fs/freevxfs/vxfs_immed.c

   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
  42 static void *   vxfs_immed_follow_link(struct dentry *, struct nameidata *);
  43
  44 static 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  */
  52 const 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  */
  60 const 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  */
  76 static void *
  77 vxfs_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  */
  99 static int
 100 vxfs_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 }