/*
 *  mmap.c
 *
 *  Copyright (C) 1995, 1996 by Paal-Kr. Engstad and Volker Lendecke
 *
 */

#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/errno.h>
#include <linux/mman.h>
#include <linux/string.h>
#include <linux/malloc.h>
#include <linux/smb_fs.h>
#include <linux/fcntl.h>

#include <asm/uaccess.h>
#include <asm/system.h>

/*
 * Fill in the supplied page for mmap
 */
static unsigned long
smb_file_mmap_nopage(struct vm_area_struct *area,
		     unsigned long address, int no_share)
{
	struct inode *inode = area->vm_inode;
	unsigned long page;
	unsigned int clear;
	unsigned long tmp;
	int n;
	int i;
	int pos;

	page = __get_free_page(GFP_KERNEL);
	if (!page)
		return 0;
	address &= PAGE_MASK;
	pos = address - area->vm_start + area->vm_offset;

	clear = 0;
	if (address + PAGE_SIZE > area->vm_end)
	{
		clear = address + PAGE_SIZE - area->vm_end;
	}
	/* what we can read in one go */
	n = SMB_SERVER(inode)->max_xmit - SMB_HEADER_LEN - 5 * 2 - 3 - 10;

	if (smb_make_open(inode, O_RDONLY) < 0)
	{
		clear = PAGE_SIZE;
	} else
	{

		for (i = 0; i < (PAGE_SIZE - clear); i += n)
		{
			int hunk, result;

			hunk = PAGE_SIZE - i;
			if (hunk > n)
				hunk = n;

			DDPRINTK("smb_file_mmap_nopage: reading\n");
			DDPRINTK("smb_file_mmap_nopage: pos = %d\n", pos);
			result = smb_proc_read(SMB_SERVER(inode),
					       SMB_FINFO(inode), pos, hunk,
					       (char *) (page + i), 0);
			DDPRINTK("smb_file_mmap_nopage: result= %d\n", result);
			if (result < 0)
				break;
			pos += result;
			if (result < n)
			{
				i += result;
				break;
			}
		}
	}

	tmp = page + PAGE_SIZE;
	while (clear--)
	{
		*(char *) --tmp = 0;
	}
	return page;
}

struct vm_operations_struct smb_file_mmap =
{
	NULL,			/* open */
	NULL,			/* close */
	NULL,			/* unmap */
	NULL,			/* protect */
	NULL,			/* sync */
	NULL,			/* advise */
	smb_file_mmap_nopage,	/* nopage */
	NULL,			/* wppage */
	NULL,			/* swapout */
	NULL,			/* swapin */
};


/* This is used for a general mmap of a smb file */
int
smb_mmap(struct inode *inode, struct file *file, struct vm_area_struct *vma)
{
	DPRINTK("smb_mmap: called\n");

	/* only PAGE_COW or read-only supported now */
	if (vma->vm_flags & VM_SHARED)
		return -EINVAL;
	if (!inode->i_sb || !S_ISREG(inode->i_mode))
		return -EACCES;
	if (!IS_RDONLY(inode))
	{
		inode->i_atime = CURRENT_TIME;
		inode->i_dirt = 1;
	}

	vma->vm_dentry = dget(file->f_dentry);
	vma->vm_ops = &smb_file_mmap;
	return 0;
}