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