return pfn from direct_access, for XIP
[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                       void **kaddr, unsigned long *pfn)
20 {
21         struct block_device *bdev = inode->i_sb->s_bdev;
22         struct block_device_operations *ops = bdev->bd_disk->fops;
23
24         BUG_ON(!ops->direct_access);
25         return ops->direct_access(bdev, sector, kaddr, pfn);
26 }
27
28 static inline int
29 __ext2_get_sector(struct inode *inode, sector_t offset, int create,
30                    sector_t *result)
31 {
32         struct buffer_head tmp;
33         int rc;
34
35         memset(&tmp, 0, sizeof(struct buffer_head));
36         rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,
37                             create);
38         *result = tmp.b_blocknr;
39
40         /* did we get a sparse block (hole in the file)? */
41         if (!tmp.b_blocknr && !rc) {
42                 BUG_ON(create);
43                 rc = -ENODATA;
44         }
45
46         return rc;
47 }
48
49 int
50 ext2_clear_xip_target(struct inode *inode, int block)
51 {
52         sector_t sector = block * (PAGE_SIZE/512);
53         void *kaddr;
54         unsigned long pfn;
55         int rc;
56
57         rc = __inode_direct_access(inode, sector, &kaddr, &pfn);
58         if (!rc)
59                 clear_page(kaddr);
60         return rc;
61 }
62
63 void 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_warning(sb, __FUNCTION__,
71                              "ignoring xip option - not supported by bdev");
72         }
73 }
74
75 struct page *
76 ext2_get_xip_page(struct address_space *mapping, sector_t offset,
77                    int create)
78 {
79         int rc;
80         void *kaddr;
81         unsigned long pfn;
82         sector_t sector;
83
84         /* first, retrieve the sector number */
85         rc = __ext2_get_sector(mapping->host, offset, create, &sector);
86         if (rc)
87                 goto error;
88
89         /* retrieve address of the target data */
90         rc = __inode_direct_access
91                 (mapping->host, sector * (PAGE_SIZE/512), &kaddr, &pfn);
92         if (!rc)
93                 return pfn_to_page(pfn);
94
95  error:
96         return ERR_PTR(rc);
97 }