LXR linux/fs/ext2/xip.c

   1/*
   2 *  linux/fs/ext2/xip.c
   3 *
   4 * Copyright (C) 2005 IBM Corporation
   5 * Author: Carsten Otte (cotte@de.ibm.com)
   6 */
   7
   8#include <linux/mm.h>
   9#include <linux/fs.h>
  10#include <linux/genhd.h>
  11#include <linux/buffer_head.h>
  12#include <linux/ext2_fs_sb.h>
  13#include <linux/ext2_fs.h>
  14#include "ext2.h"
  15#include "xip.h"
  16
  17static inline int
  18__inode_direct_access(struct inode *inode, sector_t block,
  19                      void **kaddr, unsigned long *pfn)
  20{
  21        struct block_device *bdev = inode->i_sb->s_bdev;
  22        struct block_device_operations *ops = bdev->bd_disk->fops;
  23        sector_t sector;
  24
  25        sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
  26
  27        BUG_ON(!ops->direct_access);
  28        return ops->direct_access(bdev, sector, kaddr, pfn);
  29}
  30
  31static inline int
  32__ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
  33                   sector_t *result)
  34{
  35        struct buffer_head tmp;
  36        int rc;
  37
  38        memset(&tmp, 0, sizeof(struct buffer_head));
  39        rc = ext2_get_block(inode, pgoff, &tmp, create);
  40        *result = tmp.b_blocknr;
  41
  42        /* did we get a sparse block (hole in the file)? */
  43        if (!tmp.b_blocknr && !rc) {
  44                BUG_ON(create);
  45                rc = -ENODATA;
  46        }
  47
  48        return rc;
  49}
  50
  51int
  52ext2_clear_xip_target(struct inode *inode, sector_t block)
  53{
  54        void *kaddr;
  55        unsigned long pfn;
  56        int rc;
  57
  58        rc = __inode_direct_access(inode, block, &kaddr, &pfn);
  59        if (!rc)
  60                clear_page(kaddr);
  61        return rc;
  62}
  63
  64void ext2_xip_verify_sb(struct super_block *sb)
  65{
  66        struct ext2_sb_info *sbi = EXT2_SB(sb);
  67
  68        if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
  69            !sb->s_bdev->bd_disk->fops->direct_access) {
  70                sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
  71                ext2_warning(sb, __func__,
  72                             "ignoring xip option - not supported by bdev");
  73        }
  74}
  75
  76int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
  77                                void **kmem, unsigned long *pfn)
  78{
  79        int rc;
  80        sector_t block;
  81
  82        /* first, retrieve the sector number */
  83        rc = __ext2_get_block(mapping->host, pgoff, create, &block);
  84        if (rc)
  85                return rc;
  86
  87        /* retrieve address of the target data */
  88        rc = __inode_direct_access(mapping->host, block, kmem, pfn);
  89        return rc;
  90}
  91