/*
   * Copyright (c) 2000-2001 Christoph Hellwig.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions, and the following disclaimer,
   *    without modification.
   * 2. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL").
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  /*
   * Veritas filesystem driver - support for 'immed' inodes.
   */
  #include <linux/fs.h>
  #include <linux/pagemap.h>
  #include <linux/namei.h>
  
  #include "vxfs.h"
  #include "vxfs_extern.h"
  #include "vxfs_inode.h"
  
  
  static void *	vxfs_immed_follow_link(struct dentry *, struct nameidata *);
  
  static int	vxfs_immed_readpage(struct file *, struct page *);
  
  /*
   * Inode operations for immed symlinks.
   *
   * Unliked all other operations we do not go through the pagecache,
   * but do all work directly on the inode.
   */
  const struct inode_operations vxfs_immed_symlink_iops = {
  	.readlink =		generic_readlink,
  	.follow_link =		vxfs_immed_follow_link,
  };
  
  /*
   * Address space operations for immed files and directories.
   */
  const struct address_space_operations vxfs_immed_aops = {
  	.readpage =		vxfs_immed_readpage,
  };
  
  /**
   * vxfs_immed_follow_link - follow immed symlink
   * @dp:		dentry for the link
   * @np:		pathname lookup data for the current path walk
   *
   * Description:
   *   vxfs_immed_follow_link restarts the pathname lookup with
   *   the data obtained from @dp.
   *
   * Returns:
   *   Zero on success, else a negative error code.
   */
  static void *
  vxfs_immed_follow_link(struct dentry *dp, struct nameidata *np)
  {
  	struct vxfs_inode_info		*vip = VXFS_INO(dp->d_inode);
  	nd_set_link(np, vip->vii_immed.vi_immed);
  	return NULL;
  }
  
  /**
   * vxfs_immed_readpage - read part of an immed inode into pagecache
   * @file:	file context (unused)
   * @page:	page frame to fill in.
   *
   * Description:
   *   vxfs_immed_readpage reads a part of the immed area of the
   *   file that hosts @pp into the pagecache.
   *
   * Returns:
   *   Zero on success, else a negative error code.
   *
   * Locking status:
   *   @page is locked and will be unlocked.
   */
  static int
  vxfs_immed_readpage(struct file *fp, struct page *pp)
  {
  	struct vxfs_inode_info	*vip = VXFS_INO(pp->mapping->host);
  	u_int64_t	offset = (u_int64_t)pp->index << PAGE_CACHE_SHIFT;
  	caddr_t		kaddr;
  
  	kaddr = kmap(pp);
  	memcpy(kaddr, vip->vii_immed.vi_immed + offset, PAGE_CACHE_SIZE);
  	kunmap(pp);
  	
  	flush_dcache_page(pp);
  	SetPageUptodate(pp);
          unlock_page(pp);
  
  	return 0;
  }