/*
   *  linux/fs/9p/vfs_file.c
   *
   * This file contians vfs file ops for 9P2000.
   *
   *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   *
   *  This program is free software; you can redistribute it and/or modify

   *  it under the terms of the GNU General Public License version 2
   *  as published by the Free Software Foundation.

   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to:
   *  Free Software Foundation
   *  51 Franklin Street, Fifth Floor
   *  Boston, MA  02111-1301  USA
   *
   */
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/fs.h>

  #include <linux/sched.h>

  #include <linux/file.h>
  #include <linux/stat.h>
  #include <linux/string.h>

  #include <linux/inet.h>

  #include <linux/list.h>
  #include <asm/uaccess.h>
  #include <linux/idr.h>

  #include <net/9p/9p.h>
  #include <net/9p/client.h>

  #include "v9fs.h"

  #include "v9fs_vfs.h"
  #include "fid.h"

  static const struct file_operations v9fs_cached_file_operations;

  /**
   * v9fs_file_open - open a file (or directory)
   * @inode: inode to be opened
   * @file: file being opened
   *
   */
  
  int v9fs_file_open(struct inode *inode, struct file *file)
  {

  	int err;

  	struct v9fs_session_info *v9ses;
  	struct p9_fid *fid;
  	int omode;

  	P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p 
  ", inode, file);
  	v9ses = v9fs_inode2v9ses(inode);

  	omode = v9fs_uflags2omode(file->f_flags);

  	fid = file->private_data;
  	if (!fid) {
  		fid = v9fs_fid_clone(file->f_path.dentry);
  		if (IS_ERR(fid))
  			return PTR_ERR(fid);
  
  		err = p9_client_open(fid, omode);

  		if (err < 0) {

  			p9_client_clunk(fid);
  			return err;
  		}

  		if (omode & P9_OTRUNC) {
  			inode->i_size = 0;
  			inode->i_blocks = 0;
  		}

  	}

  	file->private_data = fid;
  	if ((fid->qid.version) && (v9ses->cache)) {
  		P9_DPRINTK(P9_DEBUG_VFS, "cached");

  		/* enable cached file options */
  		if(file->f_op == &v9fs_file_operations)
  			file->f_op = &v9fs_cached_file_operations;
  	}

  	return 0;

  }
  
  /**
   * v9fs_file_lock - lock a file (or directory)
   * @inode: inode to be opened
   * @file: file being opened
   *
   * XXX - this looks like a local only lock, we should extend into 9P
   *       by using open exclusive
   */
  
  static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
  {
  	int res = 0;

  	struct inode *inode = filp->f_path.dentry->d_inode;

  	P9_DPRINTK(P9_DEBUG_VFS, "filp: %p lock: %p
  ", filp, fl);

  
  	/* No mandatory locks */
  	if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
  		return -ENOLCK;
  
  	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {

  		filemap_write_and_wait(inode->i_mapping);

  		invalidate_mapping_pages(&inode->i_data, 0, -1);

  	}
  
  	return res;
  }
  
  /**

   * v9fs_file_read - read from a file

   * @filep: file pointer to read
   * @data: data buffer to read data into
   * @count: size of buffer
   * @offset: offset at which to read data
   *
   */

  static ssize_t

  v9fs_file_read(struct file *filp, char __user * data, size_t count,
  	       loff_t * offset)

  {

  	int ret;
  	struct p9_fid *fid;

  	P9_DPRINTK(P9_DEBUG_VFS, "
  ");
  	fid = filp->private_data;
  	ret = p9_client_uread(fid, data, *offset, count);
  	if (ret > 0)
  		*offset += ret;

  	return ret;

  }
  
  /**

   * v9fs_file_write - write to a file

   * @filep: file pointer to write
   * @data: data buffer to write data from
   * @count: size of buffer
   * @offset: offset at which to write data
   *
   */
  
  static ssize_t

  v9fs_file_write(struct file *filp, const char __user * data,
  		size_t count, loff_t * offset)

  {

  	int ret;
  	struct p9_fid *fid;

  	struct inode *inode = filp->f_path.dentry->d_inode;

  	P9_DPRINTK(P9_DEBUG_VFS, "data %p count %d offset %x
  ", data,
  		(int)count, (int)*offset);

  	fid = filp->private_data;
  	ret = p9_client_uwrite(fid, data, *offset, count);
  	if (ret > 0)
  		*offset += ret;

  	if (*offset > inode->i_size) {
  		inode->i_size = *offset;
  		inode->i_blocks = (inode->i_size + 512 - 1) >> 9;
  	}
  
  	invalidate_inode_pages2(inode->i_mapping);

  	return ret;

  }

  static const struct file_operations v9fs_cached_file_operations = {

  	.llseek = generic_file_llseek,
  	.read = do_sync_read,
  	.aio_read = generic_file_aio_read,
  	.write = v9fs_file_write,
  	.open = v9fs_file_open,
  	.release = v9fs_dir_release,
  	.lock = v9fs_file_lock,
  	.mmap = generic_file_mmap,
  };

  const struct file_operations v9fs_file_operations = {

  	.llseek = generic_file_llseek,
  	.read = v9fs_file_read,
  	.write = v9fs_file_write,
  	.open = v9fs_file_open,
  	.release = v9fs_dir_release,
  	.lock = v9fs_file_lock,

  	.mmap = generic_file_mmap,

  };