+
+	if (!file)
+		return;
+
+	nr_files+=i= PAGE_SIZE/sizeof(struct file);
+
+	if (!first_file)
+		file->f_next = file->f_prev = first_file = file++, i--;
+
+	for (; i ; i--)
+		insert_file_free(file++);
+}
+
+unsigned long file_table_init(unsigned long start, unsigned long end)
+{
+	first_file = NULL;
+	return start;
+}
+
+struct file * get_empty_filp(void)
+{
+	int i;
+	struct file * f;
+
+	if (!first_file)
+		grow_files();
+repeat:
+	for (f = first_file, i=0; i < nr_files; i++, f = f->f_next)
+		if (!f->f_count) {
+			remove_file_free(f);
+			memset(f,0,sizeof(*f));
+			put_last_free(f);
+			f->f_count = 1;
+			f->f_version = ++event;
+			return f;
+		}
+	if (nr_files < NR_FILE) {
+		grow_files();
+		goto repeat;
+	}
+	return NULL;
+}