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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/blkdev.h>
13#include "ext2.h"
14#include "xip.h"
15
16static inline int
17__inode_direct_access(struct inode *inode, sector_t block,
18 void **kaddr, unsigned long *pfn)
19{
20 struct block_device *bdev = inode->i_sb->s_bdev;
21 const struct block_device_operations *ops = bdev->bd_disk->fops;
22 sector_t sector;
23
24 sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
25
26 BUG_ON(!ops->direct_access);
27 return ops->direct_access(bdev, sector, kaddr, pfn);
28}
29
30static inline int
31__ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
32 sector_t *result)
33{
34 struct buffer_head tmp;
35 int rc;
36
37 memset(&tmp, 0, sizeof(struct buffer_head));
38 tmp.b_size = 1 << inode->i_blkbits;
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_msg(sb, KERN_WARNING,
72 "warning: ignoring xip option - "
73 "not supported by bdev");
74 }
75}
76
77int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
78 void **kmem, unsigned long *pfn)
79{
80 int rc;
81 sector_t block;
82
83 /* first, retrieve the sector number */
84 rc = __ext2_get_block(mapping->host, pgoff, create, &block);
85 if (rc)
86 return rc;
87
88 /* retrieve address of the target data */
89 rc = __inode_direct_access(mapping->host, block, kmem, pfn);
90 return rc;
91}