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 <linux/blkdev.h>
15#include "ext2.h"
16#include "xip.h"
17
18static inline int
19__inode_direct_access(struct inode *inode, sector_t block,
20		      void **kaddr, unsigned long *pfn)
21{
22	struct block_device *bdev = inode->i_sb->s_bdev;
23	const struct block_device_operations *ops = bdev->bd_disk->fops;
24	sector_t sector;
25
26	sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
27
28	BUG_ON(!ops->direct_access);
29	return ops->direct_access(bdev, sector, kaddr, pfn);
30}
31
32static inline int
33__ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
34		   sector_t *result)
35{
36	struct buffer_head tmp;
37	int rc;
38
39	memset(&tmp, 0, sizeof(struct buffer_head));
40	rc = ext2_get_block(inode, pgoff, &tmp, create);
41	*result = tmp.b_blocknr;
42
43	/* did we get a sparse block (hole in the file)? */
44	if (!tmp.b_blocknr && !rc) {
45		BUG_ON(create);
46		rc = -ENODATA;
47	}
48
49	return rc;
50}
51
52int
53ext2_clear_xip_target(struct inode *inode, sector_t block)
54{
55	void *kaddr;
56	unsigned long pfn;
57	int rc;
58
59	rc = __inode_direct_access(inode, block, &kaddr, &pfn);
60	if (!rc)
61		clear_page(kaddr);
62	return rc;
63}
64
65void ext2_xip_verify_sb(struct super_block *sb)
66{
67	struct ext2_sb_info *sbi = EXT2_SB(sb);
68
69	if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
70	    !sb->s_bdev->bd_disk->fops->direct_access) {
71		sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
72		ext2_msg(sb, KERN_WARNING,
73			     "warning: ignoring xip option - "
74			     "not supported by bdev");
75	}
76}
77
78int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
79				void **kmem, unsigned long *pfn)
80{
81	int rc;
82	sector_t block;
83
84	/* first, retrieve the sector number */
85	rc = __ext2_get_block(mapping->host, pgoff, create, &block);
86	if (rc)
87		return rc;
88
89	/* retrieve address of the target data */
90	rc = __inode_direct_access(mapping->host, block, kmem, pfn);
91	return rc;
92}
93