0aa5ac159c0940947925425c06d2a688c0bb05bc
[linux-3.10.git] / 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
17 static inline int
18 __inode_direct_access(struct inode *inode, sector_t sector,
19                       unsigned long *data)
20 {
21         BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
22         return inode->i_sb->s_bdev->bd_disk->fops
23                 ->direct_access(inode->i_sb->s_bdev,sector,data);
24 }
25
26 static inline int
27 __ext2_get_sector(struct inode *inode, sector_t offset, int create,
28                    sector_t *result)
29 {
30         struct buffer_head tmp;
31         int rc;
32
33         memset(&tmp, 0, sizeof(struct buffer_head));
34         rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,
35                             create);
36         *result = tmp.b_blocknr;
37
38         /* did we get a sparse block (hole in the file)? */
39         if (!(*result)) {
40                 BUG_ON(create);
41                 rc = -ENODATA;
42         }
43
44         return rc;
45 }
46
47 int
48 ext2_clear_xip_target(struct inode *inode, int block)
49 {
50         sector_t sector = block * (PAGE_SIZE/512);
51         unsigned long data;
52         int rc;
53
54         rc = __inode_direct_access(inode, sector, &data);
55         if (!rc)
56                 clear_page((void*)data);
57         return rc;
58 }
59
60 void ext2_xip_verify_sb(struct super_block *sb)
61 {
62         struct ext2_sb_info *sbi = EXT2_SB(sb);
63
64         if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
65             !sb->s_bdev->bd_disk->fops->direct_access) {
66                 sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
67                 ext2_warning(sb, __FUNCTION__,
68                              "ignoring xip option - not supported by bdev");
69         }
70 }
71
72 struct page *
73 ext2_get_xip_page(struct address_space *mapping, sector_t offset,
74                    int create)
75 {
76         int rc;
77         unsigned long data;
78         sector_t sector;
79
80         /* first, retrieve the sector number */
81         rc = __ext2_get_sector(mapping->host, offset, create, &sector);
82         if (rc)
83                 goto error;
84
85         /* retrieve address of the target data */
86         rc = __inode_direct_access
87                 (mapping->host, sector * (PAGE_SIZE/512), &data);
88         if (!rc)
89                 return virt_to_page(data);
90
91  error:
92         return ERR_PTR(rc);
93 }