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	rc = ext2_get_block(inode, pgoff, &tmp, create);
39	*result = tmp.b_blocknr;
40
41	/* did we get a sparse block (hole in the file)? */
42	if (!tmp.b_blocknr && !rc) {
43		BUG_ON(create);
44		rc = -ENODATA;
45	}
46
47	return rc;
48}
49
50int
51ext2_clear_xip_target(struct inode *inode, sector_t block)
52{
53	void *kaddr;
54	unsigned long pfn;
55	int rc;
56
57	rc = __inode_direct_access(inode, block, &kaddr, &pfn);
58	if (!rc)
59		clear_page(kaddr);
60	return rc;
61}
62
63void ext2_xip_verify_sb(struct super_block *sb)
64{
65	struct ext2_sb_info *sbi = EXT2_SB(sb);
66
67	if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
68	    !sb->s_bdev->bd_disk->fops->direct_access) {
69		sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
70		ext2_msg(sb, KERN_WARNING,
71			     "warning: ignoring xip option - "
72			     "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}