/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * mmap.c
   *
   * Code to deal with the mess that is clustered mmap.
   *
   * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * 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 the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/fs.h>
  #include <linux/types.h>

  #include <linux/highmem.h>
  #include <linux/pagemap.h>
  #include <linux/uio.h>
  #include <linux/signal.h>
  #include <linux/rbtree.h>
  
  #define MLOG_MASK_PREFIX ML_FILE_IO
  #include <cluster/masklog.h>
  
  #include "ocfs2.h"

  #include "aops.h"

  #include "dlmglue.h"
  #include "file.h"
  #include "inode.h"
  #include "mmap.h"

  #include "super.h"

  static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)

  {

  	sigset_t oldset;
  	int ret;

  	mlog_entry("(area=%p, page offset=%lu)
  ", area, vmf->pgoff);

  	ocfs2_block_signals(&oldset);

  	ret = filemap_fault(area, vmf);

  	ocfs2_unblock_signals(&oldset);

  	mlog_exit_ptr(vmf->page);
  	return ret;

  }

  static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
  				struct page *page)
  {
  	int ret;
  	struct address_space *mapping = inode->i_mapping;

  	loff_t pos = page_offset(page);

  	unsigned int len = PAGE_CACHE_SIZE;
  	pgoff_t last_index;
  	struct page *locked_page = NULL;
  	void *fsdata;
  	loff_t size = i_size_read(inode);

  	/*
  	 * Another node might have truncated while we were waiting on
  	 * cluster locks.

  	 * We don't check size == 0 before the shift. This is borrowed
  	 * from do_generic_file_read.

  	 */

  	last_index = (size - 1) >> PAGE_CACHE_SHIFT;
  	if (unlikely(!size || page->index > last_index)) {

  		ret = -EINVAL;
  		goto out;
  	}
  
  	/*
  	 * The i_size check above doesn't catch the case where nodes
  	 * truncated and then re-extended the file. We'll re-check the
  	 * page mapping after taking the page lock inside of
  	 * ocfs2_write_begin_nolock().
  	 */
  	if (!PageUptodate(page) || page->mapping != inode->i_mapping) {

  		/*
  		 * the page has been umapped in ocfs2_data_downconvert_worker.
  		 * So return 0 here and let VFS retry.
  		 */
  		ret = 0;

  		goto out;
  	}
  
  	/*
  	 * Call ocfs2_write_begin() and ocfs2_write_end() to take
  	 * advantage of the allocation code there. We pass a write
  	 * length of the whole page (chopped to i_size) to make sure
  	 * the whole thing is allocated.
  	 *
  	 * Since we know the page is up to date, we don't have to
  	 * worry about ocfs2_write_begin() skipping some buffer reads
  	 * because the "write" would invalidate their data.
  	 */
  	if (page->index == last_index)

  		len = ((size - 1) & ~PAGE_CACHE_MASK) + 1;

  
  	ret = ocfs2_write_begin_nolock(mapping, pos, len, 0, &locked_page,
  				       &fsdata, di_bh, page);
  	if (ret) {
  		if (ret != -ENOSPC)
  			mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
  				     fsdata);
  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out;
  	}
  	BUG_ON(ret != len);
  	ret = 0;
  out:
  	return ret;
  }

  static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)

  {

  	struct page *page = vmf->page;

  	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
  	struct buffer_head *di_bh = NULL;

  	sigset_t oldset;
  	int ret;

  	ocfs2_block_signals(&oldset);

  
  	/*
  	 * The cluster locks taken will block a truncate from another
  	 * node. Taking the data lock will also ensure that we don't
  	 * attempt page truncation as part of a downconvert.
  	 */

  	ret = ocfs2_inode_lock(inode, &di_bh, 1);

  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out;
  	}

  	/*

  	 * The alloc sem should be enough to serialize with
  	 * ocfs2_truncate_file() changing i_size as well as any thread
  	 * modifying the inode btree.

  	 */

  	down_write(&OCFS2_I(inode)->ip_alloc_sem);

  	ret = __ocfs2_page_mkwrite(inode, di_bh, page);

  	up_write(&OCFS2_I(inode)->ip_alloc_sem);
  
  	brelse(di_bh);

  	ocfs2_inode_unlock(inode, 1);

  
  out:

  	ocfs2_unblock_signals(&oldset);

  	if (ret)
  		ret = VM_FAULT_SIGBUS;

  	return ret;
  }

  static const struct vm_operations_struct ocfs2_file_vm_ops = {

  	.fault		= ocfs2_fault,

  	.page_mkwrite	= ocfs2_page_mkwrite,
  };
  
  int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
  {
  	int ret = 0, lock_level = 0;

  	ret = ocfs2_inode_lock_atime(file->f_dentry->d_inode,

  				    file->f_vfsmnt, &lock_level);
  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out;
  	}

  	ocfs2_inode_unlock(file->f_dentry->d_inode, lock_level);

  out:

  	vma->vm_ops = &ocfs2_file_vm_ops;

  	vma->vm_flags |= VM_CAN_NONLINEAR;

  	return 0;
  }