release/src-rt-6.x/linux/linux-2.6/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_inode.h"
  39
  40
  41 static void *   vxfs_immed_follow_link(struct dentry *, struct nameidata *);
  42
  43 static int      vxfs_immed_readpage(struct file *, struct page *);
  44
  45 /*
  46  * Inode operations for immed symlinks.
  47  *
  48  * Unliked all other operations we do not go through the pagecache,
  49  * but do all work directly on the inode.
  50  */
  51 const struct inode_operations vxfs_immed_symlink_iops = {
  52         .readlink =             generic_readlink,
  53         .follow_link =          vxfs_immed_follow_link,
  54 };
  55
  56 /*
  57  * Adress space operations for immed files and directories.
  58  */
  59 const struct address_space_operations vxfs_immed_aops = {
  60         .readpage =             vxfs_immed_readpage,
  61 };
  62
  63 /**
  64  * vxfs_immed_follow_link - follow immed symlink
  65  * @dp:         dentry for the link
  66  * @np:         pathname lookup data for the current path walk
  67  *
  68  * Description:
  69  *   vxfs_immed_follow_link restarts the pathname lookup with
  70  *   the data obtained from @dp.
  71  *
  72  * Returns:
  73  *   Zero on success, else a negative error code.
  74  */
  75 static void *
  76 vxfs_immed_follow_link(struct dentry *dp, struct nameidata *np)
  77 {
  78         struct vxfs_inode_info          *vip = VXFS_INO(dp->d_inode);
  79         nd_set_link(np, vip->vii_immed.vi_immed);
  80         return NULL;
  81 }
  82
  83 /**
  84  * vxfs_immed_readpage - read part of an immed inode into pagecache
  85  * @file:       file context (unused)
  86  * @page:       page frame to fill in.
  87  *
  88  * Description:
  89  *   vxfs_immed_readpage reads a part of the immed area of the
  90  *   file that hosts @pp into the pagecache.
  91  *
  92  * Returns:
  93  *   Zero on success, else a negative error code.
  94  *
  95  * Locking status:
  96  *   @page is locked and will be unlocked.
  97  */
  98 static int
  99 vxfs_immed_readpage(struct file *fp, struct page *pp)
 100 {
 101         struct vxfs_inode_info  *vip = VXFS_INO(pp->mapping->host);
 102         u_int64_t       offset = (u_int64_t)pp->index << PAGE_CACHE_SHIFT;
 103         caddr_t         kaddr;
 104
 105         kaddr = kmap(pp);
 106         memcpy(kaddr, vip->vii_immed.vi_immed + offset, PAGE_CACHE_SIZE);
 107         kunmap(pp);
 108
 109         flush_dcache_page(pp);
 110         SetPageUptodate(pp);
 111         unlock_page(pp);
 112
 113         return 0;
 114 }