original development tree for Linux kernel GTP module; now long in mainline.
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/*
* 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;
}