1/*
  2 * Copyright (c) 2000-2001 Christoph Hellwig.
  3 * All rights reserved.
  4 *
  5 * Redistribution and use in source and binary forms, with or without
  6 * modification, are permitted provided that the following conditions
  7 * are met:
  8 * 1. Redistributions of source code must retain the above copyright
  9 *    notice, this list of conditions, and the following disclaimer,
 10 *    without modification.
 11 * 2. The name of the author may not be used to endorse or promote products
 12 *    derived from this software without specific prior written permission.
 13 *
 14 * Alternatively, this software may be distributed under the terms of the
 15 * GNU General Public License ("GPL").
 16 *
 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 21 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 27 * SUCH DAMAGE.
 28 */
 29
 30/*
 31 * Veritas filesystem driver - support for 'immed' inodes.
 32 */
 33#include <linux/fs.h>
 34#include <linux/pagemap.h>
 35#include <linux/namei.h>
 36
 37#include "vxfs.h"
 38#include "vxfs_extern.h"
 39#include "vxfs_inode.h"
 40
 41
 42static void *	vxfs_immed_follow_link(struct dentry *, struct nameidata *);
 43
 44static int	vxfs_immed_readpage(struct file *, struct page *);
 45
 46/*
 47 * Inode operations for immed symlinks.
 48 *
 49 * Unliked all other operations we do not go through the pagecache,
 50 * but do all work directly on the inode.
 51 */
 52const struct inode_operations vxfs_immed_symlink_iops = {
 53	.readlink =		generic_readlink,
 54	.follow_link =		vxfs_immed_follow_link,
 55};
 56
 57/*
 58 * Address space operations for immed files and directories.
 59 */
 60const struct address_space_operations vxfs_immed_aops = {
 61	.readpage =		vxfs_immed_readpage,
 62};
 63
 64/**
 65 * vxfs_immed_follow_link - follow immed symlink
 66 * @dp:		dentry for the link
 67 * @np:		pathname lookup data for the current path walk
 68 *
 69 * Description:
 70 *   vxfs_immed_follow_link restarts the pathname lookup with
 71 *   the data obtained from @dp.
 72 *
 73 * Returns:
 74 *   Zero on success, else a negative error code.
 75 */
 76static void *
 77vxfs_immed_follow_link(struct dentry *dp, struct nameidata *np)
 78{
 79	struct vxfs_inode_info		*vip = VXFS_INO(dp->d_inode);
 80	nd_set_link(np, vip->vii_immed.vi_immed);
 81	return NULL;
 82}
 83
 84/**
 85 * vxfs_immed_readpage - read part of an immed inode into pagecache
 86 * @file:	file context (unused)
 87 * @page:	page frame to fill in.
 88 *
 89 * Description:
 90 *   vxfs_immed_readpage reads a part of the immed area of the
 91 *   file that hosts @pp into the pagecache.
 92 *
 93 * Returns:
 94 *   Zero on success, else a negative error code.
 95 *
 96 * Locking status:
 97 *   @page is locked and will be unlocked.
 98 */
 99static int
100vxfs_immed_readpage(struct file *fp, struct page *pp)
101{
102	struct vxfs_inode_info	*vip = VXFS_INO(pp->mapping->host);
103	u_int64_t	offset = (u_int64_t)pp->index << PAGE_CACHE_SHIFT;
104	caddr_t		kaddr;
105
106	kaddr = kmap(pp);
107	memcpy(kaddr, vip->vii_immed.vi_immed + offset, PAGE_CACHE_SIZE);
108	kunmap(pp);
109	
110	flush_dcache_page(pp);
111	SetPageUptodate(pp);
112        unlock_page(pp);
113
114	return 0;
115}