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