release/src-rt-6.x/linux/linux-2.6/fs/freevxfs/vxfs_subr.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 - shared subroutines.
  32  */
  33 #include <linux/fs.h>
  34 #include <linux/buffer_head.h>
  35 #include <linux/kernel.h>
  36 #include <linux/slab.h>
  37 #include <linux/pagemap.h>
  38
  39 #include "vxfs_extern.h"
  40
  41
  42 static int              vxfs_readpage(struct file *, struct page *);
  43 static sector_t         vxfs_bmap(struct address_space *, sector_t);
  44
  45 const struct address_space_operations vxfs_aops = {
  46         .readpage =             vxfs_readpage,
  47         .bmap =                 vxfs_bmap,
  48         .sync_page =            block_sync_page,
  49 };
  50
  51 inline void
  52 vxfs_put_page(struct page *pp)
  53 {
  54         kunmap(pp);
  55         page_cache_release(pp);
  56 }
  57
  58 /**
  59  * vxfs_get_page - read a page into memory.
  60  * @ip:         inode to read from
  61  * @n:          page number
  62  *
  63  * Description:
  64  *   vxfs_get_page reads the @n th page of @ip into the pagecache.
  65  *
  66  * Returns:
  67  *   The wanted page on success, else a NULL pointer.
  68  */
  69 struct page *
  70 vxfs_get_page(struct address_space *mapping, u_long n)
  71 {
  72         struct page *                   pp;
  73
  74         pp = read_mapping_page(mapping, n, NULL);
  75
  76         if (!IS_ERR(pp)) {
  77                 kmap(pp);
  78                 /** if (!PageChecked(pp)) **/
  79                         /** vxfs_check_page(pp); **/
  80                 if (PageError(pp))
  81                         goto fail;
  82         }
  83
  84         return (pp);
  85
  86 fail:
  87         vxfs_put_page(pp);
  88         return ERR_PTR(-EIO);
  89 }
  90
  91 /**
  92  * vxfs_bread - read buffer for a give inode,block tuple
  93  * @ip:         inode
  94  * @block:      logical block
  95  *
  96  * Description:
  97  *   The vxfs_bread function reads block no @block  of
  98  *   @ip into the buffercache.
  99  *
 100  * Returns:
 101  *   The resulting &struct buffer_head.
 102  */
 103 struct buffer_head *
 104 vxfs_bread(struct inode *ip, int block)
 105 {
 106         struct buffer_head      *bp;
 107         daddr_t                 pblock;
 108
 109         pblock = vxfs_bmap1(ip, block);
 110         bp = sb_bread(ip->i_sb, pblock);
 111
 112         return (bp);
 113 }
 114
 115 /**
 116  * vxfs_get_block - locate buffer for given inode,block tuple
 117  * @ip:         inode
 118  * @iblock:     logical block
 119  * @bp:         buffer skeleton
 120  * @create:     %TRUE if blocks may be newly allocated.
 121  *
 122  * Description:
 123  *   The vxfs_get_block function fills @bp with the right physical
 124  *   block and device number to perform a lowlevel read/write on
 125  *   it.
 126  *
 127  * Returns:
 128  *   Zero on success, else a negativ error code (-EIO).
 129  */
 130 static int
 131 vxfs_getblk(struct inode *ip, sector_t iblock,
 132             struct buffer_head *bp, int create)
 133 {
 134         daddr_t                 pblock;
 135
 136         pblock = vxfs_bmap1(ip, iblock);
 137         if (pblock != 0) {
 138                 map_bh(bp, ip->i_sb, pblock);
 139                 return 0;
 140         }
 141
 142         return -EIO;
 143 }
 144
 145 /**
 146  * vxfs_readpage - read one page synchronously into the pagecache
 147  * @file:       file context (unused)
 148  * @page:       page frame to fill in.
 149  *
 150  * Description:
 151  *   The vxfs_readpage routine reads @page synchronously into the
 152  *   pagecache.
 153  *
 154  * Returns:
 155  *   Zero on success, else a negative error code.
 156  *
 157  * Locking status:
 158  *   @page is locked and will be unlocked.
 159  */
 160 static int
 161 vxfs_readpage(struct file *file, struct page *page)
 162 {
 163         return block_read_full_page(page, vxfs_getblk);
 164 }
 165
 166 /**
 167  * vxfs_bmap - perform logical to physical block mapping
 168  * @mapping:    logical to physical mapping to use
 169  * @block:      logical block (relative to @mapping).
 170  *
 171  * Description:
 172  *   Vxfs_bmap find out the corresponding phsical block to the
 173  *   @mapping, @block pair.
 174  *
 175  * Returns:
 176  *   Physical block number on success, else Zero.
 177  *
 178  * Locking status:
 179  *   We are under the bkl.
 180  */
 181 static sector_t
 182 vxfs_bmap(struct address_space *mapping, sector_t block)
 183 {
 184         return generic_block_bmap(mapping, block, vxfs_getblk);
 185 }