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   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
  17 static inline int
  18 __inode_direct_access(struct inode *inode, sector_t sector, unsigned long *data) {
  19         BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
  20         return inode->i_sb->s_bdev->bd_disk->fops
  21                 ->direct_access(inode->i_sb->s_bdev,sector,data);
  22 }
  23
  24 int
  25 ext2_clear_xip_target(struct inode *inode, int block) {
  26         sector_t sector = block*(PAGE_SIZE/512);
  27         unsigned long data;
  28         int rc;
  29
  30         rc = __inode_direct_access(inode, sector, &data);
  31         if (rc)
  32                 return rc;
  33         clear_page((void*)data);
  34         return 0;
  35 }
  36
  37 void ext2_xip_verify_sb(struct super_block *sb)
  38 {
  39         struct ext2_sb_info *sbi = EXT2_SB(sb);
  40
  41         if ((sbi->s_mount_opt & EXT2_MOUNT_XIP)) {
  42                 if ((sb->s_bdev == NULL) ||
  43                         sb->s_bdev->bd_disk == NULL ||
  44                         sb->s_bdev->bd_disk->fops == NULL ||
  45                         sb->s_bdev->bd_disk->fops->direct_access == NULL) {
  46                         sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
  47                         ext2_warning(sb, __FUNCTION__,
  48                                 "ignoring xip option - not supported by bdev");
  49                 }
  50         }
  51 }
  52
  53 struct page*
  54 ext2_get_xip_page(struct address_space *mapping, sector_t blockno,
  55                    int create)
  56 {
  57         int rc;
  58         unsigned long data;
  59         struct buffer_head tmp;
  60
  61         tmp.b_state = 0;
  62         tmp.b_blocknr = 0;
  63         rc = ext2_get_block(mapping->host, blockno/(PAGE_SIZE/512) , &tmp,
  64                                 create);
  65         if (rc)
  66                 return ERR_PTR(rc);
  67         if (tmp.b_blocknr == 0) {
  68                 /* SPARSE block */
  69                 BUG_ON(create);
  70                 return ERR_PTR(-ENODATA);
  71         }
  72
  73         rc = __inode_direct_access
  74                 (mapping->host,tmp.b_blocknr*(PAGE_SIZE/512) ,&data);
  75         if (rc)
  76                 return ERR_PTR(rc);
  77
  78         SetPageUptodate(virt_to_page(data));
  79         return virt_to_page(data);
  80 }