/*
   * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.

   * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.

   *
   * This copyrighted material is made available to anyone wishing to use,
   * modify, copy, or redistribute it subject to the terms and conditions

   * of the GNU General Public License version 2.

   */

  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/completion.h>
  #include <linux/buffer_head.h>
  #include <linux/mm.h>
  #include <linux/pagemap.h>

  #include <linux/gfs2_ondisk.h>

  #include <linux/lm_interface.h>

  
  #include "gfs2.h"

  #include "incore.h"

  #include "bmap.h"
  #include "glock.h"
  #include "inode.h"
  #include "ops_vm.h"

  #include "quota.h"
  #include "rgrp.h"
  #include "trans.h"

  #include "util.h"

  static int gfs2_private_fault(struct vm_area_struct *vma, struct vm_fault *vmf)

  {

  	struct gfs2_inode *ip = GFS2_I(vma->vm_file->f_mapping->host);

  
  	set_bit(GIF_PAGED, &ip->i_flags);

  	return filemap_fault(vma, vmf);

  }
  
  static int alloc_page_backing(struct gfs2_inode *ip, struct page *page)
  {

  	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

  	unsigned long index = page->index;

  	u64 lblock = index << (PAGE_CACHE_SHIFT -

  				    sdp->sd_sb.sb_bsize_shift);

  	unsigned int blocks = PAGE_CACHE_SIZE >> sdp->sd_sb.sb_bsize_shift;
  	struct gfs2_alloc *al;
  	unsigned int data_blocks, ind_blocks;
  	unsigned int x;
  	int error;
  
  	al = gfs2_alloc_get(ip);
  
  	error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
  	if (error)
  		goto out;

  	error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);

  	if (error)
  		goto out_gunlock_q;

  	gfs2_write_calc_reserv(ip, PAGE_CACHE_SIZE, &data_blocks, &ind_blocks);

  
  	al->al_requested = data_blocks + ind_blocks;
  
  	error = gfs2_inplace_reserve(ip);
  	if (error)
  		goto out_gunlock_q;

  	error = gfs2_trans_begin(sdp, al->al_rgd->rd_length +

  				 ind_blocks + RES_DINODE +
  				 RES_STATFS + RES_QUOTA, 0);
  	if (error)
  		goto out_ipres;
  
  	if (gfs2_is_stuffed(ip)) {

  		error = gfs2_unstuff_dinode(ip, NULL);

  		if (error)
  			goto out_trans;
  	}
  
  	for (x = 0; x < blocks; ) {

  		u64 dblock;

  		unsigned int extlen;
  		int new = 1;

  		error = gfs2_extent_map(&ip->i_inode, lblock, &new, &dblock, &extlen);

  		if (error)
  			goto out_trans;
  
  		lblock += extlen;
  		x += extlen;
  	}
  
  	gfs2_assert_warn(sdp, al->al_alloced);

  out_trans:

  	gfs2_trans_end(sdp);

  out_ipres:

  	gfs2_inplace_release(ip);

  out_gunlock_q:

  	gfs2_quota_unlock(ip);

  out:

  	gfs2_alloc_put(ip);

  	return error;
  }

  static int gfs2_sharewrite_fault(struct vm_area_struct *vma,
  						struct vm_fault *vmf)

  {

  	struct file *file = vma->vm_file;

  	struct gfs2_file *gf = file->private_data;
  	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);

  	struct gfs2_holder i_gh;

  	int alloc_required;
  	int error;

  	int ret = 0;

  	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
  	if (error)

  		goto out;

  	set_bit(GIF_PAGED, &ip->i_flags);
  	set_bit(GIF_SW_PAGED, &ip->i_flags);

  	error = gfs2_write_alloc_required(ip,

  					(u64)vmf->pgoff << PAGE_CACHE_SHIFT,

  					PAGE_CACHE_SIZE, &alloc_required);
  	if (error) {

  		ret = VM_FAULT_OOM; /* XXX: are these right? */
  		goto out_unlock;

  	}

  	set_bit(GFF_EXLOCK, &gf->f_flags);

  	ret = filemap_fault(vma, vmf);

  	clear_bit(GFF_EXLOCK, &gf->f_flags);

  	if (ret & VM_FAULT_ERROR)

  		goto out_unlock;

  
  	if (alloc_required) {

  		/* XXX: do we need to drop page lock around alloc_page_backing?*/
  		error = alloc_page_backing(ip, vmf->page);

  		if (error) {

  			/*
  			 * VM_FAULT_LOCKED should always be the case for
  			 * filemap_fault, but it may not be in a future
  			 * implementation.
  			 */
  			if (ret & VM_FAULT_LOCKED)

  				unlock_page(vmf->page);
  			page_cache_release(vmf->page);
  			ret = VM_FAULT_OOM;
  			goto out_unlock;

  		}

  		set_page_dirty(vmf->page);

  	}

  out_unlock:

  	gfs2_glock_dq_uninit(&i_gh);

  out:
  	return ret;

  }
  
  struct vm_operations_struct gfs2_vm_ops_private = {

  	.fault = gfs2_private_fault,

  };
  
  struct vm_operations_struct gfs2_vm_ops_sharewrite = {

  	.fault = gfs2_sharewrite_fault,

  };