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 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_cache_page(mapping, n,
  75                         (filler_t*)mapping->a_ops->readpage, NULL);
  76
  77         if (!IS_ERR(pp)) {
  78                 wait_on_page_locked(pp);
  79                 kmap(pp);
  80                 if (!PageUptodate(pp))
  81                         goto fail;
  82                 /** if (!PageChecked(pp)) **/
  83                         /** vxfs_check_page(pp); **/
  84                 if (PageError(pp))
  85                         goto fail;
  86         }
  87
  88         return (pp);
  89
  90 fail:
  91         vxfs_put_page(pp);
  92         return ERR_PTR(-EIO);
  93 }
  94
  95 /**
  96  * vxfs_bread - read buffer for a give inode,block tuple
  97  * @ip:         inode
  98  * @block:      logical block
  99  *
 100  * Description:
 101  *   The vxfs_bread function reads block no @block  of
 102  *   @ip into the buffercache.
 103  *
 104  * Returns:
 105  *   The resulting &struct buffer_head.
 106  */
 107 struct buffer_head *
 108 vxfs_bread(struct inode *ip, int block)
 109 {
 110         struct buffer_head      *bp;
 111         daddr_t                 pblock;
 112
 113         pblock = vxfs_bmap1(ip, block);
 114         bp = sb_bread(ip->i_sb, pblock);
 115
 116         return (bp);
 117 }
 118
 119 /**
 120  * vxfs_get_block - locate buffer for given inode,block tuple
 121  * @ip:         inode
 122  * @iblock:     logical block
 123  * @bp:         buffer skeleton
 124  * @create:     %TRUE if blocks may be newly allocated.
 125  *
 126  * Description:
 127  *   The vxfs_get_block function fills @bp with the right physical
 128  *   block and device number to perform a lowlevel read/write on
 129  *   it.
 130  *
 131  * Returns:
 132  *   Zero on success, else a negativ error code (-EIO).
 133  */
 134 static int
 135 vxfs_getblk(struct inode *ip, sector_t iblock,
 136             struct buffer_head *bp, int create)
 137 {
 138         daddr_t                 pblock;
 139
 140         pblock = vxfs_bmap1(ip, iblock);
 141         if (pblock != 0) {
 142                 map_bh(bp, ip->i_sb, pblock);
 143                 return 0;
 144         }
 145
 146         return -EIO;
 147 }
 148
 149 /**
 150  * vxfs_readpage - read one page synchronously into the pagecache
 151  * @file:       file context (unused)
 152  * @page:       page frame to fill in.
 153  *
 154  * Description:
 155  *   The vxfs_readpage routine reads @page synchronously into the
 156  *   pagecache.
 157  *
 158  * Returns:
 159  *   Zero on success, else a negative error code.
 160  *
 161  * Locking status:
 162  *   @page is locked and will be unlocked.
 163  */
 164 static int
 165 vxfs_readpage(struct file *file, struct page *page)
 166 {
 167         return block_read_full_page(page, vxfs_getblk);
 168 }
 169
 170 /**
 171  * vxfs_bmap - perform logical to physical block mapping
 172  * @mapping:    logical to physical mapping to use
 173  * @block:      logical block (relative to @mapping).
 174  *
 175  * Description:
 176  *   Vxfs_bmap find out the corresponding phsical block to the
 177  *   @mapping, @block pair.
 178  *
 179  * Returns:
 180  *   Physical block number on success, else Zero.
 181  *
 182  * Locking status:
 183  *   We are under the bkl.
 184  */
 185 static sector_t
 186 vxfs_bmap(struct address_space *mapping, sector_t block)
 187 {
 188         return generic_block_bmap(mapping, block, vxfs_getblk);
 189 }